Design W-band Extended Interaction Devices Uniform Magnetic Focusing Electronic Optical System

Electron optical system mainly is composed of the electron gun and magnetic focusing system, whose role is as an energy source of vacuum electronic devices, to provide to meet the application requirements of the electron beam, the electron gun is responsible for the electron beam generation, magnetic focusing system is responsible for making the electron beam focusing. Electron optical system have important applications in many aspects, such as high-power microwave source, particle accelerators, free electron laser. Due to rapid development of vacuum electronics technology, which go to the millimeter-wave submillimeter even terahertz band. The study of electron-optical system is facing with new opportunities and challenges. This thesis work mainly for extended interaction devices electron optical system carried out research and design, the main contents and conclusions are as follows:Electronic optical system uniform focusing magnetic field is designed for the W-band extended interaction device, which need the three coil and a pure iron realizing gradient uniform magnetic field distribution. First of all, according to the theoretical calculation, utilizing FEMM(Finite Element Method Magnetics) simulation software built and analysis the model for magnetic field; on the basis of the calculation of the magnetic field FEMM with electrostatic gun, using CST simulation software optimize the transmission of electron beam of high current density, high compression ratio in uniform focusing magnetic field. Results as following, for the electronic beam current, which focus electrodes influence on, which is one significance of the focus electrodes existing. For the focusing magnetic field, magnetic pole influence on magnetic field of transition region. For beam fluctuating, when the cathode emission surface radius is around 3 mm, fluctuation of electron beam is minimal. Finally, the work voltage in 14 to 17 kV, and cathode emission current density under the condition of less than 20 A/cm2. electronic beam launched by Pierce electron gun, in uniform focusing magnetic field, realize good transmission. Perveance of the gun is 0.175μP.The current density is 546.17A/cm2, compression ratio of the electronic beam is 33, and the electronic beam transverse longitudinal velocity ratio is 7.2%.According to optimization parameters of the electron optical systems, an extended interaction oscillator(EIO) with high current density electron gun working in the W-band is presented by theoretical study and simulation study in this paper. The rectangular coupled-cavity was employed as the slow wave structure of the EIO. The perveance of the electron gun is 0.175μP and the cathode emission current density is less than 20 A/cm2, the coupled cavity has nine period. PIC Simulation of the EIO shows that the beam-wave interaction efficiency is about 10.5%, and the microwave output peak power is over 1kW at 92.83 GHz.