Resonances In A Radio-frequency Plasma

This abstract reports new observations of resonances in the parallel plate plasma reactors and the theory of series resonance is in reasonable agreement with the experimental data. The measurements were performed in a capacitively coupled plasma reactor by feeding the RF voltage at 13.56 MHz to one of the parallel plates, the driven electrode, with a movable voltage probe immersed in plasma to resolve the resonant amplitudes of the plasma potential in space. The impedance of the plasma, at low pressures, can be represented by a combination of inductance and capacity. The resonance they observed is due to the capacities of the sheaths resonating with the inductance of the plasma. The observed series resonance at pressures of the order of 0.1 Pa can introduce a maximum transmission in the current between the electrodes and establish a relatively big resonant voltage. At some certain plasma parameters these are comparable with the fundamental voltage following their own spatial distribution curve in the plasma volume. The resonant frequency obtained together with the plasma and sheath thickness can provide the value of {omega}{sub pe} and then the local plasma density in this type of nonuniform plasma will be derived. It is especially important tomore » apply this resonance technique in the pressure range of 0.1 Pa where probe measurements are difficult.« less