Self-consistent integrated modeling for the Q≥1 steady-state mission of the Burning Experimental Superconducting Tokamak (BEST)

Following two different approaches, fully non-inductive scenarios have been developed aiming at a Q≥1 steady-state goal for the Burning Experimental Superconducting Tokamak (BEST), a new superconducting tokamak under design in ASIPP, China. One striking feature of BEST is the long-pulse D-T operation capability with metal wall and tungsten divertor. To meet the Q≥1 steady-state goal for BEST, fully non-inductive scenarios are designed using the self-consistent STEP physics module running under the OMFIT integrated modeling framework. Two different approaches were pursued: high density, bootstrap current dominated (high-β_P approach) and low density, external driven current dominated (reversed shear approach). In the high-β_P regime, several operational points are explored at I_p~4 MA, β_N~2.4 and f_Gr (Greenwald fraction) ranging from 0.8 to 1.2. ITBs at large radius (ρ=0.75) are predicted in these cases. Pellet-like external particle source at ρ~0.6 is important for establishing such ITB in density. The reversed shear approach is more challenging, due to limited NBCD capability and LHW accessibility at high pedestal temperature. An operational point close to the goal is found at I_p~5 MA, β_N~2.0 and f_Gr~0.3. Work supported by GA ASIPP BEST Project under 22KH000044US.