Cascade of Two $W$ -Band Helical-Waveguide Gyro-TWTs With High Gain and Output Power: Concept and Modeling

In order to realize a high-power (100 s of kilowatts at the W-band) wideband microwave amplifier, we suggest to use a cascade of two gyrotron traveling-wave tubes (gyro-TWTs), one of which possesses a relatively high gain (40-50 dB) while the other provides a high output power at a moderate (15-20 dB) gain. Both gyro-TWTs are assumed to use helically corrugated waveguides and operate at the second cyclotron harmonic. A principal scheme of such an amplifier chain is discussed, including issues on the microwave input, output, and transmission between the tubes. Computer modeling of the beam-wave interaction using CST Particle Studio PIC Solver shows the possibility of achieving of 200-370-kW output power with 8-10-GHz bandwidth when driving by a 50-mW input source at the W-band.