SPIRAL WAVE FORMATION IN 3-DIMENSIONAL EXCITABLE MEDIA

A mechanism for the generation of spiral waves in three-dimensional ex citable media is described. Experiments using the photosensitive Belou sov-Zhabotinsky reaction shaw that circular or spiral waves appear in the wake of a propagating wave following a local perturbation in illum ination intensity. The induced waves arise from three-dimensional scro ll waves striking the upper boundary of the excitable medium. Spiral w aves,ur. formed over a range of illumination intensities and perturbat ion times which place the induced wave in the vulnerable region of the refractory wave back.