A 50-MHz Multi-kV Power Amplifier for Ion-Beam Accelerator Utilizing an Optimized Toroidal Inductor

This paper presents the design and implementation of a 50-MHz multi-kV switch-mode power amplifier suitable for propelling ion beams in compact particle accelerators. Ions are accelerated by passing them through a series of plate-pairs driven by large high-frequency ac voltages. High frequency operation allows the overall length of the accelerator to be reduced. The presented power amplifier generates high voltages at high frequencies by utilizing a single switch resonant inverter with a high-quality-factor air-core toroidal inductor. The presence of a single switch facilitates high frequency operation by eliminating the need for complicated gate drive techniques. An analytical method for the design of high-frequency toroidal inductors is also introduced that maximizes the inductor quality factor and enables generation of high voltages without excessive loss. The inductor built using the proposed optimization method is shown to achieve a quality factor of 595, which is in good agreement with the theoretical prediction. A 50-MHz prototype power amplifier designed using the proposed technique is demonstrated to achieve up to 5 kV output voltage.