WAVE-PROPAGATION IN A MEDIUM WITH DISORDERED EXCITABILITY

The effect of quenched disorder on the propagation of autowaves in exc itable media is studied both experimentally and numerically in relatio n to the light-sensitive Belousov-Zhabotinsky reaction. The spatial di sorder is introduced through a random distribution with two different levels of transmittance. In one dimension the (time-averaged) wave spe ed is smaller than the corresponding to a homogeneous medium with the mean excitability. Contrarily, in two dimensions the velocity increase s due to the roughening of the front. Results are interpreted using ki nematic and scaling arguments. In particular, for d = 2 we verify a th eoretical prediction of a power-law dependence for the relative change of the propagation speed on the disorder amplitude.