Abstract
Abstract The snowflake divertor is a proposed technique for coping with the tokamak power exhaust problem in next-step experiments and eventually reactors, where extreme power fluxes to material surfaces represent a leading technological and physics challenge. In lithium-conditioned National Spherical Torus Experiment (NSTX) discharges, application of the snowflake divertor typically induced partial outer divertor detachment and severalfold heat flux reduction. UEDGE is used to analyze and compare conventional and snowflake divertor configurations in NSTX. Matching experimental upstream profiles and divertor measurements in the snowflake requires target recycling of 0.97 vs. 0.91 in the conventional case, implying partial saturation of the lithium-based pumping mechanism. Density scans are performed to analyze the mechanisms that facilitate detachment in the snowflake, revealing that increased divertor volume provides most of the parallel heat flux reduction. Also, neutral gas power loss is magnified by the increased wetted area in the snowflake, and plays a key role in generating volumetric recombination.
| Original language | English (US) |
|---|---|
| Article number | 48865 |
| Pages (from-to) | 1200-1204 |
| Number of pages | 5 |
| Journal | Journal of Nuclear Materials |
| Volume | 463 |
| DOIs | |
| State | Published - Jul 22 2015 |
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- General Materials Science
- Nuclear Energy and Engineering