Axisymmetric benchmarks of impurity dynamics in extended-magnetohydrodynamic simulations

Lyons, Brendan; Kim, C. C.; Liu, Y. Q.; Ferraro, N.M.; Jardin, S.C.; McClenaghan, Joseph; Parks, P.B.; Lao, L. L.

doi:10.1088/1361-6587/ab0e42

Cited by 32 publications

(61 citation statements)

References 30 publications

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“…M3D-C1 has been used to study several phenomena related to tokamak disruptions, such as vertical displacement event (VDE) [21], generation of halo current [22], and thermal quench due to impurities injection [23]. Given the importance of REs in disruption studies, we have implemented a fluid model of REs in M3D-C1, by adding a new equation describing the evolution of RE density [14].…”

Section: Fluid Model Of Re In Mhdmentioning

confidence: 99%

Self-consistent simulation of resistive kink instabilities with runaway electrons

Liu

Zhao²,

Jardin³

et al. 2021

Preprint

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A new fluid model for runaway electron simulation based on fluid description is introduced and implemented in the magnetohydrodynamics code M3D-C1, which includes self-consistent interactions between plasma and runaway electrons. The model utilizes the method of characteristics to solve the continuity equation for the runaway electron density with large convection speed, and uses a modified Boris algorithm for pseudo particle pushing. The model was employed to simulate magnetohydrodynamics instabilities happening in a runaway electron final loss event in the DIII-D tokamak. Nonlinear simulation reveals that a large fraction of runaway electrons get lost to the wall when kink instabilities are excited and form stochastic field lines in the outer region of the plasma. Plasma current converts from runaway electron current to Ohmic current. Given the good agreement with experiment, the simulation model provides a reliable tool to study macroscopic plasma instabilities in existence of runaway electron current, and can be used to support future studies of runaway electron mitigation strategies in ITER.

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Section: Fluid Model Of Re In Mhdmentioning

confidence: 99%

Self-consistent simulation of resistive kink instabilities with runaway electrons

Liu

Zhao²,

Jardin³

et al. 2021

Preprint

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“…These have been extensively described in Refs. [6,5]. M3D-C 1 is a non-linear 3D extended-MHD code that uses high-order finite elements and implicit time-stepping to advance the equations in time.…”

Section: Pellet-injection Modeling In M3d-cmentioning

confidence: 99%

“…The ablated material is initialized as neutrals and all the atomic physics (ionization, recombination, radiation, etc) is calculated with the KPRAD module that is coupled to the extended MHD equations [6,5]. Thus, different source terms σ s are generated for main ions and each charge state of impurities (here, each charge state is considered a different species).…”

Section: Pellet-injection Modeling In M3d-cmentioning

confidence: 99%

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Modeling of carbon pellets disruption mitigation in an NSTX-U plasma

Clauser,

Jardin,

Raman

et al. 2021

Preprint

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Single carbon pellet disruption mitigation simulations using M3D-C 1 were conducted in an NSTX-U-like plasma to support the electromagnetic pellet injection concept (EPI). A carbon ablation model has been implemented in M3D-C 1 and tested with available data. 2D simulations were conducted in order to estimate the amount of carbon needed to quench the plasma, finding that the content in a 1 mm radius vitreous carbon pellet (∼ 3.2 × 10 20 atoms) would be enough if it is entirely ablated. 3D simulations were performed, scanning over pellet velocity and parallel thermal conductivity, as well as different injection directions and pellet concepts (solid pellets and shell pellets). The sensitivity of the thermal quench and other related quantities to these parameters has been evaluated. A 1 mm radius solid pellet only partially ablates at velocities of 300 m/s or higher, thus being unable to fully quench the plasma. To further enhance the ablation, approximations to an array of pellets and the shell pellet concept were also explored. 3D field line stochastization plays an important role in both quenching the center of the plasma and in heat flux losses, thus lowering the amount of carbon needed to mitigate the plasma when compared to the 2D case. This study constitutes an important step forward in 'predict-first' simulations for disruption mitigation in NSTX-U and other devices, such as ITER.

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“…The spatial scales of the problem range from sub-millimeter-size (the scale of high density gradients in the ablation cloud near the pellet surface, affecting the ablation rates) to multi-meter-size (the distances traveled by the ablated material in tokamak plasma). Tokamak codes such as M3D-C1 and NIMROD have performed simulations of the tokamak plasma dynamics in the presence of ablating impurities (jets), pellets and SPI fragments [4][5][6]. Such global scale numerical simulations cannot resolve physics processes determining pellet ablation rates and employ semi-analytic models for impurities.…”

Section: Introductionmentioning

confidence: 99%

Near-field simulations of pellet ablation for disruptions mitigation in tokamaks

Bosviel,

Parks,

Samulyak

2020

Preprint

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Detailed numerical studies of the ablation of a single neon pellet in the plasma disruption mitigation parameter space have been performed. Simulations were carried out using FronTier, a hydrodynamic and low magnetic Reynolds number MHD code with explicit tracking of material interfaces. FronTier's physics models resolve the pellet surface ablation and the formation of a dense, cold cloud of ablated material, the deposition of energy from hot plasma electrons passing through the ablation cloud, expansion of the ablation cloud along magnetic field lines and the radiation losses. A local thermodynamic equilibrium model based on Saha equations has been used to resolve atomic processes in the cloud and Redlich-Kwong corrections to the ideal gas equation of state for cold and dense gases have been used near the pellet surface. The FronTier pellet code is the next generation of the code described in [R. Samulyak, T. Lu, P. Parks, Nuclear Fusion, (47) 2007, 103-118]. It has been validated against the semi-analytic improved Neutral Gas Shielding model in the 1D spherically symmetric approximation. Main results include quantification of the influence of atomic processes and Redlich-Kwong corrections on the pellet ablation in spherically symmetric approximation and verification of analytic scaling laws in a broad range of pellet and plasma parameters. Using axially symmetric MHD simulations, properties of ablation channels and the reduction of pellet ablation rates in magnetic fields of increasing strength have been studied. While the main emphasis has been given to neon pellets for the plasma disruption mitigation, selected results on deuterium fueling pellets have also been presented.

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Axisymmetric benchmarks of impurity dynamics in extended-magnetohydrodynamic simulations

Cited by 32 publications

References 30 publications

Self-consistent simulation of resistive kink instabilities with runaway electrons

Self-consistent simulation of resistive kink instabilities with runaway electrons

Modeling of carbon pellets disruption mitigation in an NSTX-U plasma

Near-field simulations of pellet ablation for disruptions mitigation in tokamaks

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