Gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working medium storage tank

Abstract

The invention discloses a gradient porosity foam nickel-based porous iodine storage structure for a hollow cathode iodine working medium storage tank, belongs to the technical field of spacecraft electric propulsion, and solves the problems that an existing iodine working medium storage tank is low in heat transfer efficiency, low in working medium utilization rate, insufficient in microgravity adaptability, poor in temperature uniformity and insufficient in moving part reliability. Comprising a storage tank main body and a porous iodine storage mechanism, and the porous iodine storage mechanism comprises a bottom heating surface layer, a middle iodine storage main body layer and a top steam escape layer; in the embodiment of the invention, the porous iodine storage mechanism realizes functional partition of bottom-layer enhanced heat transfer, middle-layer efficient iodine storage and top-layer low-resistance escape, meanwhile, by virtue of a capillary force constraint mechanism of micron-sized pores, the utilization rate of an iodine working medium reaches 95% or above, and the problem that liquid iodine floats in a microgravity environment is solved; the heat transfer efficiency, the flow supply stability and the on-orbit service life of the iodine working medium storage tank are obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft electric propulsion technology, specifically relating to a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks. Background Technology

[0002] Iodine, due to its significant advantages such as high storage density, low ionization energy, and low cost, is considered the most promising next-generation electric propulsion propellant to replace xenon, with broad application prospects in spacecraft attitude control, orbital transfer, and other missions. However, iodine is solid at room temperature and pressure, and needs to be heated to a certain temperature to sublimate it into vapor, which is then supplied to a hollow cathode to generate plasma. Precise control of this solid-vapor phase transition process is the core challenge for the practical application of iodine-based electric propulsion technology.

[0003] Currently, the following technical solutions are mainly used for iodine storage tanks: This integrated heated iodine storage tank utilizes a sealed connection between a top cover assembly and a lower shell assembly. Solid iodine is directly filled into the lower shell. A porous material plate is installed on one side of the top cover assembly, contacting the solid iodine on one side and housing a heater on the other. A tray spring and tray structure press the iodine against the porous material plate, ensuring contact between the heated surfaces. The working principle involves the heater heating the porous material plate, transferring heat to the solid iodine in contact with it. The iodine sublimates upon heating, producing vapor, which is then filtered through the porous material plate before being output.

[0004] This spring-piston type iodine working medium storage tank uses a piston structure to press solid iodine onto a heating surface. A spring at the rear of the piston provides continuous pressure. As iodine is consumed, the piston moves forward under the action of the spring, ensuring that the iodine remains in contact with the heating surface. Its working principle is that the heater heats the heating surface, and the solid iodine sublimates into vapor in the area in contact with the heating surface. The spring pushes the piston, continuously replenishing the heating area with iodine.

[0005] The thermal radiation heating storage tank uses MCH ceramic heating elements as the heat radiation source. The iodine working medium is fixed in place by a mesh, gaskets, and springs, maintaining a constant position between the heated surface of the working medium and the heating elements. Its working principle is that the heating elements radiate heat to the fixed heating surface, and the heat is transferred to the iodine working medium through radiation, causing it to sublimate and produce steam.

[0006] However, the aforementioned existing technical solutions all have obvious technical defects in practical applications, which restrict the application of iodine working fluid electric propulsion systems: Due to its low heat transfer efficiency and extremely low thermal conductivity (approximately 0.4 W / (m·K)), traditional storage tanks employ external heating methods, resulting in slow and uneven heat transfer, making it difficult to achieve rapid response and precise sublimation rate control.

[0007] The working fluid utilization rate is low. After iodine sublimates, it loses contact with the heating surface, creating a void effect, resulting in a large amount of residual iodine that cannot be effectively utilized. Especially in long-term on-orbit missions, the working fluid utilization rate is often below 70%, severely limiting the mission's lifespan.

[0008] The microgravity adaptability is insufficient. Liquid iodine is prone to floating in a microgravity environment and cannot remain stably in the heating area, resulting in gas-liquid entrainment and unstable supply flow, which affects the working stability of the thruster.

[0009] Poor temperature uniformity and significant temperature gradients within the storage tank create hot and cold zones. Localized overheating can lead to uncontrolled sublimation, while localized underheating can cause supply interruptions, threatening the continuous and reliable operation of the thruster.

[0010] The reliability of moving parts is a concern. Moving parts such as springs and pistons are prone to jamming and wear in long-term on-orbit environments, which affects the long-term reliability of the system.

[0011] To address the problems of low heat transfer efficiency, low working fluid utilization, insufficient microgravity adaptability, poor temperature uniformity, and insufficient reliability of moving parts in existing iodine working fluid storage tanks, we propose a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks. Summary of the Invention

[0012] The purpose of this invention is to address the shortcomings of existing technologies by providing a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks. This solves the problems of low heat transfer efficiency, low working fluid utilization, insufficient microgravity adaptability, poor temperature uniformity, and insufficient reliability of moving parts in existing iodine working fluid storage tanks.

[0013] Existing iodine working fluid storage tanks suffer from low heat transfer efficiency, low working fluid utilization, insufficient microgravity adaptability, poor temperature uniformity, and insufficient reliability of moving parts. To address these issues, we propose a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks. In short, it includes a tank body and a porous iodine storage mechanism, which comprises a bottom heating surface layer, a middle iodine storage body layer, and a top vapor escape layer. In this embodiment of the invention, the porous iodine storage mechanism achieves functional partitioning with enhanced heat transfer at the bottom layer, efficient iodine storage in the middle layer, and low-resistance evaporation at the top layer. By utilizing a three-dimensional interconnected nickel framework, the thermal conductivity is increased to 5-8 W / (m·K), and the preheating time is shortened by more than 70% to 3-5 minutes. At the same time, by leveraging the capillary force binding mechanism of micron-sized pores, the utilization rate of the iodine working medium reaches more than 95%, solving the problem of liquid iodine floating in microgravity environments and eliminating the reliability hazards caused by moving parts such as spring pistons. The temperature difference between each layer is controlled within 5°C, significantly improving the heat transfer efficiency, supply stability, and on-orbit service life of the iodine working medium storage tank.

[0014] This invention is implemented as follows: a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working medium storage tanks, wherein the gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working medium storage tanks comprises: The storage tank body includes a storage tank shell and a storage tank cavity, wherein the storage tank cavity is disposed within the storage tank shell; A porous iodine storage mechanism is installed inside the storage tank. The porous iodine storage mechanism is used to store iodine working substance. The porous iodine storage mechanism includes at least three layers of nickel foam with different porosities stacked along the height direction.

[0015] Preferably, the main body of the storage tank further includes: A heater is fixedly installed at the bottom of the inner cavity of the storage tank, and the heater is used to heat the porous iodine storage mechanism. A steam chamber is located at the top of the inner cavity of the storage tank; A steam outlet connected to the steam chamber is located at the top of the tank shell and is used to assist in the discharge of iodine vapor. An insulation layer is installed on the inner surface of the storage tank to provide auxiliary insulation for the porous iodine storage mechanism.

[0016] Preferably, the porous iodine storage mechanism comprises: The bottom heating surface layer is in direct contact with the heater at the bottom of the storage tank for rapid heat transfer. The middle iodine storage layer is used to provide storage space for iodine working medium; The top vapor escape layer is used to reduce the flow resistance of iodine vapor.

[0017] Preferably, the bottom heating surface layer, the middle iodine storage body layer, and the top steam escaping layer are arranged sequentially from bottom to top. The bottom heating surface layer and the middle iodine storage body layer, and the middle iodine storage body layer and the top steam escaping layer are formed by high-temperature vacuum sintering to form a metallurgical bonding interface. The connecting pores of the bottom heating surface layer, the middle iodine storage body layer, and the top steam escaping layer are filled with solid iodine working fluid.

[0018] Preferably, the porosity of the bottom heating surface layer is 70%-75%, the pore size of the bottom heating surface layer is 50-80μm, and the thickness of the bottom heating surface layer accounts for 20%-25% of the total thickness of the porous iodine storage mechanism.

[0019] Preferably, the porosity of the middle iodine storage layer is 82%-88%, the pore size of the middle iodine storage layer is 200-250 μm, and the thickness of the middle iodine storage layer accounts for 45%-55% of the total thickness; The porosity of the top vapor escape layer is 92%-95%, the pore size of the top vapor escape layer is 350-450μm, and the thickness of the top vapor escape layer accounts for 20%-25% of the total thickness.

[0020] Preferably, the nickel foam layer has a three-dimensional interconnected open structure, which includes ribs and pores. The cross-section of the ribs is triangular or quadrilateral, and the diameter of the ribs varies with the layer position.

[0021] Preferably, the diameter of the pores in the bottom heating layer is 30-50 μm, the diameter of the pores in the middle iodine storage layer is 20-30 μm, and the diameter of the pores in the top vapor escape layer is 10-20 μm.

[0022] Preferably, the porosity of the porous iodine storage mechanism increases monotonically along the height direction, with a gradient change rate of 0.5-1.0% / mm.

[0023] Compared with the prior art, the embodiments of this application have the following main advantages: In this embodiment of the invention, the porous iodine storage mechanism achieves functional partitioning with enhanced heat transfer at the bottom layer, efficient iodine storage in the middle layer, and low-resistance evaporation at the top layer. By utilizing a three-dimensional interconnected nickel framework, the thermal conductivity is increased to 5-8 W / (m·K), and the preheating time is shortened by more than 70% to 3-5 minutes. At the same time, by leveraging the capillary force binding mechanism of micron-sized pores, the utilization rate of the iodine working medium reaches more than 95%, solving the problem of liquid iodine floating in microgravity environments and eliminating the reliability hazards caused by moving parts such as spring pistons. The temperature difference between each layer is controlled within 5°C, significantly improving the heat transfer efficiency, supply stability, and on-orbit service life of the iodine working medium storage tank. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks provided by the present invention.

[0025] Figure 2 A schematic diagram of the structure of the nickel foam layer in an embodiment of the present invention is shown.

[0026] In the figure: 1-tank body, 11-tank shell, 12-tank cavity, 13-heater, 14-steam chamber, 15-steam outlet, 16-insulation layer, 2-porous iodine storage mechanism, 21-bottom heating surface layer, 22-middle iodine storage body layer, 23-top steam escape layer, 24-metallurgical bonding interface. Detailed Implementation

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] Existing iodine working fluid storage tanks suffer from low heat transfer efficiency, low working fluid utilization, insufficient microgravity adaptability, poor temperature uniformity, and insufficient reliability of moving parts. To address these issues, we propose a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks. In short, it includes a tank body 1 and a porous iodine storage mechanism 2. The porous iodine storage mechanism 2 includes a bottom heating surface layer 21, a middle iodine storage body layer 22, and a top vapor escape layer 23. In this embodiment of the invention, the porous iodine storage mechanism 2 achieves functional partitioning with enhanced heat transfer at the bottom layer, efficient iodine storage in the middle layer, and low-resistance evacuation at the top layer. By utilizing a three-dimensional interconnected nickel framework, the thermal conductivity is increased to 5-8 W / (m·K), and the preheating time is shortened by more than 70% to 3-5 minutes. At the same time, by utilizing the capillary force binding mechanism of micron-sized pores, the utilization rate of iodine working medium reaches more than 95%, solving the problem of liquid iodine floating in microgravity environment and eliminating the reliability hazards caused by moving parts such as spring pistons. The temperature difference between each layer is controlled within 5°C, which significantly improves the heat transfer efficiency, supply stability, and on-orbit working life of the iodine working medium storage tank.

[0030] Example 1 This invention provides a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks, such as... Figure 1 As shown, the gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank specifically includes: The storage tank body 1 includes a storage tank shell 11 and a storage tank inner cavity 12, wherein the storage tank inner cavity 12 is disposed within the storage tank shell 11; A porous iodine storage mechanism 2 is disposed inside the inner cavity 12 of the storage tank. The porous iodine storage mechanism 2 is used to store iodine working substance. The porous iodine storage mechanism 2 includes at least three layers of nickel foam with different porosities stacked together along the height direction.

[0031] In this embodiment, the storage tank body 1 further includes: Heater 13 is fixedly installed at the bottom of the inner cavity 12 of the storage tank. Heater 13 is used to heat the porous iodine storage mechanism 2. Heater 13 can be an electric heating rod or a resistance wire. Heater 13 is fixedly installed at the bottom of the inner cavity 12 of the storage tank by welding or snap-fit. A steam chamber 14 is disposed at the top of the inner cavity 12 of the storage tank, and the steam chamber 14 is in communication with the inner cavity 12 of the storage tank; A steam outlet 15 is connected to the steam chamber 14. The steam outlet 15 is located at the top of the tank shell 11 and is used to assist in the discharge of iodine vapor. The insulation layer 16 is disposed on the surface of the inner cavity 12 of the storage tank and is used to provide auxiliary insulation for the porous iodine storage mechanism 2. The insulation layer 16 is an aluminized polyimide film or an alumina fiber material.

[0032] In this embodiment of the invention, the porous iodine storage mechanism 2 achieves functional partitioning with enhanced heat transfer at the bottom layer, efficient iodine storage in the middle layer, and low-resistance evacuation at the top layer. By utilizing a three-dimensional interconnected nickel framework, the thermal conductivity is increased to 5-8 W / (m·K), and the preheating time is shortened by more than 70% to 3-5 minutes. At the same time, by utilizing the capillary force binding mechanism of micron-sized pores, the utilization rate of iodine working medium reaches more than 95%, solving the problem of liquid iodine floating in microgravity environment and eliminating the reliability hazards caused by moving parts such as spring pistons. The temperature difference between each layer is controlled within 5°C, which significantly improves the heat transfer efficiency, supply stability, and on-orbit working life of the iodine working medium storage tank.

[0033] In a further preferred embodiment of the present invention, such as Figure 1 As shown, the porous iodine storage mechanism 2 includes: The bottom heating surface layer 21 is in direct contact with the bottom heater 13 of the storage tank for rapid heat transfer. The porosity of the bottom heating surface layer 21 is 70%-75%, the pore size is 50-80μm, and the thickness of the bottom heating surface layer 21 accounts for 20%-25% of the total thickness of the porous iodine storage mechanism 2.

[0034] The middle iodine storage layer 22 is used to provide storage space for iodine working medium; the porosity of the middle iodine storage layer 22 is 82%-88%, the pore size of the middle iodine storage layer 22 is 200-250μm, and the thickness of the middle iodine storage layer 22 accounts for 45%-55% of the total thickness.

[0035] The top vapor escape layer 23 is used to reduce the flow resistance of iodine vapor. The porosity of the top vapor escape layer 23 is 92%-95%, the pore size is 350-450μm, and the thickness of the top vapor escape layer 23 accounts for 20%-25% of the total thickness.

[0036] In this embodiment, the porous iodine storage mechanism 2 is cylindrical in shape, with a diameter consistent with the inner diameter of the storage tank, ensuring a tight fit with the tank wall. Three layers of nickel foam with different porosities form the bottom heating surface layer 21, the middle iodine storage body layer 22, and the top steam escape layer 23. That is, the nickel foam layer forms the base structure of the bottom heating surface layer 21, the middle iodine storage body layer 22, and the top steam escape layer 23. The nickel foam layer has a three-dimensional interconnected open-pore structure, including pore ribs and pores. The pore ribs have triangular or quadrilateral cross-sections, which maximize heat transfer efficiency while ensuring structural strength. The pores are completely interconnected, forming a three-dimensional network of gas channels. The diameter of the pore ribs varies with the layer position (bottom heating surface layer 21, middle iodine storage body layer 22, top steam escape layer 23). Figure 2 As shown, the nickel skeleton of the foamed nickel layer is composed of pure nickel with a nickel content of ≥99.5%, and does not contain elements such as chromium (Cr) and iron (Fe) that are prone to selective corrosion by iodine. Figure 2 The nickel skeleton in the middle can correspond to the foamed nickel layer of the bottom heating surface layer 21, the middle iodine storage body layer 22, or the top vapor escape layer 23. The porosity of the porous iodine storage mechanism 2 increases monotonically along the height direction with a gradient change rate of 0.5-1.0% / mm, while the diameter of the pores decreases from the bottom to the top, forming a gradient opposite to the change in porosity.

[0037] In another embodiment of the present invention, in addition to pure nickel foam metal, the porous iodine storage mechanism 2 can use foamed iron or iron-nickel alloy as the matrix material. Porous graphite or carbon foam can also be used as the matrix material to replace the foamed nickel layer, and carbon materials are extremely chemically inert in an iodine environment and do not react with iodine at all.

[0038] In a further preferred embodiment of the present invention, the diameter of the pores in the bottom heating layer 21 is 30-50 μm, the diameter of the pores in the middle iodine storage layer 22 is 20-30 μm, and the diameter of the pores in the top vapor escaping layer 23 is 10-20 μm.

[0039] In this embodiment of the invention, the bottom heating surface layer 21, the middle iodine storage body layer 22, and the top steam escaping layer 23 are arranged sequentially from bottom to top. A metallurgical bonding interface 24 is formed between the bottom heating surface layer 21 and the middle iodine storage body layer 22, and between the middle iodine storage body layer 22 and the top steam escaping layer 23, through high-temperature vacuum sintering. Solid iodine working fluid is filled into the interconnecting pores of the bottom heating surface layer 21, the middle iodine storage body layer 22, and the top steam escaping layer 23. The solid iodine working fluid is uniformly filled into the interconnecting pores of the nickel foam, with a filling rate ≥95%, and no visible voids or cavities. A micron-level tight contact interface is formed between the iodine working fluid and the nickel foam skeleton, with no gaps and an interface thermal resistance ≤0.01 m²·K / W. After 100 thermal cycles, the interface bonding is good, with no peeling or separation.

[0040] Example 2 In a further preferred embodiment of the present invention, the gradient porosity foam nickel-based porous iodine storage structure of the hollow cathode iodine working medium storage tank is used for iodine storage tanks for small satellites, and the iodine storage capacity of the small satellite iodine storage tank is 1 kg. This embodiment is designed for small satellite application scenarios, and an iodine working medium storage tank with a storage capacity of 1 kg is designed. The tank dimensions are Φ100mm×120mm, and the total thickness of the porous iodine storage mechanism 2 is 40mm.

[0041] The specific parameters of the three-layer gradient nickel foam, i.e., the porous iodine storage mechanism 2, are as follows: the bottom heating surface layer 21 has a porosity of 72%, a pore diameter of 60 μm, a thickness of 8 mm (accounting for 20% of the total thickness), and a pore diameter of 35 μm; the middle iodine storage body layer 22 has a porosity of 85%, a pore diameter of 220 μm, a thickness of 20 mm (accounting for 50% of the total thickness), and a pore diameter of 25 μm; the top vapor escape layer 23 has a porosity of 93%, a pore diameter of 400 μm, a thickness of 12 mm (accounting for 30% of the total thickness), and a pore diameter of 15 μm. The porosity gradient change rate is 0.7% / mm, and the nickel content of the nickel foam layer is 99.6%. During preparation, the three layers of nickel foam with different porosities are cut into Φ98 mm circles and sintered in a vacuum sintering furnace at 1000℃ for 10 minutes. -3Diffusion welding was performed for 2 hours under a vacuum of 10⁻³ Pa to achieve a metallurgical bond between the three layers. The bonded porous structure was then placed in a Φ100mm storage tank, ensuring a tight fit against the tank wall. In an inert atmosphere glove box (oxygen <1ppm, water <1ppm), after heating to 120℃, 1.2kg of molten iodine was slowly injected from the top, utilizing capillary force to automatically draw it into the pores. During injection, bottom vibration (frequency 50Hz, amplitude 0.5mm) was maintained to promote uniform iodine distribution. After cooling to room temperature and solidification, X-ray inspection confirmed a fill rate ≥96% with no visible voids. Performance testing was conducted in a simulated space environment (vacuum of 10⁻³Pa), with a heating power of 20W and a set temperature of 115℃. Test results showed: stable flow was achieved in 4 minutes and 20 seconds of preheating; flow fluctuation was ±3.2% after 100 hours of continuous operation; the working fluid utilization rate was 96.8% based on post-test weighing; and the temperature difference between layers was ≤4.5℃.

[0042] Example 3 In a further preferred embodiment of the present invention, the gradient porosity foam nickel-based porous iodine storage structure of the hollow cathode iodine working medium storage tank is used for iodine storage tanks for medium and large-sized satellites, and the iodine storage capacity of the medium and large-sized satellite iodine storage tank is 5 kg. This embodiment is designed for medium and large-sized satellite application scenarios, and an iodine working medium storage tank with a storage capacity of 5 kg is designed. The tank dimensions are Φ200mm×200mm, and the total thickness of the porous iodine storage mechanism 2 is 70mm.

[0043] In this embodiment, the porous iodine storage mechanism 2 is provided with five layers of nickel foam with different pore sizes. The specific parameters of the five gradient nickel foam layers are as follows: the bottom heating surface layer 21 has a porosity of 70%, a pore size of 50 μm, a thickness of 10 mm, and a pore diameter of 40 μm; the second bottom layer has a porosity of 75%, a pore size of 100 μm, a thickness of 15 mm, and a pore diameter of 32 μm; the middle iodine storage body layer 22 has a porosity of 82%, a pore size of 200 μm, a thickness of 20 mm, and a pore diameter of 25 μm; the second upper layer has a porosity of 88%, a pore size of 300 μm, a thickness of 15 mm, and a pore diameter of 18 μm; and the top vapor escape layer 23 has a porosity of 94%, a pore size of 450 μm, a thickness of 10 mm, and a pore diameter of 12 μm. The average porosity gradient change rate is 0.6% / mm, and the nickel content of the nickel foam is 99.7%. The preparation steps of the porous iodine storage mechanism 2 in this embodiment are similar to those in Embodiment 2, except for the addition of a five-layer stacking and sintering process. Performance testing employed a segmented temperature control method using a 1325W bottom heater and a 15W sidewall auxiliary heater. Test results showed that a stable flow was achieved in 5 minutes and 10 seconds of preheating; after 500 hours of continuous operation, the flow fluctuation was ±4.1%; the working fluid utilization rate was 97.2%; and the temperature difference between each layer was ≤5.2℃.

[0044] In summary, this invention provides a gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks. In the embodiments of this invention, the porous iodine storage mechanism 2 achieves functional partitioning with enhanced heat transfer at the bottom layer, efficient iodine storage in the middle layer, and low-resistance escape at the top layer. The thermal conductivity is increased to 5-8 W / (m·K) by utilizing a three-dimensional interconnected nickel skeleton, and the preheating time is shortened by more than 70% to 3-5 minutes. At the same time, the capillary force binding mechanism of the micron-level pores enables the utilization rate of the iodine working fluid to reach more than 95%, solving the problem of liquid iodine floating in microgravity environments and eliminating the reliability hazards caused by moving parts such as spring pistons. The temperature difference between each layer is controlled within 5°C, significantly improving the heat transfer efficiency, supply stability, and on-orbit service life of the iodine working fluid storage tank.

[0045] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions are also within the scope of protection of the present invention.

Claims

1. A gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tanks, characterized in that, include: The storage tank body includes a storage tank shell and a storage tank cavity, wherein the storage tank cavity is disposed within the storage tank shell; A porous iodine storage mechanism is installed inside the storage tank. The porous iodine storage mechanism is used to store iodine working substance. The porous iodine storage mechanism includes at least three layers of nickel foam with different porosities stacked along the height direction.

2. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 1, characterized in that: The main body of the storage tank also includes: A heater is fixedly installed at the bottom of the inner cavity of the storage tank, and the heater is used to heat the porous iodine storage mechanism. A steam chamber is located at the top of the inner cavity of the storage tank; A steam outlet connected to the steam chamber is located at the top of the tank shell and is used to assist in the discharge of iodine vapor. An insulation layer is installed on the inner surface of the storage tank to provide auxiliary insulation for the porous iodine storage mechanism.

3. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 1, characterized in that: The porous iodine storage mechanism includes: The bottom heating surface layer is in direct contact with the heater at the bottom of the storage tank for rapid heat transfer. The middle iodine storage layer is used to provide storage space for iodine working medium; The top vapor escape layer is used to reduce the flow resistance of iodine vapor.

4. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 3, characterized in that: The bottom heating surface layer, the middle iodine storage body layer, and the top steam escaping layer are arranged sequentially from bottom to top. The bottom heating surface layer and the middle iodine storage body layer, and the middle iodine storage body layer and the top steam escaping layer are formed by high-temperature vacuum sintering to form a metallurgical bonding interface. The connecting pores of the bottom heating surface layer, the middle iodine storage body layer, and the top steam escaping layer are filled with solid iodine working fluid.

5. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 3, characterized in that: The porosity of the bottom heating surface layer is 70%-75%, the pore size of the bottom heating surface layer is 50-80μm, and the thickness of the bottom heating surface layer accounts for 20%-25% of the total thickness of the porous iodine storage structure.

6. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 5, characterized in that: The porosity of the middle iodine storage layer is 82%-88%, the pore size of the middle iodine storage layer is 200-250μm, and the thickness of the middle iodine storage layer accounts for 45%-55% of the total thickness.

7. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 6, characterized in that: The porosity of the top vapor escape layer is 92%-95%, the pore size of the top vapor escape layer is 350-450μm, and the thickness of the top vapor escape layer accounts for 20%-25% of the total thickness.

8. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 3, characterized in that: The nickel foam layer has a three-dimensional interconnected open structure, which includes ribs and pores, and the cross-section of the ribs is triangular or quadrilateral.

9. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 8, characterized in that: The diameter of the pores in the bottom heating layer is 30-50 μm, the diameter of the pores in the middle iodine storage layer is 20-30 μm, and the diameter of the pores in the top vapor escape layer is 10-20 μm.

10. The gradient porosity foam nickel-based porous iodine storage structure for hollow cathode iodine working fluid storage tank as described in claim 3, characterized in that: The porosity of the porous iodine storage mechanism increases monotonically along the height direction, with a gradient change rate of 0.5-1.0% / mm.

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