Numerical simulations of DC discharges in Argon: Investigating light emission spatial profiles

Capacitively coupled direct current (DC) powered plasmas are created by applying a steady, high voltage to a set of electrodes immersed in a gaseous medium. Kinetic simulation of low temperature DC plasmas allows for the detailed analysis of ion and electron energy distribution functions, plasma temperatures, and boundary layer physics relevant to semiconductor manufacturing, sterilization process of microelectronics, and industrial lighting. Here, the Particle-in-Cell (PIC) technique, with both the Direct Simulation Monte Carlo (DSMC) and Monte Carlo Collision (MCC) simulation method was used to simulate a DC, low-temperature plasma formation in Argon gas operating at 100's of mTorr. The gap distance is taken to be 1 cm with an applied voltage of 500 V to 1500 V. The simulation results are compared to experimental spectral measurements to begin to validate the numerical model. In general, an observed higher excited state density and light emission is observed near the powered electrode with a lower intensity region near the cathode. Additionally, the simulations indicate a dependence on the secondary electron emission yield at the cathode regarding overall plasma characteristics. Thus, electron emission from the cathode surface is a key process to accurately predicting plasma behavior in DC discharges.