Self-organization and symmetry-breaking in two-dimensional plasma turbulence

The spontaneous self-organization of two-dimensional magnetized plasma is investigated within the framework of magnetohydrodynamics with a particular emphasis on the symmetry-breaking induced by the shape of the confining boundaries. This symmetry-breaking is quantified by the angular momentum, which is shown to be generated rapidly and spontaneously from initial conditions free from angular momentum as soon as the geometry lacks axi-symmetry. This effect is illustrated by considering circular, square and elliptical boundaries. It is shown that the generation of angular momentum in non-axisymmetric geometries can be enhanced by increasing the magnetic pressure. The effect becomes stronger at higher Reynolds numbers. The generation of magnetic angular momentum (or angular field), previously observed at low Reynolds numbers, becomes weaker at larger Reynolds numbers. PACS numbers: 52.30.Cv, 47.65.-d, 52.65.Kj