Study on W-Band Sheet Beam Metallic Grating Amplifier Based on Combined Cherenkov and Cyclotron Resonances

In principle, if the beam is with initial transverse and axial velocity as well as propagating in period slow wave circuits, the combined Cherenkov and cyclotron resonances will exist, and the interaction will be enhanced. To illustrate and understand the influence of the combined resonance on the performance of devices intuitively, W-band sheet beam amplifiers with single-grating and staggered double-grating slow wave structures based on combined resonance and Cherenkov resonance are all designed and simulated, respectively. The results show that gain, bandwidth, and efficiency can be improved by utilizing multiresonances compared with Cherenkov resonance, which shows the attractive performance of the combined resonance. For the single-grating amplifier (SGA), the gain, bandwidth, and efficiency are improved by 1.68 dB, 2 GHz, and 0.45%, respectively. For the staggered double-grating amplifier (SDGA), the gain, bandwidth, and efficiency are improved by 0.85 dB, 5 GHz, and 0.42%, respectively. Besides, the comparisons of SGA and SDGA based on combined resonance are also presented and analyzed to provide a reference for the project implementation.