Operational and Spectral Characteristics of a Sr–Ne Glow Discharge Plasma

Abstract

We have used emission spectroscopy to determine the plasma parameters of strontium in a glow discharge lamp. The excitation temperature is determined from the Boltzmann’s plot method, and the electron density is measured from the Stark broadening of the observed spectral lines. Sr I line at 640.846 nm corresponding to $4d5p~ ^{3}{\mathbf{F}^{0}}_{4}\rightarrow 5{s}4{d}~ ^{3}{} \mathbf{D}_{3}$ transition has been used for the determination of electron number density. Further, the electron number densities in the plasma are determined at different discharge currents. Spectral emission intensities of some selected lines display Frank–Hertz-type dips at two different discharge currents. The possible role of near-resonant collisions between long-lived metastable levels of Ne and Sr atoms in creating ionization of Sr II is highlighted. The competing collisional ionization and radiative decay of the levels such as ${4p}^{6}{7p}$ in Sr II and doubly excited 4d5p levels of Sr I is considered significant in this case. Our observations show that the electron number density changes linearly with the electric field for low-discharge currents.