标题： 平行螺线管电场在有导向磁场的2.5D衰减湍流中能量转换的作用 显示英文标题

标题： Role of Parallel Solenoidal Electric Field on Energy Conversion in 2.5D Decaying Turbulence with a Guide Magnetic Field

摘要： 我们对存在引导（垂直于平面）背景磁场的衰减湍流进行2.5D粒子-网格模拟。 扰动磁场最初由低波数（长波长）的傅里叶模式组成。 随着时间推移，电磁能以每单位体积的速率 ${\pp J}\cdot{\pp E}$ 转换为等离子体动能（整体流动+热能），其中电流密度为 ${\pp J}$ ，电场为 ${\pp E}$ 。 这种衰减湍流已知会演变为具有强烈间歇性等离子体电流的状态。 在这里，我们将电场分解为无旋分量， ${\pp E}_{\rm ir}$ 和无散度（散度为零）的分量， ${\pp E}_{\rm so}$ 。 ${\pp E}_{\rm ir}$ 与电荷分离有关，而 ${\pp J}\cdot{\pp E}_{\rm ir}$ 是离子和电子之间能量转移的速率，且等离子体动能几乎没有净变化。 因此，电磁能转化为等离子体动能的净速率主要由${\pp J}\cdot{\pp E}_{\rm so}$主导，在强引导磁场情况下，这主要涉及与总磁场${\pp B}$平行的成分${\pp E}_{\rm so,\parallel}$。我们研究了能量转移率{\bf J$_\parallel\cdot$E$_{so,\parallel}$}的空间分布的各种指标，这与磁重联有关，其中最好的是 1) 垂直平面电场与平面内磁场的比值，2) 非理想电场的垂直平面分量，3) 电流螺旋度估计的大小。 显示英文摘要

摘要： We perform 2.5D particle-in-cell simulations of decaying turbulence in the presence of a guide (out-of-plane) background magnetic field. The fluctuating magnetic field initially consists of Fourier modes at low wavenumbers (long wavelengths). With time, the electromagnetic energy is converted to plasma kinetic energy (bulk flow+thermal energy) at the rate per unit volume of ${\pp J}\cdot{\pp E}$ for current density ${\pp J}$ and electric field ${\pp E}$. Such decaying turbulence is well known to evolve toward a state with strongly intermittent plasma current. Here we decompose the electric field into components that are irrotational, ${\pp E}_{\rm ir}$, and solenoidal (divergence-free), ${\pp E}_{\rm so}$. ${\pp E}_{\rm ir}$ is associated with charge separation, and ${\pp J}\cdot{\pp E}_{\rm ir}$ is a rate of energy transfer between ions and electrons with little net change in plasma kinetic energy. Therefore, the net rate of conversion of electromagnetic energy to plasma kinetic energy is strongly dominated by ${\pp J}\cdot{\pp E}_{\rm so}$, and for a strong guide magnetic field, this mainly involves the component ${\pp E}_{\rm so,\parallel}$ parallel to the total magnetic field ${\pp B}$. We examine various indicators of the spatial distribution of the energy transfer rate {\bf J$_\parallel\cdot$E$_{so,\parallel}$}, which relates to magnetic reconnection, the best of which are 1) the ratio of the out-of-plane electric field to the in-plane magnetic field, 2) the out-of-plane component of the non-ideal electric field, and 3) the magnitude of the estimate of current helicity.