Plasma and Fusion Research

Volume 16, 1202061 (2021)

Rapid Communications

Observation of Arc Trails with Significant Damage due to Glow Discharge Wall Conditioning in the Large Helical Device
Yuki HAYASHI1), Suguru MASUZAKI1), Gen MOTOJIMA1,2), Dogyun HWANGBO3), Yutaka FUJIWARA1), Mingzhong ZHAO1) and the LHD Experiment Group1)
1)
National Institute for Fusion Science, National Institutes of National Sciences, Toki 509-5292, Japan
2)
The Graduate University for Advanced Studies, SOKENDAI, Toki 509-5292, Japan
3)
Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
(Received 2 December 2020 / Accepted 1 March 2021 / Published 21 April 2021)

Abstract

We report the observation of arcing damage on the diagnostic shutter during the glow discharge wall conditioning in LHD. The diagnostic system has no experience of plasma discharge produced by electron or ion cyclotron resonance heating or neutral beam injection. The arc trails were observed on the aluminum surface but not on the stainless steel although both materials were exposed to the glow discharge with the same duration. The difference in work functions between two materials may be a cause to divide the conditions of arcing ignition.

Keywords

glow discharge conditioning, arcing, LHD

DOI: 10.1585/pfr.16.1202061

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