| 摘要 |
PROBLEM TO BE SOLVED: To supply thorium to a leading end portion of a cathode with electron-emitting substance added thereto more reliably.SOLUTION: The method for electron-emitting substance supply in a cathode with electron-emitting substance added thereto comprises: a reaction (1) where ThOand DyOreact with each other at an interface to produce (Th,Dy)O; a reaction (2) where (Th,Dy)Ois reduced by W to produce Th and Dy, and Th and Dy diffuse towards a leading end portion of the cathode; and a reaction (3) where Dy having diffused so reduces ThOat its destination to produce Th and DyObecause of a smaller standard formation free energy of Dy, and Th diffuses towards the leading end portion. The reactions (1), (2) and (3) are repeated in this order, while Th is supplied to the direction towards the leading end portion. |
