Abstract: The space plasma environment research facility (SPERF) is used to simulate the space magnetic field and plasma environment on earth. To generate a pulse current across the 3.5 μH, 0.8 mΩ toroidal field (TF) coils, a modularized capacitor-based pulsed power supply (PPS) was built. The rise time of the pulse current was approximately 130 μs, and the peak current was 260 kA. To avoid damage to the PPS when the coil load was short-circuited, the circuit parameters of the PPS, such as the number of modules, the inductance of the protection inductor, were calculated based on current waveform requirements and the maximum ratings of the thyristor switch. Since the inductance of the coil load was relatively small, the output cable was used as both the transmission line and the protection inductor, and a 4-module PPS was designed and fabricated. Simulation results indicate that the 4-module PPS design meets the demand of both the current waveform and the maximum ratings of the thyristor switch, and the discharge test further proves the output current waveform of the PPS agrees with the simulation results.