Development of a multicomponent diffusion fluid solver for two-temperature plasma sheath*

Studying the plasma sheath is fundamental to a number of applications, ranging from arcing in high vacuum electronics to charging of space platforms due to plume contamination of electric thrusters: these fields differ for the variety of the species involved in the simulation of the fluid and for the different nature of the wall confining it. In this work we investigate two different approaches to plasma fluid simulations: the multifluid, commonly used in the plasma physics community, and the multicomponent approach, commonly used in the combustion and re-entry flows community; solving the electrostatic Poisson equation ensures charge conservation in the domain and allows for a continuous description of the quasineutral bulk and of the sheath. The proposed multicomponent approach offers advantages when simulating a large number of species as the number of equations (and the model complexity) is lower, with a reduction in computational cost. We compare the results of the two methods by simulating a one-dimensional discharge with an isothermal mixture of argon plasma: we adapt the boundary conditions from the classic multifluid approach and implement a semi-implicit treatment of the electric potential in order to improve the stability of the time integration scheme.