A General Analytic Electron-Impact Ionization Electron Energy Sharing Model for Monte Carlo Plasma Modeling*

Modeling non-equilibrium plasmas with Monte Carlo collision codes or Boltzmann equation solvers requires input of collision cross sections and/or scattering models. Recently, we have developed a general analytic scattering model for calculating the electron-impact ionization electron energy sharing distribution function (EESDF), which can be readily implemented into Monte Carlo simulation codes. The EESDF is shown to be accurate for a variety of target neutral/ion/excited species and impact energies. We present a closed-form inversion formula for the model and compare the approach to scattering models generally utilized by collisional Monte Carlo codes, e.g. the commonly used model of C. B. Opal et al J. Chem. Phys. 55, 5100 (1971), the equal energy sharing approximation, and the "one-takes-all" sharing model. We note that, unlike the commonly used approach of Opal, the present analytic model is applicable to all species, requires minimal input data from the user, and does not rely on experimentally determined parameters.