| 摘要 |
PURPOSE:To aim at obtaining higher brightness and securing a long life of an electron gun by specifically setting up the axial bearings of a cathode made of monocrystal LaB6 and forming its tip into a flat having the specific diameter. CONSTITUTION:The axial bearings 3 of a flat cathode of LaB6 are set up at (100) while its tip flat area 4 is formed into a flat having the diameter of 30- 100mum. Thereby, in the flat cathode having the bearings (100), its tip is unlikely to be deformed by evaporation so that a change of brightness due to aging is little thus making said cathode to be of a long life. Also, by forming its tip flat into the flat having the diameter of 30-100mum, evaporation speed is lowered thus maintaining its tip surface for a long time while preserving high brightness and a long life. |
