10.4: Experimental demonstration of a W-band gyro-BWO using a helically corrugated waveguide

The experimental demonstration of a W-band gyro-BWO using both thermionic cusp electron gun and helically corrugated waveguide will be presented. A cusp gun uses a non-adiabatic magnetic field reversal to obtain azimuthal motion on an electron beam resulting in an annular shaped, axis-encircling beam. The cusp gun was designed to generate a beam of 1.5A at 40kV with an adjustable velocity ratio of up to 3.0. The beam had a simulated axial velocity spread of ~8% and alpha spread of ~10%. The beam had an averaged radius of 0.35mm and beam thickness of 0.05mm which is ideal to drive sub-mm wave gyro-devices under investigation. The gyro-BWO has been constructed and designed to produce pulsed millimeter wave output radiation in the frequency range 84GHz to 104GHz.