[Table of Contents]

Plasma and Fusion Research

Volume 5, S1039 (2010)

Regular Articles

Observation of Space and Energy Distributions of High Energy Electrons Produced in ECH Plasmas of LHD
Sadatsugu MUTO, Shigeru MORITA, Shin KUBO, Hiroe IGAMI, Yasuo YOSHIMURA, Hiromi TAKAHASHI, Takashi SHIMOZUMA and LHD Experimental Group
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
(Received 6 March 2009 / Accepted 8 July 2009 / Published 26 March 2010)

Abstract

Hard x-ray spectrum has been studied with x-ray pulse-height analyzer (PHA) in Large Helical Device (LHD). The hard x-ray emissions have been observed in high temperature plasmas heated by electron cyclotron heating (ECH). The radial distribution of the hard x-ray emissions is quantitatively derived from the line-integrated spectrum through an Abel inversion. When the bulk electron density ranges at 2.0 × 1018 m−3, the hard x-ray emissions are measured to be the most intense. From an analysis on the spectrum it is quantitatively proved that the energy-distribution function of the suprathermal electrons produced by ECH remarkably deviates from that of thermal electrons. The relaxation time of the high energy electrons is estimated to be 70 ms from the exponential decay rate after turning off the ECH pulse.

Keywords

hard x-ray emission, pulse height analyzer, suprathermal electron, Large Helical Device

DOI: 10.1585/pfr.5.S1039

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References

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This paper may be cited as follows:

Sadatsugu MUTO, Shigeru MORITA, Shin KUBO, Hiroe IGAMI, Yasuo YOSHIMURA, Hiromi TAKAHASHI, Takashi SHIMOZUMA and LHD Experimental Group, Plasma Fusion Res. 5, S1039 (2010).