Transient nucleate pool boiling experiments using R113 are conducted f
or short times in microgravity and in earth gravity with different hea
ter surface orientations and subcoolings. The heating surface is a tra
nsparent gold film sputtered on a quartz substrate, which simultaneous
ly provides surface temperature measurements and permits viewing of th
e boiling process from beneath. For the microgravity experiments, whic
h have uniform initial temperatures and no fluid motion, the temperatu
re distribution in the R113 at the moment of boiling inception is know
n. High speed cameras with views both across and through the heating s
urface record the boiling spread across the heater surface, which are
classified into six (6) distinct categories.