Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-Fluid Simulation of the Magnetic Field Evolution in Neutron Stars   Using a numerical simulation, we study the effects of ambipolar diffusion and
ohmic diffusion on the magnetic field evolution in the interior of an isolated
neutron star. We are interested in the behavior of the magnetic field on a long
time scale, over which all Alfven and sound waves have been damped. We model
the stellar interior as an electrically neutral plasma composed of neutrons,
protons and electrons, which can interact with each other through collisions
and electromagnetic forces. Weak interactions convert neutrons and charged
particles into each other, erasing chemical imbalances. As a first step, we
assume that the magnetic field points in one fixed Cartesian direction but can
vary along an orthogonal direction. We start with a uniform-density background
threaded by a homogeneous magnetic field and study the evolution of a magnetic
perturbation as well as the density fluctuations it induces in the particles.
We show that the system evolves through different quasi-equilibrium states and
estimate the characteristic time scales on which these quasi-equilibria occur.

1
The categories of this paper are: cs
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin