Experimental study of an interaction structure with distributed loss for a Ka-band gyro-TWT

Abstract

The distributed-loss technology has been successively applied in many gyro-TWT experiments to suppress absolute instabilities. Based on the stability analysis of a Ka-band TE₀₁ mode gyro-TWT with a distributed-loss interaction circuit, propagation losses of operation and parasitic modes are calculated and dielectric loss parameters, including thickness of the loss layer and relative permittivity, are decided. Taking advantage of the optimised parameters of a loaded dielectric, a high-gain scheme is demonstrated in a 34 GHz, TE₀₁ mode gyro-TWT, producing 160 kW saturated output power at 40 dB, stable gain and 22.8% efficiency with a 3-dB bandwidth of 5%.

Keywords:

• gyro-TWT
• the small signal linear theory
• oscillation
• distributed loss