Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic field generation by the Weibel instability at temperature
  gradients in collisionless plasmas   The Weibel instability could be responsible for the generation of magnetic
fields in various objects such as gamma-ray bursts, jets from active galactic
nuclei, and clusters of galaxies. Using numerical simulations, the development
of the Weibel instability at a temperature gradient is studied. It is found
that current sheets are first generated at the gradient, and then they are
rounded off and turn into current filaments. During this process, return
currents are generated around the filaments and they prevent filaments from
merger. The magnetic fields around the filaments persist at least until
t~8000/\omega_p, where \omega_p is the plasma frequency, and it is very likely
that they survive for a much longer time.

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The categories of this paper are: funct-an
16
The categories of this paper are: stat
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an