Light scattering studies of the ion-acoustic instability in a positive column plasma.
01 January 1985
Light scattering is used to study the amplitude, spectrum and angular distribution of the saturated state of the ion-acoustic instability in a He positive-column plasma. The ion acoustic waves are driven unstable by the electron current in the column. The properties of the saturated state are studied as a function of the concentration of hydrogen impurities which are found to be present in positive column plasmas. At concentrations of a few percent, the hydrogen ions can cause linear wave damping. Their role in saturating the instability by nonlinear processes is studied by varying the hydrogen concentration.