SMuK 2023 – scientific programme
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P: Fachverband Plasmaphysik
P 10: Magnetic Confinement III/HEPP V
P 10.1: Invited Talk
Wednesday, March 22, 2023, 11:00–11:30, CHE/0091
Diagnosing the plasma edge with helium beam spectroscopy — •Michael Griener and the ASDEX Upgrade Team — Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching
The outer 5% of the plasma radius of magnetically confined fusion plasmas – the plasma edge region – plays a key role for reactor performance. It sets the boundary for the plasma core by establishing transport barriers and it distributes the power to the plasma facing components.
The power and particle transport at the plasma edge is influenced by coherent plasma modes and turbulent structures like convective filaments. To study these important physical phenomena, diagnostics with high spatiotemporal resolution are required as typical structures with a size of around 1 cm move with velocities of several km/s.
One diagnostic dedicated to this is active spectroscopy on a locally injected neutral helium beam, which gets excited mainly by plasma electrons. Dependent on temperature Te and density ne of the plasma electrons, the population densities of the neutral helium energy levels vary. Subsequently, ne and Te can be reconstructed out of measured line intensity ratios together with a collisional radiative model.
In this talk the diagnostic principle is explained and inventive measurements of plasma modes and filaments in fusion reactor relevant plasma scenarios are discussed.