J. G. Tuttle, Hughes STX, Lanham, MD 20706
P. J. Shirron, and M. J. DiPirro, Code 713, NASA/Goddard Space Flight Center, Greenbelt, MD 20771
We report on the development of a high resolution Penetraton Depth Thermometer (PDT). Similar in principle to superconducting Fixed Point devices, the sensitive range is broadened by the use of a thin film superconductor rather than a bulk crystal. In addition, a dc current excitation is used with a dc SQUID for readout. Tests of a prototype PDT using an indium film demonstrated a maximum sensitivity of 70nK/ÃHz at 0.9Tc using limited excitation current. Temperature resolution of better than 100 pK/ÃHz is predicted. A new version of the PDT has been fabricated according to an optimized design which overcomes several limitations. Design parameters and test results of this device will be presented.
Advances in Cryogenic Engineering Vol 41, p. 1723-1730 (1996).
This work sponsored by NASA's Microgravity Science and Applications Division