K. H. Im, B.J. Lee, J.H. Han, J. Kim and KSTAR Design Team
Korea Basic Science Institute, 52 Yeoeun-Dong, Yusung-ku, Taejon, 305-333, KOREA
D. N. Hill
Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551, USA
B. Braams
Courant Institute, CIMS-NYU, 251 Mercer St., New York, NY 10012, USA
For the design of KSTAR (Korea Superconducting Tokamak Advanced Research) divertor, the analyses of edge plasma and neutral core recycling have been carried out with UEDGE, B2.5 and DEGAS.
UEDGE 2-D multi-fluid edge plasma transport code has been used to determine heat and particle fluxes and plasma temperatures at the 45o tilted divertor plate with pumping effects. Two cases of operation (1) reference (bN=3.5, li =0.8) and (2) high-b low-li (bN=5, li =0.4) have been analyzed. Also effect of impurity radiation is taken into account for carbon concentration up to 4% (Zeff ~ 2) near separatrix. The requirements of 3.5 MW/m2 peak heat flux and average and peak tile temperatures of <600oC and <1200oC, respectively, should be met for the initial heating power of 15.5 MW. The gaseous and radiative divertor modeling will be carried out to accommodate the upgraded heating power (³30 MW) and long pulse (300 s) operations.
B2.5 code has been also executed to find suitable KSTAR divertor leg length by varying divertor channel width and depth along with the variation of temperature and density of core plasmas. The results from UEDGE and B2.5 codes will be compared.
The analysis on core fueling of recycled neutrals has done with Monte-carlo neutral transport code DEGAS. Various baffle configurations including variation of gap distance and baffle shapes are simulated and eventually optimized to minimize the core fueling and to meet the requirement for limitation of core fueling.