Kinetic model of ionization waves in a positive column at intermediate pressures in inert gases

A kinetic model of ionization waves in the inert gas discharge is constructed, which is based on the simultaneous solution of the kinetic equation for electrons and the continuity equations for ions and excited atoms. The model corresponds to a range of intermediate pressures and small currents, when elastic collisions dominate in the electron energy balance and electron-electron collisions are negligibly small. A linear theory of ionization waves is constructed, growth rates and frequencies of wave disturbances able to propagate in plasma are found. It is shown that there is an upper bound to the existence of striations by pressure, as well as the lower bound by current. The self-consistent solution of the source system of equations is obtained, which describes a nonlinear wave. The profile of electric field and the electron distribution function in this field are calculated. The results of calculations are compared with the experimental data. The wavelengths obtained are essentially larger than the electron energy relaxation length. Such waves cannot be described within the limits of fluid models.