Energy Conversion and Electron Acceleration in the Magnetopause Reconnection Diffusion Region

Data are analyzed from a Magnetospheric Multiscale encounter with a dayside magnetopause reconnection region on 29 December 2016. The uniqueness of the event stems from the small (~7 km) average spacecraft separation and the sequential sampling of an electron diffusion region with electron crescent distributions. We quantitatively investigate the earthward acceleration of magnetosheath electrons through the in‐plane null by the polarization electric field EN that points radially outward from the magnetopause. The results compare favorably with previous plasma simulations with one important difference that the reconnection electric field (EM) extends throughout the region of strong EN so that both fields energize electrons in the same region. This acceleration is quantified here for the first time. As the spacecraft penetrate deeper into the region of enhanced EN, the magnetic reflection of lower‐energy electrons produces a thinner crescent.

[1]  C. Russell,et al.  How Accurately Can We Measure the Reconnection Rate E M for the MMS Diffusion Region Event of 11 July 2017? , 2018, Journal of geophysical research. Space physics.

[2]  R. Denton,et al.  Localized Oscillatory Energy Conversion in Magnetopause Reconnection , 2017, 1712.05697.

[3]  P. Cassak,et al.  Localized and Intense Energy Conversion in the Diffusion Region of Asymmetric Magnetic Reconnection , 2017, Geophysical Research Letters.

[4]  C. Russell,et al.  Electron Crescent Distributions as a Manifestation of Diamagnetic Drift in an Electron‐Scale Current Sheet: Magnetospheric Multiscale Observations Using New 7.5 ms Fast Plasma Investigation Moments , 2017, Geophysical Research Letters.

[5]  B. Anderson,et al.  The Effect of a Guide Field on Local Energy Conversion During Asymmetric Magnetic Reconnection: Particle‐in‐Cell Simulations , 2017 .

[6]  M. Hesse,et al.  The effect of reconnection electric field on crescent and U-shaped distribution functions in asymmetric reconnection with no guide field , 2017 .

[7]  C. Russell,et al.  The Effect of a Guide Field on Local Energy Conversion During Asymmetric Magnetic Reconnection: MMS Observations , 2017, 1706.08404.

[8]  P. Lindqvist,et al.  MMS observations of whistler waves in electron diffusion region , 2017 .

[9]  J. Burch,et al.  Magnetic reconnection at the dayside magnetopause: Advances with MMS , 2016 .

[10]  P. Lindqvist,et al.  Estimates of terms in Ohm's law during an encounter with an electron diffusion region , 2016 .

[11]  R. Torbert,et al.  Motion of the MMS spacecraft relative to the magnetic reconnection structure observed on 16 October 2015 at 1307 UT , 2016 .

[12]  U. Gliese,et al.  Fast Plasma Investigation for Magnetospheric Multiscale , 2016 .

[13]  J. B. Blake,et al.  Electron-scale measurements of magnetic reconnection in space , 2016, Science.

[14]  N. Bessho,et al.  Electron distribution functions in the diffusion region of asymmetric magnetic reconnection , 2016 .

[15]  Thomas E. Moore,et al.  Magnetospheric Multiscale Overview and Science Objectives , 2016 .

[16]  M. Fujimoto,et al.  Kinetic signatures of the region surrounding the X line in asymmetric (magnetopause) reconnection , 2016, 1602.00779.

[17]  David G. Sibeck,et al.  On the electron diffusion region in planar, asymmetric, systems , 2014 .

[18]  P. Cassak,et al.  Asymmetric Magnetic Reconnection: General Theory and Collisional Simulations , 2007 .

[19]  A. Vaivads,et al.  Structure of the magnetic reconnection diffusion region from four-spacecraft observations. , 2004, Physical review letters.

[20]  A. Khrabrov,et al.  Error estimates for minimum variance analysis , 1998 .

[21]  D. Willis.  Structure of the magnetopause , 1971 .