A COMPACT 0.8T SUPERCONDUCTING MRI MAGNET

A compact, cryogen-free 0.8T superconducting MRI magnet has been wound using Nb3Sn tape conductor and is maintained at 8K using a two-stage Gifford-McMahon refrigerator. The magnet is housed in a low eddy-curre nt cryostat which incorporates a fiberglass-reinforced epoxy (FRE) vac uum enclosure with an integral stainless-steel permeation barrier, a c omposite copper/fiberglass thermal shield heat stationed to the first stage of the cryocooler, and a FRE magnet support structure heat stati oned to the second stage of the cryocooler. The low eddy-current compo nents eliminate the need to shield the gradient coils. The magnet comp onents and the measured performance characteristics of the system are described in detail.