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Accueil > A propos du LPP > Communication > Actualités archivées > 2025 > Nicolas Lequette defended his PhD "Numerical modelling of the PEGASES spacecraft thruster"
Nicolas Lequette defended his PhD "Numerical modelling of the PEGASES spacecraft thruster"
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On February 6, 2025, Nicolas Lequette defended his PhD "Numerical modelling of the PEGASES spacecraft thruster".
Abstract :
The electric spacecraft propulsion industry is actively transitioning to new propellants. Until recently, the favoured propellant was xenon. It is the heaviest stable noble gas, characteristics that enhance the thrust-to-power ratio of electric thrusters. However, the limited supply cannot satisfy the growing demand as space industrializes.
New propulsion systems are designed around lighter noble gases, trading efficiency for affordability. Others make use of molecular propellants, namely
iodine. Despite being reactive, this element, a neighbour of xenon in the periodic table, can offer similar performances with the benefit of a higher storage density.
The development of the next propulsion systems requires design and simulation tools adapted to alternative propellants. In this work, we propose using
a 1D Particle-In-Cell code coupled with a fluid model as a fast way to simulate the low-pressure discharges found in electric thrusters. We implemented an
analytical model to emulate the particle transport in the unsimulated directions. This method allows the simulation of simple geometries with a 1D model. In addition, the vacuum permittivity scaling technique allows to speed up whole device simulations.
To ensure the accuracy of our model, we extensively validated it using the diagnostic data measured on the PEGASES thruster. This validation process covered a range of noble gases and iodine ICP discharges, including argon, krypton, xenon.
Noble gas validation showed that the code could reproduce the trends in the electron parameters as the pressure and power evolved. However, its reduced dimensionality and the fluid model hinder its predictive power at low pressure and high power. In iodine, the low-pressure simulations are in good agreement with the experimental data. However, the model struggles to maintain the delicate balance between the numerous species at high pressure.
Jury :
Pere Roca, Directeur de Recherche, École polytechnique, président
Gilles Cartry, Professeur, PIIM, Aix-Marseille Université, rapporteur
Laurent Garrigues, Directeur de Recherche, LAPLACE, Université de Toulouse, rapporteur
Trevor Lafleur, Senior lecturer, UNSW Canberra, examinateur
Victor Désangles, Chargé de Recherche, ONERA, examinateur
Pascal Chabert, Directeur de Recherche, LPP, Ecole polytechnique, directeur de thèse
Anne Bourdon, Directrice de Recherche, LPP, Ecole polytechnique, directrice de thèse
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