Dielectric surface flashover in vacuum at 100 K

A. Neuber, M. Butcher, L. L. Hatfield, M. Kristiansen, H. Krompholz

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Cryogenic components in high power electrical systems and in power electronics gain more and more importance. The behavior of insulators for cryogenic conditions, however, is virtually unknown. In a fast coaxial setup, dielectric test sample and electrodes in vacuum are cooled to <100 K and flashover is characterized using fast electrical and optical diagnostics. Three consecutive development stages for flashover in self-breakdown mode with a gap distance of 0.5 cm can be distinguished: (1) A fast current rise to mA amplitudes within approximately 2 ns, probably associated with field emission, followed by (2) a slow current rise to approximately 5 to 10 A amplitude with duration of 40 ns to 1 μs, associated with secondary emission avalanche saturation, and (3) a transition to a rapid gaseous ionization above the sample caused by electron induced outgassing, leading to impedance-limited current amplitudes of ≤300 A. Phase (1) shows a higher final current at lower temperature, which is probably due to a higher initial velocity of the secondary electrons, the duration of phase (2) is a decreasing function of breakdown voltage and only slightly dependent on temperature, which points to a weak temperature dependence of the outgassing process. Flashover potentials show a slight increase at lower temperature.

Original languageEnglish
Pages (from-to)512-515
Number of pages4
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Volume6
Issue number4
DOIs
StatePublished - 1999

Fingerprint Dive into the research topics of 'Dielectric surface flashover in vacuum at 100 K'. Together they form a unique fingerprint.

  • Cite this