A high power extreme ultraviolet (EUV) beam is produced. An electron beam is injected in a compact electron storage ring configured for emission of free-electron laser (FEL) radiation. The electron beam is passed through a magnetic undulator on each of a plurality of successive revolutions of the electron beam around the compact electron storage ring. The electron beam is induced to microbunch and radiate coherently while passing through the magnetic undulator. A portion of the free-electron laser radiation at an extreme ultraviolet wavelength produced by an interaction of the electron beam through the magnetic undulator is outputted.

A continuous winding method produces a continuously wound electrical device, such an undulator. A continuous tape is wound about a series of turn around pins and in grooves in a magnetic core. A plurality of winding stacks are created, each transitioning to the next sequential stack by a transition tape portion extending from one turn around pin to the next turn around pin, which is position opposite with regard to the location of the pin on the magnetic core.

An undulator magnet having favorable transportation workability is provided. Specifically, an undulator permanent magnet used for an undulator is provided that generates radiation light by meandering electrons that travel in a first direction, wherein, in the undulator permanent magnet, one end surface in the first direction forms a first connecting surface connected to another undulator permanent magnet, N poles and S poles are alternately arranged in the first direction on one magnetic pole surface in a second direction orthogonal to the first direction, and thus a magnetic flux density distribution having a plurality of peaks is generated, and when the plurality of peaks are represented as the first to m-th peaks P.sub.m (m is an integer of 1 or more) in order from the side of the first connecting surface, a magnitude of the first peak P.sub.1 is larger than a magnitude of the third peak P.sub.3.

A helical permanent magnet structure includes at least one magnet assembly. The magnet assembly includes a plurality of permanent magnets and poles. The permanent magnets are with a magnetization direction, and formed as helical shape and arranged as a helical surface, the center of the helical surface has a longitudinal passage for being passed through by a charged particle. The poles are with the same amount of the permanent magnets, wherein the poles are magnetized by the permanent magnets and absorb on one side of the permanent magnets.

X-ray pulse source (100) for generating X-ray pulses (1) includes electron pulse source device (10) including photo-emitter device (11) being configured for photo-induced creation of free electron pulses (2) and driver device (12) being configured for creating electromagnetic driver pulses (3) accelerating electron pulses (2) along acceleration path (7), and electromagnetic interaction device (50) comprising electromagnetic pulse source device (51) being configured for creating electromagnetic pulses (4) in interaction section (5) of electromagnetic interaction device (50), wherein electron pulse source device (10) and electromagnetic interaction device (50) are operable for generating X-ray pulses (1) by an interaction of electron pulses (2) and electromagnetic pulses (4), and driver device (12) includes THz driver pulse source (13), which is configured for creating single cycle or multi cycle THz driver pulses (3). Furthermore, a method of creating X-ray pulses (1) is described.

A free electron laser FEL comprises an undulator 24 generating coherent EUV radiation receiving an upstream electron beam EB2 and emitting a downstream electron beam EB4 and at least an electron source 21a, 21b operable to produce an upstream electron beam EB1, EB2 comprising bunches of electrons. A beam path is configured to direct the upstream electron beam through: a linear accelerator system (LINAC) comprising at least a first and a second linear accelerators 22a, 22b, a bunch compressor 28b, and said undulator 24. The downstream electron beam EB3, EB4 that leaves the undulator 24 recirculates through the second linear accelerator 22b in parallel with the upstream electron beam with a phase such that the downstream beam is decelerated by the second linear accelerator 22b and then recirculates through the first linear accelerator 22a in parallel with the upstream electron beam with a phase such that the downstream beam is decelerated by the first linear accelerator 22a; and to direct the downstream beam to a beam dump 100. At least a first energy spreader 50a, 50b, 50c imparts a reversible change to the energy distribution of bunches of electrons and is located at a position in the beam path before the bunch compressor 28b and so that it is only passed through by the upstream electron beam EB1. A second energy spreader 50d reverses the change to the energy distribution of bunches of electrons imparted by the at least one first energy spreader 50a, 50b, 50c, the second energy spreader 50d being located at a position in the beam path before the undulator 24 and so that it is only passed through by the upstream electron beam EB2.

A two-period inverter, including a series of permanent magnets with a spatial periodicity of ?.sub.0 or (2n+1)?.sub.0 or 2n?.sub.0 along a longitudinal axis Y and first moving apparatus arranged to modify along the axis Y, with respect to a reference position along the axis Y, the relative position of the first and second series, which move as one, with respect to the position of the third and fourth series, which move as one, by a distance (2n+1)?.sub.0/2 or (2n?1)?.sub.0/2, so that the inverter is placed in an offset position along the axis Y is discussed.

A system including an electron beam source for providing an electron beam and at least one undulator system configured to produce free-electron laser (FEL) radiation is described. The undulator system includes undulators and at least one optical section between the undulators. The undulators are configured to induce the electron beam to microbunch and radiate coherently. The optical section(s) are configured to operate on the electron beam and the FEL radiation generated by the electron beam.

A high performance superconducting undulator magnet is provided. The superconducting undulator magnet includes inset grooves in which magnetic poles are attached. The superconducting undulator magnet also includes clips for use in winding. The superconducting wire is wound such that the each revolution of the wire has a precise position within each of the grooves, the precise position being repeated in each groove. The superconducting undulator magnet provided will have a mechanical precision to preserve uniformity of the magnetic pole width and coil grooves. The undulator system provides uniformity of the undulator gap.

A high power extreme ultraviolet (EUV) beam is produced. An electron beam is injected in a compact electron storage ring configured for emission of free-electron laser (FEL) radiation. The electron beam is passed through a magnetic undulator on each of a plurality of successive revolutions of the electron beam around the compact electron storage ring. The electron beam is induced to microbunch and radiate coherently while passing through the magnetic undulator. A portion of the free-electron laser radiation at an extreme ultraviolet wavelength produced by an interaction of the electron beam through the magnetic undulator is outputted.