Waveform Control Pulse Magnetization for HTS Bulk With Flux Jump

Abstract

We improved the performance of single pulse magnetization in order to trap high magnetic field to many bulks in the high-temperature superconducting (HTS) synchronous motor with less number of times. In the proposed waveform control pulse magnetization (WCPM) method, a single pulse magnetic field may effectively magnetize the HTS bulk. In this study, we magnetized Gd–Ba–Cu–O HTS bulk by the WCPM at 77 K using the split-type copper coils without a core. Increasing the predetermined duty ratio in WCPM from 40% to 45%, HTS bulk caused flux jump by pulse field magnetization (PFM), and trapped magnetic flux density greatly increased. WCPM with 50% duty ratio allowed to reach a trapped magnetic flux density 150% higher than the conventional PFM. We always observed flux jumps over 1.7 T for this bulk while using PFM. When we attempted WCPM with the magnetic flux density slightly higher than the observed flux jump as control target for suppressing, the HTS bulk trapped a high magnetic flux density comparable to the field cooling method, only by applying a single-pulsed magnetic field. This bulk successfully trapped high magnetic flux density difficult to realize with the conventional single PFM with low energy loss from the WCPM through feedback control. By finely using flux jump well in PFM, it was shown that the HTS bulk can trap high magnetic field.