Subminiature Multibeam Cathode Structure and Fabrication Method
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
A subminiature multibeam cathode structure and technique for fabricating the structure are described herein. Fig. 1 depicts one cathode 10 and the heater 12 of a standard multibeam cathode. The substrate 11 is sapphire, and the cathode 10 and grid 14 are fabricated from a suitable metal. The grid 14 is isolated from the cathode 10 by a narrow channel 16 through the metal layer to the sapphire substrate 11. The device is heated from the back side by a thin-film heater 12 to a temperature of 800-900ŒC. The emission from the cathode 10 is cut off by a potential difference between the cathode 10 and grid 14 of 15-30 volts (Grid negative with respect to cathode). This structure makes use of the ability to form and machine ceramics in a multilayer sandwich and to drill small holes in the ceramic.