Excitation Test of YBCO Tape at 45 K With Through-Wall Linear-Motor Type Flux Pump

The linear-motor type flux pump is a wireless direct current (DC) power supply that facilitates contactless excitation of high-temperature superconducting (HTS) magnets, thereby obviating the requirement for current leads. This feature significantly reduces heat leakage and operating costs of cryogenic systems. In this investigation, we present the successful through-wall excitation of HTS magnets using the linear-motor type flux pump. The dissipative elements of the flux pump are positioned external to the Dewar wall, thereby imposing no thermal burden on the cryogenic system while wirelessly exciting the HTS magnet enclosed within the Dewar. Experimental trials were carried out with the HTS stator cooled to 45 K and the HTS coil cooled to 30 K, demonstrating that the flux pump can deliver a peak current of 237 A with two YBCO tapes connected in parallel. Additionally, observations confirmed that below 77 K, when a traveling magnetic wave is DC-biased over the zero-axis, it results in maximum output current from the flux pump as predicted by theoretical models based on macroscopic magnetic coupling effects. This successful through-wall excitation experiment validates potential industrial applications of flux pumps for powering HTS magnets.