Study of glow discharge parameters in a coaxial electrode system with a thin cathode

Abstract

Various gas discharges are the basis of many electronic, photonic devices and ion-plasma technologies. Among them, the glow discharge is the most common and is often mentioned in the scientific and technical literature. In this study, we model a glow discharge in a cylindrical coaxial system with dielectric electrode ends in the hydrodynamic drift-diffusion approximation. The model parameters are: anode diameter 10 mm, cathode diameter 30 µm, voltage 800 V, temperature of the working argon gas 300 K, pd ≈ 2 Pa∙m (p — working gas pressure, d — distance between electrodes), which corresponds to the right side of the minimum area of the Paschen curve for discharge ignition. The reactions of ionization of atoms by electron impact, generation and quenching of metastable atoms, elastic collision of electrons with atoms and elastic collision of ions, resonant recharge of ions, Penning ionization, and secondary ion-electron emission of the cathode are taken into account. The potential distribution and concentration of charged particles in the interelectrode space are calculated within the framework of a self-consistent problem, and the electron current density, concentration of charged particles, and potential along the cathode are presented. The effect of the ballast resistor Rb of the blocking capacity on the parameters and discharge mode is determined. The obtained results can be used in plasma technologies to modify the internal surfaces of metal, hollow, long parts with a small cross-sectional size.

Keywords

• glow discharge
• diffusion models
• plasma modeling
• coaxial system
• electrode
• thin cathode