| Magnetically insulated transmission line oscillator (MILO) is a crossed field devicedesigned specifically to generate microwave power at the gigawatt level, which is amajor hotspot in the field of high-power microwave (HPM) research at the present time.Now, research on MILO is concentrated in the lower microwave bands such as L, S,C-band. In this paper, an improved MILO of Ku-band is designed on the basis ofresearching the conventional MILOs. The Ku-band MILO has been mostly researchedfrom the three aspects below. A series of reasonable and valuable results are obtained.1. The MILO theory is systematically investigated. This paper preliminarilyanalyses the operating principles and explains the physics of microwave generating,amplifying and extracting in MILO. In the dispersive relation research, it has beenfound out that the device works in close to π mode and the influence of variousparameters on π mode is summed up. Additionally, the main slow-wave structure (SWS)is designed ascertaining the structural parameters. According to the current density andpower capacity requirements, the device chooses overmoded structure. Further, theholistic structure of Ku-band MILO is designed. Compared with the conventionalMILOs, the Ku-band MILO has been improved: using one choke vane to replace thechoke cavity for preventing microwave leakaging forward, adopting double-cavityextraction structure to improve the extraction characteristics. Besides, the operatingfeatures of MILO such as electric current, impedance, power and efficiency are studied.2. The simulation of Ku-band MILO is developed. The influence of variousparameters on the performance such as power, efficiency and impedance of Ku-bandMILO is studied and some basic laws on design and optimization of structure aresummarized. The typical simulation results show that: the device can producemicrowave at4.1GW with the efficiency of14.4%and frequency of13.2GHz under theinput voltage of510kV and the input current of55.7kA. In the high-frequencycharacteristics analysis, the resonant point of slow-wave structure is found out at13.24GHz in close to the π mode. Further, the simulation is formed in open cavity foundingout the resonant frequency at13.3GHz, proving the correctness of the high-frequencycharacteristics analysis, the dispersion relation research and the simulation results. Theextracting quality factor is106calculated by simulation, corresponding to theconventional classic MILOs’.3. The mode converter of Ku-band MILO is designed. Mode analysis andnumerical calculation on extracting coaxial structure of Ku-band MILO are carried out.On the basis, the design scheme of support bars is advanced. And then, the support barsand the mode converter’s taper are designed and improved. The simulation results showthat: the transmission efficiency of TEM mode in the segment of support bars is99.9%, the conversion efficiency of TM01in mode converter’taper is98.6%, the conversionefficiency of TM01in the whole mode converter is98.2%, the power capacity is about2GW. |
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