Improvement And Optimization Of The Designing Method Of TWT

Space traveling wave tube (TWT) have a potential application in satelliteindustry in the future. Due to the extremely rigorous work condition, high efficiencyplay a key role in the performance of the space TWT. This dissertation is focused onseveral hands of the design of a high efficient space TWT, the main contents of thisdissertation can be concluded as follows:(1) A new method for optimizing the electron beam performance is introduced.At first, the so-called 'synthesis method' used for Pierce gun design was employed toget the prototype gun. Secondly, in order to evaluate the electron beam performance,an objective function is defined, which can take perveance, beam waist and laminarityinto account. Finally, a direct optimization method and the EGUN program areapplied to optimize the objective function.An electron gun is obtained by the above method, and then the dissertation tooka short discussion about how to design a periodic permanent magnetic focusingsystem for matching the above-mentioned electron gun. In the electron gunexperiment, the beam performance is consistent with the initial requirement very well.This result is an evident example that exhibits the optimization method beingeffective.(2) A detailed analysis of the influences on the helical symmetry produced fromthe support rods in the helical slow-wave structure (SWS) is studied. By use of themaster-slave boundary condition of HFSS, at the condition of keeping the sameprecision, reducing the one pitch helical model to one-third pitch that cancorrespondingly shorten the original running time to one-third. The SWS used in aspace TWT was designed and the simulation result has met with the initial target.Moreover, the SWS is manufactured and its dispersion characteristic andinteraction impedance are tested by the traveling-wave method and non-resonant perturbation method respectively. The measurement data agree with the simulationresult.(3) Using the Christine 1D program in TWTCAD (a TWT simulation software),the variation of interaction characteristics with several parameters is analyzed. Nineexperimental tubes have been manufactured, and the hot test is finished in about oneyear. During this period, the tube design parameters were adjusted according to thesimulation and experiment results. At last, all targets are satisfied. Meanwhile, theavailability of the Christine 1D program in TWTCAD is verified. Although thesimulation result is not very precise, it still can provide a qualitative guidance to thedevice engineers.