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Title: Effect of error field correction coils on W7-X limiter loads

Abstract

In the first campaign Wendelstein 7-X was operated with five poloidal graphite limiters installed stellarator symmetrically. In an ideal situation the power losses would be equally distributed between the limiters. The limiter shape was designed to smoothly distribute the heat flux over two strike lines. Vertically the strike lines are not uniform because of different connection lengths. In this paper it is demonstrated both numerically and experimentally that the heat flux distribution can be significantly changed by non-resonant $n=1$ perturbation field of the order of $$10^{-4}$$ . Numerical studies are performed with field line tracing. In experiments perturbation fields are excited with five error field trim coils. The limiters are diagnosed with infrared cameras, neutral gas pressure gauges, thermocouples and spectroscopic diagnostics. Experimental results are qualitatively consistent with the simulations. With a suitable choice of the phase and amplitude of the perturbation a more symmetric plasma-limiter interaction can be potentially achieved. Finally, these results are also of interest for the later W7-X divertor operation.

Authors:
 [1];  [1];  [1]; ORCiD logo [2]; ORCiD logo [3];  [1];  [4];  [1];  [5];  [6];  [4];  [1];  [1];  [1]
  1. Max-Planck-Institut fur Plasmaphysik, Greifswald (Germany)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Wigner Institute, Budapest (Hungary)
  5. Univ. of Cagliari (Italy)
  6. Univ. of Wisconsin, Madison, WI (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
EUROfusion Consortiumand has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053.; USDOE
Contributing Org.:
[W7-X Team]
OSTI Identifier:
1466524
Grant/Contract Number:  
[633053]
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
[ Journal Volume: 57; Journal Issue: 12]; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Wendelstein 7-X; limiter; limiter symmetry; error fields; stellarator fields

Citation Formats

Bozhenkov, Sergey A., Jakubowski, M. W., Niemann, H., Lazerson, S. A., Wurden, G. A., Biedermann, C., Kocsis, G., König, R., Pisano, F., Stephey, L., Szepesi, T., Wenzel, U., Pedersen, T. S., and Wolf, R. C. Effect of error field correction coils on W7-X limiter loads. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa85ce.
Bozhenkov, Sergey A., Jakubowski, M. W., Niemann, H., Lazerson, S. A., Wurden, G. A., Biedermann, C., Kocsis, G., König, R., Pisano, F., Stephey, L., Szepesi, T., Wenzel, U., Pedersen, T. S., & Wolf, R. C. Effect of error field correction coils on W7-X limiter loads. United States. doi:10.1088/1741-4326/aa85ce.
Bozhenkov, Sergey A., Jakubowski, M. W., Niemann, H., Lazerson, S. A., Wurden, G. A., Biedermann, C., Kocsis, G., König, R., Pisano, F., Stephey, L., Szepesi, T., Wenzel, U., Pedersen, T. S., and Wolf, R. C. Wed . "Effect of error field correction coils on W7-X limiter loads". United States. doi:10.1088/1741-4326/aa85ce. https://www.osti.gov/servlets/purl/1466524.
@article{osti_1466524,
title = {Effect of error field correction coils on W7-X limiter loads},
author = {Bozhenkov, Sergey A. and Jakubowski, M. W. and Niemann, H. and Lazerson, S. A. and Wurden, G. A. and Biedermann, C. and Kocsis, G. and König, R. and Pisano, F. and Stephey, L. and Szepesi, T. and Wenzel, U. and Pedersen, T. S. and Wolf, R. C.},
abstractNote = {In the first campaign Wendelstein 7-X was operated with five poloidal graphite limiters installed stellarator symmetrically. In an ideal situation the power losses would be equally distributed between the limiters. The limiter shape was designed to smoothly distribute the heat flux over two strike lines. Vertically the strike lines are not uniform because of different connection lengths. In this paper it is demonstrated both numerically and experimentally that the heat flux distribution can be significantly changed by non-resonant $n=1$ perturbation field of the order of $10^{-4}$ . Numerical studies are performed with field line tracing. In experiments perturbation fields are excited with five error field trim coils. The limiters are diagnosed with infrared cameras, neutral gas pressure gauges, thermocouples and spectroscopic diagnostics. Experimental results are qualitatively consistent with the simulations. With a suitable choice of the phase and amplitude of the perturbation a more symmetric plasma-limiter interaction can be potentially achieved. Finally, these results are also of interest for the later W7-X divertor operation.},
doi = {10.1088/1741-4326/aa85ce},
journal = {Nuclear Fusion},
number = [12],
volume = [57],
place = {United States},
year = {2017},
month = {9}
}

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