Design and Improvement of Quench Protection for A 3 T MRI Superconducting Magnet

Abstract

In recent years, global investment in magnetic resonance imaging (MRI) has surged, with 3 T MRI technology overtaking 1.5 T as the standard in hospitals gradually. A combination of linear programming, genetic algorithms, and nonlinear programming was employed to design an actively shielded 3 T superconducting MRI magnet system. This magnet consists of seven main coils and two shielding coils, achieving a magnetic field with a peak-to-peak inhomogeneity of 10 ppm within a 50-cm-diameter spherical volume (DSV). To address the risk of quench in superconducting magnets, which can lead to damage due to excessive temperature, voltage, and stress, a quench protection system is crucial. The designed system segments the coils for protection, using diode pairs and shunt resistors to manage the quench. Initial simulations indicated that temperature rises and voltages were within safe limits, but some coils were slow to quench or did not quench at all, risking burnout. To mitigate this, quench propagation heating plates were added to increase the quench speed. Updated simulations showed rapid quench across all coils and a significant reduction in hot spot temperatures and peak voltages.