DIRECT HEATED CATHODE STRUCTURE

摘要

PURPOSE: To provide a direct-heated cathode structure with stable support structure and capable of emitting rapid thermions by constituting its structure in which one pellet has at least three filaments at predetermined angles and intervals. CONSTITUTION: A direct-heated cathode structure comprises a porous pellet 100 impregnated with cathode material, and a heater means in contact with the pellet 100. The heater means involves at least three filaments 200, which are in direct contact at their one-side ends with the outer surface of the pellet 100 at predetermined intervals held between one and the next. The volume of the pellet 100 should fall within the range between 0.012 and 1.0 mm<3> . The filaments 200 are preferably provided in four from various points of view. The filaments 200 preferably measure 0.02 to 0.1 millimeters in diameter. The filaments 200 may be passed through the pellet 100 or welded to the sides of the pellet 100.