| 摘要 |
<p>PURPOSE:To form a heater for an indirectly-heated cathode, with a high mechanical strength and a long burn-out life, by forming a heating unit winding a wire of a low specific resistance on a wire rod of a high specific resistance, and covering the surface of the heating unit with a heat-resisting insulator. CONSTITUTION:A titanium wire is used for a core rod 44 of a high specific resistance, over which a tungsten wire 12 is wound as a wire of a low specific resistance. Then some reforming and alumina coverage are provided. Because the core is the wire rod 44 of a high specific resistance, and heater is of a high mechanical strength, reducing cracking of alumina coverage which may occur while handling in transport or welding the heater foot, etc., and restraining burn-out accidents from a short circuit.</p> |
