Plasma in Earth's magnetosheath rarely experiences interparticle collisions, so kinetic microinstabilities are thought to contribute to regulating the plasma thermodynamics. Instabilities excite waves and redistribute free energy in velocity space, reducing free energy in the velocity distribution function (VDF). Using 24 hr of data spread over 163 intervals of in situ magnetosheath observations by Magnetospheric Multiscale (MMS), we investigate signatures of energy conversion where the turbulent dynamics have locally distorted the VDFs into non-Maxwellian shapes, in the context of electron and ion temperature anisotropy driven instabilities. We find enhanced average energy conversion into the particles along instability boundaries, suggesting turbulence plays a role in redistributing free energy. In so doing, we quantify the energetics associated with unstable conditions for both species. This work provides insight into the open question of how specific plasma processes couple into the turbulent dynamics, ultimately leading to energy dissipation and particle energization in collisionless plasmas.

中文翻译：

---

与地球磁层中的动能微不稳定性相关的湍流能量转换


地球磁层中的等离子体很少经历粒子间碰撞，因此动力学微不稳定性被认为有助于调节等离子体热力学。不稳定性会激发波并在速度空间中重新分配自由能，从而减少速度分布函数 （VDF） 中的自由能。使用磁层多尺度 （MMS） 在 163 个原位磁层观测间隔中分布的 24 小时数据，我们研究了能量转换的特征，其中湍流动力学在电子和离子温度各向异性驱动的不稳定性的背景下将 VDF 局部扭曲成非麦克斯韦形状。我们发现沿不稳定边界向粒子的平均能量转换增强，这表明湍流在重新分配自由能中起作用。在此过程中，我们量化了与这两个物种的不稳定条件相关的能量学。这项工作深入探讨了特定等离子体过程如何耦合到湍流动力学中，最终导致无碰撞等离子体中的能量耗散和粒子能量化这一悬而未决的问题。