ON THE BUNCHING EFFECT OF ELECTRONS IN SPATIALLY PERIODIC RESONANCE FIELDS

The spatial relaxation of the electron distribution function (EDF) in uniform and spatially periodic electric fields is considered. The anal ysis is based on the Boltzmann kinetic equation containing spatial gra dients and operators of elastic and inelastic collisions. We demonstra te that the presence of a discrete spectrum of excited states due to t he process of electron back scattering leads to the appearance of a qu asicontinuous flux of energy in the elastic region, similar to the flu x created by means of energy loss in elastic impacts. in the absence o f channels of energy dissipation connected with energy loss in elastic impacts and in the presence of several excited states, information ab out the initial EDF injected in a field of arbitrary configuration, ca n be transmitted over an unlimited distance. The process of the relaxa tion has the nature of undamped oscillations. The introduction of chan nels of energy dissipation results in a damped oscillatory relaxation character of the EDF injected into a uniform field and in the establis hment of a homogeneous EDF in this field. The relaxation of an EDF inj ected into a spatially periodic resonance field results in the distrib ution function having specific maxima which change in energy and coord inates along the resonance paths in accordance with the potential dist ribution (the so-called bunching effect). This effect can be used for the interpretation of EDF formation in S- and P-striations in inert ga s discharges at low pressures and currents.