Divertor modelling and extrapolation to reactor conditions

Kukushkin, A.S.; Pacher, H.D.

doi:10.1088/0741-3335/44/6/320

Cited by 108 publications

(101 citation statements)

References 17 publications

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“…The fraction of magnetic energy dissipated in the coils and vessel can be found from extrapolating to ℎ = 0, which gives / ≈ 45 − 50% for MGI. This is slightly higher compared to values of 25-45% found in previous studies on non-MGI disruptions [26,28]. For the VDE / is even higher, about 70%.…”

Section: Figure 12 Energy Radiated Until the End Of The Thermal Quencontrasting

confidence: 63%

Disruption mitigation by massive gas injection in JET

et al. 2011

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Abstract. Disruption mitigation is mandatory for ITER in order to reduce forces, to mitigate heat loads during the thermal quench (TQ) and to avoid runaway electrons. A fast disruption mitigation valve (DMV) has been installed at JET to study mitigation by massive gas injection (MGI). Different gas species and amounts have been investigated with respect to timescales and mitigation efficiency. We discuss the mitigation of halo currents as well as sideways forces during vertical displacement events, the mitigation of heat loads by increased energy dissipation through radiation, the heat loads which could arise by asymmetric radiation and the suppression of runaway electrons.

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Section: Figure 12 Energy Radiated Until the End Of The Thermal Quencontrasting

confidence: 63%

Disruption mitigation by massive gas injection in JET

et al. 2011

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“…The coupled energy is calculated from the current decay using a lumped parameter model for the mutual inductance, which includes energy flow to the vessel and the divertor coils [5,6]. For fast current quenches (CQ), the coupled energy amounts to 50% and to 30% for very long current decays.…”

Section: Fig 1: Comparison Of Two Disruptions With Cfc and Ilw Whicmentioning

confidence: 99%

Impact and mitigation of disruptions with the ITER-like wall in JET

et al. 2013

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Abstract:Disruptions are a critical issue for ITER because of the high thermal and magnetic energies that are released on short time scales, which results in extreme forces and heat loads. The choice of material of the plasma facing components (PFCs) can have significant impact on the loads that arise during a disruption. With the ITER-like wall (ILW) in JET made of beryllium in the main chamber and tungsten in the divertor, the main finding is a low fraction of radiation. This has dropped significantly with the ILW from 50-100% of the total energy being dissipated in the plasma with CFC to less than 50% on average and down to just 10% for VDEs. All other changes in disruption properties and loads are consequences of this low radiation: long current quenches, high vessel forces caused by halo currents and toroidal current asymmetries as well as severe heat loads. Temperatures close to the melting limit have been locally observed on upper first wall structures during deliberate VDE and even at plasma currents as low as 1.5 MA and thermal energy of about 1.5 MJ only. A high radiation fraction can be regained by massive injection of a mixture of 10%Ar with 90%D 2 . This accelerates the current quench and by this reducing halo and sideways impact. The temperature of PFCs stays below 400 ∘ C. MGI is now a mandatory tool to mitigate disruptions in closed-loop operation for currents at and above 2.5 MA in JET.

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“…During these events, the plasma thermal energy is lost on a very short time-scale [2,3], followed by a rapid decay of the plasma current in the resistive cold plasma [4][5][6][7][8][9]; these phases of the disruption are known as the thermal and current quench, respectively. The impulsive thermal loading associated with this energy loss [2,3,[10][11][12] can lead to severe melting and/or ablation of material surfaces facing the plasma. The eddy-currents driven by the current quench can cause large electromagnetic loads on invessel components [13].…”

Section: : Introduction and Backgroundmentioning

confidence: 99%

Characterization of disruption halo currents in the National Spherical Torus Experiment

Gerhardt¹,

Ménard²,

Sabbagh³

et al. 2012

Nucl. Fusion

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This paper describes the general characteristics of disruptions halo currents in the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)].The commonly observed types of vertical motion and resulting halo current patterns are described, and it is shown that plasma discharges developing between components can facilitate halo current flow. The halo current fractions and toroidal peaking factors at various locations in the device are presented. The maximum product of these two metrics for localized halo current measurements is always significantly less than the worst-case expectations from conventional aspect ratio tokamaks (which are typically written in terms of the total halo current). The halo current fraction and impulse is often largest in cases with the fastest plasma current quenches and highest quench rates. The effective duration of the halo current pulse is comparable to or shorter than the plasma current quench time. The largest halo currents have tended to occur in lower β and lower elongation plasmas. The sign of the poloidal halo current is reversed when the toroidal field direction is reversed. PACS: 52.55. Ez, 52.55.Tn

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Divertor modelling and extrapolation to reactor conditions

Cited by 108 publications

References 17 publications

Disruption mitigation by massive gas injection in JET

Disruption mitigation by massive gas injection in JET

Impact and mitigation of disruptions with the ITER-like wall in JET

Characterization of disruption halo currents in the National Spherical Torus Experiment

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