Universal gas refractive index thermodynamic temperature measurement method, apparatus and device

Abstract

The application provides a universal gas refractive index thermodynamic temperature measurement method, device and equipment, and relates to the technical field of temperature measurement. The method comprises the following steps: establishing a reference state and obtaining a reference experimental refractive index and a reference theoretical refractive index, determining a relative ratio constant representing the ratio relationship between the theoretical refractive index and the experimental refractive index in the reference state; establishing a to-be-measured state and obtaining a to-be-measured experimental refractive index and a to-be-measured theoretical refractive index; taking the relative ratio constant as a constraint condition, adjusting the numerical value of the to-be-measured thermodynamic temperature through iterative calculation, so that the ratio of the to-be-measured theoretical refractive index to the to-be-measured experimental refractive index approaches the relative ratio constant, until the deviation is less than a preset allowable error, and the converged temperature value is determined as the to-be-measured thermodynamic temperature. The application can reduce the absolute pressure measurement error and the system error caused by the deformation of the resonant cavity, and realize high-accuracy thermodynamic temperature measurement in a low-temperature zone.

Description

Technical Field

[0001] This invention relates to the field of temperature measurement technology, and in particular to a general method, apparatus and equipment for measuring the thermodynamic temperature of gas refractive index. Background Technology

[0002] Refractive index gas thermometry (RIGT) is based on electromagnetic theory and the gas law, and uses microwave resonant cavity technology to invert thermodynamic temperature by measuring the refractive index of a gas.

[0003] Traditional RIGT typically employs absolute measurement methods, requiring extremely high precision in absolute pressure measurement and accurate assessment of the resonant cavity geometry as a function of pressure. Specifically, especially in the cryogenic region: on the one hand, gas non-ideality increases, significantly increasing the relative uncertainty of absolute pressure measurement; on the other hand, the physical properties of the resonant cavity material change with decreasing temperature, making in-situ accurate measurement of its isothermal compressibility extremely difficult, and the systematic errors introduced by cavity contraction and deformation at low temperatures are difficult to completely eliminate using conventional methods, severely limiting the improvement of measurement accuracy.

[0004] Therefore, there is an urgent need to design a technical solution that can eliminate or reduce the errors in absolute pressure measurement and the systematic errors caused by resonant cavity deformation. Summary of the Invention

[0005] This invention provides a generalized method, apparatus, and equipment for measuring the thermodynamic temperature of gas refractive index, in order to solve the problems of existing absolute pressure measurement errors and systematic errors caused by resonant cavity deformation.

[0006] This invention provides a generalized method for measuring the thermodynamic temperature of gas refractive index, comprising: establishing a reference state, wherein the reference state is the state of the working gas at a known reference thermodynamic temperature and a known reference gas pressure; obtaining the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determining a relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index, wherein the relative ratio constant characterizes the ratio relationship between the theoretical refractive index and the experimental refractive index under the reference state; establishing a test state, wherein the test state is the state of the working gas at the test thermodynamic temperature; obtaining the test experimental refractive index and the test theoretical refractive index under the test state; using the relative ratio constant as a constraint, adjusting the value of the test thermodynamic temperature through iterative calculation, so that the ratio of the test theoretical refractive index to the test experimental refractive index approaches the relative ratio constant, until the deviation is less than a preset allowable error, and determining the converged temperature value as the test thermodynamic temperature.

[0007] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, the reference experimental refractive index under a reference state is obtained by: measuring the reference resonant frequency under vacuum conditions using a microwave resonant cavity; filling the microwave resonant cavity with a working gas and establishing a reference state, and measuring the first resonant frequency under the reference state; and calculating the reference experimental refractive index based on the reference resonant frequency, the first resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

[0008] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, the refractive index of the test experiment under the test state is obtained by: measuring the second resonant frequency under the test state using a microwave resonant cavity; and calculating the refractive index of the test experiment based on the reference resonant frequency, the second resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

[0009] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, the reference theoretical refractive index is obtained through the following steps: determining the molar density of the working gas under reference conditions; and calculating the reference theoretical refractive index using the virial equation and the Lorentz-Lorentz formula based on the molar density under reference conditions and the dielectric virial coefficient and magnetic susceptibility virial coefficient of the working gas.

[0010] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, the theoretical refractive index to be measured is obtained through the following steps: determining the molar density of the working gas in the test state; calculating the theoretical refractive index to be measured using the virial equation and the Lorentz-Lorentz formula based on the molar density in the test state and the dielectric virial coefficient and magnetic susceptibility virial coefficient of the working gas.

[0011] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, establishing a state to be measured includes: maintaining the gas pressure in the state to be measured at a level equal to that of a reference gas pressure through a gas pressure control system; and adjusting the temperature of the state to be measured to the thermodynamic temperature while maintaining a constant gas pressure.

[0012] According to the present invention, a generalized method for measuring the thermodynamic temperature of gas refractive index is provided. The method further includes: measuring the microwave resonant frequency of a microwave resonant cavity at multiple different test temperatures while maintaining the gas pressure at the same level as the reference gas pressure; and solving for the thermodynamic temperature at each test temperature based on the relationship between the experimental refractive index and temperature at each test temperature.

[0013] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, the method for establishing a test state includes: adjusting the temperature of the test state to the test thermodynamic temperature; adjusting the gas pressure in the test state and monitoring the real-time resonant frequency of the microwave resonant cavity until the real-time resonant frequency reaches the target resonant frequency corresponding to the reference experimental refractive index, and the test experimental refractive index in the test state is equal to the reference experimental refractive index.

[0014] According to the present invention, a generalized method for measuring the thermodynamic temperature of gas refractive index is provided, which further includes: calculating the target resonant frequency based on the reference experimental refractive index, the reference resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity.

[0015] According to a generalized method for measuring the thermodynamic temperature of gas refractive index provided by the present invention, the method for establishing a test state includes: maintaining the temperature of the test state at a single test thermodynamic temperature; acquiring the experimental resonant frequencies corresponding to at least two different gas pressure points at the single test thermodynamic temperature; calculating the ratio of the refractive indices to be measured based on the experimental resonant frequencies corresponding to the at least two different gas pressure points; using the test thermodynamic temperature as a variable, calculating the theoretical refractive indices corresponding to the at least two different gas pressure points, and calculating the ratio of the theoretical refractive indices; and iteratively solving for the test thermodynamic temperature using the constraint that the ratio of the theoretical refractive indices is equal to the ratio of the refractive indices to be measured.

[0016] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, at least two different gas pressure points include a first pressure point and a second pressure point, wherein the difference between the first pressure point and the second pressure point is less than a preset pressure threshold.

[0017] According to a generalized gas refractive index thermodynamic temperature measurement method provided by the present invention, the ratio of the refractive index to be measured is calculated based on the experimental resonant frequencies corresponding to at least two different gas pressure points, including: calculating the ratio of the refractive index to be measured based on the reference resonant frequency obtained under vacuum conditions using a microwave resonant cavity and the experimental resonant frequencies corresponding to at least two different gas pressure points.

[0018] This invention also provides a generalized gas refractive index thermodynamic temperature measurement device, comprising: a reference state establishment module for establishing a reference state, wherein the reference state is the state of the working gas under a known reference thermodynamic temperature and a known reference gas pressure; a reference refractive index acquisition and ratio determination module for acquiring the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determining a relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index, wherein the relative ratio constant characterizes the ratio relationship between the theoretical refractive index and the experimental refractive index under the reference state; a test state establishment module for establishing a test state, wherein the test state is the state of the working gas under the test thermodynamic temperature; a test refractive index acquisition module for acquiring the test experimental refractive index and the test theoretical refractive index under the test state; and a temperature iterative solution module for adjusting the value of the test thermodynamic temperature by iterative calculation with the relative ratio constant as a constraint, so that the ratio of the test theoretical refractive index to the test experimental refractive index approaches the relative ratio constant, until the deviation is less than a preset allowable error, and determining the converged temperature value as the test thermodynamic temperature.

[0019] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement any of the generalized gas refractive index thermodynamic temperature measurement methods described above.

[0020] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the generalized gas refractive index thermodynamic temperature measurement methods described above.

[0021] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements any of the generalized gas refractive index thermodynamic temperature measurement methods described above.

[0022] The generalized gas refractive index thermodynamic temperature measurement method, apparatus, and equipment provided by this invention introduces a reference state under a known reference thermodynamic temperature and reference gas pressure. It obtains the reference experimental refractive index at the experimental level and the reference theoretical refractive index at the theoretical level, establishing a relative ratio constant between the two. This relative ratio constant serves as a unified constraint benchmark for subsequent iterative solutions. This transforms the dependence on the absolute values ​​of pressure and cavity deformation parameters in traditional absolute refractive index temperature measurement into tracking the ratio relationship between the measured state and the reference state, thereby eliminating the influence of absolute pressure measurement errors on the temperature measurement results. Furthermore, by establishing the measured state and obtaining its measured actual... The experimental refractive index and the theoretical refractive index to be measured are compared. The ratio constant is used as a constraint to iteratively solve the problem, making the ratio of the theoretical refractive index to the experimental refractive index under the measured state close to the constant. This iterative solution mechanism can automatically cancel out common errors in microwave resonant frequency measurement, such as system drift and slow changes in resonant cavity geometry, in the ratio calculation, thereby effectively eliminating system errors introduced by resonant cavity deformation. Finally, by determining the converged temperature value as the thermodynamic temperature to be measured, the temperature measurement problem is transformed into a frequency ratio approximation problem. This fully utilizes the physical advantage of high accuracy in frequency measurement, thereby realizing high-accuracy thermodynamic temperature measurement in the low-temperature region. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is a schematic flowchart of a generalized gas refractive index thermodynamic temperature measurement method provided in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the path between the reference state and the state to be measured in a generalized gas refractive index thermodynamic temperature measurement method provided in an embodiment of the present invention.

[0026] Figure 3 This is an embodiment of the present invention, which provides an isobaric refractive index gas temperature measurement method and a flowchart thereof.

[0027] Figure 4 This is a flowchart of a generalized gas refractive index temperature measurement method provided in an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of a generalized gas refractive index thermodynamic temperature measuring device provided in an embodiment of the present invention.

[0029] Figure 6This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0030] 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.

[0031] The following is combined with Figure 1 This invention describes a generalized method for measuring the thermodynamic temperature of gas refractive index. For consistency, the entity performing this method will be uniformly referred to as the "system," and will not be described further thereafter.

[0032] Figure 1 This is a schematic diagram of a generalized gas refractive index thermodynamic temperature measurement method provided by an embodiment of the present invention, as shown below. Figure 1 As shown, the method includes the following: S101. Establish reference state.

[0033] The reference state refers to the state of the working gas at a known reference thermodynamic temperature and a known reference gas pressure.

[0034] In this embodiment of the invention, the working gas refers to the gas medium filled into the microwave resonant cavity for refractive index measurement. This working gas can be selected from helium-4 (… 4 He), helium-3 ( 3 Helium (He), neon (Ne), or argon (Ar), or a mixture thereof at known concentrations, can be used. Simply replace the corresponding virial coefficients and physical parameters in the theoretical calculations. This embodiment uses helium-4 as an example, but the invention is not limited thereto.

[0035] In some embodiments, the system needs to perform preparatory operations before establishing a reference state.

[0036] For example, the microwave resonant cavity is first evacuated, then the refrigerator is turned on to cool it down. After the temperature drops to the temperature to be measured, the microwave resonant frequency at each temperature point is measured under vacuum conditions to establish a vacuum frequency reference.

[0037] For example, the microwave resonant cavity can be a quasi-spherical microwave resonant cavity, which is housed in a cryostat. The cryostat provides a controllable low-temperature environment for the microwave resonant cavity, ensuring that the temperature within the cavity remains stable within the desired measurement range. It should be noted that other geometric shapes of resonant cavities can also be used, as long as they can generate a stable microwave resonant frequency.

[0038] Specifically, when establishing a reference state, the system temperature is first stabilized at a known reference thermodynamic temperature. The reference thermodynamic temperature can be selected from any one or more fixed-point temperatures among the helium superfluid transition temperature, hydrogen triple point temperature, neon triple point temperature, oxygen triple point temperature, argon triple point temperature, xenon triple point temperature, carbon dioxide triple point temperature, and water triple point temperature, or other high-accuracy thermodynamic temperatures. Then, high-purity working gas is introduced into the microwave resonant cavity until its pressure reaches the reference gas pressure. This establishes a reference state.

[0039] In this embodiment, the reference thermodynamic temperature is preferably the neon triple point temperature, approximately 24.5561 K, but the present invention is not limited thereto.

[0040] S102. Obtain the reference experimental refractive index and the reference theoretical refractive index under the reference condition.

[0041] In some embodiments, a microwave resonant cavity can be used to measure the reference resonant frequency under vacuum conditions.

[0042] For example, after the system is evacuated, the resonant frequency of the microwave resonant cavity under vacuum is measured using a microwave frequency measurement system and denoted as . .

[0043] in, This indicates the current temperature point. This vacuum resonant frequency serves as the reference frequency for subsequent refractive index calculations.

[0044] Specifically, the reference resonant frequency measurement under vacuum conditions can be performed at multiple temperature points to establish a vacuum frequency reference curve that varies with temperature.

[0045] In this embodiment, at least at the reference thermodynamic temperature Measuring the vacuum resonant frequency , which serves as the experimental refractive index benchmark for calculation reference state.

[0046] Furthermore, a working gas is introduced into the microwave resonant cavity to establish a reference state, and the first resonant frequency under the reference state is measured.

[0047] For example, at a reference thermodynamic temperature and reference gas pressure The resonant frequency of the microwave resonant cavity is measured using a microwave frequency measurement system and denoted as . .

[0048] Specifically, the first resonant frequency measurement should be performed after the system temperature has stabilized at the reference thermodynamic temperature and the pressure has stabilized at the reference gas pressure.

[0049] For example, pressure stabilization can be achieved through a gas pressure control system, which can precisely control and monitor the working gas pressure inside the resonant cavity.

[0050] Furthermore, the reference experimental refractive index is calculated based on the reference resonant frequency, the first resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

[0051] For example, the reference experimental refractive index The calculation can be performed as follows: based on the vacuum resonant frequency. Resonant frequency in the inflated state The frequency shift relationship between them, combined with the isothermal compressibility of the microwave resonator at the current temperature. Make corrections and calculate the refractive index of the reference experiment.

[0052] Specifically, the reference experimental refractive index calculation is based on the following physical principle: the resonant frequency of the microwave resonant cavity is related to the refractive index of the medium inside the cavity. When the cavity is filled with working gas, the resonant frequency will shift. The refractive index of the gas can be deduced by measuring this frequency shift.

[0053] Isothermal compressibility It is used to correct the influence of changes in the geometric dimensions of the resonant cavity under pressure on the frequency measurement results.

[0054] In this embodiment, the experimental refractive index can be calculated using the following formula: .

[0055] in, For the experimental refractive index, It is the vacuum resonant frequency. This is the resonant frequency when the air is inflated. This represents the gas pressure.

[0056] Thus, by calculating the ratio of the vacuum frequency reference to the frequency under gas conditions, and combining it with the isothermal compressibility coefficient correction, this invention can accurately obtain the refractive index data at the experimental level, laying a reliable experimental foundation for subsequent ratio determination.

[0057] In other embodiments, the molar density of the working gas under reference conditions can be determined.

[0058] For example, molar density It's pressure and temperature Function, i.e. Under reference conditions, based on the known reference gas pressure... and reference thermodynamic temperature The molar density under this state can be determined using the working gas law. .

[0059] Specifically, the working gas equation of state can be described using the virial equation. The virial equation expresses pressure as a power series of molar density, accurately describing the thermodynamic behavior of real gases at different temperatures and pressures. Under the reference state, according to... , Given the virial coefficient of the working gas, the molar density can be obtained by solving for it. .

[0060] Furthermore, based on the molar density under the reference state and the dielectric and magnetic virial coefficients of the working gas, the reference theoretical refractive index is calculated using the virial equation and the Lorentz-Lorentz formula.

[0061] For example, theoretical refractive index The calculations are based on the Lorentz-Lorenz equation in electromagnetic theory, which establishes a quantitative relationship between the refractive index and molar density of a gas.

[0062] Specifically, the theoretical refractive index can be calculated as follows: .

[0063] Among them, molar density It's pressure and temperature Function, unit is kilogram per mole (kg / mol); The virial coefficient is the first magnetic susceptibility, and its unit is cubic meters per mole (m). 3 / mol); , and These are the first, second, and third dielectric virial coefficients, respectively, with units of cubic meters per mole (m³). 3 / mol), m6th power per mole square (m 6 / mol 2 ) and m9 per mole cubic meter (m9) 9 / mol 3 ).

[0064] In this embodiment, for the working gas Helium-4, the above virial coefficient is: , , , All of these can be obtained from publicly available physical property databases. When changing the type of working gas, simply replace the aforementioned virial coefficients and physical parameters accordingly.

[0065] Thus, by combining the virial equation and the Lorentz-Lorentz formula, this invention can accurately calculate the refractive index of the working gas under known conditions from a theoretical perspective, providing a theoretical benchmark for subsequent comparison with experimental refractive indices.

[0066] S103. Determine the relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index.

[0067] The relative ratio constant characterizes the relationship between the theoretical refractive index and the experimental refractive index under the reference state.

[0068] In some embodiments, the relative ratio constant It is determined by the ratio of the theoretical refractive index to the experimental refractive index under reference conditions.

[0069] For example, relative ratio constant The calculation method is as follows (first example): .

[0070] in, Theoretical refractive index, For the experimental refractive index, For temperature, For pressure, Given the known reference state, r It is a ratio.

[0071] For example, relative ratio constant It can also be calculated in a manner that includes, but is not limited to, the following (second example): .

[0072] The following text uses only relative ratio constants. The first example provides a detailed explanation; others only require further explanation. r Simply define the update and iteration constraints: Specifically, the reference experimental refractive index under reference conditions. and reference theoretical refractive index The system then calculates the ratio of the two to obtain the relative ratio constant. This ratio constant reflects the proportional relationship between theoretically calculated values ​​and experimentally measured values ​​under known reference conditions.

[0073] It should be noted that this relative ratio constant The physical significance lies in its characterization of the system deviation characteristics of the measurement system under reference conditions. Since experimental refractive index measurements are inevitably affected by factors such as resonant cavity geometry errors and circuit system drift, while theoretical refractive index calculations are based on idealized physical models, the ratio between the two... actually contains the system error information of the measurement link. In the subsequent measurement of the state to be tested, by maintaining the constant ratio as a constraint condition, these system errors can be automatically offset in the ratio operation.

[0074] In this way, the present invention establishes the ratio constant of the theoretical refractive index and the experimental refractive index under the reference state, which provides a key constraint reference for the subsequent temperature solution of the state to be tested, so that the temperature measurement is transformed from relying on absolute values to tracking relative ratios.

[0075] S104: Establish the state to be tested.

[0076] wherein the state to be tested is a state where the working gas is at the thermodynamic temperature to be tested.

[0077] In the following, first in combination with Figure 2 the schematic diagram of the path between the reference state and the state to be tested provided by the embodiment of the present invention is described, so as to generally understand the basic concepts of the other three measurement paths.

[0078] Figure 2 is a schematic diagram of the path between the reference state and the state to be tested in the generalized gas refractive index thermodynamic temperature measurement method provided by the embodiment of the present invention.

[0079] As shown in Figure 2 in the pressure-refractive index (p-(n-1)) phase diagram, the vertical axis represents the gas pressure p, and the horizontal axis represents the difference (n-1) between the gas refractive index n and 1. In the figure, T1, T2, and T3 are three isotherms, which respectively correspond to three different constant temperatures and satisfy T1<T2<T3. The three measurement paths of the present invention respectively correspond to different trajectories: Isobaric refractive index gas thermometry: measurement is carried out along the isobar, that is, starting from the reference state, the temperature is changed under the condition that the pressure remains constant, and the temperature measurement is realized by measuring the change of the gas refractive index. This path appears as a horizontal direction on the phase diagram.

[0080] Iso-refractive index gas thermometry: measurement is carried out along the iso-refractive index line, that is, starting from the reference state, under the condition that the refractive index remains constant, the temperature measurement is realized by adjusting the gas pressure. This path appears as a vertical direction on the phase diagram.

[0081] Generalized gas refractive index thermometry: measurement is carried out along the isotherms (the oblique lines T1, T2, T3), that is, under the condition that the temperature remains constant, the refractive index ratio of two different pressure points is measured to invert the temperature.

[0082] In addition, the generalized gas refractive index thermometry is used for comparison with the relative measurement method of the present invention.

[0083] In this embodiment of the invention, the three measurement paths each have their own characteristics and can be selected according to actual measurement needs. The isobaric path is suitable for scenarios requiring multi-point temperature measurement, the isorefractive index path is suitable for high-precision measurement under low temperature and low pressure environments, and the isothermal path is suitable for scenarios where no external reference thermodynamic temperature is required. The specific implementation methods of these three paths are described in detail below.

[0084] Path 1: Isobaric refractive index gas thermometry; In one alternative implementation, the gas pressure under the test state can be maintained at an equal level to the reference gas pressure by a gas pressure control system.

[0085] For example, in the isobaric refractive index gas thermometry method, measurements are taken along isobars, i.e., the pressure of the state to be measured is maintained. Compared with reference gas pressure Consistent. The gas pressure control system continuously monitors the pressure value inside the resonant cavity and maintains the pressure at a constant level through feedback adjustment. nearby.

[0086] Specifically, the core of the isobaric refractive index gas thermometry method lies in maintaining constant pressure. Because the pressure remains constant, the mechanical stress on the resonant cavity remains unchanged during the measurement process, thus avoiding geometric deformation of the resonant cavity caused by pressure changes.

[0087] Furthermore, while maintaining a constant gas pressure, the temperature of the state to be measured is adjusted to the thermodynamic temperature to be measured.

[0088] For example, when the pressure is constant Under these conditions, the temperature of the microwave resonant cavity is adjusted by the temperature control system to stabilize it at the initial estimated value of the temperature to be measured. After the temperature stabilizes, measure the microwave resonant frequency under this condition. .

[0089] Specifically, temperature regulation can be achieved through a cryogenic thermostat temperature control system. This system can precisely control the resonant cavity temperature near the target temperature and maintain long-term temperature stability.

[0090] In this embodiment, the initial estimated value of the temperature to be measured It can be set according to experimental requirements, for example, it can be set near a target temperature in the low temperature zone.

[0091] Furthermore, with the gas pressure maintained at the same level as the reference gas pressure, the microwave resonant frequency of the microwave resonant cavity was measured at multiple different test temperatures.

[0092] For example, in the isobaric refractive index gas thermometry method, the temperature can be sequentially set to multiple different measured temperature values ​​while keeping the pressure constant. For instance, it can be set to... , , After stabilizing at each temperature point, the corresponding microwave resonant frequency was measured.

[0093] Specifically, the selection of each temperature point to be measured can be determined according to the actual temperature measurement needs. For example, multiple measurement points can be selected evenly at certain temperature intervals within the target temperature zone.

[0094] Furthermore, the thermodynamic temperature at each test temperature is determined based on the relationship between the experimental refractive index and temperature at each test temperature.

[0095] For example, at each temperature point to be measured, the experimental refractive index at that temperature is calculated based on the measured microwave resonant frequency, and the curve of the experimental refractive index changing with temperature is obtained. Then, the thermodynamic temperature of each temperature point is solved by iterative inversion.

[0096] Specifically, in the isobaric refractive index gas thermometry method, since the pressure is constant, the theoretical relationship between refractive index and temperature can be pre-calculated using the virial equation and the Lorentz-Lorentz formula. The experimental refractive index at each temperature point is then compared with the theoretical prediction, taking into account the relative ratio constant. By applying constraints, the accurate thermodynamic temperature at each temperature point can be obtained through iterative solutions.

[0097] Thus, by using a constant pressure design for the isobaric refractive index gas thermometry method, this invention effectively avoids resonant cavity deformation caused by pressure changes, reduces the dependence on the accuracy of isothermal compressibility evaluation, and thereby reduces the systematic error introduced by the uncertainty of cavity deformation parameters. At the same time, by using a multi-point measurement method, multiple temperature points can be measured at a single pressure setting, improving measurement efficiency.

[0098] Path 2: Isorefractory gas thermometry In another alternative implementation, the temperature of the state to be measured can be adjusted to the thermodynamic temperature to be measured.

[0099] For example, the measurement path is in temperature-pressure ( - Measurements are taken along the isorheological lines in the phase diagram, i.e., the isorheological microwave frequency path, and the temperature at low temperature and low pressure is determined using a reference point at a higher temperature and high pressure.

[0100] Furthermore, the gas pressure in the test state is adjusted, and the real-time resonant frequency of the microwave resonant cavity is monitored until the real-time resonant frequency reaches the target resonant frequency corresponding to the refractive index of the reference experiment.

[0101] In this test, the refractive index of the experimental sample is equal to that of the reference sample under the test conditions.

[0102] For example, first, the temperature is adjusted to the temperature of the point to be measured, and then the gas pressure is adjusted so that the measured microwave resonant frequency reaches the target resonant frequency, thereby achieving the refractive index. Consistent with the reference state, that is: .

[0103] Specifically, by adjusting the gas pressure to make the experimental refractive index of the test state equal to that of the experimental reference state, a direct constraint relationship between the test state and the reference state was established.

[0104] Alternatively, the target resonant frequency can be calculated first based on the reference experimental refractive index, the reference resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity.

[0105] For example, based on the experimental refractive index value of the reference state, the microwave resonant frequency required to reach that refractive index, i.e., the target resonant frequency, is calculated in reverse.

[0106] Specifically, the target resonant frequency is calculated based on the experimental refractive index calculation formula, and is solved in reverse by using the known reference experimental refractive index, vacuum resonant frequency and isothermal compressibility coefficient.

[0107] In some embodiments, adjusting the gas pressure in the test state can be achieved through a high-precision pressure control system, combined with real-time microwave frequency monitoring, to ensure accurate attainment of the target resonant frequency.

[0108] For example, the pressure control system adopts a closed-loop control method, and dynamically adjusts the intake or exhaust valves according to the real-time monitoring of the deviation between the microwave resonant frequency and the target resonant frequency to achieve precise pressure regulation.

[0109] Thus, by using the isorefractive index constraint of the gas thermometry path, this invention transforms temperature measurement under low temperature and low pressure into comparison with a high pressure reference point, effectively avoiding the problem of insufficient accuracy in absolute pressure measurement under low temperature and low pressure environments.

[0110] Path 3: Generalized Gas Refractive Index Thermometry In another alternative implementation, the temperature of the state to be measured can be maintained at a single thermodynamic temperature to be measured.

[0111] For example, this measurement path is in temperature-pressure ( - Measurements are taken along the isotherms in the phase diagram at the temperature to be measured. While keeping the temperature constant, the microwave resonant frequency is measured at two different pressure points, and the thermodynamic temperature is inverted using the ratio of the refractive indexes of the two states.

[0112] Furthermore, at a single thermodynamic temperature to be measured, the experimental resonant frequencies corresponding to at least two different gas pressure points are obtained respectively.

[0113] Among them, at least two different gas pressure points include a first pressure point and a second pressure point, and the difference between the first pressure point and the second pressure point is less than a preset pressure threshold.

[0114] For example, a working gas is first introduced into the microwave resonant cavity to bring it to the first pressure point. Measuring the microwave resonant frequency at the temperature to be measured Then maintain the temperature. Keep the pressure constant, then change the gas pressure to the second pressure point. Measuring the microwave resonant frequency at the temperature to be measured .

[0115] Specifically, the first pressure point With the second pressure point They should be close together to reduce the isothermal compressibility of the microwave resonant cavity. And the effect of pressure measurement.

[0116] In this embodiment of the invention, the preset pressure threshold can be set according to the experimental accuracy requirements. For example, it can be set to... and The difference is less than a certain percentage or less than a certain absolute pressure value. For example, less than 1%.

[0117] Furthermore, the ratio of the refractive index to be measured is calculated based on the experimental resonant frequencies corresponding to at least two different gas pressure points.

[0118] Optionally, the ratio of the refractive index to be measured can be calculated based on the reference resonant frequency under vacuum conditions obtained by microwave resonant cavity measurement and the experimental resonant frequencies corresponding to at least two different gas pressure points.

[0119] For example, the experimental refractive index is first calculated under two pressures, and then the two are divided to obtain the ratio of experimental refractive indices. .

[0120] Specifically, the experimental refractive index ratio The calculation can utilize the vacuum reference resonant frequency to eliminate common-mode errors during the measurement process. Since the two pressure point measurements are performed at the same temperature, the constant term error caused by vacuum frequency drift is automatically canceled out in the ratio calculation.

[0121] Furthermore, by taking the thermodynamic temperature to be measured as a variable, the theoretical refractive index corresponding to at least two different gas pressure points is calculated, and the ratio of the theoretical refractive indices is calculated.

[0122] For example, calculate the same temperature separately. Two pressures and Each corresponding theoretical refractive index and Then calculate the theoretical refractive index ratio: .

[0123] Specifically, in theoretical refractive index calculations, molar density It is determined by the current pressure and temperature using the virial equation. For a given temperature and pressure Solving the virial equation yields the molar density. Then, substitute the values ​​into the Lorentz-Lorentz formula to calculate the theoretical refractive index.

[0124] Furthermore, the thermodynamic temperature to be measured is solved iteratively by using the constraint that the ratio of the theoretical refractive index to the ratio of the refractive index to be measured is equal.

[0125] For example, the deviation is calculated: .

[0126] If the deviation is less than the preset tolerance, then output To obtain the final thermodynamic temperature. If the deviation is too large, adjust. Return to recalculate the theoretical refractive index under both pressures. and Until it converges.

[0127] Specifically, in the generalized gas refractive index thermometry approach, the iterative solution objective is to maximize the theoretical refractive index ratio. Approximating the experimental refractive index ratio Due to the experimental refractive index ratio It is obtained directly through frequency measurement, and does not rely on prior knowledge of temperature. Therefore, it can be obtained by continuously adjusting the temperature. This ensures that the theoretical ratio matches the experimental ratio, thus allowing for the accurate deduction of the thermodynamic temperature.

[0128] Thus, this invention achieves absolute temperature measurement without external reference thermodynamic temperature by iteratively solving the path ratio constraint of the generalized gas refractive index thermometry method, while eliminating the error of the vacuum frequency drift constant term through differential measurement.

[0129] The above S104 conceptually describes the basic principles and operation methods of the three paths. The following section will combine... Figure 3 and Figure 4 The flowcharts detail the specific operational steps of the isobaric refractive index gas thermometry method / isorefractive index gas thermometry method and the generalized gas refractive index thermometry method, so that those skilled in the art can directly implement the above measurement schemes based on the flowcharts.

[0130] The following is combined with Figure 3This invention describes the specific operation flow of the isobaric refractive index gas thermometry method and the isobaric refractive index gas thermometry measurement method provided in the embodiments of the present invention.

[0131] Figure 3 This invention provides an isobaric refractive index gas thermometry method and a flowchart of the measurement method. (See attached diagram.) Figure 3 As shown, the method includes the following steps: S301. Measuring vacuum resonant frequency .

[0132] For example, after evacuating the microwave resonant cavity, the resonant frequency under vacuum is measured using a microwave frequency measurement system, which serves as the frequency reference for subsequent calculations of the refractive index.

[0133] S302. Measuring the microwave resonant frequency of the reference state. .

[0134] For example, the system temperature is stabilized at a reference thermodynamic temperature. Fill the cavity with working gas to the reference gas pressure. The microwave resonant frequency under this reference state is measured.

[0135] S303. Calculate the experimental refractive index under the reference condition. and theoretical refractive index .

[0136] For example, the experimental refractive index is calculated based on the vacuum resonant frequency and the reference state resonant frequency, while the theoretical refractive index is calculated based on the virial equation and the Lorentz-Lorentz formula.

[0137] S304. Calculate the experimental refractive index under the reference condition. and theoretical refractive index ratio .

[0138] For example, dividing the theoretical refractive index by the experimental refractive index yields the relative ratio constant. .

[0139] S305, Maintaining Pressure exist The location remains unchanged.

[0140] For example, the gas pressure inside the cavity is maintained at a reference gas pressure by a gas pressure control system. nearby.

[0141] S306. Adjust the temperature to the temperature of the point to be measured. .

[0142] For example, the temperature of the microwave resonant cavity is adjusted to the initial estimated value of the temperature to be measured by a temperature control system. .

[0143] S307. Measure the resonant frequency at the temperature of the point to be measured. .

[0144] For example, after the temperature stabilizes, the microwave resonant frequency under the current state is measured. .

[0145] S308. Objective: Maintain .

[0146] For example, the experimental refractive index of the test state is equal to that of the experimental refractive index of the reference state as the control target of the isorheological method for gas thermometry.

[0147] S309. Adjust the temperature to the temperature of the point to be measured. .

[0148] For example, the temperature of the microwave resonant cavity is adjusted to the initial estimated value of the temperature to be measured by a temperature control system. .

[0149] S310, Adjusting gas pressure This makes the measured frequency The target resonant frequency at the temperature to be measured .

[0150] For example, the gas pressure is adjusted so that the measured microwave resonant frequency reaches the target resonant frequency.

[0151] S311, calculate separately Experimental refractive index and theoretical refractive index .

[0152] For example, the experimental refractive index is calculated based on the measured microwave resonant frequency, while the theoretical refractive index is calculated based on the virial equation and the Lorentz-Lorentz formula.

[0153] S312, Calculate the deviation .

[0154] For example, the absolute value of the difference between the theoretical refractive index and the relative ratio constant multiplied by the experimental refractive index is calculated.

[0155] S313. Deviation < Tolerance? If yes, proceed to S315; otherwise, proceed to S314.

[0156] For example, it is determined whether the deviation is less than a preset allowable error.

[0157] S314. Adjust the temperature of the point to be measured. Recalculate And execute S312.

[0158] For example, if the deviation does not meet the convergence condition, the temperature estimate is adjusted. Return to S312 to recalculate.

[0159] S315, Output As the high-accuracy thermodynamic temperature to be measured .

[0160] For example, when the deviation is less than the preset tolerance error, the output is... As the final thermodynamic temperature.

[0161] Thus, this invention effectively avoids the resonant cavity deformation error caused by pressure changes by using the isobaric refractive index gas thermometry method to measure the temperature at multiple points under constant pressure. At the same time, by using the isobaric refractive index gas thermometry method to convert low-temperature and low-pressure measurements into comparisons with high-pressure reference points, the problem of insufficient accuracy in absolute pressure measurements in the low-temperature region is avoided.

[0162] The following is combined with Figure 4 This invention describes the specific operation process of the generalized gas refractive index thermometry method provided in the embodiments of the present invention.

[0163] Figure 4 This is a flowchart of a generalized gas refractive index thermometry method provided by an embodiment of the present invention. Figure 4 As shown, the method includes the following steps: S401, Temperature reaches the target temperature. A certain amount of gas is then introduced.

[0164] For example, the temperature of the microwave resonant cavity is stabilized at the temperature to be measured. Then, working gas is introduced into the cavity.

[0165] S402, Measuring the temperature to be measured Microwave resonant frequency .

[0166] For example, adjust the pressure to the first pressure point. The microwave resonant frequency under this condition is measured.

[0167] S403, Measure the microwave resonant frequency under another pressure. .

[0168] For example, keeping the temperature constant, the pressure is changed to a second pressure point. The microwave resonant frequency under this condition is measured.

[0169] S404. Calculate the experimental refractive index under two pressures. ratio .

[0170] For example, the experimental refractive indexes at the two pressure points are calculated separately, and the ratio between the two is calculated. .

[0171] S405, Calculate the theoretical refractive index respectively. , .

[0172] For example, with the temperature to be measured Using as the variable, calculate the theoretical refractive index corresponding to the two pressure points respectively.

[0173] S406, Calculate the deviation .

[0174] For example, the deviation between the theoretical refractive index ratio and the experimental refractive index ratio is calculated.

[0175] S407. Deviation < Tolerance? If yes, proceed to S409; otherwise, proceed to S408.

[0176] For example, it is determined whether the deviation is less than a preset allowable error.

[0177] S408, Adjust the temperature of the point to be measured. And execute S405.

[0178] For example, if the deviation does not meet the convergence condition, adjust the temperature. Return to S405 to recalculate.

[0179] S409, Output As the high-accuracy thermodynamic temperature to be measured .

[0180] For example, when the deviation is less than the preset tolerance error, the output is... As the final thermodynamic temperature.

[0181] Thus, this invention performs differential measurements of two pressure points at a single temperature by using the generalized gas refractive index thermometry method. It uses the equality of the experimental refractive index ratio and the theoretical refractive index ratio of the two states at the same temperature as an iterative constraint, achieving absolute temperature measurement without relying on an external reference thermodynamic temperature. At the same time, since the measurements of the two pressure points are performed at the same temperature, the common-mode error caused by vacuum frequency drift is automatically canceled in the ratio calculation, eliminating the influence of vacuum frequency reference instability on temperature measurement accuracy.

[0182] S105. Obtain the experimental refractive index and the theoretical refractive index under the test conditions.

[0183] In some embodiments, a microwave resonant cavity can be used to measure the second resonant frequency under the test state.

[0184] For example, after the state to be tested is established, the resonant frequency of the microwave resonant cavity in the current state is measured using a microwave frequency measurement system.

[0185] Specifically, the measurement method for the second resonant frequency is similar to that for the first resonant frequency, both performed using a microwave frequency measurement unit. During measurement, it is essential to ensure the system temperature has stabilized to obtain accurate frequency data.

[0186] Furthermore, the refractive index of the experiment under test is calculated based on the reference resonant frequency, the second resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

[0187] For example, the refractive index of the test experiment is calculated in the same way as that of the reference experiment, both based on the ratio of the vacuum resonant frequency to the resonant frequency in the gas-filled state, and corrected by the isothermal compressibility coefficient.

[0188] Specifically, the refractive index of the experiment to be measured The calculation formula is as follows: .

[0189] in, The resonant frequency under vacuum conditions. This is the resonant frequency in the inflated state. For gas pressure, For the resonator at temperature Isothermal compressibility (unit: Pascal, 1 / Pa). The refractive index is used in the experiment.

[0190] Thus, by unifying the experimental refractive index calculation method, this invention ensures the comparability of experimental data between the reference state and the state to be tested, providing reliable experimental input for the ratio constraint iterative solution.

[0191] In other embodiments, the molar density of the working gas in the test state can be determined.

[0192] For example, based on the pressure under the test state and temperature The molar density under this state is determined by the working gas law. .

[0193] Specifically, the method for determining molar density is consistent under both the reference state and the test state, both based on the virial equation. The difference lies in the fact that temperature and pressure under the test state are measured or initially estimated, requiring continuous correction through iterative calculations.

[0194] Furthermore, based on the molar density under the test conditions and the dielectric and magnetic virial coefficients of the working gas, the theoretical refractive index to be tested is calculated using the virial equation and the Lorentz-Lorentz formula.

[0195] For example, the theoretical refractive index to be measured The calculation formula is as follows: .

[0196] Among them, the parameters are: molar density virial coefficients , , , The parameter system used in the refractive index calculation is consistent with that used in the reference theory, except for the molar density. The value varies with the pressure and temperature of the measured state.

[0197] Specifically, the temperature under the state to be measured and pressure Substitute into the virial equation to solve for the molar density Then Substituting these values ​​into the Lorentz-Lorentz formula yields the theoretical refractive index to be measured. This theoretical refractive index is determined by temperature. The function, during the iteration process It is constantly being adjusted and updated.

[0198] Thus, by using a unified theoretical refractive index calculation method, this invention ensures the comparability of theoretical data between the reference state and the state to be measured, providing reliable theoretical input for the ratio constraint iterative solution.

[0199] S106. Using the relative ratio constant as a constraint, the value of the thermodynamic temperature to be measured is adjusted through iterative calculation to make the ratio of the theoretical refractive index to be measured to the experimental refractive index to be measured approach the relative ratio constant until the deviation is less than the preset allowable error. The converged temperature value is then determined as the thermodynamic temperature to be measured.

[0200] In some embodiments, the core of the iterative solution is to make the ratio of the theoretical refractive index to the experimental refractive index in the test state equal to the ratio in the reference state. .

[0201] For example, the deviation is calculated: .

[0202] If there is a deviation If the error is less than the preset tolerance, then output... To finally measure the thermodynamic temperature If the deviation is too large, adjust accordingly. Return to S105 to recalculate the experimental and theoretical refractive indices under the test conditions until convergence.

[0203] Specifically, the iterative solution process is as follows: First, set the initial estimated value of the temperature to be measured. Based on this temperature value and current pressure Calculate the refractive index of the experiment to be tested respectively. and the theoretical refractive index to be measured Then calculate the deviation. .like If the error is less than the preset tolerance, then convergence is determined, and the result is output. As the final thermodynamic temperature. If If the convergence condition is not met, adjust according to the direction and magnitude of the deviation. Then recalculate until the convergence condition is met.

[0204] For example, the preset tolerance error can be set to 1×10. -6 Alternatively, other values ​​may be determined based on the required measurement accuracy.

[0205] For example, if Then appropriately reduce Conversely, increase the appropriate level. .

[0206] In the generalized gas refractive index thermodynamic temperature measurement method provided by this invention, a reference state under a known reference thermodynamic temperature and reference gas pressure is introduced. At the experimental level, a reference experimental refractive index is obtained; at the theoretical level, a reference theoretical refractive index is obtained, and a relative ratio constant between the two is established. This relative ratio constant serves as a unified constraint benchmark for subsequent iterative solutions. This transforms the dependence on the absolute values ​​of pressure and cavity deformation parameters in traditional absolute refractive index temperature measurement into tracking the ratio relationship between the measured state and the reference state, thereby eliminating the influence of absolute pressure measurement errors on the temperature measurement results. Furthermore, by establishing the measured state and obtaining its measured experimental refractive index... The ratio of the theoretical refractive index to the experimental refractive index is used as a constraint for iterative solution, making the ratio of the theoretical refractive index to the experimental refractive index under the measured state approximate this constant. This iterative solution mechanism can automatically cancel out common errors in microwave resonant frequency measurement, such as system drift and slow changes in resonant cavity geometry, in the ratio calculation, thereby effectively eliminating system errors introduced by resonant cavity deformation. Finally, by determining the converged temperature value as the thermodynamic temperature to be measured, the temperature measurement problem is transformed into a frequency ratio approximation problem, making full use of the physical advantage of high accuracy in frequency measurement, and thus realizing high-accuracy thermodynamic temperature measurement in the low-temperature region.

[0207] In another embodiment of the present invention, a multi-path cross-validation temperature measurement strategy is also included.

[0208] For example, under the same experimental system, multiple measurements can be performed on the same state point by combining measurement paths such as isobaric refractive index gas thermometry, isorefractive index gas thermometry, generalized gas refractive index thermometry, and generalized gas refractive index thermometry.

[0209] Specifically, by comparing temperature measurement results under different paths, the accuracy and consistency of experimental data can be cross-validated, providing a basis for evaluating the reliability of measurement results.

[0210] It should be noted that, in addition to measuring thermodynamic temperature, the method provided by this invention can also be used to measure gas density, pressure, or retrieve gas thermophysical parameters such as polarizability and virial coefficient if the temperature is known.

[0211] In this embodiment of the invention, under known and accurate temperature conditions, high-precision refractive index data can be obtained by using the relative measurement method of the present invention, and thermophysical parameters such as working gas polarizability or higher-order virial coefficients can be obtained by inversion calculation.

[0212] Figure 5 This is a schematic diagram of a generalized gas refractive index thermodynamic temperature measuring device provided by an embodiment of the present invention. Figure 5 As shown, the device includes: a reference state establishment module 501, a reference refractive index acquisition and ratio determination module 502, a test state establishment module 503, a test refractive index acquisition module 504, and a temperature iterative solution module 505.

[0213] The system includes the following modules: a reference state establishment module 501, which establishes a reference state where the working gas is at a known reference thermodynamic temperature and a known reference gas pressure; a reference refractive index acquisition and ratio determination module 502, which acquires the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determines a relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index, the relative ratio constant representing the ratio of the theoretical refractive index to the experimental refractive index under the reference state; a test state establishment module 503, which establishes a test state where the working gas is at the test thermodynamic temperature; a test refractive index acquisition module 504, which acquires the test experimental refractive index and the test theoretical refractive index under the test state; and a temperature iterative solution module 505, which uses the relative ratio constant as a constraint to iteratively calculate and adjust the test thermodynamic temperature value, making the ratio of the test theoretical refractive index to the test experimental refractive index approach the relative ratio constant, until the deviation is less than the preset allowable error, and then determines the converged temperature value as the test thermodynamic temperature.

[0214] In some embodiments, the reference refractive index acquisition and ratio determination module 502 is specifically used for: measuring the reference resonant frequency under vacuum conditions using a microwave resonant cavity; filling the microwave resonant cavity with working gas and establishing a reference state, measuring the first resonant frequency under the reference state; and calculating the reference experimental refractive index based on the reference resonant frequency, the first resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

[0215] In some embodiments, the refractive index acquisition module 504 is specifically used to: measure the second resonant frequency under the test state using a microwave resonant cavity; and calculate the experimental refractive index based on the reference resonant frequency, the second resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

[0216] In some embodiments, the reference refractive index acquisition and ratio determination module 502 is specifically used to: determine the molar density of the working gas under a reference state; and calculate the reference theoretical refractive index using the virial equation and the Lorentz-Lorentz formula based on the molar density under the reference state and the dielectric virial coefficient and magnetic susceptibility virial coefficient of the working gas.

[0217] In some embodiments, the refractive index acquisition module 504 is specifically used to: determine the molar density of the working gas in the test state; and calculate the theoretical refractive index to be measured using the virial equation and the Lorentz-Lorentz formula based on the molar density in the test state and the dielectric virial coefficient and magnetic susceptibility virial coefficient of the working gas.

[0218] In some embodiments, the test state establishment module 503 is specifically used to: maintain the gas pressure in the test state to be equal to the reference gas pressure through the gas pressure control system; adjust the temperature of the test state to the test thermodynamic temperature while the gas pressure is kept constant; and perform the measurement under isothermal conditions, that is, change the gas pressure to two or more different pressure points while the temperature is kept constant.

[0219] In some embodiments, the generalized gas refractive index thermodynamic temperature measuring device provided by the present invention further includes: a temperature determination module, used to measure the microwave resonant frequency of the microwave resonant cavity at multiple different test temperatures while maintaining the gas pressure at a level equal to the reference gas pressure; and to solve for the thermodynamic temperature at each test temperature based on the experimental refractive index versus temperature relationship at each test temperature.

[0220] In some embodiments, the test state establishment module 503 is specifically used to: adjust the temperature of the test state to the test thermodynamic temperature; adjust the gas pressure in the test state and monitor the real-time resonant frequency of the microwave resonant cavity until the real-time resonant frequency reaches the target resonant frequency corresponding to the reference experimental refractive index, and the test experimental refractive index in the test state is equal to the reference experimental refractive index.

[0221] In some embodiments, the generalized gas refractive index thermodynamic temperature measuring device provided by the present invention further includes: a resonant frequency determination module, used to calculate the target resonant frequency based on the reference experimental refractive index, the reference resonant frequency and the isothermal compressibility coefficient of the microwave resonant cavity.

[0222] In some embodiments, the test state establishment module 503 is specifically used for: maintaining the temperature of the test state at a single test thermodynamic temperature; acquiring the experimental resonant frequencies corresponding to at least two different gas pressure points at the single test thermodynamic temperature; calculating the test refractive index ratio based on the experimental resonant frequencies corresponding to the at least two different gas pressure points; using the test thermodynamic temperature as a variable, calculating the theoretical refractive index corresponding to the at least two different gas pressure points, and calculating the theoretical refractive index ratio; and iteratively solving for the test thermodynamic temperature with the theoretical refractive index ratio being equal to the test refractive index ratio as a constraint.

[0223] In some embodiments, the test state establishment module 503 is specifically used to calculate the refractive index ratio to be tested based on the reference resonant frequency under vacuum conditions obtained by measuring with a microwave resonant cavity and the experimental resonant frequencies corresponding to at least two different gas pressure points.

[0224] In this embodiment of the invention, the above modules can be integrated into the same physical device or distributed across different devices and work collaboratively through communication connections. The specific implementation of each module can employ various methods, such as hardware circuits, programmable logic devices, or microprocessors running software programs; this invention does not impose any limitations on these methods.

[0225] Figure 6 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 6 As shown, the electronic device may include: a processor 610, a communications interface 620, a memory 630, and a communications bus 640, wherein the processor 610, the communications interface 620, and the memory 630 communicate with each other through the communications bus 640.

[0226] The processor 610 can call logic instructions in the memory 630 to execute a generalized gas refractive index thermodynamic temperature measurement method. This method includes: establishing a reference state, where the working gas is at a known reference thermodynamic temperature and a known reference gas pressure; acquiring the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determining a relative ratio constant based on the reference experimental and reference theoretical refractive indices, where the relative ratio constant characterizes the ratio between the theoretical and experimental refractive indices under the reference state; establishing a test state, where the working gas is at the test thermodynamic temperature; acquiring the test experimental refractive index and the test theoretical refractive index under the test state; using the relative ratio constant as a constraint, iteratively calculating and adjusting the value of the test thermodynamic temperature to make the ratio of the test theoretical refractive index to the test experimental refractive index approach the relative ratio constant until the deviation is less than a preset allowable error, and determining the converged temperature value as the test thermodynamic temperature.

[0227] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0228] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the generalized gas refractive index thermodynamic temperature measurement method provided by the above methods. The method includes: establishing a reference state, wherein the reference state is the state of the working gas under a known reference thermodynamic temperature and a known reference gas pressure; obtaining the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determining a relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index, wherein the relative ratio constant characterizes the ratio relationship between the theoretical refractive index and the experimental refractive index under the reference state; establishing a test state, wherein the test state is the state of the working gas under the test thermodynamic temperature; obtaining the test experimental refractive index and the test theoretical refractive index under the test state; using the relative ratio constant as a constraint, adjusting the value of the test thermodynamic temperature through iterative calculation, so that the ratio of the test theoretical refractive index to the test experimental refractive index approaches the relative ratio constant, until the deviation is less than a preset allowable error, and determining the converged temperature value as the test thermodynamic temperature.

[0229] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements a generalized gas refractive index thermodynamic temperature measurement method provided by the methods described above. This method includes: establishing a reference state, where the working gas is at a known reference thermodynamic temperature and a known reference gas pressure; acquiring a reference experimental refractive index and a reference theoretical refractive index under the reference state, and determining a relative ratio constant based on the reference experimental and reference theoretical refractive indices, where the relative ratio constant characterizes the ratio between the theoretical and experimental refractive indices under the reference state; establishing a test state, where the working gas is at a test thermodynamic temperature; acquiring the test experimental refractive index and the test theoretical refractive index under the test state; using the relative ratio constant as a constraint, iteratively calculating and adjusting the value of the test thermodynamic temperature to make the ratio of the test theoretical refractive index to the test experimental refractive index approach the relative ratio constant until the deviation is less than a preset allowable error, and determining the converged temperature value as the test thermodynamic temperature.

[0230] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0231] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0232] 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 generalized method for measuring the thermodynamic temperature of gas refractive index, characterized in that, The method includes: Establish a reference state, which is the state of the working gas under a known reference thermodynamic temperature and a known reference gas pressure; Obtain the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determine the relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index. The relative ratio constant characterizes the ratio relationship between the theoretical refractive index and the experimental refractive index under the reference state. Establish a test state, wherein the test state is the state of the working gas at the test thermodynamic temperature; Obtain the experimental refractive index and the theoretical refractive index under the test state; Using the relative ratio constant as a constraint, the value of the thermodynamic temperature to be measured is adjusted through iterative calculation so that the ratio of the theoretical refractive index to the experimental refractive index to be measured approaches the relative ratio constant until the deviation is less than the preset allowable error. The converged temperature value is then determined as the thermodynamic temperature to be measured.

2. The method according to claim 1, characterized in that, Obtaining the reference experimental refractive index under the reference state includes: The reference resonant frequency under vacuum conditions was measured using a microwave resonant cavity. A working gas is introduced into the microwave resonant cavity to establish the reference state, and the first resonant frequency under the reference state is measured. The reference experimental refractive index is calculated based on the reference resonant frequency, the first resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

3. The method according to claim 2, characterized in that, The process of obtaining the refractive index of the experiment under the test state includes: The second resonant frequency under the test state is measured using the microwave resonant cavity. The refractive index of the experiment to be tested is calculated based on the reference resonant frequency, the second resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity at the current temperature.

4. The method according to claim 1, characterized in that, The reference theoretical refractive index is obtained through the following steps: Determine the molar density of the working gas under the reference state; The reference theoretical refractive index is calculated using the virial equation and the Lorentz-Lorentz formula based on the molar density under the reference state and the dielectric virial coefficient and magnetic susceptibility virial coefficient of the working gas.

5. The method according to claim 2, characterized in that, The theoretical refractive index to be measured is obtained through the following steps: Determine the molar density of the working gas under the test state; The theoretical refractive index to be measured is calculated using the virial equation and the Lorentz-Lorentz formula based on the molar density under the test state and the dielectric virial coefficient and magnetic susceptibility virial coefficient of the working gas.

6. The method according to claim 5, characterized in that, The establishment of the state to be tested includes: The gas pressure under the test state is maintained at the same level as the reference gas pressure by a gas pressure control system. While maintaining a constant gas pressure, the temperature of the state to be measured is adjusted to the thermodynamic temperature to be measured.

7. The method according to claim 6, characterized in that, The method further includes: While maintaining the gas pressure at the same level as the reference gas pressure, the microwave resonant frequency of the microwave resonant cavity was measured at multiple different test temperatures. The thermodynamic temperature at each test temperature is determined by calculating the relationship between the experimental refractive index and temperature at each test temperature.

8. The method according to claim 2, characterized in that, The establishment of the state to be tested includes: Adjust the temperature of the state to be measured to the thermodynamic temperature to be measured; The gas pressure in the test state is adjusted, and the real-time resonant frequency of the microwave resonant cavity is monitored until the real-time resonant frequency reaches the target resonant frequency corresponding to the reference experimental refractive index, and the test experimental refractive index in the test state is equal to the reference experimental refractive index.

9. The method according to claim 8, characterized in that, The method further includes: The target resonant frequency is calculated based on the reference experimental refractive index, the reference resonant frequency, and the isothermal compressibility coefficient of the microwave resonant cavity.

10. A generalized method for measuring the thermodynamic temperature of gas refractive index, characterized in that, The method includes: The temperature of the state to be measured is maintained at a single thermodynamic temperature to be measured, wherein the state to be measured is the state of the working gas at the thermodynamic temperature to be measured. At the single thermodynamic temperature to be measured, the experimental resonant frequencies corresponding to at least two different gas pressure points are obtained respectively; The ratio of the refractive index to be measured is calculated based on the experimental resonant frequencies corresponding to at least two different gas pressure points. Using the thermodynamic temperature to be measured as a variable, calculate the theoretical refractive index corresponding to each of the at least two different gas pressure points, and calculate the ratio of the theoretical refractive indices. The thermodynamic temperature to be measured is solved iteratively by using the theoretical refractive index ratio as a constraint that the ratio of the refractive index to be measured is equal to that of the refractive index to be measured.

11. The method according to claim 10, characterized in that, The at least two different gas pressure points include a first pressure point and a second pressure point, and the difference between the first pressure point and the second pressure point is less than a preset pressure threshold.

12. The method according to claim 10, characterized in that, The calculation of the refractive index ratio based on the experimental resonant frequencies corresponding to the at least two different gas pressure points includes: The ratio of the refractive index to be measured is calculated based on the reference resonant frequency under vacuum conditions obtained by microwave resonant cavity measurement and the experimental resonant frequencies corresponding to the at least two different gas pressure points.

13. A universal gas refractive index thermodynamic temperature measuring device, characterized in that, The device includes: A reference state establishment module is used to establish a reference state, which is the state of the working gas under a known reference thermodynamic temperature and a known reference gas pressure; The reference refractive index acquisition and ratio determination module is used to acquire the reference experimental refractive index and the reference theoretical refractive index under the reference state, and determine the relative ratio constant based on the reference experimental refractive index and the reference theoretical refractive index. The relative ratio constant characterizes the ratio relationship between the theoretical refractive index and the experimental refractive index under the reference state. The test state establishment module is used to establish the test state, wherein the test state is the state of the working gas at the test thermodynamic temperature; The module for obtaining the refractive index to be measured is used to obtain the experimental refractive index to be measured and the theoretical refractive index to be measured under the test state. The temperature iterative solution module is used to adjust the value of the thermodynamic temperature to be measured by iterative calculation with the relative ratio constant as a constraint condition, so that the ratio of the theoretical refractive index to the experimental refractive index to be measured approaches the relative ratio constant, until the deviation is less than the preset allowable error, and the converged temperature value is determined as the thermodynamic temperature to be measured.

14. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the generalized gas refractive index thermodynamic temperature measurement method as described in any one of claims 1 to 12.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the generalized gas refractive index thermodynamic temperature measurement method according to any one of claims 1 to 12.

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