Interaction between ion acoustic waves and electron plasma waves

The interaction between long-wavelength ion acoustic waves and short-wavelength electron plasma waves has been examined in a low density Q-machine plasma. When the two waves were excited simultaneously, the electron wave became amplitude modulated, giving rise to ponderomotive forces acting on the electrons, and thus in turn affecting the propagation characteristics of the ion acoustic waves. The influence of the electron plasma waves was to reduce the phase velocity and the damping distance of the ion acoustic wave. The experimental results are supported by theoretical considerations based on a simple model by introducing an effective electron temperature.