Emitter (3) and target (7) are arranged so as to face each other in vacuum chamber (1), and guard electrode (5) is provided at outer circumferential side of electron generating portion (31) of emitter (3). Emitter (3) is supported movably in both end directions of vacuum chamber (1) by emitter supporting unit (4) having movable body (40). To perform regeneration process of guard electrode (5), emitter is moved to no-discharge position by operating emitter supporting unit, and state in which field emission of electron generating portion (31) is suppressed is set, then by applying voltage across guard electrode (5), discharge is repeated. After regeneration process, by operating emitter supporting unit again, emitter is moved to discharge position, and state in which field emission of electron generating portion (31) is possible is set with movement of movable body (40) toward the other and side being restrained by movement restraining unit (6).

Opening edge surface (45a) of an emitter supporting unit female screw bore (45) provided at an emitter supporting unit (4) extends along radial direction of the emitter supporting unit female screw bore (45). An emitter supporting unit operation hole (32) provided at a flange portion (30a) of a vacuum enclosure (11) has shape into which one selected from a position adjustment shaft (6) and a pressing shaft (9) can be inserted from their shaft tip sides. The position adjustment shaft is provided, on an outer circumferential surface of its tip (61), with a tip side male screw portion (61a) that can be screwed into the emitter supporting unit female screw bore (45). The pressing shaft has, at its tip (91), a tip surface (91a) having a larger diameter than an opening diameter of the emitter supporting unit female screw bore (45) and extending along radial direction of the pressing shaft.

Emitter (3) and target (7) are arranged so as to face each other in vacuum chamber (1), and guard electrode (5) is provided at outer circumferential side of electron generating portion (31) of emitter (3). Emitter (3) is supported movably in both end directions of vacuum chamber (1) by emitter supporting unit (4) having movable body (40). To perform regeneration process of guard electrode (5), emitter is moved to no-discharge position by operating emitter supporting unit, and state in which field emission of electron generating portion (31) is suppressed is set, then by applying voltage across guard electrode (5), discharge is repeated. After regeneration process, by operating emitter supporting unit again, emitter is moved to discharge position, and state in which field emission of electron generating portion (31) is possible is set with movement of movable body (40) toward the other end side being restrained by movement restraining unit (6).

An X-ray tube comprises a vacuum vessel; a cathode and an anode fixedly disposed inside the vacuum vessel; and a rotary mechanism that rotates the vacuum vessel. The cathode is disposed on the circumference with the rotary shaft of the rotary mechanism as its center and includes a plurality of cathode parts that can individually be turned ON/OFF. The anode includes parts opposite to the plurality of cathode parts, respectively.

Disclosed is an electron beam generation source including: an electron discharge part extending on a desired axis and configured to discharge electrons; a movable part connected to one end of the electron discharge part; a support part configured to support the movable part to be movable along the axis; and a tension holding part configured to hold tension of the electron discharge part by applying a pressing force or a tensile force to the movable part. The movable part and the tension holding part are disposed on the axis.

An electric field emission device includes a vacuum vessel configured to include a vacuum chamber; an emitter positioned on one side in an axial direction of the chamber and including an electron generation portion facing another side in the axial direction; a target positioned on the other side of the chamber and facing the emitter; a guard electrode that is a cylindrical body, is fixed to the vacuum vessel, and has an opening portion; a support to move the emitter in the axial direction on an inner side of the guard electrode; and an electric field shield body formed of a conductor connected to the guard electrode. The electric field shield body partially overlaps the opening portion on a projection plane in the axial direction, and is formed in a shape partitioning the opening portion into a plurality of areas.