An electron tube includes a housing having a window having an electromagnetic wave transmitting property, an electron emission plate disposed inside the housing, the electron emission plate emitting electrons, and a holding member disposed inside the housing and configured to hold the electron emission plate and to apply a voltage to the electron emission plate. The electron emission plate has a first main surface and a second main surface facing each other. The holding member has a base portion being in contact with the first main surface, and a plurality of electron emission plate biasing portions which are in contact with an edge of the second main surface and are configured to elastically bias the electron emission plate to the base portion. The holding member is electrically connected to the second main surface through the plurality of electron emission plate biasing portions.

An in-vacuum light sensor system, including a light sensor assembly comprising a photocathode configured for converting an impinging photon to a photoelectron, a semiconductor diode configured for multiplying the photoelectron impinging thereon, and a housing including vacuum-compatible materials configured for being placed in a vacuum chamber. The housing is configured for housing the photocathode and the semiconductor diode and for propagation of the photoelectron from the photocathode to the semiconductor diode. An electrical biasing subassembly is configured for electrically biasing at least the photocathode and the semiconductor diode, and the vacuum chamber is configured for positioning the light sensor apparatus therein.

An in-vacuum light sensor system, including a light sensor assembly comprising a photocathode configured for converting an impinging photon to a photoelectron, a semiconductor diode configured for multiplying the photoelectron impinging thereon, and a housing including vacuum-compatible materials configured for being placed in a vacuum chamber. The housing is configured for housing the photocathode and the semiconductor diode and for propagation of the photoelectron from the photocathode to the semiconductor diode. An electrical biasing subassembly is configured for electrically biasing at least the photocathode and the semiconductor diode, and the vacuum chamber is configured for positioning the light sensor apparatus therein.

An ion detection system comprising an upper plate configured for propagation of ions therethrough, a lower plate comprising a converter configured for converting ions impinging thereon to secondary electrons, a secondary electron multiplication assembly configured for receiving the secondary electrons and comprising at least one or optionally a series of oppositely facing pairs of dynodes, wherein in the optional series of oppositely facing pairs of dynodes, each pair is spaced apart from an adjacent pair, and wherein a first electric field is created in between the oppositely facing pair of dynodes. A magnetic system is provided for generating a magnetic field.

An electron tube includes a housing that is internally held in a vacuum and has a window transmitting an electromagnetic wave, an electron emitting unit that is disposed in the housing and has a meta-surface emitting electrons in response to incidence of the electromagnetic wave, an electron multiplying unit that is disposed in the housing and multiplies the electrons emitted from the electron emitting unit, and an electron collecting unit that is disposed in the housing and collects the electrons multiplied by the electron multiplying unit. The window contains at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, and calcium carbonate.

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 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 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.

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.