Systematic analysis of the quench process performance and simulation of the 9.4 T-800 mm whole-body MRI magnet

Abstract

In 2021, the Institute of Electrical Engineering, Chinese Academy of Sciences successfully reached 9.4T in a whole-body magnetic resonance imaging (MRI) superconducting magnet with an inner diameter of 800 mm. In this study, a systematic analysis of both the real quench protection performance and a simulation are reported. The four successful quench protections during the entire energization process proved the feasibility of the “in-out-in” quench protection protocol for a 9.4T-800 mm superconducting magnet. The quench trigger sequence was shown to be adjusted by changing the heater thickness, which demonstrates the flexibility of the “in-out-in” quench protection protocol to fit a different MRI magnet design. The high accuracy of the quench protection simulation method and code was confirmed through comparison of the simulation results with the real performance. Moreover, the limitations of the current quench protection and reference value to other MRI magnets were discussed. It is believed that this study will be useful to other research groups and promote the development of an extremely high-field whole-body MRI system.

Quench analysis of a no-insulation REBCO magnet based on the ADI method considering the coupling effect of the cryostat

“…The unbalanced force originates from the asymmetry nature of the quench propagation process in the NI magnet. To be specific, unlike insulated magnets such as MRI magnets, where the azimuthal currents of all turns in one certain subcoil decay simultaneously and the transient currents with temporalspatial quench trigger sequence of diffferent subcoils can be controlled through dump-resistor and heater circuit [59,60], the quench in the NI magnet occurs along the SP coils in sequence through electromagnetic coupling effect and the azimuthal current in each pancake also rises and decays successively. This unique asymmetry feature determines that the spatial distribution of the magnetic field around the NI magnet during quench is not symmetric about the midplane of the magnet and so is the eddy current in the cryostat.…”