High resolution kinetic simulations of collisionless plasma driven by shear show the development of turbulence characterized by dynamic coherent sheetlike current density structures spanning a range of scales down to electron scales. We present evidence that these structures are sites for heating and dissipation, and that stronger current structures signify higher dissipation rates. Evidently, kinetic scale plasma, like magnetohydrodynamics, becomes intermittent due to current sheet formation, leading to the expectation that heating and dissipation in astrophysical and space plasmas may be highly nonuniform and patchy.
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Article Synopsis
- Turbulence and magnetic reconnection are important nonlinear plasma phenomena that significantly affect energy transport in space and astrophysical plasmas.
- Recent high-resolution, multi-spacecraft observations have improved our understanding of their complex interactions, revealing how turbulence generates current sheets that can undergo reconnection.
- This paper reviews current knowledge on these interactions in collisionless plasmas, particularly in Earth's magnetosphere, highlighting findings from NASA's missions in key areas like the magnetosheath and magnetotail.
How magnetic reconnection is triggered or suppressed is an important outstanding problem. By considering pinching of a current sheet that has formed at non-equilibrium, we show that the background plasma beta is a major controlling factor in the onset and nature of magnetic reconnection. A high plasma beta inhibits a current sheet from pinching down to kinetic scales required for collisionless reconnection, while a low beta facilitates it.
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