Sputtered atom transport in high-current gas discharges: A self-consistent computer simulation study

It is experimentally known that particles sputtered from the cathode of high-current gas discharges heat the discharge locally in front of the cathode, reduce its density there, and induce a ‘‘sputter wind’’ in the discharge gas. As a consequence, sputtered particles are stopped less strongly in a high-current discharge, as compared to a low-current discharge. We study the coupled system of sputter current and discharge gas, using a direct simulation Monte Carlo algorithm adoped from gas kinetics, which simulates the Boltzmann equation underlying these transport processes. A cylindrical model system is studied. The effects of density reduction and discharge heating in front of the cathode and a convection wind are clearly observed. By comparing the sputtered particle flow in this simulation with that of a reference simulation in which the discharge gas is kept in its initial condition, the effects of the coupling between sputtered currents and discharge are brought out most clearly. Comparison of the gas density reduction in front of the cathode with experimental data is favorable.