Dispersion of Ionization Waves in Positive Columns

The dispersion relations for the ionization, ion-acoustic and electron plasma waves are numerically calculated from the basic equations which consist of the continuity and momentumequations for electrons and ions, the energy balance equation for electrons and the Maxwellequations. Only the ionization wave among the three waves is detectable at the gas pressure of a few Torr. First, it is confirmed that the values for the real part of the frequency agree well with the experimental ones but the imaginary part shows some discrepancy. Next, the method is extended to calculate the dispersion relation for a gas mixture by assuming that the basic equations are modified by considering each ion. The calculated results agree qualitatively withthose observed for the ionization wave in a mixture of Ne–He.