Conducted interference on electron gun power supplies of DC EB accelerator

Internal electromagnetic interference produced by a 3MeV, 10mA industrial electron beam accelerator is presented in this paper. Accelerating potential for this accelerator is generated by a parallel coupled voltage multiplier based high voltage power supply. Electron beam is produced by an electron gun using a thermionic emitter. The electron gun, which is located at the high voltage terminal of the accelerator, has to be powered by isolated power supplies floating at the accelerating potential in the order of 3MV. Operating power for the power supplies are extracted from the multiplier column itself. At full terminal voltage, 1000J energy is stored in the terminal capacitance. During occasional electrical breakdowns in the system, the stored energy is released creating high frequency, high current transients in the frequency range of several MHz. The floating power supplies are subjected to severe electromagnetic interference during the discharges. This paper describes some of the identified breakdown pathways, estimation of associated conducted stresses on the power supplies and protection methods.