A magnetic field system and magnetic field control method for a wide-angle helium-3 neutron polarization device

Abstract

A magnetic field system and magnetic field control method for a wide-angle helium-3 neutron polarization device are disclosed, relating to the field of helium-3 polarization technology. The system includes four sets of Helmholtz coils; a first set of Helmholtz coils is nested within a second set of Helmholtz coils; the plane of the first set of Helmholtz coils intersects the plane of the second set of Helmholtz coils, with the intersection line passing through the center of the circles containing the first and second sets of Helmholtz coils; the second set of Helmholtz coils is nested within a third set of Helmholtz coils; the third set of Helmholtz coils is nested within a fourth set of Helmholtz coils; the plane of the third set of Helmholtz coils intersects the plane of the fourth set of Helmholtz coils, with the intersection line passing through the center of the circles containing the third and fourth sets of Helmholtz coils; the plane of the third set of Helmholtz coils is perpendicular to the plane of the first set of Helmholtz coils; the plane of the fourth set of Helmholtz coils is perpendicular to the plane of the second set of Helmholtz coils.

Description

Technical Field

[0001] This invention relates to the field of polarized helium-3 technology, specifically to a magnetic field system and magnetic field control method for a wide-angle helium-3 neutron polarization device. Background Technology

[0002] XYZ polarization analysis of polarized neutrons is an effective method for separating magnetic, nuclear coherent, and incoherent scattering, particularly suitable for neutron instruments equipped with wide-angle detectors. In this technique, neutron polarization is adiabatically transmitted into the sample in a selected direction, and the scattered beam undergoes spin analysis along the same direction as the incident beam polarization. Compared to conventional neutron polarization analysis, this wide-angle XYZ polarization analysis can be performed over a wide range of scattering angles, offering faster analysis speeds and higher detection efficiency.

[0003] Currently, the wide-angle polarization spectrometers built internationally for wide-angle polarization analysis utilize either supermirror arrays or polarized helium-3 neutron devices. While supermirror arrays can also be considered for wide-angle polarization analysis, their polarized neutron beam width and receiving angle are relatively small, and they are expensive. In contrast, wide-angle polarized helium-3 neutron devices offer a wide operating wavelength spectrum, a large receiving angle, uniform polarization analysis capability, and are relatively inexpensive. Therefore, using polarized helium-3 neutron spin filters to construct a wide-angle polarization spectrometer is the most attractive solution. However, the depolarization time of a wide-angle polarized helium-3 device is determined by the magnetic field gradient, requiring a relatively large uniform magnetic field region. To maintain the long-term stability of the polarization rate of helium-3, a magnetic field device capable of providing a highly uniform magnetic field is needed. Due to the limited space in neutron source spectrometers, the overall diameter and height of the magnetic field device must be minimized to allow it to be installed within a general-purpose spectrometer via a universal flange. In neutron experiments, the direction of the main magnetic field of polarized helium-3 needs to be changed to obtain polarized neutrons with different polarization directions.

[0004] Currently, the most advanced magnetic field devices internationally use a nested Helmholtz coil configuration, commonly one or two sets of Helmholtz coils. However, these configurations have neutron black areas and the direction of the main magnetic field cannot be switched. Configurations with four nested Helmholtz coils, on the other hand, do not have neutron black areas, resulting in a larger neutron scattering angle. However, the direction of the main magnetic field they generate can only be switched within a two-dimensional plane. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a magnetic field system for a wide-angle helium-3 neutron polarization device in which the magnetic field direction can be switched in three-dimensional space.

[0006] According to the first aspect, one embodiment provides a magnetic field system for a wide-angle helium-tri-neutron polarization device, including a first set of Helmholtz coils, a second set of Helmholtz coils, a third set of Helmholtz coils and a fourth set of Helmholtz coils.

[0007] The first set of Helmholtz coils is fitted onto the second set of Helmholtz coils. The inner diameter of the first set of Helmholtz coils is larger than the outer diameter of the second set of Helmholtz coils. The plane in which the first set of Helmholtz coils is located intersects the plane in which the second set of Helmholtz coils is located. Furthermore, the line of intersection between the plane in which the first set of Helmholtz coils is located and the plane in which the second set of Helmholtz coils is located passes through the center of the circle in which the first set of Helmholtz coils and the second set of Helmholtz coils are located.

[0008] The second set of Helmholtz coils is fitted onto the third set of Helmholtz coils, and the inner diameter of the second set of Helmholtz coils is larger than the outer diameter of the third set of Helmholtz coils; the third set of Helmholtz coils is fitted onto the fourth set of Helmholtz coils, and the inner diameter of the third set of Helmholtz coils is larger than the outer diameter of the fourth set of Helmholtz coils; the plane in which the third set of Helmholtz coils is located intersects the plane in which the fourth set of Helmholtz coils is located, and the line of intersection of the plane in which the plane in which the third set of Helmholtz coils is located and the plane in which the fourth set of Helmholtz coils is located passes through the center of the circle in which the third set of Helmholtz coils and the fourth set of Helmholtz coils are located.

[0009] The plane in which the third set of Helmholtz coils is located is perpendicular to the plane in which the first set of Helmholtz coils is located; the plane in which the fourth set of Helmholtz coils is located is perpendicular to the plane in which the second set of Helmholtz coils is located.

[0010] The direction of the magnetic field in the magnetic field system is determined by the magnitude and direction of the current flowing through each set of Helmholtz coils, and the direction of the magnetic field is used to maintain the spin direction of the helium-3.

[0011] In one embodiment, a power module is also included.

[0012] Each set of Helmholtz coils is connected to an independent power module, which controls the magnitude and direction of the current passing through each set of Helmholtz coils.

[0013] In one embodiment, the magnetic field direction of the magnetic field system is determined based on the magnitude and direction of the current flowing through each set of Helmholtz coils, including:

[0014] The power module connected to the first set of Helmholtz coils applies a counterclockwise current to the first set of Helmholtz coils to generate a first magnetic field;

[0015] The power module connected to the second set of Helmholtz coils applies a counterclockwise current to the second set of Helmholtz coils to generate a second magnetic field;

[0016] The power module connected to the third set of Helmholtz coils applies a clockwise current to the third set of Helmholtz coils to generate a third magnetic field.

[0017] The power module connected to the fourth set of Helmholtz coils applies a clockwise current to the fourth set of Helmholtz coils to generate a fourth magnetic field.

[0018] Each power module adjusts the magnitude of the current applied to the first set of Helmholtz coils, the second set of Helmholtz coils, the third set of Helmholtz coils, and the fourth set of Helmholtz coils, in order to generate a magnetic field with the magnetic field direction pointing in the first direction based on the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field.

[0019] In one embodiment, the magnetic field direction of the magnetic field system is determined based on the magnitude and direction of the current flowing through each set of Helmholtz coils, including:

[0020] The power module connected to the first set of Helmholtz coils applies a counterclockwise current to the first set of Helmholtz coils to generate a first magnetic field;

[0021] The power module connected to the second set of Helmholtz coils applies a counterclockwise current to the second set of Helmholtz coils to generate a second magnetic field;

[0022] The power module connected to the third set of Helmholtz coils applies a counterclockwise current to the third set of Helmholtz coils to generate a third magnetic field.

[0023] The power module connected to the fourth set of Helmholtz coils applies a counterclockwise current to the fourth set of Helmholtz coils to generate a fourth magnetic field.

[0024] Each power module adjusts the magnitude of the current applied to the first set of Helmholtz coils, the second set of Helmholtz coils, the third set of Helmholtz coils, and the fourth set of Helmholtz coils, in order to generate a magnetic field pointing in the second direction based on the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field.

[0025] In one embodiment, the magnetic field direction of the magnetic field system is determined based on the magnitude and direction of the current flowing through each set of Helmholtz coils, including:

[0026] The power module connected to the first set of Helmholtz coils applies a counterclockwise current to the first set of Helmholtz coils to generate a first magnetic field;

[0027] The power module connected to the second set of Helmholtz coils applies a counterclockwise current to the second set of Helmholtz coils to generate a second magnetic field;

[0028] The power module connected to the third set of Helmholtz coils applies a counterclockwise current to the third set of Helmholtz coils to generate a third magnetic field.

[0029] The power module connected to the fourth set of Helmholtz coils applies a clockwise current to the fourth set of Helmholtz coils to generate a fourth magnetic field.

[0030] Each power module adjusts the magnitude of the current applied by the first, second, third, and fourth Helmholtz coils to generate a magnetic field pointing in the third direction based on the first, second, third, and fourth magnetic fields.

[0031] In one embodiment, the magnetic field gradient determined based on the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field is less than a set gradient.

[0032] In one embodiment, the set gradient is 10. -3 / cm.

[0033] In one embodiment, the intersection angle between the plane where the first set of Helmholtz coils is located and the plane where the second set of Helmholtz coils is located is less than 90 degrees.

[0034] In one embodiment, the intersection angle between the plane where the third set of Helmholtz coils is located and the plane where the fourth set of Helmholtz coils is located is less than 90 degrees.

[0035] According to the second aspect, one embodiment provides a magnetic field control method for a wide-angle helium-3 neutron polarization device. The method employs the aforementioned magnetic field system, in which the magnitude and direction of the current flowing through each set of Helmholtz coils are controlled to determine the magnetic field direction; the spin direction of helium-3 is maintained by the magnetic field direction.

[0036] According to the magnetic field system and magnetic field control method of the wide-angle helium-3 neutron polarization device described in the above embodiment, the magnetic field system includes four sets of Helmholtz coils. The first and second sets of Helmholtz coils are arranged alternately, as are the third and fourth sets. The third and fourth sets of Helmholtz coils are perpendicular to the first and second sets, respectively. The first and second sets of Helmholtz coils generate magnetic fields in two directions. Adding the perpendicular third and fourth sets of Helmholtz coils determines a third direction of magnetic field. This allows for the determination of a magnetic field system for a wide-angle helium-3 neutron polarization device where the magnetic field direction can switch in three-dimensional space. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the two-dimensional structure of four Helmholtz coils in the magnetic field system of a wide-angle helium-3 neutron polarization device in one embodiment. Figure 1 ;

[0038] Figure 2 This is a schematic diagram of the three-dimensional structure of two sets of Helmholtz coils in the magnetic field system of a wide-angle helium-3 neutron polarization device in one embodiment.

[0039] Figure 3 This is a schematic diagram of the two-dimensional structure of four Helmholtz coils in the magnetic field system of a wide-angle helium-3 neutron polarization device in one embodiment. Figure 2 ;

[0040] Figure 4 This is a schematic diagram showing the direction of the magnetic field generated by the two Helmholtz coils of the magnetic field system of a wide-angle helium-3 neutron polarization device in one embodiment. Figure 1 ;

[0041] Figure 5 This is a schematic diagram showing the direction of the magnetic field generated by the two Helmholtz coils of the magnetic field system of a wide-angle helium-3 neutron polarization device in one embodiment. Figure 2 ;

[0042] Figure 6 This is a flowchart of a method for controlling the magnetic field of a wide-angle helium-3 neutron polarization device in another embodiment. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. 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 this application. 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 this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application 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.

[0044] 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.

[0045] 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. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages).

[0046] Please refer to Figure 1 This application provides a magnetic field system for a wide-angle helium-3 neutron polarization device. The main body of the magnetic field system is composed of four sets of Helmholtz coils, specifically the first set of Helmholtz coils (i.e., the... Figure 1 B1), the second set of Helmholtz coils (i.e. Figure 1 (B2 in the middle), the third set of Helmholtz coils (i.e.) Figure 1 B1c) and the fourth set of Helmholtz coils (i.e. Figure 1 (B2c in the text). A Helmholtz coil consists of a pair of identical circular conductor coils.

[0047] Please refer to Figure 2 In some embodiments, in the magnetic field system used in this application, the inner diameter of the first set of Helmholtz coils B1 is larger than the outer diameter of the second set of Helmholtz coils B2, and the first set of Helmholtz coils B1 is fitted onto the second set of Helmholtz coils B2. The plane where the first set of Helmholtz coils B1 is located intersects the plane where the second set of Helmholtz coils B2 is located, and the intersection line of the planes where the first set of Helmholtz coils B1 and the second set of Helmholtz coils B2 is located passes through the center of the circle where the third set of Helmholtz coils B1c and the fourth set of Helmholtz coils are located. That is, the first set of Helmholtz coils B1 and the second set of Helmholtz coils B2 intersect, and the intersection line passes through the diameters of the first set of Helmholtz coils B1 and the second set of Helmholtz coils B2. In some embodiments, the intersection angle between the plane where the first set of Helmholtz coils B1 and the plane where the second set of Helmholtz coils B2 is located is less than 90 degrees.

[0048] In the magnetic field system used in this application, the inner diameter of the second Helmholtz coil B2 is larger than the outer diameter of the third Helmholtz coil B1c, and the inner diameter of the third Helmholtz coil B1c is larger than the outer diameter of the fourth Helmholtz coil B2c. The third and fourth Helmholtz coils B1c and B2c are also intersected, and the intersecting method is similar to that of the first and second Helmholtz coils B1c. Specifically, the plane containing the third Helmholtz coil B1c intersects the plane containing the fourth Helmholtz coil B2c, and the line of intersection between the two planes passes through the center of the circles containing both coils. In some embodiments, the intersection angle between the plane where the third Helmholtz coil B1c is located and the plane where the fourth Helmholtz coil B2c is located is less than 90 degrees.

[0049] However, the plane where the third Helmholtz coil B1c is located is perpendicular to the plane where the first Helmholtz coil B1 is located, and the plane where the fourth Helmholtz coil B2c is located is perpendicular to the plane where the second Helmholtz coil B2 is located.

[0050] Please refer to Figure 1 This is a front view of the four sets of Helmholtz coils in the magnetic field system. That is, from the plane where the first set of Helmholtz coils B1 and the second set of Helmholtz coils B2 are located, the complete third set of Helmholtz coils B1c and the fourth set of Helmholtz coils B2c can be seen. In other words, the third set of Helmholtz coils B1c and the fourth set of Helmholtz coils B2c are perpendicular to the first set of Helmholtz coils B1 and the second set of Helmholtz coils B2.

[0051] Please refer to Figure 3 This is a side view of the four Helmholtz coils in the magnetic field system, that is, viewed from the plane where the third Helmholtz coil B1c and the fourth Helmholtz coil B2c are located. The complete first Helmholtz coil B1 and the second Helmholtz coil B2 can be seen. That is, the first Helmholtz coil B1 and the second Helmholtz coil B2 are perpendicular to the third Helmholtz coil B1c and the fourth Helmholtz coil B2c.

[0052] In some embodiments, the magnetic field system also includes a power supply module, with each set of Helmholtz coils connected to an independent power supply module, through which the magnitude and direction of the current passing through each set of Helmholtz coils are adjusted.

[0053] Due to the magnetic effect of the current, each Helmholtz coil is powered by an independent power module. In this way, each pair of Helmholtz coils will generate a very uniform magnetic field region in the central area, thus forming four directional vectors on the central axis. Finally, by changing the magnitude and direction of the current in the four pairs of coils, the four sets of Helmholtz coils can be superimposed in the central area to generate a magnetic field direction that can be arbitrarily adjusted in three-dimensional space.

[0054] In some embodiments, because helium-3 has a spin, the direction of the helium-3 spin needs to be maintained by the direction of the magnetic field generated in the magnetic field system.

[0055] In some embodiments, please refer to Figure 4 A pair of Helmholtz coils can generate a uniform magnetic field region at the center and can also generate a vector magnetic field along the central axis of the coils, defined by... Figure 4 The positive direction is clockwise when viewed from the positive z-axis downwards. When the power module connected to the first Helmholtz coil B1 applies a counterclockwise current to the first Helmholtz coil B1, the first Helmholtz coil B1 generates the first magnetic field, such as... Figure 4 The direction of the magnetic field is indicated by number 1. When the second Helmholtz coil B2 is connected to the power module and a counterclockwise current is applied to it, the second Helmholtz coil B2 generates a second magnetic field, such as... Figure 4 The direction of the magnetic field marked 2. Please refer to [the relevant information]. Figure 5 When the power module connected to the third Helmholtz coil B1c applies a clockwise current to the third Helmholtz coil B1c, the third Helmholtz coil B1c will generate a third magnetic field, such as... Figure 5 The direction of the magnetic field indicated by number 3. When the power module connected to the fourth Helmholtz coil B2c applies a clockwise current to the fourth Helmholtz coil B2c, the fourth Helmholtz coil B2c will generate a fourth magnetic field, such as... Figure 5 The direction of the magnetic field designated as 4. Based on this, the directions of the first, second, third, and fourth magnetic fields have been determined. At this point, adjusting the current in each Helmholtz coil can affect the magnitudes of the first, second, third, and fourth magnetic fields. Then, through the principle of magnetic field superposition, a magnetic field pointing in the first direction can be generated. In some embodiments, the first direction is the direction of the y-axis.

[0056] In some embodiments, when the generated magnetic field direction is along the y-axis, the normalized gradient of the magnetic field placed at a set point in the polarized helium-3 region is calculated using the following formula:

[0057]

[0058] Wherein, Gradient represents the magnitude of the normalized magnetic field gradient placed at a designated point in the polarized helium-3 region. B is the component of the magnetic field strength at the set point in the x-axis direction. x The magnitude of the gradient in space, B is the component of the magnetic field strength at the set point in the z-axis direction. z The magnitude of the gradient in space.

[0059]

[0060]

[0061] in, B is the component of the magnetic field strength at the set point in the x-axis direction. x The partial derivative along the x-axis, B is the component of the magnetic field strength at the set point in the x-axis direction. x The partial derivative along the y-axis, B is the component of the magnetic field strength at the set point in the x-axis direction. x Partial derivative along the z-axis; B is the component of the magnetic field strength at the set point in the z-axis direction. z The partial derivative along the x-axis, B is the component of the magnetic field strength at the set point in the z-axis direction. z The partial derivative along the y-axis, B is the component of the magnetic field strength at the set point in the z-axis direction. z Partial derivative along the z-axis.

[0062] In some embodiments, the normalized magnetic field gradient at a set point placed in the polarized helium-3 region can be calculated to be less than 10 using the above calculations. -3 / cm.

[0063] Similarly, when the power module connected to the first Helmholtz coil B1 applies a counterclockwise current to the first Helmholtz coil B1, the first Helmholtz coil B1 generates a first magnetic field. When the power module connected to the second Helmholtz coil B2 applies a counterclockwise current to the second Helmholtz coil B2, the second Helmholtz coil B2 generates a second magnetic field. When the power module connected to the third Helmholtz coil B1c applies a counterclockwise current to the third Helmholtz coil B1c, the third Helmholtz coil B1c generates a third magnetic field. When the power module connected to the fourth Helmholtz coil B2c applies a counterclockwise current to the fourth Helmholtz coil B2c, the fourth Helmholtz coil B2c generates a fourth magnetic field. At this point, the directions of the first, second, third, and fourth magnetic fields are determined. Adjusting the current in each Helmholtz coil then affects the magnitudes of these magnetic fields. Through the principle of magnetic field superposition, a magnetic field pointing in the second direction can be generated. In some embodiments, the second direction is the x-axis.

[0064] In some embodiments, when the generated magnetic field direction is along the x-axis, the normalized gradient of the magnetic field placed at a set point in the polarized helium-3 region is calculated using the following formula:

[0065]

[0066] Wherein, Gradient represents the magnitude of the normalized magnetic field gradient placed at a designated point in the polarized helium-3 region. B is the component of the magnetic field strength at the set point in the y-axis direction. y The magnitude of the gradient in space, B is the component of the magnetic field strength at the set point in the z-axis direction. z The magnitude of the gradient in space.

[0067]

[0068]

[0069] in, B is the component of the magnetic field strength at the set point in the y-axis direction. y The partial derivative along the x-axis, B is the component of the magnetic field strength at the set point in the y-axis direction. y The partial derivative along the y-axis, B is the component of the magnetic field strength at the set point in the z-axis direction. y Partial derivative along the z-axis; B is the component of the magnetic field strength at the set point in the z-axis direction. z The partial derivative along the x-axis, B is the component of the magnetic field strength at the set point in the z-axis direction. z The partial derivative along the y-axis, B is the component of the magnetic field strength at the set point in the z-axis direction. z Partial derivative along the z-axis.

[0070] In some embodiments, the normalized magnetic field gradient at a set point placed in the polarized helium-3 region can be calculated to be less than 10 using the above calculations. -3 / cm.

[0071] When the power module connected to the first Helmholtz coil B1 applies a counter-clockwise current to it, the first Helmholtz coil B1 generates a first magnetic field. When the power module connected to the second Helmholtz coil B2 applies a counter-clockwise current to it, the second Helmholtz coil B2 generates a second magnetic field. When the power module connected to the third Helmholtz coil B1c applies a counter-clockwise current to it, the third Helmholtz coil B1c generates a third magnetic field. When the power module connected to the fourth Helmholtz coil B2c applies a clockwise current to it, the fourth Helmholtz coil B2c generates a fourth magnetic field. At this point, the directions of the first, second, third, and fourth magnetic fields are determined. By adjusting the current to each Helmholtz coil, the magnitudes of these magnetic fields can be affected. Through the principle of magnetic field superposition, a magnetic field pointing in a third direction can be generated. In some embodiments, the third direction is the direction of the z-axis.

[0072] In some embodiments, when the generated magnetic field direction is along the z-axis, the normalized gradient of the magnetic field placed at a set point in the polarized helium-3 region is calculated using the following formula:

[0073]

[0074] Wherein, Gradient represents the magnitude of the normalized magnetic field gradient placed at a designated point in the polarized helium-3 region. B is the component of the magnetic field strength at the set point in the x-axis direction. x The magnitude of the gradient in space, B is the component of the magnetic field strength at the set point in the y-axis direction. y The magnitude of the gradient in space.

[0075]

[0076]

[0077] in, B is the component of the magnetic field strength at the set point in the x-axis direction. x The partial derivative along the x-axis, B is the component of the magnetic field strength at the set point in the x-axis direction. x The partial derivative along the y-axis, B is the component of the magnetic field strength at the set point in the x-axis direction. x Partial derivative along the z-axis; B is the component of the magnetic field strength at the set point in the y-axis direction. y The partial derivative along the x-axis, B is the component of the magnetic field strength at the set point in the y-axis direction. y The partial derivative along the y-axis, B is the component of the magnetic field strength at the set point in the z-axis direction. y Partial derivative along the z-axis.

[0078] In some embodiments, the normalized magnetic field gradient at a set point placed in the polarized helium-3 region can be calculated to be less than 10 using the above calculations. -3 / cm.

[0079] Therefore, the magnetic field system provided in this application achieves arbitrary adjustment of the magnetic field direction in three-dimensional space, and the magnetic field gradient determined by the first, second, third, and fourth magnetic fields is less than a set gradient. In some embodiments, the set gradient is 10. -3 / cm. The neutron filter of the wide-angle helium-3 neutron polarization device is placed at the center of the magnetic field generated by the superposition of four sets of Helmholtz coils, thereby achieving a highly uniform magnetic field gradient in the area where the neutron filter is placed. In addition, the magnetic field system provided in this application can also enable neutrons to pass through areas without black spots.

[0080] Please refer to Figure 6 In some embodiments, this application also provides a magnetic field control method for a wide-angle helium-3 neutron polarization device. This method employs the magnetic field system of the aforementioned wide-angle helium-3 neutron polarization device and specifically includes the following steps:

[0081] Step S100: Control the magnitude and direction of the current flowing through each Helmholtz coil to determine the direction of the magnetic field of each set of Helmholtz coils.

[0082] In this magnetic field system, by controlling the magnitude and direction of the current flowing through each Helmholtz coil, the direction of the magnetic field for each set of Helmholtz coils can be determined.

[0083] Step S200: Determine the magnetic field direction of the magnetic field system based on the magnetic field direction of each Helmholtz coil.

[0084] After determining the magnetic field direction of each Helmholtz coil, the magnetic field direction of the magnetic field system can be determined by superimposing the magnetic fields, and finally the spin direction of helium neutrons can be controlled by the magnetic field direction.

[0085] In some embodiments, with Figure 4 Clockwise, looking downwards along the positive z-axis, is considered the positive direction. Applying a counter-clockwise current to the first Helmholtz coil B1 and the second Helmholtz coil B2, and a clockwise current to the third Helmholtz coil B1c and the fourth Helmholtz coil B2c, determines the magnetic field direction of each Helmholtz coil. Adjusting the current to each coil then affects the magnitude of its magnetic field. Through the principle of magnetic field superposition, a magnetic field pointing in the first direction can be generated. In some embodiments, the first direction is the direction of the y-axis.

[0086] A counter-clockwise current is applied to the first set of Helmholtz coils B1, the second set of Helmholtz coils B2, the third set of Helmholtz coils B1c, and the fourth set of Helmholtz coils B2c. This determines the direction of the magnetic field of each Helmholtz coil. By adjusting the current magnitude of each Helmholtz coil, the magnitude of its magnetic field can be affected. Through the principle of magnetic field superposition, a magnetic field pointing in the second direction can be generated. In some embodiments, the second direction is the x-axis direction.

[0087] A counter-clockwise current is applied to the first set of Helmholtz coils B1, the second set of Helmholtz coils B2, and the third set of Helmholtz coils B1c, while a clockwise current is applied to the fourth set of Helmholtz coils B2c. This determines the magnetic field direction of each Helmholtz coil. By adjusting the current magnitude of each Helmholtz coil, the magnitude of its magnetic field can be affected. Through the principle of magnetic field superposition, a magnetic field pointing in a third direction can be generated. In some embodiments, this third direction is the direction of the z-axis.

[0088] Therefore, based on the magnetic field system provided in this application, by adjusting the magnitude and direction of the current passing through the Helmholtz coil, a magnetic field that can switch magnetic field directions in three-dimensional space can be formed, thereby maintaining the stability of the helium-3 spin direction.

[0089] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A magnetic field system for a wide-angle helium-triton polarization device, characterized in that, Including the first set of Helmholtz coils, the second set of Helmholtz coils, the third set of Helmholtz coils and the fourth set of Helmholtz coils; The first set of Helmholtz coils is fitted onto the second set of Helmholtz coils. The inner diameter of the first set of Helmholtz coils is larger than the outer diameter of the second set of Helmholtz coils. The plane in which the first set of Helmholtz coils is located intersects the plane in which the second set of Helmholtz coils is located. Furthermore, the line of intersection between the plane in which the first set of Helmholtz coils is located and the plane in which the second set of Helmholtz coils is located passes through the center of the circle in which the first set of Helmholtz coils and the second set of Helmholtz coils are located. The second set of Helmholtz coils is fitted onto the third set of Helmholtz coils, and the inner diameter of the second set of Helmholtz coils is larger than the outer diameter of the third set of Helmholtz coils; the third set of Helmholtz coils is fitted onto the fourth set of Helmholtz coils, and the inner diameter of the third set of Helmholtz coils is larger than the outer diameter of the fourth set of Helmholtz coils; the plane in which the third set of Helmholtz coils is located intersects the plane in which the fourth set of Helmholtz coils is located, and the line of intersection of the plane in which the plane in which the third set of Helmholtz coils is located and the plane in which the fourth set of Helmholtz coils is located passes through the center of the circle in which the third set of Helmholtz coils and the fourth set of Helmholtz coils are located. The plane in which the third set of Helmholtz coils is located is perpendicular to the plane in which the first set of Helmholtz coils is located; the plane in which the fourth set of Helmholtz coils is located is perpendicular to the plane in which the second set of Helmholtz coils is located. The direction of the magnetic field in the magnetic field system is determined by the magnitude and direction of the current flowing through each set of Helmholtz coils, and the direction of the magnetic field is used to maintain the spin direction of the helium-3.

2. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 1, characterized in that, It also includes a power module, Each set of Helmholtz coils is connected to an independent power module, which adjusts the magnitude and direction of the current passing through each set of Helmholtz coils.

3. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 1, characterized in that, The magnetic field direction of the magnetic field system is determined based on the magnitude and direction of the current flowing through each Helmholtz coil, including: The power module connected to the first set of Helmholtz coils applies a counterclockwise current to the first set of Helmholtz coils to generate a first magnetic field; The power module connected to the second set of Helmholtz coils applies a counterclockwise current to the second set of Helmholtz coils to generate a second magnetic field; The power module connected to the third set of Helmholtz coils applies a clockwise current to the third set of Helmholtz coils to generate a third magnetic field. The power module connected to the fourth set of Helmholtz coils applies a clockwise current to the fourth set of Helmholtz coils to generate a fourth magnetic field. Each power module adjusts the magnitude of the current applied to the first set of Helmholtz coils, the second set of Helmholtz coils, the third set of Helmholtz coils, and the fourth set of Helmholtz coils, in order to generate a magnetic field with the magnetic field direction pointing in the first direction according to the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field.

4. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 1, characterized in that, The magnetic field direction of the magnetic field system is determined based on the magnitude and direction of the current flowing through each Helmholtz coil, including: The power module connected to the first set of Helmholtz coils applies a counterclockwise current to the first set of Helmholtz coils to generate a first magnetic field; The power module connected to the second set of Helmholtz coils applies a counterclockwise current to the second set of Helmholtz coils to generate a second magnetic field; The power module connected to the third set of Helmholtz coils applies a counterclockwise current to the third set of Helmholtz coils to generate a third magnetic field. The power module connected to the fourth set of Helmholtz coils applies a counterclockwise current to the fourth set of Helmholtz coils to generate a fourth magnetic field. Each power module adjusts the magnitude of the current applied to the first set of Helmholtz coils, the second set of Helmholtz coils, the third set of Helmholtz coils, and the fourth set of Helmholtz coils, in order to generate a magnetic field pointing in the second direction based on the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field.

5. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 1, characterized in that, The magnetic field direction of the magnetic field system is determined based on the magnitude and direction of the current flowing through each Helmholtz coil, including: The power module connected to the first set of Helmholtz coils applies a counterclockwise current to the first set of Helmholtz coils to generate a first magnetic field; The power module connected to the second set of Helmholtz coils applies a counterclockwise current to the second set of Helmholtz coils to generate a second magnetic field; The power module connected to the third set of Helmholtz coils applies a counterclockwise current to the third set of Helmholtz coils to generate a third magnetic field. The power module connected to the fourth set of Helmholtz coils applies a clockwise current to the fourth set of Helmholtz coils to generate a fourth magnetic field. Each power module adjusts the magnitude of the current applied by the first, second, third, and fourth Helmholtz coils to generate a magnetic field pointing in the third direction based on the first, second, third, and fourth magnetic fields.

6. The magnetic field system of the wide-angle helium-triton polarization device as described in any one of claims 3-5, characterized in that, The magnetic field gradient determined based on the first, second, third, and fourth magnetic fields is less than the set gradient.

7. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 6, characterized in that, The gradient is set to 10. -3 / cm.

8. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 1, characterized in that, The plane containing the first set of Helmholtz coils intersects the plane containing the second set of Helmholtz coils at an angle of less than 90 degrees.

9. The magnetic field system of the wide-angle helium-triton polarization device as described in claim 1, characterized in that, The intersection angle between the plane where the third set of Helmholtz coils is located and the plane where the fourth set of Helmholtz coils is located is less than 90 degrees.

10. A magnetic field control method for a wide-angle helium-triton polarization device, characterized in that, The method employs a magnetic field system as described in any one of claims 1-9, wherein the magnitude and direction of the current flowing through each set of Helmholtz coils are controlled in the magnetic field system to determine the direction of the magnetic field; and the spin direction of helium-3 is maintained by the direction of the magnetic field.

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