Characteristics of halo currents in JT-60U

Neyatani, Y.; Yoshino, R.; Nakamura, Y.; Sakurai, S.

doi:10.1088/0029-5515/39/4/312

Cited by 47 publications

(54 citation statements)

References 13 publications

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“…Hence, it is clear, and intuitive, that the stored energy just prior to the disruption is the relevant quantity. It has been speculated that plasmas with large pre-disruption stored energy create more impurities during the phase of the disruption proceeding the halo currents, thus increasing the halo resistance [27]; the present data is consistent with that hypothesis, though without reliable and routine measurements of the halo temperature and resistivity, this suggestion remains an untested hypothesis. Additionally, plasmas that disrupt at large stored energy and high β N in NSTX are often more centered in the vessel through the disruption process, compared to those which have large pre-disruption stored energy loss or that disrupt earlier in the discharge.…”

Section: C) Time Duration Of the Halo Current Pulsesupporting

confidence: 84%

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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Section: C) Time Duration Of the Halo Current Pulsesupporting

confidence: 84%

Characterization of disruption halo currents in the National Spherical Torus Experiment

Gerhardt¹,

Ménard²,

Sabbagh³

et al. 2012

Nucl. Fusion

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“…The differing interpretation of the JET data in [49] and the IDDB JET data is likely due to the fact that the IDDB possesses many more data points than reference [49]. The higher data resolution in the IDDB makes it clear that the inverse relationship interpreted from the data inm reference [53] was a figment of the relatively small number of samples available. NSTX exhibits a monotonic increase in the maximum FTPF as the current decay rate increases.…”

Section: Halo Currentmentioning

confidence: 99%

“…This effect is attributed to an increase in impurity density due to increased conducted heat flux to the divertor, which in turn cools the halo region, makes it more resistive, and reduces the total halo current [49,53]. However, as shown in figure 10, this…”

Section: Halo Currentmentioning

confidence: 99%

The ITPA disruption database

et al. 2015

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Abstract.A multi-device database of disruption characteristics has been developed under the auspices of the International Tokamak Physics Activity magneto-hydrodynamics topical group. The purpose of this ITPA Disruption Database (IDDB) is to find the commonalities between the disruption and disruption mitigation characteristics in a wide variety of tokamaks in order to elucidate the physics underlying tokamak disruptions and to extrapolate toward much larger devices, such as ITER and future burning plasma devices. In contrast to previous smaller disruption data collation efforts, the IDDB aims 2 to provide significant context for each shot provided, allowing exploration of a wide array of relationships between pre-disruption and disruption parameters. The IDDB presently includes contributions from nine tokamaks, including both conventional aspect ratio and spherical tokamaks. An initial parametric analysis of the available data is presented. This analysis includes current quench rates, halo current fraction and peaking, and the effectiveness of massive impurity injection. The IDDB is publicly available, with instruction for access provided herein.3

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“…This halo current was produced in SOL component and flows into the vacuum vessel through in-vessel components that may give rise to large force acting on the vessel and in-vessel components [2]. The number of research articles has been published to investigate the halo current in other Tokamak devices such as JET [3], JT-60U [4], and NSTX [5]. Like in Experimental Advanced Superconducting Tokamak (EAST) reactor [6][7][8], there are some failures of the feedback control in VD event caused by disruption.…”

Section: Introductionmentioning

confidence: 99%

Theoretical relation between halo current-plasma energy displacement/deformation in EAST

Khan

Song

et al. 2018

J Theor Appl Phys

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In this paper, theoretical model for calculating halo current has been developed. This work attained novelty as no theoretical calculations for halo current has been reported so far. This is the first time to use theoretical approach. The research started by calculating points for plasma energy in terms of poloidal and toroidal magnetic field orientations. While calculating these points, it was extended to calculate halo current and to developed theoretical model. Two cases were considered for analyzing the plasma energy when flows down/upward to the diverter. Poloidal as well as toroidal movement of plasma energy was investigated and mathematical formulations were designed as well. Two conducting points with respect to (R, Z) were calculated for halo current calculations and derivations. However, at first, halo current was established on the outer plate in clockwise direction. The maximum generation of halo current was estimated to be about 0.4 times of the plasma current. A Matlab program has been developed to calculate halo current and plasma energy calculation points. The main objective of the research was to establish theoretical relation with experimental results so as to precautionary evaluate the plasma behavior in any Tokamak.

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Characteristics of halo currents in JT-60U

Cited by 47 publications

References 13 publications

Characterization of disruption halo currents in the National Spherical Torus Experiment

Characterization of disruption halo currents in the National Spherical Torus Experiment

The ITPA disruption database

Theoretical relation between halo current-plasma energy displacement/deformation in EAST

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