Zur Ausbreitung von Ionenschall‐Instabilitäten in schwach ionisierten Plasmen unter Berücksichtigung eines Potentialgradienten

A dispersion relation for the ion‐acoustic instability in a dc‐discharge is derived. The dc electric field term in the linearized Vlasov‐equation is not neglected, and the ion drift velocity is taken into account. Collisions of the electrons and ions with the neutrals are considered on the basis of a Davy‐dov‐collision term. The influence of the dc field and the ion drift leads to higher values of the spatial growth rates in the low frequency range and a shift of the maximum of the growth rates and the high frequency boundary of the unstable waves toward lower frequencies. The phase velocity diminishes, what is, above all, a result of the consideration of the ion drift velocity.