The nuclear bombs would be very small, 10-100 tons microfusion yield if feasible. So the magsail would be maybe 5 km diameter, spin-stabilized. The bombs would have a polyethylene casing to absorb most of the fast neutrons and gamma rays, becoming a cloud of ionized plasma. The gas released by the magsail would be ionized as well, perhaps by an RF waveguide, to create an extremely large polarized magnetic field, much larger than the magsail itself. The high energy plasma from the bomb would push against the magnetic field, in turn pushing the magsail. The energy imparted from the explosion would stretch the tethers a certain amount, and the elastic tension would be translated into a thrust force as viewed from the payload (unmanned). The payload would have a debris shield, and be magnetically shielded as well.