Drift turbulence, particle transport, and anomalous dissipation at the reconnecting magnetopause

Journal Article · 28 May 2018 · Physics of Plasmas

DOI: https://doi.org/10.1063/1.5027086 · OSTI ID:1477696

Le, A.  ^[1]; Daughton, W. ^[1]; Ohia, O. ^[1]; Chen, L. -J. ^[2]; Liu, Y. -H.  ^[3]; Wang, S.  ^[2]; Nystrom, W. D. ^[1]; Bird, R. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of Maryland, College Park, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
3. Dartmouth College, Hanover, NH (United States)

Here, using fully kinetic 3D simulations, the reconnection dynamics of asymmetric current sheets are examined at the Earth's magnetopause. The plasma parameters are selected to model MMS magnetopause diffusion region crossings with guide fields of 0.1, 0.4, and 1 of the reconnecting magnetosheath field. In each case, strong drift-wave fluctuations are observed in the lower-hybrid frequency range at the steep density gradient across the magnetospheric separatrix. These fluctuations give rise to cross-field electron particle transport. In addition, this turbulent mixing leads to significantly enhanced electron parallel heating in comparison to 2D simulations. We study three different methods of quantifying the anomalous dissipation produced by the drift fluctuations, based on spatial averaging, temporal averaging, and temporal averaging followed by integrating along magnetic field lines. A comparison of different methods reveals complications in identifying and measuring the anomalous dissipation. Nevertheless, the anomalous dissipation from short wavelength drift fluctuations appears weak for each case, and the reconnection rates observed in 3D are nearly the same as in 2D models. Finally, the 3D simulations feature a number of interesting new features that are consistent with recent MMS observations, including cold beams of magnetosheath electrons that penetrate into the hotter magnetospheric inflow, the related observation of decreasing temperature in regions of increasing total density, and an effective turbulent diffusion coefficient that agrees with predictions from quasi-linear theory.

• Research Organization: Dartmouth College, Hanover, NH (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
• Sponsoring Organization: LANL Laboratory Directed Research and Development (LDRD) Program; National Aeronautics and Space Administration (NASA) (United States); USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1477696
• Report Number(s): LA-UR--18-21459
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 25; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English