AN ELECTRON SOURCE FOR WIDE RANGE PRESSURE GAUGE CONVERTER

The possibilities of constructing an electron source for a wide-range (10-7-760 Torr) vacuum gauge with one pressure gauge converter based on a direct-channel cathode and photocathode resistant to air at atmospheric pressure are investigated. It is shown that the use of a direct incandescent cathode is limited at an air pressure above 1 Torr due to the surface ionization of carbon dioxide contained in the air on the filament with the formation of negative ions. A number of materials for the photocade providing electron emission under the action of ultraviolet radiation (185, 254, 275 nm) have been studied. It has been established that a stable electron source can be created based on the photoemission of electrons from a boron or indium-based photocathode using a radiation source with wavelengths of 185 and 254 nm.