High-power microwave production by gyroharmonic conversion and co-generation

Abstract

An rf accelerator that adds significant gyration energy to a relativistic electron beam, and mechanisms for extracting coherent radiation from the beam, are described. The accelerator is a cyclotron autoresonance accelerator (CARA), underlying theory and experimental tests of which are reviewed. The measurements illustrate the utility of CARA in preparing beams for high harmonic gyro interactions. Examples of preparation of gyrating axis-encircling beams of ∼400 kV, 25 A with 1<a<2 using a 2.856 GHz CARA are discussed. Generation of MW-level harmonic power emanating from a beam prepared in CARA into an output cavity structure is predicted by theory. First measurements of intense superradiant 2nd through 6th harmonic emission from a CARA beam are described. Gyroharmonic conversion (GHC) at MW power levels into an appropriate resonator can be anticipated, in view of the results described here. Another radiation mechanism, closely related to GHC, is also described. This mechanism, dubbed “co-generation,” is ...