Double layer mechanism in sel-organization of copper secondary nodules under a parallel magnetic field

From the longterm response of electrolytic current of copper deposition in a parallel magnetic field, a new type of micro-MHD effect on the secondary nodules arising from the unstable growth of nonequilibrium fluctuations in the electrical double layer (second micro-MHD effect) was theoretically analyzed. Such instability emerges with charac-teristic convection cells (micro-MHD flows). Then, the unstable condition that double layer overpotential must be positive was derived, which was ascertained by the copper deposition with proton adsorption at the double layer, leading to secondary nodules with ca. 100 μm diameter. To validate the theoretical results, the surface morphology of the deposit and the velocity distribution of the convection cells were theoretically calculated.