THE DYNAMIC, SIMULTANEOUS IMAGING OF BOTH PHOTON-INDUCED AND FIELD-INDUCED ELECTRON-EMISSION FROM ELECTRON PINHOLES IN PLANAR VACUUM-INSULATED HV ELECTRODES

Details are given of a new photo-field electron emission microscopy te chnique that has been developed for the dynamic imaging of the prebrea kdown electron emission processes that occurs on the surface of vacuum -insulated high-voltage electrodes. This new instrument can operate in : (a) a field-electron emission mode, (b) a photo-electron emission mo de, and (c) the combined field- and photo-electron emission mode. Typi cal results obtained from the early application have confirmed the ear lier finding that the prebreakdown electrons are emitted from isolated particulate surface structures on the surface of an electrode. These findings have also revealed that there are two types of associated emi ssion process, i.e. a ''surface'' and an ''edge'' process. This succes sful early application has demonstrated the potential of this techniqu e for the fundamental study of the physical origin of the prebreakdown electron emission from planar HV electrodes.