MILO Performance Improvement Study—An Equivalent Circuit Approach

In this article, a high-power microwave (HPM) oscillator magnetically insulated line oscillator (MILO) design study has been carried out to improve its performance. Impedances of different subsections of the device have been matched. An equivalent circuit approach, which is simpler and easy to handle, has been adopted for this purpose. First, the input impedance of the tapered inner conductor of the coaxial structure has been matched with the impedance of the choke disks. Then, the extractor inner radius and extractor gap impedance have been optimized at the output section. This impedance matching scheme provides the maximum efficiency of the device with the maximum RF transmission. The optimum position of the stub to match the impedance with the output side has also been analyzed. To validate our concept, initially, an experimentally reported
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-band MILO has been simulated using commercial particle-in-cell (PIC) code, which provides an RF output power of 1.38 GW with the efficiency of 7.8%. The PIC simulation results have been found in agreement of ~5% with the experimental values. Furthermore, the PIC simulation with the optimized design parameters has improved the RF output power of 2.5 GW with an efficiency of 14.4%.