To provide an electron source enclosing vacuum airtight vessel by which a thickness of a getter box to house a getter whose inside can be held in a high vacuum can be thinned.
A getter box lengthwise in the illustrated vertical direction is arranged so as to project further leftward from the left end of a cathode base board 1. This getter box is formed by being surrounded by a bottom plate 3b and a side plate 3a. A nonevaporating getter 11 is housed on the under surface side of the cathode base board 1. The nonevaporating getter 11 has in the center a resistance heating body 11b such as a nichrome wire heated by current conduction, and an almost columnar and long nonevaporating getter body part 11a is formed by sintering power composed of Zr-Al alloy on its periphery.
TANAKA GENTARO
KOGURE YUICHI
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