A high-power microwave (HPM) vacuum tube source and method of precise coaxial alignment of the field emission (FE) cathode, cylindrical RF generating tube and magnet field includes positioning a low-power thermionic emission (TE) cathode inside the FE cathode in a “cathode-in-cathode” arrangement. With the HPM source under vacuum and the FE cathode deactivated, the TE cathode emits a surrogate electron beam through the generating tube. Measurement circuits measure the surrogate electron beam's position with respect to a longitudinal axis fore and aft of the generating tube. The measurements circuits may, for example, be a repositionable fluorescent target or electric field sensors embedded in the cylindrical RF generating tube. The coaxial alignment of the primary cathode, cylindrical RE generating tube and magnet is adjusted until the position of the surrogate electron beam satisfies a coaxial alignment tolerance.

A high-power microwave (HPM) vacuum tube source and method of precise coaxial alignment of the field emission (FE) cathode, cylindrical RF generating tube and magnet field includes positioning a low-power thermionic emission (TE) cathode inside the FE cathode in a “cathode-in-cathode” arrangement. With the HPM source under vacuum and the FE cathode deactivated, the TE cathode emits a surrogate electron beam through the generating tube. Measurement circuits measure the surrogate electron beam's position with respect to a longitudinal axis fore and aft of the generating tube. The measurements circuits may, for example, be a repositionable fluorescent target or electric field sensors embedded in the cylindrical RF generating tube. The coaxial alignment of the primary cathode, cylindrical RE generating tube and magnet is adjusted until the position of the surrogate electron beam satisfies a coaxial alignment tolerance.

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.

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.

A field emission cathode device and formation method involves a rotating field emission cathode including a field emission material deposited on a surface thereof, the field emission cathode rotating about an axis and being electrically connected to ground, and a planar gate electrode extending parallel to the surface of the rotating field emission cathode and defining a gap therebetween. A gate voltage source is electrically connected to the gate electrode and is arranged to interact therewith to generate an electric field, with the electric field inducing a portion of the surface of the rotating field emission cathode adjacent to the gate electrode to emit electrons from the field emission material toward and through the gate electrode.

A field emission cathode device and formation method involves a rotating field emission cathode including a field emission material deposited on a surface thereof, the field emission cathode rotating about an axis and being electrically connected to ground, and a planar gate electrode extending parallel to the surface of the rotating field emission cathode and defining a gap therebetween. A gate voltage source is electrically connected to the gate electrode and is arranged to interact therewith to generate an electric field, with the electric field inducing a portion of the surface of the rotating field emission cathode adjacent to the gate electrode to emit electrons from the field emission material toward and through the gate electrode.

A field emission cathode device comprises a field emission cathode including a cylindrical substrate and a field emission material deposited on a cylindrical surface thereof. The field emission cathode defines a longitudinal axis. A solenoid extends concentrically about the cylindrical surface, and defines a gap therebetween. The solenoid defines opposed open ends perpendicular to the longitudinal axis. A current source directs a constant polarity (DC) current to the solenoid, that forms a magnetic field along the solenoid. A gate voltage source electrically connected to the solenoid or the field emission cathode interacts therewith to generate an electric field inducing the field emission cathode to emit electrons from the field emission material into the gap. The emitted electrons are responsive to the magnetic field to spiral within the gap and about the longitudinal axis, in correspondence with the current flow in the solenoid, through the first open end of the solenoid.

A field emission cathode device comprises a field emission cathode including a cylindrical substrate and a field emission material deposited on a cylindrical surface thereof. The field emission cathode defines a longitudinal axis. A solenoid extends concentrically about the cylindrical surface, and defines a gap therebetween. The solenoid defines opposed open ends perpendicular to the longitudinal axis. A current source directs a constant polarity (DC) current to the solenoid, that forms a magnetic field along the solenoid. A gate voltage source electrically connected to the solenoid or the field emission cathode interacts therewith to generate an electric field inducing the field emission cathode to emit electrons from the field emission material into the gap. The emitted electrons are responsive to the magnetic field to spiral within the gap and about the longitudinal axis, in correspondence with the current flow in the solenoid, through the first open end of the solenoid.

A light modulated electron source utilizes a photon-beam source to modulate the emission current of an electron beam emitted from a silicon-based field emitter. The field emitter's cathode includes a protrusion fabricated on a silicon substrate and having an emission tip covered by a coating layer. An extractor generates an electric field that attracts free electrons toward the emission tip for emission as part of the electron beam. The photon-beam source generates a photon beam including photons having an energy greater than the bandgap of silicon, and includes optics that direct the photon beam onto the emission tip, whereby each absorbed photon creates a photo-electron that combines with the free electrons to enhance the electron beam's emission current. A controller modulates the emission current by controlling the intensity of the photon beam applied to the emission tip. A monitor measures the electron beam and provides feedback to the controller.

The purpose of the present invention is to provide an emitter that is made of hafnium carbide (HfC) and that releases electrons in a stable and highly efficient manner, a method for manufacturing the emitter, and an electron gun and electronic device in which the emitter is used. In this nanowire equipped emitter, the nanowires are made of hafnium carbide (HfC) single crystal, the longitudinal direction of the nanowires match the <100> crystal direction of the hafnium carbide single crystal, and the end part of the nanowires through which electrons are to be released comprise the (200) face and the {310} face of the hafnium carbide single crystal, with the (200) face being the center and the {311} faces surrounding the (200) face.