Efficiency enhancement of a klystron-like relativistic backward wave oscillator with local decompression magnetic field

A klystron-like relativistic backward wave oscillator (RBWO) with a local decompression magnetic field is presented. There is a local non-uniform magnetic field near the extractor. As the electron beam travels through the RBWO, it will transport upwards and approach the extractor wall, then move downwards, and enter a coaxial collector. Owing to a higher kinetic energy of the electron beam which can be converted into microwave energy efficiently and a stronger electric field that can interact with the electron beam during the beam decompression in the extractor, the efficiency of the klystron-like RBWO is significantly increased to about 65%, compared to 55% with the conventional magnetic field.