A helium-3 gas cell neutron spin independent flipping system and a control method thereof

Abstract

A dual-helium three-chamber neutron spin-independent flipping system and its control method are disclosed, belonging to the field of polarized neutron scattering technology. The flipping system includes: a polarizer chamber, an analyzer chamber, a common magnetic field assembly, and a flipping module; the common magnetic field assembly generates a common static magnetic field; the flipping module includes a first radio frequency (RF) coil, a second RF coil, and a flipping control system. The flipping control system outputs a first RF signal and sends it to the first and second RF coils respectively, causing the first RF coil to generate a first RF magnetic field and the second RF coil to generate a second RF magnetic field; the polarizer chamber contains... 3 The spin direction of He gas nuclei flips under the influence of a common static magnetic field and a first radio frequency magnetic field, within the analyzer's gas chamber. 3 The spin direction of He gas nuclei is flipped under the influence of a common static magnetic field and a second radio frequency magnetic field. This invention enables the spin direction of the emitted neutron beams from both the polarizer and the analyzer to be flipped independently online.

Description

Technical Field

[0001] This invention relates to the field of polarized neutron scattering technology, specifically to a dual-helium three-chamber neutron spin-independent flipping system and its control method. Background Technology

[0002] Polarized neutron scattering is a core technique for analyzing the microscopic magnetic structure, spin dynamics, and magnetic fluctuations of magnetic materials. One of its key technologies is the use of polarized helium-3 neutron spin filters to polarize and analyze neutron beams. Compared with traditional polarization methods (such as supermirrors), polarized helium-3 neutron spin filters offer advantages such as wide-angle coverage, broad energy spectrum adaptation, and uniform polarization, and have become standard equipment in mainstream international neutron sources (such as ILL, NIST, ISIS, and J-PARC).

[0003] Neutron spin filters are core components of polarized neutron scattering spectrometers, relying on spin-correlated nuclear absorption effects to screen neutron spin states: allowing only neutrons with a single spin direction to pass through while absorbing neutrons with another spin state, thus enabling neutron beam polarization or scattering neutron spin analysis. In existing neutron spin filters, to fully measure the four polarization channels ((+,+), (+,-), (-,+), (-,-)), the spin directions of the polarizer and analyzer need to be independently flipped. Spin flipping typically employs adiabatic fast passage (AFP) technology, which can achieve low-loss (<1%) neutron spin state switching.

[0004] However, the inventors recognized that existing neutron spin filters only support "single-sided online flipping": only the polarization direction of the polarizer can be quickly flipped online via the AFP, while the polarization direction of the analyzer cannot be flipped online and can only be reset via an offline pumping station or transfer system. In other words, existing neutron spin filters can only control the online flipping of the spin direction of the emitted neutron beam from the polarizer, but cannot control the online flipping of the spin direction of the emitted neutron beam from the analyzer. This results in limited measurement modes: the inability to flexibly switch the flipping combination of the polarizer and analyzer, the inability to completely and efficiently acquire data from all four polarization channels, or the need for offline operation, which is time-consuming and reduces neutron beam utilization efficiency. Summary of the Invention

[0005] The present invention mainly addresses the technical problem that existing neutron spin filters can only control the online reversal of the spin direction of the emitted neutron beam from the polarizer, but cannot control the online reversal of the spin direction of the emitted neutron beam from the analyzer.

[0006] According to a first aspect, one embodiment provides a dual-helium three-chamber neutron spin-independent flipping system, comprising:

[0007] The polarizer chamber is filled with 3 He gas;

[0008] The analyzer gas chamber is filled with 3 He gas, wherein the analyzer chamber and the polarizer chamber are arranged coaxially and collinearly;

[0009] A common magnetic field assembly is used to generate a common static magnetic field, and both the polarizer gas chamber and the analyzer gas chamber are located within the area of ​​influence of the common static magnetic field.

[0010] The flip module includes a first radio frequency (RF) coil, a second RF coil, and a flip control system. The flip control system is connected to both the first and second RF coils. The flip control system outputs a first RF signal and sends it to both the first and second RF coils. The first RF coil generates a first RF magnetic field in response to receiving the first RF signal, and the second RF coil generates a second RF magnetic field in response to receiving the first RF signal. The magnetic field directions of both the first and second RF magnetic fields are perpendicular to the magnetic field direction of the common static magnetic field. The polarizer chamber is located within the effective region of the first RF magnetic field. 3 The spin direction of He gas nuclei flips under the influence of the common static magnetic field and the first radio frequency magnetic field; the analyzer gas chamber is located within the region of influence of the second radio frequency magnetic field, and the analyzer gas chamber contains... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field and the second radio frequency magnetic field.

[0011] In one embodiment, the first radio frequency coil is sleeved on the outside of the polarizer gas chamber, and an electromagnetic shielding structure is provided on the outside of the first radio frequency coil; the second radio frequency coil includes a first coil and a second coil, the first coil is disposed on the outside of the end of the polarizer gas chamber away from the analyzer gas chamber, and the second coil is disposed on the outside of the end of the analyzer gas chamber away from the polarizer gas chamber.

[0012] or,

[0013] The second radio frequency coil is sleeved on the outside of the analyzer gas chamber, and an electromagnetic shielding structure is provided on the outside of the second radio frequency coil; the first radio frequency coil includes a first coil and a second coil, the first coil is disposed on the outside of the end of the polarizer gas chamber away from the analyzer gas chamber, and the second coil is disposed on the outside of the end of the analyzer gas chamber away from the polarizer gas chamber.

[0014] In one embodiment, the electromagnetic shielding structure is made of aluminum alloy or copper; and / or,

[0015] The thickness of the electromagnetic shielding structure is ≥2mm.

[0016] In one embodiment, the flip control system includes a first terminal, a first data acquisition unit, and a power amplification unit. The first terminal is connected to the first radio frequency coil and the second radio frequency coil in sequence through the first data acquisition unit and the power amplification unit, respectively.

[0017] The first terminal can output a first radio frequency signal and send it to the first radio frequency coil and the second radio frequency coil in sequence through the first data acquisition unit and the power amplification unit.

[0018] In one embodiment, the first terminal includes a first sub-terminal and a second sub-terminal, the first data acquisition unit includes a first data acquisition card and a second data acquisition card, and the power amplification unit includes a first power amplifier and a second power amplifier.

[0019] The first sub-terminal is connected to the first radio frequency coil via the first data acquisition card and the first power amplifier in sequence. The first sub-terminal can output a first radio frequency signal and send it to the first radio frequency coil via the first data acquisition card and the first power amplifier in sequence.

[0020] The second sub-terminal is connected to the second radio frequency coil via the second data acquisition card and the second power amplifier in sequence. The second sub-terminal can output a first radio frequency signal and send it to the second radio frequency coil via the second data acquisition card and the second power amplifier in sequence.

[0021] In one embodiment, the dual-helium three-chamber neutron spin-independent flipping system further includes:

[0022] The real-time monitoring module includes a first detection coil, a second detection coil, and a detection control system. The detection control system is connected to the first and second detection coils respectively. The first detection coil is disposed on the side of the polarizer gas chamber, and the second detection coil is disposed on the side of the analyzer gas chamber. The detection control system can output a second radio frequency signal and send it to the first and second detection coils respectively. In response to receiving the second radio frequency signal, the first detection coil generates a third radio frequency magnetic field, and the second detection coil generates a fourth radio frequency magnetic field in response to receiving the second radio frequency signal. The magnetic field directions of the third and fourth radio frequency magnetic fields are both perpendicular to the magnetic field direction of the common static magnetic field or both oblique to the magnetic field direction of the common static magnetic field. The first and second detection coils are also used to collect the FID signal induced by the third and fourth radio frequency magnetic fields after the second radio frequency signal ends and send it to the detection control system. The detection control system is configured to analyze and obtain the polarization rate of the polarizer gas chamber and the analyzer gas chamber respectively based on the collected FID signal.

[0023] In one embodiment, the detection and control system includes a second terminal, a second data acquisition unit, a transceiver combining unit, and a filtering unit. The second terminal is connected to the first detection coil and the second detection coil in sequence through the second data acquisition unit, the transceiver combining unit, and the filtering unit.

[0024] The second terminal can output a second radio frequency signal and send it to the first detection coil and the second detection coil in sequence through the second data acquisition unit, the transceiver combining unit and the filtering unit. The first detection coil and the second detection coil are used to collect the FID signal induced by the third radio frequency magnetic field and the fourth radio frequency magnetic field after the second radio frequency signal ends, and send it to the second terminal in sequence through the filtering unit, the transceiver combining unit and the second data acquisition unit. The second terminal is configured to analyze the polarization rate of the polarizer gas chamber and the analyzer gas chamber according to the collected FID signal.

[0025] In one embodiment, the second terminal includes a third sub-terminal and a fourth sub-terminal, the second data acquisition unit includes a third data acquisition card and a fourth data acquisition card, the transceiver combining unit includes a first duplexer and a second duplexer, the filtering unit includes a first filter and a second filter, and the FID signal includes a first FID signal and a second FID signal.

[0026] The third sub-terminal is connected to the first detection coil via the third data acquisition card, the first duplexer, and the first filter in sequence; the third sub-terminal can output a second radio frequency signal and send it to the first detection coil via the third data acquisition card, the first duplexer, and the first filter in sequence; the first detection coil is used to collect the first FID signal induced by the third radio frequency magnetic field after the second radio frequency signal ends, and send it to the third sub-terminal via the first filter, the first duplexer, and the third data acquisition card in sequence; the third sub-terminal is configured to analyze and obtain the polarization rate of the polarizer gas chamber based on the collected first FID signal;

[0027] The fourth sub-terminal is connected to the second detection coil via the fourth data acquisition card, the second duplexer, and the second filter in sequence. The fourth sub-terminal can output a second radio frequency signal and send it to the second detection coil via the fourth data acquisition card, the second duplexer, and the second filter in sequence. The second detection coil is used to collect the second FID signal induced by the fourth radio frequency magnetic field after the second radio frequency signal ends, and send it to the fourth sub-terminal via the second filter, the second duplexer, and the fourth data acquisition card in sequence. The fourth sub-terminal is configured to analyze the polarization of the analyzer gas chamber based on the collected second FID signal.

[0028] In one embodiment, the common magnetic field component is a dual Helmholtz coil or a Lee-Whiting coil; and / or,

[0029] Both the first and second RF coils are AFP coils.

[0030] According to a second aspect, one embodiment provides a control method for a dual-helium-three-chamber neutron spin-independent flipping system, applied to the dual-helium-three-chamber neutron spin-independent flipping system described in any one aspect, the method comprising:

[0031] At the first moment, the flip control system outputs a first radio frequency signal and sends it to the first radio frequency coil. In response to receiving the first radio frequency signal, the first radio frequency coil generates a first radio frequency magnetic field, causing the polarizer gas chamber... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field generated by the common magnetic field component and the first radio frequency magnetic field;

[0032] At the second moment, the flip control system outputs a first radio frequency signal and sends it to the second radio frequency coil. The second radio frequency coil, in response to receiving the first radio frequency signal, generates a second radio frequency magnetic field, causing the gas inside the analyzer chamber to... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field generated by the common magnetic field component and the second radio frequency magnetic field; wherein the time interval between the second moment and the first moment is greater than a threshold.

[0033] According to the dual-helium three-chamber neutron spin independent flipping system and its control method described above, since an independent radio frequency coil is provided for each of the polarizer chamber and the analyzer chamber, the flipping control system can output a first radio frequency signal and send it to the first radio frequency coil and the second radio frequency coil respectively. This allows the first radio frequency coil to generate a first radio frequency magnetic field acting on the polarizer, and the second radio frequency coil to generate a second radio frequency magnetic field acting on the analyzer. The two radio frequency magnetic fields do not interfere with each other and can work independently; thus, the spin independent flipping of the polarizer chamber and the analyzer chamber... 3 The spin direction of He gas nuclei can be independently flipped under the influence of corresponding radio frequency magnetic fields and common magnetic fields; because the spin direction of the emitted neutron beams from the polarizer gas chamber and the analyzer gas chamber is different from that inside the gas chamber. 3 The spin directions of He gas nuclei are the same, given that the polarizer and analyzer chambers contain... 3The spin direction of He gas nuclei can be independently flipped online, and the spin direction of the emitted neutron beams from the corresponding polarizer and analyzer chambers can also be independently flipped online. In other words, this dual-helium-three-chamber neutron spin independent flipping system can not only independently flip the polarization direction of the polarizer online, but also independently flip the polarization direction of the analyzer online, achieving bilateral online independent flipping. Thus, it can control the independent online flipping of the spin direction of both the emitted neutron beams from the polarizer and the analyzer online. With the dual-helium-three-chamber neutron spin independent flipping system provided by this invention, the flipping combination of the polarizer and analyzer can be flexibly switched without offline operation, and all four polarization channels can be collected completely and efficiently, greatly improving experimental efficiency. Attached Figure Description

[0034] Figure 1 A first-view structural schematic diagram of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment;

[0035] Figure 2 This is a second-view structural schematic diagram of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0036] Figure 3 This is a third-view structural schematic diagram of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0037] Figure 4 This is a first architectural block diagram of the flipping module of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0038] Figure 5 This is a schematic diagram of a first partial structure of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0039] Figure 6 This is a schematic diagram of the second partial structure of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0040] Figure 7 This is a schematic diagram of the polarizer of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0041] Figure 8 An exploded view of a polarizer of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment;

[0042] Figure 9 This is a second architecture block diagram of the flipping module of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0043] Figure 10This is a third architecture block diagram of the flipping module of a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0044] Figure 11 This is a first architectural block diagram of a real-time monitoring module for a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0045] Figure 12 This is a second architecture block diagram of a real-time monitoring module for a dual-helium three-chamber neutron spin-independent flipping system according to one embodiment.

[0046] Figure 13 This is a third architecture block diagram of a real-time monitoring module for a dual-helium three-chamber neutron spin-independent flipping system, as one embodiment. Figure 14 This is a flowchart illustrating a control method for a dual-helium three-chamber neutron spin-independent flipping system, as one embodiment.

[0047] Explanation of reference numerals in the attached figures:

[0048] 100. Polarizer gas chamber;

[0049] 200. Analyzer gas chamber;

[0050] 300. Common magnetic field components;

[0051] 400. Flip module; 410. First RF coil; 420. Second RF coil; 421. First coil; 422. Second coil; 430. Flip control system; 431. First terminal; 4311. First sub-terminal; 4312. Second sub-terminal; 432. First data acquisition unit; 4321. First data acquisition card; 4322. Second data acquisition card; 433. Power amplification unit; 4331. First power amplifier; 4332. Second power amplifier; 440. Electromagnetic shielding structure;

[0052] 500. Real-time monitoring module; 510. First detection coil; 520. Second detection coil; 530. Detection control system; 531. Second terminal; 5311. Third sub-terminal; 5312. Fourth sub-terminal; 532. Second data acquisition unit; 5321. Third data acquisition card; 5322. Fourth data acquisition card; 533. Transceiver combining unit; 5331. First duplexer; 5332. Second duplexer; 534. Filtering unit; 5341. First filter; 5342. Second filter;

[0053] 600. Fixed base;

[0054] 700. Fixed mechanism;

[0055] 800. Frame components;

[0056] 1000, a dual-helium three-chamber neutron spin-independent flipping system. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0058] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0059] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this invention, unless otherwise specified, include both direct and indirect connections (linkages).

[0060] Existing neutron spin filters still have the following drawbacks in terms of spin inversion:

[0061] (1) Lack of real-time independent monitoring of polarization state of dual chambers: The existing FID (Free Induction Attenuation) method is usually used for single chamber polarization monitoring, but there is no online independent calibration and closed-loop feedback control for the polarization state of each of the two chambers in the integrated dual chamber configuration.

[0062] (2) No complete dual-chamber independent flip control strategy: For different working modes such as polarizer flip alone and analyzer flip alone, the existing technology has not established corresponding timing control and state switching schemes.

[0063] Existing neutron spin filters suffer from drawbacks, resulting in incomplete polarization analysis capabilities, low measurement efficiency, and large systematic errors, making them unsuitable for the rapid, reliable, and fully polarized channel measurements required by modern neutron spectrometers. Therefore, this invention aims to systematically solve these problems and achieve true independent spin-flipping in a dual-cell configuration.

[0064] In one embodiment of the present invention, a dual-helium three-chamber neutron spin-independent flipping system 1000 is provided, such as... Figures 1-3 As shown in the overall structural diagram, the dual-helium three-chamber neutron spin-independent flipping system 1000 includes:

[0065] Polarizer chamber 100, filled with 3 He gas;

[0066] Analyzer gas chamber 200, filled with 3 He gas, analyzer chamber 200 and polarizer chamber 100 are arranged coaxially and collinearly;

[0067] The common magnetic field component 300 is used to generate a common static magnetic field, and both the polarizer gas chamber 100 and the analyzer gas chamber 200 are located within the area of ​​influence of the common static magnetic field.

[0068] The flip module 400 includes a first radio frequency coil 410, a second radio frequency coil 420, and a flip control system 430, such as... Figure 4 As shown, the flip control system 430 is connected to the first radio frequency coil 410 and the second radio frequency coil 420 respectively. The flip control system 430 can output a first radio frequency signal and send it to the first radio frequency coil 410 and the second radio frequency coil 420 respectively. The first radio frequency coil 410 generates a first radio frequency magnetic field in response to receiving the first radio frequency signal, and the second radio frequency coil 420 generates a second radio frequency magnetic field in response to receiving the first radio frequency signal. The magnetic field directions of the first radio frequency magnetic field and the second radio frequency magnetic field are both perpendicular to the magnetic field direction of the common static magnetic field. The polarizer gas chamber 100 is located within the effective area of ​​the first radio frequency magnetic field, and the polarizer gas chamber 100 contains... 3 The spin direction of He gas nuclei flips under the influence of a common static magnetic field and a first radio frequency magnetic field; the analyzer gas chamber 200 is located within the region of influence of the second radio frequency magnetic field, and the analyzer gas chamber 200 contains... 3 The spin direction of He gas nuclei flips under the influence of a common static magnetic field and a second radio frequency magnetic field.

[0069] In this dual-helium three-chamber neutron spin-independent flipping system 1000, the common magnetic field assembly 300 uses a dual Helmholtz coil configuration to provide a uniform main magnetic field (10~15G) for the polarizer chamber 100 and the analyzer chamber 200. The common magnetic field assembly 300 can also use an improved Lee-Whiting coil to obtain better uniformity in the central region.

[0070] Both the first RF coil 410 and the second RF coil 420 are AFP coils. Utilizing the AFP (Adiabatic Fast Passage) flipping principle, a linearly swept RF field B1 is superimposed on the static magnetic field B0 to cause the helium trinuclear spin to undergo adiabatic flipping.

[0071] In the dual-helium-three-chamber neutron spin independent flipping system 1000 provided in this embodiment of the invention, the polarizer chamber 100 and the analyzer chamber 200 are integrated into the same compact common magnetic field system, forming an integrated structure with dual-helium-three-chambers, which greatly reduces the difficulty of adding polarization function.

[0072] Because an independent radio frequency coil is provided for each of the polarizer chamber 100 and the analyzer chamber 200, the flip control system 430 can output a first radio frequency signal and send it to the first radio frequency coil 410 and the second radio frequency coil 420 respectively. This allows the first radio frequency coil 410 to generate a first radio frequency magnetic field acting on the polarizer, and the second radio frequency coil 420 to generate a second radio frequency magnetic field acting on the analyzer. The two radio frequency magnetic fields do not interfere with each other and can work independently; thus, the polarizer chamber 100 and the analyzer chamber 200 are respectively equipped with independent radio frequency coils. 3 The spin direction of He gas nuclei can be flipped under the influence of a corresponding radio frequency magnetic field and a common magnetic field.

[0073] Because the spin direction of the emitted neutron beams from polarizer chamber 100 and analyzer chamber 200 is opposite to that inside the chamber... 3 The spin directions of He gas nuclei are the same, given that the polarizer gas chamber 100 and the analyzer gas chamber 200 contain... 3 The spin direction of He gas nuclei can be independently flipped online, and consequently, the spin direction of the emitted neutron beams from the polarizer chamber 100 and the analyzer chamber 200 can also be independently flipped online. In other words, this dual-helium three-chamber neutron spin-independent flipping system 1000 can not only independently and rapidly flip the polarization direction of the polarizer online, but also independently flip the polarization direction of the analyzer online, achieving bilateral online flipping; thus, it can control not only the independent online flipping of the spin direction of the emitted neutron beam from the polarizer, but also the independent online flipping of the spin direction of the emitted neutron beam from the analyzer.

[0074] Both the polarizer and analyzer can be independently flipped online, offering complete functionality without offline operation. The polarizer and analyzer flipping combinations can be flexibly switched, significantly improving experimental efficiency. It can acquire complete and efficient data from all four polarization channels, supporting complete online measurements of (+,+), (+,-), (-,+), and (-,-), improving data acquisition efficiency and reducing the waste of scarce neutron beams.

[0075] As an optional implementation method, such as Figures 5-8 As shown, the first radio frequency coil 410 is sleeved on the outside of the polarizer gas chamber 100, and an electromagnetic shielding structure 440 is sleeved on the outside of the first radio frequency coil 410; the second radio frequency coil 420 includes a first coil 421 and a second coil 422. The first coil 421 is disposed on the outside of the end of the polarizer gas chamber 100 away from the analyzer gas chamber 200, and the second coil 422 is disposed on the outside of the end of the analyzer gas chamber 200 away from the polarizer gas chamber 100.

[0076] In this embodiment, the first RF coil 410 is a solenoid RF coil, and the second RF coil 420 is two rectangular or square planar coils. Of course, the coil types used in the first RF coil 410 and the second RF coil 420 can also be interchanged, that is, the first RF coil 410 can be two rectangular or square planar coils, and the second RF coil 420 can be a solenoid RF coil.

[0077] In this case, an alternative implementation is as follows: a second radio frequency coil 420 is sleeved on the outside of the analyzer gas chamber 200, and an electromagnetic shielding structure 440 is sleeved on the outside of the second radio frequency coil 420; the first radio frequency coil 410 includes a first coil 421 and a second coil 422, the first coil 421 is disposed on the outer side of the end of the polarizer gas chamber 100 away from the analyzer gas chamber 200, and the second coil 422 is disposed on the outer side of the end of the analyzer gas chamber 200 away from the polarizer gas chamber 100. This alternative implementation is not accompanied by separate drawings; those skilled in the art can clearly understand this structure by referring to the foregoing drawings and the textual description of this embodiment.

[0078] Furthermore, the electromagnetic shielding structure 440 can be made of aluminum alloy, and its thickness is ≥2mm. This embodiment of the invention utilizes an aluminum alloy shielding layer to isolate electromagnetic signals. When the flip control system 430 applies a radio frequency signal to the polarizer AFP coil (first radio frequency coil 410), the aluminum alloy shielding layer isolates the radio frequency signal, thereby ensuring that it can flip the polarization of helium-3 within the polarizer gas chamber 100 while minimizing the signal's impact on the analyzer. Similarly, when the flip control system 430 applies a radio frequency signal to the analyzer AFP coil (second radio frequency coil 420), the aluminum alloy shielding layer isolates the radio frequency signal, thereby ensuring that it can flip the polarization of helium-3 within the analyzer gas chamber 200 while minimizing the signal's impact on the polarizer, thus ensuring independent separation of the signals from the two gas chambers.

[0079] Alternatively, the electromagnetic shielding structure 440 can also be made of copper, which is thinner and easier to process.

[0080] As an optional implementation method, such as Figure 9As shown, the flip control system 430 includes a first terminal 431, a first data acquisition unit 432, and a power amplification unit 433. The first terminal 431 is connected to the first radio frequency coil 410 and the second radio frequency coil 420 in sequence through the first data acquisition unit 432 and the power amplification unit 433.

[0081] The first terminal 431 can output a first radio frequency signal, which is then transmitted to the first radio frequency coil 410 and the second radio frequency coil 420 respectively through the first data acquisition unit 432 and the power amplification unit 433.

[0082] Furthermore, such as Figure 10 As shown, the first terminal 431 includes a first sub-terminal 4311 and a second sub-terminal 4312, the first data acquisition unit 432 includes a first data acquisition card 4321 and a second data acquisition card 4322, and the power amplification unit 433 includes a first power amplifier 4331 and a second power amplifier 4332.

[0083] The first sub-terminal 4311 is connected to the first radio frequency coil 410 via the first data acquisition card 4321 and the first power amplifier 4331 in sequence. The first sub-terminal 4311 can output the first radio frequency signal and send it to the first radio frequency coil 410 via the first data acquisition card 4321 and the first power amplifier 4331 in sequence.

[0084] The second sub-terminal 4312 is connected to the second radio frequency coil 420 via the second data acquisition card 4322 and the second power amplifier 4332. The second sub-terminal 4312 can output the first radio frequency signal and send it to the second radio frequency coil 420 via the second data acquisition card 4322 and the second power amplifier 4332.

[0085] A Gaussian envelope function can be input into the igor program through the first sub-terminal 4311 and the second sub-terminal 4312. The radio frequency signal is output through the data acquisition unit, then amplified by the power amplifier (the amplification factor is between 1 and 100 times), and finally applied to the AFP coil.

[0086] In other words, this invention provides a dual-channel AFP switching module, comprising two independently controlled RF power amplifiers, with an electromagnetic shielding structure 440 positioned between the two AFP transmit coils, supporting independent spin switching of the polarizer chamber 100 and the analyzer chamber 200. The dual-channel AFP switching module includes:

[0087] 1. First AFP channel: corresponding to polarizer gas chamber 100, including first power amplifier 4331, first radio frequency coil 410 (polarizer AFP coil), first data acquisition card 4321, and first sub-terminal 4311 (computer).

[0088] 2. Second AFP channel: corresponding to analyzer gas chamber 200, including second power amplifier 4332, second radio frequency coil 420 (analyzer AFP coil), second data acquisition card 4322, and second sub-terminal 4312 (computer).

[0089] 3. Electromagnetic shielding structure 440: An aluminum alloy shielding layer is set on the outside of the polarizer.

[0090] 4. Common magnetic field system: It adopts a double Helmholtz coil configuration to provide a uniform main magnetic field for the two air chambers.

[0091] To address the lack of a complete independent dual-chamber flipping control strategy in existing neutron spin filters and the absence of corresponding timing control and state switching schemes, this invention's dual-channel AFP flipping module supports two operating modes:

[0092] Mode 1: Polarizer flipped individually

[0093] Step 1: At time t0, the first timing control unit enables the first RF power amplifier and performs AFP sweep (polarizer spin flip).

[0094] Step 2: At time t1 (t1-t0=Δt), the first channel completes the flip, and the second channel remains in standby mode.

[0095] Mode 2: Analyzer flipped separately

[0096] Step 1: At time t0, the second timing control unit enables the second RF power amplifier and performs an AFP sweep (analyzer spin flip).

[0097] Step 2: At time t1, the second channel completes the flip, while the first channel remains in standby mode.

[0098] To address the lack of a real-time independent monitoring method for the polarization state of dual-chamber systems, as an optional implementation method, such as... Figure 11 As shown, the dual-helium three-chamber neutron spin-independent flipping system 1000 also includes:

[0099] The real-time monitoring module 500 includes a first detection coil 510, a second detection coil 520, and a detection control system 530, wherein the detection control system 530 is connected to the first detection coil 510 and the second detection coil 520 respectively; see also Figure 1 , 36-8, the first detection coil 510 is disposed on the side of the polarizer gas chamber 100, and the second detection coil 520 is disposed on the side of the analyzer gas chamber 200; the detection control system 530 can output a second radio frequency signal and send it to the first detection coil 510 and the second detection coil 520 respectively. In response to receiving the second radio frequency signal, the first detection coil 510 generates a third radio frequency magnetic field, and the second detection coil 520 generates a fourth radio frequency magnetic field in response to receiving the second radio frequency signal. The magnetic field directions of the third radio frequency magnetic field and the fourth radio frequency magnetic field are both perpendicular to the magnetic field direction of the common static magnetic field or both oblique to the magnetic field direction of the common static magnetic field; the first detection coil 510 and the second detection coil 520 are also used to collect the FID (Free Induction Decay) signal induced by the third radio frequency magnetic field and the fourth radio frequency magnetic field after the second radio frequency signal ends, and send it to the detection control system 530. The detection control system 530 is configured to analyze and obtain the polarization of the polarizer gas chamber 100 and the analyzer gas chamber 200 respectively based on the collected FID signal.

[0100] The first detection coil 510 and the second detection coil 520 are both FID detection coils. In order to make the magnetic field directions of the third radio frequency magnetic field and the fourth radio frequency magnetic field perpendicular to the magnetic field direction of the common static magnetic field or oblique to the magnetic field direction of the common static magnetic field, the first detection coil 510 and the second detection coil 520 are in an inclined or vertical state when placed on the side of the gas chamber.

[0101] In the dual-helium three-chamber neutron spin independent flipping system 1000 provided in this embodiment of the invention, since an independent detection coil is set for each of the polarizer chamber 100 and the analyzer chamber 200, the detection control system 530 can output a second radio frequency signal and send it to the first detection coil 510 and the second detection coil 520 respectively. This allows the first detection coil 510 to generate a third radio frequency magnetic field and the second detection coil 520 to generate a fourth radio frequency magnetic field. Therefore, after the radio frequency excitation is removed, the first detection coil 510 and the second detection coil 520 can collect the FID decay signal released by the nuclear relaxation in the two chambers. The peak amplitude of the FID signal and... 3 The polarizability of He atomic nuclei is directly proportional to the polarizability of the two gas chambers. The real-time polarizability of the two chambers can be obtained by calculating the amplitude. The specific method for calculating the polarizability using FID signals is existing technology and will not be elaborated upon in this embodiment. This embodiment proposes a real-time independent monitoring scheme for the polarization state of two gas chambers based on FID signal separation: online independent calibration of the polarizability of the two gas chambers is achieved using FID measurement.

[0102] In some embodiments, such as Figure 12As shown, the detection control system 530 includes a second terminal 531, a second data acquisition unit 532, a transceiver combining unit 533, and a filtering unit 534. The second terminal 531 is connected to the first detection coil 510 and the second detection coil 520 in sequence through the second data acquisition unit 532, the transceiver combining unit 533, and the filtering unit 534.

[0103] The second terminal 531 can output a second radio frequency signal and send it sequentially through the second data acquisition unit 532, the transceiver combining unit 533 and the filtering unit 534 to the first detection coil 510 and the second detection coil 520 respectively. The first detection coil 510 and the second detection coil 520 are used to collect the FID signal induced by the third radio frequency magnetic field and the fourth radio frequency magnetic field after the second radio frequency signal ends, and send it sequentially through the filtering unit 534, the transceiver combining unit 533 and the second data acquisition unit 532 to the second terminal 531. The second terminal 531 is configured to analyze and obtain the polarization rate of the polarizer gas chamber 100 and the analyzer gas chamber 200 according to the collected FID signal.

[0104] Furthermore, such as Figure 13 As shown, the second terminal 531 includes a third sub-terminal 5311 and a fourth sub-terminal 5312, the second data acquisition unit 532 includes a third data acquisition card 5321 and a fourth data acquisition card 5322, the transceiver combining unit 533 includes a first duplexer 5331 and a second duplexer 5332, the filtering unit 534 includes a first filter 5341 and a second filter 5342, and the FID signal includes a first FID signal and a second FID signal.

[0105] The third sub-terminal 5311 is connected to the first detection coil 510 via the third data acquisition card 5321, the first duplexer 5331, and the first filter 5341 in sequence. The third sub-terminal 5311 can output a second radio frequency signal and send it to the first detection coil 510 via the third data acquisition card 5321, the first duplexer 5331, and the first filter 5341 in sequence. The first detection coil 510 is used to collect the first FID signal induced by the third radio frequency magnetic field after the second radio frequency signal ends and send it to the third sub-terminal 5311 via the first filter 5341, the first duplexer 5331, and the third data acquisition card 5321 in sequence. The third sub-terminal 5311 is configured to analyze and obtain the polarization rate of the polarizer chamber 100 based on the collected first FID signal.

[0106] The fourth sub-terminal 5312 is connected to the second detection coil 520 via the fourth data acquisition card 5322, the second duplexer 5332, and the second filter 5342. The fourth sub-terminal 5312 can output a second radio frequency signal and send it to the second detection coil 520 via the fourth data acquisition card 5322, the second duplexer 5332, and the second filter 5342. The second detection coil 520 is used to collect the second FID signal induced by the fourth radio frequency magnetic field after the second radio frequency signal ends and send it to the fourth sub-terminal 5312 via the second filter 5342, the second duplexer 5332, and the fourth data acquisition card 5322. The fourth sub-terminal 5312 is configured to analyze the polarization of the analyzer gas chamber 200 based on the collected second FID signal.

[0107] In other words, this invention provides a dual-chamber FID real-time monitoring module, comprising:

[0108] 1. First FID detection coil: placed on the side of polarizer gas chamber 100, used to excite and receive the nuclear magnetic resonance signal of the gas chamber.

[0109] 2. Second FID detector coil: placed on the side of the analyzer gas chamber 200, used to excite and receive the nuclear magnetic resonance signal of the gas chamber.

[0110] 3. Multi-channel data acquisition card: at least 2 independent input channels, sampling rate ≥1MHz.

[0111] 4. Duplexer: Used to simultaneously maintain the receiving signal circuit and the transmitting signal circuit.

[0112] 5. Filter: Used to suppress noise.

[0113] This invention proposes a real-time dual-channel independent monitoring system based on FID signal separation, which can obtain the polarization state of each of the two gas chambers in real time and realize closed-loop control.

[0114] In addition, the dual-chamber FID real-time monitoring module can also adopt an "alternating measurement" scheme, requiring only one FID detection system. The two chambers are connected in a time-sharing manner through mechanical switching or radio frequency switching, thus eliminating the need for independent coils in the dual-channel FID.

[0115] In some embodiments, the dual-helium three-cell neutron spin independent flipping system 1000 provided in this invention can also realize a "flip-verification" closed-loop control strategy for independent cell flipping: defining the timing logic for two operating modes, namely polarizer independent flipping and analyzer independent flipping, and verifying the flipping effect through FID measurement feedback. Specifically, in each mode, a closed-loop control process of "AFP flipping → waiting for the RF field to be applied to complete → FID monitoring and verification → judging the flipping loss rate" is executed.

[0116] An exemplary implementation, such as Figures 1-6 As shown, the dual-helium three-chamber neutron spin independent flipping system 1000 provided in this embodiment of the invention also includes a fixed base 600 and a fixing mechanism 700. The polarizer gas chamber 100 and the analyzer gas chamber 200 are both fixed on the fixed base 600. The fixing mechanism 700 is provided in two sets for fixing the dual Helmholtz coils (common magnetic field assembly 300). The fixed base 600 is set on the lower coil of the dual Helmholtz coils. The first coil 421 and the second coil 422 are fixed on the dual Helmholtz coils.

[0117] In addition, the dual-helium three-chamber neutron spin independent flipping system 1000 also includes a frame assembly 800, and a fixing mechanism 700 is fixed inside the frame assembly 800. Thus, all other components of the dual-helium three-chamber neutron spin independent flipping system 1000 are fixed inside the frame assembly 800, which can protect the various components of the dual-helium three-chamber neutron spin independent flipping system 1000.

[0118] In summary, the dual-helium-three-chamber neutron spin-independent flipping system provided in this invention, within a compact integrated dual-helium-three neutron spin filter configuration, achieves completely independent, low-loss, and repeatable spin flipping of the polarizer and analyzer through a dual-channel independently controlled AFP flipping system, a FID-based dual-chamber real-time monitoring method, and a modular control strategy. This results in independent flipping of the spin direction of the emitted neutron beams from the polarizer and analyzer. Specifically, this invention includes the following innovative technical means:

[0119] (1) Dual-channel AFP flip system: Two independent RF power amplifiers and AFP coils are designed, along with an electromagnetic shielding structure (aluminum alloy shielding layer), to achieve independent output of the RF field of the two air chambers and adjustable power, effectively suppressing dual-channel RF crosstalk.

[0120] (2) Independent monitoring method for polarization state of two chambers: Two FID signals are used to measure the polarization rate of the two helium-3 chambers in real time and independently.

[0121] (3) Control strategy: Establish multiple working modes such as polarizer individual flip and analyzer individual flip, and ensure repeatability and low loss rate (<1%) of each flip through closed-loop feedback control.

[0122] The present invention can mainly solve the following technical problems:

[0123] (1) The independent online spin flipping of the two chambers in the integrated dual-helium three-chamber system is realized, so that the polarizer and analyzer can quickly and repeatedly switch the spin direction through AFP technology, thereby supporting the complete and efficient measurement of all four polarization channels.

[0124] (2) Solve the electromagnetic crosstalk problem of dual-channel AFP radio frequency field in compact space. Through hardware design (independent shielding, coil geometry layout optimization), ensure that the switching efficiency of each air cell is not lower than that of a single air cell (<1%).

[0125] A combined scheme to achieve RF crosstalk suppression: electromagnetic simulation optimization of coil layout + aluminum alloy shielding layer + time-division switching, ensuring crosstalk ≤1%; an aluminum alloy shielding layer (thickness ≥2mm) is set between the two AFP coils; the AFP switching adopts a time-division execution strategy, and the start time interval between the two switching operations is ≥10s.

[0126] (3) To solve the problem of real-time independent monitoring of the polarization state of two gas chambers, a method is provided that can monitor the polarization state of two gas chambers at the same time, so as to realize online calibration and feedback control of polarizability.

[0127] (4) Establish a complete dual-chamber independent flipping control strategy that can automatically switch working modes according to experimental needs and ensure the high reliability and repeatability of the flipping process.

[0128] The dual-helium-three-chamber neutron spin-independent flipping system provided in this invention embodiment can achieve independent control of the spin direction of the two independent helium-three chambers of the polarizer and analyzer in an integrated compact configuration. This enables independent control of the spin direction of the emitted neutron beam from the polarizer and analyzer, filling the gap in the prior art that cannot achieve independent online spin flipping of dual chambers, and significantly improving the polarization analysis capability of the neutron spin filter.

[0129] In one embodiment of the present invention, a control method 10000 for a dual-helium-three-chamber neutron spin-independent flipping system is provided, applied to the dual-helium-three-chamber neutron spin-independent flipping system provided in the above embodiment. The method includes:

[0130] Step 1100: At the first moment, the flip control system outputs a first radio frequency signal and sends it to the first radio frequency coil. In response to receiving the first radio frequency signal, the first radio frequency coil generates a first radio frequency magnetic field, causing the polarizer gas chamber... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field generated by the common magnetic field assembly and the first radio frequency magnetic field;

[0131] Step 1200: At the second moment, the flip control system outputs a first radio frequency signal and sends it to the second radio frequency coil. In response to receiving the first radio frequency signal, the second radio frequency coil generates a second radio frequency magnetic field, causing the gas inside the analyzer chamber to... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field generated by the common magnetic field component and the second radio frequency magnetic field; wherein the time interval between the second moment and the first moment is greater than a threshold.

[0132] Specifically, the time interval between the second moment and the first moment is ≥10s.

[0133] In the method provided in this embodiment of the invention, the flipping adopts a time-division execution strategy, and the starting time interval between two flipping operations is ≥10s, which can achieve radio frequency crosstalk suppression.

[0134] This document describes various exemplary embodiments with reference to them. However, those skilled in the art will recognize that changes and modifications can be made to the exemplary embodiments without departing from the scope of this document. For example, various operational steps and components for performing operational steps can be implemented in different ways depending on the specific application or considering any number of cost functions associated with the operation of the system (e.g., one or more steps can be deleted, modified, or combined with other steps).

[0135] While the principles herein have been illustrated in various embodiments, numerous modifications to the structures, arrangements, proportions, elements, materials, and components, particularly suited to specific environments and operational requirements, may be used without departing from the principles and scope of this disclosure. These modifications and other alterations or alterations will be included within the scope of this document. Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the fundamental principles of the invention.

Claims

1. A dual-helium three-chamber neutron spin-independent flipping system, characterized in that, include: The polarizer chamber is filled with 3 He gas; The analyzer gas chamber is filled with 3 He gas, wherein the analyzer chamber and the polarizer chamber are arranged coaxially and collinearly; A common magnetic field assembly is used to generate a common static magnetic field, and both the polarizer gas chamber and the analyzer gas chamber are located within the area of ​​influence of the common static magnetic field. The flip module includes a first radio frequency (RF) coil, a second RF coil, and a flip control system. The flip control system is connected to both the first and second RF coils. The flip control system outputs a first RF signal and sends it to both the first and second RF coils. The first RF coil generates a first RF magnetic field in response to receiving the first RF signal, and the second RF coil generates a second RF magnetic field in response to receiving the first RF signal. The magnetic field directions of both the first and second RF magnetic fields are perpendicular to the magnetic field direction of the common static magnetic field. The polarizer chamber is located within the effective region of the first RF magnetic field. 3 The spin direction of He gas nuclei flips under the influence of the common static magnetic field and the first radio frequency magnetic field; the analyzer gas chamber is located within the region of influence of the second radio frequency magnetic field, and the analyzer gas chamber contains... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field and the second radio frequency magnetic field.

2. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 1, characterized in that, The first radio frequency coil is sleeved on the outside of the polarizer gas chamber, and an electromagnetic shielding structure is provided on the outside of the first radio frequency coil; the second radio frequency coil includes a first coil and a second coil, the first coil is disposed on the outside of the end of the polarizer gas chamber away from the analyzer gas chamber, and the second coil is disposed on the outside of the end of the analyzer gas chamber away from the polarizer gas chamber. or, The second radio frequency coil is sleeved on the outside of the analyzer gas chamber, and an electromagnetic shielding structure is provided on the outside of the second radio frequency coil; the first radio frequency coil includes a first coil and a second coil, the first coil is disposed on the outside of the end of the polarizer gas chamber away from the analyzer gas chamber, and the second coil is disposed on the outside of the end of the analyzer gas chamber away from the polarizer gas chamber.

3. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 2, characterized in that, The electromagnetic shielding structure is made of aluminum alloy or copper; and / or, The thickness of the electromagnetic shielding structure is ≥2mm.

4. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 1, characterized in that, The flip control system includes a first terminal, a first data acquisition unit, and a power amplification unit. The first terminal is connected to the first radio frequency coil and the second radio frequency coil in sequence through the first data acquisition unit and the power amplification unit, respectively. The first terminal can output a first radio frequency signal and send it to the first radio frequency coil and the second radio frequency coil in sequence through the first data acquisition unit and the power amplification unit.

5. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 4, characterized in that, The first terminal includes a first sub-terminal and a second sub-terminal; the first data acquisition unit includes a first data acquisition card and a second data acquisition card; and the power amplification unit includes a first power amplifier and a second power amplifier. The first sub-terminal is connected to the first radio frequency coil via the first data acquisition card and the first power amplifier in sequence. The first sub-terminal can output a first radio frequency signal and send it to the first radio frequency coil via the first data acquisition card and the first power amplifier in sequence. The second sub-terminal is connected to the second radio frequency coil via the second data acquisition card and the second power amplifier in sequence. The second sub-terminal can output a first radio frequency signal and send it to the second radio frequency coil via the second data acquisition card and the second power amplifier in sequence.

6. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 1, characterized in that, The dual-helium three-chamber neutron spin-independent flipping system also includes: The real-time monitoring module includes a first detection coil, a second detection coil, and a detection control system. The detection control system is connected to the first and second detection coils respectively. The first detection coil is disposed on the side of the polarizer gas chamber, and the second detection coil is disposed on the side of the analyzer gas chamber. The detection control system can output a second radio frequency signal and send it to the first and second detection coils respectively. In response to receiving the second radio frequency signal, the first detection coil generates a third radio frequency magnetic field, and the second detection coil generates a fourth radio frequency magnetic field in response to receiving the second radio frequency signal. The magnetic field directions of the third and fourth radio frequency magnetic fields are both perpendicular to the magnetic field direction of the common static magnetic field or both oblique to the magnetic field direction of the common static magnetic field. The first and second detection coils are also used to collect the FID signal induced by the third and fourth radio frequency magnetic fields after the second radio frequency signal ends and send it to the detection control system. The detection control system is configured to analyze and obtain the polarization rate of the polarizer gas chamber and the analyzer gas chamber respectively based on the collected FID signal.

7. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 6, characterized in that, The detection and control system includes a second terminal, a second data acquisition unit, a transceiver combining unit, and a filtering unit. The second terminal is connected to the first detection coil and the second detection coil in sequence through the second data acquisition unit, the transceiver combining unit, and the filtering unit. The second terminal can output a second radio frequency signal and send it to the first detection coil and the second detection coil in sequence through the second data acquisition unit, the transceiver combining unit and the filtering unit. The first detection coil and the second detection coil are used to collect the FID signal induced by the third radio frequency magnetic field and the fourth radio frequency magnetic field after the second radio frequency signal ends, and send it to the second terminal in sequence through the filtering unit, the transceiver combining unit and the second data acquisition unit. The second terminal is configured to analyze the polarization rate of the polarizer gas chamber and the analyzer gas chamber according to the collected FID signal.

8. The dual-helium three-chamber neutron spin-independent flipping system as described in claim 7, characterized in that, The second terminal includes a third sub-terminal and a fourth sub-terminal; the second data acquisition unit includes a third data acquisition card and a fourth data acquisition card; the transceiver combining unit includes a first duplexer and a second duplexer; the filtering unit includes a first filter and a second filter; and the FID signal includes a first FID signal and a second FID signal. The third sub-terminal is connected to the first detection coil via the third data acquisition card, the first duplexer, and the first filter in sequence; the third sub-terminal can output a second radio frequency signal and send it to the first detection coil via the third data acquisition card, the first duplexer, and the first filter in sequence; the first detection coil is used to collect the first FID signal induced by the third radio frequency magnetic field after the second radio frequency signal ends, and send it to the third sub-terminal via the first filter, the first duplexer, and the third data acquisition card in sequence; the third sub-terminal is configured to analyze and obtain the polarization rate of the polarizer gas chamber based on the collected first FID signal; The fourth sub-terminal is connected to the second detection coil via the fourth data acquisition card, the second duplexer, and the second filter in sequence. The fourth sub-terminal can output a second radio frequency signal and send it to the second detection coil via the fourth data acquisition card, the second duplexer, and the second filter in sequence. The second detection coil is used to collect the second FID signal induced by the fourth radio frequency magnetic field after the second radio frequency signal ends, and send it to the fourth sub-terminal via the second filter, the second duplexer, and the fourth data acquisition card in sequence. The fourth sub-terminal is configured to analyze the polarization of the analyzer gas chamber based on the collected second FID signal.

9. The dual-helium three-chamber neutron spin-independent flipping system as described in any one of claims 1 to 8, characterized in that, The common magnetic field component is a dual Helmholtz coil or a Lee-Whiting coil; and / or, Both the first and second RF coils are AFP coils.

10. A control method for a dual-helium-three-chamber neutron spin-independent flipping system, applied to the dual-helium-three-chamber neutron spin-independent flipping system according to any one of claims 1 to 9, characterized in that, The method includes: At the first moment, the flip control system outputs a first radio frequency signal and sends it to the first radio frequency coil. In response to receiving the first radio frequency signal, the first radio frequency coil generates a first radio frequency magnetic field, causing the polarizer gas chamber... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field generated by the common magnetic field component and the first radio frequency magnetic field; At the second moment, the flip control system outputs a first radio frequency signal and sends it to the second radio frequency coil. In response to receiving the first radio frequency signal, the second radio frequency coil generates a second radio frequency magnetic field, causing the gas inside the analyzer chamber to... 3 The spin direction of He gas nuclei is flipped under the influence of the common static magnetic field generated by the common magnetic field component and the second radio frequency magnetic field; wherein the time interval between the second moment and the first moment is greater than a threshold.

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