Study on Effect of Neutral Gas Pressure on Plasma Characteristics in Capacitive RF Argon Glow Discharges at Low Pressure by Fluid Modeling

Abstract

For capacitively coupled radio frequency argon glow discharges at low pressure, based on the drift-diffusive approximation, a 1-D fluid model of the plasmas is established. The electrons and ions continuity equations and Poisson equation are simultaneously solved until a periodic steady state is achieved. Our results show that the electrons are accelerated by strong electric fields in the sheaths, resulting in more ohmic heating. These strong fields may be caused by low electron convection in bulk plasma region even when gas pressure increases due to the sheath thickness and the electrons’ temperatures all decrease. Thus, a local peak of the dissipation near the boundary between the sheath regions and the bulk plasma region is observed due to a higher local electron temperature in the sheath regions. Subsequently, the peak of the net power absorption grows in the bulk plasma region, since the electron thermal convection and dissipation contribute significantly and the electron density reaches the maximum. Finally, the ionization and excitation rates are clearly enhanced in the sheath regions compared to the bulk plasma region due to electron heating that has small changes in the bulk plasma region.