Numerical Simulation of Streamer Physics in Nanosecond Pulsed Surface Discharges

Two-dimensional numerical simulations of a nanosecond pulsed single dielectric barrier discharge (SDBD) are performed in air. Streamers produced in nanosecond SDBDs have filamentary properties and generate a strong electric field and high-density gradient of charged particles. This results in non-equilibrium effects of electrons, which makes analysis of the plasma physics challenging. To simulate the streamer discharge, a 17-species hydrodynamic plasma model is used, including an air chemistry scheme with ions and neutral species in thermal equilibrium and electrons in thermal non-equilibrium. We investigate the charged particles, the electric field and the electron energy (i.e. electron temperature) created due to collisions between high-energy particles and understand the physics of discharge. The electric field and the electron energy have different physical properties depending on the plasma generation regions (streamer head, streamer body, or sheath), and these discharge physics are consistent with the observations of other studies. Electron energy results obtained assuming non-equilibrium and equilibrium of electrons are compared to confirm the non-equilibrium effects of electrons in the streamer head and sheath. This effect is attributed to the locally large electric field gradient in the streamer head and sheath.