Plasma and Fusion Research

Volume 3, S1055 (2008)

Regular Articles

Density Collapse and Fluctuation Observed in Poloidally Rotating Plasma on TU-Heliac
Yutaka TANAKA, Sumio KITAJIMA, Mamiko SASAO, Hiroyasu UTOH, Hiroshi AOYAMA, Keisuke IWAZAKI, Hajime UMETSU, Keiichi ISHII, Atsushi OKAMOTO, Takashi KOBUCHI, Shigeru INAGAKI1), Yasuhiro SUZUKI2) and Hiromi TAKAHASHI2)
Department of Quantum Science and Energy Engineering, Tohoku University, Sendai 980-8579, Japan
1)
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
2)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 16 November 2007 / Accepted 30 March 2008 / Published 1 August 2008)

Abstract

The ohmic heated plasma in TU-Heliac was biased by a hot-cathode to drive E × B poloidal rotation. Coincident measurements of the line density and ion saturation currents revealed the existence of density collapse accompanied by fluctuation in the poloidally rotating plasma. The radial density profiles just before and after the collapse were estimated. The steep density gradient vanished with the density collapse. The power spectra of the fluctuation were calculated from the ion saturation current obtained with a high-speed triple probe. The frequency of fluctuation was compared to the E × B poloidal rotation frequency, where the fluctuation appeared with density collapse. The fluctuation frequency was 2 to 3 times the rotation frequency. This suggested that the poloidal mode number of fluctuation was m =2 or 3.

Keywords

heliac, stellarator, poloidal rotation, density collapse, fluctuation

DOI: 10.1585/pfr.3.S1055

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This paper may be cited as follows:

Yutaka TANAKA, Sumio KITAJIMA, Mamiko SASAO, Hiroyasu UTOH, Hiroshi AOYAMA, Keisuke IWAZAKI, Hajime UMETSU, Keiichi ISHII, Atsushi OKAMOTO, Takashi KOBUCHI, Shigeru INAGAKI, Yasuhiro SUZUKI and Hiromi TAKAHASHI, Plasma Fusion Res. 3, S1055 (2008).