Spectroscopic investigation of micro-hollow cathode discharge

Abstract

Summary form only given, as follows. Micro-hollow cathode discharge has interesting properties such as non-Maxwellian energy distribution function, high current density, and feasibility in generating high-pressure non-equilibrium plasmas without glow-to-arc transition. Many applications such as thin film deposition, detoxification of gaseous pollution, electron source and surface modification have been recently studied. Micro-hollow cathode, 0.8mm in diameter drilled in brass plate of 4mm thickness in argon (and air) glow discharge is investigated experimentally. The relations between breakdown voltage of hollow cathode glow discharge and gas pressure in argon and air are measured. Minimum of breakdown voltages obtained, are about 400V for argon 20Torr and 410V for air 2Torr. With appearance of hollow cathode effect, the current voltage characteristics have shown abrupt increase of discharge current, strong optical emission from the hollow cathode is also observed, and constant discharge voltage of 300V up to 100mA in air pressure higher than a few Torr is attained. Measurement of electron temperature and gas temperature is carried out by optical emission spectroscopy. Using hydrogen line intensity ratio method for electron temperature and intensity distribution of nitrogen first negative rotational band for gas temperature, following results are obtained. The electron temperatures axe about a few electron volts at 1OTorr argon and discharge current up to 100mA, and they decreases with increase of discharge current. Rotational temperatures are about 0.035eV up to 123mA in 12Torr air and showed no current dependence.