A method for analyzing total ionizing dose of a satellite based on oblique incidence

Abstract

The application provides a satellite ionization total dose analytical analysis method based on oblique incidence, considers the shielding thickness thickening and total dose low efficiency effect caused by oblique incidence, and significantly reduces ionization total dose data. Specifically, the method comprises the following steps: step one, analyzing the relationship between the satellite ionization total dose and the equivalent shielding thickness under the vertical incidence condition according to the satellite orbit parameter; step two, obtaining a fitting formula and fitting coefficients of the relationship between the satellite ionization total dose and the equivalent shielding aluminum thickness under the vertical incidence condition according to the relationship between the satellite ionization total dose and the equivalent aluminum shielding thickness under the vertical incidence condition; step three, analyzing the calculation formula of the satellite ionization total dose and the equivalent aluminum shielding thickness under the isotropic incidence condition considering the oblique incidence effect by using the fitting formula and the fitting coefficients; and step four, analyzing the ionization total dose of a device in a single machine in the satellite according to the calculation formula.

Description

Technical Field

[0001] This invention relates to a method for analyzing the total ionizing dose of a satellite based on oblique incidence, belonging to the field of space radiation technology. Background Technology

[0002] Satellites in orbit encounter captured electrons, captured protons, and protons from solar flares, resulting in a total ionizing dose effect that can cause device parameters to exceed tolerances and performance degradation. During satellite development, protective designs against this total ionizing dose are necessary to ensure that the effect does not impact the satellite's on-orbit performance.

[0003] Total ionizing dose (TID) analysis is fundamental to protective design, and currently, two main methods are used: one-dimensional (1D) and three-dimensional (3D) analysis. The one-dimensional method first calculates the relationship between the TID and the equivalent aluminum shielding thickness under perpendicular incidence conditions based on the space radiation environment. Then, it analyzes the total shielding thickness in a one-dimensional direction perpendicular to the device, considering only simplified shielding elements such as satellite sub-panels, individual unit casings, and circuit boards. The corresponding TID is then retrieved from the TID-shielding thickness relationship data. The three-dimensional method requires constructing 3D shielding models of individual units and the entire satellite. It analyzes the shielding thickness and corresponding total dose in each direction within the unit or the entire satellite, and finally sums the total doses in each direction to obtain the final TID.

[0004] One-dimensional analysis methods only consider the main shielding perpendicular to the device direction. While simple, they do not account for oblique incidence. In oblique incidence, the particle's path length increases, the shielding thickness increases, and the total dose decreases, leading to an overestimation of the total dose obtained by one-dimensional analysis. However, one-dimensional analysis only considers the bulkhead shielding related to the entire satellite and does not consider other individual unit shielding. Therefore, individual unit shielding is not coupled with the overall satellite configuration and layout, and individual unit design does not need to be iterated with the overall satellite design, simplifying the design process.

[0005] The 3D analysis method not only considers shielding from all directions but also incorporates the effects of increased thickness and reduced dose caused by oblique incidence. Its total dose result is lower and closer to reality, which is beneficial for reducing the shielding requirements of individual units and devices. However, the 3D analysis method requires constructing a complete 3D model of the satellite, which is a very large workload, often taking several weeks. Furthermore, because it considers the overall satellite structure and layout, there is a coupling relationship between individual units and the entire satellite. If the overall satellite structure and layout change, the shielding conditions of individual units will change, and the design of individual units carries the risk of repeated iterations. Summary of the Invention

[0006] This invention proposes a satellite ionization total dose analysis method based on oblique incidence, which takes into account the effects of increased shielding thickness and reduced total dose caused by oblique incidence, and significantly reduces the ionization total dose data.

[0007] The present invention is achieved through the following technical solution.

[0008] A method for analytical analysis of total ionizing dose from a satellite based on oblique incidence includes the following steps:

[0009] Step 1: Analyze the relationship between the total ionizing dose of the satellite and the equivalent aluminum shielding thickness under vertical incidence conditions based on the satellite's orbital parameters;

[0010] Step 2: Obtain the fitting formula and fitting coefficients for the relationship between the total satellite ionization dose and the equivalent shielding thickness under vertical incidence conditions;

[0011] Step 3: Analyze the calculation formulas for the total satellite ionization dose and equivalent aluminum shielding thickness under isotropic incidence conditions considering the oblique incidence effect using the aforementioned fitting formulas and fitting coefficients.

[0012] Step 4: Analyze the total ionization dose of the components in the satellite's internal unit according to the calculation formula.

[0013] The beneficial effects of this invention are:

[0014] 1. This invention takes into account the shielding thickness enhancement effect caused by oblique incidence, and through the analysis of fitting coefficients, it can effectively reduce the analysis results of total ionizing dose, thereby effectively reducing the difficulty of device selection, which is conducive to reducing satellite weight, reducing development costs, and accelerating development progress.

[0015] 2. This invention divides satellite orbits into geostationary orbit, intermediate Earth orbit, and low Earth orbit, proposes different fitting formulas, and analyzes the total dose based on different fitting coefficients, which is approximately 16% to 58% of the total dose considering only one-dimensional vertical thickness.

[0016] 3. This invention only considers the main shielding materials of the single satellite module, single satellite shell, and circuit board, without considering the overall satellite structure and layout. This can decouple the single unit from the whole satellite, eliminate the need for iterative design between the single unit and the whole satellite, and avoid repeated development. Attached Figure Description

[0017] Figure 1 This is a flowchart of the satellite ionization total dose analysis method based on oblique incidence, as described in this invention.

[0018] Figure 2 The results of the total ionization dose analysis and fitting values ​​in the specific implementation method are shown below;

[0019] Figure 3 The results are the total ionization dose analysis and fitting values ​​in the specific implementation method.

[0020] Figure 4The results show the total ionization dose analysis and fitting values ​​in the specific implementation method.

[0021] Figure 5 A schematic diagram to account for thickness variations due to oblique incidence. Detailed Implementation

[0022] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the drawings are merely exemplary and are intended to illustrate the principles and spirit of the present invention, and are not intended to limit the scope of the present invention.

[0023] like Figure 1 As shown, the satellite ionization total dose analysis method based on oblique incidence of the present invention specifically includes the following steps:

[0024] Step 1: Analyze the relationship between the total ionizing dose of the satellite and the equivalent aluminum shielding thickness under vertical incidence conditions based on the satellite's orbital parameters;

[0025] The following table shows the relationship between the total ionization dose and the thickness of the shielding aluminum for the following three orbits: geostationary orbit (35,786 km altitude), medium Earth orbit (20,000 km to 25,000 km altitude), and low Earth orbit (below 1,500 km altitude).

[0026] Table 1. Relationship between total ionizing dose and shielding aluminum thickness for different orbits.

[0027]

[0028]

[0029] Step 2: Obtain the fitting formula and fitting coefficients for the relationship between the total satellite ionization dose and the equivalent shielding thickness under vertical incidence conditions;

[0030] In practice, different orbits experience different space radiation environments, resulting in variations in the relationship between the total ionizing dose and the shielding thickness. Therefore, this embodiment proposes different fitting formulas for different orbits, as follows:

[0031] For geostationary orbit and low Earth orbit, the fit is performed according to formula (1):

[0032]

[0033] Where f is the total dose in rad (Si); t is the equivalent shielding aluminum thickness in mm; and A1, B1, A2, B2, A3, and B3 are fitting coefficients.

[0034] For the geostationary orbit, the fit is performed according to formula (2):

[0035]

[0036] Where f is the total dose in rad (Si); t is the equivalent aluminum shielding thickness in mm; and A4, B4, A5, B5, A6, and B6 are fitting coefficients.

[0037] It can be seen that the first and third terms of formulas (1) and (2) are the same, but the second term is different: in this embodiment, the exponent of the second term t in formula (1) is 0.5, while the exponent of the second term t in formula (2) is 1.

[0038] According to formulas (1) and (2), the relationship between the total ionization dose and the shielding aluminum thickness in geostationary orbit, intermediate Earth orbit, and low Earth orbit in Table 1 is fitted to obtain the corresponding fitting coefficients, and the results are as follows:

[0039] The geostationary orbit fitting results are shown in Figure 2 The fitting coefficients are as follows (3):

[0040]

[0041] The fitting results for the medium Earth orbit are shown in Figure 3 The fitting coefficients are as follows (4):

[0042]

[0043] The fitting results for the low Earth orbit are shown in Figure 4 The fitting coefficients are as follows (5):

[0044]

[0045] Step 3: Analyze the calculation formulas for the total satellite ionization dose and equivalent aluminum shielding thickness under isotropic incidence conditions considering the oblique incidence effect using the aforementioned fitting formulas and fitting coefficients.

[0046] The principle behind this step is that spatial particles are isotropically incident, with both perpendicular and oblique incidence scenarios. Oblique incidence penetrates a thicker shield than perpendicular incidence, therefore the total dose considering oblique incidence is lower than the total dose considering only perpendicular incidence. This embodiment analyzes the relationship between the total dose of isotropic incidence considering the oblique incidence effect and the shield thickness, such as... Figure 5 As shown, specifically:

[0047] First, the total dose corresponding to different incident angles under isotropic incidence conditions is integrated. Under the incident angle θ, the vertical thickness t becomes the oblique thickness t / cos(θ). Substituting the oblique thickness into formulas (1) and (2), the total dose under oblique incidence conditions is obtained. The total dose under oblique incidence is then integrated with respect to θ in the range of (0, π / 2) to obtain the relationship between the total dose and the shielding thickness under isotropic incidence conditions considering the oblique incidence effect. The integration adopts the following formula (6):

[0048]

[0049] Then, the fitting functions for different orbits (i.e., formulas (1) and (2)) are substituted into formula (6) respectively to obtain the formulas for the total dose of geostationary orbit, low Earth orbit, and medium Earth orbit; as shown in the following formulas:

[0050] The formula relating the total dose to shielding thickness for geostationary and low Earth orbits is as follows:

[0051]

[0052] The formula relating the total dose in mid-Earth orbit to the shielding thickness is:

[0053]

[0054] Where the total dose is f(t) when the shielding thickness is t, and the total dose is f(t / cos(θ)) when the oblique incidence angle is θ, and Ei(z) is an exponential integral function, expressed as follows:

[0055]

[0056] It can be seen that the above formulas (7) and (8) yield the formulas for calculating the actual dose D inside when the vertical thickness is t, under the condition of isotropic incidence considering the oblique incidence effect.

[0057] Finally, by substituting the fitting coefficients of formulas (3) and (5) into formula (7) and the fitting coefficients of formula (4) into formula (8), we can obtain the results of the relationship between the total dose and shielding thickness in geostationary orbit, low Earth orbit, and medium Earth orbit.

[0058] The formula for calculating the relationship between the total dose in geostationary orbit and the shielding thickness is as follows:

[0059]

[0060] The formula for calculating the relationship between the total dose in mid-Earth orbit and the shielding thickness is as follows:

[0061]

[0062] The formula for calculating the relationship between the total dose in low Earth orbit and the shielding thickness is as follows:

[0063]

[0064] Step 4: Analyze the total ionizing dose of components within the satellite's internal unit according to the aforementioned calculation formula; specifically:

[0065] For a specific component within the satellite's internal unit, the thicknesses of the satellite's main shielding material, including the outer shell and circuit board, are obtained. The equivalent aluminum thicknesses of each main shielding material are then added together to obtain the total equivalent aluminum thickness t0. Based on the satellite's orbital altitude, a suitable orbit is selected from formulas (10), (11), and (12). The total equivalent aluminum thickness t0 is substituted into the formula to calculate the corresponding total dose, thus obtaining the dose of the component.

[0066] Table 2 presents the total dose calculation results for different track heights and equivalent aluminum shield thicknesses. It can be seen that considering the oblique incidence effect, the total dose is 16% to 58% of the total dose considering only the vertical incidence method. That is, without adding any additional shielding, considering the oblique incidence effect can reduce the total dose by about half.

[0067] Table 2. Total ionizing dose results considering oblique incidence and their ratio to results considering only perpendicular incidence.

[0068]

[0069]

[0070]

[0071] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for analyzing total ionizing dose from a satellite based on oblique incidence, characterized in that, Includes the following steps: Step 1: Analyze the relationship between the total ionizing dose of the satellite and the equivalent aluminum shielding thickness under vertical incidence conditions based on the satellite's orbital parameters; Step 2: Obtain the fitting formula and fitting coefficients for the relationship between the total satellite ionization dose and the equivalent aluminum shield thickness under vertical incidence conditions; Step 3: Analyze the calculation formulas for the total satellite ionization dose and equivalent aluminum shielding thickness under isotropic incidence conditions considering oblique incidence effects using the aforementioned fitting formulas and fitting coefficients. Step 4: Analyze the total ionizing dose of the components in the satellite's internal unit according to the calculation formula; The satellite's operating orbits include geostationary orbit (35,786 km altitude), medium Earth orbit (20,000 km to 25,000 km altitude), and low Earth orbit (below 1,500 km altitude). Different fitting formulas are proposed for different orbits, as follows: For geostationary orbit and low Earth orbit, the fit is performed according to formula (1): （1） Where f is the total dose in rad (Si); t is the equivalent aluminum shielding thickness in mm; A1, B1, A2, B2, A3, and B3 are fitting coefficients; For the geostationary orbit, the fit is performed according to formula (2): （2） Where f is the total dose in rad (Si); t is the equivalent aluminum shielding thickness in mm; A4, B4, A5, B5, A6, and B6 are fitting coefficients; The formula for calculating the total ionizing dose of a satellite and the equivalent aluminum shielding thickness under isotropic incidence conditions, considering the oblique incidence effect, is analyzed using the aforementioned fitting formula and fitting coefficients. Specifically: First, the total dose corresponding to different incident angles is integrated to obtain the dose considering oblique incidence. The integration is performed using the following formula (6): （6） Then, the fitting functions of different orbits are substituted into formula (6) respectively to obtain the total dose integral results of geostationary orbit, low Earth orbit, and medium Earth orbit; The specific formula for calculating the relationship between the total dose and shielding thickness for geostationary orbit, low Earth orbit, and medium Earth orbit is as follows: The formula relating the total dose to shielding thickness for geostationary and low Earth orbits is as follows: （7） The formula relating the total dose in mid-Earth orbit to the shielding thickness is: （8） in, It is an exponential integral function, expressed as: （9）。 2. The method for analyzing total satellite ionization dose based on oblique incidence as described in claim 1, characterized in that, The total ionizing dose of components within a single unit of the satellite is analyzed based on the aforementioned calculation formula; specifically: For a specific component inside the satellite, the thicknesses of the main shielding materials, including the satellite module, the outer shell, and the circuit boards, are obtained. The equivalent aluminum shielding thicknesses of each main shielding material are then added together to obtain the total equivalent aluminum shielding thickness. and the total equivalent aluminum shielding thickness Substitute these values ​​into formula (7) or formula (8) to calculate the total dose for different orbits.

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