| 摘要 |
PURPOSE:To achieve a focal distribution for good resolving power and high X-ray output, by providing inner walls opposed to each other across an electron beam restriction hole in the direction of rotation of an anode target and different from each other in thickness. CONSTITUTION:A cup-shaped convergence electrode 202 is disposed around a cathode filament 201 and a filament cover 212. A filament pillar 211 is secured with an electrically-insulating support to the convergence electrode 202. The electrode 202 has an electron beam restriction hole 207 opposed to the electron emission surface 201a of the cathode filament 201. Inner walls 214, 215 opposed to each other across the electron beam restriction hole 207 in the direction of rotation of an anode target 3 are made different from each other in thickness. As a result, a nonuniform X-ray intensity distribution asymmetric in the direction of the minor side of the cross section of the electron beam restriction hole 207 is achieved to provide an X-ray focus good for an X-ray image and an X-ray output.
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