Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Alfven Wave Collisions, The Fundamental Building Block of Plasma
  Turbulence I: Asymptotic Solution   The nonlinear interaction between counterpropagating Alfven waves is the
physical mechanism underlying the cascade of energy to small scales in
astrophysical plasma turbulence. Beginning with the equations for
incompressible MHD, an asymptotic analytical solution for the nonlinear
evolution of these Alfven wave collisions is derived in the weakly nonlinear
limit. The resulting qualitative picture of nonlinear energy transfer due to
this mechanism involves two steps: first, the primary counterpropagating Alfven
waves interact to generate an inherently nonlinear, purely magnetic secondary
fluctuation with no parallel variation; second, the two primary waves each
interact with this secondary fluctuation to transfer energy secularly to two
tertiary Alfven waves. These tertiary modes are linear Alfven waves with the
same parallel wavenumber as the primary waves, indicating the lack of a
parallel cascade. The amplitude of these tertiary modes increases linearly with
time due to the coherent nature of the resonant four-wave interaction
responsible for the nonlinear energy transfer. The implications of this
analytical solution for turbulence in astrophysical plasmas is discussed. The
solution presented here provides valuable intuition about the nonlinear
interactions underlying magnetized plasma turbulence, in support of an
experimental program to verify in the laboratory the nature of this fundamental
building block of astrophysical plasma turbulence.

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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: funct-an
1
The categories of this paper are: cs
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The categories of this paper are: dg-ga