Full-Fluid Moment Model for Gas Breakdown and Low Temperature, Partially Magnetized Plasmas

Transport in low temperature plasmas (LTPs), both magnetized and unmagnetized, is not fully understood, despite its effect on industrial plasma conditions in microchip etching and semiconductor fabrication. As such, a high-fidelity fluid model is needed in the LTP community to help explain the transport phenomena. In particular, the most commonly used fluid model in the LTP community utilizes the so-called drift-diffusion (DD) approximation, neglecting the inertial term. This talk will discuss the formulation of the full fluid moment (FFM) model that solves the full momentum equation, thus capturing inertial effects, and present the results obtained from the FFM model. The boundary condition treatment included in the model uses kinetic fluxes, which are obtained from reconstructed velocity distribution functions. The ability of FFM to capture inertial effects allows it to more accurately model phenomena compared to conventional DD models. Applications of FFM, such as direct current (DC) and radio frequency (RF) breakdown, are presented to demonstrate the ability of the model, showing good agreement with the results obtained from a particle-in-cell/Monte Carlo collision (PIC-MCC) model and showing some deviation from the DD model, particularly at a rarefied (collisionless) condition. The FFM model is also used to study azimuthally rotating spokes in a Penning-type configuration, showing that the spokes are driven in the direction of the diamagnetic drift, as opposed to the Ε×Β drift. The FFM results led to development of a gradient drift instability theory including the electron inertial effects. The advantages, limitations, and future directions of the FFM model will be discussed.