Plasma particle-in-cell simulations with QED reactions for pair production experiments using a high-Z solid target

A new simulation scheme has been developed to investigate high-energy plasma phenomena including pair production and Bremsstrahlung in a high-Z nuclear field. The simulation scheme consists of (1) a Particle-in-Cell scheme for relativistic plasma dynamics, (2) a conservative semi-Lagrangian scheme for hard photon transport and (3) a Monte-Carlo scheme for the considered QED reactions. The developed scheme is applied to a test simulation relevant to recent experiments of positron production from a thin gold target irradiated by a high intensity laser. The simulation results successfully show a basic process leading to the positron ejection from the target. The process involves electron acceleration due to laser-plasma interaction at the target front, hard photon emission and pair production inside the target, and electrostatic positron acceleration at the target rear side.