Provided are an electron gun, an electron gun component, an electron beam applicator, and an alignment method that can align the emission axis of an electron beam with the optical axis of the electron optical system of the counterpart device even when misalignment of a mounted position of the electron gun being mounted to the counterpart device is larger. The electron gun includes: a light source; a vacuum chamber; a photocathode that emits an electron beam in response to receiving light from the light source; an electrode kit; and an electrode kit drive device, the electrode kit includes a photocathode supporting part, and an anode arranged spaced apart from the photocathode supporting part, the photocathode is placed on the photocathode supporting part, and the electrode kit drive device moves the electrode kit in an X-Y plane, where one direction is defined as an X direction, a direction orthogonal to the X direction is defined as a Y direction, and a plane including the X direction and the Y direction is defined as the X-Y plane.

A photocathode including a substrate, a photoelectric conversion layer provided on the substrate and generating photoelectrons in response to incidence of light, and an underlayer provided between the substrate and the photoelectric conversion layer and containing beryllium, in which the underlayer has a first underlayer containing a nitride of beryllium.

A solar generator can include a photon-enhanced thermionic emission generator with a cathode to receive solar radiation. The photon-enhanced thermionic emission generator can include an anode that in conjunction with the cathode generates a first current and waste heat from the solar radiation. A thermoelectric generator can be thermally coupled to the anode and can convert the waste heat from the anode into a second current. A circuit can connect to the photon-enhanced thermionic emission generator and to the thermoelectric generator and can combine the first and the second currents into an output current.

A solar generator can include a photon-enhanced thermionic emission generator with a cathode to receive solar radiation. The photon-enhanced thermionic emission generator can include an anode that in conjunction with the cathode generates a first current and waste heat from the solar radiation. A thermoelectric generator can be thermally coupled to the anode and can convert the waste heat from the anode into a second current. A circuit can connect to the photon-enhanced thermionic emission generator and to the thermoelectric generator and can combine the first and the second currents into an output current.

A photocathode 4 includes an optically transparent conductive layer provided between a translucent substrate and a photoelectric conversion layer. The optically transparent conductive layer is formed of a constituent material including carbon. A Raman spectrum of the constituent material has a peak of a band, a peak of a band, a peak of a band, and a peak of a band.

A photocathode 4 includes an optically transparent conductive layer provided between a translucent substrate and a photoelectric conversion layer. The optically transparent conductive layer is formed of a constituent material including carbon. A Raman spectrum of the constituent material has a peak of a band, a peak of a band, a peak of a band, and a peak of a band.

An electromagnetic radiation detector includes an inlet window intended to receive a stream of incident photons, as well as a photocathode in the form of a semiconductive layer. A conductive layer is deposited on the downstream face of the inlet window and a thin dielectric layer is disposed between the conductive layer and the semiconductive layer. The conductive layer is brought to a potential below that of the semiconductive layer so as to drive the photoelectrons out of the recombination zone and consequently improve the quantum yield of the photocathode.

A transmission mode photocathode comprises: an optically transparent substrate having an outside face to which light is incident, and an inside face from which the light incident to the outside face side is output; a photoelectric conversion layer disposed on the inside face side of the optically transparent substrate and configured to convert the light output from the inside face into a photoelectron or photoelectrons; and an optically-transparent electroconductive layer comprising graphene, and disposed between the optically transparent substrate and the photoelectric conversion layer.

A transmission mode photocathode comprises: an optically transparent substrate having an outside face to which light is incident, and an inside face from which the light incident to the outside face side is output; a photoelectric conversion layer disposed on the inside face side of the optically transparent substrate and configured to convert the light output from the inside face into a photoelectron or photoelectrons; and an optically-transparent electroconductive layer comprising graphene, and disposed between the optically transparent substrate and the photoelectric conversion layer.

An electron emission device includes a substrate and an electron emission layer. The electron emission layer is provided above the substrate, and is provided with an opening. The electron emission layer has an edge defining the opening and is configured to emit electrons from the edge when the edge is irradiated with light.