Potential structure measurements of ech plasma in a helical axis stellarator

Sumio Kitajima, Ryohta Kudoh, Shigeru Inagaki, Eiji Nakamura, Masakazu Takayama, Hiroshige Watanabe

Research output: Contribution to journalArticle


ECH plasma potential structures were measured by Langmuir probes in the Tohoku University HELIAC. By adjusting the coil current ratio of the center conductor and the toroidal coils, 2 characteristic configurations were selected, the 1st case with the n ̸ m = 3/2 rational surface, the 2nd case without the rational surface. A perturbation field was added in the 1st case in order to produce m=2 magnetic islands. Before ECH turn-off the potential structure near the ECH antenna strongly depends on MOD B surfaces; on the other hand, away from antenna the potential structure agrees well with magnetic surfaces, but peculiar regions resembling m=2 islands appear along a rational surface and disappear in the case without a rational surface. After ECH turn-off both potential structures, near and away from the antenna, not only agree very well with magnetic surfaces, but also preserve the magnetic island structures.

Original languageEnglish
Pages (from-to)4223-4229
Number of pages7
JournalJapanese Journal of Applied Physics
Issue number8 R
Publication statusPublished - Aug 1995
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

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