Measurement of Plasma Temperature and Electron Density

Abstract

This investigation aims at measuring the temperature of the plasma obtained by passing condensed discharge through a Geisler tube containing neon. The wave-length of Ne I λ5852 emitted from condensed discharge was compared with that of the same line emitted from arc discharge, the comparison being made with a Fabry-Perot etalon. Red shift of the line by spark discharge was detected. From the amount of the shift the half-value width contributed by the ionic field and electrons was calculated by Lindholm’s formula. Subtracting this (vectorially) from the observed half-value width, the width contributed by the Doppler effect alone was obtained, and then the plasma temperature was calculated. From the line profiles of Hγ and Ne I λ4715 Holtsmark’s so-called normal field strength F_n was obtained, and therefore the electron density could be deduced. In our present example the mean plasma temperature was T=6×10³ K, and the mean electron density N=1×10¹⁰ per cm³.