Modelling of tungsten impurity edge transport and screening for different divertor conditions in EAST

Wang, Hui; Xu, Guoliang; Ding, Rui; Liu, Xiaoju; Si, H.; Zhang, Qing; Ding, Fang; Zhu, Dahuan; Yan, Rong; Xie, Hai; Meng, Lingyi; Wang, Liang; Hai, Ran; Wang, Zhibin; Chen, Junling

doi:10.1088/1741-4326/ac8fa4

Cited by 9 publications

(8 citation statements)

References 47 publications

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“…This is due to the fact that inadequate seeded impurities can give rise to larger Γ ERO W depending on the competition between lower T e and increased incident Ne ion flux [4], which is in accordance with the measurement of sputtered W flux during the Ne seeding experiment on EAST [29]. However, larger Γ ERO W does not necessarily raise C CEI W (figures 12(a) and (c)) since the divertor regime also plays an important role in W accumulation in the core, which was demonstrated by our previous work [3] and DIVIMP simulations on EAST [22].…”

Section: Influence Of Ne Puffing Rate On W Transport and Accumulation...supporting

confidence: 88%

The influence of E× B drift on tungsten target erosion and W impurity transport during neon seeding on EAST

et al. 2023

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Mitigating tungsten (W) wall erosion and core accumulation is vitally important to the steady-state operation of tokamaks. It is well known that drifts have a great impact on the transport of charged particles in the edge region, which could affect W source and W impurity transport. In this work, SOLPS-ITER modeling is applied to study the W impurity behavior on EAST during neon seeding with the consideration of E×B drift. The objective is to find out the relationship between the eroded W flux, W transport and corresponding accumulation in core in different discharge regimes. The effect of drift on W sputtering at targets and W impurity distribution in the cases of different toroidal magnetic field (Bt) directions is assessed. The simulation results indicate that drift could influence W transport via W impurity retention and redistribution in divertor, and the leakage from divertor. In forward Bt (B×∇B points to the X-point), eroded W flux at outer target is increased remarkably, and most of the W ions transport from outer to inner divertor and escape to upstream region in high field side. While W ions mainly transport from inner to outer divertor and escape from divertor in low field side in reversed Bt due to the opposite drift flux. Ne puffing rate is scanned in forward Bt and without drift cases to further investigate the W erosion and W impurity transport in different divertor regimes. It is found that W source from targets is generally enhanced by drift compared to the without drift cases. The core accumulation as well as poloidal asymmetry is also influenced significantly by the drift. In attached regime, intense W source and strong drift flux lead to enhanced W accumulation in the core, and obvious poloidal asymmetry of W density distribution appears. The drift flux is reduced, and W erosion is suppressed after detachment. W concentration in the core and poloidal asymmetry declines consequently. Therefore, adequate Ne impurity seeding can be applied to control the W accumulation in the core.

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Section: Influence Of Ne Puffing Rate On W Transport and Accumulation...supporting

confidence: 88%

The influence of E× B drift on tungsten target erosion and W impurity transport during neon seeding on EAST

et al. 2023

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“…Therefore, the far-SOL unreversed poloidal drift dominates and helps to enhance the divertor W screening. Note that for the same D 2 puff rate, cases with OSP on the horizontal target exhibit a higher upstream electron density than cases with OSP on the vertical target, and a higher upstream electron density is also favorable for W screening [15].…”

Section: Discussionmentioning

confidence: 97%

“…Due to the divertor in-out asymmetry caused by the ⃗ E × ⃗ B drifts, the inner divertor region has a higher average n e and a lower average T i than that in the outer divertor region. As discussed in [15], the ion temperature gradient velocity v TiG ∝ T i 3/2 /n e , so v TiG in the inner divertor region is relatively smaller, and thus the parallel ⃗ E × ⃗ B drift has a greater impact on the W transport. The ratio of the W leakage rate with drifts to that without drifts.…”

Section: The Low-recycling Regimementioning

confidence: 97%

Drifts effect on the divertor W leakage mechanisms under different dissipative divertor conditions of EAST

Wang,

Xu,

Ding

et al. 2024

Nucl. Fusion

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A new drift module has been developed in the DIVIMP code, enabling two-dimensional simulations of tungsten (W) transport in the edge plasma with full drifts included. By using the SOLPS-DIVIMP code package, the impact of drifts on W transport and screening has been investigated for various levels of dissipative divertor conditions and different divertor geometric configurations in EAST. Simulation results reveal that E ⃗×B ⃗ drifts can enhance the W leakage by more than one order of magnitude. Under the favorable Bt direction, W erosion mainly occurs on the outer divertor target, making the W leakage from the outer divertor region the dominator. A leakage path from the near-SOL region is revealed by the modeling results. In the leakage path, both the ion temperature gradient force and the reversed poloidal E ⃗×B ⃗ drift are pointing upstream. With the radial E ⃗×B ⃗ drift pushing W ions from the well-screened far-SOL region to the near-SOL region, the leakage from the near-SOL region becomes significant. As the divertor condition varies from the low-recycling regime to the deep detachment regime, the decrease of the ion temperature gradient velocity and poloidal E ⃗×B ⃗ drift velocity narrows the width of the near-SOL leakage tunnel and thus enhances W screening. While under the unfavorable Bt, W erosion and leakage from the inner divertor target matters, the leakage mechanism especially the leakage path from the near-SOL region is similar as the favorable Bt cases. Furthermore, the effect of different divertor geometries on the W screening has been investigated. The configuration with the outer strike point (OSP) on the horizontal divertor plate is proved to narrow the near-SOL leakage tunnel, and thus the unreversed poloidal E ⃗×B ⃗ drift pointing to the divertor target dominates and helps to enhance the divertor W screening. For the same D2 puffing rate, the W leakage ability of cases with the OSP on the horizontal target can be more than 10 times weaker than the cases with the OSP on the vertical target, especially when the divertor is detached.

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“…By combining the 0D theoretical analysis and 2D simulations of W erosion and transport carried out by using the SOLPS-DIVIMP, W screening is proved to be enhanced for high upstream plasma density conditions, mainly because the impurity temperature gradient velocity decreases with the increase of the upstream plasma density. Moreover, 2D simulations suggest that the impurity pressure gradient force cannot be neglected for edge W transport analysis, especially for the detached divertor conditions [51].…”

Section: Edge Physicsmentioning

confidence: 99%

Summary of the 10th Conference on Magnetically Confined Fusion Theory and Simulation (CMCFTS)

Wang

Qiu

Wang

et al. 2023

Plasma Sci. Technol.

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This paper gives a summary of the organization and the presentations delivered at the 10th Conference on Magnetically Confined Fusion Theory and Simulation (CMCFTS) held in Zhuhai, China, from 28th to 31st October 2022. The conference focused on the latest progress in the research of the magnetic confined fusion plasma theory and simulations, as well as the large-scale numerical simulation techniques developed in recent years. This conference is held both online and offline, with about 110 domestic participants from 18 institutes participating in the live conference, and the statistical data from the live broadcast platform indicated that the online conference attracted over 20000 views per day. A summary of the conference is given, and the history of the CMCFTS is presented. A brief introduction to the poster section is also included in this paper.

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Modelling of tungsten impurity edge transport and screening for different divertor conditions in EAST

Cited by 9 publications

References 47 publications

The influence of E× B drift on tungsten target erosion and W impurity transport during neon seeding on EAST

The influence of E× B drift on tungsten target erosion and W impurity transport during neon seeding on EAST

Drifts effect on the divertor W leakage mechanisms under different dissipative divertor conditions of EAST

Summary of the 10th Conference on Magnetically Confined Fusion Theory and Simulation (CMCFTS)

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