Evidence for Eigenfrequencies in Dendritic Growth Dynamics

Microgravity dendritic growth experiments, conducted aboard the space shuttle Columbia, are described. In-situ video images reveal that pivalic acid dendrites growing in the diffusioncontrolled environment of low-earth orbit exhibit a range of transient or non-steady-state behaviors. The observed transient features of the growth process are being studied with the objective of understanding the mechanisms responsible for these behaviors. Included in these observations is possible evidence for characteristic frequencies or limit cycles in the growth behavior near the tip of the dendrites. These data, and their interpretations, will be discussed.