CN212907119U - Helium tri-neutron polarization device - Google Patents

Abstract

The utility model relates to a neutron polarization technical field, concretely relates to three neutron polarization devices of helium, the three neutron polarization devices of helium of this application include polarization component, heating element, magnetic field subassembly and laser assembly. The laser module is used for introducing circularly polarized light into the polarization cavity and providing photons for polarization of helium triatomic atoms, so that the process of absorption of photon transition by alkali metal atoms is continuously carried out and continuous collision with the helium triatomic atoms is realized, polarization transfer is completed, polarization of the helium triatomic atoms is finally realized, and further polarization of neutrons is carried out.

Description

Helium tri-neutron polarization device

Technical Field

The utility model relates to a neutron polarization technical field, concretely relates to helium three neutron polarizing equipment.

Background

The neutrons are 1/2 spin particles with magnetic dipole moments and can therefore be polarized to produce polarized neutron beams. Polarized neutron scattering has the advantages that any other technology cannot compete on the research of magnetic materials, and the polarized neutron scattering is the only detection technology capable of indiscriminately and respectively carrying out magnetic scattering and nuclear scattering. In the mainstream neutron polarization technology at present, the polarized helium tri-neutron spin filtering device has the remarkable advantages of large receiving angle, high polarization rate, low background, wide energy spectrum, uniform polarization and analysis capability and the like, and becomes the mainstream choice for realizing neutron polarization at present. In the SEOP method in the helium tri-neutron polarization method, the polarization of helium tri is directly realized under high pressure (1-10bar), firstly, the electrons at the outermost layer of alkali metal are polarized, and then the polarization is transferred to the nuclear spin of helium tri-atoms in a spin exchange mode. Due to its advantages of being usable in a multi-wavelength range, large acceptance angle, and being usable as both a polarization inverter and a polarization analyzer, it is the polarizer most suitable for a spallation neutron source. In-situ systems in laboratories, the spin polarization of neutrons decreases with time and affects the experiments, for example, measurements of magnetic imaging require long measurement times, so that the neutron spin polarization must remain stable for several days. The in-situ system is inconvenient to transport, and the polarization degree of the in-situ system is rapidly attenuated along with the delay of time, so that a corresponding in-line polarized helium tri-neutron spin filtering system needs to be designed, and the stable polarization of neutron beams in the whole process is kept, so that the polarized neutron experiment is completed.

SUMMERY OF THE UTILITY MODEL

The utility model provides a three neutron polarization devices of helium, its aim at is to stabilize polarization to the neutron at the line.

A helium tri-neutron polarization device, comprising: the device comprises a polarization component, a heating component, a magnetic field component and a laser component;

a sealed polarization cavity is formed in the polarization assembly and is used for containing helium tri-gas and alkali metal;

the heating assembly is used for heating the polarization assembly and providing a required temperature environment for helium tri-gas polarization;

the magnetic field assembly is arranged at the periphery of the polarizing assembly and is used for forming a stable polarizing magnetic field;

the laser assembly is used for introducing circularly polarized light into the polarization cavity and providing photons for helium tri-gas polarization.

In one embodiment, the heating assembly comprises a heating cylinder and a heating pipeline, and heated gas is introduced into the heating pipeline;

or the heating assembly comprises a heating cylinder and a heating controller, wherein the heating controller is an air pipe type heating controller and is heated by air flow through a closed heating surface.

In one embodiment, the magnetic field assembly comprises an AFP coil assembly and a main magnetic field assembly;

the AFP coil assembly comprises a first cylinder and an AFP coil wound on the first cylinder, and the AFP coil is wound on the outer wall of the first cylinder along the axial direction of the first cylinder;

the main magnetic field assembly comprises a second cylinder and a main coil wound on the outer wall of the second cylinder, and the main coil is wound on the outer wall of the second cylinder along the circumferential direction.

In one embodiment, the main magnetic field assembly further comprises two secondary coils, wherein the two secondary coils are wound around the periphery of the main coil along the circumferential direction and are respectively positioned at two ends of the second cylinder.

In one embodiment, the heating cylinder further comprises a cooling water pipe, wherein the cooling water pipe is wound on the periphery of the heating cylinder;

the sapphire substrate is characterized by further comprising a circular supporting piece, sapphire sheets are arranged on the supporting piece, the supporting piece is arranged at two ends of the first cylinder, the second cylinder is sleeved outside the first cylinder, and the periphery of the supporting piece is in contact with the inner wall of the second cylinder;

the cooling water pipe is positioned between the heating cylinder and the first cylinder and used for thermally isolating the AFP coil assembly and the main magnetic field assembly.

In one embodiment, still include permalloy sleeve and encapsulation dome, permalloy sleeve suit is in main magnetic field subassembly periphery, the setting of encapsulation dome is in the telescopic both ends of permalloy, be equipped with the through-hole on the encapsulation dome, the center of through-hole, the center of sapphire piece and the axle center of heating barrel is on same light path, the polarization subassembly sets up in the cavity of heating barrel.

In one embodiment, the laser assembly comprises a laser, a lens, a polarization beam splitter, a quarter wave plate and a reflector;

the laser is used for emitting laser (795 nm for example) with fixed wavelength, and lens, polarization spectroscope and quarter wave plate set gradually on the light path are used for with the laser of fixed wavelength is separated into levogyration circular polarization light and dextrorotation circular polarization light, and makes levogyration circular polarization light and dextrorotation circular polarization light, inject into respectively from the through-hole on the encapsulation dome in the polarization intracavity, wherein the speculum is used for changing the direction of light path.

In one embodiment, the device further comprises a box body, the polarization assembly, the heating assembly and the magnetic field assembly are all arranged in the box body, a group of opposite side walls of the box body are respectively provided with a transmission part, and the center of the transmission part, the hole center of the through hole in the packaging round cover and the shaft center of the heating cylinder are all located on the same light path;

the laser device is arranged outside the box body, the lens, the polarization spectroscope and the quarter wave plate are all arranged in the box body, and the box body is further provided with a through hole for neutrons to pass through.

In one embodiment, a gas connecting pipe is arranged on the box body, an inner port of the gas connecting pipe is communicated with the heating pipeline, and an outer port of the gas connecting pipe is used for connecting a heating box;

the box body is also provided with a liquid connecting pipe, the inner port of the liquid connecting pipe is communicated with the cooling water pipe, and the outer end of the liquid connecting pipe is used for connecting a water cooler;

the box body is also provided with a BNC connector, the interior of the heating cylinder body in the box body is also provided with a temperature sensor, the temperature sensor is electrically connected with the BNC connector, and the BNC connector is used for connecting a temperature measuring instrument and a magnetic field wiring;

at least one cooling fan is further arranged in the box body.

In one embodiment, the box body is composed of a movable cover plate, a pressure plate sensor is arranged on the movable cover plate, and the pressure plate sensor is electrically connected with the controller;

a photodiode is arranged near the emitting position of the laser and is also electrically connected with the controller;

the polarization component is also provided with an FID coil and an EPR coil, wherein the FID coil is used for measuring the relative polarizability in the polarization cavity, and the EPR coil is used for measuring the absolute polarizability;

the mounting cylinder is arranged on the box body, one end of the mounting cylinder is aligned with the polarization assembly, the photodiode is arranged at the other end of the mounting cylinder, and the D2 filter is arranged in the mounting cylinder;

and the pipeline of the cooling water pipe is also provided with a flow switch, and the flow switch is also electrically connected with the controller.

The helium tri-neutron polarization device according to the embodiment comprises a polarization assembly, a heating assembly, a magnetic field assembly and a laser assembly. The laser module is used for introducing circularly polarized light into the polarization cavity and providing photons for polarization of the helium tri-gas, so that the process of photon transition absorption by alkali metal atoms is continuously carried out and continuous collision with the helium tri-atom is realized, polarization transfer is completed, polarization of the helium tri-atom is finally realized, and further polarization of neutrons is carried out.

Drawings

Fig. 1 is a schematic view of the overall structure of a polarization device according to an embodiment of the present application;

FIG. 2 is an exploded view of the heating assembly and magnetic field assembly of the polarizing device of an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a polarization device according to an embodiment of the present application;

FIG. 4 is a schematic structural diagram of a laser assembly according to an embodiment of the present disclosure;

FIG. 5 is a schematic view of a polarizer according to an embodiment of the present disclosure at a viewing angle;

FIG. 6 is a schematic structural view of a heating assembly and a cooling water pipe according to an embodiment of the present application;

FIG. 7 is a schematic structural diagram of an AFP coil assembly according to an embodiment of the present application;

FIG. 8 is a schematic structural view of a main magnetic field assembly of an embodiment of the present application;

FIG. 9 is a schematic structural diagram of an interlock control system according to an embodiment of the present application;

FIG. 10 is a flowchart illustrating operation of an interlock control system according to an embodiment of the present application;

fig. 11 is a schematic optical path diagram according to an embodiment of the present application.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.

Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.

The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning.

The helium tri-neutron polarization device of the application uses Spin-exchange optical pumping technology SEOP (Spin-exchange optical pumping), and the basic principle is that when neutrons pass through helium tri-gas polarized by laser continuous pumping, the polarized gas has about 3 orders of magnitude higher than the neutron absorption cross section parallel to helium tri-Spin to the neutron absorption cross section of Spin and helium tri-antiparallel, and the polarization of neutron beam current is realized by utilizing the characteristic.

The first embodiment is as follows:

referring to fig. 1, the present embodiment provides a helium tri-neutron polarization apparatus, which mainly includes: a polarization assembly, a heating assembly 1, a magnetic field assembly and a laser assembly.

As shown in fig. 3, the polarization assembly 1 is a sealed glass container, which is a sealed polarization cavity for containing the helium tri-gas and the alkali metal gas, the glass container is provided with an injection port for injecting the helium tri-gas and the alkali metal gas, and the glass container is also provided with an FID coil 12, and the FID coil 12 is used for measuring the relative polarizability in the glass container; the system further comprises a mounting cylinder 14, an EPR coil 13, a photodiode and a D2 filter 15, wherein the EPR coil 13 is arranged outside the glass container and used for applying a radio frequency field, the photodiode 16 is used for detecting a fluorescence signal, the D2 filter 15 is used for filtering laser light, and the method is used for measuring absolute polarizability in the glass container. The heating element sets up and is used for carrying out the even heating to polarization chamber 1 of polarization subassembly 1 around polarization subassembly 1, provides stable temperature environment for three gaseous polarizations of helium to guarantee that polarization is stable goes on. The magnetic field assembly is arranged at the periphery of the polarization assembly and is used for forming a stable magnetic field and providing a stable magnetic field environment for neutron polarization. The laser component is used for introducing circularly polarized light into the polarization cavity and providing photons for helium tri-gas polarization. So that the process of helium triatomic absorption photon transition is continuously carried out to complete stable polarization of neutrons. In order to ensure the efficient filtration of three pairs of neutrons of polarized helium, the polarization cavity has the characteristics of high temperature resistance, no magnetism, light transmission and low permeability, so that glass is required to be selected as a container of helium. The susceptibility of the polarization cavity is measured by the free decay Induction FID (free Induction Decay) technology and the electron Paramagnetic resonance EPR (Electron Paramagnetic resonance) technology of Nuclear Magnetic Resonance (NMR) method, respectively, and the relative susceptibility and the absolute susceptibility are measured by the adiabatic Fast channel AFP (adiabatic Fast passage) technology of the NMR method, respectively.

As shown in fig. 2, the heating assembly of this embodiment includes a heating cylinder 21 and a heating pipeline disposed at the periphery of the heating cylinder 21, in which the heating cylinder 21 is made of PEEK (polyetheretherketone), and heated gas is introduced into the heating pipeline to continuously heat the heating cylinder 21, so that a stable high-temperature environment is maintained in the polarization cavity, and the high-temperature environment is used for vaporizing alkali metal into steam. Then the outer layer of the heating pipeline is wrapped with glass fiber with proper thickness to achieve the effects of heat preservation and no heat dissipation.

The magnetic field assembly of the present embodiment includes an AFP coil assembly and a main magnetic field assembly, as shown in fig. 7, winding directions of coils on the AFP coil assembly and the main magnetic field assembly are perpendicular to each other, so as to provide magnetic fields perpendicular to each other to realize neutron inversion. Specifically, the AFP coil assembly includes a first barrel 31 and an AFP coil wound on the first barrel 31, wherein a plurality of spacers 32 are axially disposed on the first barrel 31, the AFP coil is wound around the spacers 32, so that the AFP coil 32 is wound on the outer wall of the first barrel 31 along the axial direction of the first barrel 31, and the AFP coil can provide a magnetic field along a first direction after being energized. Referring to fig. 8, the main magnetic field assembly includes a second cylinder 41 and a main coil 42 wound around the outer wall of the second cylinder 41, wherein the main coil 42 is wound around the outer wall of the second cylinder 41 along a circumferential direction, so that when the main coil 42 is energized, a magnetic field is formed along a second direction, and the first direction is perpendicular to the second direction, i.e., two magnetic fields perpendicular to each other are formed.

Further, for the purpose of uniformity of the magnetic field formed along the second direction, the main magnetic field assembly of the present embodiment further includes two sub-coils 43, and the two sub-coils 43 are wound around the periphery of the main coil 42 along the circumferential direction and are respectively located at two ends of the second cylinder 41.

The primary field in the magnetic field is used to define the direction of polarization and the secondary coil 43 is used to apply a weak transverse field pulse, and then the helium-III polarizability is calculated by the measurement system. The main magnetic field has to be satisfied

The relaxation time can be guaranteed to be sufficiently long. In the experiment, a uniform main magnetic field is provided for a polarization system by using a magnetic field coil in the magnetic shielding shell, and the uniformity of the magnetic field is ensured by adding secondary coils 43 at two sides of the main coil.

During operation, need with the magnetic field subassembly suit on heating element to provide even magnetic field, in order to avoid the heat that heating element produced to the harm of permalloy, influence its magnetic screen nature, as figure 6, still be equipped with condenser tube 22 in this embodiment, condenser tube 22 coiling is in heating pipeline's periphery, and condenser tube 22 adopts the Teflon material to make. Specifically, a cavity with a gap is formed between the heating pipeline and the cooling water pipe 22, that is, the cooling water pipe 22 is ensured not to be in direct contact with the heating pipeline, so that the influence on the heating efficiency is avoided.

In order to avoid too fast heat dissipation, sapphire plates are further provided at both ends of the first cylinder 31 in this embodiment. The sapphire sheet 62 is relatively thin, so that the sapphire sheet 62 is fixed and plays a supporting role through the circular support 61, the sapphire sheet 62 is arranged at the center of the support, the support 62 is fixed at two ends of the first cylinder 31 through screws, the second cylinder 41 is sleeved outside the first cylinder 31, and the periphery of the support 62 is in contact with the inner wall of the second cylinder 41. The cooling water pipe 22 is located between the heating cylinder 21 and the first cylinder 31, and plays a role of magnetic shielding for the AFP coil assembly, the main magnetic field assembly and the permalloy. The sapphire sheet 62 can ensure that neutrons and laser pass through, and the sapphire sheet 62 is additionally arranged in the through hole of the circular support 62 and is used for light transmission, heat preservation, high neutron transmittance and background reduction.

In order to shield an external magnetic field, the device of the embodiment further comprises a permalloy sleeve 53 and a packaging circular cover 51, the permalloy sleeve 53 is sleeved on the periphery of the main magnetic field component, namely sleeved on the outer wall of the main coil 42, the packaging circular cover 51 is arranged at two ends of the permalloy sleeve 53, a through hole 52 is formed in the packaging circular cover 51 and used for allowing laser and neutrons to pass through, the center of the through hole 52, the center of the sapphire sheet 62 and the axis of a cylindrical cavity inside the heating cylinder 21 are all located on the same optical path, and the polarization component is arranged in the cavity of the heating cylinder 21. Because various ferromagnetic objects are more on the neutron spectrometer line, the magnetic field environment on the spectrometer is more complex than that in a laboratory, and the depolarization time is shortened. The permalloy sleeve 53 made of the magnetic shielding material with high magnetic permeability designed in the embodiment can shield the complex electromagnetic environment on the spectrometer.

Referring to fig. 4, the laser assembly of the present embodiment includes a laser 8, a lens 81, a polarization beam splitter 82, a quarter wave plate 84, and a plurality of mirrors 83. As shown in fig. 11, the laser 8 is used for emitting laser light with a fixed wavelength, and the lens, the polarization beam splitter 82 and the quarter wave plate 84 are sequentially disposed on the laser light path, and a plurality of mirrors 83 are further disposed on the light path. The laser beam emitted from the laser 8 is a laser with a fixed wavelength (e.g. 795nm), is transmitted through an optical fiber and then shaped into parallel light by a lens, and then the separation of the linearly polarized P light along the vertical direction and the linearly polarized S light along the horizontal direction is realized by using a polarization beam splitter (also called a polarized beam splitter) 82; the separated linearly polarized light is changed into circularly polarized light through a Quarter Wave Plate (QWP)84 respectively, wherein P light is changed into right circularly polarized light, S light is changed into left circularly polarized light, and then the light beam path is adjusted to be on the same horizontal line with the polarization cavity through a reflecting mirror 83 made of a coated silicon wafer material, so that the light in two different directions irradiates into the polarization cavity along symmetrical paths. The laser assembly will be continuously turned on while undergoing neutron spin filtering, so that the process of absorption of photon transitions by the alkali metal atoms continues.

Further, the device of the embodiment further includes a box 7, the polarization assembly, the heating assembly and the magnetic field assembly are all disposed in the box 7, a neutron transmission part is disposed on each of a set of opposite side walls of the box 7, the transmission part is a silicon wafer 71, and the center of the silicon wafer 71, the center of the through hole 52 in the sealing dome 51, the center of the heating cylinder 21 and the center of the sapphire sheet 62 are all on the same optical path.

The laser 8 of this embodiment is disposed outside the bottom of the case 7, the lens, the polarization beam splitter 82, the reflector 83 and the quarter wave plate 84 are all disposed inside the case 7, and the bottom of the case 7 is further provided with a through hole for the laser to pass through.

As shown in fig. 5, the housing 7 of the present embodiment is provided with a gas connecting pipe 74, an inner port of the gas connecting pipe 74 is communicated with the heating duct, an outer port is used for connecting the heating box 73, and the heating box 73 is used for generating a heating air flow. Still be equipped with liquid connecting pipe 75 on the box 7, the internal port and the condenser tube 22 intercommunication of liquid connecting pipe 75, the outer end is used for connecting the water-cooling machine for provide recirculated cooling water, carry out thermal insulation. The box body 7 is further provided with a BNC joint 76, the inside of the heating cylinder 21 in the box body 7 or the outer wall of the polarization assembly is further provided with a temperature sensor 11, such as a thermocouple, the temperature sensor 11 is electrically connected with the BNC joint 76, and the BNC joint is used for being connected with a temperature measuring instrument to measure the temperature information in the polarization assembly 1 in real time so as to monitor the temperature. Four corners of the inner wall of the upper cover of the box body 7 are respectively provided with a heat radiation fan 72 for radiating heat in the box body 7.

The box 7 of this embodiment is composed of a removable cover plate, which is mounted on an aluminum alloy frame, the removable cover plate is made of aluminum plate, and the bottom of the frame is a bread board for fixing the optical element, the polarization assembly 1, the heating assembly, the magnetic field assembly and the laser assembly. The wiring is connected to the measuring instrument through a BNC connector 76 on the aluminum plate, and the air pipe and the water pipe are connected to a gas connecting pipe 74 and a liquid connecting pipe 75 on the aluminum plate through a water hole and a gas hole on the aluminum plate, respectively. Mounting holes for mounting the N-type silicon wafer 71 are reserved in the two plates corresponding to the transmission neutrons so as to filter external impurity light and prevent internal laser leakage, and a fan 72 is designed to dissipate heat of an online system so as to prevent the system from being overheated.

The on-line system not only ensures the safety of workers, but also ensures the long-term safe operation of the system, so a safety interlocking control device must be added to the system. When an accident occurs, the laser interlocking control system can quickly and reliably make corresponding actions to avoid damage to personnel and machine equipment, and the embodiment is further provided with the laser interlocking system, as shown in fig. 9, wherein the laser interlocking system comprises a controller. The movable cover plate 7 is provided with a pressure plate sensor which is electrically connected with the controller; when the laser device runs, the box body is closed, the tightness of the laser device is kept, and when the laser device stops, the movable cover plate can be opened for overhauling and maintenance. To prevent the flap from being opened during operation of the laser 8, or to activate the laser 8 when the flap is not in place, as shown in fig. 10, a pressure plate sensor is provided on all flaps, and the laser will not turn on or turn off automatically as long as any flap is not in place.

The emitting part of the laser 8 is also provided with a photodiode which is also connected with the controller; the photodiode is used to detect the laser light and the laser 8 will be stopped as soon as the photodiode detects a laser light leak. The pipeline of the cooling water pipe is also provided with a flow switch, and the flow switch is also connected with the controller. Laser 8 can produce a large amount of heats at the during operation, for preventing that the laser is too warm to lead to damaging, need to walk the heat that laser 8 produced through the cooling water. Therefore, a flow switch is arranged on the cooling water pipeline, the flow switch can detect the cooling water flow in real time, and once the cooling water flow is lower than a threshold value or the flow switch is closed, the system can immediately turn off the laser 8.

When the system is powered off, the power switch is automatically switched to the off state, so that the laser is still in the off state when the power is supplied again. The mode of the laser interlock control system requires the operator to switch between "commissioning mode" and "run mode" using a security key. When the safety key is in the debugging mode, the control system enters the debugging mode, and the interlocking control system is closed at the moment. When the safety key is in the running state, the system enters the interlocking state, and the interlocking control system is started at the moment.

It is right to have used specific individual example above the utility model discloses expound, only be used for helping to understand the utility model discloses, not be used for the restriction the utility model discloses. To the technical field of the utility model technical personnel, the foundation the utility model discloses an idea can also be made a plurality of simple deductions, warp or replacement.

Claims (10)

1. A helium tri-neutron polarization device, comprising: the device comprises a polarization component, a heating component, a magnetic field component and a laser component;

a sealed polarization cavity is formed in the polarization assembly and is used for containing helium tri-gas and alkali metal gas;

the heating assembly is used for heating the polarization assembly and providing a required temperature environment for helium tri-gas polarization;

the magnetic field assembly is arranged at the periphery of the polarizing assembly and is used for forming a stable polarizing magnetic field;

the laser assembly is used for introducing circularly polarized light into the polarization cavity and providing photons for helium tri-gas polarization.

2. The helium tri-neutron polarization device of claim 1, wherein the heating assembly comprises a heating cylinder and a heating pipe, and heated gas is introduced into the heating pipe.

3. The helium tri-neutron polarization device of claim 2, wherein the magnetic field assembly comprises an AFP coil assembly and a main magnetic field assembly;

the AFP coil assembly comprises a first cylinder and an AFP coil wound on the first cylinder, and the AFP coil is wound on the outer wall of the first cylinder along the axial direction of the first cylinder;

the main magnetic field assembly comprises a second cylinder and a main coil wound on the outer wall of the second cylinder, and the main coil is wound on the outer wall of the second cylinder along the circumferential direction.

4. The helium tri-neutron polarization device of claim 3, wherein the main magnetic field assembly further comprises two secondary coils, wherein the two secondary coils are wound around the periphery of the main coil along the circumferential direction and are respectively located at two ends of the second cylinder.

5. The helium tri-neutron polarization device of claim 3, further comprising a cooling water pipe, wherein the cooling water pipe is wound around the periphery of the heating cylinder;

the sapphire substrate is characterized by further comprising a circular supporting piece, sapphire sheets are arranged on the supporting piece, the supporting piece is arranged at two ends of the first cylinder, the second cylinder is sleeved outside the first cylinder, and the periphery of the supporting piece is in contact with the inner wall of the second cylinder;

the cooling water pipe is positioned between the heating cylinder and the first cylinder and used for thermally isolating the AFP coil assembly and the main magnetic field assembly.

6. The helium tri-neutron polarization device of claim 5, further comprising a permalloy sleeve and a packaging dome, wherein the permalloy sleeve is sleeved on the periphery of the main magnetic field component, the packaging dome is arranged at two ends of the permalloy sleeve, a through hole is formed in the packaging dome, the center of the through hole, the center of the sapphire sheet and the axis of the heating cylinder are in the same optical path, and the polarization component is arranged in a cavity of the heating cylinder.

7. The helium tri-neutron polarization device of claim 6, wherein the laser assembly comprises a laser, a lens, a polarization beam splitter, and a quarter wave plate;

the laser is used for emitting laser with fixed wavelength, and the lens, the polarization spectroscope and the quarter-wave plate are sequentially arranged on a light path of the laser and are used for separating the laser with the fixed wavelength into left-handed circularly polarized light and right-handed circularly polarized light, and the left-handed circularly polarized light and the right-handed circularly polarized light are made to be respectively emitted into the polarization cavity from the through holes in the packaging round cover.

8. The helium tri-neutron polarization device according to claim 7, further comprising a box, wherein the polarization assembly, the heating assembly and the magnetic field assembly are all disposed in the box, a set of opposite side walls of the box are respectively provided with a transmission part, and the center of the transmission part, the hole center of the through hole on the packaging dome and the shaft center of the heating cylinder are all on the same optical path; the box body is also provided with a through hole for laser to pass through.

9. The helium tri-neutron polarization device of claim 8, wherein a gas connection pipe is arranged on the box body, an inner port of the gas connection pipe is communicated with the heating pipeline, and an outer port of the gas connection pipe is used for connecting a heating box;

the box body is also provided with a liquid connecting pipe, the inner port of the liquid connecting pipe is communicated with the cooling water pipe, and the outer end of the liquid connecting pipe is used for connecting a water cooler;

the box body is also provided with a BNC joint, the interior of the heating cylinder body in the box body is also provided with a temperature sensor, the temperature sensor is electrically connected with the BNC joint, and the BNC joint is used for connecting a thermodetector;

at least one cooling fan is further arranged in the box body.

10. The helium tri-neutron polarization device of claim 9, wherein the box body is composed of a removable cover plate, a pressure plate sensor is arranged on the removable cover plate, and the pressure plate sensor is electrically connected with the controller;

the emitting part of the laser is also provided with a photodiode, and the photodiode is also electrically connected with the controller;

the polarization component is also provided with an FID coil and an EPR coil, wherein the FID coil is used for measuring the relative polarizability in the polarization cavity, and the EPR coil is used for measuring the absolute polarizability;

the mounting cylinder is arranged on the box body, one end of the mounting cylinder is aligned with the polarization assembly, the photodiode is arranged at the other end of the mounting cylinder, and the D2 filter is arranged in the mounting cylinder;

and the pipeline of the cooling water pipe is also provided with a flow switch, and the flow switch is also electrically connected with the controller.

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