The Gas-Heating Phase in Electrical Breakdown
Abstract
This report focuses attention on the neglected gas-heating stage associated with a spark. A brief review is followed by summaries of recent experimental and theoretical investigations. It is shown that in all cases gas heating is preceded by the formation of a weakly ionized plasma. The transformation to a strongly ionized gas requires additional ionization that can be associated with several different physical processes. In small gaps (3.0 mm) with metal electrodes, the influx of electrons from a cathode spot with at least a single cell is responsible for gas heating. In longer gaps (1 to 3 cm) highly luminous ionization waves are produced. These can be reflected at the electrodes and increase the degree of ionization. They are well known but not clearly explained in longer discharges. This stage is followed by the formation of hot filaments either at the electrodes or in mid gap. These seem to be associated with the onset of effective ion-electron interactions. In large surface discharges (approx. 1.0 m) the glow and hot channel behind it constitute a stable propagating unit that seems to be controlled by three body electron-ion recombination. The properties of these gliding discharges are similar to those of lightning leaders. In all cases there is strong evidence to support the concept of fluid dynamic effects associated with the hot electron population in the weakly ionized gas. Thus the propagation of stable discontinuities, either strong (shocks) or weak, is shown to be possible.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1983
- Accession Number
- ADA141961
Entities
People
- Ernesto Barreto
Organizations
- State University of New York at Albany