Optimization of closed ion source for a high-sensitivity residual gas analyzer

Abstract

A closed ion source (CIS) has been optimized by investigating the effect of electron entrance slit size and the effect of mesh in the slit. A stainless steel mesh was placed on the electron entrance slits for a uniform potential distribution inside the CIS anode. Sensitivity of the closed ion sources having four different slit sizes with and without the mesh was compared using mass spectra of SF6 gas (97% He gas base) introduced into the CIS anode through a needle valve. For each CIS, isolation of anode potential with a mesh in the slit exhibited a significant sensitivity enhancement, but ion current measured directly behind each CIS showed negligible mesh effect. In order to elucidate the mesh effect, electron trajectories were simulated inside the anode. The computer simulation shows that, with mesh in the slit, more electrons are focused to a central region of the anode. This suggests ions generated in the CIS with mesh should have higher probability of passing through the quadrupole mass filter.

Diagnostic Techniques for Electrical Discharge Plasma Used in PVD Coating Processes

“…Gas ion sources with a closed electron current are an effective tool for the implementation of ionic surface treatment processes [88][89][90][91][92]. Technological ion sources are used for cleaning and activating the surface of products before applying thin-film coatings, ion assistance in the processes of coating deposition, ion-beam etching, and shaping.…”