J. Phys. Colloques
Volume 40, Numéro C7, Juillet 1979XIVe Conférence Internationale sur les Phénomènes d'Ionisation dans les Gaz / XIVth International Conference on Phenomena in Ionized Gases
|Page(s)||C7-301 - C7-302|
J. Phys. Colloques 40 (1979) C7-301-C7-302
A SUBSONIC ELECTRON FLUID AND THE FORMATION OF SMALL SPARKSE. Barreto et H. Jurenka
Atmospheric Sciences Research Center, State University of New York at Albany, Albany, New York 12222.
In a small high pressure discharge gap, avalanches and streamers start ionization but do not produce gas heating or a conducting bright filamentary channel. The electron density is not high enough to promote the ion-electron interaction that leads to rapid neutral gas heating. Nevertheless, long after initial ionization has subsided in a gap, a very rapid transient stage is produced. This constitutes the spark proper and changes a weakly ionized cold gas into a hot, highly conducting luminous fluid. The spark stage may incorporate very rapidly moving luminous fronts, and depending on the power supply, may lead to a much cooler are discharge. It has been suggested many times that the spark transition can be associated with electron fluid behavior : For instance, using 2 mm long gaps we have shown that the initial ionization produces a long-lived high temperature, non-equipartition electron fluid, and that the propagation of fast luminous fronts can be associated with non-linear electron waves.1 Here we present evidence to show that, under appropriate conditions, subsonic electron fluid behavior can also be exhibited. It is schown that heating of the gas can be accomplished by electrons that be-have as a fluid and undergo subsonic turbulent mixing. From a practical point of view, the study is pertinent to problems in lightning, explosion and ignition of combustible gas mixtures, vacuum discharges and electrode erosion problems.