Observation of ion-beam instability in a two-ion species plasma

The ion-beam instability in a two-ion species plasma is studied theoretically and experimentally, where the instability is caused by the interaction between the ion acoustic wave and the heavy-ion beam with the energy higher than that in a single ion plasma. The beam energies for th unstable wave depend on both the light ion concentration and the mass ratio of the heavy ion to the light one. The experimental results agree well with those calculated by the kinetic theory. (author)