Dynamical properties of superfluid turbulence
Despite all the experimental work done in recent years to study superfluid turbulence, the understanding of the dynamical properties of this system is still poor. The author designed a new cryogenic probe to perform a series of experiments to study the dynamical response of the vortex line density in turbulent thermal counterflow. The apparatus uses a small glass flow tube to probe the fluctuations in the line density around the two turbulent states (TI, TII) present in this system. A chemical potential gradiometer is used that measures the chemical potential across the flow tube. This quantity is directly related to the vortex line density. The gradiometer also enabled both the steady state and the dynamical properties of the turbulence to be studied. These experiments have established the existence of fluctuations in the chemical potential in turbulent counterflow. For the first time fluctuations in the dissipation were observed in the TI/TII transition region. The fluctuations are characteristic of broad-band noise showing no evidence of fluctuations at preferred frequency. The TI/TII transition is characterized by a sharp increase in the noise power amplitude and its variation with heat current reveals a complex structure.
- Research Organization:
- Ohio State Univ., Columbus (USA)
- OSTI ID:
- 5196801
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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