Quantification of Radial Diffusion in Energizing MeV (Millions of Electron Volts) Electrons in the Magnetosphere

磁层研究的一个重要目标是了解并最终准确预测辐射带中高能粒子的变异性。能量范围在几十万电子伏特（keV）到几百万电子伏特（MeV）之间的电子可以通过辐射损伤和深介电充电对航天器电子设备产生有害影响。尽管利用径向扩散模型预测地球同步轨道上和轨道内的MeV电子已经取得了重大进展，但控制这些电子变异性的不同物理机制的定量贡献仍然不清楚。以往的辐射扩散模型假设辐射源种群位于辐射带的外边界，但由于观测资料有限，很难证实这一假设的有效性。这种不确定性也提出了所用径向扩散系数和损失率的有效性问题。这个项目将通过实际测量电子作为源群来消除这种不确定性。这将通过在地球同步轨道上使用洛斯阿拉莫斯国家实验室（LANL）传感器的数据来完成。目标是量化径向扩散对地球同步轨道内MeV电子加速度的贡献。该项目将利用SAMPEX和Polar卫星的数据，将实际损失率纳入扩散模型。地球同步轨道内的模型结果将与极地测量结果进行比较。这种比较将使确定多少MeV电子的增强可归因于径向扩散成为可能。研究的很大一部分将由一名研究生在首席研究员的指导下进行。

An important objective of magnetospheric research is the understanding and eventual accurate prediction of the variability of energetic particles in the radiation belts. Electrons in the energy range of a few hundred thousands of electron volts (keV) to a few millions of electron volts (MeV) can have deleterious effects on spacecraft electronics through radiation damage and deep dielectric charging. Though significant progress has been made in predicting MeV electrons at and inside geosynchronous orbit using the radial diffusion model, the quantitative contribution of different physical mechanisms governing the variability of these electrons are still unclear. Previous radial diffusion models have assumed a source population at the outer boundary of the radiation belt, but it has been difficult to confirm the validity of this assumption due to limited observations. This uncertainty also raises the question of the validity of the radial diffusion coefficients and loss rates used. This project will eliminate this uncertainty by using actual measurements of electrons as the source population. This will be accomplished by using data from Los Alamos National Laboratory (LANL) sensors at geosynchronous orbit. The goal is to quantify the contribution of radial diffusion to the acceleration of MeV electrons inside geosynchronous orbit. The project will incorporate realistic loss rates into the diffusion model by using data from the SAMPEX and Polar satellites. The model results inside geosynchronous orbit will be compared to Polar measurements. This comparison will make it possible to determine how much enhancement of MeV electrons can be attributed to radial diffusion. A significant portion of the research will be carried out by a graduate student under the direction of the Principal Investigator.