LAUSR

A comparative study of capacitively coupled radio frequency discharges was conducted using 2-D particle-in-cell simulation (PIC) and 2-D fluid plasma simulation. The selected scenario was a planar discharge with a 3-cm gap operated in helium, at a gas pressure of 400 Pa, with a driving voltage between 120 and 400 V at 3.2 MHz. The solvers were adapted to a 1-D problem by using periodic boundary conditions perpendicular to the gap, and the models included ion impact-induced secondary electron emission from the electrodes. A good agreement was obtained between the results of both solvers, with less than 23% deviation in the peak plasma density. For the studied range of secondary emission coefficients, $0.08 < \gamma _{\mathrm {se}} < 0.378$ , it was found that a common transition point between “alpha” and “gamma” modes occurs at $V_{\mathbf {rf}} \sim 250$ V. Since the simulation results were shown to be less sensitive to the secondary emission coefficient below this transition voltage, these results can serve as a standard benchmark for plasma codes.