| 摘要 |
PROBLEM TO BE SOLVED: To provide a microfocus X-ray tube with focusing efficiency of electron beams improved and preventing electrostatic charge on an insulator of a negative electrode due to reflected electron from a target. SOLUTION: As for an opening of a grid electrode constituting an electron focusing system 56 of the negative electrode 12, a G1 electrode 60 is to have a tapered face with its aperture getting larger as it gets away from a cathode 54, a G3 electrode 64 is to have a tapered face with its aperture getting smaller as it gets away from the cathode 54, and an aperture of a G2 electrode 62 is to be nearly the same as the minimum aperture of the G1 electrode 60 to improve focusing of electron beams running along an outside track away from a center axis 72. Further, a negative electrode cover 68 made of a metal material is arranged to cover an electron-focusing insulator 66 supporting the electron focusing system 56 to prevent reflected electron from the target 18 from colliding with an insulator 66a. COPYRIGHT: (C)2007,JPO&INPIT
|
