Simulation of tungsten target erosion and tungsten impurity transport during argon seeding on EAST

Wang, Yilin; Sang, Chaofeng; Zhang, Chen; Zhao, Xuele; Zhang, Yanjie; Jia, Guozhi; Senichenkov, I.; Wang, Liang; Zhou, Qingrui; Wang, Dezhen

doi:10.1088/1361-6587/ac0351

Cited by 12 publications

(11 citation statements)

References 52 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: 90%

“…As shown in figure 1, two cryo-pumps are set behind the baffle and the recycling coefficient at the pump duct is assumed to be R = 0.9, and the impurity gas is injected near the outer strike point (OSP). These are consistent with our previous work [3]. The input power entering the core-edge interface (CEI, r − r sep = −5.1 cm at outer-mid plane) is set to P CEI = 4 MW, equally divided between electrons and ions.…”

Section: Simulation Setupsupporting

confidence: 75%

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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: 90%

Section: Simulation Setupsupporting

confidence: 75%

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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“…Previous studies for ITER show that the core W concentration should be kept under the level of 10 −5 , otherwise the burning plasma condition cannot be achieved [4]. Operation in detachment conditions can effectively reduce the divertor W erosion rate [5][6][7], and thus, future fusion tokamaks will be operated in partial-detached or fully-detached regimes to meet the lifetime requirement of the divertor. In this context, understanding and assessing the key physical mechanisms governing the W leakage from the divertor to the core plasma for different degrees of detachment are essential.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Xu²,

Ding³

et al. 2022

Nucl. Fusion

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Tungsten (W) transport and screening in the edge plasma are investigated for EAST high dissipative divertor conditions. By combining the one-dimensional impurity fluid model (1DImpFM) and the two-point model formatting (2PMF), 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. Based on dedicated EAST density ramp-up experiments, two-dimensional simulations of W erosion and transport are carried out for different levels of dissipative divertor conditions by using the SOLPS-DIVIMP code package, and the modeling results are benchmarked with the 1DImpFM analytic model. The prompt-redeposition, the divertor screening, and the main SOL screening are quantitatively analyzed. For detached divertor conditions, the increase of the W ionization length reduces the prompt redeposition rate, but both the divertor screening and SOL screening are reinforced. The 1DImpFM can well interpret the W leakage in the near separatrix region; however, the 2D simulations suggest that the impurity pressure gradient force which is neglected by the 1DImpFM plays an important role, especially in the far-SOL region. With the divertor condition varied from the high-recycling regime to the deep detachment regime, the W source moves from the near strike point region to the far SOL, and thus makes the W transport in the far SOL more important. Therefore, the impurity pressure gradient force cannot be neglected for edge W transport analysis, especially for the detached divertor conditions.

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“…not self-consistently) using a simple Roth-Bohdansky formula based on computed electron and ion temperature profiles and impinging ion fluxes profiles. Note that no W redeposition and no W transport are considered in this simple approach-accounting for these effects would require self-consistent inclusion of W ions and neutrals into the model (as, for example, in [55]), which requires more computing power and longer time to reach the steady-state solution.…”

Section: Estimates Of W Erosionmentioning

confidence: 99%

SOLPS-ITER modeling of CFETR advanced divertor with Ar and Ne seeding

Senichenkov¹,

Ding²,

Molchanov³

et al. 2022

Nucl. Fusion

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The Chinese Fusion Engineering Testing Reactor (CFETR) is a project proposed by Chinese fusion community to bridge the gap between ITER and commercial fusion power plant with the fusion power up to 1 GW. The mitigation of divertor target heat fluxes for such a powerful machine is a challenging problem, which might appear to be more severe than in ITER. In the present paper the results of CFETR advanced divertor optimization by SOLPS-ITER modeling with full drifts and currents activated are presented. Three divertor geometries, which differ by the distance from X-point to the strike point on the outer target, are considered. Argon (Ar) and neon (Ne) are compared as seeded impurities. It is demonstrated that for all three geometries and for both radiators it is possible to achieve acceptable divertor heat loads (below 5 MW/m2) without notable fuel dilution (Zeff < 2.5). Impurity compression in divertors and pedestal radiation are compared for two gases. Similar core plasma and divertor conditions, as well as radiated power fraction, may be achieved with 2-3 times less Ar seeding rate than the Ne one. Estimated radiation from the confined region appears to be small compared to the exhaust power. However, in all modeling cases the T_e at the far Scrape-Off Layer (SOL) part of both targets remains significantly above 5 eV, which might cause tungsten sputtering. Further optimization of targets shape will be performed to reduce the electron and ion temperature.

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Simulation of tungsten target erosion and tungsten impurity transport during argon seeding on EAST

Cited by 12 publications

References 52 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

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

SOLPS-ITER modeling of CFETR advanced divertor with Ar and Ne seeding

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