<scp>Influence</scp> of the drifts on the double‐peaked emission profile of the visible light in the upper divertor region of <scp>EAST</scp>

Guo, Jin; Lu, Zhiyuan; Jia, Guozhi; Ruan, Xinglei; Xu, Yuchen; Mao, Shaohua; Yang, Jianhua; Wang, Yumin; Meng, Lingyi; Yang, Qingquan; Xu, G. S.; Ye, Minyou

doi:10.1002/ctpp.202100181

Cited by 5 publications

(3 citation statements)

References 38 publications

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“…SOLPS-ITER has been widely applied to simulate the divertor and boundary plasma in many tokamaks [29,30]. It has been recognized as an effective tool for simulating the effects of drifts [10,[31][32][33]. While the effects of drifts are considered important in forming the double-peaked profiles, SOLPS-ITER is employed in this work.…”

Section: Simulation Setupsmentioning

confidence: 99%

Simulation study of the influence of upstream density and power in the scrape-off layer on the double-peaked density profile at the divertor target

Guo¹,

Mao²,

Jia³

et al. 2022

Nucl. Fusion

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The double-peaked distribution of particle deposition at the divertor targets has been observed in various tokamaks, and is considered as a potential approach for mitigating the divertor particle and heat load in future fusion reactor. Recently, the systematical analysis of the double-peaked distribution behavior during EAST experiments show that, the appearance of the double-peaked profile is related to the line-average density and heating power. In order to understand the general trends and related mechanisms, the influences of the upstream density (ne,sep) and power into scrape-off layer (PSOL) on the double-peaked density profile are investigated by SOLPS-ITER simulations with full drifts and currents. It is found that, the ne peak near the strike point is mainly contributed by the strong ionization source close to the target, and the ne peak in far-SOL region is caused by the synergetic effects of poloidal and radial E×B drifts along the SOL. The double-peaked distribution is affected by the PSOL and impurity seeding by increasing or decrease the whole profile of the electron temperature at the target (Tet). When the peak value of Tet (Tet,peak) is fixed, the density peak in the far-SOL is increased for higher ne,sep, by reducing the Tet in the far-SOL region on the lower-field side under unfavorable BT, and by the upstream-extended ionization source due to the geometry effect on the high-field side under favorable BT. Statistical analysis of the simulated results shows that the scaling expression of the peak ratio is ~Tet,peak -(1.4~2.1) ne,sep 1.6~1.8. In addition to upper boundary found in the analysis of EAST experiment, a lower boundary of the region where double-peaked feature appears on the PSOL-ne,sep plane is identified by simulations and preliminarily confirmed according to the measurements in several EAST discharges.

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Section: Simulation Setupsmentioning

confidence: 99%

Simulation study of the influence of upstream density and power in the scrape-off layer on the double-peaked density profile at the divertor target

Guo¹,

Mao²,

Jia³

et al. 2022

Nucl. Fusion

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“…B2.5 (a multi-fluid code for plasma transport calculation) and EIRENE (a Monte-Carlo code for neutral transport calculation) [55], and widely applied to many tokamaks to study the divertor physics and boundary plasma transport [8,10,39,[56][57][58][59][60][61][62][63][64][65][66][67][68][69]. The latest version SOLPS-ITER introduces advanced models for the drift effect and neutral transport [70] and has been recognized as an effective tool for studying the effect of drift on the SOL plasma [42,43,45]. Complete W species can be included in the SOLPS-ITER; however, the simulation is too time-consuming [71].…”

Section: Simulation Schemementioning

confidence: 99%

“…In recent years, it was found that the E × B drift has significant effects on the SOL plasma by changing the in-out asymmetry [35,36], degree of detachment [37][38][39], characteristics of the target profile [40][41][42], distribution of low-Z radiation impurity [43][44][45], etc. Since the velocity of impurity ion caused by parallel forces is inversely proportional to the mass of impurity ion, the effect of E × B drift on high-Z impurity is expected to be more pronounced than that on low-Z impurity, especially in the divertor region, where the pitch angle is small [46].…”

Section: Introductionmentioning

confidence: 99%

Simulation study of the influence of E× B drift on tungsten impurity transport in the scrape-off layer

Guo,

Xu,

Mao

et al. 2023

Nucl. Fusion

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Future fusion reactors such as ITER have adopted tungsten (W) as the plasma-facing materials (PFMs) in the divertor region. It is crucial to keep the W concentration in the core plasma at an extremely low level. Great efforts have been put forward on understanding the W transport in the scrape-off layer (SOL), which is related to the source of the core W contamination. In this work, the influence of E×B drift on the W impurity transport in the SOL is studied by numerical simulations for a model case based on EAST upper single-null configuration with high recycling divertor plasma. The W transport is simulated using DIVIMP on the background plasma obtained from SOLPS-ITER simulation including drifts. The E×B drift of the W ions is introduced according to the background electric field. Therefore, both the direct E×B drift effect of W ion itself and the indirect effect via background plasma on the W transport process in the SOL can be studied. We focus on the influence on the flux of W impurities entering confined plasma across the last closed flux surface Γenter, which is expected to be proportional to the core W concentration. It is found that Γenter is mainly from the outer (inner) target under favorable (unfavorable) toroidal field BT, and can be increased by more than one order of magnitude compared with the case without drifts. It reflects the significant influence of E×B drift effects. The detailed effects due to the background plasma and the poloidal and radial E×B drift of W ion, as well as the related mechanisms, are analyzed for the three stages of W transport in the SOL, including the effective sputtering from the target, the leakage from the divertor and the entry into the confined plasma.

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Simulation study of the influence of the cross‐field anomalous diffusion on the tungsten impurity transport in the scrape‐off layer with activated drifts

Guo,

Xu,

Mao

et al. 2024

Contrib. Plasma Phys

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Tungsten (W) impurity eroded from the divertor target can degrade the confinement performance of future fusion reactors. The mechanism of the effect of E × B drift on the W transport in the scrape‐off layer (SOL) was investigated with a fixed cross‐field anomalous particle diffusion coefficient for W ions (D⊥,W) of 1 m2s−1 in our previous simulation work, which indicates that the W flux entering the confined region (Γenter) and mean W concentration in the confined region () can be increased by more than one order of magnitude by drifts. In this work, the influence of the cross‐field anomalous diffusion on the W transport in the SOL is further investigated. The basic flow pattern of the W ion flux (ΓW) keeps when D⊥,W varying from 0.5 to 3 m2s−1, and Γenter mainly comes from the hotter divertor region. Results show that D⊥,W value affects the W leakage from divertor region and entry into confined region. Therefore, Γenter and both decrease with increasing D⊥,W. Mechanisms for cases w/wo drifts are compared.

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Influence of the drifts on the double‐peaked emission profile of the visible light in the upper divertor region of EAST

Cited by 5 publications

References 38 publications

Simulation study of the influence of upstream density and power in the scrape-off layer on the double-peaked density profile at the divertor target

Simulation study of the influence of upstream density and power in the scrape-off layer on the double-peaked density profile at the divertor target

Simulation study of the influence of E× B drift on tungsten impurity transport in the scrape-off layer

Simulation study of the influence of the cross‐field anomalous diffusion on the tungsten impurity transport in the scrape‐off layer with activated drifts

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