One of the main obstacles hindering the construction of a commercial fusion reactor is the control of turbulence that arises as a result of the tremendous pressure gradients resulting from the high temperatures and densities required to achieve self-sustained fusion reactions. The description of electromagnetic turbulence in a reactor-scale device cannot be done analytically, and the computational cost of numerically simulating global turbulent transport is currently prohibitive. For this reason, experimental research on turbulence is a fundamental tool for identifying mechanisms capable of bringing it down to acceptable levels, as well as for validating reduced models that can be used for predictive simulations today.
The central objective of this thesis will be the characterization of turbulence in Wendelstein 7-X, the world's largest optimized stellarator, located at the Max-Planck-Institut für Plasmaphysik facilities in Greifswald, Germany. To achieve this, a set of Doppler reflectometry systems installed by the Fusion National Laboratory group will be used to investigate high-performance scenarios developed in the upcoming experimental campaigns of 2024 and 2025, in which turbulence suppression will allow for high temperatures to be reached in the plasma center.
In addition to this main objective, other ongoing lines of research related to the thesis would include:
- Development of improvements in reflectometry systems.
- Application of machine learning techniques for automated data analysis.
- Experimental validation of gyrokinetic simulations.
- Comparison of turbulence and turbulent transport in different stellarator devices, including the LHD heliotron (Japan) and the TJ-II heliac (Madrid).
