Spectroscopic diagnostic of magnetic fusion plasmas: application to ITER

This thesis focuses on the modeling of the atomic line radiation emitted by magnetic fusion plasmas for diagnostic purposes. An improvement of the accuracy of diagnostics is proposed, in order to have a better characterization of runaway electrons in the context of ITER preparation. In the first chapter, we discuss about fusion reaction, about how it is produced in tokamak machines, and we discuss about the disruptions, which are a consequence of instabilities. They are one cause of runaway electrons. In the second chapter, the formalism used in spectral line broadening models is introduced based on quantum mechanics and statistical physics. Numerical calculations are also presented. They are done for applications to synthetic diagnostics in tokamak divertor plasma conditions. Hydrogen Balmer lines with a moderate principal quantum number are considered. In the third chapter, we discuss the physics underlying Langmuir waves. This includes the Landau damping process and its inverse counterpart, the plasma-beam instability mechanism. It is possible to calculate the magnitude of the electric field which is created by a beam of electrons using the quasilinear theory. We present this theory and we present a generalization to strongly nonlinear regimes for which the Langmuir waves are coupled with the ion sound and electromagnetic waves. Finally, we discuss this model and, next, apply the formalism for different beam densities in tokamak edge plasmas and we examine the possibility for making a diagnostic of runaway electrons based on atomic spectroscopy in the fourth chapter. (author)