A half-wave superconducting transformer-rectifier flux pump using J c(B) switches

Abstract

High temperature superconducting (HTS) flux pumps can generate ultra-high currents (>1 kA) without the requirement for thermally inefficient room temperature current leads. Ultra-high currents enable physically smaller magnets with significantly less inductance unlocking new design opportunities. However, limited by intrinsically low electrical power efficiencies, existing HTS flux pumps cannot output high voltage or high power. In this work, we design, devise, and experimentally verify a transformer–rectifier type HTS flux pump using Jc(B) switching. We show that the rectification can be achieved by exploiting the HTS E-J relation with the application of DC magnetic fields. A quasi-persistent current of 54.5 A has been achieved at 77 K only limited by the load coil critical current. In addition, the electrical power efficiencies of both half-wave and full-wave flux pump are derived. We illustrate that the fundamental J c(B) mechanism provides significantly higher efficiency than existing HTS flux pumps. This advancement will overthrow the common knowledge that HTS flux pumps could only be used for maintaining rather than fast ramping magnetic fields.