Electron Emission Properties and Surface Atom Behavior of an Impregnated Cathode Coated with Tungsten Thin Film Containing Sc₂O₃

Abstract

A new cathode has been developed which shows similar electron emission characteristics as a previously reported Sc2O3 mixed matrix impregnated cathode (Sc2O3 MM Cathode). Contrary to the Sc2O3 MM cathode, the new cathode is resistive to prolonged heating at high temperatures and to ion bombardment. This has been made possible by applying to a standard impregnated cathode a tungsten thin-film containing about 5 weight percent Sc2O3. The electron-emission property is found to be strongly linked to the surface atom composition as well as to the distribution of surface atoms.

Low‐energy electron diffraction study of atomic structure of Sc–O/W(100) surface acting as Schottky emitter at high temperatures

“…Regarding the emitters used in cathode ray tubes, the role of Sc 2 O 3 in scandate cathodes 2 and Sc 2 O 3 dispersedoxide cathodes 3 has been studied to some extent. Kultashev and Makarov 4 reported that a preferential reduction in the work function of an Sc-O/W system occurs for the W(100) surface by heating to ¾1100 K. Zagwijn et al 5 investigated the effects of scandium and oxygen in scandate dispenser cathodes.…”

Preparation and characterization of scandia-doped tungsten powders prepared by a spray-drying method

“…There are many remarkable advantages of scandate cathode compared with the ''M'' type cathode, i.e., the working temperature of scandate cathode can be reduced by 100-150°C, which is highly significant in vacuum electronic devices. It was found in previous work that the raw powder properties, for example morphology and particle size, greatly affected the emission property of the cathode [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Emission property of scandia and Re doped tungsten matrix dispenser cathode

“…An increase of electron emission current density at a given operating temperature is one of the main goals of thermionic cathode improvement for different applications in vacuum tubes. For thermionic cathodes, one of the most prospective candidates for the continuously improved vacuum devices in high emission current is scandate cathode [1][2][3][4][5][6][7][8]. However, the problems preventing high emission scandate cathodes from being widely utilized normally come down to a possible non-uniformity in emission, the susceptibility to ion bombardment damage and the poor reproducibility [9].…”