A plasma wave and electron-plasma diffusion interpretation of Thomson scattering from a plasma containing negative ions

The properties of electron diffusion and ion-acoustic wave propagation in a plasma composed of negative ions, positive ions and electrons are investigated. Both the ion-acoustic wave phase velocity and the effective electron diffusion coefficient are found to be functions of λ_, the ratio of negative ion to electron number density. In particular the phase velocity is found to be proportional to (1 + λ_) ^{1 2} while the effective electron diffusion coefficient is found to be proportional to (1 + λ_). These results are then applied to obtain a qualitative description of Thomson scattering from the three species plasma.