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Title: Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase

Abstract

Wendelstein 7-X is the first comprehensively optimized stellarator aiming at good confinement with plasma parameters relevant to a future stellarator power plant. Plasma operation started in 2015 using a limiter configuration. After installing an uncooled magnetic island divertor, extending the energy limit from 4 to 80 MJ, operation continued in 2017. For this phase, the electron cyclotron resonance heating (ECRH) capability was extended to 7 MW, and hydrogen pellet injection was implemented. The enhancements resulted in the highest triple product (6.5 × 10 19 keV m ₋3 s) achieved in a stellarator until now. Plasma conditions [T e(0) ≈ T i(0) ≈ 3.8 keV, τ E > 200 ms] already were in the stellarator reactor-relevant ion-root plasma transport regime. Stable operation above the 2nd harmonic ECRH X-mode cutoff was demonstrated, which is instrumental for achieving high plasma densities in Wendelstein 7-X. Further important developments include the confirmation of low intrinsic error fields, the observation of current-drive induced instabilities, and first fast ion heating and confinement experiments. The efficacy of the magnetic island divertor was instrumental in achieving high performance in Wendelstein 7-X. Symmetrization of the heat loads between the ten divertor modules could be achieved by external resonant magnetic fields.more » Full divertor power detachment facilitated the extension of high power plasmas significantly beyond the energy limit of 80 MJ.« less

Authors:
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  1. Max-Planck-Institut für Plasmaphysik, Wendelsteinstrasse 1, 17491 Greifswald, Germany
  2. Laboratorio Nacional de Fusión, CIEMAT, Avenida Complutense, 40, 28040 Madrid, Spain
  3. Research Center Jülich, Institute for Energy and Climate Research Plasma Physics, Wilhelm-Johnen-Strasse, 52428 Jülich, Germany
  4. University of Wisconsin Madison, Engineering Drive, Madison, Wisconsin 53706, USA
  5. Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany
  6. National Institute for Fusion Science, 322-6 Oroshicho, Toki, Gifu Prefecture 509-5202, Japan
  7. Laboratory for Plasma Physics, LPP-ERM/KMS, Avenue de la Renaissance 30, B-1000 Brussels, Belgium
  8. Princeton Plasma Physics Laboratory, 100 Stellarator Rd., Princeton, New Jersey 08540, USA
  9. Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
  10. Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC). Fusion Energy Sciences (FES) (SC-24)
Contributing Org.:
the Wendelstein 7-X Team
OSTI Identifier:
1565869
Report Number(s):
LA-UR-19-23413
Journal ID: ISSN 1070-664X
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 8; Conference: 60. Annual Meeting of the APS Division of Plasma Physics, Portland, OR (United States), 5-9 Nov 2018; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Wendelstein 7-X; divertor; detachment; long-pulse

Citation Formats

Wolf, R. C., Alonso, A., Äkäslompolo, S., Baldzuhn, J., Beurskens, M., Beidler, C. D., Biedermann, C., Bosch, H. -S., Bozhenkov, S., Brakel, R., Braune, H., Brezinsek, S., Brunner, K. -J., Damm, H., Dinklage, A., Drewelow, P., Effenberg, F., Feng, Y., Ford, O., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Harder, N., Hartmann, D., Helander, P., Heinemann, B., Hirsch, M., Höfel, U., Hopf, C., Ida, K., Isobe, M., Jakubowski, M. W., Kazakov, Y. O., Killer, C., Klinger, T., Knauer, J., König, R., Krychowiak, M., Langenberg, A., Laqua, H. P., Lazerson, S., McNeely, P., Marsen, S., Marushchenko, N., Nocentini, R., Ogawa, K., Orozco, G., Osakabe, M., Otte, M., Pablant, N., Pasch, E., Pavone, A., Porkolab, M., Puig Sitjes, A., Rahbarnia, K., Riedl, R., Rust, N., Scott, E., Schilling, J., Schroeder, R., Stange, T., von Stechow, A., Strumberger, E., Sunn Pedersen, T., Svensson, J., Thomson, H., Turkin, Y., Vano, L., Wauters, T., Wurden, G., Yoshinuma, M., Zanini, M., and Zhang, D. Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase. United States: N. p., 2019. Web. doi:10.1063/1.5098761.
Wolf, R. C., Alonso, A., Äkäslompolo, S., Baldzuhn, J., Beurskens, M., Beidler, C. D., Biedermann, C., Bosch, H. -S., Bozhenkov, S., Brakel, R., Braune, H., Brezinsek, S., Brunner, K. -J., Damm, H., Dinklage, A., Drewelow, P., Effenberg, F., Feng, Y., Ford, O., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Harder, N., Hartmann, D., Helander, P., Heinemann, B., Hirsch, M., Höfel, U., Hopf, C., Ida, K., Isobe, M., Jakubowski, M. W., Kazakov, Y. O., Killer, C., Klinger, T., Knauer, J., König, R., Krychowiak, M., Langenberg, A., Laqua, H. P., Lazerson, S., McNeely, P., Marsen, S., Marushchenko, N., Nocentini, R., Ogawa, K., Orozco, G., Osakabe, M., Otte, M., Pablant, N., Pasch, E., Pavone, A., Porkolab, M., Puig Sitjes, A., Rahbarnia, K., Riedl, R., Rust, N., Scott, E., Schilling, J., Schroeder, R., Stange, T., von Stechow, A., Strumberger, E., Sunn Pedersen, T., Svensson, J., Thomson, H., Turkin, Y., Vano, L., Wauters, T., Wurden, G., Yoshinuma, M., Zanini, M., & Zhang, D. Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase. United States. doi:10.1063/1.5098761.
Wolf, R. C., Alonso, A., Äkäslompolo, S., Baldzuhn, J., Beurskens, M., Beidler, C. D., Biedermann, C., Bosch, H. -S., Bozhenkov, S., Brakel, R., Braune, H., Brezinsek, S., Brunner, K. -J., Damm, H., Dinklage, A., Drewelow, P., Effenberg, F., Feng, Y., Ford, O., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Harder, N., Hartmann, D., Helander, P., Heinemann, B., Hirsch, M., Höfel, U., Hopf, C., Ida, K., Isobe, M., Jakubowski, M. W., Kazakov, Y. O., Killer, C., Klinger, T., Knauer, J., König, R., Krychowiak, M., Langenberg, A., Laqua, H. P., Lazerson, S., McNeely, P., Marsen, S., Marushchenko, N., Nocentini, R., Ogawa, K., Orozco, G., Osakabe, M., Otte, M., Pablant, N., Pasch, E., Pavone, A., Porkolab, M., Puig Sitjes, A., Rahbarnia, K., Riedl, R., Rust, N., Scott, E., Schilling, J., Schroeder, R., Stange, T., von Stechow, A., Strumberger, E., Sunn Pedersen, T., Svensson, J., Thomson, H., Turkin, Y., Vano, L., Wauters, T., Wurden, G., Yoshinuma, M., Zanini, M., and Zhang, D. Tue . "Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase". United States. doi:10.1063/1.5098761. https://www.osti.gov/servlets/purl/1565869.
@article{osti_1565869,
title = {Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase},
author = {Wolf, R. C. and Alonso, A. and Äkäslompolo, S. and Baldzuhn, J. and Beurskens, M. and Beidler, C. D. and Biedermann, C. and Bosch, H. -S. and Bozhenkov, S. and Brakel, R. and Braune, H. and Brezinsek, S. and Brunner, K. -J. and Damm, H. and Dinklage, A. and Drewelow, P. and Effenberg, F. and Feng, Y. and Ford, O. and Fuchert, G. and Gao, Y. and Geiger, J. and Grulke, O. and Harder, N. and Hartmann, D. and Helander, P. and Heinemann, B. and Hirsch, M. and Höfel, U. and Hopf, C. and Ida, K. and Isobe, M. and Jakubowski, M. W. and Kazakov, Y. O. and Killer, C. and Klinger, T. and Knauer, J. and König, R. and Krychowiak, M. and Langenberg, A. and Laqua, H. P. and Lazerson, S. and McNeely, P. and Marsen, S. and Marushchenko, N. and Nocentini, R. and Ogawa, K. and Orozco, G. and Osakabe, M. and Otte, M. and Pablant, N. and Pasch, E. and Pavone, A. and Porkolab, M. and Puig Sitjes, A. and Rahbarnia, K. and Riedl, R. and Rust, N. and Scott, E. and Schilling, J. and Schroeder, R. and Stange, T. and von Stechow, A. and Strumberger, E. and Sunn Pedersen, T. and Svensson, J. and Thomson, H. and Turkin, Y. and Vano, L. and Wauters, T. and Wurden, G. and Yoshinuma, M. and Zanini, M. and Zhang, D.},
abstractNote = {Wendelstein 7-X is the first comprehensively optimized stellarator aiming at good confinement with plasma parameters relevant to a future stellarator power plant. Plasma operation started in 2015 using a limiter configuration. After installing an uncooled magnetic island divertor, extending the energy limit from 4 to 80 MJ, operation continued in 2017. For this phase, the electron cyclotron resonance heating (ECRH) capability was extended to 7 MW, and hydrogen pellet injection was implemented. The enhancements resulted in the highest triple product (6.5 × 1019 keV m₋3 s) achieved in a stellarator until now. Plasma conditions [Te(0) ≈ Ti(0) ≈ 3.8 keV, τE > 200 ms] already were in the stellarator reactor-relevant ion-root plasma transport regime. Stable operation above the 2nd harmonic ECRH X-mode cutoff was demonstrated, which is instrumental for achieving high plasma densities in Wendelstein 7-X. Further important developments include the confirmation of low intrinsic error fields, the observation of current-drive induced instabilities, and first fast ion heating and confinement experiments. The efficacy of the magnetic island divertor was instrumental in achieving high performance in Wendelstein 7-X. Symmetrization of the heat loads between the ten divertor modules could be achieved by external resonant magnetic fields. Full divertor power detachment facilitated the extension of high power plasmas significantly beyond the energy limit of 80 MJ.},
doi = {10.1063/1.5098761},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 26,
place = {United States},
year = {2019},
month = {8}
}

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Figures / Tables:

FIG. 11 FIG. 11: Coil arrangement of W7-X, showing the shaped modular coils, the planar coils (both superconducting) and four (out of five) trim coils (normally conducting), which are used to correct the intrinsic error fields. Selected magnetic flux surfaces and in the foreground magnetic field lines are also illustrated (for illustrationmore » purposes, the magnetic field coils in the foreground are cut away; reproduced with permission from Sunn Pedersen et al., Nat. Commun. 7, 13493 (2016). Copyright 2016 Springer Nature).« less

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