Alumina samples with different surface polishing (unpolished, 9 micrometers diamond-finished, and 9 micrometers SiC-finished samples) were used in our studies in vacuum, under pulse excitation, to understand the influence of surface preparation on the surface predischarge associated with microplasmas. The unpolished sample exhibited very active predischarge events, consisting of active localized plasmas on the surface, with associated large predischarge current and high intensity of luminosity, and low electrical breakdown strength. Compared to the SiC-finished sample, the diamond-finished sample showed more active predischarge events and lower conditioned and hold-off voltages. There seems to be a correlation between the predischarge activity and the surface preparation. Our experimental studies indicate that the phenomena of predischarge localized plasmas are related to the physical state of the dielectric surface.

Date Published: 1 May 1994
PDF: 4 pages
Proc. SPIE 2259, XVI International Symposium on Discharges and Electrical Insulation in Vacuum, (1 May 1994); doi: 10.1117/12.174673

Published in SPIE Proceedings Vol. 2259:
XVI International Symposium on Discharges and Electrical Insulation in Vacuum
Gennady A. Mesyats, Editor(s)