| Microwave electronic vacuum device are a kind of devices which use charged particles to interact with electromagnetic signals and give the energy of electron beam to electromagnetic signals.As an electronic vacuum device,traveling wave tube plays an important role in electromagnetic applications.With the development of science and technology,people's research and application of electromagnetic wave have entered the field of millimeter wave and terahertz.Because the structure size of traveling wave tube decreases sharply with the increase of frequency,the power capacity decreases,so it is an important work to improve the output power of traveling wave tube at high frequency,and it is an effective method to improve the output power of traveling wave tube by means of integrated power combination.As a kind of traveling wave tube,dual mode traveling wave tube works in high and low modes and has important applications in radar,electronic countermeasure and so on.The main contents of this thesis are as follows:(1)Study on dual-mode traveling wave tube with dielectric-supported suspension line in Ka band.First,the high frequency characteristics of slow-wave structure are calculated and analyzed,and finally the size of slow-wave structure is determined according to the design requirements.Next,the full cycle model is established and the transmission characteristics are calculated.The return loss is lower than-15dB in the27GHz-32GHz band range.Then beam-wave interaction in low and high mode of traveling wave tube is calculated,in the 27GHz-32GHz band range,low mode:the working voltage is 4700V and current is 0.11A,output power is higher than 24W,the maximum output power can reach 54.2W,the gain is 20.35dB;high mode:the working voltage is 4700V and current is 0.15A,output power is higher than 28W,the maximum output power can reach 72.5W,the gain is 21.6dB.Finally,a method based on MEMS sacrificial layer technology is proposed to process the integrated slow-wave structure.(2)Power integration design for planar traveling wave tube.Firstly,the slow-wave structure of dielectric-support suspension line is connected in two and four channels,and the transmission characteristics are calculated.The effect of coupling on transmission parameters of multi-channel slow-wave structure is discussed,and the amplitude and phase consistency of each branch signal of two-channel and four-channel structures are analyzed.Then the beam-wave interaction of the power integrated traveling wave tube in high and low mode is calculated,and the output power of the single-channel,two-channel and four-channel structures is compared.The results show that the output power of the traveling wave tube can be greatly improved by the integrated design of multi-electron beams and multiple slow-wave circuits,compared with the traveling wave tube with single electron beam and single slow-wave circuit.Finally,the effect of electromagnetic coupling on the output power of two-channel and four-channel slow-wave structures is analyzed.(3)An electron gun for Ka band four beams power integrated dual mode TWT is designed.A dual anode sheet beam electron gun is designed.The dual-mode operation is realized by changing the voltage of the first anode.The first anode voltage is 4900V and 4000V,respectively,the second anode voltage remains 4900V.The obtained current is 0.11A and 0.15A,respectively,the current densities are 131A/cm~2 and178A/cm~2,which are consistent with the electron beam parameters calculated by the interaction. |
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