Thermal and magnetic responses of a solid nitrogen/magnetized YBCO disk system undergoing temperature cycles in the range of 8-60 K

In this paper we report thermal and magnetic responses of a magnetized YBCO disk cooled by a cryogenic design/operation concept that incorporates solid nitrogen in the system. The YBCO disk was "field-cooled" at 88 K and then operated in the range 8-60 K. During each cooling sequence, the system is thermally coupled to a cryocooler; then thermally decoupled from the cryocooler at 8 K and left decoupled until it reaches 60 K. As an application of this cryogenic design/operation concept, we describe a 0.5-T/80 cm bore magnet wound with MgB/sub 2/ presently being developed at FBML.