Reduced fluid simulation of runaway electron generation in the presence of resistive kink modes

Matsuyama, Akinobu; Aiba, N.; Yagi, M.

doi:10.1088/1741-4326/aa6867

Cited by 17 publications

(20 citation statements)

References 46 publications

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“…That is, when the RE current fraction is increased, the region outside the resistive layer tends towards the ideal MHD limit in which the low-resistivity analytical scaling is valid. Such a behaviour has also been observed by Matsuyama et al [167] in a similar (but not identical) case.…”

Section: Runaway Electron Fluidsupporting

confidence: 81%

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The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

et al. 2021

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JOREK is a massively parallel fully implicit non-linear extended magneto-hydrodynamic (MHD) code for realistic tokamak X-point plasmas. It has become a widely used versatile simulation code for studying large-scale plasma instabilities and their control and is continuously developed in an international community with strong involvements in the European fusion research programme and ITER organization. This article gives a comprehensive overview of the physics models implemented, numerical methods applied for solving the equations and physics studies performed with the code. A dedicated section highlights some of the verification work done for the code. A hierarchy of different physics models is available including a free boundary and resistive wall extension and hybrid kinetic-fluid models. The code allows for flux-surface aligned iso-parametric finite element grids in single and double X-point plasmas which can be extended to the true physical walls and uses a robust fully implicit time stepping. Particular focus is laid on plasma edge and scrape-off layer (SOL) physics as well as disruption related phenomena. Among the key results obtained with JOREK regarding plasma edge and SOL, are deep insights into the dynamics of edge localized modes (ELMs), ELM cycles, and ELM control by resonant magnetic perturbations, pellet injection, as well as by vertical magnetic kicks. Also ELM free regimes, detachment physics, the generation and transport of impurities during an ELM, and electrostatic turbulence in the pedestal region are investigated. Regarding disruptions, the focus is on the dynamics of the thermal quench (TQ) and current quench triggered by massive gas injection and shattered pellet injection, runaway electron (RE) dynamics as well as the RE interaction with MHD modes, and vertical displacement events. Also the seeding and suppression of tearing modes (TMs), the dynamics of naturally occurring TQs triggered by locked modes, and radiative collapses are being studied.

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Section: Runaway Electron Fluidsupporting

confidence: 81%

“…While various applications of the model are on their way, some studies have already been performed. Similar approaches are followed by other codes, see e.g., references [167,[285][286][287].…”

Section: Vertical Displacement Events and Halo Current Dynamicsmentioning

confidence: 99%

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

et al. 2021

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“…The MHD instabilities can lead to deconfinement of both runaway electrons and bulk plasma, with significant oscillations observed in ECE and interferometer signals [22]. To understand the effect of runaway electrons on MHD instabilities, efforts have been taken on both theoretical analysis and numerical simulations [23][24][25][26]. In these works, it is found that the linear growth rate of MHD instabilities is approximately the same as in a plasma without runaway electrons, but the nonlinear saturation level is different [23].…”

Section: Introductionmentioning

confidence: 99%

Structure and overstability of resistive modes with runaway electrons

Liu,

Zhao,

Jardin

et al. 2020

Preprint

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We investigate the effects of runaway electron current on the dispersion relation of resistive magnetohydrodynamic (MHD) modes in tokamaks. We present a new theoretical model to derive the dispersion relation, which is based on the asymptotic analysis of resistive layer structure of the modes. It is found that in addition to the conventional resistive layer, a new runaway current layer can emerge whose properties depend on the ratio of the Alfvén velocity to the runaway electron convection speed. Due to the contribution from this layer, both the tearing mode and kink mode will have a real frequency in addition to a growth rate. The derived dispersion relation has been compared with numerical results using both a simplified eigenvalue calculation and a M3D-C 1 linear simulation, and good agreement is found in both cases.

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“…For example, it was shown in Ref. [6] that the non-linear evolution of the (1, 1) kink mode becomes insensitive to the RE advection velocity as long as it is significantly larger than the Alfvén speed.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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 non-linear 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, that 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 non-linear 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 demostrated to be suitable to study various kinds of MHD-RE interaction in MHD-active and disruption relevant plasmas.

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Reduced fluid simulation of runaway electron generation in the presence of resistive kink modes

Cited by 17 publications

References 46 publications

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

Structure and overstability of resistive modes with runaway electrons

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

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