Comparison of Simulation Methods of Ion-Atomic Collisions in PIC-MC

Abstract

The main ion-atomic collision treatment methods based on Monte-Carlo simulation are consid-ered and discussed. We have proposed an efficient scheme for simulation of time between colli-sions taking into account cross-section dependence on ion velocity and random generation of ion velocities and scattering angles after collisions. The developed algorithm of simulation of interval between collisions takes into account the change of relative velocity of ion-atom pair as well as the change of cross-section of collision and atomic concentration. At the same time, unlike the widely used " null-collision " method, both the probability of collision and change of particles' state which determines this probability are taken into consideration for each particle independently in time. The simulation results according to the techniques proposed are found to be close to the theoreti-cal values of ion drift velocities. It is revealed that the " null-collision " method results in exceeding of drift velocity in strong and intermediate fields. At the same time the proposed method of accu-mulation of probability under the same conditions gives values close to theoretical ones. In weak fields calculated values of drift velocity in both methods exceed theoretical values to some small extent.