A 4.7-T magnet with a 0.3 M bore for P-31 magnetic resonance spectroscopic imaging

A 0.3-m-bore, 4.7-T, high-homogeneity magnet, used for P-31 magnetic resonance imaging, has been constructed and installed. The magnets are comprised of a set of solenoids, which attained designed 94.8-A current (1.8 MJ) without quenching. Diodes in the cryostat resulted in a fast ramp rate of 3 T in 10 min. The field inhomogeneity for the bare magnet was -250 p.p.m./0.1 m dsv, which was finally reduced to 6 p.p.m./0.1 m dsv by shim coils. The field decay was less than 0.05 p.p.m./h. The magnet system is currently used for P-31 magnetic resonance spectroscopic imaging experiments on living animals in the laboratory. >