On the formation of the EDF in the inelastic energy region in the ionization waves

Abstract

Low pressure gas discharges in the inert gases frequently exist in striated mode. The occurrence of the striations at low pressures and small currents is a consequence of the resonant formation of the energy distribution function of electrons (EDF) in spatially periodic electric fields. At these conditions the energy relaxation length in elastic energy region is much bigger than the striation length and the relaxation length in the inelastic region is much smaller than that. This difference in the relaxation lengths in elastic and inelastic energy regions causes the different ways of the EDF formation in those regions. Before the excitation threshold the EDF is formed non-locally, what is connected with the big value of the energy relaxation length, while after the excitation threshold the small value of the relaxation length makes the EDF to form under the influence of the local value of the electric field with additional phase shift. It is shown in the presented paper, that in the limiting case of small values of relaxation length in the inelastic energy region the solution of the Boltzman equation can be obtained by sewing the non-local solution in the elastic energy region with the local solution in the inelastic region and also the appropriate phase shift can be determined.