Genestreti, KJ;
Burch, JL;
Cassak, PA;
Torbert, RB;
Ergun, RE;
Varsani, A;
Phan, TD;
... Allen, RC; + view all
(2017)
The effect of a guide field on local energy conversion during asymmetric magnetic reconnection: MMS observations.
Journal of Geophysical Research: Space Physics
, 122
(11)
11,342-11,353.
10.1002/2017ja024247.
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Abstract
We compare case studies of Magnetospheric Multiscale (MMS)-observed magnetopause electron diffusion regions (EDRs) to determine how the rate of work done by the electric field, inline image varies with shear angle. We analyze MMS-observed EDR event with a guide field approximately the same size as the magnetosheath reconnecting field, which occurred on 8 December 2015. We find that inline image was largest and positive near the magnetic field reversal point, though patchy lower-amplitude inline image also occurred on the magnetosphere-side EDR near the electron-crescent point. The current associated with the large inline image near the X-point was carried by electrons with a velocity distribution function (VDF) resembling the magnetosheath inflow, shifted in the −v∥ direction. At the magnetosphere-side EDR, the current was carried by electrons with a crescent-like VDF. We compare this 8 December event to 10 other EDRs with different guide field strengths. The dual-region inline image was observed in three other moderate-shear EDR events, whereas three high-shear events had a strong positive inline image near the electron-crescent point and one low-shear event had a strong positive inline image only near the BL=0 point. The dual-region inline image was seen for one of three “intermediate"-shear EDRs with guide fields of ∼0.2–0.3. We propose a physical relationship between the shear angle and mode of energy conversion where (a) a guide field provides an efficient mechanism for carrying a current at the field reversal point (streaming) and (b) a guide field may limit the formation of crescent eVDFs, limiting the current carried near the stagnation point.
| Type: | Article |
|---|---|
| Title: | The effect of a guide field on local energy conversion during asymmetric magnetic reconnection: MMS observations |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/2017ja024247 |
| Publisher version: | https://doi.org/10.1002/2017ja024247 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Magnetic Reconnection; Magnetopause; MMS |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10027979 |
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