Study Of A S-band Relativistic Magnetron With Axial Diffraction Output

The reason why the magnetron is widely used in radar, energy and other areas, that the magnetron can produce very high output power, high electron conversion efficiency, stable phase.So far, the magnetron is still one of the most important components in orthogonal field of high power microwave source(HPM).In order to meet the demand, the magnetron need to be extrapolated in high-current direction and then relativistic magnetron(RM) developed rapidly.However, the relativistic magnetron developingfor a long time, its low efficiency problem is not concerned.The conventional magnetron generally takes methods of extracting energy in radial, namely, opens one or more slots in the position of the resonator, and then uses the waveguide to couple energy.The characteristic of extracting energy in radial, makes volume of the magnetron apparatus very large, the magnetic field system also taking up a lot of space.In order to meeting the current demand for miniaturization, the model of the relativistic magnetron with axial diffraction output(MDO) is proposed.Compared with the conventional relativistic magnetron, MDO has many advantages.Firstly, in the structure, MDO gradually extends in the axial to radiates energy, sothere is no need to open slots in radial and the structure is symmetricalin the angular.Secondly, eliminating the complex apparatusfor extracting energy in radial,radiating energy in axial cansimplify magnetic field system andhasthe characteristics of miniaturization.Thirdly, the symmetry in the angularof theMDOmakes it work in any mode, and the desired output mode can be selected depending on the ways of extracting energy.Device of extracting energy also plays a role in the conversion mode.Finally, the high-power microwave energy can be extracted, avoiding problems of microwave breakdown when outputting energy in radial andsome limits of parameter. It is also improving the low efficiency problem of general relativistic magnetron.In order to meeting the demand for miniaturization and avoiding havingsome adverse effects on magnetron which is caused by the low efficiency, the paper focuses on the researchand design of the MDO.Theresonance system ofthe magnetronselects A6 relativistic magnetron which has been studied for a long time, the anode cavity radius, height and cathode radius adopts its classic size.The part of horn antenna adopts trough output structure andthe research method adopts theory as well as simulation.Based onthetheory ofmagnetron, the article analyzes some features of the MDO and therelationship between radiation pattern and methods of energy extraction.The radiation pattern is TE01 mode when choosing three-cavity output structure.The preliminary designed MDO is simulated by CHIPICwhich is a three-dimensional particle simulation softwareself-developed by China andoptimizethe magnetron basing on the simulation results.Themaximumefficiency is 22.9% after optimization. Taking into account the fact that the transparent cathode can accelerate the start-up ofπmode and improve efficiency, transparent cathode can replace ordinary cathode. After using transparent cathode, continuing to optimize the magnetron, it ends up with a axial output relativistic magnetron which has power output of 436 MW, electron conversion efficiency of 46.2%, the operating frequency of 2.867 GHz.In order to verify the accuracy of the simulation results,it is also compared with the results calculated by the mainstream of foreign software.The two software’s simulation time and parallel computing time is compared, too.The results of the comparison show that the simulation results of the two software are same, however, CHIPIC software canparallel computingwhich can save a lot of simulation time.