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MMS analysis of a dayside compressed magnetospheric separatrix in the presence of cold ions and a moderate guide field
  • +26
  • Mohammed BARAKA,
  • O Le Contel,
  • P Canu,
  • S W Alqeeq,
  • J Dargent,
  • A Beck,
  • G Cozzani,
  • A Retinò,
  • T Chust,
  • L Mirioni,
  • S Toledo-Redondo,
  • M Akhavan-Tafti,
  • R Bandyopadhyay,
  • A Chasapis,
  • C Norgren,
  • Y Khotyaintsev,
  • N Ahmadi,
  • H Y Wei,
  • D Fischer,
  • D J Gershman,
  • J L Burch,
  • R B Torbert,
  • B L Giles,
  • S A Fuselier,
  • R E Ergun,
  • P.-A Lindqvist,
  • C T Russell,
  • R J Strangeway,
  • K R Bromund
Mohammed BARAKA
Laboratoire de Physique des Plasmas

Corresponding Author:[email protected]

Author Profile
O Le Contel
Laboratoire de Physique des Plasmas
P Canu
Laboratoire de Physique des Plasmas
S W Alqeeq
Laboratoire de Physique des Plasmas
J Dargent
Laboratoire de Physique des Plasmas
A Beck
Laboratoire Leprince-Ringuet
G Cozzani
Department of Physics, University of Helsinki
A Retinò
Laboratoire de Physique des Plasmas
T Chust
Laboratoire de Physique des Plasmas
L Mirioni
Laboratoire de Physique des Plasmas
S Toledo-Redondo
Departamento Electromagnetismo y Electronica, Universidad de Murcia
M Akhavan-Tafti
Climate and Space Sciences and Engineering
R Bandyopadhyay
Department of Astrophysical Sciences, Princeton University
A Chasapis
Laboratory for Atmospheric and Space Physics, University of Colorado
C Norgren
Swedish Institute of Space Physics
Y Khotyaintsev
Swedish Institute of Space Physics
N Ahmadi
Laboratory for Atmospheric and Space Physics, University of Colorado
H Y Wei
Institute of Geophysics and Planetary Physics
D Fischer
Space Research Institute, Academy of Sciences
D J Gershman
NASA Goddard Space Flight Center
J L Burch
Southwest Research Institute
R B Torbert
Space Science Center, Department of Physics
B L Giles
NASA Goddard Space Flight Center
S A Fuselier
Southwest Research Institute
R E Ergun
Institute of Geophysics and Planetary Physics
P.-A Lindqvist
Space and Plasma Group, Royal Institute of Technology
C T Russell
Institute of Geophysics and Planetary Physics
R J Strangeway
Institute of Geophysics and Planetary Physics
K R Bromund
NASA Goddard Space Flight Center

Abstract

This study reports on a dayside magnetic reconnection event with a moderate guide field (0.4 times the reconnecting magnetic field) detected by the Magnetospheric Multiscale (MMS) mission. The spacecraft traversed the compressed magnetospheric separatrix, observing cold ions with densities up to 10 cm-3 and a large magnetosheath density up to 150 cm-3. We provide a detailed analysis of current densities, generalized Ohm’s law, and energy conversion processes in both the spacecraft (J.E) and the fluid (J.E’) frames during the separatrix crossing. The normal electric field is directed away from the separatrix due to the cold ion drift on the magnetosphere side and to the magnetosheath ion drift in the presence of a guide field in the exhaust region. In the spacecraft frame, energy transfers from the plasma to the fields (J.E≈J.E<0) due to the convective field associated with the earthward motion of the magnetopause and the ion diamagnetic current associated with the large density gradient. In the fluid frame, energy conversion reverses due to the magnetic field-aligned current density and electric field produced by the divergence of the electron pressure tensor (J.E’≈J.E’). Additionally, we give insights into the local changes in electromagnetic, bulk flow, and thermal energies. We show that flow and thermal energy variations of the plasma are mostly driven by the compressible term of the electron pressure strain at the separatrix.
03 Sep 2024Submitted to ESS Open Archive
09 Sep 2024Published in ESS Open Archive