The impact of fusion-born alpha particles on runaway electron dynamics in ITER disruptions
Journal article, 2023

In the event of a tokamak disruption in a D-T plasma, fusion-born alpha particles take several milliseconds longer to thermalise than the background. As the damping rates drop drastically following the several orders of magnitudes drop of temperature, Toroidal Alfvén Eigenmodes (TAEs) can be driven by alpha particles in the collapsing plasma before the onset of the current quench. We employ kinetic simulations of the alpha particle distribution and show that the TAEs can reach sufficiently strong saturation amplitudes to cause significant core runaway electron (RE) transport in unmitigated ITER disruptions. As the eigenmodes do not extend to the plasma edge, this effect leads to an increase of the RE plateau current. Mitigation via massive material injection however changes the Alfvén frequency and can lead to mode suppression. A combination of the TAE-caused core RE transport with other perturbation sources could lead to a drop of runaway current in unmitigated disruptions.

runaway electrons

runaway electron mitigation

alpha particles

disruption

Alfvénic instabilities

Author

A. Lier

Max Planck Society

G. Papp

Max Planck Society

Ph Lauber

Max Planck Society

Istvan Pusztai

Chalmers, Physics, Subatomic, High Energy and Plasma Physics

K. Sarkimaki

Max Planck Society

Ola Embréus

Chalmers, Physics, Subatomic, High Energy and Plasma Physics

Nuclear Fusion

0029-5515 (ISSN) 1741-4326 (eISSN)

Vol. 63 5 056018

Implementation of activities described in the Roadmap to Fusion during Horizon Europe through a joint programme of the members of the EUROfusion consortium

European Commission (EC) (101052200), 2021-01-01 -- 2025-12-31.

Subject Categories

Meteorology and Atmospheric Sciences

Fusion, Plasma and Space Physics

Condensed Matter Physics

DOI

10.1088/1741-4326/acc4de

More information

Latest update

5/3/2023 1