Collisional Radiative models

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Table of contents

Résumé
Abstract
Remerciements
Contents
List of Figures
List of Tables
1 Introduction
1.1 The challenge of energy
1.1.1 Historical approach
1.1.2 Fossil fuels: availability and consequences
1.1.3 Alternative energy sources
1.1.4 Energy generation fromnuclear fusion
1.2 Nuclear fusion reactor
1.2.1 Fusion reactions
1.2.2 Ignition
1.2.3 Confinement
1.2.4 Tokamak
1.2.5 Existing tokamaks
1.3 Scope of this thesis
2 X-ray radiation
2.1 Introduction
2.2 X-ray emission
2.2.1 Bremsstrahlung emission
2.2.2 Radiative recombination
2.2.3 Spontaneous emission
2.3 Ionization equilibrium
2.3.1 Local Thermodynamical Equilibrium
2.3.2 Corona Equilibrium
2.3.3 Collisional Radiative models
2.3.4 Effect of impurity transport on the equilibrium
2.4 Total plasma emissivity
2.4.1 X-ray emissivity on ITER
2.4.2 Influence of impurity transport on the X-ray emissivity
2.5 Extraction of plasma parameters from X-ray measurement
2.5.1 Impurity density
2.5.2 Impurity transport coefficients
2.5.3 Electron temperature
3 X-ray measurement
3.1 Photodiodes
3.1.1 Semiconductor photodiodes
3.1.2 Vacuum photodiodes
3.2 Gas detectors
3.2.1 Ionization chambers
3.2.2 Multi-anodes Low Voltage Ionization Chamber
3.2.3 Gas ElectronMultipliers
3.2.4 X-rays detectors for ITER nuclear phase
3.3 X-ray tomography
3.3.1 Overview
3.3.2 MinimumFisher Information method
3.4 Accuracy of the X-ray emissivity calculation tool
4 Simulation of a Low Voltage Ionization Chamber on ITER
4.1 Line-integration of the emissivity
4.1.1 Simplified representation of a detector-aperture system
4.1.2 Pixelization of the plasma
4.2 Interaction between X-ray photons and matter
4.2.1 Absorption processes
4.2.2 Inelastic scattering: Compton effect
4.2.3 Elastic scattering processes
4.2.4 Pair production
4.2.5 Relative importance of the different processes
4.3 Synthetic diagnostic
4.3.1 Computation of the different physical processes
4.3.2 Monte Carlo-based synthetic diagnostic
4.3.3 Matrix-based synthetic diagnostic
4.3.4 Comparison of the twomethods
5 X-ray tomography on ITER
5.1 ITER radial X-ray cameras
5.2 Tomographic capabilities
5.2.1 Figures of merit
5.2.2 Emissivity profiles
5.2.3 Tomographic reconstructions
5.3 Addition of lines-of-sight: proof of concept
5.4 Geometry proposal
5.4.1 60 vertical lines-of-sight configuration
5.4.2 44 vertical lines-of-sight configuration
6 Application of the synthetic diagnostic
6.1 X-ray measurement on ITER with Low Voltage Ionization Chambers
6.1.1 Influence of the filling gas
6.1.2 Influence of the filter
6.1.3 Influence of the length pressure product
6.2 Calibration of the LVIC measured current
6.2.1 Calibrationmethodology
6.2.2 Line-of-sight dependency of the calibration factor
6.2.3 Application to simulation results
6.3 Tomography using LVIC
6.3.1 Tomographic reconstruction of a SXR-restricted emissivity profile
6.3.2 Influence of the calibration method on the tomographic reconstruction
6.3.3 Tomographic reconstruction over a wide energy range
6.3.4 Influence of perturbative noise on the tomographic reconstruction
6.3.5 Alternative calibration method
7 Application to impurity transport study
7.1 Reconstruction of the tungsten transport coefficients on ITER
7.1.1 Scenarios
7.1.2 LVIC measurement
7.1.3 Negative V scenario reconstruction
7.1.4 Positive V scenario reconstruction
7.2 Poloidal asymmetries
7.2.1 Collisional regimes
7.2.2 Theory of parallel forces
7.2.3 Poloidal asymmetries on ITER
8 Energy discrimination using LVIC
8.1 Spectral deconvolution method
8.1.1 Hypothesis on the X-ray spectrum
8.1.2 Minimization algorithm
8.2 Application to ITER
8.2.1 Figures of merit
8.2.2 Spectral deconvolution using argon-filledMA-LVIC
8.2.3 Spectral deconvolution using xenon-filled MA-LVIC
8.2.4 Comparison between argon and xenon
8.2.5 Improving the reconstruction in the [2, 3] keV energy band
8.2.6 Sensitivity analysis
8.3 Energy-resolved X-ray tomography
8.3.1 Figures of merit
8.3.2 Results
8.3.3 Sensitivity analysis
8.4 Reconstruction of the electron temperature
8.4.1 Figures of merit
8.4.2 Results
8.4.3 Sensitivity analysis
9 Conclusion and perspectives
Bibliography