Design and simulation of a 7.0 T conduction cooled superconducting magnet

A Conduction cooled superconducting magnet (SM) for human magnetic resonance imaging, made of Nb₃Sn superconducting coils, has been designed. The magnet features a warm bore with a diameter of 850 mm and a central field strength of 7 T. The size and positioning of a bundle of seven epoxy-impregnated coils were determined using both linear and nonlinear optimization methods. These methods ensured that the superconducting coils achieved a magnetic field uniformity of 10 ppm within a 400 mm diameter spherical volume (DSV). The magnet was designed to operate at a current of 250 A in a cryogenic system, and its temperature will be maintained below 8 K through conduction cooling provided by a Gifford-McMahon (G-M) cryocooler at its second-stage cooling capacity. The SM and its cryogenic system were designed according to a comprehensive analysis of the mechanical and thermal features of the magnet system. The design was evaluated and validated by Finite Elements simulations. The results confirmed that the magnet is capable of stable and reliable operation at low temperatures, effectively achieving conduction cooling.