Insulator surface charging during fast pulsed surface flashover in vacuum

Conference · Sat Jan 01 00:00:00 EST 1977

OSTI ID:7212950

Anderson, R. A.; Brainard, J. P.

The fact that charges accumulate on the surface of an electrically stressed insulator in vacuum is well established, but the rate of charging is not, and the role of this charge in surface flashover is controversial. Previous investigations support the hypothesis that charging proceeds very rapidly by means of an avalanche of electrons released from the insulator surface by secondary emission and that the avalanche is responsible for establishing the discharge channel in cathode-initiated surface flashover. In the experiments, insulators were subjected in vacuum (10/sup -3/ to 10/sup -4/ Pa pressure) to high-voltage steps having 3 ns risetime. Measurements of the current of electrons arriving at the anode electrode at the edge of a 20 mm long, rectangular insulator verified that a secondary electron emission avalanche occurs on the insulator surface prior to breakdown, even for voltage pulses lasting only a few nanoseconds. In addition, the critical electric field angle associated with the equilibrium surface charge was determined under fast pulsed conditions, and found to agree well with the dc measurements of Boersch, et al. (LCL)

• Research Organization: Sandia Labs., Albuquerque, N.Mex. (USA)
• DOE Contract Number: EY-76-C-04-0789
• OSTI ID: 7212950
• Report Number(s): SAND-77-0799C; CONF-771028-2
• Resource Relation: Conference: Conference on electrical insulation and dielectric phenomena, Schenectady, New York, USA, 17 Oct 1977
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
ELECTRICAL INSULATORS
FLASHOVER
BREAKDOWN
ELECTRIC CHARGES
ELECTRON EMISSION
MEASURING METHODS
SURFACES
VACUUM SYSTEMS
CURRENTS
ELECTRIC CURRENTS
ELECTRIC DISCHARGES
ELECTRICAL EQUIPMENT
EMISSION
EQUIPMENT
200300* - Electric Power Engineering- Power Transmission & Distribution- (-1989)