GEM: Suprathermal and Energetic Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Inner Magnetosphere

本课题主要研究地球磁层等离子体波对离子的加热作用。电磁离子回旋波和磁声波是由环电流离子在磁层中产生的等离子体波。这些等离子体波可以散射和加热离子，将能量从环电流转移到其他区域或人群。这个项目通过结合模拟和范艾伦探测器的观测来研究离子加热过程。建模工作将揭示波粒相互作用中离子的来源。了解离子动力学将有助于未来穿越磁层的太空任务和离子波相互作用在空间天气预报中的实现。该项目将有助于量化磁层内部的离子通量变化，许多卫星在磁层内部运行，以提供人类通信、导航和安全的基本需求。该项目支持波士顿大学的两名早期职业科学家、一名女教师和一名研究生。波士顿大学空间物理中心为空间科学研究、学生培训和教学、社区参与和推广活动等方面的合作提供了理想的环境。本项目旨在通过综合卫星观测和数值模拟，确定电磁波和磁声波共振离子加热的条件和后果。首先，将使用范艾伦探测器的数据对离子加热事件进行调查。离子加热事件将根据不同的波性质和背景等离子体参数进行分类，以揭示引起内磁层明显离子加热特征的临界条件。其次，对电磁场和磁声波事件中离子的加热和散射效应进行了拟线性模拟。模拟输入由观测所得的波特性和本底等离子体参数提供，以证明离子加热的效率和能量。第三，由于位源波和磁声波的振幅可能很大，以至于它们可以打破准线性近似，因此离子与大振幅波之间的相互作用将使用测试粒子代码进行评估。一系列的测试粒子模拟将通过不同的波幅值来找到非线性效应变得重要的阈值。我们还将评估强磁场波和强磁声波的离子相俘获和聚束效应，以量化它们在不同能量下对离子加速的贡献。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。

The focus of this project is to study the ion heating by plasma waves in the Earth's magnetosphere. The electromagnetic ion cyclotron (EMIC) and magnetosonic waves are plasma waves generated by ring current ions in the magnetosphere. These plasma waves could scatter and heat the ions, transferring energy from the ring current to other regions or populations. This project investigates the ion heating process by combining simulations with Van Allen Probes observations. The modeling efforts will reveal the source of ions from wave-particle interaction. Understanding the ion dynamics will help future space missions traveling through the magnetosphere and implementation of the ion-wave interaction effects in space weather prediction. This project will help quantify the ion flux variations in the inner magnetosphere, where many satellites are operating to provide human's essential needs of communication, navigation, and security. This project supports two early-career scientists, a female faculty and a graduate student at Boston University. The Center for Space Physics at Boston University provides an ideal environment for collaboration in space science research, student training and teaching, community engagement, and outreach activities.This project aims to determine the conditions and consequences of resonant ion heating by EMIC and magnetosonic waves through comprehensive satellite observations and numerical modeling. Firstly, a survey of ion heating events will be performed using the Van Allen Probes data. The ion heating events will be categorized by different wave properties and background plasma parameters, to reveal the critical conditions that cause evident ion heating features in the inner magnetosphere. Secondly, a series of quasilinear simulations of the ion heating and scattering effects will be performed during the EMIC and magnetosonic wave events. The simulation inputs are provided by the wave properties and background plasma parameters from the survey to demonstrate the efficiency and energies of ion heating. Thirdly, since the amplitudes of EMIC and magnetosonic waves could be large so that they can break the quasi-linear approximation, the interaction between ions and large amplitude waves will be evaluated using a test particle code. A series of test particle simulations will be performed through varying wave amplitudes to find the threshold beyond which nonlinear effects become important. The ion phase trapping and bunching effects by strong EMIC and magnetosonic waves will also be evaluated to quantify their contribution to ion acceleration at different energies.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.