The ITPA disruption database

Eidietis, N. W.; Gerhardt, S. P.; Granetz, R.; Kawano, Y.; Lehnen, M.; Lister, J.B.; Pautasso, G.; Riccardo, V.; Tanna, R.L.; Thornton, A.

doi:10.1088/0029-5515/55/6/063030

Cited by 64 publications

(49 citation statements)

References 60 publications

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“…The data in Fig. 4, which are quantitatively consistent with the ITPA Disruption Database [14,17,43], identify C(η −1 ) = 1.2-4.2 ms/m 2 as the range to be used when projecting τ CQ to ITER. The machines that define the extrema in this range, C-Mod (4.2 ms/m 2 ) and DIII-D (1.2 ms/m 2 ), warrant further discussion.…”

Section: Disruption Current Quench Analysissupporting

confidence: 75%

A multi-machine scaling of halo current rotation

et al. 2017

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Halo currents generated during unmitigated tokamak disruptions are known to develop rotating asymmetric features that are of great concern to ITER because they can dynamically amplify the mechanical stresses on the machine. This paper presents a multi-machine analysis of these phenomena. More specifically, data from C-Mod, NSTX, ASDEX Upgrade, DIII-D, and JET are used to develop empirical scalings of three key quantities: (1) the machine-specific minimum current quench time, τ CQ ; (2) the halo current rotation duration, trot; and (3) the average halo current rotation frequency, f h. These data reveal that the normalized rotation duration, trot/τ CQ , and the average rotation velocity, v h , are surprisingly consistent from machine to machine. Furthermore, comparisons between carbon and metal wall machines show that metal walls have minimal impact on the behavior of rotating halo currents. Finally, upon projecting to ITER, the empirical scalings indicate that substantial halo current rotation above f h = 20 Hz is to be expected. More importantly, depending on the projected value of τ CQ in ITER, substantial rotation could also occur in the resonant frequency range of 6-20 Hz. As such, the possibility of damaging halo current rotation during unmitigated disruptions in ITER cannot be ruled out.

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Section: Disruption Current Quench Analysissupporting

confidence: 75%

A multi-machine scaling of halo current rotation

et al. 2017

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“…Despite the seemingly short warning timescale, 20 ms is a sufficient amount of time to deploy massive gas injection in DIII-D [56].…”

Section: Non-disruptivementioning

confidence: 99%

Statistical analysis of m/n = 2/1 locked and quasi-stationary modes with rotating precursors at DIII-D

Sweeney¹,

Choi²,

Haye³

et al. 2016

Nucl. Fusion

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Abstract.A database has been developed to study the evolution, the nonlinear effects on equilibria, and the disruptivity of locked and quasi-stationary modes with poloidal and toroidal mode numbers m = 2 and n = 1 at DIII-D. The analysis of 22,500 discharges shows that more than 18% of disruptions are due to locked or quasistationary modes with rotating precursors (not including born locked modes). A parameter formulated by the plasma internal inductance l i divided by the safety factor at 95% of the poloidal flux, q 95 , is found to exhibit predictive capability over whether a locked mode will cause a disruption or not, and does so up to hundreds of milliseconds before the disruption. Within 20 ms of the disruption, the shortest distance between the island separatrix and the unperturbed last closed flux surface, referred to as d edge , performs comparably to l i /q 95 in its ability to discriminate disruptive locked modes. Out of all parameters considered, d edge also correlates best with the duration of the locked mode. Disruptivity following a m/n = 2/1 locked mode as a function of the normalized beta, β N , is observed to peak at an intermediate value, and decrease for high values. The decrease is attributed to the correlation between β N and q 95 in the DIII-D operational space. Within 50 ms of a locked mode disruption, average behavior includes exponential growth of the n = 1 perturbed field, which might be due to the 2/1 locked mode. Surprisingly, even assuming the aforementioned 2/1 growth, disruptivity following a locked mode shows little dependence on island width up to 20 ms before the disruption. Separately, greater deceleration of the rotating precursor is observed when the wall torque is large. At locking, modes are often observed to align at a particular phase, which is likely related to a residual error field. Timescales associated with the mode evolution are also studied and dictate the response times necessary for disruption avoidance and mitigation. Observations of the evolution of β N during a locked mode, the effects of poloidal beta on the saturated width, and the reduction in Shafranov shift during locking are also presented.

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“…What is more, a multidevice International Tokamak Physics Activity (known as ITPA) disruption database (known as IDDB) including nine tokamak devices with various scales describing CQ time, halo current and massive impurity injection, has been developed by the ITPA since 1994 (Eidietis et al . 2015) in order to find commonalities of disruption characteristics over different tokamaks, and to provide parametric relationships between predisruption and disruption parameters and scaling extrapolating to International Thermonuclear Experimental Reactor (known as ITER) and other large tokamaks.…”

Section: Introductionmentioning

confidence: 99%

Magnetic energy dissipation during the current quench of disruption in EAST

et al. 2020

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A disruption database characterizing the current quench of disruptions with ITER-like tungsten divertor has been developed on EAST. It provides a large number of plasma parameters describing the predisruptive plasma, current quench time, eddy current, and mitigation by massive impurity injection, which shows that the current quench time strongly depends on magnetic energy and post-disruption electron temperature. Further, the energy balance and magnetic energy dissipation during the current quench phase has been well analysed. Magnetic energy is also demonstrated to be dissipated mainly by ohmic reheating and inductive coupling, and both of the two channels have great effects on current quench time. Also, massive gas injection is an efficient method to speed up the current quench and increase the fraction of impurity radiation.

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The ITPA disruption database

Cited by 64 publications

References 60 publications

A multi-machine scaling of halo current rotation

A multi-machine scaling of halo current rotation

Statistical analysis of m/n = 2/1 locked and quasi-stationary modes with rotating precursors at DIII-D

Magnetic energy dissipation during the current quench of disruption in EAST

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