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Theoretical analysis and full-wave simulations combined in the development of the synthetic Doppler reflectometry diagnostics for tokamaks

Abstract : Plasma turbulence is nowadays believed to be responsible for the anomalous transport and consequently the degradation of discharge conditions in magnetic confined fusion devices, such as tokamaks. Since a good energy confinement time is crucial for achieving a positive energy yield, understanding and control of turbulent processes is currently one of the major goals of the Magnetic Confinement Fusion research. To study the plasma turbulence, experimental tools that are able to provide information about its characteristics are necessary. Such tools include microwave diagnostics and, in particular, Doppler reflectometry and radial correlation Doppler reflectometry. While these non-invasive diagnostics benefit from the simplicity of the setup, there are a number of unresolved issues when it comes to the interpretation of the experimental data. Issues such are small-angle scattering and plasma curvature effects limit the range of applicability of the simple interpretation of the measurements, while nonlinear scattering effects make it inapplicable altogether. These problems make it necessary to validate the interpretation of experimental data. Thus, the primary goal of this thesis was to create a synthetic Doppler reflectometry and radial correlation Doppler reflectometry diagnostic for the interpretation of the FT-2 tokamak experimental results. This goal is achieved by applying full-wave IPF-FD3D code to the results of gyrokinetic plasma modelling with ELMFIRE code to obtain the synthetic signals, which are then benchmarked with experimental measurements. The synthetic diagnostic is also used for a more general study of the possibility of nonlinear effects influencing the experimental measurements. Finally, the secondary goal of this thesis was to perform an analytical research of plasma curvature effects, nonlinear scattering and a novel technique for turbulence structures’ characterization. The first principles analytical study was performed by considering the Helmholtz equation and obtaining an analytical expression for the experimental signals. The results for the latter two topics were numerically validated with the partial use of specially developed linear numerical model and the full-wave IPF-FD3D code.
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Submitted on : Thursday, September 17, 2020 - 2:23:12 PM
Last modification on : Sunday, June 26, 2022 - 2:53:45 AM
Long-term archiving on: : Thursday, December 3, 2020 - 9:42:34 AM


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  • HAL Id : tel-02941925, version 1


Oleg Krutkin. Theoretical analysis and full-wave simulations combined in the development of the synthetic Doppler reflectometry diagnostics for tokamaks. Physics [physics]. Université de Lorraine; Fiziko-tekhnicheskij institut im. A. F. Ioffe (Leningrad, Russie), 2020. English. ⟨NNT : 2020LORR0042⟩. ⟨tel-02941925⟩



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