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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 × 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 facilitatedmore » 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; TRN: US2000921
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. https://doi.org/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. 2019. "Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase". United States. https://doi.org/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},
url = {https://www.osti.gov/biblio/1565869}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 26,
place = {United States},
year = {Tue Aug 13 00:00:00 EDT 2019},
month = {Tue Aug 13 00:00:00 EDT 2019}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 57 works
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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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Works referenced in this record:

Ripple transport in helical-axis advanced stellarators: a comparison with classical stellarator/torsatrons
journal, February 1994


Progress in the design and development of a test divertor (TDU) for the start of W7-X operation
journal, June 2009


Argon impurity transport studies at Wendelstein 7-X using x-ray imaging spectrometer measurements
journal, June 2017


First measurements of error fields on W7-X using flux surface mapping
journal, August 2016


Density limits in toroidal plasmas
journal, July 2002


Design improvement of the target elements of Wendelstein 7-X divertor
journal, August 2012


Overview of first Wendelstein 7-X high-performance operation
journal, June 2019


The WENDELSTEIN 7-X mechanical structure support elements: Design and tests
journal, November 2005


Remote-Steering Antennas for 140 GHz Electron Cyclotron Heating of the Stellarator W7-X
journal, January 2017


Stellarator and tokamak plasmas: a comparison
journal, November 2012


Performance and properties of the first plasmas of Wendelstein 7-X
journal, October 2016


Neoclassical transport simulations for stellarators
journal, February 2011


Comparison of particle trajectories and collision operators for collisional transport in nonaxisymmetric plasmas
journal, April 2014


Wendelstein 7-X Program—Demonstration of a Stellarator Option for Fusion Energy
journal, September 2016


Design and construction of WENDELSTEIN 7-X
journal, October 2001


Aspects of steady-state operation of the Wendelstein 7-X stellarator
journal, December 2012


Theory of plasma confinement in non-axisymmetric magnetic fields
journal, July 2014


Measurements and correction of the 1/1 error field in Wendelstein 7-X
journal, December 2018


Major results from the first plasma campaign of the Wendelstein 7-X stellarator
journal, July 2017


Study and design of the ion cyclotron resonance heating system for the stellarator Wendelstein 7-X
journal, June 2014


Comparison between stellarator and tokamak divertor transport
journal, January 2011


Divertor concept for the W7-X stellarator and mode of operation
journal, May 2002


Limiter observations during W7-X first plasmas
journal, April 2017


Up-scaling the island divertor along the W7-stellarator line
journal, July 2013


Overview of the Wendelstein 7-X phase contrast imaging diagnostic
journal, October 2018


Magnetic configuration effects on the Wendelstein 7-X stellarator
journal, May 2018


Chapter 6: Steady state operation
journal, June 2007


Key results from the first plasma operation phase and outlook for future performance in Wendelstein 7-X
journal, May 2017


Design and technological solutions for the plasma facing components of WENDELSTEIN 7-X
journal, October 2011


Progress in the Integrated Development of the Helical System
journal, August 2010


The Wendelstein 7-X Trim Coil System
journal, June 2014


Armoring of the Wendelstein 7-X divertor-observation immersion-tubes based on NBI fast-ion simulations
journal, September 2019


First island divertor experiments on the W7-AS stellarator
journal, November 2001


Core radial electric field and transport in Wendelstein 7-X plasmas
journal, February 2018


Physics in the magnetic configuration space of W7-X
journal, November 2014


Engineering Challenges in W7-X: Lessons Learned and Status for the Second Operation Phase
journal, May 2018


Major results from the stellarator Wendelstein 7-AS
journal, March 2008


Setup and initial results from the magnetic flux surface diagnostics at Wendelstein 7-X
journal, May 2016


Diamagnetic energy measurement during the first operational phase at the Wendelstein 7-X stellarator
journal, July 2018


ASCOT: Solving the kinetic equation of minority particle species in tokamak plasmas
journal, April 2014


Methods for measuring 1/1 error field in Wendelstein 7-X stellarator
journal, June 2016


Collisionless alpha -particle confinement in stellarators
journal, June 1992


Progress in the ITER Physics Basis
journal, June 2007


Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies
journal, November 2018


The Stellarator Concept
journal, January 1958


Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X
journal, November 2013


Final integration, commissioning and start of the Wendelstein 7-X stellarator operation
journal, August 2017


Infrared imaging systems for wall protection in the W7-X stellarator (invited)
journal, October 2018


CASTOR3D: linear stability studies for 2D and 3D tokamak equilibria
journal, November 2016


Design of the Wendelstein 7-X inertially cooled Test Divertor Unit Scraper Element
journal, October 2015


Wall conditioning throughout the first carbon divertor campaign on Wendelstein 7-X
journal, December 2018


Error fields in the Wendelstein 7-X stellarator
journal, November 2018


First results from divertor operation in Wendelstein 7-X
journal, November 2018


Sawtooth oscillations in tokamaks
journal, November 1990


ECRH and W7-X: An intriguing pair
conference, January 2014

  • Erckmann, V.; Braune, H.; Gantenbein, G.
  • REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Proceedings of the 35th Annual Review of Progress in Quantitative Nondestructive Evaluation, AIP Conference Proceedings
  • https://doi.org/10.1063/1.4864608

Current status of the neutral beam heating system of W7-X
journal, October 2013


Confirmation of the topology of the Wendelstein 7-X magnetic field to better than 1:100,000
journal, November 2016


Studies towards an upgraded 1.5 MW gyrotron for W7-X
journal, January 2019


Advanced electron cyclotron heating and current drive experiments on the stellarator Wendelstein 7-X
journal, January 2017


Correction possibilities of magnetic field errors in WENDELSTEIN 7-X
journal, November 2005


Das Fusionsexperiment WENDELSTEIN 7-X
journal, November 1993


Fast particle confinement with optimized coil currents in the W7-X stellarator
journal, April 2014


Modelling of NBI ion wall loads in the W7-X stellarator
journal, June 2018


The Thomson scattering system at Wendelstein 7-X
journal, September 2016


Sawtooth oscillations in tokamaks.
journal, January 1989


The Stellarator Concept
journal, January 1981


Overview of first Wendelstein 7-X high-performance operation
text, January 2019


Studies towards an upgraded 1.5 MW gyrotron for W7-X
text, January 2019


Works referencing / citing this record:

Coherence imaging spectroscopy at Wendelstein 7-X for impurity flow measurements
journal, January 2020


Soft x-ray tomography measurements in the Wendelstein 7-X stellarator
journal, January 2020


Suppression of electrostatic micro-instabilities in maximum- J stellarators
journal, January 2020