A Study of Plasma Parameters in Hollow Cathode Plasma Jet in Pulse Regime

摘要

The pulsed DC hollow cathode discharge has been studied in the low pressure plasma jet sputtering system by means of cylindrical Langmuir probe. Measurements have been performed in pure Ar with the flow rate of 30 sccm. The repetition frequency of the pulses of 1 kHz has been chosen with the pulse width 100 us (duty cycle 10%) and 50 mu s (duty cycle 5 %) and the amplitude of the pulses was approximately 400 V. The average discharge current varied between 150 and 250 mA. To obtain better stability of the discharge a 3.8 k Omega resistor was connected across the pulse switch. Consequently, there was a weak continuous DC discharge on the background of the pulsed discharge. From the probe characteristics the plasma and floating potential, electron density and electron temperature have been evaluated. Their dependences on the pressure (in the range of several Pa) and on the radial distance from the central axis of the system are presented. Temporal resolution of the measurements is 0.5 mu s.