Punchthrough of ceramic insulators

Author

Shea, John J.

Author_Institution

Westinghous Sci. & Technol. Center, Pittsburgh, PA, USA

fYear

1990

fDate

28-31 Oct 1990

Firstpage

441

Lastpage

450

Abstract

A study of punchthrough breakdown in an alumina insulator is presented. The alumina cylinder, containing electrodes at 300 kV in a vacuum of 10^-6 torr, experienced permanent puncture damage from a breakdown process that was unexpected because the fields from the electrodes were well below the breakdown strength of the ceramic. Punchthrough was concluded to be caused by a combination of electric field stress in the ceramic and embedded electrons which formed a volume charge within the ceramic. Calculations were made to determine the minimum electron density necessary to exceed the breakdown strength of the ceramic while in the electric field. The electric fields in the ceramic were determined from computer field mappings of the equipotential contours in the cylinder. The calculated minimum electron charge density, under zero electrode generated field, was 138×10 ^l5 e^-/cm³. Color center reactions confirmed that electrons bombarded the ceramic

Keywords

alumina; ceramics; electric breakdown of solids; electric fields; insulating materials; insulators; 1×10^-6 torr; 300 kV; Al₂O₃; alumina cylinder; breakdown strength; ceramic insulators; colour centre reactions; computer field mappings; electric field stress; electrodes; embedded electrons; equipotential contours; punchthrough breakdown; volume charge; Ceramics; Copper; Electric breakdown; Electrodes; Electron tubes; Embedded computing; Insulation; Stress; Surface charging; Vacuum breakdown;

fLanguage

English

Publisher

ieee

Conference_Titel

Electrical Insulation and Dielectric Phenomena, 1990. Annual Report., Conference on

Conference_Location

Pocono Manor, PA

Type

conf

DOI

10.1109/CEIDP.1990.201380

Filename

201380