CATHODE-GRID KNOT WITH FIELD-EMISSION CATHODE Russian patent published in 2018 - IPC H01J1/304 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to air-free electronic devices, including air-free devices of microwave range, which use field-emission cathode as current sources. Cathode-grid knot comprises field-emission cathode in form of needle with large aspect ratio geometric dimensions and control grid of conductive material with holes. Control grid is separated from cathode by air-free gap. In this case, surface of grid and surface, forming holes of the grid are covered with film of dielectric material. When voltage is applied to control grid is positive relative to the cathode, corresponding to the beginning of autoelectronic emission from the cathode, electrons from lateral surface near the apex of the point are deposited on sections of the grid covered with a film made of dielectric material and impart negative charge to it. Negative charge of film reduces the tension electric field on lateral surface of field-emission cathode and limits emission from those areas from which electrons hit the grid. As a result, emission angle from the tip of peak is reduced to values when all the cathode current without loss passes into the hole in the grid. As charge from dielectric film drifts, its potential rises, then leads to recovery of emission from side surface of autoemitter and to deposition of electrons on sections of the grid covered with dielectric film. Negative charge of film will increase again, which leads to limiting emissions from lateral surface of the tip, etc. This process is dynamic, self-regulating and installed in absence of current-gripping on the grid.

EFFECT: technical result is an increase in emission capacity of cathode, reliability of operation of cathode-grid knot of electronic device, and improvement the quality of electron beam by decreasing emission angle from the top of auto emitter.

1 cl, 2 dwg