Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-dimensional numerical simulations of fast-to-Alfven conversion in
  sunspots   The conversion of fast waves to the Alfven mode in a realistic sunspot
atmosphere is studied through three-dimensional numerical simulations. An
upward propagating fast acoustic wave is excited in the high-beta region of the
model. The new wave modes generated at the conversion layer are analyzed from
the projections of the velocity and magnetic field in their characteristic
directions, and the computation of their wave energy and fluxes. The analysis
reveals that the maximum efficiency of the conversion to the slow mode is
obtained for inclinations of 25 degrees and low azimuths, while the Alfven wave
conversions peaks at high inclinations and azimuths between 50 and 120 degrees.
Downward propagating Alfven waves appear at the regions of the sunspot where
the orientation of the magnetic field is in the direction opposite to the wave
propagation, since at these locations the Alfven wave couples better with the
downgoing fast magnetic wave which are reflected due to the gradients of the
Alfven speed. The simulations shows that the Alfven energy at the chromosphere
is comparable to the acoustic energy of the slow mode, being even higher at
high inclined magnetic fields.

16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs