Monte Carlo method for investigating population kinetics in non-local thermodynamic equilibrium plasmas

Abstract

Abstract We propose a new method to solve the collisional-radiative (CR) model with the Monte Carlo method for investigating population kinetics of non-local thermodynamic equilibrium plasmas. The CR model is solved using massive sample particles accounting detailed energy levels. Whether an atom/ion undergoes an ionization/excitation/decay process is determined by probabilities calculated from ionization cross-sections, excitation and decay rates. By continuously iterating this process for massive atoms/ions, the ionization population distribution is obtained. The numerical convergence can be achieved for a mid-Z element using 103 particles in the Monte Carlo simulation. The results of the Monte Carlo simulations are compared with other methods and experimental results. The self emission spectra of silicon plasma is obtained and the ionization population distribution of silicon and iron plasmas are calculated. The proposed method can be used to interpret high energy density experiments and astrophysical phenomena where non-local thermodynamic equilibrium effects play vital roles.