Search

Your search keyword '"Association EURATOM-Risø National Laboratory"' showing total 12 results
Start Over Author "Association EURATOM-Risø National Laboratory"
12 results on '"Association EURATOM-Risø National Laboratory"'

1. Blob dynamics in the TORPEX experiment: a multi-code validation

Author

Eric Serre, J. Denis, Fabio Riva, Anders Nielsen, Ivo Furno, Christian Theiler, Volker Naulin, Jens Madsen, J. Juul Rasmussen, Luke Easy, Patrick Tamain, C. Colin, Fulvio Militello, Paolo Ricci, Jeppe Olsen, John Omotani, Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom, Culham Centre for Fusion Energy (CCFE), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Department of Physics, Department of Micro- and Nanotechnology, Technical University of Denmark (DTU), Lille économie management - UMR 9221 [LEM], Mines Paris - PSL (École nationale supérieure des mines de Paris), Ecole Polytechnique Fédérale de Lausanne [EPFL], Association EURATOM-Risø National Laboratory, Laboratoire de Mécanique, Modélisation et Procédés Propres [M2P2], Physique des interactions ioniques et moléculaires [PIIM], Lille économie management - LEM - UMR 9221 (LEM), Université de Lille-Université catholique de Lille (UCL)-Centre National de la Recherche Scientifique (CNRS), MINES ParisTech - École nationale supérieure des mines de Paris, aucun, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Dept. of Physics, University of Wisconsin-Madison, Technical University of Denmark [Lyngby] (DTU), Physique des interactions ioniques et moléculaires (PIIM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Tokamak, Dynamics (mechanics), CRPP_EDGE, Plasma, Condensed Matter Physics, Fluid models, 01 natural sciences, Stability (probability), [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, 010305 fluids & plasmas, law.invention, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Nuclear Energy and Engineering, law, Physics::Plasma Physics, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Multi code, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Statistical physics, Torpex, 010306 general physics
Abstract

International audience; Three-dimensional and two-dimensional seeded blob simulations are performed with five different fluid models, all based on the drift-reduced Braginskii equations, and the numerical results are compared among themselves and validated against experimental measurements provided by the TORPEX device ( Fasoli et al 2006 Phys. Plasmas 13 055902). The five models are implemented in four simulation codes, typically used to simulate the plasma dynamics in the tokamak scrape-off layer, namely BOUT++ (Dudson et al 2009 Comput. Phys. Commun. 180 1467), GBS (Ricci et al 2012 Plasma Phys. Control. Fusion 54 124047), HESEL (Nielsen et al 2015 Phys. Lett. A 379 3097), and TOKAM3X (Tamain et al 2014 Contrib. Plasma Phys. 54 555). Three blobs with different velocities and different stability properties are simulated. The differences observed among the simulation results and the different levels of agreement with experimental measurements are investigated, increasing our confidence in our simulation tools and shedding light on the blob dynamics. The comparisons demonstrate that the radial blob dynamics observed in the three-dimensional simulations is in good agreement with experimental measurements and that, in the present experimental scenario, the two-dimensional model derived under the assumption of k(vertical bar vertical bar) = 0 is able to recover the blob dynamics observed in the three-dimensional simulations. Moreover, it is found that an accurate measurement of the blob temperature is important to perform reliable seeded blob simulations.

Published
2016
Full Text
View/download PDF

2. 40th European Physical Society Conference on Plasma Physics

Author

Volker Naulin, Sylvie Jacquemot, Optics and Plasma Research [Roskilde], Association EURATOM-Risø National Laboratory, Technical University of Denmark [Lyngby] (DTU)-Technical University of Denmark [Lyngby] (DTU), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire pour l'utilisation des lasers intenses (LULI), Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Danmarks Tekniske Universitet = Technical University of Denmark (DTU)-Danmarks Tekniske Universitet = Technical University of Denmark (DTU)

Subjects
Physics, Nuclear Energy and Engineering, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Engineering ethics, Plasma, 010306 general physics, Condensed Matter Physics, 010303 astronomy & astrophysics, 01 natural sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2013
Full Text
View/download PDF

3. Overview of the TCV tokamak program: scientific progress and facility upgrades

Author

S. Mastrostefano, J.-Ph. Hogge, S. Nowak, W. Bin, Bogdan Hnat, Nuno Cruz, S. Allan, T. C. Blanken, Cristian Galperti, H. F. Meyer, M. Faitsch, Stefano Coda, Y. Andrebe, D. Rittich, E. Maljaars, Laust Emil Hjerrild Tophøj, C. Ham, P. Molina Cabrera, Alessandro Pau, Jonathan Graves, D. Douai, C.K. Tsui, H. Weisen, J-M Moret, Marco Gobbin, M. Nocente, David Moulton, Heinz Isliker, F. Sciortino, S. Vartanian, M. Koubiti, P. A. Schneider, V. P. Loschiavo, R. M. McDermott, E. Alessi, I Miron, Yann Camenen, F. Braunmüller, Duccio Testa, T. Odstrcil, J. Juul Rasmussen, J. Horacek, M. Sertoli, G. De Tommasi, Geert Verdoolaege, Patrick Maget, Gustavo Granucci, Timothy P. Robinson, M. Preynas, Cyrille Honoré, Benedikt Geiger, Paolo Innocente, C. Tsironis, A. Jardin, J.A. Boedo, Izaskun Garrido, M. Gospodarczyk, M. G. Dunne, F. Carpanese, M. Kong, Ondrej Ficker, N. Vianello, V. Igochine, P. Zestanakis, V. Pericoli Ridolfini, R. Scannell, T. Lunt, A. Malygin, J. Ahn, M. Bernert, G. Calabrò, Theophilos Pisokas, M. Wischmeier, Piero Martin, Fulvio Militello, B. Lomanowski, Benoit Labit, Giuseppe Gorini, Daniele Carnevale, A. Czarnecka, Faa Federico Felici, F. Saint-Laurent, B. Sieglin, X. Llobet, Patrick Tamain, M. Mavridis, G. Ciraolo, Ambrogio Fasoli, J. Sinha, F. Causa, Ch. Schlatter, J. Decker, Raffaele Albanese, P. Blanchard, F. Bouquey, C. Angioni, G. De Masi, R. McAdams, A. Moro, S. Garavaglia, Hugo Bufferand, Antoine Merle, O. Chellai, Torsten Stange, Laure Vermare, Loukas Vlahos, W. A. J. Vijvers, G. Pautasso, Olivier Février, N. A. Kirneva, H. Reimerdes, Timothy Goodman, Nicolas Fedorczak, Bruce Lipschultz, E. Lazzaro, C. Piron, Z. Huang, J. Kamleitner, James Harrison, Fabio Riva, Lorenzo Frassinetti, Paolo Ricci, Y. R. Martin, Anders Nielsen, B. Esposito, Jonathan Citrin, Antti Hakola, M. Reich, I. T. Chapman, Kevin Verhaegh, C. Marini, H.B. Le, V. Naulin, B. P. Duval, M. Silva, A. Gallo, J. Hawke, A. Krämer-Flecken, D. Hogeweij, N. Krawczyk, Roberto Maurizio, Ivo Furno, Marco Ariola, Christian Theiler, A. N. Karpushov, Jernej Kovacic, M. N. A. Beurskens, A. Uccello, M. Fontana, C. J. Rapson, Tom Wauters, Christian Hopf, C. Ionita Schrittwieser, S. Saarelma, T. Eich, T. Stoltzfus-Dueck, S. Fietz, P. Piovesan, R. Jacquier, D. Choi, H. Anand, Nick Walkden, Gergely Papp, F. Nespoli, D. L. Keeling, B. S. Schneider, Sergio Galeani, G. Ramogida, S. Elmore, E. Giovannozzi, Stefano Alberti, Rémy Nouailletas, O. Kudlacek, R. Guirlet, R. Papřok, Matteo Zuin, T. Bolzonella, F. Crisanti, D. Mazon, U. A. Sheikh, Pascale Hennequin, R. Cesario, A.J. Thornton, S. Costea, P. Buratti, C. Cianfarani, R. Schrittwieser, A. Teplukhina, N.M.T. Vu, Laurie Porte, M. Spolaore, Carlo Sozzi, Minh Quang Tran, M. Maraschek, Olivier Sauter, C. Reux, G. Anastassiou, Ramogida, G., Giovannozzi, E., Esposito, B., Cianfarani, C., Cesario, R., Causa, F., Calabró, G., Buratti, P., Max-Planck-Institut für Plasmaphysik [Garching] (IPP), EURATOM/CCFE Fusion Association, Culham Science Centre [Abingdon], Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences et Ingénierie Chimiques (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Associazone EURATOM ENEA sulla Fusione, EURATOM, Sygen International Plc, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-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), Institute of Plasma Physics, Association Euratom/IPP.CR (IPP PRAGUE), Czech Academy of Sciences [Prague] (CAS), York Plasma Institute (YPI), University of York [York, UK], Association EURATOM-CEA (CEA/DSM/DRFC), Association EURATOM-Risø National Laboratory, Technical University of Denmark [Lyngby] (DTU), Plateforme RX, UFR Chimie, Université Paris Diderot - Paris 7 (UPD7), Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Consiglio Nazionale delle Ricerche [Roma] (CNR), EUROfusion MST1 Team, Coda, S., Ahn, J., Albanese, Raffaele, Alberti, S., Alessi, E., Allan, S., Anand, H., Anastassiou, G., Andrèbe, Y., Angioni, C., Ariola, M., Bernert, M., Beurskens, M., Bin, W., Blanchard, P., Blanken, T. C., Boedo, J. A., Bolzonella, T., Bouquey, F., Braunmüller, F. H., Bufferand, H., Camenen, Y., Carnevale, D., Carpanese, F., Chapman, I. T., Chellai, O., Choi, D., Ciraolo, G., Citrin, J., Costea, S., Crisanti, F., Cruz, N., Czarnecka, A., Decker, J., De Masi, G., DE TOMMASI, Gianmaria, Douai, D., Dunne, M., Duval, B. P., Eich, T., Elmore, S., Faitsch, M., Fasoli, A., Fedorczak, N., Felici, F., Février, O., Ficker, O., Fietz, S., Fontana, M., Frassinetti, L., Furno, I., Galeani, S., Gallo, A., Galperti, C., Garavaglia, S., Garrido, I., Geiger, B., Gobbin, M., Goodman, T. P., Gorini, G., Gospodarczyk, M., Granucci, G., Graves, J. P., Guirlet, R., Hakola, A., Ham, C., Harrison, J., Hawke, J., Hennequin, P., Hnat, B., Hogeweij, D., Hogge, J. P. h., Honoré, C., Hopf, C., Horáček, J., Huang, Z., Igochine, V., Innocente, P., Ionita Schrittwieser, C., Isliker, H., Jacquier, R., Jardin, A., Kamleitner, J., Karpushov, A., Keeling, D. L., Kirneva, N., Kong, M., Koubiti, M., Kovacic, J., Krämer Flecken, A., Krawczyk, N., Kudlacek, O., Labit, B., Lazzaro, E., Le, H. B., Lipschultz, B., Llobet, X., Lomanowski, B., Loschiavo, VINCENZO PAOLO, Lunt, T., Maget, P., Maljaars, E., Malygin, A., Maraschek, M., Marini, C., Martin, P., Martin, Y., Mastrostefano, S., Maurizio, R., Mavridis, M., Mazon, D., Mcadams, R., Mcdermott, R., Merle, A., Meyer, H., Militello, F., Miron, I. G., Molina Cabrera, P. A., Moret, J. M., Moro, A., Moulton, D., Naulin, V., Nespoli, F., Nielsen, A. H., Nocente, M., Nouailletas, R., Nowak, S., Odstrčil, T., Papp, G., Papřok, R., Pau, A., Pautasso, G., Pericoli Ridolfini, V., Piovesan, P., Piron, C., Pisokas, T., Porte, L., Preynas, M., Rapson, C., Juul Rasmussen, J., Reich, M., Reimerdes, H., Reux, C., Ricci, P., Rittich, D., Riva, F., Robinson, T., Saarelma, S., Saint Laurent, F., Sauter, O., Scannell, R., Schlatter, C. h., Schneider, B., Schneider, P., Schrittwieser, R., Sciortino, F., Sertoli, M., Sheikh, U., Sieglin, B., Silva, M., Sinha, J., Sozzi, C., Spolaore, M., Stange, T., Stoltzfus Dueck, T., Tamain, P., Teplukhina, A., Testa, D., Theiler, C., Thornton, A., Tophøj, L., Tran, M. Q., Tsironis, C., Tsui, C., Uccello, A., Vartanian, S., Verdoolaege, G., Verhaegh, K., Vermare, L., Vianello, N., Vijvers, W. A. J., Vlahos, L., Vu, N. M. T., Walkden, N., Wauters, T., Weisen, H., Wischmeier, M., Zestanakis, P., Zuin, M., Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Coda, S, Ahn, J, Albanese, R, Alberti, S, Alessi, E, Allan, S, Anand, H, Anastassiou, G, Andrãbe, Y, Angioni, C, Ariola, M, Bernert, M, Beurskens, M, Bin, W, Blanchard, P, Blanken, T, Boedo, J, Bolzonella, T, Bouquey, F, Braunmã¼ller, F, Bufferand, H, Buratti, P, Calabrã³, G, Camenen, Y, Carnevale, D, Carpanese, F, Causa, F, Cesario, R, Chapman, I, Chellai, O, Choi, D, Cianfarani, C, Ciraolo, G, Citrin, J, Costea, S, Crisanti, F, Cruz, N, Czarnecka, A, Decker, J, De Masi, G, De Tommasi, G, Douai, D, Dunne, M, Duval, B, Eich, T, Elmore, S, Esposito, B, Faitsch, M, Fasoli, A, Fedorczak, N, Felici, F, Fã©vrier, O, Ficker, O, Fietz, S, Fontana, M, Frassinetti, L, Furno, I, Galeani, S, Gallo, A, Galperti, C, Garavaglia, S, Garrido, I, Geiger, B, Giovannozzi, E, Gobbin, M, Goodman, T, Gorini, G, Gospodarczyk, M, Granucci, G, Graves, J, Guirlet, R, Hakola, A, Ham, C, Harrison, J, Hawke, J, Hennequin, P, Hnat, B, Hogeweij, D, Hogge, J, Honorã©, C, Hopf, C, Horã¡ä ek, J, Huang, Z, Igochine, V, Innocente, P, Ionita Schrittwieser, C, Isliker, H, Jacquier, R, Jardin, A, Kamleitner, J, Karpushov, A, Keeling, D, Kirneva, N, Kong, M, Koubiti, M, Kovacic, J, Krämer-Flecken, A, Krawczyk, N, Kudlacek, O, Labit, B, Lazzaro, E, Le, H, Lipschultz, B, Llobet, X, Lomanowski, B, Loschiavo, V, Lunt, T, Maget, P, Maljaars, E, Malygin, A, Maraschek, M, Marini, C, Martin, P, Martin, Y, Mastrostefano, S, Maurizio, R, Mavridis, M, Mazon, D, Mcadams, R, Mcdermott, R, Merle, A, Meyer, H, Militello, F, Miron, I, Molina Cabrera, P, Moret, J, Moro, A, Moulton, D, Naulin, V, Nespoli, F, Nielsen, A, Nocente, M, Nouailletas, R, Nowak, S, Odsträ il, T, Papp, G, PapÅ™ok, R, Pau, A, Pautasso, G, Pericoli Ridolfini, V, Piovesan, P, Piron, C, Pisokas, T, Porte, L, Preynas, M, Ramogida, G, Rapson, C, Juul Rasmussen, J, Reich, M, Reimerdes, H, Reux, C, Ricci, P, Rittich, D, Riva, F, Robinson, T, Saarelma, S, Saint-Laurent, F, Sauter, O, Scannell, R, Schlatter, C, Schneider, B, Schneider, P, Schrittwieser, R, Sciortino, F, Sertoli, M, Sheikh, U, Sieglin, B, Silva, M, Sinha, J, Sozzi, C, Spolaore, M, Stange, T, Stoltzfus-Dueck, T, Tamain, P, Teplukhina, A, Testa, D, Theiler, C, Thornton, A, Tophã¸j, L, Tran, M, Tsironis, C, Tsui, C, Uccello, A, Vartanian, S, Verdoolaege, G, Verhaegh, K, Vermare, L, Vianello, N, Vijvers, W, Vlahos, L, Vu, N, Walkden, N, Wauters, T, Weisen, H, Wischmeier, M, Zestanakis, P, and Zuin, M

Subjects
Nuclear and High Energy Physics, Tokamak, Technology and Engineering, Nuclear engineering, Overview, overview, 01 natural sciences, 010305 fluids & plasmas, law.invention, Settore ING-INF/04 - Automatica, law, Control theory, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, 010306 general physics, tokamak, Nuclear and High Energy Physic, Physics, Toroid, Divertor, Magnetic confinement fusion, Plasma, Condensed Matter Physics, TCV, TRANSPORT, Magnetohydrodynamics, Beam (structure)
Abstract

a quiescent runaway beam carrying the entire electrical current appears to develop in some cases. Developments in plasma control have benefited from progress in individual controller design and have evolved steadily towards controller integration, mostly within an environment supervised by a tokamak profile control simulator. TCV has demonstrated effective wall conditioning with ECRH in He in support of the preparations for JT-60SA operation. © 2017 Ecole Polytechnique Federale de Lausanne., in particular, the double decay length in L-mode limited plasmas was found to be replaced by a single length at high SOL resistivity. Experiments on disruption mitigation by massive gas injection and electron-cyclotron resonance heating (ECRH) have begun in earnest, in parallel with studies of runaway electron generation and control, in both stable and disruptive conditions, The TCV tokamak is augmenting its unique historical capabilities (strong shaping, strong electron heating) with ion heating, additional electron heating compatible with high densities, and variable divertor geometry, in a multifaceted upgrade program designed to broaden its operational range without sacrificing its fundamental flexibility. The TCV program is rooted in a three-pronged approach aimed at ITER support, explorations towards DEMO, and fundamental research. A 1 MW, tangential neutral beam injector (NBI) was recently installed and promptly extended the TCV parameter range, with record ion temperatures and toroidal rotation velocities and measurable neutral-beam current drive. ITER-relevant scenario development has received particular attention, with strategies aimed at maximizing performance through optimized discharge trajectories to avoid MHD instabilities, such as peeling-ballooning and neoclassical tearing modes. Experiments on exhaust physics have focused particularly on detachment, a necessary step to a DEMO reactor, in a comprehensive set of conventional and advanced divertor concepts. The specific theoretical prediction of an enhanced radiation region between the two X-points in the low-field-side snowflake-minus configuration was experimentally confirmed. Fundamental investigations of the power decay length in the scrape-off layer (SOL) are progressing rapidly, again in widely varying configurations and in both D and He plasmas

Full Text
View/download PDF

4. Design and performance of the collective Thomson scattering receiver at ASDEX Upgrade.

Author

Furtula V, Salewski M, Leipold F, Michelsen PK, Korsholm SB, Meo F, Moseev D, Nielsen SK, Stejner M, and Johansen T

Abstract

Here we present the design of the fast-ion collective Thomson scattering receiver for millimeter wave radiation installed at ASDEX Upgrade, a tokamak for fusion plasma experiments. The receiver can detect spectral power densities of a few eV against the electron cyclotron emission background on the order of 100 eV under presence of gyrotron stray radiation that is several orders of magnitude stronger than the signal to be detected. The receiver down converts the frequencies of scattered radiation (100-110 GHz) to intermediate frequencies (IF) (4.5-14.5 GHz) by heterodyning. The IF signal is divided into 50 IF channels tightly spaced in frequency space. The channels are terminated by square-law detector diodes that convert the signal power into DC voltages. We present measurements of the transmission characteristics and performance of the main receiver components operating at mm-wave frequencies (notch, bandpass, and lowpass filters, a voltage-controlled variable attenuator, and an isolator), the down-converter unit, and the IF components (amplifiers, bandpass filters, and detector diodes). Furthermore, we determine the performance of the receiver as a unit through spectral response measurements and find reasonable agreement with the expectation based on the individual component measurements.

Published
2012
Full Text
View/download PDF

5. Measurements of intrinsic ion Bernstein waves in a tokamak by collective Thomson scattering.

Author

Korsholm SB, Stejner M, Bindslev H, Furtula V, Leipold F, Meo F, Michelsen PK, Moseev D, Nielsen SK, Salewski M, de Baar M, Delabie E, Kantor M, and Bürger A

Abstract

In this Letter we report measurements of collective Thomson scattering (CTS) spectra with clear signatures of ion Bernstein waves and ion cyclotron motion in tokamak plasmas. The measured spectra are in accordance with theoretical predictions and show clear sensitivity to variation in the density ratio of the main ion species in the plasma. Measurements with this novel diagnostic demonstrate that CTS can be used as a fuel ion ratio diagnostic in burning fusion plasma devices.

Published
2011
Full Text
View/download PDF

6. Broadband notch filter design for millimeter-wave plasma diagnostics.

Author

Furtula V, Michelsen PK, Leipold F, Salewski M, Korsholm SB, Meo F, Nielsen SK, Stejner M, Moseev D, and Johansen T

Abstract

Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ∼900 MHz, and a typical insertion loss below 2 dB in the passband of ±9 GHz. The design is based on a fundamental rectangular waveguide with eight cylindrical cavities coupled by T-junction apertures formed as thin slits. Parameters that affect the notch performance such as physical lengths and conductor materials are discussed. The excited resonance mode in the cylindrical cavities is the fundamental TE(11). The performance of the constructed filter is measured using a vector network analyzer monitoring a total bandwidth of 30 GHz. We compare the measurements with numerical simulations.

Published
2010
Full Text
View/download PDF

7. Antenna design for fast ion collective Thomson scattering diagnostic for the international thermonuclear experimental reactor.

Author

Leipold F, Furtula V, Salewski M, Bindslev H, Korsholm SB, Meo F, Michelsen PK, Moseev D, Nielsen SK, and Stejner M

Abstract

Fast ion physics will play an important role for the international thermonuclear experimental reactor (ITER), where confined alpha particles will affect and be affected by plasma dynamics and thereby have impacts on the overall confinement. A fast ion collective Thomson scattering (CTS) diagnostic using gyrotrons operated at 60 GHz will meet the requirements for spatially and temporally resolved measurements of the velocity distributions of confined fast alphas in ITER by evaluating the scattered radiation (CTS signal). While a receiver antenna on the low field side of the tokamak, resolving near perpendicular (to the magnetic field) velocity components, has been enabled, an additional antenna on the high field side (HFS) would enable measurements of near parallel (to the magnetic field) velocity components. A compact design solution for the proposed mirror system on the HFS is presented. The HFS CTS antenna is located behind the blankets and views the plasma through the gap between two blanket modules. The viewing gap has been modified to dimensions 30x500 mm(2) to optimize the CTS signal. A 1:1 mock-up of the HFS mirror system was built. Measurements of the beam characteristics for millimeter-waves at 60 GHz used in the mock-up agree well with the modeling.

Published
2009
Full Text
View/download PDF

8. Commissioning activities and first results from the collective Thomson scattering diagnostic on ASDEX Upgrade (invited).

Author

Meo F, Bindslev H, Korsholm SB, Furtula V, Leuterer F, Leipold F, Michelsen PK, Nielsen SK, Salewski M, Stober J, Wagner D, and Woskov P

Abstract

The collective Thomson scattering (CTS) diagnostic installed on ASDEX Upgrade uses millimeter waves generated by the newly installed 1 MW dual frequency gyrotron as probing radiation at 105 GHz. It measures backscattered radiation with a heterodyne receiver having 50 channels (between 100 and 110 GHz) to resolve the one-dimensional velocity distribution of the confined fast ions. The steerable antennas will allow different scattering geometries to fully explore the anisotropic fast ion distributions at different spatial locations. This paper covers the capabilities and operational limits of the diagnostic. It then describes the commissioning activities carried out to date. These activities include gyrotron studies, transmission line alignment, and beam pattern measurements in the vacuum vessel. Overlap experiments in near perpendicular and near parallel have confirmed the successful alignment of the system. First results in near perpendicular of scattered spectra in a neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH) plasma (minority hydrogen) on ASDEX Upgrade have shown evidence of ICRH heating phase of hydrogen.

Published
2008
Full Text
View/download PDF

9. Investigation of first mirror heating for the collective Thomson scattering diagnostic in ITER.

Author

Salewski M, Meo F, Bindslev H, Furtula V, Korsholm SB, Lauritzen B, Leipold F, Michelsen PK, Nielsen SK, and Nonbøl E

Abstract

Collective Thomson scattering (CTS) has the capabilities to measure phase space densities of fast ion populations in ITER resolved in configuration space, in velocity space, and in time. In the CTS system proposed for ITER, probing radiation at 60 GHz generated by two 1 MW gyrotrons is scattered in the plasma and collected by arrays of receivers. The transmission lines from the gyrotrons to the plasma and from the plasma to the receivers contain several quasioptical mirrors among other components. These are designed to produce astigmatic beam patterns in the plasma where the beam shapes will have a direct impact on the signal strength of the diagnostic, the spatial resolution, and the robustness of probe and receiver beam overlap against density excursions. The first mirror has a line of sight to the plasma and is thus exposed to severe neutron streaming. The present neutronics and thermomechanical modeling of a first mirror on the high field side indicates that the mirror curvature may warp due to heating. This may alter the beam quality, and therefore, thermal effects have to be accounted for during the design of the mirror. The modeling further demonstrates that thin mirrors are superior to thick mirrors from a thermomechanical point of view.

Published
2008
Full Text
View/download PDF

10. Impurity and trace tritium transport in tokamak edge turbulence.

Author

Naulin V

Abstract

The turbulent transport of impurity or minority species, as for example tritium, is investigated in drift-Alfvén edge turbulence. The full effects of perpendicular and parallel convection are kept for the impurity species. The impurity density develops a granular structure with steep gradients and locally exceeds its initial values due to the compressibility of the flow. An approximate decomposition of the impurity flux into a diffusive part and an effective convective part (characterized by a pinch velocity) is performed and a net inward pinch effect is recovered. The pinch velocity is explained in terms of turbulent equipartition [Phys. Plasmas 2, 2874 (1995)] and is found to vary poloidally. An approximate relationship between pinch velocity and turbulent diffusion is suggested.

Published
2005
Full Text
View/download PDF

11. Computations of intermittent transport in scrape-off layer plasmas.

Author

Garcia OE, Naulin V, Nielsen AH, and Rasmussen JJ

Abstract

Two-dimensional fluid simulations of interchange turbulence for geometry and parameters relevant for the scrape-off layer of magnetized plasmas are presented. The computations, which have distinct plasma production and loss regions, reveal bursty ejection of particles and heat from the bulk plasma in the form of blobs. These structures propagate far into the scrape-off layer where they are dissipated due to transport along open magnetic field lines. From single-point recordings it is shown that the blobs have asymmetric conditional wave forms and lead to positively skewed and flattened probability distribution functions. The radial propagation velocity may reach one-tenth of the sound speed. These results are in excellent agreement with recent experimental measurements.

Published
2004
Full Text
View/download PDF

12. Bursting and large-scale intermittency in turbulent convection with differential rotation.

Author

Garcia OE and Bian NH

Abstract

The tilting mechanism, which generates differential rotation in two-dimensional turbulent convection, is shown to produce relaxation oscillations in the mean flow energy integral and bursts in the global fluctuation level, akin to Lotka-Volterra oscillations. The basic reason for such behavior is the unidirectional and conservative transfer of kinetic energy from the fluctuating motions to the mean component of the flows, and its dissipation at large scales. Results from numerical simulations further demonstrate the intimate relation between these low-frequency modulations and the large-scale intermittency of convective turbulence, as manifested by exponential tails in single-point probability distribution functions. Moreover, the spatio-temporal evolution of convective structures illustrates the mechanism triggering avalanche events in the transport process. The latter involves the overlap of delocalized mixing regions when the barrier to transport, produced by the mean component of the flow, transiently disappears.

Published
2003
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results