High-energy radiation and pair production by Coulomb processes in particle-in-cell simulations

Abstract

We present a Monte Carlo implementation of Bremsstrahlung, Bethe-Heitler, and Coulomb Trident processes into the particle-in-cell (PIC) simulation framework. In order to address photon emission and electron-positron pair productions in a wide range of physical conditions, we derive the Bremsstrahlung and Bethe-Heitler cross sections taking account of screening effects in arbitrary ionized plasmas. Our calculations are based on a simple model for the atomic Coulomb potential that describes shielding due to both bound electrons, free electrons, and ions. We then detail a pairwise particle interaction algorithm suited to weighted PIC plasma simulations, for which we perform several validation tests. Finally, we carry out a parametric study of photon and pair production during high-energy electron transport through micrometric solid foils. Compared to the zero-dimensional model of Myatt et al. [Phys. Rev. E 76, 066409 (2009)], our integrated one-dimensional simulations pinpoint the importance of the electron energy losses resulting from the plasma expansion.