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

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。地球周围的辐射带主要由被太阳风和宇宙射线捕获的相对论粒子组成。这个空间区域是非常有活力的。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。这个项目将在多点空间观测的指导下，用3-D混合模拟和测试粒子电子计算相结合的方法来研究这些过程。这些结果将在理解地球和其他行星的磁层方面有广泛的应用。这项工作支持一名博士生和两名本科生。该项目将确定ULF波，包括电磁离子回旋(EMIC)波和动力学阿尔芬波(KAWS)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)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？来自尾部或外部压缩的局域注入如何激发EMIC/Alfven波？(2)这些EMIC波和KAW中高能电子的输运系数是多少，与之相关的电子散射和进入损失锥的沉淀是什么？(3)ULF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。描述完全动力学离子物理的混合模型包括偶极几何中的磁层内部混合模型和基于自洽太阳风-磁层相互作用的三维奥本全球混合程序(ANGIE3D)。这些模拟将通过NOAA和NASA操作的卫星的近赤道测量以及卫星、立方体卫星和气球实验的低空测量来验证。这一奖项反映了NSF的法定任务，并通过使用基金会的智力优势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.