| 摘要 |
PROBLEM TO BE SOLVED: To provide an X-ray tube having a cathode structure capable of making the electronic density distribution of a focus point surface higher toward the center with a focus point temperature set at a specified value or lower. SOLUTION: A CNT (carbon nanotube) 4 of an electric field emission type electron source is formed in a convex shape in one direction at a cathode 2 close to which a flat and mesh type gate electrode 3 is arranged. A negative high voltage is impressed on the CNT 4 from a high voltage source 7 to the cathode 2, and a positive voltage is impressed on the gate electrode 3 from a gate power source 6 to the CNT 4. Electrons are irradiated with higher electron density compared with a peripheral part from the center of the CNT 4, and focused and collide on the target surface of a rotating anode 1 applied with the positive high voltage from the high voltage source 7. The density distribution of electrons colliding with the target surface is narrow in width becoming higher toward the center at the focus point. COPYRIGHT: (C)2005,JPO&NCIPI
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