Simulations of nitrogen glow discharge phenomena for high-speed flow control

Plasma actuators offer a promising opportunity for high-speed flow control applications. The forcing of the flow occurs through three primary mechanisms: electrohydrodynamic forcing or ion drag, dilatation effects related to gas heating, and magnetohydrodynamic forcing in the presence of magnetic fields. In order to gain a physical understanding of these factors, we developped a detailed computational model for the plasma and bulk flow. The model is based on a two-dimensional, self-consistent, multi-species continuum description of the plasma. We use a two-temperature chemical kinetics model that includes the following species: e$^{-}$, N$_{2}^{+}$, N$^{+}$, N, and N$_{2}$. In this work, a surface plasma actuator with two bare-electrodes on a single plane is considered. The imposed background flow-field simulates a boundary layer with an external velocity of 700 m/s. Results include maps of charge density, temperature and electric potential profiles. For a pressure of 5 Torr and an applied voltage of 2500 V, the sheath region in front of the cathode is about 5 mm thick. The peak electron number density reaches $\sim $1e16 m\^{}(-3) in the bulk plasma. The number density of N$_{2}^{+}$ is found to be dominant in the discharge, about two orders of magnitude higher than that of N$^{+}$. Relative contributions of the body forces will be explored for different operating conditions.