Dielectric surface flashover in vacuum at cryogenic temperature (100 K)

A. Neuber, H. Krompholz, L. L. Hatfield

Research output: Contribution to journalConference article

7 Scopus citations

Abstract

Recent developments in high power systems use cryogenic components, where the performance of insulators at such low temperatures is unknown. In a fast coaxial setup, electrodes and dielectric sample are cooled to less than 100 K in vacuum, and the flashover initiation processes for gap distances on the order of 1 cm are characterized using fast electrical and optical diagnostics. As reported before, two development stages can be distinguished: a first phase with slowly rising current and the presence of free electrons, with a duration of 10-50 ns, and a second stage with a fast current rise due to gaseous ionization and collision dominated electrons. First experiments comparing cooled samples and samples at room temperature do not show discernible differences for Lexan. For Alumina, however, an increase of the duration of phase 1 is observed, with a higher current amplitude at the transition from phase one to phase two. Also, the current rise in phase two is reduced. These results indicate a temperature dependence of the electron induced outgassing process which is expected to cause the transition from phase one to phase two.

Original languageEnglish
Pages (from-to)575-578
Number of pages4
JournalConference on Electrical Insulation and Dielectric Phenomena (CEIDP), Annual Report
Volume2
StatePublished - 1997
EventProceedings of the 1997 Annual Conference on Electrical Insulation and Dielectric Phenomena. Part 2 (of 2) - Minneapolis, MN, USA
Duration: Oct 19 1997Oct 22 1997

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