A comparison of particle in cell and fluid model simulations of low-pressure radio frequency discharges

A comparison is made between particle-in-cell model (PIC) and fluid model simulations of a radio frequency (rf) gaseous discharge containing a helium model gas. The agreement in the discharge properties predicted by the two models is examined over a range of pressures and applied voltages. It is found that there is quantitative agreement in the overall discharge behavior predicted by the PIC and fluid simulations at pressures above 100 mTorr and applied voltages up to 800 V. With the exception of the ion energy at the electrodes, the two models also agree in their prediction of the scaling of discharge properties as a function of the applied voltage. Below 100 mTorr, disagreement in the period-averaged electron heating predicted by each model leads to differences in the predicted discharge properties. The estimate for the electron power input prediction can be improved in the fluid simulation by including an analytic expression for stochastic heating in the electron energy balance equation.