Analysis of Formation Process of High-Voltage Ultra-Short Pulsed Plasma.

Abstract

The formation process of high-voltage ultra-short pulsed plasma in argon gas has been clarified by computer simulation based on mass conservation equations of electrons and ions coupled with Poisson's equation, including the transport processes of resonance photons which cause photoemission of secondary electrons on the cathode. First, the initial charged particle densities for high-voltage ultra-short pulses were estimated through a simulation of an after-glow period following the end of the former pulse. In this after-glow period, the decay process of plasma is mainly governed by recombinations and a large amount of charged particles, more than 107cm-3, remain even 20ms after the voltage is turned off. Then, the formation process of the plasma structure in the high-voltage ultra-short pulse was analyzed. The residual charged particles generated by the former pulse assist in the formation of the plasma structure in the next pulse. The electron photoemission has a significant effect on the formation process of th plasma structure, especially a very short time after the voltage rise. The lag time of the current rise obtained through this simulation agrees well with our experimental result. The model developed in this study could become a fundamental basis for applying this type of pulsed plasma to the active control of plasma chemical reactions.