Precise Measurements of Dendrite Growth of Ice Crystals in Microgravity

An ice crystal growth experiment was performed on board the International Space Station. The experiment was repeated 134 times with various undercooling conditions. Dendrite crystal growth velocity and tip radius were precisely measured by using a newly developed software. The results are compared with those obtained previously on the ground as well as with those reported by Glicksman et al. for Succinonitrile (SCN). The plot of the dimensionless velocity V as a function of the dimensionless undercooling Δ under microgravity revealed values that were consistently lower than those obtained under 1-G which indicates that thermal convection was suppressed. The plot of the dimensionless radius R0 as a function of Δ showed a less scattered value. The stability factor σ* became close to that of SCN when it was calculated using the geometrical mean radius.