Design and experiment of a 34GHz TE01 gyro-TWT

The design and experimental study of a 34GHz gyro-TWT amplifier operating in the circular TE01 mode at the fundamental cyclotron harmonic are presented. The interaction circuit in this experiment consisted of periodic dielectric loaded circuits that provided the required loss for stable operation. The potential backward wave oscillation interactions involving the spurious modes TE11, TE21, and TE02 are effectively suppressed. The Ka-band gyro-TWT is zero-drive stable at the operating points. A saturated peak power of 160 kW was measured at 34GHz by hot test, corresponding to a saturated gain of 40 dB and an efficiency of 22.8%.The measured bandwidth over 120 kW is at the range of 33.5-35.5GHz. The large-signal prediction shows excellent agreement to the hot test results. Moreover, the designs of interaction circuits, and input coupler and output window are also achieved to satisfy the requirements.