Key Technology Research On Millimeter-Wave Broadband Extended Interaction Klystron

Driven by the demand of high-power broadband millimeter-wave applications,extended interaction klystron(EIK)has been extensively studied and applied for its numerous advantages.EIK has a short development period in China,and there is no existing millimeter-wave broadband EIK circuit.Hence,one of the key technology research is the systematic study of extended interaction circuit,searching for the broadband circuit with which to build the broad frequency tuning extended interaction oscillator(EIO)and broadband extended interaction amplifier(EIA).This dissertation focuses on the millimeter-wave broadband EIK,theoretical research,circuit design and preliminary experimental measurement on it are carried out.Main content of research included the broad frequency tuning EIO and broadband EIA,with an emphasis on broadband EIA.The study of broad frequency tuning EIO is not only to achieve itself,but also serves as the characteristic study of the extended interaction circuit,guides the output performance optimization and stability analyses of the common single-mode EIO/EIA,and explores solution for broadband EIA.For the millimeter-wave broad frequency tuning EIO,several attempts have been made to extend the frequency tuning range.Electronic tuning multi-mode EIO overcomes the limitation of the electronic tuning range of the common single-mode EIO.By using multiple modes,an electronic tuning range of more than 0.73 GHz is obtained in W-band.For the first time,the multi-mode continuous tuning near the standing-wave mode is achieved.In addition,its multi-mode working mechanism guides the design of broadband multi-mode EIA.The mechanical tuning high-efficiency dual-cavity EIO overcomes the efficiency limitation and circuit instability of the common single-cavity EIO.The electronic efficiency is increased from 14.2% to 20.2%(or from 16.8% to 21.7%)by introducing the bunching cavity,and the efficiency can be further improved.A mechanical tuning range of more than 80 MHz is obtained in Ka-band by introducing mechanical tuning into the bunching cavity.In addition,feasibility and stability of this circuit are analyzed and improved.For the millimeter-wave broadband EIA,due to the limitation of single-mode working mechanism of the common extended interaction circuit,bandwidth of the existing EIA circuits are generally around 0.5%.A new broadband multi-mode extended interaction circuit is proposed.-3dB bandwidth of the Ka-band broadband multi-mode EIA using this circuit is more than 2.4%,and it can be further improved.For the first time,the multi-mode working mechanism is studied and broadband multi-mode amplification is achieved.This circuit has the advantages of broadband,high-gain,simple structure and easy engineering implementation,which is suitable for millimeter-wave applications.In addition,the study on the uniform/stagger grating extended interaction circuit explains the authentic working mechanism of stagger grating ? mode EIA,which is widely used at present.At the same time,dual 2? modes are studied by the simulation and experiment;common single-mode extended interaction circuit is systematically studied;design methods of the W-band pencil-beam/sheet-beam single-mode EIA are presented;electric field distribution characteristics of the low-voltage circuit is analyzed;bandwidth limitation of the common multi-cavity stagger-tuning single-mode EIA is analyzed;characteristics of the uniform/stagger grating circuit are studied;strong/weak coupling grating,suppression of mode competition and electric field distribution measurement are of great significance to the research of extended interaction circuit.Two typical circuits are selected for experimental measurement,including the electric field distribution measurement of dual 2? modes in the common extended interaction circuit and the reflection/transmission characteristics of the new broadband multi-mode circuit in different stagger degrees.For the former one,not only the existence of the 2? cavity mode as a competition mode is verified for the first time,but also the electric field distribution of the 2? grating mode as a common working mode is obtained.For the latter one,resonance characteristics of the new broadband multi-mode circuit are verified,and it serves as the basis of the following experiment.In a word,not only the common single-mode EIO/EIA,but also dual 2? modes and electronic tuning multi-mode EIO are studied.More importantly,based on the above study,the new broadband multi-mode working mechanism and a new broadband multi-mode circuit are proposed.In this dissertation,EIA bandwidth is improved to a new level and the research of the broadband EIA is extended to a new field by the study of the multi-mode circuit.In addition,all of the circuit parameters of the broad frequency tuning multi-mode EIO and broadband multi-mode EIA are given for the convenience of researchers.