Simulating the nonlinear interaction of relativistic electrons and tokamak plasma instabilities: implementation and validation of a fluid model

V. Bandaru (Corresponding author), M. Hölzl, F.J. Artola, G. Papp, G.T.A. Huijsmans

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

For the simulation of disruptions in tokamak fusion plasmas, a fluid model describing the evolution of relativistic runaway electrons and their interaction with the background plasma is presented. The overall aim of the model is to self-consistently describe the nonlinear coupled evolution of runaway electrons (REs) and plasma instabilities during disruptions. In this model, the runaway electrons are considered as a separate fluid species in which the initial seed is generated through the Dreicer source, which eventually grows by the avalanche mechanism (further relevant source mechanisms can easily be added). Advection of the runaway electrons is considered primarily along field lines, but also taking into account the E×B drift. The model is implemented in the nonlinear magnetohydrodynamic (MHD) code jorek based on Bezier finite elements, with current coupling to the thermal plasma. Benchmarking of the code with the one-dimensional runaway electron code go is done using an artificial thermal quench on a circular plasma. As a first demonstration, the code is applied to the problem of an axisymmetric cold vertical displacement event in an ITER plasma, revealing significantly different dynamics between cases computed with and without runaway electrons. Though it is not yet feasible to achieve fully realistic runaway electron velocities close to the speed of light in complete simulations of slowly evolving plasma instabilities, the code is demonstrated to be suitable to study various kinds of MHD-RE interactions in MHD-active and disruption relevant plasmas.

Original languageEnglish
Article number063317
Number of pages11
JournalPhysical Review E
Volume99
Issue number6
DOIs
Publication statusPublished - 27 Jun 2019

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magnetohydrodynamic stability
Nonlinear Interaction
Fluid Model
Plasma
Electron
fluids
electrons
magnetohydrodynamics
interactions
thermal plasmas
Bézier
advection
Avalanche
avalanches
Benchmarking
Advection
Interaction
seeds
electron scattering
simulation

Cite this

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abstract = "For the simulation of disruptions in tokamak fusion plasmas, a fluid model describing the evolution of relativistic runaway electrons and their interaction with the background plasma is presented. The overall aim of the model is to self-consistently describe the nonlinear coupled evolution of runaway electrons (REs) and plasma instabilities during disruptions. In this model, the runaway electrons are considered as a separate fluid species in which the initial seed is generated through the Dreicer source, which eventually grows by the avalanche mechanism (further relevant source mechanisms can easily be added). Advection of the runaway electrons is considered primarily along field lines, but also taking into account the E×B drift. The model is implemented in the nonlinear magnetohydrodynamic (MHD) code jorek based on Bezier finite elements, with current coupling to the thermal plasma. Benchmarking of the code with the one-dimensional runaway electron code go is done using an artificial thermal quench on a circular plasma. As a first demonstration, the code is applied to the problem of an axisymmetric cold vertical displacement event in an ITER plasma, revealing significantly different dynamics between cases computed with and without runaway electrons. Though it is not yet feasible to achieve fully realistic runaway electron velocities close to the speed of light in complete simulations of slowly evolving plasma instabilities, the code is demonstrated to be suitable to study various kinds of MHD-RE interactions in MHD-active and disruption relevant plasmas.",
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Simulating the nonlinear interaction of relativistic electrons and tokamak plasma instabilities : implementation and validation of a fluid model. / Bandaru, V. (Corresponding author); Hölzl, M.; Artola, F.J.; Papp, G.; Huijsmans, G.T.A.

In: Physical Review E, Vol. 99, No. 6, 063317, 27.06.2019.

Research output: Contribution to journalArticleAcademicpeer-review

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