Ka-Band Gyrotron Traveling-Wave Tubes With the Highest Continuous-Wave and Average Power

TLDR

Single‑stage depressed collectors, a first for gyro‑TWTs, enable electron efficiencies up to 36 % for pulsed and 33 % for CW operation at the second cyclotron harmonic. Experimental tests of two Ka‑band gyro‑TWT amplifiers with helically corrugated waveguides showed pulsed output of 130–160 kW at 33.1–35.5 GHz (10 % duty) and CW output of 7.7 kW with 2.6 GHz –3 dB bandwidth, while the depressed collectors achieved the reported efficiencies, confirming high‑power reliability.

Abstract

The results of experimental investigation of two Ka-band gyrotron traveling-wave tube (gyro-TWT) amplifiers with helically corrugated waveguides are presented. The first tube produces pulsed output power of 130-160 kW within the frequency range of 33.1-35.5 GHz and is capable of operating with a 10% duty factor. Reliability of its major components in the high average power operation regime (about 10 kW) was proven in a continuous-wave (CW) experiment. The second gyro-TWT amplifier delivered CW power of up to 7.7 kW with -3-dB bandwidth of 2.6 GHz and -1-dB bandwidth of 2.1 GHz. Effective implementation of single-stage depressed collectors (to the best of our knowledge, for the first time for gyro-TWTs) enabled the electron efficiencies as high as 36% for the pulsed tube and 33% for the CW tube to be achieved at operation at the second cyclotron harmonic.