Experimental Investigation of Bridge Quench in an HTS Flux Pump Operating at 77 K

Transformer–rectifier flux pumps offer an effective and contactless means to supply current to high-temperature superconducting (HTS) magnets, significantly reducing thermal losses associated with conventional current leads. They have demonstrated high-current capability and the ability to sustain target currents and magnetic fields over extended periods by compensating for inherent flux dissipation, showing promise for compact, cryogen-free superconducting systems. However, while liquid nitrogen are well studied, the stability of conduction-cooled systems remains insufficiently investigated. This paper presents an experimental study on the bridge quench behavior of a conduction-cooled half-wave transformer–rectifier HTS flux pump. By varying the amplitude and frequency of the applied AC magnetic field, the relationship between dynamic losses, bridge temperature rise, and quench initiation was analyzed. The results reveal that excessive field amplitude leads to localized resistive transition and voltage spikes, which suppress flux pumping efficiency and introduce current ripple. Comparisons with LN2cooling confirm that inadequate heat removal is the dominant factor limiting system stability.