Effects of Ion-Atom Collisions on the Propagation and Damping of Ion-Acoustic Waves

Abstract

Experiments are described on ion‐acoustic wave propagation and damping in alkali plasmas of various degrees of ionization. An increase of the ratio $T_e{\mathrm{/T}}_i$ from 1 to approximately 3‐4, caused by ion‐atom collisions, results in a decrease of the (Landau) damping of the waves. At high gas pressure and/or low wave frequency a “fluid” picture adequately describes the experimental results.