Observation of Space and Energy Distributions of High Energy Electrons Produced in ECH Plasmas of LHD

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...

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Bibliographic Details
Published in:Plasma and Fusion Research 2010/03/26, Vol.5, pp.S1039-S1039
Main Authors: MUTO, Sadatsugu, MORITA, Shigeru, KUBO, Shin, IGAMI, Hiroe, YOSHIMURA, Yasuo, TAKAHASHI, Hiromi, SHIMOZUMA, Takashi, Group, LHD Experimental
Format: Article
Language:English
Subjects:
hard x-ray emission
Large Helical Device
pulse height analyzer
suprathermal electron
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Summary: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.
ISSN:1880-6821
1880-6821
DOI:10.1585/pfr.5.S1039