| 摘要 |
<p>PURPOSE:To have stable emission of current of approx. 50muA under 1X10Torr by subjecting an emitter of Nb carbide mono-crystals to a specific treatment. CONSTITUTION:In ethylene or other hydrocarbon gas (at 1X10<6>Torr), an emitter of Nb carbide mono-crystals are heated to 1400-1800'C for 5000 sec or longer. i.e., over 5000 L, where one L is equivalent to 1X10<-6>Torr.sec. Thereby a graphite film is formed on the surface. This is followed by evacuation to an extra-high vacuum (for ex., 1x10<-10> Torr), and a strong electric field over 10<3>V/cm is impressed. This causes change of the emission pattern, and gives stabilization of the emission current. Thereby stable operation is obtained such that short duration noise is below + or -0.2% and the drift is below + or -0.1%/hr even under the condition with a degree of vacuum of 1X10<-10>Torr and an emission current of 50muA.</p> |
