Attenuation of electron gun generated surges in an electron beam evaporation system using ferrite beads

Vacuum breakdown is a very common problem during the operation of any electron gun, more so for e-guns used for vacuum evaporation. This not only spoils the coating or welding job but also causes damage to the electronics of the power system. This paper discusses an approach to attenuate the breakdown current near the gun itself, so that the surge does not propagate to cause any detrimental effect on the power source and thereby on the job. In this paper, ferrite beads on both the feed lines have been used to suppress the high frequency content and reduce the amplitude of the breakdown signal. An induction coil sensor has been designed to monitor the breakdown signal. The high frequency surge in the MHz range could be attenuated to a lower range of KHz by use of ferrite bead. A detailed quantitative analysis of the breakdown signal has been presented in this paper. ▸ Using spectral analysis, characteristics of a breakdown signal is identified. ▸ Characteristics of a breakdown signal is used to compute the value of inductance. ▸ To filter out high frequency components of the signal, required ferrite beads are used. ▸ Experimentally verified the smoothening of the breakdown signal using ferrite beads.