Transitions between orbits of resonance attractors for spiral waves

Spiral waves rotating in a thin layer of the light-sensitive Belousov-Zhabo tinsky reaction can he controlled by the application of short light pulses at instants corresponding to the passage of a wave front through a measurin g point. It is shown that such a feedback results in a drift of the spiral wave core along a discrete set of stable circular orbits centered at the me asuring point, in food quantitative agreement with the theory of the resona nce attractor recently developed. Variations of parameters in the feedback loop initiate transitions between orbits of different size. Thus a spiral w ave drift can he induced along a snail-shaped trajectory with permanently g rowing distance from the measuring point.