Jeffrey Oleski with Michael Martens and David Doll
Persistent Switch Design for MgB2 Superconducting Magnet
High quality MRI imaging requires that the main magnetic field remain temporally stable to within 0.1 ppm per hour, which is achieved by operating the main superconducting magnet in persistent current mode. After a power supply ramps the magnets to full current, persistent switches are used to isolate the power supply and operate the magnet in persistent current mode. Persistent switch designs exist for the NiTi magnets used in present-day MRI scanners, but we propose to design a persistent switch for use in conduction-cooled MgB2 superconductor MRI magnets. Design considerations include: constraints on the resistance of the switch in the normal and superconducting state; strain sensitivity of the MgB2; conduction cooling of the switch; heater elements to change the temperature of the switch; and connections with persistent joints.