Periodic, aperiodic and chaotic motion of drift wave vortices in a circular region

The modulated point vortex model associated with the Hasegawa-Mima equation is used to study the dynamical behavior of drift wave vortices in a bounded region. When a circle is taken as the boundary of the region, the potential for the vortices can be constructed with the aid of the circle theorem which replaces the boundary by the mirror images of the vortices inside the circle and ensures that the potential for the vortices is zero on the boundary. Periodic, aperiodic and chaotic motions are realized depending on the number of vortices and the magnitude of the value of the diamagnetic drift which breaks the rotational symmetry and has a tendency to drive vortices into chaotic motion.