NSWP: Theoretical Modeling of the Inner Radiation Belt, II

NSWP：内辐射带的理论模型，II

• 批准号: 0518190
• 负责人: Richard Selesnick
• 金额: --
• 依托单位: Aerospace Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0518190&HistoricalAwards=false
• 关键词: NSWP; Theoretical; Modeling; Inner; Radiation

This project will construct a comprehensive theoretical model of the Earth's inner radiation belt protons and light ions. The model will be based on an existing simplified proton model. It will describe the inner zone's full spatial dependence, energy dependence, and solar cycle time dependence. Components of the model will include: Monte Carlo simulation of the albedo neutron decay source; injection of solar protons and helium; secondary sources of light ions from nuclear reactions of trapped protons with the neutral atmosphere; energy loss to ionization of the neutral atmosphere, and to free electrons in the ionosphere and plasmasphere, with solar cycle dependence from the historical solar activity record; particle acceleration by adiabatic compression based on multipole geomagnetic field models from the archeomagnetic record and the International Geomagnetic Reference Field; numerical trapped particle trajectory tracing to calculate drift averages of the neutron decay source and the atmospheric densities, and the rigidity trapping limits; nuclear scattering of the trapped particles from the neutral atmosphere, including elastic and inelastic processes; radial diffusion with empirically determined diffusion coefficients; and decay of radioactive trapped secondaries. The resulting model will be compared to existing radiation belt data and empirical models for validation. The model will provide a framework for understanding the physical processes occurring in the inner zone of the radiation belt. The proposed quantitative study of the relative importance of each model component will lead to a new understanding of the dominant physical mechanisms. In particular, the lifetimes and significant loss mechanisms of the trapped particles will be determined, the relative significance of the external (radial diffusion) and internal (neutron decay and nuclear reaction) sources will be evaluated, and the nuclear reactions that are significant for populating the inner radiation belt will be identified. An accurate model the inner radiation belt will be of practical value for specifying the hazardous radiation environment in low Earth orbit. Current empirical models are used extensively in spacecraft design but are lacking in the detailed energy, spatial, and temporal variations that will be addressed in this work.

该项目将构建地球内辐射带质子和轻离子的综合理论模型。该模型将以现有的简化质子模型为基础。它将描述内区的完整空间依赖性，能量依赖性和太阳周期时间依赖性。该模型的组成部分将包括：蒙特卡罗模拟中子衰变源;注入太阳质子和氦;捕获的质子与中性大气层的核反应产生的轻离子次级源;中性大气层电离以及电离层和等离子体中自由电子的能量损失，其中太阳周期依赖于历史太阳活动记录;基于古地磁记录和国际地磁参考场多极地磁场模型的绝热压缩粒子加速：计算中子衰变源和大气密度漂移平均值的俘获粒子轨道数值追踪，以及刚性俘获极限;中性大气中俘获粒子的核散射，包括弹性和非弹性过程;根据经验确定扩散系数的径向扩散;以及放射性俘获二次衰变。所产生的模型将与现有的辐射带数据和经验模型进行比较，以进行验证。该模型将为理解辐射带内部区域发生的物理过程提供一个框架。拟议的定量研究的相对重要性，每个模型组件将导致一个新的理解的主导物理机制。特别是，将确定被捕获粒子的寿命和重大损失机制，将评估外部（径向扩散）和内部（中子衰变和核反应）源的相对重要性，并将确定对填充内辐射带具有重要意义的核反应。精确的内辐射带模型对于确定近地轨道辐射环境的危害性具有重要的实用价值。目前的经验模型被广泛用于航天器的设计，但缺乏详细的能源，空间和时间的变化，将在这项工作中解决。