Plasma and Fusion Research

Volume 15, 2401025 (2020)

Regular Articles

Discrimination of Partial Discharges in Gaseous and Liquid Nitrogen by Using Waveform Characteristics
Kazuki YAMADA, Tomohiro KAWASHIMA, Tetsuhiro OBANA1), Yoshinobu MURAKAMI, Masayuki NAGAO and Naohiro HOZUMI
Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Aichi 441-8580, Japan
Device Engineering and Advanced Physics Research Division, National Institute for Fusion Science, Gifu 509-5292, Japan
(Received 29 November 2019 / Accepted 13 March 2020 / Published 11 May 2020)


The cryogenic coolant is important as an electrical insulation in an immersion cooling. One of the dielectric breakdown mechanisms of the cryogenic coolant is via bubbles, caused by partial discharge (PD). The insulation performance has been discussed with PD parameters and breakdown voltage. However, the essential PD mechanism has not been clarified in detail. In this paper, PDs in gaseous and liquid nitrogen were discriminated based on characteristics of the original PD waveform. It was shown that the difference in charge behavior appears significantly in the fall time of the original PD waveform.


electrical insulation, partial discharge, waveform characteristics, liquid nitrogen, gaseous nitrogen

DOI: 10.1585/pfr.15.2401025


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