Enhancement of trapped field of REBCO bulk in a desktop-type magnet system

Abstract

We developed a desktop-type bulk magnet system using a Stirling refrigerator and used it to study how to improve the trapped field by pulsed field magnetization (PFM). Although PFM has the advantage that the bulk is activated in a few seconds using an ordinary inexpensive equipment, the amplitude of a trapped field is low as compared with the maximum performance of the material. This paper aims to improve the trapped field by changing the size of soft-iron yoke, which are generally used to extend the pulse width. When a f60-mm GdBCO bulk was magnetized using f64-mm and f80-mm yokes, the maximum flux density and total magnetic flux of large yoke were 13% and 23% higher than those of small one, respectively. Moreover, improvement of trapped field by multi PFM was investigated. When a magnetic field of 5.8 T was applied twice, the maximum trapped field of 1.46 T and the total magnetic flux of 1.86 mWb were achieved.