Spectroscopic and electric probe measurements of plasma parameters in the negative glow region of helium discharge plasma

Abstract

The essential plasma parameters, i.e., electron temperature, T e electron density, n e and ion temperature, T i, have been measured in the negative glow (NG) region of a helium cold-cathode discharge plasma as a function of the filler gas pressure. For the determination of these parameters two different techniques have been used throughout this work. Spectroscopic technique depending on the line intensity ratio of He(I) resonance line at 3888.65 Å and He(II) ionized line at 4686 Å, besides the width and profile of the working heluim gas, is the first one, while electrical single probe technique depending on the voltage–current characteristics of the plasma is the second one. By this second technique the experimental data of the floating potential, V f, and the plasma potential, V s, were used to define the negative glow region. Comparison between the results of both techniques revealed a strong agreement of the measured values of T e, besides a fairly good agreement of the measured values of n e.