Quench Protection Using CLIQ of a MgB2 0.5 T Persistent Mode Magnet

A protection system using the coupling loss induced quench (CLIQ) method has been simulated for an eight coil 0.5 T MRI main magnet designed with MgB
₂
superconducting wire. The temperature rise was modeled in MATLAB using the Douglas-Gunn method to solve the three-dimensional heat equation and Heun's method was used to solve the circuit equations associated with the CLIQ electrical circuit. The wire's twist pitch and the voltage and capacitance of the CLIQ unit can be varied to study their impact on quench protection performance. Simulations of CLIQ protection were performed on the entire 0.5 T eight coil magnet. The peak temperature varied with the wire's twist pitch. The optimal twist pitch was around 3.5 and 5.5 cm assuming the lowest and highest transverse resistivity, respectively. For the entire main magnet using CLIQ protection, the peak temperature reaches 188 K with a 10 mF capacitor at 1.3 kV.