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Title: Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies

Abstract

For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 × 10 20 keV m –3 s), observed up to now in stellarators, was achieved. For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Furthermore, sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.

Authors:
ORCiD logo; ORCiD logo; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
the Wendelstein 7-X Team
OSTI Identifier:
1485472
Grant/Contract Number:  
Grant agreement No 633053
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 61; Journal Issue: 1; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; stellarator; Wendelstein 7-X; electron-cyclotron-resonance heating and current drive

Citation Formats

Wolf, R. C., Bozhenkov, S., Dinklage, A., Fuchert, G., Kazakov, Y. O., Laqua, H. P., Marsen, S., Marushchenko, N. B., Stange, T., Zanini, M., Abramovic, I., Alonso, A., Baldzuhn, J., Beurskens, M., Beidler, C. D., Braune, H., Brunner, K. J., Chaudhary, N., Damm, H., Drewelow, P., Gantenbein, G., Gao, Yu, Geiger, J., Hirsch, M., Höfel, U., Jakubowski, M., Jelonnek, J., Jensen, T., Kasparek, W., Knauer, J., Korsholm, S. B., Langenberg, A., Lechte, C., Leipold, F., Mora, H. Trimino, Neuner, U., Nielsen, S. K., Moseev, D., Oosterbeek, H., Pablant, N., Pasch, E., Plaum, B., Pedersen, T. Sunn, Sitjes, A. Puig, Rahbarnia, K., Rasmussen, J., Salewski, M., Schilling, J., Scott, E., Stejner, M., Thomsen, H., Thumm, M., Turkin, Y., and Wilde, F. Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies. United States: N. p., 2018. Web. doi:10.1088/1361-6587/aaeab2.
Wolf, R. C., Bozhenkov, S., Dinklage, A., Fuchert, G., Kazakov, Y. O., Laqua, H. P., Marsen, S., Marushchenko, N. B., Stange, T., Zanini, M., Abramovic, I., Alonso, A., Baldzuhn, J., Beurskens, M., Beidler, C. D., Braune, H., Brunner, K. J., Chaudhary, N., Damm, H., Drewelow, P., Gantenbein, G., Gao, Yu, Geiger, J., Hirsch, M., Höfel, U., Jakubowski, M., Jelonnek, J., Jensen, T., Kasparek, W., Knauer, J., Korsholm, S. B., Langenberg, A., Lechte, C., Leipold, F., Mora, H. Trimino, Neuner, U., Nielsen, S. K., Moseev, D., Oosterbeek, H., Pablant, N., Pasch, E., Plaum, B., Pedersen, T. Sunn, Sitjes, A. Puig, Rahbarnia, K., Rasmussen, J., Salewski, M., Schilling, J., Scott, E., Stejner, M., Thomsen, H., Thumm, M., Turkin, Y., & Wilde, F. Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies. United States. doi:10.1088/1361-6587/aaeab2.
Wolf, R. C., Bozhenkov, S., Dinklage, A., Fuchert, G., Kazakov, Y. O., Laqua, H. P., Marsen, S., Marushchenko, N. B., Stange, T., Zanini, M., Abramovic, I., Alonso, A., Baldzuhn, J., Beurskens, M., Beidler, C. D., Braune, H., Brunner, K. J., Chaudhary, N., Damm, H., Drewelow, P., Gantenbein, G., Gao, Yu, Geiger, J., Hirsch, M., Höfel, U., Jakubowski, M., Jelonnek, J., Jensen, T., Kasparek, W., Knauer, J., Korsholm, S. B., Langenberg, A., Lechte, C., Leipold, F., Mora, H. Trimino, Neuner, U., Nielsen, S. K., Moseev, D., Oosterbeek, H., Pablant, N., Pasch, E., Plaum, B., Pedersen, T. Sunn, Sitjes, A. Puig, Rahbarnia, K., Rasmussen, J., Salewski, M., Schilling, J., Scott, E., Stejner, M., Thomsen, H., Thumm, M., Turkin, Y., and Wilde, F. Tue . "Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies". United States. doi:10.1088/1361-6587/aaeab2. https://www.osti.gov/servlets/purl/1485472.
@article{osti_1485472,
title = {Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies},
author = {Wolf, R. C. and Bozhenkov, S. and Dinklage, A. and Fuchert, G. and Kazakov, Y. O. and Laqua, H. P. and Marsen, S. and Marushchenko, N. B. and Stange, T. and Zanini, M. and Abramovic, I. and Alonso, A. and Baldzuhn, J. and Beurskens, M. and Beidler, C. D. and Braune, H. and Brunner, K. J. and Chaudhary, N. and Damm, H. and Drewelow, P. and Gantenbein, G. and Gao, Yu and Geiger, J. and Hirsch, M. and Höfel, U. and Jakubowski, M. and Jelonnek, J. and Jensen, T. and Kasparek, W. and Knauer, J. and Korsholm, S. B. and Langenberg, A. and Lechte, C. and Leipold, F. and Mora, H. Trimino and Neuner, U. and Nielsen, S. K. and Moseev, D. and Oosterbeek, H. and Pablant, N. and Pasch, E. and Plaum, B. and Pedersen, T. Sunn and Sitjes, A. Puig and Rahbarnia, K. and Rasmussen, J. and Salewski, M. and Schilling, J. and Scott, E. and Stejner, M. and Thomsen, H. and Thumm, M. and Turkin, Y. and Wilde, F.},
abstractNote = {For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 × 1020 keV m–3 s), observed up to now in stellarators, was achieved. For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Furthermore, sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.},
doi = {10.1088/1361-6587/aaeab2},
journal = {Plasma Physics and Controlled Fusion},
number = 1,
volume = 61,
place = {United States},
year = {2018},
month = {11}
}

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Figures / Tables:

Figure 1 Figure 1: Illustration of one-half of the W7-X ECRH facility (reproduced with permission from [22]). The gyrotron beams are collected in the single-beam section and optically transmitted together over approximately 30 m in the multi-beam section, before they are divided into single beams again near the launchers. The other halfmore » of the facility (not shown) is a mirror image of the one shown.« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.