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 solver codes 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, which can be readily implemented in Monte Carlo simulation codes. Here we present our approach and show the utility and accuracy of the model for a wide range of impact energies, species, ions, and species excited states. We compare this approach to scattering models generally utilized by Boltzmann equation solver and collisional Monte Carlo codes, e.g. the commonly used model of C. B. Opal et al. J. Chem. Phys. 55, 4100 (1971), the equal-energy sharing approximation, and approximating the primary electron to take all of the excess energy. 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.