The kinetic scale structure of the Plasma Sheet Boundary Layer: Implications of collisionless magnetic reconnection and first MMS observations

Thursday, 17 December 2015: 09:09
2018 (Moscone West)
John Dorelli1, Daniel J Gershman1, Levon A Avanov1, Craig J Pollock2, Barbara L Giles1, Rumi Nakamura3, Li-Jen Chen1, Roy B Torbert4, Ulrik Gliese1, Alexander C Barrie5, Matthew P Holland1, Michael O Chandler6, Victoria N Coffey6, Elizabeth MacDonald1, Chad Salo7, Charles Dickson8, Yoshifumi Saito9, Christopher T Russell10, Wolfgang Baumjohann11 and James L Burch12, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)NASA Goddard Space Flight Center, Heliophysics Sci. Div., Greenbelt, MD, United States, (3)Austrian Academy of Sciences, Vienna, Austria, (4)University of New Hampshire Main Campus, Durham, NH, United States, (5)NASA Goddard Space Flight Center, (SGT Inc.), Greenbelt, MD, United States, (6)NASA Marshall Space Flight Center, Huntsville, AL, United States, (7)Stellar Solutions, Chantilly, VA, United States, (8)AS and D, Inc., Beltsville, MD, United States, (9)ISAS Institute of Space and Astronautical Science, Kanagawa, Japan, (10)University of California Los Angeles, IGPP/EPSS, Los Angeles, CA, United States, (11)Austrian Academy of Sciences, Graz, Austria, (12)Southwest Research Institute, San Antonio, TX, United States
The relationship between magnetic reconnection and the Plasma Sheet Boundary Layer (PSBL) is still an open problem in magnetospheric physics. While one can understand observed PSBL velocity distributions on the basis of a simple steady state drift-kinetic model with prescribed electric and magnetic fields (e.g., Onsager et al. [1990,1991]), such models do not incorporate the kinetic scale dynamics at the reconnection site. For example, Shay et al. [2011] have argued that the out-of-plane quadrupole magnetic field pattern at the reconnection site can be viewed as an obliquely propagating kinetic Alfv\'{e}n wave with very large parallel group velocity, the implication being that the field-aligned current structure should quickly become global, though still confined to field lines connected to the ion diffusion region at the reconnection site. This raises the very interesting question: How would such a global wave structure appear in the PSBL on the kinetic scale? Here, we present some first observations of the PSBL by NASA's Magnetospheric Multiscale (MMS) mission where Fast Plasma Investigation (FPI) Burst Data (30 ms and 150 ms resolution for 3D electron and ion velocity distributions, respectively) is available during intervals where lower resolution (4.5 s) Fast Survey distributions showed evidence of connection to a remote reconnection site. This allows us to test for the first time whether the quadrupole magnetic field structure near the reconnection site -- a local structure already observed by previous spacecraft -- does indeed support a global field-aligned current pattern around the magnetic separatrix. We will also probe for the first time the electron kinetic scale sub-structure of the PSBL and compare with electron-scale features observed near the magnetic separatrix at the dayside magnetopause.