Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fluctuation Dynamo in a Collisionless, Weakly Magnetized Plasma   Results from a numerical study of fluctuation dynamo in a collisionless,
weakly magnetized plasma are presented. The key difference between this dynamo
and its magnetohydrodynamic (MHD) counterpart is the adiabatic production of
magnetic-field-aligned pressure anisotropy by the amplification of a weak seed
field. This in turn drives kinetic instabilities on the ion-Larmor
scale---namely, firehose and mirror---which sever the adiabatic link between
the thermal and magnetic pressures, thereby allowing the dynamo to proceed.
After an initial phase of rapid growth driven by these instabilities, the
magnetic energy grows exponentially and exhibits a $k^{3/2}$ spectrum that
peaks near the resistive scale, similar to the large-magnetic-Prandtl-number
($\mathrm{Pm}\gg{1}$) MHD dynamo. The magnetic field self-organizes into a
folded-sheet topology, with direction reversals at the resistive scale and
field lines curved at the parallel scale of the flow. The effective
$\mathrm{Pm}$ is determined by whether the ion-Larmor scale is above or below
the field-reversing scale: in the former case, particles undergo Bohm-like
diffusion; in the latter case, particles scatter primarily off firehose
fluctuations residing at the ends of the magnetic folds, and the viscosity
becomes anisotropic. The magnetic field ultimately saturates at dynamical
strengths, with its spectral peak migrating towards larger scales. This
feature, along with an anti-correlation of magnetic-field strength and
field-line curvature and a gradual thinning of magnetic sheets into ribbons,
resemble the saturated state of the large-$\mathrm{Pm}$ dynamo, the primary
differences manifesting in firehose/mirror-unstable regions. These results have
implications for magnetic-field growth in the weakly collisional intracluster
medium of galaxy clusters.

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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph