Patent ID: 8908833

Claim:
An X-ray generator comprising: a cathode for generating electrons; a rotating anode having a cylindrical electron impingement surface, an X-ray focal point being formed by a region in which said electrons impinge upon the electron impingement surface; and a Wehnelt electrode for imparting an electric field to the electrons emitted from said cathode; wherein said Wehnelt electrode has a field formation surface for forming said electric field, and an electron passage aperture formed by the field formation surface; the field formation surface of said Wehnelt electrode is inclined with respect to a plane tangent to an outer circumferential surface of said rotating anode at the center of said X-ray focal point, said Wehnelt electrode has a first space provided in a position near said electron passage aperture, and a second space in a position distant from said electron passage aperture, the second space being connected to said first space and having a volume smaller than that of the first space; a portion of said cathode is in said first space, and the remainder of said cathode is in said second space; a first X-ray blocking member is removably attached to a wall at a boundary portion between said first space and said second space; and a line normal to the outer circumferential surface of said rotating anode at the center of said X-ray focal point passes through said first space and intersects with said first X-ray blocking member.