GRAVITY CURRENTS AND THE ELECTROLYTE CONCENTRATION FIELD IN ELECTROCHEMICAL DEPOSITION

Using shadowgraphs, we visualize local electrolyte concentration varia tions in quasi-two-dimensional electrochemical deposition experiments. Experiments have been performed in both circular and parallel-electro de geometries. Our results indicate that a region of ion depletion mov es from the cathode towards the anode, while a region of enhanced conc entration grows in from the anode. Large scale gravity-driven flows, w hich drive the growth of these regions, are observed. The growth speed of the metal aggregate at the cathode is the same as the speed at whi ch these flows move anions away from the cathode, except at the earlie st stages of growth. By integrating the shadowgraph intensity, we calc ulate the concentration field in the parallel geometry.