Variations in the Scroll Ring Characteristics with the Excitability and the Size of the Pinning Obstacle in the BZ Reaction

We report the experimental results of the effects of excitability on the wave characteristics of free rotating and pinned scroll rings in the Belousov-Zhabotinsky (BZ) reaction. The experiments show that the stability of the scroll ring depends on the excitability of the medium. At low excitability, the scroll ring becomes less stable and eventually breaks up. As we increase the excitability of the medium, the time period (T) and wavelength (λ ) of the excitation wave decrease while wave velocity (v) increases. Properties of both free and pinned scroll rings change in the same way. However, at a given excitability, both the λ and v of a pinned scroll ring increase with the size of the obstacle. For the range of parameters chosen in our experiments, the excitability changes brought by varying reactant concentrations have a higher impact on the scroll ring properties than those induced by the size of the pinning obstacle.