AN OPEN REFRIGERATOR COOLED SUPERCONDUCTING MAGNET FOR THE SPECIAL-PURPOSE OF MAGNETIC-RESONANCE-IMAGING

A 10K refrigerator cooled superconducting magnet with an open-ended, C -shaped iron core was developed and tested for the special purpose of magnetic resonance imaging, The magnet employs a single Nb3Sn tape sup erconducting coil and an open-ended Iron loop. The superconducting coi l is cooled and maintained at the 10K operational temperature by a Gif ford-McMahon(G-M) cryocooler. The magnetic field In the iron open gap Is used for magnetic resonance Imaging. The field homogeneity is achie ved by contoured iron pole faces and specially developed passive shimm ing procedures, We have achieved less than 1ppm/hour field stability a nd a 29ppm field homogeneity over a 10 cm diameter spherical volume. H igh quality images have been produced using this magnet.