A gallium fixed point based on-orbit calibration blackbody

Abstract

This invention discloses an on-orbit calibration blackbody based on gallium fixed points. The blackbody includes a blackbody main component, a heating element (5), and a temperature measuring unit (8). The blackbody main component includes a bottom cover (7), a top cover (4), and metallic gallium. The bottom cover (7) is made of single-crystal silicon, on which carbon nanotubes are grown. The top cover (4) has a cylindrical cavity structure. The top cover (4) and the bottom cover (7) are sealed and pressed together, and the cavity formed by them is used to fill metallic gallium. The temperature measuring unit (8) and the heating element (5) are mounted on the surface of the top cover (4). This invention utilizes the melting point of metallic gallium as a temperature reference, eliminating concerns about inaccurate blackbody temperature even after long-term use, and meeting the traceability requirements of space payloads.

Description

Technical Field

[0001] This invention belongs to the field of optical testing technology, specifically relating to an on-orbit calibration blackbody based on gallium fixed points and its assembly method. Background Technology

[0002] Earth observation utilizes spacecraft and ground-based monitoring platforms to explore planets and human activities. It primarily includes satellite navigation and positioning, space infrared remote sensing, aerospace geophysical exploration, and the processing and utilization of Earth observation data. From weather forecasting to monitoring natural disasters and ecosystems, human social life, and geophysical and atmospheric science research, Earth observation data provides crucial information support for related research and decision-making. For space payloads, traceable calibration is performed before launch, but this method cannot guarantee the long-term validity of measurements during on-orbit operation. Therefore, on-orbit measurement traceability technology is crucial; it is an effective way to improve the calibration accuracy of space sensors.

[0003] An in-orbit calibrated blackbody serves as a reference for infrared radiation instruments. Embedded within the instrument as a component of the spacecraft, it is used for space payload calibration. Blackbody radiation is calculated using Planck's equations under known thermodynamic temperatures. However, even with pre-flight calibration, the accuracy of the calibrated target cannot be guaranteed due to long-term temperature detector drift and oxidation of the blackbody cavity surface in the near-Earth orbit environment, failing to meet the low uncertainty requirements for climate measurements. Therefore, to achieve the low uncertainty required for in-orbit measurements, a traceable space-based reference blackbody source must be designed. Summary of the Invention

[0004] The purpose of this invention is to provide a traceable spatial reference blackbody source to meet the traceability requirements of spatial payload values.

[0005] To achieve the objective of this invention, this invention provides an on-orbit calibrated blackbody based on gallium fixed points, and the technical solution is as follows:

[0006] The blackbody includes a blackbody main component, a heating element, and a temperature measuring unit.

[0007] The blackbody component includes a bottom cover, a top cover, and gallium metal. The bottom cover is made of single-crystal silicon, on which carbon nanotubes are grown. The top cover has a cylindrical cavity structure. The top cover and the bottom cover are sealed and pressed together, and the cavity they form is used to fill gallium metal.

[0008] The temperature measuring unit and the heating element are mounted on the surface of the top cover.

[0009] Furthermore, the temperature measuring unit is fixed in the groove at the center of the top cover, close to the radiating surface; the heating element uses two polyimide sheets as a base, with a resistance wire sandwiched in between; the resistance wire is made of nickel-chromium alloy.

[0010] Furthermore, it also includes a heat insulation component and a housing. The heat insulation component has a cylindrical cavity structure, and the housing and heat insulation component enclose the blackbody main component, the temperature measuring unit, and the heating element.

[0011] Furthermore, the heat insulation component is coated with a polytetrafluoroethylene protective layer; the outer shell is made of titanium alloy.

[0012] Furthermore, it also includes conductive components, which provide heating and power paths for the heating element and temperature measuring unit, and whose wiring is led out through the central hole of the heating element and heat insulation component.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] Existing on-orbit calibrated blackbodies use temperature sensors pre-calibrated on the ground as a temperature reference. After prolonged operation, the calibrated temperature of these sensors may deviate, and this deviation cannot be detected. Compared to existing on-orbit calibrated blackbodies, this invention utilizes the melting point of gallium as a temperature reference. Even after prolonged use, there is no need to worry about inaccurate blackbodi temperatures, thus meeting the traceability requirements of space payloads. Attached Figure Description

[0015] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0016] Figure 1 The diagram shows a schematic of an on-orbit calibration blackbody based on gallium fixed points provided by an embodiment of the present invention.

[0017] Figure 2 A longitudinal cross-sectional view of an on-orbit calibration blackbody based on gallium fixed points provided in an embodiment of the present invention is shown.

[0018] The above figures include the following reference numerals:

[0019] 1. Outer shell, 2. Gasket, 3. Rubber ring, 4. Top cover, 5. Heating element, 6. Heat insulation component, 7. Bottom cover, 8. Temperature measuring unit, 9. Polytetrafluoroethylene protective layer. Detailed Implementation

[0020] The invention will be further described below with reference to the accompanying drawings.

[0021] As an embodiment of the present invention, an on-orbit calibration blackbody based on a gallium fixed point is provided, such as Figure 1 As shown, it includes a blackbody main component, a housing 1, a gasket 2, a heating element 5, a heat insulation component 6, a temperature measuring unit 8, a polytetrafluoroethylene protective layer 9, and conductive components.

[0022] The blackbody component consists of a bottom cover 7, a rubber ring 3, a top cover 4, and gallium metal. The bottom cover 7 is made of monocrystalline silicon, and carbon nanotubes are grown on the monocrystalline silicon substrate to ensure emissivity. The top cover 4 is a cylindrical cavity structure made of stainless steel. The top cover 4 and the bottom cover 7 are sealed together by a silicone rubber ring 3, and the cavity formed by them is used to fill gallium metal.

[0023] The temperature measuring unit 8 measures the temperature of the radiating surface using a temperature sensor. The temperature measuring unit 8 is directly mounted on the surface of the stainless steel top cover 4 of the gallium fixed-point blackbody using an adhesive bonding method. The mounting position is designed within the central groove of the stainless steel top cover 4, and is positioned as close as possible to the radiating surface to obtain a temperature value that is close to that of the radiating surface.

[0024] The heating element 5 is located on the surface of the top cover 4 and controls the temperature of the gallium fixed-point calibration blackbody in orbit. The heating element 5 uses two polyimide sheets as a substrate with a resistance wire sandwiched in between. The resistance wire is connected to a power source to form a closed circuit. The resistance wire is made of nickel-chromium alloy, which has high resistivity and good high-temperature oxidation resistance, enabling high-precision temperature control and maintaining the blackbody temperature within a stable range, thus ensuring the stability of the blackbody radiation value during the calibration process.

[0025] The heat insulation component 6 is a cylindrical cavity structure coated with a polytetrafluoroethylene (PTFE) protective layer 9. The outer shell 1 is made of titanium alloy. The outer shell 1 and the heat insulation component 6 are fastened together with screws and washers 2, enclosing the blackbody main component, temperature measuring unit 8, and heating element 5. The main function of the outer shell 1 and the PTFE protective layer of the heat insulation component 6 is to provide solid support and fixation for the radiating surface of the blackbody main component, while also serving as thermal insulation to ensure minimal heat leakage between the blackbody main component and the mounting structure. This helps to ensure the platform time and reduces the impact on the overall thermal control design of the load.

[0026] The conductive component provides heating and power paths for the heating element 5 and the temperature measuring unit 8, and its wiring is led out through the central hole of the heating element 5 and the heat insulation component 6. After being heated by electricity, the gallium metal undergoes a phase transition. At the plateau temperature of the phase transition, the fixed-point blackbody can be used as a standard radiation source for load radiation calibration.

[0027] Figure 2This diagram shows a longitudinal half-section of an on-orbit calibrated blackbody based on gallium fixed points, provided by an embodiment of the present invention.

[0028] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, components, or combinations thereof.

[0029] Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0031] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. An on-orbit calibration blackbody based on gallium fixed points, characterized in that, The blackbody includes: a blackbody main component, a heating element (5), and a temperature measuring unit (8). The blackbody main component includes a bottom cover (7), a top cover (4), and gallium metal. The bottom cover (7) is made of single-crystal silicon, and carbon nanotubes are grown on the single-crystal silicon substrate. The top cover (4) is a cylindrical cavity structure. The top cover (4) and the bottom cover (7) are sealed and pressed together, and the cavity they form is used to fill gallium metal. The temperature measuring unit (8) and the heating element (5) are installed on the surface of the top cover (4).

2. The on-orbit calibration blackbody based on gallium fixed points according to claim 1, characterized in that, The temperature measuring unit (8) is fixed in the groove in the center of the top cover (4), close to the radiation surface.

3. The on-orbit calibration blackbody based on gallium fixed points according to claim 1, characterized in that, The heating element (5) uses two polyimide substrates with a resistance wire sandwiched in between.

4. The on-orbit calibration blackbody based on gallium fixed points according to claim 3, characterized in that, The resistance wire is made of nickel-chromium alloy.

5. The on-orbit calibration blackbody based on gallium fixed points according to claim 1, characterized in that, It also includes a heat insulation component (6) and a housing (1). The heat insulation component (6) is a cylindrical cavity structure. The housing (1) and the heat insulation component (6) enclose the blackbody main component, the temperature measuring unit (8) and the heating element (5) within it.

6. The on-orbit calibration blackbody based on gallium fixed points according to claim 5, characterized in that, The heat insulation component (6) is coated with a polytetrafluoroethylene protective layer (9).

7. The on-orbit calibration blackbody based on gallium fixed points according to claim 6, characterized in that, The outer shell (1) is made of titanium alloy.

8. The on-orbit calibration blackbody based on gallium fixed points according to claim 5, characterized in that, It also includes conductive components, which provide heating and power paths for the heating element (5) and the temperature measuring unit (8), and their wiring is led out through the central hole of the heating element (5) and the heat insulation component (6).

Images