Temperature Dependent Performance of a Conduction-Cooled Jc(B) Transformer- Rectifier Flux Pump

Abstract

Transformer-rectifier flux pumps provide an elegant solution for high current generation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&gt;$</tex-math></inline-formula> 1 kA) in superconducting magnets. By using step-down transformers and superconducting switches they can charge magnets with minimal heat-load between the external and cryogenic components. High temperature superconductors' type-II superconductivity enables a range of different switching approaches. It was recently shown that a switching approach based on reducing the critical current with an applied DC magnetic field - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J_c(B)</i> switching - is feasible. The efficiencies of this switching method are an attractive option for a conduction-cooled system where cooling power is limited. In this work we present the first conduction-cooled transformer-rectifier driven by <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J_c(B)</i> switching where we successfully charge a magnet up to its critical current of 115 A whilst monitoring various component temperatures. We explore the parameter space of applied current and switch temperature to establish the effects on the charging time and maximum current.