Design and manufacturing of superconducting magnets for magnetic resonance imaging system

We design and manufacture 1.5T and 3T superconducting magnets for the magnetic resonance imaging (MRI). We have realized the helium zero boil-off. For the region of leakage magnetic field (5 gauss line), we have successfully developed a uniform design and have secured compatibility for magnets with different center magnetic fields (for 1.5T and 3T). The magnetic field stability is one order higher than the currently available specifications thanks to the use of the optimal superconducting joint technique. This in turn helps extend the time constant of magnetic field decay to over a century. The typical ultimate magnetic field homogeneity is 1 - 6 ppm/50 cm DSV (diameter spherical volume). The magnetic field homogeneity may be raised one order higher in the region of 40 cm DSV. The magnets we realized are the quench-less magnet that never experiences quenching after reaching the rating. (author)