Effects of Close Collisions on Ion Oscillations in a Plasma

Abstract

This paper describes effects of close collisions on ion oscillations in a fully ionized plasma. The damping rate due to the ion-ion collisions is derived from the Boltzmann-Vlasov equation which includes the collision terms used by Bhatnagar et al. (cf. Phys. Rev. 94 (1954) 511). The so-called “two-stream instability” in a plasma is considered in some detail taking into account the effects of the collisions. As the collision frequencies become large compared with the frequencies of oscillations, the results tend to those of the two-fluid model and the ion oscillations are stable so far as the relative drift velocity between electrons and ions is not larger than the thermal velocities of these particles.