具有速度剪切和磁剪切的天体物理喷流中的耗散与粒子加速：Kelvin-Helmholtz不稳定性与Drift-Kink不稳定性的相互作用
Dissipation and particle acceleration in astrophysical jets with velocity and magnetic shear: Interaction of Kelvin-Helmholtz and Drift-Kink Instabilities
AI总结：
通过二维PIC模拟研究相对论对等离子体中KH与DK不稳定性的耦合，发现其破坏猫眼涡旋、增强耗散并驱动高效非热粒子加速。
摘要：
我们给出了磁化、无碰撞、相对论性对等离子体在同时受到速度剪切和磁场剪切作用时的二维particle-in-cell模拟，这一场景常见于天体物理黑洞喷流—风边界。我们构造了只允许Kelvin-Helmholtz（KH）不稳定性和Drift-Kink（DK）不稳定性发展、而禁止撕裂模的条件。结果发现，DKI能够有效破坏KHI产生的猫眼涡旋，在DK时间尺度上形成湍流剪切层。与仅有速度剪切或仅有磁剪切的情形相比，这种相互作用使耗散显著增强。此外，我们观察到高效的非热粒子加速，其原因是不稳定性驱动的电场与剪切界面附近粒子的类Speiser运动发生对齐。本研究强调耗散对多种同时发生的不稳定性的敏感性，从而为进一步在动理学层面研究其非线性相互作用提供了有力动机。
英文摘要：
We present 2D particle-in-cell simulations of a magnetized, collisionless, relativistic pair plasma subjected to combined velocity and magnetic-field shear, a scenario typical for astrophysical black-hole jet-wind boundaries. We create conditions where only the Kelvin-Helmholtz (KH) and Drift-Kink (DK) instabilities can develop, while tearing modes are forbidden. We find that DKI can effectively disrupt the cats-eye vortices generated by KHI, creating a turbulent shear layer on the DK timescale. This interplay leads to a significant enhancement of dissipation over cases with only velocity shear or only magnetic shear. Moreover, we observe efficient nonthermal particle acceleration caused by the alignment of the instability-driven electric fields with Speiser-like motion of particles close to the shear interface. This study highlights the sensitivity of dissipation to multiple simultaneous instabilities, thus providing a strong motivation for further studies of their nonlinear interaction at the kinetic level.
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