Kinetic modelling of runaway electron generation in argon-induced disruptions in ASDEX Upgrade
Journal article, 2020

Massive material injection has been proposed as a way to mitigate the formation of a beam of relativistic runaway electrons that may result from a disruption in tokamak plasmas. In this paper we analyse runaway generation observed in eleven ASDEX Upgrade discharges where disruption was triggered using massive gas injection. We present numerical simulations in scenarios characteristic of on-axis plasma conditions, constrained by experimental observations, using a description of the runaway dynamics with a self-consistent electric field and temperature evolution in two-dimensional momentum space and zero-dimensional real space. We describe the evolution of the electron distribution function during the disruption, and show that the runaway seed generation is dominated by hot-tail in all of the simulated discharges. We reproduce the observed dependence of the current dissipation rate on the amount of injected argon during the runaway plateau phase. Our simulations also indicate that above a threshold amount of injected argon, the current density after the current quench depends strongly on the argon densities. This trend is not observed in the experiments, which suggests that effects not captured by zero-dimensional kinetic modelling - such as runaway seed transport - are also important.

fusion plasma

plasma simulation

runaway electrons

Author

Klara Insulander Björk

Chalmers, Physics, Subatomic, High Energy and Plasma Physics

G. Papp

Max Planck Society

Ola Embréus

Chalmers, Physics, Subatomic and Plasma Physics

Linnea Hesslow

Chalmers, Physics, Subatomic and Plasma Physics

Tünde Fülöp

Chalmers, Physics, Subatomic, High Energy and Plasma Physics

Oskar Vallhagen

Chalmers, Physics, Subatomic and Plasma Physics

A. Lier

Max Planck Society

G. Pautasso

Max Planck Society

A. Bock

Max Planck Society

Journal of Plasma Physics

0022-3778 (ISSN) 1469-7807 (eISSN)

Vol. 86 4 855860401

Running away and radiating (PLASMA)

European Commission (EC), 2015-10-01 -- 2020-09-30.

Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium (EUROfusion)

European Commission (EC), 2014-01-01 -- 2019-01-01.

Runaway electrons in fusion plasmas

Swedish Research Council (VR), 2018-12-01 -- 2021-12-31.

Subject Categories

Other Physics Topics

Fusion, Plasma and Space Physics

Condensed Matter Physics

DOI

10.1017/S0022377820000793

More information

Latest update

10/8/2020