3D-VIRTUS: Equilibrium condition solver of radio-frequency magnetized plasma discharges for space applications

Abstract

We present 3D-VIRTUS (3-Dimensional adVanced fluId dRifT diffUsion plaSma solver), a numerical tool conceived for the evaluation of the equilibrium conditions of Helicon plasma sources, that consists of the Electro-Magnetic Module, and the FLUID Module. The first evaluates the power deposited into the plasma by the antenna that drives the discharge, and it is based on a solid numerical tool (i.e., ADAMANT). The power deposition is used by the second module to solve for the macroscopic transport of charged and neutral species by means of a fluid approach, and assuming valid the Drift-Diffusion approximation. The set of continuity, momentum, energy, and Poisson equations are solved numerically through the Finite Volume Method, and are implemented in OpenFOAM. The two modules are iterated until a converged solution is obtained. This approach allows the self-consistent evaluation of the local plasma parameters (e.g., plasma density) at equilibrium in Helicon sources that feature (i) arbitrary-shaped plasma regions, and antennas, (ii) realistic magneto-static fields generated by electromagnets or permanent magnets. The numerical accuracy of the FLUID Module has been assessed as a function of the time, and space discretization. The FLUID Module, and the 3D-VIRTUS code have been independently validated against other well-established numerical approaches and experimental measurements. Finally, 3D-VIRTUS has been exploited to investigate Helicon plasma discharges for space propulsion applications for magneto-static field values from 0 G up to 750 G.