Local physics control of the x-line orientation in three-dimensional asymmetric magnetic reconnection

三维不对称磁重联中x线方向的局部物理控制

• 批准号: 1757599
• 负责人: Yi-Hsin Liu
• 金额: $ 0.63万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1757599&HistoricalAwards=false
• 关键词: Local; physics; control; line; orientation

Magnetic reconnection is arguably one of the most important energy conversion and transport processes in space plasmas. This project aims to answer a fundamental question related to our understanding of magnetic reconnection: is there a simple principle that determines the orientation of the reconnection x-line in a asymmetric current sheet? The solution of this basic question remains unclear with our current understanding of magnetic reconnection, and the project aims to use Blue Waters to resolve this issue. Ultimately, the project's goal is to develop an understanding of the three-dimensional (3D) nature of asymmetric magnetic reconnection itself, which is an important step in the quest for predicting the location and orientation of magnetic reconnection in the Earth's magnetopause. Moreover, increased understanding of x-line will enable space scientists to more accurately estimate the efficiency of flux transfer from solar wind to the Earth's magnetosphere. In addition, the work proposed here is timely to the study of dayside reconnection during the 1st phase of NASA's Magnetospheric Multiscale Mission (MMS). The goal of the project centers around the local physics control of 3D x-line in asymmetric reconnection, which has a direct application to terrestrial magnetopause. The project will address the following questions: a) What is the underlying physics that control the 3D x-line orientation? b) How does the 3D x-line spread? Does it have an intrinsic extent? c) How does the diamagnetic drift affect the orientation and the motion of a 3D x-line? d) What role do oblique tearing instabilities and the resulting flux ropes play?The development of reconnection x-line requires a fully kinetic description, hence this project will employ the particle-in-cell (PIC) code, VPIC, which is optimized on the Blue Waters supercomputer. For 3D simulations, the project employs an innovative approach to induce a single x-line by using a localized perturbation so that the x-line has sufficient freedom to choose its orientation.

磁重联可以说是空间等离子体中最重要的能量转换和传输过程之一。这个项目旨在回答一个与我们对磁重联的理解相关的基本问题：在不对称电流片中，是否存在一个简单的原则来决定重联x线的方向？根据我们目前对磁重联的理解，这个基本问题的解决方案仍然不清楚，该项目旨在使用Blue Waters来解决这个问题。最终，该项目的目标是了解不对称磁重联本身的三维（3D）性质，这是预测地球磁层顶磁重联位置和方向的重要一步。此外，对x线的进一步了解将使空间科学家能够更准确地估计从太阳风到地球磁层的通量转移效率。此外，本文提出的工作对NASA磁层多尺度任务（MMS）第一阶段的日侧重联研究是及时的。该项目的目标是围绕不对称重联中三维x线的局部物理控制，这对地球磁层顶有直接的应用。该项目将解决以下问题：a)控制3D x线方向的底层物理是什么？b) 3D x线如何扩散？它有内在的程度吗？c)抗磁漂移如何影响三维x线的方向和运动？d)斜撕裂不稳定性和由此产生的通量绳起什么作用？重连x线的开发需要完整的动力学描述，因此该项目将采用在Blue Waters超级计算机上进行优化的粒子胞内（PIC）代码VPIC。对于3D模拟，该项目采用了一种创新的方法，通过局部扰动诱导单个x线，使x线有足够的自由选择其方向。

项目成果

Drift turbulence, particle transport, and anomalous dissipation at the reconnecting magnetopause

• DOI: 10.1063/1.5027086
• 发表时间: 2018-06-01
• 期刊: PHYSICS OF PLASMAS
• 影响因子: 2.2
• 作者: Le, A.;Daughton, W.;Bird, R.
• 通讯作者: Bird, R.

Orientation and Stability of Asymmetric Magnetic Reconnection X Line

• DOI: 10.1029/2018ja025410
• 发表时间: 2018-05
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: Yi‐Hsin Liu;Michael Hesse;Tak Chu Li;M. Kuznetsova;Ari Le