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Accueil > Séminaires & Soutenances > Séminaires, soutenances de thèses et HDR précédents > 2019 > Soutenances de thèses et HDR 2019 > Le vendredi 27 septembre 2019 à 10h
Le vendredi 27 septembre 2019 à 10h
Soutenance de thèse de Romain Lucken
Lieu : Sorbonne Université Campus Pierre et Marie Curie, 4 place Jussieu, 75005 Paris (Salle : Tours 22-23, salle 317, 3e étage).
La présentation se déroulera en Anglais et sera suivie d’un buffet.
Titre : Theory and Simulations of Low Pressure Plasma Transport Phenomena
Abstract :
The field of low-temperature plasma physics has emerged from the first fundamental discoveries in atom and plasma physics more than a century ago. However, it has soon become driven by applications. In the first half of the XXth century, one of the most important application is the "Calutron" (California University Cyclotron) invented by E. Lawrence in Berkeley. It was part of the Manhattan project, and operated as a mass spectrometer to separate uranium isotopes. In a 1949 report of the Manhattan project, D. Bohm makes two observations that are fundamental for low-temperature plasma physics :
(i) The ions must have minimum kinetic energy when they enter the plasma sheath estimated to Te , Te being the electron temperature in eV ;
(ii) plasma transport across a magnetic field is enhanced by instabilities.
Plasma electric propulsion is used on military satellites and space probes since the 1960s and has gained more and more interest in the last twenty years as space commercial applications were developing. However, the same questions as the ones D. Bohm was faced with, namely multi-dimensional transport, plasma sheath interaction, and instabilities, arise. Theory and simulation are even more important for electric space propulsion systems design since testing in real conditions involves to launch a satellite into space.
In this work, (i) we derive the equations of the multi-dimensional isothermal plasma transport, (ii) we establish a sheath criterion that causes the magnetic confinement to saturate in low-temperature, weakly ionized plasmas, and (iii) we model the electron cooling through the magnetic filter of the PEGASES (Plasma Propulsion with Electronegative Gases) thruster. All the theories are driven and validated with extensive two-dimensional particle-in- cell (PIC) simulations, using the LPPic code that was partially developed in the frame of this project. Finally, (iv) the simulation cases are extended to an iodine inductively coupled plasma (ICP) discharge with a new set of reaction cross sections.
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