Electron impact ionization and dielectric breakdown in liquid Xe and Ar

Resolving the question of whether electron avalanches can occur in liquids is of fundamental importance when formulating models for electrical breakdown in liquids. It is of interest to study this phenomena in liq. Xe because: (a) there are practical applications involving high field electron transport in liq. Xe, (b) electron transport can be easily modeled in a simple liquid such as Xe, and (c) electron avalanches have been experimentally observed in liq. Xe, and so comparisons can be made. The electron energy distribution function, drift velocity, and ionization rate for electrons in liq. Xe have been calculated using a kinetic model for electron transport. The electron scattering rates have been obtained using the Van Hove approach in which the liquid is characterized by the dynamic structure function, S(q&oarr;,ω). The threshold field for ionization, E_t (such that the ionization coefficient, α≠0 for E>E_t ) is found to be ≈400 kV/cm. This value for E_t as well as those for α are in good agreement with experiment. In particular the minimum at high fields in the experimental α vs E curve is also present in the calculated results. These results serve to elucidate the kinetics of electron avalanches in liquids, and are used (with the results of Ref. [1]) to assess the “electronic” model of breakdown in liq. Xe and Ar