Electron Beam Emission System for Space Welding Based on Indirectly-Heated Bombardment Cathode

Abstract

An electron beam emission system developed for space welding and consisting of an indirectly-bombardment cathode fabricated using LaB6 was studied to improve the working life of the space welding electron gun. The energy transfer model of the indirectly-heated bombardment cathode was established based on the cooling effect of thermionic emission and the bombardment heating structure. The efficiency of the energy transfer model was verified by conducting emission tests and the differences between the test and theoretical values were analyzed. The designed electron beam emission system could emit 500 mA beam current in a stable manner at an acceleration voltage of 20 kV, and the diameter of the beam spot was less than 400 μm. The structure, indirectly heated by electron bombardment, exhibited a stable performance, could stabilize the working temperature of the cathode by exploiting the bombardment beam, and the total heating efficiency of the system could reach 76.04%.