Abstract
Abstract. The Earth's magnetosphere provides an excellent laboratory for magnetic reconnection research. In particular, the magnetotail current sheet that is formed between the interface of the similar Northern and Southern Hemispheres of the magnetotail provides a relatively stable symmetric reconnection configuration that can be used to study basic aspects of the reconnection process. Of particular importance is the manner in which electrons are processed by the reconnection. Simulations and satellite data analyses of the ion diffusion region have suggested that the fluxes of electrons in the inflow regions of reconnection are greater in the directions parallel and anti-parallel to the magnetic field (field-aligned) whereas the electron flux in the outflow region is distributed more isotropically. However, this has only been studied experimentally on a case-by-case basis. In this paper, we investigate this claim by analyzing the degree of bulk electron field alignment in the outflow and inflow regions during encounters of the magnetic reconnection ion diffusion region by the Cluster spacecraft in the years 2001–2006. We demonstrate that while the median electron flux in the inflow region is indeed more field aligned than in the outflow region during some ion diffusion region encounters, the variation of the signature across events is so large that it cannot be said to be a general feature of magnetic reconnection in the Earth's magnetotail.
Highlights
Magnetic reconnection is a plasma process where magnetic energy is converted into particle energy and the magnetic field topology is changed (Vasyliunas, 1975)
It has previously been reported that the electron flux in the magnetic reconnection inflow region is predominantly aligned with the magnetic field, while in the outflow region the bulk electron direction movement is more isotropic (Nagai et al, 2001; Egedal et al, 2005; Chen et al, 2008; Egedal et al, 2010)
We have tested the degree of electron field alignment in the outflow and inflow regions of 21 ion diffusion regions
Summary
Magnetic reconnection is a plasma process where magnetic energy is converted into particle energy and the magnetic field topology is changed (Vasyliunas, 1975). The inflow region signatures considered were: (1) no observations of high velocity ion outflow, (2) the spacecraft situated inside the ion diffusion region where E + vi × B = 0, (3) no crossing of the neutral sheet (change of Bx polarity) during the time interval and (4) the location of the spacecraft outside of the separatrix region Another possible inflow signature arises from the fact that the still-magnetized electrons are convecting at the E ×B velocity in the Z direction due to the reconnection electric field Ey. the low resolution of the Cluster electron velocity measurements (often at 10s of seconds or more) did not allow any useful comparisons.
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