Bidirectional Repeating Long Pulse Magnet System for Magnetic Refrigerator

A bidirectional repeating long pulse magnet system for room temperature magnetic refrigerator has been designed in Wuhan National High Magnetic Field Center. By using ac power capacitor bank and anti-parallel thyristors, a bidirectional magnetic field is generated and the classical crowbar is removed for maximizing the utilization of energy. For the sake of long pulse width and repeating pulse application, a special rapid cooling magnet with large inductance of 87 mH and internal cooling channels is designed. It has a 60 mm bore and 16 layers, with 7 internal cooling channels built by annular sticks between layers. Finally, the proposed bidirectional repeating long pulse magnet system with bidirectional magnetic field of + 6.2 T/ -3.8 T and pulse width of 193 ms has been successfully achieved. The design and implementation of the proposed repeating pulsed magnet system will be presented in detail in the paper.