The boundaries identification of Kelvin-Helmholtz vortices in observational data has been addressed by searching for single-spacecraft small-scale signatures. A recent hybrid Vlasov-Maxwell simulation of Kelvin-Helmholtz instability has pointed out clear kinetic features which uniquely characterize the vortex during both the nonlinear and turbulent stage of the instability. We compare the simulation results with \textit{in situ} observations of Kelvin-Helmholtz vortices by the Magnetospheric MultiScale satellites. We find good agreement between simulation and observations. In particular, the edges of the vortex are associated with strong current sheets, while the center is characterized by a low value for the magnitude of the total current density and strong deviation of the ion distribution function from a Maxwellian distribution. We also find a significant temperature anisotropy parallel to the magnetic field inside the vortex region and strong agyrotropies near the edges. We suggest that these kinetic features can be useful for the identification of Kelvin-Helmholtz vortices in \textit{in situ} data.
Plasma Mixing Driven by the Collisionless Kelvin-Helmholtz Instability: Insights from fully kinetic simulation and density-based diagnostics
KU Leuven(荷语鲁汶大学);Royal Belgian Institute for Space Aeronomy(比利时皇家空间空气动力学研究所);University of Wisconsin-Madison(威斯康星大学麦迪逊分校);National Research Council, CNR-ISTP(国家研究委员会等离子体科学与技术研究所);Observatoire Côte d’Azur, Université Côte d’Azur(蔚蓝海岸天文台,蔚蓝海岸大学);LPC2E, CNRS, Université d’Orléans(奥尔良大学CNRS LPC2E实验室)
Kelvin-Helmholtz vortices in the Martian +E hemisphere downstream of crustal magnetic anomalies
University of Science and Technology of China(中国科学技术大学);The University of Hong Kong(香港大学);National Space Science Center, Chinese Academy of Sciences(中国科学院国家空间科学中心);Harbin Institute of Technology, Shenzhen(哈尔滨工业大学(深圳));Space Research Institute, Austrian Academy of Sciences(奥地利科学院空间研究所)
Turbulence properties and kinetic signatures of electron in Kelvin-Helmholtz waves during a geomagnetic storm
University of Maryland College Park(马里兰大学帕克分校);NASA Goddard Space Flight Center(美国宇航局戈达德太空飞行中心);University of New Hampshire(新罕布什尔大学);Dartmouth College(达特茅斯学院);University of Maryland Baltimore(马里兰大学巴尔的摩分校)
Simultaneous Mars-orbit observations reveal Kelvin-Helmholtz instability-driven bulk atmospheric ion escape
Boston University(波士顿大学);Institute for Advanced Study, Princeton(普林斯顿高等研究院);Catholic University of America(美利坚天主教大学);NASA Goddard Space Flight Center(美国宇航局戈达德太空飞行中心);University of Iowa(爱荷华大学);University of Colorado(科罗拉多大学);University of California, Berkeley(加州大学伯克利分校)
Kelvin--Helmholtz instability in a cool solar jet in the framework of Hall magnetohydrodynamics: A case study
本文研究了沿轴向运动的圆柱形磁通管中的磁流体动力学(MHD)模发生Kelvin-Helmholtz(KH)不稳定的条件。本文从线性化的霍尔磁流体力学方程出发,对冷等离子体的实波数和复角波频率\textbf{/complex wave phase velocities},导出了磁流体力学模\textbf{obtained}的色散关系.色散方程在固定的输入参数和变化的$l_\mathrm{Hall}/a$比值下数值求解,其中$l_\mathrm{Hall} = c/ω_\mathrm{pi}$($c$是光速,$ω_\mathrm{pi}$是离子等离子体频率)和$a$是通量管半径。结果表明,磁流体动力学模式的稳定性取决于四个参数:磁通量管与其周围环境的密度差、内外磁场的比值、$l_\mathrm{Hall}/a$的比值和Alfvén马赫数\textbf{defined as the ratio of the tube axial velocity to Alfvén speed inside the flux tube}的值。研究发现,在高密度对比度下,当$l_\mathrm{Hall}/a$值较小时,在某一临界Alfvén马赫数(或等效的临界流速)下,扭折($m = 1$)模式会因KH不稳定性而变得不稳定,但阈值$l_\mathrm{Hall}/a$可以抑制KH不稳定性的发生。然而,在…