Self-Consistent Simulation of the Excitation of Compressional Alfvén Eigenmodes and Runaway Electron Diffusion in Tokamak Disruptions

Chang Liu, Andrey Lvovskiy, Carlos Paz-Soldan, Stephen C. Jardin, Amitava Bhattacharjee

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Alfvénic modes in the current quench (CQ) stage of the tokamak disruption have been observed in experiments. In DIII-D the excitation of these modes is associated with the presence of high-energy runaway electrons (REs), and a strong mode excitation is often associated with the failure of RE plateau formation. In this work we present results of self-consistent kinetic-MHD simulations of RE-driven compressional Alfvén eigenmodes (CAEs) in DIII-D disruption scenarios, providing an explanation of the CQ modes. Simulation results reveal that high energy trapped REs can have resonance with the Alfvén mode through their toroidal precession motion, and the resonance frequency is proportional to the energy of REs. The mode frequencies and their relationship with the RE energy are consistent with experimental observations. The perturbed magnetic fields from the modes can lead to spatial diffusion of REs including the nonresonant passing ones, thus providing the theoretical basis for a potential approach for RE mitigation.

Original languageEnglish (US)
Article number085102
JournalPhysical review letters
Volume131
Issue number8
DOIs
StatePublished - Aug 25 2023

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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