Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Forced magnetic reconnection and plasmoid coalescence: I - MHD
  Simulations   Forced magnetic reconnection, a reconnection event triggered by external
perturbation, should be ubiquitous in the solar corona. Energy released during
such cases can be much greater than that which was introduced by the
perturbation. It is unclear how the properties of the external perturbation and
the initial current sheet affect the reconnection region properties, and
thereby the reconnection dynamics and energy release profile. We investigate
the effect of the form of the external perturbation and initial current sheet
on the evolution of the reconnection region and the energy release process.
Chiefly we explore the non-linear interactions between multiple, simultaneous
perturbations, which represent more realistic scenarios. Future work will use
these results in test particle simulations to investigate particle acceleration
over multiple reconnection events. Simulations are performed using Lare2d, a
2.5D Lagrangian-remap solver for the visco-resistive MHD equations. The model
of forced reconnection is extended to include superpositions of sinusoidal
driving disturbances, including localised Gaussian perturbations. A transient
perturbation is applied to the boundaries of a region containing a force-free
current sheet. The simulation domain is sufficiently wide to allow multiple
magnetic islands to form and coalesce. Island coalescence contributes
significantly to energy release and involves rapid reconnection. Long
wavelength modes in perturbations dominate the evolution, without the presence
of which reconnection is either slow, as in the case of short wavelength modes,
or the initial current sheet remains stable, as in the case of noise
perturbations. Multiple perturbations combine in a highly non-linear manner:
reconnection is typically faster than when either disturbance is applied
individually, with multiple low-energy events contributing to the same total
energy release.

22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio