Study of a Broadband and High-Power Terahertz Gyrotron Traveling-Wave Amplifier

This letter presents a high-power (> 1 kW) broadband gyrotron traveling wave amplifier (gyro-TWA) based on a five-fold (5F) helically corrugated interaction region (HCIR) that operates at the frequency range of 254-280 GHz. The 5F HCIR was manufactured and its measured dispersion characteristics matched very well both with the theoretical predictions and simulated results. The third harmonic cyclotron mode of a 60 keV, 0.75 A, axis-encircling electron beam could be used to resonantly interact with a traveling TE31-like eigenwave in the 5F HCIR to achieve a broadband amplification. The 3-D particle-in-cell simulations predicted a saturated output power and gain of ~1.5 kW and 39.7 dB respectively, with a 3-dB bandwidth of ~26 GHz (~10% relative bandwidth) driven by a 0.16 W input signal.