Research On Beam-wave Interaction Of Extended Interaction Klystron In Terahertz Band

With the increasing interest of researchers in terahertz technology,conventional microwave vacuum devices should be improved to accommodate this particular and promising band when it comes to the terahertz band.The extended interaction klystron is one type of devices developed from traditional klystrons that can fully satisfy the terahertz band.When designing and developing an extended interaction klystron,people often rely on experiments or general-purpose simulation software to obtain their operating characteristic parameters or other valuable data.However,these methods generally consume a lot of time,manpower and financial resources,and small-scale dedicated computing software can quickly and easily assist research work.In this thesis,the terahertz technology and the corresponding devices are introduced firstly,then the development and prospects of terahertz technology are described.After that the history and working principle of klystrons and extended interaction klystrons are introduced and also CAD technology is described.From a mathematical and physical point of view,the klystron interaction process is analyzed and related important parameters is introduced.Then a mathematical derivation is made to obtain the matrix expression of the coupling cavity impedance.According to related theories,the formula for calculating the electronic conductance of the multi-gap coupling cavity in 2? modes and ? modes are deduced first,and the corresponding calculation software is designed and developed.The stability of the electronic conductance in the coupling cavity is analyzed by changing the operating voltage,gap width and cycle length.At the same time,the electronic conductance formula deduced by the kinematics theory is compared with the calculation results and good results are obtained.Secondly,the calculation formula and method of the small signal gain of extended interaction klystron are introduced and analyzed,and the corresponding calculation software is designed and developed.When comparing with the calculation result in the literature,a more consistent result is obtained.Finally,according to the onedimension disk model,the calculation software of the electronic conversion efficiency of the extended interaction klystron is developed and designed using MATLAB,and compared with the MAGIC simulation results.The differences are analyzed briefly.Using the developed electronic conversion efficiency calculation software,the influence of the change of the characteristic impedance of the coupling cavity on the electronic conversion efficiency is preliminary studied,and the results is analyzed.The calculation software developed on the basis of the electronic conductance,small signal gain,and large-signal electronic conversion efficiency of the extended interaction klystron that is designed and developed in this thesis has the characteristics of easy operation and short calculation time.It can,to some extent,bring convenience to the relevant research process.