Time-dependent convection in a /sup 3/He-superfluid /sup 4/He solution

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5330379

Haucke, H J

It was established that dilute solutions of /sup 3/He in superfluid /sup 4/He display the hydrodynamic instability known as Rayleigh-Benard convection. This instability involves a transition from a state where the fluid is motionless to one of steady convective flow, occurring when the temperature gradient or heat flow through the cell exceeds some critical value. Emphasis was on characterizing the subsequent transitions found at higher heat flows, taking full advantage of the high-stability and low-noise characteristics of the experimental system. While the dilute solutions behave in a manner analogous to classical fluids in these studies, a turbulent state most likely comprised of a convectively driven tangle of quantum vortex lines was also observed. Increasing the heat flow above the convective onset eventually produces a transitions from steady flow to oscillatory flow. The onset of these oscillations is shown to be analagous to a continuous phase transition. Still larger heat flows excite a second (incommensurate) oscillatory mode. Much of this work is on the transitions to chaos arising from the interaction of these two oscillations, specifically period doubling, intermittency, and modelocking. Theoretical models exist for these transitions and are compared with the data when feasible. Calculations of dimension and entropy for experimental data are presented, as well as power spectra and Poincare sections.

• Research Organization: California Univ., San Diego (USA)
• OSTI ID: 5330379
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CONVECTION
DISPERSIONS
ENERGY TRANSFER
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
HEAT TRANSFER
HELIUM 3
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
MIXTURES
NUCLEI
OSCILLATIONS
SOLUTIONS
STABLE ISOTOPES
SUPERFLUIDITY
VORTICES