Undulator control method and device, undulator and optical system

Abstract

The invention relates to an undulator control method and device, an undulator and an optical system. The undulator control method comprises the following steps: keeping the temperature of the superconducting material part to be greater than or equal to a first preset temperature by the temperature control part, and generating a background magnetic field with first preset background field intensity by the first magnetic field generation part; the background field intensity of the background magnetic field is kept unchanged as the first preset background field intensity, and the temperature of the superconducting material part is reduced from the first preset temperature to the second preset temperature through the temperature control part; the superconducting material part is kept in a superconducting state, and the background field intensity is reduced from the first preset background field intensity to the second preset background field intensity by the first magnetic field generation part, so that the superconducting material part generates an undulating magnetic field with the preset undulating field intensity; and keeping the background field intensity unchanged as a second preset background field intensity, and raising the temperature of the superconducting material part by the temperature control part so as to reduce the undulating field intensity of the undulating magnetic field until the undulator generates light with the target fundamental wavelength.

Description

Technical Field

[0001] The present disclosure relates to the field of electromagnetic technology, and more specifically, to an undulator control method and device, an undulator, and an optical system. Background Art

[0002] An undulator is a device that can provide a periodic magnetic field, which can be used to generate high-intensity free electron lasers, etc. At present, undulators can be formed based on permanent magnets (for example, neodymium iron boron (NdFeB) or samarium cobalt (SmCo), etc.) or superconducting magnets. Among them, the technology of permanent magnet undulators is relatively mature, but due to the constraints of the residual magnetic field of the permanent magnet, the period of this undulator is difficult to be further shortened. Compared with permanent magnet blocks, superconducting blocks can capture larger magnetic fields, and accordingly, the performance of superconducting undulators can be greatly improved. At present, there are several undulator structures based on superconducting bulk materials, including: (1) using a uniform magnetic field in a vertical direction perpendicular to the axial direction of the undulator (e.g., a dipole field provided by a rectangular coil) to magnetize two rows of axially arranged superconducting bulk materials to generate an axially distributed plane undulating magnetic field; (2) using a uniform magnetic field in the axial direction (e.g., a background field provided by a solenoid coil) to magnetize superconducting bulk materials arranged in staggered rows to generate an axially distributed plane undulating magnetic field; (3) using a uniform magnetic field in the axial direction to magnetize superconducting bulk materials arranged in a rotationally staggered row to generate an axially distributed spiral undulating magnetic field. However, there is still room for improvement in the above-mentioned undulators based on superconducting bulk materials. Summary of the invention

[0003] The present disclosure aims to provide an undulator control method and device, an undulator and an optical system, which change the flux pinning force in the superconducting material part of the undulator by adjusting the temperature, thereby changing the undulator magnetic field of the undulator to obtain light with a desired fundamental wavelength.

[0004] According to a first aspect of the present disclosure, an undulator control method is provided, wherein the undulator comprises a first magnetic field generating component for generating a background magnetic field and a second magnetic field generating component for generating an undulating magnetic field, wherein the second magnetic field generating component comprises a superconducting material portion and a temperature control portion, and the undulator control method comprises:

[0005] The temperature control unit maintains the temperature of the superconducting material unit at a temperature greater than or equal to a first preset temperature so that the superconducting material unit is in a non-superconducting state, and the first magnetic field generating component generates a background magnetic field with a first preset background field strength;

[0006] The background field strength of the background magnetic field is maintained at a first preset background field strength, and the temperature control unit reduces the temperature of the superconducting material portion from the first preset temperature to the second preset temperature, so that the superconducting material portion is transformed from a non-superconducting state to a superconducting state;

[0007] The superconducting material portion is kept in a superconducting state, and the first magnetic field generating component reduces the background field strength from a first preset background field strength to a second preset background field strength, so that the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, wherein the second preset background field strength is zero or the second preset background field strength is less than or equal to a preset field strength threshold; and

[0008] The background field intensity is maintained at a second preset background field intensity, and the temperature of the superconducting material portion is increased by the temperature control portion to reduce the undulating field intensity of the undulating magnetic field until the undulator generates light having a target fundamental wavelength.

[0009] In some embodiments, the target fundamental wavelength is in the range of 6.5 to 13.5 nm.

[0010] In some embodiments, increasing the temperature of the superconducting material portion by the temperature control portion comprises:

[0011] The temperature of the superconducting material portion is increased by the temperature control portion at a first preset rate to avoid quenching of the superconducting material portion.

[0012] In some embodiments, generating a background magnetic field having a first preset background field strength by the first magnetic field generating component includes increasing the background field strength from zero to the first preset background field strength at a constant second preset rate by the first magnetic field generating component; and / or

[0013] Reducing the background field strength from the first preset background field strength to the second preset background field strength by the first magnetic field generating component includes reducing the background field strength from the first preset background field strength to the second preset background field strength by the first magnetic field generating component at a constant third preset rate.

[0014] In some embodiments, after the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, the undulator control method further includes:

[0015] The temperature control unit lowers the temperature of the superconducting material unit to a third preset temperature to freeze the magnetic flux of the superconducting material unit.

[0016] In some embodiments, the first preset temperature is in the range of 80-100K or 100-120K;

[0017] The second preset temperature is in the range of 5-10K or 10-15K; and / or

[0018] The third preset temperature is in the range of 3-7K or 7-11K.

[0019] In some embodiments, after the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, the undulator control method further includes:

[0020] measuring a phase error of the undulating magnetic field;

[0021] comparing the measured phase error with a preset phase threshold; and

[0022] When the measured phase error is greater than or equal to a preset phase threshold, magnetic field shimming is performed on the superconducting material portion.

[0023] According to a second aspect of the present disclosure, an undulator control device is provided, the undulator control device comprising a memory and a processor, the memory storing instructions, and when the instructions are executed by the processor, the steps of the undulator control method as described above are implemented.

[0024] According to a third aspect of the present disclosure, an undulator is provided, the undulator being configured to generate light having an adjustable target fundamental wavelength, the undulator comprising:

[0025] A first magnetic field generating component, the first magnetic field generating component is configured to generate a background magnetic field; and

[0026] A second magnetic field generating component, wherein the second magnetic field generating component is configured to generate a undulating magnetic field, and the second magnetic field generating component includes a superconducting material portion and a temperature control portion, wherein the superconducting material portion is positioned to generate the undulating magnetic field under the action of the background magnetic field, and the temperature control portion is configured to continuously adjust and maintain the temperature of the superconducting material portion.

[0027] In some embodiments, the undulator further comprises an undulator control device according to claim 8.

[0028] In some embodiments, the first magnetic field generating component is disposed in a first vacuum chamber, the second magnetic field generating component is disposed in a second vacuum chamber, and the first vacuum chamber and the second vacuum chamber are isolated from each other.

[0029] In some embodiments, the superconducting material portion is configured such that an undulator period of the undulator is less than or equal to 10 mm.

[0030] In some embodiments, the superconducting material portion is formed of a high temperature superconducting bulk material.

[0031] In some embodiments, the superconducting material portion includes a plurality of superconducting units arranged at intervals along the axial direction of the undulator, wherein each superconducting unit includes a superconducting block and a superconducting ring arranged around the superconducting block, and any two adjacent superconducting units are staggered in a vertical direction perpendicular to the axial direction to generate a periodic undulating magnetic field.

[0032] In some embodiments, the undulator further comprises:

[0033] A beam chamber is provided through a gap between the superconducting block and the superconducting ring in each superconducting unit.

[0034] In some embodiments, the outer contour of the superconducting block is consistent with the inner contour of the superconducting ring; and

[0035] The inner contour shape of the superconducting ring is consistent with the outer contour shape of the superconducting ring.

[0036] In some embodiments, a cross section of the superconducting block perpendicular to the axial direction is rectangular, circular, or semicircular.

[0037] In some embodiments, the temperature control unit includes:

[0038] a heater attached to the superconducting material portion; and

[0039] A gas-liquid two-phase cooling pipe is spirally wound around the superconducting material portion.

[0040] In some embodiments, the temperature control unit includes:

[0041] a heater attached to the superconducting material portion;

[0042] Refrigeration machine;

[0043] Thermally conductive connecting wires; and

[0044] One or more flanges, wherein the refrigerator is thermally connected to the superconducting material portion via the thermally conductive connection line and the one or more flanges.

[0045] According to a fourth aspect of the present disclosure, an optical system is provided, which includes the undulator as described above, and the optical system is a synchrotron radiation system, a free electron laser generation system or a lithography system.

[0046] Other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0048] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

[0049] Figure 1 A schematic structural diagram of an undulator according to an exemplary embodiment of the present disclosure is shown;

[0050] Figure 2 A schematic flow chart of an undulator control method according to an exemplary embodiment of the present disclosure is shown;

[0051] Figure 3 A schematic flow chart of an undulator control method according to another exemplary embodiment of the present disclosure is shown;

[0052] Figure 4 A partial flow chart of an undulator control method according to another exemplary embodiment of the present disclosure is shown;

[0053] Figure 5 A block diagram of an undulator control device according to an exemplary embodiment of the present disclosure is shown;

[0054] Figure 6 A schematic diagram of the structure of a superconducting material portion and a beam chamber in an undulator according to a specific embodiment of the present disclosure is shown;

[0055] Figure 7 A schematic structural diagram of a superconducting material portion and a beam chamber in an undulator according to another specific embodiment of the present disclosure is shown;

[0056] Figure 8 A schematic diagram showing magnetization current distribution in a superconducting material portion of an undulator according to a specific embodiment of the present disclosure is shown;

[0057] Fig. 9 A schematic structural diagram of a second magnetic field generating component in an undulator according to a specific embodiment of the present disclosure is shown;

[0058] Fig.10 A schematic structural diagram of a second magnetic field generating component in an undulator according to another specific embodiment of the present disclosure is shown.

[0059] Note that in the embodiments described below, the same reference numerals are sometimes used in common between different drawings to represent the same parts or parts with the same functions, and their repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0060] For ease of understanding, the positions, sizes, and ranges of various structures shown in the drawings and the like sometimes do not represent actual positions, sizes, and ranges, etc. Therefore, the disclosed invention is not limited to the positions, sizes, and ranges, etc. disclosed in the drawings and the like. In addition, the drawings are not necessarily drawn to scale, and some features may be exaggerated to show details of specific components. DETAILED DESCRIPTION

[0061] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0062] The following description of at least one exemplary embodiment is merely illustrative in nature and is not intended to limit the present disclosure and its application or use. It will be appreciated by those skilled in the art that they are merely exemplary, rather than exhaustive, ways in which the present disclosure may be implemented.

[0063] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0064] In an undulator based on a superconducting block, the background magnetic field can be used to magnetize the superconducting block, thereby generating a periodic undulating magnetic field. Further, when a high-energy electron beam passes through the undulating magnetic field, radiated light can be generated. Among them, the fundamental wavelength of the light is related to parameters such as the electron beam energy, the undulator period, and the undulating magnetic field strength. In an exemplary embodiment of the present disclosure, a scheme is proposed that can adjust the fundamental wavelength of the light generated by the undulator to improve the controllability and flexibility of the undulator so that it can better meet the needs of scientific research or production.

[0065] In an exemplary embodiment of the present disclosure, Figure 1 As shown, the undulator 100 may include a first magnetic field generating component 110 for generating a background magnetic field and a second magnetic field generating component 120 for generating an undulating magnetic field. For example, the first magnetic field generating component 110 may be formed by a superconducting solenoid magnet or other types of magnetic field generating components capable of generating a background magnetic field, and the second magnetic field generating component 120 may include a superconducting material portion 121 and a temperature control portion 122. The first magnetic field generating component 110 or the superconducting solenoid magnet may generate an axial (e.g., Figure 6 The background magnetic field of the z-axis shown in the figure is used to induce the superconducting material part 121 in the second magnetic field generating part 120 to generate an undulating magnetic field in the axial direction. In addition, the temperature control part 122 in the second magnetic field generating part 120 can be used to adjust the temperature of the superconducting material part 121 to keep it in a desired state or to adjust the undulating field strength of the undulating magnetic field generated by it. Based on the above undulator, as Figure 2 As shown, in an exemplary embodiment of the present disclosure, the undulator control method may include:

[0066] In step S910, the temperature control unit 122 maintains the temperature of the superconducting material unit 121 at a temperature greater than or equal to a first preset temperature so that the superconducting material unit 121 is in a non-superconducting state, and the first magnetic field generating component 110 generates a background magnetic field having a first preset background field strength.

[0067] Specifically, the first preset temperature can be determined according to the critical temperature of the superconducting material portion 121, and the first preset temperature should be greater than the critical temperature of the superconducting material portion 121 to keep the superconducting material portion 121 in a non-superconducting state. In some embodiments, the superconducting material portion 121 can be a block formed of a high-temperature superconducting material (usually a superconducting material with a critical temperature above 30K). Such a high-temperature superconducting block can generate a strong undulating magnetic field, thereby helping to reduce the undulator period and thereby reduce the size of the entire undulator under the condition of generating light of the same fundamental wavelength, so as to reduce the manufacturing and operating costs of the undulator. For example, depending on the type of high-temperature superconducting material selected, the first preset temperature can be in the range of 80 to 100K or 100 to 120K. In a specific example, the temperature control portion 122 can maintain the temperature of the superconducting material portion 121 at a temperature greater than or equal to 100K to keep the superconducting material portion 121 in a non-superconducting state.

[0068] When the superconducting material portion 121 is in a non-superconducting state, the first magnetic field generating component 110 can generate a background magnetic field having a first preset background field strength. In some embodiments, the first magnetic field generating component 110 can increase the background field strength from zero to the first preset background field strength at a constant second preset rate, and increasing the field strength at a constant rate helps to simplify the control of the first magnetic field generating component 110. However, it can be understood that in some other embodiments, the background field strength can also be increased from zero to the first preset background field strength at a variable rate, which is not limited here. In some embodiments, the first preset background field strength can be calculated or determined based on the target fundamental wavelength of the light to be generated. In addition, since the present disclosure involves unidirectional adjustment of the fundamental wavelength of light, a certain margin can be reserved when calculating or determining the first preset background field strength. Specifically, the first preset background field strength can be greater than or equal to the background field strength corresponding to the undulating field strength of the light used to generate the target fundamental wavelength, as will be described in detail later.

[0069] return Figure 2 , the undulator control method may further include:

[0070] Step S920, maintaining the background field strength of the background magnetic field at the first preset background field strength, and reducing the temperature of the superconducting material part 121 from the first preset temperature to the second preset temperature by the temperature control part 122, so that the superconducting material part 121 changes from the non-superconducting state to the superconducting state.

[0071] Under the premise that the superconducting material portion 121 is in a superconducting state, the magnetization of the superconducting material portion 121 can be achieved. Here, the second preset temperature should be less than or equal to the critical temperature of the superconducting material used to form the superconducting material portion 121. In addition, in some embodiments, in order to ensure that the superconducting material portion 121 can be stably in a superconducting state, and for the consideration of reducing the change of magnetic flux in the superconducting material portion 121, the second preset temperature can be much smaller than the critical temperature of the superconducting material. For example, in the case where the superconducting material portion 121 is formed of a high-temperature superconducting material, the second preset temperature can be much smaller than the critical temperature of the high-temperature superconducting material, for example, the second preset temperature can be in the range of 5 to 10K or 10 to 15K. In a specific example, the temperature control portion 122 can reduce the temperature of the superconducting material portion 121 from 100K to 10K, so that the superconducting material portion 121 is transformed from a non-superconducting state to a superconducting state, and the superconducting material portion 121 can be stably maintained in a superconducting state to avoid quenching caused by external interference.

[0072] return Figure 2 , the undulator control method may further include:

[0073] Step S930, keeping the superconducting material portion 121 in a superconducting state, the first magnetic field generating component 110 reduces the background field strength from the first preset background field strength to the second preset background field strength, so that the superconducting material portion 121 generates an undulating magnetic field with a preset undulating field strength.

[0074] Among them, the second preset background field strength can be zero, or the second preset background field strength can be a very small field strength, for example, less than or equal to the preset field strength threshold. Due to the flux pinning characteristics of superconducting materials, when the background magnetic field decreases from the first preset background field strength to the second preset background field strength, the superconducting material part 121 can be magnetized to induce a permanent magnetization current, and then an undulating magnetic field with a preset undulating field strength can be generated. It should be noted that in the undulator, the undulating magnetic field is a periodic magnetic field formed by the superconducting material part 121 with a periodic structure, for example, it can be an undulating magnetic field whose field strength varies in a sinusoidal or cosine form along the axial direction. Accordingly, the undulating field strength described in this article refers to the maximum magnetic field intensity or the magnetic field intensity amplitude in the periodic undulating magnetic field.

[0075] In addition, it can be understood that the preset undulation field strength is related to the first preset background field strength and the relative position relationship between the superconducting material part 121 and the first magnetic field generating component 110. Therefore, the preset undulation field strength and / or the first preset background field strength can be predetermined or calculated based on the target fundamental wavelength of the light to be generated and the structural parameters of the undulator.

[0076] In addition, in the embodiments of the present disclosure, since the background field strength can be reduced to the second preset background field strength by controlling the first magnetic field generating component 110, especially when the second preset background field strength is zero, the adverse effects of the remaining background magnetic field on the electron beam bunching performance can be well avoided, thereby improving the quality of light generated by the undulator.

[0077] Similarly, in some embodiments, the first magnetic field generating component 110 can reduce the background field strength from the first preset background field strength to the second preset background field strength at a constant third preset rate, and reducing the field strength at a constant rate helps to simplify the control of the first magnetic field generating component 110. However, it can be understood that in some other embodiments, the background field strength can also be reduced from the first preset background field strength to the second preset background field strength at a variable rate, which is not limited here.

[0078] return Figure 2 , the undulator control method may further include:

[0079] Step S940, maintaining the background field strength at the second preset background field strength, and increasing the temperature of the superconducting material portion 121 by the temperature control portion 122 to reduce the undulating field strength of the undulating magnetic field until the undulator 100 generates light having a target fundamental wavelength.

[0080] Specifically, according to the undulator equation, the fundamental wavelength λ of the generated light can be expressed as Where K' is the deflection coefficient and can be expressed as λ u is the undulator period, γ is the Lorentz factor and can be used to characterize the energy of the electron, e is the electron charge, B0 is the undulating field strength of the undulating magnetic field, m is the electron mass, and c is the speed of light in vacuum.

[0081] According to the above undulator equation, the fundamental wavelength of the generated light is related to the undulator period, the electron beam energy and the undulator field strength of the undulator magnetic field. In addition, during the operation of the undulator, the energy of the input electron beam and the undulator structural parameters (for example, the undulator period) are usually determined and difficult to change. Therefore, if it is desired to adjust the fundamental wavelength of the generated free electron laser in real time and continuously during the operation of the undulator, it can be achieved by changing the undulator field strength of the undulator magnetic field. Specifically, the temperature of the superconducting material part 121 can be increased by the temperature control part 122, so that the magnetic flux pinning force in the superconducting material part 121 decreases with the increase in temperature, thereby reducing the undulator field strength of the undulator magnetic field, or reducing the deflection coefficient K' of the undulator, thereby reducing the fundamental wavelength of the free electron laser. When the fundamental wavelength of the generated free electron laser reaches the target fundamental wavelength, the temperature control part 121 can stop further heating to continuously generate a free electron laser with a target fundamental wavelength.

[0082] In some embodiments, the undulator period can be set to be less than or equal to 10 mm, and accordingly, the deflection coefficient K' can be in the range of 1 to 2. Among them, a too large K' value corresponds to a too large deflection angle, which affects the coherence characteristics of the free electron laser, and a too small K' value will increase the length of the undulator system and increase the cost.

[0083] In some embodiments, the temperature control portion 122 may increase the temperature of the superconducting material portion 121 slowly enough, for example, may increase the temperature of the superconducting material portion 121 at a first preset rate, thereby avoiding quenching of the superconducting material portion 121 .

[0084] In addition, in some embodiments, the adjustment of the fundamental wavelength is usually unidirectional, that is, the fundamental wavelength of the generated free electron laser can only be reduced by increasing the temperature of the superconducting material part 121 within a certain range, and the fundamental wavelength cannot be increased by reducing the temperature of the superconducting material part 121. Therefore, when determining the first preset background field strength and the preset undulation field strength initially generated, the first preset background field strength and the preset undulation field strength can be appropriately increased, thereby reserving a certain margin for subsequent adjustments. In some embodiments, the light generated may include a free electron laser in the extreme ultraviolet (EUV) band, and its wavelength may be in the range of, for example, 6.5 to 13.5 nm. Light in this band can be widely used in lithography machine systems. During the operation of the undulator, by adjusting the temperature of the superconducting material part 121, the fundamental wavelength of the radiated light can be reduced in the range from 13.5 nm to 6.5 nm, thereby obtaining the desired target fundamental wavelength. In addition, it can be understood that in some other embodiments, the undulator can also be used to generate light in other bands, such as from infrared light to ultraviolet light, soft X-rays, hard X-rays, etc., without limitation herein.

[0085] In another exemplary embodiment of the present disclosure, Figure 3 As shown, after the superconducting material portion 121 generates an undulating magnetic field with a preset undulating field strength, the undulator control method may further include:

[0086] In step S950 , the temperature control unit 122 lowers the temperature of the superconducting material unit 121 to a third preset temperature to freeze the magnetic flux of the superconducting material unit 121 .

[0087] Specifically, there is a flux creep effect in the superconducting material, that is, due to the thermal activation energy, the magnetic flux lines break away from the original pinning center and jump to another pinning center, thereby causing the magnetic flux lines to flow slowly. In order to suppress or eliminate the flux creep, the temperature of the superconducting material part 121 can be further reduced to a third preset temperature by the temperature control part 122 to freeze the magnetic flux. For example, the third preset temperature can be in the range of 3 to 7K or 7 to 11K. In a specific example, the temperature control part 122 can further reduce the temperature of the superconducting material part 121 from 10K to 7K to freeze the magnetic flux. In addition, in some embodiments, such as Figure 3 As shown, step S940 may be performed after step S950, that is, the temperature of the superconducting material portion 121 may be slowly increased after the magnetic flux is frozen, so as to reduce the undulating magnetic field by slowly reducing the magnetic flux pinning force in the superconducting material portion 121, thereby reducing the fundamental wavelength of the generated free electron laser. Alternatively, in other embodiments, step S940 may also be performed before step S950, that is, the magnetic flux may be frozen by cooling after light having a target fundamental wavelength is generated.

[0088] In another exemplary embodiment of the present disclosure, before the undulator is officially put into operation, a debugging operation such as magnetic field shimming may be performed on it to improve the performance of the undulator. Specifically, in the process of debugging the undulator, the superconducting material portion 121 may be made to generate an undulating magnetic field according to steps S910 to S930, or according to steps S910 to S950. After the superconducting material portion 121 generates an undulating magnetic field with a preset undulating field strength, Figure 4 As shown, the undulator control method may further include:

[0089] Step S961, measuring the phase error of the undulating magnetic field;

[0090] Step S962, comparing the measured phase error with a preset phase threshold; and

[0091] Step S963 , when the measured phase error is greater than or equal to a preset phase threshold, magnetic field shimming is performed on the superconducting material portion 121 .

[0092] That is to say, steps S961 to S963 may be performed during the debugging of the undulator. By comparing the measured phase error of the undulating magnetic field with the preset phase threshold after the undulator generates an undulating magnetic field, the superconducting material portion 121 may be shimmed for magnetic field. For example, the magnetic field shimming may be achieved by changing the structure and other parameters of the superconducting material portion 121 (for example, adjusting the magnetic pole height, replacing the block material, etc.), so that the superconducting material portion 121 can generate a more ideal undulating magnetic field to improve the performance of the undulator. It is understandable that once the debugging of the undulator is completed and the undulator enters a normal working state, steps S961 to S963 may no longer be performed unless the undulating magnetic field has undergone a significant change.

[0093] The present disclosure also provides an undulator control device, such as Figure 5 As shown, the undulator control device may include a memory 510 and a processor 520. The memory 510 stores instructions. When the instructions are executed by the processor 520, the steps of the undulator control method described above may be implemented.

[0094] Among them, the processor 520 can perform various actions and processes according to the instructions stored in the memory 510. Specifically, the processor 520 can be an integrated circuit chip with signal processing capabilities. The above-mentioned processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The various methods, steps and logic block diagrams disclosed in the embodiments of the present disclosure can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc., which can be an X86 architecture or an ARM architecture, etc.

[0095] The memory 510 stores executable instructions, which are executed by the processor 520 to perform the undulator control method described above. The memory 510 can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. The non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM) or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous connection dynamic random access memory (SLDRAM) and direct memory bus random access memory (DR RAM). It should be noted that the memory of the method described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0096] The present disclosure also provides a non-transitory computer-readable storage medium having instructions stored thereon. When the instructions are executed by a processor, the steps of the undulator control method described above can be implemented.

[0097] Similarly, the computer-readable storage medium in the embodiments of the present disclosure may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory. It should be noted that the computer-readable storage medium described herein is intended to include but is not limited to these and any other suitable types of memory.

[0098] The present disclosure also provides a computer program product, which includes instructions. When the instructions are executed by a processor, the steps of the undulator control method described above can be implemented.

[0099] Instructions may be any set of instructions to be executed directly by one or more processors, such as machine code, or any set of instructions to be executed indirectly, such as a script. The terms "instructions," "application," "process," "step," and "program" herein may be used interchangeably herein. Instructions may be stored in an object code format for direct processing by one or more processors, or as a script or collection of independent source code modules in any other computer language, including those interpreted on demand or compiled in advance. Instructions may include instructions that cause one or more processors, such as to act as the various neural networks herein. The functions, methods, and routines of the instructions are explained in more detail elsewhere herein.

[0100] The present disclosure also provides an undulator, which can be configured to generate light having an adjustable target fundamental wavelength. In some embodiments, the undulator control method and / or undulator control device as described above can be used to control the undulator. Figure 1 As shown, in an exemplary embodiment of the present disclosure, the undulator 100 may include a first magnetic field generating component 110 and a second magnetic field generating component 120. Among them, the first magnetic field generating component 110 may be configured to generate a background magnetic field, and the second magnetic field generating component 120 may be configured to generate an undulating magnetic field. In some embodiments, the undulator may also include an undulator control device as described above to achieve adjustment of the fundamental wavelength of the light generated by it. However, it can be understood that in some other embodiments, the undulator control device may also be set independently of the undulator.

[0101] In some embodiments, the first magnetic field generating component 110 may be formed by a superconducting solenoid magnet, which may provide a magnetic field exceeding 10 T, for example. Figure 1 As shown, the first magnetic field generating component 110 or the superconducting solenoid magnet may include a GM refrigerator 111, a refrigeration service tower 112, a room temperature dewar 113, a low temperature dewar (e.g., a 50K dewar) 114, and a superconducting coil 115. The superconducting coil may be formed of, for example, Nb-Ti or Nb3Sn round wire.

[0102] Furthermore, in some embodiments, Figure 1 As shown, the second magnetic field generating component 120 may include a superconducting material portion 121 and a temperature control portion 122, wherein the superconducting material portion 121 may be positioned to generate an undulating magnetic field under the action of a background magnetic field, for example, it may be arranged adjacent to the first magnetic field generating component 110, and under normal circumstances, the generated undulating magnetic field will increase with the increase of the background magnetic field. The temperature control portion 122 may be configured to continuously adjust and maintain the temperature of the superconducting material portion 121, for example, temperature control may be achieved within a range from 100K to 7K, and the controlled axial temperature difference may be lower than 0.1K, and the temperature control accuracy may be better than 0.1K, so that radiation light having a target fundamental wavelength may be generated based on the undulator control method as described above.

[0103] In some embodiments, Figure 1As shown, the undulator may include a first vacuum chamber and a second vacuum chamber isolated from each other, wherein the first magnetic field generating component 110 may be disposed in the first vacuum chamber, and the second magnetic field generating component 120 may be disposed in the second vacuum chamber, so as to individually control or adjust parameters such as temperature and vacuum degree associated with each magnetic field generating component. However, it is understandable that in some other embodiments, the first magnetic field generating component 110 and the second magnetic field generating component 120 may also be disposed in the same vacuum chamber, but this may lead to an increase in the time required for operations such as magnetic field shimming, because a larger vacuum chamber often requires more time to achieve a change in vacuum degree.

[0104] In some embodiments, the superconducting material portion may be formed of a high-temperature superconducting bulk material. On the one hand, the high-temperature superconducting material helps to increase the operating temperature of the undulator, thereby reducing the operating cost of the undulator. On the other hand, the high-temperature superconducting bulk material can capture a stronger magnetic field, thereby forming a stronger undulating magnetic field, which can effectively reduce the required undulator period while generating light of the same fundamental wavelength, thereby reducing the overall size of the undulator. In some embodiments, by adopting a superconducting material portion 121 having a suitable material and structure, the undulator period can be made less than or equal to 10 mm. In addition, reducing the undulator period can help significantly reduce the required energy of the electron beam, thereby reducing the length of the linear accelerator that accelerates the electron beam, thereby reducing costs.

[0105] In some embodiments, Figure 6 and Figure 7 As shown, the superconducting material portion 121 may include a portion along the axial direction of the undulator (ie, Figure 6 A plurality of superconducting units are arranged at intervals (in the z direction), wherein each superconducting unit may include a superconducting block 121a and a superconducting ring 121b arranged around the superconducting block 121a, and any two adjacent superconducting units are connected in a vertical direction perpendicular to the axial direction (i.e., Figure 6 The superconducting units are arranged in a staggered manner in the y direction to generate a periodic undulating magnetic field. For example, the magnetizing current generated in the superconducting unit is distributed as follows: Figure 8 As shown in the figure, "-" indicates that the current direction is perpendicular to the paper and outward (i.e., along Figure 6 The positive x direction in the figure indicates that the current is in the positive x direction, and the “+” indicates that the current is in the direction perpendicular to the paper (i.e., along Figure 6negative x direction in the paper). In the first superconducting unit from the left, the magnetizing current direction of the upper part of the superconducting ring 121b is perpendicular to the paper and outward, the magnetizing current direction of the lower part of the superconducting ring 121b is perpendicular to the paper and inward, the magnetizing current direction of the upper part of the superconducting block 121a is perpendicular to the paper and outward, and the magnetizing current direction of the lower part of the superconducting block 121a is perpendicular to the paper and inward. Similarly, in the second superconducting unit from the left, the magnetizing current direction of the upper part of the superconducting ring 121b is perpendicular to the paper and inward, the magnetizing current direction of the lower part of the superconducting ring 121b is perpendicular to the paper and inward, the magnetizing current direction of the upper part of the superconducting block 121a is perpendicular to the paper and outward, and the magnetizing current direction of the lower part of the superconducting block 121a is perpendicular to the paper and inward. Along the z-axis direction, the current directions at the same vertical position (same y coordinate) are alternately reversed, thereby forming a periodic undulating magnetic field. Among them, two adjacent superconducting units can form a period of the undulator, and its size in the z-axis direction corresponds to the undulator period, Figure 8 In the specific example shown, there are five undulator cycles in total. The superconducting unit is formed by providing the superconducting blocks 121a and the superconducting rings 121b which are electrically isolated from each other, which helps to improve the efficiency of magnetic field utilization so as to generate an undulating magnetic field of sufficient strength. Figure 6 and Figure 7 In the specific embodiment shown, in any two adjacent superconducting units, the lower gap between the superconducting block 121a and the superconducting ring 121b in one superconducting unit is at least partially aligned with the upper gap between the superconducting block 121a and the superconducting ring 121b in the other superconducting unit in the axial direction, so as to achieve a staggered arrangement of multiple superconducting units. In addition, the undulator may also include a beam chamber 130 (e.g., a vacuum beam chamber), which may pass through the gap between the superconducting block 121a and the superconducting ring 121b in each superconducting unit, for example Figure 6 and Figure 7 In the embodiment, the beam chamber 130 passes through the mutually aligned portions of the gaps between the plurality of superconducting units, so that the electron beam traveling in the beam chamber 130 is affected by the periodic undulating magnetic field to generate free electron laser.

[0106] In some embodiments, Figure 6 and Figure 7 As shown, the outer contour shape of the superconducting block 121a can be consistent with the inner contour shape of the superconducting ring 121b, and the inner contour shape of the superconducting ring 121b can be consistent with the outer contour shape of the superconducting ring 121b, that is, the superconducting ring 121b conforms to the surrounding of the superconducting block 121a. In a specific example, the shape of the cross section of the superconducting block 121a perpendicular to the axial direction can be rectangular, circular or semicircular, and accordingly, the superconducting ring 121b can be a rectangular ring, a circular ring or a semicircular ring. However, it can be understood that in some other embodiments, the superconducting block can also have other shapes, which are not limited here.

[0107] In some embodiments, Fig. 9 As shown, the temperature control section 122 may include a heater 122a and a gas-liquid two-phase cooling pipe 122b, wherein the heater 122a may be attached to the superconducting material section 121 to heat the superconducting material section 121, and the gas-liquid two-phase cooling pipe 122b may be spirally wound around the superconducting material section 121, wherein helium may flow, and connected to, for example, a cooling pipeline of a cryogenic station or a cryogenic plant, so as to achieve cooling of the superconducting material section 121 through effects such as thermal siphon or forced flow cooling. Under the synergistic effect of the heating of the heater 122a and the cooling of the gas-liquid two-phase cooling pipe 122b, the temperature of the superconducting material section 121 may be continuously adjusted to or maintained at a desired temperature, so that the undulator generates light having a target fundamental wavelength.

[0108] In other embodiments, Fig.10 As shown, the temperature control portion 122 may include a heater 122a, a refrigerator 122c, a heat-conducting connecting wire 122d, and one or more flanges 122e, wherein the heater 122a may be attached to the superconducting material portion 121 to heat the superconducting material portion 121, and the refrigerator 122c may be thermally connected to the superconducting material portion 121 via the heat-conducting connecting wire 122d and one or more flanges 122e to cool the superconducting material portion 121. In a specific example, the heat-conducting connecting wire 122d may be made of copper, and the front, middle, and rear portions of the superconducting material portion 121 may be surrounded by a total of three flanges 122e, and connected to the corresponding heat-conducting connecting wires 122d, thereby improving the temperature uniformity of the superconducting material portion 121. Similarly, under the synergistic effect of the heating of the heater 122a and the cooling of the refrigerator 122c, the heat-conducting connecting wire 122d and the one or more flanges 122e, the temperature of the superconducting material portion 121 can be continuously adjusted to or maintained at a desired temperature, so that the undulator generates light with a target fundamental wavelength. Fig.10 The scheme shown can be based on, for example, only one GM refrigerator to control the temperature of the superconducting material part 121. It is simple to operate and has good safety. It does not require a large cryogenic station or cryogenic factory. Therefore, it is particularly convenient when making an undulator prototype and helps to reduce R&D costs.

[0109] The present disclosure also provides an optical system, which may include the undulator as described above. For example, the optical system may be a synchrotron radiation system, a free electron laser generation system, or a photolithography system. The generated EUV light with adjustable wavelength may be used in processes such as photolithography.

[0110] In the technical solution disclosed in the present invention, by configuring a background magnetic field with a first preset background field strength when the superconducting material portion is in a non-superconducting state, and then transforming the superconducting material portion to a superconducting state, the background field strength of the background magnetic field is reduced to a second preset background field strength, so that the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, and further by slowly increasing the temperature of the superconducting material portion to slowly reduce the magnetic field pinning force therein, thereby reducing the undulating field strength, thereby achieving real-time and continuous adjustment of the fundamental wavelength of the generated light, which helps to better meet the needs of scientific research and production. In addition, in the present disclosure, the background field strength can be reduced to a very small second preset background field strength, especially when the second preset background field strength is zero, the adverse effects of the remaining background magnetic field on the performance of the undulator can be avoided. Moreover, the undulator disclosed in the present invention adopts a block plus ring configuration, which can obtain a higher undulating magnetic field in an extremely short undulator period, with high magnetic field utilization efficiency, and the superconducting materials involved in the magnetic field generating components can adopt a passive quench protection scheme of diodes in parallel. In particular, the superconducting material part that generates the undulating magnetic field does not require an external power supply, and does not require a complex quench detection and protection system, which helps to reduce the manufacturing and operating costs of the undulator.

[0111] The words "left", "right", "front", "back", "top", "bottom", "up", "down", "high", "low", etc., in the specification and claims, if present, are used for descriptive purposes and are not necessarily used to describe an unchanging relative position. It should be understood that the words so used are interchangeable under appropriate circumstances, so that the embodiments of the present disclosure described herein, for example, can operate in other orientations than those shown or otherwise described herein. For example, when the device in the drawings is turned over, features previously described as "above" other features may now be described as "below" the other features. The device may also be oriented in other ways (rotated 90 degrees or in other orientations), and the relative spatial relationships will be interpreted accordingly.

[0112] In the specification and claims, when an element is referred to as being "on", "attached", "connected", "coupled", or "contacting" another element, the element may be directly on, directly attached, directly connected, directly coupled, or directly contacting another element, or one or more intermediate elements may be present. In contrast, when an element is referred to as being "directly" "on", "directly attached", "directly connected", "directly coupled", or "directly contacting" another element, there will be no intermediate elements. In the specification and claims, a feature being arranged "adjacent" to another feature may refer to a feature having a portion that overlaps with an adjacent feature or a portion that is located above or below an adjacent feature.

[0113] As used herein, the word "exemplary" means "serving as an example, instance, or illustration" rather than as a "model" to be exactly copied. Any implementation described as an example herein is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, the present disclosure is not to be limited by any expressed or implied theory given in the technical field, background, summary, or detailed description.

[0114] As used herein, the term "substantially" is intended to include any minor variations due to design or manufacturing imperfections, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for deviations from a perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may exist in actual implementations.

[0115] In addition, the terms "first", "second" and the like may also be used herein for reference purposes only and are not intended to be limiting. For example, the terms "first", "second" and other such numerical terms referring to structures or elements do not imply a sequence or order unless the context clearly indicates otherwise.

[0116] It should also be understood that when the term “include / comprises” is used in this document, it indicates the presence of the specified features, integers, steps, operations, units and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, units and / or components and / or their combinations.

[0117] In this disclosure, the term "provide" is used in a broad sense to cover all ways of obtaining an object, and thus "providing an object" includes but is not limited to "purchasing", "preparing / manufacturing", "arranging / setting up", "installing / assembling", and / or "ordering" an object, etc.

[0118] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0119] Those skilled in the art will appreciate that the boundaries between the above operations are merely illustrative. Multiple operations can be combined into a single operation, a single operation can be distributed in additional operations, and operations can be performed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a specific operation, and the order of operations may be changed in various other embodiments. However, other modifications, variations, and replacements are equally possible. Aspects and elements of all embodiments disclosed above may be combined in any manner and / or in combination with aspects or elements of other embodiments to provide multiple additional embodiments. Therefore, this specification and accompanying drawings should be considered illustrative, not restrictive.

[0120] Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. The various embodiments disclosed herein may be combined in any manner without departing from the spirit and scope of the present disclosure. It should also be understood by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. An undulator control method, characterized in that: The undulator includes a first magnetic field generating component for generating a background magnetic field and a second magnetic field generating component for generating an undulating magnetic field, wherein the second magnetic field generating component includes a superconducting material portion and a temperature control portion, and the undulator control method includes: The temperature control unit maintains the temperature of the superconducting material unit at a temperature greater than or equal to a first preset temperature so that the superconducting material unit is in a non-superconducting state, and the first magnetic field generating component generates a background magnetic field with a first preset background field strength; The background field strength of the background magnetic field is maintained at a first preset background field strength, and the temperature control unit reduces the temperature of the superconducting material portion from the first preset temperature to the second preset temperature, so that the superconducting material portion is transformed from a non-superconducting state to a superconducting state; The superconducting material portion is kept in a superconducting state, and the first magnetic field generating component reduces the background field strength from a first preset background field strength to a second preset background field strength, so that the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, wherein the second preset background field strength is zero or the second preset background field strength is less than or equal to a preset field strength threshold; and The background field intensity is maintained at a second preset background field intensity, and the temperature of the superconducting material portion is increased by the temperature control portion to reduce the undulating field intensity of the undulating magnetic field until the undulator generates light having a target fundamental wavelength.

2. The undulator control method according to claim 1, characterized in that: The target fundamental wave wavelength is in the range of 6.5 to 13.5 nm.

3. The undulator control method according to claim 1, characterized in that: Increasing the temperature of the superconducting material portion by the temperature control portion includes: The temperature of the superconducting material portion is increased by the temperature control portion at a first preset rate to avoid quenching of the superconducting material portion.

4. The undulator control method according to claim 1, characterized in that: Generating a background magnetic field having a first preset background field strength by the first magnetic field generating component includes increasing the background field strength from zero to the first preset background field strength at a constant second preset rate by the first magnetic field generating component; and / or Reducing the background field strength from the first preset background field strength to the second preset background field strength by the first magnetic field generating component includes reducing the background field strength from the first preset background field strength to the second preset background field strength by the first magnetic field generating component at a constant third preset rate.

5. The undulator control method according to claim 1, characterized in that: After the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, the undulator control method further includes: The temperature control unit lowers the temperature of the superconducting material unit to a third preset temperature to freeze the magnetic flux of the superconducting material unit.

6. The undulator control method according to claim 5, characterized in that: The first preset temperature is in the range of 80-100K or 100-120K; The second preset temperature is in the range of 5-10K or 10-15K; and / or The third preset temperature is in the range of 3-7K or 7-11K.

7. The undulator control method according to claim 1, characterized in that: After the superconducting material portion generates an undulating magnetic field with a preset undulating field strength, the undulator control method further includes: measuring a phase error of the undulating magnetic field; comparing the measured phase error with a preset phase threshold; and When the measured phase error is greater than or equal to a preset phase threshold, magnetic field shimming is performed on the superconducting material portion.

8. An undulator control device, characterized in that: The undulator control device comprises a memory and a processor, wherein instructions are stored in the memory, and when the instructions are executed by the processor, the steps of the undulator control method according to any one of claims 1 to 7 are implemented.

9. An undulator, characterized in that: The undulator is configured to generate light having an adjustable target fundamental wavelength, and the undulator comprises: A first magnetic field generating component, the first magnetic field generating component is configured to generate a background magnetic field; and A second magnetic field generating component, wherein the second magnetic field generating component is configured to generate a undulating magnetic field, and the second magnetic field generating component includes a superconducting material portion and a temperature control portion, wherein the superconducting material portion is positioned to generate the undulating magnetic field under the action of the background magnetic field, and the temperature control portion is configured to continuously adjust and maintain the temperature of the superconducting material portion.

10. The undulator according to claim 9, characterized in that The undulator further comprises an undulator control device according to claim 8 .

11. The undulator according to claim 9, characterized in that The first magnetic field generating component is disposed in a first vacuum chamber, the second magnetic field generating component is disposed in a second vacuum chamber, and the first vacuum chamber and the second vacuum chamber are isolated from each other.

12. The undulator according to claim 9, characterized in that The superconducting material portion is configured so that an undulator period of the undulator is less than or equal to 10 mm.

13. The undulator according to claim 9, characterized in that The superconducting material portion is formed of a high temperature superconducting bulk material.

14. The undulator according to claim 9, characterized in that The superconducting material portion includes a plurality of superconducting units arranged at intervals along the axial direction of the undulator, wherein each superconducting unit includes a superconducting block and a superconducting ring arranged around the superconducting block, and any two adjacent superconducting units are staggered in a vertical direction perpendicular to the axial direction to generate a periodic undulating magnetic field.

15. The undulator according to claim 14, characterized in that The undulator further comprises: A beam chamber is provided through a gap between the superconducting block and the superconducting ring in each superconducting unit.

16. The undulator according to claim 14, characterized in that The outer contour of the superconducting block is consistent with the inner contour of the superconducting ring; and The inner contour shape of the superconducting ring is consistent with the outer contour shape of the superconducting ring.

17. The undulator according to claim 14, characterized in that A cross section of the superconducting block perpendicular to the axial direction may be rectangular, circular or semicircular.

18. The undulator according to claim 9, characterized in that The temperature control unit comprises: a heater attached to the superconducting material portion; and A gas-liquid two-phase cooling pipe is spirally wound around the superconducting material portion.

19. The undulator according to claim 9, characterized in that The temperature control unit comprises: a heater attached to the superconducting material portion; Refrigeration machine; Thermally conductive connecting wires; and One or more flanges, wherein the refrigerator is thermally connected to the superconducting material portion via the thermally conductive connection line and the one or more flanges.

20. An optical system, characterized in that: The optical system comprises an undulator according to any one of claims 9 to 19, and the optical system is a synchrotron radiation system, a free electron laser generation system or a photolithography system.

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