Spatio-temporal characteristics of microhollow cathode sustained discharge

Abstract

Micro hollow cathode sustained discharge (MCSD) is simulated by using a fluid model, and the spatiotemoral characteristics of the electric potential, electron density, ion density and electric field are investigated. Results show that the MCSD acts in different modes at different times. The first stage is the Townsend discharge mode. The second is a transition mode from Townsend discharge mode to a hollow cathode effect mode, and the electron density, ion density and electric field near the cathode rise drastically, in which the MCSD is ignited initially. The third stage is the hollow cathode effect mode, and the MCSD forms generally. The last stage is stable discharge state. At the stable discharge stage, the electron density and the ion density each achieve 1015 cm-3 with a peak density located in the center of hollow cathode chamber. The value of electron density in the MCSD region is on the order of 1013 cm -3. The results also show that the micro-hollow cathode discharge (MHCD) contributes to the formation of MCSD, and the MCSD also facilitates the development of MHCD. In addition, the voltage on the second anode has important influence on the distributions of electric potential, electron density and electric field both inside the hollow cathode and outside the hollow cathode. Moreover, the influence on the MCSD is more apparent than the influence on the MHCD. With the increase of voltage on the second anode, the cathode sheath close to the first anode becomes more and more apparent. The second anode is necessary for the formation of micro-hollow cathode sustained discharge.