Strong current sheet at a magnetosheath jet: kinetic structure and electron acceleration
Monday, 10 July 2017: 15:20
Furong Room (Cynn Hotel)
Elin Eriksson1,2, Andris Vaivads1, Yuri V Khotyaintsev1, Emiliya Yordanova1, Heli Hietala3, Mats Andre1, Levon A Avanov4, John Dorelli5, Daniel J Gershman6, Barbara L Giles4, Benoit Lavraud7, William R Paterson4, Craig J Pollock8, Yoshifumi Saito9, Werner Magnes10, Christopher T Russell11, Roy B Torbert12, Robert Ergun13, Per-Arne Lindqvist14 and James L Burch15, (1)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (2)Uppsala University, Uppsala, Sweden, (3)University of California Los Angeles, Los Angeles, CA, United States, (4)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (5)NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, United States, (6)University of Maryland College Park, College Park, MD, United States, (7)IRAP, Toulouse, France, (8)NASA Goddard Space Flight Center, Heliophysics Sci. Div., Greenbelt, MD, United States, (9)ISAS Institute of Space and Astronautical Science, Kanagawa, Japan, (10)Space Research Institute, Austrian Academy of Sciences, Graz, Austria, (11)University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (12)University of New Hampshire Main Campus, Durham, NH, United States, (13)Univ Colorado, Boulder, CO, United States, (14)KTH Royal Institute of Technology, Stockholm, Sweden, (15)Southwest Research Institute, San Antonio, TX, United States
Abstract:
Localized kinetic-scale regions of strong current are believed to play an important role in plasma thermalization and particle acceleration in turbulent plasmas. Thin current sheets have been observed before in the turbulent magnetosheath using Cluster data with different methods. The thin current sheets found by Cluster have been obtained with spacecraft separation comparable to ion scales. However, the particle instrumentation is not sufficient to resolve the physical processes of particle acceleration and plasma thermalization in detail at thin current sheets. Now we use MMS (Magnetospheric Multiscale) data to observe these processes. The MMS separation is comparable to the ion scale and the data from the particle instruments has a sufficient resolution during burst mode to resolve in detail these processes for our event.
We present a detailed study of a strong localized current, 4900 nA m-2, located at a fast plasma jet observed in the magnetosheath downstream of a quasi-parallel shock. The shape of the current region is in the form of a sheet, but also shows strong variations on the scale of the spacecraft separation. The thickness of the current region is ~ 3 ion inertial lengths and forms at a boundary separating magnetosheath-like and solar wind-like plasmas. The current sheet has a high normal magnetic field component indicating that the regions at the different sides of the current sheet are magnetically connected. We suggest that the current sheet is forming due to high velocity shears associated with the jet. Inside the current sheet we observe local electron acceleration, producing electron beams, along the magnetic field. This suggest that electron beams observed in the magnetosheath do not have to originate from the bow shock, but can also be generated locally inside the magnetosheath.
