A. Tilgner

Double diffusive staircases are experimentally investigated in a fluid layer with a stabilizing temperature gradient and a destabilizing gradient of ion concentration. Gradients of temperature and ion concentration are maintained in a steady state within an electrochemical system. Staircases are observed even if the density stratification is unstable. None of the previously proposed mechanisms for staircase formation can be recognized in the experiments. Ion transport through fingers that are part of a staircase is not the same as the transport through fingers extending through the entire cell. Fingers cease to exist if the diffusive heat transport between neighboring fingers is insufficient.