Superconducting Andulator Device

Abstract

The present disclosure includes at least a first superconducting coil structure (302) and at least a second superconducting coil structure (304) disposed on the opposite side of the first superconducting coil structure. The first and second superconducting coil structures are separated by a gap (h g ) dedicated to the passage of an electron beam. Each superconducting coil structure includes a plurality of grooves (332, 334) that penetrate the thickness (h m ) of the superconducting coil structure to separate the superconducting coil structure into a plurality of element coils. The grooves are configured such that the current flowing through the superconducting coil structure between the grooves can flow alternately in two different directions in the superconducting coil structure, and relates to an undulator device (300).

Description

Technical Field

[0001] The present disclosure generally relates to superconducting coils, and more particularly to an undulator, or wiggler, which is a device comprising a superconducting coil.

Background Art

[0002] For example, for performing experiments, there are devices in which electrons are generated, emitted, accelerated, and the path of the electrons can be deflected. A synchrotron is one of these devices. In a synchrotron, a high-energy electron beam is emitted, and the emitted electron beam is generally directed to components such as bending magnets (benders), undulator magnets (undulators), or wiggler magnets (wigglers) in an accumulation ring or a free electron laser, and a synchrotron radiation source (also called a "synchrotron light source") can be generated. Each of these benders, undulators, or wigglers supplies a magnetic field adapted to change the direction of the electron beam path, for example, to bend, vibrate, or wiggle the electron beam respectively. The change in direction is a form of acceleration, and thus, high-energy electrons can be converted into optical radiation, also called "synchrotron radiation".

[0003] Benders were first used to generate synchrotron radiation. Better electron beam quality and significantly higher brightness are generally provided by wigglers or undulators in addition to benders. These two types of magnets are generally called "insertion devices". Insertion devices are typically placed in the straight sections of an accumulation ring or a free electron laser.

[0004] An undulator or wiggler typically comprises a periodic structure of dipole magnets that can be permanent magnets or electromagnets. The periodic structure is adapted to generate an alternating magnetic field along the length of the undulator. This alternating magnetic field is adapted to forcibly undulate the electrons of the electron beam around the beam axis corresponding to the direction of the emitted electron beam. Since the electrons undergo many direction changes, they can be converted into light radiation of significantly higher brightness.

[0005] The main difference between an undulator and a wiggler is the strength of their magnetic fields and the amplitude of the deviation of the electrons from the beam axis, and the wiggler generally provides a stronger field than the undulator. This results in a wider horizontal opening angle of the emitted radiation and a luminescence spectrum characterized by a wider energy band.

[0006] For simplicity of explanation, the term "undulator" or "undulator device" can be used to refer to either an undulator or a wiggler.

[0007] In certain applications, improvements to the undulator are desired.

Summary of the Invention

Problems to be Solved by the Invention

[0008] There is a need to provide an improved undulator device.

[0009] It is also desirable that the undulator device be easy to implement.

Means for Solving the Problems

[0010] One embodiment addresses all or some of the drawbacks of known undulator devices.

[0011] One embodiment is - at least a first superconducting coil structure, and - At least a second superconducting coil structure arranged on the opposite side of the first superconducting coil structure and comprising The first and second superconducting coil structures are separated by a gap dedicated to the passage of an electron beam having an electron beam trajectory around the beam axis, the beam axis being in a first direction, Each superconducting coil structure includes a plurality of grooves that separate the superconducting coil structure into a plurality of element coils through the thickness of the superconducting coil structure, the grooves being configured such that the current flowing through the superconducting coil structure between the grooves can flow alternately in two different directions, for example, substantially two opposite directions, in the superconducting coil structure. Providing an undulator device.

[0012] The grooves preferably reach at least one side of the superconducting coil structure.

[0013] The undulator device may include a plurality of auxiliary grooves that penetrate the thickness of the superconducting coil structure, the auxiliary grooves being arranged at a distance from the grooves and being completely accommodated inside the superconducting coil structure without reaching the sides of the superconducting coil structure.

[0014] In an embodiment, the first superconducting coil structure and the second superconducting coil structure extend in a direction substantially parallel to the first direction, and the gap is in a second direction substantially perpendicular to the first direction.

[0015] In an embodiment, the first and second superconducting coil structures are centered on the beam axis in the second direction and preferably in a third direction perpendicular to the first and second directions.

[0016] In an embodiment, the alternating different directions of the current correspond to two opposite directions in a third direction perpendicular to the first and second directions.

[0017] In an embodiment, the plurality of grooves extend in a third direction perpendicular to the first and second directions. The grooves are, for example, substantially straight.

[0018] In an embodiment, each of the grooves starts at a first side of the superconducting coil structure or a second side of the superconducting coil structure opposite to the first side, stops at a position at a certain distance from the second side or the first side of the superconducting coil structure, and the first side and the second side extend in, for example, a first direction.

[0019] In an embodiment, the grooves are regularly distributed in the first direction.

[0020] In a specific embodiment, the plurality of grooves includes a first groove that starts from the first side and stops at a position at a first distance from the second side, and a second groove that starts from the second side and stops at a position at a second distance from the first side, the first and second grooves alternate, and the first and second distances are, for example, equal.

[0021] In an embodiment, - the dimension of each groove in the first direction is 0.01 mm or more, for example 0.05 mm or more, and / or - the dimension of each element coil in the first direction is 20 mm or less, and / or - the dimension of each superconducting coil structure in a second direction parallel to the direction of the gap is 10 mm or less, preferably 1 mm or less.

[0022] In an embodiment, at least one second superconducting coil structure is adapted to be powered by a current of the same polarity as the current adapted to power at least one first superconducting coil structure.

[0023] In an embodiment, the grooves of at least one first superconducting coil structure are aligned with the grooves of at least one second superconducting coil structure in the first direction.

[0024] In an embodiment, at least one first superconducting coil structure and / or at least one second superconducting coil structure includes an auxiliary groove that penetrates the thickness of the superconducting coil structure, and the auxiliary groove is arranged at a distance from the groove, for example, substantially following the current lines between the grooves. For example, at least one of the auxiliary grooves is in at least two parts.

[0025] In an embodiment, at least one first superconducting coil structure is a first multi-structure including at least a first inner superconducting coil structure and a first outer superconducting coil structure assembled together, and at least one second superconducting coil structure is a second multi-structure including at least a second inner second superconducting coil structure and a second outer superconducting coil structure assembled together, and the first and second multi-structures are, for example, a pair, for example, a similar pair.

[0026] In a specific embodiment, - Each of the first inner superconducting coil structure and the second inner superconducting coil structure is longer or smaller than each of the first outer superconducting coil structure and the second outer superconducting coil structure, and / or - Each of the first and second inner superconducting coil structures has more or fewer two end grooves and two end element coils than each of the first and second outer superconducting coil structures, and / or - Each of the first inner superconducting coil structure and the second inner superconducting coil structure is offset in the first direction by a distance equal to the sum of the dimensions in the first direction of a certain element coil among the plurality of element coils and one of the plurality of grooves adjacent to the element coil with respect to each of the first outer superconducting coil structure and the second outer superconducting coil structure, and / or - Each of the first outer superconducting coil structure and the second outer superconducting coil structure is powered by a current with a polarity opposite to the current that powers each of the first inner superconducting coil structure and the second inner superconducting coil structure.

[0027] In an embodiment, - Each superconducting coil structure preferably has at least a planar portion along the electron beam trajectory and / or - A plurality of element coils of each superconducting coil structure form a serpentine structure.

[0028] In an embodiment, each superconducting coil structure further comprises at least one current path coupled to a plurality of element coils, the at least one current path extending in a first direction, and preferably comprises two current paths, one on each side parallel to the first direction of the plurality of element coils.

[0029] In an embodiment, the angulator device further comprises a device for compensating the Lorentz force on the first and second superconducting coil structures, for example, a ferromagnetic collar surrounding the first and second superconducting coil structures.

[0030] In an embodiment, each superconducting coil structure comprises a stacking of different layers, for example consisting of a stacking, the stacking comprising - A substrate layer composed of or coated with a material such as, for example, Hastelloy, and - At least one buffer layer on the substrate layer, preferably a plurality of buffer layers, the at least one buffer layer being composed of a material such as, for example, alumina, yttria, magnesium oxide, and / or lanthanum manganite, at least one buffer layer, and - A superconducting layer on the at least one buffer layer, the superconducting layer comprising a superconducting material or a material adapted to be superconducting under appropriate conditions such as below the temperature limit, for example, a rare earth-based material such as rare earth barium copper oxide or yttrium barium copper oxide, superconducting layer Comprising, The substrate layer includes, for example, at least a tube to enable a cooling fluid such as nitrogen or helium to flow through the superconducting coil structure and / or to enable wiring to pass through the superconducting coil structure.

[0031] In an embodiment, the stacking includes: - Repeating the buffer and the superconducting layer, preferably several times, for example, 1 to 25 times, and optionally, - Repeating the substrate layer with the repeated buffer and superconducting layer, preferably several times, for example, 1 to 25 times and is provided with.

Brief Description of the Drawings

[0032] The foregoing features and advantages, as well as others, are described in detail in the following description of specific embodiments given by way of illustration and not limitation with reference to the accompanying drawings.

[0033]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

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Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8A

Figure 8B

DETAILED DESCRIPTION OF THE INVENTION

[0034] Like features are designated by like reference numerals in the various figures. In particular, structural and / or functional features that are common between the various embodiments may have the same reference numeral and may be given the same structural, dimensional and material properties.

[0035] For clarity, only those operations and elements useful for understanding the embodiments described herein are shown and described in detail. In particular, the electrical connection between the coil and the external power source is not shown.

[0036] Unless otherwise indicated, when referring to two elements connected to each other, this means a direct connection without intermediate elements other than conductors, and when referring to two elements coupled to each other, this means that these two elements can be connected or that they can be coupled via one or more other elements.

[0037] In the following disclosure, unless otherwise indicated, when referring to absolute position modifiers such as "front", "rear", "top", "bottom", "left", "right", etc., or relative position modifiers such as "above", "below", "higher", "lower", etc., or direction modifiers such as "horizontal", "vertical", etc., reference is made to the orientation shown in the figures or to the toroid oriented in normal use.

[0038] Unless otherwise specified, the expressions "about", "approximately", "substantially", "on the order of" mean within 10%, preferably within 5%.

[0039] In the following disclosure, the length corresponds to the dimension of the direction (beam axis) of the electron beam that is referenced as the "X" direction (longitudinal direction or first direction) in the figure, the height or thickness corresponds to the dimension of the direction that separates two rows of magnets or coils or two coil structures or coil multi-structures perpendicular to the beam axis, which is referenced as the "Z" direction (vertical direction or second direction) in the figure, and the width corresponds to the dimension of the direction perpendicular to the X and Z directions, which is referenced as the "Y" direction (lateral direction or third direction) in the figure. In the following disclosure, the electron beam trajectory is substantially in a plane parallel to the first and third directions X, Y.

[0040] The drawings are not to scale. Note that the drawings refer to an embodiment of the disclosed undulator, which may sometimes simply be referred to as a device when no ambiguity is expected. As will be readily understood by those skilled in the art, other embodiments may be possible. The actual dimensions and / or shapes of each of the components of the embodiment may vary. Only the important details of the embodiment are shown, but those skilled in the art can understand how the entire device can be constructed without undue experimentation. Some details may be omitted from the figures, but the inventors believe that it is not necessary to add these details for an overall understanding of the features of the disclosed embodiment. These omitted details include, among other things, elements for holding or fixing the device and / or its functional components or for supplying power. Some features of the embodiment are exaggerated for ease of understanding.

[0041] A simplified example of an undulator 100 is shown in FIG. 1. An electron beam 112 having an initial emission path corresponding to the beam axis 110 in the X direction is injected into the undulator 100. The undulator 100 includes a first row 102 of magnets 102a, 102b and a second row 104 of magnets 104a, 104b that are spaced apart from and opposed to the first row 102 of magnets, and the beam axis 110 is between the first row and the second row. The two rows of magnets 102, 104 induce a magnetic field therebetween. The magnets preferably have the same dimensions and can be permanent magnets or electromagnets.

[0042] The first set of magnets 102a, 104a with left - pointing arrows are configured to generate a first magnetic - field contribution mainly by the magnetic - field lines between the magnets oriented mainly in a first direction, and the second set of magnets 102b, 104b with right - pointing arrows are configured to generate a second magnetic - field contribution mainly by the magnetic - field lines between the magnets oriented mainly in a second direction opposite to the first direction. The first set of magnets and the second set of magnets are arranged alternately.

[0043] Thus, the magnets are configured in a periodic structure that can be defined by the distance d in the X - direction between the centers of two adjacent first - set magnets or between the centers of two adjacent second - set magnets. m as defined by.

[0044] When electrons move between the first row 102 of magnets and the second row 104 of magnets, they alternately move from the first magnetic - field contribution to the second magnetic - field contribution and from the second magnetic - field contribution to the first magnetic - field contribution via the undulator device 100. The periodic reversal or switching of the magnetic - field orientation vibrates or undulates the electron trajectory as shown by the oscillatory trajectory 114. The periodic magnetic field, substantially the oscillation, has a spatial periodicity λ m defined by the distance d u Electrons are accelerated in an oscillatory pattern by the periodic magnetic field by changing the direction or trajectory of the electrons. As a result, the electrons emit electromagnetic radiation 116 defined by the oscillatory trajectory 114. This radiation can be guided via one or more beamlines (plural possible) for performing experiments (not shown), for example.

[0045] Improvements can be brought to the undulator in order to increase the peak magnetic field applied to the electrons in particular, while reducing the size and weight of the undulator, without degrading the quality of the magnetic field along the beam axis. The distance d mReducing it is particularly desirable in order to make the undulator more compact and thus obtain more available space in, for example, a storage ring or a free electron laser that can be used for experiments or diagnostics, i.e., to obtain more space not occupied by the undulator. Such an improved undulator can be achieved using superconducting technology, for example, using superconducting coils. These undulators can be called superconducting undulators.

[0046] Figure 2 shows an example of a superconducting undulator 200. The superconducting undulator 200 includes a first row 202 (lower row) of coils 202a, 202b (lower coils) and a second row 204 (upper row) of coils 204a, 204b (upper coils) that are spaced apart from and opposed to the first row of coils 202. The beam axis 210 is between the first row and the second row. The coils 202a, 202b, 204a, 204b are superconducting coils. In the example of Figure 2, the coils 202a, 202b, 204a, 204b are inserted into an iron frame 206, for example, into slots of the iron frame. In a variant, the coils of each row of coils can be separated by iron poles.

[0047] The first set of coils 202a, 204a is configured to generate a first magnetic field contribution by magnetic field lines between two rows mainly oriented in a first direction, while the second set of coils 202b, 204b is configured to generate a second magnetic field contribution by magnetic field lines between two rows mainly oriented in a second direction opposite to the first direction as indicated by the vertical arrows in Figure 2. The first set of coils and the second set of coils are arranged alternately.

[0048] The periodic structure of the coils can be defined by the X - direction distance d between the centers of two adjacent first - set coils or between the centers of two adjacent second - set coils c thereby.

[0049] When electrons move between the first row 202 and the second row 204 of coils, they alternately move from the first magnetic field contribution to the second magnetic field contribution and from the second magnetic field contribution to the first magnetic field contribution via the angulator device 200. The periodic reversal or switching of the magnetic field orientation causes the trajectories of the electrons to oscillate (angulate), as indicated by the oscillatory trajectory 214. The periodic magnetic field, substantially an oscillation, has a spatial periodicity λ c defined by the distance d u .

[0050] The advantage of this angulator is that the current generating the periodic magnetic field can have the same amplitude in each set of coils along the length of the angulator device. Thus, the magnetic field contributions generated by each set of coils can have substantially the same amplitude along the length of the angulator device, and for opposite directions, it depends on whether it is generated by the first set of coils or the second set of coils. If the coils are geometrically and electrically identical and the iron frame or poles exhibit homogeneous magnetic behavior, the periodic magnetic field generated in the angulator can approach ideal.

[0051] One limitation of such an angulator with superconducting coils is the size of the coils, and in particular, the height h c can be important as it may reduce or limit the peak magnetic field applied to the electrons. The length L of the coils in the X direction c is also a limiting dimension as this dimension, together with the distance or gap g between two adjacent coils in the X direction c , defines the spatial periodicity λ u . In fact, the distance d c corresponds to twice the sum of the length L c and the gap g c .

[0052] Another limitation is imposed by using a superconducting coil having a high aspect ratio such as a tape, because the magnetic field contribution of persistent eddy currents generated within the tape can significantly degrade the magnetic field quality on the beam axis.

[0053] Also, as described above, the coils are preferably geometrically and electrically identical. However, it is not easy for all such coils to be identical.

[0054] Furthermore, it is desirable to avoid using ferromagnetic materials for magnetic field generation to avoid problems related to saturation and non-uniformity of material properties that can lead to degradation of magnetic field quality.

[0055] The inventors propose an undulator that can overcome all or some of the above-mentioned drawbacks, and in particular, can increase the peak magnetic field that can be applied to electrons, for example, up to about 1 tesla (T) at most, and further up to 1.5 T at most.

[0056] Advantageously, the inventors adapt the spatial period λ u to the peak magnetic field and / or can reduce the spatial period λ u in order to avoid disturbing the electron trajectories, even though the magnetic field may increase. As a result, in synchrotron applications, the spectrum of the emitted synchrotron light remains within a narrow energy band desirable for undulator performance.

[0057] Embodiments of the undulator will be described below. These embodiments are non-limiting, and various modifications will be apparent to those skilled in the art from the instructions of this description.

[0058] FIG. 3A schematically shows in an overall perspective view a superconducting undulator 300 (undulator device) according to an embodiment. FIG. 3B schematically and in detail shows in a cross-sectional view the superconducting coil structure 302 of the superconducting undulator 300 of FIG. 3A. FIG. 3C partially shows in a top view the superconducting coil structure 302 of FIGS. 3A and 3B.

[0059] The superconducting undulator 300 includes a first superconducting coil structure 302 (lower coil structure) and a second superconducting coil structure 304 (upper coil structure) disposed on the opposite side of the first superconducting coil structure 302, and the first and second coil structures are separated by a distance (gap) h in the Z direction. g The distance h g is a design parameter and depends on the required peak magnetic field at the beam axis 310, the spatial periodicity λ u , and the physical characteristics of the electron beam.

[0060] The beam axis 310 corresponding to the direction of the emitted electron beam is represented in the X direction, and preferably, the centers of the first coil structure 302 and the second coil structure 304 are centered in the Y and Z directions. The electron beam oscillates around the beam axis 310 in the XY plane along the electron beam trajectory 314 due to the Lorentz force.

[0061] For simplicity of explanation, each superconducting coil structure may be referred to as a "coil structure", and the superconducting undulator may be referred to as an "undulator" or an "undulator device".

[0062] The longitudinal direction of the undulator device corresponds to the longitudinal direction of the superconducting coil structure.

[0063] The first coil structure 302 and the second coil structure 304 are preferably similar.

[0064] As shown in FIG. 3B, each superconducting coil structure may include, for example, a stacking 320 of different layers and may consist of, for example, the stacking 320. In FIG. 3B, only the coil structure 302 is referenced, but it can also be applied to the coil structure 304.

[0065] The stacking 320 is composed of a material such as Hastelloy or different materials, for example, another nickel alloy, and includes a substrate layer 322 covered by Hastelloy.

[0066] The substrate layer 322 may include at least one tube (not shown) through which a coolant can flow to enable cooling of the entire coil structure. In particular, the superconducting layer 326 described in detail below may require appropriate cooling during operation.

[0067] On the substrate layer 322, there is a buffer layer 324 which may preferably be a structure of several stacked buffer layers. The buffer layer(s) can be composed of one or several materials such as alumina, yttria, magnesium oxide, and lanthanum manganite. The buffer layer(s) can be deposited by techniques such as sputtering before depositing the superconducting layer 326. The buffer layer(s) can form an appropriate template for the formation of the superconducting layer 326 described below.

[0068] On the buffer layer 324, the superconducting layer 326 is disposed. The superconducting layer 326 can be composed of rare earth barium copper oxide (REBCO) or yttrium barium copper oxide (YBCO) or other suitable superconducting materials. The superconducting layer 326 can be deposited by techniques such as metalorganic chemical vapor deposition (MOCVD).

[0069] A metal layer, for example, a silver layer, can be deposited on the superconducting layer (not shown in FIG. 3B). The metal layer can form a shunt layer that provides a path for current, for example, when one or more superconducting layers undergo a local transition from the superconducting to the normal conducting state, which is generally called a quench.

[0070] The sequence of the buffer and superconducting layers, and optionally the metal layer, can be repeated N times, for example about 10 times, to form a stack 328 on the substrate layer 322. In other words, several sequences of the buffer and superconducting layers can be deposited on the substrate layer 322.

[0071] By combining multiple layers (tapes) into one, the achievable minimum thickness of tape stacking can be reduced. The same current can flow through a thinner coil, getting closer to the beam axis 310, and as a result, a higher magnetic field can be generated.

[0072] The described stack 328 comprising the substrate layer and the sequence of the buffer and superconducting layers, optionally the metal layer, repeated N times, can form a stacking, or can be repeated M times to form a stacking 320. In this last case, multiple stacks 328 can be formed and stacked on top of each other, or the stack can be long enough like a tape and can be wound up on itself in the longitudinal direction, with M turns corresponding to M stacked layers.

[0073] Other details or variations of the superconducting coil structure of the superconducting undulator according to the embodiment, and a method for manufacturing the superconducting coil structure, can be found in European Patent Application No. EP22305437 filed on April 4, 2022 by the same applicant "RENAISSANCE FUSION" entitled "Method for Manufacturing Superconducting Coils and Devices", which is incorporated herein by reference to the maximum extent permitted by law.

[0074] As shown in FIG. 3A, each superconducting coil structure 302, 304 is substantially planar and extends within the plane XY of the rectangle 306. In other words, each superconducting coil structure forms a parallelepiped structure.

[0075] This is a non-limiting shape, and the superconducting coil structure can have many other shapes such as disk-shaped or free-form. Each superconducting coil structure can also be at least partially curved instead of being completely planar. Preferably, the superconducting coil structure has a planar portion along the electron beam trajectory 314.

[0076] Regardless of the shape, especially due to the stacking structure, the height h of each coil structure m is preferably thin, typically less than about 10 mm, and even less than about 1 mm.

[0077] The thin height h of each coil structure m enables the reduction of the distance in the Z direction between the center of each coil structure 302, 304 and the beam axis 310 because the distance in the Z direction between the center and the end of each coil structure decreases. As a result, when the distance from the coil generating the magnetic field becomes smaller, the peak magnetic field becomes larger, so the peak magnetic field applied to the electron beam can be increased.

[0078] In each superconducting coil structure 302, 304, the grooves 332, 334 are formed through the coil structure as shown in FIG. 3C, thereby separating the coil into different parts and forming several element coils along the length L of the coil structure g FIG. 3C is a partial top view of the superconducting coil structure 302, showing only two element coils 302A, 302B, but preferably there are two or more element coils in each superconducting coil structure. Each groove traverses the entire thickness of the coil structure. The groove can also be called a slit.

[0079] The grooves can be formed preferably using patterning methods such as laser patterning or engraving, or other techniques such as mechanical techniques or photolithography.

[0080] The grooves of each superconducting coil structure are such that the current I flowing within the coil structure between these grooves (represented by the dotted lines in FIGS. 3A and 3C) can flow alternately in two different directions, preferably substantially two opposite directions, within the coil structure so that a magnetic field whose direction changes periodically and preferably has a spatial periodicity λ along the X direction can be generated. u The current I can flow alternately in two different directions, preferably substantially two opposite directions, within the coil structure so that a magnetic field whose direction changes periodically and preferably has a spatial periodicity λ along the X direction can be generated.

[0081] When electrons from the emitted electron beam travel in the X direction through the undulator device 300, they receive a periodic magnetic field that causes the electron trajectories to oscillate (undulate) around the beam axis 310, as indicated by the oscillatory trajectories 314 in a plane parallel to the X and Y directions.

[0082] It should be noted that when it is shown that the current can flow alternately in two different directions, and even in opposite directions, while these two different directions, and even opposite directions, of the current are those that enable obtaining the periodic magnetic field of interest (i.e., the Z component of the magnetic field), it does not exclude the possibility that the current can flow in other directions or orientations within the coil structure.

[0083] In a particular embodiment, the alternating opposite directions of the current I can be in the width direction (Y direction) of the coil structure. For example, as will be described in detail later, the grooves 332, 334 can extend in the width direction of the coil structure. The grooves 332, 334 can be substantially straight.

[0084] The grooves 332, 334 can be regularly distributed along the beam axis, i.e., in the X direction.

[0085] The grooves 332, 334 of the first coil structure 302 are preferably aligned in the X direction with the grooves 332, 334 of the second coil structure 304.

[0086] The second coil structure 304 is powered by a current of the same polarity as the current supplied to the first coil structure 302, thereby synthesizing the Z components of the magnetic fields generated by the two coil structures on the beam axis and not canceling them. Ideally, this can reduce or even cancel the Y component of the magnetic field.

[0087] In the illustrated superconducting coil structures 302, 304, the grooves 332, 334 extend in the Y direction of the XY plane, which is a direction perpendicular to the beam axis, i.e., the X direction. The grooves 332, 334 are formed along a partial width (i.e., not along the full width) of each superconducting coil structure 302, 304. In other words, each groove 332, 334 stops at a distance d s from one of the long sides of the rectangular coil structure. The width w s of each groove is defined by the difference between the width w m of the coil structure and the distance d s .

[0088] The first groove 332 starts from the first long side 306A of the rectangle and stops at a distance d s from the second long side 306B of the rectangle. The second groove 334 starts from the second long side 306B and stops at the same distance d s from the first long side 306A of the rectangle. The first and second grooves are arranged alternately, whereby the path generated for the current I between the grooves is a substantially meandering / wavy path.

[0089] The respective distances d s of the first groove from the second long side and the second groove from the first long side are the same but not limited thereto and may be different.

[0090] The distance L m between adjacent first groove 332 and second groove 334 is preferably regular along the length of the coil structure and is preferably equal to the distance d s but not limited thereto and may be different.

[0091] This distance L mcorresponds to the length of each element coil. Therefore, this distance L m If this is regular along the length of the coil structure, and if the width of each element coil substantially corresponds to the width w m of the coil structure, the element coils formed by the grooves can be geometrically identical. Also, since the same current I flows between the grooves of each coil structure, the current generating the magnetic field in each element coil is the same.

[0092] In addition, the length L m of the element coil can be adjusted by adjusting the position of the groove.

[0093] Furthermore, the distance between the element coils can be adjusted, for example, by adjusting the length L s (L shown in FIG. 3C s ) and can be decreased, for example.

[0094] The width w m of each superconducting coil structure can be more than 20 mm, for example, about 30 mm or more, or even about 50 mm or more.

[0095] The spatial periodicity λ u is defined by twice the sum of the length L m of the element coil and the length L s of the groove.

[0096] For example, the length L s of the groove can be about 0.01 mm or more, or 0.05 mm or more, or even about 0.1 mm or more. For example, the distance L m between adjacent grooves is about 20 mm or less.

[0097] Examples of the dimensions of the superconducting undulator according to the embodiment are shown in Table 1 below.

[0098]

Table 1

[0099] An example of the dimensions of the superconducting coil structure in the superconducting transformer according to the embodiment is shown in Table 2 below.

[0100] [Table 2]

[0101] FIG. 4 schematically shows, in a top view, a superconducting coil structure 402 of a superconducting transformer 400 according to another embodiment.

[0102] The superconducting coil structure 402 in FIG. 4 is mainly different from the superconducting coil structure 302 in FIG. 3C in that each element coil 402A, 402B includes at least one auxiliary groove, that is, two auxiliary grooves 436, 438, between the grooves 432, 434 in the illustrated example. The auxiliary grooves 436, 438 are arranged to reduce undesirable non-uniformities in the current lines flowing through the coil structure between the grooves. In the illustrated example, the auxiliary grooves 436, 438 substantially follow the shape of the current lines between the grooves and are arranged at different distances from the grooves. The auxiliary grooves can be curved as shown in FIG. 4.

[0103] In fact, as shown in FIG. 3C by the darkest zone corresponding to the zone where the current has the most important amplitude, as can be seen on the right-hand scale of the figure, without the auxiliary grooves, the current preferentially flows along the shortest path between the grooves. Therefore, the current lines tend to concentrate around these shortest paths, which can lead to a non-uniform distribution of the current lines in each element coil and a non-uniform magnetic field distribution. The auxiliary grooves force the current to take other paths, as can be seen in FIG. 4 where the darkest zones are more evenly distributed. This results in a more uniform magnetic field distribution and can improve the quality of the magnetic field generated by the transformer, for example, making it closer to a perfect sine curve.

[0104] The auxiliary groove(s) can also have the advantage of providing impedance to the circulation of eddy currents in the superconducting layer(s) of the superconducting coil structure, and thus they can be beneficial for the magnetic field quality on the beam axis.

[0105] The additional groove is completely contained within the superconducting coil structure, i.e., it does not reach the sides of the superconducting coil structure, whereas the auxiliary groove is different from the groove in that the groove reaches at least one side of the superconducting coil structure.

[0106] The dimension of the auxiliary groove in the first direction X can be significantly lower than the length L of the groove. s It can be significantly lower.

[0107] One auxiliary groove 438 can be in two parts 438A, 438B, for example, to enable current redistribution in the case of a quench.

[0108] The superconducting coil structure 402 of FIG. 4 is also different from the superconducting coil structure 302 of FIG. 3C in that grooves 432, 434 are patterned to round the edges of the element coils 402A, 402B. This feature does not need to be related to the presence of the auxiliary grooves 436, 438.

[0109] As seen in FIGS. 3C, 4, and FIGS. 5A, 5B, and 6 described below, the plurality of element coils of each superconducting coil structure can form a serpentine structure.

[0110] FIG. 5A schematically shows a superconducting undulator 500 according to another embodiment in an overall perspective view. FIG. 5B schematically shows details of the superconducting undulator 500 of FIG. 5A.

[0111] The superconducting undulator 500 of FIGS. 5A and 5B is different from the superconducting undulator 300 of FIG. 3A in that instead of having a first coil structure 302 facing a second coil structure 304, there is a first pair 502 of assembled first coil structures 502A, 502B (lower coil structure) facing a second pair 504 of assembled second coil structures 504A, 504B (upper coil structure). The first pair 502 and the second pair 504 of coil structures are design parameters including the required peak magnetic field at the beam axis 310 and the spatial periodicity λ. uand separated by a distance that depends on the physical characteristics of the electron beam. The beam axis 310 is represented in the X direction and is centered with respect to the coil structure pair 502, 504 in the Y and Z directions. The electron beam oscillates around the axis 310 within the XY plane along the electron beam trajectory 314.

[0112] More precisely, the first coil structures 502A, 502B are composed of a first inner coil structure 502A (closest to the beam axis 310) assembled with a first outer coil structure 502B (farthest from the beam axis 310), and similarly, the second coil structures 504A, 504B are composed of a second inner coil structure 504A assembled with a second outer coil structure 504B.

[0113] The coil structures 502A, 502B, 504A, 504B are preferably similar, except that the inner coil structures 502A, 504A have two end grooves 538A and two end element coils more than the outer coil structures 502B, 504B. For example, they are similar to the coil structures 302, 304 described above. The end groove and the end element coil respectively mean a groove and an element coil located at the end of the longitudinal direction X of the inner coil structure.

[0114] In the example, the inner coil structures 502A, 504A are longer than the outer coil structures 502B, 504B, but this is not essential. For example, the outer coil structures 502B, 504B can be made longer than the inner coil structures 502A, 504A.

[0115] When assembled together, each of the first and second inner and outer coil structures has a distance substantially equal to the sum of the length L of the element coil m and the length L of the adjacent groove S that is, the spatial periodicity λ u offset by half, whereby the meandering shapes of the first and second outer coil structures are inverted with respect to the meandering shapes of the first and second inner coil structures.

[0116] Therefore, as shown in FIG. 5B, the first outer coil structure needs to be powered by a current having a polarity opposite to that of the current supplied to the first inner coil structure in order to avoid canceling the currents in the Y direction and instead combine them. The same applies to the second inner and outer coil structures.

[0117] The grooves 432 and 434 of the first outer structure 502B are aligned in the X direction with the grooves 432 and 434 of the first inner structure 502A that are not at its ends, and the grooves 432 and 434 of the second outer structure 504B are aligned in the X direction with the grooves 432 and 434 of the second inner structure 504A that are not at its ends.

[0118] The grooves 432 and 434 of the second pair 504 of coil structures are preferably aligned in the X direction with the grooves 432 and 434 of the first pair 502 of coil structures.

[0119] The second pair 504 of coil structures is powered by a current having the same polarity as the current supplied to the first pair 502 of coil structures.

[0120] This embodiment can compensate for the undesirable magnetic field errors that may appear with only two coil structures as shown in FIG. 3A, for example, reducing or even canceling the horizontal magnetic field component, i.e., in the XY plane of FIGS. 5A and 5B.

[0121] Also, the coil terminals 510, which are the terminals of the inner coil structures 502A and 504A that enable current to reach and / or depart from the coil structures, are in the same position as the coil terminals 510 of the outer coil structures 502B and 504B for each pair 502 and 504 of inner and outer coil structures. Therefore, the currents in the inner and outer coil structures can reach and return in substantially the same region and direction. This configuration can reduce the undesirable magnetic fields that may be generated differently by the coil terminals.

[0122] In the examples of FIGS. 5A and 5B, two pairs are shown, each being two superconducting coil structures. This is not limiting, and instead of a pair, a multi-structure of two or more superconducting coil structures may be used. Preferably, at least two different superconducting coil structures of each multi-structure are offset by approximately half of the spatial periodicity λ in the X direction u by about half of

[0123] FIG. 6 schematically shows, in a top view, a superconducting coil structure 602 of a superconducting undulator 600 according to another embodiment.

[0124] The superconducting coil structure 602 of FIG. 6 is different from the superconducting coil structure 302 of FIG. 3A mainly in that it mainly includes a current path 602B coupled to a central serpentine coil structure 602A in the X direction and extending on both longitudinal sides thereof.

[0125] This configuration makes it possible to reduce or even cancel the current in the X direction and thus the Y component of the magnetic field. In practice, the Z component of the magnetic field is mainly of interest. Thus, it is not necessary to necessarily have a multi-structure of two or more superconducting coil structures, and the same effect can be obtained.

[0126] The current is represented by small arrows. FIG. 6 shows a specific polarity of the current, but the opposite polarity may also be used. For example, instead of entering the central serpentine coil structure 602A and exiting through the current path 602B, the current may enter the current path 602B and exit through the central serpentine coil structure 602A.

[0127] FIG. 7 shows, in a partial overall perspective view, a superconducting undulator according to another embodiment. The superconducting undulator 700 of FIG. 7 is different from the superconducting undulator 300 of FIG. 3A mainly in that it mainly includes a device 740 for compensating the Lorentz force on the coil structure.

[0128] Device 740 includes, for example, poles made of ferromagnetic material added to the outside of each coil structure (where the inside of the coil structure corresponds to the side facing the beam axis and the outside corresponds to the side opposite the inside), or in the vicinity thereof, and is, for example, composed of such poles. Only the pole on the outside 304B side (the side opposite the inside 304A) of the second coil structure 304 is shown, but it is preferable that another pole is also added to the outside of, or in the vicinity of, the first coil structure 302. The poles can be made of, for example, iron, nickel, or cobalt.

[0129] The ferromagnetic poles are adapted to attract the coils and compensate for the contribution of the Lorentz force.

[0130] The effect of each pole depends on its width w p and / or its length L p and can also be parameterized by the distance d p between the coil and the pole. The distance d p between the coil and the pole can be zero or, for example, equal to about 1 mm. The width w p of the pole can depend on the width w m of the coil structure to which the pole is added. The length L p of the pole can also depend on the length of the coil structure to which the pole is added. For example, the width w p of the pole is 50 - 100 mm, and the length L p of the pole is 500 - 1500 mm. The thickness of the pole can have a small impact on the attraction effect when the ferromagnetic material is not magnetically saturated and can be, for example, about 10 mm.

[0131] Other shapes and / or dimensions of the ferromagnetic poles can be designed to compensate for the contribution of the Lorentz force. Also, the ferromagnetic poles can be arranged at different positions relative to the coil structure.

[0132] FIG. 8A schematically shows in perspective view a superconducting undulator 800 according to another embodiment having another device 840 for compensating the Lorentz force. FIG. 8B schematically shows in cross - sectional view the device 840 for compensating the Lorentz force of FIG. 8A.

[0133] The device 840 of FIGS. 8A and 8B has a different shape from the device 740 of FIG. 7 and is arranged at a different position with respect to the coil structures, here the pair 502, 504 of coil structures of FIGS. 5A and 5B. The device 840 for compensating the Lorentz force comprises, for example, a ferromagnetic pole in the form of a collar, for example an iron collar, surrounding the pair 502, 504 of coil structures and consists of, for example, said collar.

[0134] The width w p and height h p of the ferromagnetic collar are each adapted to the width w m and height h m of the pair 502, 504 of coil structures. The length L p of the iron collar can be made smaller than the length of the pair 502, 504 of coil structures.

[0135] It should be noted that the use of the ferromagnetic poles as shown in the embodiments of FIGS. 7, 8A and 8B aims to remove mechanical loads that may otherwise affect the superconducting structure by compensating for the contribution of the Lorentz force. The ferromagnetic poles of the embodiments have different functions compared to the ferromagnetic poles used in the art which are generally used to increase the amplitude of the magnetic field.

[0136] Furthermore, the ferromagnetic poles of the embodiments do not penetrate the superconducting coil structure as is common in the art. Instead, the ferromagnetic poles of the embodiments are arranged above or around the superconducting coil structure, which provides the functions described above.

[0137] Various embodiments and variations have been described. Those skilled in the art will understand that they can combine the specific features of these embodiments and that other variations will readily occur to those skilled in the art.

[0138] Finally, the actual implementation of the embodiments and variations described herein is within the capabilities of those skilled in the art based on the functional descriptions provided above.

Claims

1. - at least a first superconducting coil structure (302; 402; 502A, 502B; 602), - at least a second superconducting coil structure (304; 504A, 504B) disposed on the opposite side of the first superconducting coil structure comprising The first and second superconducting coil structures are separated by a gap (h ｇ ) dedicated to the passage of an electron beam having an electron beam trajectory (314) around a beam axis (310), and the beam axis is in a first direction (X), each superconducting coil structure - the thickness (h ｍ ) through which the superconducting coil structure is separated into a plurality of element coils (302A, 302B; 402A, 402B) by a plurality of grooves (332, 334; 432, 434), wherein the grooves are configured such that a current flowing through the superconducting coil structure between the grooves can flow alternately in two different directions, for example, substantially two opposite directions, in the superconducting coil structure, and the grooves reach at least one side of the superconducting coil structure, a plurality of grooves, and - a plurality of auxiliary grooves penetrating the thickness of the superconducting coil structure, the auxiliary grooves being spaced apart from the grooves and completely accommodated inside the superconducting coil structure without reaching the sides of the superconducting coil structure comprising an angulator device (300; 400; 500; 600; 700; 800).

2. The first superconducting coil structure (302; 402; 502A, 502B; 602) and the second superconducting coil structure (304; 504A, 504B) extend in a direction substantially parallel to the first direction (X), and the gap (h ｇ ) is in a second direction (Z) substantially perpendicular to the first direction (X), the angular device (300; 400; 500; 600; 700; 800) according to claim 1.

3. The first and second superconducting coil structures are centered on the beam axis (310) in the second direction (Z) and preferably in a third direction (Y) perpendicular to the first and second directions, of the angulator device (300; 400; 500; 600; 700; 800) according to claim 2.

4. The alternating different directions of the current correspond to two opposite directions in a third direction (Y) perpendicular to the first and second directions, of the angulator device (300; 400; 500; 600; 700; 800) according to claim 2 or 3.

5. The plurality of grooves (332, 334; 432, 434) extend in a third direction (Y) perpendicular to the first and second directions, the grooves being, for example, substantially straight, of the angulator device (300; 400; 500; 600; 700; 800) according to any one of claims 2 to 4.

6. Each of the grooves (332, 334; 432, 434) starts from a first side (306A) of the superconducting coil structure or a second side (306B) of the superconducting coil structure opposite to the first side and stops at a position at a certain distance from the second side (306B) or the first side (306A) of the superconducting coil structure, the first and second sides extending, for example, in the first direction (X), of the angulator device (300; 400; 500; 600; 700; 800) according to any one of claims 1 to 5.

7. The grooves are regularly distributed in the first direction (X), of the angulator device (300; 400; 500; 600; 700; 800) according to any one of claims 1 to 6.

8. The plurality of grooves includes a first groove (332; 432) that starts from the first side (306A) and stops at a position at a first distance from the second side (306B), and a second groove (334; 434) that starts from the second side (306B) and stops at a position at a second distance (d ｓ ) from the first side (306A), the first and second grooves being alternating, and the first and second distances being equal, for example, the angulator device (300; 400; 500; 600; 700; 800) according to claim 7, which depends on claim 6.

9. - The dimension (L ｓ ) in the first direction (X) of each groove (332, 334; 432, 434) is 0.01 mm or more, for example 0.05 mm or more, and / or - The dimension (L ｍ ) in the said first direction (X) of each element coil (302A, 302B; 402A, 402B) is 20 mm or less, and / or - The dimension (h ｇ ) in the second direction (Z) parallel to the direction of the gap (h ｍ ) of each superconducting coil structure is 10 mm or less, preferably 1 mm or less. The angulator device (300; 400; 500; 600; 700; 800) according to any one of claims 1 to 8.

10. The at least one second superconducting coil structure (304; 504A, 504B) is adapted to be powered by a current having the same polarity as the current adapted to power the at least one first superconducting coil structure (302; 402; 502A, 502B), the angulator device (300; 400; 500; 600; 700; 800) according to any one of claims 1 to 9.

11. The grooves (332, 334; 432, 434) of the at least one first superconducting coil structure are aligned in the first direction (X) with the grooves (332, 334; 432, 434) of the at least one second superconducting coil structure, the angulator device (300; 400; 500; 600; 700; 800) according to any one of claims 1 to 10.

12. The auxiliary grooves are substantially curved, for example, substantially following the shape of the current lines between the grooves, and / or at least one (438) of the auxiliary grooves is in at least two parts, the angulator device (400) according to any one of claims 1 to 11.

13. The at least one first superconducting coil structure is a first multi-structure (502) comprising at least a first inner superconducting coil structure (502A) and a first outer superconducting coil structure (502B) assembled together, the at least one second superconducting coil structure is a second multi-structure (504) comprising at least a second inner superconducting coil structure (504A) and a second outer superconducting coil structure (504B) assembled together, the first and second multi-structures are, for example, pairs, for example, similar pairs, the angulator device (500) according to any one of claims 1 to 12.

14. - Each of the first inner superconducting coil structure (502A) and the second inner superconducting coil structure (504A) is longer or smaller than each of the first outer superconducting coil structure (502B) and the second outer superconducting coil structure (504B), and / or - Each of the first inner superconducting coil structure (502A) and the second inner superconducting coil structure (504A) has two end grooves (538A) and two end element coils that are more or less than those of each of the first outer superconducting coil structure (502B) and the second outer superconducting coil structure (504B), and / or - Each of the inner superconducting coil structure of the first (502A) and the second inner superconducting coil structure (504A) is, for example, with respect to each of the first outer superconducting coil structure (502B) and the second outer superconducting coil structure (504B), the sum of the dimensions in the first direction of a certain element coil among the plurality of element coils and one groove among the plurality of grooves adjacent to the element coil (L ｍ , L ｓ ) is offset in the first direction (X) by a distance equal to, and / or - Each of the first outer superconducting coil structure (502B) and the second outer superconducting coil structure (504B) is powered by a current having a polarity opposite to that of the current supplied to each of the first inner superconducting coil structure (502A) and the second inner superconducting coil structure (504A). The undulator device (500) according to claim 13.

15. - Each superconducting coil structure preferably has at least a planar portion along the electron beam trajectory (314), and / or - The plurality of element coils of each superconducting coil structure form a meandering structure. The undulator device (300; 400; 500; 600; 700; 800) according to any one of claims 1 to 14.

16. Each superconducting coil structure (602) further comprises at least one current path (602B) coupled to the plurality of element coils (602A), the at least one current path extending in the first direction (X), preferably comprising two current paths, one on each side parallel to the first direction of the plurality of element coils (602A). The undulator device (600) according to any one of claims 1 to 15.

17. A device (740; 840) for compensating the Lorentz force on the first and second superconducting coil structures, for example, further comprising a ferromagnetic collar surrounding the first and second superconducting coil structures. The undulator device (700; 800) according to any one of claims 1 to 16.

18. Each superconducting coil structure comprises a stacking of different layers (320), for example consisting of the stacking (320), and the stacking is - A substrate layer (322) composed or coated with a material such as Hastelloy, - at least one buffer layer (324) on the substrate layer, preferably a plurality of buffer layers, wherein the at least one buffer layer is composed of a material such as, for example, alumina, yttria, magnesium oxide, and / or lanthanum manganite, at least one buffer layer; - a superconducting layer (326) on the at least one buffer layer (324), wherein the superconducting layer is a superconducting material or a material adapted to be superconducting under appropriate conditions such as below a temperature limit, for example, a rare earth-based material such as rare earth barium copper oxide or yttrium barium copper oxide, superconducting layer (326); comprising; The substrate layer (322) includes, for example, at least a tube to enable a cooling fluid such as nitrogen or helium to flow through the superconducting coil structure and / or to enable wiring to pass through the superconducting coil structure. The angulator device according to any one of claims 1 to 17.

19. The stacking (320) is - a repetition of the buffer layer and the superconducting layer, preferably several (N times) repetitions, for example, 1 to 25 repetitions, and in some cases, - a repetition of the substrate layer (322) and the repeated buffer layer and superconducting layer, preferably several (M times) repetitions, for example, 1 to 25 repetitions The angulator device according to claim 18, comprising.

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