Speaker
Description
Nuclear fusion is a promising solution to the world energy problems, but it requires a mixture of deuterium and tritium to be heated to temperatures exceeding 100 million degrees Celsius. Regimes with improved confinement, such as the H-mode, are being considered for a future fusion reactor. The existence of a strong shear (gradient) in the plasma flow is thought to be fundamental for the turbulence suppression, explaining the transition to H-mode. The origin of the flow shear is still not fully understood and therefore flow measurements are required to better understand the turbulence suppression process.
This proposal focuses on the characterization of the edge flow profile when approaching the transition to H-mode at JET (Joint European Torus, EUROfusion, UK), contributing to a better understanding of the transition physics and its triggering mechanisms. To this purpose, detailed measurements were obtained by Doppler backscattering, a microwave diagnostic that measures the propagation velocity of the turbulent structures. A large dataset is available at JET with varied plasma parameters that should allow for the characterization of the flow shear and its dependence on the plasma parameters. This work will help to clarify the importance of shear flows in the H-mode access.
