Quench Protection Design of a Head-Only 1.5 T MRI Superconducting Magnet

This article presents a quench protection design of a head-only 1.5 T MRI superconducting magnet with bath-cooling in Wuhan National High Magnetic Field Center (WHMFC). The magnet consists of nine coaxial solenoid coils fabricated with NbTi wire with a copper to non-copper ratio of eight. It operates at around 510 A with a total storage energy of 0.59 MJ. A passive quench protection circuit with a heater network is employed to protect the magnet from damage during the quench event. The quench protection circuit consists of a set of diodes and a heater network. The diode assembly is composed of two groups of two diodes connected in series and then reverse-parallel. The heater network is composed of 18 heaters connected in parallel and each coil's surface is glued with two heaters arranged at 0° and 180°, respectively. Different quench scenarios are simulated and analyzed, and the simulation results show that the quench protection circuit can effectively protect this magnet from damage.