When an emission current is changed, a decrease in brightness of an electron beam is prevented. An electron gun includes a cathode that emits thermoelectrons, a Wehnelt electrode that focuses the thermoelectrons, a control electrode that extracts the thermoelectrons from a distal end of said cathode, an anode that accelerates the thermoelectrons and irradiates a powder with the thermoelectrons as an electron beam, and an optimum condition collection controller that changes at least one of a bias voltage to be applied to the Wehnelt electrode and a control electrode voltage to be applied to the control electrode, and decides a combination of the bias voltage and the control electrode voltage at which the brightness of the electron beam reaches a peak.

The purpose of the present invention, relating to lanthanide boride, which is known as a low work function material, is to provide a novel low work function material with low chemical reactivity, in particular a low work function material of which the material surface, after being exposed to atmospheric gases, can be cleaned at a heating temperature lower than in the prior art. The present invention is a laminate containing a lanthanide boride film formed on a substrate, the surface of said film being covered by a thin film, wherein the thin film is a monatomic layer of a hexagonal boron nitride thin film.

Examples of an electron gun with a moving cathode station and a moving anode station are described. The moving cathode has a driver that moves the station and comprises a plurality of cathodes with a plurality of bias cups to control a thermal electron emission region by applying a bias voltage to the bias cup. The moving anode station comprises a plurality of anodes and has driver to move the anode station such that a position of each anode is synchronized with a positioned of a respective matching pair of cathode and bias cup. A controller that is in communication with the anode and cathode moving stations controls the bias voltage and the drivers to control the amount of thermal electrons and to synchronize and align a predetermined cathode with a predetermined anode thus controlling the size and parameters of the generated electron beam.

Examples of an electron gun with a moving cathode station and a moving anode station are described. The moving cathode has a driver that moves the station and comprises a plurality of cathodes with a plurality of bias cups to control a thermal electron emission region by applying a bias voltage to the bias cup. The moving anode station comprises a plurality of anodes and has driver to move the anode station such that a position of each anode is synchronized with a positioned of a respective matching pair of cathode and bias cup. A controller that is in communication with the anode and cathode moving stations controls the bias voltage and the drivers to control the amount of thermal electrons and to synchronize and align a predetermined cathode with a predetermined anode thus controlling the size and parameters of the generated electron beam.

An electron emitter that consists of: a low work function material including Lanthanum hexaboride or Iridium Cerium that acts as an emitter, a cylinder base made of high work function material that has a cone shape where the low work function material is embedded in the high work function material but is exposed at end of the cone and the combined structure is heated and biased to a negative voltage relative to an anode, an anode electrode that has positive bias relative to the emitter, and a wehnelt electrode with an aperture where the cylindrical base protrudes through the wehnelt aperture so the end of the cone containing the emissive area is placed between the wehnelt and the anode.

The present invention relates to a method for prolonging lifetime of a triod electron beam source when forming a three-dimensional article through successively depositing individual layers of powder material that are fused together so as to form the article, the method comprising the steps of: adjusting a cathode heating power at a predetermined value above a threshold heating value, which threshold heating value creates a predetermined X-ray signal emanating from the triod electron beam source, fusing the three-dimensional article with the electron beam source having the cathode heating power at a predetermined value above a threshold heating value.

This invention provides a charged particle source, which comprises an emitter and means of generating a magnetic field distribution. The magnetic field distribution is minimum, about zero, or preferred zero at the tip of the emitter, and along the optical axis is maximum away from the tip immediately. In a preferred embodiment, the magnetic field distribution is provided by dual magnetic lens which provides an anti-symmetric magnetic field at the tip, such that magnetic field at the tip is zero.

This invention provides a charged particle source, which comprises an emitter and means fo generating a magnetic field distribution. The magnetic field distribution is minimum, about zero, or preferred zero at the tip of the emitter, and along the optical axis is maximum away from the tip immediately. In a preferred embodiment, the magnetic field distribution is provided by dual magnetic lens which provides an anti-symmetric magnetic field at the tip, such that magnetic field at the tip is zero.

This invention provides a charged particle source, which comprises an emitter and means of generating a magnetic field distribution. The magnetic field distribution is minimum, about zero, or preferred zero at the tip of the emitter, and along the optical axis is maximum away from the tip immediately. In a preferred embodiment, the magnetic field distribution is provided by dual magnetic lens which provides an anti-symmetric magnetic field at the tip, such that magnetic field at the tip is zero.

A permanently sealed vacuum tube is used to provide the electrons for an electron microscope. This advantageously allows use of low vacuum at the sample, which greatly simplifies the overall design of the system. There are two main variations. In the first variation, imaging is provided by mechanically scanning the sample. In the second variation, imaging is provided by point projection. In both cases, the electron beam is fixed and does not need to be scanned during operation of the microscope. This also greatly simplifies the overall system.