| 摘要 |
PURPOSE:To provide a cathode structure which enables improvement of its initial and long-period electron discharging characteristics. CONSTITUTION:¦A cathode sleeve material 32 made of a nickel-chromium alloy is prepared, and subjected to heat treatment at 1,000 deg.C for 30min in a moistened atmosphere of hydrogen with a dew point of 20 deg.C so as to make a cylindrical blackened cathode sleeve 32 coated with a blackened layer 32a consisting of chromium oxide. Next, a base metal 31, the cylindrical blackened cathode sleeve 32 and a cylindrical reflecting member 35 are welded 36 to each other at a plural number of close contacts 36. By the means mentioned above, the member 35 having a given heat radiation peak, the sleeve 32 and the base metal 31 can be assembled into a cathode structure in such a manner that the upper end of the sleeve 32 doesn't protrude from the top surface of the base metal 31. Besides, such a cathode structure can be assembled after blackening only the sleeve 32. Consequently, a cathode structure with an exceptionally excellent characteristic is obtained. |
