Theoretical And Experimental Study On High Power Travelling Wave Tube

Travelling wave tubes(TWTs)as a traditional broadband device have occupied the power amplification of communications,radars,and electron warfare for many years.It includes a large number of military and civilian systems,such as one-dimensional multi-beam-phased array,two-dimensional passive and active-phased array systems.It is an important direction to develop high power,high frequency,high efficiency and miniaturization for TWT.Traveling wave tubes have developed rapidly in recent years.They are becoming more and more important in the fields of biology,chemistry,physics,engineering,astronmary and son on.Its application has gradually penetrated into many aspects of social economy and national security.A series of studies on high power millimeter-wave TWTs in the bandwidth range of 18-50 GHz were developed in recent years in china.Helix structure TWT mainly works under 40 GHz and folded rectangular waveguide TWT mainly develops over 40 GHz.As the frequency increase,many kinds of new slow-wave structure TWT are pouring in,which has laid a very good foundation for electronic vacuum devices moving to high frequencies and even the terahertz band.The theme of this Ph.D thesis is the key technologies of high-power,high-frequency traveling wave tubes and the innovations of this thesis are as follows:1.A 100 W broadband K-band high-efficiency miniaturized TWT was first developed in this thesis,and then through power synthesis technology achieved power 200 W target in the whole K-band.It is the first time in domestic that power synthesis technology is applied to high-power broadband K-band TWT,which is fast and reliable.Electromagnetic compatibity,electromagnetic ineerference and communication for power levels greater 200 W are well satisfied.2.The technology of broadband millimeter wave high efficiency distribution design,antenna thermal stability and high efficiency collector design has been carried on in this thesis,which has improved the output power and efficiency of the broadband K-band traveling wave tube.The output power and the overall tube efficiency of the successfully developed single-tube 250 W broadband K-band high-efficiency mininaturized traveling wave tube are greater than 250 W and44%.Compared with a similar foreign product,the 250 W brosdband K-band high-efficiency miniaturized TWT is that the volume is doubled,the output power is increased by 100 W,and the whole tube efficiency is increased by 10%.3.The folded V-shape groove waveguide which is suitable for working in millimeter wave and terahertz wave is proposed.The 94 GHz folded V-shape groove waveguide TWT and the 220 GHz folded V-shape groove waveguide TWT are designed.They are haves the characteristics of high frequency,low loss and large size.At the same time,the output section used two phase-speed negative transitions of 94 GHz folded V-shape groove waveguide traveling wave tube improved the electronic efficiency and expand the working bandwidth.The double anode electon gun is designed for the operating parameters of the 94 GHz folded V-shape groove traveling wave tube.When the electron injection is loaded with a cathode voltage of 16.95 kV and the anode voltage of 11.5kV,a current of 200 mA can be obtained and the electron injection waist and the distance of the electron injection are obtained 0.16 mm and 15.7mm respectively.4.A ridge-loaded folded rectangular groove waveguide is proposed by loading ridges on the straight portions of the folded rectangular groove waveguide to enhance the beam-wave interaction.A 340 GHz ridge-loaded folded rectangular groove waveguide TWT,A suitable attenuator structure and the transmission waveguide structure for this new slow-wave structure aredesigned.At the frequency point of 340 GHz,the maximum gain of the 340 GHz ridge-loaded folded rectangular groove waveguide TWT is 26.99 dB.Its 3dB bandwidth is 335GHz-342 GHz,which can generate average output power of more than 39 W.The thermology and mechanicalanalyses of 340 GHz ridge-loaded folded rectangular groove waveguide TWT are carried out to verify its reliability.5.The folded double ridge groove waveguide is put forward to expand the bandwidth,which is fit for THz traveling-wave tubes because of its high efficiency,wideband and high power.At the frequency point of 340 GHz,the output power and the maximum gain of 340 GHz folded double ridge groove waveguide TWT is 65.8W and 27.21 dB respectively.Its 3dB bandwidth is 335GHz-343 GHz.The thermology and mechanicalanalyses of 340 GHz folded double ridge groove waveguide TWT are carried out to verify its reliability.