Alpha particle driven Alfvénic instabilities in ITER post-disruption plasmas

Nuclear Fushion

article

A. Lier¹  G. Papp¹  Ph. W. Lauber¹  O. Embreus²  G.J. Wilkie³  S. Braun⁴ 

[1] Max Planck Institute for Plasma Physics;Department of Physics, Chalmers University of Technology;Princeton Plasma Physics Laboratory, Princeton;Center for Computational Engineering Science, RWTH Aachen University

关键词: runaway electrons;    ITER disruption;    alpha particle;    Alfv´enic instabilities;   

DOI  :  10.1088/1741-4326/ac054c

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Fusion-born alpha particles in ITER disruption simulations are investigated as a possible drive of Alfvénic instabilities. The ability of these waves to expel runaway electron (RE) seed particles is explored in the pursuit of a passive, inherent RE mitigation scenario. The spatiotemporal evolution of the alpha particle distribution during the disruption is calculated using the linearized Fokker–Planck solver CODION coupled to a fluid disruption simulation. These simulations are done in the limit of no alpha particle transport during the thermal quench, which can be seen as a most pessimistic situation where there is also no RE seed transport. Under these assumptions, the radial anisotropy of the resulting alpha population provides free energy to drive Alfvénic modes during the quench phase of the disruption. We use the linear gyrokinetic magnetohydrodynamic code LIGKA to calculate the Alfvén spectrum and find that the equilibrium is capable of sustaining a wide range of modes. The self-consistent evolution of the mode amplitudes and the alpha distribution is calculated utilizing the wave-particle interaction tool HAGIS. Intermediate mode number ( n= 7–15, 22–26) toroidal Alfvén eigenmodes are shown to saturate at an amplitude of up toδB / B≈ 0.1% in the spatial regimes crucial for RE seed formation. We find that the mode amplitudes are predicted to be sufficiently large to permit the possibility of significant radial transport of REs.

【 授权许可】

Unknown