Low-temperature directional emissivity test method and test system based on thermal radiation effect

Abstract

The invention discloses a low-temperature directional emissivity test method and test system based on a thermal radiation effect, and belongs to the technical field of space exploration. The test method comprises the following steps: establishing optical path connection between a thermal radiation change sensor and a radiation quantity adjusting device; a sample table comprising a blackbody cavity, a sample testing cavity and a reflector sample area is arranged in the radiation quantity adjusting device; the angle between the radiation quantity adjusting device and the emission light path is changed, and the radiation quantity emitted by the sample and obtained by the thermal radiation change sensor is adjusted; the thermal radiation change sensor obtains a detection signal corresponding to the change of the radiation quantity emitted by the received sample; and acquiring the emissivity of the sample based on the detection signal. The radiation quantity adjusting device is used for adjusting the radiation quantity emitted by the sample and obtained by the thermal radiation change sensor, the thermal radiation change sensor can measure the emissivity, and compared with a method for calculating the emissivity by measuring the absolute value of temperature and the like in the prior art, the method has higher precision and reliability.

Description

Technical Field

[0001] The present invention relates to the field of space detection technology, and in particular to a low-temperature directional emissivity testing method and testing system based on thermal radiation effect. Background Art

[0002] In deep space exploration missions, in order to keep the internal temperature of the spacecraft within the normal operating temperature range of the instrument components, it is necessary to accurately measure the low-temperature emissivity of the spacecraft surface, so as to evaluate the internal heat generation of the spacecraft required to maintain the temperature range. The existing emissivity measurement methods are mainly divided into calorimetry, energy method and reflection method.

[0003] The calorimetric method is mainly used to measure the high-temperature hemispherical total emissivity of metal materials. The hemispherical emissivity of the metal sample is calculated by heating the metal sample with electricity, measuring the sample's temperature and the electric power generated by the sample. On the one hand, the calorimetric method can only measure metal materials, which limits its scope of application. On the other hand, the current and voltage values ​​of the sample at extremely low temperatures are low, and the measurement error is large. Therefore, the calorimetric method is difficult to meet the requirements for accurate measurement of the low-temperature emissivity of the aircraft surface at low temperatures (space close to absolute zero).

[0004] The energy method and the reflection method currently rely on the Fourier spectrometer. On the one hand, when the sample is at a low temperature, the radiation spectrum of the sample collected by the spectrometer's DTGS, MCT-B, and InGaAs sensors is completely covered by the room temperature environment signal and cannot be collected, making it impossible to achieve the measurement of the energy method and the reflection method. On the other hand, when measuring the reflection method, the spectrometer needs to be placed in a low-temperature vacuum environment, and the spectrometer cannot work under this condition. Therefore, the energy method and the reflection method cannot meet the requirements for accurate measurement of the low-temperature emissivity of the aircraft surface at low temperatures (space close to absolute zero).

[0005] Therefore, there is an urgent need in the art for an emissivity testing method and a testing system that can accurately measure the low-temperature emissivity of an aircraft surface at low temperatures. Summary of the invention

[0006] In view of the above analysis and in response to the shortcomings of the prior art, the present invention aims to provide a low-temperature directional emissivity test method and test system based on thermal radiation effect, so as to solve the problem that the prior art cannot accurately measure the low-temperature emissivity of the aircraft surface at low temperatures near absolute zero.

[0007] The purpose of the present invention is mainly achieved through the following technical solutions:

[0008] Establishing an optical path connection between the thermal radiation change sensor and the radiation amount regulating device;

[0009] A sample stage including a black body cavity, a sample test chamber and a reflector sample area is arranged in the radiation amount adjusting device;

[0010] Changing the angle between the radiation amount adjusting device and the emission light path to adjust the radiation amount emitted by the sample acquired by the thermal radiation change sensor;

[0011] The thermal radiation change sensor obtains a detection signal corresponding to a change in the amount of radiation emitted by the sample it receives;

[0012] The emission rate of the sample is obtained based on the detection signal.

[0013] Preferably, the thermal radiation change sensor obtains a detection signal corresponding to a change in the amount of radiation emitted by the sample received by the sensor, including:

[0014] Detection signal when the measurement area is a black body, a reflector and a sample to be measured at a target temperature under a vacuum environment;

[0015] The emissivity of the sample at the target temperature is obtained based on the detection signal.

[0016] Preferably, when the measurement area is measured to be a black body, a reflector and a sample to be measured at the target temperature, the detection signal includes:

[0017] Adjust the angle between the radiation amount adjusting device and the emission light path of the sample to a, so that the input radiation amount of the thermal radiation change sensor changes, and obtain the voltage change difference ΔU of the sample to be tested;

[0018] Adjust the angle between the radiation adjustment device and the emission light path of the sample to a, so that the input radiation of the thermal radiation change sensor changes, and obtain the black body cavity voltage change difference ΔU 黑 ;

[0019] Adjust the angle between the radiation adjustment device and the emission light path of the sample to a, so that the input radiation of the thermal radiation change sensor changes, and obtain the reflector voltage change difference ΔU 镜 .

[0020] Preferably, a>90°.

[0021] Preferably, when the measurement area is measured to be a black body, a reflector and a sample to be measured at the target temperature, the detection signal further comprises: adjusting the temperature of the measurement area to the target temperature by adopting multi-stage refrigeration.

[0022] Preferably, the cooling medium of the measuring area is liquid helium.

[0023] Preferably, acquiring the emissivity based on the detection signal comprises: connecting the cooling medium and the measuring area via a flexible high thermal conductivity material to achieve indirect cooling.

[0024] Preferably, obtaining the emissivity based on the detection signal comprises: based on or Get ε A ; where ε A is the emissivity of the sample to be tested, ε1 is the emissivity of the blackbody cavity, and ε0 is the emissivity of the reflector sample area.

[0025] Preferably, based on Get ε A .

[0026] A low-temperature directional emissivity test system based on thermal radiation effect, used in the above test method, comprises: a thermal radiation change sensor and a radiation amount adjustment device connected by an optical path;

[0027] The radiation amount adjusting device can adjust the radiation amount emitted by the sample acquired by the thermal radiation change sensor;

[0028] The radiation amount adjusting device is arranged with a rotating shaft perpendicular to the emission light path of the sample, and can rotate around the rotating shaft to change the angle between itself and the emission light path.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] (1) The present invention uses a radiation amount adjusting device to adjust the radiation amount emitted by the sample obtained by the thermal radiation change sensor, thereby realizing the thermal radiation change sensor to measure the emissivity. Compared with the prior art method of calculating the emissivity by measuring the absolute value of temperature, the present invention has higher accuracy and reliability.

[0031] (2) The present invention detects thermal radiation changes based on a thermal radiation change sensor. The detection sample is not limited to metals, and the output detection signal is related to the change in thermal radiation migration and has nothing to do with temperature. Therefore, it still has good detection accuracy at low temperatures.

[0032] (3) The present invention introduces the test data of a black body and a reflector at the same temperature based on the change in thermal radiation. Since the same background radiation at the same temperature is included, the same background radiation is deducted in the calculation formula. Therefore, compared with the prior art, the present invention has the advantage of not being affected by background radiation.

[0033] (4) The present invention adopts a bolometer sensor, which can adapt to liquid nitrogen temperature or even liquid helium temperature, which is close to the space temperature environment, thereby avoiding the defect that the traditional Fourier infrared detection equipment is difficult to apply to the extremely low temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0035] Figure 1 This is a schematic diagram of the overall structure of a low-temperature directional emissivity testing system in one embodiment of the present invention;

[0036] Figure 2 A partial enlarged view of a motion control module in one embodiment of the present invention;

[0037] Figure 3 This is a front view of a sample stage 005 in one embodiment of the present invention;

[0038] Figure 4 It is a cross-sectional view of the sample stage 005A-A plane in one embodiment of the present invention.

[0039] Reference numerals:

[0040] Radiation amount adjustment device 001, thermal radiation change sensor 002;

[0041] Cold screen 003, first refrigeration unit 11, second refrigeration unit 12;

[0042] Temperature sensor 007;

[0043] Cold head 1101, first connection part 1102, first refrigerant storage tank 1201, second refrigerant storage tank 1202;

[0044] Vacuum chamber 004;

[0045] Sample stage 005, sample test chamber 051, black body cavity 052, reflector sample area 053, heating device 054;

[0046] An optical path transmission unit 1313, a first off-axis parabolic mirror 1301, a second off-axis parabolic mirror 1302, and a plane reflector 1303;

[0047] First motion unit 1414;

[0048] The second motion unit 15, the second motion unit fixed end 1501, the second motion unit motion end 1502;

[0049] The third motion unit 16, a fixed base 1601, a rotating connection part 1602, a supporting connection structure 1603; a rotor part 1602a, and a stator part 1602b. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0051] About technical terms

[0052] Bold

[0053] Reflectivity ≈ 0, emissivity ≈ 1, an object that absorbs almost all radiation and re-emits it.

[0054] Ideal reflector

[0055] An object with reflectivity ≈ 1 and emissivity ≈ 0 will reflect almost all radiation.

[0056] The present invention discloses a low-temperature emissivity testing method based on thermal radiation effect, comprising:

[0057] Establishing an optical path connection between the thermal radiation change sensor and the radiation amount regulating device;

[0058] A sample stage including a black body cavity, a sample test chamber and a reflector sample area is arranged in the radiation amount adjusting device;

[0059] Changing the angle between the radiation amount adjusting device and the emission light path to adjust the radiation amount emitted by the sample acquired by the thermal radiation change sensor;

[0060] The thermal radiation change sensor obtains a detection signal corresponding to a change in the amount of radiation emitted by the sample it receives;

[0061] The emission rate of the sample is obtained based on the detection signal.

[0062] During implementation, after establishing an optical path connection between the thermal radiation change sensor 002 and the radiation amount adjusting device 001, the radiation amount adjusting device 001 is adjusted to change the radiation amount emitted by the sample received by the thermal radiation change sensor 002. Based on the change in radiation amount, the thermal radiation change sensor 002 obtains a corresponding electrical signal, and then obtains the emissivity of the sample at that temperature.

[0063] Specifically, Figure 1-Figure 4 As shown, in order to realize low-temperature emissivity testing and provide a controllable temperature environment for the emission area of ​​the sample and the thermal radiation change sensor 002, the temperature environment of the emission area of ​​the sample and the thermal radiation change sensor 002 is further controlled by a temperature control module.

[0064] During implementation, the temperature control module is adjusted so that the emission area of ​​the sample and the thermal radiation change sensor 002 are at the target temperature, and the radiation amount adjustment device 001 is adjusted to change the radiation amount emitted by the sample received by the thermal radiation change sensor 002, and an electrical signal corresponding to the change in radiation amount is obtained based on the thermal radiation change sensor 002, thereby obtaining the emissivity of the sample at this temperature.

[0065] Specifically, it is necessary to use the thermal radiation change sensor 002 to obtain the peak-to-valley voltage difference ΔU of the sample and the peak-to-valley voltage difference ΔU of the black body when the radiation amount adjustment device 001 has the same adjustment amount. 黑 , the peak-to-valley voltage difference of the reflector ΔU 镜 ; emissivity of the sample at the target temperature ε A satisfy:

[0066] Among them, ε1 is the emissivity of the black body; ε0 is the emissivity of the reflector sample area.

[0067] It should be noted that the thermal radiation change sensor is an emissivity measurement device based on thermal radiation changes. It cannot measure the absolute value of the radiation, but can measure the change in the radiation. The output voltage signal of the thermal radiation change sensor 002 is proportional to the difference in the input radiation change.

[0068] Specifically, the thermal radiation change sensor 002 may be a bolometer sensor, which can directly measure the amount of thermal radiation migration during the thermal radiation process, and the detection accuracy is not affected by temperature.

[0069] Compared with the prior art, the present invention provides a thermal radiation change sensor and a radiation amount adjusting device connected by an optical path. The radiation amount adjusting device can adjust the radiation emitted by the sample acquired by the thermal radiation change sensor, thereby realizing the emissivity measurement of the thermal radiation change sensor. Compared with the prior art method of calculating the emissivity by measuring absolute values ​​such as temperature, the present invention has higher accuracy and reliability.

[0070] Compared with the prior art, the present invention detects thermal radiation changes based on the thermal radiation change sensor 002. The detection sample is not limited to metal, and the output detection signal is related to the change in thermal radiation migration and has nothing to do with temperature. Therefore, it still has good detection accuracy at low temperatures.

[0071] Compared with the prior art, the present invention adopts a bolometer sensor, which can adapt to liquid nitrogen temperature or even liquid helium temperature and other temperature environments close to space temperature, avoiding the defect that Fourier infrared detection equipment in traditional technologies is difficult to adapt to extremely low temperature environments.

[0072] Specifically, the low temperature emissivity test system also includes a motion control module. Under the control of the motion control module, the angle of the radiation amount adjustment device 001 relative to the sample emission light path changes, thereby causing the radiation amount emitted by the sample received by the thermal radiation change sensor 002 to change.

[0073] Specifically, the radiation amount adjusting device 001 may be a chopper.

[0074] It should be noted that the chopper in this field can modulate the optical radiation and remove the background and noise in the system.

[0075] Compared with the prior art, the present invention uses a chopper to not only output adjustable reflected radiation for the thermal radiation change sensor 002, but also effectively remove the background radiation interference of low-temperature space, thereby improving the detection accuracy.

[0076] Specifically, the motion control module includes a first motion mechanism, and the radiation amount adjustment device 001 reciprocates around the rotation axis from a direction perpendicular to the light path to a direction parallel to the light path under the action of the first motion mechanism.

[0077] Specifically, the temperature control module includes a first refrigeration unit 11 and a second refrigeration unit 12 which are separately disposed; the first refrigeration unit 11 provides a low temperature environment for the sample emission area, and the second refrigeration unit 12 provides a low temperature environment for the thermal radiation change sensor 002 .

[0078] Preferably, the temperature control module also includes a cold screen 003, the first refrigeration unit 11 includes a cold head 1101, and the cold head 1101 and the sample emission area are arranged in the cold screen 003 to reduce the heat exchange caused by thermal radiation; the low-temperature emissivity test system also includes a vacuum module, the cold screen 003 and the internal sample emission area, and the first refrigeration unit 11 are arranged in a vacuum chamber 004 of the vacuum module; the heat exchange method between the first refrigeration unit 11 and the sample emission area includes: heat conduction and thermal radiation, which can realize cooling of the sample emission area.

[0079] Specifically, the first refrigeration unit 11 is connected to the sample emission area through a metal material with good heat conduction.

[0080] Preferably, the metal material may be copper. Preferably, the metal material may be oxygen-free copper, and the room temperature thermal conductivity may reach 400 W / mK.

[0081] During implementation, the vacuum module provides a vacuum environment for the cold screen 003 and the sample emission area inside it, and the first refrigeration unit 11, reducing the heat exchange path between the first refrigeration unit 11 and the outside world in the form of heat conduction through the air through the outer wall of the vacuum chamber 004 of the vacuum module; at the same time, the cold screen 003 can effectively reflect external thermal radiation, reducing the heat exchange between the first refrigeration unit 11 in the cold screen 003 and the outside world in the form of thermal radiation, thereby achieving good refrigeration and heat preservation effects in the cold screen 003; at the same time, the first refrigeration unit 11 and the sample emission area are connected by materials with good heat conduction, so that the first refrigeration unit 11 and the sample emission area can be efficiently exchanged with each other in the form of heat conduction, and the sample emission area can be cooled.

[0082] Compared with the prior art, the use of the cold shield 003 under vacuum conditions can reduce the heat exchange of heat conduction and heat radiation at the same time, and improve the cooling effect of the system.

[0083] Specifically, the first refrigeration unit 11 also includes a primary refrigeration device and a secondary refrigeration device; the refrigeration medium of the secondary refrigeration device is connected to the cold head 1101 for cooling the cold head 1101; the primary refrigeration device is used to cool the secondary refrigeration device and discharge the heat generated by the secondary refrigeration device.

[0084] Preferably, the primary refrigeration device is a water-cooled machine whose refrigeration medium is water; and the secondary refrigeration device has helium as the refrigeration medium.

[0085] It is understandable that helium, as the common gas with the lowest liquefaction point (the liquefaction point can reach 4K), is suitable for use as a refrigerant medium close to absolute zero. In addition, helium is an expensive rare gas and can only be used as a refrigerant in a closed heat exchange manner. Using water with a larger specific heat capacity as the heat exchange medium between helium and the outside world can greatly improve the heat exchange efficiency between helium and the outside world.

[0086] Specifically, the second refrigeration unit 12 is provided with a first refrigerant medium storage tank 1201 and a second refrigerant medium storage tank 1202 from near to far from the thermal radiation change sensor 002 , and the temperature of the refrigerant in the first refrigerant medium storage tank 1201 is lower than that in the second refrigerant medium storage tank 1202 .

[0087] Specifically, the refrigerant in the first refrigerant storage tank 1201 may be liquid helium, and the refrigerant in the second refrigerant storage tank 1202 may be liquid nitrogen.

[0088] Preferably, the first refrigerant medium storage tank 1201 and the second refrigerant medium storage tank 1202 may be Dewar tanks.

[0089] During implementation, the thermal radiation change sensor 002 and the first refrigerant medium storage tank 1201 and the second refrigerant medium storage tank 1202 are all provided with connectable and disconnectable connecting gas paths. The medium in the second refrigerant medium storage tank 1202 is first used to lower the temperature to a certain temperature, and then the medium in the first refrigerant medium storage tank 1201 is used to cool the thermal radiation change sensor 002 to a lower temperature.

[0090] Specifically, the vacuum module also includes a primary vacuum pump, a secondary vacuum pump and a vacuum gauge; all three are connected to the vacuum chamber 004, wherein the upper vacuum limit of the secondary vacuum pump is higher than that of the primary vacuum pump.

[0091] During implementation, after the vacuum chamber 004 is sealed, a primary vacuum pump is used to evacuate the chamber to obtain a certain vacuum degree, and then a secondary vacuum pump is used to obtain a higher vacuum degree.

[0092] Specifically, the primary vacuum pump may be a mechanical pump; and the secondary vacuum pump may be a molecular pump.

[0093] Specifically, the measurement module is further provided with an optical path transmission unit 13. After the sample is emitted, the radiation is propagated in the optical path transmission unit 13 and connects the sample emission area, the radiation amount adjustment device 001, and the thermal radiation change sensor 002 through an optical path.

[0094] Specifically, the optical path transmission unit 13 includes two off-axis parabolic mirrors and at least one plane reflector 1303; the focus of the first off-axis parabolic mirror 1301 is located at the center of the sample, and is used to collect the divergent radiation emitted by the sample and convert it into parallel light. The parallel light is collected by the plane reflector 1303 and then reflected and transmitted to the next plane reflector 1303. The last plane reflector 1303 in the optical path is transmitted to the first off-axis parabolic mirror 1301, focusing the light radiation on the thermal radiation change sensor 002.

[0095] For example, Figure 1 In the optical path shown, a first off-axis parabolic mirror 1301 is provided at the head end of the optical path, a second off-axis parabolic mirror 1302 is provided at the end of the optical path, and a plane reflector 1303 for transmission is provided between the two off-axis parabolic mirrors.

[0096] Specifically, the reflectivity of the off-axis parabolic mirror and the plane reflector 1303 to infrared radiation is above 0.95.

[0097] Preferably, the light reflecting surfaces of the off-axis parabolic mirror and the plane reflector 1303 are gold reflecting layers to reduce the collection of stray signals.

[0098] Preferably, the optical path transmission unit 13 is disposed in the vacuum chamber 004 of the vacuum module, which can reduce the interference of air molecule dispersion on optical radiation detection.

[0099] Specifically, the measurement module further includes a sample stage 005 for fixing the measurement sample, and the sample stage 005 is provided with a black body cavity 052 , a sample test chamber 051 , and a reflector sample area 053 .

[0100] During implementation, the sample to be tested is placed in the sample test chamber 051, and the radiation adjustment device 001 uses the thermal radiation change sensor 002 to measure the change value of the electrical signal of the sample to be tested, the black body cavity 052, and the reflector at the target temperature, thereby obtaining the emissivity of the sample to be tested at the target temperature.

[0101] Preferably, the sample stage 005 is further provided with a heating device 054 and a temperature sensor 007. The temperature sensor 007 is used to measure the actual temperature of the test area of ​​the sample to be tested. The heating device 054 and the first refrigeration unit 11 cooperate to adjust the temperature of the sample test area.

[0102] During implementation, the temperature of the sample testing area can be easily achieved by adjusting the heating power of the heating device 054 and the cooling power of the first cooling unit 11 .

[0103] Specifically, the motion control module also includes a second motion unit 15 and a third motion unit 16, the second motion unit 15 includes a second motion unit fixed end 1501 and a motion end 1502 that can rotate relative to each other; the sample stage 005 is fixed to the motion end of the second motion unit 15, and can rotate with the motion end relative to the fixed end of the second motion unit 15, thereby realizing the emissivity test of samples placed at different angles;

[0104] Specifically, the third motion unit 16 includes: a fixed base 1601, a rotating connection part 1602, and a supporting connection structure 1603; the rotating connection part 1602 is provided with a rotor part 1602a and a stator part 1602b, the stator part 1602b is fixed by the fixed base 1601, and the rotor part 1602a and the stator part 1602b can rotate relative to each other; the fixed end of the second motion unit 15 is fixed to the first bracket, and can be displaced up and down relative to the fixed base 1601 of the third motion unit.

[0105] Specifically, the supporting connection structure 1603 includes: a connection structure body and a sliding connection part, wherein one end of the connection structure body is fixed to a horizontal plane, and the other end is a longitudinally extending free end, and the sliding connection part slides freely between the two ends of the connection structure body.

[0106] Specifically, the sliding connection part and the connection structure body can be connected by a ball or a slide rail.

[0107] Specifically, a first bracket and a second bracket are disposed on both sides of the sliding connection portion. The first bracket is fixedly connected to a fixed end of the second motion unit 15, and the second bracket is connected to the rotor part 1602a.

[0108] During implementation, the rotor part 1602a of the rotating connection part 1602 rotates relative to the stator part 1602b, and the sample stage 005 rotates with the moving end of the second moving unit 15 relative to the fixed end of the second moving unit 15. The angle of the emission plane of the sample to be tested changes relative to the detection optical path, so that the emission plane of the sample to be tested is emitted at different angles and the emissivity at different angles is measured.

[0109] Specifically, Figure 3 and 4 As shown, the sample stage 005 is provided with a base and a measuring part, wherein the measuring part is fixed to the base; and the base is fixed to the moving end of the second moving unit 15 .

[0110] Preferably, there are multiple sample testing chambers 051 arranged in sequence in the vertical direction.

[0111] Optionally, four sample testing chambers 051 are provided.

[0112] During implementation, different samples to be tested are arranged in the sample testing chamber 051, and the sample stage 005 moves up and down along with the moving end 1603 of the third moving unit, so as to realize the sample replacement and the measurement of the emissivity of different samples to be tested.

[0113] Specifically, the second motion unit 15 and the third motion unit 16 may be motors.

[0114] Preferably, the rotor part 1602a is connected to a screw rod, and the moving end 1603 of the third moving unit is provided with a thread matching the screw rod; when the rotor part 1602a rotates relative to the stator part 1602b, the sample stage 005 moves up and down relative to the connecting structure body along with the first bracket and the sliding connection part, and at the same time, different samples to be tested are arranged in the sample testing chamber 051, and the sample stage 005 moves up and down relative to the connecting structure body along with the sliding connection part, thereby realizing the sample replacement of the samples to be tested and measuring the emissivity of different samples to be tested.

[0115] Preferably, the center of the sample to be tested coincides with the rotation axis of the moving end 1502. When the sample to be tested rotates, its center is always on the rotation axis of the moving end 1502, avoiding detection errors caused by changes in the distance between its center and the thermal radiation change sensor 002.

[0116] Preferably, the first refrigeration unit 11 and the sample emission area are connected in a flexible and deformable manner, so that the first refrigeration unit 11 is connected to the sample emission area and the sample emission area is cooled when the sample stage 005 rotates or moves up and down.

[0117] Preferably, the first refrigeration unit 11 is connected to the sample emission area via a first connection portion 1102 , and the first connection portion 1102 is made of a flexible high thermal conductive material.

[0118] Preferably, the first connecting portion 1102 is a copper fiber braided tape.

[0119] Specifically, when the thermal radiation change sensor 002 is used to obtain the same adjustment amount of the adjustment device, the peak-to-valley voltage difference ΔU of the sample and the peak-to-valley voltage difference ΔU of the black body cavity 052 are 黑 , the peak-to-valley voltage difference ΔU of the reflector sample area 053 镜 ; emissivity of the sample at the target temperature ε A satisfy:

[0120] Among them, ε1 is the emissivity of the black body cavity 052; ε0 is the emissivity of the reflector sample area 053.

[0121] Specifically, the above emissivity ε A The expression formula and its derivation process are as follows:

[0122] The thermal radiation change sensor 002 (such as the Bolometer sensor) can only collect the difference signal modulated by the chopper. When the chopper rotates, the sensor alternately collects the radiation signals of the sample and the chopper blades. The radiation energy of an object includes two parts, namely the radiation energy of the object itself and the environmental radiation energy reflected by the object.

[0123] The radiation energy E of an ideal black body is based on the Boltzmann formula:

[0124] E=εσT 4 ; Where σ is the Boltzmann constant, ε is the emissivity, and T is the thermodynamic temperature.

[0125] When collecting samples, the sample's own radiation and the background radiation reflected on the sample are superimposed and enter the sensor through the optical transmission unit 13. The radiation energy E1 received by the sensor satisfies:

[0126] Wherein, ΔU is the peak-to-valley voltage difference of the sensor, ρ0 is the reflectivity of the optical transmission unit 13, σ is the Boltzmann constant, and ε A is the sample emissivity, ρ A is the sample reflectivity, T A is the sample thermodynamic temperature, ε W is the emissivity of cold screen 003, T W is the thermodynamic temperature of cold shield 003.

[0127] At this time, the sample is surrounded by the cold shield 003, and the reflected energy comes from the cold shield 003.

[0128] When the chopper is collected, the radiation energy E2 received by the sensor satisfies:

[0129] When the radiation amount adjustment device 001 is located inside the cold shield 003:

[0130] ε C is the emissivity of the radiation adjustment device 001, ρ C is the reflectivity of the radiation adjustment device 001, T C is the sample thermodynamic temperature, ε W is the emissivity of cold screen 003, T W is the thermodynamic temperature of cold shield 003.

[0131] When the radiation amount adjustment device 001 is located outside the cold shield 003:

[0132] ε V is the emissivity of the inner wall of the vacuum chamber, T V is the thermodynamic temperature of the inner wall of the vacuum chamber.

[0133] It should be noted that the bolometer sensor can only collect changing radiation signals. The use of a chopper allows the sensor to alternately receive radiation signals from the sample and the radiation adjustment device 001 to generate alternating signals, and the difference between the peaks and troughs can be proportional to the radiation difference.

[0134] Further, illustratively, taking the case where the radiation amount adjustment device 001 is located inside the cold shield 003 as an example, the peak-to-valley voltage difference ΔU of the sensor can be obtained by a bolometer sensor, and ΔU satisfies:

[0135]

[0136] Where ΔU is the peak-to-valley voltage difference of the sensor, and Cte is the sensor response coefficient.

[0137] Under the premise that the chopper temperature, the cold shield 003 temperature or the temperature of the inner wall of the vacuum chamber remain constant, E2 can be used as a constant during the measurement process; the ΔU expression can be simplified to:

[0138]

[0139] After the temperature stabilizes, k and Z can be used as constants during a single measurement.

[0140] In an ideal case, the emissivity of a black body is 0 and the emissivity is 1, and the reflectivity of the specimen area of ​​an ideal reflector is 1 and the emissivity is 0.

[0141] The emissivity ε of an ideal black body as the sample to be tested A =1, reflectivity ρ A =0;

[0142] Where ΔU 黑 It is the peak-to-valley voltage difference of the sensor when measuring a black body.

[0143] The emissivity ε measured by an ideal reflector as the sample to be tested A =0, reflectivity ρ A =1;

[0144] Where ΔU 镜 It is the difference between the peak and valley voltage of the sensor when measuring the reflector.

[0145] It should be noted that, by adjusting formula (I) to formula (III), it can be known that:

[0146]

[0147] For opaque materials, ε+ρ=1;

[0148] Formula (IV) is further simplified to obtain:

[0149] That is, the emissivity of the sample can be determined by measuring the peak-to-valley voltage difference ΔU of the sensor at that temperature.

[0150] Formula (V) is applicable to the measurement of samples with an emissivity greater than 0.2 at low temperatures. For samples with an emissivity less than 0.2, the difference between their emissivity and that of actual blackbody samples cannot be ignored. Actual blackbody samples cannot be regarded as ideal blackbody. The above formula will have a large deviation and needs to be adjusted according to actual conditions:

[0151] When measuring a black body, ε A =ε1,ρ A =ρ1=1-ε1, where ε A is the emissivity of the sample to be tested, ε1 is the emissivity of the blackbody cavity, ρ A is the reflectivity of the sample to be tested, ρ1 is the reflectivity of the black body cavity, and the peak-to-valley voltage difference ΔU of the sensor at a given temperature 黑 satisfy:

[0152]

[0153] After the temperature stabilizes, k and Z can be used as constants during a single measurement.

[0154] When measuring a reflector, ε A =ε0,ρ A =ρ0=1-ε0, where ε A is the emissivity of the sample to be tested, ε0 is the emissivity of the reflector sample area, ρ A is the reflectivity of the sample to be tested, ρ0 is the reflectivity of the reflector sample area, and the peak-to-valley voltage difference ΔU of the sensor at a given temperature 镜 satisfy:

[0155]

[0156] From formula (VI) and formula (VII), we can know that:

[0157]

[0158] Given that ε1≠ε0, the emissivity of the sample to be tested is ε A satisfy:

[0159]

[0160] It should be noted that formula (IX) takes into account the actual emissivity of the blackbody sample and the reflector sample, reduces the error, and is suitable for measuring the emissivity of materials under different emissivities.

[0161] Compared with the prior art, the present invention introduces the test data of the black body and the reflector at the same temperature based on the change of thermal radiation. Because the same background radiation at the same temperature is included and the same background radiation is deducted in the calculation formula, it has the advantage of not being affected by background radiation compared with the prior art.

[0162] It should be noted that the emissivity ε1 of the non-ideal blackbody sample can be obtained by adjusting the internal emissivity parameters of the instrument through a quantifiable and traceable optical thermometer, and the measured temperature is matched with the blackbody temperature to obtain the emissivity value.

[0163] It should be noted that the emissivity ε0 of the non-ideal reflector sample can be measured by the integrating sphere reflection method.

[0164] Specifically, the thermal radiation change sensor obtains a detection signal corresponding to a change in the amount of radiation emitted by the sample received by the sensor, including:

[0165] Detection signal when the measurement area is a black body, a reflector and a sample to be measured at a target temperature under a vacuum environment;

[0166] The emissivity of the sample at the target temperature is obtained based on the detection signal.

[0167] Specifically, when the measurement area is a black body, a reflector, and a sample to be measured at the target temperature, the detection signal includes:

[0168] Adjust the angle between the radiation amount adjusting device 001 and the emission light path of the sample to a, so that the input radiation amount of the thermal radiation change sensor 002 changes, and obtain the voltage change difference ΔU of the sample to be tested;

[0169] Adjust the angle between the radiation adjustment device 001 and the emission light path of the sample to a, so that the input radiation of the thermal radiation change sensor 002 changes, and obtain the black body cavity voltage change difference ΔU 黑 ;

[0170] Adjust the angle between the radiation amount adjusting device 001 and the emission light path of the sample to a, so that the input radiation amount of the thermal radiation change sensor 002 changes, and obtain the reflector voltage change difference ΔU 镜 .

[0171] Preferably, a>90°.

[0172] Specifically, when the measurement area is measured to be a black body, a reflector and a sample to be measured at the target temperature, the detection signal further includes: adjusting the temperature of the measurement area to the target temperature by using multi-stage cooling.

[0173] Preferably, the cooling medium of the measuring area is liquid helium.

[0174] Preferably, the cooling medium is connected to the measuring area via a flexible high thermal conductivity material to achieve indirect cooling.

[0175] Specifically, the pressure of the vacuum environment is ≤10 -3 pa.

[0176] Specifically, the low temperature emissivity test method includes:

[0177] S1: evacuate the vacuum chamber to the target vacuum degree;

[0178] S2: Adjust the temperature of the sample test area to the target temperature;

[0179] S3: adjusting the radiation amount adjusting device 001 to the same rotation angle, and obtaining a detection signal based on the thermal radiation change sensor 002 when the measurement area is a black body, a reflector and a sample to be measured;

[0180] S4: Obtaining the emissivity of the sample to be tested at the target temperature based on the above detection signal.

[0181] Specifically, the vacuuming in S1 includes:

[0182] S101: using a primary vacuum pump to obtain a first vacuum degree;

[0183] S102: Using a secondary vacuum pump to obtain a second vacuum degree.

[0184] Specifically, the primary vacuum pump may be a mechanical pump; the secondary vacuum pump may be a molecular pump;

[0185] The first vacuum degree is ≤5pa, the second vacuum degree is ≤10 -3 pa.

[0186] Adjusting to the target temperature in S2 includes:

[0187] S201: The test area is made to obtain a target temperature based on the first refrigeration unit 11 and the heating device 054 in the sample stage 005;

[0188] S202: Inject refrigerant into the first refrigerant storage tank 1201 and the second refrigerant storage tank 1202 in the second refrigeration unit 12 to ensure that the operating temperature of the thermal radiation change sensor 002 is ≤40K.

[0189] Specifically, obtaining the target temperature in S201 includes:

[0190] S2011: operate the first refrigeration unit 11 to cool the sample stage 005 to below 20K;

[0191] S2012: Adjust the heating power of the heating device 054 and the cooling power of the first cooling unit 11 so that the test area obtains the target temperature.

[0192] Specifically, in S2012, the first refrigeration unit 11 adopts two-stage refrigeration.

[0193] Specifically, the first refrigeration unit 11 is provided with a helium internal circulation refrigerator and a circulating water refrigerator for dissipating heat for the helium internal circulation refrigerator; the helium internal circulation refrigerator is connected to the cold head 1101 to circulate refrigeration for the cold head 1101 .

[0194] Specifically, injecting the refrigerant medium in S202 includes:

[0195] S2021: injecting liquid nitrogen into the first refrigerant storage tank 1201 and the second refrigerant storage tank 1202;

[0196] S2022: Purging the first refrigerant storage tank 1201 with helium until nitrogen is exhausted;

[0197] S2023: Inject liquid helium into the first refrigerant storage tank 1201.

[0198] It can be understood that the second refrigerant storage tank 1202 injected with liquid nitrogen helps to reduce the heat loss of the first refrigerant storage tank 1201, and helps the thermal radiation change sensor 002 to operate at the low temperature of liquid helium.

[0199] Specifically, the detection signal obtained in S3 when the measurement area is the black body cavity 052, the reflector sample area 053 and the sample to be measured includes:

[0200] S301: adjusting the third motion unit 16 so that the focus of the first off-axis parabolic mirror 1301 is at the center of the sample to be tested, adjusting the radiation amount adjustment device 001 so that the input radiation amount of the thermal radiation change sensor 002 changes, and obtaining the voltage change difference ΔU;

[0201] S302: Adjust the third motion unit 16 so that the focus of the first off-axis parabolic mirror 1301 is at the center of the black body cavity 052, and adjust the radiation amount adjustment device 001 to the same degree as S301 so that the input radiation amount of the thermal radiation change sensor 002 changes, and obtain the voltage change difference ΔU 黑 ;

[0202] S303: Adjust the third motion unit 16 so that the focus of the first off-axis parabolic mirror 1301 is at the center of the reflector sample area 053, adjust the radiation amount adjustment device 001 to the same degree as S301 so that the input radiation amount of the thermal radiation change sensor 002 changes, and obtain the voltage change difference ΔU 镜 .

[0203] Exemplarily, in S301-S303, the radiation amount adjusting device 001 is adjusted to rotate more than 90° to obtain the voltage change difference of the black body cavity 052, the reflector sample area 053 and the sample to be tested during the rotation process of the adjusting device.

[0204] In S4, obtaining the emissivity of the sample to be tested at the target temperature based on the detection signal includes: 黑 , ΔU 镜 Substituting into the formula: or Get ε A ; Among them, ε1 is the emissivity of the black body cavity 052; ε0 is the emissivity of the reflector sample area 053.

[0205] It should be noted that the emissivity ε1 of the non-ideal blackbody sample can be obtained by adjusting the internal emissivity parameters of the instrument through a quantifiable and traceable optical thermometer, and the measured temperature is matched with the blackbody temperature to obtain the emissivity value.

[0206] It should be noted that the emissivity ε0 of the non-ideal reflector sample can be measured by the integrating sphere reflection method.

[0207] Preferably, substitute into the formula: Get more accurate calculation results.

[0208] In order to better illustrate the present invention, the following embodiments are further disclosed:

[0209] Example 1

[0210] Prepare the test sample, use the above test system and test method to test, prepare the disc sample, size (diameter × thickness) Test different materials and angles, and substitute the formula to obtain the emissivity of the sample to be tested. Specifically, the emissivity of stainless steel, a high-reflection and low-emission material, can only be obtained by Calculation, high emission and low reflection material graphite is used It is calculated that at 40K and 150K, the measured value of the reflector emissivity ε0 is about 0.035, and the measured value of the blackbody emissivity ε1 is about 1. The results are as follows: the voltage signal of the sample to be tested, the voltage signal of the blackbody cavity, and the voltage signal of the reflector sample area.

[0211] 40K Thermal Radiation Change Sensor Test Data Sheet

[0212] 0° / V 30° / V 60° / V <![CDATA[Boldface (ΔU 黑 )]]> 8.88 8.88 9.04 <![CDATA[Mirror (ΔU 镜 )]]> 2 1.2 3.92 Graphite(ΔU) 5.76 5.52 7.28 Stainless steel(ΔU) 2.4 1.56 4.56

[0213] 40K emissivity

[0214]

[0215]

[0216] 150K Thermal Radiation Change Sensor Test Data Sheet

[0217] 0° / V 30° / V 60° / V <![CDATA[Boldface (ΔU 黑 )]]> 6.4 6.72 6.65 <![CDATA[Mirror (ΔU 镜 )]]> 2 1.12 4.08 Graphite(ΔU) 4.4 4 6 Stainless steel(ΔU) 2.16 4.36 4.4

[0218] 150K emissivity

[0219] 0° 30° 60° graphite 0.546 0.514 0.747 Stainless steel 0.036 0.579 0.125

[0220] Example 2

[0221] Select a material with known emissivity at the target temperature to prepare a test sample, use the above test system and test method to test, and prepare a disc-shaped sample with a size (diameter × thickness) The test temperature is 80K, and the multiple measurement data are as follows:

[0222]

[0223] Experimental conclusion: The deviation between the mean of multiple measurements and the theoretical value is less than 3%, and the measurement standard deviation is less than 5%.

[0224] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A low temperature directional emissivity test method based on thermal radiation effect, characterized in that: include: Establishing an optical path connection between the thermal radiation change sensor and the radiation amount regulating device; A sample stage including a black body cavity, a sample test chamber and a reflector sample area is arranged in the radiation amount adjusting device; Changing the angle between the radiation amount adjusting device and the emission light path to adjust the radiation amount emitted by the sample acquired by the thermal radiation change sensor; The thermal radiation change sensor obtains a detection signal corresponding to a change in the amount of radiation emitted by the sample it receives; The emission rate of the sample is obtained based on the detection signal.

2. A low temperature directional emissivity testing method according to claim 1, characterized in that: The thermal radiation change sensor obtains a detection signal corresponding to a change in the amount of radiation emitted by the sample received by the sensor, including: Detection signal when the measurement area is a black body, a reflector and a sample to be measured at a target temperature under a vacuum environment; The emissivity of the sample at the target temperature is obtained based on the detection signal.

3. A low temperature directional emissivity testing method according to claim 2, characterized in that: When the measurement area is a black body, a reflector and a sample to be measured at the target temperature, the detection signal includes: Adjust the angle between the radiation amount adjusting device and the emission light path of the sample to a, so that the input radiation amount of the thermal radiation change sensor changes, and obtain the voltage change difference ΔU of the sample to be tested; Adjust the angle between the radiation adjustment device and the emission light path of the sample to a, so that the input radiation of the thermal radiation change sensor changes, and obtain the black body cavity voltage change difference ΔU 黑 ; Adjust the angle between the radiation adjustment device and the emission light path of the sample to a, so that the input radiation of the thermal radiation change sensor changes, and obtain the reflector voltage change difference ΔU 镜 .

4. A low temperature directional emissivity testing method according to claim 3, characterized in that: a＞90°。 5. A low temperature directional emissivity testing method according to claim 2, characterized in that: When the measurement area is measured to be a black body, a reflector and a sample to be measured at the target temperature, the detection signal also includes: using multi-stage cooling to adjust the temperature of the measurement area to the target temperature.

6. A low temperature directional emissivity testing method according to claim 5, characterized in that: The cooling medium of the measuring area is liquid helium.

7. A low temperature directional emissivity testing method according to claim 6, characterized in that: Acquiring the emissivity based on the detection signal includes: connecting the cooling medium and the measuring area through a flexible high thermal conductivity material to achieve indirect cooling.

8. A low temperature directional emissivity testing method according to claim 7, characterized in that: Acquiring the emissivity based on the detection signal includes: based on or Get ε A ; where ε A is the emissivity of the sample to be tested, ε1 is the emissivity of the blackbody cavity, and ε0 is the emissivity of the reflector sample area.

9. A low temperature directional emissivity testing method according to claim 8, characterized in that: based on Get ε A .

10. A low temperature directional emissivity test system based on thermal radiation effect, characterized in that: The test method according to any one of claims 1 to 9 comprises: a thermal radiation change sensor and a radiation amount adjustment device connected by an optical path; The radiation amount adjusting device can adjust the radiation amount emitted by the sample acquired by the thermal radiation change sensor; The radiation amount adjusting device is arranged with a rotating shaft perpendicular to the emission light path of the sample, and can rotate around the rotating shaft to change the angle between itself and the emission light path.

Images