Low frequency ion acoustic instability in the positive column of a d.c. discharge

The one-dimensional dispersion equation of the electroacoustic instability of the low pressure positive column is numerically analyzed. The column steady state parameters were obtained from the plasma balance equations based on a Maxwell distribution. The computed curves are compared with the experimental dispersions measured for spontaneously existing anode-directed wave observed at the cathode end of the column. Although the agreement between the observed and computed dispersion curves is fairly good the current driven electroacoustic instability does not provide a universal explanation for all of these waves. (author)