Frequency Spectrum of Fluctuations Near a Rational Surface in a Toroidal Heliac
- 1 March 1993
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 32 (3A) , L349
- https://doi.org/10.1143/jjap.32.l349
Abstract
Density and space potential fluctuations have been studied in electron cyclotron resonance heating (ECRH) plasma of a helical axis stellarator TU Heliac using Langmuir probe techniques. These fluctuations are coherent and global, which can be explained by a drift instability model in cylindrical geometry. A particular fluctuation mode vanishes inside a rational surface. The ratio of this mode, n/m, corresponds to the rotational transform ι/ of this rational surface, (m, n: poloidal, toroidal fluctuation modes, respectively). This phenomenon near the rational surface can also be explained by a drift instability theory.Keywords
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