Observation of non-local effects in ion transport channel in J-TEXT plasmas

Shi, Yuejiang; Zhang, Yang; Chen, Z. Y.; Cheng, Zhifeng; Zhang, Xiaoyi; Yan, Wei; Wen, Jie; Cai, Qinxue; Zhao, K.J.; Hong, SeulChan; Kwon, Jae-Min; Diamond, P. H.; Shi, Peng; Zhou, Hangyu; Pan, Xiaolong; Chen, Zhipeng; Yang, SeongMoo; Dong, Ye; Wang, Lu; Ding, Yonghua; Liang, Yun-Feng; Shi, Z.B.; Na, Yong-Su

doi:10.1088/1741-4326/ab8858

Cited by 7 publications

(10 citation statements)

References 39 publications

(72 reference statements)

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“…Experiment with 'cold-pulse propagation (CPP)' is more common than with 'heat-pulse propagation' [26,27], as it can be triggered more easily with a simple gas or impurity injection in the edge region of the tokamak plasmas. The impurity injections by laser blow off of target materials [1][2][3] and by gas injection through supersonic molecular beam [4][5][6] led to a significant drop in the edge temperature along with an increase in the core temperature.…”

Section: Introductionmentioning

confidence: 99%

Gas-puff induced cold pulse propagation in ADITYA-U tokamak

Macwan¹,

Raj²,

Singh³

et al. 2021

Nucl. Fusion

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Short bursts (∼1 ms) of gas, injecting ∼1017–1018 molecules of hydrogen and/or deuterium, lead to the observation of cold pulse propagation phenomenon in hydrogen plasmas of the ADITYA-U tokamak. After every injection, a sharp increase in the chord-averaged density is observed followed by an increase in the core electron temperature. Simultaneously, the electron density and temperature decrease at the edge. All these observations are characteristics of cold pulse propagation due to the pulsed gas application. The increase in the core temperature is observed to depend on the values of both the chord-averaged plasma density at the instant of gas-injection and the amount of gas injected below a threshold value. Increasing the amount of gas-puff leads to higher increments in the core-density and the core-temperature. Interestingly, the rates of rise of density and temperature remain the same. The gas-puff also leads to a fast decrease in the radially outward electric field together with a rapid increase in the loop-voltage suggesting a reduction in the ion-orbit loss and an increase in Ware-pinch. This may explain the sharp density rise, which remains mostly independent of the toroidal magnetic field and plasma current in the experiment. Application of a subsequent gas-puff before the effect of the previous gas-pulse dies down, leads to an increase in the overall electron density and consequently the energy confinement time.

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Section: Introductionmentioning

confidence: 99%

Gas-puff induced cold pulse propagation in ADITYA-U tokamak

Macwan¹,

Raj²,

Singh³

et al. 2021

Nucl. Fusion

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“…Following the previous observation of non-local transport (NLT) in multiple transport channels (electron temperature, particle, and momentum) [53], recent J-TEXT experiments reveal that the ion transport channel shows a similar non-local response to the electron transport channel [54], owing to the improved temporal resolution of the ion temperature measurement to millisecond level. Very fast ion temperature decreases are observed in the edge, while the ion temperature in the core promptly begin to rise after injection of the cold pulse.…”

Section: Observation Of Non-local Effects In Ion Transport Channelmentioning

confidence: 68%

Advances in physics and applications of 3D magnetic perturbations on the J-TEXT tokamak

Wang¹,

Liang²,

Ding³

et al. 2022

Nucl. Fusion

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In the recent two years, three major achievements have been made on J-TEXT in supporting for the expanded operation regions and diagnostic capabilities, e.g. the 105 GHz/500 kW/1 s ECRH system and the poloidal divertor configuration. Especially, the 400 kW ECW has also been successfully injected into the diverted plasma. The locked mode (LM), especially the 2/1 LM, is one of the biggest threats to the plasma operation. Both the thresholds of 2/1 and 3/1 LM are observed to vary non-monotonically on electron density. The electrode biasing (EB) was applied successfully to unlock the LM from either a rotating or static RMP field. In the presence of 2/1 LM, three kinds of standing wave (SW) structures have been observed to share a similar connection to the island structure, i.e. the nodes of the SWs locate around the O- or X- points of the 2/1 island. The control and mitigation of disruption is essential to the safe operation of ITER, and it has been systematically studied by applying RMP field, MGI and SPI on J-TEXT. When the RMP induced 2/1 LM is larger than a critical width, the MGI shutdown process can be significantly influenced. If the phase difference between the O-point of LM and the MGI valve is +90° (or -90°), the penetration depth and the assimilation of impurities can be enhanced (or suppressed) during the pre-TQ phase and result in a faster (or slower) thermal quench. A secondary MGI can also suppress the RE generation, if the additional high-Z impurity gas arrives at the plasma edge before TQ. When the secondary MGI has been applied after the formation of RE current plateau, the RE current can be dissipated, and the dissipation rate increases with the injected impurity quantity, and saturates with a maximum of 28 MA/s.

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“…Typical of these is the well know experiment of Gentle et al [7], in which a rapid rise in core temperature is observed in response to edge cooling. Ongoing work continues the study of these "non-local phenomena" [8].…”

Section: Introductionmentioning

confidence: 88%

“…When the zonally averaged profiles ⟨T ⟩ and ⟨n⟩ exhibit no corrugations, as shown in figure 1, we set 8) and ( 9) are the evolution equations for vorticity. In equation (8), the second term on the R.H.S can be combined with the L.H.S., yielding a useful evolution equation for potential vorticity ( φ − ∆ φ). Equation (9) shows that zonal vorticity evolves according to Reynolds force, as expected.…”

Section: From Kinetics To Pv Dynamicsmentioning

confidence: 99%

Physics of turbulence spreading and explicit nonlocality

Yan

Diamond

2021

Plasma Phys. Control. Fusion

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In this paper, we systematically derive a model for turbulence spreading from the basic kinetic equation. The model contains explicit nonlocal nonlinear diffusion and nonlocal growth. When the nonlocality scale parameter δ b (banana width) vanishes, this model reduces to the usual turbulence spreading model. We elucidate the mechanisms of nonlinear saturation and nonlocal growth. Results show that nonlocal effects, especially the nonlocal growth, thicken the turbulence spreading front and increase the speed of front propagation. More turbulence intensity penetrates the stable region when δ b increases. The penetration depth ∆ p is proportional to δ b /L T , therefore the fraction of turbulence in the unstable region scales as 1 − δ b * . The transport scales the same way.

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Observation of non-local effects in ion transport channel in J-TEXT plasmas

Cited by 7 publications

References 39 publications

Gas-puff induced cold pulse propagation in ADITYA-U tokamak

Gas-puff induced cold pulse propagation in ADITYA-U tokamak

Advances in physics and applications of 3D magnetic perturbations on the J-TEXT tokamak

Physics of turbulence spreading and explicit nonlocality

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