Sensitive temperature gradiometer for use at low temperatures.
A device capable of very sensitive temperature gradient measurements in the presence of relatively large ambient temperature fluctuations is described. The device uses a pair of ''matched'' superconducting thin films in a bridge arrangement, with a SQUID magnetometer probe as the null detector.
Cryogenic Thermometry For Turbulence Research: An Overview
We briefly summarize the current status of conventional cryogenic thermometry with emphasis on devices of interest for the proposed High Reynolds Number Turbulence Facility, and point out some other very high resolution capabilities that exist.
Destruction of superconductivity by current
A series of measurements was made of the return of resistance in superconducting wires when the current was increased up to and beyond the critical value. Wires of pure indium of three different diameters were used, and measurements were made on each wire at four different temperatures. The transition curves for a wire of given diameter were reproducible and were independent of temperature. Measurements on sections of wire 0.6 millimeter long gave substantially the same results as measurements on long wires. The fraction of the normal resistance restored by the critical current varied from 0.77 for a wire 0.36 millimeter in diameter to 0.85 for wires 0.11 millimeter in diameter. The classical formula predicts a value of 0.50. The results are discussed in the light of Landau's theory of the intermediate state, and it is shown that the classical value may be approached for wires of large diameter.