Prebunching Of Electrons In Harmonic-Multiplying Cluster-Cavity Gyro-Amplifiers

The use of a cluster of cavities in frequency multiplying gyro-amplifiers is considered. An analytical theory has been developed to maximize the second harmonic current and optimize the drift section length for the case of a single low-Q input cavity, operating at the fundamental cyclotron harmonic, and bunching clustered cavities operating at the second-harmonic. MAGY simulations have been conducted to benchmark the theory and further study the detailed characteristics of cluster-cavity gyro-amplifiers. The theory and MAGY code simulation agree. In the small signal regime, the bandwidth of a cluster-cavity device (with a pair of cavities in the cluster) is twice that of a single cavity device, while both have the same peak bunching. With a gyro-TWT output section, a peak power of 247kW, efficiency of 24.2% and bandwidth of 1.08% have been simulated using a cluster of cavities as a buncher. Also, the power-bandwidth product is 105 kWxMHz, which is double that of the single cavity buncher case