Plasma Conductivity Estimation in Inductively Coupled Electrodeless Discharge by Equivalent Circuit

Abstract

An equivalent distributed constant circuit model for inductively-coupled electrodeless discharge, having a double tube structure, is introduced. The distribution profile of plasma conductivity in the tube is calculated by means of the diffusion equation for electron density. The obtained profile shows good agreement with the measured profile of the excited mercury atom density. Then, plasma conductivity as a function of the induced discharge current is estimated by comparing the experimental results with the results calculated using the model. The estimated maximum plasma conductivity, σmax , is independent of operating frequency and is approximated by the following expression for the employed discharge tube: σmax =0.007814iD2+0.4836iD, where iD is induced discharge current in A(rms)/m.