论文标题

近似太阳风中的动力学尺度电流表:特性,依赖比例的特征和重新连接发作

Kinetic-scale current sheets in near-Sun solar wind: properties, scale-dependent features and reconnection onset

论文作者

Lotekar, A., Vasko, I. Y., Phan, T., Bale, S. D., Bowen, T. A., Halekas, J., Artemyev, A. V., Khotyaintsev, Yu., Mozer, F. S.

论文摘要

我们介绍了帕克太阳能探针在第一个围场左右观察到的11,200个质子动力学尺度电流板(CS)的统计分析。 CS厚度$λ$在几个到200公里的范围内,典型值约为30 km,而当前密度在0.1至10 \; $μ{\ rm a/m^2} $范围内,典型值约为0.7 \; $μ{\ $μ{\ rm rm a/m^2} $。这些CSS得益于73--290样品/s分辨率的磁场测量值解决。就质子惯性长度而言,$λ_{p} $,CS厚度$λ$的范围从$ 0.1 $到$10λ_{p} $,典型值约为2 $λ_{p} $。磁场幅度在CSS上没有显着变化,因此,电流密度由磁场对齐的分量支配。 CSS通常是不对称的,在CS边界处统计上不同的磁场幅度。 The current density is larger for smaller-scale CSs, $J_0\approx 0.15 \cdot (λ/100\;{\rm km})^{-0.76}$ $μ{\rm A/m^2}$, but does not statistically exceed the Alfvén current density $J_A$ corresponding to the ion-electron drift of local Alfvén speed. CSS表现出显着的比例依赖性电流密度和磁性剪切角,$ j_0/j_ {a} \大约0.17 \ cdot(λ/λ_{p})^{ - 0.67} $和$δθ\ $δθ\ yourtion(pairc}^{\ circ} \ ccirc} \ ccirc} \ ccirc} \ ccirc} \ ccict} \ c Cy/λ/λ_}基于这些观察结果和与1个AU的最新研究的比较,我们得出结论,近似太阳风中的质子动力学尺度CSS由湍流级联反应产生,并且它们会自动在参数范围内,在参数范围内,由于涡轮壳的底导致的底膜机制不会被降解机械抑制。

We present statistical analysis of 11,200 proton kinetic-scale current sheets (CS) observed by Parker Solar Probe during 10 days around the first perihelion. The CS thickness $λ$ is in the range from a few to 200 km with the typical value around 30 km, while current densities are in the range from 0.1 to 10\;$μ{\rm A/m^2}$ with the typical value around 0.7\;$μ{\rm A/m^2}$. These CSs are resolved thanks to magnetic field measurements at 73--290 Samples/s resolution. In terms of proton inertial length $λ_{p}$, the CS thickness $λ$ is in the range from about $0.1$ to $10λ_{p}$ with the typical value around 2$λ_{p}$. The magnetic field magnitude does not substantially vary across the CSs and, accordingly, the current density is dominated by the magnetic field-aligned component. The CSs are typically asymmetric with statistically different magnetic field magnitudes at the CS boundaries. The current density is larger for smaller-scale CSs, $J_0\approx 0.15 \cdot (λ/100\;{\rm km})^{-0.76}$ $μ{\rm A/m^2}$, but does not statistically exceed the Alfvén current density $J_A$ corresponding to the ion-electron drift of local Alfvén speed. The CSs exhibit remarkable scale-dependent current density and magnetic shear angles, $J_0/J_{A}\approx 0.17\cdot (λ/λ_{p})^{-0.67}$ and $Δθ\approx 21^{\circ}\cdot (λ/λ_{p})^{0.32}$. Based on these observations and comparison to recent studies at 1 AU, we conclude that proton kinetic-scale CSs in the near-Sun solar wind are produced by turbulence cascade and they are automatically in the parameter range, where reconnection is not suppressed by the diamagnetic mechanism, due to their geometry dictated by turbulence cascade.

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