论文标题
空间和天体物理等离子体中“电流介导的”湍流状态的证据
Evidence of a "current-mediated" turbulent regime in space and astrophysical plasmas
论文作者
论文摘要
湍流能量级联对于空间和天体物理等离子体中磁水动力学尺度以下如何发展是一个主要的开放问题。在这里，我们测量了Parker太阳探针在太阳附近的观测值以及血浆湍流的最新数值模拟中的磁波动的功率谱。两者都揭示了斜坡与$ -11/3 $兼容的幂律行为，比离子特性尺度小，比太阳风和地球的磁石中通常观察到的较高。我们通过开发一个简单的两流体模型来解释这种行为，该模型不需要任何动力学过程或电子惯性效应。尽管动力学是由磁场通过电流密度驱动的，但它的特征是离子动能对亚离子尺度的总湍流能量级联反应的显着贡献。我们预计该制度可能与一类低β等离子体有关，例如太阳能电晕，非宽容的磁化喷气机和磁盘以及实验室等离子体。
How the turbulent energy cascade develops below the magnetohydrodynamic scales in space and astrophysical plasmas is a major open question. Here, we measure the power spectrum of magnetic fluctuations in Parker Solar Probe's observations close to the Sun and in state-of-the-art numerical simulations of plasma turbulence. Both reveal a power-law behavior with a slope compatible with $-11/3$ at scales smaller than the ion characteristic scales, steeper than what is typically observed in the solar wind and in the Earth's magnetosheath. We explain such behavior by developing a simple two-fluid model which does not require any kinetic processes nor electron-inertia effects. This is characterized by a significant contribution of the ion kinetic energy to the total turbulent energy cascade at sub-ion scales, although the dynamics is driven by the magnetic field through the current density. We expect that this regime may be relevant for a broad class of low-beta plasmas, e.g. the solar corona, non-relativistic magnetized jets and disks, and laboratory plasmas.
