Pulsed Field Magnetization of Large MgB2 Bulk Fabricated by Reactive Liquid Mg Infiltration

Pulsed field magnetization (PFM) was performed for the first time on a large MgB2 bulk 50mm diameter fabricated by a reactive liquid Mg infiltration (Mg-RLI) method, and the time dependence of the local field B-L(C)(t) and the trapped field profiles were measured. The trapped field of B-z = 0.47 T and the total trapped flux of Phi = 0.50mWb were achieved at T-s = 23 K and both values decreased with increasing temperature T-s. The experimental results can be qualitatively reproduced by numerical simulation using electromagnetic and thermal fields for PFM. The flux dynamics and the heat generation/propagation in the MgB2 bulk during PFM were in clear contrast with those in REBaCuO superconducting bulks because of the large thermal conductivity, small specific heat, and narrow temperature margin against the transition temperature T-c. (C) 2012 The Japan Society of Applied Physics