MARFEs in tokamak edge plasma: Pattern formation under nonlocal constraints

A simplified two-dimensional nonlinear fluid model is developed to elucidate the basic mechanism of the formation of multifaceted asymmetric radiation from the edge of tokamak plasmas (MARFE). In the framework of a mixed Eulerian-Lagrangian description, the problem is reduced to reaction-diffusion-type equation with nonlocality, which obeys the constraints of length constancy and mass conservation along the magnetic field. With a simple cooling function, this model predicts formation of stationary MARFE-like structures.