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和最终准确预测辐射带内高能粒子的可变性。能量范围在几十万电子伏特(Kev)到几百万电子伏特(Mev)的电子可能会通过辐射损伤和深层介质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在预测地球同步轨道上和轨道内的MeV电子方面取得了重大进展，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。以往的径向扩散模型都假定辐射带外边界处有源布居，但由于观测有限，这一假设的正确性一直难以得到证实。这种不确定性还提出了所使用的径向扩散系数和损失率的有效性的问题。这个项目将通过使用实际测量的电子作为源总体来消除这种不确定性。这将通过使用洛斯阿拉莫斯国家实验室(LANL)地球同步轨道传感器的数据来实现。其目标是量化径向扩散对地球同步轨道内MeV电子加速的贡献。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。这种比较将使我们有可能确定有多少MeV电子的增强可以归因于径向扩散。大部分研究将由一名研究生在首席调查员的指导下进行。

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.