Study of a 500-GHz Medium-Power Second-Harmonic Multiplying Gyrotron Traveling-Wave Amplifier With a Broad Frequency Range

A harmonic multiplying gyrotron traveling-wave amplifier (gyro-TWA) allows magnetic field reduction and frequency multiplication. This study presents a low-voltage, lowcurrent, 500-GHz second-harmonic multiplying gyro-TWA that produces a medium power of similar to 10 W over a broad frequency range (similar to 5 GHz). An improved harmonic multiplying gyro-TWA featuring a distributed-loss structure achieves improved amplification performance and stability. Simulation results show that the involved spurious oscillations can be suppressed by high lossy-section resistivity, long lossy section, and short copper section. A tuned magnetic field is employed to achieve broadband frequency characteristics. The output power of the amplifier is a quadratic function of the input power. With a 12-kV, 0.3-A electron beam, the frequency range of the proposed amplifier is approximately 5 GHz for a 1-50-mW input power that can be provided by a 250-GHz commercial solid-state source.