| 摘要 |
PURPOSE:To increase the quantity of X-ray and improve the life of a cathode of a tube by providing a plurality of controlling electrodes on the cathode side in addition to an electron emitting electrode and focusing electrode and controlling an electron beam through voltage applied to the controlling electrodes. CONSTITUTION:The first controlling electrode 6a, the second controlling electrode (shielding electrode) 17, and shielding electrode lead 18 are provided on the cathode side in addition to an electron emitting electrode and focusing electrode, and an electron beam from the cathode side to an anode is controlled through voltage applied to the plurality of electrodes. Thus the space charge near the cathode is kept in sufficiently high density, and the electric field near the cathode is greatly reduced. Accordingly the quantity of X-ray is increased and the life of the cathode of a tube is improved. |
