Observation of large-amplitude ion acoustic wave in microwave-plasma interaction experiments

Large amplitude ion acoustic wave, which is not satisfied with a linear dispersion relationship of ion acoustic wave, is observed in microwave-plasma interaction experiments. This ion acoustic wave is excited around critical density layer and begins to propagate to underdense region with a phase velocity one order faster than sound velocity Cs, which is predicted by the linear theory, the phase velocity and the wave length of the wave decreases as it propagates. Finally, it converges to Cs and strongly dumps. Diagnostic by the Faraday cup indicates that this ion acoustic wave is accompanied with a hot ion beam. (author)