Performance Projections For SPARC*

SPARC, the fourth in the series of compact high-field tokamaks at MIT will be a D-T burning experiment based on emerging HTS magnet technology. The projected SPARC performance, using a pre-conceptual design point, rests on conservative plasma physics – essentially the ITER baseline scenario. In terms of dimensionless plasma parameters, SPARC is closer to the database median than ITER. In fact, a number of shots exist in the ITER confinement database that simultaneously match all of the plasma and geometric dimensionless parameters, increasing confidence in the projections. Under the baseline assumptions for confinement and access to H-mode, SPARC would achieve Q ~ 3.6 and generate up to 100 MW of fusion power. Using different confinement assumptions, we find that SPARC has robust access to Q > 2 even at H₉₈ of 0.9, that is, one standard deviation below the scaling mean.  It would reach Q = 1 in L-mode (H₈₉ = 1) and Q ~ 2.6 in a modestly improved L-mode (H₈₉ = 1.4). There is a long tail on its high end performance, with Q = 5 in reach with H₉₈ of 1.1 (one standard deviation above the scaling mean) and perhaps higher in I-mode.  Advanced operation with hybrid modes or ITBs could be explored in this device, but are not required for the mission.