Flow experiments in superfluid ^4He near T_λ
Abstract
We report here, data from an experiment studying flow of superfluid helium through an array of sub-micron wide slit-apertures. The data is obtained by applying an AC drive voltage to the diaphragm in a Helmholtz resonator cell. We have observed a staircase pattern in the measurements of the amplitude of diaphragm motion as a function of applied drive. At a temperature approximately 60 microKelvin below the transition we observe critical phase difference less than 2*Pi. This indicates that the array must be close to Josephson regime, unexpectedly for this temperature range. Dependence of the resonant frequency on the amplitude indicates nonlinear current-phase characteristic as well. The work is being carried out at JPL, California Institute of Technology under contract to NASA.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2000
- Bibcode:
- 2000APS..MARS36140S