An Output System For The High-power Microwave Generators Driven By Sheet Electron Beams

The increasing application demands impel the high-power microwave(HPM) forward, attempting higher power, higher frequency and longer pulse. However, the traditional HPM generators are facing the problems of plasma and breakdown which can hardly be solved for the small sizes of high-frequency instruments. HPM generators driven by sheet election beam(SEB), with large aspect ratio, is promising to breach the bottlenecks on the way of increasing power, as a result of low current density, fine structure compactness and good convenience to adjust injection impedance and power. Because HPM generators with SEB and their operating modes are large-aspect-ratio, new output system adapting to the large aspect ratio is badly needed. In this dissertation, an output system for HPM with SEB has been designed, containing SEB collector, large-aspect-ratio TM11-TE10 mode converter and radiation antenna. The detailed contents include the followings:1. An SEB collector is designed. The parameters have been deduced, calculated and simulated. The collector is thick enough to collect SEB effectively, while the microwave can transit with S21=-0.04 d B. The thermal analyses show that the SEB collector can hold the current with 3 k A, 300 k V, pulse width 40 ns and repetition frequency 50 Hz without exterior water cooling instruments.2. A large-aspect-ratio TM11-TE10 mode converter has been designed. The parameters have been deduced, calculated and simulated. The simulation shows that S21=-0.03 d B at12.5 GHz and S21>-0.45 d B over 10.58~13.58 GHz. The power handing capacity is about 2.85 GW. It performs much better with larger aspect ratio. A compact structure is also designed reducing axial length 22.6%.3. Another two mode converters based on slotted waveguide array antenna theory are presented, which can transfer the standardized TEM mode into large-aspect-ratio TE10 mode and large-aspect-ratio TM11 mode with S21=-0.02 d B and S21=-0.04 d B at 12.5 GHz. Their interesting bands with S21>-0.45 d B are 11.67~13.34 GHz and 11.60-13.42 GHz,meeting the needs of cool testing.4. An integrated scheme is presented. Two kinds of slotted waveguide array antennas are designed, simulated and optimized. In the edge feeding one, the total Gain reaches 20.04 d B, while side levels are-1.75 d B in E-plane and 0.91 d B in H-plane,and the half-power bandwidths(HPBM) are 13.70°in E-plane and 10.93°in H-plane. In the center feeding one, the total Gain reaches 21.66 d B, while side levels are-2.46 d B in E-plane and-1.45 d B in H-plane,and the HPBMs are 22.39°in E-plane and 9.15°in H-plane. The integration of SEB collector and mode converter can reduce 225? and 128 ? for SEB collector and waveguide respectively. According to different applications, two kinds of schemes are presented, the transverse one and the axial one, providing a reliable technique scheme to HPM with SEB.5. Engineering designs, fabrications and experiments are presented. Three kinds of mode converters have been engineering designed and processed. The experimental results show that at operating frequency 12.5 GHz, the TEM-TE10 mode converter's S21=-0.23 d B, the TEM-TM11 mode converter's S21=-0.43 d B, and the TM11-TE10 mode converter's S21=-0.19 d B,while their bands agree with the simulations. Hot test scheme has been presented at last.