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PhD defense – Valentin JONCQUIÈRES : “Numerical model and simulation of Hall effect thrusters”

  Friday 12 April 2019 at 14h00

  Phd Thesis       SALLE DE CONFERENCES JCA, Cerfacs, Toulouse, France    

The space propulsion has been a political issue in the midst of the Cold War and remains nowadays a strategic and industrial issue. The chemical propulsion on rocket engines is limited by its ejection velocity and its lifetime. Electric propulsion and more particularly Hall effect thrusters appear then as the most powerful and used technology for space satellite operation. The physic inside a thruster is complex because of the electromagnetic fields and important collision processes. Therefore, all specificities of the engine operation are not perfectly understood. After hundreds of hours of tests, thruster walls are curiously eroded and electromagnetic instabilities are developing within the ionization chamber. The measured electron mobility is in contradiction with the analytical models and raises issues on the plasma behavior inside the discharge chamber. As a result, the AVIP code was developed to provide a massively parallel and unstructured 3D code to Safran Aircraft Engines modeling unsteady plasma inside the thruster. Lagrangian and Eulerian methods are used and integrated in the solver and my work has focused on the development of a fluid model which is faster and therefore better suited to industrial conception. The model is based on a set of equations for neutrals, ions and electrons without drift-diffusion hypothesis, combined with a Poisson equation to describe the electric potential. A rigorous expression of collision terms and a precise description of the boundary conditions for sheaths have been established. This model has been implemented numerically in an unstructured formalism and optimized to obtain good performances on new computing architectures. The model and the numerical implementation allow us to perform a real Hall effect thruster simulation. Overall operating properties such as the acceleration of the ions or the location of the ionization zone are captured. Finally, a second application has successfully reproduced azimuthal instabilities in the Hall thruster with the fluid model and justified the role of these instabilities in the anomalous electron transport and in the erosion of the walls.

Jury :

Thierry MAGIN                 Van Karman Institute, Belgium                               Referee

Khaled HASSOUNI           LIMHP-CNRS, Université Paris Nord                    Referee

Olivier SIMONIN              INP Toulouse                                                           Member

Anne BOURDON               LPP ECOLE POLYTECHNIQUE Palaiseau          Member

Paul-Quentin ELIAS         ONERA Chatillon                                                    Member

Stephan ZURBACH           SAFRANGROUP Vernon                                      Invited

Olivier VERMOREL           CERFACS, Toulouse                                             Co-advisor

Bénédicte CUENOT          CERFACS, Toulouse                                              Advisor






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