Method for Evaluating Electron Beam Quality and Design of the Double-Cylindrical-Beam Gun

To evaluate the beam quality of an electron gun, beam waist, beam position, operating current, operating voltage, beam envelope, cross-section current distribution and cross-section macro particle distribution are generally observed by designers. The existing method to evaluate beam quality of multi-beam electron gun is inaccurate. This article investigates a new method for evaluating the quality of electron beams. In the method, The centroid of the cross-section current is defined to evaluate the beam trajectory. The current and macro particle are evaluated in radial and angular. A method of analyzing laminarity of the electron beam is introduced To verify the feasibility of the above method, a double-cylindrical-beam electron gun is designed. The evaluation for the beam quality can prove that the method is effective.