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

该奖项全部或部分由《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来自太阳风和宇宙射线的相对论性粒子组成。这个空间区域是非常动态的。在磁层内部，即辐射带中离地球较近的部分，超低频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，通过三维混合模拟结合测试粒子电子计算来研究这些过程。研究结果将对了解地球和其他行星的磁层具有广泛的应用价值。这项工作支持一名博士生和两名本科生。该项目将确定包括电磁离子回旋波（EMIC）波和动能阿尔芬波（KAWs）在内的超高频波在辐射带电子损失和电子径向扩散中的作用。将回答的科学问题包括：(1)哪些内部或外部过程控制了内磁层中场波和kaw的产生和整体结构，包括离子波-粒子相互作用？尾部局部注射或外部压迫如何激发EMIC/Alfven波？(2)高能电子在这些位相波和kaw中的输运系数是什么，以及相关的电子散射和沉降到损失锥中的情况是什么？(3)超短波波和外压缩脉冲对电子径向输运的影响是什么？该团队将在三维全球混合模拟中进行相对论性测试-粒子电子计算。混合模型描述了完全的离子动力学物理，包括偶极几何的内磁层混合模型和基于自一致太阳风-磁层相互作用的Auburn全局三维混合代码（ANGIE3D）。模拟将通过NOAA和NASA运行的卫星的近赤道测量和卫星、CubeSats的低空测量以及气球实验进行验证。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.