There is described a device for generating electromagnetic field oscillation in a RF device or cavity. The device generally has a photo-diode configured for receiving a laser pulse train and emitting a first electrical signal based thereon, the first electrical signal having a plurality of frequencies; and a harmonics selector configured to output a second electrical signal having one or more frequency of the first electrical signal, the one or more frequency being selected in a manner for the output to generate the electromagnetic field oscillation in the RF device or cavity.

A photocathode can include a body fabricated of a wide bandgap semiconductor material, a metal layer, and an alkali halide photocathode emitter. The body may have a thickness of less than 100 nm and the alkali halide photocathode may have a thickness less than 10 nm. The photocathode can be illuminated with a dual wavelength scheme.

An electron beam source is provided that includes a vessel forming a chamber, a cathode disposed within the chamber, the cathode comprising a low dimensional electrically conductive material having an anisotropic restricted thermal conductivity, an electrode disposed in the chamber, the electrode being connectable to a power source for applying a positive voltage to the electrode relative to the cathode for accelerating free electrons away from the cathode to form an electron beam when the cathode is illuminated by electromagnetic (EM) radiation such that the cathode thermionically emits free electrons, and an electron emission window in the chamber for passing a generated electron beam out of the chamber. An electron microscope that incorporates the electron beam source is also provided.

An electron beam emitted from a photoexcited electron gun is increased in luminance. An electron gun 15 includes: a photocathode 1 including a substrate 11 and a photoelectric film 10; a light source 7 that emits pulsed excitation light; a condenser lens 2 that focuses the pulsed excitation light toward the photocathode; and an extractor electrode 3 that faces the photocathode and that accelerates an electron beam generated from the photoelectric film by focusing the pulsed excitation light by the condenser lens, transmitting the pulsed excitation light through the substrate of the photocathode, and causing the pulsed excitation light to be incident on the photocathode. The pulsed excitation light is condensed at different timings at different positions on the photoelectric film of the photocathode.

System and method for Ultrafast Electron Diffraction (UED) and Microscopy (UEM) configured to image atomic motion in real time with sub-femtosecond temporal resolution. Presented methodology utilizes the interaction of the pump optical pulse with the initial electron pulse that has been gated with the gating optical pulse. The initial electron pulse is generated in the electron microscope by the pulse of auxiliary light. In one case, the pump and gating pulses have attosecond duration and are duplicates of one another. The use of attosecond optical pulse (with frequency spectrum extending over two octaves in the visible and flanking spectral ranges) for optical gating of a pulse of electrons.

Provided is a method of adjusting an electron-beam irradiated area in an electron beam irradiation apparatus that deflects an electron beam with a deflector to irradiate an object with the electron beam, the method including: emitting an electron beam while changing an irradiation position on an adjustment plate by controlling the deflector in accordance with an electron beam irradiation recipe, the adjustment plate detecting a current corresponding to the emitted electron beam; acquiring a current value detected from the adjustment plate; forming image data corresponding to the acquired current value; determining whether the electron-beam irradiated area is appropriate based on the formed image data; and updating the electron beam irradiation recipe when the electron-beam irradiated area is determined not to be appropriate.

A high-brightness electron beam source is disclosed. The electron beam source may include a broadband illumination source configured to generate broadband illumination. A tunable spectral filter may be configured to filter the broadband illumination to provide filtered illumination having an excitation spectrum. The electron beam source may further include a photocathode configured to emit one or more electron beams in response to the filtered illumination, wherein emission from the photocathode is adjustable based on the excitation spectrum of the filtered illumination from the tunable spectral filter.

A photocathode structure, which can include an alkali halide, has a protective film on an exterior surface of the photocathode structure. The protective film includes ruthenium. This protective film can be, for example, ruthenium or an alloy of ruthenium and platinum. The protective film can have a thickness from 1 nm to 20 nm. The photocathode structure can be used in an electron beam tool like a scanning electron microscope.

A high voltage feedthrough assembly for providing an electric potential in a vacuum environment comprises a flange connector being adapted for a connection with a vacuum vessel, a vacuum-tight insulator tube having a longitudinal extension with a first end facing to the flange connector and a second end being adapted for projecting into the vacuum vessel, and an electrode device coupled to the second end of the insulator tube, wherein the electrode device has a front electrode, including a photocathode or a field emitter tip and facing to the vacuum vessel and a cable adapter for receiving a high-voltage cable, wherein a flexible tube connector is provided for a vacuum-tight coupling of the insulator tube with the flange connector, and a manipulator device is connected with the insulator tube for adjusting a geometrical arrangement of the insulator tube relative to the flange connector.

Provided is an electron gun that can have a setting to make it possible to irradiate a desired location on an irradiation target with an electron beam having a desired electron beam parameter by using only the component included in the electron gun. This object can be achieved by an electron gun including: a light source; a photocathode configured to generate releasable electrons in response to receiving light from the light source; an anode configured to generate an electric field between the photocathode and the anode, extract the releasable electrons by the generated electric field, and form an electron beam; and a control unit, and the control unit sets the number of emission times of the electron beam and sets an electron beam parameter for each emitting electron beam, or sets an emission duration of the electron beam and sets an electron beam parameter of an emitting electron beam in association with the emission duration.