Removing Particles From Surfaces Using Vacuum Electron Emission
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Small particulate matter in the micron and sub-micron range can be removed from surfaces by charging the particles by vacuum electron emission and subsequent removal of the particles from said surfaces by relatively high electric fields under vacuum. The figure shows a basic configuration, involving a substrate surface 1 (insulating or metallic) that has particles 2 on it, a vacuum gap between the surface and an insulated metallic collector electrode 3 and an illumination source 4. In a reasonably high vacuum, the vacuum gap provides a high dielectric strength to allow creation of high electric fields without sparkover. The dielectric breakdown strength of air reaches a minimum at a pressure much less that atmospheric. A high-quality vacuum allows making electric fields stronger than 1 MV/cm before field emission occurs.