Impact of error field and error field correction on heat fluxes in SPARC*

Using a single toroidal array of coils to reduce the m,n=2,1 resonant error field produced by the misalignment of the axisymmetric coils in SPARC can result in the enhancement of the local divertor heat fluxes by an order of magnitude. Managing high divertor heat fluxes (q_// ~ 10GW/m²) poses a challenge for tokamak devices like SPARC. The presence of non-axisymmetric magnetic field perturbations adds complexity to the problem by generating intricate 3D edge magnetic topologies that alter the heat flux distributions on the target plates. In this study we utilize the MHD code M3DC1 to simulate the 3D magnetic perturbations generated by the shift and tilt of several axisymmetric coils within specified tolerances, as well as from error field correction coils, in SPARC. Employing a 3D heat flux layer model, we computed the resultant heat flux distributions, derived from magnetic footprints calculated with the MAFOT code. Our findings highlight that the utilization of the error field correction coils located at the midplane can: 1) lead to heat deposition in non-preferred regions; 2) further enhance the local heat fluxes when used to correct the m/n=2/1 resonant error field to improve core plasma performance. The impact on the 3D geometry of the divertor region will also be shown.