  We analyze solar quiescent prominence bubble characteristics and instability
dynamics using Hinode/Solar Optical Telescope (SOT) data. We measure bubble
expansion rate, prominence downflows, and the profile of the boundary layer
brightness and thickness as a function of time. The largest bubble analyzed
rises into the prominence with a speed of about 1.3 km/s until it is
destabilized by a localized shear flow on the boundary. Boundary layer
thickness grows gradually as prominence downflows deposit plasma onto the
bubble with characteristic speeds of 20 - 35 km/s. Lateral downflows initiate
from the thickened boundary layer with characteristic speeds of 25 - 50 km/s,
"draining" the layer of plasma. Strong shear flow across one bubble boundary
leads to an apparent coupled Kelvin-Helmholtz Rayleigh-Taylor (KH-RT)
instability. We measure shear flow speeds above the bubble of 10 km/s and infer
interior bubble flow speeds on the order of 100 km/s. Comparing the measured
growth rate of the instability to analytic expressions, we infer a magnetic
flux density across the bubble boundary of ~10^{-3} T (10 gauss) at an angle of
~70 degrees to the prominence plane. The results are consistent with the
hypothesis that prominence bubbles are caused by magnetic flux that emerges
below a prominence, setting up the conditions for RT, or combined KH-RT,
instability flows that transport flux, helicity, and hot plasma upward into the
overlying coronal magnetic flux rope.
