Design of a G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit

A high-order-mode harmonic multiplying gyro-TWA could allow the amplifier to achieve high average powers. An improved mode-selective circuit is employed for suppressing non-TE 0n competing modes while wall losses are employed for suppressing TE 0n competing modes. A G-band second harmonic multiplying gyro-TWT is predicted to yield a peak output power of 56 kW at 200 GHz with an efficiency of 11%, a saturated gain of 48 dB and a 3 dB bandwidth of 3.6 GHz.