94-GHz 25-kW CW low-voltage harmonic gyrotron

A low-voltage second-harmonic gyrotron intended as a compact lightweight source has been designed and evaluated with a particle-tracing code and the particle-in-cell code MAGIC. The two codes are shown to be in good agreement when applied to a conventional fundamental-frequency gyrotron and also to the novel second-harmonic gyrotron. The 25-kW continuous wave (CW) 94-GHz gyrotron with a predicted conversion efficiency of 32% and device efficiency of 22.5% is driven by a 25-kV 4.5-A (/spl upsi//sub /spl perp////spl upsi//sub 2/=1.5, /spl Delta//spl upsi//sub z///spl upsi//sub z/=7%) electron beam from a magnetron injection gun and employs a low-loss TE/sub 021//TE/sub 031/ complex cavity for mode control. Although the 17-kG CW gyrotron will use a cryogen-free high-T/sub c/ superconducting magnet, a 94-GHz prototype will be tested at low duty with a conventional low-T/sub c/ superconducting magnet.