Vacuum surface flashover: A high-pressure phenomenon
Desorbed gases from insulator surfaces may be much more important in flashover initiation than properties of the dielectric surface. Ambient neutral densities, immediately above the insulator surface, in the initial stages of flashover have been calculated to lie in the range from 2 x 10/sup 17//cm/sup 3/ to 2 x 10/sup 21//cm/sup 3/ with a mean of about 1 x 10/sup 19//cm/sup 3/, whether flashover occurred on surfaces in air at atmospheric pressure or in vacuum as low as 10/sup -6/ Torr. The evidence presented indicates that, for dc and microsecond pulse voltages, surface flashover is a local, relatively high-pressure phenomenon. Comparison of field strengths of surface flashover for various insulating materials perpendicular to the electrodes, operating pressures, and voltage waveforms appears to indicate that flashover values range well within an order of magnitude (approx.18--80kV/cm). A filamentary nature of the flashover discharge is shown and is consistent with gas breakdown phenomena. Ionization wave front velocities are examined and these compare favorably with those obtained from gaseous breakdown studies.
- Research Organization:
- Sandia National Laboratories, Albuquerque, New Mexico, 87185
- OSTI ID:
- 5788354
- Journal Information:
- J. Appl. Phys.; (United States), Vol. 58:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLASS
FLASHOVER
BREAKDOWN
COPPER
DESORPTION
ELECTRICAL INSULATORS
ELECTRODES
IONIZATION
SORPTIVE PROPERTIES
SURFACES
TOWNSEND DISCHARGE
CURRENTS
ELECTRIC CURRENTS
ELECTRIC DISCHARGES
ELECTRICAL EQUIPMENT
ELEMENTS
EQUIPMENT
METALS
SURFACE PROPERTIES
TRANSITION ELEMENTS
360603* - Materials- Properties