| 摘要 |
PROBLEM TO BE SOLVED: To prevent an electron beam irradiation area on a target from being bent by devising the shape of an opening in an X-ray tube provided with an electron gun having a structure wherein an opening of an Wehnelt electrode is unsymmetrical with respect to an electron emission body. SOLUTION: A long and slender coiled filament 16 is arranged in the long and slender opening 18a of the Wehnelt electrode. Two long sides 26a, 28a of the opening 18a are located in unsymmetrical positions with respect to the centerline in the width direction of the filament 16. The two long sides 26a, 28a are bent in the same direction respectively as viewed from the normal line direction of a surface of the Wehnelt electrode. Radii of curvatures R1, R2 of two long sides 26a, 28a differ from each other. Thereby, the electron beam irradiation area on the target becomes almost linear without being bent. COPYRIGHT: (C)2007,JPO&INPIT
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