Effect of Background Gas Pressure on Macroparticles in Cathodic Arc Plasma Deposition

The 1-D stationary fluid model combined with orbital motion limited theory is presented to describe the charging of macroparticle (MP) in a cathodic vacuum arcs operating in a reactive gas. The effect of the background gas pressure on MPs is analyzed from the viewpoint of MP dynamics. The main forces acting on an MP as well as the charging of MP in the interelectrode region of the discharge are studied. The ion drag force decreases with the gas pressure, while the neutral drag force increases. MP potential is calculated taking account the dependence of the plasma parameters on the background gas pressure. The electrostatic reflection of MP increases with the background pressure as a consequence of the increased negative potential of MP. As a result, MP can be confined in the plasma due to the force balance.