Abstract
Kinetic studies of the electrons in spatially inhomogeneous, bounded plasmas have been performed by means of two different numerical techniques: the solution of the space-dependent electron Boltzmann equation (BE) using a multiterm approximation of the Legendre polynomial expansion of the electron velocity distribution function and Monte Carlo (MC) simulations. Appropriate conditions at the boundaries of gas discharge plasmas have been deduced, which are adequate for the direct comparison of electron BE and MC simulation results. In particular, extended boundary conditions at the electron emitting cathode are represented and discussed. The investigations are performed for dc discharges in oxygen at conditions typical of abnormal glow discharges. The analysis of the results shows extreme alterations of the properties of the electrons in the discharge region, where pronounced groups of electrons are found, which are generated by electron impact dissociation processes and ionization processes when assuming equal energy sharing in ionizing collisions and isotropic scattering in inelastic electron collisions. The influence of these assumptions on the results obtained is discussed. The very good agreement between the results of the BE and MC calculations verifies the consistence of the derived extended boundary conditions at the cathode and of both the kinetic approaches.
Published Version
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