Trapped Field Enhancement of a Thin, High-Jc MgB2 Bulk Without Flux Jumps Using Pulsed Field Magnetization With a Split-Type Coil With a Soft Iron Yoke
We have investigated the suppression of flux jumps and the enhancement of trapped field on a thin, high-Jc MgB2 bulk (30 mm in diameter and 7 mm in thickness) for the pulsed field magnetization (PFM) using a split-type coil with a soft iron yoke, and compared the results to those magnetized using the split-type coil without a yoke and a solenoid-type coil with a yoke. A maximum-trapped field, Bz, of 0.71 T at 14 K was achieved on the bulk surface without flux jumps by using the split coil with yoke. On the other hand, low Bz values with flux jumps were observed for the cases using the split-type coil without a soft iron yoke, and the solenoid-type coil with a yoke. These results reproduce previous ones for a thick, high-Jc MgB2 bulk (22 mm in diameter and 15 mm in thickness), for which the trapped field was enhanced to a record high value of Bz = 1.10 T at 13 K by PFM using the split-type coil with a yoke.