Investigation on the transformer-rectifier flux pump for high field magnets

Due to the improvement in the manufacturing of the superconductor, the superconducting magnets have been widely used in the areas such as magnetic resonance imaging (MRI), particle accelerators, and magnetic levitation systems. The transformer-rectifier flux pump is an effective method to energize the superconducting magnets. However, in the real system of the flux pump, some undesired dc current will be inevitably generated in the flux pumping system during the process of energizing the superconducting magnets. The undesired dc current will have many negative impacts such as slowing down the charging process, decreasing the final field of the superconducting magnets, and resulting in the failure of the whole system. This paper will focus on the origin of the undesired dc current in the flux pump, investigate the damage that the undesired dc current causes, and propose an effective method of removing the undesired dc current. The proposed method has greatly improved the performance of the flux pump. An experimental system is built and tests are carried out to verify the practicality and validity of the proposed method