Optimization of the snowflake divertor for power and particle exhaust on NSTX-U

被引:10
作者
Vail, P. J. [1 ]
Izacard, O. [1 ]
Kolemen, E. [1 ]
机构
[1] Princeton Univ, Dept Mech & Aerosp Engn, Princeton, NJ 08544 USA
基金
美国能源部;
关键词
NSTX-U; snowflake divertor; cryopump; UEDGE; DIII-D; TRANSPORT;
D O I
10.1016/j.nme.2019.03.003
中图分类号
TL [原子能技术]; O571 [原子核物理学];
学科分类号
0827 ; 082701 ;
摘要
In this paper, simple analytical modeling and numerical simulations performed with the multi-fluid edge transport code UEDGE are used to identify optimal snowflake divertor (SFD) configurations for heat flux mitigation and sufficient cryopumping performance on the National Spherical Torus eXperiment Upgrade (NSTX-U). A model is presented that describes the partitioning of sheath-limited SOL power and particle exhaust in the SFD as a result of diffusive transport to multiple activated strike points. The model is validated against UEDGE predictions and used to analyze a database of 70 SFD-minus equilibria. The optimal location for the entrance to a divertor cryopumping system on NSTX-U is computed for enabling sufficient pumping performance with acceptable power loading in a variety of SFD-minus configurations. UEDGE simulations of one promising equilibrium from the database indicate that a significant redistribution of power to the divertor legs occurs as a result of neutral particle removal near one of the SFD-minus strike points in the outboard scrape-off layer. It is concluded that pump placement at the optimal location is advantageous as the large number of compatible equilibria reduces the precision required of real-time SFD configuration control systems and enables acceptable divertor solutions even if UEDGE-predicted power redistribution slightly reduces the achievable pumping performance.
引用
收藏
页码:516 / 523
页数:8
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