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1. Overview of the first Wendelstein 7-X long pulse campaign with fully water-cooled plasma facing components.

Author

Grulke, O., Albert, C., Alcuson Belloso, J.A., Aleynikov, P., Aleynikova, K., Alonso, A., Anda, G., Andreeva, T., Arvanitou, M., Ascasibar, E., Aymerich, E., Avramidis, K., Bähner, J.-P., Baek, S.-G., Balden, M., Baldzuhn, J., Ballinger, S., Banduch, M., Bannmann, S., and Bañón Navarro, A.

Subjects
*ELECTRON cyclotron resonance heating, *COOLING of water, *PLASMA beam injection heating, *HEAT flux, *ENTHALPY, *PLASMA heating, *MAGNETIC measurements
Abstract

After a long device enhancement phase, scientific operation resumed in 2022. The main new device components are the water cooling of all plasma facing components and the new water-cooled high heat flux divertor units. Water cooling allowed for the first long-pulse operation campaign. A maximum discharge length of 8 min was achieved with a total heating energy of 1.3 GJ. Safe divertor operation was demonstrated in attached and detached mode. Stable detachment is readily achieved in some magnetic configurations but requires impurity seeding in configurations with small magnetic pitch angle within the edge islands. Progress was made in the characterization of transport mechanisms across edge magnetic islands: Measurement of the potential distribution and flow pattern reveals that the islands are associated with a strong poloidal drift, which leads to rapid convection of energy and particles from the last closed flux surface into the scrape-off layer. Using the upgraded plasma heating systems, advanced heating scenarios were developed, which provide improved energy confinement comparable to the scenario, in which the record triple product for stellarators was achieved in the previous operation campaign. However, a magnetic configuration-dependent critical heating power limit of the electron cyclotron resonance heating was observed. Exceeding the respective power limit leads to a degradation of the confinement. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Correction to ‘Proton-driven plasma wakefield acceleration in AWAKE’

Author

The AWAKE Collaboration, Gschwendtner, E., Turner, M., Adli, E., Ahuja, A., Apsimon, O., Apsimon, R., Bachmann, A.-M., Batsch, F., Bracco, C., Braunmüller, F., Burger, S., Burt, G., Buttenschön, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D., Damerau, H., Deubner, L. H., Dexter, A., Doebert, S., Farmer, J., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Grulke, O., Hartin, A., Helm, A., Henderson, J. R., Hüther, M., Ibison, M., Jolly, S., Keeble, F., Kelisani, M. D., Kim, S.-Y., Kraus, F., Krupa, M., Lefevre, T., Li, Y., Liu, S., Lopes, N., Lotov, K. V., Martyanov, M., Mazzoni, S., Minakov, V. A., Molendijk, J. C., Moody, J. T., Moreira, M., Muggli, P., Panuganti, H., Pardons, A., Asmus, F. Peña, Perera, A., Petrenko, A., Pukhov, A., Rey, S., Sherwood, P., Silva, L. O., Sosedkin, A. P., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Wendt, M., Williamson, B., Wing, M., Woolley, B., and Xia, G.

Published
2020

4. Wendelstein 7-X on the path to long-pulse high-performance operation

Author

Endler, M., Baldzuhn, J., Beidler, C.D., Bosch, H.-S., Bozhenkov, S., Buttenschön, B., Dinklage, A., Fellinger, J., Feng, Y., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Hartmann, D., Jakubowski, M., König, R., Laqua, H.P., Lazerson, S., McNeely, P., Naujoks, D., Neuner, U., Otte, M., Pasch, E., Sunn Pedersen, T., Perseo, V., Puig Sitjes, A., Rahbarnia, K., Rust, N., Schmitz, O., Spring, A., Stange, T., von Stechow, A., Turkin, Y., Wang, E., and Wolf, R.C.

Published
2021
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5. Realization of a gas puff imaging system on the Wendelstein 7-X stellarator.

Author

Terry, J. L., von Stechow, A., Baek, S. G., Ballinger, S. B., Grulke, O., von Sehren, C., Laube, R., Killer, C., Scharmer, F., Brunner, K. J., Knauer, J., and Bois, S.

Subjects
PLASMA boundary layers, HEATING load, PLASMA dynamics, PLASMA gases, IMAGING systems
Abstract

A system for studying the spatiotemporal dynamics of fluctuations in the boundary of the W7-X plasma using the "Gas-Puff Imaging" (GPI) technique has been designed, constructed, installed, and operated. This GPI system addresses a number of challenges specific to long-pulse superconducting devices, such as W7-X, including the long distance between the plasma and the vacuum vessel wall, the long distance between the plasma and diagnostic ports, the range of last closed flux surface (LCFS) locations for different magnetic configurations in W7-X, and management of heat loads on the system's plasma-facing components. The system features a pair of "converging–diverging" nozzles for partially collimating the gas puffed locally ≈135 mm radially outboard of the plasma boundary, a pop-up turning mirror for viewing the gas puff emission from the side (which also acts as a shutter for the re-entrant vacuum window), and a high-throughput optical system that collects visible emission resulting from the interaction between the puffed gas and the plasma and directs it along a water-cooled re-entrant tube directly onto the 8 × 16 pixel detector array of the fast camera. The DEGAS 2 neutral code was used to simulate the Hα (656 nm) and HeI (587 nm) line emission expected from well-characterized gas-puffs of H2 and He and excited within typical edge plasma profiles in W7-X, thereby predicting line brightnesses used to reduce the risks associated with system sensitivity and placement of the field of view. Operation of GPI on W7-X shows excellent signal-to-noise ratios (> 100 at 2 Mframes/s) over the field of view for minimally perturbing gas puffs. The GPI system provides detailed measurements of the two-dimensional (radial and poloidal) dynamics of plasma fluctuations in the W7-X edge and scrape-off layer and in and around the magnetic islands outside the LCFS that make up the island divertor configuration employed on W7-X. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Heavy ion beam probe for Wendelstein 7-X measurement capabilities as projected through its design.

Author

Demers, D. R., Crowley, T. P., Fimognari, P. J., Mora, H. Trimino, Grulke, O., and Laube, R.

Subjects
PLASMA equilibrium, PLASMA turbulence, PLASMA density, PLASMA potentials, ELECTRON plasma
Abstract

A heavy ion beam probe (HIBP) diagnostic is being developed for studies of plasma equilibrium and turbulence in the optimized Wendelstein 7-X (W7-X) stellarator. Operation of W7-X has experimentally demonstrated that its optimized magnetic field results in improved neoclassical particle confinement and, as a result, turbulence is the predominant cause of energy transport. The HIBP will have the unique ability to provide experimental data needed to complement models of both neoclassical and turbulent transport. It will acquire direct measurements in the W7-X plasma interior of the electric potential (needed for understanding ambipolar particle flux) and fluctuations of electron density and potential (needed for understanding turbulence). The HIBP for W7-X will inject singly charged ion beams with energies of up to 2 MeV and is designed to access the upper cross section of the W7-X plasma. We use trajectory simulations to illustrate the plasma coverage that the diagnostic can achieve in the reference magnetic configurations of W7-X. We calculate beam signal levels, discuss anticipated measurement sensitivity of broadband fluctuations of electron density and plasma potential, and show how they depend on plasma density. We also discuss the diagnostic sensitivity to equilibrium plasma potential. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Proton-driven plasma wakefield acceleration in AWAKE

Author

The AWAKE Collaboration, Gschwendtner, E., Turner, M., Adli, E., Ahuja, A., Apsimon, O., Apsimon, R., Bachmann, A.-M., Batsch, F., Bracco, C., Braunmüller, F., Burger, S., Burt, G., Buttenschön, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D., Damerau, H., Deubner, L. H., Dexter, A., Doebert, S., Farmer, J., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Grulke, O., Hartin, A., Helm, A., Henderson, J. R., Hüther, M., Ibison, M., Jolly, S., Keeble, F., Kelisani, M. D., Kim, S.-Y., Kraus, F., Krupa, M., Lefevre, T., Li, Y., Liu, S., Lopes, N., Lotov, K. V., Martyanov, M., Mazzoni, S., Minakov, V.A., Molendijk, J. C., Moody, J. T., Moreira, M., Muggli, P., Panuganti, H., Pardons, A., Asmus, F. Peña, Perera, A., Petrenko, A., Pukhov, A., Rey, S., Sherwood, P., Silva, L. O., Sosedkin, A. P., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Wendt, M., Williamson, B., Wing, M., Woolley, B., and Xia, G.

Published
2019

11. Edge plasma measurements on the OP 1.2a divertor plasmas at W7-X using the combined probe

Author

Drews, P., Killer, C., Cosfeld, J., Knieps, A., Brezinsek, S., Jakubowski, M., Brandt, C., Bozhenkov, S., Dinklage, A., Cai, J., Endler, M., Hammond, K., Henkel, M., Gao, Y., Geiger, J., Grulke, O., Höschen, D., König, R., Krämer-Flecken, A., Liang, Y., Li, Y., Liu, S., Niemann, H., Nicolai, D., Neubauer, O., Neuner, U., Rack, M., Rahbarnia, K., Rudischhauser, L., Sandri, N., Satheeswaran, G., Schilling, S., Thomsen, H., Windisch, T., and Sereda, S.

Published
2019
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12. Localized phase contrast imaging at the Wendelstein 7-X stellarator.

Author

Hansen, S. K., Porkolab, M., Bähner, J.-P., Stechow, A. von, Grulke, O., and Edlund, E. M.

Subjects
PLASMA confinement, ELECTRON density, PLASMA waves, FOCAL planes, PLASMA density
Abstract

In its basic form, phase contrast imaging (PCI) provides line-integrated measurements of electron density fluctuations in plasmas. As turbulent fluctuations in magnetically confined plasmas have wave vectors almost perpendicular to the background magnetic field, the signals scattered by fluctuations from different parts of the PCI line-of-sight (LoS) are spatially separated in focal planes of the plasma. This allows localized PCI measurements by placing a mask in such a plane, to only permit signals from specific parts of the LoS to reach the PCI detectors. The present paper describes modeling and design of localization masks for the PCI system at the Wendelstein 7-X (W7-X) stellarator as well as the first results obtained using the masks in the recent long-pulse W7-X experimental campaign. During this project, we have extended the theory describing the mask response within the Fraunhofer diffraction model. As a novel development, we show from first principles that the mask response is determined by the fraction of power of the scattered beam spots that passes the mask. These insights have been used to select the W7-X mask design, consisting of a circular cutout, allowing the unscattered beam spot to pass the mask, with wedges covering a fixed angular range outside the central cutout. In the recent W7-X experimental campaign, the masks have verified the location of the main turbulence features observed by the PCI system and provided new information about the location of short-wavelength magnetohydrodynamic modes. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Acceleration of electrons in the plasma wakefield of a proton bunch

Author

Adli, E., Ahuja, A., Apsimon, O., Apsimon, R., Bachmann, A.-M., Barrientos, D., Batsch, F., Bauche, J., Berglyd Olsen, V. K., Bernardini, M., Bohl, T., Bracco, C., Braunmüller, F., Burt, G., Buttenschön, B., Caldwell, A., Cascella, M., Chappell, J., Chevallay, E., Chung, M., Cooke, D., Damerau, H., Deacon, L., Deubner, L. H., Dexter, A., Doebert, S., Farmer, J., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Garolfi, L., Gessner, S., Gorgisyan, I., Gorn, A. A., Granados, E., Grulke, O., Gschwendtner, E., Hansen, J., Helm, A., Henderson, J. R., Hüther, M., Ibison, M., Jensen, L., Jolly, S., Keeble, F., Kim, S.-Y., Kraus, F., Li, Y., Liu, S., Lopes, N., Lotov, K. V., Maricalva Brun, L., Martyanov, M., Mazzoni, S., Medina Godoy, D., Minakov, V. A., Mitchell, J., Molendijk, J. C., Moody, J. T., Moreira, M., Muggli, P., Öz, E., Pasquino, C., Pardons, A., Peña Asmus, F., Pepitone, K., Perera, A., Petrenko, A., Pitman, S., Pukhov, A., Rey, S., Rieger, K., Ruhl, H., Schmidt, J. S., Shalimova, I. A., Sherwood, P., Silva, L. O., Soby, L., Sosedkin, A. P., Speroni, R., Spitsyn, R. I., Tuev, P. V., Turner, M., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Williamson, B., Wing, M., Woolley, B., and Xia, G.

Published
2018
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17. AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

Author

Gschwendtner, E., Adli, E., Amorim, L., Apsimon, R., Assmann, R., Bachmann, A.-M., Batsch, F., Bauche, J., Berglyd Olsen, V.K., Bernardini, M., Bingham, R., Biskup, B., Bohl, T., Bracco, C., Burrows, P.N., Burt, G., Buttenschön, B., Butterworth, A., Caldwell, A., Cascella, M., Chevallay, E., Cipiccia, S., Damerau, H., Deacon, L., Dirksen, P., Doebert, S., Dorda, U., Farmer, J., Fedosseev, V., Feldbaumer, E., Fiorito, R., Fonseca, R., Friebel, F., Gorn, A.A., Grulke, O., Hansen, J., Hessler, C., Hofle, W., Holloway, J., Hüther, M., Jaroszynski, D., Jensen, L., Jolly, S., Joulaei, A., Kasim, M., Keeble, F., Li, Y., Liu, S., Lopes, N., Lotov, K.V., Mandry, S., Martorelli, R., Martyanov, M., Mazzoni, S., Mete, O., Minakov, V.A., Mitchell, J., Moody, J., Muggli, P., Najmudin, Z., Norreys, P., Öz, E., Pardons, A., Pepitone, K., Petrenko, A., Plyushchev, G., Pukhov, A., Rieger, K., Ruhl, H., Salveter, F., Savard, N., Schmidt, J., Seryi, A., Shaposhnikova, E., Sheng, Z.M., Sherwood, P., Silva, L., Soby, L., Sosedkin, A.P., Spitsyn, R.I., Trines, R., Tuev, P.V., Turner, M., Verzilov, V., Vieira, J., Vincke, H., Wei, Y., Welsch, C.P., Wing, M., Xia, G., and Zhang, H.

Published
2016
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18. Path to AWAKE: Evolution of the concept

Author

Caldwell, A., Adli, E., Amorim, L., Apsimon, R., Argyropoulos, T., Assmann, R., Bachmann, A.-M., Batsch, F., Bauche, J., Berglyd Olsen, V.K., Bernardini, M., Bingham, R., Biskup, B., Bohl, T., Bracco, C., Burrows, P.N., Burt, G., Buttenschön, B., Butterworth, A., Cascella, M., Chattopadhyay, S., Chevallay, E., Cipiccia, S., Damerau, H., Deacon, L., Dirksen, P., Doebert, S., Dorda, U., Elsen, E., Farmer, J., Fartoukh, S., Fedosseev, V., Feldbaumer, E., Fiorito, R., Fonseca, R., Friebel, F., Geschonke, G., Goddard, B., Gorn, A.A., Grulke, O., Gschwendtner, E., Hansen, J., Hessler, C., Hillenbrand, S., Hofle, W., Holloway, J., Huang, C., Hüther, M., Jaroszynski, D., Jensen, L., Jolly, S., Joulaei, A., Kasim, M., Keeble, F., Kersevan, R., Kumar, N., Li, Y., Liu, S., Lopes, N., Lotov, K.V., Lu, W., Machacek, J., Mandry, S., Martin, I., Martorelli, R., Martyanov, M., Mazzoni, S., Meddahi, M., Merminga, L., Mete, O., Minakov, V.A., Mitchell, J., Moody, J., Müller, A.-S., Najmudin, Z., Noakes, T.C.Q., Norreys, P., Osterhoff, J., Öz, E., Pardons, A., Pepitone, K., Petrenko, A., Plyushchev, G., Pozimski, J., Pukhov, A., Reimann, O., Rieger, K., Roesler, S., Ruhl, H., Rusnak, T., Salveter, F., Savard, N., Schmidt, J., von der Schmitt, H., Seryi, A., Shaposhnikova, E., Sheng, Z.M., Sherwood, P., Silva, L., Simon, F., Soby, L., Sosedkin, A.P., Spitsyn, R.I., Tajima, T., Tarkeshian, R., Timko, H., Trines, R., Tückmantel, T., Tuev, P.V., Turner, M., Velotti, F., Verzilov, V., Vieira, J., Vincke, H., Wei, Y., Welsch, C.P., Wing, M., Xia, G., Yakimenko, V., Zhang, H., and Zimmermann, F.

Published
2016
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19. AWAKE: A Proton-Driven Plasma Wakefield Acceleration Experiment at CERN

Author

Bracco, C., Amorim, L.D., Assmann, R., Batsch, F., Bingham, R., Burt, G., Buttenschön, B., Butterworth, A., Caldwell, A., Chattopadhyay, S., Cipiccia, S., Deacon, L.C., Doebert, S., Dorda, U., Feldbaumer, E., Fonseca, R.A., Fedossev, V., Goddard, B., Grebenyuk, J., Grulke, O., Gschwendtner, E., Hansen, J., Hessler, C., Hofle, W., Holloway, J., Jaroszynski, D., Jenkins, M., Jensen, L., Jolly, S., Jones, R., Kasim, M.F., Lopes, N., Lotov, K., Mandry, S.R., Martyanov, M., Meddahi, M., Mete, O., Minakov, V., Moody, J., Muggli, P., Najmudin, Z., Norreys, P.A., Öz, E., Pardons, A., Petrenko, A., Pukhov, A., Rieger, K., Reimann, O., Seryi, A.A., Shaposhnikova, E., Sherwood, P., Silva, L.O., Sosedkin, A., Tarkeshian, R., Trines, R.M.G.M., Velotti, F.M., Vieira, J., Vincke, H., Welsch, C., Wing, M., and Xia, G.

Published
2016
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20. Engineering design for the magnetic diagnostics of Wendelstein 7-X

Author

Endler, M., Brucker, B., Bykov, V., Cardella, A., Carls, A., Dobmeier, F., Dudek, A., Fellinger, J., Geiger, J., Grosser, K., Grulke, O., Hartmann, D., Hathiramani, D., Höchel, K., Köppen, M., Laube, R., Neuner, U., Peng, X., Rahbarnia, K., Rummel, K., Sieber, T., Thiel, S., Vorköper, A., Werner, A., Windisch, T., and Ye, M.Y.

Published
2015
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21. Preparing the operation of Wendelstein 7-X in the steady-state regime

Author

W7-X Team, Bosch, H.-S., Eeten, P. van, Grulke, O., Bräuer, T., Degenkolbe, S., Nagel, M., Rummel, T., Schacht, J., Spring, A., and Winter, A.

Subjects
Technology, ddc:600
Abstract

The Wendelstein 7-X stellarator (W7-X) started operation in December 2015 and has performed three experimental campaigns up to November 2018. Since then the device has been completed to the planned configuration (most importantly with predominantly actively cooled first wall, including the High Heat Flux divertor and a divertor cryo pump) to be able to perform stationary plasma programs. After this completion pFhase, at the end of 2021, the commissioning has been performed and scientific operation has started in the fall of 2022.

Published
2023

22. Controlled growth of the self-modulation of a relativistic proton bunch in plasma

Author

Verra, L., Zevi Della Porta, G., Pucek, J., Nechaeva, T., Wyler, S., Bergamaschi, M., Senes, E., Guran, E., Moody, J.T., Kedves, M.Á., Gschwendtner, E., Muggli, P., Agnello, R., Ahdida, C.C., Goncalves, M.C.A., Andrebe, Y., Apsimon, O., Apsimon, R., Arnesano, J.M., Bachmann, A.-M., Barrientos, D., Batsch, F., Bencini, V., Blanchard, P., Burrows, P.N., Buttenschön, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D.A., Davut, C., Demeter, G., Dexter, A.C., Doebert, S., Elverson, F.A., Farmer, J., Fasoli, A., Fedosseev, V., Fonseca, R., Furno, I., Gorn, A., Granados, E., Granetzny, M., Graubner, T., Grulke, O., Hafych, V., Henderson, J., Hüther, M., Khudiakov, V., Kim, S.-Y., Kraus, F., Krupa, M., Lefevre, T., Liang, L., Liu, S., Lopes, N., Lotov, K., Martinez Calderon, M., Mazzoni, S., Medina Godoy, D., Moon, K., Morales Guzmán, P.I., Moreira, M., Nowak, E., Pakuza, C., Panuganti, H., Pardons, A., Pepitone, K., Perera, A., Pukhov, A., Ramjiawan, R.L., Rey, S., Schmitz, O., Silva, F., Silva, L., Stollberg, C., Sublet, A., Swain, C., Topaloudis, A., Torrado, N., Tuev, P., Velotti, F., Verzilov, V., Vieira, J., Weidl, M., Welsch, C., Wendt, M., Wing, M., Wolfenden, J., Woolley, B., Xia, G., Yarygova, V., Zepp, M., and AWAKE Collaboration

Subjects
Accelerator Physics (physics.acc-ph), Other Fields of Physics, General Physics and Astronomy, FOS: Physical sciences, Acceleratorfysik och instrumentering, Accelerator Physics and Instrumentation, Accelerators and Storage Rings, Ciências Naturais::Ciências Físicas [Domínio/Área Científica], Fusion, Plasma and Space Physics, Physics - Plasma Physics, Plasma Physics (physics.plasm-ph), Fusion, plasma och rymdfysik, physics.plasm-ph, Physics::Accelerator Physics, Physics - Accelerator Physics, physics.acc-ph
Abstract

A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case. A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case.

Published
2022
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24. Confinement in electron heated plasmas in Wendelstein 7-X and ASDEX Upgrade; the necessity to control turbulent transport

Author

Beurskens, M.N.A., Angioni, C., Bozhenkov, S. A., Ford, O., Kiefer, C., Xanthopoulos, P., Turkin, Y., Alcus��n, J.A., Baehner, J.P., Beidler, C., Birkenmeier, G., Fable, E., Fuchert, G., Geiger, B., Grulke, O., Hirsch, M., Jakubowski, M., Laqua, H.P., Langenberg, A., Lazerson, S., Pablant, N., Reisner, M., Schneider, P., Scott, E.R., Stange, T., Von Stechow, A., Stober, J., Stroth, U., Wegner, Th., Weir, G., Zhang, D., Zocco, A., Wolf, R.C., Zohm, H., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfu��, Daniel, Thumm, Manfred, Wadle, Simone, and Weggen, J��rg

Published
2022
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25. Letter

Author

Li, Y., Xu, G., Dudson, B., Liu, X., Huang, Z., Killer, C., Feng, Y., Liu, S., Yan, N., Morales, J., Tsitrone, E., Brezinsek, S., Liang, Y., Eldon, D., Xiao, C., Geiger, J., Grulke, O., Otte, M., the WEST Team, the W7-X Team, Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, WEST Team, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Nuclear and High Energy Physics, Technology, ddc:620, Condensed Matter Physics, ddc:600
Abstract

A universal energy partition mechanism between ions and electrons has been confirmed to exist in the scrape-off layer of both the WEST tokamak and the W7-X stellarator. A peaked plasma density structure induced by an infinite magnetic connection length structure is observed to destroy this dependence and enhance the local ion and electron temperature ratio in the stellarator. A theoretical analysis reveals that the ratio of ion and electron parallel heat conduction is predominant in determining this universality, while electrons would further be cooled in the density-peaked region.

Published
2022
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26. Magnetic configuration scans during divertor operation of Wendelstein 7-X

Author

Team, The W7-X, Andreeva, T., Geiger, J., Dinklage, A., Wurden, G., Thomsen, H., Rahbarnia, K., Schmitt, J. C., Hirsch, M., Fuchert, G., Nührenberg, C., Alonso, A., Beidler, C. D., Beurskens, M. N. A., Bozhenkov, S., Brakel, R., Brandt, C., Bykov, V., Grahl, M., Grulke, O., Killer, C., Kocsis, G., Klinger, T., Krämer-Flecken, A., Lazerson, S., Otte, M., Pablant, N., Schilling, J., Windisch, T., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Subjects
Technology, ddc:600
Published
2022

27. Confinement in electron heated plasmas in Wendelstein 7-X and ASDEX Upgrade; the necessity to control turbulent transport

Author

W7-X Team, Beurskens, M. N. A., Angioni, C., Bozhenkov, S. A., Ford, O., Kiefer, C., Xanthopoulos, P., Turkin, Y., Alcusón, J. A., Baehner, J. P., Beidler, C., Birkenmeier, G., Fable, E., Fuchert, G., Geiger, B., Grulke, O., Hirsch, M., Jakubowski, M., Laqua, H. P., Langenberg, A., Lazerson, S., Pablant, N., Reisner, M., Schneider, P., Scott, E. R., Stange, T., Stechow, A. von, Stober, J., Stroth, U., Wegner, Th., Weir, G., Zhang, D., Zocco, A., Wolf, R. C., Zohm, H., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, and EUROfusion MST1 Team

Subjects
Technology, Nuclear and High Energy Physics, Turbulent transport, Materials science, Turbulence, Ion temperature clamping, Plasma, Electron, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Nuclear physics, Electron heating, ASDEX Upgrade, Physics::Plasma Physics, 0103 physical sciences, Stellarator transport, Wendelstein 7-X, ddc:620, 010306 general physics, ddc:600
Abstract

In electron (cyclotron) heated plasmas, in both ASDEX Upgrade (L-mode) and Wendelstein 7-X, clamping of the ion temperature occurs at T i ∼ 1.5 keV independent of magnetic configuration. The ions in such plasmas are heated through the energy exchange power as n e 2 ( T e − T i ) / T e 3 / 2 , which offers a broad ion heating profile, similar to that offered by alpha heating in future thermonuclear fusion reactors. However, the predominant electron heating may put an additional constraint on the ion heat transport, as the ratio T e/T i > 1 can exacerbates ITG/TEM core turbulence. Therefore, in practical terms the strongly ‘stiff’ core transport translates into T i-clamping in electron heated plasmas. Due to this clamping, electron heated L-mode scenarios, with standard gas fueling, in either tokamaks or stellarators may struggle to reach high normalized ion temperature gradients required in a compact fusion reactor. The comparison shows that core heat transport in neoclassically optimized stellarators is driven by the same mechanisms as in tokamaks. The absence of a strong H-mode temperature edge pedestal in stellarators, sofar (which, like in tokamaks, could lift the clamped temperature-gradients in the core), puts a strong requirement on reliable and sustainable core turbulence suppression techniques in stellarators.

Published
2021
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31. Conceptual design of a heavy ion beam probe diagnostic for the Wendelstein 7-X Stellarator.

Author

Trimino Mora, H., Crowley, T. P., Demers, D. R., Fimognari, P. J., Grulke, O., and Laube, R.

Subjects
ION beams, HEAVY ions, CONCEPTUAL design, CONFIGURATION space, PLASMA density, SPACE trajectories
Abstract

This article describes the current state of the design of the heavy ion beam probe (HIBP) for Wendelstein 7-X (W7-X). It will be the first HIBP diagnostic on an optimized stellarator and is designed to study electric fields and ion scale turbulence in all W7-X reference magnetic configurations. The use of an existing 2 MV accelerator, located outside of the torus hall, results in the need for a circuitous primary beamline. This increases the complexity of the ion optics design to deliver a focused beam to the plasma. To access most of the magnetic configuration space of W7-X, the secondary beamline and an energy analyzer are designed to pivot, thereby redirecting a wider range of secondary beam trajectories. Signal level estimates indicate that the equilibrium potential can be measured at all radii and that the radial coverage for potential and density fluctuations measurements depends on the plasma density. [ABSTRACT FROM AUTHOR]

Published
2022
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32. Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma

Author

Batsch, F, Muggli, P, Agnello, R, Ahdida, CC, Amoedo Goncalves, MC, Andrebe, Y, Apsimon, O, Apsimon, R, Bachmann, A-M, Baistrukov, MA, Blanchard, P, Braunmüller, F, Burrows, PN, Buttenschön, B, Caldwell, A, Chappell, J, Chevallay, E, Chung, M, Cooke, DA, Damerau, H, Davut, C, Demeter, G, Deubner, HL, Doebert, S, Farmer, J, Fasoli, A, Fedosseev, VN, Fiorito, R, Fonseca, RA, Friebel, F, Furno, I, Garolfi, L, Gessner, S, Gorgisyan, I, Gorn, AA, Granados, E, Granetzny, M, Graubner, T, Grulke, O, Gschwendtner, E, Hafych, V, Helm, A, Henderson, JR, Hüther, M, Kargapolov, I Yu, Kim, S-Y, Kraus, F, Krupa, M, Lefevre, T, Liang, L, Liu, S, Lopes, N, Lotov, KV, Martyanov, M, Mazzoni, S, Medina Godoy, D, Minakov, VA, Moody, JT, Moon, K, Morales Guzmán, PI, Moreira, M, Nechaeva, T, Nowak, E, Pakuza, C, Panuganti, H, Pardons, A, Perera, A, Pucek, J, Pukhov, A, Ramjiawan, RL, Rey, S, Rieger, K, Schmitz, O, Senes, E, Silva, LO, Speroni, R, Spitsyn, RI, Stollberg, C, Sublet, A, Topaloudis, A, Torrado, N, Tuev, PV, Turner, M, Velotti, F, Verra, L, Verzilov, VA, Vieira, J, Vincke, H, Welsch, CP, Wendt, M, Wing, M, Wiwattananon, P, Wolfenden, J, Woolley, B, Xia, G, Zepp, M, Zevi Della Porta, G, AWAKE Collaboration, and Collaboration, AWAKE

Subjects
Accelerator Physics (physics.acc-ph), Proton, Other Fields of Physics, Phase (waves), FOS: Physical sciences, General Physics and Astronomy, Ciências Naturais::Ciências Físicas [Domínio/Área Científica], 01 natural sciences, Instability, Relativistic particle, physics.plasm-ph, 0103 physical sciences, 010306 general physics, physics.acc-ph, Physics, acceleration, Plasma, electron-beam, Accelerators and Storage Rings, Physics - Plasma Physics, ddc, Plasma Physics (physics.plasm-ph), Transverse plane, Amplitude, Physics::Accelerator Physics, Physics - Accelerator Physics, Atomic physics, Event (particle physics)
Abstract

We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude ($\ge(4.1\pm0.4)$ MV/m), the phase of the modulation along the bunch is reproducible from event to event, with 3 to 7% (of 2$\pi$) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated., Comment: Letter and Supplemental Material, 6 figures, 8 pages

Published
2021
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34. Ion temperature clamping in Wendelstein 7-X electron cyclotron heated plasmas

Author

W7-X Team, Beurskens, M. N. A., Bozhenkov, S. A., Ford, O., Xanthopoulos, P., Zocco, A., Turkin, Y., Alonso, A., Beidler, C., Calvo, I., Carralero, D., Estrada, T., Fuchert, G., Grulke, O., Hirsch, M., Ida, K., Jakubowski, M., Killer, C., Krychowiak, M., Kwak, S., Lazerson, S., Langenberg, A., Lunsford, R., Pablant, N., Pasch, E., Pavone, A., Reimold, F., Romba, Th., Stechow, A. von, Smith, H. M., Windisch, T., Yoshinuma, M., Zhang, D., Wolf, R. C., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Subjects
Technology, ddc:600
Published
2021

36. Current effect on the edge profiles in the island at W7-X

Author

Drews, P., Killer, C., Knieps, A., Reimold, F., Zhang, D., Brezinsek, S., Jakubowski, M., Cosfeld, J., Endler, M., Hammond, K., Henkel, M., Geiger, J., Grulke, O., König, R., Krämer-Flecken, A., Liang, Y., Liu, S., Nicolai, D., Satheeswaran, G., Neubauer, O., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2021

37. Magnetic and Electrostatic Turbulence Island Modulation in the W7-X Boundary

Author

Spolaore M., Killer C., Agostinetti P., Cavazzana R., Ghiraldelli R., Grenfell G., Grulke O., Knieps A., Lazerson S.A., Moresco M., Martines E., Neubauer O., Nocolai D., Satheeswaran G., Schweer B., Vianello N., and W7-X Team

Subjects
magnetic and electrostatic turbulence island modulation, magnetic island in the boundary of nuclear fusion, stellarator experiment W7-X
Abstract

The presence of magnetic island in the boundary of fusion devices is expected to strongly affect the local plasma properties, inducing local flow velocity patterns and perturbing the edge profiles as well as the transport properties. In particular the proximity to the island Xpoint or O-point is found to induce both electrostatic and magnetic turbulence modulation, with experimental evidences in different magnetic configurations. The boundary of the W7-X stellarator experiment is characterized by the presence of a poloidal chain of magnetic islands, whose features depend on the magnetic configuration as defined by the rotational transform, ?/2?. These islands intercept the divertor plates and provide a poloidal series of X-points constituting the island divertor, the concept exploited in the W7-X for the particle and energy exhaust. In this contribution the presence and features of turbulent fluctuations in both electrostatic and magnetic quantities, including the parallel current density fluctuations will be investigated in the Scrape-Off-Layer region of W7-X experiment. To this end a specifically designed insertable probe head was constructed within the framework of EUROfusion WP.S1 work package in collaboration between Consorzio RFX, IPP Greifswald and Forschungszentrum Jülich. The probe head, named High Resolution Probe (HRP) [1,2], was conceived to be installed on the mid-plane multi-purpose fast reciprocating manipulator on W7-X and is suitable for the study of electrostatic and magnetic properties of filaments emerging from turbulence background and characterizing the edge region. In particular the magnetic island related turbulence modulation and the filamentary structure population distribution will be analysed by applying advanced statistical tools First measurements were performed during the W7-X experimental campaign OP1.2b, where in particular the probe was exploring different magnetic configurations. The respective features of the electromagnetic turbulence will be compared.

Published
2021

38. Core plasma density fluctuations in Wendelstein 7-X ECRH plasmas

Author

Bähner, J., Alcuson, J., Hansen, S., Stechow, A., Grulke, O., Windisch, T., Smith, H., Huang, Z., Edlund, E., Porkolab, M., Beurskens, M., Bozhenkov, S., Ford, O., Vano, L., Langenberg, A., Pablant, N., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2021

39. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author

W7-X Team, Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S. A., Brunner, K. J., Damm, H., Drevlak, M., Ford, O. P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., Hirsch, M., Höfel, U., Kazakov, Ye. O., Kleiber, R., Krychowiak, M., Kwak, S., Langenberg, A., Laqua, H. P., Neuner, U., Pablant, N. A., Pasch, E., Pavone, A., Pedersen, T. S., Rahbarnia, K., Schilling, J., Scott, E. R., Stange, T., Svensson, J., Thomsen, H., Turkin, Y., Warmer, F., Wolf, R. C., Zhang, D., Abramovic, I., Äkäslompolo, S., Alcusón, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., Bähner, J. P., Baek, S. G., Balden, M., Banduch, M., Barbui, T., Behr, W., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., Böckenhoff, D., Böswirth, B., Böttger, L.-G., Borsuk, V., Boscary, J., Bosch, H.-S., Brakel, R., Brand, H., Brandt, C., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Burhenn, R., Bussiahn, R., Buttenschön, B., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M., Cole, M. J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., Molin, A. da, Silva, A. da, Pena, A. de la, Degenkolbe, S., Dhard, C. P., Dibon, M., Dinklage, A., Dittmar, T., Drewelow, P., Drews, P., Durodie, F., Edlund, E., Effenberg, F., Ehrke, G., Elgeti, S., Endler, M., Ennis, D., Esteban, H., Estrada, T., Fellinger, J., Feng, Y., Flom, E., Fernandes, H., Fietz, W. H., Figacz, W., Fontdecaba, J., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., García Regaña, J., Gates, D., Geiger, B., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Grulke, O., Guerard, C., Hacker, P., Han, X., Harris, J. H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hollfeld, K. P., Hölting, A., Höschen, D., Houry, M., Howard, J., Huang, X., Huang, Z., Hubeny, M., Huber, M., Hunger, H., Ida, K., Ilkei, T., Illy, S., Israeli, B., Jablonski, S., Jakubowski, M., Jelonnek, J., Jenzsch, H., Jesche, T., Jia, M., Junghanns, P., Kacmarczyk, J., Kallmeyer, J.-P., Kamionka, U., Kasahara, H., Kasparek, W., Kenmochi, N., Killer, C., Kirschner, A., Klinger, T., Knauer, J., Knaup, M., Knieps, A., Kobarg, T., Kocsis, G., Köchl, F., Kolesnichenko, Y., Könies, A., König, R., Kornejew, P., Koschinsky, J.-P., Köster, F., Krämer, M., Krampitz, R., Krämer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., Kühner, G., Kurki-Suonio, T., Kurz, P. A., Landreman, M., Lang, P., Lang, R., Langish, S., Laqua, H., Laube, R., Lazerson, S., Lechte, C., Lennartz, M., Leonhardt, W., Li, C., Li, Y., Liang, Y., Linsmeier, C., Liu, S., Lobsien, J.-F., Loesser, D., Loizu Cisquella, J., Lore, J., Lorenz, A., Losert, M., Lücke, A., Lumsdaine, A., Lutsenko, V., Maaßberg, H., Marchuk, O., Matthew, J. H., Marsen, S., Marushchenko, M., Masuzaki, S., Maurer, D., Mayer, M., McCarthy, K., McNeely, P., Meier, A., Mellein, D., Mendelevitch, B., Mertens, P., Mikkelsen, D., Mishchenko, A., Missal, B., Mittelstaedt, J., Mizuuchi, T., Mollen, A., Moncada, V., Mönnich, T., Morisaki, T., Moseev, D., Murakami, S., Náfrádi, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nocentini, R., Nührenberg, C., Nührenberg, J., Obermayer, S., Offermanns, G., Ogawa, K., Ölmanns, J., Ongena, J., Oosterbeek, J. W., Orozco, G., Otte, M., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfuß, D., Paqay, S., Pawelec, E., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., Pölöskei, P., Porkolab, M., Proll, J., Puiatti, M.-E., Puig Sitjes, A., Purps, F., Rack, M., Récsei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riedl, R., Riemann, J., Risse, K., Rohde, V., Röhlinger, H., Romé, M., Rondeshagen, D., Rong, P., Roth, B., Rudischhauser, L., Rummel, K., Rummel, T., Runov, A., Rust, N., Ryc, L., Ryosuke, S., Sakamoto, R., Salewski, M., Samartsev, A., Sanchez, M., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schlüter, K.-H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schröder, M., Schröder, T., Schroeder, R., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szabó, V., Szabolics, T., Szepesi, T., Szökefalvi-Nagy, Z., Tamura, N., Tancetti, A., Terry, J., Thomas, J., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trimino Mora, H., Tsuchiya, H., Tsujimura, T., Tulipán, S., Unterberg, B., Vakulchyk, I., Valet, S., Vanó, L., Eeten, P. van, Milligen, B. van, Vuuren, A. J. van, Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Stechow, A. von, Vorköper, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Wauters, T., Wegener, L., Weggen, J., Wegner, T., Wei, Y., Weir, G., Wendorf, J., Wenzel, U., Werner, A., White, A., Wiegel, B., Wilde, F., Windisch, T., Winkler, M., Winter, A., Winters, V., Wolf, S., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., Zuin, M., W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, Applied Physics and Science Education, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, and European Commission

Subjects
Magnetically Confined Plasmas, Tokamak, Design, Helias, Nuclear engineering, Magnetically confined plasmas, 01 natural sciences, 7. Clean energy, Article, Plasma physics, 010305 fluids & plasmas, law.invention, law, Physics::Plasma Physics, 0103 physical sciences, Nuclear fusion, 010306 general physics, Engineering & allied operations, Stellarator, Physics, Plasma fusion, Multidisciplinary, Toroid, biology, Plasma Physics, Física, Magnetic confinement fusion, Plasma, biology.organism_classification, Energía Nuclear, ddc:620, Wendelstein 7-X
Abstract

Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak1 is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)2, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator’s non-turbulent ‘neoclassical’ energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas3,4. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible1,5. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization., Previously documented record values of the fusion triple product in the stellarator Wendelstein 7-X are shown to be evidence for reduced neoclassical energy transport in this optimized device.

Published
2021
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40. Heat pulse propagation and anomalous electron heat transport measurements on the optimized stellarator W7-X

Author

Weir, G.M., Xanthopoulos, P., Hirsch, M., Höfel, U., Stange, T., Pablant, N., Grulke, O., Äkäslompolo, S., Alcusón, J., Bozhenkov, S., Beurskens, M., Dinklage, A., Fuchert, G., Geiger, J., Landreman, M., Langenberg, A., Lazerson, S., Marushchenko, N., Pasch, E., Schilling, J., Scott, E.R., Turkin, Y., Klinger, T., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Published
2021
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41. Publisher Correction: Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author

Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S. A., Brunner, K. J., Damm, H., Drevlak, M., Ford, O. P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., Hirsch, M., H��fel, U., Kazakov, Ye. O., Kleiber, R., Krychowiak, M., Kwak, S., Langenberg, A., Laqua, H. P., Neuner, U., Pablant, N. A., Pasch, E., Pavone, A., Pedersen, T. S., Rahbarnia, K., Schilling, J., Scott, E. R., Stange, T., Svensson, J., Thomsen, H., Turkin, Y., Warmer, F., Wolf, R. C., Zhang, D., Abramovic, I., ��k��slompolo, S., Alcus��n, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., B��hner, J. P., Baek, S. G., Balden, M., Banduch, M., Barbui, T., Behr, W., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., B��ckenhoff, D., B��swirth, B., B��ttger, L.-G., Borsuk, V., Boscary, J., Bosch, H.-S., Brakel, R., Brand, H., Brandt, C., Br��uer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Burhenn, R., Bussiahn, R., Buttensch��n, B., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M., Cole, M. J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., Da Molin, A., Da Silva, A., De La Pena, A., Degenkolbe, S., Dhard, C. P., Dibon, M., Dinklage, A., Dittmar, T., Drewelow, P., Drews, P., Durodie, F., Edlund, E., Effenberg, F., Ehrke, G., Elgeti, S., Endler, M., Ennis, D., Esteban, H., Estrada, T., Fellinger, J., Feng, Y., Flom, E., Fernandes, H., Fietz, W. H., Figacz, W., Fontdecaba, J., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., Garc��a Rega��a, J., Gates, D., Geiger, B., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Grulke, O., Guerard, C., Hacker, P., Han, X., Harris, J. H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hollfeld, K. P., H��lting, A., H��schen, D., Houry, M., Howard, J., Huang, X., Huang, Z., Hubeny, M., Huber, M., Hunger, H., Ida, K., Ilkei, T., Illy, S., Israeli, B., Jablonski, S., Jakubowski, M., Jelonnek, J., Jenzsch, H., Jesche, T., Jia, M., Junghanns, P., Kacmarczyk, J., Kallmeyer, J.-P., Kamionka, U., Kasahara, H., Kasparek, W., Kenmochi, N., Killer, C., Kirschner, A., Klinger, T., Knauer, J., Knaup, M., Knieps, A., Kobarg, T., Kocsis, G., K��chl, F., Kolesnichenko, Y., K��nies, A., K��nig, R., Kornejew, P., Koschinsky, J.-P., K��ster, F., Kr��mer, M., Krampitz, R., Kr��mer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., K��hner, G., Kurki-Suonio, T., Kurz, P. A., Landreman, M., Lang, P., Lang, R., Langish, S., Laqua, H., Laube, R., Lazerson, S., Lechte, C., Lennartz, M., Leonhardt, W., Li, C., Li, Y., Liang, Y., Linsmeier, C., Liu, S., Lobsien, J.-F., Loesser, D., Loizu Cisquella, J., Lore, J., Lorenz, A., Losert, M., L��cke, A., Lumsdaine, A., Lutsenko, V., Maa��berg, H., Marchuk, O., Matthew, J. H., Marsen, S., Marushchenko, M., Masuzaki, S., Maurer, D., Mayer, M., McCarthy, K., McNeely, P., Meier, A., Mellein, D., Mendelevitch, B., Mertens, P., Mikkelsen, D., Mishchenko, A., Missal, B., Mittelstaedt, J., Mizuuchi, T., Mollen, A., Moncada, V., M��nnich, T., Morisaki, T., Moseev, D., Murakami, S., N��fr��di, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nocentini, R., N��hrenberg, C., N��hrenberg, J., Obermayer, S., Offermanns, G., Ogawa, K., ��lmanns, J., Ongena, J., Oosterbeek, J. W., Orozco, G., Otte, M., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfu��, D., Paqay, S., Pawelec, E., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., P��l��skei, P., Porkolab, M., Proll, J., Puiatti, M.-E., Puig Sitjes, A., Purps, F., Rack, M., R��csei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riedl, R., Riemann, J., Risse, K., Rohde, V., R��hlinger, H., Rom��, M., Rondeshagen, D., Rong, P., Roth, B., Rudischhauser, L., Rummel, K., Rummel, T., Runov, A., Rust, N., Ryc, L., Ryosuke, S., Sakamoto, R., Salewski, M., Samartsev, A., S��nchez, E., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schl��ter, K.-H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schr��der, M., Schr��der, T., Schroeder, R., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipli��, S., Slaby, C., Sleczka, M., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szab��, V., Szabolics, T., Szepesi, T., Sz��kefalvi-Nagy, Z., Tamura, N., Tancetti, A., Terry, J., Thomas, J., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trimino Mora, H., Tsuchiya, H., Tsujimura, T., Tulip��n, S., Unterberg, B., Vakulchyk, I., Valet, S., Van��, L., Van Eeten, P., Van Milligen, B., Van Vuuren, A. J., Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Von Stechow, A., Vork��per, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Wauters, T., Wegener, L., Weggen, J., Wegner, T., Wei, Y., Weir, G., Wendorf, J., Wenzel, U., Werner, A., White, A., Wiegel, B., Wilde, F., Windisch, T., Winkler, M., Winter, A., Winters, V., Wolf, S., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., and Zuin, M.

Subjects
Chemical engineering, ddc:660
Published
2021

42. Experimental study of extended timescale dynamics of a plasma wakefield driven by a self-modulated proton bunch

Author

Chappell, J., Adli, E., Agnello, R., Aladi, M., Andrebe, Y, Apsimon, O., Apsimon, R., Bachmann, A.-M., Baistrukov, M. A., Batsch, F., Bergamaschi, M., Della Porta, G. Z., Blanchard, P., Burrows, P. N., Buttenschön, B., Caldwell, A., Chevallay, E., Chung, M., Cooke, D. A., Damerau, H., Davut, C., Demeter, G., Deubner, L. H., Dexter, A., Djotyan, G. P., Doebert. S., Farmer, J., Fasoli, A., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Furno, I., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Granetzny, M., Grulke, O., Gschwendtner, E., Hafych, V., Hartin, A., Helm, A, Henderson, J. R., Howling, A., Hüther, M ., Jacquier, R., Jolly, S. W., Kargapolov, I. Y., Kedves, M. Á., Keeble, F., Kelisani, M. D., Kim, S.-Y, Krausz, F., Krupa, M., Lefevre, T ., Li, Y., Liang, L., Liu, S., Lopes, N. C., Lotov, K. V., Martyanov, M., Mazzoni, S., Medina Godoy, D., Militsyn, B. L., Minakov, V. A., Moody, J. T., Morales Guzmán, P. I., Moreira, M. T., Panuganti, H., Pardons, A., Peña Asmus, F., Perera, A., Petrenko, A., Pucek, J., Pukhov, A., Ráczkevi, B., Ramjiawan, R. L., Rey, S., Ruhl, H., Saberi, H., Schmitz, O., Senes, E., Sherwood, P., Silva, L. O., Spitsyn, R. I., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Williamson, B., Wing, M., Wolfenden, J., Woolley, B., Xia, G. X., and Zepp, M.

Subjects
Accelerator Physics (physics.acc-ph), Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), Proton, Other Fields of Physics, FOS: Physical sciences, Electron, 01 natural sciences, law.invention, law, Electron injection, Physics::Plasma Physics, physics.plasm-ph, 0103 physical sciences, 010306 general physics, physics.acc-ph, Physics, 010308 nuclear & particles physics, Dynamics (mechanics), Surfaces and Interfaces, Plasma, Laser, Accelerators and Storage Rings, Physics - Plasma Physics, ddc, Plasma Physics (physics.plasm-ph), Amplitude, Physics::Accelerator Physics, Physics - Accelerator Physics, Atomic physics, Excitation
Abstract

Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scans., 11 pages, 8 figures

Published
2021
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43. Changes in the edge magnetic field of Wendelstein 7-X in high-beta plasmas

Author

Knieps, A., Liang, Y., Suzuki, Y., Andreeva, T., Drews, P., Gao, Y., Geiger, J., Grulke, O., Hollfeld, K., Jakubowski, M., Killer, C., Neubauer, O., Nicolai, D., Neuner, U., Niemann, H., Huang, Z., Rahbarnia, K., Satheeswaran, G., Schilling, J., Thomsen, H., Zhou, S., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2021

44. High-performance ECRH at W7-X: experience and perspectives

Author

W7-X Team, Laqua, H. P., Baldzuhn, J., Braune, H., Bozhenkov, S., Brunner, K., Hirsch, M., Hoefel, U., Knauer, J., Langenberg, A., Marsen, S., Moseev, D., Pasch, E., Rahbarnia, K., Stange, T., Wolf, R. C., Pablant, N., Grulke, O., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Subjects
Technology, ddc:600
Published
2021

46. Suppression of core turbulence by profile shaping in Wendelstein 7-X

Author

Stechow, A. v., Grulke, O., Wegner, Th., Proll, J. H. E., Alcus��n, J. A., Smith, H. M., Baldzuhn, J., Beidler, C. D., Beurskens, M. N. A., Bozhenkov, S. A., Edlund, E., Geiger, B., Huang, Z., Ford, O. P., Fuchert, G., Langenberg, A., Pablant, N., Pasch, E., Porkolab, M., Rahbarnia, K., Schilling, J., Scott, E. R., Thomsen, H., Van��, L., Weir, G., and Team, The W7-X

Subjects
Plasma Physics (physics.plasm-ph), FOS: Physical sciences, Physics - Plasma Physics
Abstract

In the Wendelstein 7-X magnetic confinement experiment, a reduction of turbulent density fluctuations as well as anomalous impurity diffusion is associated with a peaking of the plasma density profile. These effects correlate with improved confinement and appear largely due to a reduction of anomalous transport as the change in neoclassical transport is small. The observed decrease of turbulent heat flux with increased density gradients is in agreement with nonlinear gyrokinetic simulations, and has been attributed to the unique geometry of W7-X that limits the severity of trapped electron modes.

Published
2020

47. Evolution of a plasma column measured through modulation of a high-energy proton beam

Author

Gessner, S., Adli, E., Apsimon, O., Apsimon, R., Bachmann, A.-M., Batsch, F., Bracco, C., Braunmuller, F., Burger, S., Burt, G., Buttenschon, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D., Damerau, H., Demeter, G., Deubner, L.H., Dexter, A., Doebert, S., Farmer, J., Fedosseev, V.N., Fiorito, R., Fonseca, R.A., Friebel, F., Garolfi, L., Goddard, B., Gorgisyan, I., Gorn, A.A., Granados, E., Grulke, O., Gschwendtner, E., Hartin, A., Helm, A., Henderson, J.R., Huther, M., Ibison, M., Jolly, S., Keeble, F., Kelisani, M.D., Khudyakov, V.K., Kim, S.-Y., Kraus, F., Krupa, M., Lefevre, T., Li, Y., Liu, S., Lopes, N., Lotov, K.V., Martyanov, M., Mazzoni, S., Minakov, V.A., Molendijk, J.C., Moody, J.T., Moreira, M., Panuganti, H., Pardons, A., Pena Asmus, F., Perera, A., Petrenko, A., Pukhov, A., Rey, S., Ruhl, H., Saberi, H., Sherwood, P., Silva, L.O., Sosedkin, A.P., Sublet, A., Tuev, P.V., Turner, M., Velotti, F., Verra, L., Verzilov, V.A., Vieira, J., Welsch, C.P., Wendt, M., Williamson, B., Wing, M., Woolley, B., Xia, G., and Zevi Della Porta, G.

Subjects
Accelerator Physics (physics.acc-ph), Plasma Physics (physics.plasm-ph), Physics::Plasma Physics, physics.plasm-ph, Other Fields of Physics, FOS: Physical sciences, Physics::Accelerator Physics, Physics - Accelerator Physics, Accelerators and Storage Rings, Physics - Plasma Physics, physics.acc-ph
Abstract

Plasma wakefield acceleration is a method for accelerating particle beams using electromagnetic fields that are orders of magnitude larger than those found in conventional radio frequency cavities. The core component of a plasma wakefield accelerator is the plasma source, which ranges from millimeter-scale gas jets used in laser-driven experiments, to the ten-meter-long rubidium cell used in the AWAKE experiment. The density of the neutral gas is a controlled input to the experiment, but the density of the plasma after ionization depends on many factors. AWAKE uses a high-energy proton beam to drive the plasma wakefield, and the wakefield acts back on the proton bunch by modulating it at the plasma frequency. We infer the plasma density by measuring the frequency of modulation of the proton bunch, and we measure the evolution of the density versus time by varying the arrival of the proton beam with respect to the ionizing laser pulse. Using this technique, we uncover a microsecond-long period of a stable plasma density followed by a rapid decay in density. The stability of the plasma after ionization has implications for the design of much longer vapor cells that could be used to accelerate particle beams to extremely high energies.

Published
2020

49. Spectra of highly ionized xenon (6–30 nm) excited in W7-AS plasmas

Author

Hacker, H.H., Burhenn, R., Kondo, K., Anton, M., Assmus, D., Baeumel, S., Beidler, C., Bindemann, T., Brakel, R., Cattanei, G., Dinklage, A., Dodhy, A., Dorst, D., Ehmler, H., Elsner, A., Endler, M., Engelhardt, K., Erckmann, V., Feng, Y., Fuchs, C., Gadelmeier, F., Geiger, J., Giannone, L., Grigull, P., Gruenwald, G., Grulke, O., Harmeyer, E., Hartfuss, H.J., Herrnegger, F., Hirsch, M., Hofner, J., Hollmann, F., Holzhauer, E., Igitkhanov, Y., Jaenicke, R., Karger, F., Kick, M., Kisslinger, J., Klose, S., Knauer, J., Kroiss, H., Kühner, G., Kus, A., Laqua, H., Liu, R., Maassberg, H., Marushchenko, N., McCormick, K., Michel, G., Noke, F., Ott, W., Otte, M., Pacco-Duechs, M.G., Penningsfeld, F.P., Polunovsky, E., Probst, F., Purps, F., Ruhs, N., Rust, N., Saffert, N.J., Salat, A., Sallander, J., Sardei, F., Schneider, F., Schubert, M., Sidorenko, I., Speth, E., Suess, R., Thomsen, H., Volpe, F., Wagner, F., Weller, A., Wendland, C., Werner, A., Wobig, H., Wuersching, E., and Zimmermann, D.

Published
2001
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50. Conceptual design and performance predictions for 2D beam emission spectroscopy turbulence measurements at Wendelstein 7-X.

Author

Smith, D. R., McKee, G., Den Hartog, D., Geiger, B., Grulke, O., Han, X., Jaehnig, K., Seyfert, C., and Windisch, T.

Subjects
EMISSION spectroscopy, CONCEPTUAL design, PLASMA turbulence, TURBULENCE, DOPPLER effect, LIGHT transmission, NEUTRAL beams
Abstract

A conceptual design for a 2D beam emission spectroscopy diagnostic system to measure ion gyro-scale plasma turbulence at Wendeslstein 7-X is described. The conceptual design identifies field-aligned viewing geometries and ports for cross-field turbulence measurements in the neutral beam volume. A 2D sightline grid covers the outer plasma region, and the grid configuration provides sufficient k-space coverage in radial and poloidal directions for ion temperature gradient and trapped-electron mode turbulence measurements. Emission intensity estimates, optical transmission losses, and detector noise levels indicate that the measurements will be sensitive to plasma density fluctuations as small as δn/n ≈ 0.5% with a bandwidth of 1 MHz. Implementation challenges include a small beam emission Doppler shift due to nearly radial heating beams and reduced optical throughput due to collection aperture limitations. [ABSTRACT FROM AUTHOR]

Published
2022
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