| 摘要 |
<p>PURPOSE:To prevent deterioration in electron irradiation capacity during operation by providing an internal oxidation layer and a reduction agent diffusion control layer to a substrate metal. CONSTITUTION:A substrate metal 31 obtained in the form of cap with Ni ribbon including Mg and Si is subjected to the heat processing at 600-900 deg.C under the dry hydrogen ambient. Thereafter, the heat processing for 60sec at 1,000 deg.C under the ambient where a partial pressure of oxygen is specified by a mixed gas of CO and CO2, a temperature is raised up to 1,100 deg.C and heating is continued for 90sec while the mixed gas of CO and CO2 is rapidly exhausted. Thereby, a particle precipitation band 52 is formed like a line at the position of the depth of 2-5mum from the surface along the external circumference of substrate metal 31. The area, except for that coated with oxide for electron irradiation, is coated with resist and is etched in order to remove the resist. Thereby, evaporation of Mg from the side surface or surface of the area other than the region coated with oxide layer can be suppressed as much as possible and the substrate which maintains a reduction force for a long period can be obtained.</p> |
