A Novel Beam Forming Electrode for Sheet Beam Electron Gun

A novel beam focusing electrode (BFE) is proposed for an electron gun to form a sheet electron beam. The proposed BFE is in the shape of an elliptical ring and is defined by the parameters of height and the lengths of the major and minor axis. The BFE is suitable for microfabrication and can be designed to form a sheet electron beam from either a rectangular cathode or circular cathode. A thermionic electron gun with a circular-cylindrical cathode is then designed based on the proposed BFE. CST particle studio is used to determine the electron beam trajectory and to achieve a sheet electron beam with beam current of 20 mA, voltage of 4000 V, and cross-section size of 0.75 mm×0.15 mm. The fabrication and assembly of the thermionic electron gun are also briefly described.