On the formation ofelectron velocity distribution functions in striation-like fields

Abstract

Peculiarities of the formation of electron distribution functions in spatially periodicstriation-like fields in a neon dc glow discharge are analysed on the basis of anaccurate solution of the Boltzmann kinetic equation, taking into account elastic andinelastic collisions, as well as spatial gradients. Mean axial electric fields andstriation lengths are measured in a wide range of pressures. The transition from thelocal formation of electron distribution function through the weakly nonlocal case atadvanced pressures to the distinctly nonlocal formation at low pressures is demonstrated.The phase shifts between the electron density and rates of excitation and ionization dueto nonlocal effects and finiteness of the lifetime of excited atoms are illustrated.Comparison between numerical and approximate analytical solutions is performed for thelimiting cases of low and advanced pressures, when the kinetic equation can be solvedanalytically by means of the small parameter expansion.