ELECTROCONVECTION PATTERNS IN SMECTIC FILMS AT AND ABOVE ONSET

We have studied patterns of electrically driven convective vortices in thin freely suspended films of smectic liquid crystal at and above th e onset of convection. We present measurements of the convective ampli tude above onset, the spatial variation of the amplitude due to the pr esence of end walls, and the relaxation of the amplitude following a s udden change in the experimental control parameter. Our experimental r esults are shown to agree with predictions based on the Ginzburg-Landa u equation, and we find values for the dimensionless length and time s cales of the Ginzburg-Landau equation.