Compact 12.5 MW, 55 kV solid state modulator

This paper describes the development of a very compact solid state, actively switched MOSFET modulator system, capable of switching 55 kV at 250 A, with pulse widths up to 6 /spl mu/s, at a duty cycle of 0.1%. The modulator, which measures only 12''/spl times/12''/spl times/40'' (0.3 m/spl times/0.3 m/spl times/1 m), is combined with a specially developed capacitor recharging DC supply and integrated control unit to form a system capable of driving high peak power, pulse magnetrons (up to 5 MW of peak RF output), for radar and linear accelerator applications. The novel mechanical realisation, the design concept and key features of the modulator are discussed. The paper describes the overall system performance in the context of significant potential for the improvement of tube lifetimes and concludes with a brief outline of future enhancements and developments to the modulator.