| At present,TWT has been used in many fields of modern science and technology,such as radar,communication,precision measurement,etc.,and has become an important microwave electronic device of electronic equipment.With the increase of operating frequency of the device,the loss of high frequency TWT system increases,which has a great impact on the overall performance of TWT.The traditional sine Waveguide slow Wave structure has the good transmission characteristics of low loss and small reflection,and the output power also has the characteristics of Wide band.However,with the increase of frequency,the size of the slow wave structure gradually decreases,so it is difficult to make the ideal sine structure.Therefore,it is necessary to improve the traditional slow wave structure to realize the machining.So we need to improve on traditional slow wave structure,can be processed to achieve the purpose.At the same time,the coupling impedance is further improved by adjusting the slow wave structure,and the output power is further increased.The basic design principles of the improved sine slow wave structure are also introduced.At the same time,the improved sine slow wave structure,the conventional sine slow wave structure and the folded waveguide slow wave structure from the slow wave characteristics,transmission characteristics and beam-wave interaction characteristics are compared.In this paper,the single-stage 12.5 KV improved sine slow wave structure and the double-stage 17 KV improved sine slow wave structure are also designed.Finally,the processing and testing of slow wave structures are introduced.The specific work is as follows:1.The original structure is further improved on the basis of the traditional sine slow wave structure.An improved 340 GHz sine slow wave structure is proposed,which can be machined easily.And the coupling impedance of the structure is further improved.2.Comparing the improved slow wave structure with the conventional sine slow wave structure and the folded slow wave structure,that the improved sine SWS has better performance than the conventional sine SWS.Under the condition that the high frequency characteristics of the improved slow wave structure and the folded waveguide slow wave structure are almost the same,the peak output power of the beam-wave interaction simulation is close to,but the bandwidth of the improved slow wave structure is much wider than that of the folded waveguide slow wave structure.At the same time,the transmission characteristic of the two is almost the same,in the final note-Wave interaction simulation output peak power close to,but improved bandwidth slow-wave structure is far wider than folded waveguide slow-wave structure.At the same time,the improved slow wave structure has more advantages than the folded waveguide slow wave structure.3.A single-stage improved sine slow wave structure is designed,with a working voltage of about 12.5KV and a working current of 30 mA,in the case of 8 million grids.When the input power is 8mW,the output power is greater than 1W.The output gain corresponding to 30 GHz bandwidth is greater than 21 dB in the frequency range of 320-350 GHz.4.A two-stage improved sine slow wave structure is designed.The working voltage is about 17 KV,the working current is 30 mA,and the phase velocity jump technology is adopted.The two-segment sine slow wave structure has the advantages of strong machinability,wide bandwidth and high gain.When the input power is 8mW,the output power of the slow wave structure of the improved sine TWT is greater than 10 W,the corresponding output gain is greater than 30 dB,and the bandwidth is greater than 30 GHz.Finally,the actual periodic magnetic field and the actual electron beam information from the electron gun are taken into the slow wave structure for the interaction calculation,and the output power and gain of the TWT are greater than that of the ideal condition.5.Experiment: In order to determine the actual loss of the slow wave structure under the existing processing methods and verify the rationality of the attenuator design,the machining and size measurement of the test section of the slow wave structure with and without the attenuator were completed.Finally,a Vector Network Analyzer is used to test the slow wave structure,and the experimental results are in good agreement with the simulation results.In conclusion,compared with the traditional structure,the improved sine slow wave structure can further improve the performance of the device such as bandwidth and power due to the flexible design of structural parameters,so it has great research potential and value. |
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