Efficient electron heating in short-pulsed magnetron discharges

Abstract

The effect of the duty cycle of the cathode pulse on the electron energy distribution function and the plasma parameters was investigated by means of the time-resolved probe measurements in the pulsed and unbalanced magnetron discharges. The discharges were driven by the cathode pulse with the repetition frequency of 20 kHz in three regulation modes of constant voltage, constant current, and constant power. As the duty cycle was reduced, the electron temperature averaged during the pulse-on period rapidly increased irrespective of the regulation mode. The comparison of the measured electron energy distribution functions shows that the increase of the electron temperature is caused by the decrease of the population of trapped low-energy electrons and the increase of the population of drifting high-energy electrons. It will be shown that these results can be explained from efficient electron heating by the high-voltage cathode sheath more deeply penetrating into the bulk with the reduction of the duty cycle during the pulse-on period.