We construct numerical examples of a `modon' (counter-rotating vortices)
in a Euler flow by exploiting the analogy between steady
Euler flows and magnetostatic equilibria in a perfectly conducting fluid.
A numerical Modon solution can be found by determining its corresponding
magnetostatic equilibrium, which we refer to as `magnetic modon'.
Such an equilibrium is obtained numerically by a relaxation procedure
which conserves the topology of the relaxing field.
Our numerical results show how the shape of a magnetic
modon depends on its `signature' (magnetic flux profile), and that
these magnetic modons are unexpectedly unstable to non-symmetric
perturbations. Diffusion can change the topology of the field through
a reconnection process and separate the two magnetic eddies. We
further show that the analogous Euler flow (or modon) behaves
similar to a perturbed Hill's vortex.
FIGURE (a) the energy is plotted against the time, showing a slow
phase of near-equilibrium and a rapid phase of magnetic
reconnection;
(b-g) 'snap-shots' of the magnetic field at various
stages (each represented by a dot on the energy plot (a).
This paper has been submitted to
The Journal of Plasma Physics.
Magnetic Modons 
