Linear and nonlinear analyses of a wideband gyro-TWT

Linear and nonlinear analyses on a gyrotron amplifier with a periodically disk-loaded cylindrical waveguide circuit are performed. The dispersion relation of the circuit allows for wideband interaction with a relativistic beam of moderate power (Vb = 60 kV, Ib = 5 A). Linear analysis of the interaction with the fundamental mode shows a gain of the order of 50-60 dB/m over a bandwidth larger than 22 percent and a linear phase-vs-frequency characteristic. Nonlinear analysis predicts 48-kW saturated output power at 5.3 GHz with 18-percent efficiency. The saturation length for a 20-dB tube is about 37 cm.