Design and fabrication of solid nitrogen cooled MgB2 based persistent magnet for MRI application

Physicians and surgeons rely critically on magnetic resonance imaging (MRI) scans to diagnose and treat critical injuries and medical conditions. In an MRI system, high, stable (\u3c0.1 ppm h-1), and uniform (≤10 ppm in 50 cm diameter of spherical volume) magnetic fields are required for obtaining high-resolution images of the human body. The unique possibilities for the operation of superconducting magnets (i.e., persistent-mode) make them ideal for MRI application. Thus, in the majority of commercially available MRI systems, superconducting persistent magnets based on niobium titanium (NbTi) have been used. These magnets, which are cooled in an expensive liquid helium (LHe) bath at 4.2 K, cannot currently be avoided. Thus, the high operation costs of MRI systems obstruct their extensive use in developing and underdeveloped countries

Cryogenic acceptance tests of SST-1 superconducting coils

Toroidal field (TF) and poloidal field (PF) coils of steady-state superconducting tokamak (SST-1) have been fully refurbished to ensure cryostable and low-dc-resistance interpancake and intercoil joints, helium leak tightness of the winding pack, and \u3e 10 MΩ winding pack to ground insulation resistance under cold conditions. As per SST-1 mission mandate, all TF coils and PF3 Top had been cold tested at full operational parameters. A dedicated large coil test facility was integrated for these tests. Specially adapted solutions such as magnet preparation cum transport stand, demountable busbar supports, demountable sensor mountings, reusable joints for busbar connections inside cryostat, etc., were developed. These measures led to timely and successful completion of cold tests and integration of the magnet system on to the SST-1 machine shell. The functionality of various diagnostics of the magnet system was also established during these tests. Details of coil refurbishment, test facility, test campaigns, and some important test results are reported in this paper