A Composite Protection Method for Total Ionizing Dose in Medium Earth Orbit Space Irradiation

Abstract

The present invention relates to a composite shielding method for total radiation dose in medium-orbit space, comprising the following steps: S1. calculating the total radiation dose at any position of a spacecraft in medium-orbit space; S2. calculating the energy loss per unit distance of protons in the material; S3. selecting a shielding material based on the energy loss per unit distance of protons in the material; and S4. coating aluminum with the selected shielding material to construct a composite shielding material for spacecraft radiation protection in medium-orbit space. The method provides reliable protection for spacecraft against the total radiation dose in medium-orbit space at a minimal cost in mass and volume.

Description

Technical field

[0001] The present invention relates to the field of aerospace technology, and in particular to a composite protection method for total space radiation dose in a medium orbit. [Background Technology]

[0002] Medium Earth Orbits (MEOs), with altitudes between 2,000 and 10,000 km, offer high revisit times and long-term residency, enabling remote sensing satellites to provide excellent sustained imaging capabilities. However, due to their location within Earth's proton capture zone, the high-energy proton flux encountered by these satellites is significantly higher than that of other commonly used low-Earth satellite orbits. Improving satellite protection against radiation exposure in the MEO space environment is a key consideration in satellite design and development.

[0003] The medium-orbit orbit is located in the inner belt of the Earth's radiation belt, and the high-energy protons have strong penetrating power, resulting in a significant reduction in the effect of alleviating the cumulative total ionizing dose by increasing the thickness of the shielding metal. This is significantly different from the GEO orbit (Geosynchronous orbit (GEO) refers to a circular orbit in which an artificial satellite orbits the Earth at about 36,000 km above the Earth's equator.) The total ionizing dose of satellites is mainly caused by electrons.

[0004] In radiation environments dominated by electrons, traditional aluminum shielding can significantly reduce the total ionizing dose. However, medium-range orbits (MEOs) lie within Earth's inner radiation belt, where high-energy protons can penetrate the satellite's skin and casing, posing a threat to components. As the aluminum thickness increases, the electron dose decreases rapidly, leaving the total dose dominated by protons. Increasing the shielding thickness in this situation does not significantly reduce the ionizing dose, and excessive shielding thickness places an additional burden on the spacecraft. For MEOs, total dose protection strategies for both protons and electrons must be considered simultaneously to ensure reliable satellite protection with minimal engineering effort.

[0005] The absorbed dose is defined as the energy absorbed per unit mass of material receiving ionizing radiation. The international unit is defined as Gray (Gy). 1 Gray means that 1 kilogram (Kg) of material absorbs 1 joule (J) of energy. 1Gy = 1J / Kg, 1Gy = 100radsi, 10Gy = 1kradsi.

[0006] The present invention makes technical improvements to the composite protection method for the total dose of space radiation in the medium orbit. [Summary of the invention]

[0007] The purpose of the present invention is to provide a method for achieving reliable protection of spacecraft against total space radiation dose in medium orbit at a lower cost in mass and volume.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a composite protection method for the total dose of space radiation in the medium orbit, comprising the following steps:

[0009] S1. Calculate the total radiation dose at any position of the spacecraft in the medium orbit space;

[0010] S2. Calculate the energy loss per unit distance of protons in the material;

[0011] S3. Select shielding materials based on the energy loss per unit distance of protons in the material;

[0012] S4. Cover the selected shielding material on aluminum to construct a spacecraft composite shielding material for medium-orbit space radiation protection.

[0013] Preferably, the composite protection method for total space radiation dose in medium orbit further includes the following steps:

[0014] S5. Determine the mass ratio of different components in the composite shielding material based on the curve of the total ionization dose after the total ionization dose of the medium orbit space radiation passes through the composite shielding material and the change of the aluminum mass percentage.

[0015] Preferably, the composite protection method for total radiation dose of medium orbit space includes step S1: using ray tracing to calculate the distribution of shielding thickness in solid angle with any position as the center, the equivalent thickness of sector i is d, and the solid angle occupied is Ω i , the irradiation dose D is obtained by interpolation from the irradiation dose depth curve i (d), then the radiation dose contribution of sector i is The total radiation dose received at any position is

[0016] Preferably, in the composite protection method for total dose of medium orbit space radiation, step S2: the energy loss S per unit distance of protons in the material is expressed as in e and v are the charge and velocity of the incident proton, z is the atomic number of the incident proton, N and Z are the atomic density and atomic number of the absorbing material, m0 is the electron rest mass, and I is the ionization potential of the material atoms.

[0017] Preferably, in the composite protection method for total radiation dose of medium orbit space, step S3: the energy loss S of protons per unit distance in the material is proportional to N and Z. When the material density ρ is determined, N = ρ / A×N A , where A is the atomic mass of the material, N A is Avogadro's constant.

[0018] Preferably, in the composite protection method for the total dose of medium-orbit space radiation, in step S3, the law of proton energy loss per unit distance in the material is as follows: the material's ability to block protons is proportional to the material's charge-to-mass ratio. Under the same mass thickness, the hydrogen element with the highest charge-to-mass ratio has the best proton shielding ability.

[0019] Preferably, in the composite protection method for total dose of medium orbit space radiation, the shielding material selected in step S3 is a hydrogen-rich polymer material.

[0020] Preferably, the composite protection method for total dose of medium orbit space radiation includes step S4: covering polyethylene on aluminum to construct a spacecraft composite shielding material with high mechanical properties, good temperature performance and low secondary rays.

[0021] Preferably, in the composite protection method for total dose of medium orbit space radiation, step S5: the optimal mass ratio of the composite shielding material is aluminum and polyethylene in a mass ratio of 1:3.

[0022] The composite protection method for the total radiation dose of medium-orbit spacecraft according to the present invention has the following beneficial effects: the radiation protection of medium-orbit spacecraft taking into account the total radiation doses of protons and electrons at the same time is constructed, a composite shielding material for medium-orbit spacecraft with high mechanical properties, good temperature performance and low secondary rays is constructed, and reliable protection of the spacecraft is achieved with relatively low engineering cost; further, in combination with existing theoretical analysis and engineering practice, a composite protection scheme for the total radiation dose of medium-orbit spacecraft based on polymer materials such as Al (aluminum) and PE (polyethylene) is proposed, and the protection effect is optimized through a suitable combination of material ratios, that is, a better protection effect is achieved at a relatively low cost in mass and volume.

Brief Description of the Drawings

[0023] Figure 1 This is a schematic diagram of a PE and aluminum composite protection scheme that uses a composite protection method for the total dose of space radiation in medium orbit.

[0024] Figure 2 It is a step-by-step diagram of a composite protection method for total space radiation dose in medium orbit.

[0025] Figure 3 It is a composite protection method for the total radiation dose of medium orbit space. The curve of the total radiation dose in the PE and aluminum composite protection scheme changes with the Al mass percentage. [Specific implementation method]

[0026] The present invention will be further described below in conjunction with embodiments and with reference to the accompanying drawings.

[0027] Example

[0028] This embodiment implements a composite protection method for the total radiation dose of medium orbit space.

[0029] For medium-orbit orbits, it's necessary to consider both proton and electron total dose protection solutions to ensure reliable satellite protection at minimal engineering cost. Combining existing theoretical analysis and engineering practice, this embodiment proposes a composite protection method for total space radiation dose in medium-orbit orbits based on polymer materials such as Al (aluminum) and PE (polyethylene). By combining appropriate material ratios, this solution optimizes the protection effect, achieving superior protection at minimal mass and volume cost.

[0030] In medium-orbit, the equivalent Al shielding thickness required to reduce the total ionizing dose to approximately 20 kradsi for a five-year satellite lifespan is approximately 2.09 g / cm² (7.7 mm). The addition of hydrogen-rich polymers can enhance protection against proton doses from space radiation, thereby improving overall protection. Among several hydrogen-rich polymers, polyethylene (PE) is a preferred choice due to its high hydrogen content, ease of processing, and excellent adaptability, making it widely used in aerospace engineering. Figure 1 This is a schematic diagram of a composite protection scheme using PE and aluminum for the total dose of space radiation in the medium orbit. Figure 1 As shown, this embodiment proposes a composite protection method for the total dose of space radiation exposure to the medium orbit orbit, and proposes a composite space radiation protection solution for the medium orbit orbit based on Al and PE materials.

[0031] Figure 2 This is a step-by-step diagram of a composite protection method for the total dose of space radiation in the medium orbit. Figure 2 As shown, the composite protection method for total space radiation dose in medium orbit in this embodiment includes the following steps.

[0032] Calculate the total radiation dose at a certain position of the spacecraft, and use ray tracing to calculate the distribution of shielding thickness in the solid angle with the position as the center. Assume that the equivalent thickness of sector i is d and the solid angle occupied is Ω i , the irradiation dose D can be obtained by interpolation in the irradiation dose depth curve i (d), then the radiation dose contribution of this sector is The total radiation dose received at this location is D tot :

[0033]

[0034] The stopping power of a material for charged particles can be expressed by the energy loss per unit distance of the charged particles in the material:

[0035] S=-dE / dx (2)

[0036] For protons, equation (1) can be expressed by Bethe's equation (electron ionization energy loss rate equation):

[0037]

[0038] in,

[0039]

[0040] Where e and v are the charge and velocity of the incident particle, z is the atomic number of the incident particle, N and Z are the atomic density and atomic number of the absorbing material, m0 is the electron rest mass, and I is the ionization potential of the material atoms. From (2) and (3), we can see that S is proportional to N and Z. When the material density ρ is determined:

[0041] N=ρ / A×N A (5)

[0042] Where A is the atomic mass of the material, N A =Avogadro's constant. Therefore, a material's ability to block protons is roughly proportional to its charge-to-mass ratio. For the same mass and thickness, hydrogen, the element with the highest charge-to-mass ratio, offers the best proton shielding.

[0043] The effectiveness of proton protection, specifically proton shielding, is directly related to the shielding material's charge-to-mass ratio. A higher charge-to-mass ratio improves shielding performance, making hydrogen-rich polymers more advantageous. Polyethylene (PE) and other polymer materials were selected as the benchmark materials for the multifunctional composite shielding material used in this embodiment's composite protection method for total space radiation dose in medium-orbit orbit. These composite shielding materials exhibit high mechanical properties, excellent temperature resistance, and low secondary radiation emissions.

[0044] Passive radiation shielding methods, i.e., using shielding materials for radiation protection, would create a significant amount of unnecessary extra mass if a large-area skin were used throughout. Furthermore, because polymer materials generally have a lower density than aluminum, for the same mass and thickness, the material thickness is often greater, which can also place a burden on the spacecraft's volume constraints. Therefore, the composite shielding method for total radiation dose in medium-orbit space, developed in this embodiment, employs a more efficient method of combined shielding using aluminum and PE polymer materials.

[0045] Metal materials like AL can effectively protect against space electrons, while polymers like PE can effectively protect against space proton radiation. Combining these two materials, through appropriate proportions, can effectively protect against medium-orbit space radiation exposure, where both electron and proton doses are high. This embodiment presents a composite protection method for total space radiation dose in medium-orbit space. While effectively protecting against the total space radiation dose, it also reduces the overall protection mass and volume, lowering overall aerospace development costs.

[0046] This embodiment provides a composite protection method for total space radiation dose in medium orbit, which can reduce the total ionization dose and lighten the satellite mass by replacing Al with a portion of PE (polyethylene). Figure 3 This is a composite protection method for the total radiation dose of medium orbit space. The total radiation dose in the PE and aluminum composite protection scheme varies with the Al mass percentage. Figure 3 As shown in the figure, in the composite protection method for the total dose of medium orbit space radiation in this embodiment, in the PE and aluminum composite protection scheme, when the mass thickness is fixed at 2.09g / cm2 and the double-layer shielding of Al and PE is used, the total ionization dose changes with the Al mass percentage.

[0047] To minimize the total ionization dose, there is an optimal mass ratio of Al and PE materials. Analysis shows that as the Al content increases, the total electron dose decreases, while the total proton dose increases. The total ionization dose initially decreases and then increases. When the Al content reaches 25% by mass, the total ionization dose reaches its minimum, achieving the best overall protection against total space radiation dose.

[0048] Therefore, by using a mass ratio of Al and PE of 1:3 (i.e., aluminum accounts for 25%), a space radiation composite protection scheme of metal and polymer materials is formed, which can obtain the best protection effect against the total dose of space radiation in the medium orbit.

[0049] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the principles of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A composite protection method for total radiation dose in medium orbit space, characterized in that The following steps are involved: S1. Calculate the total radiation dose at any position of the spacecraft in the medium orbit space; S2. Calculate the energy loss per unit distance of protons in the material; S3. Select shielding materials based on the energy loss per unit distance of protons in the material; S4. Covering the selected shielding material on aluminum to construct a spacecraft composite shielding material for medium orbit space radiation protection; Hydrogen-rich polyethylene is selected as the shielding material; polyethylene is covered on aluminum to construct a spacecraft composite shielding material; among them, Al and PE are mixed in a mass ratio of 1:3 to form a space radiation composite protection solution of metal and polymer materials.

2. The composite protection method for total radiation dose of medium orbit space according to claim 1, characterized in that The following steps are also included: S5. Determine the mass ratio of different components in the composite shielding material based on the curve of the total ionization dose after the total ionization dose of the medium orbit space radiation passes through the composite shielding material and the change of the aluminum mass percentage.

3. The composite protection method for total radiation dose of medium orbit space according to claim 2, characterized in that Step S1: Calculate the distribution of shielding thickness in solid angle by ray tracing with any position as the center. The equivalent thickness of sector i is d and the solid angle occupied is Ω. i , the irradiation dose D is obtained by interpolation from the irradiation dose depth curve i (d), then the radiation dose contribution of sector i is The total radiation dose received at any position is 4. The composite protection method for total radiation dose in medium orbit space according to claim 3 is characterized in that Step S2: The energy loss S per unit distance of the proton in the material is expressed as in e and v are the charge and velocity of the incident proton, z is the atomic number of the incident proton, N and Z are the atomic density and atomic number of the absorbing material, m0 is the electron rest mass, and I is the ionization potential of the material atoms.

5. The composite protection method for total radiation dose in medium orbit space according to claim 4, characterized in that Step S3: The energy loss S per unit distance of the proton in the material is proportional to N and Z. When the material density ρ is determined, N = ρ / A×N A , where A is the atomic mass of the material, N A is Avogadro's constant.

6. The composite protection method for total radiation dose in medium orbit space according to claim 5, characterized in that Step S3: The law of proton energy loss per unit distance in the material: the material's ability to block protons is proportional to the material's charge-to-mass ratio. Under the same mass thickness, the hydrogen element with the highest charge-to-mass ratio has the best proton shielding ability.

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