Improvement of thermal stability with alloy impregnation in Gd-Ba-Cu-O superconductors for pulsed field magnetization

We present a post-fabrication treatment that improves thermal conductivity of bulk Gd-Ba-Cu-O magnets. A small hole about 1 mm in diameter was artificially drilled into the centre of bulk Gd-Ba-Cu-O 25 mm in diameter and 18 mm in thickness. An aluminium wire was inserted into the hole, and then the sample was subjected to the impregnation by using Bi- Su-Cd alloy. A pulsed-field magnetization was performed for Gd-Ba-Cu-O bulk with and without the alloy impregnation treatment. The temperature of samples was monitored with thermocouples and local magnetic field density was measured with a Hall sensor at several positions. The maximum temperature rise was depressed by 4 K and the trapped field was increased by 25 % at 44 K. The result shows that the alloy impregnation is very effective in enhancing the thermal conductivity and thereby improving the field trapping ability.