The present invention provides an emitter, which comprises carbon nanotubes and is excellent in the efficiency of electron emission, and an X-ray tube comprising the same.

In a vacuum chamber (1), an emitter (3) and a target (7) are opposed to each other. A guard electrode (5) is disposed around an outer circumference of an electron generating portion (31) of the emitter (3). A supporting part (4) supports the emitter (3) movably in an end-to-end direction of the vacuum chamber (1). Reforming treatment is performed on the guard electrode (5) by operating the supporting part (4), moving the emitter (3) to an open end (21) side (non-discharge position) and applying a voltage to repeatedly effect discharge on the guard electrode (5) in a state where field emission from the electron generation portion (31) is suppressed. After the reforming treatment, the supporting part (4) is again operated. The emitter (3) is moved to an open end (22) side (discharge position) and placed in a state where field emission from the electron generation portion (31) is allowed.

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.

A vacuum container is configured so that an opening on one side and an opening on another side in the longitudinal direction of a cylindrical insulating body are sealed with an emitter unit and a target unit respectively; and a vacuum chamber is provided on the inner peripheral side of the insulating body. The emitter unit is provided with: a moving body located on the one side in the longitudinal direction in the vacuum chamber and supported so as to be movable in the longitudinal direction via a bellows; and a guard electrode located on the outer peripheral side of the moving body. An emitter section having an electron generating section is formed at a tip section of the moving body on the other side in the longitudinal direction by subjecting the surface of the tip section to film formation processing.

The invention relates to a metal jet x-ray tube which is less affected by the problem of the power density at the point of impact of the electron beam on the anode component than conventional tubes. For this purpose the metal jet x-ray tube has a metal jet (6) as anode component (7), which metal jet is so thin that an electron beam (4) impinging on the metal jet (6) is only partially decelerated by the metal jet. Furthermore a blade cathode is provided as a cathode component (3), which blade cathode comprises a cathode blade (10) directed with a slight inclination downwards in the direction of the liquid metal jet (6) of the anode component (7).

Provided is an X-ray generator including a thermal electron emission type X-ray generator configured to generate a negative high voltage and a filament current, a field electron emission type X-ray generator including an anode electrode to be grounded, and configured to use the negative high voltage to bias the cathode electrode, and a field emission current control unit configured to convert the filament current to generate an output voltage to be provided to a gate electrode of the field electron emission type X-ray generator and convert the filament current to fix, to a specific level, a level of an emission current flowing through the cathode electrode.

Disclosed is an X-ray generation apparatus for intra-oral X-ray imaging, a guide holder, and an X-ray imaging system comprising the same. The X-ray generation apparatus includes a body and a plurality of X-ray sources disposed in different positions of the body, and configured to irradiate X-rays to a field of view, wherein the body moves along a predetermined trajectory for the field of view.

In the present invention, a ferroelectric body is irradiated with ultraviolet light, and the ferroelectric body is caused to stably generate electric potential. A method for radiating charged particles, in which the UV-light-receiving surface of the ferroelectric body that receives UV light and is caused to generate a potential difference is irradiated with UV light having a wavelength not transmitted by the ferroelectric body, and charged particles are radiated from the charged-particle-radiation surface of the ferroelectric body, wherein the UV-light-receiving surface is irradiated with pulses of UV light at a peak power of 1 MW or greater. The pulse width of the UV light is measured in picoseconds (less than 1×10.sup.−9 seconds), and the UV pulses can be transmitted by fiber.

The X-ray tube disclosed herein includes an electron emission unit including an electron emission element using a cold cathode; an anode unit disposed opposite to the electron emission unit, with which electrons emitted from the electron emission unit collide; and a focus structure disposed between the electron emission unit and a target unit disposed on a surface of the anode unit that is opposed to the electron emission unit. The electron emission unit is divided into first and second regions which can independently be turned ON/OFF. The X-ray tube is focus-designed such that collision regions, at the anode unit, of electron beams emitted from the respective first and second regions substantially coincide with each other.

The present disclosure may provide a micro X-ray tube with a filter tube to filter X-rays and at the same time to serve as an insulator. For this, the X-ray tube may include a filter tube between a second electrode and a gate electrode, hence separating from each other. The second electrode may have a target and the gate electrode may accelerate an electron-beam to collide with the target. The filter tube includes an alumina (Al.sub.2O.sub.3). The target is inclined to allow the X-rays to be directed toward the filter tube.