Turbulent He II thermal counterflow: fluctuations and the thermal resistance in large channels
Experiments were performed to study the behavior of He II undergoing turbulent thermal counterflow in large (approx. 1 mm characteristic dimension) flow channels. In one series of experiments small random motions of a flat-plate oscillator which was resonantly mounted in the flow channel were observed. The mean squared oscillator displacement was measured as a function of counterflow velocity and its dependence on temperature, oscillator size, and channel geometry was investigated. An interpretation of the random motions in terms of vortex line density fluctuations is presented and a correlation time for these fluctuations is deduced from the data. This correlation time is shown to be identical to that derived from the Vinen model of superfluid turbulence. In a related experiment the thermal resistance of turbulent He II in 1 mm diameter flow tubes was measured as a function of the counterflow velocity. An ac measurement technique is described which employs a thin film superconducting bolometer to resolve the microkelvin temperature differences from which the thermal resistance is deduced. The results obtained suggest that the general features of the turbulent state described by the Vinen model are common to counterflow in large and small channels. However, the detailed properties of the turbulence are shown to depend strongly on channel size.
- Research Organization:
- Ohio State Univ., Columbus (USA)
- OSTI ID:
- 5126728
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HELIUM II
TURBULENT FLOW
BOLOMETERS
OSCILLATORS
SUPERFLUIDITY
TEMPERATURE DEPENDENCE
VELOCITY
ELECTRONIC EQUIPMENT
EQUIPMENT
EVEN-EVEN NUCLEI
FLUID FLOW
FLUIDS
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MEASURING INSTRUMENTS
NUCLEI
QUANTUM FLUIDS
STABLE ISOTOPES
640450* - Fluid Physics- Superfluidity