A neutron transmission experiment device with adjustable supporting plate and cold shield

Abstract

The utility model discloses a kind of adjustable backing plate and neutron transmission rate experimental device with cold screen, including the experimental cavity of two ends opening, front and rear sealing flange being set to its front and rear, refrigeration system, temperature control system and cold screen, adjustable bracket fixed backing plate is equipped in experimental cavity, to adapt to the installation demand of different size sample, its height can be flexibly adjusted;Refrigeration system uses GM refrigerator as cold source, temperature control system can realize accurate temperature control in 20~300K range, minimum temperature is better than 20K, temperature control accuracy reaches ±0.1K;Cold screen uses high reflectivity metal material, effectively insulates thermal radiation;Experimental cavity side is equipped with beam window, reduces neutron loss, solve the problem that traditional equipment is caused by cavity narrow and leads to sample adaptability poor, meet the neutron transmission rate experimental demand of large size sample under low temperature condition, with temperature control accurate, wide applicability and experimental efficiency high advantage.

Description

Technical Field

[0001] This utility model relates to the field of neutron transmittance experiments, specifically to a neutron transmittance experimental device equipped with an adjustable support plate and a cold screen. Background Technology

[0002] In the field of neutron transmittance experiments, neutron transmittance testing is a key method for studying the neutron scattering characteristics of materials, their internal structure, and dynamic processes. However, traditional neutron transmittance experimental setups have many significant limitations in terms of sample environment control.

[0003] Most existing experimental equipment is designed for room temperature or small-sized samples, making it difficult to meet the experimental requirements of large-sized samples in low-temperature environments. Specifically, the experimental equipment in current neutron experiment beamlines designed for low-temperature environments generally suffers from the following problems: Sample size limitation: The experimental chamber is designed to be relatively small, only able to accommodate samples of limited size. In practical applications, many working conditions involve samples of larger size, which traditional equipment cannot test. This greatly limits the representativeness and application scope of the experimental results, making it difficult to directly apply the experimental findings to actual production or scientific research scenarios.

[0004] Insufficient temperature control precision: When the experimental temperature is below the liquid nitrogen temperature range, the cooling process of existing equipment is complex and the temperature control precision is low. In low-temperature environments, even small temperature fluctuations can have a significant impact on experimental results, and traditional equipment struggles to achieve stable and precise low-temperature loading, resulting in a significant reduction in the reliability of experimental data and failing to provide accurate and effective evidence for scientific research.

[0005] Poor experimental flexibility: The equipment interface design is fixed and has weak adaptability, only allowing installation on specific types of neutron beamlines. This means that if a change of experimental platform is required in different experimental scenarios, the equipment cannot be quickly adjusted or ported, requiring the customization of dedicated interfaces. This not only increases experimental costs and time but also leads to low experimental efficiency, hindering the smooth progress of scientific research.

[0006] Limited functionality: Most devices only support experiments at room temperature or a single temperature point, and cannot achieve continuous adjustment within a controlled temperature range. Many scientific research projects require studying the correlation between sample temperature field distribution and transmittance under multiple operating conditions. Traditional equipment cannot meet this need, limiting the depth and breadth of scientific research.

[0007] Therefore, developing a neutron transmittance experimental device that can overcome the above-mentioned technical bottlenecks is of great practical significance. Summary of the Invention

[0008] To address the aforementioned issues, this invention aims to provide a neutron transmittance experimental device with an adjustable support plate and a cold screen, suitable for conducting neutron transmittance experiments on large-size samples in a vacuum and low-temperature environment. This device meets the correlation detection requirements of temperature field distribution and transmittance of large-size samples under actual working conditions and can be applied to research in multiple fields such as neutron scattering experiments.

[0009] The technical solution adopted in this invention includes: The experimental chamber is a hollow structure with openings at both ends. Inside, there is an adjustable height tray for placing samples. The tray is fixed inside the experimental chamber by an adjustable height bracket to accommodate the experimental needs of samples of different sizes. Front and rear sealing flanges are respectively located at the front and rear openings of the experimental chamber, and are connected by bolts to achieve quick disassembly and sealing. The refrigeration system uses a GM refrigerator as the cold source and is connected to the experimental chamber through pipes to force cooling of the interior of the experimental chamber. The temperature control system, including a temperature controller and a program control module, is connected to a temperature sensor inside the experimental chamber to monitor and precisely adjust the temperature inside the experimental chamber in real time. The cold screen, including the cold screen side plate and the cold screen bending plate, is set inside the experimental chamber and surrounds the sample area. It is made of a high reflectivity metal material and can effectively isolate the influence of external radiation on the stability of the temperature field inside the experimental chamber. A beam window, located on one side of the experimental cavity, is used for the passage of a neutron beam; Furthermore, the experimental chamber is made of stainless steel, and its inner surface is polished to reduce neutron scattering and gas adsorption; the connecting pipe is equipped with a vacuum isolation valve to maintain the vacuum state of the experimental chamber when maintaining or replacing the refrigeration system.

[0010] Furthermore, the contact surface between the sealing flange and the experimental chamber is provided with a sealing ring made of low-temperature resistant rubber to ensure the sealing performance of the device in a deep low-temperature environment.

[0011] Furthermore, the tray is made of a material with good thermal conductivity and has a sample fixing device on its surface to ensure the stability of the sample during the experiment; the tray's support is also equipped with a fine-tuning mechanism to precisely adjust the position and angle of the sample, ensuring that the neutron beam can accurately irradiate the target area of ​​the sample.

[0012] Furthermore, the beam window is made of a material with high neutron transmittance and low scattering cross section. The window shape is circular or rectangular, and the window thickness is 0.5 mm with a thin wall design to minimize neutron loss and increase the neutron flux reaching the sample.

[0013] Furthermore, the temperature control system has a temperature range of 20~300 K, and the minimum sample loading temperature is better than 20 K.

[0014] Furthermore, it also includes a vacuum pumping system connected to the experimental chamber, used to evacuate the inside of the experimental chamber to below 10 Pa before the experiment; the vacuum pumping system is equipped with a vacuum gauge, which can display and monitor the vacuum level inside the chamber in real time.

[0015] Furthermore, it is equipped with a temperature sensor and a heating block, which can monitor and control the temperature nodes in real time. The device, together with a neutron monitor, can collect neutron transmittance data during the experiment at different temperature points, and can be connected to a computer for subsequent data analysis and processing.

[0016] Furthermore, the experimental apparatus is designed to be suitable for various neutron beamlines. By adjusting the size of the experimental cavity, the interface design, and the position and shape of the beam window, it can be quickly adapted to different neutron scattering experimental platforms.

[0017] Furthermore, the structure of the cold screen uses a high reflectivity metal with a reflectivity of ≥95%, which can effectively isolate the influence of external radiation on the stability of the internal temperature field of the experimental chamber.

[0018] This utility model provides a neutron transmittance experimental device with an adjustable support plate and a cold screen. Through structural innovation and functional integration, it significantly improves the technical level and application scope of neutron experiments. The specific beneficial effects are as follows: The experimental chamber of this invention adopts a hollow, adjustable structure, coupled with an adjustable-height tray support, which can support the loading and testing of large-sized samples (such as blocks / films with a diameter or side length exceeding 300 mm). This design solves the problem of poor sample adaptability caused by the small chamber size of traditional equipment, making the experimental results closer to actual working conditions and providing more valuable data for scientific research and practical applications.

[0019] This invention uses a GM refrigerator as the cold source, combined with a temperature controller and programmable control module, to continuously adjust the temperature within the range of 20~300K, with a minimum sample loading temperature better than 20K and a temperature control accuracy of ±0.1K. Compared to traditional liquid nitrogen cooling methods, this device does not require frequent refrigerant replenishment, significantly improving temperature stability. It is particularly suitable for temperature-sensitive experimental scenarios such as low-temperature phase transitions and superconducting materials, providing reliable temperature control for scientific research in these fields.

[0020] Improving experimental efficiency and flexibility: The front and rear sealing flanges can be quickly disassembled and assembled with bolts, and the modular interface design allows the device to be adapted to different models of neutron beam station sample stages without the need for customized interfaces. The time required to evacuate to below 10 Pa before the experiment is reduced to within 30 minutes, and the alignment error between the beam window and the neutron beam during belt-driven experiments is ≤0.2mm. This significantly reduces equipment setup time, improves experimental efficiency, and enables researchers to conduct experiments more quickly.

[0021] Enhancing data reliability: The cold shield material (high-reflectivity metal) effectively isolates external thermal radiation. Combined with the thermally conductive material of the support plate and the fine-tuning mechanism, it ensures that the sample temperature uniformity is ≤1K / cm. The beam window has a thin wall thickness of 0.5mm, which further increases the neutron flux. These designs reduce the interference of external factors on the experiment, ensuring the accuracy and reliability of the experimental data and providing high-quality data support for scientific research analysis.

[0022] Expanding experimental capabilities and application scenarios: This device supports both offline (sample pre-cooling) and belt-based (online testing) modes, covering neutron scattering needs in fields such as materials science, condensed matter physics, and biomacromolecules. For example, in the research of lithium-ion battery cathode materials, it can achieve in-situ observation of the structural evolution of electrode materials within the range of -50℃ to room temperature, providing key data support for the development of new energy materials and expanding the application scope of neutron experiments.

[0023] In this invention, the GM refrigerator has a lifespan exceeding 20,000 hours, extending the maintenance cycle to once a year, reducing annual operating costs by more than 60% compared to liquid helium circulation systems. The vacuum isolation valve design allows for refrigeration system replacement without shutting down the system, further improving equipment availability, reducing the impact of equipment maintenance on experimental progress, and lowering operating costs. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a side view of the structure of the present invention; Figure 3 yes Figure 2 A schematic diagram of the cross-sectional structure along the AA direction.

[0025] Figure labeling: 1. Experimental chamber; 2. Refrigeration system; 3. Front and rear sealing flanges; 4. Beam window; 5. Connecting aluminum plate; 6. Cold screen bending plate; 7. Cold screen side plate; 8. Vacuum sealing connector; 9. Filter parts; 10. Filter support plate; 11. Base support; 12. Base; 13. Temperature-conducting copper head. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-3The specific embodiments of the present invention will be described in detail below. Figure 1 A schematic diagram of the overall structure of the present invention is shown. Figure 2 This is a schematic diagram of the side view structure. Figure 3 for Figure 2 A schematic diagram of the cross-sectional structure along the AA direction.

[0027] I. Overall Structure of the Device This neutron transmittance experimental apparatus, equipped with an adjustable support plate and a cold shield, mainly consists of an experimental chamber 1, a cooling system 2, front and rear sealing flanges 3, a cold shield assembly, a beam window 4, a support plate assembly, a temperature control system, and a vacuum pumping system.

[0028] II. Structure and Function of Each Component In this invention, the experimental chamber 1 is a hollow cylindrical structure open at both ends, made of 316L stainless steel. Its internal surface is polished to effectively reduce neutron scattering and gas adsorption. The chamber wall thickness is 10mm, the internal diameter is 500mm, and the length is 800mm. O-ring sealing grooves are machined on the flange faces at both ends of the chamber, achieving vacuum sealing through the front and rear sealing flanges 3. A beam window 4, 200mm in diameter, is opened on the side wall of the chamber, made of single-crystal silicon with a nickel-plated surface to reduce neutron scattering. The bottom of the chamber is connected to the base 12 via an MB threaded seat. The base 12 is equipped with a horizontal adjustment mechanism to ensure that the experimental chamber 1 is perpendicular to the neutron beam.

[0029] In this invention, the refrigeration system 2 uses a GM refrigerator as the cold source, with a cooling capacity of 2W@20K. The refrigeration system 2 is thermally connected to the top of the experimental chamber 1 via a connecting aluminum plate 5, used for forced cooling of the interior of the experimental chamber 1. A vacuum isolation valve is provided on the connecting pipe; when maintenance or replacement of the refrigeration system 2 is required, this valve can be closed to maintain the vacuum state of the experimental chamber 1.

[0030] In this invention, the front and rear sealing flanges 3 are made of aluminum alloy with a thickness of 30mm, and are respectively located at the front and rear openings of the experimental chamber 1, and connected to the experimental chamber 1 by 12 M12 bolts. A sealing ring made of low-temperature resistant rubber (fluororubber, temperature range -50℃ to 200℃) is provided on the contact surface between the sealing flanges and the experimental chamber 1 to ensure the sealing performance of the device in deep cryogenic environments. A sample loading hole with a diameter of 250mm is opened in the center of the front flange, and a vacuum-sealed insert 8 is configured to introduce the temperature sensor and heating block.

[0031] In this invention, a cold shield is placed inside the experimental chamber 1 and surrounds the sample area, using a high-reflectivity metal material. It consists of a cold shield bending plate 6 and a cold shield side plate 7, employing a 0.5mm thick aluminum foil structure (made of a high-reflectivity metal material). The cold shield bending plate 6 surrounds the support plate assembly, and the cold shield side plate 7 covers the side wall of the experimental chamber 1, forming a closed thermal shielding space that effectively isolates the influence of external thermal radiation on the stability of the internal temperature field of the experimental chamber 1.

[0032] The tray assembly of this invention includes a filter tray 10 and a sample tray, both made of copper with a thickness of 5 mm. The filter tray 10 is fixed to the bottom of the experimental chamber 1 by a base support 11 and is used to hold the neutron filter. The sample tray is mounted above the filter tray 10 via a guide rail and can be finely adjusted (±5 mm) along the neutron beam direction. The tray is made of a material with good thermal conductivity and has sample fixing devices, such as T-slots, on its surface. Combined with a special clamp, this ensures the stability of the sample during the experiment. The tray's support also has a fine-tuning mechanism for precisely adjusting the position and angle of the sample, ensuring that the neutron beam accurately irradiates the target area of ​​the sample.

[0033] In this invention, the beam window 4 is located on one side of the experimental cavity 1 and is made of single-crystal silicon material with high neutron transmittance and low scattering cross section. The window is circular in shape (or rectangular according to actual needs) and has a thin wall design with a thickness of 0.5 mm to minimize neutron loss and increase the neutron flux reaching the sample.

[0034] The temperature control system in this invention consists of an M36i temperature controller, a diode resistance temperature sensor, and a heating block. The temperature sensor is embedded in the sample tray, and the heating block is attached to the back of the tray, connected to an external controller via a vacuum-sealed connector 8. The temperature controller supports PID regulation, with a temperature control range of 20-300K, and a minimum sample loading temperature better than 20K. The temperature control accuracy reaches ±0.1K, enabling real-time monitoring and precise adjustment of the internal temperature of the experimental chamber 1.

[0035] In this invention, the vacuum pumping system is connected to the experimental chamber 1 and is used to evacuate the interior of the experimental chamber 1 to below 10 Pa before the experiment. The vacuum pumping system is equipped with a vacuum gauge, which can display and monitor the vacuum level inside the chamber in real time.

[0036] III. Experimental Operation Procedure Offline Experiment Mode: Open the front flange, fix the sample to the tray assembly, and connect the temperature sensor and heating wire.

[0037] Close the front and rear sealing flanges 3, start the vacuum pumping system, and use the vacuum pump to pump the pressure inside the cavity to below 10Pa. At the same time, the vacuum gauge displays and monitors the vacuum level inside the cavity in real time.

[0038] Start the cooling system 2 and cool down to the target temperature (adjustable from 20K to 300K) at an appropriate rate (e.g., 5K / min) according to the experimental requirements.

[0039] Once the set temperature is reached, it is maintained at a stable temperature for 2 hours. During this period, the temperature can be monitored and adjusted in real time via a temperature control system. Simultaneously, the device, in conjunction with a neutron monitor, can collect neutron transmittance data at different temperature points during the experiment, and can be connected to a computer for subsequent data analysis and processing.

[0040] Belt-based experimental mode: The entire device was hoisted to the neutron beam station sample stage, and the base 12 was adjusted so that the center of the beam window 4 coincided with the neutron beam (error ≤ 0.2 mm).

[0041] Repeat the offline mode vacuuming and cooling steps, that is, after closing the front and rear sealing flanges 3, vacuum to the specified pressure, start the refrigeration system 2 to cool down to the target temperature and maintain stability.

[0042] The neutron source was activated, and neutron transmittance and temperature data were collected simultaneously and transmitted to a computer for analysis via a data acquisition card. During the experiment, the temperature control system monitored and adjusted the temperature nodes in real time to ensure that the experiment was carried out accurately under the set temperature conditions.

[0043] Example: Low-Temperature Neutron Scattering Experiment of Lithium-ion Battery Cathode Material This embodiment aims to study the structural evolution of lithium-ion battery cathode material (LiCoO2) in the range of -50℃ to room temperature, and to verify the device's ability to measure the low-temperature neutron transmittance of large-sized samples (200mm diameter discs).

[0044] In this embodiment, the experimental chamber 1 is made of 316L stainless steel, with an inner diameter of 500mm and a length of 800mm. Both ends are sealed by front and rear sealing flanges 3. A sample loading hole (diameter 250mm) is opened in the center of the front flange, and a vacuum-sealed connector 8 is configured to introduce a temperature sensor (PT100).

[0045] In this embodiment, the GM refrigerator 2 of the refrigeration system is thermally connected to the top of the experimental chamber 1 via a connecting aluminum plate 5, with a cooling capacity of 80W@20K. One end of the heat-conducting copper head 13 is fixed to the bottom of the sample tray, and the other end is inserted into the cold head of the refrigeration system 2 to achieve efficient heat conduction between the sample and the cold source.

[0046] Cold screen assembly: It consists of a cold screen bending plate 6 and a cold screen side plate 7, and adopts a 0.05mm thick aluminum foil structure (a high reflectivity metal material) to wrap the sample area to reduce thermal radiation interference.

[0047] In this embodiment, the filter tray 10 is fixed to the bottom of the experimental chamber 1 by the base support 11, and the sample tray is finely adjusted (±1mm) along the neutron beam direction. The LiCoO2 sample (200mm in diameter and 5mm in thickness) is fixed to the surface of the tray by a special clamp.

[0048] In this embodiment, the beam window 4 is a suitably designed monocrystalline silicon window.

[0049] In this embodiment, the temperature control system consists of an M36i temperature controller, a diode resistance temperature sensor, and a heating block. The temperature sensor is embedded in the sample tray, and the heating block is attached to the back of the tray, connected to an external controller via a vacuum-sealed connector 8. The temperature controller supports PID regulation, with a temperature control range of 20K - 300K and a temperature control accuracy of ±0.1K.

[0050] Experimental steps: Open the front flange, fix the LiCoO2 sample to the tray assembly, and connect the temperature sensor and heating wire.

[0051] Close the front and rear sealing flanges 3, and use a vacuum pump to pump the pressure inside the cavity to 8 Pa.

[0052] Start the cooling system 2 and cool down to -50℃ (223K) at a rate of 5K / min, and maintain the temperature stable for 2 hours.

[0053] Turn on the neutron source and simultaneously collect neutron transmittance and temperature data, recording once every 10K interval, until room temperature (293K).

[0054] After the experiment, the neutron source was turned off, the sample was heated to room temperature using a heating film, and the front flange was opened to remove the sample.

[0055] Experimental results: The neutron diffraction pattern of LiCoO2 in the range of -50℃ to room temperature was successfully obtained, which verified the device's ability to control the low temperature of large-sized samples (temperature uniformity ≤0.8K / cm).

[0056] This embodiment presents a neutron transmittance experimental device with an adjustable support plate and a cold screen, suitable for conducting neutron transmittance experiments on samples of different sizes under vacuum and low temperature conditions. It can meet the correlation detection requirements of temperature field distribution and transmittance of samples under actual working conditions, and is also suitable for neutron scattering experiments, providing an efficient, accurate, and highly applicable experimental device for neutron experimental techniques. The above embodiment further demonstrates that this device, through modular design and precise temperature control technology, achieves efficient neutron scattering measurement of large / small samples under vacuum and low temperature conditions, applicable to research in materials science, life sciences, and other fields.

Claims

1. A neutron transmittance experimental apparatus equipped with an adjustable support plate and a cold screen, characterized in that, include: The experimental chamber is a hollow structure with openings at both ends. Inside, there is an adjustable height tray for placing samples. The tray is fixed inside the experimental chamber by an adjustable height bracket to accommodate the experimental needs of samples of different sizes. Front and rear sealing flanges are respectively located at the front and rear openings of the experimental chamber, and are connected by bolts to achieve quick disassembly and sealing. The refrigeration system uses a GM refrigerator as the cold source and is connected to the experimental chamber through pipes to force cooling of the interior of the experimental chamber. The temperature control system, including a temperature controller and a program control module, is connected to a temperature sensor inside the experimental chamber to monitor and precisely adjust the temperature inside the experimental chamber in real time. The cold screen, including the cold screen side plate and the cold screen bending plate, is set inside the experimental chamber and surrounds the sample area. It is made of a high-reflectivity metal material. The beam window, located on one side of the experimental cavity, is used for the passage of the neutron beam.

2. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, The experimental chamber is made of stainless steel, and its inner surface is polished to reduce neutron scattering and gas adsorption. The connecting pipe is equipped with a vacuum isolation valve to maintain the vacuum state of the experimental chamber when maintaining or replacing the refrigeration system.

3. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, The contact surface between the sealing flange and the experimental chamber is equipped with a sealing ring made of low-temperature resistant rubber to ensure the sealing performance of the device in deep low-temperature environments.

4. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, The tray is made of a material with good thermal conductivity and has a sample fixing device on its surface to ensure the stability of the sample during the experiment.

5. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 4, characterized in that, The support of the tray is also equipped with a fine-tuning mechanism to precisely adjust the position and angle of the sample, ensuring that the neutron beam can accurately irradiate the target area of ​​the sample.

6. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, The beam window is made of a material with high neutron transmittance and low scattering cross section. The window shape is circular or rectangular, and the window thickness is 0.5 mm with a thin wall design to minimize neutron loss and increase the neutron flux reaching the sample.

7. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, It also includes a vacuum pumping system connected to the experimental chamber, which is used to evacuate the inside of the experimental chamber to below 10 Pa before the experiment; the vacuum pumping system is equipped with a vacuum gauge, which can display and monitor the vacuum level inside the chamber in real time.

8. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, It is also equipped with a temperature sensor and a heating block, which can monitor and control the temperature nodes in real time. The device, together with a neutron monitor, can collect neutron transmittance data during the experiment at different temperature points, and can be connected to a computer for subsequent data analysis and processing.

9. The neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, The experimental setup is designed to be suitable for a variety of neutron beamlines. By adjusting the size of the experimental cavity, the interface design, and the position and shape of the beam window, it can be quickly adapted to different neutron scattering experimental platforms.

10. A neutron transmittance experimental apparatus with an adjustable support plate and a cold screen according to claim 1, characterized in that, The cold screen is made of a high-reflectivity metal material with a reflectivity of ≥95%, which can effectively isolate the influence of external radiation on the stability of the internal temperature field of the experimental chamber.

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