| 摘要 |
<p>PURPOSE:To obtain an indirectly-heated cathode having a short temperature drop zone (end cooling zone) generated at the end of the cathode due to heat absorption through a support body, and ensuring high heating efficiency. CONSTITUTION:A coil heater 5 comprising a heater wire 3 and an insulation layer 4 is wound around a core 2, while a coil cathode 8 comprising a fine metal wire 6 and an electron emission material layer 7 is wound around the core 2 adjacent to the coil heater 5. According to this construction, the heating value of the coil heater 5 is large, and the coil cathode 8 is heated by the coil heater 5 from two directions.</p> |
