Collaborative Research: GEM--Radiation Belt Losses Using Combined Global Hybrid and Test Particle Simulations

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。地球周围的辐射带主要由从太阳风和宇宙射线中捕获的相对论粒子组成。这个空间区域是非常动态的。在内磁层中，超低频（ULF）波对粒子的加速和损失起着重要的作用。该项目将在多点空间观测的指导下，结合试验粒子电子计算，利用三维混合模拟来研究这些过程。结果将有广泛的应用，以了解地球和其他行星的磁层。这项工作支持博士学位。该项目将确定ULF波，包括电磁离子回旋（EMIC）波和动力阿尔芬波（KAWs），在辐射带电子损失以及电子径向扩散中的作用。所要回答的科学问题包括：（1）是什么内部或外部过程控制着内磁层EMIC波和KAWs的产生和全球结构，包括离子波-粒子相互作用？EMIC/Alfven波是如何由来自尾部的局部注入或外部压缩激发的？(2)在这些EMIC波和KAWs中，高能电子的输运系数是多少？相关的电子散射和沉淀到损失锥中是什么？(3)超低频波和外部压缩脉冲对电子径向输运的影响是什么？该团队将在3-D全球混合模拟中进行相对论测试粒子电子计算。混合模型，描述完全动力学离子物理，包括一个内磁层混合模型的偶极子几何和奥本全球混合代码在3-D（ANGIE 3D）的基础上自洽的太阳风磁层相互作用。模拟将通过NOAA和NASA操作卫星的近赤道测量观测以及卫星、CubeSats和气球实验的低空测量进行验证。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The radiation belts around the Earth consist mainly of relativistic particles that are trapped from the solar wind and cosmic rays. This region of space is extremely dynamic. In the inner magnetosphere, the part of the radiation belts closer to Earth, ultra-low frequency (ULF) waves play important roles in the acceleration and loss of particles. This project will investigate these processes with 3-D hybrid simulations combined with test-particle electron calculations, guided by multipoint space observations. Results will have broad application to understanding magnetospheres of the Earth and other planets. The work supports a Ph.D. student and two undergraduate students.The project will establish the role of ULF waves, including electromagnetic ion cyclotron (EMIC) waves and kinetic Alfven waves (KAWs), in the radiation belt electron loss as well as electron radial diffusion. The science questions that will be answered include: (1) What internal or external processes control the generation and global structure, including ion wave-particle interactions, of EMIC waves and KAWs in the inner magnetosphere? How are EMIC/Alfven waves excited by localized injections from the tail or external compressions? (2) What are the transport coefficients of energetic electrons in these EMIC waves and KAWs, and what are the associated electron scattering and precipitation into the loss cone? (3) What are the effects of ULF waves and external compressional pulses on electron radial transport? The team will conduct relativistic test-particle electron calculations in 3-D global hybrid simulations. The hybrid models, describing fully kinetic ion physics, include an inner magnetospheric hybrid model in dipole geometry and the Auburn global hybrid code in 3-D (ANGIE3D) based on the self-consistent solar wind-magnetosphere interaction. The simulations will be validated with observations of the near-equatorial measurements from NOAA and NASA operated satellites and low-altitude measurements from satellites, CubeSats, and balloon experiments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.