Modeling of the effects of impurity seeding on plasma detachment and impurity screening of snowflake divertor on HL-2M tokamak by SOLPS-ITER

Zhang, Yanjie; Sang, Chaofeng; Li, Jiaxian; Zheng, Guoyao; Senichenkov, I.; Rozhansky, V.; Zhang, Chen; Wang, Yilin; Zhao, Xuele; Wang, Dezhen

doi:10.1088/1741-4326/ac8564

Cited by 5 publications

(4 citation statements)

References 69 publications

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“…However, the simulation just produces a weak second peak in the particle flux profiles, and does not show a particle flux bifurcation structure near the divertor targets. Thus, much related modeling work is still ongoing [47,48].…”

Section: Discussionmentioning

confidence: 99%

Characteristics of double-peaked particle deposition at divertor target plates in the EAST tokamak

Wang

et al. 2021

Nucl. Fusion

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Increasing the heat and particle deposition on the divertor target plates is an effective approach for reducing the extremely high heat load. Future tokamak fusion devices are expected to have a deposition width on the order of a millimeter. Recently, a double-peaked distribution (DPD) pattern of particle deposition at the divertor target plates has been observed in both deuterium and helium plasma discharges in the Experimental Advanced Superconducting Tokamak, which can significantly spread the deposition width of heat and particle fluxes, and clearly shows a toroidal symmetric distribution. It has been found that the DPD behavior occurs not only in plasma discharges with lower hybrid wave (LHW) heating, but also with electron cyclotron resonance heating or neutral beam injection (NBI) heating alone. In addition, the DPD shows an obvious in–out asymmetry between the divertor target plates, which strongly depends on the toroidal field direction, i.e. it distinctly appears on the outer divertor plate in unfavorable B t conditions, while shifting to the inner divertor plate under favorable B t conditions. Meanwhile, the transition between the single-peaked distribution and the DPD is normally correlated with the line-averaged plasma density and the auxiliary heating power. The statistical results for the pure LHW heating discharge scheme show that the DPD behavior is significantly affected by both the plasma density and the heating power, i.e. the lower the ratio of the plasma density to the heating power, the more likely it is that DPD behavior will occur. The critical boundary lines between the DPD and non-DPD patterns are obtained with the line expressions ∼ 2P LHW,abs + 1.4 and ∼ 3.33P LHW,abs + 1 for the unfavorable and favorable B t cases, respectively. Finally, the underlying physics is also discussed, suggesting that the electric field drifts and the local sheath boundary condition may exert a strong influence on the DPD.

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Section: Discussionmentioning

confidence: 99%

Characteristics of double-peaked particle deposition at divertor target plates in the EAST tokamak

Wang

et al. 2021

Nucl. Fusion

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“…Seeded impurities have a great impact on divertor plasma and thus change Γ ERO W at targets. When the impurity seeding rate is increased, radiation exhaust caused by impurities is enhanced, which can prompt the achievement of divertor detachment [10,23,24]. Drifts may trigger the movement of the radiation front and affect plasma parameters in the divertor [25,26].…”

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

confidence: 99%

“…SOLPS-ITER code suite with improved numerical solution of the drift terms and the electric potential equation has been applied to study the effect of drifts on the transport of seeded impurities [10,11]. To our best knowledge, the influence of drifts on the transport of sputtered W impurity by SOLPS-ITER still remains unsolved.…”

Section: Introductionmentioning

confidence: 99%

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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“…Experiments involving N impurity seeding in the HL-2A device revealed that the main factors contributing to divertor detachment are increased neutral pressure and volumetric energy loss [17]. Zhang et al [18]. investigated impurity seeding scenarios in the HL-2M device using SOLPS-ITER simulations and discovered that Ar and Ne impurity seeding leads to increased radiation power in the inner and outer target plate regions, effectively promoting divertor detachment.…”

Section: Introductionmentioning

confidence: 99%

Correlation between impurity radiation rollover and divertor detachment with boundary impurity seeding in HL-2A

Ye,

Tan,

Wang

et al. 2024

Phys. Scr.

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Divertor detachment has significant potential for reducing the divertor target thermal load, and impurity seeding is the primary method for achieving divertor detachment. In this study, different impurity seeding scenarios (N, Ne, and Ar) at the boundary region of HL-2A were simulated using the SOLPS-ITER code. Density scans revealed that when the divertor target electron temperature dropped below 5 eV, a rollover in impurity radiation from the core edge regions of Ar, N, and Ne occurred, and the radiation from impurities in the divertor started to increase concurrently, indicating a correlation between impurity radiation rollover and divertor detachment. Impurity radiation rollover is discovered to be primarily related to impurity transport, which is governed by thermal and friction forces.Prior to divertor detachment, the dominance of thermal forces over friction forces causes impurity ions to transport upstream. However, after detachment, friction forces dominate the impurity ions transport to the divertor region. After analyzing the density and velocity of impurity ions in different charge states, it was found that the core radiation rollover after detachment is mainly caused by high charge state impurity ions. Furthermore, the ability of the divertor to achieve particle flow rollover primarily depends on whether the decrease in plasma pressure (P t) exceeds the decrease in plasma temperature (T t 1/2).

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Modeling of the effects of impurity seeding on plasma detachment and impurity screening of snowflake divertor on HL-2M tokamak by SOLPS-ITER

Cited by 5 publications

References 69 publications

Characteristics of double-peaked particle deposition at divertor target plates in the EAST tokamak

Characteristics of double-peaked particle deposition at divertor target plates in the EAST tokamak

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

Correlation between impurity radiation rollover and divertor detachment with boundary impurity seeding in HL-2A

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