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Subminiature Multibeam Cathode Structure and Fabrication Method

IP.com Disclosure Number: IPCOM000038474D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Caswell, NS: AUTHOR [+2]

Abstract

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.

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Subminiature Multibeam Cathode Structure and Fabrication Method

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 800-900OEC. 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. The structure is illustrated in Fig. 2. The small cathode ceramic structure shown in the center of Fig. 2 consists of two layers of ceramic and 3 layers of metal. The top layer is the grid plane, the center is the cathode lead, one lead for each cathode, and the bottom layer is the heater metallurgy. Electrical connections to the tube pins are made by an outer ceramic layer which is metallized and patterned. Small wires are used to connect the two ceramic layers, and to connect the outer ceramic layer and tube pines. The outer wires are welded in place, while the inner connections can be made by brazing with a hi...