Potential structure measurements of ech plasma in a helical axis stellarator

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

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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

  • General Engineering
  • General Physics and Astronomy


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