Development of a superconducting transformer for high current conductor testing

Abstract

Critical current (Ic) tests on superconducting conductors require currents on the order of tens of kilo-amperes in combination with sub-microvolt resolution voltage measurements. Instead of traditional expensive DC power supply and complicated current leads, a superconducting transformer has been developed to feed the test sample with current up to 30 kA. The transformer consists of two concentric layer-wound superconducting solenoids with the primary coil inside the secondary. In order to reduce the influence by stray field of background magnet and transformer, a hall array with two hall sensors symmetrically distributed around the secondary conductor is used to achieve accurate secondary current measurement. This paper describes the design and manufacturing of transformer, including accurate secondary current measurement method. The first test results are also presented. The superconducting transformer system enables fast, high resolution, economic and safe tests of high current conductors.