Device and equipment for measuring near-field radiation emissivity at low temperature

Abstract

The utility model provides a device and equipment for measuring near-field radiation emissivity at low temperature. The device comprises a vacuum tube with a hollow inner cavity and a measuring mechanism fixed in the vacuum tube, the measuring mechanism comprises an adjusting assembly, a transmitting end sample piece connected with the adjusting assembly and an absorbing end sample piece correspondingly matched with the transmitting end sample piece; the adjusting assembly comprises a leveling structure and a distance adjusting structure; the distance adjusting structure comprises a movable rod, a driving piece for driving the movable rod to move and a thermal insulation piece connected with one end of the movable rod; the leveling structure is fixed with the thermal insulation piece, and the transmitting end sample piece is fixed with the leveling structure; the distance adjusting structure can drive the leveling structure and the transmitting end sample piece to be close to or far away from the absorbing end sample piece along the axial direction of the vacuum tube; the leveling structure can be driven by the distance adjusting structure to enable the lower surface of the transmitting end sample piece to be attached to the upper surface of the absorbing end sample piece and enable the lower surface of the transmitting end sample piece and the upper surface of the absorbing end sample piece to be kept in a relatively parallel state.

Description

Technical Field

[0001] This utility model relates to the field of cryogenic equipment technology. More specifically, it relates to a device and equipment for measuring near-field radiative emissivity at cryogenic temperatures. Background Technology

[0002] Thermal radiation, as a common heat transfer mechanism, enables contactless heat transfer between objects. However, with the rapid development of micro- and nanofabrication technologies, device sizes are becoming increasingly miniaturized and integrated, with the spacing between components ranging from macroscopic to micro- and nanoscale. Whether at room temperature or cryogenic temperatures, when the spacing between devices approaches or is smaller than the characteristic wavelength of radiation, the near-field effect of thermal radiation becomes prominent, potentially exceeding the upper limit of Planck's law for blackbody radiation. However, this rapidly increasing heat flux density can become uncontrollable in cryogenic devices, leading to decreased performance and reliability, and even malfunction. Therefore, a deeper understanding of the near-field emissivity of materials at cryogenic temperatures is not only crucial for exploring fundamental physics but also of great significance for improving the performance of devices such as quantum computers and single-photon detectors, as well as developing technologies for thermal management and control.

[0003] The most significant challenge in near-field radiation testing devices lies in controlling the vacuum spacing and the parallelism between samples. Existing experimental setups for studying near-field radiation characteristics at room temperature employ a fixed spacing of nanopillars or particles to achieve the near-field state. While this method directly maintains the parallelism of the system spacing, it cannot adjust the spacing in real time, severely impacting experimental efficiency. Furthermore, the parallelism depends on the fabrication precision of the nanopillars. In addition, this method cannot directly obtain the radiative heat flux density, requiring consideration of the thermal conductivity of the nanopillars or particles, making result processing cumbersome. Moreover, this device does not consider low-temperature design, making experimental studies of near-field radiation in low-temperature regions difficult. Utility Model Content

[0004] To address the aforementioned problems, this invention provides a device for measuring near-field radiative emissivity at low temperatures, enabling convenient and rapid measurement of near-field radiative emissivity at low temperatures and improving work efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a device for measuring near-field radiative emissivity at low temperatures, comprising:

[0007] A vacuum tube with a hollow inner cavity and a measuring mechanism fixed inside the vacuum tube;

[0008] The measuring mechanism includes an adjustment component, an emitting end sample connected to the adjustment component, and an absorbing end sample corresponding to and cooperating with the emitting end sample.

[0009] The adjustment assembly includes a leveling structure for adjusting the parallelism between the emitting end sample and the absorbing end sample, and a distance adjustment structure for adjusting the distance between the emitting end sample and the absorbing end sample.

[0010] The adjustment structure includes a moving rod that can move along the axial direction of the vacuum tube, a driving component for driving the moving rod, and a thermal insulation component connected to one end of the moving rod; the leveling structure is fixed to the thermal insulation component, and the emitting end sample is fixed to the leveling structure.

[0011] The adjustment structure is configured to drive the leveling structure and the emitting sample to move closer to or further away from the absorbing sample along the axial direction of the vacuum tube.

[0012] The leveling structure is configured to allow the lower surface of the emitting sample to fit against the upper surface of the absorbing sample under the drive of the adjusting structure, and to keep the lower surface of the emitting sample and the upper surface of the absorbing sample relatively parallel.

[0013] In a preferred embodiment, the measuring mechanism further includes a shield fixed inside the vacuum tube; the emitting sample, the absorbing sample, the thermal insulation component, and the leveling structure are all located inside the shield.

[0014] In a preferred embodiment, the adjustable distance structure further includes a hollow tube fixed to the shielding cover; the hollow tube is coaxially arranged with the shielding cover; the driving component is fixed to the top wall of the hollow tube, and the driving end of the driving component extends into the hollow tube; the top end of the moving rod corresponds to the driving end of the driving component, and the bottom end of the moving rod penetrates the bottom wall of the hollow tube and extends into the shielding cover to connect with the thermal insulation component.

[0015] A preferred embodiment is that the driving component includes an assembly with a through hole for fixing to the top wall of the hollow tube, a piezoelectric inertial motor fixed to the assembly, and a screw that cooperates with the piezoelectric inertial motor; the moving rod is connected to the inner surface of the top wall of the hollow tube through an elastic element; the through hole has an internal thread and communicates with the hollow tube; the screw is screwed into the through hole; the lower end face of the screw is an arc surface; the top end of the moving rod has a groove that abuts against the lower end of the screw; the screw can push the moving rod to move downward along the vacuum tube axis under the drive of the piezoelectric inertial motor.

[0016] A preferred embodiment is that the leveling structure includes a positioning member fixed to a thermally insulating member, an adjusting member for fixing the emitting sample, a first mating member disposed on the positioning member, a second mating member disposed on the adjusting member, and an elastic member whose two ends are respectively connected to the positioning member and the adjusting member; the first mating member and the second mating member abut against each other and form a static friction fit under the elastic force of the elastic member; the adjusting member is configured to overcome the static friction between the first mating member and the second mating member under the drive of the leveling structure, so that the lower surface of the emitting sample is in contact with the upper surface of the absorbing sample.

[0017] The preferred embodiment is that the number of the first mating component, the second mating component, and the elastic component is at least three; the first mating component is evenly arranged around the circumference of the positioning component, and the second mating component is evenly arranged around the circumference of the adjusting component; the axis of the first mating component is perpendicular to the axis of the second mating component, and the circumferential sidewall of the first mating component abuts against the circumferential sidewall of the second mating component.

[0018] In a preferred embodiment, the measuring mechanism further includes a heat sink fixed to the bottom wall of the vacuum tube, a reference plate fixed to the upper surface of the heat sink, and a calorimeter rod fixed to the reference plate and arranged along the axial direction of the vacuum tube, the top end of the calorimeter rod being connected to the absorption end sample; the upper surface of the reference plate is provided with a heat insulation layer.

[0019] In a preferred embodiment, the leveling structure is fixed to the thermal insulation component via a mounting component; a heating element and a temperature sensor are provided on the upper surface of the mounting component, and a heating element and a temperature sensor are provided on the lower surface of the absorption end sample.

[0020] A preferred embodiment is that the shielding cover includes an inner cover and an outer cover arranged coaxially, and an insulation layer disposed between the inner cover and the outer cover; the inner cover is fixed to the bottom wall of the hollow tube, and the outer cover is fixed to the circumferential side wall of the hollow tube.

[0021] This utility model also provides a device for measuring near-field radiative emissivity at low temperatures, including the apparatus for measuring near-field radiative emissivity at low temperatures as described above; the device also includes a capacitive sensor, a control system, a liquid nitrogen Dewar, a vacuum pump, and an optical anti-vibration platform; the vacuum tube is provided with a first interface and a second interface; the liquid nitrogen Dewar is located on the optical anti-vibration platform, and the vacuum tube is immersed in the liquid nitrogen Dewar;

[0022] The capacitive sensor is electrically connected to the emitting and absorbing sample pieces respectively through the first interface to monitor the distance between the emitting and absorbing sample pieces; the control system is electrically connected to the driving component through the first interface to control the start and stop of the driving component; the vacuum pump is vacuum-sealed to the second interface to extract air from the vacuum tube; the liquid nitrogen Dewar is used to provide the experimental environment.

[0023] The beneficial effects of this utility model are as follows:

[0024] This invention achieves controllable adjustment of the micro-nano-level spacing between the transmitting and receiving ends through the precise cooperation of the driving component and the moving rod. Compared to traditional testing methods that require repeated replacement of samples with fixed spacing, this design significantly improves the testing efficiency of the same sample. Specifically, by precisely adjusting the driving component to drive the moving rod to perform micro-nano-level displacement, since the transmitting and receiving sample pieces are already pressed and locked in a parallel state through the leveling structure during initial installation, even during the upward movement of the moving rod, the strict parallel alignment of the transmitting and receiving sample pieces can still be ensured. This invention enables accurate measurement of near-field radiation. Unlike far-field radiation, when the radiation spacing is less than or equal to the radiation wavelength (usually on the micro-nano scale), the radiation energy increases significantly as the spacing decreases. By achieving precise micro-nano-level spacing adjustment, this invention can effectively observe the significant enhancement effect of near-field radiation. This real-time adjustable micro-nano-spacing structure provides a powerful tool for studying the near-field radiation characteristics under different spacing conditions. The application scope of this invention is not limited to the research of single materials, but can also be extended to the near-field radiation performance testing of different material systems under different temperatures and spacing conditions, which has broad application prospects and research value. Attached Figure Description

[0025] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0026] Figure 1 This is a schematic diagram of the overall structure of the device for measuring near-field radiative emissivity at low temperatures according to this utility model.

[0027] Figure 2 This is a structural schematic diagram of the mating position between the drive component and the moving rod of this utility model.

[0028] Figure 3 This is a structural schematic diagram of the driving component of this utility model.

[0029] Figure 4 This is a schematic diagram showing the fit between the mounting components, leveling structure, and transmitter sample of this utility model.

[0030] Figure 5 This is a schematic diagram of the leveling structure of this utility model.

[0031] Figure 6 This is a schematic diagram of the internal structure of the shielding cover of this utility model.

[0032] Figure 7 This is a schematic diagram of the overall structure of the device for measuring near-field radiative emissivity at low temperatures according to this utility model.

[0033] Reference numerals: 1. Vacuum tube; 21. Emitter sample; 22. Absorber sample; 23. Leveling structure; 241. Moving rod; 242. Driving component; 243. Thermal insulation component; 244. Hollow tube; 25. Shielding cover; 2421. Assembly part; 2422. Piezoelectric inertial motor; 2423. Screw; 2424. Adjusting knob; 2425. Preload ring; 2426. Neck nut; 2411. Groove; 2412. Elastic component; 231. Positioning component; 232. Adjusting component; 233. First mating component. 234. Second mating component; 235. Elastic component; 236. First fixing component; 237. Second fixing component; 26. Heat sink; 27. Reference plate; 28. Calorimeter rod; 291. Mounting component; 292. Connecting component; 251. Inner cover; 252. Outer cover; 100. Device for measuring near-field radiative emissivity at low temperatures; 200. Capacitive sensor; 300. Control system; 400. Liquid nitrogen Dewar; 500. Vacuum pump; 600. Optical anti-vibration platform; 101. First interface; 102. Second interface. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0035] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0036] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0037] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0039] To address the problems existing in the prior art, this utility model provides a device for measuring near-field radiative emissivity at low temperatures, combined with... Figures 1 to 7As shown, the device for measuring near-field radiative emissivity at low temperatures specifically includes: a vacuum tube 1 with a hollow inner cavity and a measuring mechanism fixed inside the vacuum tube 1. The measuring mechanism includes an adjustment assembly, an emitting sample 21 connected to the adjustment assembly, and an absorbing sample 22 corresponding to the emitting sample 21. The adjustment assembly includes a leveling structure 23 for adjusting the parallelism between the emitting sample 21 and the absorbing sample 22, and a distance adjustment structure for adjusting the distance between the emitting sample 21 and the absorbing sample 22. The distance adjustment structure includes a moving rod 241 movable along the axial direction of the vacuum tube, a driving member 242 for driving the moving rod 241, and a thermally insulating member 243 connected to one end of the moving rod 241. The leveling structure 23 is fixed to the thermally insulating member 243, and the emitting sample 21 is fixed to the leveling structure 23. The distance adjustment structure is configured to drive the leveling structure 23 and the emitting sample 21 to move closer to or further away from the absorbing sample 22 along the axial direction of the vacuum tube. The leveling structure 23 is configured to allow the lower surface of the emitting sample 21 to adhere to the upper surface of the absorbing sample 22 under the drive of the adjusting structure, and to maintain the lower surface of the emitting sample 21 and the upper surface of the absorbing sample 22 in a relatively parallel state. This invention, through the cooperation of the driving component 242 and the moving rod 241, achieves micro-nano-level controllable adjustment of the emitting sample 21 and the receiving sample 22 at different distances, eliminating the need to repeatedly replace samples with fixed distances, thus improving testing efficiency for the same sample. The adjusting structure achieves micro-nano-level distance adjustment, and the emitting sample 21 and the absorbing sample 22 remain relatively parallel through the leveling structure 23. When the moving rod 241 moves upward, the emitting sample 21 and the absorbing sample 22 still remain relatively parallel. The near-field radiation measured by this invention differs from the far-field radiation. When the radiation distance is less than or equal to the radiation wavelength, the radiation amount increases as the sample distance decreases. Therefore, this invention achieves significant near-field radiation by adjusting the distance to the micro-nano level. By adjusting the micro-nano-level spacing between the emitting sample 21 and the absorbing sample 22 in real time during the experiment using an adjustable spacing structure, near-field radiation at different spacings can be obtained. This invention realizes the measurement of near-field radiative emissivity of a sample plane with variable parallel spacing using a mechanically driven structure in a low-temperature region, achieving high measurement accuracy and efficiency.

[0040] In the above embodiment, the measuring mechanism further includes a shield 25 fixed inside the vacuum tube; the emitting end sample 21, the absorbing end sample 22, the thermal insulation component 243 and the leveling structure 23 are all located inside the shield.

[0041] Furthermore, the shielding cover 25 includes an inner cover 251 and an outer cover 252 coaxially arranged, and an insulating layer disposed between the inner cover 251 and the outer cover 252; the inner cover 251 is fixed to the bottom wall of the hollow tube 244, and the outer cover 252 is fixed to the circumferential side wall of the hollow tube 244. The inner cover 251 is a primary copper shield with thermal shielding function. The outer cover 252 is a secondary copper shield with thermal shielding function, and an insulating layer is disposed between the secondary copper shield and the primary copper shield to reduce radiative heat transfer between the sample and the external space. The emitting sample 21 is positioned above and correspondingly disposed above the absorbing sample 22, and the corresponding areas of the top surface of the absorbing sample 22 and the bottom surface of the emitting sample 21 are the same to ensure that the heat emitted by the emitting sample 21 can be completely absorbed by the absorbing sample 22.

[0042] In one specific embodiment, the adjusting structure further includes a hollow tube 244 fixed to the shielding cover 25; the hollow tube 244 includes a top wall, a bottom wall, and a peripheral side wall. The hollow tube 244 is coaxially arranged with the shielding cover 25. The driving member 242 is fixed to the top wall of the hollow tube 244, and the driving end of the driving member 242 extends into the hollow tube 244. The top end of the moving rod 241 corresponds to the driving end of the driving member 242, and the bottom end of the moving rod 241 penetrates the bottom wall of the hollow tube 244 and extends into the shielding cover 25 to connect with the thermal insulation member 243. The upper end of the hollow tube 244 has a threaded hole, and the flange is installed and covered on the upper end of the hollow tube 244 by screwing to form the top wall of the hollow tube 244. The lower end of the peripheral side wall of the hollow tube 244 has an external thread for screwing the primary copper shield. The upper end of the moving rod 241 located in the hollow tube 244 is connected to the lower end face of the flange by a spring.

[0043] More specifically, the driving component 242 includes a fitting 2421 with a through hole for fixing to the top wall of the hollow tube 244, a piezoelectric inertial motor 2422 fixed to the fitting 2421, and a screw 2423 cooperating with the piezoelectric inertial motor 2422; the moving rod 241 is connected to the inner surface of the top wall of the hollow tube 244 through an elastic member 2412; the through hole has an internal thread and communicates with the hollow tube 244; the screw 2423 is screwed into the through hole; the lower end face of the screw 2423 is an arc surface; the top end of the moving rod 241 has a groove 2411 that abuts against the lower end of the screw 2423; the screw 2423 can push the moving rod 241 downward along the vacuum tube axis under the drive of the piezoelectric inertial motor 2422.

[0044] The upper end of the screw 2423 includes an adjustment knob 2424, which can be used to coarsely adjust the spacing between the emitting and absorbing sample pieces. The piezoelectric inertial motor 2422 includes a metal shielding layer to shield against external electromagnetic interference. A pre-tightening ring 2425 is fitted onto the assembly 2421 for screwing and fixing to the top wall of the hollow tube 244. A neck nut 2426 fitted onto the lower end of the screw 2423 and the lower end face of the screw 2423 abut against the groove 2411 on the moving rod 241. The piezoelectric inertial motor 2422 drives the screw 2423 to rotate, thereby moving it downward on the assembly 2421 and pushing the moving rod 241 downward, so that the emitting sample piece 21 is close to the absorbing sample piece 22. When the piezoelectric inertial motor 2422 drives the screw 2423 to rotate, thus moving it upward on the assembly 2421, the moving rod 241 moves upward under the elastic restoring force of the elastic element 2412, causing the emitting sample 21 to move away from the absorbing sample 22, thereby adjusting the distance between the emitting and absorbing sample 21. This adjustable distance structure allows for real-time adjustment of the radiation distance between the emitting and absorbing sample 22, saving significant testing time and avoiding the time wasted by the cumbersome process of replacing fixed-distance components (such as nanopillars). Furthermore, since existing nanoscale fixed-distance components and samples need to be fabricated as a single unit, testing the radiation performance at different distances requires samples fabricated with different fixed-distance components, resulting in low sample reuse and waste. This device has the advantages of simple operation, convenient assembly, and strong fine-tuning performance.

[0045] In one specific embodiment, the leveling structure 23 includes a positioning member 231 fixed to the thermal insulation member 243, an adjustment member 232 for fixing the emitting sample member 21, a first mating member 233 disposed on the positioning member 231, a second mating member 234 disposed on the adjustment member 232, and an elastic member 235 connected at both ends to the positioning member 231 and the adjustment member 232 respectively; the first mating member 233 and the second mating member 234 abut against each other and form a static friction fit under the elastic force of the elastic member 235; the adjustment member 232 is configured to overcome the static friction between the first mating member 233 and the second mating member 234 under the drive of the leveling structure, so that the lower surface of the emitting sample member 21 is in contact with the upper surface of the absorbing sample member 22. The number of the first mating component 233, the second mating component 234, and the elastic component 235 is at least three. The first mating component 233 is evenly arranged circumferentially along the positioning component 231, and the second mating component 234 is evenly arranged circumferentially along the adjusting component 232. The axis of the first mating component 233 is perpendicular to the axis of the second mating component 234, and the circumferential sidewall of the first mating component 233 abuts against the circumferential sidewall of the second mating component 234. The first mating component 233 and the second mating component 234 enable the emitting end sample component 21 to contact and completely adhere to the absorbing end sample component 22, keeping the lower surface of the emitting end sample component 21 parallel to the upper surface of the absorbing end sample component 22. The static friction of the first mating component 233 and the second mating component 234 fixes the relative position of the emitting end sample component 21 and the absorbing end sample component 22. The aforementioned leveling structure 23, based on the friction lock principle, enables high-precision automatic fine-tuning of the transmitter sample 21 relative to the absorber sample 22. Through an automatic friction lock mechanism, the position of the transmitter sample 21 is stably fixed after adjustment, thus maintaining the required precise positioning state for extended periods. This meets the requirements for automation, stability, and efficiency in scenarios such as low-temperature optical alignment and precision machining. The friction lock self-locking function generates stress through the elastic element 235, causing the first mating element 233 and the second mating element 234 to be tightened and generate pressure. At this time, the contact surfaces of the first mating element 233 and the second mating element 234 generate static friction, which counteracts the gravity of the adjusting element 232 and the transmitter sample 21, achieving a locking function to prevent displacement of the transmitter sample 21 after leveling. The adjusting element 232, fixed to the transmitter sample 21 through the connecting element 292, provides assembly space for the upper surface of the transmitter sample 21 and facilitates replacement of the transmitter sample 21. More specifically, the leveling structure 23 further includes a first fixing member 236 disposed on the positioning member 231 and a second fixing member 237 disposed on the adjusting member 232. One end of the elastic member 235 is connected to the first fixing member 236, and the other end is connected to the second fixing member 237. The number of the first mating member 233, the second mating member 234, and the elastic member 235 is not limited to three, and can be changed according to the required accuracy and load size.For example, in scenarios with high load or high fine-tuning precision, the number of elastic elements 235 can be increased, forming more friction lock structures in conjunction with a corresponding number of first mating elements 233 and second mating elements 234, thereby improving load capacity and self-locking capability. If it is necessary to increase the number of elastic elements 235, the external structure of the positioning element 231 and adjusting element 232 can be changed according to the number of corresponding mating elements, without any restrictions.

[0046] In one specific embodiment, the measuring mechanism further includes a heat sink 26 fixed to the bottom wall of the vacuum tube 1, a reference plate 27 fixed to the upper surface of the heat sink 26, and a calorimeter rod 28 fixed to the reference plate 27 and arranged axially along the vacuum tube. The top end of the calorimeter rod 28 is connected to the absorption end sample 22. An insulation layer is provided on the upper surface of the reference plate 27. The upper and lower ends of the calorimeter rod 28 are respectively connected to the absorption end sample 22 and the reference plate 27 to conduct the radiative heat flow received by the absorption end sample 22 from the emission end sample 21. The reference plate 27 is used to provide support for the absorption end sample 22 and to provide a path for the transfer of cold energy. An insulation layer is provided on the top surface of the reference plate 27. Since the insulation layer material is epoxy resin with low thermal conductivity, it can provide a buffer for the transfer of cold energy. In addition, since the thermal conductivity of the calorimeter rod 28 is constant, the heat passing through the calorimeter rod 28 can be calculated by measuring the temperature at both ends of the calorimeter rod 28 (i.e., the absorption end sample 22 and the reference plate 27). The heat sink 26 is fixed to the bottom wall of the vacuum tube 1 through a positioning groove and forms thermal contact. The heat sink 26 is also connected to the reference plate 27 by screws.

[0047] In one specific embodiment, the leveling structure 23 is fixed to the thermal insulation component 243 via a mounting component 291; a heating element and a temperature sensor are disposed on the upper surface of the mounting component 291, and a heating element and a temperature sensor are disposed on the lower surface of the absorbing end sample component 22. The thermal insulation component 243, which has a thermal shielding function, can prevent heat from being conducted from the emitting end sample component 21 to the moving rod 241, ensuring one-dimensional heat transfer during the experiment. The mounting component 291, which has good thermal conductivity, is provided with mounting holes for mounting the heating element and the temperature sensor.

[0048] This invention also provides a device for measuring near-field radiative emissivity at low temperatures, comprising the apparatus 100 described above for measuring near-field radiative emissivity at low temperatures; the device further comprises a capacitive sensor 200, a control system 300, a liquid nitrogen Dewar 400, a vacuum pump 500, and an optical anti-vibration platform 600; the vacuum tube 1 is provided with a first interface 101 and a second interface 102; the liquid nitrogen Dewar 400 is located on the optical anti-vibration platform 600, and the vacuum tube 1 is immersed in the liquid nitrogen Dewar 400; the capacitive sensor 200 is electrically connected to the emitting sample 21 and the absorbing sample 22 respectively through the first interface 101 to monitor the distance between the emitting sample 21 and the absorbing sample 22; the control system 300 is electrically connected to the drive 242 through the first interface 101 to control the start and stop of the drive 242; the vacuum pump 500 is vacuum-sealed to the second interface 102 to extract air from the vacuum tube 1; the liquid nitrogen Dewar 400 is used to provide a temperature-stable experimental environment. This device benefits from the cryogenic liquid environment provided by the liquid nitrogen Dewar 400, ensuring stable experimental temperatures and allowing experiments to reach the cryogenic range (77K-300K). Thanks to the adjustable spacing of the adjustable structure, this invention is independent of the processing precision of nanopillars or particles, improving the device's flexibility and avoiding the waste of time and resources caused by cumbersome sample replacement processes. The leveling structure 23 ensures that the lower surface of the emitting sample 21 and the upper surface of the absorbing sample 22 are relatively parallel, and the gap is monitored in real time using a capacitive sensor 200, improving the reliability of the measurement results. The use of the optical vibration damping platform 600 reduces the impact of external vibrations on the minute gap between the emitting and absorbing sample 21, thus improving the device's stability. The components are assembled using bolts and nuts, allowing for flexible installation and placement on any part of the experimental platform. The cryogenic cold source can be changed according to the temperature range, making it suitable for near-field radiation measurements in different cryogenic temperature ranges, such as liquid nitrogen and liquid helium. Each component of this invention is assembled independently, allowing for easy replacement of any faulty component without replacing the entire device. Furthermore, when not in use, each part can be disassembled and stored, saving space. This device solves the problems of cumbersome operation and material waste associated with using fixed-spacing nanopillars or particles. It is more convenient and efficient for studying the near-field radiation characteristics of materials with different micro / nano spacings at low temperatures.

[0049] In the actual measurement process:

[0050] Step 1: Calorimeter rod calibration

[0051] During calibration, the temperature of the transmitting sample is controlled to be consistent with that of the mounting component, and the heating amount Q of the absorbing sample is...R Record the temperature T of the sample at the absorption end. A Reference plate temperature T K Adjust Q R The size of Q is determined by repeating the experiment. R With T A -T K The relationship.

[0052] Step 2: Emissivity Test

[0053] During emissivity testing, a given temperature T of the emitter sample is used. R Record the temperature T of the sample at the absorption end. A Reference plate temperature T K Meanwhile, the heat absorbed by the sample at the absorption end, Q, was obtained by reverse calibration curve. A Value size. T is calculated using the following formula. A T R Q A The value is used to calculate the emissivity of the transmitter sample. Where: ε RA Q represents the emissivity of the sample under test. A The heat absorbed by the sample at the absorption end; A is the surface area of ​​the sample to be measured (known); σ is the Stefan-Boltzmann constant (known); T R T A These represent the temperatures of the emitting and absorbing sample pieces, respectively.

[0054] The temperatures of the absorber sample 21, emitter sample 22, and reference plate 27 are adjusted using heating elements. Temperature sensors monitor the temperatures of the absorber sample 21 and emitter sample 22, transmitting the monitored temperature signals to an external control system 300. The control system then regulates the temperature, precisely adjusting the sample temperatures to allow variations from 77K to 300K. Specifically, the heating element is located on the back of the mounting component 291, and the heating temperature is transmitted to the emitter sample 21 via a thermal connection. The heating element is also located on the back of the absorber sample 22. The temperature sensor transmits the monitored temperature signals of the absorber sample 22 and emitter sample 21 to the external control system 300. Upon receiving the monitored temperature signals, the operator can use the control system 300 to achieve real-time temperature control of the absorber sample 22 and emitter sample 21, maintaining a constant ambient temperature within a certain range (77K to 300K) for testing samples in various stable temperature zones.

[0055] Third step, pre-tightening

[0056] The control system 300 can control the adjusting structure to ensure smooth axial movement of the moving rod 241. After the experiment begins, the operator can control the drive component 242 via the control system 300 to move the moving rod 241. The leveling structure 23 is fixed to the emitting sample 21. During sample installation, the downward preload of the moving rod 241 presses the emitting sample 21 and the absorbing sample 22 tightly together. At this time, the leveling structure 23 uses static friction to keep the emitting sample 21 and the absorbing sample 22 relatively parallel. When the moving rod 241 moves upward, the leveling structure 23 ensures that the emitting sample 21 and the absorbing sample 22 are parallel to each other.

[0057] Step 4: Cool down

[0058] Vacuum tube 1 is placed directly in the liquid nitrogen Dewar 400, allowing it to quickly reach liquid nitrogen temperature. Thermal grease is applied to the surface of the positioning groove, causing heat sink 26 to cool rapidly. Furthermore, the calorimeter rod 28 is screwed to the absorber sample 22 and reference plate 27 at both ends, with the cooling direction as follows: heat sink 26 → reference plate 27 → calorimeter rod 28 → absorber sample 22. Because the emitter sample 21 and absorber sample 22 are pressed tightly together, the emitter sample 21 also cools rapidly until all components below the thermal insulation component 243 are cooled to liquid nitrogen temperature.

[0059] Step 5, adjust the distance

[0060] Both the absorber sample 22 and the emitter sample 21 have connecting electrodes on their backs, which are used to connect to the positive and negative terminals of the external capacitance sensor 200, respectively. The capacitance changes with the distance between the two samples, satisfying the following relationship: C = εA / d; where: C is the capacitance, ε is the dielectric constant of vacuum (known), A is the surface area of ​​the sample to be measured (known), and d is the distance between the emitter sample and the absorber sample. The operator can monitor the distance between the absorber sample 22 and the emitter sample 21 in real time through the capacitance sensor 200.

[0061] Step 6: Temperature control and calorific value measurement

[0062] The control system 300 controls the gap adjustment structure to create a gap between the absorber sample 22 and the emitter sample 21. At this time, the emitter sample 21 is disconnected from the cold source, and the heating element is turned on to control the temperature of the emitter sample 21. When the temperature is stable, the temperature of the absorber sample 22 is recorded, and the heat flux density is measured through the relationship calibrated by the calorimeter rod 28.

[0063] In summary, this invention achieves controllable adjustment of the micro-nano-level spacing between the transmitting and receiving ends through the precise coordination of the driving component and the moving rod. Compared to traditional testing methods that require repeated replacement of samples with fixed spacing, this design significantly improves the testing efficiency of the same sample. Specifically, by precisely adjusting the driving component to drive the moving rod to perform micro-nano-level displacement, since the transmitting and receiving sample pieces are already pressed and locked in a parallel state through the leveling structure during initial installation, even during the upward movement of the moving rod, the strict parallel alignment of the transmitting and receiving sample pieces can still be ensured. This invention enables accurate measurement of near-field radiation. Unlike far-field radiation, when the radiation spacing is less than or equal to the radiation wavelength (usually on the micro-nano scale), the radiation energy significantly increases as the spacing decreases. By achieving precise micro-nano-level spacing adjustment, this invention can effectively observe the significant enhancement effect of near-field radiation. This real-time adjustable micro-nano-spacing structure provides a powerful tool for studying the near-field radiation characteristics under different spacing conditions. The application scope of this invention is not limited to the research of single materials, but can also be extended to the near-field radiation performance testing of different material systems under different temperatures and spacing conditions, which has broad application prospects and research value.

[0064] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.

Claims

1. An apparatus for measuring near-field radiative emission at low temperatures, characterized in that, The application relates to a vacuum tube with a hollow inner cavity and a measuring mechanism fixed in the vacuum tube. The measuring mechanism comprises an adjusting assembly, a transmitting end sample piece connected with the adjusting assembly and an absorbing end sample piece corresponding to the transmitting end sample piece. The adjusting assembly comprises a leveling structure for adjusting parallelism between the transmitting end sample piece and the absorbing end sample piece and a distance adjusting structure for adjusting the distance between the transmitting end sample piece and the absorbing end sample piece. The distance adjusting structure comprises a moving rod axially movable along the vacuum tube, a driving piece for driving the moving rod to move and a thermal insulation piece connected with one end of the moving rod; the leveling structure and the thermal insulation piece are fixed, and the transmitting end sample piece is fixed with the leveling structure. The distance adjusting structure is configured to drive the leveling structure and the transmitting end sample piece to move axially along the vacuum tube to approach or move away from the absorbing end sample piece. The leveling structure is configured to make the lower surface of the transmitting end sample piece fit the upper surface of the absorbing end sample piece and keep the lower surface of the transmitting end sample piece and the upper surface of the absorbing end sample piece in a relatively parallel state under the driving of the distance adjusting structure. The measuring mechanism further comprises a shielding cover fixed in the vacuum tube; the transmitting end sample piece, the absorbing end sample piece, the thermal insulation piece and the leveling structure are located in the shielding cover.

2. The apparatus for measuring near-field radiative emission rate at low temperatures according to claim 1, wherein, The distance adjusting structure further comprises a hollow tube fixed with the shielding cover; the hollow tube is coaxially arranged with the shielding cover; the driving piece is fixed on the top wall of the hollow tube, and the driving end of the driving piece extends into the hollow tube; the top end of the moving rod is correspondingly matched with the driving end of the driving piece, and the bottom end of the moving rod penetrates through the bottom wall of the hollow tube and extends into the shielding cover to be connected with the thermal insulation piece.

3. The apparatus for measuring near-field radiative emission rate at low temperatures according to claim 2, wherein, The driving piece comprises a fitting piece with a through hole for being fixed with the top wall of the hollow tube, a piezoelectric inertia motor fixed with the fitting piece and a screw rod matched with the piezoelectric inertia motor; the moving rod is connected with the inner surface of the top wall of the hollow tube through an elastic piece; the through hole has an internal thread and is communicated with the hollow tube; the screw rod is screwed in the through hole; the lower end surface of the screw rod is an arc surface; the top end of the moving rod is formed with a groove matched with the lower end of the screw rod; the screw rod can drive the moving rod to move downward along the axis of the vacuum tube under the driving of the piezoelectric inertia motor.

4. The apparatus for measuring near-field radiative emission rate at low temperatures according to claim 3, wherein, The leveling structure comprises a positioning piece fixed with the thermal insulation piece, an adjusting piece for fixing the transmitting end sample piece, a first matching piece arranged on the positioning piece, a second matching piece arranged on the adjusting piece and an elastic piece connected with the positioning piece and the adjusting piece at two ends; the first matching piece and the second matching piece are abutted and form a static friction fit under the elastic force of the elastic piece; the adjusting piece is configured to overcome the static friction force between the first matching piece and the second matching piece under the driving of the distance adjusting structure, so that the lower surface of the transmitting end sample piece fits the upper surface of the absorbing end sample piece.

5. The apparatus for measuring near-field radiative emission rate at low temperatures of claim 1, wherein, The number of the first matching pieces, the second matching pieces and the elastic pieces is at least three; the first matching pieces are uniformly arranged along the circumference of the positioning piece, and the second matching pieces are uniformly arranged along the circumference of the adjusting piece; the axis of the first matching piece and the axis of the second matching piece are perpendicular, and the circumferential side wall of the first matching piece is abutted with the circumferential side wall of the second matching piece.

6. The device for measuring near-field radiative emission at cryogenic temperatures of claim 5, wherein, ​ 7. The apparatus for measuring near-field radiative emission rate at low temperatures of claim 1, wherein, The measuring mechanism further comprises a heat sink fixed to the bottom wall of the vacuum tube, a reference plate fixed to the upper surface of the heat sink, and a calorimetric rod fixed to the reference plate and arranged along the axial direction of the vacuum tube, wherein the top end of the calorimetric rod is connected to the sample piece at the absorbing end; and the upper surface of the reference plate is provided with a thermal insulation layer.

8. The apparatus for measuring near-field radiative emission rate at low temperatures of claim 1, wherein, The leveling structure is fixed to the thermal insulation member through a mounting member; the upper surface of the mounting member is provided with a heating sheet and a temperature sensor, and the lower surface of the sample piece at the absorbing end is provided with a heating sheet and a temperature sensor.

9. The apparatus for measuring near-field radiative emission rate at low temperatures of claim 3, wherein, The shielding cover comprises an inner cover body and an outer cover body arranged coaxially and a thermal insulation layer arranged between the inner cover body and the outer cover body; the inner cover body is fixed to the bottom wall of the hollow tube, and the outer cover body is fixed to the circumferential side wall of the hollow tube.

10. An apparatus for measuring near-field radiative emission at cryogenic temperatures, comprising: The device for measuring the near-field radiation emissivity at low temperature comprises the device for measuring the near-field radiation emissivity at low temperature according to any one of claims 1-9; the device further comprises a capacitive sensor, a control system, a liquid nitrogen Dewar, a vacuum pump and an optical shockproof platform; the vacuum tube is provided with a first interface and a second interface; the liquid nitrogen Dewar is arranged on the optical shockproof platform, and the vacuum tube is immersed in the liquid nitrogen Dewar; The capacitive sensor is electrically connected to the sample piece at the emitting end and the sample piece at the absorbing end through the first interface to monitor the distance between the sample piece at the emitting end and the sample piece at the absorbing end; the control system is electrically connected to the driving member through the first interface to control the start and stop of the driving member; the vacuum pump is in vacuum sealing connection with the second interface to extract air in the vacuum tube; and the liquid nitrogen Dewar is used to provide an experimental environment.

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