Recent advances in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si6.svg"><mml:msub><mml:mi>β</mml:mi><mml:mi>N</mml:mi></mml:msub></mml:math> experiments and magnetohydrodynamic instabilities with hybrid scenarios in the HL-2A Tokamak

Chen, W.; Yu, Liming; Xu, M.; Ji, Xiao; Shi, Z.B.; He, Xiaoxue; Li, Z.J.; Li, Y.G.; Wang, T.B.; Jiang, M.; Gong, Shuwen; Wen, Jie; Shi, P.W.; Yang, Z.C.; Fang, Kairui; Li, J.; Lai, W.; Zhong, Weizhi; Sun, A.P.; Cao, Jianyong; Ding, X.T.; Dong, Dingfeng; Yang, Qingwei; Liu, Yi; Yan, L.W.; Wang, Z.X.; Duan, Xuru

doi:10.1016/j.fmre.2021.12.011

Cited by 13 publications

(9 citation statements)

References 40 publications

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“…These simulation results are qualitatively consistent with that observed in DIII-D, where the experimental evidence shows a transition from a linear to quadratic dependence for the EP loss rate with increasing perturbation amplitude [29]. A direct comparison with the HL-2A experiments is not yet possible, due to limitations in the energetic ion diagnostics (such as fast ion D α , fast ion loss detector [28] for the high-β N discharges [26].…”

Section: Xk-induced Ep Transportsupporting

confidence: 85%

“…In the high-β N regime, global MHD instabilities with perturbation structures similar to that of XKs are observed in various devices [23][24][25]. Recently, a global instability is observed during NBI heating in the HL-2A high-β N experiments [26]. Furthermore, FLMs are often observed in the wall-stabilized high-β N (above the no-wall β N limit) plasmas in JT-60U [27,28] and DIII-D [12,29].…”

Section: Introductionmentioning

confidence: 98%

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Effects of external kink and fishbone-like modes on energetic particle transport in tokamak plasmas

Wang

Hao²,

Zou³

et al. 2022

Nucl. Fusion

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Transport and loss of beam injected energetic-particles (EPs) due to three-dimensional (3D) perturbations, associated with the external kink (XK) instability and fishbone-like mode (FLM), are numerically investigated utilizing the guiding center following code ORBIT for static toroidal plasmas in HL-2A. The perturbation structure for the XK is computed by the MARS-F code and then mapped to the Boozer coordinates as defined in ORBIT. The simulation shows that the EP profile experiences a significant change in the middle of the plasma column, when the XK-induced radial magnetic field perturbation amplitude, normalized by the equilibrium field, exceeds a threshold value of about 10−2. The EP transport is found to be dominated by a diffusion process instead of convection. Furthermore, by scanning the perturbation frequency as a free parameter while maintaining the XK mode structure (thus mimicking the FLM as observed in DIII-D and JT-60U tokamaks), redistribution and loss of EPs are found to be substantially enhanced due to strong resonances between the FLM and EPs, when the mode frequency exceeds a threshold value of ~2 kHz for the case considered. For either XK or FLM, the response of passing EPs to the perturbation is dominant due to the assumed tangential neutral beam injection. Most lost EPs due to these instabilities are initially passing particles but are eventually lost through trapped orbits.

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Section: Xk-induced Ep Transportsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 98%

Effects of external kink and fishbone-like modes on energetic particle transport in tokamak plasmas

Wang

Hao²,

Zou³

et al. 2022

Nucl. Fusion

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“…H-mode discharges have been achieved with NBI heating, electron cyclotron resonance heating (ECRH) and lower hybrid current drive (LHCD) in HL-2A [45][46][47]. The main parameters for H-mode plasmas are plasma current I p = 140-200 kA, toroidal magnetic field B t = 1.2-1.5 T and line-averaged electron density n e = (2-3) × 10 19 m -3 .…”

Section: Characteristicsmentioning

confidence: 99%

The effect of impurity seeding into the closed divertor on plasma detachment in the HL-2A tokamak

et al. 2023

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Recent progress towards an increased understanding of the detached divertor physics has been made with the very closed divertor geometry in HL-2A. Non-intrinsic impurities were injected into the outer divertor chamber, and increased divertor neutral pressure and enhanced volumetric energy loss in the divertor were observed. Meanwhile the neutral pressure in the main chamber decreased slightly, and neutral compression between divertor and main chamber increased largely. This led to divertor detachment with a low level of upstream plasma line-averaged electron density (~0.5n_GW). In H-mode, a little degradation of the core confinement, characterized by decrease of plasma stored energy and pedestal pressure, and increase of edge localized mode (ELM) frequency, was observed, but the H-mode was still sustained well with H98>1. The pedestal density fluctuation was increased during detachment, implying that the enhanced pedestal transport might be responsible for the degradation. During divertor detachment phase, the impurities were well controlled in the divertor without strong radiation near X-point region, and the main plasma density did not increase but decreases slightly, this could be beneficial from the very closed divertor geometry. The experimental results suggest that, the very closed divertor geometry has the advantages of volumetric energy loss, gas pumping and impurity control in the divertor without significant effects on the plasma confinement, thus gives a wider operation window for the divertor detachment.

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“…Each fishbone/sawtooth/internal kink mode [1][2][3][4][5] and tearing mode (TM) [6][7][8] has been frequently observed in tokamak experiments and widely investigated experimentally, theoretically and numerically. Energetic particles [9][10][11] are inevitably produced in burning plasmas (such as alpha particles from deuterium and tritium fusion reactions) and via auxiliary heating methods such as neutral beam injection (NBI). A great deal of attention has been paid to the interaction between the fishbone/sawtooth/internal kink mode and energetic ions over the past few decades and the understanding of underlying physics about it is relatively mature [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Hybrid-kinetic simulation of synergy between fishbone/sawtooth and tearing mode-induced energetic-ion transport in a tokamak plasma

Zhu

Chen

et al. 2023

Nucl. Fusion

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The resonant interaction between m/n = 2/1 tearing mode (TM) and energetic-ions redistributed by m/n = 1/1 fishbone/sawtooth collapse is evidently observed recently in HL-2A NBI-heated high-density plasmas, where m is poloidal mode number and n is toroidal mode number. This event essentially results from a typical synergistic effect with multiple-mode nature. Understanding such experimental phenomenon, especially when using high-power auxiliary heating, is crucial for achieving the high-performance plasmas with high confinement and high β N in the prospective thermonuclear fusion reactors. In this work, based on the typical experimental phenomenon of synergy between fishbone/sawtooth and TM on HL-2A, a self-consistent nonlinear hybrid-kinetic simulation is conducted utilizing the experimental parameters and profiles before the occurrence of this synergy as the code M3D-K input. In particular, we focus chiefly on the phase-space transport, loss and redistribution of energetic-ions induced by two cases, one with only m/n = 2/1 TM and one with the synergy between m/n = 1/1 fishbone/sawtooth and m/n = 2/1 TM. It is found that the synergy of the fishbone/sawtooth and m/n = 2/1 TM on eneregtic-ion transport, loss and redistribution is significantly important and can dramatically enhance the loss rate of energetic- ions compared with the case with only m/n = 2/1 TM. It is due to the fact that such synergy can open up an efficient energetic-ion loss channel which connects the plasma center and edge. The phase space transport and redistribution of energetic-ions induced by the two different cases are also respectively analyzed and compared in detail. These findings indicate that the synergy triggering the sawtooth collapse is catastrophic and can help us understand the underlying mechanisms of synergy induced energetic-ion transport in the future reactor-grade devices such as International Thermonuclear Experimental Reactor.

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Recent advances in high-βN experiments and magnetohydrodynamic instabilities with hybrid scenarios in the HL-2A Tokamak

Cited by 13 publications

References 40 publications

Effects of external kink and fishbone-like modes on energetic particle transport in tokamak plasmas

Effects of external kink and fishbone-like modes on energetic particle transport in tokamak plasmas

The effect of impurity seeding into the closed divertor on plasma detachment in the HL-2A tokamak

Hybrid-kinetic simulation of synergy between fishbone/sawtooth and tearing mode-induced energetic-ion transport in a tokamak plasma

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