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1,159 results on '"Luhmann, A"'

1. Temporal Evolution of the Solar-Wind Electron Core Density at Solar Minimum by Correlating SWEA Measurements from STEREO A and B

Author

Opitz, A., Sauvaud, J.-A., Fedorov, A., Wurz, P., Luhmann, J. G., Lavraud, B., Russell, C. T., Kellogg, P., Briand, C., Henri, P., Malaspina, D. M., Louarn, P., Curtis, D. W., Penou, E., Karrer, R., Galvin, A. B., Larson, D. E., Dandouras, I., and Schroeder, P.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics and Astroparticles
Abstract

The twin STEREO spacecraft provide a unique tool to study the temporal evolution of the solar-wind properties in the ecliptic since their longitudinal separation increases with time. We derive the characteristic temporal variations at ∼ 1 AU between two different plasma parcels ejected from the same solar source by excluding the spatial variations from our datasets. As part of the onboard IMPACT instrument suite, the SWEA electron experiment provides the solar-wind electron core density at two different heliospheric vantage points. We analyze these density datasets between March and August 2007 and find typical solar minimum conditions. After adjusting for the theoretical time lag between the two spacecraft, we compare the two density datasets. We find that their correlation decreases as the time difference increases between two ejections. The correlation coefficient is about 0.80 for a time lag of a half day and 0.65 for two days. These correlation coefficients from the electron core density are somewhat lower than the ones from the proton bulk velocity obtained in an earlier study, though they are still high enough to consider the solar wind as persistent after two days. These quantitative results reflect the variability of the solar-wind properties in space and time, and they might serve as input for solar-wind models.

Published
2010

2. Sequential Coronal Mass Ejections from AR8038 in May 1997

Author

Li, Y., Lynch, B. J., Welsch, B. T., Stenborg, G. A., Luhmann, J. G., Fisher, G. H., Liu, Y., and Nightingale, R. W.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics and Astroparticles, Coronal mass ejection, EUV dimming, Flare, Magnetic field, Sigmoid
Abstract

Three homologous coronal mass ejections (CMEs) occurred on 5, 12 and 16 May 1997 from the single magnetic polarity inversion line (PIL) of AR8038. The three events together provide STEREO-like quadrature views of the 12 May 1997 CME and EIT double dimming. The recurrent CMEs with the nearly identical post-CME potential state and the ‘sigmoid to arcade to sigmoid’ transformations indicate a repeatable store – release – restore process of the free energy. How was the free magnetic energy re-introduced to the potential state corona after each release in this decaying active region? Making use of the known time interval bounded by the adjacent homologous CMEs, we made the following measures. The unsigned magnetic flux of AR8038, ΦAR, decreased by approximately 18% during 66 h, while the unsigned flux, ΦPIL, in a Gaussian-weighted PIL-region containing the flare site increased by about 50% during 36 hrs prior to the C1.3 flare on 12 May 1997. The significant increase of ΦPIL demonstrates the magnetic gradient increase and the build-up of free energy in the PIL-region during the time leading to the eruption. Fourier local correlation tracking (FLCT) flow speed in AR8038 ranges from 0 to 292.8 m s−1 with a mean value of 63.2 m s−1. The flow field contains a persistent converging flow towards the flaring PIL and an effective shear flow distributed in the AR. Minor angular motions were found. An integrated proxy Poynting flux S h estimates the energy input to the corona to be on the order of 1.15×1032 erg during the 66 hrs before the C1.3 flare. It suggests that sufficient energy for a flare/CME can be introduced to the corona on the order of several days by the flows deduced from photospheric magnetic field motions in this small decaying active region.

Published
2010

3. Organization of Energetic Particles by the Solar Wind Structure During the Declining to Minimum Phase of Solar Cycle 23

Author

Lee, C. O., Luhmann, J. G., Pater, I., Mason, G. M., Haggerty, D., Richardson, I. G., Cane, H. V., Jian, L. K., Russell, C. T., and Desai, M. I.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics and Astroparticles, Energetic particles, Solar wind, Solar activity cycle, Magnetic fields: interplanetary
Abstract

We investigate the organization of the low energy energetic particles (≤1 MeV) by solar wind structures, in particular corotating interaction regions (CIRs) and shocks driven by interplanetary coronal mass ejections, during the declining-to-minimum phase of Solar Cycle 23 from Carrington rotation 1999 to 2088 (January 2003 to October 2009). Because CIR-associated particles are very prominent during the solar minimum, the unusually long solar minimum period of this current cycle provides an opportunity to examine the overall organization of CIR energetic particles for a much longer period than during any other minimum since the dawn of the Space Age. We find that the particle enhancements associated with CIRs this minimum period recurred for many solar rotations, up to 30 at times, due to several high-speed solar wind streams that persisted. However, very few significant CIR-related energetic particle enhancements were observed towards the end of our study period, reflecting the overall weak high-speed streams that occurred at this time. We also contrast the solar minimum observations with the declining phase when a number of solar energetic particle events occurred, producing a mixed particle population. In addition, we compare the observations from this minimum period with those from the previous solar cycle. One of the main differences we find is the shorter recurrence rate of the high-speed solar wind streams (∼10 solar rotations) and the related CIR energetic particle enhancements for the Solar Cycle 22 minimum period. Overall our study provides insight into the coexistence of different populations of energetic particles, as well as an overview of the large-scale organization of the energetic particle populations approaching the beginning of Solar Cycle 24.

Published
2010

4. Multi-Spacecraft Observations: Stream Interactions and Associated Structures

Author

Jian, L. K., Russell, C. T., Luhmann, J. G., Galvin, A. B., and MacNeice, P. J.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics and Astroparticles, Solar wind, Stream interaction, Shock, Multi-spacecraft observation
Abstract

The stream interaction region (SIR), formed when a fast stream overtakes a preceding slow stream, is the predominant large-scale solar wind structure at this early phase of the STEREO mission. Using multi-spacecraft observations from STEREO A and B, ACE, Wind, and Ulysses in 2007, we analyze three stream interaction events in depth in May, August, and November of 2007, respectively, when the spacecraft had quite different spatial separations. We attempt to determine the causes of the differences in the SIR properties, whether they are spatial or temporal variations, and also to examine the steepening or widening of the SIR during its radial evolution. The presence and characteristics of associated shocks, the relation to the heliospheric current sheet, and other structures are also studied.

Published
2009

5. Small Solar Wind Transients and Their Connection to the Large-Scale Coronal Structure

Author

Kilpua, E. K., Luhmann, J. G., Gosling, J., Li, Y., Elliott, H., Russell, C. T., Jian, L., Galvin, A. B., Larson, D., Schroeder, P., Simunac, K., and Petrie, G.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics
Abstract

It has been realized for some time that the slow solar wind with its embedded heliospheric current sheet often exhibits complex features suggesting at least partially transient origin. In this paper we investigate the structure of the slow solar wind using the observations by the Wind and STEREO spacecraft during two Carrington rotations (2054 and 2055). These occur at the time of minimum solar activity when the interplanetary medium is dominated by recurrent high-speed streams and large-scale interplanetary coronal mass ejections (ICMEs) are rare. However, the signatures of transients with small scale-sizes and/or low magnetic field strength (comparable with the typical solar wind value, ∼ 5 nT) are frequently found in the slow solar wind at these times. These events do not exhibit significant speed gradients across the structure, but instead appear to move with the surrounding flow. Source mapping using models based on GONG magnetograms suggests that these transients come from the vicinity of coronal source surface sector boundaries. In situ they are correspondingly observed in the vicinity of high density structures where the dominant electron heat flux reverses its flow polarity. These weak transients might be indications of dynamical changes at the coronal hole boundaries or at the edges of the helmet streamer belt previously reported in coronagraph observations. Our analysis supports the idea that even at solar minimum, a considerable fraction of the slow solar wind is transient in nature.

Published
2009

6. Effects of the Weak Polar Fields of Solar Cycle 23: Investigation Using OMNI for the STEREO Mission Period

Author

Lee, C. O., Luhmann, J. G., Zhao, X. P., Liu, Y., Riley, P., Arge, C. N., Russell, C. T., and Pater, I.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics, STEREO mission, Solar wind, Solar cycle, models, Solar cycle, observations, Magnetic fields, observations, Magnetic fields, interplanetary
Abstract

The current solar cycle minimum seems to have unusual properties that appear to be related to weak solar polar magnetic fields. We investigate signatures of this unusual polar field in the ecliptic near-Earth interplanetary magnetic field (IMF) for the STEREO period of observations. Using 1 AU OMNI data, we find that for the current solar cycle declining phase to minimum period the peak of the distribution for the values of the ecliptic IMF magnitude is lower compared to a similar phase of the previous solar cycle. We investigate the sources of these weak fields. Our results suggest that they are related to the solar wind stream structure, which is enhanced by the weak polar fields. The direct role of the solar field is therefore complicated by this effect, which redistributes the solar magnetic flux at 1 AU nonuniformly at low to mid heliolatitudes.

Published
2009

7. A Multispacecraft Analysis of a Small-Scale Transient Entrained by Solar Wind Streams

Author

Rouillard, A. P., Savani, N. P., Davies, J. A., Lavraud, B., Forsyth, R. J., Morley, S. K., Opitz, A., Sheeley, N. R., Burlaga, L. F., Sauvaud, J.-A., Simunac, K. D., Luhmann, J. G., Galvin, A. B., Crothers, S. R., Davis, C. J., Harrison, R. A., Lockwood, M., Eyles, C. J., Bewsher, D., and Brown, D. S.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics, Sun: magnetic field, Sun: corotating interaction regions, Interplanetary medium: coronal mass ejection
Abstract

The images taken by the Heliospheric Imagers (HIs), part of the SECCHI imaging package onboard the pair of STEREO spacecraft, provide information on the radial and latitudinal evolution of the plasma compressed inside corotating interaction regions (CIRs). A plasma density wave imaged by the HI instrument onboard STEREO-B was found to propagate towards STEREO-A, enabling a comparison between simultaneous remote-sensing and in situ observations of its structure to be performed. In situ measurements made by STEREO-A show that the plasma density wave is associated with the passage of a CIR. The magnetic field compressed after the CIR stream interface (SI) is found to have a planar distribution. Minimum variance analysis of the magnetic field vectors shows that the SI is inclined at 54° to the orbital plane of the STEREO-A spacecraft. This inclination of the CIR SI is comparable to the inclination of the associated plasma density wave observed by HI. A small-scale magnetic cloud with a flux rope topology and radial extent of 0.08 AU is also embedded prior to the SI. The pitch-angle distribution of suprathermal electrons measured by the STEREO-A SWEA instrument shows that an open magnetic field topology in the cloud replaced the heliospheric current sheet locally. These observations confirm that HI observes CIRs in difference images when a small-scale transient is caught up in the compression region.

Published
2009

8. Solar Wind Sources in the Late Declining Phase of Cycle 23: Effects of the Weak Solar Polar Field on High Speed Streams

Author

Luhmann, J. G., Lee, C. O., Li, Yan, Arge, C. N., Galvin, A. B., Simunac, K., Russell, C. T., Howard, R. A., and Petrie, G.

Subjects
Physics, Extraterrestrial Physics, Space Sciences, Meteorology/Climatology, Astrophysics, STEREO mission, Solar wind, Solar cycle, Solar magnetic field, PFSS model
Abstract

The declining phases of solar cycles are known for their high speed solar wind streams that dominate the geomagnetic responses during this period. Outstanding questions about these streams, which can provide the fastest winds of the solar cycle, concern their solar origins, persistence, and predictability. The declining phase of cycle 23 has lasted significantly longer than the corresponding phases of the previous two cycles. Solar magnetograph observations suggest that the solar polar magnetic field is also ∼ 2 – 3 times weaker. The launch of STEREO in late 2006 provided additional incentive to examine the origins of what is observed at 1 AU in the recent cycle, with the OMNI data base at the NSSDC available as an Earth/L1 baseline for comparisons. Here we focus on the year 2007 when the solar corona exhibited large, long-lived mid-to-low latitude coronal holes and polar hole extensions observed by both SOHO and STEREO imagers. STEREO provides in situ measurements consistent with rigidly corotating solar wind stream structure at up to ∼ 45° heliolongitude separation by late 2007. This stability justifies the use of magnetogram-based steady 3D solar wind models to map the observed high speed winds back to their coronal sources. We apply the WSA solar wind model currently running at the NOAA Space Weather Prediction Center with the expectation that it should perform its best at this quiet time. The model comparisons confirm the origins of the observed high speed streams expected from the solar images, but also reveal uncertainties in the solar wind source mapping associated with this cycle’s weaker solar polar fields. Overall, the results illustrate the importance of having accurate polar fields in synoptic maps used in solar wind forecast models. At the most fundamental level, they demonstrate the control of the solar polar fields over the high speed wind sources, and thus one specific connection between the solar dynamo and the solar wind character.

Published
2009

9. DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy

Author

M. E. Fenstermacher, J. Abbate, S. Abe, T. Abrams, M. Adams, B. Adamson, N. Aiba, T. Akiyama, P. Aleynikov, E. Allen, S. Allen, H. Anand, J. Anderson, Y. Andrew, T. Andrews, D. Appelt, R. Arbon, N. Ashikawa, A. Ashourvan, M. Aslin, Y. Asnis, M. Austin, D. Ayala, J. Bak, I. Bandyopadhyay, S. Banerjee, K. Barada, L. Bardoczi, J. Barr, E. Bass, D. Battaglia, A. Battey, W. Baumgartner, L. Baylor, J. Beckers, M. Beidler, E. Belli, J. Berkery, T. Bernard, N. Bertelli, M. Beurskens, R. Bielajew, S. Bilgili, B. Biswas, S. Blondel, J. Boedo, I. Bogatu, R. Boivin, T. Bolzonella, M. Bongard, X. Bonnin, P. Bonoli, M. Bonotto, A. Bortolon, S. Bose, N. Bosviel, S. Bouwmans, M. Boyer, W. Boyes, L. Bradley, R. Brambila, D. Brennan, S. Bringuier, L. Brodsky, M. Brookman, J. Brooks, D. Brower, G. Brown, W. Brown, M. Burke, K. Burrell, K. Butler, R. Buttery, I. Bykov, P. Byrne, A. Cacheris, K. Callahan, J. Callen, G. Campbell, J. Candy, J. Canik, P. Cano-Megias, N. Cao, L. Carayannopoulos, T. Carlstrom, W. Carrig, T. Carter, W. Cary, L. Casali, M. Cengher, G. Cespedes Paz, R. Chaban, V. Chan, B. Chapman, I. Char, A. Chattopadhyay, R. Chen, J. Chen, X. Chen, M. Chen, Z. Chen, M. Choi, W. Choi, G. Choi, L. Chousal, C. Chrobak, C. Chrystal, Y. Chung, R. Churchill, M. Cianciosa, J. Clark, M. Clement, S. Coda, A. Cole, C. Collins, W. Conlin, A. Cooper, J. Cordell, B. Coriton, T. Cote, J. Cothran, A. Creely, N. Crocker, C. Crowe, B. Crowley, T. Crowley, D. Cruz-Zabala, D. Cummings, M. Curie, D. Curreli, A. Dal Molin, B. Dannels, A. Dautt-Silva, K. Davda, G. De Tommasi, P. De Vries, G. Degrandchamp, J. Degrassie, D. Demers, S. Denk, S. Depasquale, E. Deshazer, A. Diallo, S. Diem, A. Dimits, R. Ding, S. Ding, W. Ding, T. Do, J. Doane, G. Dong, D. Donovan, J. Drake, W. Drews, J. Drobny, X. Du, H. Du, V. Duarte, D. Dudt, C. Dunn, J. Duran, A. Dvorak, F. Effenberg, N. Eidietis, D. Elder, D. Eldon, R. Ellis, W. Elwasif, D. Ennis, K. Erickson, D. Ernst, M. Fasciana, D. Fedorov, E. Feibush, N. Ferraro, J. Ferreira, J. Ferron, P. Fimognari, D. Finkenthal, R. Fitzpatrick, P. Fox, W. Fox, L. Frassinetti, H. Frerichs, H. Frye, Y. Fu, K. Gage, J. Galdon Quiroga, A. Gallo, Q. Gao, A. Garcia, M. Garcia Munoz, D. Garnier, A. Garofalo, A. Gattuso, D. Geng, K. Gentle, D. Ghosh, L. Giacomelli, S. Gibson, E. Gilson, C. Giroud, F. Glass, A. Glasser, D. Glibert, P. Gohil, R. Gomez, S. Gomez, X. Gong, E. Gonzales, A. Goodman, Y. Gorelov, V. Graber, R. Granetz, T. Gray, D. Green, C. Greenfield, M. Greenwald, B. Grierson, R. Groebner, W. Grosnickle, M. Groth, H. Grunloh, S. Gu, W. Guo, H. Guo, P. Gupta, J. Guterl, W. Guttenfelder, T. Guzman, S. Haar, R. Hager, S. Hahn, M. Halfmoon, T. Hall, K. Hallatschek, F. Halpern, G. Hammett, H. Han, E. Hansen, C. Hansen, M. Hansink, J. Hanson, M. Hanson, G. Hao, A. Harris, R. Harvey, S. Haskey, E. Hassan, A. Hassanein, D. Hatch, R. Hawryluk, W. Hayashi, W. Heidbrink, J. Herfindal, J. Hicok, D. Hill, E. Hinson, C. Holcomb, L. Holland, C. Holland, E. Hollmann, J. Hollocombe, A. Holm, I. Holmes, K. Holtrop, M. Honda, R. Hong, R. Hood, A. Horton, L. Horvath, M. Hosokawa, S. Houshmandyar, N. Howard, E. Howell, D. Hoyt, W. Hu, Y. Hu, Q. Hu, J. Huang, Y. Huang, J. Hughes, T. Human, D. Humphreys, P. Huynh, A. Hyatt, C. Ibanez, L. Ibarra, R. Icasas, K. Ida, V. Igochine, Y. In, S. Inoue, A. Isayama, O. Izacard, V. Izzo, A. Jackson, G. Jacobsen, A. Jaervinen, A. Jalalvand, J. Janhunen, S. Jardin, H. Jarleblad, Y. Jeon, H. Ji, X. Jian, E. Joffrin, A. Johansen, C. Johnson, T. Johnson, C. Jones, I. Joseph, D. Jubas, B. Junge, W. Kalb, R. Kalling, C. Kamath, J. Kang, D. Kaplan, A. Kaptanoglu, S. Kasdorf, J. Kates-Harbeck, P. Kazantzidis, A. Kellman, D. Kellman, C. Kessel, K. Khumthong, E. Kim, H. Kim, J. Kim, S. Kim, K. Kim, C. Kim, W. Kimura, M. King, J. King, J. Kinsey, A. Kirk, B. Kiyan, A. Kleiner, V. Klevarova, R. Knapp, M. Knolker, W. Ko, T. Kobayashi, E. Koch, M. Kochan, B. Koel, M. Koepke, A. Kohn, R. Kolasinski, E. Kolemen, E. Kostadinova, M. Kostuk, G. Kramer, D. Kriete, L. Kripner, S. Kubota, J. Kulchar, K. Kwon, R. La Haye, F. Laggner, H. Lan, R. Lantsov, L. Lao, A. Lasa Esquisabel, C. Lasnier, C. Lau, B. Leard, J. Lee, R. Lee, M. Lee, Y. Lee, C. Lee, S. Lee, M. Lehnen, A. Leonard, E. Leppink, M. Lesher, J. Lestz, J. Leuer, N. Leuthold, X. Li, K. Li, E. Li, G. Li, L. Li, Z. Li, J. Li, Y. Li, Z. Lin, D. Lin, X. Liu, J. Liu, Y. Liu, T. Liu, C. Liu, Z. Liu, D. Liu, A. Liu, A. Loarte-Prieto, L. Lodestro, N. Logan, J. Lohr, B. Lombardo, J. Lore, Q. Luan, T. Luce, T. Luda Di Cortemiglia, N. Luhmann, R. Lunsford, Z. Luo, A. Lvovskiy, B. Lyons, X. Ma, M. Madruga, B. Madsen, C. Maggi, K. Maheshwari, A. Mail, J. Mailloux, R. Maingi, M. Major, M. Makowski, R. Manchanda, C. Marini, A. Marinoni, A. Maris, T. Markovic, L. Marrelli, E. Martin, J. Mateja, G. Matsunaga, R. Maurizio, P. Mauzey, D. Mauzey, G. Mcardle, J. Mcclenaghan, K. Mccollam, C. Mcdevitt, K. Mckay, G. Mckee, A. Mclean, V. Mehta, E. Meier, J. Menard, O. Meneghini, G. Merlo, S. Messer, W. Meyer, C. Michael, C. Michoski, P. Milne, G. Minet, A. Misleh, Y. Mitrishkin, C. Moeller, K. Montes, M. Morales, S. Mordijck, D. Moreau, S. Morosohk, P. Morris, L. Morton, A. Moser, R. Moyer, C. Moynihan, T. Mrazkova, D. Mueller, S. Munaretto, J. Munoz Burgos, C. Murphy, K. Murphy, C. Muscatello, C. Myers, A. Nagy, G. Nandipati, M. Navarro, F. Nave, G. Navratil, R. Nazikian, A. Neff, G. Neilson, T. Neiser, W. Neiswanger, D. Nelson, A. Nelson, F. Nespoli, R. Nguyen, L. Nguyen, X. Nguyen, J. Nichols, M. Nocente, S. Nogami, S. Noraky, N. Norausky, M. Nornberg, R. Nygren, T. Odstrcil, D. Ogas, T. Ogorman, S. Ohdachi, Y. Ohtani, M. Okabayashi, M. Okamoto, L. Olavson, E. Olofsson, M. Omullane, R. Oneill, D. Orlov, W. Orvis, T. Osborne, D. Pace, G. Paganini Canal, A. Pajares Martinez, L. Palacios, C. Pan, Q. Pan, R. Pandit, M. Pandya, A. Pankin, Y. Park, J. Park, S. Parker, P. Parks, M. Parsons, B. Patel, C. Pawley, C. Paz-Soldan, W. Peebles, S. Pelton, R. Perillo, C. Petty, Y. Peysson, D. Pierce, A. Pigarov, L. Pigatto, D. Piglowski, S. Pinches, R. Pinsker, P. Piovesan, N. Piper, A. Pironti, R. Pitts, J. Pizzo, U. Plank, M. Podesta, E. Poli, F. Poli, D. Ponce, Z. Popovic, M. Porkolab, G. Porter, C. Powers, S. Powers, R. Prater, Q. Pratt, I. Pusztai, J. Qian, X. Qin, O. Ra, T. Rafiq, T. Raines, R. Raman, J. Rauch, A. Raymond, C. Rea, M. Reich, A. Reiman, S. Reinhold, M. Reinke, R. Reksoatmodjo, Q. Ren, Y. Ren, J. Ren, M. Rensink, J. Renteria, T. Rhodes, J. Rice, R. Roberts, J. Robinson, P. Rodriguez Fernandez, T. Rognlien, A. Rosenthal, S. Rosiello, J. Rost, J. Roveto, W. Rowan, R. Rozenblat, J. Ruane, D. Rudakov, J. Ruiz Ruiz, R. Rupani, S. Saarelma, S. Sabbagh, J. Sachdev, J. Saenz, S. Saib, M. Salewski, A. Salmi, B. Sammuli, C. Samuell, A. Sandorfi, C. Sang, J. Sarff, O. Sauter, K. Schaubel, L. Schmitz, O. Schmitz, J. Schneider, P. Schroeder, K. Schultz, E. Schuster, J. Schwartz, F. Sciortino, F. Scotti, J. Scoville, A. Seltzman, S. Seol, I. Sfiligoi, M. Shafer, S. Sharapov, H. Shen, Z. Sheng, T. Shepard, S. Shi, Y. Shibata, G. Shin, D. Shiraki, R. Shousha, H. Si, P. Simmerling, G. Sinclair, J. Sinha, P. Sinha, G. Sips, T. Sizyuk, C. Skinner, A. Sladkomedova, T. Slendebroek, J. Slief, R. Smirnov, J. Smith, S. Smith, D. Smith, J. Snipes, G. Snoep, A. Snyder, P. Snyder, E. Solano, W. Solomon, J. Song, A. Sontag, V. Soukhanovskii, J. Spendlove, D. Spong, J. Squire, C. Srinivasan, W. Stacey, G. Staebler, L. Stagner, T. Stange, P. Stangeby, R. Stefan, R. Stemprok, D. Stephan, J. Stillerman, T. Stoltzfus-Dueck, W. Stonecipher, S. Storment, E. Strait, D. Su, L. Sugiyama, Y. Sun, P. Sun, Z. Sun, A. Sun, D. Sundstrom, C. Sung, J. Sungcoco, W. Suttrop, Y. Suzuki, T. Suzuki, A. Svyatkovskiy, C. Swee, R. Sweeney, C. Sweetnam, G. Szepesi, M. Takechi, T. Tala, K. Tanaka, X. Tang, S. Tang, Y. Tao, R. Tao, D. Taussig, T. Taylor, K. Teixeira, K. Teo, A. Theodorsen, D. Thomas, K. Thome, A. Thorman, A. Thornton, A. Ti, M. Tillack, N. Timchenko, R. Tinguely, R. Tompkins, J. Tooker, A. Torrezan De Sousa, G. Trevisan, S. Tripathi, A. Trujillo Ochoa, D. Truong, C. Tsui, F. Turco, A. Turnbull, M. Umansky, E. Unterberg, P. Vaezi, P. Vail, J. Valdez, W. Valkis, B. Van Compernolle, J. Van Galen, R. Van Kampen, M. Van Zeeland, G. Verdoolaege, N. Vianello, B. Victor, E. Viezzer, S. Vincena, M. Wade, F. Waelbroeck, J. Wai, T. Wakatsuki, M. Walker, G. Wallace, R. Waltz, W. Wampler, L. Wang, H. Wang, Y. Wang, Z. Wang, G. Wang, S. Ward, M. Watkins, J. Watkins, W. Wehner, Y. Wei, M. Weiland, D. Weisberg, A. Welander, A. White, R. White, S. Wiesen, R. Wilcox, T. Wilks, M. Willensdorfer, H. Wilson, A. Wingen, M. Wolde, M. Wolff, K. Woller, A. Wolz, H. Wong, S. Woodruff, M. Wu, Y. Wu, S. Wukitch, G. Wurden, W. Xiao, R. Xie, Z. Xing, X. Xu, C. Xu, G. Xu, Z. Yan, X. Yang, S. Yang, T. Yokoyama, R. Yoneda, M. Yoshida, K. You, T. Younkin, J. Yu, M. Yu, G. Yu, Q. Yuan, L. Zaidenberg, L. Zakharov, A. Zamengo, S. Zamperini, M. Zarnstorff, E. Zeger, K. Zeller, L. Zeng, M. Zerbini, L. Zhang, X. Zhang, R. Zhang, B. Zhang, J. Zhang, L. Zhao, B. Zhao, Y. Zheng, L. Zheng, B. Zhu, J. Zhu, Y. Zhu, M. Zsutty, M. Zuin, Fenstermacher, M. 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Shousha, R, Si, H, Simmerling, P, Sinclair, G, Sinha, J, Sinha, P, Sips, G, Sizyuk, T, Skinner, C, Sladkomedova, A, Slendebroek, T, Slief, J, Smirnov, R, Smith, J, Smith, S, Smith, D, Snipes, J, Snoep, G, Snyder, A, Snyder, P, Solano, E, Solomon, W, Song, J, Sontag, A, Soukhanovskii, V, Spendlove, J, Spong, D, Squire, J, Srinivasan, C, Stacey, W, Staebler, G, Stagner, L, Stange, T, Stangeby, P, Stefan, R, Stemprok, R, Stephan, D, Stillerman, J, Stoltzfus-Dueck, T, Stonecipher, W, Storment, S, Strait, E, Su, D, Sugiyama, L, Sun, Y, Sun, P, Sun, Z, Sun, A, Sundstrom, D, Sung, C, Sungcoco, J, Suttrop, W, Suzuki, Y, Suzuki, T, Svyatkovskiy, A, Swee, C, Sweeney, R, Sweetnam, C, Szepesi, G, Takechi, M, Tala, T, Tanaka, K, Tang, X, Tang, S, Tao, Y, Tao, R, Taussig, D, Taylor, T, Teixeira, K, Teo, K, Theodorsen, A, Thomas, D, Thome, K, Thorman, A, Thornton, A, Ti, A, Tillack, M, Timchenko, N, Tinguely, R, Tompkins, R, Tooker, J, De Sousa, A, Trevisan, G, Tripathi, S, Ochoa, A, Truong, D, Tsui, C, Turco, F, Turnbull, A, Umansky, M, Unterberg, E, Vaezi, P, Vail, P, Valdez, J, Valkis, W, Van Compernolle, B, Van Galen, J, Van Kampen, R, Van Zeeland, M, Verdoolaege, G, Vianello, N, Victor, B, Viezzer, E, Vincena, S, Wade, M, Waelbroeck, F, Wai, J, Wakatsuki, T, Walker, M, Wallace, G, Waltz, R, Wampler, W, Wang, L, Wang, H, Wang, Y, Wang, Z, Wang, G, Ward, S, Watkins, M, Watkins, J, Wehner, W, Wei, Y, Weiland, M, Weisberg, D, Welander, A, White, A, White, R, Wiesen, S, Wilcox, R, Wilks, T, Willensdorfer, M, Wilson, H, Wingen, A, Wolde, M, Wolff, M, Woller, K, Wolz, A, Wong, H, Woodruff, S, Wu, M, Wu, Y, Wukitch, S, Wurden, G, Xiao, W, Xie, R, Xing, Z, Xu, X, Xu, C, Xu, G, Yan, Z, Yang, X, Yang, S, Yokoyama, T, Yoneda, R, Yoshida, M, You, K, Younkin, T, Yu, J, Yu, M, Yu, G, Yuan, Q, Zaidenberg, L, Zakharov, L, Zamengo, A, Zamperini, S, Zarnstorff, M, Zeger, E, Zeller, K, Zeng, L, Zerbini, M, Zhang, L, Zhang, X, Zhang, R, Zhang, B, Zhang, J, Zhao, L, Zhao, B, Zheng, Y, Zheng, L, Zhu, B, Zhu, J, Zhu, Y, Zsutty, M, Zuin, M, Lawrence Livermore National Laboratory, Princeton Plasma Physics Laboratory, Princeton University, General Atomics, Max-Planck-Institut für Plasmaphysik, Imperial College London, National Institute for Fusion Science, Universidade de São Paulo, University of Texas at Austin, ITER, College of William and Mary, University of California Los Angeles, University of California San Diego, Columbia University, Massachusetts Institute of Technology, Oak Ridge National Laboratory, Eindhoven University of Technology, Oak Ridge Associated Universities, West Virginia University, University of Tennessee, Knoxville, National Research Council of Italy, Stony Brook University, Purdue University, University of Seville, University of Science and Technology of China, Carnegie Mellon University, Institute for Plasma Research, Peking University, University of California Davis, University of California Irvine, Commonwealth Fusion Systems, University of Liverpool, University of Illinois at Urbana-Champaign, University of Milan - Bicocca, Georgia Institute of Technology, Southwestern Institute of Physics, University of Toronto, Auburn University, Polytechnic University of Turin, Universidade Lisboa, Association CCFE, KTH Royal Institute of Technology, San Diego State University, Durham University, Lehigh University, Fusion and Plasma Physics, University of Washington, Department of Applied Physics, Sandia National Laboratories, Ghent University, Technical University of Denmark, CEA, University of Colorado Boulder, Harvard University, National Technical University of Athens, Coventry University, University of Stuttgart, Czech Academy of Sciences, Harvey Mudd College, Seoul National University, Donghua University, University of York, Dalian University of Technology, University of California Berkeley, Los Alamos National Laboratory, United States Department of Energy, University of British Columbia, Pacific Northwest National Laboratory, University of Wisconsin, Michigan State University, University of Strathclyde, Pennsylvania State University, Rensselaer Polytechnic Institute, University of Southern California, Chalmers University of Technology, University of Virginia, University of Naples Federico II, University of Oxford, VTT Technical Research Centre of Finland, National Institute of Technology, University of Connecticut, DIFFER, CIEMAT, Hanyang University, Brigham Young University, UiT The Arctic University of Norway, Australian National University, Russian Research Centre Kurchatov Institute, Forschungszentrum Jülich, Zhejiang University, The University of Tokyo, University of Michigan, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, Aalto-yliopisto, Aalto University, DIII-D Team, Complex Ionized Media, Elementary Processes in Gas Discharges, Applied Physics and Science Education, Science and Technology of Nuclear Fusion, and Control Systems Technology

Subjects
Nuclear and High Energy Physics, Tokamak, Technology and Engineering, DIII-D, Nuclear engineering, TOKAMAKS, MITIGATION, law.invention, Plasma physics, mitigation, law, plasma physic, tokamak, Physics, Core-edge integration, Basis (linear algebra), plasma physics, core-edge integration, scenarios, Fusion power, Condensed Matter Physics, SCENARIOS, fusion energy, Fusion energy
Abstract

Funding Information: This material is based upon work supported by the US Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Awards DE-FC02-04ER54698 and DE-AC52-07NA27344. Publisher Copyright: © 2022 IAEA, Vienna. DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.

Published
2022
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10. Development and application of radar reflectometer using micro to infrared waves

Author

A. Mase, Y. Kogi, D. Kuwahara, Y. Nagayama, N. Ito, T. Maruyama, H. Ikezi, X. Wang, M. Inutake, T. Tokuzawa, J. Kohagura, M. Yoshikawa, S. Shinohara, A. Suzuki, F. Sakai, M. Yamashika, B. J. Tobias, C. Muscatello, X. Ren, M. Chen, C. W. Domier, and N. C. Luhmann

Subjects
Electromagnetic waves, radar reflectometry, imaging, plasma, biomedical measurement, remote sensing, Physics, QC1-999
Abstract

Progress in microwave and millimeter-wave technologies has made possible advanced diagnostics for application to various fields, including radio astronomy, alien substance detection, plasma diagnostics, airborne and space-borne imaging radars called as synthetic aperture radars, and living body measurements. Transmission, reflection, scattering, and radiation processes of electromagnetic waves are utilized as diagnostic principles. The diagnostics are classified as active and passive systems. Specifically, active radar reflectometry has become of importance in various applications due to the possibility of high localization and accessibility of the measurements as well as the non-invasive nature of the systems. In this paper, recent development and application of radar reflectometers are described. The key words are profile reflectometry, fluctuation reflectometry, imaging radar (optics imaging and synthetic aperture imaging), and radio-optics fusion technology in order to improve the spatial resolution.

Published
2018
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11. Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development

Author

U. Stroth, D. Aguiam, E. Alessi, C. Angioni, N. Arden, R. Arredondo Parra, V. Artigues, O. Asunta, M. Balden, V. Bandaru, A. Banon-Navarro, K. Behler, A. Bergmann, M. Bergmann, J. Bernardo, M. Bernert, A. Biancalani, R. Bielajew, R. Bilato, G. Birkenmeier, T. Blanken, V. Bobkov, A. Bock, T. Body, T. Bolzonella, N. Bonanomi, A. Bortolon, B. Böswirth, C. Bottereau, A. Bottino, H. van den Brand, M. Brenzke, S. Brezinsek, D. Brida, F. Brochard, C. Bruhn, J. Buchanan, A. Buhler, A. Burckhart, Y. Camenen, B. Cannas, P. Cano Megias, D. Carlton, M. Carr, P. Carvalho, C. Castaldo, M. Cavedon, C. Cazzaniga, C. Challis, A. Chankin, C. Cianfarani, F. Clairet, S. Coda, R. Coelho, J.W. Coenen, L. Colas, G. Conway, S. Costea, D. Coster, T. Cote, A.J. Creely, G. Croci, D.J. Cruz Zabala, G. Cseh, A. Czarnecka, I. Cziegler, O. D’Arcangelo, A. Dal Molin, P. David, C. Day, M. de Baar, P. de Marné, R. Delogu, S. Denk, P. Denner, A. Di Siena, J.J. Dominguez Palacios Durán, D. Dunai, A. Drenik, M. Dreval, R. Drube, M. Dunne, B.P. Duval, R. Dux, T. Eich, S. Elgeti, A. Encheva, K. Engelhardt, B. Erdös, I. Erofeev, B. Esposito, E. Fable, M. Faitsch, U. Fantz, M. Farnik, H. Faugel, F. Felici, O. Ficker, S. Fietz, A. Figueredo, R. Fischer, O. Ford, L. Frassinetti, M. Fröschle, G. Fuchert, J.C. Fuchs, H. Fünfgelder, S. Futatani, K. Galazka, J. Galdon-Quiroga, D. Gallart Escolà, A. Gallo, Y. Gao, S. Garavaglia, M. Garcia Muñoz, B. Geiger, L. Giannone, S. Gibson, L. Gil, E. Giovannozzi, S. Glöggler, M. Gobbin, J. Gonzalez Martin, T. Goodman, G. Gorini, T. Görler, D. Gradic, G. Granucci, A. Gräter, H. Greuner, M. Griener, M. Groth, A. Gude, L. Guimarais, S. Günter, G. Haas, A.H. Hakola, C. Ham, T. Happel, N. den Harder, G. Harrer, J. Harrison, V. Hauer, T. Hayward-Schneider, B. Heinemann, T. Hellsten, S. Henderson, P. Hennequin, A. Herrmann, E. Heyn, F. Hitzler, J. Hobirk, K. Höfler, J.H. Holm, M. Hölzl, C. Hopf, L. Horvath, T. Höschen, A. Houben, A. Hubbard, A. Huber, K. Hunger, V. Igochine, M. Iliasova, T. Ilkei, K. Insulander Björk, C. Ionita-Schrittwieser, I. Ivanova-Stanik, W. Jacob, N. Jaksic, F. Janky, A. Jansen van Vuuren, A. Jardin, F. Jaulmes, F. Jenko, T. Jensen, E. Joffrin, A. Kallenbach, S. Kálvin, M. Kantor, A. Kappatou, O. Kardaun, J. Karhunen, C.-P. Käsemann, S. Kasilov, A. Kendl, W. Kernbichler, E. Khilkevitch, A. Kirk, S. Kjer Hansen, V. Klevarova, G. Kocsis, M. Koleva, M. Komm, M. Kong, A. Krämer-Flecken, K. Krieger, A. Krivska, O. Kudlacek, T. Kurki-Suonio, B. Kurzan, B. Labit, K. Lackner, F. Laggner, A. Lahtinen, P.T. Lang, P. Lauber, N. Leuthold, L. Li, J. Likonen, O. Linder, B. Lipschultz, Y. Liu, A. Lohs, Z. Lu, T. Luda di Cortemiglia, N.C. Luhmann, T. Lunt, A. Lyssoivan, T. Maceina, J. Madsen, A. Magnanimo, H. Maier, J. Mailloux, R. Maingi, O. Maj, E. Maljaars, P. Manas, A. Mancini, A. Manhard, P. Mantica, M. Mantsinen, P. Manz, M. Maraschek, C. Marchetto, L. Marrelli, P. Martin, A. Martitsch, F. Matos, M. Mayer, M.-L. Mayoral, D. Mazon, P.J. McCarthy, R. McDermott, R. Merkel, A. Merle, D. Meshcheriakov, H. Meyer, D. Milanesio, P. Molina Cabrera, F. Monaco, M. Muraca, F. Nabais, V. Naulin, R. Nazikian, R.D. Nem, A. Nemes-Czopf, G. Neu, R. Neu, A.H. Nielsen, S.K. Nielsen, T. Nishizawa, M. Nocente, J.-M. Noterdaeme, I. Novikau, S. Nowak, M. Oberkofler, R. Ochoukov, J. Olsen, F. Orain, F. Palermo, O. Pan, G. Papp, I. Paradela Perez, A. Pau, G. Pautasso, C. Paz-Soldan, P. Petersson, P. Piovesan, C. Piron, U. Plank, B. Plaum, B. Plöck, V. Plyusnin, G. Pokol, E. Poli, L. Porte, T. Pütterich, M. Ramisch, J. Rasmussen, G. Ratta, S. Ratynskaia, G. Raupp, D. Réfy, M. Reich, F. Reimold, D. Reiser, M. Reisner, D. Reiter, T. Ribeiro, R. Riedl, J. Riesch, D. Rittich, J.F. Rivero Rodriguez, G. Rocchi, P. Rodriguez-Fernandez, M. Rodriguez-Ramos, V. Rohde, G. Ronchi, A. Ross, M. Rott, M. Rubel, D.A. Ryan, F. Ryter, S. Saarelma, M. Salewski, A. Salmi, O. Samoylov, L. Sanchis Sanchez, J. Santos, O. Sauter, G. Schall, K. Schlüter, K. Schmid, O. Schmitz, P.A. Schneider, R. Schrittwieser, M. Schubert, C. Schuster, T. Schwarz-Selinger, J. Schweinzer, E. Seliunin, A. Shabbir, A. Shalpegin, S. Sharapov, U. Sheikh, A. Shevelev, G. Sias, M. Siccinio, B. Sieglin, A. Sigalov, A. Silva, C. Silva, D. Silvagni, J. Simpson, S. Sipilä, E. Smigelskis, A. Snicker, E. Solano, C. Sommariva, C. Sozzi, G. Spizzo, M. Spolaore, A. Stegmeir, M. Stejner, J. Stober, E. Strumberge, G. Suarez Lopez, H.-J. Sun, W. Suttrop, E. Sytova, T. Szepesi, B. Tál, T. Tala, G. Tardini, M. Tardocchi, D. Terranova, M. Teschke, E. Thorén, W. Tierens, D. Told, W. Treutterer, G. Trevisan, E. Trier, M. Tripský, M. Usoltceva, M. Valisa, M. Valovic, M. van Zeeland, F. Vannini, B. Vanovac, P. Varela, S. Varoutis, N. Vianello, J. Vicente, G. Verdoolaege, T. Vierle, E. Viezzer, I. Voitsekhovitch, U. von Toussaint, D. Wagner, X. Wang, M. Weiland, A.E. White, M. Willensdorfer, B. Wiringer, M. Wischmeier, R. Wolf, E. Wolfrum, Q. Yang, Q. Yu, R. Zagórski, I. Zammuto, T. Zehetbauer, W. Zhang, W. Zholobenko, M. Zilker, A. Zito, H. Zohm, S. Zoletnik, the EUROfusion MST1 Team, Max-Planck-Institut für Plasmaphysik [Garching] (IPP), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Aix Marseille Université (AMU), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), EUROfusion MST1 Team, Barcelona Supercomputing Center, Department of Applied Physics, Aalto-yliopisto, Aalto University, Stroth, U, Aguiam, D, Alessi, E, Angioni, C, Arden, N, Parra, R, Artigues, V, Asunta, O, Balden, M, Bandaru, V, Banon-Navarro, A, Behler, K, Bergmann, A, Bergmann, M, Bernardo, J, Bernert, M, Biancalani, A, Bielajew, R, Bilato, R, Birkenmeier, G, Blanken, T, Bobkov, V, Bock, A, Body, T, Bolzonella, T, Bonanomi, N, Bortolon, A, Boswirth, B, Bottereau, C, Bottino, A, Van Den Brand, H, Brenzke, M, Brezinsek, S, Brida, D, Brochard, F, Bruhn, C, Buchanan, J, Buhler, A, Burckhart, A, Camenen, Y, Cannas, B, Megias, P, Carlton, D, Carr, M, Carvalho, P, Castaldo, C, Cavedon, M, Cazzaniga, C, Challis, C, Chankin, A, Cianfarani, C, Clairet, F, Coda, S, Coelho, R, Coenen, J, Colas, L, Conway, G, Costea, S, Coster, D, Cote, T, Creely, A, Croci, G, Zabala, D, Cseh, G, Czarnecka, A, Cziegler, I, D'Arcangelo, O, Molin, A, David, P, Day, C, De Baar, M, De Marne, P, Delogu, R, Denk, S, Denner, P, Di Siena, A, Palacios Duran, J, Dunai, D, Drenik, A, Dreval, M, Drube, R, Dunne, M, Duval, B, Dux, R, Eich, T, Elgeti, S, Encheva, A, Engelhardt, K, Erdos, B, Erofeev, I, Esposito, B, Fable, E, Faitsch, M, Fantz, U, Farnik, M, Faugel, H, Felici, F, Ficker, O, Fietz, S, Figueredo, A, Fischer, R, Ford, O, Frassinetti, L, Froschle, M, Fuchert, G, Fuchs, J, Funfgelder, H, Futatani, S, Galazka, K, Galdon-Quiroga, J, Escola, D, Gallo, A, Gao, Y, Garavaglia, S, Munoz, M, Geiger, B, Giannone, L, Gibson, S, Gil, L, Giovannozzi, E, Gloggler, S, Gobbin, M, Martin, J, Goodman, T, Gorini, G, Gorler, T, Gradic, D, Granucci, G, Grater, A, Greuner, H, Griener, M, Groth, M, Gude, A, Guimarais, L, Gunter, S, Haas, G, Hakola, A, Ham, C, Happel, T, Den Harder, N, Harrer, G, Harrison, J, Hauer, V, Hayward-Schneider, T, Heinemann, B, Hellsten, T, Henderson, S, Hennequin, P, Herrmann, A, Heyn, E, Hitzler, F, Hobirk, J, Hofler, K, Holm, J, Holzl, M, Hopf, C, Horvath, L, Hoschen, T, Houben, A, Hubbard, A, Huber, A, Hunger, K, Igochine, V, Iliasova, M, Ilkei, T, Bjork, K, Ionita-Schrittwieser, C, Ivanova-Stanik, I, Jacob, W, Jaksic, N, Janky, F, Jansen Van Vuuren, A, Jardin, A, Jaulmes, F, Jenko, F, Jensen, T, Joffrin, E, Kallenbach, A, Kalvin, S, Kantor, M, Kappatou, A, Kardaun, O, Karhunen, J, Kasemann, C, Kasilov, S, Kendl, A, Kernbichler, W, Khilkevitch, E, Kirk, A, Hansen, S, Klevarova, V, Kocsis, G, Koleva, M, Komm, M, Kong, M, Kramer-Flecken, A, Krieger, K, Krivska, A, Kudlacek, O, Kurki-Suonio, T, Kurzan, B, Labit, B, Lackner, K, Laggner, F, Lahtinen, A, Lang, P, Lauber, P, Leuthold, N, Li, L, Likonen, J, Linder, O, Lipschultz, B, Liu, Y, Lohs, A, Lu, Z, Luda Di Cortemiglia, T, Luhmann, N, Lunt, T, Lyssoivan, A, Maceina, T, Madsen, J, Magnanimo, A, Maier, H, Mailloux, J, Maingi, R, Maj, O, Maljaars, E, Manas, P, Mancini, A, Manhard, A, Mantica, P, Mantsinen, M, Manz, P, Maraschek, M, Marchetto, C, Marrelli, L, Martin, P, Martitsch, A, Matos, F, Mayer, M, Mayoral, M, Mazon, D, Mccarthy, P, Mcdermott, R, Merkel, R, Merle, A, Meshcheriakov, D, Meyer, H, Milanesio, D, Cabrera, P, Monaco, F, Muraca, M, Nabais, F, Naulin, V, Nazikian, R, Nem, R, Nemes-Czopf, A, Neu, G, Neu, R, Nielsen, A, Nielsen, S, Nishizawa, T, Nocente, M, Noterdaeme, J, Novikau, I, Nowak, S, Oberkofler, M, Ochoukov, R, Olsen, J, Orain, F, Palermo, F, Pan, O, Papp, G, Perez, I, Pau, A, Pautasso, G, Paz-Soldan, C, Petersson, P, Piovesan, P, Piron, C, Plank, U, Plaum, B, Plock, B, Plyusnin, V, Pokol, G, Poli, E, Porte, L, Putterich, T, Ramisch, M, Rasmussen, J, Ratta, G, Ratynskaia, S, Raupp, G, Refy, D, Reich, M, Reimold, F, Reiser, D, Reisner, M, Reiter, D, Ribeiro, T, Riedl, R, Riesch, J, Rittich, D, Rodriguez, J, Rocchi, G, Rodriguez-Fernandez, P, Rodriguez-Ramos, M, Rohde, V, Ronchi, G, Ross, A, Rott, M, Rubel, M, Ryan, D, Ryter, F, Saarelma, S, Salewski, M, Salmi, A, Samoylov, O, Sanchez, L, Santos, J, Sauter, O, Schall, G, Schluter, K, Schmid, K, Schmitz, O, Schneider, P, Schrittwieser, R, Schubert, M, Schuster, C, Schwarz-Selinger, T, Schweinzer, J, Seliunin, E, Shabbir, A, Shalpegin, A, Sharapov, S, Sheikh, U, Shevelev, A, Sias, G, Siccinio, M, Sieglin, B, Sigalov, A, Silva, A, Silva, C, Silvagni, D, Simpson, J, Sipila, S, Smigelskis, E, Snicker, A, Solano, E, Sommariva, C, Sozzi, C, Spizzo, G, Spolaore, M, Stegmeir, A, Stejner, M, Stober, J, Strumberge, E, Lopez, G, Sun, H, Suttrop, W, Sytova, E, Szepesi, T, Tal, B, Tala, T, Tardini, G, Tardocchi, M, Terranova, D, Teschke, M, Thoren, E, Tierens, W, Told, D, Treutterer, W, Trevisan, G, Trier, E, Tripsky, M, Usoltceva, M, Valisa, M, Valovic, M, Van Zeeland, M, Vannini, F, Vanovac, B, Varela, P, Varoutis, S, Vianello, N, Vicente, J, Verdoolaege, G, Vierle, T, Viezzer, E, Voitsekhovitch, I, Von Toussaint, U, Wagner, D, Wang, X, Weiland, M, White, A, Willensdorfer, M, Wiringer, B, Wischmeier, M, Wolf, R, Wolfrum, E, Yang, Q, Yu, Q, Zagorski, R, Zammuto, I, Zehetbauer, T, Zhang, W, Zholobenko, W, Zilker, M, Zito, A, Zohm, H, and Zoletnik, S

Subjects
Nuclear and High Energy Physics, Asdex Upgrade, confinement, ELLM-free discharges, sol, Computer science, Nuclear engineering, ALCATOR C-MOD, UPPER DIVERTOR, ASDEX Upgrade, Physics::Plasma Physics, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Simulació per ordinador, alcator c-mod, ddc:530, upper divertor, ELLM-free discharge, SOL, Basis (linear algebra), Physics, turbulence, transition, h-mode plasmas, Condensed Matter Physics, ddc, Informàtica::Aplicacions de la informàtica::Aplicacions informàtiques a la física i l‘enginyeria [Àrees temàtiques de la UPC], Fusion reactors, Physics and Astronomy, CONFINEMENT MODES, H-MODE PLASMAS, Physics::Space Physics, Nuclear fusion, TURBULENCE, ddc:620, confinement modes, TRANSITION
Abstract

An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L–H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced Dα H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Peer Reviewed "Article signat per més de 50 autors/es: U. Stroth, D. Aguiam, E. Alessi, C. Angioni, N. Arden, R. Arredondo Parra, V. Artigues, O. Asunta, M. Balden, V. Bandaru, A. Banon-Navarro, K. Behler, A. Bergmann, M. Bergmann, J. Bernardo, M. Bernert, A. Biancalani, R. Bielajew, R. Bilato, G. Birkenmeier, T. Blanken, V. Bobkov, A. Bock, T. Body, T. Bolzonella, N. Bonanomi, A. Bortolon, B. Böswirth, C. Bottereau, A. Bottino, H. van den Brand, M. Brenzke, S. Brezinsek, D. Brida, F. Brochard, C. Bruhn, J. Buchanan, A. Buhler, A. Burckhart, Y. Camenen, B. Cannas, P. Cano Megias, D. Carlton, M. Carr, P. Carvalho, C. Castaldo, M. Cavedon, C. Cazzaniga, C. Challis, A. Chankin, C. Cianfarani, F. Clairet, S. Coda, R. Coelho, J.W. Coenen, L. Colas, G. Conway, S. Costea, D. Coster, T. Cote, A.J. Creely, G. Croci, D.J. Cruz Zabala, G. Cseh, A. Czarnecka, I. Cziegler, O. D'Arcangelo, A. Dal Molin, P. David, C. Day, M. de Baar, P. de Marné, R. Delogu, S. Denk, P. Denner, A. Di Siena, J.J. Dominguez Palacios Durán, D. Dunai, A. Drenik, M. Dreval, R. Drube, M. Dunne, B.P. Duval, R. Dux, T. Eich, S. Elgeti, A. Encheva, K. Engelhardt, B. Erdös, I. Erofeev, B. Esposito, E. Fable, M. Faitsch, U. Fantz, M. Farnik, H. Faugel, F. Felici, O. Ficker, S. Fietz, A. Figueredo, R. Fischer, O. Ford, L. Frassinetti, M. Fröschle, G. Fuchert, J.C. Fuchs, H. Fünfgelder, S. Futatani, K. Galazka, J. Galdon-Quiroga, D. Gallart Escolà, A. Gallo10, Y. Gao11, S. Garavaglia3, M. Garcia Muñoz16, B. Geiger21, L. Giannone1, S. Gibson32, L. Gil2, E. Giovannozzi18, S. Glöggler1, M. Gobbin8, J. Gonzalez Martin, T. Goodman, G. Gorini, T. Görler, D. Gradic, G. Granucci, A. Gräter, H. Greuner, M. Griener, M. Groth, A. Gude, L. Guimarais, S. Günter, G. Haas, A.H. Hakola, C. Ham, T. Happel, N. den Harder, G. Harrer, J. Harrison, V. Hauer, T. Hayward-Schneider, B. Heinemann, T. Hellsten, S. Henderson, P. Hennequin, A. Herrmann, E. Heyn, F. Hitzler, J. Hobirk, K. Höfler, J.H. Holm, M. Hölzl, C. Hopf, L. Horvath, T. Höschen, A. Houben, A. Hubbard, A. Huber, K. Hunger, V. Igochine, M. Iliasova, T. Ilkei, K. Insulander Björk, C. Ionita-Schrittwieser, I. Ivanova-Stanik, W. Jacob, N. Jaksic, F. Janky, A. Jansen van Vuuren, A. Jardin, F. Jaulmes, F. Jenko, T. Jensen, E. Joffrin, A. Kallenbach, S. Kálvin, M. Kantor, A. Kappatou, O. Kardaun, J. Karhunen4, C.-P. Käsemann, S. Kasilov, A. Kendl, W. Kernbichler, E. Khilkevitch, A. Kirk, S. Kjer Hansen, V. Klevarova, G. Kocsis, M. Koleva, M. Komm, M. Kong, A. Krämer-Flecken, K. Krieger, A. Krivska, O. Kudlacek, T. Kurki-Suonio, B. Kurzan, B. Labit, K. Lackner, F. Laggner, A. Lahtinen, P.T. Lang, P. Lauber, N. Leuthold, L. Li, J. Likonen, O. Linder, B. Lipschultz, Y. Liu, A. Lohs, Z. Lu, T. Luda di Cortemiglia, N.C. Luhmann, T. Lunt, A. Lyssoivan, T. Maceina, J. Madsen, A. Magnanimo, H. Maier, J. Mailloux, R. Maingi, O. Maj, E. Maljaars, P. Manas, A. Mancini, A. Manhard, P. Mantica, M. Mantsinen, P. Manz, M. Maraschek, C. Marchetto, L. Marrelli, P. Martin, A. Martitsch, F. Matos, M. Mayer, M.-L. Mayoral, D. Mazon, P.J. McCarthy, R. McDermott, R. Merkel, A. Merle, D. Meshcheriakov, H. Meyer, D. Milanesio, P. Molina Cabrera, F. Monaco, M. Muraca, F. Nabais, V. Naulin, R. Nazikian, R.D. Nem, A. Nemes-Czopf, G. Neu, R. Neu, A.H. Nielsen, S.K. Nielsen, T. Nishizawa, M. Nocente, J.-M. Noterdaeme, I. Novikau, S. Nowak, M. Oberkofler, R. Ochoukov, J. Olsen, F. Orain, F. Palermo, O. Pan, G. Papp, I. Paradela Perez, A. Pau, G. Pautasso, C. Paz-Soldan, P. Petersson, P. Piovesan, C. Piron, U. Plank, B. Plaum, B. Plöck, V. Plyusnin, G. Pokol, E. Poli, L. Porte, T. Pütterich, M. Ramisch, J. Rasmussen, G. Ratta, S. Ratynskaia, G. Raupp, D. Réfy, M. Reich1, F. Reimold, D. Reiser, M. Reisner, D. Reiter, T. Ribeiro, R. Riedl, J. Riesch, D. Rittich, J.F. Rivero Rodriguez, G. Rocchi, P. Rodriguez-Fernandez, M. Rodriguez-Ramos, V. Rohde, G. Ronchi, A. Ross, M. Rott, M. Rubel, D.A. Ryan, F. Ryter, S. Saarelma, M. Salewski, A. Salmi, O. Samoylov, L. Sanchis Sanchez, J. Santos, O. Sauter, G. Schall, K. Schlüter, K. Schmid, O. Schmitz, P.A. Schneider, R. Schrittwieser, M. Schubert, C. Schuster, T. Schwarz-Selinger, J. Schweinzer, E. Seliunin, A. Shabbir, A. Shalpegin, S. Sharapov, U. Sheikh, A. Shevelev, G. Sias, M. Siccinio, B. Sieglin, A. Sigalov, A. Silva, C. Silva, D. Silvagni, J. Simpson, S. Sipilä, E. Smigelskis, A. Snicker, E. Solano, C. Sommariva, C. Sozzi, G. Spizzo, M. Spolaore, A. Stegmeir, M. Stejner, J. Stober, E. Strumberge1, G. Suarez Lopez, H.-J. Sun, W. Suttrop, E. Sytova, T. Szepesi, B. Tál, T. Tala, G. Tardini, M. Tardocchi, D. Terranova, M. Teschke, E. Thorén, W. Tierens, D. Told, W. Treutterer, G. Trevisan, E. Trier, M. Tripský, M. Usoltceva, M. Valisa, M. Valovic, M. van Zeeland, F. Vannini, B. Vanovac, P. Varela, S. Varoutis, N. Vianello, J. Vicente, G. Verdoolaege, T. Vierle, E. Viezzer, I. Voitsekhovitch, U. von Toussaint, D. Wagner, X. Wang, M. Weiland, A.E. White, M. Willensdorfer, B. Wiringer, M. Wischmeier, R. Wolf, E. Wolfrum, Q. Yang, Q. Yu, R. Zagórski, I. Zammuto, T. Zehetbauer, W. Zhang, W. Zholobenko, M. Zilker, A. Zito, H. Zohm, S. Zoletnik and the EUROfusion MST1 Team "

Published
2022
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12. On the relationship between magnetic cloud field polarity and geoeffectiveness

Author

E. K. J. Kilpua, Y. Li, J. G. Luhmann, L. K. Jian, and C. T. Russell

Subjects
Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract

In this paper, we have investigated geoeffectivity of near-Earth magnetic clouds during two periods concentrated around the last two solar minima. The studied magnetic clouds were categorised according to the behaviour of the Z-component of the interplanetary magnetic field (BZ) into bipolar (BZ changes sign) and unipolar (BZ maintains its sign) clouds. The magnetic structure of bipolar clouds followed the solar cycle rule deduced from observations over three previous solar cycles, except during the early rising phase of cycle 24 when both BZ polarities were identified almost with the same frequency. We found a clear difference in the number of unipolar clouds whose axial field points south (S-type) between our two study periods. In particular, it seems that the lack of S-type unipolar clouds contributed to relatively low geomagnetic activity in the early rising phase of cycle 24. We estimated the level of magnetospheric activity using a Dst prediction formula with the measured BZ and by reversing the sign of BZ. We found that bipolar clouds with fields rotating south-to-north (SN) and north-to-south (NS) were equally geoeffective, but their geoeffectiveness was clearly modified by the ambient solar wind structure. Geoeffectivity of NS-polarity clouds was enhanced when they were followed by a higher-speed solar wind, while the majority of geoeffective SN-polarity clouds lacked the trailing faster wind. A leading shock increased the geoeffectiveness of both NS- and SN-polarity clouds, in particular, in the case of an intense storm. We found that in 1995–1998, SN-polarity clouds were more geoeffective, while in 2006–2011 NS-polarity clouds produced more storms. A considerably larger fraction of events were trailed by a higher-speed solar wind during our latter study period, which presumably increased geoeffectivity of NS-polarity. Thus, our study demonstrates that during low and moderate solar activity, geoeffectivity of opposite polarity bipolar clouds may depend significantly on the surrounding solar wind structure. In addition, different polarities also give different temporal storm evolutions: a storm from an SN-polarity cloud is expected to occur, on average, half-a-day earlier than a storm from an NS-polarity cloud.

Published
2012
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13. Interplanetary coronal mass ejections in the near-Earth solar wind during the minimum periods following solar cycles 22 and 23

Author

E. K. J. Kilpua, C. O. Lee, J. G. Luhmann, and Y. Li

Subjects
Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract

In this paper we examine the occurrence rates and properties of interplanetary coronal mass ejections (ICMEs) and solar activity levels during the minima following solar cycle 22 (January 1995–December 1997) and 23 (January 2007–April 2010) minima using observations from the OMNI data base. Throughout the minimum following cycle 22 the CME and ICME rates roughly tracked each other, while for the minimum following cycle 23 they diverged. During the minimum after solar cycle 23, there were large variations in the streamer belt structure. During the lowest activity period of cycle 23 (based on sunspot numbers), the ICME rate was about four times higher than during a similar activity period of cycle 22. We propose that this relatively high ICME rate may be due to CME source regions occurring at lower heliolatitudes and due to equatoward deflection of slow and weak CMEs originating from the mid- and high-heliolatitudes. The maximum magnetic fields of the ICMEs identified during the minimum following cycle 23 were ~30 % lower and their radial widths were ~15 % lower compared to the ICMEs observed during the minimum following solar cycle 22. The weak and small ICMEs may result from intrinsically weak CMEs and/or they may represent stronger CMEs that are encountered far away from the center.

Published
2011
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14. Mode analysis limitations of ECE-I & ECE measurements at the plasma edge

Author

Vanovac B., Denk S.S., Wolfrum E., Willensdorfer M., Suttrop W., Fischer R., and Luhmann N.C.

Subjects
Physics, QC1-999
Abstract

Interpretation of the Electron Cyclotron Emission (ECE) and ECE Imaging (ECE-I) measurements concerning the measurement position and the radiation temperature (Trad) at the plasma edge is associated with significant uncertainty. Various limitations such as low and high-density limits, relativistic and Doppler shift-broadening, mode overlap were identified in the past. Here, we analyse the influence of density profile variation onto the radiation temperature in H-mode plasmas at ASDEX Upgrade tokamak. We show that, in the region of steep gradients, the variation of the density profile leads to an outward-shift of the measurement position, towards lower Trad. The analysis is extended towards the study of the contribution of the ordinary mode (O-mode) emission to the measured Trad at the plasma edge. With this analysis, we show the qualitative agreement between experimental observations and modeling when taking into account the O-mode contribution to the ECE measurements. All of these effects are assessed via the Electron Cyclotron Radiation transport forward model that is now routinely used to model the response of the ECE-I and ECE systems in different plasma scenarios.

Published
2019
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15. Overview of the ECE measurements on EAST

Author

Liu Yong, Zhao Hailin, Zhou Tianfu, Liu Xiang, Zhu Zeying, Han Xiang, Schmuck Stefan, Fessey John, Trimble Paul, Domier C.W., Luhmann N.C., Ti Ang, Li Erzhong, Ling Bili, Hu Liqun, Feng Xi, Liu Ahdi, Rowan W.L., Huang He, Phillips P.E., and Figini Lorenzo

Subjects
Physics, QC1-999
Abstract

Radiometer systems and a Michelson interferometer, have been operated routinely to detect the elec-tron cyclotron emission (ECE) from EAST plasmas for diagnosing the local electron temperature. A common quasi-optical antenna placed inside the vacuum vessel is employed to collect and focus the plasma emission, and the line of sight is along a radial chord. All of the systems are located in a diagnostic room where the plasma emission is transmitted by overmoded corrugated waveguide. In-situ absolute intensity calibration has been carried out for both the radiometer systems and the Michelson interferometer independently, to ensure that the ECE diagnostic provides an independent electron temperature measurement. In order to diagnose the small-amplitude electron temperature fluctuation, a correlation ECE (CECE) diagnostic has been designed and commissioned recently. The CECE diagnostic employs an independent antenna system which has improved poloidal resolution. A synthetic diagnostic is realized by using the simulation code SPECE to interpret the ECE data in plasmas with non-Maxwellian distribution, and preliminary results imply that the ECE data could be still useful as a localized measurement in plasmas with non-thermal electrons, such as the LHW-heated plasmas on EAST.

Published
2019
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16. Development of ECE/ECEI diagnostics and MHD-related studies on HL-2A tokamak

Author

Yang Z.C., Jiang M., Shi Z.B., Ding X.T., Luhmann N.C., Zhong W.L., Chen W., Shi P.W., Xu Y., Wen J., Liang A.S., Liu Y., and Yang Q.W.

Subjects
Physics, QC1-999
Abstract

A novel 60-channel electron cyclotron emission (ECE) radiometer has been designed and tested for the measurement of electron temperature profiles on the HL-2A tokamak. This system is based on the intermediate frequency division technique, and has the features of wide working frequency range (60−90 GHz) and high temporal-spatial resolution (3 µs, 1 cm), which covers almost the entire plasma region. Also, an electron cyclotron emission imaging (ECEI) system has been developed for studying two dimensional electron temperature fluctuations. It is comprised of several front-end quasi-optical lenses, a 24 channel heterodyne imaging array with a tunable RF frequency range spanning 60−135 GHz, and a set of back-end ECEI electronics that together generate two 24×8 array images of the 2nd harmonic X-mode electron cyclotron emission from the HL-2A plasma. The measurement region can be flexibly shifted due to two independent local oscillator sources, and the field of view can be adjusted easily by changing the position of the zoom lenses as well. The temporal resolution is about 2.5 µs and the achievable spatial resolution is 1 cm. The ECE/ECEI diagnostics have been demonstrated to be powerful tools to study MHD-related physics including the multi-scale interaction between macro-scale MHD and micro-scale turbulence on the HL-2A tokamak.

Published
2019
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17. Diagnostics of corotating interaction regions with the kinetic properties of iron ions as determined with STEREO/PLASTIC

Author

P. Bochsler, M. A. Lee, R. Karrer, L. K. Jian, L. Ellis, C. J. Farrugia, A. B. Galvin, L. M. Kistler, H. Kucharek, E. Möbius, M. A. Popecki, K. D. C. Simunac, L. M. Blush, H. Daoudi, P. Wurz, B. Klecker, R. F. Wimmer-Schweingruber, B. Thompson, J. G. Luhmann, C. T. Russell, and A. Opitz

Subjects
Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract

STEREO/PLASTIC determines three-dimensional distributions of solar wind iron ions with unprecedented time resolution. Typically 300 to 1000 counts are registered within each 5 min time interval. For the present study we use the information contained in these distributions to characterize CIRs (Corotating Interaction Regions) in two test cases. We perform a consistency test for both the derived physical parameters and for the analytical model of CIRs of Lee (2000). At 1 AU we find that apart from compositional changes the most indicative parameter for marking the time when a CIR passes a spacecraft is the angular deflection of the flow vector of particles. Changes in particle densities and the changes in magnitudes of speeds are apparently less reliable indicators of stream interfaces.

Published
2010
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18. Statistics of counter-streaming solar wind suprathermal electrons at solar minimum: STEREO observations

Author

B. Lavraud, A. Opitz, J. T. Gosling, A. P. Rouillard, K. Meziane, J.-A. Sauvaud, A. Fedorov, I. Dandouras, V. Génot, C. Jacquey, P. Louarn, C. Mazelle, E. Penou, D. E. Larson, J. G. Luhmann, P. Schroeder, L. Jian, C. T. Russell, C. Foullon, R. M. Skoug, J. T. Steinberg, K. D. Simunac, and A. B. Galvin

Subjects
Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract

Previous work has shown that solar wind suprathermal electrons can display a number of features in terms of their anisotropy. Of importance is the occurrence of counter-streaming electron patterns, i.e., with "beams" both parallel and anti-parallel to the local magnetic field, which is believed to shed light on the heliospheric magnetic field topology. In the present study, we use STEREO data to obtain the statistical properties of counter-streaming suprathermal electrons (CSEs) in the vicinity of corotating interaction regions (CIRs) during the period March–December 2007. Because this period corresponds to a minimum of solar activity, the results are unrelated to the sampling of large-scale coronal mass ejections, which can lead to CSE owing to their closed magnetic field topology. The present study statistically confirms that CSEs are primarily the result of suprathermal electron leakage from the compressed CIR into the upstream regions with the combined occurrence of halo depletion at 90° pitch angle. The occurrence rate of CSE is found to be about 15–20% on average during the period analyzed (depending on the criteria used), but superposed epoch analysis demonstrates that CSEs are preferentially observed both before and after the passage of the stream interface (with peak occurrence rate >35% in the trailing high speed stream), as well as both inside and outside CIRs. The results quantitatively show that CSEs are common in the solar wind during solar minimum, but yet they suggest that such distributions would be much more common if pitch angle scattering were absent. We further argue that (1) the formation of shocks contributes to the occurrence of enhanced counter-streaming sunward-directed fluxes, but does not appear to be a necessary condition, and (2) that the presence of small-scale transients with closed-field topologies likely also contributes to the occurrence of counter-streaming patterns, but only in the slow solar wind prior to CIRs.

Published
2010
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19. STEREO observations of interplanetary coronal mass ejections and prominence deflection during solar minimum period

Author

E. K. J. Kilpua, J. Pomoell, A. Vourlidas, R. Vainio, J. Luhmann, Y. Li, P. Schroeder, A. B. Galvin, and K. Simunac

Subjects
Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract

In this paper we study the occurrence rate and solar origin of interplanetary coronal mass ejections (ICMEs) using data from the two Solar TErrestrial RElation Observatory (STEREO) and the Wind spacecraft. We perform a statistical survey of ICMEs during the late declining phase of solar cycle 23. Observations by multiple, well-separated spacecraft show that even at the time of extremely weak solar activity a considerable number of ICMEs were present in the interplanetary medium. Soon after the beginning of the STEREO science mission in January 2007 the number of ICMEs declined to less than one ICME per month, but in late 2008 the ICME rate clearly increased at each spacecraft although no apparent increase in the number of coronal mass ejections (CMEs) occurred. We suggest that the near-ecliptic ICME rate can increase due to CMEs that have been guided towards the equator from their high-latitude source regions by the magnetic fields in the polar coronal holes. We consider two case studies to highlight the effects of the polar magnetic fields and CME deflection taking advantage of STEREO observations when the two spacecraft were in the quadrature configuration (i.e. separated by about 90 degrees). We study in detail the solar and interplanetary consequences of two CMEs that both originated from high-latitude source regions on 2 November 2008. The first CME was slow (radial speed 298 km/s) and associated with a huge polar crown prominence eruption. The CME was guided by polar coronal hole fields to the equator and it produced a clear flux rope ICME in the near-ecliptic solar wind. The second CME (radial speed 438 km/s) originated from an active region 11007 at latitude 35° N. This CME propagated clearly north of the first CME and no interplanetary consequences were identified. The two case studies suggest that slow and elongated CMEs have difficulties overcoming the straining effect of the overlying field and as a consequence they are guided by the polar coronal fields and cause in-situ effects close to the ecliptic plane. The 3-D propagation directions and CME widths obtained by using the forward modelling technique were consistent with the solar and in-situ observations.

Published
2009
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20. Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

Author

A. B. Galvin, M. A. Popecki, K. D. C. Simunac, L. M. Kistler, L. Ellis, J. Barry, L. Berger, L. M. Blush, P. Bochsler, C. J. Farrugia, L. K. Jian, E. K. J. Kilpua, B. Klecker, M. Lee, Y. C.-M. Liu, J. L. Luhmann, E. Moebius, A. Opitz, C. T. Russell, B. Thompson, R. F. Wimmer-Schweingruber, and P. Wurz

Subjects
Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract

STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h) sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007) which includes minor ion (He, Fe, O) kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

Published
2009
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22. System-on-Chip approach microwave diagnostics development for burning plasma

Author

Neville C. Luhmann, Calvin Domier, Yilun Zhu, Jon Dannenberg, Ying Chen, and Guanying Yu

Subjects
Heterodyne, Physics, Tokamak, business.industry, Local oscillator, Integrated circuit, Chip, law.invention, Optics, Microwave imaging, law, System on a chip, business, Microwave
Abstract

System-on-chip (SoC) millimeter wave integrated circuit technology has been developed and employed in chip heterodyne radiometers in Electron Cyclotron Emission Imaging (ECEI) and Microwave Imaging Reflectometer (MIR) on the DIII-D tokamak for 2D electron temperature and density fluctuation diagnostics. The W-band (75-110 GHz) ECEI system has been employed with 20 poloidal horn receiver modules with customized monolithic integrated circuit chips and internal local oscillator coupling path. The new SoC approach demonstrates > 30 dB additional gain on the receiver and 95% electronics noise suppression compared to the previous Schottky diode mixer array 1 . An F-band (110-140 GHz) receiver chip has been developed to measure MHD and turbulence behavior on the DIII-D high-field side, such as Alfven eigenmodes. Furthermore, it can image pedestal structure evolution on fusion facilities with stronger magnetic fields, such as ASDEX-U, EAST, HL-2M, and LHD. The F-band chip performance has been tested in the laboratory. Also, V-band (55-75 GHz) transmitter and receiver modules (55-75 GHz) have been developed for DIII-D and NSTX-U Microwave Imaging Reflectometer (MIR) application suitability for 2D density fluctuation imaging on the pedestal region 2 .

Published
2021
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23. The Solar Clock

Author

Janet G. Luhmann, Christopher T. Russell, and Lan Jian

Subjects
Physics, Thesaurus (information retrieval), Geophysics, Information retrieval, Dynamo theory, Solar cycle
Published
2019
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24. A Clock in the Sun?

Author

C. T. Russell, J. G. Luhmann, and Lan Jian

Subjects
Solar minimum, Physics, Schedule, 010504 meteorology & atmospheric sciences, Astronomy, Astronomy and Astrophysics, 01 natural sciences, Term (time), Solar cycle, Amplitude, Space and Planetary Science, Duration (music), 0103 physical sciences, Cadence, Solar dynamo, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

The sunspot cycle is quite variable in duration and amplitude, yet in the long term, it seems to return to solar minimum on schedule, as if guided by a clock with an average period of close to 11.05 years for the sunspot number cycle and 22.1 years for the magnetic cycle. This paper provides a brief review of the sunspot number cycle since 1750, discusses some of the processes controlling the solar dynamo, and provides clues that may add to our understanding of what controls the cadence of the solar clock.

Published
2019
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25. Magnetic topology at Venus: new insights to the Venus plasma environment

Author

Shaosui Xu, David L. Mitchell, Yingjuan Ma, Janet G. Luhmann, and R. A. Frahm

Subjects
Physics, biology, Venus, Plasma, biology.organism_classification, Topology, Topology (chemistry)
Abstract

Venus lacks significant intrinsic magnetic fields and thus its atmosphere and ionosphere interact directly with the solar wind flow and magnetic fields. Interplanetary magnetic fields (IMF) can penetrate into the ionosphere when the upstream solar wind dynamic is stronger than the ionospheric plasma pressure. Magnetic topology can be inferred at Venus if it is defined as the magnetic connectivity to the collisional atmosphere/ionosphere, rather than connectivity to the planet’s surface. Utilizing electron and magnetic field measurements from the Venus Express mission, this study provides the first characterization of magnetic topology at Venus by examining the pitch angle and energy distribution of superthermal (> ~1 eV) electrons. More specifically, the presence of loss cones in electron pitch angle distributions infers the connectivity to the nightside collisional atmosphere and the presence of ionospheric photoelectrons (identified from electron energy distributions) indicates the connectivity to the dayside collisional ionosphere. We show case examples of various magnetic topology types at Venus, including the most expected draped IMF, open field lines connected to the nightside atmosphere, open field lines connected to the dayside ionosphere, and, most surprisingly, cross-terminator closed field lines. More interestingly, during one of the ionospheric hole events identified by Collinson et al. [2014, JGRA], we discover not only the expected open magnetic topology but also a field-aligned potential drop, which has implications for its formation mechanism. The characterization of magnetic connectivity could provide new insights into many important topics on Venus, such as planetary ion outflow, energetic electron precipitation (possible auroral emission), and the formation mechanism of Venusian ionospheric holes.

Published
2021
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27. Space Physics at Venus: Exploring atmospheric dynamics, escape, and evolution

Author

Janet G. Luhmann, Christopher M. Fowler, Steve Boucher, Chuanfei Dong, Shannon Curry, Gina A. DiBraccio, Moa Persson, S. Ledvina, Christopher T. Russell, Yoshifumi Futaana, Joseph O'Rourke, Michael J. Way, Shaosui Xu, Glyn Collinson, and Robin Ramstad

Subjects
Physics, biology, Venus, Space physics, Atmospheric dynamics, biology.organism_classification, Astrobiology
Published
2021
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28. Electron cyclotron emission imaging in tokamak plasmas

Author

Munsat, Tobin, Domier, Calvin W., Kong, Xiangyu, Liang, Tianran, Luhmann, Neville C., Jr., Tobias, Benjamin J., Lee, Woochang, Park, Hyeon K., Yun, Gunsu, Classen, Ivo. G.J., and Donne, Anthony J.H.

Subjects
Diagnostic imaging -- Methods, Diagnostic imaging -- Technology application, Plasma (Ionized gases) -- Properties, Technology application, Astronomy, Physics
Abstract

We discuss the recent history and latest developments of the electron cyclotron emission imaging diagnostic technique, wherein electron temperature is measured in magnetically confined plasmas with two-dimensional spatial resolution. The key enabling technologies for this technique are the large-aperture optical systems and the linear detector arrays sensitive to millimeter-wavelength radiation. We present the status and recent progress on existing instruments as well as new systems under development for future experiments. We also discuss data analysis techniques relevant to plasma imaging diagnostics and present recent temperature fluctuation results from the tokamak experiment for technology oriented research (TEXTOR). [c] 2010 Optical Society of America OCIS codes: 280.5395, 040.2840, 120.5630.

Published
2010

29. Novel Sawtooth Structure Loading to Mitigate Mode Competition in a 346 GHz Backward Wave Oscillator

Author

Neville C. Luhmann, Christian Hurd, and Yuan Zheng

Subjects
Competition (economics), Physics, Acoustics, Structure (category theory), Mode (statistics), Wave structure, Backward-wave oscillator, Sawtooth wave, Stability (probability), Electronic circuit
Abstract

A novel approach to mitigate mode competition and improve stability in a 346 GHz Backward Wave Oscillator (BWO) by loading a copper sawtooth slow wave structure (SWS) is proposed. The effects of mode competition, and the sawtooth structure loading effects are discussed. CST simulation has been used to verify the analysis and test of the stability of those circuits.

Published
2020
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30. Search for Martian Schumann Resonances

Author

Syed A. Haider, Yanan Yu, Christopher T. Russell, Peter Chi, Janet G. Luhmann, and J. P. Pabari

Subjects
Martian, Physics, Schumann resonances, Astrobiology
Abstract

On Earth, electric discharges in thunderstorms produce ELF waves in the Earth-ionosphere waveguide that circles the globe. These waves give rise to Schumann resonances in the waveguide resonant cavity. These waves are also expected to occur at Venus, produced by strong lightning in the Venus atmosphere and at Mars produced by active dust devils or dust storms, during southern hemisphere summer, when the planet is near periapsis. Within dust storms, dust particles undergo triboelectric charging. The charge transfer leads to charge separation. A lightning discharge is expected to occur when the charge exceeds the breakdown strength of the media present. The transient electric discharge emits electromagnetic waves in the VLF/ELF range of frequency, leading to Schumann Resonance in the surface-ionospheric cavity. In a heterogeneous cavity, Schumann resonance modes are observable using an in-situ instrument. Recently has it been possible to search for these electromagnetic waves from the Mars surface using the UCLA-provided InSight fluxgate magnetometer. The weakness of the vertical component of ULF waves at Mars suggests that the subsurface is electrically conducting, allowing trapping of electromagnetic energy between the sub-surface and the ionosphere. The fundamental mode of Schumann resonance carries higher energy compared to there are more chances of observing the fundamental mode. Various values of the first mode are predicted in the literature for Mars like 13-14 Hz or between 9-14 Hz and 17.5 Hz. Even if the fundamental mode is above 10 Hz, the 20 Hz sampling rate will allow detection of an aliased signal. We examine the data obtained during Martian sandstorms for the possible existence of such waves. A large dust storm was detected on Mars beginning on InSight sols 40 to 50, and ending during sols 50 to 90. Examining the 20 Hz InSight magnetometer data during this period reveals no clearly identifiable Schumann Resonance signals within the bandwidth of the magnetometer.

Published
2020
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31. ESCAPADE: Coordinated multipoint measurements of Mars' unique hybrid magnetosphere

Author

Christopher M. Fowler, Yuki Harada, Shannon Curry, David Brain, Janet G. Luhmann, Paul Withers, Yingjuan Ma, Matthieu Berthomier, Ronan Modolo, Aroh Barjatya, Edward Thiemann, Shaosui Xu, Christopher T. Russell, Davin Larson, Robert Lillis, Phyllis Whittlesey, Roberto Livi, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Embry-Riddle Aeronautical University, University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Astronomy [Boston], Boston University [Boston] (BU), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Solar System, Ion thruster, Spacecraft, business.industry, Astronomy, Magnetosphere, Mars Exploration Program, Proton (rocket family), Solar wind, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Van Allen Probes, Astrophysics::Earth and Planetary Astrophysics, business
Abstract

Multi-spacecraft missions after 2000 (Cluster II, THEMIS, Van Allen Probes, and MMS) have revolutionized our understanding of the causes, patterns and variability of a wide array of plasma phenomena in the terrestrial magnetospheric environment. ESCAPADE is a twin-spacecraft Mars mission concept that will similarly revolutionize our understanding of how solar wind momentum and energy flows throughout Mars’ magnetosphere to drive ion and sputtering escape, two processes which have helped shape Mars’ climate evolution over solar system history. ESCAPADE will measure magnetic field strength and topology, ion plasma distributions (separated into light and heavy masses), as well as suprathermal electron flows and thermal electron and ion densities, from coordinated elliptical, 200 km x ~7000 km orbits. ESCAPADE are small spacecraft ( ESCAPADE is due to complete its preliminary design review in August 2020, thereafter moving toward build, test, integration and launch two years later. We will report on science goals and objectives, mission design challenges, and provide a status update.

Published
2020
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32. W-band system-on-chip electron cyclotron emission imaging system on DIII-D

Author

B. J. Tobias, G. J. Kramer, Calvin Domier, Ying Chen, J.H. Yu, C. Luo, Neville C. Luhmann, Ahmed Diallo, Yu Ye, Yilun Zhu, Xiaodong Li, Guanying Yu, M. Chen, and Yang Ren

Subjects
010302 applied physics, Physics, Noise temperature, business.industry, Local oscillator, Amplifier, Superheterodyne receiver, Schottky diode, 01 natural sciences, Low-noise amplifier, 010305 fluids & plasmas, law.invention, Optics, W band, law, 0103 physical sciences, Radio frequency, business, Instrumentation
Abstract

Monolithic, millimeter-wave "system-on-chip" (SoC) technology has been employed in heterodyne receiver integrated circuit radiometers in a newly developed Electron Cyclotron Emission Imaging (ECEI) system on the DIII-D tokamak for 2D electron temperature profile and fluctuation evolution diagnostics. A prototype module operating in the E-band (72 GHz-80 GHz) was first employed in a 2 × 10 element array that demonstrated significant improvements over the previous quasi-optical Schottky diode mixer arrays during the 2018 operational campaign of the DIII-D tokamak. For compatibility with International Thermonuclear Experimental Reactor relevant scenarios on DIII-D, the SoC ECEI system was upgraded with 20 horn-waveguide receiver modules. Each individual module contains a University of California Davis designed W-band (75 GHz-110 GHz) receiver die that integrates a broadband low noise amplifier, a double balanced down-converting mixer, and a ×4 multiplier on the local oscillator (LO) chain. A ×2 multiplier and two IF amplifiers are packaged and selected to further boost the signal strength and downconvert the signal frequency. The upgraded W-band array exhibits >30 dB additional gain and 20× improvement in noise temperature compared with the previous Schottky diode radio frequency mixer input systems; an internal 8 times multiplier chain is used to bring down the LO frequency below 12 GHz, thereby obviating the need for a large aperture for quasi-optical LO coupling and replacing it with coaxial connectors. Horn-waveguide shielding housing avoids out-of-band noise interference on each individual module. The upgraded ECEI system plays an important role for absolute electron temperature evolution and fluctuation measurements for edge and core region transport physics studies.

Published
2020

33. ICME Evolution in the Inner Heliosphere

Author

Noé Lugaz, Nat Gopalswamy, Janet G. Luhmann, and Lan Jian

Subjects
Geomagnetic storm, Physics, 010504 meteorology & atmospheric sciences, Solar energetic particles, Astronomy, Astronomy and Astrophysics, Space weather, 01 natural sciences, Heliophysics, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Magnetic cloud, Interplanetary spaceflight, 010303 astronomy & astrophysics, Heliosphere, 0105 earth and related environmental sciences
Abstract

ICMEs (interplanetary coronal mass ejections), the heliospheric counterparts of what is observed with coronagraphs at the Sun as CMEs, have been the subject of intense interest since their close association with geomagnetic storms was established in the 1980s. These major interplanetary plasma and magnetic field transients, often preceded and accompanied by solar energetic particles (SEPs), interact with planetary magnetospheres, ionospheres, and upper atmospheres in now fairly well-understood ways, although their details and context affect their overall impacts. The term ICME as it is used here refers to the complete solar-wind plasma and field disturbance, including the leading shock (if present), the compressed, deflected solar-wind plasma and the field behind the shock (“sheath”), and the coronal ejecta (the “driver”) – often called a magnetic cloud. Many uncertainties remain in understanding both the relationship to what is observed at the Sun and the variety of local outcomes suggested by in-situ observations. This impacts our abilities to interpret events and to forecast effects based on solar observations. Here, we briefly consider what is known about ICMEs and their evolution en route from the Sun from the combination of available observations and interpretive models that have been developed up to now. The included references are only representative of the large body of work that has been published on this subject. Our aim is to provide the reader with an updated synthesis of research results in this still active area of heliophysics at the dawn of the Parker Solar Probe (PSP) and Solar Orbiter (SO) mission era.

Published
2020
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34. ESCAPADE: coordinated multipoint measurements of Mars' near-space plasma environment

Author

Shaosui Xu, Yuki Harada, Shannon Curry, Aroh Barjatya, David Brain, Roberto Livi, Paul Withers, Robert Lillis, Ronan Modolo, Davin Larson, Christopher M. Fowler, Janet G. Luhmann, Edward Thiemann, Christopher T. Russell, and Phyllis Whittlesey

Subjects
Physics, Mars Exploration Program, Plasma, Astrobiology, Near space
Abstract

Multi-spacecraft missions after 2000 (Cluster II, THEMIS, Van Allen Probes, and MMS) have revolutionized our understanding of the causes, patterns and variability of a wide array of plasma phenomena in the terrestrial magnetospheric environment. ESCAPADE is a twin-spacecraft Mars mission concept that will similarly revolutionize our understanding of how solar wind momentum and energy flows throughout Mars’ magnetosphere to drive ion and sputtering escape, two processes which have helped shape Mars’ climate evolution over solar system history. ESCAPADE will measure magnetic field strength and topology, ion plasma distributions (separated into light and heavy masses), as well as suprathermal electron flows and thermal electron and ion densities, from elliptical, 200 km x 7000 km orbits. ESCAPADE are small spacecraft (ESCAPADE has been selected for Phase A and B study by NASA as one of three finalists in the SIMPLEX-II program. We will report on science goals, engineering and mission design challenges, and provide a status update.

Published
2020
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35. Structure and Variability of the Martian Ion Composition Boundary Layer

Author

John E. P. Connerney, Janet G. Luhmann, Jasper Halekas, David Brain, Gina A. DiBraccio, Bruce M. Jakosky, David L. Mitchell, and J. P. McFadden

Subjects
Physics, 010504 meteorology & atmospheric sciences, Magnetosphere, Geophysics, Bow shocks in astrophysics, 01 natural sciences, Physics::Geophysics, Atmosphere, Boundary layer, Solar wind, Magnetosheath, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Exosphere
Abstract

A complex boundary layer with a variety of charged particle and electromagnetic field signatures, including a transition between plasma predominantly of solar wind origin and plasma of planetary origin, lies between the Martian bow shock and the ionosphere. In this paper, we develop and utilize algorithms to autonomously identify and characterize this ion composition boundary (ICB), using data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We find an asymmetric ICB with a larger average thickness, lower altitude, and lower velocity shear in the hemisphere where the solar wind motional electric field points outward, as a result of the asymmetry of the mass loading process. The ICB thickness scales with the magnetosheath proton gyroradius at the top of the boundary layer but does not clearly vary with external drivers. The ICB location varies with solar wind ram pressure and crustal magnetic field strength, but does not clearly respond to solar wind Mach number or extreme ultraviolet irradiance. The ICB represents a distinct boundary for ion density and flow speed, but the magnetic field strength and direction typically do not vary significantly across the ICB. The plasma density and flow speed at the ICB vary seasonally, likely in response to variations in the neutral exosphere and/or atmosphere. However, the ICB on average remains at or below the altitude where pressure balance is achieved between the piled up magnetic field (MPB) and the solar wind ram pressure, regardless of season or crustal magnetic field strength.

Published
2018
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36. Statistical Study of the Energetic Proton Environment at Titan's Orbit From the Cassini Spacecraft

Author

Xianzhe Jia, Andrew J. Coates, Nick Sergis, Norbert Krupp, Elias Roussos, A. Azari, D. Román, I. J. Rae, K. Dialynas, Geraint H. Jones, Leonardo Regoli, and Janet G. Luhmann

Subjects
Physics, 010504 meteorology & atmospheric sciences, Spacecraft, business.industry, Astronomy, 01 natural sciences, symbols.namesake, Geophysics, Space and Planetary Science, 0103 physical sciences, symbols, Titan (rocket family), business, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Published
2018
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37. The Twisted Configuration of the Martian Magnetotail: MAVEN Observations

Author

Shaosui Xu, Gina A. DiBraccio, Jasper Halekas, Yuki Harada, David Brain, Shannon Curry, Chuanfei Dong, Bruce M. Jakosky, Suranga Ruhunusiri, Y. I. J. Soobiah, David L. Mitchell, Jacob Gruesbeck, Jared Espley, Takuya Hara, Janet G. Luhmann, Yingjuan Ma, and John E. P. Connerney

Subjects
Physics, Martian, 010504 meteorology & atmospheric sciences, Field line, Ecliptic, Magnetic reconnection, Mars Exploration Program, Atmosphere of Mars, Astrophysics, 01 natural sciences, Current sheet, Geophysics, Physics::Space Physics, 0103 physical sciences, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Interplanetary magnetic field, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract

Measurements provided by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are analyzed to investigate the Martian magnetotail configuration as a function of interplanetary magnetic field (IMF) BY. We find that the magnetotail lobes exhibit a ~45deg twist, either clockwise or counterclockwise from the ecliptic plane, up to a few Mars radii downstream. Moreover, the associated cross-tail current sheet is rotated away from the expected location for a Venus-like induced magnetotail based on nominal IMF draping. Data-model comparisons using magnetohydrodynamic simulations are in good agreement with the observed tail twist. Model field line tracings indicate that a majority of the twisted tail lobes are composed of open field lines, surrounded by draped IMF. We infer that dayside magnetic reconnection between the crustal fields and draped IMF creates these open fields and may be responsible for the twisted tail configuration, similar to what is observed at Earth.

Published
2018
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38. High level of integration of front-end imaging optics system for electron cyclotron emission imaging diagnostics on the DIII-D tokamak

Author

Neville C. Luhmann, Yilun Zhu, Guangzhi Xu, Xiangbin Li, Guanying Yu, and J. H. Cao

Subjects
Physics, Tokamak, DIII-D, business.industry, Mechanical Engineering, Cyclotron, Resolution (electron density), Curved mirror, Plasma, law.invention, Front and back ends, Optics, Upgrade, Nuclear Energy and Engineering, law, General Materials Science, business, Civil and Structural Engineering
Abstract

The optics system of the Electron Cyclotron Emission Imaging (ECEI) diagnostics on the DIII-D tokamak has been developed and installed for high-resolution temperature fluctuations measurement in the previous decade. The System-on-Chip approach upgrade was finished in June 2019 with high integrated receiver array with 20 individual modules. In this paper, we design new optics with high-level integration. In the new optics system, there will be two mirrors from plasma to receiver array, including one replaceable curved mirror out of the vacuum and one fixed curved mirror in the vessel. There are two options with 1:1 and 1:2 magnifications for high poloidal resolution and larger poloidal window modes. The new optics system has multiple improvements, including lighter weight, smaller size, more flexible installation and alignment. The synthetic ECEI module is used to evaluate the new optics system.

Published
2021
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39. OVERVIEW OF PHYSICS STUDIES ON ASDEX UPGRADE

Author

Neville C. Luhmann, J. Mailloux, A. Kappatou, Yann Camenen, R. Arredondo Parra, P. Petersson, G. F. Harrer, I. Gomez Ortiz, E. Giovannozzi, S. S. Henderson, C. Sommariva, Thomas Schwarz-Selinger, G. Fuchert, Christopher G. Albert, P. Piovesan, A. Herrmann, C. Piron, Robert Lunsford, J. Hobirk, F. Clairet, L. Xiang, Carlo Cazzaniga, A. Burckhart, B. Kurzan, Bernhard Ploeckl, G. Kocsis, A. Mancini, Benoit Labit, M. Reich, N. den Harder, Faa Federico Felici, M. Oberparleiter, Tamás Szepesi, Sibylle Günter, K. Behler, R. Merkel, Ocleto D'Arcangelo, G. Haas, Alessandro Bortolon, T. B. Cote, E. Trier, P. Simon, A. Gude, Daniele Milanesio, Winfried Kernbichler, Dorothea Gradic, M. Rodriguez-Ramos, G.A. Rattá, G. Croci, O. Tudisco, E. Heyn, M. Groth, J. Gonzalez Martin, Olivier Sauter, Irena Ivanova-Stanik, Massimo Nocente, J. R. Harrison, Martin Heyn, C. Bruhn, C. Ham, L. Shao, M. Schubert, F. Brochard, Yu Gao, Bernd Heinemann, Sandra C. Chapman, Armin Manhard, S. S. Denk, A. Jardin, D. P. Coster, G. Schall, L. Horvath, Alexander Creely, Roman Schrittwieser, Patrick J. McCarthy, C. Castaldo, B. Wiringer, M. J. Mantsinen, Till Höschen, Ph. Lauber, V. Mertens, Anders Nielsen, G. Suarez, M. E. Manso, M. Dibon, S. Wiesen, Mirko Salewski, C. D. Challis, J. Schweinzer, D. Douai, Lorenzo Frassinetti, R. C. Wolf, Mirko Ramisch, P. de Marne, Yueqiang Liu, H. van den Brand, S. Nowak, E. Joffrin, M. Teschke, Karl Schmid, D. Silvagni, L. Giannone, D. I. Refy, E. Wolfrum, M. Sertoli, Chanho Moon, O. J. W. F. Kardaun, A. Ross, S. Elgeti, A. Shalpegin, G. D. Conway, A. Sigalov, Alberto Bottino, Benedikt Geiger, M. Willensdorfer, D. C. van Vugt, Mark Maraschek, W. Zhang, M. Oberkofler, M. Griener, Stylianos Varoutis, Bill Scott, F. Monaco, W. Suttrop, Helmut Faugel, Christian Hopf, J. Vicente, Gerhard Raupp, S. Fietz, Omar Maj, D. Terranova, Q. Yu, E. Seliunin, L. Gil, K. Lackner, I. Novikau, S. Heinzel, G. Birkenmeier, O. Linder, I. Zammuto, H. Fünfgelder, Alessandro Biancalani, D. Prisiazhniuk, Analiza M. Silva, Volker Hauer, Ulrich Stroth, M. Faitsch, Toke Koldborg Jensen, S. Brezinsek, S. Garavaglia, V. Nikolaeva, C. Angioni, T. Maceina, Antti Snicker, O. Schmitz, T. Vierle, A. Scarabosio, D. Carlton, F. Penzel, M. Tardocchi, Riccardo Maggiora, V. Plyusnin, A. Bergmann, A. Bock, G. Rocchi, Andreas Frank Martitsch, J. W. Coenen, I. Erofeev, Pierre Manas, J. Stober, O. Meyer, M. A. Van Zeeland, A. S. Jacobsen, H. Meister, Jens Madsen, E. Smigelskis, A. Lohs, T. Happel, A. Gallo, F. Ryter, P. A. Schneider, A. Kallenbach, Alf Köhn, C. Bottereau, I. Paradela Perez, N. Arden, M. Koubiti, Gergely Papp, Burkhard Plaum, Jorge Ferreira, P. Denner, H. Greuner, Daniel Told, M. Weiland, T. Hayward-Schneider, B. Sieglin, A. Buhler, B. Böswirth, A. Krämer-Flecken, F. Jaulmes, J. Galdon-Quiroga, M. Balden, J. Pinzón Acosta, C. Sozzi, T. Bolzonella, G. Neu, Simon Freethy, T. Sehmer, K. Höfler, T. T. Ribeiro, F. Mink, Ursel Fantz, Q. Yang, Jeppe Olsen, M. Wischmeier, P. Mantica, Timothy Goodman, R. Delogu, T. Tala, Panagiotis Tolias, A. Houben, G. Tardini, A. Kirk, T. Odstrcil, R. Fischer, J. Juul Rasmussen, D. Carralero, H. F. Meyer, P. Martin, J. Miettunen, E. Maljaars, Matthew Carr, Z. Yang, G. Pautasso, B. P. Duval, E. Sytova, Stefano Coda, D. Meshcheriakov, Morten Stejner, S. Zoletnik, Thomas Zehetbauer, M. Li, F. Liu, R. Neu, A. Drenik, P. Manz, E. Fable, Otto Asunta, Zhixin Lu, S. Kálvin, Bruce Lipschultz, Vinodh Bandaru, A. Di Siena, Mattia Siccinio, S. Costea, Frank Jenko, Peter Lang, V. Rohde, Manfred Zilker, F. Nabais, H. J. Sun, Chris Hegna, A. Krivska, M. Rott, S. E. Sharapov, Antoine Merle, J. Bernardo, K. Engelhardt, M. Garcia-Munoz, M. Kantor, M. Hölzl, J. M. Santos, L. Guimarais, A. Figuereido, Carlos B. da Silva, Ch. Day, P. David, U. von Toussaint, T. C. Blanken, D. A. Ryan, F. Palermo, Silvio Ceccuzzi, J.-M. Noterdaeme, M. Gobbin, A. Jansen van Vuuren, C.-P. Kasemann, D. Rittich, Wouter Tierens, Taina Kurki-Suonio, C. Martens, R. Riedl, Antti Hakola, A. Czarnecka, F. Hitzler, M. Spolaore, M. Tripský, D. Brida, A. V. Chankin, Alessandro Pau, T. Ilkei, K. Krieger, Emanuele Poli, Florian Laggner, J. F. Rivero-Rodriguez, Wolfgang Jacob, Nengchao Wang, Anne White, S. Kjer Hansen, Stefan Kragh Nielsen, M. Fröschle, R. Bilato, O. Kudlacek, Tobias Görler, A. Stegmeir, Ari Salmi, L. Colas, A. Mlynek, Istvan Cziegler, V. Bobkov, James Buchanan, A. Gräter, T. Luda di Cortemiglia, R. Drube, John Hammer Holm, Giuliana Sias, K. Galazka, Giuseppe Gorini, V. Igochine, B. Vanovac, O. P. Ford, A. Garcia-Carrasco, R. M. McDermott, B. Tal, A. Lebschy, M. Cavedon, Julia Fuchs, E. Viezzer, R. Dux, R.A. Pitts, Svetlana V. Ratynskaia, Aqsa Shabbir, Sergei Kasilov, M. Bernert, S. Saarelma, Gergö Pokol, F. Reimold, Geert Verdoolaege, M. Mayer, Marek Rubel, L. Sanchis-Sanchez, R. Maingi, William Hornsby, U. Plank, C. Cianfarani, N. Vianello, A. Huber, Gustavo Granucci, Didier Mazon, S. Glöggler, J. Simpson, I. Faust, G. L. Ravera, Laurie Porte, Johann Riesch, F. Janky, A Lyssoivan, T. Pütterich, F. Orain, M. Valisa, B. Esposito, C. Gleason-González, Juha Karhunen, M. Valovic, H. Maier, Gábor Cseh, A. Nemes-Czopf, E. Thoren, O. Pan, T. Eich, R. Coelho, M.R. de Baar, E. Strumberger, T. Hellsten, Lionello Marrelli, Boglarka Erdos, Pascale Hennequin, R. Ochoukov, H. Zohm, D. Wagner, Yevgen O. Kazakov, A. Medvedeva, M. G. Dunne, W. Treutterer, N. Leuthold, R. Zagórski, S. Potzel, V. Klevarova, Dirk Reiser, X. Wang, T. Lunt, Meyer, H, Angioni, C, Albert, C, Arden, N, Arredondo Parra, R, Asunta, O, De Baar, M, Balden, M, Bandaru, V, Behler, K, Bergmann, A, Bernardo, J, Bernert, M, Biancalani, A, Bilato, R, Birkenmeier, G, Blanken, T, Bobkov, V, Bock, A, Bolzonella, T, Bortolon, A, Boswirth, B, Bottereau, C, Bottino, A, Van Den Brand, H, Brezinsek, S, Brida, D, Brochard, F, Bruhn, C, Buchanan, J, Buhler, A, Burckhart, A, Camenen, Y, Carlton, D, Carr, M, Carralero, D, Castaldo, C, Cavedon, M, Cazzaniga, C, Ceccuzzi, S, Challis, C, Chankin, A, Chapman, S, Cianfarani, C, Clairet, F, Coda, S, Coelho, R, Coenen, J, Colas, L, Conway, G, Costea, S, Coster, D, Cote, T, Creely, A, Croci, G, Cseh, G, Czarnecka, A, Cziegler, I, D'Arcangelo, O, David, P, Day, C, Delogu, R, De Marne, P, Denk, S, Denner, P, Dibon, M, Di Siena, A, Douai, D, Drenik, A, Drube, R, Dunne, M, Duval, B, Dux, R, Eich, T, Elgeti, S, Engelhardt, K, Erdos, B, Erofeev, I, Esposito, B, Fable, E, Faitsch, M, Fantz, U, Faugel, H, Faust, I, Felici, F, Ferreira, J, Fietz, S, Figuereido, A, Fischer, R, Ford, O, Frassinetti, L, Freethy, S, Froschle, M, Fuchert, G, Fuchs, J, Funfgelder, H, Galazka, K, Galdon-Quiroga, J, Gallo, A, Gao, Y, Garavaglia, S, Garcia-Carrasco, A, Garcia-Munoz, M, Geiger, B, Giannone, L, Gil, L, Giovannozzi, E, Gleason-Gonzalez, C, Gloggler, S, Gobbin, M, Gorler, T, Gomez Ortiz, I, Gonzalez Martin, J, Goodman, T, Gorini, G, Gradic, D, Grater, A, Granucci, G, Greuner, H, Griener, M, Groth, M, Gude, A, Gunter, S, Guimarais, L, Haas, G, Hakola, A, Ham, C, Happel, T, Den Harder, N, Harrer, G, Harrison, J, Hauer, V, Hayward-Schneider, T, Hegna, C, Heinemann, B, Heinzel, S, Hellsten, T, Henderson, S, Hennequin, P, Herrmann, A, Heyn, M, Heyn, E, Hitzler, F, Hobirk, J, Hofler, K, Holzl, M, Hoschen, T, Holm, J, Hopf, C, Hornsby, W, Horvath, L, Houben, A, Huber, A, Igochine, V, Ilkei, T, Ivanova-Stanik, I, Jacob, W, Jacobsen, A, Janky, F, Jansen Van Vuuren, A, Jardin, A, Jaulmes, F, Jenko, F, Jensen, T, Joffrin, E, Kasemann, C, Kallenbach, A, Kalvin, S, Kantor, M, Kappatou, A, Kardaun, O, Karhunen, J, Kasilov, S, Kazakov, Y, Kernbichler, W, Kirk, A, Kjer Hansen, S, Klevarova, V, Kocsis, G, Kohn, A, Koubiti, M, Krieger, K, Krivska, A, Kramer-Flecken, A, Kudlacek, O, Kurki-Suonio, T, Kurzan, B, Labit, B, Lackner, K, Laggner, F, Lang, P, Lauber, P, Lebschy, A, Leuthold, N, Li, M, Linder, O, Lipschultz, B, Liu, F, Liu, Y, Lohs, A, Lu, Z, Luda Di Cortemiglia, T, Luhmann, N, Lunsford, R, Lunt, T, Lyssoivan, A, Maceina, T, Madsen, J, Maggiora, R, Maier, H, Maj, O, Mailloux, J, Maingi, R, Maljaars, E, Manas, P, Mancini, A, Manhard, A, Manso, M, Mantica, P, Mantsinen, M, Manz, P, Maraschek, M, Martens, C, Martin, P, Marrelli, L, Martitsch, A, Mayer, M, Mazon, D, Mccarthy, P, Mcdermott, R, Meister, H, Medvedeva, A, Merkel, R, Merle, A, Mertens, V, Meshcheriakov, D, Meyer, O, Miettunen, J, Milanesio, D, Mink, F, Mlynek, A, Monaco, F, Moon, C, Nabais, F, Nemes-Czopf, A, Neu, G, Neu, R, Nielsen, A, Nielsen, S, Nikolaeva, V, Nocente, M, Noterdaeme, J, Novikau, I, Nowak, S, Oberkofler, M, Oberparleiter, M, Ochoukov, R, Odstrcil, T, Olsen, J, Orain, F, Palermo, F, Pan, O, Papp, G, Paradela Perez, I, Pau, A, Pautasso, G, Penzel, F, Petersson, P, Pinzon Acosta, J, Piovesan, P, Piron, C, Pitts, R, Plank, U, Plaum, B, Ploeckl, B, Plyusnin, V, Pokol, G, Poli, E, Porte, L, Potzel, S, Prisiazhniuk, D, Putterich, T, Ramisch, M, Rasmussen, J, Ratta, G, Ratynskaia, S, Raupp, G, Ravera, G, Refy, D, Reich, M, Reimold, F, Reiser, D, Ribeiro, T, Riesch, J, Riedl, R, Rittich, D, Rivero-Rodriguez, J, Rocchi, G, Rodriguez-Ramos, M, Rohde, V, Ross, A, Rott, M, Rubel, M, Ryan, D, Ryter, F, Saarelma, S, Salewski, M, Salmi, A, Sanchis-Sanchez, L, Santos, J, Sauter, O, Scarabosio, A, Schall, G, Schmid, K, Schmitz, O, Schneider, P, Schrittwieser, R, Schubert, M, Schwarz-Selinger, T, Schweinzer, J, Scott, B, Sehmer, T, Seliunin, E, Sertoli, M, Shabbir, A, Shalpegin, A, Shao, L, Sharapov, S, Sias, G, Siccinio, M, Sieglin, B, Sigalov, A, Silva, A, Silva, C, Silvagni, D, Simon, P, Simpson, J, Smigelskis, E, Snicker, A, Sommariva, C, Sozzi, C, Spolaore, M, Stegmeir, A, Stejner, M, Stober, J, Stroth, U, Strumberger, E, Suarez, G, Sun, H, Suttrop, W, Sytova, E, Szepesi, T, Tal, B, Tala, T, Tardini, G, Tardocchi, M, Teschke, M, Terranova, D, Tierens, W, Thoren, E, Told, D, Tolias, P, Tudisco, O, Treutterer, W, Trier, E, Tripsky, M, Valisa, M, Valovic, M, Vanovac, B, Van Vugt, D, Varoutis, S, Verdoolaege, G, Vianello, N, Vicente, J, Vierle, T, Viezzer, E, Von Toussaint, U, Wagner, D, Wang, N, Wang, X, Weiland, M, White, A, Wiesen, S, Willensdorfer, M, Wiringer, B, Wischmeier, M, Wolf, R, Wolfrum, E, Xiang, L, Yang, Q, Yang, Z, Yu, Q, Zagorski, R, Zammuto, I, Zhang, W, Van Zeeland, M, Zehetbauer, T, Zilker, M, Zoletnik, S, Zohm, H, Meyer, H., Universidad de Sevilla, Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla. RNM138: Física Nuclear Aplicada, Universidad de Sevilla. TEP111: Ingeniería Mecánica, CEA Cadarache, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Culham Science Centre, Max-Planck-Institut für Plasmaphysik, Department of Applied Physics, Dutch Institute for Fundamental Energy Research, University of Lisbon, Eindhoven University of Technology, National Research Council of Italy, Princeton University, CEA, Forschungszentrum Jülich, Université de Lorraine, CNRS, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, University of Warwick, Swiss Federal Institute of Technology Lausanne, University of Innsbruck, University of Wisconsin-Madison, Massachusetts Institute of Technology, Hungarian Academy of Sciences, Soltan Institute for Nuclear Studies, University of York, Karlsruhe Institute of Technology, KTH Royal Institute of Technology, University of Seville, University of Milan - Bicocca, Fusion and Plasma Physics, VTT Technical Research Centre of Finland, Vienna University of Technology, Max-Planck Computing and Data Facility, General Atomics, Université Paris-Saclay, Graz University of Technology, Institut für Grenzflachenverfahrenstechnik und Plasmatechnologie, Danmarks Tekniske Universitet, Budapest University of Technology and Economics, Polish Academy of Sciences, Royal Military Academy, Ghent University, ITER Organization, University of California Davis, Polytechnic University of Turin, Barcelona Supercomputing Center, University College Cork, Chalmers University of Technology, University of Cagliari, ITER, CIEMAT, CAS - Institute of Plasma Physics, Max Planck Institute for Plasma Physics, Aalto-yliopisto, Aalto University, Angioni, C., Albert, C. G., Arden, N., Arredondo Parra, R., Asunta, O., De Baar, M., Balden, M., Bandaru, V., Behler, K., Bergmann, A., Bernardo, J., Bernert, M., Biancalani, A., Bilato, R., Birkenmeier, G., Blanken, T. C., Bobkov, V., Bock, A., Bolzonella, T., Bortolon, A., Boswirth, B., Bottereau, C., Bottino, A., Van Den Brand, H., Brezinsek, S., Brida, D., Brochard, F., Bruhn, C., Buchanan, J., Buhler, A., Burckhart, A., Camenen, Y., Carlton, D., Carr, M., Carralero, D., Castaldo, C., Cavedon, M., Cazzaniga, C., Ceccuzzi, S., Challis, C., Chankin, A., Chapman, S., Cianfarani, C., Clairet, F., Coda, S., Coelho, R., Coenen, J. W., Colas, L., Conway, G. D., Costea, S., Coster, D. P., Cote, T. B., Creely, A., Croci, G., Cseh, G., Czarnecka, A., Cziegler, I., D'Arcangelo, O., David, P., Day, C., Delogu, R., De Marne, P., Denk, S. S., Denner, P., Dibon, M., Di Siena, A., Douai, D., Drenik, A., Drube, R., Dunne, M., Duval, B. P., Dux, R., Eich, T., Elgeti, S., Engelhardt, K., Erdos, B., Erofeev, I., Esposito, B., Fable, E., Faitsch, M., Fantz, U., Faugel, H., Faust, I., Felici, F., Ferreira, J., Fietz, S., Figuereido, A., Fischer, R., Ford, O., Frassinetti, L., Freethy, S., Froschle, M., Fuchert, G., Fuchs, J. C., Funfgelder, H., Galazka, K., Galdon-Quiroga, J., Gallo, A., Gao, Y., Garavaglia, S., Garcia-Carrasco, A., Garcia-Munoz, M., Geiger, B., Giannone, L., Gil, L., Giovannozzi, E., Gleason-Gonzalez, C., Gloggler, S., Gobbin, M., Gorler, T., Gomez Ortiz, I., Gonzalez Martin, J., Goodman, T., Gorini, G., Gradic, D., Grater, A., Granucci, G., Greuner, H., Griener, M., Groth, M., Gude, A., Gunter, S., Guimarais, L., Haas, G., Hakola, A. H., Ham, C., Happel, T., Den Harder, N., Harrer, G. F., Harrison, J., Hauer, V., Hayward-Schneider, T., Hegna, C. C., Heinemann, B., Heinzel, S., Hellsten, T., Henderson, S., Hennequin, P., Herrmann, A., Heyn, M. F., Heyn, E., Hitzler, F., Hobirk, J., Hofler, K., Holzl, M., Hoschen, T., Holm, J. H., Hopf, C., Hornsby, W. A., Horvath, L., Houben, A., Huber, A., Igochine, V., Ilkei, T., Ivanova-Stanik, I., Jacob, W., Jacobsen, A. S., Janky, F., Jansen Van Vuuren, A., Jardin, A., Jaulmes, F., Jenko, F., Jensen, T., Joffrin, E., Kasemann, C. -P., Kallenbach, A., Kalvin, S., Kantor, M., Kappatou, A., Kardaun, O., Karhunen, J., Kasilov, S., Kazakov, Y., Kernbichler, W., Kirk, A., Kjer Hansen, S., Klevarova, V., Kocsis, G., Kohn, A., Koubiti, M., Krieger, K., Krivska, A., Kramer-Flecken, A., Kudlacek, O., Kurki-Suonio, T., Kurzan, B., Labit, B., Lackner, K., Laggner, F., Lang, P. T., Lauber, P., Lebschy, A., Leuthold, N., Li, M., Linder, O., Lipschultz, B., Liu, F., Liu, Y., Lohs, A., Lu, Z., Luda Di Cortemiglia, T., Luhmann, N. C., Lunsford, R., Lunt, T., Lyssoivan, A., Maceina, T., Madsen, J., Maggiora, R., Maier, H., Maj, O., Mailloux, J., Maingi, R., Maljaars, E., Manas, P., Mancini, A., Manhard, A., Manso, M. -E., Mantica, P., Mantsinen, M., Manz, P., Maraschek, M., Martens, C., Martin, P., Marrelli, L., Martitsch, A., Mayer, M., Mazon, D., Mccarthy, P. J., Mcdermott, R., Meister, H., Medvedeva, A., Merkel, R., Merle, A., Mertens, V., Meshcheriakov, D., Meyer, O., Miettunen, J., Milanesio, D., Mink, F., Mlynek, A., Monaco, F., Moon, C., Nabais, F., Nemes-Czopf, A., Neu, G., Neu, R., Nielsen, A. H., Nielsen, S. K., Nikolaeva, V., Nocente, M., Noterdaeme, J. -M., Novikau, I., Nowak, S., Oberkofler, M., Oberparleiter, M., Ochoukov, R., Odstrcil, T., Olsen, J., Orain, F., Palermo, F., Pan, O., Papp, G., Paradela Perez, I., Pau, A., Pautasso, G., Penzel, F., Petersson, P., Pinzon Acosta, J., Piovesan, P., Piron, C., Pitts, R., Plank, U., Plaum, B., Ploeckl, B., Plyusnin, V., Pokol, G., Poli, E., Porte, L., Potzel, S., Prisiazhniuk, D., Putterich, T., Ramisch, M., Rasmussen, J., Ratta, G. A., Ratynskaia, S., Raupp, G., Ravera, G. L., Refy, D., Reich, M., Reimold, F., Reiser, D., Ribeiro, T., Riesch, J., Riedl, R., Rittich, D., Rivero-Rodriguez, J. F., Rocchi, G., Rodriguez-Ramos, M., Rohde, V., Ross, A., Rott, M., Rubel, M., Ryan, D., Ryter, F., Saarelma, S., Salewski, M., Salmi, A., Sanchis-Sanchez, L., Santos, J., Sauter, O., Scarabosio, A., Schall, G., Schmid, K., Schmitz, O., Schneider, P. A., Schrittwieser, R., Schubert, M., Schwarz-Selinger, T., Schweinzer, J., Scott, B., Sehmer, T., Seliunin, E., Sertoli, M., Shabbir, A., Shalpegin, A., Shao, L., Sharapov, S., Sias, G., Siccinio, M., Sieglin, B., Sigalov, A., Silva, A., Silva, C., Silvagni, D., Simon, P., Simpson, J., Smigelskis, E., Snicker, A., Sommariva, C., Sozzi, C., Spolaore, M., Stegmeir, A., Stejner, M., Stober, J., Stroth, U., Strumberger, E., Suarez, G., Sun, H. -J., Suttrop, W., Sytova, E., Szepesi, T., Tal, B., Tala, T., Tardini, G., Tardocchi, M., Teschke, M., Terranova, D., Tierens, W., Thoren, E., Told, D., Tolias, P., Tudisco, O., Treutterer, W., Trier, E., Tripsky, M., Valisa, M., Valovic, M., Vanovac, B., Van Vugt, D., Varoutis, S., Verdoolaege, G., Vianello, N., Vicente, J., Vierle, T., Viezzer, E., Von Toussaint, U., Wagner, D., Wang, N., Wang, X., Weiland, M., White, A. E., Wiesen, S., Willensdorfer, M., Wiringer, B., Wischmeier, M., Wolf, R., Wolfrum, E., Xiang, L., Yang, Q., Yang, Z., Yu, Q., Zagorski, R., Zammuto, I., Zhang, W., Van Zeeland, M., Zehetbauer, T., Zilker, M., Zoletnik, S., Zohm, H., ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, and EUROfusion MST1 Team

Subjects
Magnetic confinement, Edge-localized modes (ELMs), Nuclear engineering, PLASMAS, Nuclear physics, 01 natural sciences, 010305 fluids & plasmas, ASDEX Upgrade, ITER, MODE, Physics, iter, Divertor, magnetic confinement, Magnetic confinement fusion, mode, Dissipation, Condensed Matter Physics, ddc, Tokamak physics, Física nuclear, tokamak physics, Tokamaks, FLUX, Nuclear and High Energy Physics, Technology and Engineering, DEMO, nuclear fusion, Electron cyclotron resonance, Resonant magnetic perturbations, Physics::Plasma Physics, 0103 physical sciences, Nuclear fusion, ddc:530, 010306 general physics, SOLID TUNGSTEN DIVERTOR, Física [Àrees temàtiques de la UPC], demo, plasmas, solid tungsten divertor, flux, ___, HEAVY ALLOYS, Magnetohydrodynamics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], heavy alloys
Abstract

The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q95 = 5.5, ) at low density. Higher installed electron cyclotron resonance heating power 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m−1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and Er allow for inter ELM transport analysis confirming that Er is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of 'natural' no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle—measured for the first time—or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. "Article signat per més de 100 autors/es: H. Meyer, for the AUG Team: D. Aguiam, C. Angioni, C.G. Albert, N. Arden, R. Arredondo Parra, O. Asunta, M. de Baar, M. Balden, V. Bandaru, K. Behler, A. Bergmann, J. Bernardo, M. Bernert, A. Biancalani, R. Bilato, G. Birkenmeier, T.C. Blanken, V. Bobkov, A. Bock, T. Bolzonella, A. Bortolon, B. Böswirth, C. Bottereau, A. Bottino, H. van den Brand, S. Brezinsek, D. Brida, F. Brochard, C. Bruhn, J. Buchanan, A. Buhler, A. Burckhart, Y. Camenen, D. Carlton, M. Carr, D. Carralero, C. Castaldo, M. Cavedon, C. Cazzaniga, S. Ceccuzzi, C. Challis, A. Chankin, S. Chapman, C. Cianfarani, F. Clairet, S. Coda, R. Coelho, J.W. Coenen, L. Colas, G.D. Conway, S. Costea, D.P. Coster, T.B. Cote, A. Creely, G. Croci, G. Cseh, A. Czarnecka, I. Cziegler, O. D'Arcangelo, P. David, C. Day, R. Delogu, P. de Marné, S.S. Denk, P. Denner, M. Dibon, A. Di Siena, D. Douai, A. Drenik, R. Drube, M. Dunne, B.P. Duval, R. Dux, T. Eich, S. Elgeti, K. Engelhardt, B. Erdös, I. Erofeev, B. Esposito, E. Fable, M. Faitsch, U. Fantz, H. Faugel, I. Faust, F. Felici, J. Ferreira, S. Fietz, A. Figuereido, R. Fischer, O. Ford, L. Frassinetti, S. Freethy, M. Fröschle, G. Fuchert, J.C. Fuchs, H. Fünfgelder, K. Galazka, J. Galdon-Quiroga, A. Gallo, Y. Gao, S. Garavaglia, A. Garcia-Carrasco, M. Garcia-Muñoz, B. Geiger, L. Giannone, L. Gil, E. Giovannozzi, C. Gleason-González, S. Glöggler, M. Gobbin, T. Görler, I. Gomez Ortiz, J. Gonzalez Martin, T. Goodman, G. Gorini, D. Gradic, A. Gräter, G. Granucci, H. Greuner, M. Griener, M. Groth, A. Gude, S. Günter, L. Guimarais, G. Haas, A.H. Hakola, C. Ham, T. Happel, N. den Harder, G.F. Harrer, J. Harrison, V. Hauer, T. Hayward-Schneider, C.C. Hegna, B. Heinemann, S. Heinzel, T. Hellsten, S. Henderson, P. Hennequin, A. Herrmann, M.F. Heyn, E. Heyn, F. Hitzler, J. Hobirk, K. Höfler, M. Hölzl, T. Höschen, J.H. Holm, C. Hopf, W.A. Hornsby, L. Horvath, A. Houben, A. Huber, V. Igochine, T. Ilkei, I. Ivanova-Stanik, W. Jacob, A.S. Jacobsen, F. Janky, A. Jansen van Vuuren, A. Jardin, F. Jaulmes, F. Jenko, T. Jensen, E. Joffrin, C.-P. Käsemann, A. Kallenbach, S. Kálvin, M. Kantor, A. Kappatou, O. Kardaun, J. Karhunen, S. Kasilov,, Y. Kazakov, W. Kernbichler, A. Kirk, S. Kjer Hansen, V. Klevarova, G. Kocsis, A. Köhn, M. Koubiti, K. Krieger, A. Krivska, A. Krämer-Flecken, O. Kudlacek, T. Kurki-Suonio, B. Kurzan, B. Labit, K. Lackner, F. Laggner, P.T. Lang, P. Lauber, A. Lebschy, N. Leuthold, M. Li, O. Linder, B. Lipschultz, F. Liu, Y. Liu, A. Lohs, Z. Lu, T. Luda di Cortemiglia, N.C. Luhmann, R. Lunsford, T. Lunt, A. Lyssoivan, T. Maceina, J. Madsen, R. Maggiora, H. Maier, O. Maj, J. Mailloux, R. Maingi, E. Maljaars, P. Manas, A. Mancini, A. Manhard, M.-E. Manso, P. Mantica, M. Mantsinen, P. Manz, M. Maraschek, C. Martens, P. Martin, L. Marrelli, A. Martitsch, M. Mayer, D. Mazon, P.J. McCarthy, R. McDermott, H. Meister, A. Medvedeva, R. Merkel, A. Merle, V. Mertens, D. Meshcheriakov, O. Meyer, J. Miettunen, D. Milanesio, F. Mink, A. Mlynek, F. Monaco, C. Moon, F. Nabais, A. Nemes-Czopf, G. Neu, R. Neu, A.H. Nielsen, S.K. Nielsen, V. Nikolaeva, M. Nocente, J.-M. Noterdaeme, I. Novikau, S. Nowak, M. Oberkofler, M. Oberparleiter, R. Ochoukov, T. Odstrcil, J. Olsen, F. Orain, F. Palermo, O. Pan, G. Papp, I. Paradela Perez, A. Pau, G. Pautasso, F. Penzel, P. Petersson, J. Pinzón Acosta, P. Piovesan, C. Piron, R. Pitts, U. Plank, B. Plaum, B. Ploeckl, V. Plyusnin, G. Pokol, E. Poli, L. Porte, S. Potzel, D. Prisiazhniuk, T. Pütterich, M. Ramisch, J. Rasmussen, G.A. Rattá, S. Ratynskaia, G. Raupp, G.L. Ravera, D. Réfy, M. Reich, F. Reimold, D. Reiser, T. Ribeiro, J. Riesch, R. Riedl, D. Rittich, J.F. Rivero-Rodriguez, G. Rocchi, M. Rodriguez-Ramos, V. Rohde, A. Ross1, M. Rott, M. Rubel, D. Ryan, F. Ryter, S. Saarelma, M. Salewski, A. Salmi, L. Sanchis-Sanchez, J. Santos, O. Sauter, A. Scarabosio, G. Schall, K. Schmid, O. Schmitz, P.A. Schneider, R. Schrittwieser, M. Schubert, T. Schwarz-Selinger, J. Schweinzer, B. Scott, T. Semer, E. Seliunin, M. Sertoli, A. Shabbir, A. Shalpegin, L. Shao, S. Sharapov, G. Sias, M. Siccinio, B. Sieglin, A. Sigalov, A. Silva, C. Silva, D. Silvagni, P. Simon, J. Simpson, E. Smigelskis, A. Snicker, C. Sommariva, C. Sozzi, M. Spolaore, A. Stegmeir, M. Stejner, J. Stober, U. Stroth, E. Strumberger, G. Suarez, H.-J. Sun, W. Suttrop, E. Sytova, T. Szepesi, B. Tál, T. Tala, G. Tardini, M. Tardocchi, M. Teschke, D. Terranova, W. Tierens, E. Thorén, D. Told, P. Tolias, O. Tudisco, W. Treutterer, E. Trier, M. Tripský, M. Valisa, M. Valovic, B. Vanovac, D. van Vugt, S. Varoutis, G. Verdoolaege, N. Vianello, J. Vicente, T. Vierle, E. Viezzer, U. von Toussaint, D. Wagner, N. Wang, X. Wang, M. Weiland, A.E. White, S. Wiesen, M. Willensdorfer, B. Wiringer, M. Wischmeier, R. Wolf, E. Wolfrum, L. Xiang, Q. Yang, Z. Yang, Q. Yu, R. Zagórski, I. Zammuto, W. Zhang, M. van Zeeland, T. Zehetbauer, M. Zilker, S. Zoletnik, H. Zohm and the EUROfusion MST1 Team55

Published
2018
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40. Plasma response measurements of external magnetic perturbations using electron cyclotron emission and comparisons to 3D ideal MHD equilibrium

Author

Willensdorfer, M., Denk, S.S., Strumberger, E., Suttrop, W., Vanovac, B., Brida, D., Cavedon, M., Classen, I., Dunne, M., Fietz, S., Fischer, R., Kirk, A., Laggner, F.M., Liu, Y.Q., Odstrcil, T., Ryan, D.A., Viezzer, E., Zohm, H., Luhmann, I.C., Team, ASDEXUpgrade, Team, EUROfusionMST1, Science and Technology of Nuclear Fusion, Willensdorfer, M, Denk, S, Strumberger, E, Suttrop, W, Vanovac, B, Brida, D, Cavedon, M, Classen, I, Dunne, M, Fietz, S, Fischer, R, Kirk, A, Laggner, F, Liu, Y, Odstrcil, T, Ryan, D, Viezzer, E, Zohm, H, Luhmann, I, ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, and EUROfusion MST1 Team

Subjects
ideal MHD, Cyclotron, FOS: Physical sciences, Perturbation (astronomy), Electron, 01 natural sciences, 7. Clean energy, Vertical bar, 010305 fluids & plasmas, law.invention, ASDEX Upgrade, law, Physics::Plasma Physics, 0103 physical sciences, ECE imaging, magnetic perturbations, ECE, 010306 general physics, plasma response, Physics, magnetic perturbation, Plasma, Condensed Matter Physics, Physics - Plasma Physics, Computational physics, Plasma Physics (physics.plasm-ph), Amplitude, Nuclear Energy and Engineering, Magnetohydrodynamics
Abstract

The plasma response from an external n = 2 magnetic perturbation field in ASDEX Upgrade has been measured using mainly electron cyclotron emission (ECE) diagnostics and a rigid rotating field. To interpret ECE and ECE-imaging (ECE-I) measurements accurately, forward modeling of the radiation transport has been combined with ray tracing. The measured data is compared to synthetic ECE data generated from a 3D ideal magnetohydrodynamics (MHD) equilibrium calculated by VMEC. The measured amplitudes of the helical displacement around the low field side midplane are in reasonable agreement with the one from the synthetic VMEC diagnostics. Both exceed the prediction from the vacuum field calculations and indicate the presence of a kink response at the edge, which amplifies the perturbation. VMEC and MARS-F have been used to calculate the properties of this kink mode. The poloidal mode structure of the magnetic perturbation of this kink mode at the edge peaks at poloidal mode numbers larger than the resonant components |m| > |nq|, whereas the poloidal mode structure of its displacement is almost resonant |m| ~ |nq|. This is expected from ideal MHD in the proximity of rational surfaces. The displacement measured by ECE-I confirms this resonant response., 34 pages, 19 figures. This is an author-created, un-copyedited version of an article submitted for publication in Plasma Physics and Controlled Fusion. IoP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it

Published
2016

41. DIII-D research towards establishing the scientific basis for future fusion reactors

Author

L. Abadie, T. W. Abrams, J. Ahn, T. Akiyama, P. Aleynikov, J. Allcock, E. O. Allen, S. Allen, J. P. Anderson, A. Ashourvan, M. E. Austin, J. Bak, K. K. Barada, N. Barbour, L. Bardoczi, J. Barr, J. L. Barton, E. M. Bass, D. Battaglia, L. R. Baylor, J. Beckers, E. A. Belli, J. W. Berkery, N. Bertelli, J. M. Bialek, J. A. Boedo, R. L. Boivin, P. T. Bonoli, A. Bortolon, M. D. Boyer, R. E. Brambila, B. Bray, D. P. Brennan, A. R. Briesemeister, S. A. Bringuier, M. W. Brookman, D. L. Brower, B. R. Brown, W. D. Brown, D. Buchenauer, M. G. Burke, K. H. Burrell, J. Butt, R. J. Buttery, I. Bykov, J. M. Candy, J. M. Canik, N. M. Cao, L. Carbajal Gomez, L. C. Carlson, T. N. Carlstrom, T. A. Carter, W. Cary, L. Casali, M. Cengher, V. S. Chan, B. Chen, J. Chen, M. Chen, R. Chen, Xi Chen, W. Choi, C. Chrobak, C. Chrystal, R. M. Churchill, M. Cianciosa, C. F. Clauser, M. Clement, J. Coburn, C. S. Collins, A. W. Cooper, B. M. Covele, J. W. Crippen, N. A. Crocker, B. J. Crowley, A. Dal Molin, E. M. 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J, Donovan, D, Drake, J, Du, D, Du, H, Du, X, Duarte, V, Duran, J, Eidietis, N, Elder, D, Eldon, D, Elwasif, W, Ely, T, Eng, K, Engelhorn, K, Ennis, D, Erickson, K, Ernst, D, Evans, T, Fenstermacher, M, Ferraro, N, Ferron, J, Finkenthal, D, Fisher, P, Fishler, B, Flanagan, S, Fooks, J, Frassinetti, L, Frerichs, H, Fu, Y, Fulop, T, Gao, Q, Garcia, F, Garofalo, A, Gattuso, A, Giacomelli, L, Giraldez, E, Giroud, C, Glass, F, Gohil, P, Gong, X, Gorelov, Y, Granetz, R, Green, D, Greenfield, C, Grierson, B, Groebner, R, Grosnickle, W, Groth, M, Grunloh, H, Guo, H, Guo, W, Guterl, J, Hager, R, Hahn, S, Halpern, F, Han, H, Hansink, M, Hanson, J, Harris, J, Haskey, S, Hatch, D, Heidbrink, W, Herfindal, J, Hill, D, Hill, M, Hinson, E, Holcomb, C, Holland, C, Holland, L, Hollmann, E, Holm, A, Hong, R, Hoppe, M, Houshmandyar, S, Howard, J, Howard, N, Hu, Q, Hu, W, Huang, H, Huang, J, Huang, Y, Hughes, G, Hughes, J, Humphreys, D, Hyatt, A, Ida, K, Igochine, V, In, Y, Inoue, S, Isayama, A, Isler, R, Izzo, V, Jackson, M, Jarvinen, A, Jeon, Y, Ji, H, Jian, X, Jimenez, R, Johnson, C, Joseph, I, Kaczala, D, Kaplan, D, Kates-Harbeck, J, Kellman, A, Kellman, D, Kessel, C, Khumthong, K, Kim, C, Kim, H, Kim, J, Kim, K, Kim, S, Kimura, W, King, J, Kirk, A, Kleijwegt, K, Knolker, M, Kohn, A, Kolemen, E, Kostuk, M, Kramer, G, Kress, P, Kriete, D, La Haye, R, Laggner, F, Lan, H, Lanctot, M, Lantsov, R, Lao, L, Lasnier, C, Lau, C, Law, K, Lawrence, D, Le, J, Lee, R, Lehnen, M, Leon, R, Leonard, A, Lesher, M, Leuer, J, Li, G, Li, K, Liao, K, Lin, Z, Liu, C, Liu, F, Liu, Y, Liu, Z, Loch, S, Logan, N, Lohr, J, Lore, J, Luce, T, Luhmann, N, Lunsford, R, Luo, C, Luo, Z, Lupin-Jimenez, L, Lvovskiy, A, Lyons, B, Ma, X, Maingi, R, Makowski, M, Mantica, P, Manuel, M, Margo, M, Marinoni, A, Marmar, E, Martin, W, Masline, R, Matsunaga, G, Mauzey, D, Mauzey, P, Mcclenaghan, J, Mckee, G, Mclean, A, Mclean, H, Meier, E, Meitner, S, Menard, J, Meneghini, O, Merlo, G, Meyer, W, Miller, D, Miller, W, Moeller, C, Montes, K, Morales, M, Mordijck, S, Moser, A, Moyer, R, Muller, S, Munaretto, S, Murakami, M, Murphy, C, Muscatello, C, Myers, C, Nagy, A, Navratil, G, Nazikian, R, Neff, A, Neiser, T, Nelson, A, Nguyen, P, Nguyen, R, Nichols, J, Nocente, M, Nygren, R, O'Neill, R, Odstrcil, T, Ohdachi, S, Okabayashi, M, Olofsson, E, Ono, M, Orlov, D, Osborne, T, Pablant, N, Pace, D, Paguio, R, Pajares Martinez, A, Pan, C, Pankin, A, Park, J, Park, Y, Parker, C, Parker, S, Parks, P, Pawley, C, Paz-Soldan, C, Peebles, W, Penaflor, B, Petrie, T, Petty, C, Peysson, Y, Pigarov, A, Piglowski, D, Pinsker, R, Piovesan, P, Piper, N, Pitts, R, Pizzo, J, Podesta, M, Poli, F, Ponce, D, Porkolab, M, Porter, G, Prater, R, Qian, J, Ra, O, Rafiq, T, Raman, R, Rand, C, Randall, G, Rauch, J, Rea, C, Reinke, M, Ren, J, Ren, Q, Ren, Y, Rhodes, T, Rice, J, Rognlien, T, Rost, J, Rowan, W, Rudakov, D, Salmi, A, Sammuli, B, Samuell, C, Sandorfi, A, Sang, C, Sauter, O, Schissel, D, Schmitz, L, Schmitz, O, Schuster, E, Scoville, J, Seltzman, A, Sfiligoi, I, Shafer, M, Shen, H, Shi, T, Shiraki, D, Si, H, Smith, D, Smith, S, Snipes, J, Snyder, P, Solano, E, Solomon, W, Sontag, A, Soukhanovskii, V, Spong, D, Stacey, W, Staebler, G, Stagner, L, Stahl, B, Stangeby, P, Stoltzfus-Dueck, T, Stotler, D, Strait, E, Su, D, Sugiyama, L, Sulyman, A, Sun, Y, Sung, C, Suttrop, W, Suzuki, Y, Svyatkovskiy, A, Sweeney, R, Taimourzadeh, S, Takechi, M, Tala, T, Tan, H, Tang, S, Tang, X, Taussig, D, Taylor, G, Taylor, N, Taylor, T, Teklu, A, Thomas, D, Thomas, M, Thome, K, Thorman, A, Tinguely, R, Tobias, B, Tooker, J, Torreblanca, H, Torrezan De Sousa, A, Trevisan, G, Truong, D, Turco, F, Turnbull, A, Unterberg, E, Vaezi, P, Vail, P, Van Zeeland, M, Velasco Enriquez, M, Venkatesh, M, Victor, B, Volpe, F, Wade, M, Walker, M, Wall, J, Wallace, G, Waltz, R, Wang, G, Wang, H, Wang, Y, Wang, Z, Wang, F, Ward, S, Watkins, J, Watkins, M, Wehner, W, Weiland, M, Weisberg, D, Welander, A, White, A, White, R, Whyte, D, Wijkamp, T, Wilcox, R, Wilks, T, Wilson, H, Wingen, A, Wolfe, E, Wu, M, Wu, W, Wukitch, S, Xia, T, Xiang, N, Xiao, B, Xie, R, Xu, G, Xu, H, Xu, X, Yan, Z, Yang, Q, Yang, X, Yoshida, M, Yu, G, Yu, J, Yu, M, Zamperini, S, Zeng, L, Zhao, B, Zhao, D, Zhao, H, Zhao, Y, Zhu, Y, and Zywicki, B

Subjects
Physics, Nuclear and High Energy Physics, fusion, model, Tokamak, DIII-D, Divertor, Mechanics, Plasma, Fusion power, Dissipation, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Pedestal, Heat flux, law, Physics::Plasma Physics, 0103 physical sciences, 010306 general physics, tokamak, plasma, energy
Abstract

DIII-D research is addressing critical challenges in preparation for ITER and the next generation of fusion devices through focusing on plasma physics fundamentals that underpin key fusion goals, understanding the interaction of disparate core and boundary plasma physics, and developing integrated scenarios for achieving high performance fusion regimes. Fundamental investigations into fusion energy science find that anomalous dissipation of runaway electrons (RE) that arise following a disruption is likely due to interactions with RE-driven kinetic instabilities, some of which have been directly observed, opening a new avenue for RE energy dissipation using naturally excited waves. Dimensionless parameter scaling of intrinsic rotation and gyrokinetic simulations give a predicted ITER rotation profile with significant turbulence stabilization. Coherence imaging spectroscopy confirms near sonic flow throughout the divertor towards the target, which may account for the convection-dominated parallel heat flux. Core-boundary integration studies show that the small angle slot divertor achieves detachment at lower density and extends plasma cooling across the divertor target plate, which is essential for controlling heat flux and erosion. The Super H-mode regime has been extended to high plasma current (2.0 MA) and density to achieve very high pedestal pressures (~30 kPa) and stored energy (3.2 MJ) with H 98y2 ≈ 1.6–2.4. In scenario work, the ITER baseline Q = 10 scenario with zero injected torque is found to have a fusion gain metric independent of current between q 95 = 2.8–3.7, and a lower limit of pedestal rotation for RMP ELM suppression has been found. In the wide pedestal QH-mode regime that exhibits improved performance and no ELMs, the start-up counter torque has been eliminated so that the entire discharge uses ≈0 injected torque and the operating space is more ITER-relevant. Finally, the high- (⩽3.8) hybrid scenario has been extended to the high-density levels necessary for radiating divertor operation, achieving ~40% divertor heat flux reduction using either argon or neon with P tot up to 15 MW.

Published
2019
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42. On the Origins of Mars' Exospheric Nonthermal Oxygen Component as Observed by MAVEN and Modeled by HELIOSARES

Author

François Leblanc, Bruce M. Jakosky, Robert E. Johnson, Justin Deighan, Jasper Halekas, Jean-Yves Chaufray, F. Gonzalez-Galindo, Ludivine Leclercq, Frank Eparvier, Mehdi Benna, J. P. McFadden, Ronan Modolo, Paul R. Mahaffy, Robert Lillis, Takuya Hara, Miguel Lopez-Valverde, Janet G. Luhmann, François Forget, Shannon Curry, and Nicholas M. Schneider

Subjects
Martian, Physics, 010504 meteorology & atmospheric sciences, Magnetosphere, Atmosphere of Mars, Mars Exploration Program, 01 natural sciences, Astrobiology, Atmosphere, Solar wind, Geophysics, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Ionosphere, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Exosphere
Abstract

The first measurements of the emission brightness of the oxygen atomic exosphere by Mars Atmosphere and Volatile EvolutioN (MAVEN) mission have clearly shown that it is composed of a thermal component produced by the extension of the upper atmosphere and of a non-thermal component. Modeling these measurements allows us to constrain the origins of the exospheric O and, as a consequence, to estimate Mars' present oxygen escape rate. We here propose an analysis of three periods of MAVEN observations based on a set of three coupled models: a hybrid magnetospheric model (LatHyS), an Exospheric General Model (EGM) and the Global Martian Circulation model of the Laboratoire de Meteorologie Dynamique (LMD-GCM), which provide a description of Mars' environment from the surface up to the solar wind. The simulated magnetosphere by LatHyS is in good agreement with MAVEN Plasma and Field Package instruments data. The LMD-GCM modeled upper atmospheric profiles for the main neutral and ion species are compared to NGIMS/MAVEN data showing that the LMD-GCM can provide a satisfactory global view of Mars' upper atmosphere. Finally, we were able to reconstruct the expected emission brightness intensity from the oxygen exosphere using EGM. The good agreement with the averaged measured profiles by IUVS during these three periods suggests that Mars' exospheric non-thermal component can be fully explained by the reactions of dissociative recombination of the O2+ ion in Mars' ionosphere, limiting significantly our ability to extract information from MAVEN observations of the O exosphere on other non-thermal processes, such as sputtering.

Published
2017
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43. Solar Wind Interaction and Impact on the Venus Atmosphere

Author

Gabriella Stenberg Wieser, Janet G. Luhmann, Stas Barabash, and Yoshifumi Futaana

Subjects
Physics, 010504 meteorology & atmospheric sciences, biology, Astronomy, Magnetosphere, Astronomy and Astrophysics, Venus, Space physics, biology.organism_classification, Bow shocks in astrophysics, 01 natural sciences, Astrobiology, Atmosphere of Venus, Solar wind, Magnetosheath, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of “Earth’s Twin”. Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA’s probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models, describing the plasma interaction on scales ranging from ion gyro radius to the entire induced magnetosphere. In this review article, we review what has been found from space physics measurements around Venus (from the solar wind down to the ionopause), with a particular emphasis on updated results since the Venus Express mission. We conclude the article by a short discussion on the remaining open scientific questions and the future of this field.

Published
2017
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44. On the origins of magnetic flux ropes in near-Mars magnetotail current sheets

Author

David Brain, Bruce M. Jakosky, Christian Mazelle, Gina A. DiBraccio, Jared Espley, Jasper Halekas, Yuki Harada, David L. Mitchell, James P. McFadden, Kanako Seki, Takuya Hara, and Janet G. Luhmann

Subjects
Martian, Physics, 010504 meteorology & atmospheric sciences, Flux, Atmosphere of Mars, Mars Exploration Program, Geophysics, 01 natural sciences, Magnetic flux, Current sheet, Physics::Space Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Current (fluid), Ionosphere, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

We analyze Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of magnetic flux ropes embedded in Martian magnetotail current sheets, in order to evaluate the role of magnetotail reconnection in their generations. We conduct a minimum variance analysis to infer the generation processes of magnetotail flux ropes from the geometrical configuration of the individual flux rope axial orientation with respect to the overall current sheet. Of 23 flux ropes detected in current sheets in the near-Mars (∼1–3 Martian radii downstream) magnetotail, only 3 (possibly 4) can be explained by the magnetotail reconnection scenario, while the vast majority of the events (19 events) are more consistent with flux ropes that are originally generated in the dayside ionosphere and subsequently transported into the nightside magnetotail. The mixed origins of the detected flux ropes imply complex nature of generation and transport of Martian magnetotail flux ropes.

Published
2017
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45. Prospects for Modeling and Forecasting SEP Events with ENLIL and SEPMOD

Author

Yan Li, Janet G. Luhmann, Christina O. Lee, M. L. Mays, Christina Cohen, Hazel Bain, Yoshifumi Futaana, R. A. Mewaldt, Dusan Odstrcil, and R. A. Leske

Subjects
Physics, Solar energetic particles, Space and Planetary Science, Coronal mass ejection, Astronomy and Astrophysics, Geophysics, Interplanetary magnetic field, Space weather, Interplanetary spaceflight, Event (particle physics), Heliosphere, Shock (mechanics)
Abstract

One view of major Solar Energetic Particle (SEP) events is that these (proton-dominated) fluxes are accelerated in heliospheric shock sources created by Interplanetary Coronal Mass Ejections (ICMEs), and then travel mainly along interplanetary magnetic field lines connecting the shock(s) to the observer(s). This places a particular emphasis on the role of the heliospheric conditions during the event, requiring a realistic description of the latter to interpret and/or model SEP events. The well-known ENLIL heliospheric simulation with cone model generated ICME shocks is used together with the SEPMOD particle event modeling scheme to demonstrate the value of applying these concepts at multiple inner heliosphere sites.

Published
2017
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46. 0.2-THz Dual Mode Sheet Beam Traveling Wave Tube

Author

Diana Gamzina, Yuan Zheng, and Neville C. Luhmann

Subjects
010302 applied physics, Physics, Beam diameter, business.industry, Traveling-wave tube, 01 natural sciences, 010305 fluids & plasmas, Electronic, Optical and Magnetic Materials, law.invention, Current sheet, Optics, law, 0103 physical sciences, Cathode ray, Continuous wave, Laser beam quality, Electrical and Electronic Engineering, business, Beam (structure), Electron gun
Abstract

Equipping the adjustable horizontal focusing electrodes (FEs), a dual mode electron gun providing different current beams, has been proposed and evaluated. Employing this tunable FE electron gun, a continuous wave (CW)/pulsed dual mode, 0.2-THz sheet beam traveling wave tube (SB-TWT) has been designed. The tube employs a high density and high current sheet beam for pulsed mode operation, and a reduced size and lower current sheet beam for the CW mode. This scheme provides CW mode increased efficiency and higher beam transmission factor than other, more conventional, dualmode techniques such as by changing the RF drive power. Using a 1.2-T uniform focusing magnetic field, both beams are predicted to have excellent transmission factor (more than 99%) to the collector through the 65-mm beam tunnel. Driven by the pulsed, high current electron beam, the 0.2-THz SB-TWT exhibits more than 100-W power over a 20-GHz bandwidth. Driven by the low current electron beam, the tube provides 20-dB gain and 10-W CW output power over the required bandwidth of 0.19 THz–0.21 THz.

Published
2017
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47. Spike-wave discharges in absence epilepsy: segregation of electrographic components reveals distinct pathways of seizure activity

Author

Thomas Seidenbecher, Heiko J. Luhmann, Jonas Terlau, Annika Lüttjohann, Jenq-Wei Yang, Hans-Christian Pape, and Zeinab Khastkhodaei

Subjects
0301 basic medicine, Physiology, Thalamus, Local field potential, 03 medical and health sciences, Epilepsy, 0302 clinical medicine, Childhood absence epilepsy, Seizures, medicine, Animals, Humans, Child, Physics, Cerebral Cortex, Neurons, Quantitative Biology::Neurons and Cognition, Spike-and-wave, Electroencephalography, medicine.disease, Patient Discharge, Rats, Electrophysiology, 030104 developmental biology, Epilepsy, Absence, Spike (software development), Centromedian nucleus, Neuroscience, 030217 neurology & neurosurgery
Abstract

Key points The major electrophysiological hallmarks of absence seizures are spike and wave discharges (SWDs), consisting of a sharp spike component and a slow wave component. In a widely accepted scheme, these components are functionally coupled and reflect an iterative progression of neuronal excitation during the spike and post-excitatory silence during the wave. In a genetic rat model of absence epilepsy, local pharmacological inhibition of the centromedian thalamus (CM) selectively suppressed the spike component, leaving self-contained waves in epidural recordings. Thalamic inputs induced activity in cortical microcircuits underlying the spike component, while intracortical oscillations generated the wave component. Based on these findings, we propose a model in which oscillatory waves provide adequate time windows for integration of thalamocortical inputs and feedback responses during generation of a synchronized SWD. Abstract Spike and wave discharges (SWDs) are the electrographic hallmark of absence seizures and the major diagnostic criterion for childhood absence epilepsy (CAE). In a widely accepted scheme, the alternating sequence of spikes and waves reflects an iterative progression of neuronal excitation during the spike component and post-excitatory silence during the wave component. Here we challenge this view by showing that these two components are not necessarily coupled. In a genetic rat model of CAE, self-contained waves occurred in motor cortex in synchrony with SWDs in the somatosensory system during blockade of afferent input from the thalamus. Current-source density analyses of multi-site local field potentials (LFPs) revealed layer-specific activity, in which thalamic inputs induced a sequence of cellular-synaptic events underlying the spike component, while intracortical oscillations generated the wave component. These findings indicate novel principles of SWDs, where oscillatory cortical waves provide adequate time windows for integration of thalamocortical inputs and feedback responses during generation of seizure activity.

Published
2019

48. First in situ evidence of Mars nonthermal exosphere

Author

Antoine Martinez, Robert Lillis, Paul Mahaffy, Ronan Modolo, Bruce M. Jakosky, Shannon Curry, Janet G. Luhmann, François Leblanc, Meredith Elrod, Jean-Yves Chaufray, Mehdi Benna, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), NASA Goddard Space Flight Center (GSFC), University of Maryland [Baltimore County] (UMBC), University of Maryland System, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), and University of Colorado [Boulder]

Subjects
Physics, 010504 meteorology & atmospheric sciences, Atmospheric escape, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Scale height, Astrophysics, Mars Exploration Program, Effects of high altitude on humans, 010502 geochemistry & geophysics, 01 natural sciences, Pickup Ion, Geophysics, Altitude, General Earth and Planetary Sciences, Dissociative recombination, 0105 earth and related environmental sciences, Exosphere
Abstract

International audience; Dedicated in‐situ measurements of Mars' exospheric Ar density by NGIMS/MAVEN highlight profiles displaying two slopes altitude variation. Below 230 km, the Ar density is characterized by scale height of 13.5 ± 1.7 km and above 400 km by scale height of 156 ± 25 km. A comparison with the model HELIOSARES suggests that the most probable origin of the Ar non‐thermal component is the collisional interaction, below the exobase, between the atmospheric Ar and the non‐thermal O atoms produced by the dissociative recombination of O2+. These measurements therefore provide a new approach to constrain one of the main source of Mars' atmospheric escape. They also lead to set up an upper limit on the efficiency of pickup ion sputtering at Mars. The comparison with HELIOSARES suggests that NGIMS detection sensitivity might allow a positive detection of this mechanism if more measurements at high altitude deep in the nightside are performed.

Published
2019
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49. Solar Terrestrial Relations Observatory (STEREO) Observations of Stream Interaction Regions in 2007 – 2016: Relationship with Heliospheric Current Sheets, Solar Cycle Variations, and Dual Observations

Author

Janet G. Luhmann, Lan Jian, Christopher T. Russell, and Antoinette B. Galvin

Subjects
Physics, 010504 meteorology & atmospheric sciences, Shock (fluid dynamics), Mesoscale meteorology, Lagrangian point, Coronal hole, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Article, Solar cycle, Solar wind, Space and Planetary Science, Observatory, 0103 physical sciences, Heliospheric current sheet, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

We have conducted a survey of 575 slow-to-fast stream interaction regions (SIRs) using Solar Terrestrial Relations Observatory (STEREO) A and B data, analyzing their properties while extending a Level-3 data product through 2016. Among 518 pristine SIRs, 54% are associated with heliospheric current sheet (HCS) crossings, and 34% are without any HCS crossing. The other 12% of the SIRs often occur in association with magnetic sectors shorter than three days. The SIRs with HCS crossings have slightly slower speeds but higher maximum number densities, magnetic-field strengths, dynamic pressures, and total pressures than the SIRs without an HCS. The iron charge state is higher throughout the SIRs with an HCS than the SIRs without an HCS, by about $1/3$ charge unit. In contrast with the comparable phases of Solar Cycle 23, slightly more SIRs and higher recurrence rates are observed in the years 2009 – 2016 of Cycle 24, with a lower HCS association rate, possibly attributed to persistent equatorial coronal holes and more pseudo-streamers in this recent cycle. The solar-wind speed, peak magnetic field, and peak pressures of SIRs are all lower in this cycle, but the weakening is less than for the comparable background solar-wind parameters. Before STEREO-B lost contact in October 2014, 151 SIR pairs were observed by the twin spacecraft. Of the dual observations, the maximum speed is the best correlated of the plasma parameters. We have obtained a sample of plasma-parameter differences analogous to those that would be observed by a mission at Lagrange points 4 or 5. By studying several cases with large discrepancies between the dual observations, we investigate the effects of HCS relative location, tilt of stream interface, and small transients on the SIR properties. To resolve the physical reasons for the variability of SIR structures, mesoscale multi-point observations and time-dependent solar-wind modeling are ultimately required.

Published
2019
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50. Noise suppression for MHD characterization with electron cyclotron emission imaging 1D technique

Author

Max E Austin, Neville C. Luhmann, Xiaoliang Li, Ying Chen, Guanying Yu, Yingchu Wang, Yang Ren, J.H. Yu, Xianzi Liu, Yilun Zhu, Bingzhe Zhao, G. J. Kramer, Ahmed Diallo, and J. H. Cao

Subjects
Physics, Noise suppression, Nuclear Energy and Engineering, law, Cyclotron, Electron, Magnetohydrodynamics, Condensed Matter Physics, Image resolution, Characterization (materials science), law.invention, Computational physics
Abstract

Significant noise suppression for magnetohydrodynamics (MHD) mode characterization in the spatial and spectral domain is achieved by processing two-dimensional (2D) electron cyclotron emission imaging (ECEI) data with a one-dimensional (1D) ECEI technique using a short time window ( 1 ms ). The technique is applied to detect toroidal Alfven eigenmodes (TAEs) in the temporal spectrum and fit their radial envelope using the data from the DIII-D tokamak W-band 2D ECEI system. Using the data length (time window) of only 1 ms , the 1D ECEI can clearly detect the TAEs (∼100 kHz ) on the spectrum, while similar spectrum quality requires ∼10 ms data length with the cross power spectrum between two midplane ECEI channels. The 1D ECEI technique also effectively avoids biased fitting when resolving the fine structure of the TAE’s radial envelope. The radially spatial resolution of 1D ECEI is constrained by the finite ECE radiation volume of the ECEI receiver. With forward radiation modeling, we find the DIII-D ECEI system can sensitively measure the even parity MHD activities, for which the mode width is >15 mm, and tearing modes (odd parity MHD activities), for which the island full width is >30 mm.

Published
2021
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