| 摘要 |
PURPOSE:To emit sufficient thermoelectrons even if the filament temperature is low when a magnetron is driven at a low voltage by providing a specific impregnated type cathode. CONSTITUTION:A thermoelectron emitter 15 impregnated with barium oxide into porous tungsten is soldered to the outer periphery of a molybdenum tube 14 with an inner diameter of 5mm and an outer diameter of 6mm, for example, to form an impregnated type cathode 13. The cathode 13 is concentrically arranged outside a spiral filament 10, its lower section is connected to an end shield 11, and its upper section is arranged via a cavity of 0.3mm from an end shield 12. When the cathode with this structure is used, a magnetron is driven at a voltage of 340V, the emitter 15 is heated to 1150 deg.C, and a current of 1.8A flows in the filament 10, for example.
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