PHOTOCATHODE DEVICE THAT REPLENISHES PHOTOEMISSIVE COATING

摘要

A photocathode device may replenish its photoemissive coating to replace coating material that desorbs/evaporates during photoemission. A linear actuator system may regulate the release of a replenishment material vapor, such as an alkali metal, from a chamber inside the photocathode device to a porous cathode substrate. The replenishment material deposits on the inner surface of a porous membrane and effuses through the membrane to the outer surface, where it replenishes the photoemissive coating. The rate of replenishment of the photoemissive coating may be adjusted using the linear actuator system to regulate performance of the photocathode device during photoemission. Alternatively, the linear actuator system may adjust a plasma discharge gap between a cartridge containing replenishment material and a metal grid. A potential is applied between the cartridge and the grid, resulting in ejection of metal ions from the cartridge that similarly replenish the photoemissive coating.

主权项

1. An apparatus, comprising:
a first chamber comprising a porous cathode substrate, the porous cathode substrate comprising an outer wall surface and an inner wall surface; a second chamber housing a replenishment material, the second chamber separated from the first chamber by a first wall, the first wall comprising an orifice that allows a vapor of the replenishment material to move into the first chamber from the second chamber; and a linear actuator system configured to convert the replenishment material into vapor or ions, wherein at least some of the replenishment material vapor or ions travel through the inner wall surface of the porous cathode substrate to the outer wall surface of the porous cathode substrate, thereby replenishing a photoemissive coating.