Soutenance de Simon Vincent
| When |
Dec 09, 2021
from 10:00 to 12:00 |
|---|---|
| Where | Salle Condorcet (1 place de l'école) |
| Contact Name | Simon Vincent |
| Attendees |
Simon Vincent |
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Low frequency waves are ubiquitous in magnetized plasmas. At the edge of fusion plasmas these waves are notably responsible, via wave turbulence, for an important radial transport. The plasma confinement can be greatly damaged, making these waves one of the most challenging obstacles to the achievement of sustained thermonuclear fusion.
In this PhD thesis, low-frequency waves are studied experimentally in an Argon plasma column of length 1 m and diameter 20 cm. The plasma is generated via an inductive source of power 1 kW at a pressure of 1 mTorr and confined by an axial magnetic field ranging from 170 to 640 G. In a first part the plasma parameters (density, electronic temperature, plasma potential) radial profiles are assessed by electrostatic probe measurements. Besides, fast camera imaging of the light naturally emitted by the plasma provides the spatio-temporal evolution of the low-frequency waves. A second part is dedicated to the waves identification, their non-linear interactions, and the inward wave transport they generate. In a last part a Tungsten electrode is placed at the center of the plasma column, heated up to the level of thermoionic emission, and biased with respect to the chamber ground. The current thus injected in the plasma greatly modifies its global equilibrium and the developing low-frequency waves. Simultaneous probe / camera measurements show a transition towards a convective and intermittent outward transport.