Example compact modular electron beam units are provided that can be used to generate electron beams using field emitter elements. A modular electron beam unit may comprise an electron beam source including a base portion, at least one field emitter element coupled to the base portion, the field emitter element including a field emitter tip, at least one gate electrode and a membrane window disposed over the at least one gate electrode.

Accelerator apparatus (100) for accelerating charged particles (2) with pulsed radiation includes horn-shaped coupling device (10) with at least one horn coupler (11, 15) having input aperture (12), electrically conductive walls (13) and output aperture (14), wherein pulsed radiation is received at input aperture and focused towards output aperture, and waveguide device (20) coupled with the output aperture and configured for receiving focused pulsed radiation. Waveguide device includes injection section (21) for providing charged particles and subjecting them to acceleration by pulsed radiation in injection section, and lateral output port (23) for releasing accelerated charged particles along particle acceleration direction. The at least one horn coupler receives linearly polarized single cycle pulses (1) including broadband frequency spectrum shaped as a linearly polarized plane wave and focuses linearly polarized single cycle pulses. Waveguide device has non-resonant broadband transmission characteristic. Furthermore, charged particle gun and method of accelerating charged particles are described.

The emitter of the present invention includes a nanowire. The nanowire is formed from a hafnium carbide (HfC) single crystal, and at least an end portion of the hafnium carbide single crystal, from which electrons are to be emitted, is covered with hafnium oxide (HfO.sub.2). In the emitter, the thickness of the hafnium oxide may be 1 nm to 20 nm.

A power supply circuit and a field emission electron source are provided. The power supply circuit includes: field effect transistors S.sub.i coupled in series via drains and sources in sequence, wherein 1in, n2, and wherein a source of S.sub.1 is coupled to a negative electrode of a voltage source, and a drain of S.sub.n is used as an output terminal of the power supply circuit to couple to a load; a first group of diodes D.sub.1i coupled in series; a first group of resistors R.sub.1j, 2jn; and a current feedback module configured to adjust an internal resistance of the field effect transistors S.sub.i, coupled in series in sequence, so as to cause a current passing through the load to be constant; wherein the field effect transistors S.sub.i, 1in, operate in a constant current region.

The emitter of the present invention includes a nanowire. The nanowire is formed from a hafnium carbide (HfC) single crystal, and at least an end portion of the hafnium carbide single crystal, from which electrons are to be emitted, is covered with hafnium oxide (HfO.sub.2). In the emitter, the thickness of the hafnium oxide may be 1 nm to 20 nm.

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.

The purpose of the present invention is to provide a charged particle gun using merely an electrostatic lens, said charged particle gun being relatively small and having less aberration, and to provide a field emission-type charged particle gun having high luminance even with a high current. This charged particle gun has: a charged particle source; an acceleration electrode that accelerates charged particles emitted from the charged particle source; a control electrode, which is disposed further toward the charged particle source side than the acceleration electrode, and which has a larger aperture diameter than the aperture diameter of the acceleration electrode; and a control unit that controls, on the basis of a potential applied to the acceleration electrode, a potential to be applied to the control electrode.

Provided is a superconducting cryo module that can be made more compact. A superconducting cryo module according to the present disclosure comprises: a superconducting accelerating cavity that has a cell part accelerating electrons, a beam pipe part extending from the cell part to an electron incidence side, and an extraction part of the electrons which were accelerated by the cell part; and an electron gun that is located in the interior of the beam pipe part of the superconducting accelerating cavity, is located on the same axis as a beam axis BA of the superconducting accelerating cavity, and emits electrons into the cell part.