Effect of Thickness and Radial Position of Aperture in a Pole Piece in Focusing of Multibeam Electron Gun

A four-beam electron gun has been designed using OPerating environment for Electromagnetic Research and Analysis (OPERA) 3-D to demonstrate the dependence of beam focusing on the thickness and the radial position of anode aperture in a pole piece with reference to the gun axis. The study is important in the sense that focusing the off-axis electron beamlets are a bit difficult with a common focusing system. The OPERA simulated results have been also compared with computer simulation technique simulated results. An example of four-beam electron gun to deliver a total of 428-mA (107 4) current at 6-kV beam voltage has been considered for carrying out the aforementioned study. The four electron beamlets are generated through four individual cathodes, surrounded by electrically isolated four beam focusing electrode and corresponding four individual anodes and a common focusing system.