The effect of laser-induced photodetachment in O₂ rf discharges

Using the relaxation continuum (RCT) model, numerical analysis of oxygen rf glow discharges between parallel plates with laser irradiation parallel to the electrode was performed. The oxygen discharge sustained by a sinusoidal wave voltage at a frequency of 13.56 MHz, amplitude of 200-230 V and pressure of 0.5-1.0 Torr is irradiated by the laser with a power of 300 W, width of 2 mm and wavelength of 0.53 μm. Under these conditions, laser-induced photodetachment occurs with a large enough rate to affect the discharge structure significantly. When the plasma is irradiated continuously, the number density of ions in the incident region decreases by about 30%. The electron number density and the flux in the discharge when the pulsed laser is turned on and off every ten rf cycles, show prominent temporal variation with the variation of the electric field. Electron cooling is enhanced during the laser irradiation.