To address issues of low output voltage ripple, low ignition energy, rapid shutdown, and to reduce the risk of high-voltage ignition damaging high-frequency switching devices in neutral beam injection systems, this paper proposes a modular inverter-type power supply design. A 120 kV/80 A high-power modular inverter is developed. It incorporates 84 high-frequency inverter modules (1600 V/80 A each) in a staggered-phase cascade. Transformer isolation of each module safeguards switching devices during ignition, and 20 kHz staggered phase control minimizes filter capacitor requirements while maintaining voltage ripple within specifications. Performance tests on the prototype show a rise time of 67 μs, turn-off time of 3.3 μs, ignition energy release of 1.3 J, and voltage ripple of 3.3%, with the ripple reduced to less than 1% after interleaving. The results demonstrate that the design achieves low voltage ripple, fast shutdown, and controlled energy release, confirming its feasibility