Study Of The Effect Of Fabrication Errors On TWT Beam-Wave Interaction And The Inhibition Methods

With the development of traveling wave tube to higher frequencies, the working frequency extension to hundreds of GHz even THz frequency range, the circuit structure of the minimum size requirements of magnitude of 0.002 mm or less, also more and more high to the requirement of process, but in the process of manufacturing technology, inevitably there will be some random error is introduced in the traveling wave tube high frequency circuit, impact on the traveling wave tube performance. Manufacturing error has become a main cause of the traveling wave tube performance is not ideal.Therefore, Effect of random circuit fabrication errors on small-signal gain and phase in traveling-wave tubes has important significance.This paper around the traveling wave tube linear theory and the traveling wave tube simulation technology carry on research, the main research content of this paper includes the following several aspects:1 First,according to the spiral conductive surface model, derived the dispersion relation of helix TWT,established the dispersion equation to solve the slow wave ratio and the relationship of the angular frequency. Then, analyzing the helix TWT slow-wave system coupling impedance and attenuation characteristics,provide theory basis for analysising the effect of random circuit fabrication errors on small-signal gain and phase.2 Based on the small-signal theory, this paper studied the effect of random error on the small signal gain and phase, get the analytical expression of first-order perturbation theory. Finally, by means of numerical analysis method, the numerical results with the first-order perturbation theory analytical results were compared to verify the consistency, the analytical and numerical solutions.At the same time.we found the small-signal parameters with pertubations has significant impact on small-signal gain and phase.Our study also confirms that the effects of perturbations in the circuit phase velocity dominate the effects of perturbations in C and d.All of this provide accurate theoretical support for later research of the effect of random circuit fabrication errors on TWT beam-wave interaction.3 Based on the the first-order perturbation theory, with the help of the latest development in traveling wave tube CAD technology, using the V band helix traveling wave tube as an example.I analysis the effect of random circuit fabrication errors on TWT beam-wave interaction from three aspects:1.The effect of random slow wave circuit errors on small-signal gain and phase.2. The effect of random wave-beam interacion errors on small-signal gain and phase.3.The effect of random circuit fabrication errors on bandwidth of TWT.Through the simulation study of the three aspects,this paper detailed analysis the effect of fabrication errors on TWT beam-wave interaction,and methods of inhibiting the fabrication errors. This paper provides a feasible method for the analysis of the effect of fabrication errors on TWT, at the same time it also has a certain engineering significance for the design of twt.