SHEAR-FLOW EFFECTS ON THE NONLINEAR EVOLUTION OF THERMAL INSTABILITIES

In the weak radiation drive regime, the coupling between the thermal instability driven by impurity radiation and the self-consistent flow profile modification leads to a simple dynamical system that can be approximated by the Volterra-Lotka equations. In this system the shear flow acts as a predator and the temperature fluctuations act as prey. The solutions are oscillatory, and their behavior resembles that of edge-localized modes (ELM's). The solutions of the simplified model are compared with the three-dimensional and two-dimensional nonlinear numerical results for this instability.