| 摘要 |
PROBLEM TO BE SOLVED: To enhance the S/N ratio of X rays generated and emitted. SOLUTION: A center axis of a target 4 and that of a hood electrode 5 mounted on an end portion 40 of the target 4 so as to cover an X-ray generating surface 41 are adapted to be substantially normal to an electron incoming axis (electron incoming track 1e) from an electron gun part 2 and to be substantially parallel to an X-ray outgoing axis (X-ray outgoing track lx) from an X-ray outgoing window 32. By providing an inwardly projecting limit projection part 53 on an inner surface portion of an X-ray outgoing port 51 in one end of the tubular hood electrode 5, the track of X rays outgoing from an internal space in the hood electrode 5 to the exterior is limited to reduce noise components of the X rays, and thus its S/N ratio can be enhanced.
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