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

A C Rager; J C Dorelli; D J Gershman; V Uritsky; L A Avanov; R B Torbert; J L Burch; R E Ergun; J Egedal; C Schiff; J R Shuster; B L Giles; W R Paterson; C J Pollock; R J Strangeway; C T Russell; B Lavraud; V N Coffey; Y Saito

doi:10.1002/2017GL076260

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

Geophys Res Lett. 2018 Jan 28;45(2):578-584. doi: 10.1002/2017GL076260. Epub 2018 Jan 30.

Authors

A C Rager^{1

2}, J C Dorelli², D J Gershman², V Uritsky^{1

2}, L A Avanov^{2

3}, R B Torbert^{4

5}, J L Burch⁵, R E Ergun⁶, J Egedal⁷, C Schiff², J R Shuster^{2

3}, B L Giles², W R Paterson², C J Pollock⁸, R J Strangeway⁹, C T Russell⁹, B Lavraud¹⁰, V N Coffey¹¹, Y Saito¹²

Affiliations

¹ Department of Physics Catholic University of America Washington DC USA.
² NASA Goddard Space Flight Center Greenbelt MD USA.
³ Department of Astronomy University of Maryland College Park MD USA.
⁴ Department of Physics University of New Hampshire Durham NH USA.
⁵ Southwest Research Institute San Antonio TX USA.
⁶ Astrophysical and Planetary Sciences University of Colorado Boulder Boulder CO USA.
⁷ Department of Physics University of Wisconsin Madison WI USA.
⁸ Denali Scientific Healy AK USA.
⁹ Earth, Planetary, and Space Sciences University of California Los Angeles CA USA.
¹⁰ Research Institute in Astrophysics and Planetology Toulouse France.
¹¹ NASA Marshall Space Flight Center Huntsville AL USA.
¹² Institute for Space and Astronautical Science Sagamihara Japan.

Abstract

We report Magnetospheric Multiscale observations of electron pressure gradient electric fields near a magnetic reconnection diffusion region using a new technique for extracting 7.5 ms electron moments from the Fast Plasma Investigation. We find that the deviation of the perpendicular electron bulk velocity from E × B drift in the interval where the out-of-plane current density is increasing can be explained by the diamagnetic drift. In the interval where the out-of-plane current is transitioning to in-plane current, the electron momentum equation is not satisfied at 7.5 ms resolution.

Keywords: diamagnetic drift; reconnection.