Persistent Current Switches for Control of the 1.5 T MRI Magnetic System

The currently achieved level of technology development around the world makes it possible to construct superconducting (SC) magnetic systems with a helium-free cooling system that does not require replenishing it with liquid helium throughout the entire service life. A magnetic resonance imaging (MRI) with a 1.5 T magnetic system that operates in vacuum under helium-free cooling conditions is being developed in Russia. The article presents the design of a superconducting switch, commonly known as a persistent current switch (PCS), for controlling the MRI magnetic system during current input/output. The PCS operates, like the entire magnetic system, under helium-free cooling conditions. To optimize the PCS design and study its unsteady operating modes, a numerical model based on the finite element method has been developed, which solves the unsteady heat conduction equation. Two PCS operating modes are considered: standard current input or output and fast current output. The PCS winding temperature variations during its operation is presented. The mechanical stresses arising in the cooled PCS predicted by the finite element method are presented. The PCS experimental samples that meet the technical requirements for the 1.5 T MRI magnetic system are presented.