Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry, CV4 7AL, United Kingdom.
Phys Rev Lett. 2012 Jun 29;108(26):261103. doi: 10.1103/PhysRevLett.108.261103. Epub 2012 Jun 26.
A connection between kinetic processes and intermittent turbulence is observed in the solar wind plasma using measurements from the Wind spacecraft at 1 A.U. In particular, kinetic effects such as temperature anisotropy and plasma heating are concentrated near coherent structures, such as current sheets, which are nonuniformly distributed in space. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. The inhomogeneous heating in these regions, which is present in both the magnetic field parallel and perpendicular temperature components, results in protons at least 3-4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is not sufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures.
在日地空间 1 个天文单位处利用 Wind 卫星的测量数据,在太阳风等离子体中观察到动力过程与间歇性湍流之间的关联。特别地,诸如各向异性温度和等离子体加热等动力效应集中在非均匀分布于空间的相干结构(如电流片)附近。此外,这些相干结构优先出现在对镜和火环不稳定性不稳定的等离子体中。在磁场平行和垂直温度分量中都存在的这些区域中的不均匀加热,导致质子比在典型稳定等离子体条件下至少热 3-4 倍。这些结果提供了对湍流状态下动力过程的新理解,在该状态下,线性 Vlasov 理论不足以解释在非高斯结构附近运行的不均匀等离子体动力学。