[Table of Contents]

Plasma and Fusion Research

Volume 2, S1090 (2007)

Regular Articles

Advanced Probe Measurement System in TU-Heliac
Yutaka TANAKA, Hiromi TAKAHASHI, Hiroyasu UTOH, Michiaki OGAWA, Junji SHINDE, Hiroshi AOYAMA, Keisuke IWAZAKI, Hajime UMETSU, Atsushi OKAMOTO, Katsuhiro SHINTO, Sumio KITAJIMA, Masayuki YOKOYAMA1), Shigeru INAGAKI1), Yasuhiro SUZUKI1), Kiyohiko NISHIMURA1) and Mamiko SASAO
Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, 980-8579, Japan
1)
National Institute for Fusion Science, Toki, 509-5292, Japan
(Received 4 December 2006 / Accepted 31 March 2007 / Published 20 November 2007)

Abstract

An advanced probe measurement system consisting of high-speed Langmuir probes with a preamplifier and a Copper shield was designed and installed in TU-Heliac. Potential and density fluctuations were measured in the hot-cathode biased plasma, and power spectra were calculated using the complex Fourier transform. There were low frequency fluctuations (f < 10 kHz), high frequency fluctuations (70 < f < 200 kHz) and sharp spectra applied for the plasma production (10 < f < 50 kHz). In the region above 200 kHz, the power decreased by a factor of 1/f2 for the potential fluctuation and 1/f2∼3 for the density fluctuation. The phase shift between potential and density fluctuations was almost 0 rad at ρ = 0.54. On the other hand, the phase shift was not 0 rad at ρ = 0.21, especially in the 100 ∼ 200 kHz region. The high frequency fluctuation at ρ = 0.21 grew on the time scale of 10-5 s, which was obtained from the time dependent signals of the high frequency fluctuation.

Keywords

heliac, electrode biasing, poloidal flow, fluctuation, instability

DOI: 10.1585/pfr.2.S1090

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This paper may be cited as follows:

Yutaka TANAKA, Hiromi TAKAHASHI, Hiroyasu UTOH, Michiaki OGAWA, Junji SHINDE, Hiroshi AOYAMA, Keisuke IWAZAKI, Hajime UMETSU, Atsushi OKAMOTO, Katsuhiro SHINTO, Sumio KITAJIMA, Masayuki YOKOYAMA, Shigeru INAGAKI, Yasuhiro SUZUKI, Kiyohiko NISHIMURA and Mamiko SASAO, Plasma Fusion Res. 2, S1090 (2007).