Multi-layer space shielding material optimization method based on uniform design

Abstract

The method comprises the steps of 1, determining radiation shielding parameters; 2, analyzing and determining a radiation shielding material; 3, determining a space radiation environment; 4, geometric design and material result analysis; 5, multi-layer shielding material optimization based on uniform design; 6, analyzing a simulation result; and 7, comparing, analyzing and verifying. According to the method, research is carried out on the multilayer space shielding material by adopting a particle transport analysis means, analysis is carried out starting from a technological process, fault mode, influence and harmfulness analysis is carried out on the multilayer space shielding material, and key control parameters influencing the radiation shielding performance in the optimization design process of the multilayer space shielding material are found out. And performing experimental design on the key parameters through uniform design, and determining optimal design of the key parameters. And performing simulation analysis on the obtained key factors by means of particle transport software MCNP6 to obtain dose equivalent distribution conditions of the multilayer material under different thickness conditions, and verifying and correcting the simulation model through FLUKA codes. And finally, summarizing the multilayer space radiation shielding material in combination with the optimization model so as to provide a theoretical basis for shielding optimization of the multilayer material of the spacecraft.

Description

(I) Technical field:

[0001] The present invention relates to a method for optimizing multi-layer space shielding materials based on uniform design, which uses particle transport analysis to conduct research on multi-layer space shielding materials. Starting from the shielding material itself, the key shielding parameters such as shielding performance and dose equivalent are analyzed, and the key control parameters affecting the radiation shielding performance in the optimization design process of the multi-layer shielding material are found. The key parameters are experimentally designed through uniform design to determine the optimal design of the key parameters. The obtained key factors are simulated and analyzed with the help of particle transport software MCNP6 to obtain the dose equivalent distribution of multi-layer materials under different thicknesses, and the simulation model is compared and verified by FLUKA code. Finally, the multi-layer space radiation shielding material is summarized in combination with the optimization model, and the visualization results of the multi-layer radiation shielding material are given, thereby providing a theoretical basis for the optimization of multi-layer material shielding of spacecraft. (II) Background technology:

[0002] Space radiation is effective in damaging humans and electronic equipment. Solar particle events (SPE), galactic cosmic radiation (GCR), and the Allan radiation belts are the major space radiation sources. Shielding can reduce the overall exposure of people and electrical equipment. One of the strategies being studied to help reduce the hazards of radiation exposure to humans and electrical equipment is radiation shielding. Radiation hazards in space increase with protons and high atomic number, high Z and E particles (HZE). Elements with the highest charge-to-mass ratio are the best shielding materials against HZE particles. Neutrons, gamma rays, and X-rays produced by particle collisions increase the radiation hazard. Space shielding methods must be studied to improve the reliability of system radiation exposure.

[0003] Over the years, a large number of radiation dose estimation studies have been conducted for manned and unmanned space missions. Initial studies on radiation shielding used radiation transfer codes to determine the amount and type of radiation transmitted through the shield at different depths and material properties. However, there is little research on multi-layer shielding materials, which are materials that shield radiation exposure by using multiple different Z values ​​(atomic numbers). This will bring new optimization technologies to the next generation of deep space vehicles and space stations. At present, research on radiation shielding for spacecraft walls is more limited to aluminum material shielding. Secondly, research on aluminum-polyethylene-aluminum multilayer composites is in the laboratory stage. The optimization design of multi-layer radiation shielding materials is an emerging research hotspot.

[0004] To this end, this method takes multi-layer radiation shielding materials as the research object. Aiming at the problems of insufficient multi-layer design of multi-layer space radiation shielding materials and the lack of innovation of existing optimization methods, a method for optimizing multi-layer space shielding materials based on uniform design is designed. First, by analyzing the space particle environment, the particle energy spectrum under different radiation environments (SPE, GCR, Allen radiation belt) is determined, and 15 shielding materials are selected for shielding performance analysis to determine the shielding efficiency of the materials. Subsequently, a shielding performance analysis model for multi-layer materials based on uniform design is proposed. In this model, the width, number of layers and material distribution of the shielding material are defined as control parameters. By using experimental simulation data, a regression model is established to illustrate the relationship between control parameters and dose equivalent, so that the optimal combination of control parameters can be identified. Radiation shielding tests are carried out by MCNP6 particle transport software to determine the optimal design of multi-layer materials, and the FLUKA code is used for verification and comparative analysis to verify the effectiveness of the proposed multi-layer radiation shielding optimization model. This provides a theoretical basis for the optimization design of multi-layer materials for space radiation shielding. (III) Summary of the invention:

[0005] 1. Purpose: The purpose of the present invention is to provide a method for optimizing multi-layer space shielding materials based on uniform design, which takes into account the analysis of the shielding performance of single-layer materials under different radiation environments and the optimization modeling of multi-layer shielding materials based on uniform design. This method solves the problem that it is difficult to achieve the shielding efficiency of materials in a space particle environment due to the unclear control parameters of the multi-layer shielding material modeling, and verifies the correctness of the constructed optimization model, making the particle transport results more valuable for reference, and provides a theoretical basis for the effective optimization of multi-layer radiation materials in a space environment.

[0006] 2. Technical solution: The present invention is a method for optimizing multi-layer space shielding materials based on uniform design, which comprises the following steps:

[0007] Step 1: Determine radiation shielding parameters;

[0008] Determine the shielding parameters of the shielding material, which are used to describe the shielding performance of the material. The stopping power and fragmentation cross section of the charged particles in the material are selected as parameters to describe the shielding performance of the material.

[0009] Step 2: Analyze and determine radiation shielding materials;

[0010] In order to screen and evaluate the radiation protection performance of shielding materials through simulation calculations, particle transport codes are used. These particle transport programs usually rely on measured nuclear cross-section information. By measuring the Bragg curve of high-energy heavy ions. Examining the energy loss of a particle beam through a material is more informative than examining the path of a single particle. The Bragg depth position of a heavy ion beam in the 1GeV energy range in different materials is calculated using SRIM-2013 simulation. The effect of shielding materials in blocking radiation can be determined. Fifteen shielding materials were studied in particular, and materials containing hydrogen, boron and nitrogen effectively improved the shielding capability.

[0011] Step 3: Determine the space radiation environment;

[0012] The space radiation environment is mainly penetrated by charged particle radiation from SPEs, GCRs and Van Allen belts. We establish three different radiation environment energy spectra. For all studies, the GCR spectra of the 2010 solar minimum in the BO-2014GCR model are used to compare coronal mass ejections (CMEs), pulsed SPEs and GCRs by comparing element abundances. Allen belt proton and electron spectra are simulated using omere. Energy spectra of single or combined particle fields with these spectra are generated according to the predetermined input and output formats as input to Monte Carlo simulations.

[0013] Step 4: Geometric design and material results analysis;

[0014] A shielding simulation model for particle energy spectrum shielding calculations is established using a quasi-spherical shell geometry, and different energy spectra are used to analyze the shielding performance of different shielding materials through MCNP6. The exposure and spherical shielding thickness (depth) curves of various candidate shielding materials are evaluated to balance the preliminary quality requirements and radiation constraints with additional mission parameters.

[0015] Step 5: Multi-layer shielding material optimization based on uniform design;

[0016] In order to improve the shielding effect of multilayer materials, a combination optimization method of multilayer materials was studied. Based on the above research and actual requirements, dose equivalent was selected as the main indicator to measure the shielding ability of materials. Structural parameters include the number of material layers, material sequence and material combination. Surface density is the main control parameter. Considering cost constraints and time requirements, the uniform design method was used to reduce the number of experiments with high parameter levels. By exploring the dependence of four control parameters on the shielding performance dose equivalent, a regression model was established and the optimal value of the parameters was solved.

[0017] Step 6: Simulation results analysis;

[0018] Based on the uniform design, a combination of different material plates is proposed. Of course, care must be taken to ensure that all calculations are performed using exactly the same assumptions: the same radiation transfer scheme, geometry, GCR radiation input boundary conditions, and damage assessment model. This is instructive for optimizing the results by changing the materials and thicknesses of different layers in the design. The results show that aluminum can be used with epoxy resin to minimize the dose equivalent. Through the combination design of multi-layer materials, it was found that Design 3 and Design 6 have the best shielding efficiency.

[0019] Step 7: Comparative analysis and verification.

[0020] In order to evaluate the effectiveness of the optimal parameters, the test samples were validated based on the optimal parameter values. The optimal parameter values ​​for both designs were verified by the FLUKA code. The numerical simulation results of the multilayer radiation shielding material showed a high degree of agreement and the best optimization scheme was determined. Design 6 reflects the relatively low levels of proton and electron flux at higher orbital altitudes. Therefore, the results of the validation tests can clearly show the effectiveness of the proposed model. In addition to radiation shielding, meeting these material requirements can also reduce the weight savings predicted based on the radiation shielding analysis. This shows that there is a quantitatively supported radiation protection design strategy that may be used to launch future spacecraft habitats. (IV) Description of the drawings:

[0021] Figure 1 Implementation steps flow chart

[0022] Figure 2 Comparison of radiation protection performance of different materials based on Bragg curve

[0023] Figure 3 Z=1, 2, 8, 26, annual GCR spectrum of ions with solar modulation parameter of 475MV

[0024] Figure 4 Van Allen band energy spectrum: (a) solar extreme year proton energy spectrum (b) solar extreme year electron energy spectrum

[0025] Figure 5 Spherical geometry design exposed to isotropic radiation

[0026] Figure 6 Comparative Dose Equivalent Analysis of Single-Layer Radiation Shielding Materials (BON2010GCR Model, ICRP-60)

[0027] Figure 7 Comparative Dose Equivalent Analysis of Single-Layer Radiation Shielding Materials (SPE related to Free-Space Carrington Events)

[0028] Figure 8Comparative Dose Equivalent Analysis of Single-Layer Radiation Shielding Materials (2023, 48.6° Inclination, Low Earth Orbit Environment) Fig. 9 Comparative Dose Equivalence Analysis of Eight Multilayer Shielding Material Designs (BON2010GCR Model, ICRP-60)

[0029] Fig.10 Comparison of 3 results based on MCNP6 and FLUKA code design

[0030] Fig.11 Comparison of 6 results based on MCNP6 and FLUKA code design

[0031] Fig.12 Design solution for multi-layer radiation material hard shell of spacecraft hull (V) Specific implementation methods:

[0032] The stress damage simulation method for electronic component through-hole insertion process of the present invention will be further described in detail below in conjunction with the accompanying drawings. The specific steps are as follows:

[0033] Step 1: Determine the radiation shielding parameters for evaluating multi-layer shielding materials;

[0034] First, determine the shielding parameters of the shielding material, which are used to describe the shielding performance of the material.

[0035] The elementary particles of space radiation have shielding materials, and radiation shielding mainly realizes the energy loss of space radiation. The Bethe-Bloch and Bradt-Peters equations can be used to roughly estimate the energy loss:

[0036]

[0037] Where S is the stopping power or linear energy transfer (LET). σ is the fragment cross section, N A Avogadro constant ρ, the density of the shielding material. e, electron charge, m, electron mass, c, speed of light, β = c / v. I, average excitation energy, A p and A T Atomic weight of projectile and shielding material target, Z p and Z T The atomic number of the projectile and the target of the shielding material. 0 The radius of the nucleus, the C(β) shell correction term, L 1 (β) is the Barkas correction term, L 2 (β) is the Bloch correction term, L 3 (β) Mott correction term, semi-empirical term c 1 and c 2 is the energy-dependent geometric cross-section correction term in Equation 2.

[0038] Durante and Cucinotta used Equations 1 and 2 to derive the following approximations for the stopping power and fragmentation cross section of a charged particle per unit target mass of material:

[0039]

[0040]

[0041] Target atomic weight of shielding material A T It is also inversely proportional to the stopping power and fragmentation cross section of the charged particles in the material. It can be deduced from the formula that lightweight materials will have better effects in space radiation protection. Liquid hydrogen is theoretically the best shielding material. Due to the need for cryogenic storage and insulated containers, liquid hydrogen has safety and reliability issues, which means that it still faces many challenges in its practical application in space radiation protection. For space radiation shielding, materials with high shielding property values ​​are preferred. Therefore, it is very necessary to study the radiation resistance of materials.

[0042] Step 2: Analyze and determine radiation shielding materials;

[0043] In order to screen and evaluate the radiation protection performance of shielding materials through simulation calculations, tools such as HZETRN, MCNP6, GEANT4, PHITS and FLUKA are often used. These transport plans usually rely on measured nuclear cross-section information.

[0044] An efficient screening method to determine how well a shielding material blocks radiation is to measure the Bragg curves of energetic heavy ions. Examining the energy loss of a particle beam as it passes through a material is more informative than examining the paths of individual particles, since the interaction between each incident particle and the material it passes through is random. The Bragg depth positions of heavy ion beams over the 1 GeV energy range in different materials were calculated using SRIM-2013 simulations. The number of heavy ions in a single simulation was 10 6 The results are as follows Figure 2 .

[0045] Examining the properties of the initial slope of the Bragg curve is a useful screening method to determine how well a shielding material blocks radiation. If the shielding thickness is x, theoretically no radiation particle should be harmed. The formula for flux, F(x), is:

[0046]

[0047] When the shield thickness x is small, the stopping power S can be considered as a constant if it is assumed that the radiating particle deposits its energy completely through the incident projectile.

[0048] Through the above analysis, we focused on 15 shielding materials (see Table 1). Materials containing hydrogen, boron and nitrogen effectively improve shielding capabilities. Polymer fiber and fiber resin shielding materials are also comparable in reducing space radiation.

[0049] Table 1 Target materials and their physical parameters used in the experiment

[0050]

[0051] Step 3: Determine the space radiation environment;

[0052] The space radiation environment is mainly penetrated by charged particle radiation from SPE, GCR and Van Allen belt. Among them, GCR charged particles are dangerous to humans in spacecraft, while SPE can be dangerous to humans protected only by current space suits. For all studies, the GCR spectrum of the 2010 solar minimum in the BO-2014GCR model was used, using the solar modulation parameters of 475MV, assuming that the GCR occurs at 1AU in free space, as Figure 3 All transport estimates in the energy range from 1 keV / n to 100 GeV / n include particles between Z = 1 and Z = 28. GCR spectra are collected directly for MC simulations without using any additional biasing methods.

[0053] Solar particle events (SPEs) are proton masses accelerated by the Sun's magnetic field. For the photosphere, coronal mass ejections (CMEs), pulsed SPEs, and GCRs, by comparing elemental abundances, proton flux accounts for more than 90% of the total, although their dose equivalent contribution is only 8% of the total. Iron nuclei account for only 0.03% of the GCR flux, three orders of magnitude lower than the proton flux, but their dose equivalent contribution is 20%. Therefore, it is necessary to consider radiation damage from heavy ions when studying the shielding performance characteristics of spacecraft materials.

[0054] Table 2 Element abundances of the photosphere, CME, pulsed SPE and GCR

[0055]

[0056] The Van Allen belts are belts of charged particles trapped in the Earth's magnetic field. They pose a threat to spacecraft orbiting or leaving the Earth. The trapped proton model was calculated using the AP9-MIN and AP9-MAX proton flux models. We simulated the proton and electron spectra using omere, as shown in Figure 4 The outer band has energies up to 10 MeV for electrons and 30 keV to 500 MeV for protons, although protons with energies above 30 MeV will penetrate into the inner band.

[0057] This section studies the energy spectra of the space environment, including GCR, SPE, and Van Allen bands. The energy spectra of single or combined particle fields with these spectra are generated according to the predetermined input and output formats as inputs to Monte Carlo simulations.

[0058] Step 4: Geometric design and material results analysis;

[0059] In order to simplify the problem and reduce the calculation time, a quasi-spherical shell geometry is used. Due to the isotropy of the particle energy spectrum in space, the quasi-spherical shell geometry provides a reasonable approximation for studying space radiation protection problems. The schematic diagram of the spherical shell geometry used for particle energy spectrum shielding calculation is shown in Figure 5 The geometry used in this study was chosen to provide a reasonable link to engineering design applications and ongoing experimental work, while allowing MC simulations to approach convergence for low-energy light ion and heavy target fragmentation at a reasonable computational cost.

[0060] MCNP6 uses different energy spectra to analyze the shielding performance of different shielding materials. It can evaluate the exposure vs. spherical shielding thickness (depth) curves of various candidate shielding materials, thereby balancing preliminary quality requirements and radiation constraints with additional mission parameters. Figure 6 It shows the results of multiple calculations by MCNP6, simulating the dose equivalent behind different shielding materials when the solar minimum GCR was at 1 AU in 2010. Figure 7 Comparative dose equivalence analysis of single-layer radiation shielding materials (SPE related to free-space Carrington events). Figure 8 Comparative dose equivalent analysis of single-layer radiation shielding materials (in the 48.6° inclined low Earth orbit environment recorded in 2023).

[0061] Step 5: Multi-layer shielding material optimization based on uniform design;

[0062] In the material design process of multi-layer radiation shielding, the stopping power and total nuclear fragmentation cross section of the material are the main factors affecting the shielding performance of the material. Therefore, in order to improve the shielding effect of multi-layer materials, it is necessary to study the combination optimization method of multi-layer materials. Based on the above research and actual requirements, dose equivalent is selected as the main indicator to measure the shielding ability of materials. Structural parameters include the number of material layers, material sequence and material combination. Surface density is the main control parameter.

[0063] Table 3 lists the ranges of these main control parameters, which are obtained based on actual requirements, including the size, sequence, surface density and number of layers of shielding materials under operating conditions. Gradients of different parameters are designed.

[0064] Table 3 Range of control parameter values ​​in the experiment

[0065]

[0066] From a practical point of view, considering cost constraints and time requirements, the uniform design method is used to reduce the number of experiments with high parameter levels. In order to balance the experimental cost, fully explore the entire experimental field and consider practical needs, the number of parameter levels is set to 15 accordingly. The best column should be selected from a specific uniform design table with the smallest deviation to represent the best uniform design of the experiment. Therefore, according to the principle of minimum deviation, the first, fourth, fifth and sixth columns are selected to generate the experimental plan, and the specific arrangement is shown in Table 4.

[0067] Table 4 Uniform design table with four factors and fifteen levels

[0068]

[0069] The dependence of the four control parameters on the shielding performance dose equivalent was explored by quadratic polynomial stepwise regression analysis. The commonly used quadratic model is expressed as follows,

[0070]

[0071] Among them, a k b ij is the unknown value that can be calculated from the experimental data based on the least squares method. y represents the value of dose equivalent.

[0072] The dose equivalent can be calculated by numerical methods. However, those parameters shown in Formula 2 are difficult to obtain and calculate. Then, in order to simplify the numerical calculation, Formula 6 is given:

[0073]

[0074] Based on the experimental data, the stepwise regression method was applied to obtain the regression model. Based on formula 6, the regression model can be expressed as follows:

[0075]

[0076] in,

[0077] In order to solve the optimal value of the parameter from the regression model, the partial derivative of y of the control parameter is performed according to Formula 7, and the result is shown in Formula 8.

[0078]

[0079] The optimal values ​​calculated according to Formula 8 are listed in Table 6, and the optimal combination of control parameters is determined.

[0080] Table 6 Optimal parameter values ​​for shielding performance

[0081]

[0082] Step 6: Simulation results analysis;

[0083] Based on the uniform design, a combination of different material plates is proposed. Of course, care must be taken to ensure that all calculations are performed using exactly the same assumptions: the same radiation transfer scheme, geometry, GCR radiation input boundary conditions and damage assessment model. The 15 experiments were performed according to the experimental plan in Table 4. Considering the characteristics of the radiation shielding materials and the weak shielding performance of Ta and W, cutting experiments were performed. The radiation shielding experiments No. 2 and No. 3 were cut. The experimental data are listed in Table 7.

[0084] Table 7 Complex multilayer material designs 1 to 8

[0085]

[0086] According to the experimental plan in Table 7, 8 experiments were conducted. Fig. 9 Displays the results of the dose equivalent analysis for eight shield designs. The final answer for each shield design performance is 100 g / cm 2 Dose equivalent exposure rate behind the shielding material, indicating the location inside the spacecraft. This is instructive for optimizing the results by changing the materials and thickness of different layers in the design. The results show that the dose equivalent of a single layer of Al is reduced to about 322.2mSv / year. The combined design of hydrogen-rich shielding materials gradually reduces the dose equivalent to ~200mSv / year. Epoxy resin is effectively used for neutron shielding. Aluminum can be used with epoxy resin to minimize the dose equivalent. Through the combined design of multi-layer materials, it was found that Design 3 and Design 6 have the best shielding efficiency, and their dose equivalents are reduced to 101.9mSv / year and 161.1mSv / year.

[0087] Step 7: Comparative analysis and verification;

[0088] In order to evaluate the effectiveness of the optimal parameters, the test samples were verified based on the optimal parameter values. Based on the same particle energy spectrum and geometric boundary conditions, numerical analysis was performed using the FLUKA program to verify the optimal parameter values ​​of the two designs.

[0089] Fig.10 and Fig.11 A dose equivalence comparison of results from the MCNP6 and FLUKA deterministic codes for the 2010 Solar Minimum GCR is shown. Numerical simulation results for multilayer radiation shielding materials are in very good agreement.

[0090] In design 6 (Al+C 14 H 14 N 2 O 4+C 21 H 25 CIO 5 +LiH+PBO+BN+Al), the dose equivalent simulated by FLUKA is very close to that of MCNP6, with an error of less than 5%. At 30 g / cm2, the result of FLUKA is slightly lower than that of MCNP6. The average energy values ​​of neutrons and photons are 0.032 MeV / n and 0.0057 MeV / n, respectively.

[0091] Multilayer composite shielding can be lighter than aluminum shielding, thus saving weight while meeting the required total dose level. Design 6 reflects the relatively low levels of proton and electron flux at higher orbital altitudes. Therefore, the results of the validation tests can clearly show the effectiveness of the proposed model.

[0092] Design 6 made of 100g / cm 2 Design solutions for hard shell modules with thick radiation protection are visualized as follows Fig.12 A visual indication of the material distribution across the layers and an estimate of the mass properties are provided in the design of a multi-layer composite. Meeting these material requirements, in addition to radiation shielding, can also reduce the weight savings predicted based on the radiation shielding analysis. This suggests that there is quantitatively supported radiation protection design strategy that could potentially be used to launch future spacecraft habitats.

Claims

1. A method for optimizing multi-layer space shielding materials based on uniform design, characterized in that: Based on the theory of particle physics, the shielding performance and combination optimization of multi-layer shielding materials in multi-layer space environment are studied. By comprehensively analyzing the radiation resistance of various shielding materials, the dose equivalent is minimized, and the relationship between parameters and dose equivalent is established, a multi-layer material shielding performance analysis model based on uniform design is established. In this model, the width, number of layers and material distribution of the shielding material are defined as control parameters. By using experimental simulation data, we developed a regression model to illustrate the relationship between control parameters and dose equivalent, so that the optimal combination of control parameters can be identified and the optimal multi-layer radiation shielding scheme can be determined. The effectiveness of the optimal parameters and regression model was confirmed by analyzing the results using a particle transport code. Finally, the multi-layer space radiation shielding material is summarized in combination with the optimization model, thereby providing a theoretical basis for the optimization of multi-layer material shielding for spacecraft. The specific steps of this method are as follows: Step 1: Determine radiation shielding parameters; Step 2: Analyze and determine radiation shielding materials; Step 3: Determine the space radiation environment; Step 4: Geometric design and material results analysis; Step 5: Multi-layer shielding material optimization based on uniform design; Step 6: Simulation results analysis; Step 7: Comparative analysis and verification.

2. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: The specific process of determining and evaluating the radiation shielding parameters of the multi-layer shielding material described in step 1 is as follows: There are many parameters to describe the shielding performance of radiation shielding materials. This study selected specific shielding parameters as a description of the energy loss of materials in space radiation. The estimated particle energy loss calculation is implemented according to the Bethe-Bloch and Bradt-Peters equations: The key shielding performance description parameters S and σ are selected. S is the stopping power or linear energy transfer (LET) and σ is the fragment cross section. The following approximate values ​​for the stopping power and fragmentation cross section of a charged particle per unit target mass of material are derived from equations 1 and 2: Target atomic weight of shielding material A T It is also inversely proportional to the stopping power and fragmentation cross section of the charged particles in the material. From the formula, it can be deduced that lightweight materials will have a better effect in space radiation protection. By describing the key shielding parameters, the main reference basis for material selection is determined. It is theoretically determined that materials with a high hydrogen content will have better effects in space radiation protection, which provides a basis for subsequent material selection. Therefore, for space radiation shielding, materials with high shielding characteristic values ​​are preferred, and it is very necessary to study the radiation resistance of materials.

3. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: Analyze and determine the radiation shielding material as described in step 2. The specific process is as follows: There are many types of materials suitable for aerospace radiation shielding, including metal materials, composite materials, etc. Based on the descriptive parameters of key shielding materials, the material selection method for aerospace radiation shielding is determined. That is, measuring the Bragg curve of high-energy heavy ions and checking the energy loss of particle beams passing through materials is more informative than checking the path of individual particles. Therefore, SRIM-2013 is used to simulate and calculate the Bragg depth position of heavy ion beams in the 1GeV energy range in different materials, and the results are shown in Figure 2. It is found that materials containing hydrogen, boron and nitrogen effectively improve the shielding capability. Polymer fiber and fiber resin shielding materials are also comparable in reducing space radiation, which determines the results of subsequent material selection. The 15 shielding materials for this study were determined through specific method analysis, as shown in Table 1. The selected materials are the basis for the subsequent multi-layer material shielding optimization design.

4. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: Determine the space radiation environment as described in step 3. The specific process is as follows: First, determine the particle energy spectrum of the space environment, the charged particle environment of SPE, GCR and Van Allen belt. Analyze the impact of different radiation environments on space shielding. GCR charged particles are dangerous to humans in spacecraft, while SPE may be dangerous to humans who are only protected by current space suits. The cumulative effect of Van Allen belt on devices is relatively obvious. Secondly, we determine the particle energy spectrum. Based on the current research foundation, we select the GCR spectrum of the 2010 solar minimum in the BO-2014GCR model, the specific solar particle event (SPE), and the proton and electron model energy spectra in the 2023 AP9, and analyze them respectively. Finally, the energy spectrum of the space environment, including GCR, SPE and Van Allen bands, is generated according to the predetermined input and output formats as input to the Monte Carlo simulation to determine the 2 of the selected material.

5. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: The geometric design and material result analysis described in step 4. The specific process is as follows: To simplify the problem and reduce computational time, a quasi-spherical shell geometry is used. Due to the isotropy of the particle energy spectrum in space, the quasi-spherical shell geometry provides a reasonable approximation for studying space radiation protection problems. Design of spherical shell-like geometry for particle energy spectrum shielding calculations. The spherical shell-like geometry is designed to provide a reasonable connection between engineering design applications and ongoing experimental work, while allowing MC simulations to approach convergence for low-energy light ions and heavy target fragments at a reasonable computational cost. The shielding performance of different shielding materials is analyzed by using different energy spectra through MCNP6. The exposure and spherical shielding thickness (depth) curves of various candidate shielding materials are evaluated to balance the preliminary quality requirements and radiation constraints with additional mission parameters. The comparative dose equivalent analysis of GCR, SPE and Van Allen belt single-layer radiation shielding materials is simulated respectively. This part of the results provides a reference for the optimization of multi-layer radiation shielding materials.

6. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: The specific process of the optimization of multi-layer shielding materials based on uniform design described in step 5 is as follows: Based on the above research and actual requirements, dose equivalent is selected as the main indicator to measure the shielding ability of materials. Structural parameters include the number of material layers, material sequence and material combination. Surface density is the main control parameter. The range of control parameters is listed in Table 3, and different gradients are designed. On this basis, the uniform design method was used to reduce the number of experiments with high parameter levels, and a four-factor fifteen-level test table was designed. According to the minimum deviation principle, the first, fourth, fifth and sixth columns are selected to generate the experimental plan. The specific arrangement is shown in Table 4. Then, a regression model of key control parameters of multi-layer shielding materials was established. The regression model was obtained by applying the stepwise regression method. Based on formula 6, the regression model can be expressed as follows: in, To solve the optimal value of the parameters in the regression model, the partial derivative of y of the control parameter is taken according to Formula 7, and the result is shown in Formula 8. The best values ​​calculated according to formula 8 are listed in Table 6, and the best combination of control parameters is determined. That is, under the condition of a specific shielding thickness, the best combination values ​​of the number of material layers, the material sequence and the material combination are determined. Table 6 Optimal parameter values ​​for shielding performance 7. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: The specific process of the simulation result analysis described in step 6 is as follows: On the basis of uniform design, a combination scheme of different material plates is proposed. According to the number of tests in Table 4, the radiation shielding experiments No. 2 and No. 3 are tailored considering the characteristics of radiation shielding materials and the weak shielding performance of Ta and W. The experimental data are listed in Table 7. Figure 9 shows the dose equivalent analysis results of eight shielding designs. The dose equivalent of a single layer of Al was reduced to about 322.2 mSv / year. The combined design of hydrogen-rich shielding materials gradually reduced the dose equivalent to ~200 mSv / year. Epoxy resin was effectively used for neutron shielding. Design 3 and Design 6 were found to have the best shielding efficiency, and their dose equivalents were reduced to 101.9 mSv / year and 161.1 mSv / year.

8. The method for optimizing multi-layer space shielding materials based on uniform design according to claim 1, characterized in that: The specific process of the comparative analysis and verification described in step 7 is as follows: In order to evaluate the effectiveness of the optimal parameters, the test samples were verified based on the optimal parameter values. Based on the same particle energy spectrum and geometric boundary conditions, numerical analysis was performed using the FLUKA program to verify the optimal parameter values ​​of the two designs. The numerical simulation results of the multilayer radiation shielding material are very consistent. 100g / cm2 made by optimal design 6 2 The design solution for the hard shell module with thick radiation protection layer is visualized in Figure 12. In the design of multi-layer composite materials, a visual indication of the material distribution of the layers and an estimate of the mass properties are provided.

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