Low-temperature fixed point thermodynamic temperature in-situ measurement and calibration device and method

Abstract

The invention provides a low-temperature fixed point thermodynamic temperature in-situ measurement and calibration device and method.The low-temperature fixed point thermodynamic temperature in-situ measurement and calibration device comprises a working cavity, a microwave resonant cavity and a fixed point coupling part are arranged in the working cavity in a sealed mode, a first thermometer is arranged on the microwave resonant cavity, and a second thermometer is arranged on the fixed point coupling part; a fixed point device and a second thermometer are arranged on the fixed point coupling part; the temperature control module is used for providing working temperature for the working cavity; the pressure control module is used for providing working pressure for the working cavity; and the acquisition module comprises an analyzer connected with the microwave resonant cavity and a temperature measurement bridge connected with the second thermometer, the analyzer is used for acquiring the microwave resonant frequency in the microwave resonant cavity, and the temperature measurement bridge is used for acquiring the resistance value of the second thermometer. According to the invention, the thermodynamic temperature T of the fixed point can be measured in situ, and the reproduction of the fixed point T90 is realized, so that the constructed R-T relationship of the standard resistance thermometer is more accurate.

Description

Technical Field

[0001] This invention relates to the field of low-temperature thermodynamic temperature measurement technology, and in particular to a device and method for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature. Background Technology

[0002] In the field of low-temperature metrology, the International Temperature Scale (ITS), as a globally unified numerical standard for temperature, plays a crucial role in the measurement and transmission of thermodynamic temperature. Fixed points, as an important component of the ITS, serve to calibrate and establish the standard resistance thermometer. R - T The (resistance-temperature) relationship is used to transfer temperature values. Therefore, it is evident that both the measurement of fixed-point thermodynamic temperature and the calibration methods of standard resistance thermometers are crucial for constructing accurate... R - T Relationships are all crucial.

[0003] However, in current low-temperature temperature metrology practices, the measurement methods for fixed-point thermodynamic temperature are still mainly based on non-in-situ measurements, and their specific operational procedures have significant shortcomings: First, the specific temperature state of the fixed point needs to be calibrated onto a standard resistance thermometer in a dedicated fixed-point reproduction device; then, the standard resistance thermometer, which has been preliminarily calibrated, needs to be removed from the fixed-point reproduction device and transferred to a reference-level temperature measurement system; finally, the temperature state of the fixed point is reproduced by reproducing the resistance value of the standard resistance thermometer in the reference-level temperature measurement system, thereby completing the reference-level measurement of the fixed-point thermodynamic temperature.

[0004] The drawbacks of this non-in-situ measurement method are quite prominent: On the one hand, the resistance characteristics of the standard resistance thermometer will drift over time. During the transfer from the fixed-point reproduction device to the reference-level temperature measurement system, and during the interval between two experiments, the resistance reference of the thermometer will undergo uncontrollable changes, resulting in errors in the final reproduced fixed-point temperature and affecting the measurement accuracy. On the other hand, this method requires two independent sets of equipment, namely the fixed-point reproduction device and the reference-level temperature measurement system, which not only significantly increases the economic cost of equipment purchase and maintenance, but also means that the experiments of the two sets of devices cannot be carried out simultaneously and must be operated in stages, extending the entire experimental cycle. This is time-consuming and labor-intensive, and it is difficult to meet the actual needs of efficient and high-precision temperature measurement.

[0005] Meanwhile, in the field of standard resistance thermometer calibration methods, the currently common calibration method in the industry is based on the fixed-point temperature defined by the current International Temperature Scale (ITS-90) (hereinafter referred to as...). T 90 Using temperature as the calibration reference has the drawback that some fixed points defined by ITS-90 have limitations. T 90The temperature itself has a high degree of uncertainty, especially at the two low-temperature fixed points around 17K and 20.3K. T 90 The temperature uncertainty even exceeds 1 mK. Because the calibration reference itself has significant uncertainty, using these fixed points to calibrate a standard resistance thermometer will lead to large deviations in the calculated thermometer calibration coefficients, making it impossible to establish a high-precision calibration system. R - T This relationship prevents the efficient transfer of temperature values.

[0006] Given the aforementioned shortcomings, how to develop a fixed-point thermodynamic temperature in-situ measurement device and directly calibrate the in-situ measurement results onto a standard resistance thermometer has become an urgent problem to be solved in this technical field. Summary of the Invention

[0007] This invention provides an in-situ measurement and calibration device and method for low-temperature fixed-point thermodynamic temperature, which solves the problems of large errors, high costs, and low efficiency in existing non-in-situ measurement methods for fixed-point thermodynamic temperature, as well as the limitations of fixed-point international temperature scales. T 90 The high uncertainty leads to the standard resistance thermometer being calibrated R - T To overcome the shortcomings of low accuracy in relational measurements, in-situ measurement of the thermodynamic temperature at a fixed point is achieved. T Simultaneously achieve fixed point T 90 The reproduction of this allows for the construction of a standard resistance thermometer. R - T The relationship is more precise.

[0008] This invention provides a device for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature, comprising: The working cavity is a sealed enclosure containing a microwave resonant cavity and a fixed-point coupling component. A first thermometer is mounted on the microwave resonant cavity, and a fixed-point device and a second thermometer are mounted on the fixed-point coupling component. A temperature control module is used to provide the working temperature for the working chamber; A pressure control module is used to provide working pressure to the working chamber; The acquisition module includes an analyzer connected to the microwave resonant cavity and a temperature measuring bridge connected to the second thermometer. The analyzer is used to acquire the microwave resonant frequency in the microwave resonant cavity, and the temperature measuring bridge is used to acquire the resistance value of the second thermometer.

[0009] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the microwave resonant cavity includes a cavity body, and the cavity body is provided with an air inlet and an air outlet communicating with the working cavity. The cavity wall is provided with a plurality of spaced mounting holes for mounting a plurality of the first thermometers; The cavity is connected to the analyzer outside the working cavity via a microwave antenna.

[0010] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the fixed-point coupling component is suspended below the microwave resonant cavity; The fixed point coupling component is a copper block, which has multiple spaced mounting holes for mounting multiple fixed point devices and multiple second thermometers.

[0011] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the temperature control module includes at least one closed protective cover disposed outside the working chamber, a refrigerator and a heating device, wherein the refrigerator and the heating device are used to regulate the temperature inside the working chamber.

[0012] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the protective cover includes a primary protective cover disposed outside the working chamber and a zero-level protective cover disposed outside the primary protective cover, and both the primary protective cover and the zero-level protective cover are provided with the heating device. Both the primary protective shield and the zero-level protective shield are equipped with vacuum piping structures. The cold head of the refrigeration unit is located between the primary protective cover and the zero-level protective cover.

[0013] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the cold head of the refrigeration unit is disposed on the top of the primary protective cover via a flexible connector.

[0014] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the temperature control module includes a temperature control thermometer disposed on the fixed-point coupling component and a temperature control bridge disposed outside the working chamber, and the temperature control thermometer is electrically connected to the temperature control bridge via a lead wire.

[0015] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the pressure control module includes a gas pipeline connected to the working chamber and an air extraction assembly, an air filling assembly, and a pressure gauge disposed on the gas pipeline.

[0016] According to the present invention, a low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device is provided, wherein the pumping assembly includes a first vacuum pump group and a second vacuum pump group, the filling assembly includes a gas cylinder and a cold trap, and the pressure gauge includes a piston pressure gauge and a digital pressure gauge. The gas pipeline includes a main pipeline connecting the gas cylinder and the working chamber, a first branch pipeline and a second branch pipeline disposed on the main pipeline, the cold trap, the first branch pipeline and the second branch pipeline are arranged sequentially along the main pipeline, a first flow meter is provided between the cold trap and the first branch pipeline, a second flow meter and a first vacuum pump group are sequentially provided on the first branch pipeline, the piston pressure gauge and the second vacuum pump group are sequentially provided on the second branch pipeline, and the digital pressure gauge is provided on the main pipeline.

[0017] This invention also provides a method for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature, using the low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device described above, comprising the following steps: The temperature and pressure inside the working chamber are adjusted by the temperature control module and the pressure control module until the fixed point device reaches the preset temperature. The analyzer acquires the microwave resonant frequency within the microwave resonant cavity, and the data is processed to obtain the fixed-point thermodynamic temperature. T ; The resistance value of a standard reference thermometer is collected, and the data is processed to obtain the fixed-point thermal reproduction. T 90 temperature; The resistance value of the second thermometer is acquired by the temperature measuring bridge. R Data processing yielded R - T or R - T 90 The relationship was established, and in-situ comparisons were performed.

[0018] The present invention provides a device and method for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature. Through the integrated design of a sealed working chamber, the microwave resonant cavity and the fixed-point coupling component are integrated into the same sealed space, allowing the entire operation to be completed without transferring any core measurement components. Simultaneously, the temperature control module and pressure control module provide a stable and controllable temperature and pressure environment for the working chamber, ensuring that the microwave resonant cavity remains under constant measurement conditions after the fixed-point device reaches the set temperature, thus avoiding interference from environmental fluctuations on the microwave resonant frequency acquisition. Based on this, the analyzer directly acquires the microwave resonant frequency within the cavity and calculates the fixed-point thermodynamic temperature. T This fundamentally eliminates the drift error and environmental interference error caused by non-in-situ transfer, making TThe measurement results are closer to the true thermodynamic temperature, significantly improving the measurement accuracy.

[0019] This invention can directly measure the thermodynamic temperature of a fixed point in situ. T The measurement results are more accurate than those obtained through non-in-situ measurements, and are also more time-saving, labor-saving, and cost-effective. It allows for in-situ measurement of thermodynamic temperature at fixed points. T At the same time, achieve fixed point T 90 The reproduction can be achieved by directly applying the fixed-point thermodynamic temperature. T In-situ calibration onto a standard resistance thermometer is possible, and a fixed point can also be used. T 90 Calibration is performed, and the calibration results of the two are compared in situ. Theoretically, because... T Its uncertainty is lower, therefore it is used to construct standard resistance thermometers. R - T The relationship is more precise. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a simplified structural diagram of the in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature provided by the present invention.

[0022] Figure 2 This is a flowchart illustrating the in-situ measurement and calibration method for low-temperature fixed-point thermodynamic temperature provided by the present invention.

[0023] Figure label: 10. Working chamber; 101. Cylinder; 102. First flange; 11. Microwave resonant cavity; 12. Fixed point coupling component; 13. Fixed point device; 14. Second thermometer; 15. Analyzer; 16. Temperature measuring bridge; 17. Microwave antenna; 18. Connecting flange; 19. Second lifting rod; 20. Refrigeration unit; 201. Secondary cold head; 21. Primary protective cover; 211. First cover; 212. Primary flange; 22. Zero-level protective cover; 221. Second cover; 222. Zero-level flange; 23. First three-way valve; 24. Third vacuum pump unit 25. First pressure gauge; 26. Second three-way valve; 27. Fourth vacuum pump assembly; 28. Second pressure gauge; 29. ​​Third boom; 30. Fourth boom; 31. Flexible connector; 32. Temperature control bridge; 33. Gas cylinder; 34. Cold trap; 35. Main pipeline; 36. First branch pipeline; 37. Second branch pipeline; 38. Pressure pipe; 39. First flow meter; 40. Second flow meter; 41. First vacuum pump assembly; 42. Third three-way valve; 43. Piston pressure gauge; 44. Second vacuum pump assembly; 45. Four-way valve; 46. Digital pressure gauge. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] In the description of this invention, it should be understood that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] like Figure 1 As shown, the present invention provides a device for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature, comprising: The working chamber 10 is sealed inside. The working chamber 10 is equipped with a microwave resonant cavity 11 and a fixed point coupling component 12. The microwave resonant cavity 11 is equipped with a first thermometer, and the fixed point coupling component 12 is equipped with a fixed point device 13 and a second thermometer 14. The first thermometer and the second thermometer 14 are both standard resistance thermometers to be calibrated. The temperature control module is used to provide the working temperature for the working chamber 10; The pressure control module is used to provide working pressure to the working chamber 10; The data acquisition module includes an analyzer 15 connected to the microwave resonant cavity 11 and a temperature measuring bridge 16 connected to the second thermometer 14. The analyzer 15 is used to acquire the microwave resonant frequency within the microwave resonant cavity 11, and the temperature measuring bridge 16 is used to acquire the resistance value of the second thermometer 14. Both the analyzer 15 and the temperature measuring bridge 16 are located outside the working cavity 10. The microwave resonant cavity 11 is equipped with a microwave antenna 17 connected to the analyzer 15 at room temperature. The second thermometer 14 is connected to the temperature measuring bridge 16 via a lead wire.

[0029] The temperature control module and pressure control module provide a stable temperature and pressure environment for the temperature measurement system in the working chamber 10. Together with the acquisition module, they can collect data related to the thermodynamic temperature of a fixed point and calibrate the standard resistance thermometer.

[0030] In a preferred embodiment of the present invention, the microwave resonant cavity 11 includes a cavity body, which has an air inlet and an air outlet communicating with the working cavity 10. That is, the cavity body adopts a non-closed design, and the internal pressure is connected to the working cavity 10, achieving synchronization of the temperature and pressure environment between the microwave resonant cavity 11 and the working cavity 10. This eliminates the interference of internal environmental deviations in the microwave resonant cavity 11 on the acquisition of the microwave resonant frequency, thus providing a fixed-point thermodynamic temperature.T The precise calculations provide a more stable medium foundation. Furthermore, some experiments require a specific gas atmosphere to prevent reactions between the fixed-point material and air components, or to optimize the stability of the fixed-point temperature. The design of the inlet and outlet allows the device to flexibly adapt to the gas environment requirements of different experimental conditions. In addition, it facilitates gas replacement and cleaning within the chamber, ensuring the stability and repeatability of long-term measurements.

[0031] Furthermore, the cavity wall is provided with a plurality of spaced mounting holes for mounting a plurality of the first thermometers.

[0032] The cavity is connected to the analyzer 15 outside the working cavity 10 via a microwave antenna 17. Specifically, the microwave antenna 17 includes a transmitting antenna and a receiving antenna, which are connected to the cavity wall to achieve efficient transmission of microwave signals, reduce signal interference and loss, and improve the accuracy of microwave resonant frequency measurement.

[0033] Figure 1 The microwave resonant cavity 11 shown in the diagram adopts a spherical cavity structure, divided into upper and lower hemispheres, each equipped with a microwave antenna 17 and connected to the analyzer 15. It is understood that in other examples, the microwave resonant cavity 11 may also adopt other shapes, such as cylindrical cavities, plate structures, etc., depending on the measurement requirements.

[0034] In a preferred embodiment of the present invention, the fixed-point coupling component 12 is suspended below the microwave resonant cavity 11. Figure 1 As shown, a connecting flange 18 is provided below the microwave resonant cavity 11, and the fixed point coupling component 12 is suspended below the connecting flange 18 by the first hanger.

[0035] Furthermore, the fixed-point coupling component 12 is a copper block with multiple spaced mounting holes for mounting multiple fixed-point devices 13 and multiple second thermometers 14. The use of a uniformly heated copper block for the fixed-point coupling component 12 ensures a uniform temperature distribution around the fixed-point devices 13, guarantees the stability of fixed-point reproduction, and improves the accuracy of thermometer calibration. The high thermal conductivity of the copper block also significantly accelerates the thermal response speed, shortening the time it takes for the fixed-point devices 13 to reach the set temperature. The multiple fixed-point devices 13 and multiple second thermometers 14 can be arranged on the same side or different sides, depending on actual needs. Figure 1 Multiple fixed-point devices 13 and multiple second thermometers 14 are respectively installed on the upper and lower surfaces of the copper block. The shape of the copper block can be cuboid, cube, cylinder, etc., and can be flexibly arranged.

[0036] Furthermore, the working chamber 10 includes a cylindrical body 101 and a first flange 102 disposed at the top opening of the cylindrical body 101. The cylindrical body 101 and the first flange 102 are sealed together. The microwave resonant cavity 11 is suspended below the first flange 102 by a second suspension rod 19. The working chamber 10 is preferably made of high-conductivity oxygen-free copper. The second suspension rod 19 is preferably made of copper to improve the heat conduction rate.

[0037] In a preferred embodiment of the present invention, the temperature control module includes at least one enclosed protective cover disposed outside the working chamber 10, a refrigerator 20, and a heating device. The refrigerator 20 and the heating device are used to regulate the temperature inside the working chamber 10. Through the functional coordination of multiple components, the problems of maintaining a low-temperature environment and precise temperature control can be solved, avoiding interference from the external environment on the temperature field of the working chamber 10, and providing reliable temperature assurance for the stable reproduction of the fixed-point device 13, accurate acquisition of microwave resonant frequency, and calibration of the standard resistance thermometer.

[0038] In some embodiments, the protective shield includes a primary protective shield 21 disposed outside the working cavity 10 and a zero-level protective shield 22 disposed outside the primary protective shield 21, such as... Figure 1 As shown, the primary protective cover 21 includes a first cover body 211 and a primary flange 212 located at the top opening of the first cover body 211. The first cover body 211 is bolted to the primary flange 212, which can reduce external radiative heat transfer. The primary protective cover 21 is also equipped with an independent vacuum pipeline structure, including a first three-way valve 23, a third vacuum pump group 24 and a first pressure gauge 25, which can realize air extraction in the primary protective cover 21 and monitor pressure changes. After vacuuming, the heat exchange between the working chamber 10 and the surrounding first flange 102, first cover body 211 and primary flange 212 can be reduced.

[0039] The zero-level protective cover 22 includes a second cover 221 and a zero-level flange 222 located at the top opening of the second cover 221. The second cover 221 is made of stainless steel and is bolted to the zero-level flange 222. The zero-level protective cover 22 is also equipped with an independent vacuum pipeline structure, including a second three-way valve 26, a fourth vacuum pump group 27 and a second pressure gauge 28, which can realize the evacuation of air inside the zero-level protective cover 22 and monitor pressure changes. The evacuation can isolate the external heat from being transferred inward.

[0040] Furthermore, both the primary protective cover 21 and the zero-level protective cover 22 are equipped with heating devices. In one example, heating elements are installed on both the primary flange 212 and the zero-level flange 222. Temperature control at each level is achieved through a PID active temperature control program, ensuring the temperature of the core temperature measurement system remains stable at the target value. Heating elements can also be installed on the first flange 102. The first pressure gauge 25 and the second pressure gauge 28 can, for example, be digital pressure gauges, providing a clear display of real-time pressure values ​​and improving monitoring effectiveness.

[0041] Furthermore, the first flange 102 and the primary flange 212 are connected by the third hanger 29, and the primary flange 212 and the zero flange 222 are connected by the fourth hanger 30. The third hanger 29 and the fourth hanger 30 are insulated hangers, and the materials include, but are not limited to, G10 material, polyimide composite material, stainless steel, etc. The hangers can adopt a hollow structure to reduce weight and reduce heat transfer. Specifically, the hangers can adopt a thin-walled hollow structure, or the hangers can adopt a hollow structure with a larger wall thickness and have hollow openings on the hanger wall.

[0042] Furthermore, the main body of the refrigeration unit 20 is located in a room temperature environment, for example, outside the zero-level flange 222. The cold head of the refrigeration unit 20 is located between the primary protective cover 21 and the zero-level protective cover 22, such as between the primary flange 212 and the zero-level flange 222. The cold head of the refrigeration unit 20 may include, for example, a primary cold head and a secondary cold head 201. Figure 1 As shown, the secondary cold head 201 is installed perpendicular to the primary flange 212. The secondary cold head 201 is connected to the primary flange 212 via a flexible connector 31, providing a low-temperature environment for the core temperature measurement system. The flexible connector 31 can efficiently transfer the cold energy from the cold head to the core temperature measurement system while effectively suppressing temperature fluctuations in the cold head from being transferred to the core temperature measurement system, thus avoiding temperature field fluctuations in the core temperature measurement system. The primary cold head (not shown in the figure) is positioned above the secondary cold head 201. For example, a secondary flange (not shown in the figure) is provided between the primary flange 212 and the zero-level flange 222. The primary cold head is connected to the secondary flange via a flexible connector. The flexible connector 31 can be, for example, a copper braid formed by multiple strands of copper wire or a copper braided strip, to ensure thermal conductivity and reduce thermal resistance during cold energy transfer.

[0043] In a preferred embodiment of the present invention, the temperature control module includes a temperature-controlled thermometer disposed on the fixed-point coupling component 12 and a temperature-controlled bridge 32 disposed outside the working chamber 10. The temperature-controlled thermometer is electrically connected to the temperature-controlled bridge 32 via leads. The temperature-controlled thermometer is used to detect the temperature of the fixed-point coupling component 12 and to control the temperature of the fixed-point coupling component 12. By directly placing the temperature-controlled thermometer on the fixed-point coupling component 12, the real-time temperature of the fixed-point coupling component 12 can be directly acquired, eliminating the temperature control deviation caused by the temperature field gradient and improving the accuracy of fixed-point reproduction.

[0044] Based on the above embodiments, the pressure control module further includes a gas pipeline connected to the working chamber 10 and a vacuuming assembly, an inflation assembly, and a pressure gauge disposed on the gas pipeline. The vacuuming assembly enables vacuum pretreatment of the working chamber 10 to eliminate interference from impurity gases. The inflation assembly injects the target gas to construct a pressure environment suitable for fixed-point reproduction. The pressure gauge monitors the pressure inside the chamber in real time, providing accurate feedback for closed-loop control. Different low-temperature fixed-point reproductions and microwave resonant frequency measurements may require different pressure ranges. The pressure control module of this invention, through the flexible combination of the vacuuming assembly and the inflation assembly, can cover a wide range of pressure control needs, improving the versatility of the device.

[0045] like Figure 1 As shown, the pumping assembly includes a first vacuum pump group 41 and a second vacuum pump group 44, the filling assembly includes a gas cylinder 33 and a cold trap 34, and the pressure gauge includes a piston pressure gauge 43 and a digital pressure gauge 46. The gas pipeline includes a main pipeline 35 connecting the gas cylinder 33 and the working chamber 10, a first branch pipeline 36 and a second branch pipeline 37 disposed on the main pipeline 35. One end of the main pipeline 35 is connected to the gas cylinder 33 and the other end is connected to the zero-level flange 222, and is connected to the working chamber 10 through a pressure pipe 38. The cold trap 34, the first branch pipeline 36 and the second branch pipeline 37 are arranged sequentially along the main pipeline 35. A first flow meter 39 is provided between the cold trap 34 and the first branch pipeline 36. A second flow meter 40 and a first vacuum pump group 41 are sequentially provided on the first branch pipeline 36. The first branch pipeline 36 is connected to the main pipeline 35 through a third three-way valve 42. The piston pressure gauge 43 and the second vacuum pump group 44 are sequentially provided on the second branch pipeline 37. The second branch pipeline 37 is connected to the main pipeline 35 through a four-way valve 45. The digital pressure gauge 46 is provided on the main pipeline 35.

[0046] The aforementioned pressure control module can evacuate the working chamber 10, fill it with high-purity gas, or evacuate it when needed. By controlling the piston position in the reference-stage piston pressure gauge 43 to remain constant, the pressure within the working chamber 10 is kept stable, providing a stable pressure environment for the core temperature measurement system. The digital pressure gauge 46 can monitor pressure dynamics in real time, providing closed-loop feedback and data traceability for pressure regulation. The digital pressure gauge 46 can be installed beside the four-way valve 45. By setting the first flow meter 39, the intake flow rate can be adjusted. Combined with the use of the second flow meter 40, by controlling the flow rates of the first flow meter 39 and the second flow meter 40 to ensure stable flow into the working chamber 10, accurately controlling the injection rate and total amount of high-purity gas, and ensuring a stable and controllable filling process for the working chamber 10.

[0047] In the experiment, the low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device of the present invention first provides a stable temperature and pressure environment for the temperature measurement space within the working chamber 10 through the temperature control module and the pressure control module. When the fixed-point device 13 reaches the set temperature, the analyzer 15 collects the microwave resonant frequency within the microwave resonant cavity 11, and obtains the fixed-point thermodynamic temperature through data processing. T Then, by collecting the resistance value of a standard reference thermometer and processing the data, the fixed-point thermal reproduction is obtained. T 90 Temperature, and simultaneously the temperature measuring bridge 16 acquires the resistance value of the standard resistance thermometer to be calibrated. R After data processing, the following results were obtained. R - T or R - T 90 The relationship is established, and in-situ comparisons are performed. Theoretically... T The uncertainty is lower, and its construction is more accurate. R - T The relationship is more precise.

[0048] The device of the present invention can detect the resistance change of a standard resistance thermometer under the same fixed point state by repeatedly reproducing the fixed point state, thereby verifying the stability of the standard resistance thermometer.

[0049] In a preferred embodiment, the plurality of fixed point devices 13 on the fixed point coupling component 12 include, but are not limited to, balanced hydrogen fixed point (13.8033K), neon fixed point (24.5561K), oxygen fixed point (54.3584K), argon fixed point (83.8058K), xenon fixed point (161.40596K), mercury fixed point (234.3156K), etc.

[0050] As a preferred embodiment, the working gas in each gas pipeline can be adjusted appropriately according to the temperature range being measured, including but not limited to helium (helium-3, helium-4 or mixtures thereof), argon, neon, etc.

[0051] In a preferred embodiment, the device of the present invention can collect the saturated vapor pressure values ​​of helium-3 and helium-4 within the microwave resonant cavity 11 (in situ reproduction of the international temperature scale T in the temperature range of 0.65K-5K). 90 and thermodynamic temperature T The relevant data, after processing, yielded the saturated vapor pressure. P With thermodynamic temperature T Between P - T Relationships can transfer thermodynamic temperature not only through pressure, but also... T 90 and T In situ comparison.

[0052] The reference temperature measurement methods of the core temperature measurement system of the device of this invention include, but are not limited to, gas refractive index thermometry, constant pressure gas refractive index thermometry, acoustic thermometry, and dielectric constant thermometry. The refrigeration method of the refrigerator can be various forms such as adsorption refrigeration, pulse tube refrigeration, GM refrigeration with throttling, or fluid refrigeration methods such as liquid nitrogen or liquid helium.

[0053] like Figure 2 As shown, the present invention also provides a method for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature, using the low-temperature fixed-point thermodynamic temperature in-situ measurement and calibration device of the above embodiments and examples, including the following steps: S1. Adjust the temperature and pressure in the working chamber through the temperature control module and the pressure control module until the fixed point device reaches the preset temperature; S2. The microwave resonant frequency within the microwave resonant cavity is acquired using the analyzer, and the fixed-point thermodynamic temperature is obtained through data processing. T ; S3. Collect the resistance value of the standard reference thermometer, and obtain the fixed-point thermal reproduction data through data processing. T 90 temperature; S4. Acquire the resistance value of the second thermometer through the temperature measuring bridge. R Data processing yielded R - T or R - T 90 The relationship was established, and in-situ comparisons were performed.

[0054] The present invention provides a device and method for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature. Through the integrated design of a sealed working chamber, the microwave resonant cavity and the fixed-point coupling component are integrated into the same sealed space, allowing the entire operation to be completed without transferring any core measurement components. Simultaneously, the temperature control module and pressure control module provide a stable and controllable temperature and pressure environment for the working chamber, ensuring that the microwave resonant cavity remains under constant measurement conditions after the fixed-point device reaches the set temperature, thus avoiding interference from environmental fluctuations on the microwave resonant frequency acquisition. Based on this, the analyzer directly acquires the microwave resonant frequency within the cavity and calculates the fixed-point thermodynamic temperature. T This fundamentally eliminates the drift error and environmental interference error caused by non-in-situ transfer, making T The measurement results are closer to the true thermodynamic temperature, significantly improving the measurement accuracy.

[0055] This invention can directly measure the thermodynamic temperature of a fixed point in situ. T The measurement results are more accurate than those obtained through non-in-situ measurements, and are also more time-saving, labor-saving, and cost-effective. It allows for in-situ measurement of thermodynamic temperature at fixed points.T At the same time, achieve fixed point T 90 The reproduction can be achieved by directly applying the fixed-point thermodynamic temperature. T In-situ calibration onto a standard resistance thermometer is possible, and a fixed point can also be used. T 90 Calibration is performed, and the calibration results of the two are compared in situ. Theoretically, because... T Its uncertainty is lower, therefore it is used to construct standard resistance thermometers. R - T The relationship is more precise.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature, characterized in that, include: The working cavity is a sealed enclosure containing a microwave resonant cavity and a fixed-point coupling component. A first thermometer is mounted on the microwave resonant cavity, and a fixed-point device and a second thermometer are mounted on the fixed-point coupling component. A temperature control module is used to provide the working temperature for the working chamber; A pressure control module is used to provide working pressure to the working chamber; The acquisition module includes an analyzer connected to the microwave resonant cavity and a temperature measuring bridge connected to the second thermometer. The analyzer is used to acquire the microwave resonant frequency in the microwave resonant cavity, and the temperature measuring bridge is used to acquire the resistance value of the second thermometer.

2. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 1, characterized in that, The microwave resonant cavity includes a cavity body, which is provided with an air inlet and an air outlet communicating with the working cavity. The cavity wall is provided with a plurality of spaced mounting holes for mounting a plurality of the first thermometers; The cavity is connected to the analyzer outside the working cavity via a microwave antenna.

3. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 1, characterized in that, The fixed-point coupling component is suspended below the microwave resonant cavity; The fixed point coupling component is a copper block, which has multiple spaced mounting holes for mounting multiple fixed point devices and multiple second thermometers.

4. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 1, characterized in that, The temperature control module includes at least one enclosed protective cover, a refrigerator, and a heating device disposed outside the working chamber. The refrigerator and the heating device are used to regulate the temperature inside the working chamber.

5. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 4, characterized in that, The protective cover includes a primary protective cover disposed outside the working chamber and a zero-level protective cover disposed outside the primary protective cover, and both the primary protective cover and the zero-level protective cover are equipped with the heating device; Both the primary protective shield and the zero-level protective shield are equipped with vacuum piping structures. The cold head of the refrigeration unit is located between the primary protective cover and the zero-level protective cover.

6. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 5, characterized in that, The cold head of the refrigeration unit is mounted on top of the primary protective cover via a flexible connector.

7. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 4, characterized in that, The temperature control module includes a temperature-controlled thermometer mounted on the fixed-point coupling component and a temperature-controlled bridge mounted on the outside of the working chamber. The temperature-controlled thermometer is electrically connected to the temperature-controlled bridge via leads.

8. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to any one of claims 1-7, characterized in that, The pressure control module includes a gas pipeline connected to the working chamber and an air extraction assembly, an air filling assembly, and a pressure gauge installed on the gas pipeline.

9. The in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature according to claim 8, characterized in that, The pumping assembly includes a first vacuum pump group and a second vacuum pump group; the filling assembly includes a gas cylinder and a cold trap; and the pressure gauge includes a piston pressure gauge and a digital pressure gauge. The gas pipeline includes a main pipeline connecting the gas cylinder and the working chamber, a first branch pipeline and a second branch pipeline disposed on the main pipeline, the cold trap, the first branch pipeline and the second branch pipeline are arranged sequentially along the main pipeline, a first flow meter is provided between the cold trap and the first branch pipeline, a second flow meter and a first vacuum pump group are sequentially provided on the first branch pipeline, the piston pressure gauge and the second vacuum pump group are sequentially provided on the second branch pipeline, and the digital pressure gauge is provided on the main pipeline.

10. A method for in-situ measurement and calibration of low-temperature fixed-point thermodynamic temperature, characterized in that, Using the in-situ measurement and calibration device for low-temperature fixed-point thermodynamic temperature as described in any one of claims 1-9 includes the following steps: The temperature and pressure inside the working chamber are adjusted by the temperature control module and the pressure control module until the fixed point device reaches the preset temperature. The analyzer acquires the microwave resonant frequency within the microwave resonant cavity, and the data is processed to obtain the fixed-point thermodynamic temperature. T ; The resistance value of a standard reference thermometer is collected, and the data is processed to obtain the fixed-point thermal reproduction. T 90 temperature; The resistance value of the second thermometer is acquired by the temperature measuring bridge. R Data processing yielded R - T or R - T 90 The relationship was established, and in-situ comparisons were performed.

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