| 摘要 |
PURPOSE:To improve the emission characteristics of an electron gun by thermally decomposing under a reducing gas atmosphere having specific oxygen potential, the carbonate of a cathode structure having an oxide cathode obtained by thermally decomposing the carbonate. CONSTITUTION:Thermal decomposion of a cathode structure having an oxide cathode obtained by thermally decomposing carbonate, a heater for heating said cathode and an electron trap structure equipped with a grid electrode or an anode provided in opposition to said cathode structure is performed in a reducing gas atmosphere providing oxygen potential having a mixture of CO and CO2 where the partial pressure of the CO is ten times larger than that of CO2 under the whole pressure of CO and CO2 generated by the thermal decomposition less than 100Torr. Hereby, oxidation polution on the surface of a metal member near the cathode can be prevented, allowing the emission characteristics to be improved. |
