Studies of high heat-flux and runaway electron damage on plasma-facing materials

Gilligan, J.G.; Niemer, K.A.; Bourham, Mohamed; Croessmann, C.D.; Hankins, O.E.; Tallavarjula, S.; Mohanti, R.; Orton, N.P.

doi:10.1016/0022-3115(90)90143-b

Cited by 11 publications

(8 citation statements)

References 7 publications

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“…Equation of motion for charged particles in magnetic field is given in [37]. Most of previously published work [15][16][17][18][19] consider the initial runaway electron beam as parallel to the magnetic field. This is done to minimize computer time.…”

Section: Mathematical and Physical Modelmentioning

confidence: 99%

“…These studies analysed the energy of electrons, energy density of the runaway electron impact and duration of the electron impact. Several numerical simulations were carried out using realistic tokamak wall geometries and runaway electron impact parameters [15][16][17][18][19][20] and showed surface melting of wall armor material of up to several millimetres depth.…”

Section: Introductionmentioning

confidence: 99%

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Self-consistent analysis of the effect of runaway electrons on plasma facing components in ITER

Sizyuk¹,

Hassanein²

2009

Nucl. Fusion

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Physical and computational models are developed, used and benchmarked for studying the response of ITER tokamak plasma facing components to runaway electron impact following a plasma disruption. The energy deposition, temperature evolution and material melting thickness are calculated for a wide range of runaway electron parameters, namely, electron kinetic energy, magnetic field, energy partition ratio (along and across magnetic field direction) impact duration, and wall material composition. It is shown that the electron energy partition ratio will have a significant effect on the wall heat load with melting of the first wall with beryllium armor possible. If tungsten armor is used instead, the surface of the mockup is overheated and melted for all ranges of studied parameters of the runaway electrons. Using an insert of a thin layer of a high-Z material inside the beryllium armor can mitigate the heat load in the armor and heat sink structure.

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Section: Mathematical and Physical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-consistent analysis of the effect of runaway electrons on plasma facing components in ITER

Sizyuk¹,

Hassanein²

2009

Nucl. Fusion

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“…Plasma disruptions are the result of non-linearly unstable magneto-hydrodynamic (MHD) instabilities which destroy the global plasma confinement and result in rapid and localized energy deposition upon the Plasma Facing Components (PFCs), potentially causing irreversible damage to future high performance devices [1]. Among the threats posed by disruptions, the runaway electrons and their localized deposition onto the first wall are one of the most feared consequences [1][2][3] . In the most disastrous scenario, significant portion of the original plasma current could be converted into runaway electron current, and all of their kinetic energy as well as a large portion of the magnetic energy it carries could be unleashed locally [4].…”

Section: Introductionmentioning

confidence: 99%

“…[1] Among the threats posed by disruptions, the runaway electrons and their localized deposition onto the first wall is one of the most feared consequence. [1][2][3] In the most disastrous scenario, significant portion of the original plasma current could be converted into runaway electron current, and all of their kinetic energy as well as a large portion of the magnetic energy it carries could be unleashed locally. [4] This should be avoided at all costs, and there have a lot of effort going on regarding the control and depletion of such runaway current.…”

Section: Introductionmentioning

confidence: 99%

Drift surface solver for runaway electron current dominant equilibria during the current quench

Yuan

2023

Chinese Phys. B

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Runaway electron current generated during the Current Quench phase of tokamak disruptions could result in severe damage to future high performance devices. To control and mitigate such runaway electron current, it is important to accurately describe the runaway electron current dominated equilibrium, based on which further stability analysis could be carried out. In this paper, we derive a Grad-Shafranov-like equation solving for the axisymmetric drift surfaces of the runaway electrons instead of the magnetic flux surfaces for the simple case that all runaway electron share the same parallel momentum. This new equilibrium equation is then numerically solved with simple rectangular wall with ITER-like and MAST-like geometry parameters. The deviation between the drift surfaces and the flux surfaces is readily obtained, and runaway electrons is found to be well confined even in regions with open field lines. The change of the runaway electron parallel momentum is found to result in a horizontal current center displacement without any changes in the total current or the external field. The runaway current density profile is found to affect the susceptibility of such displacement, with flatter profiles result in more displacement by the same momentum change. With up-down asymmetry in the external poloidal field, such displacement is accompanied by a vertical displacement of runaway electron current. It is found that this effect is more pronounced in smaller, compact device and weaker poloidal field cases. The above results demonstrate the dynamics of current center displacement caused by the momentum space change in the runaway electrons, and pave way for future, more sophisticated runaway current equilibrium theory with more realistic consideration on the runaway electron momentum distribution. This new equilibrium theory also provides foundation for future stability analysis of the runaway electron current.

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“…1,2 During a major disruption in a tokamak reactor, the rapid release of significant amounts of energy has the potential to cause massive damage to plasma-facing components of the containment vessel and to also exert unbearably high electromagnetic forces on the structure itself leading to a failure. 3,4 Additionally, the formation of runaway electrons (REs) poses another threat in the event that runaway beams impact plasma-facing components inside the tokamak. 1,5 While impact of runaway beams with low-energy densities can be tolerated to a point, the event of a high-energy runaway beam, carrying even a small fraction of the pre-disruption plasma current, impacting the plasma-facing components locally could be catastrophic.…”

Section: Introductionmentioning

confidence: 99%

Understanding how minority relativistic electron populations may dominate charge state balance and radiative cooling of a post-thermal quench tokamak plasma

et al. 2022

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Minority relativistic electron populations can occur in a range of complex plasmas. Of specific interest is when runaway electrons form among the presence of high-atomic-number ion species in a tokamak plasma discharge. It has been recently demonstrated that ion charge state distributions and radiation losses at low bulk electron temperatures can be dominated by relativistic electrons, even though their density is orders of magnitude lower. This was attributed to the relativistic enhancement of electron impact inelastic cross sections. In this work, we provide a closer inspection of the atomic physics underpinning this effect. We also demonstrate the consequences of runaway enhanced scattering on post-disruption tokamak fusion discharges with neon and argon impurities present. Effects on charge state distributions, radiation and spectral characteristics, and reduced-order modeling considerations are discussed.

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Studies of high heat-flux and runaway electron damage on plasma-facing materials

Cited by 11 publications

References 7 publications

Self-consistent analysis of the effect of runaway electrons on plasma facing components in ITER

Self-consistent analysis of the effect of runaway electrons on plasma facing components in ITER

Drift surface solver for runaway electron current dominant equilibria during the current quench

Understanding how minority relativistic electron populations may dominate charge state balance and radiative cooling of a post-thermal quench tokamak plasma

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