Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of twist on magnetic flux tubes at the base of the solar
  convection zone   Using two-dimensional magnetohydrodynamics calculations, we investigate a
twist gen- eration mechanism on a magnetic flux tube at the base of the solar
convection zone based on the idea of Choudhuri, 2003, Sol. Phys., 215, 31 in
which a toroidal mag- netic field is wrapped by a surrounding mean poloidal
field. During generation of the twist, the flux tube follows four phases. (1)
It quickly splits into two parts with vortex motions rolling up the poloidal
magnetic field. (2) Owing to the physical mechanism similar to that of the
magneto-rotational instability, the rolled-up poloidal field is bent and
amplified. (3) The magnetic tension of the disturbed poloidal magnetic field
re- duces the vorticity, and the lifting force caused by vortical motion
decreases. (4) The flux tube gets twisted and begins to rise again without
splitting. Investigation of these processes is significant because it shows
that a flux tube without any initial twist can rise to the surface in
relatively weak poloidal fields.

5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat