Unstable control methods and devices, undulators and optical systems

Abstract

This disclosure relates to an undulator control method and apparatus, an undulator, and an optical system. The undulator control method includes: maintaining the temperature of a superconducting material section at a temperature greater than or equal to a first preset temperature by a temperature control unit, and generating a background magnetic field with a first preset background field strength by a first magnetic field generating component; 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 section from the first preset temperature to a second preset temperature by the temperature control unit; maintaining the superconducting material section in a superconducting state, and 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, so that the superconducting material section generates an undulating magnetic field with a preset undulation field strength; and maintaining the background field strength at the second preset background field strength, and increasing the temperature of the superconducting material section by the temperature control unit to reduce the undulation field strength of the undulation magnetic field until the undulator generates light with a target fundamental wavelength.

Description

Technical Field

[0001] This disclosure relates to the field of electromagnetic technology, and more specifically, to an undulator control method and apparatus, an undulator, and an optical system. Background Technology

[0002] A undulator is a device that provides a periodic magnetic field, which can be used to generate high-intensity free-electron lasers, among other things. Currently, undulators can be formed based on permanent magnets (e.g., neodymium iron boron (NdFeB) or samarium cobalt (SmCo)) or superconducting magnets. While the technology of permanent magnet undulators is relatively mature, the period of such undulators is limited by the residual magnetic field of the permanent magnet, making it difficult to further shorten. Compared to permanent magnet blocks, superconducting bulk materials can trap a larger magnetic field, and correspondingly, the performance of superconducting undulators can be significantly improved. Currently, several undulator structures based on superconducting bulk materials exist, including: (1) magnetizing two rows of axially arranged superconducting bulk materials with a uniform magnetic field (e.g., a dipole field provided by a rectangular coil) in the vertical direction perpendicular to the undulator's axial direction to generate an axially distributed planar undulating magnetic field; (2) magnetizing staggered superconducting bulk materials with a uniform magnetic field (e.g., a background field provided by a solenoid coil) in the axial direction to generate an axially distributed planar undulating magnetic field; and (3) magnetizing rotated staggered superconducting bulk materials with a uniform magnetic field in the axial direction to generate an axially distributed helical 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] This disclosure aims to provide a undulator control method and apparatus, a undulator, and an optical system, which change the magnetic flux pinning force in the superconducting material section of the undulator by adjusting the temperature, thereby changing the undulation magnetic field of the undulator to obtain light with a desired fundamental wavelength.

[0004] According to a first aspect of this disclosure, a method for controlling an undulator is provided. 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. The second magnetic field generating component includes a superconducting material section and a temperature control section. The undulator control method includes:

[0005] The temperature control unit maintains the temperature of the superconducting material part at a temperature greater than or equal to a first preset temperature, so that the superconducting material part 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 kept constant at the first preset background field strength, and the temperature control unit lowers the temperature of the superconducting material part from the first preset temperature to the second preset temperature, so that the superconducting material part changes from a non-superconducting state to a superconducting state.

[0007] While maintaining the superconducting material in a superconducting state, 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, thereby causing the superconducting material to generate an oscillating magnetic field with a preset oscillation field strength, wherein the second preset background field strength is zero or less than or equal to a preset field strength threshold; and

[0008] The background field strength is kept constant at the second preset background field strength, and the temperature of the superconducting material is increased by the temperature control unit to reduce the oscillation field strength of the oscillation magnetic field until the oscillator generates light with the 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, raising the temperature of the superconducting material section by the temperature control unit includes:

[0011] The temperature control unit raises the temperature of the superconducting material section at a first preset rate to prevent the superconducting material section from losing its superconductivity.

[0012] In some embodiments, generating a background magnetic field with 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 by the first magnetic field generating component at a constant second preset rate; and / or

[0013] Reducing the background field strength from a first preset background field strength to a 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 generates a 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 section to a third preset temperature to freeze the magnetic flux of the superconducting material section.

[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 generates a undulating magnetic field with a preset undulating field strength, the undulator control method further includes:

[0020] Measure the phase error of the undulating magnetic field;

[0021] Compare 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, the superconducting material is padded with a magnetic field.

[0023] According to a second aspect of this disclosure, an oscillator control device is provided, the oscillator control device including a memory and a processor, the memory storing instructions that, when executed by the processor, implement the steps of the oscillator control method as described above.

[0024] According to a third aspect of this 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, configured to generate a background magnetic field; and

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

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

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

[0029] In some embodiments, the superconducting material portion is configured such that the 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 spaced apart along the axial direction of the undulator, wherein each superconducting unit includes a superconducting block and a superconducting ring disposed 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 includes:

[0033] A beam chamber that passes through the gap between the superconducting block and the superconducting ring in each superconducting unit.

[0034] In some embodiments, the outer contour shape of the superconducting block corresponds to the inner contour shape of the superconducting ring; and

[0035] The internal contour shape of the superconducting ring is consistent with the external contour shape of the superconducting ring.

[0036] In some embodiments, the superconducting block has a rectangular, circular, or semi-circular cross-section in the direction perpendicular to the axial direction.

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

[0038] Heater, the heater being attached to the superconducting material portion; and

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

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

[0041] A heater, the heater being attached to the superconducting material portion;

[0042] Refrigeration unit;

[0043] Thermally conductive connecting wires; and

[0044] One or more flanges, wherein the refrigeration unit is thermally connected to the superconducting material section via the thermally conductive connecting line and the one or more flanges.

[0045] According to a fourth aspect of this disclosure, an optical system is provided, the optical system including the undulator as described above, and the optical system is a synchrotron radiation system, a free-electron laser generating system, or a lithography system.

[0046] Other features and advantages of this disclosure will become clearer from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0047] The accompanying drawings, which form part of this specification, illustrate embodiments of this disclosure and, together with the specification, serve to explain the principles of this disclosure.

[0048] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein:

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

[0050] Figure 2 A flowchart illustrating an exemplary embodiment of an oscillator control method according to the present disclosure is shown.

[0051] Figure 3 A flowchart illustrating an oscillator control method according to another exemplary embodiment of the present disclosure is shown;

[0052] Figure 4 A partial flowchart of an oscillator control method according to yet another exemplary embodiment of the present disclosure is shown;

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

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

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

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

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

[0058] Figure 10 A schematic diagram of the structure of the 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 across different figures to denote the same parts or parts having the same function, and repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to denote similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0060] For ease of understanding, the positions, dimensions, and extents of the structures shown in the accompanying drawings and other materials may not represent actual positions, dimensions, and extents. Therefore, the disclosed invention is not limited to the positions, dimensions, and extents disclosed in the accompanying drawings and other materials. Furthermore, the drawings are not necessarily drawn to scale, and some features may be enlarged to show details of specific components. Detailed Implementation

[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, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.

[0062] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. Those skilled in the art will understand that they merely illustrate exemplary ways that can be used to implement this disclosure, and are not exhaustive.

[0063] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0064] In a superconducting bulk undulator, the superconducting bulk material can be magnetized using a background magnetic field to generate a periodic undulating magnetic field. Furthermore, when a high-energy electron beam passes through this undulating magnetic field, it can generate radiated light. The fundamental wavelength of the light is related to parameters such as the electron beam energy, the undulator period, and the strength of the undulating magnetic field. In an exemplary embodiment of this disclosure, a scheme is proposed to adjust the fundamental wavelength of the light generated by the undulator, thereby improving the controllability and flexibility of the undulator and enabling it to better meet the needs of scientific research or production.

[0065] In one exemplary embodiment of this disclosure, such as 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 of a superconducting solenoid magnet or other type of magnetic field generating component 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 can generate an axial (e.g., Figure 6 The background magnetic field (shown as z-axis) induces the superconducting material section 121 in the second magnetic field generating component 120 to generate an axially undulating magnetic field. Furthermore, the temperature control unit 122 in the second magnetic field generating component 120 can be used to adjust the temperature of the superconducting material section 121 to a desired state or to adjust the undulation field strength of the generated undulating magnetic field. Based on the above undulator, as... Figure 2 As shown, in an exemplary embodiment of this disclosure, the oscillator control method may include:

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

[0067] Specifically, the first preset temperature can be determined based on the critical temperature of the superconducting material section 121. This first preset temperature should be greater than the critical temperature of the superconducting material section 121 to keep the superconducting material section 121 in a non-superconducting state. In some embodiments, the superconducting material section 121 can be a bulk material formed of a high-temperature superconducting material (typically referring to a superconducting material with a critical temperature above 30K). Such a high-temperature superconducting bulk material can generate a strong oscillating magnetic field, thereby helping to reduce the oscillator period while generating light of the same fundamental wavelength, thus reducing the overall size of the oscillator and lowering the manufacturing and operating costs of the oscillator. For example, depending on the type of high-temperature superconducting material used, the first preset temperature can be in the range of 80–100K or 100–120K. In a specific example, the temperature of the superconducting material section 121 can be maintained at or above 100K by the temperature control unit 122 to keep the superconducting material section 121 in a non-superconducting state.

[0068] When the superconducting material section 121 is in a non-superconducting state, the first magnetic field generating component 110 can generate a background magnetic field with 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. Increasing the field strength at a constant rate helps simplify the control of the first magnetic field generating component 110. However, it is 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 varying rate, which is not limited here. In some embodiments, the first preset background field strength can be calculated or determined according to the target fundamental wavelength of the light to be generated. Furthermore, since this 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 oscillation field strength used to generate the light of the target fundamental wavelength, as will be described in detail below.

[0069] return Figure 2 The oscillator control method may also include:

[0070] In step S920, the background field strength of the background magnetic field is kept constant at the first preset background field strength, and the temperature control unit 122 lowers the temperature of the superconducting material unit 121 from the first preset temperature to the second preset temperature, so that the superconducting material unit 121 changes from a non-superconducting state to a superconducting state.

[0071] With the superconducting material section 121 in a superconducting state, magnetization of the superconducting material section 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 section 121. Furthermore, in some embodiments, in order to ensure that the superconducting material section 121 can be stably in a superconducting state, and for considerations such as reducing magnetic flux changes in the superconducting material section 121, the second preset temperature can be much smaller than the critical temperature of the superconducting material. For example, when the superconducting material section 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 5-10K or 10-15K. In a specific example, the temperature control unit 122 can reduce the temperature of the superconducting material section 121 from 100K to 10K, so that the superconducting material section 121 changes from a non-superconducting state to a superconducting state, and so that the superconducting material section 121 can be stably maintained in the superconducting state, avoiding loss of superconductivity caused by external interference.

[0072] return Figure 2 The oscillator control method may also include:

[0073] In step S930, the superconducting material section 121 is kept in a superconducting state, and the background field strength is reduced from the first preset background field strength to the second preset background field strength by the first magnetic field generating component 110, so that the superconducting material section 121 generates a wavy magnetic field with a preset wavy field strength.

[0074] The second preset background field strength can be zero, or it can be a very small field strength, such as less than or equal to a 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 section 121 can be magnetized to induce a permanent magnetizing current, thereby generating a undulating magnetic field with a preset undulating field strength. It should be noted that in the undulator, the undulating magnetic field is a periodic magnetic field formed by the superconducting material section 121 with a periodic structure. For example, it can be a undulating magnetic field with the field strength varying in a sinusoidal or cosine form along the axial direction. Accordingly, the undulating field strength mentioned herein refers to the maximum magnetic field strength or magnetic field strength amplitude in the periodic undulating magnetic field.

[0075] Furthermore, it is understood that the preset undulation field strength is related to the first preset background field strength and the relative positional relationship between the superconducting material part 121 and the first magnetic field generating part 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 this disclosure, since the background field strength can be reduced to a 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 performance of the electron beam bundle can be well avoided, thereby improving the quality of the light generated by the undulator.

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

[0078] return Figure 2 The oscillator control method may also include:

[0079] In step S940, the background field strength is kept constant at the second preset background field strength, and the temperature of the superconducting material section 121 is increased by the temperature control section 122 to reduce the oscillation field strength of the oscillation magnetic field until the oscillator 100 generates light with the 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 Let γ be the undulator period, γ be the Lorentz factor which can be used to characterize the energy of the electron, e be the electron charge, B0 be the undulator field strength, m be the electron mass, and c be the speed of light in vacuum.

[0081] According to the aforementioned undulator equation, the fundamental wavelength of the generated light is related to the undulator period, the electron beam energy, and the undulation field strength of the undulation magnetic field. Furthermore, during the operation of the undulator, the energy of the input electron beam and the undulator structural parameters (e.g., the undulator period) are generally fixed and difficult to change. Therefore, if it is desired to continuously adjust the fundamental wavelength of the generated free electron laser in real time during the operation of the undulator, this can be achieved by changing the undulation field strength of the undulation magnetic field. Specifically, the temperature control unit 122 can increase the temperature of the superconducting material section 121, causing the magnetic flux pinning force in the superconducting material section 121 to decrease with increasing temperature, thereby reducing the undulation field strength of the undulation magnetic field, or in other words, reducing the undulator deflection coefficient K', and thus 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 unit 121 can stop further heating to continuously generate a free electron laser with the target fundamental wavelength.

[0082] In some embodiments, the undulator period can be set to less than or equal to 10 mm, and correspondingly, the deflection coefficient K' can range from 1 to 2. An excessively large K' value corresponds to an excessively large deflection angle, affecting the coherence characteristics of the free-electron laser, while an excessively small K' value leads to an increase in the length and cost of the undulator system.

[0083] In some embodiments, the temperature control unit 122 can raise the temperature of the superconducting material unit 121 sufficiently slowly, for example, by raising the temperature of the superconducting material unit 121 at a first preset rate, thereby preventing the superconducting material unit 121 from losing its superconductivity.

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

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

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

[0087] Specifically, magnetic flux creep exists in superconducting materials, where thermal activation energy causes magnetic flux lines to detach from their original pinning centers and jump to another, resulting in a slow flow of the flux lines. To suppress or eliminate magnetic flux creep, the temperature control unit 122 can further reduce the temperature of the superconducting material section 121 to a third preset temperature to freeze the magnetic flux. For example, the third preset temperature can be in the range of 3–7 K or 7–11 K. In a specific example, the temperature control unit 122 can further reduce the temperature of the superconducting material section 121 from 10 K to 7 K to freeze the magnetic flux. Furthermore, in some embodiments, such as Figure 3 As shown, step S940 can be performed after step S950. That is, the temperature of the superconducting material section 121 can 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 section 121, thereby reducing the fundamental wavelength of the generated free electron laser. Alternatively, in some embodiments, step S940 can also be performed before step S950. That is, the magnetic flux can be frozen by cooling after the light with the target fundamental wavelength is generated.

[0088] In yet another exemplary embodiment of this disclosure, before the undulator officially operates, it can be subjected to debugging operations such as magnetic field padding to improve the performance of the undulator. Specifically, during the debugging process of the undulator, the superconducting material section 121 can be made to generate a undulating magnetic field according to steps S910 to S930, or according to steps S910 to S950. After the superconducting material section 121 generates a undulating magnetic field with a preset undulating field strength, as Figure 4 As shown, the oscillator control method may also include:

[0089] Step S961: Measure the phase error of the oscillating magnetic field;

[0090] Step S962: Compare the measured phase error with a preset phase threshold; and

[0091] Step S963: When the measured phase error is greater than or equal to the preset phase threshold, magnetic field padding is applied to the superconducting material section 121.

[0092] In other words, steps S961 to S963 can be performed during the debugging of the undulator. By comparing the phase error of the measured undulating magnetic field with a preset phase threshold after the undulator generates a undulating magnetic field, magnetic field compensation can be performed on the superconducting material section 121. For example, magnetic field compensation can be achieved by changing the structural parameters of the superconducting material section 121 (e.g., adjusting the magnetic pole height, replacing the bulk material, etc.), thereby enabling the superconducting material section 121 to generate a more ideal undulating magnetic field and improving the performance of the undulator. It is understood that once the debugging of the undulator is completed and the undulator enters normal working condition, steps S961 to S963 can be discontinued unless the undulating magnetic field changes significantly.

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

[0094] The processor 520 can execute various actions and processes according to instructions stored in the memory 510. Specifically, the processor 520 can be an integrated circuit chip with signal processing capabilities. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this disclosure. The general-purpose processor can be a microprocessor or any conventional processor, and can be an x86 architecture or an ARM architecture, etc.

[0095] Memory 510 stores executable instructions that are executed by processor 520 using the oscillator control method described above. Memory 510 may be volatile memory or non-volatile memory, or may include both. Non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM) 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 linked dynamic random access memory (SLDRAM), and direct memory bus random access memory (DR RAM). It should be noted that the memory used in the methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0096] This disclosure also provides a non-transitory computer-readable storage medium storing instructions that, when executed by a processor, can implement the steps of the oscillator control method described above.

[0097] Similarly, the computer-readable storage medium in the embodiments of this disclosure may be volatile memory or 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] This disclosure also provides a computer program product including instructions that, when executed by a processor, can implement the steps of the oscillator control method as described above.

[0099] Instructions can be any set of instructions that will be executed directly by one or more processors, such as machine code, or any set of instructions that will be executed indirectly, such as a script. The terms “instruction,” “application,” “process,” “step,” and “program” used herein are interchangeable. Instructions can be stored in object code format for direct processing by one or more processors, or stored in any other computer language, including scripts or sets of independent source code modules that are interpreted on demand or compiled ahead of time. Instructions can include instructions that cause one or more processors to act as the various neural networks described herein. The function, methods, and routines of instructions are explained in more detail in other parts of this document.

[0100] This disclosure also provides an undulator that can be configured to generate light having an adjustable target fundamental wavelength. In some embodiments, the undulator can be controlled using the undulator control method and / or undulator control device described above. Figure 1 As shown, in an exemplary embodiment of this disclosure, the undulator 100 may include a first magnetic field generating component 110 and a second magnetic field generating component 120. 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 further include the undulator control device as described above to adjust the fundamental wavelength of the light it generates. However, it is understood that in some other embodiments, the undulator control device may be provided independently of the undulator.

[0101] In some embodiments, the first magnetic field generating component 110 may be formed of a superconducting solenoid magnet, which can provide, for example, a magnetic field exceeding 10 T. In some embodiments, such as Figure 1 As shown, the first magnetic field generating component 110 or superconducting solenoid magnet may include a GM refrigerator 111, a cooling 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 from, for example, Nb-Ti or Nb3Sn round wire.

[0102] Furthermore, in some embodiments, such as Figure 1 As shown, the second magnetic field generating component 120 may include a superconducting material section 121 and a temperature control section 122. The superconducting material section 121 can be positioned to generate an oscillating magnetic field under the influence of a background magnetic field. For example, it can be arranged adjacent to the first magnetic field generating component 110, and typically, the generated oscillating magnetic field increases with the increase of the background magnetic field. The temperature control section 122 can be configured to continuously adjust and maintain the temperature of the superconducting material section 121. For example, it can achieve temperature control in the range of 100K to 7K, and the controlled axial temperature difference can be less than 0.1K, and the temperature control accuracy can be better than 0.1K. Thus, radiation light with a target fundamental wavelength can be generated based on the oscillator control method described above.

[0103] In some embodiments, such as Figure 1As shown, the undulator may include a first vacuum chamber and a second vacuum chamber isolated from each other. A first magnetic field generating component 110 may be disposed in the first vacuum chamber, and a 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 level associated with each magnetic field generating component. However, it is understood 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 padding, because a larger vacuum chamber often requires more time to achieve the vacuum level transition.

[0104] In some embodiments, the superconducting material section can 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 trap a strong magnetic field, thereby forming a strong undulation magnetic field. This can effectively reduce the required undulator period while generating light of the same fundamental wavelength, thus reducing the overall size of the undulator. In some embodiments, by employing a superconducting material section 121 with suitable materials and structure, the undulator period can be less than or equal to 10 mm. Furthermore, reducing the undulator period can help to significantly reduce the energy of the required electron beam, thereby reducing the length of the linear accelerator used to accelerate the electron beam, and thus reducing costs.

[0105] In some embodiments, such as Figure 6 and Figure 7 As shown, the superconducting material section 121 may include components along the axial direction of the undulator (i.e., Figure 6 Multiple superconducting units are arranged at intervals in the z-direction (as shown in the image). Each superconducting unit may include a superconducting block 121a and a superconducting ring 121b surrounding the superconducting block 121a. Any two adjacent superconducting units are spaced at intervals in the vertical direction perpendicular to the axial direction (i.e., ...). Figure 6 The magnetizing currents in the superconducting unit are staggered along the y-direction to generate a periodic oscillating magnetic field. For example, the magnetizing current distribution generated in the superconducting unit is as follows: Figure 8 As shown, "-" indicates that the current direction is perpendicular to the paper and outwards (i.e., along the direction of the paper). Figure 6 (in the positive x direction), "+" indicates that the current direction is perpendicular to the paper and inwards (i.e., along the positive x direction). Figure 6(in the negative x direction). 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 outwards, while the magnetizing current direction of the lower part of the superconducting ring 121b is perpendicular to the paper and inwards. The magnetizing current direction of the upper part of the superconducting block 121a is perpendicular to the paper and outwards, while the magnetizing current direction of the lower part of the superconducting block 121a is perpendicular to the paper and inwards. 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 inwards, while the magnetizing current direction of the lower part of the superconducting ring 121b is perpendicular to the paper and inwards. The magnetizing current direction of the upper part of the superconducting block 121a is perpendicular to the paper and outwards, while the magnetizing current direction of the lower part of the superconducting block 121a is perpendicular to the paper and inwards. Along the z-axis direction, the current directions at the same vertical position (same y-coordinate) alternately reverse, thus forming a periodic oscillating magnetic field. Among them, two adjacent superconducting units can form one cycle of the oscillator, and its size in the z-axis direction corresponds to the oscillator period. Figure 8 In the specific example shown, a total of five oscillator cycles are included. Forming the superconducting unit by setting up electrically isolated superconducting blocks 121a and superconducting rings 121b helps improve magnetic field utilization efficiency to generate a sufficiently strong oscillating magnetic field. 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 in the axial direction with the upper gap between the superconducting block 121a and the superconducting ring 121b in the other superconducting unit, thereby achieving a staggered arrangement of multiple superconducting units. Furthermore, the undulator may also include a beam chamber 130 (e.g., a vacuum beam chamber) that can pass through the gap between the superconducting block 121a and the superconducting ring 121b in each superconducting unit, for example in… Figure 6 and Figure 7 In the beam chamber 130, the beam passes through the gaps between multiple superconducting units and the portion of the beam chamber 130 that is aligned with each other, so that the electron beam traveling in the beam chamber 130 is subjected to a periodic oscillating magnetic field and generates a free electron laser.

[0106] In some embodiments, such as Figure 6 and Figure 7 As shown, the outer contour shape of the superconducting block 121a can conform to the inner contour shape of the superconducting ring 121b, and the inner contour shape of the superconducting ring 121b can conform to the outer contour shape of the superconducting ring 121b, that is, the superconducting ring 121b conformally surrounds the superconducting block 121a. In a specific example, the shape of the cross-section of the superconducting block 121a in the direction perpendicular to the axial direction can be rectangular, circular, or semi-circular, and correspondingly, the superconducting ring 121b can be a rectangular ring, a circular ring, or a semi-circular ring. However, it is understood that in some other embodiments, the superconducting block may also have other shapes, which are not limited here.

[0107] In some embodiments, such as Figure 9 As shown, the temperature control unit 122 may include a heater 122a and a gas-liquid two-phase cooling pipe 122b. The heater 122a may be attached to the superconducting material section 121 to heat the superconducting material section 121. The gas-liquid two-phase cooling pipe 122b may be spirally wound around the superconducting material section 121, through which helium may flow, and is connected to a cooling pipeline, such as that of a cryogenic station or cryogenic plant, to cool the superconducting material section 121 through effects such as thermosiphon or forced flow cooling. Under the synergistic effect of the heating by the heater 122a and the cooling by the gas-liquid two-phase cooling pipe 122b, the temperature of the superconducting material section 121 can be continuously adjusted to or maintained at the desired temperature, thereby enabling the undulator to generate light with the target fundamental wavelength.

[0108] In other embodiments, such as Figure 10 As shown, the temperature control unit 122 may include a heater 122a, a refrigerator 122c, a heat-conducting connecting wire 122d, and one or more flanges 122e. The heater 122a may be attached to the superconducting material section 121 to heat it, and the refrigerator 122c may be thermally connected to the superconducting material section 121 via the heat-conducting connecting wire 122d and one or more flanges 122e to cool it. 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 section 121 may be surrounded by three flanges 122e, which are connected to the corresponding heat-conducting connecting wires 122d, thereby improving the temperature uniformity of the superconducting material section 121. Similarly, through the combined action of heating in heater 122a and cooling in cooler 122c, thermally conductive connecting wire 122d, and cooling in one or more flanges 122e, the temperature of the superconducting material section 121 can be continuously adjusted to or maintained at the desired temperature, thereby enabling the undulator to generate light with the target fundamental wavelength. Figure 10 The proposed solution can control the temperature of the superconducting material section 121 using, for example, a single GM cryostat. It is simple to operate, safe, and does not require a large cryogenic station or cryogenic factory. Therefore, it is particularly convenient when making undulator prototypes, which helps to reduce R&D costs.

[0109] This disclosure also provides an optical system that may include the undulator described above. For example, the optical system may be a synchrotron radiation system, a free-electron laser generation system, or a lithography system. The generated wavelength-tunable EUV light can be used for processes such as lithography.

[0110] In the technical solution of this disclosure, by configuring a background magnetic field with a first preset background field strength when the superconducting material part is in a non-superconducting state, and then converting the superconducting material part 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 part generates an oscillating magnetic field with a preset oscillation field strength. Furthermore, by slowly increasing the temperature of the superconducting material part, the magnetic field pinning force is gradually reduced, thereby reducing the oscillation field strength. This achieves 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 this 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, which can avoid the adverse effects of the remaining background magnetic field on the oscillator performance. Moreover, the undulator disclosed herein adopts a block plus ring configuration, which can obtain a high undulating magnetic field with an extremely short undulator period. It has high magnetic field utilization efficiency, and the superconducting materials involved in the magnetic field generating component can all adopt a passive quench protection scheme with diodes in parallel. In particular, the superconducting material part that generates the undulating magnetic field does not require 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 terms “left,” “right,” “front,” “back,” “top,” “bottom,” “upper,” “lower,” “high,” “lower,” etc., used in the specification and claims, if present, are for descriptive purposes and not necessarily for describing unchanging relative positions. It should be understood that such terms are interchangeable where appropriate, enabling embodiments of this disclosure described herein to operate, for example, in orientations different from those shown or otherwise described herein. For example, when the device in the drawings is reversed, a feature previously described as “above” other features may now be described as “below” other features. The device may also be oriented in other ways (rotated 90 degrees or in other orientations), in which case the relative spatial relationships will be interpreted accordingly.

[0112] In the specification and claims, when an element is described as being "on top of," "attached to," "connected to," "coupled to," or "in contact with" another element, the element may be directly located on top of, directly attached to, directly connected to, directly coupled to, or directly in contact with the other element, or one or more intermediate elements may be present. Conversely, when an element is described as being "directly" located on top of, directly attached to, directly connected to, directly coupled to, or directly in contact with another element, no intermediate elements are present. In the specification and claims, when a feature is arranged "adjacent" to another feature, it may mean that a feature has a portion overlapping with the adjacent feature or a portion located above or below the adjacent feature.

[0113] As used herein, the term “exemplary” means “serving as an example, instance, or illustration” and not as a “model” to be precisely copied. Any implementation described herein by example is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, this disclosure is not limited to any theory expressed or implied as given in the field of art, background art, summary of invention, or detailed description.

[0114] As used herein, the term "substantially" means any minor variation resulting from design or manufacturing defects, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for differences from the perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may exist in the actual implementation.

[0115] Furthermore, terms such as “first,” “second,” etc., may be used in this document for reference purposes only and are not intended to be limiting. For example, unless the context clearly indicates otherwise, the words “first,” “second,” and other such numerical terms relating to structures or elements do not imply order or sequence.

[0116] It should also be understood that when the term “including / contains” is used herein, it indicates the presence of the indicated feature, whole, step, operation, unit and / or component, but does not preclude the presence or addition of one or more other features, wholes, steps, operations, units and / or components and / or combinations thereof.

[0117] In this disclosure, the term “provide” is used broadly to cover all ways of obtaining an object, and therefore “provide an object” includes, but is not limited to, “purchasing,” “preparing / manufacturing,” “arranging / setting up,” “installing / assembling,” and / or “ordering” an object.

[0118] As used herein, the term “and / or” includes any and all combinations of one or more of the listed items in association. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this 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 recognize that the boundaries between the above operations are merely illustrative. Multiple operations may be combined into a single operation, a single operation may be distributed among additional operations, and operations may be performed with at least partial overlap in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be changed in various other embodiments. However, other modifications, variations, and substitutions are equally possible. Aspects and elements of all the embodiments disclosed above may be combined in any way and / or in combination with aspects or elements of other embodiments to provide multiple additional embodiments. Therefore, this specification and the accompanying drawings should be considered illustrative rather than restrictive.

[0120] While specific embodiments of this disclosure have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. The various embodiments disclosed herein can be combined in any way without departing from the spirit and scope of this disclosure. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. A method for controlling an oscillator, 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. The second magnetic field generating component includes a superconducting material section and a temperature control section. The undulator control method includes: The temperature control unit maintains the temperature of the superconducting material part at a temperature greater than or equal to a first preset temperature, so that the superconducting material part 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 kept constant at the first preset background field strength, and the temperature control unit lowers the temperature of the superconducting material part from the first preset temperature to the second preset temperature, so that the superconducting material part changes from a non-superconducting state to a superconducting state. While maintaining the superconducting material in a superconducting state, 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, thereby causing the superconducting material to generate an oscillating magnetic field with a preset oscillation field strength, wherein the second preset background field strength is zero or less than or equal to a preset field strength threshold; and The background field strength is kept constant at the second preset background field strength, and the temperature of the superconducting material is increased by the temperature control unit to reduce the oscillation field strength of the oscillation magnetic field until the oscillator generates light with the target fundamental wavelength.

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

3. The oscillator control method according to claim 1, characterized in that, The temperature increase of the superconducting material section by the temperature control unit includes: The temperature control unit raises the temperature of the superconducting material section at a first preset rate to prevent the superconducting material section from losing its superconductivity.

4. The oscillator control method according to claim 1, characterized in that, The generation of a background magnetic field with 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 by the first magnetic field generating component at a constant second preset rate. and / or Reducing the background field strength from a first preset background field strength to a 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 oscillator control method according to claim 1, characterized in that, After the superconducting material generates a 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 section to a third preset temperature to freeze the magnetic flux of the superconducting material section.

6. The oscillator 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 oscillator control method according to claim 1, characterized in that, After the superconducting material generates a undulating magnetic field with a preset undulating field strength, the undulator control method further includes: Measure the phase error of the undulating magnetic field; Compare 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, the superconducting material is padded with a magnetic field.

8. A oscillator control device, characterized in that, The undulator control device includes a memory and a processor. The memory stores instructions that, when executed by the processor, implement the steps of the undulator control method according to any one of claims 1 to 7.

9. An oscillator, characterized in that, The undulator is configured to generate light having an adjustable target fundamental wavelength, and the undulator includes: A first magnetic field generating component, configured to generate a background magnetic field; and A second magnetic field generating component is configured to generate an oscillating magnetic field, and the second magnetic field generating component includes a superconducting material part and a temperature control part; The temperature control unit is configured to maintain the temperature of the superconducting material portion at a temperature greater than or equal to a first preset temperature, so that the superconducting material portion is in a non-superconducting state, and the first magnetic field generating component is configured to generate a background magnetic field with a first preset background field strength. While keeping the background magnetic field strength constant at a first preset background field strength, the temperature control unit is configured to reduce the temperature of the superconducting material section from a first preset temperature to a second preset temperature, so that the superconducting material section transitions from a non-superconducting state to a superconducting state. While maintaining the superconducting material portion in a superconducting state, the first magnetic field generating component is configured to reduce 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 oscillating magnetic field with a preset oscillation field strength, wherein the second preset background field strength is zero or less than or equal to a preset field strength threshold, and While keeping the background field strength unchanged at the second preset background field strength, the temperature control unit is configured to increase the temperature of the superconducting material unit to reduce the undulation field strength of the undulation magnetic field until the undulator generates light with the target fundamental wavelength.

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

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

12. The undulator according to claim 9, characterized in that, The superconducting material section is formed from high-temperature superconducting bulk material.

13. The undulator according to claim 9, characterized in that, The superconducting material section includes a plurality of superconducting units spaced apart along the axial direction of the undulator. Each superconducting unit includes a superconducting block and a superconducting ring surrounding the superconducting block. Any two adjacent superconducting units are staggered in a vertical direction perpendicular to the axial direction to generate a periodic undulating magnetic field.

14. The undulator according to claim 13, characterized in that, The undulator also includes: A beam chamber that passes through the gap between the superconducting block and the superconducting ring in each superconducting unit.

15. The undulator according to claim 13, characterized in that, The outer contour shape of the superconducting block is consistent with the inner contour shape of the superconducting ring; and The internal contour shape of the superconducting ring is consistent with the external contour shape of the superconducting ring.

16. The undulator according to claim 13, characterized in that, The superconducting block has a rectangular, circular, or semi-circular cross-section in the direction perpendicular to the axial direction.

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

18. The undulator according to claim 9, characterized in that, The temperature control unit includes: A heater, the heater being attached to the superconducting material portion; Refrigeration unit; Thermally conductive connecting wires; and One or more flanges, wherein the refrigeration unit is thermally connected to the superconducting material section via the thermally conductive connecting line and the one or more flanges.

19. An optical system, characterized in that, The optical system includes an undulator according to any one of claims 9 to 18, and the optical system is a synchrotron radiation system, a free-electron laser generation system, or a lithography system.

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