Study On Phase Locking And Power Combining Of Relativistic Magnetron

There are physical limits on all kinds of high-power microwave sources due to the inherent limitations of physical mechanism and structures. In order to get higher coherent radiation power, the power combining based on phase-locking technology is one of the promising ways. In this thesis, the injection phase-locking and cascaded phase-locking constructed by relativistic magnetrons are investigated, and the technology of spatial power combining as well as an experimental scheme of it are discussed.The property and characteristic of relativistic magnetron is analyzed by theory and simulation firstly. The high-frequency system is studied from three different ways: electromagnetic theory, equivalent circuit method and high-frequency software. The situation of relativistic magnetron with three extraction windows was studied by PIC method. Simulation results show that driven by 500kV voltage and 0.5T axial magnetic field, the relativistic magnetron can radiate a high power microwave of 580MW at 2.9GHz from every one of the three extraction windows. The efficiency of the device is 26.5%. Besides, the influences of driving voltage, axial magnetic field, cathode-cap, anode end cap and transparent cathode on the property of the device are investigated in detail.For the injection phase-locking model, the classical phase-locking condition is deduced at first. Then the influences of injection time, injection ratio and frequency mismatch on the phase-locking feature are studied by PIC simulation. It is found that the oscillation of relativistic magnetron can be controlled or disturbed when alien signal was injected into one of the resonators, and it will return to the state of free oscillation when the external signal switches off. The results show that the parameter region able to realize phase-locking obtained from PIC simulation is wider than that from classical derivation. Finally, the classical phase-locking condition is modified by the simulation results.For the model of cascaded magnetron, the relationship between the connector and transmission parameter is studied firstly, the transmission parameter reduces dramatically with the increasing of connector length or the decreasing of connector radius. Then the influence of connector parameters on phase-locking is investigated by PIC method. It is found that proper phase locking condition can be realized with the appropriate choice of connector parameters. Typically the time for magnetron units to realize phase-locking is less then 10ns. In the situation of phase locking, the phase difference between magnetron units is in the range of±36°.The last part of the dissertation focuses on power combining. Three methods of spatial powers combining are discussed. The parallel beams are adopted for power combining of relativistic magnetron. According to the preliminary research on radiation systems, an experimental scheme of power combining based on cascaded magnetron model is designed. Then the measurement methods of related parameters are discussed.