INSTABILITY OF MAGNETIC MODONS AND ANALOGOUS EULER FLOWS

We construct numerical examples of a 'modon' (counter-rotating vortice s) in an Euler flow by exploiting the analogy between steady Euler how s and magnetostatic equilibria in a perfectly conducting fluid. A nume rical modon solution can be found by determining its corresponding mag netostatic equilibrium, which we refer to as a 'magnetic modon'. Such an equilibrium is obtained numerically by a relaxation procedure that conserves the topology of the relaxing field. Our numerical results sh ow how the shape of a magnetic modon depends on its 'signature' (magne tic flux profile), and that these magnetic modons are unexpectedly uns table to nonsymmetric perturbations. Diffusion can change the topology of the field through a reconnection process and separate the two magn etic eddies. We further show that the analogous Euler flow (or modon) behaves similar to a perturbed Hill's vortex.