Study of the operating modes of the electrostatic lens of the welding electron gun

Abstract

The paper presents the results of a study of the operating modes of a technological electron gun used in installations for electron beam welding. The design of an electron gun, which is part of the ELA-15I power complex, is considered, and the results of modeling the accelerating gap for a new design gun with an accelerating voltage of 120 kV are presented. The current-voltage characteristics of the gun operation were experimentally obtained at different temperatures of the main LaB6 cathode. For this, the beam current was recorded at different values of the control electrode potential. A mathematical model of the accelerating gap was implemented, which makes it possible to analyze the shape of the electron beam in the region of the first lens. Using a mathematical model, the shapes of the electron beam were calculated for various operating modes of the gun, and the characteristic transverse size of the beam in the crossover was determined. The beam diameter and the angle of convergence in the area of focusing the beam on the product were determined experimentally. Conclusions were made about the equality of the crossover diameters of the full-scale and mathematical models, as well as about the sufficient coincidence of the experimental and calculated volt-ampere characteristics. The design of the accelerating gap of the ELA-15 gun was optimized with an increase in the accelerating voltage from 60 kV to 120 kV. The optimization results are shown for the original and modified design in the form of a comparison of the patterns of the distribution of the electrostatic field strength and a comparison of the current-voltage characteristics.