Method of simplified kinetic equation for simulating the electron kinetics in dense gases in strong electric fields

A method for calculating the electron kinetics in dense gases in strong electric fields is developed. The method differs from the forward-backward approximation proposed by Ra?zer and Shne?der for “high-energy” electrons in that it introduces the effective cosines of the scattering angles with respect to the electric force, μ⁺(?, E) and μ^?(?, E), which are different from +1 and ?1, as in the forward-backward approximation. The method was implemented numerically for atmospheric-pressure helium and molecular nitrogen for fields in the ranges 10–200 and 50–800 kV/cm, respectively. The cosines μ⁺(?, E) and μ^?(?, E), the frequency of “fatal” collisions making high-energy electrons to pass from an acceleration regime to a deceleration one, and the rate at which the electrons leave the low-energy reservoir with energies of ≤15 eV for nitrogen and of ≤20 eV for helium are calculated.