SMuK 2021 – scientific programme

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P: Fachverband Plasmaphysik

P 13: Magnetic Confinement IV & Helmholtz Graduate School IV

P 13.3: Talk

Thursday, September 2, 2021, 14:55–15:20, H4

Alpha particle dynamics and Alfvenic instabilities in ITER post-disruption plasmas — •Andrej Lier¹, Gergely Papp¹, Philipp Lauber¹, Stefanie Braun², George Wilkie³, and Ola Embreus⁴ — ¹Max Planck Institute for Plasma Physics, D-85748 Garching, Germany — ²Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden — ³Princeton Plasma Physics Laboratory, Princeton NJ 08540, USA — ⁴Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden

Fusion-born alpha particles in ITER disruption simulations are investigated as a possible drive of Alfvenic instabilities. The ability of these waves to expel RE seed particles is explored in the pursuit of a passive, inherent RE mitigation scenario in synergy with built-in RE mitigation systems. An analytical model is introduced that is able to compute the spatiotemporal evolution of the alpha particle distribution in a mitigated thermal quench. We use a linear gyrokinetic stability code to calculate the Alfven spectrum and find that the equilibrium is capable of sustaining a wide range of modes. The natural radial anisotropy of the alpha population provides free energy to drive Alfvenic modes during the quench phase of the disruption. The self-consistent evolution of the mode amplitudes and the alpha distribution is calculated utilizing wave-particle interaction methods. Intermediate mode number Toroidal Alfven Eigenmodes (TAEs) are shown to saturate at an amplitude of up to dB/B ~ 0.1% in the spatial regimes crucial for RE seed formation.