The importance of core fueling for the Q ≥ 5 inductive mission for the Burning Experimental Superconducting Tokamak (BEST)

Self-consistent integrated modeling using STEP in OMFIT has shown that for the inductive scenario in BEST the fusion gain Q ≥ 5 mission can be achieved using moderately sized D-T fueling pellets. BEST, a new superconducting tokamak, is currently under design by ASIPP in China with 0D parameters R₀=3.6 [m], a=1.1 [m], B_T0=6.15 [T], P_aux=41 [MW], including 10 [MW] NBI, 15 [MW] ICRF, 10 [MW] LHW and 6 [MW] ECH. The baseline standard H-mode operation scenario will be operating at I_p of 7.3 [MA], Z_effective of 2 and f_gw~ 0.9 at the pedestal. For this scenario, the integrated modeling predicts a fusion performance of Q = 1.5, with a promising path to better performance by using core fueling pellets. To predict the density source of the pellets, the flexible Pellet Ablation Module (PAM) has been used. PAM has been previously validated on DIII-D experiments¹. The injection angle, position, size, and velocity are constrained by engineering limitations. Therefore, pellets of 2mm - 4.5mm in radius, injected from the low field side at velocities of 1.5 km/s – 3.0 km/s were evaluated in the STEP workflow. The resulting fusion gain 1.5 < Q < 5.9 increases with pellet size and velocity as the deposition depth 0.3 < ρ_dep < 0.7 and density peaking 1.6 < ne₀/ne_ped < 2.8 increases at the same ne_ped.