Numerical study of the power deposition in low-pressure hollow cathode arc discharges

Abstract

Erosion is always the major factor for shortening the working lifetime of discharge devices with hollow cathode. In this paper, we employ a 2D self-consistent fluid model developed primarily in our previous work (Cong et al 2019 J. Phys. D: Appl. Phys. 52 045205) to carry out a systematic study of the properties of the low-pressure hollow cathode arc and its power depositions onto the cathode wall as well as into particles under different discharge conditions. The model considers the electron transport, electron energy transport, gas heating and flow, and cathode thermal balance. In the cathode thermal balance, apart from thermionic emission, ion bombardment, heat conduction, and surface radiation, the Coulomb collision between electrons and ions is additionally considered. The uniform axial applied magnetic field is also included in the present model. The results show that there exists an optimal discharge stage in the wide range of gas flow rate, in which the voltage and power depositions are almost constant. We also find that the contribution of power deposition from particles accounts nearly for half of the total power deposition onto the cathode. The discharge conditions such as gas flow rate, discharge current, and axial magnetic field can all change the pattern and area of the arc wetting the cathode wall, and therefore influence the properties or power depositions of the hollow cathode arc plasma.