Dissipation and particle acceleration at intermittent structures with velocity and magnetic shear: Interaction of Kelvin-Helmholtz and Drift-Kink instabilities
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| Format: | Preprint |
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2025
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| _version_ | 1866908609614446592 |
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| author | Tsung, Tsun Hin Navin Werner, Gregory R. Uzdensky, Dmitri A. Begelman, Mitchell C. |
| author_facet | Tsung, Tsun Hin Navin Werner, Gregory R. Uzdensky, Dmitri A. Begelman, Mitchell C. |
| contents | We present two-dimensional (2D) particle-in-cell simulations of a magnetized, collisionless, relativistic pair plasma subjected to combined velocity and magnetic-field shear, a scenario typical at intermittent structures in plasma turbulence. We create conditions where only the Kelvin-Helmholtz (KH) and Drift-Kink (DK) instabilities can develop, while tearing modes are forbidden. The interaction of DKI and KHI generates qualitatively new structures, marked by a thickened shear layer with very weak electromagnetic field, modulated by KH vortices. Over a range of moderately strong velocity shears explored, the interaction of DKI and KHI results in a significant enhancement of dissipation over cases with only velocity shear or only magnetic shear. Moreover, we observe a new and efficient way of particle acceleration where particles are stochastically accelerated by the motional electric field exterior to the shear layer as they meander in an S-shaped pattern in and out of it. This process takes advantage of the bent geometry of the shear layer caused by the DK-KHI interaction and is responsible for most of the highest-energy particles produced in our simulations. These results further our understanding of dissipation and particle acceleration at intermittent structures, which are present in plasma turbulence across a wide range of astrophysical contexts such as in AGN jet sheaths, potentially relevant to limb-brightened emission, etc., and highlight the sensitivity of dissipation to multiple interacting instabilities, thus providing a strong motivation for further studies of their nonlinear interaction at the kinetic level. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_21187 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Dissipation and particle acceleration at intermittent structures with velocity and magnetic shear: Interaction of Kelvin-Helmholtz and Drift-Kink instabilities Tsung, Tsun Hin Navin Werner, Gregory R. Uzdensky, Dmitri A. Begelman, Mitchell C. High Energy Astrophysical Phenomena Plasma Physics We present two-dimensional (2D) particle-in-cell simulations of a magnetized, collisionless, relativistic pair plasma subjected to combined velocity and magnetic-field shear, a scenario typical at intermittent structures in plasma turbulence. We create conditions where only the Kelvin-Helmholtz (KH) and Drift-Kink (DK) instabilities can develop, while tearing modes are forbidden. The interaction of DKI and KHI generates qualitatively new structures, marked by a thickened shear layer with very weak electromagnetic field, modulated by KH vortices. Over a range of moderately strong velocity shears explored, the interaction of DKI and KHI results in a significant enhancement of dissipation over cases with only velocity shear or only magnetic shear. Moreover, we observe a new and efficient way of particle acceleration where particles are stochastically accelerated by the motional electric field exterior to the shear layer as they meander in an S-shaped pattern in and out of it. This process takes advantage of the bent geometry of the shear layer caused by the DK-KHI interaction and is responsible for most of the highest-energy particles produced in our simulations. These results further our understanding of dissipation and particle acceleration at intermittent structures, which are present in plasma turbulence across a wide range of astrophysical contexts such as in AGN jet sheaths, potentially relevant to limb-brightened emission, etc., and highlight the sensitivity of dissipation to multiple interacting instabilities, thus providing a strong motivation for further studies of their nonlinear interaction at the kinetic level. |
| title | Dissipation and particle acceleration at intermittent structures with velocity and magnetic shear: Interaction of Kelvin-Helmholtz and Drift-Kink instabilities |
| topic | High Energy Astrophysical Phenomena Plasma Physics |
| url | https://arxiv.org/abs/2510.21187 |