Collaborative Research: GEM--Transition from Ion-Coupled to Electron-Only Reconnection

磁场重联在太阳风磁场到地球磁场的能量传输中起着重要作用。这一过程通过亚风暴和磁鞘驱动磁尾中的全球能量释放。本项目研究磁鞘中的重联是如何发生的，重点是离子耦合和电子重联的相对贡献。了解磁重联对于与卫星相关的国家安全优先事项非常重要，因为这些事件产生的空间天气影响可能会损坏或摧毁这些系统。此外，该项目还将通过培养一名博士后和一名研究生，以及为处境危险的少数民族高中生提供实习机会，来支持下一代STEM科学家。本课题系统研究了离子偶联到纯电子磁重联的关键控制因素和能量释放特性。主要的子问题是：(1)什么因素控制从离子耦合到纯电子重联的转变？(2)在离子偶联少或无离子偶联的情况下，重联过程中控制加热的因素是什么？(3)三维物理是否影响离子耦合到纯电子重联的转变？细胞内粒子动力学模拟将在2-1/2和3维进行。将确定离子耦合程度、离子排气速度、电子排气速度和排气中的加热情况，并与入流条件进行比较，以确定关键控制因素，最终建立物理模型。模拟和模型将与MMS卫星观测的湍流磁鞘重联进行比较，以验证模型并在观测中找到离子耦合程度的线索。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。

Magnetic reconnection plays a fundamental role in energy transport from the solar wind magnetic fields to the Earth’s magnetic field. This process drives global energy releases in the magnetotail through sub-storms and in the magnetosheath. This project studies how reconnection in the magnetosheath occurs, focusing on the relative contributions from ion-coupled and electron-only reconnection. Understanding of magnetic reconnection is important to national security priorities related to satellites as these events produce space weather affects that can damage or destroy these systems. Additionally, the project will support the next generation of STEM scientists through training of a post-doc and a graduate student and providing internships for at-risk minority high school students.This project is a systematic study of key controlling factors and energy release properties of the transition from ion-coupled to electron-only magnetic reconnection. The primary sub-questions are: (1) What are the factors controlling the transition from ion-coupled to electron-only reconnection? (2) What are the factors controlling heating during reconnection with little or no ion coupling? And (3) Does 3D physics impact the transition from ion-coupled to electron-only reconnection? Kinetic particle-in-cell simulations will be conducted in 2-1/2 and 3 dimensions. The degree of ion coupling, ion exhaust velocities, electron exhaust velocities, and heating in the exhaust will be determined and compared with inflow conditions to determine the key controlling factors and ultimately all the creation of physical models. The simulations and models will be compared with MMS satellite observations of reconnection in the turbulent magnetosheath to both validate the models and find clues to the degree of ion coupling in the observations.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.