A cryogenic temperature sensor calibration system and method

Abstract

The application discloses a low-temperature temperature sensor calibration system and method, and relates to the technical field of sensor calibration.The system comprises a vacuum cavity, a first-stage cold shield and a second-stage cold shield arranged inside the vacuum cavity from outside to inside, and a refrigerator.The calibration device is arranged in the second-stage cold shield and comprises a first-stage structure and a second-stage structure.The first-stage structure comprises a second-stage cold disc, a thermal resistance assembly and a third-stage cold disc from top to bottom, the second-stage cold disc is connected with a second-stage cold head, and the third-stage cold disc is provided with an electrical connector.The second-stage structure comprises a calibration cold disc and a heat-conducting column connected between the third-stage cold disc and the calibration cold disc, and the calibration cold disc is provided with a low-temperature temperature sensor.The system performs staged cooling on the inside of the vacuum cavity through the first-stage cold head and the second-stage cold head, attenuates and filters temperature fluctuations of the second-stage cold head transmitted to the third-stage cold disc through the thermal resistance assembly, and collects a sensor resistance value signal after the temperature of the calibration cold disc is controlled to a set temperature point through a heater.The system and method have high temperature stability and high operation efficiency, and can improve calibration precision and work efficiency.

Description

Technical Field

[0001] This invention relates to the field of sensor calibration technology, and in particular to a low-temperature temperature sensor calibration system and method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Cryogenic temperature sensors are devices specifically designed to measure extremely low temperatures (typically well below 0°C and approaching absolute zero). With a measurement limit as low as 5 mK, they can accurately monitor real-time changes in low temperatures, providing reliable data support for scientific research and industrial applications. As the demand for cryogenic temperature sensors in cryogenic fields increases, and as the requirements for accuracy and precision rise, there is a need to develop cryogenic temperature sensor calibration systems that combine high precision and high efficiency.

[0004] Currently, most cryogenic temperature sensor calibration systems are based on cryogenic compressors. However, cryogenic compressors rely on the alternating flow and periodic expansion of hot and cold fluids to achieve cooling, but this working principle inevitably leads to temperature fluctuations in the cold head. In addition, during operation, the mechanical moving parts of the cryogenic compressor and its associated equipment such as vacuum pumps introduce significant mechanical vibrations, further deteriorating temperature stability.

[0005] The temperature fluctuation of the secondary cold head in conventional refrigeration units exceeds ±0.1K, limiting the high-precision calibration of cryogenic temperature sensors. To mitigate the impact of vibration, existing technologies often add vibration damping devices between the secondary cold head and the calibration device. While this method can suppress vibration transmission to some extent, its effect on improving temperature fluctuations is limited and still falls short of the calibration requirements for high-precision sensors. Furthermore, in practical engineering and research applications, it is often necessary to calibrate dozens of cryogenic temperature sensors simultaneously. This process involves multiple manual operations such as welding, disassembly, and fixing, which is cumbersome, time-consuming, and results in low overall testing efficiency.

[0006] In summary, existing low-temperature sensor calibration systems still generally suffer from problems such as large temperature fluctuations, complex calibration processes, and low efficiency, which seriously restrict the rapid and reliable calibration of high-precision low-temperature sensors. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a low-temperature temperature sensor calibration system and method that combines high temperature stability with high operational efficiency, thereby improving the calibration accuracy and working efficiency of low-temperature temperature sensors.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a low-temperature temperature sensor calibration system, comprising: A vacuum chamber, wherein the interior of the vacuum chamber is provided with a primary cold shield and a secondary cold shield arranged from the outside to the inside; The refrigeration unit includes a primary cold head mounted on a primary cold shield and a secondary cold head mounted on a secondary cold shield; A temperature calibration device is located inside a secondary cold shield and includes a primary structure and a secondary structure. The primary structure includes a secondary cold plate, a thermal resistance component, and a tertiary cold plate connected sequentially from top to bottom. The secondary cold plate is connected to the secondary cold head, and the tertiary cold plate is equipped with an electrical connector. The secondary structure includes a calibration cold plate and a heat-conducting column connecting the tertiary cold plate and the calibration cold plate. The calibration cold plate is equipped with a low-temperature sensor to be calibrated and a standard low-temperature sensor. The electrical connection and calibration are completed by connecting both low-temperature sensors to electrical connectors through aviation pins.

[0009] As an alternative implementation, the thermal resistance component includes several groups of thermal resistance components formed by stacking several pieces of metal material, and the thermal resistance of the several groups of thermal resistance components is symmetrically arranged.

[0010] As an alternative implementation, the thermal resistance component attenuates and filters the temperature fluctuations transmitted from the secondary cold head to the tertiary cold plate along the heat transfer path through the thermal resistance generated by the thermal resistance sub-component, thereby reducing the temperature fluctuation amplitude at the calibration cold plate to within ±1 mK.

[0011] As an alternative implementation, the refrigerator is used to perform graded cooling of the vacuum cavity through a primary cold head and a secondary cold head, and to shield radiative heat leakage step by step through a primary cold shield and a secondary cold shield, so that the temperature of the calibration cold plate is reduced to the target calibration temperature range.

[0012] As an alternative implementation, a heater is installed on the heat-conducting column. The heater is used to control the temperature of the calibration cold plate during the temperature control process. After changing the temperature of the calibration cold plate to the set temperature point, the resistance value signal of the low-temperature sensor to be calibrated and the temperature value of the standard low-temperature sensor are collected.

[0013] As an alternative implementation, the low-temperature sensor to be calibrated and the standard low-temperature sensor are arranged in a centrally symmetrical manner around the heat-conducting column.

[0014] As an alternative implementation, a heat sink is provided on the lower surface of the three-stage cold plate.

[0015] As an alternative implementation, the heat sink is formed by uniformly winding multiple strands of wire around the surface of an oxygen-free copper pillar, providing an isothermal anchor point for the sensor leads.

[0016] As an alternative implementation, the secondary cold plate, tertiary cold plate, heat-conducting column, and calibration cold plate are all made of oxygen-free copper.

[0017] In a second aspect, the present invention provides a method for calibrating a low-temperature temperature sensor, employing the low-temperature temperature sensor calibration system of the first aspect, comprising: Install the low-temperature sensor to be calibrated and the standard low-temperature sensor on the calibration cold plate. After completing the electrical connection with the electrical connector through the aviation pin, seal the vacuum chamber and evacuate to the set vacuum threshold. Start the refrigeration unit to cool the inside of the vacuum chamber in stages through the first-stage and second-stage cold heads, and shield the radiative heat leakage step by step through the first-stage and second-stage cold screens, so that the temperature of the calibration cold plate reaches the target calibration temperature range. The temperature fluctuations transferred from the secondary cold head to the tertiary cold plate along the heat transfer path are attenuated and filtered by the thermal resistance component, so that the temperature fluctuation amplitude at the calibration cold plate is reduced to within ±1 mK. The temperature of the calibration cold plate is controlled by a heater. After the temperature of the calibration cold plate is controlled to the set temperature point, the resistance value signal of the low temperature sensor to be calibrated and the temperature value of the standard low temperature sensor are collected. The temperature of the calibration cold plate is changed to the next set temperature point, and the data acquisition process is repeated. Based on the resistance value signals collected from multiple temperature points, the temperature characteristic curve of the low temperature sensor to be calibrated is obtained by fitting, and the calibration is completed.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes a low-temperature temperature sensor calibration system and method, solving the problems of large temperature fluctuations and low calibration efficiency in existing calibration systems. The calibration device adopts a hierarchical modular design. The primary structure connects to the secondary cold head of the refrigeration unit and consists of a secondary cold plate, a thermal resistance component, and a tertiary cold plate. A thermal resistance network formed by multiple high thermal resistance metal sheets and the interfacial contact thermal resistance effectively suppresses temperature fluctuations in the cold head. The secondary structure includes heat-conducting pillars and a calibration cold plate, which are detachably connected to the primary structure, facilitating rapid sensor installation and replacement. A quick electrical connection interface combining electrical connectors and aviation pins is also used to achieve rapid disassembly and replacement of the low-temperature temperature sensor. This invention's system combines high temperature stability and high operational efficiency, improving the calibration accuracy and working efficiency of low-temperature temperature sensors.

[0019] This invention effectively suppresses temperature fluctuations in the refrigeration unit's cold head by using a thermal resistance component and a graded cold plate structure, achieving a highly stable temperature field at the calibration cold plate. Combined with a large heat capacity heat-conducting column, a heat-spreading design, and a symmetrical sensor layout, it ensures uniform heat transfer and consistent temperature measurement, significantly improving temperature stability and calibration accuracy.

[0020] This invention's modular two-level structure design and quick electrical connection interface facilitate the installation, replacement, and electrical connection of batch sensors. Sensor replacement eliminates the need to disassemble the core temperature suppression module, avoiding complex soldering and disassembly processes, thus significantly shortening calibration preparation time and improving overall work efficiency. Simultaneously, by reducing frequent disassembly of the core cold head structure and temperature fluctuation suppression module, the risk of increased system heat leakage, deteriorated interface thermal contact, or mechanical damage due to improper operation is reduced, improving the long-term operational stability and reliability of the calibration system.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the low-temperature temperature sensor calibration system provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the internal structure of the vacuum cavity provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the temperature calibration device provided in Embodiment 1 of the present invention; The components include: 1. Refrigeration unit; 2. Vacuum chamber; 3. Primary cold shield; 4. Secondary cold shield; 5. Primary cold head; 6. Secondary cold head; 7. Temperature calibration device; 8. Secondary cold plate; 9. Thermal resistance component; 10. Tertiary cold plate; 11. Heat-conducting column; 12. Calibration cold plate; 13. Heat sink; 14. Electrical connector; 15. Aviation pin; 16. Low-temperature sensor to be calibrated; 17. Standard low-temperature sensor; and 18. Heater. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0028] Example 1 This embodiment provides a low-temperature temperature sensor calibration system. Through a hierarchical structure and thermal management design, it effectively suppresses the impact of inherent temperature fluctuations of the refrigerator on measurement accuracy. At the same time, it significantly improves the ease of operation and overall efficiency of batch calibration of multiple sensors, thereby meeting the urgent need for high-precision and high-efficiency low-temperature sensor calibration and solving the problems of large temperature fluctuation amplitude, complex calibration process and low efficiency in existing calibration systems.

[0029] like Figures 1-2 As shown, it mainly includes: Vacuum chamber 2, inside which are arranged a primary cooling shield 3 and a secondary cooling shield 4 from the outside to the inside; The refrigeration unit 1 includes a primary cold head 5 disposed on a primary cold screen 3 and a secondary cold head 6 disposed on a secondary cold screen 4; Temperature calibration device 7 is located inside secondary cold shield 4 and includes primary structure and secondary structure. The primary structure includes secondary cold plate 8, thermal resistance component 9 and tertiary cold plate 10 connected from top to bottom. Secondary cold plate 8 is connected to secondary cold head 6 and tertiary cold plate 10 is provided with electrical connector 14. The secondary structure includes a calibration cold plate 12 and a heat-conducting column 11 connecting the tertiary cold plate 10 and the calibration cold plate 12. The calibration cold plate 12 is equipped with a low-temperature sensor 16 to be calibrated and a standard low-temperature sensor 17. The electrical connection and calibration are completed by connecting the two low-temperature sensors to the electrical connector 14 through aviation pins 15.

[0030] like Figures 1-2 As shown, in this embodiment, the vacuum chamber 2 is provided with a multi-stage cold shield, including a first-stage cold shield 3 and a second-stage cold shield 4 from the outside to the inside; The refrigerator 1 is installed on top of the vacuum chamber 2 via a flange seal. The primary cold head 5 and the secondary cold head 6 of the refrigerator 1 extend into the vacuum chamber 2. To reduce radiative heat leakage, a primary cold shield 3 is installed on the primary cold head 5, and a secondary cold shield 4 is installed on the secondary cold head 6.

[0031] As an alternative implementation, the refrigerator 1 may be a pulse tube refrigerator, a GM refrigerator, or a Stirling refrigerator.

[0032] In this embodiment, the temperature calibration device 7 is located within the space surrounded by the secondary cold shield 4 to shield the ambient thermal radiation and improve the temperature stability of the low-temperature sensor.

[0033] The temperature calibration device 7 adopts a modular and hierarchical design, specifically divided into a primary structure for suppressing temperature fluctuations and a secondary structure for installation and calibration.

[0034] like Figure 3 As shown, specifically: The upper end of the primary structure is directly fixed to the secondary cold head 6, and its function is to filter and attenuate the periodic temperature fluctuations and mechanical vibrations from the refrigeration unit's cold head. It includes, from top to bottom, the secondary cold plate 8, the thermal resistance assembly 9, and the tertiary cold plate 10, all connected in sequence.

[0035] The thermal resistance component 9 includes several groups of thermal resistance components made up of several stacked metal materials, each of which has a surface roughness Ra value of less than 0.8 μm.

[0036] This structure, composed of multiple stacked metal materials, utilizes the high thermal resistance of the materials themselves and the interfacial contact thermal resistance between the sheets to form a thermal resistance network with significant thermal inertia, effectively smoothing temperature fluctuations transmitted from the secondary cold head 6. Through this design, the temperature fluctuation amplitude transmitted to the tertiary cold plate 10 can be reduced from over ±0.1 K at the secondary cold head 6 to within ±1 mK.

[0037] In addition, the symmetrical thermal resistance layout of several sets of thermal resistance components not only improves the cooling speed and temperature uniformity of the calibration device, but also provides ample space for the installation of the secondary structure.

[0038] As an alternative implementation method, the metal material can be a low thermal conductivity metal material, such as stainless steel sheet, titanium alloy sheet, nickel-based alloy sheet or lead sheet.

[0039] As an alternative implementation, each set of thermal resistor components can be composed of 10 stacked 304 stainless steel sheets. The thermal resistor component 9 includes 3 sets of thermal resistor components, totaling 30 sheets. It is understood that each set of thermal resistor components can be composed of 5-15 stacked stainless steel sheets. The more sheets there are, the better the temperature stability, but the cooling becomes slower and the temperature difference becomes larger. Therefore, 10 sheets can be selected as a compromise, but it is not limited to this.

[0040] As an alternative implementation, the secondary cold plate 8, the thermal resistance assembly 9, and the tertiary cold plate 10 are fixed to the end of the secondary cold head 6 by high-strength bolts.

[0041] As an alternative implementation method, both the secondary cold plate 8 and the tertiary cold plate 10 are made of high thermal conductivity oxygen-free copper TU0 to ensure that heat can be transferred efficiently and evenly.

[0042] The secondary structure is used to install and calibrate the low-temperature sensor. It is detachably connected to the primary structure, so that the primary structure can be replaced without disassembling the sensor. Specifically, it includes a heat-conducting pillar 11 and a calibration cold plate 12, with the heat-conducting pillar 11 connecting the tertiary cold plate 10 and the calibration cold plate 12.

[0043] A heater 18 is mounted on the surface of the heat-conducting column 11. The heater 18 is used to precisely control the temperature of the calibrated cold plate 12 during the temperature control process, so as to achieve rapid and uniform heat transfer.

[0044] A low-temperature sensor 16 to be calibrated and a standard low-temperature sensor 17 as a reference are installed on the surface of the calibration cold plate 12. In order to improve the uniformity of the temperature field, the low-temperature sensor 16 to be calibrated and the standard low-temperature sensor 17 are arranged in a centrally symmetrical manner around the heat-conducting column 11 on the surface of the calibration cold plate 12.

[0045] As an alternative implementation, the upper end of the heat-conducting column 11 is detachably connected to the bottom of the three-stage cold plate 10, and its lower end is detachably connected to the calibration cold plate 12.

[0046] Detachable connections can be made using threads, keys, pins, snap-fits, etc.

[0047] As an alternative implementation method, the heat-conducting pillar 11 is made of oxygen-free copper TU0, which has a large volume and heat capacity, and plays a role in stabilizing heat flow and uniform temperature.

[0048] As an alternative implementation, the calibration cold plate 12 is made of oxygen-free copper TU0, and its surface is precision polished.

[0049] In this embodiment, a heat sink 13 is provided on the lower surface of the three-stage cold plate 10 to ensure that heat leakage along the sensor lead direction will not introduce additional temperature difference at the measurement point.

[0050] As an alternative implementation, the heat sink 13 is formed by uniformly and tightly winding multiple fine wires around the surface of an oxygen-free copper pillar, providing an isothermal anchor point for the sensor leads to dissipate parasitic heat flow and avoid heat leakage along the direction of the sensor leads, which could cause a temperature difference at the measurement point.

[0051] In this embodiment, to enable rapid connection and replacement of the sensor, an electrical connection component is designed, including an aviation pin 15 located in the calibration cold plate 12 area, and an electrical connector 14 (such as a micro-D connector) connected to an external cable and installed on the three-stage cold plate 10, without the need to disassemble the main structure of the temperature calibration device 7.

[0052] The leads of the low-temperature sensor 16 to be calibrated and the standard low-temperature sensor 17 are soldered to aviation connector 15 and connected to electrical connector 14 via aviation connector 15. During calibration, simply insert the low-temperature sensor 16 to be calibrated into aviation connector 15 and connect the male and female connectors of electrical connector 14 to complete the electrical connection of all sensors. This design avoids the tedious operation of soldering or desoldering leads for each calibration.

[0053] Example 2 This embodiment provides a method for calibrating a low-temperature temperature sensor, using the low-temperature temperature sensor calibration system of Embodiment 1. The specific calibration method includes: Step 1, Installation and Electrical Connection: Install the low-temperature sensor 16 to be calibrated and the standard low-temperature sensor 17 at their respective mounting positions on the surface of the calibration cold plate 12. Use a thermal interface material (Apiezon N grease or indium foil) to ensure that the bottom of the sensor is in close contact with the surface of the calibration cold plate 12. Solder the leads of each sensor to the aviation pin 15 and connect the aviation pin 15 to the electrical connector 14 installed on the three-stage cold plate 10 to complete the electrical connection.

[0054] Step 2, System Sealing and Vacuuming: After closing the flange cover of vacuum chamber 2 and confirming a good seal, start the vacuum pump and molecular pump to evacuate vacuum chamber 2 until the internal pressure of vacuum chamber 2 reaches the set vacuum threshold (10). - 4 Pa).

[0055] Step 3, Cooling: Start the refrigeration unit 1, and cool the inside of the vacuum chamber 2 in stages through the first-stage cold head 5 and the second-stage cold head 6; shield the radiative heat leakage step by step through the first-stage cold shield 3 and the second-stage cold shield 4, so that the temperature of the calibration cold plate 12 is finally reduced to the target calibration temperature range.

[0056] Step 4, Temperature Fluctuation Suppression: Utilizing the thermal resistance generated by the multi-piece metal stacked structure of the thermal resistance component 9, the temperature fluctuations transmitted from the secondary cold head 6 to the tertiary cold plate 10 along the heat transfer path are effectively attenuated and filtered, reducing the temperature fluctuation amplitude at the calibration cold plate 12 from more than ±0.1K at the secondary cold head 6 to within ±1mK.

[0057] Step 5, Precision Temperature Control and Data Acquisition: After the set temperature point stabilizes, the temperature of the calibration cold plate 12 is precisely controlled by the heater 18; at the same time, the temperature value of the standard low temperature sensor 17 and the resistance value signal data of the low temperature sensor 16 to be calibrated are acquired; after the temperature of the standard low temperature sensor 17 is maintained within the calibration point temperature error range for a set time, the heating power of the heater 18 is adjusted to change the temperature of the calibration cold plate 12 to the next set temperature point, and the data acquisition process is repeated.

[0058] Step 6: Calibration Data Processing and Output: Based on the collected standard low-temperature sensor data and the low-temperature sensor data to be calibrated, a calibration curve is established through a fitting algorithm, and various calibration parameters of the low-temperature sensor to be calibrated are determined, and the calibration results are output.

[0059] Step 7, Reset and Replacement: After calibration, turn off the refrigerator 1 and wait for the system to return to room temperature. Then, open the vacuum chamber 2, disconnect the aviation pin 15 from the electrical connector 14, take out the calibrated sensor, and install the next batch of sensors to be calibrated. Repeat the above steps for batch calibration.

[0060] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A low-temperature temperature sensor calibration system, characterized in that, include: A vacuum chamber, wherein the interior of the vacuum chamber is provided with a primary cold shield and a secondary cold shield arranged from the outside to the inside; The refrigeration unit includes a primary cold head mounted on a primary cold shield and a secondary cold head mounted on a secondary cold shield; A temperature calibration device is located inside a secondary cold shield and includes a primary structure and a secondary structure. The primary structure includes a secondary cold plate, a thermal resistance component, and a tertiary cold plate connected sequentially from top to bottom. The secondary cold plate is connected to the secondary cold head, and the tertiary cold plate is equipped with an electrical connector. The secondary structure includes a calibration cold plate and a heat-conducting column connecting the tertiary cold plate and the calibration cold plate. The calibration cold plate is equipped with a low-temperature sensor to be calibrated and a standard low-temperature sensor. The electrical connection and calibration are completed by connecting both low-temperature sensors to electrical connectors through aviation pins.

2. The low-temperature temperature sensor calibration system as described in claim 1, characterized in that, The thermal resistance component includes several groups of thermal resistance components made of several stacked metal materials, and the thermal resistance of the several groups of thermal resistance components is symmetrically arranged.

3. The low-temperature temperature sensor calibration system as described in claim 2, characterized in that, The thermal resistance component attenuates and filters the temperature fluctuations transmitted from the secondary cold head to the tertiary cold plate along the heat transfer path through the thermal resistance generated by the thermal resistance sub-component, reducing the temperature fluctuation amplitude at the calibrated cold plate to within ±1 mK.

4. The low-temperature temperature sensor calibration system as described in claim 1, characterized in that, The refrigerator is used to cool the interior of the vacuum chamber in stages through a primary cold head and a secondary cold head, and to shield radiative heat leakage step by step through a primary cold shield and a secondary cold shield, so that the temperature of the calibration cold plate is reduced to the target calibration temperature range.

5. The low-temperature temperature sensor calibration system as described in claim 1, characterized in that, A heater is installed on the heat-conducting column. The heater is used to control the temperature of the calibration cold plate during the temperature control process. After changing the temperature of the calibration cold plate to the set temperature point, the resistance value signal of the low-temperature sensor to be calibrated and the temperature value of the standard low-temperature sensor are collected.

6. The low-temperature temperature sensor calibration system as described in claim 1, characterized in that, The low-temperature sensor to be calibrated and the standard low-temperature sensor are arranged in a centrally symmetrical manner around the heat-conducting column.

7. The low-temperature temperature sensor calibration system as described in claim 1, characterized in that, A heat sink is installed on the lower surface of the three-stage cold plate.

8. A low-temperature temperature sensor calibration system as described in claim 7, characterized in that, The heat sink is formed by multiple strands of wire evenly wound around the surface of an oxygen-free copper pillar, providing an isothermal anchor point for the sensor leads.

9. A low-temperature temperature sensor calibration system as described in claim 1, characterized in that, The secondary cold plate, tertiary cold plate, heat-conducting column, and calibration cold plate are all made of oxygen-free copper.

10. A method for calibrating a low-temperature temperature sensor, characterized in that, The low-temperature temperature sensor calibration system according to any one of claims 1-9 includes: Install the low-temperature sensor to be calibrated and the standard low-temperature sensor on the calibration cold plate. After completing the electrical connection with the electrical connector through the aviation pin, seal the vacuum chamber and evacuate to the set vacuum threshold. Start the refrigeration unit to cool the inside of the vacuum chamber in stages through the first-stage and second-stage cold heads, and shield the radiative heat leakage step by step through the first-stage and second-stage cold screens, so that the temperature of the calibration cold plate reaches the target calibration temperature range. The temperature fluctuations transferred from the secondary cold head to the tertiary cold plate along the heat transfer path are attenuated and filtered by the thermal resistance component, so that the temperature fluctuation amplitude at the calibration cold plate is reduced to within ±1 mK. The temperature of the calibration cold plate is controlled by a heater. After the temperature of the calibration cold plate is controlled to the set temperature point, the resistance value signal of the low temperature sensor to be calibrated and the temperature value of the standard low temperature sensor are collected. The temperature of the calibration cold plate is changed to the next set temperature point, and the data acquisition process is repeated. Based on the resistance value signals collected from multiple temperature points, the temperature characteristic curve of the low temperature sensor to be calibrated is obtained by fitting, and the calibration is completed.

Images