Research on the effect of resonant magnetic perturbations on disruption limit in J-TEXT tokamak

Hu, Qiming; Wang, Nengchao; Yu, Q.; Ding, Yonghua; Ren, Bo; Chen, Zhipeng; Jin, Hai

doi:10.1088/0741-3335/58/2/025001

Cited by 12 publications

(14 citation statements)

References 31 publications

(51 reference statements)

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“…However, most of the experimental and modeling results have focused on stable and healthy plasma, which is obviously different for the actual situation in ITER. For the inevitable disruption in ITER, uncontrolled modes, which can be controlled for instance by a combination of applied resonant magnetic perturbation (RMP) [19][20][21], electron cyclotron current drive [22] and electrode biasing [23], are likely to appear before the application of DMS [24]. In addition, statistical studies of disruptions on JET have found that they nearly all exhibit signs of mode locking before the disruption takes place [25].…”

Section: Nuclear Fusionmentioning

confidence: 99%

The impact of an m/n = 2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT

et al. 2019

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Locked modes (LMs) will be one of the major causes of disruptions in the ITER tokamak. Disruption mitigation systems (DMSs), such as massive gas injection (MGI) or shattered pellet injection (SPI), are expected to be deployed in pre-disruption discharges with large pre-existing locked modes. A series of target plasmas with an m/n = 2/1 locked mode induced by resonant magnetic perturbation (RMP) penetration was terminated by an MGI on the J-TEXT tokamak. The penetration of the injected impurities during the process was diagnosed using a fast frame visible camera and a multi-channel polarimeter-interferometer (POLARIS) in combination. The electron temperature evolution during thermal quench (TQ) is also shown in detail. It is found that both the phase and width of the 2/1 mode have an effect on MGI shutdown dynamics. When the mode is larger than the critical width, the penetration depth and assimilation of impurities can be enhanced during pre-TQ, leading to a faster quenching process if the relative phase between the O-point of the 2/1 mode and the MGI valve is ∆φ = +90°. Conversely, the penetration depth and assimilation of impurities are suppressed, leading to a slower TQ when the relative phase is ∆φ = −90°. The toroidal radiation asymmetry is worse with the locked mode. The results suggest that the 3D effect between the injected impurities and the 2/1 locked mode is important during the disruption mitigation process.

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Section: Nuclear Fusionmentioning

confidence: 99%

The impact of an m/n = 2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT

et al. 2019

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“…Previous researches on J-TEXT demonstrated that the field penetration threshold increases with the increase of density and scales proportionally to n 0.5 e in the range of (0.7-2.7) × 10 19 m −3 [20]. However, an unexpected lower field penetration threshold was recently observed in higher density plasma in a series of discharges [30]. Facts above show that the field penetration threshold can even decrease with an increase of the density in some cases, accentuating the question how the field penetration threshold depends on the density.…”

mentioning

confidence: 94%

Disentanglement of density and rotation dependences of the field penetration threshold on the J-TEXT tokamak

Huang

Liang

et al. 2020

Nucl. Fusion

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The field penetration threshold of magnetic perturbations has been observed to vary non-monotonically with an increase of density in ohmic plasmas on the J-TEXT tokamak. This observation appears contradicting the previous empirical density scaling law. Disentanglement of plasma density and rotation dependences of the field penetration threshold has been carried out. It shows that the field penetration threshold depends only weakly on the density but linearly on the plasma rotation. This result is not only important for the prediction of error field tolerance in fusion devices, but also opens a question on the role of density in the forced magnetic reconnection process in magnetized plasmas.

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“…Theories of error field penetration have been developed in past decades and explained the experimental observations [6,[17][18][19][20][21]. In particular, for locked mode theory based on the frame of MHD [22][23][24][25], the bifurcated state of rotating plasma has been analyzed in different response regimes.…”

Section: Introductionmentioning

confidence: 99%

Density scaling of error field penetration in radio-frequency-dominant heating plasmas in the EAST tokamak

et al. 2021

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The density scaling of n = 1 error field penetration is investigated under radio-frequency (RF)-dominant heated L-mode discharges in the EAST tokamak. It is found that the density scaling of the threshold field strength for error field penetration in lower-hybrid current drive (LHCD) plasmas is about b r ∝ n e 0.4 , where b r represents the error field amplitude. The results show a weaker density dependence compared to that observed in the previous ohmic heated discharges (Wang et al 2018 Nucl. Fusion 58 056024). For a better understanding of the density scaling, it is compared with field penetration theories, and it is found that it lies in the Waelbroeck regime. The observed scaling is consistent with that evaluated with the magnetohydrodynamic (MHD) theory on error field penetration, for which all the physical parameters are determined experimentally. Due to the density dependence of LHCD heating efficiency, the stronger negative correlation between density and temperature results in a weaker density scaling in these LHCD plasmas. Using realistic parameters under LHCD and ohmic heating as input, respectively, the numerical results based on a reduced MHD model reproduce well the scaling from the error field penetration theory and the observations. Besides, the density scaling in various tokamak operational regimes is also numerically investigated. This provides an excellent validation of MHD theory on error field penetration in the RF-dominant heated L-mode discharges.

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Research on the effect of resonant magnetic perturbations on disruption limit in J-TEXT tokamak

Cited by 12 publications

References 31 publications

The impact of an m/n = 2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT

The impact of an m/n = 2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT

Disentanglement of density and rotation dependences of the field penetration threshold on the J-TEXT tokamak

Density scaling of error field penetration in radio-frequency-dominant heating plasmas in the EAST tokamak

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