Revisiting particle dynamics in HiPIMS discharges. II. Plasma pulse effects

A detailed experimental study of high power impulse magnetron sputtering discharges is performed using time-resolved ground state density mapping of the sputtered neutrals and ions. This Paper deals with the effects related to the plasma-on phase and can be considered as an extension of Paper I being published simultaneously. The influence of plasma pulse duration, pulse energy, gas pressure as well as molecular oxygen admixture on the spatial and temporal particle density evolution is examined. Special attention is given to the temporal evolution of the ionization fraction distribution of the sputtered atoms. In addition, the 2D vector maps reflecting particle propagation, sputtering, and ionization in the discharge volume are also presented and discussed, similarly to the first part of this study [J. Appl. Phys. 128, 043303 (2020)].