| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for cathode for electron tube by which cathode with extremely small emission slump even after the use at electric current density as high as 2-4A/cm<2> can be manufactured. SOLUTION: A cathode 8 for electron tube is constituted of a heater coil 1, a cylindrical sleeve 2 in which the heater coil 1 is built, a substrate 3 installed in the open part in one end of the sleeve 2, and an emitter 7 consisting of a barium-containing alkali earth metal oxide 5 and a terbium oxide 6. The emitter 7 is produced by coating the substrate 3 with a mixture of alkali earth metal carbonate which satisfies a/b <=2.3 (wherein a stands for the average particle size in the longer axis direction of unit particle of the alkali earth metal carbonate and b for the average particle size in the shorter axis direction) and terbium oxide and thermally decomposing the mixture in vacuum. |
