Observations of low-frequency mode in a multicomponent plasma with negative ions

Abstract

Based on linear perturbation theory, a dispersion relation for low-frequency (LF) electrostatic waves has been derived in a multicomponent plasma containing negative ions. To relate the theoretical observations with experiments on the LF wave, the slower mode has been studied extensively for various plasma models. The experiment was carried out in Ar, F, and electron plasma in a double plasma device. The experimental observations on LF electrostatic waves yield the qualitative frequency variations due to the presence of negative ions. In the region of lower negative ion concentration, the mode decreases with the addition of a higher percentage of negative ion concentration while later, in the higher region of negative ion concentration, the variation shows the asymptotic behavior with negative ion concentration. Both the observations, theoretical and experimental, have shown a good agreement with each other. Moreover, a theoretical model of plasma with heavy negative ions has also been presented.