High-Temperature Superconducting (HTS) magnets offer a novel pathway to magnetically confined fusion energy generation. Reactor-scale fusion devices require tens of kA of current to generate large toroidal fields for magnetic confinement. Operating HTS magnets at kA-current levels is difficult due to unavoidable joint resistances that require active driving of current. The large footprint and energy demand of a solid-state power supply and multi-kA current leads present significant constraints on the size, cost and efficiency of a fusion tokamak. An alternative approach is to use an HTS Flux Pump, which can generate and sustain persistent currents in HTS coils at the kA-levels required by fusion magnet systems. Here, we outline the design of a 60 kA transformer-rectifier flux pump for energizing and sustaining an 80 mH HTS fusion magnet. The flux pump is driven by an iron-core transformer with copper primary and HTS secondary windings. This is rectified by switching elements in the superconducting circuit into a dc voltage output which charges the inductive load. To charge the load coil to 60 kA in 24 hours, an output dc voltage of 55 mV is needed. However, only 6 mV is required to maintain a long-term steady current of 60 kA. Such a device can significantly reduce the cost and footprint of future fusion reactor designs.

Keywords: Tokamak, Fusion, HTS Flux Pump, Efficiency