Objective Aiming at the special requirements of compressed magnetic field waveforms for field-reversed configuration (FRC) nuclear fusion devices, conventional single-stage capacitor energy storage power supplies cannot generate the required inflection characteristics on the current rising edge, and fail to meet the two-stage magnetic field regulation requirements of FRC devices. Specifically, a high current change rate (di/dt) is required in the initial stage to increase plasma temperature and density, and a gentle current rise is needed in the subsequent stage to stably maintain the field-reversed configuration. Therefore, a magnetic compression power supply topology based on two-stage pulsed capacitor discharge is proposed.

Method A cooperative discharge topology with differentiated primary and secondary parameters of two-stage pulsed capacitors was designed, and diode isolation technology was adopted to realize staged circuit triggering, so as to construct precisely controllable segmented current change rate (di/dt) characteristics on the current rising edge. The operating mechanisms of two magnetic compression power supply circuit topologies, namely thyristor-internal and thyristor-external configurations, were analyzed. The time-domain analytical expressions of voltage and current in each stage of circuit discharge and freewheeling were derived, and the effectiveness of the theoretical model was verified by MATLAB simulation.

Result The research results show that the magnetic compression power supply adopting two-stage pulsed capacitor structure can effectively extend the discharge duration and stably maintain the plasma field-reversed configuration. The discharge current waveform can be flexibly regulated by adjusting the parameters of two-stage pulsed capacitors. In addition, the thyristor-external topology can significantly suppress the current tailing phenomenon, reduce the current tailing time, and provide a reliable discharge path for capacitor reverse voltage.

Conclusion The proposed magnetic compression power supply scheme based on two-stage pulsed capacitor discharge can provide flexible compressed magnetic field waveform regulation capability for magnetic confinement nuclear fusion devices. It can effectively extend the fusion reaction time and improve the neutron yield, and achieve an excellent balance between long-pulse discharge performance and system miniaturization and compactness. The scheme has important engineering application value in FRC fusion neutron source devices.