2006 年 41 巻 9 号 p. 390-396
The time evolutions and three-dimensional temperature profiles in a cryocooled superconducting bulk disk have been investigated using a finite element method (FEM) after applying pulse field magnetization (PFM). The bulk is either cooled down along the ab-plane through the brass support component and magnetized using a split-type coil, or cooled along the c-axis and magnetized using a solenoid coil. The temperature rise ΔT due to the magnetic flux intrusion in the case of the “ab-plane cooled type” is experimentally small and the trapped field BTP is enhanced as compared to the “c-axis cooled type”. The calculated temperatures T'(t) can effectively reproduce the measured T(t) with an appropriate assumption of the heating area and total generated heat Q. The heating area is wider and the Q value is relatively smaller in the “ab-plane cooled type” as compared to the “c-axis cooled type”. These analytical results suggest that, in the “ab-plane cooled type”, cooling along the high thermal-conductive direction in the bulk magnet and the increase in total heat capacity due to close contact of the bulk magnet and the brass support component are effective for reducing ΔT and enhancing BTP.