Magnetic reconnection is an important energy conversion process that can impulsively release stored magnetic energies, and is highly relevant to solar, magnetospheric, and laboratory plasmas. Particle characteristics and their evolution in the diffusion region of collisionless reconnection is a largely unknown area, especially in 3D. This research will combine data analysis, simulation, and engineering expertise to map out distinct electron regions within the ion diffusion region of magnetotail reconnection using data from the multi-spacecraft mission Cluster. 2D and 3D PIC simulations will guide the interpretation of Cluster data. The project schedule: In year 1, distinct electron regions for Cluster reconnection events in the magnetotail will be reconstructed and the evolution of electron distribution functions during the course of reconnection will be investigated by PIC simulations. In year 2, electron characteristics and dynamics will be studied within the evolving electron current sheet during reconnection using 2D PIC simulations and high-resolution Cluster EDI electron data. In year 3, distinct electron regions around key energy conversion sites will be identified, including magnetic nulls, in 3D reconnection using Cluster and PIC simulation data. This proposal seeks to understand the nonlinear energy conversion physics in space plasmas that has crucial applications to solar and astrophysical physics as well as laboratory reconnection. The proposed study is key to understanding dissapation in reconnection layers in space. The expected new knowledge will further our understanding of how kinetic-scale plasma processes couple to macroscopic phenomena such as magnetospheric substorms. Results from the proposed investigation will be communicated to the science community in AGU meetings, and APS Division of Plasma Physics meetings. As part of the proposed effort, the results will be published in refereed journals. The results obtained through the proposed project will be organized into a minicourse on reconnection in the magnetotail. The minicourse will serve as an introduction to a key energy conversion process in the magnetosphere for pre-college (through partnership of UNH with the Harlem Children Society), undergraduate and graduate students at UNH. This proposal was submitted to the NSF-DoE Partnership in Plasma Science and Engineering joint solicitation 08-589. This award is being funded jointly by the Division of Physics of the Mathematical and Physical Sciences Directorate and by Atmospheric Sciences Division of the Geosciences Directorate
The project has resulted in high-impact discoveries on the kinetic physics of collisionless magnetic reconnection as well as new partnerships between the PI's group and several other leading research groups in space, simulation, and laboratory reconnection research. The impact is briefly summaried in the following two categories. (i) Intellectual Merit The discoveries made under the project have been documented in eight papers, including three papers in Physics of Plasmas, and conference presentations led by the students (high-school, undergraduate, and Ph.D.) and the PI. These discoveries are made through syntheses of space observations and fully kinetic plasma simulations. The discoveries include:1. highly anisotropic electrons in the reconnection inflow region, and highly structured electron distributions in reconnection exhaust. 2. electron phase-space-hole structure in the reconnection electron layer. 3. Discrete striation structures in the electron velocity distributions in the center of the electron diffusion layer, and the coherent distortion of striations into rings and acrs toward the end of the electron outflow jet . 4. Distinct electron regions at crater FTEs at the magnetopause, and in the magnetotail at dipolarization fronts, near 3D magnetic nulls, and in magnetic islands. Our understanding of the reconnection kinetic physics has achieved a new level that enables predictive capabilities based on measurements of plasma particles and fields. (ii) Broader Impact Our work on the kinetic physics of reconnection has broad impact on research fields involving impulsive energy release by reconnection in plasma systems where binary collisions are relatively unimportant, such as the magnetosphere, solar wind, solar corona, and other astrophysical and laboratory plasma systems. Through the project, the PI's research group have established partnerships with Bill Daughton at LANL, Jan Egedal at MIT, Masaaki Yamada at PPPL, Homa Karimabadi at UCSD, and Roy Torbert at UNH. The students supported by the grants received multi-faceted training - from space instrumentation and data analysis to plasma simulations and laboratory experiments. In addition to the PI who is a mid-career female physicist with two children, thirteen students have been supported in part by the project, including one female student who has graduated with a Master degree in Physics, two undergraduate students, four Ph.D. students in Physics, and six female high-school students who have moved on to major in physical sciences in college.
