Study Of A Magnetic Injection Gun For Tereaherz Gyrotron Traveling Wave Tube

Gyrotron traveling wave tube(Gyro-TWT) is a kind of sub-millimeter amplifier which based on the theory of electron cyclotron maser, it’s an important part of the Gyrotron tubes. Because of the high requirement of the electron beam, there is a different meaning to design a Gyro-TWT electron gun. With the improvement of the frequency, to get an electron gun with high quality electron beam is more difficult.In this paper, a double anodes magnetic injection gun(MIG) is discussed in 2D and 3D. In 2D, Finite Difference Time Domain(FDTD) is used to do the research of the transverse velocity and the longitudinal velocity of the electron beam, the current and the magnetic field; in 3D, Finite Integration Time Domain(FITD) is used to study the motor processes of the electron beam, the electron distribution in the output window of the gun, and the simulation of non-axsymmetric structure. The main content of this paper is as follows: first, the theories of intense electron optics are deduced, based on Maxwell’s equations, axisymmetrical electrostatic field and magnetostatic field are deduced as well as electronic motion equations and electron trajectory equations. In the support of the theories, a Gyro-TWT MIG which is working in the frequency of 0.35 THz is analyzed and simulated. The ratio of transverse and longitudinal velocity is 1.2, the spread of the transverse velocity is 3.8%, the working current is 3A, the voltage ratio between the cathode and the first anode is 2.89, the compression ratio of the magnetic field is 32.8. The factors which affect the quality of the electron beam, such as the position of the cathode、the voltage between cathode and the anodes、the distribution and the value of the magnetic field and the structure of the anodes are discussed, and the results are presented in pictures. What’s more, the motion of electron beam、the cyclotron motion of a single electron and the distribution of electron beam in the output window are also discussed in the paper. Combined with the structure of confocal waveguide, the author makes a primary research on sector electron beam. Without the affection of the electron beam quality, part of section electron beam distributions are achieved. The angular deflection of the electron beam is been analyzed and modified. In this paper, the specific location of the electron beam is studied.