Development of an active energy-recovery scheme for repetitive compact-torus-injection pulsed-power supplies

Compact torus injection (CTI) technology utilizes electromagnetic force to inject compact torus (CT) plasma as a fuel carrier into the core of a nuclear fusion reactor. However, the performance of a CTI system is constrained by its pulsed power supplies, which operate under high current conditions with a microsecond pulse width. This paper presents a solid-state solution that improves the repetition performance and energy efficiency of microsecond pulsed power supplies for CTI systems based on high-current thyristors with gate turn-off (GTO)-like characteristics and active energy-recovery technology. The structural, forward, and reverse blocking characteristics of the GTO-like thyristor are analyzed. Then, a topology is designed for both measuring the blocking recovery characteristics of devices and enhancing the efficiency of the pulsed power supply system. The prototype experimental results show that repetitive operation at 8 Hz with a peak current of 112 kA is achieved at 5.5 kV. The maximum energy-recovery rate reaches 31.1%, which is 6.8 percentage points higher than the energy-recovery rate achieved by the traditional energy-recovery topology.