Numerical Investigations on Dilute Cold Plasma Potential and Electron Temperature

TL;DR

This paper uses hybrid numerical simulations to analyze electron temperature and potential development in dilute cold plasma, confirming exponential behaviors and providing insights into steady and unsteady flow properties.

Contribution

It introduces a hybrid simulation approach combining fluid and particle methods to study plasma properties, validating theoretical exponential trends in various flow scenarios.

Findings

Electron temperature and potential profiles are smooth and exponential in steady flows.

Unsteady flows show monotonic property development during start-up and shutdown.

Large gradients cause deviations from predicted exponential behaviors.

Abstract

Simulation results are presented to demonstrate electron temperature and electrical potential development in dilute and cold plasma development. The simulation method is a hybrid method which adopted fluid model for electrons due to their high mobility, while heavy ions and neutrals are modelled with the direct simulation Monte Carlo and Particle-In-Cell methods. The flows include steady, starting-up and shutting-down scenarios. The goal is to illustrate the exponential behaviors which were predicted in several recently developed formulas. Those formulas include many coefficients related with local properties, and they are difficult to determine. Hence, those trends can only efficiently demonstrate by numerical simulations which are more convenient than experimental measurements. The results confirm several facts. For steady plasma flows, the electron temperature and potential profiles are smooth, very likely, they can be approximated with exponential functions. For unsteady flows, the property developing trends in the shutting down or starting-up processes change monotonically. Further, at locations with large gradients, the property change trends are less ideal than those formulas. This is consistent with the assumptions with which those formulas were developed.