W-band extended interaction device uniform magnetic focusing electronic optical system

Uniform magnetic focusing system adopts three coil and a pureironto realize gradient uniform magnetic field distribution. The model of magnetic field is built and analyzed by utilizing FEMM (Finite Element Method Magnetics) simulation software, according to the theoretical calculation of the electrostatic gun with uniform focusing magnetic field. CST simulation of the electron gun shows that the perveance of the electron gun is 0.175 P and the cathode emission current density is less than 10 A/cm2 and the anode voltage is 17 kV, under conditions of the magnetic field 0.7 T. CST simulation software optimizes the transmission of electron beam to get the results. The results shows that gun parameter compression ratio is about 32, the beam current density is 343.17 A/cm2, and the electronic beam transverse longitudinal velocity ratio is 7.2%.