Soutenance de Francis Pagaud
| When |
Jul 01, 2024
from 02:00 to 04:00 |
|---|---|
| Where | Amphithéâtre Anne L'Huillier |
| Contact Name | Francis Pagaud |
| Attendees |
Francis Pagaud |
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Transport, waves and instabilities are common issues in magnetised plasmas, leading to fundamental problems and operating limits for fusion plasmas, plasma particle accelerators or plasma propulsion. Controlling plasma properties is desirable yet complex. First, the impact of a hot cathode on the properties of a magnetised argon plasma is studied. This element emits a significant quantity of primary electrons into the plasma core. The complex interactions between a biased hot surface and a cold plasma give rise to a rich dynamical system. A characterisation of this system highlights a detailed understanding of the cathode's thermodynamic properties, as well as a precise description of its various operating regimes. This new control parameter enables to adjust experimentally the plasma density, temperature and local electric field, thus impacting the overall plasma dynamics. An in-depth comparison with an analytical model for controlling the electrostatic potential within the plasma will be presented and criticised. Finally, the implementation of a new antenna for plasma generation will be detailed. This "helicon" source produces a high density and allows optimal plasma heating. The existence of coherent fluctuations and unstable operating regimes will be documented, and the underlying physical mechanisms will be discussed.