An undulator comprises at least M permanent magnet periods arranged sequentially in a transmission direction of electron beams, each of the permanent magnet periods comprises four rows of permanent magnet structures, in which each row comprises N rows of permanent magnet groups, and each row of the permanent magnet groups comprises K permanent magnet units, wherein M, N and K are natural numbers greater than or equal to 1; the four rows of the permanent magnet structures are pairwise matched, then relatively disposed on both sides of the transmission direction of electron beams, and are capable of forming at least one composite magnetic fields by relative displacement, such that elliptically polarized light, circularly polarized light, or linearly polarized light with an arbitrary polarization angle of 0360 is generated when electron beams pass through the composite magnetic fields, and such that velocity directions of electrons are deviated from an axis direction of the undulator.

Systems and methods for generating longitudinally modulated (micro-bunched) electron bunches and for generating coherent radiation by the emission from relativistic electrons with a density that is longitudinally modulated (micro-bunched) with a spatial dimension that is significantly below the wavelength of the emitted radiation. The light source includes a high-brightness relativistic electron beam that interacts in a magnetic structure (linear or helical undulator or wiggler) or an electromagnetic structure with a pulse of high-power electro-magnetic wave (modulation laser pulse). The interaction leads to a large energy-modulation of the electron bunch which is transformed into a spatial modulation by an energy-dispersive element that can be the same undulator.

A device includes: a first magnet array; a first magnet support body; a second magnet array; a second magnet support body; a gap drive mechanism for performing vertical drive of the magnet support bodies to change a gap; first, second connection beams connected to the magnet support bodies; a mechanism for connecting the connection beams to the gap drive mechanism; a cancellation spring mechanism for cancelling a suction force that acts between magnet arrays; and a spring interlocking mechanism for connecting the cancellation spring mechanism to the magnet support bodies. In the spring interlocking mechanism, first and second spring support frames that are connected to the first and second connection beams via a connecting portion, and a guide mechanism for guiding vertical movements of the first and second spring support frames are mounted, and the cancellation spring mechanism are mounted to both the first and second spring support frames.

An EUV light generator including the following components: A. an electron storage ring including a first linear section and a second linear section; B. an electron supplier configured to supply the electron storage ring with an electron bunch; C. a high-frequency acceleration cavity disposed in the first linear section and configured to accelerate the electron bunch in such a way that a length Lez of the electron bunch satisfies 0.09 mLez3 m; and D. an undulator disposed in the second linear section and configured to output EUV light when the electron bunch enters the undulator.

Employing undulator devices as x-ray radiation sources requires expensive and bulky support systems for operation, which are not robust and lead to limited ranges of generated radiation energies. A force-compensated undulator device is described. The device includes an undulator having first and second magnet arrays disposed along a central axis. The first magnet array is translatable along the central axis. The device further includes a compensator unit disposed adjacent to the first magnet array with the compensator unit having a first row of magnets disposed along a compensator axis with the compensator axis being parallel to the central axis, and a second row of magnets disposed along the compensator axis. The first row of magnets is translatable along the compensator axis. The compensator provides magnetic forces that neutralize the system dynamic magnetic forces generated by the undulator.

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.

A method of patterning lithographic substrates, the method comprising using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further comprises reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

A method of patterning lithographic substrates, the method including using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

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.

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.