  The potential formation of multi-mega-ampere beams of relativistic "runaway"
electrons (REs) during sudden terminations of tokamak plasmas poses a
significant challenge to the tokamak's development as a fusion energy source.
Here, we use state-of-the-art modeling of disruption magnetohydrodynamics
coupled with a self-consistent evolution of RE generation and transport to show
that a non-axisymmetric in-vessel coil will passively prevent RE beam formation
during disruptions in the SPARC tokamak, a compact, high-field, high-current
device capable of achieving a fusion gain Q > 2 in deuterium-tritium plasmas.
