Fast capacitor charging is a power electronics application with unique challenges requiring both low voltage, high current operation and high voltage, low current operation from the same system at different points in the charge cycle. Such dynamically differing operating points create distinct challenges in obtaining high efficiency throughout a charge cycle. In addition, the power supply must be protected from negative voltage swings when attached to a high rep-rate power modulator. This paper presents the design and testing of a rapid capacitor charger designed for high rep-rate command charging of a Marx generator. The output stage uses a large inductor to delay discontinuous conduction during the early portion of the charge cycle and greatly improve efficiency. The design goals and tradeoffs will be discussed and simulation results will be compared to experimental data.