Electrons in the Geomagnetic Tail

[9312467] ashourr - abdalla提出的理论研究是计算地磁尾到地球磁层的电子分布，并评估局部和全局电子和离子之间的电荷中性问题。虽然离子在磁尾中的动力学已经成为广泛的理论研究的主题，使用单粒子轨道计算、混合模拟和磁流体动力学模拟，但电子动力学实际上被忽略了。然而，等离子体最基本的方面——电荷中性的建立和维持——取决于电子的行为。有些电子以高速运动，并迅速穿越大量空间；局部电荷中性的建立既依赖于电子的全局源和汇，也依赖于尾部电场和磁场的大尺度结构。到目前为止，还没有科学的方法能够解决全局输运和计算电子在尾部的局部分布。在提出的大规模动力学方法中，从不同的源区域开始，电子将被允许沿着使用模型电磁场确定的轨迹在磁尾的整个体积中传播，以表示尾部配置。局部电子分布函数将通过将通过局部空间区域的每个轨迹的贡献相加来计算，并且将电子密度与局部离子密度（由大规模动力学技术类似地计算）进行比较，以确定电荷中性违反的程度。电磁场模型中加入平行电场，并进行调整，使电子和离子电荷密度达到最合理的平衡。这一提议的潜在意义是深远的，因为它的成功，我们可以第一次直接评估空间等离子体中的电荷中性问题，确定维持电荷中性所需的大尺度势电场，并确定电荷中性要求尾部等离子体和电离层之间交换电子的程度。＊＊＊

9312467 Ashour-Abdalla The proposed theoretical investigation is to calculate electron distributions in the geomagnetic tail to the Earth's magnetosphere and to evaluate the local and global problem of charge neutrality between electrons and ions. Although the dynamics of ions in the magnetotail has been the subject of extensive theoretical investigations using single particle orbit calculations, hybrid simulations, and magnetohydrodynamic fluid simulations, electron dynamics have been virtually ignored. Yet, the most fundamental aspect of a plasma - the establishment and maintenance of charge neutrality - depends on electron behavior. Some electrons move at high speeds and rapidly traverse large volumes of space; the establishment of local charge neutrality depends on both the global sources and sinks of electrons and the large scale structure of the electric and magnetic fields in the tail. Until now, no scientific methodology has existed capable of addressing global transport and calculating the local distributions of electrons in the tail. In the proposed large scale kinetics approach, starting from various source regions, electrons will be allowed to propagate throughout the entire volume of the magnetotail along trajectories which are determined using model electromagnetic fields to represent the tail configuration. The local electron distribution function will be calculated by summing the contributions of each trajectory passing through the local spatial region, and the electron density will be compared to the local ion density (which is similarly calculated by the large scale kinetics technique) to determine the extent of charge neutrality violation. Parallel electric fields will be added to the electromagnetic field model, and will be adjusted to obtain the closet reasonable balance between electron and ion charge densities. The potential significance of this proposed is profound in that, with its success we could for the first time directly asses s the problem of charge neutrality in a space plasma, determine the large scale potential electric fields required to maintain charge neutrality, and establish the extent to which charge neutrality demands the exchange of electrons between the tail plasma and the ionosphere. ***