Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The moving boundary problem in the presence of a dipole magnetic field   An exact analytic solution is obtained for a uniformly expanding, neutral,
infinitely conducting plasma sphere in an external dipole magnetic field. The
electrodynamical aspects related to the radiation and transformation of energy
were considered as well. The results obtained can be used in analyzing the
recent experimental and simulation data.

2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th