OPTICAL INVESTIGATIONS OF FILM DYNAMICS IN SUPERFLUID HE-3 USING A COOLED CHARGED COUPLED DEVICE

We have investigated optically the dynamics of 0.1 mm thick superfluid He-3 films at temperatures 0.66-1.0T(c), using a CCD sensor at 70 K i nside the vacuum can of our nuclear-demagnetization cryostat. Relaxati on of the free liquid surface, deflected 0.5mum from equilibrium by a 5 nJ heat pulse, was found to be overdamped with a time constant tau(s ) almost-equal-to 1 s close to T(c). Using two-fluid hydrodynamics, th e measured response curves were employed to determine the second-visco sity coefficient zeta3 in the range 0.86-0.99T(c). A good agreement wi th the theoretical results by Einzel was obtained.