Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Double layer electric fields aiding the production of energetic flat-top
  distributions and superthermal electrons within the exhausts from magnetic
  reconnection   Using a kinetic simulation of magnetic reconnection it was recently shown
that magnetic-field-aligned electric fields (E||) can be present over large
spatial scales in reconnection exhausts. The largest values of E|| are observed
within double layers. The existence of double layers in the Earth's
magnetosphere is well documented. In our simulation their formation is
triggered by large parallel streaming of electrons into the reconnection
region. These parallel electron fluxes are required for maintaining
quasi-neutrality of the reconnection region and increase with decreasing values
of the normalized electron pressure upstream of the reconnection region. A
threshold normalized pressure is derived for strong double layers to develop.
We also document how the electron confinement, provided in part by the
structure in E||, allows sustained energization by perpendicular electric
fields. The energization is a consequence of the confined electrons' chaotic
orbital motion that includes drifts aligned with the reconnection electric
field. The level of energization is proportional to the initial particle energy
and therefore is enhanced by the initial energy boost of the acceleration
potential, acquired by electrons entering the region. The mechanism is
effective in an extended region of the reconnection exhaust allowing for the
generation of superthermal electrons in reconnection scenarios, including those
with only a single x-line. An expression for the phase-space distribution of
the superthermal electrons is derived, providing an accurate match to the
kinetic simulation results. The numerical and analytical results agree with
detailed spacecraft observations recorded during reconnection events in the
Earth's magnetotail.

1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph