Intrinsic fluctuations of the vortex-line density in superfluid turbulence
We present a comprehensive experimental study of the intrinsic fluctuations associated with superfluid turbulence. Fluctuations in the chemical potential and temperature difference for He II thermal counterflow in a small-diameter tube become extremely large at the T-I--T-II transition. This result is in qualitative agreement with a simple dynamical model of a transcritical bifurcation. The fluctuations in the fully developed T-II state are smaller than 0.1%, in accord with computer simulations of fluctuations in homogeneous superfluid turbulence. Consistent measurements of the power spectra, power amplitude, relaxation time, and steady-state vortex-line density are presented. Our results are in substantial disagreement with previous measurements of fluctuations in superfluid turbulence. We suggest that the major discrepancy is due to unexpectedly large-amplitude fluctuations generated by macroscopic inhomogeneities in the vortex-line density present in the earlier experiments. Evidence from a variety of experiments, including our own measurements of externally driven fluctuations, supports this interpretation.
- Research Organization:
- Department of Physics, The Ohio State University, Columbus, Ohio 43210-1106
- OSTI ID:
- 6772059
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 35:7
- Country of Publication:
- United States
- Language:
- English
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