Updates on a W-band Gyro-BWO using a helically corrugated waveguide experiment

The experimental demonstration of a W-band gyrotron backward-wave oscillator (gyro-BWO) using both thermionic cusp electron gun and helically corrugated waveguide will be presented. The cusp gun is designed to generate an axis-encircling electron beam of 1.5 A at 40 kV with an adjustable velocity ratio of up to 3.0. The beam had a simulated axial velocity spread (Δv
_z
/v
_z
) of ~8% and alpha spread (Δ α /α) of ~10%. The beam had an averaged radius of 0.35 mm and beam thickness of 0.05 mm which is ideal to drive sub-mm wave gyro-devices under investigation. The gyro-BWO has been experimentally measured and the latest results will be presented.