New developments in relativistic klystron amplifiers

A relativistic klystron amplifier that employed cavities with inductively loaded wide gaps and a novel converter has achieved 50% energy efficiency, a significant advance over the previous state of the art of 20%. The new device was immersed in a 3 kG magnetic field and contained two innovations: (1) Wide gaps which include an inductively loaded return current structure that was opaque to the unmodulated beam space charge but transparent to the RF field. (2) A novel converter that was made of a “leaky” cavity with a radially-converging inductively-loaded structure that was inserted in the output wide-gap. This structure reduced the potential energy residing in the electron beam and maximized RF output energy.