Method for selecting solar cosmic ray model

Abstract

The present invention proposes a method and system for selecting a solar cosmic ray model, including a selection requirement instruction for a solar cosmic ray model. Based on the purpose of analysis, research or experiment, the data requirements of the corresponding solar cosmic ray model are obtained from the selection requirement instruction. Since the single particle effect brought by solar cosmic rays is mainly related to the energy and flux of transient particles, while the total ionization dose effect and the total displacement dose effect are closely related to the energy and cumulative flux (infusion) of cumulative particles, of course, astronauts will also be threatened by the instantaneous flux and the cumulative flux. Therefore, it is necessary to select a solar cosmic ray model that meets the requirements of the solar cosmic ray model selection instruction from a variety of different angles in this application according to the on-orbit period of the spacecraft, the type of effect concerned, whether the object of analysis is effect or probability, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of space radiation environment design related to spacecraft and analysis of space radiation effects, fault analysis and ground environment parameter design caused by it. Specifically, the present invention relates to a method for selecting a solar cosmic ray environment model. Background Art

[0002] Solar cosmic rays are a type of space environment that consists of all elements in the universe. They are mainly caused by solar activity, but the most important component is protons, namely hydrogen (H). Solar cosmic rays refer to a large number of high-energy protons, electrons, and heavy nuclear particle streams emitted during the solar explosive activity, most of which are composed of protons. They are sometimes called solar proton events, or solar particle events (SPEs). However, there is a slight difference in concept. Generally, an event in which a series of solar cosmic rays are generated by solar explosions is called a solar proton event, and the environment of the solar proton event itself is called a solar cosmic ray.

[0003] Generally, solar cosmic ray particles can be produced by two types of processes: one is solar flares, which are energy excitation phenomena that can be observed on the surface of the sun; the other is shock waves that propagate in interplanetary space driven by coronal mass ejections. The energy range of solar cosmic ray particles generally ranges from 10MeV to tens of GeV. The internationally recognized standard for solar proton events is: near the Earth's orbit, that is, at a distance of 1AU from the sun, the observed proton flux from the sun with an energy greater than 10MeV exceeds 10pfu (p·cm-2·sr-1·s-1) for 15 consecutive minutes.

[0004] On the one hand, solar activity modulates solar cosmic rays. The intensity and frequency of solar proton events are clearly correlated with the solar activity cycle. Large-scale solar proton events often occur when the overall solar activity level is high, that is, when the number of sunspots is high. Statistical results show that near the peak year of solar activity, there are more solar proton events, with more than 10 events per year. Due to the sporadic nature of solar proton events, sometimes there are no events for several months, and sometimes there are several events in a month. In years with low solar activity, the probability of solar proton events is lower, generally only 3 to 4 times a year, or even less. The comparative relationship between the annual number of solar particle events and the average annual number of sunspots can be seen in Figure 1 .

[0005] On the other hand, the geomagnetic field also modulates solar cosmic rays. After entering the range of the geomagnetic field, solar cosmic rays will be deflected to varying degrees by the geomagnetic field. The ability of charged particles to resist the deflection of the geomagnetic field is expressed by magnetic stiffness R = APC / Ze. For charged particles from outside the geomagnetic field to pass through the geomagnetic field, the particles must have a sufficiently large magnetic stiffness. To reach a specific point in the magnetosphere from a specific direction, the particles must have a certain amount of energy. Due to the distribution characteristics of the geomagnetic field, the particle energy required to reach the polar region is much smaller than that required to reach the equatorial region.

[0006] In addition, there is also the radiation damage effect of solar cosmic rays. From the perspective of the cumulative effect of solar cosmic rays on spacecraft, the long-term cumulative effect of solar cosmic rays on spacecraft is mainly divided into the total ionization dose effect and the displacement damage effect. The mechanism is that after the charged particles in space are incident on the spacecraft absorber (electronic components or materials), they produce ionization effect on it, and at the same time, the energy is ionized and absorbed by the atoms in the absorber, thereby causing total dose damage to the spacecraft absorber, and it tends to worsen with the extension of radiation time, which can cause charge activation, charge transfer, valence bond changes, decomposition, increased defect density, reduced carrier lifetime, increased dark current of photoelectric devices, increased radiation damage to solar cells, etc.

[0007] From the perspective of the transient effects of solar cosmic rays on spacecraft, the single particle effect mainly caused by the transient effects of solar cosmic rays on spacecraft is that a single high-energy charged particle generates a large number of charged particles in the sensitive area of ​​the device, causing soft errors in semiconductor devices, single particle upsets in logic devices and memories, single particle lockups in CMOS devices, and even single particle permanent damage. It can be divided into single particle upsets, single particle lockups, single particle gate breakdown, single particle burnout, single particle functional interruption, single particle multi-bit errors, single particle transients, single particle induced dark currents, etc.

[0008] Generally, commonly used solar cosmic ray models are known in the art, including solar cosmic ray flux models and solar cosmic ray peak flux models. Solar cosmic ray flux models mainly include King model, JPL model, ESP model, ISO18147 model, etc. These models are based on the observation data of solar particle events that occurred in history, and use statistical methods to obtain the probability distribution of the cumulative flux of solar protons in different mission periods to form the so-called statistical model. In addition, the 19-week solar cosmic ray model that accumulates all solar proton fluxes in the 19th solar activity week has also been used in international spacecraft design. A comparison of different solar cosmic ray flux models is shown in Table 1.

[0009] Table 1 Comparison of characteristics of commonly used solar cosmic ray models

[0010]

[0011] Table 1 Comparison of characteristics of commonly used solar cosmic ray models (continued)

[0012]

[0013] The solar cosmic ray peak flux models mainly include the CREME96 model, the CHIME model, etc. In addition, the above-mentioned ESP model, ISO 18147 model, etc. can also give the peak flux of solar protons and heavy ions. These models are often used to predict the analysis of transient single particle effects. The characteristics of some solar cosmic ray peak flux models are compared in Table 2.

[0014] Table 2 Comparison of characteristics of some solar cosmic ray peak flux models

[0015] Summary of the invention

[0016] The technical problem to be solved by the present invention is to overcome to a certain extent the problem in the related art that there is no unified method for selecting the corresponding solar cosmic ray model according to the use environment, which leads to inconvenience in using the solar cosmic ray model. The present application provides a method for selecting a solar cosmic ray model and a storage medium thereof.

[0017] Selection of space solar cosmic ray models involved in space environment analysis, effect prediction and on-orbit failure analysis of spacecraft during spacecraft development.

[0018] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0019] The method for selecting the solar cosmic ray model includes the following steps:

[0020] Determine important parameters of spacecraft engineering missions

[0021] From the perspective of the spacecraft engineering mission itself, the orbit of the spacecraft, the launch cycle, the solar activity and the important parameters of the on-orbit life are mainly determined. For example, the space station is located in the LEO orbit, the navigation satellite may have LEO, MEO and GEO orbits, and the communication satellite is mainly located in the GEO orbit.

[0022] Is it affected by geomagnetic shielding?

[0023] Based on the orbital position of the spacecraft and the height of the geomagnetic field, it is determined whether the solar cosmic ray particles are affected by the geomagnetic field. Based on the orbital altitude of the spacecraft, it is determined whether the spacecraft is within the geomagnetic layer. If the spacecraft's operating altitude is within the geomagnetic layer, the solar cosmic rays are affected by the geomagnetic shielding; if it is outside the geomagnetic layer, they are not affected by the geomagnetic shielding; if the orbital altitude is changing, the spacecraft may need to frequently cross the geomagnetic layer and is periodically affected by the geomagnetic layer.

[0024] The analysis is concerned with the environment and effects of solar cosmic rays, or the probability of solar proton events. For the spacecraft itself, the impact of solar cosmic rays on the spacecraft needs to be paid attention to, that is, the radiation effect of solar cosmic rays. If the concern is to analyze the probability of a certain type of space environment event, such as the probability of single particle upset, then the probability of solar proton events needs to be paid attention to.

[0025] When analyzing the effects of solar cosmic rays, the main consideration is whether to focus on transient effects or cumulative effects, while also considering the probability of solar proton events. Among them, single-particle effects (also called single-particle events) are transient effects, and if it is the total ionization dose or the total displacement dose, it is a cumulative effect.

[0026] Depending on the type of solar cosmic ray effect of concern, the type of solar cosmic ray model can be selected accordingly, including the solar cosmic ray peak flux model, injection model, solar proton event probability model or abnormal large event probability model.

[0027] Probability Analysis of Solar Proton Events

[0028] The probability of occurrence of solar proton events is analyzed mainly from the perspective of their use in the analysis of the solar cosmic ray environment and effects. Three situations should be considered: (1) the probability of a solar proton event occurring within a given mission cycle, such as the probability of a solar proton event occurring within a period from the beginning of N to the end of N+n years; (2) whether the focus is on the frequency of solar proton events and the energy spectrum of particles greater than or less than a certain energy, for the analysis of single particle events, etc. For example, within the mission cycle, how many times per year may solar proton events occur, and what is the energy spectrum distribution law of protons greater than a certain energy, such as 30MeV; (3) the situation of possible abnormal large solar proton events. Abnormal large events usually refer to proton events with energy greater than a certain value and fluence greater than a certain value.

[0029] Selection of solar cosmic ray model.

[0030] 1. Selection of solar cosmic ray fluence model

[0031] The proton fluence in a solar particle event over a mission period (1 year or more) can be modeled using the ESP. For mission periods less than 1 year, the fluence is usually 1 year. When the mission period is longer than 1 solar cycle (11 years), the total number of years of high solar activity within the mission period is usually used.

[0032] For interplanetary missions, a correction factor is used to deal with the solar particle model. For the case of r<1AU, the correction factor is r-2, and for the case of r>1AU, the correction factor is 1.

[0033] 2. Selection of peak flux model for solar cosmic rays

[0034] For the peak solar particle flux, the CREME96 model can be used.

[0035] The peak flux of solar particles can be selected from the worst 5 minutes, worst 1 day, and worst 1 week values ​​respectively.

[0036] 3. Selection of probability model for solar particle events

[0037] The JPL91 model can be used to estimate the probability of a solar particle event occurring within a given mission period.

[0038] The ISO 18147 model can be used for the occurrence frequency and energy spectrum distribution function of solar particle events.

[0039] 4. Selection of probability model for abnormal solar particle events

[0040] The King model or October 89 model can be used to analyze the probability of proton events with energy greater than a certain value and injection greater than a certain value.

[0041] Using this method, the solar cosmic ray model that should be used for aerospace engineering missions or spacecraft on-orbit fault analysis can be quickly determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a structural diagram of the annual number of solar particle events and the average annual number of sunspots:

[0043] Figure 2 A flow chart of a method for selecting a solar cosmic ray model of the present invention;

[0044] Figure 3 This is the process of determining the solar cosmic ray model during the execution of the spacecraft engineering mission in Example 1 of the present invention. DETAILED DESCRIPTION

[0045] The following is the attached Figure 2-3 The test method and the test system of the present invention are described in detail, but the description is merely exemplary and is not intended to limit the protection scope of the present invention in any way.

[0046] Example 1: A Chinese space station is set up in a medium orbit with an orbit altitude of 400 km, an inclination of 42-43 degrees, a design life of more than 10 years, and a launch date of April 29, 2021. For example, see Figure 3 .

[0047] First, spacecraft engineering mission analysis.

[0048] It mainly determines the orbit of the spacecraft, the launch date, the solar activity, the life in orbit, etc. For example, the space station is located in the LEO orbit, the navigation satellite may have LEO, MEO, and GEO orbits, and the communication satellite is mainly located in the GEO orbit. Taking the Chinese space station as an example, the orbit altitude is 400km, the inclination is 42-43 degrees, the design life is more than 10 years, and the launch date is April 29, 2021. (https: / / baike.so.com / doc / 5857552-6070395.html)

[0049] Second, whether it is affected by the geomagnetic shielding.

[0050] Since charged particles are modulated by the geomagnetic shield, only particles with a magnetic stiffness greater than the geomagnetic cutoff stiffness can penetrate the geomagnetic layer and enter the orbital position of the spacecraft. The Earth's magnetosphere is located 600 to 1,000 kilometers above the ground. The outer boundary of the magnetosphere is called the magnetopause, which is 50,000 to 70,000 kilometers from the ground. Under the compression of the solar wind, the Earth's magnetic field lines extend far into the space on the side facing away from the sun, forming a long tail called the magnetotail. Therefore, most LEO orbit satellites are located in the geomagnetic layer and are protected by the geomagnetic layer. Deep space probes represented by the "Chang'e" series pass through the magnetosphere and enter deep space orbits, and the surrounding space environment is not affected by the geomagnetic field.

[0051] Third, the analysis focuses on the environment and effects of solar cosmic rays or the probability of solar proton events.

[0052] For the space radiation effects of spacecraft, we need to analyze whether we are concerned about transient effects or cumulative effects. In the process of effect analysis, we need to analyze the probability of a possible solar proton event. For single-particle effects, whether it is single-particle flipping, single-particle locking or single-particle burning, we focus on transient effects, that is, the effects of single high-energy particles, especially protons, on spacecraft. For total ionization dose effects and displacement damage effects, we focus on the effects of cumulative damage. However, the premise for the occurrence of these effects is whether a solar proton event occurs.

[0053] Fourth, analysis of solar cosmic ray effects.

[0054] The radiation effects of solar cosmic rays on spacecraft can be divided into transient effects and cumulative effects. Transient effects are mainly single-particle effects. Cumulative effects are mainly total ionization dose effects and displacement damage effects (also called total displacement damage dose effects). For the Chinese space station, if it is its electronic systems, especially electronic devices, most of the focus is on transient effects, that is, single-particle effects. It is necessary to focus on single-particle effects such as single-particle flips, single-particle burnouts, and single-particle locks caused by the peak flux of solar cosmic rays; and for the long-term operation of the space station, it is necessary to pay attention to the cumulative total ionization dose and displacement total dose effects of sensitive materials and devices, such as the total ionization dose of electronic components, optical window glass, thermal control materials, etc. For example, the solar cells, optocouplers, optical waveguides, solar cells, photodiodes, phototransistors, etc. used on the space station need to pay attention to the increase in dark current, the decrease in open-circuit voltage, and the increase in signal-to-noise ratio caused by their total displacement dose effects.

[0055] Analysis of environmental characteristics corresponding to the solar cosmic ray radiation effects;

[0056] The transient effect is mainly related to the peak flux of solar cosmic rays, while the cumulative effect is mainly related to the fluence of solar cosmic rays. Peak flux mainly refers to the high flux of solar high-energy particles, especially solar protons, in a specific time period, such as 5 minutes, 1 day, 1 week, etc. The peak flux is usually expressed in terms of integral flux and differential flux. Flux refers to the number of particles passing through a unit area per unit time, also called fluence rate or flux density, with units of cm -2 ·s -1 The unidirectional flux is the number of particles incident from a certain direction per unit time per unit solid angle and per unit area, and the unit is, usually with the symbol of the particle. The integrated flux is the flux of particles with energy exceeding a given energy (E0). The unit of the omnidirectional integrated flux is cm -2 ·s -1 , the unit of unidirectional flux is cm -2 ·s -1 ·sr -1 , differential flux refers to the particle flux in the energy range from E to E+dE. The unit of unidirectional differential flux is cm -2 ·s -1 ·sr -1 MeV -1 .

[0057] Fluence is the integral of flux over time, that is, the number of particles passing through a unit area in a certain period of time. From a physical definition, fluence is the time-integrated flux of incident particles per unit area, also called cumulative flux, with units of cm -2, usually with the sign of the particle. It often refers to the total number of particles with energy greater than a certain value over a period of time. Fluence is a cumulative quantity, so it is closely related to the total ionization dose and the total displacement dose.

[0058] Fifth, probability analysis of the occurrence of solar cosmic rays.

[0059] Three situations should be considered: (1) the probability of a solar proton event occurring within a given mission cycle, such as the probability of a solar proton event occurring within a period from year N to year N+n; (2) whether the focus is on the frequency of solar proton events and the energy spectrum of particles with energies greater than or less than a certain value, for the analysis of single particle events, etc. For example, within the mission cycle, how many times a year is the frequency of solar proton events likely to occur, and what is the energy spectrum distribution law of protons with energies greater than a certain value, such as 30 MeV; (3) the possibility of abnormal solar proton events. Abnormal large events usually refer to proton events with energies greater than a certain value and a flux greater than a certain value. Abnormal solar proton events that have occurred in history are generally used as references, such as solar proton events caused by the solar eruption in August 1972 and the solar eruption in October 1989.

[0060] Sixth, the selection of the solar cosmic ray model.

[0061] (1) Selection of solar cosmic ray fluence model

[0062] The proton fluence during a solar particle event over a mission period (1 year or more) can be modeled using the ESP.

[0063] For mission cycles of less than 1 year, the injection volume is usually 1 year's injection volume.

[0064] When the mission period is longer than one solar cycle (11 years), the total number of years of high solar activity within the mission period is usually used.

[0065] For interplanetary missions, a correction factor is used to deal with the solar particle model. For the case of r<1AU, the correction factor is r-2, and for the case of r>1AU, the correction factor is 1.

[0066] (2) Selection of peak flux model for solar cosmic rays

[0067] For the peak solar particle flux, the CREME96 model can be used.

[0068] The peak flux of solar particles can be selected from the worst 5 minutes, worst 1 day, and worst 1 week values ​​respectively.

[0069] (3) Selection of probability model for solar particle events

[0070] The JPL91 model can be used to estimate the probability of a solar particle event occurring within a given mission period.

[0071] The ISO 18147 model can be used for the occurrence frequency and energy spectrum distribution function of solar particle events.

[0072] (4) Selection of probability model for anomalous solar particle events

[0073] The King model or October 89 model can be used to analyze the probability of proton events with energy greater than a certain value and injection greater than a certain value.

[0074] The King model is used as the probability and flux model of abnormal solar particle events based on the solar particle event data in August 1972. It is suitable for the analysis of the impact of solar cosmic rays when the particle energy is 10-70MeV and the spacecraft protection thickness is 1-10mm.

[0075] The particle flux model for abnormal solar particle events based on the solar particle event data in October 1989 is the October 89 model. It is suitable for the analysis of low-energy particle flux for the study of spacecraft surface materials and solar cell effects and high-energy particle flux for deep protection research.

[0076] Although the specific embodiments of the present invention are described and illustrated in detail above, it should be pointed out that various equivalent changes and modifications can be made to the above embodiments based on the concept of the present invention. As long as the functional effects produced do not exceed the spirit covered by the specification and drawings, they should all be within the protection scope of the present invention.

Claims

1. The method for selecting a solar cosmic ray model includes the following steps: First, determine the important parameters of the spacecraft engineering mission From the spacecraft engineering mission itself, determine the orbit of the spacecraft, the launch cycle, the solar activity and the important parameters of the on-orbit life; Second, whether it is affected by geomagnetic shielding According to the orbital position of the spacecraft and the height of the geomagnetic field, it is determined whether the solar cosmic ray particles are affected by the geomagnetic field. According to the orbital height of the spacecraft, it is determined whether the spacecraft is in the geomagnetic layer. If the spacecraft is in the geomagnetic layer, the solar cosmic rays are affected by the geomagnetic shielding; if it is outside the geomagnetic layer, it is not affected by the geomagnetic shielding; if the orbital height is variable, the spacecraft needs to frequently cross the geomagnetic layer, and it is periodically affected by the geomagnetic layer. Third, the analysis is concerned with the environment and effects of solar cosmic rays, or the probability of solar proton events. For the spacecraft itself, it is necessary to focus on the impact of solar cosmic rays on the spacecraft, that is, the solar cosmic ray radiation effect; if the concern is to analyze the probability of a certain type of space environment event, then it is necessary to focus on the probability of solar proton events; Fourth, when analyzing the effects of solar cosmic rays, we should mainly consider whether the focus is on transient effects or cumulative effects, and also consider the probability of solar proton events. For single particle effects, they are transient effects, while for total ionization dose or total displacement dose, they are cumulative effects. Fifth, the type of solar cosmic ray model is selected according to the type of solar cosmic ray effect of concern, including the peak flux model, injection model, solar proton event probability model or abnormal large event probability model of solar cosmic ray; Sixth, the probability of a solar proton event is analyzed mainly from the perspective of its use in the analysis of the solar cosmic ray environment and effects. Three situations should be considered: (1) the probability of a solar proton event occurring within a given mission cycle, and the probability of a solar proton event occurring; (2) whether the focus is on the frequency of solar proton events and the energy spectrum of particles greater than or less than a certain energy, for the analysis of single particle events; (3) the possibility of an abnormally large solar proton event; an abnormally large event refers to a proton event with an energy greater than a certain value and a flux greater than a certain value; Seventh, the selection of solar cosmic ray model 1) Selection of solar cosmic ray fluence model The proton fluence during a mission cycle solar particle event is modeled using the ESP; Wherein: the mission period is 1 year and / or more; 2) Selection of peak flux model of solar cosmic rays For the peak solar particle flux, the CREME96 model is used; 3) Selection of probability model for solar particle events The JPL91 model can be used to determine the probability of solar particle events occurring within a given mission period. The frequency and energy spectrum distribution function of solar particle events use the ISO 18147 model; 4) Selection of probability model for abnormal solar particle events The King model or October 89 model is used to analyze the probability of proton events with energy greater than a certain value and injection greater than a certain value.

2. The method of claim 1, wherein: The space station is located in the LEO orbit, the navigation satellite may be located in the LEO, MEO, or GEO orbits, and the communication satellite is mainly located in the GEO orbit.

3. The method of claim 1, wherein: Single event effects include single event upset, single event latch-up, and single event burnout.

4. The method of claim 1, wherein: Analyzing the probability of a solar proton event means how many times a year a solar proton event may occur during the mission cycle, and what the energy spectrum distribution pattern of protons with an energy ratio greater than a certain value is.

5. The method of claim 1, wherein: For mission periods of less than 1 year, the injection volume is usually 1 year's injection volume. When the mission period is longer than 1 solar activity cycle, the total number of years of high solar activity cycles within the mission period is used.

6. The method of claim 1, wherein: For interplanetary missions, a correction factor is used to deal with the solar particle model. For r < 1 AU, the correction factor is r -2 , for r>1AU, the correction factor is 1.

7. The method according to any one of claims 1 to 6, wherein: The peak flux of solar particles uses the values ​​of the worst 5 minutes, worst 1 day, and worst 1 week respectively.

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