Cold Cathodes Based on an Assembly of Microchannel Plates for Low-Power X-Ray Tubes

Abstract

t—A simple and economical method for manufacturing a cold cathode (electron generator) for a miniature and low-power X-ray emitter is described. The autoelectronic generator contains an assembly of two microchannel plates (MCPs) of the chevron type with an emissive carbon layer of Graphite 33 conductive glue, which contains carbon nanostructures (CNSs). The operating voltage does not exceed 2000 V. The dependence of the electron-generator output current on the distance between the MCPs in the assembly is determined. Thus, when the gap is increased from 0.2 to 0.63 mm the maximum DC current value increases from 0.65 to 4 μA; when the gap is further increased to 1.4 mm, the current increases to 4.5 μA. It is established that the maximum current of the electron generator in the pulsed mode of 53 μA is achieved if the first MCP in the assembly with a CNS layer at the input end is supplied with a pulse voltage of 800 V, a frequency of 2.3 kHz, and an off-duty ratio of 28, while a constant voltage of 1200 V is fed to the second MCP. In this case, the gap between the MCPs in the assembly is 1.4 mm.