INDIRECTLY HEATED CATHODE STRUCTURE

摘要

PURPOSE: An indirectly heated cathode structure is provided to prevent current leakage between the heater and cathode even at a high temperature of 1400°C or higher. CONSTITUTION: An indirectly heated cathode structure comprises an electron emission member(21) for emitting thermal electron when heated; a base metal(22) including a fixed portion(22a) where the electron emission member is mounted, and a skirt portion(22b) extended downward from an edge of the fixed portion; a heater(23) incorporated into the base metal, and which has a diamond insulation layer(23a) formed at the outer periphery of the heater; and a support member(24) for supporting the heater. The diamond insulation layer has a thickness of 2μm or higher.