Backward wave oscillator for high power generation at THz frequencies

The progress in microfabrication techniques and three dimensional electromagnetic simulations have enabled the fabrication of vacuum electron devices up to 1 THz. In particular, the backward wave oscillator is a compact and powerful THz vacuum source, based on the transfer of energy from an electron beam to an electromagnetic (EM) wave propagating in a slow wave structure. The paper reports the design and fabrication challenges to realize a near-THz Backward Wave Oscillator for plasma diagnostics in nuclear fusion. In particular, the beam optics and confinement as well as the slow wave structure are described. Manufacturing as well as device implementation and demonstration considerations are discussed. The double corrugated waveguide is used with a cylindrical electron beam producing an output power on the order of 1 W.