Maximization in the damping rate of the ion acoustic wave in a two-ion plasma

Abstract

The characteristics of dispersion and Landau damping of ion acoustic waves are experimentally investigated in an argon-helium plasma with varying ion composition ratio. The dispersion relations change continuously from the argon mode to the helium mode. The damping rate has a maximum when the ion number density ratio (r = nHe/nA + nHe) is about 0.08. This maximum is attributed to the resonance of helium ions with the argon mode ion acoustic wave and is consistent with theoretical predictions.