Effect of Duty Ratio on Glow Discharge Current of Hollow Cathode in Slender Tube at Low Pressure

In order to obtain the film with good performance and uniform texture on the inner wall of slender tube, hollow cathode glow plasma discharge was carried out by using slender tube as vacuum cathode under low pressure. By studying the real-time measurement of average current and current peak under various atmospheres(pure Ar, pure N₂, nitrogen and argon), the discharge current of plasma under different pulse duty cycle conditions was compared, and the influence of changing duty cycle under multiple atmospheres was discussed and analyzed.The experimental results show that the pulse current waveform changes significantly with the change of duty cycle when using a pulse power source with a frequency of 40 kHz. The waveforms of different atmospheres are different,but both the peak values and the average current increase. The pure Ar atmosphere increases from 20% duty cycle to 70% duty cycle, and the peak current increases from 0.325 A to 0.5 A, and the average current increases from 0.12 A to 0.28 A. It is found that the overall current uniformity of pure Ar and mixing atmosphere is better than that of pure N₂. Ar is in the range of 30%~60% duty cycle, and the parameter k30% ~60% is 0.12.