Diffusion Waves in Low Density Plasmas

Abstract

The diffusion waves in a plasma are analyzed for the ion-neutral collision frequency greater than the ion plasma frequency. It is, then, observed that with the increase in frequency, the diffusion wave tends to a mode governed by an electron free diffusion rather than the ion acoustic mode. The experiment has been mode in an axially decaying helium plasma produced by r.f. discharge at the pressures of 2.0 and 4.0 Torr. The interferometer patterns of the diffusion waves are well explained by the theory proposed here.