The effect of variations in the magnetic field direction from turbulence on kinetic-scale instabilities
The effect of variations in the magnetic field direction from turbulence on kinetic-scale instabilities
复制标题
湍流引起的磁场方向变化对动力学尺度不稳定性的影响
DOI：
10.1051/0004-6361/202345965
复制
发表时间：
2023
影响因子：
6.5
通讯作者：
Isenberg, Philip A.
中科院分区：
文献类型：
--
作者：
Opie, Simon;Verscharen, Daniel;Chen, Christopher H.;Owen, Christopher J.;Isenberg, Philip A.
在太阳风的动力学尺度上，不稳定性将能量从粒子转移到电磁场的波动中，同时将等离子体条件恢复到热力学平衡。我们研究了在惯性范围的小尺度末端的背景湍流波动和动力学不稳定性之间的相互作用，以降低质子温度的各向异性。我们分析了来自太阳轨道飞行器任务的现场太阳风观测，以开发磁场方向变化的测量方法。我们发现，足以引起等离子体微不稳定的非平衡条件与变异性水平升高相吻合。我们表明，在温度各向异性驱动的不稳定性增长的不稳定区域，我们对磁场波动的测量是非遍历的。我们得出结论，湍流作用和不稳定性之间的竞争在太阳风质子尺度能量学的调节中起着重要作用。这种竞争不仅取决于磁场的可变性，而且取决于等离子体在非平衡条件下的空间持久性。
At kinetic scales in the solar wind, instabilities transfer energy from particles to fluctuations in the electromagnetic fields while restoring plasma conditions towards thermodynamic equilibrium. We investigate the interplay between background turbulent fluctuations at the small-scale end of the inertial range and kinetic instabilities acting to reduce proton temperature anisotropy. We analyse in situ solar wind observations from the Solar Orbiter mission to develop a measure for variability in the magnetic field direction. We find that non-equilibrium conditions sufficient to cause micro-instabilities in the plasma coincide with elevated levels of variability. We show that our measure for the fluctuations in the magnetic field is non-ergodic in regions unstable to the growth of temperature anisotropy-driven instabilities. We conclude that the competition between the action of the turbulence and the instabilities plays a significant role in the regulation of the proton-scale energetics of the solar wind. This competition depends not only on the variability of the magnetic field but also on the spatial persistence of the plasma in non-equilibrium conditions.