The isothermal dendritic growth experiment

Although it is known that dendritic growth is controlled by the transport of latent heat from the moving solid/melt interface as the dendrite advances into a supercooled melt, a fully predictive analysis has eluded researchers. The complications added by gravity-driven convection preclude any straight forward zero parameter test of heat conduction analysis, crystal growth physics, or a scaling analysis associated with pattern formation theories for terrestrial dendritic growth data. The Isothermal Dendritic Growth Experiment (IDGE) was designed, built, and flown to test dendritic growth theories by making accurate on-orbit, microgravity dendritic growth measurements, using succinonitrile (SCN: a bcc organic plastic material used here as a physical analog to metals). The IDGE was launched to a low-earth orbit by NASA in March, 1994, as one of four primary experiments comprising the second United States Microgravity Payload (USMP-2). The experiment operated for nine days at a quasi-static acceleration level of approximately 7 x 10(-7) g(o). The IDGE night data have now been analyzed, permitting a comprehensive comparison between dendritic growth under terrestrial and microgravity conditions.