METHOD FOR REDUCING FLUCTUATION OF CUT-OFF VOLTAGE, CATHODE FOR ELECTRONIC TUBE, AND METHOD FOR MANUFACTURING CATHODE FOR ELECTRONIC TUBE

摘要

A method for reducing fluctuation of cut-off voltage of a cathode for an electronic tube in which a metal layer (9) is formed by heating on a surface (7a) of the cathode base body (7) and is used to protrude a cathode base body (7), an electron emissive material layer (11) is formed on the front side (7a) of the cathode base body (7) directly or via the metal layer (9), and a heating means (5) is provided for emitting thermoelectrons from a front side (11a) of the electron emissive material layer (11) by heating the electron emissive material layer (11). The front side (11a) of the electron emissive material layer (11) is deformed and protruded forward by the length of reduction of the consumed front side (11a) of the electron emissive material layer (11) because of the forward protrusion/deformation of the cathode base body (7) caused by the metal layer (9) formed by heating by the heating means (5).