| Radial beam travelling wave tubes(TWTs)are the mainly kind of miniature product of vacuum electronic devices,which can fullfill the application requirements of the fifth generation wireless systems,new radar systems because of the properties of wide bandwidth,low work voltage and small dimensions.In this paper,design and implement of slow wave structure(SWS),electron gun and magnetic focusing system are elaborated in detail,which include the transmission characteristic of the angular logarithmic microstrip SWS,the generation of fan-shaped radial divergent sheet beam,radial tunnable periodically cusped magnetic(PCM)focusing system and the design of azimuthal supported angular logarithmic strip line SWS.The main work and innovation of this dissertation are as follows:1.Study on the transmission characteristic of the angular logarithmic microstrip SWS.The transimission characteristic study of angular logarithmic microstrip SWS is improved based on short period ones,in this paper,the variation trend of transmission characteristic of whole period SWS are studied with different structure parameters.Based on the optimized structure parameters,the microstrip SWS on quartz is fabricated and tested,and the experimental results accord well with the simulation results.2.The fan-shaped radial divergent sheet beam electron gun is proposed and studied.To meet the required electron beam of angular logarithmic microstrip SWS,the fan-shaped radial divergent electron beam gun is proposed.The disk-shaped radial divergent/convergent can be used to the full angle(360 deg)logarithmic microstrip SWS.But for the angular logarithmic microstrip SWS,fan-shaped radial divergent/convergent sheet beam is needed for the beam-wave interaction.In this paper,the design platform of fan-shaped radial divergent sheet beam gun is established,and the electron gun with different work voltages and emission currents by using the cathode head with the emission surface of cylindrical surface and hyperboloidal surface can be easily designed on the design platform.3.Study on the fan-shaped tunable radial PCM magnetic focusing system.In order to keep the shape of the fan-shaped radial divergent sheet beam during the movement process through the electron tunnel with special height,the fan-shaped tunable radial PCM magnetic focusing system is designed.And the peak magnetic value is(633~1255)Gs,the staggered angle of the pole pieces is 0.9 deg,then,the transmission efficiency is 100% when the electron beam travelling through the 0.52 mm height electron tunnel.4.The preparation technology and test method are designed for radial divergent electron beam optical system.Based on the theoretical design of the fan-shaped radial divergent electron gun and fan-shaped tunable radial PCM magnetic focusing system,the preparation technology is designed and the proto type of the drift tube is manufactured.Under the work voltage of 1700 V,the hot test results show that the emission current is 46.3mA and the transmission efficiency is 90.7%.5.The azimuthal supported angular logarithmic strip line SWS is proposed and studied.Angular logarithmic microstrip SWS has the properties of low work voltage,wide band width,high interaction efficiency and so on,but the disadvantages are also obvious,such as charge accumulation and electrostatic discharge caused by defocused electron beam bombardment.The situation may worsen the working state or damage the tubes.To keep the properties and avoid the disadvantages of microstrip SWS,the azimuthal supported angular logarithmic strip line SWS is designed,which with the work voltage of 5720 V,the gain of 15.4dB and the 3dB band width of 5GHz.Both theoretical and process design are based on the domestic technological level,in order to realize that the structure size can be machined easily and assembly technology can be operated,and at the same time,are also provided with innovativeness.The research achievements in this paper have profound guiding significance for the productization of new generation miniature angular logarithmic radial beam TWT. |
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