Electromagnetic Properties Of HTWT With Hot Electron Beam Loaded

Helical traveling wave tube(HTWT)is a kind of very important vacuum electronic device,which has high power,wide band,high gain and high efficiency.HTWTs are widely used in radar,electronic countermeasure,satellite communication and so on.The research on the electromagnetic properties of the HTWT is usually neglected the influence of the electron beam,and the cold VSWR and the cold high—frequency characteristics are used to evaluate the electromagnetic properties.However,when HTWT is under working,the electron beam will inevitably affect the propagation of electromagnetic wave,which causes differences between hot electromagnetic and cold electromagnetic performance.How to analyze the influence of electron beam and get accurate standing wave interaction becomes an important issue when designing high performance space HTWTs.In this paper,take a broadband HTWT as an example to analyze the influence of electron beam on electromagnetic properties of TWT.The main work of this thesis is:1.Analyzing the equivalent medium of electron beam.Based on the Maxwell equation and the electronic fluid mechanics,we using method of equivalent medium quality to study the electron beam focus on infinite magnetic field and periodic magnetic field.The electron beam in infinite magnetic field is equivalent to a medium,reciprocal and anisotropic dielectric tensor by means of equivalent medium quality.The electron beam in periodic magnetic field can be considered as a kind of anisotropic medium,and the permittivity and permeability are both tensor and chiral.And analyze the influence of the electron beam parameters on the dielectric tensor.2.Theoretical analysis of the electromagnetic properties of electron beam loading.Firstly,the high frequency structure is simplified into a spiral guide surface model,and analyzing the spiral guide surface model of not loaded and loaded electron beam.Then,deduce the corresponding dispersion,coupling impedance and the characteristic impedance,by contrast with simulation result in cold condition to verify the correctness of the theoretical derivation.Then,analyze the effect of electronic voltage,electric current and electron injection radius on electromagnetic properties.It provides a theoretical basis for influence of electromagnetic properties.3.Using CST Microwave Studio to simulate the broadband HTWT.Then,design an attenuation model of HTWT.And get the corresponding cold Standing wave characteristics.After that,loading the electron beam under different magnetic field into the HTWT,and establishing a complete energy transfer system model.Finally,using CST to simulate the hot VSWR of an infinite focusing magnetic field,and analyze the influence of electron voltage,electron current and electron beam radius on the standing wave.