An Electron Gun Controller for a Small Electrostatic Electron Accelerator

Abstract

The Houghton College electrostatic electron accelerator uses a small Van de Graaff generator and an accelerator column made from alternating high-density polyethylene and aluminum rings to create a uniform electric field. The accelerator column is evacuated to about 10-6 torr by a rotary forepump and a diffusion pump. To produce the electrons, an electron gun made from a 3RP1 CRT is located inside the high voltage terminal. The electrodes of the electron gun require user-controlled voltages for the anode, focus and intensity grids. Since the gun is located inside the HV terminal, a microcontroller/amplifier circuit was designed to produce the required voltages and communicate with the user via a non-conducting, fiber optic RS232 link. The remote control system has been tested with the electron gun attached to the vacuum system.