Research and Development for Upgrading a Cryogen-Free 18 T Superconducting Magnet

We have studied for upgrading an 18 T super-conducting magnet conductively cooled by a GM/JT cryocooler at Tohoku University in Japan to a 23 T superconducting magnet. In order to upgrade the cryogen-free high field superconducting magnet up to 23 T, an
${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}({\rm Y}123)$
coated conductor insert is intended for replacing the insert using
${\rm Bi}_{2}{\rm Sr}_{2}{\rm Ca}_{2}{\rm Cu}_{3}{\rm O}_{10}({\rm Bi}2223)$
tape with stainless steel reinforcement tape. We have produced double pancake coils with almost the same size as a double pancake coil for the Bi2223 insert, and have investigated the performance of the coils. And the design of the double pancake coil was reviewed from the result of the R&D coils.