SOME EVIDENCE FOR THE EXISTENCE AND MAGNITUDE OF A CRITICAL MARANGONI NUMBER FOR THE ONSET OF OSCILLATORY FLOW IN CRYSTAL-GROWTH MELTS

Experiments on floating half zones of NaNO3 heated from above show the onset of oscillatory Marangoni convection at a critical Marangoni number Ma(T)c ∼ 104. The dependence of Ma(T)c on zone length is investigated and discussed. Literature on the onset of temperature oscillations is reviewed. It gives Ma(T)c of the same order of magnitude for other melts. Effects of oscillatory Marangoni convection in crystal growth from melt are discussed. A description of the state of oscillatory Marangoni convection in this geometry is given. © 1979.