1. Inferring the Magnetotail reconnection model from its magnetic products
Authors: S. Beyene1, C.J. Owen1, A.P. Walsh1, A.N. Fazakerley1, E. Lucek2, I. Dandouras3
1Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, RH5 6NT, UK
2Space and Atmospheric Physics, Imperial College London, SW7 2BZ, UK 3Centre d’Etude Spatiale des Rayonnements, Toulouse, France

2. The details of magnetic reconnection are not fully known.
Motivation
The details of magnetic reconnection are not fully known.
Reconnection creates magnetic structures which have been observed.
There are two competing models each predicting a magnetic structure (MXR and time dependant reconnection).
By studying the magnetic structure, the correct model can be inferred (whether it be either, a hybrid or neither).
We seek a crossing when spacecraft separation was similar to the size of these structures (~1.5RE, 2006 Tail Season, spacecraft 10,000km separation).
Varied ‘impact parameters’ (unitless radial distance) one spacecraft outside, one near the centre and the other two at various distances inside the magnetic structure. 2 2

3. Multiple X-Line Reconnection
Distance Dependant
Multiple X lines present
Flux ropes created between X-Lines
Fastest X-Line
Bipolar signature 3 3

4. Time Dependant Reconnection
"from Kiehas et al., 2009"
One X Line, two flux bulges
MHD waves propagate from X-Line
outflow tear drop shaped
Uneven bipolar, plasma in second half 4 4

5. Data Search
The Cluster data was searched to find a magnetic structure (in the tail) to analyse in the hopes of inferring the reconnection model. 5 5

6. Orbit Plot Relative to C3
In the Magnetotail
Tetrahedral formation
C3 far south 6 6

7. Spacecraft located in the magnetolobe
Small, long lasting bipolar signature (compared to C1 and C4)
Small increase in energy, density, pressure, temperature and velocity
Event is consistent with a TCR (Travelling Compression Region) 7 7

8. Bipolar signature seen in Bz as well as a dip in Bx
0 and 180 degree pitch angle particles see a greater increase in DEF 8 8

9. 9 9

10. -ve Bx indicating a crossing of the neutral sheet
Spacecraft crosses from plasma sheet to structure and back out into the plasma sheet
No bipolar signature
-ve Bx indicating a crossing of the neutral sheet
Can be explained by the movement of the plasma sheet or by a magnetic structure 10 10

11. Possible Interpretations: Flux Rope11 11

12. Possible Interpretations: Flux Bulge12 12

13. Possible Interpretations: Wave13 13

14. Summary
Magnetic structures were searched for in the Cluster dataset, at a time when the spacecraft separation was close to the size of the magnetic structure.
The event studied had the spacecraft at significantly different impact parameters.
By analysing the structure, the reconnection model can be studied.
Two reconnection models exist, both predicting different magnetic structures.
By comparing the observed magnetic structure to the two theoretical magnetic structures, the reconnection model can be inferred
Observed event more consistent with a plasma sheet wave