LINEAR-STABILITY ANALYSIS OF ROTATING SPIRAL WAVES IN EXCITABLE MEDIA

Fast numerical methods are used to solve the equations for periodicall y rotating spiral waves in excitable media, and the associated eigenva lue problem for the stability of these waves. Both equally and singly diffusive media are treated. Rotating-wave solutions are found to be d iscretely selected by the system and an isolated, complex-conjugate pa ir of eigenmodes is shown to cause instability of these waves. The ins tability arises at the point of zero curvature on the spiral interface and results in wavelike disturbances which propagate from this point along the interface.