Design And Simulation Of The Electron Optical System Of W Band Extended Interaction Klystron(EIK)

W-band millimeter wave is one of the atmospheric windows, whose wavelength is between microwave and optical wave. It is possessed of properties of millimeter wave and infrared. W-band microwave device has been widely used in radar guidance,electronic countermeasure and other applications. Because of its characters of high power capacity, longevity and high reliability, vacuum electronic devices are widely,among which especially the Extended Interaction Klystron(EIK) gains widespread applications due to its high power, high efficiency, high gain and easy control of self-excited oscillation.EIK mainly are made up of 4 parts, which include the electron optical systems, the high frequency system, output and input system and the cooling system. The energy of EIK comes from the electron beam, so the electron beam’s voltage and current density,waist radius and laminar flow decide the performance of EIK. Research on electron optical systems in the design of EIK has the vital significance. Electron optical system mainly includes 3 components, the pierce gun, magnetic focusing system and the depressed collector. Its main function is to study the electronic injection forming in the electron gun, how it stably goes through a beam tunnel at the high frequency system under the action of magnetic focusing system, and its divergence in the collector.This work studies the W-band EIK electron optical system, the parameters of which are as follows: perveance is 0.1449, the current of electron beam is 0.35 A, the beam waist radius is 0.3mm, and the transmission length of the electron beam is longer than 50 mm. It has the characteristics of high voltage electron beam, high density current,small waist beam radius and long transmission. The formation, focus and stable transmission of high current density electron beam in high frequency system is the main focus of design.Convergence electron beam projector has been used to analyze the theory of the formation, focus and transmission of electron beam. Then Iterative method has been used to calculate the initial parameters, which can be substituted in ORION tools for the design of anode and focus. Finally, using 2D ORION tools design the structure of electron beam projector. In the design of focusing system, because of the high frequency of W-band waveband and the length of high frequency system, this focusing system uses uniform focusing magnetic field formed in Uniform permanent-magnetic Field produced by Permanent Magnet Rings. Pierce electron gun、Uniform permanent-magnetic and the collector are checking calculation by CST.