Square-Wave-Fed Cockcroft-Walton Voltage Multipliers for Enhanced Design Flexibility in Ionic Propulsion

The development of high-power-density high-voltage DC/DC power electronic circuits plays a crucial role in ionic propulsion’s potential employment. Traditional Cockcroft-Walton voltage multipliers (VMs) are typically fed by sinusoidal voltages delivered by a resonant converter coupled with a high-voltage step-up transformer. This paper presents a complete analytical modeling of square-wave-fed VMs. Closed-form expressions for output voltage ripple and drop, and power losses are derived, revealing a fundamentally different charge-transfer mechanism and reduced ripple compared to conventional sinusoidal operation. By decoupling the VM from a resonant magnetic interface, the proposed framework provides an additional degree of freedom in the design of the front-end power stage and enables flexible frequency modulation and advanced control strategies that are not accessible in resonant architectures. The feasibility of this approach has been numerically and experimentally tested, including scaled-down validation and full-scale high-voltage feasibility tests up to nearly 7 kV, confirming the predicted scalability. Furthermore, the proposed VM is directly employed to drive a wire-to-plane ionic thruster, demonstrating stable operation and practical applicability.