Excitation of ionization instability in microwave discharge plasma

Summary form only given. In a gaseous discharge, the ionization frequency is a strong function of RF wave field amplitude. A perturbation in the wave distribution can result in strong modification of local ionization rate and introduce a density perturbation. The modification of the local dielectric constant of the plasma due to the density perturbation leads to effects on wave distribution. The nonlinear self-focusing effect tends to trap wave intensity in the density trough. However, the wave electric field tends to increase with the decrease of the dielectric constant. Therefore, before the self-focusing effect takes over, the induced density perturbation gives rise to a positive feedback to the wave electric field perturbation. An ionization instability can thus be excited. This instability process has been examined analytically by Gil'denburg and Kim (1978), who derived the growth rate and the oscillation frequency of the instability. An experiment was performed to verify the theoretical results.