W-band Gyro-BWO using a helically corrugated waveguide

Presented in this paper is the design of a W-Band Gyro-BWO with a helically corrugated waveguide and a cusp electron gun. The interaction region has been constructed with good accuracy and microwave results measured using a vector network analyzer are given. The microwave dispersion agrees well with analytical and numerical theory. The transmission loss of this helically corrugated waveguide was measured to be ∼1dB over the frequency range (84 – 104GHz). A cusp electron gun has been designed to generate a 1.5A, 40kV electron beam with an adjustable pitch angle (α) of up to 3. The beam was optimized through numerical simulation with an axial velocity spread, ΔV
z
/V
z
, of 7% and Δα/α, of 10.4% at α=1.65. From simulation of the beam-wave interaction the maximum output power from the Gyro-BWO was predicted to be 10kW (CW) at 17% efficiency, with a 3dB frequency tuning range of ∼84–104GHz.