Master thesis and internship[BR]- Master's thesis : Improving the Conditioning of the Acoustic Subsystem and Source Terms in Multifluid Plasma Equations of State[BR]- Integration Internship

Abstract

This work is realised in the ForDGe software and is a step towards the development of a tool capable of modeling electric propulsion such as Hall effect thrusters. It shows how the change from a non-dimensionlisation scheme with single velocity scale to a species dependent velocity scale improves the performances of the ForDGe software in the context of plasma modeling. ForDGe uses the Discontinuous Galerkin method, which is a combination of the principles of Finite Element and Finite Volume Methods, in combination with a Runge-Kutta time integration scheme. To explore the performances of the new non-dimensionalisation two test cases are used: the sod shock tube test case with and without computation of the electric potential. The improvements metrics are the precision of the results and the convergence rate of the linear solver used in the time integration scheme: GMRes. The precision improvement is measured in the balance of the non-dimensionalised variables and accuracy of the results as adjudicated by analytical solutions. The convergence rate is dependent on the clustering of the eigenvalues of the expanded Jacobian and its improvement is measured by the scattering of those eigenvalues. The test cases show that the new non-dimensionalisation reduces the bias towards the electron particle momentum. The multi velocity scaling scheme also finds correct results for the computation of the electric potential where the single velocity scaling scheme does not and the eigenvalues of the multi velocity scaling scheme are more clustered.