Abstract: An electron gun includes a cathode including an electron emitting portion, an extraction electrode for extracting electrons emitted from the electron emitting portion, and a focusing electrode for focusing the electrons extracted by the extraction electrode. The focusing electrode includes an outside electrode having a tubular shape, and an inside electrode arranged inside the outside electrode. The inside electrode defines a first space having a columnar shape, and includes a first surface on a side of the cathode, and a second surface on an opposite side of the first surface. An inside surface of the outside electrode and the second surface of the inside electrode define a second space. The inside electrode includes an electron passage hole, and a communicating portion which makes the first space and the second space communicate with each other.

Abstract: An ion source is configured for soft electron ionization and produces a low electron-energy, yet high-intensity, electron beam. The ion source includes an electron source that produces the electron beam and transmits it into an ionization chamber. The electron beam interacts with sample material in the ionization chamber to produce an ion beam that may be transmitted to a downstream device. The electron source is configured for generating a virtual cathode upstream of the ionization chamber, which enhances the intensity of the electron beam.

Abstract: There is disclosed a method of controlling an electron gun without causing decreases in brightness of the electron beam if a current-limiting aperture cannot be used. The electron gun (10) has a cathode (11), a Wehnelt electrode (12), a control electrode (13), an anode (14), and a controller (22). The Wehnelt electrode (12) has a first opening (12c) in which the tip of the cathode is inserted, and focuses thermal electrons emitted from the tip of the cathode (11). The thermal electrons emitted from the tip of the cathode (11) are caused to pass into a second opening (13c) by the control electrode (13). The anode (14) accelerates the thermal electrons emitted from the cathode (11) such that the thermal electrons passed through the second opening (13c) pass through a third opening (14b) and impinge as an electron beam (B1) on a powdered sample (8).

Abstract: An object of the present invention is to provide an electron beam apparatus, in which a plurality of electron beams, e.g., four electron beams, is produced for one optical axis with a relatively high current achieved for each electron beam. Provided is an electron beam apparatus comprising: an electron beam emitter (32) having an electron gun (30), said electron gun (30) disposed along an optical axis (23) and operable to emit a plurality of off-axis electron beams along a direction defined by a certain angle with respect to the optical axis (23); a plurality of apertures (34) disposed at a location offset from the optical axis (23); and an electromagnetic lens (7) for forming a magnetic field between the electron gun (30) and the apertures (34) to control the plurality of off-axis electron beams emitted from the electron gun (30) so that the plurality of off-axis electron beams passes through the apertures (34).

Abstract: A cap can comprise an aperture, and an attenuator may block the aperture during at least one point in time. In one embodiment, the attenuator can include a cover that may be displaced by a spring. In another embodiment, such as an electron gun, may comprise a support cap with an aperture, a displaceable cover that may cover the aperture, and a spring. A material attached to the spring and acting as a fuse may release the spring and expose the aperture after an electrical current blows the “fuse”. In yet another embodiment, a method for using a tube may comprise evacuating the tube while a cover covers an aperture in the support cap of a electron gun that is at least partially in the tube and moving the cover to expose the aperture after the tube is sealed.

Abstract: A mechanically tunable magnetron injection gun (MIG) provides an annular, relativistic beam of electrons for injection into an axially aligned magnetic field of a gyrotron-class device. The electron emitter encircles a center electrode. Turning a knob adjusts the center electrode's axial position relative to the rest of the cathode. The adjustable center electrode provides an effective means for local field adjustment. The center electrode is located in a particularly sensitive electric field region and adjusts the electric field so as to tune the electron beam from the inside out. Adjusting the center electrode position while the device is in operation is a means for providing mechanical tunability (with respect to beam quality and transverse-to-axial velocity ratio) for the MIG.

Abstract: An advanced center post (ACP) gun is provided which is capable of producing either a large orbit or small orbit electron beam. The gun comprises an annular shaped cathode, a control electrode adjacent the cathode, and an annular anode having an opening therethrough. A center post is disposed axially within the center region of the cathode and the control electrode along a center line of the electron gun and interaction region of a microwave device. The anode is shaped in conjunction with the center post to control position of equipotential lines of an electric field provided in an inter-electrode space between the cathode and the anode so that an electron beam emitted by the cathode converges at the anode opening. The control electrode provides electrostatic focusing of the beam to further control the beam convergence. Multiple polepieces provide accurate control of the magnetic field in the interaction region to shape the beam and control the orbit size and velocity spread.

Abstract: An electron gun producing a spiral electron beam for gyrotron devices comprises means for producing an axial magnetic field propagating the beam axially beyond the anode of the electron gun, and separate electromagnets for producing a transverse "kicker" electromagnetic field beyond the anode and perpendicular to the magnetic propagation field such as to apply a transverse impulse of short duration, imparting a transverse motion, to the electrons to cause them to spiral as they are propagated axially beyond the anode.

Abstract: A cold field emitter is placed in special relationship to an anode device ving a hole in it close to the emitter. A second electrode can be located above the hole in the anode and be a circular shape of lesser diameter than the first anode so as to shape the hollow beam being emitted by the device.

Abstract: A modulatable, hollow beam electron gun assembly includes an electron-optical (E-O) column having a fixed diameter ring, dispenser type cathode assembly for providing a hollow electron beam through thermionic emission from a hollow cylindrical cathode element, first and second control grid assemblies, a first anode assembly and a second anode assembly, which in combination with a beam modulator assembly comprises an electrostatic coaxial lens assembly. The grid and anode assemblies provide control of the emitted beam current density.