Details

Autor(en) / Beteiligte

• Eastwood, J. P.
• Mistry, R.
• Phan, T. D.
• Schwartz, S. J.
• Ergun, R. E.
• Drake, J. F.
• Øieroset, M.
• Stawarz, J. E.
• Goldman, M. V.
• Haggerty, C.
• Shay, M. A.
• Burch, J. L.
• Gershman, D. J.
• Giles, B. L.
• Lindqvist, P. A.
• Torbert, R. B.
• Strangeway, R. J.
• Russell, C. T.

Titel

Guide Field Reconnection: Exhaust Structure and Heating

Ist Teil von

• Geophysical research letters, 2018-05, Vol.45 (10), p.4569-4577

Ort / Verlag

United States: Blackwell Publishing Ltd

Erscheinungsjahr

2018

Link zum Volltext

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Magnetospheric Multiscale observations are used to probe the structure and temperature profile of a guide field reconnection exhaust ~100 ion inertial lengths downstream from the X‐line in the Earth's magnetosheath. Asymmetric Hall electric and magnetic field signatures were detected, together with a density cavity confined near 1 edge of the exhaust and containing electron flow toward the X‐line. Electron holes were also detected both on the cavity edge and at the Hall magnetic field reversal. Predominantly parallel ion and electron heating was observed in the main exhaust, but within the cavity, electron cooling and enhanced parallel ion heating were found. This is explained in terms of the parallel electric field, which inhibits electron mixing within the cavity on newly reconnected field lines but accelerates ions. Consequently, guide field reconnection causes inhomogeneous changes in ion and electron temperature across the exhaust. Plain Language Summary Plasma heating and energization by magnetic reconnection is a fundamental process in space, solar, astrophysical, and planetary plasmas. Most reconnecting current sheets do not exhibit perfectly antialigned magnetic fields and a so‐called guide field is often present. Using new experimental data from NASA's Magnetospheric Multiscale mission, this article shows that far from the X‐line during guide field reconnection, the heating is substantially modified from the typically studied antiparallel case. More specifically, the new multipoint, high time resolution Magnetospheric Multiscale measurements of a guide field reconnection exhaust in the Earth's magnetosheath reveal inhomogenous ion and electron heating and cooling. This uncovers in new detail the structure of the exhaust, including predicted density cavity structure and electron holes, and indicates the importance of the parallel electric field. The results are important for the general understanding of reconnection heating and energization. The results will be of immediate and timely interest to the Geophysical Research Letters (GRL) community and beyond. Key Points A guide field reconnection exhaust was encountered by MMS in the magnetosheath ~100 ion inertial lengths downstream from the X‐line A density cavity forms on one edge of the exhaust with embedded electron jetting toward the X‐line and electron holes on the cavity edge The parallel electric field causes electron cooling and ion heating in the cavity and inhomogeneous temperature profiles across the exhaust