Research On The Electron Optics Of Sheet Beam Klystron

Research results and some conclusions of electron-optical system of sheet beamklystrons (SBK) are presented in this dissertation.First of all, the essential theories of sheet electron beam are summarized. Startingfrom the electronic equations of motion in Cartesian coordinate system, we havediscussed separately the track equation and stability conditions of sheet electron beamin uniform magnetic field and periodic cusped magnetic field(PCM).Secondly, platforms of electron-optical system of sheet beam klystron have beenestablished and the related electron-optical software tools are introduced. We explainin detail how to use the software including EGUN, SUPERFISH, MAFIA, MAGICand CST PARTICLE STUDIO in this dissertation.Thirdly, the electron-optical system of an X-band 100-MW sheet beam klystronis designed: the rectangular sheet electron beam is generated by using cylindercathode with rectangular cut perpendicular to the electron beam; rectangular sheetelectron beam is focused with a structure of four magnets added in the general closedPCM configuration.Fourthly, the 2D simulations of electron-optical system ofsheet beam klystronare finished. Generally speaking, the height of the sheet electron beam (verticaldirection)is much smaller than the width (horizontal direction), so we can supposethat the electron beam is infinite in the horizontal direction. Consequently, the 2Dsimulations of electron-optical system are finished to save simulation time in thisdissertation. As a result, we get the elementary data of electron-optical system.Finally, the 3D simulations of electron-optical system of sheet beam klystronsare finished. On the base of 2D simulations, we have performed 3D simulations of electron-optical system and the results of simulation indicate:(1) In the case of setting ideal emitting surface, the magnetic amplitude offocused electron beam and some characters (such as ripple wavelength) of electronbeam agree with the theoretical values. Meanwhile, the beam transmission of 100% ina 600-mm distance is obtained.(2) In the case of the PCM fields added to the electrons emitted by the electrongun in this dissertation, the poor performance of electron trajectory is found, withonly 92.5% transmission in a 600-mm distance; with an increase of the magnitude ofmagnetic field from 0.0422 T to 0.074T, the beam transmission of 99.6% in the samedistance can be obtained.