Wave Characteristics in E×B Source: Pressure-Dependent Evolution of Plasma Oscillation Phenomena

We have observed a pressure-dependent evolution of plasma oscillation in the E×B source. The wave characteristics of plasma oscillation were thoroughly measured with multi-array probes to investigate the changes in frequency and wavenumber of the oscillations. At relatively high pressure in the range of mTorr, the Simon-Hoh instability with harmonic components was readily observed in the measured frequency-wavenumber resolved power spectrum density. The fundamental frequency of the Simon-Hoh Instability is near 35 kHz, and their harmonics (i.e., second and third harmonics) are distinguishable. As the working pressure decreases, the Simon-Hoh instability and breathing mode (below 30 kHz) co-exist. In contrast, the extinction of the Simon-Hoh instability with a high mode number occurs as the power density of the breathing mode increases. Finally, the evolution of the wave properties has been discussed in detail with the theoretical description of the dispersion relation.