The transport of tungsten impurities induced by the intrinsic carbon during upper-single null discharge on EAST tokamak

Zhou, Qingrui; Sang, Chaofeng; Xu, Guoliang; Ding, Rui; Zhao, Xuele; Wang, Yilin; Wang, Dezhen

doi:10.1016/j.nme.2020.100849

Cited by 8 publications

(6 citation statements)

References 34 publications

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“…If the cross-field diffusion coefficient, which is now unknown for CFETR, is greater than 0.3 m 2 s −1 , the divertor plasma in the high-recycling regime (the peak electron temperature of ∼15 eV) is adequate to screen the tungsten impurity sputtered from the divertor target. It is in line with our previous study [24] and the recent simulation results on EAST tokamak [50].…”

Section: Pure Diffusion Casesupporting

confidence: 93%

Simulation study of the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer

Xu¹,

Xu²,

Mao³

et al. 2021

Plasma Phys. Control. Fusion

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It is critical to keep a low level of tungsten impurity concentration in the core plasma of the fusion reactor. Using the OEDGE code, the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer is studied. Based on the design parameters of the China Fusion Engineering Test Reactor, the background plasma with the peak target electron temperature of 15 eV is generated using the onion-skin model. The neon impurity with the assumed concentration of 0.2% inside the separatrix is included for estimating the tungsten sputtering source. In a series of simulations of tungsten transport, the diffusion coefficient D ⊥ is varied from 0.1 to 10 m 2 s −1 , and the hypothetical inward pinch velocity V IMP is in the range of 0-5 m s −1 . The tungsten concentration inside the separatrix increases with decreasing diffusion coefficient and exceeds 10 −5 for the diffusion coefficient lower than about 0.2 m 2 s −1 . When the hypothetical inward pinch is included, the tungsten concentration increases. The relation between the relative increase in tungsten concentration and V IMP /D ⊥ is fitted.

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Section: Pure Diffusion Casesupporting

confidence: 93%

Simulation study of the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer

Xu¹,

Xu²,

Mao³

et al. 2021

Plasma Phys. Control. Fusion

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“…With the calculated W source and plasma background provided by SOLPS modeling, the transport of W impurity is simulated by DIVIMP code [50], which uses the Monte Carlo method to track particles and their charge states in the plasma. The details of the SOLPS-DIVIMP coupling for EAST W divertor can be found in the recent work [51].…”

Section: Simulation Modelmentioning

confidence: 99%

Design of EAST lower divertor by considering target erosion and tungsten ion transport during the external impurity seeding

Sang

Zhou

et al. 2021

Nucl. Fusion

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To demonstrate the performance of tungsten (W) as the divertor target material and to solve the power handling problem during high power long-pulse discharge, the upgrade of EAST lower divertor is planned. In this work, the physical design of the W divertor is presented by using 2D edge plasma code SOLPS and Monte Carlo impurity transport code DIVIMP. The optimized divertor geometry is proposed after systematic examination of target shapes, target slant angles and the pump opening locations. The performance of the designed divertor is further assessed by impurity seeding. By comparing the medium and high power discharges with argon (Ar) seeding, the differences on the divertor power radiation and impurity core accumulation are distinguished. The simulated effective ion charge Z eff fits well the scaling law, which is based on multi-machine database. Ar seeding and neon (Ne) seeding scans are carried out separately. The simulation results indicate Ar has higher power radiation efficiency than that of Ne, thus promoting the achievement of plasma detachment. However, the core compatibility with Ar is worse than with Ne. The W target erosion and W impurity transport during impurity seeding are simulated by the DIVIMP–SOLPS coupled modeling. It illustrates that under the similar divertor plasma conditions, Ar seeding causes more serious W erosion and more severe core contamination by W impurity, than Ne seeding. Finally, the divertor in–out asymmetry is studied by considering electromagnetic drifts. The simulation results manifest that the designed open vertical inner target reduces in–out asymmetry due to that its weak power radiation capability is offset by the ion flow driven by the drifts. In addition, the designed divertor is compatible with the quasi snowflake magnetic configuration. These studies will improve the understanding of W target sputtering and W impurity transport control during the radiative divertor discharges for CFETR/DEMO.

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“…However, the transport of the eroded W impurity has not been included in that model. The W erosion and impurity transport on DIII-D, JET and EAST has been simulated by OEDGE [21], DIVIMP [22], EDGE2D/ERIENE-DIVIMP [23,24] and SOLPS-DIVIMP [25]. However, these works have not considered the impact of W impurity on the background plasma, i.e.…”

Section: Introductionmentioning

confidence: 99%

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

Wang¹,

Sang²,

Zhang³

et al. 2021

Plasma Phys. Control. Fusion

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The upgrade of experimental advanced superconducting tokamak lower divertor to use tungsten (W) target is undertaken, however the target erosion and W impurity accumulation in the core pose a great challenge during high power discharge with external impurity seeding. This paper aims to study the influence of argon (Ar) seeding on the target erosion and the W impurity transport on steady-state operation. The scrape-off layer/divertor plasma as well as W impurity are self-consistently simulated by using SOLPS-ITER code package. With the constant input power, the Ar seeding rate is varied to study the changes on divertor plasma, incident Ar flux, the target erosion and W impurity transport. The simulation results indicate that the external Ar impurity influences W target erosion through both reducing the plasma temperature and introducing heavier incident particles, which significantly complicates the erosion process. The eroded W flux has great impact on the W core accumulation, and the divertor plasma condition influences W impurity transport remarkably. A correlation between peak electron temperature (T e ) at the outer target and the W concentration (C W ) at the core-edge-interface is found. Moreover, the influence of the W impurity on the background boundary plasma is also evaluated.

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The transport of tungsten impurities induced by the intrinsic carbon during upper-single null discharge on EAST tokamak

Cited by 8 publications

References 34 publications

Simulation study of the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer

Simulation study of the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer

Design of EAST lower divertor by considering target erosion and tungsten ion transport during the external impurity seeding

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

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