| 摘要 |
<p>A dispenser cathode is fabricated by sandwiching a reservoir 12 of electron emitting material between a perforated metal foil 11 and a support structure 13. The electron emitting material is in the form of a pellet of barium oxide impregnated with a wax or resinous material to minimize chemical reduction of the barium oxide in air. During tube bakeout or subsequently during cathode activation, the wax or resinous material evaporates and barium oxide migrates through the apertures to cover the surface of the foil in a uniform manner. The desired pattern of apertures in the foil is achieved by photolithography, or by forming the foil (e.g., by chemical vapor deposition, sputter deposition, evaporation, or sintering) on a substrate containing an array of protruding posts. With either technique for forming the apertures, a shadow grid can also be formed as an integral part of the cathode surface by depositing a layer of oxygen scavenging material such as zirconium or graphite on a selected portion of the cathode surface. <IMAGE></p> |
