Comparison of divertor behavior and plasma confinement between argon and neon seeding in EAST

Li, Kedong; Yang, Zhongshi; Wang, Huiqian; Xu, Guosheng; Yuan, Q.P.; Guo, H.Y.; Eldon, D.; Hyatt, A.W.; Humphreys, David; Chen, Meiwen; Wu, Kai; Liu, Jianbin; He, Tao; Yang, Qian; Lin, Xin; Xu, Jichan; Meng, Lingyi; Ding, Fang; Chen, Xiaohua; Luo, Yu; Wu, Jinyong; Duan, Yanmin; Luo, Guang–Nan; Wang, Liang

doi:10.1088/1741-4326/abf418

Cited by 30 publications

(26 citation statements)

References 53 publications

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“…Also, a slight decrease of the plasma stored energy (∼8%) was observed after 10 s, which was not seen with neon seeding in an 18 s long-pulse H-mode discharge with P heat ∼ 5.5 MW (shot #101825). According to the previous detachment experiments with an upper divertor in the EAST, it has shown that the compatibility of detachment and core confinement with Ne seeding is better than that with Ar seeding [35] under present plasma conditions on the EAST.…”

Section: Long-pulse Detachment Operation With the New Lower Tungsten ...mentioning

confidence: 83%

“…A lower pedestal and a steeper-gradient increase inside the core plasma were observed during Ar seeding, similar to the DIII-D detached high β P scenario with both ITB and ETB, to be shown later in section 4. The strong ITB formation mechanism in DIII-D to be shown in section 4.3 and the EAST results in reference [35], suggesting that neon seeding may offer a more promising tool for favorable core-edge integration in the high β P plasma conditions in EAST, with respect to Ar seeding. In the EAST 2019 winter campaign, the compatible core-edge integration in the high β P scenario has been extended and demonstrated with H 98 > 1.2 at β P ∼ 2.5, β N ∼ 2.0, f bs ∼ 50%, f gw ∼ 0.7 at moderate q 95 ∼ 6.7 (EAST #94437) [33,34], with the peak heat flux on the divertor reduced by ∼30%, using a mixture of 50% neon and 50% D 2 seeding.…”

Section: Progress Of Active Detachment Control In East High β P Scenariomentioning

confidence: 89%

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Achievements of actively controlled divertor detachment compatible with sustained high confinement core in DIII-D and EAST

Wang

Eldon

et al. 2022

Nucl. Fusion

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The compatibility of efficient divertor detachment with high-performance core plasma is vital to the development of magnetically controlled fusion energy. The joint research on the EAST and DIII-D tokamaks demonstrates successful integration of divertor detachment with excellent core plasma confinement quality, a milestone towards solving the critical Plasma-wall-interaction (PWI) issue and core-edge integration for ITER and future reactors. In EAST, actively controlled partial detachment with Tet,div ~ 5 eV around the strike point and H98 > 1 in different H-mode scenarios including the high βP H-mode scenario have been achieved with ITER-like tungsten divertor, by optimizing the detachment access condition and performing detailed experiments for core-edge integration. For active long pulse detachment feedback control, a 30s H-mode operation with detachment-control duration being 25s has been successfully achieved in EAST. DIII-D has achieved actively controlled fully detached divertor with low plasma electron temperature (Tet,div ≤ 5 eV across the entire divertor target) and low particle flux (degree of detachment, DoD >3), simultaneously with very high core performance (βN ~3, βP >2 and H98~1.5) in the high βP scenario being developed for ITER and future reactors. The high-βP high confinement scenario is characterized by an internal transport barrier (ITB) at large radius and a weak edge transport barrier (ETB, or pedestal), which are synergistically self-organized. Both the high-βP scenario and impurity seeding facilitate divertor detachment. The detachment access leads to the reduction of ETB, which facilitates the development of an even stronger ITB at large radius in the high βP scenario. Thus, this strong large radius ITB enables the core confinement improvement during detachment. These significant joint DIII-D and EAST advances on the compatibility of high confinement core and detached divertor show a great potential for achieving a high-performance core plasma suitable for long pulse operation of fusion reactors with controllable steady-state PWIs.

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Section: Long-pulse Detachment Operation With the New Lower Tungsten ...mentioning

confidence: 83%

Section: Progress Of Active Detachment Control In East High β P Scenariomentioning

confidence: 89%

Achievements of actively controlled divertor detachment compatible with sustained high confinement core in DIII-D and EAST

Wang

Eldon

et al. 2022

Nucl. Fusion

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“…In EAST radiative divertor feedback control experiments, it is commonly observed that seeding impurity can raise the central T i [17,18]. One EAST typical high β P discharge (H 98y2 > 1.2, β P ∼ 2.5, β N ∼ 2.0, f bs ∼ 50%, n e /n GW ∼ 0.7, q 95 ∼ 6.7, I p = 400 kA, B t = 2.4 T, P LHW+EC ∼ 3.4 MW and P NBI ∼ 5.4 MW) is shown in figure 1.…”

Section: Enhanced Central T I By Neon Seedingmentioning

confidence: 99%

Mechanism of enhanced ion temperature by impurity seeding in EAST H-mode plasma

Yang,

Gong,

Qian

et al. 2023

Nucl. Fusion

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Ion temperature (Ti) profiles are commonly observed to increase in peaking, leading to higher central Ti, after impurity seeding in EAST H-mode plasma. Argon can be more efficient to raise Ti than neon. Toroidal rotation can also be enhanced in scenarios with NBI heating. More significant increased toroidal rotation is brought by seeding argon than seeding neon. Turbulence is experimentally observed to be suppressed. Extensive modelling by quasilinear gyrokinetic code QuaLiKiz is performed to explain above observations. It is found that the enhanced Ti can be always explained by the turbulence stabilization. But the mechanism of turbulence stabilization is related to heating methods and the seeding impurity species. In the pure RF (ECRH+LHW) heating scenarios, where only TEM exists, argon can stabilize TEM more significantly than neon due to its higher charge and heavier mass. In the scenarios with increasing NBI power, ion heat flux can be dominated by ITG, thus the enhanced Ti is mainly attributed to ITG stabilization. In these cases, except argon’s ability to more efficiently stabilize TEM, more evident increased toroidal rotation brought by argon seeding can be also beneficial to stabilize turbulences.

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“…During 2019 EAST campaign, a series of detachment experiments were carried out by Ne or Ar mixed with D 2 seeding from the UO-GP. [28] The effect of different magnetic configurations on plasma detachment with impurity seeding is studied by changing the B t direction. In this paper, two representative shots with different magnetic configurations are presented to show the characteristics of radiation belts during neon seeding.…”

Section: Resultsmentioning

confidence: 99%

Evolution of the high-field-side radiation belts during the neon seeding plasma discharge in EAST tokamak

Xu¹,

Wang²,

Xu³

et al. 2022

Chinese Phys. B

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Divertor detachment achieved by injecting impurities or increasing density is always accompanied with various local radiation phenomena in the boundary or core plasma. This paper presents the formation and evolution of the high-field-side (HFS) radiation belts during the neon seeding plasma discharge in upper single null configuration with two directions of toroidal magnetic field in EAST tokamak. The neon mixed with deuterium seeding can induce the divertor detachment with strong radiation belts in the HFS scrape-off layer (SOL) region. With the increase of the radiation power, the plasma discharge will transit from H-mode to L-mode, meanwhile the radiation belts move away from the near X-point to HFS SOL. When the radiation power is high enough, the radiation belts begin to move further to the other X-point along the HFS SOL, and even cause plasma disruption. The results indicate that the behavior of the radiation belts is related to the radiation power, plasma confinement performance and state of divertor detachment, which is useful for developing better feedback control methods to achieve high-performance radiative divertor operation mode.

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Comparison of divertor behavior and plasma confinement between argon and neon seeding in EAST

Cited by 30 publications

References 53 publications

Achievements of actively controlled divertor detachment compatible with sustained high confinement core in DIII-D and EAST

Achievements of actively controlled divertor detachment compatible with sustained high confinement core in DIII-D and EAST

Mechanism of enhanced ion temperature by impurity seeding in EAST H-mode plasma

Evolution of the high-field-side radiation belts during the neon seeding plasma discharge in EAST tokamak

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