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

Nuclear Fushion

article

Yilin Wang¹  Chaofeng Sang¹  Xuele Zhao¹  Yihan Wu¹  Qingrui Zhou¹  Yanjie Zhang¹  Dezhen Wang¹ 

[1] Key Laboratory of Materials Modification by Laser, Ion and Electron Beams ,(Ministry of Education), School of Physics, Dalian University of Technology

关键词: tungsten divertor;    neon seeding;    target erosion;    impurity transport;    drifts;   

DOI  :  10.1088/1741-4326/aceb09

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Mitigating tungsten (W) wall erosion and core accumulation are vitally important for 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 ofE× Bdrift. The objective is to establish the relationship between the eroded W flux, W transport and the corresponding accumulation in the core in different discharge regimes. The effects of drift on W sputtering at targets and W impurity distribution in the cases of different toroidal magnetic field ( B _t) directions are assessed. The simulation results indicate that drift could influence W transport via W impurity retention and redistribution in the divertor, and the leakage from the divertor. In forwardB _t ( B×∇ Bpoints to theX -point), eroded W flux at the outer target is increased remarkably, and most of the W ions transport from the outer to the inner divertor and escape to the upstream region in the high field side. W ions mainly transport from the inner to the outer divertor and escape from the divertor in the low field side in reversedB _t due to the opposite drift flux. The Ne puffing rate is scanned in forwardB _t and without-drift cases to further investigate the W erosion and W impurity transport in different divertor regimes. It is found that the W source from targets is generally enhanced by drift compared to cases without drift. The core accumulation, as well as poloidal asymmetry, is also influenced significantly by the drift. In the attached regime, the 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 consequently decline. Therefore, adequate Ne impurity seeding can be applied to control the W accumulation in the core.

【 授权许可】

Unknown