Pressure effect on a tandem hollow cathode discharge in argon.

The tandem hollow cathode discharge, formulated by arranging two discharges in series, is an important method used to increase the irradiance of a hollow cathode discharge. In this paper, based on a two-dimensional fluid model we studied a five-layer tandem hollow cathode discharge, with three hollow electrodes stacked together and separated by the insulators to obtain the configuration of anode/insulator/cathode/insulator/anode from the top to the bottom. In the model, the thickness of both electrodes and insulators is set at 1 cm and the diameter of the hollow cavity is 2 cm. The pressure effect on the discharge properties is investigated with gas pressure ranges from 100 Pa to 5 kPa. The gap voltage first decreases, reaching a minimum sustaining voltage at 1 kPa, and then increases. Based on the two-dimensional electron density distributions, the discharges parameters (including the electron density, ion density, electric potential, and electric field) of one integrated hollow cathode discharge at 1 kPa and two relatively independent discharges at 100 Pa and 4 kPa are presented, respectively. The results indicate that the paralleled hollow cathode discharges can be manipulated into one integrated discharge with a higher plasma density by the monotonous control of gas pressure. [ABSTRACT FROM AUTHOR]