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

S. A. Bozhenkov, M. W. Jakubowski, H. Niemann, S. A. Lazerson, G. A. Wurden, C. Biedermann, G. Kocsis, R. König, F. Pisano, L. Stephey, T. Szepesi, U. Wenzel, T. S. Pedersen, R. C. Wolf

Research output: Contribution to journalArticle

8 Citations (Scopus)

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. These results are also of interest for the later W7-X divertor operation.

Original languageEnglish
Article number126030
JournalNuclear Fusion
Volume57
Issue number12
DOIs
Publication statusPublished - Sep 27 2017

Keywords

  • error fields
  • limiter
  • limiter symmetry
  • stellarator fields
  • Wendelstein 7-X

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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    Bozhenkov, S. 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. (2017). Effect of error field correction coils on W7-X limiter loads. Nuclear Fusion, 57(12), [126030]. https://doi.org/10.1088/1741-4326/aa85ce