Engineering topics

Chui, T. C. P.

Publications and source records attributed to Chui, T. C. P..

22 records · Page 2

NASA NTRS1987

The lambda point experiment in microgravity

An experiment for performing high-resolution measurements of the heat capacity singularity at the lambda point of helium in microgravity conditions is described. By obtaining such measurements in space, it is expected that the intrinsic distortion of the transition would be reduced by at least two orders of magnitude, allowing the theory of cooperative phase transitions to be more effectively tested. Technology developments for the lambda point experiment include a new high-resolution thermometer, an advanced thermal control system, and a reusable flight-qualified superfluid helium dewar.

Lipa, J. A.↗

NASA NTRS1987

Thermal conductivity and Kapitza boundary resistance of He-4 near T(gamma)

The preliminary results of high resolution measurements of the thermal conductivity of He-4 in a cell with a nominal 1 mm gap are reported and compared with previous results obtained with a 2 mm gap. The temperature dependence of the conductivity was found to be similar for both cells, indicating that size and boundary effects are well controlled. The detailed behavior of the Kapitza resistance just below T(gamma) is also reported.

Chui, T. C. P.↗

NASA NTRS1987

Thermal diffusive conductivity of dilute superfluid (He-3)-(He-4) mixtures

A new technique is described for measuring the effective thermal conductivity of superfluid (He-3)-(He-4) mixtures. The results confirm the large departures from hydrodynamic theory reported previously. The analysis suggests that the measured conductivity is the finite thermal diffusive conductivity of superfluid helium in the absence of counterflow. This conductivity need not diverge in the limit of small He-3 concentration.

Chui, T. C. P.↗

NASA NTRS1983

Very high-resolution heat-capacity measurements near the lambda point of helium

New measurements of the heat capacity of a sample of helium 3-mm high are reported, which extend to within 5 x 10 to the -8th deg of the lambda transition at the vapor pressure. From an analysis of the results allowing for the effect of gravity, the values -0.0127 + or - 0.0026 (2 sigma) for the exponent alpha (= alpha-prime) and 1,058 + or - 0.004 for the leading singularity ratio A/A-prime are obtained. These values are in closer agreement with the theoretical predictions than those reported previously.

Lipa, J. A.↗