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

The compact torus injection (CTI) technology utilizes the electromagnetic force to inject the 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 working under high current condition with microsecond pulse width. This paper presents a solid-state solution to improve the repetition performance and energy efficiency of microseconds pulsed power supplies for CTI systems based on high-current thyristors (GTO-like) and the active energy recovery technology. The structural, forward and reverse blocking characteristics of the GTO-like thyristor were analyzed. Then the topology was designed for both measuring the blocking recovery characteristics of devices and enhancing the efficiency of the pulsed power supplies system. The prototype experimental results show that 8 Hz repetitive operation with 112 kA peak current was achieved at 5.5 kV, the maximum energy recovery rate reached 31.1%, which is 6.8 percentage points higher than that of the traditional energy recovery topology.