Measurements of both species (mass) and thermal diffusivities on Earth are prone to be contaminated by convective contributions to the overall transport. Previous studies of mass and thermal diffusivities conducted on spacecraft have demonstration the gain in precision, and lower absolute values, resulting from the reduced convective transport possible in a low-gravity environment. We have developed a technique for the in-situ measurement of mass diffusivity in liquids at several temperatures utilizing a single sample. In this approach, which circumvents solidification of the diffusion sample prior to concentration profiling, the evolution of the concentration distribution of a radiotracer is followed in real time using two pairs of radiation detectors. A low-temperature version of this hardware was flown successfully on the Mir space station as a risk-mitigation experiment. The experimental hardware for the space station is based on this design. We will measure the self-diffusivity of several metal elements over a wide temperature range and the binary- and impurity-diffusivities of II-VI compounds approximately 100 K above their melting points. Thermal diffusivity measurement of the II-VI materials will be conducted in hardware presently in the design phase.
Thermophysical property measurements on international space station
Space technology and applications international forum -1999 ; 1999 ; Albuquerque, New Mexico (USA)
AIP Conference Proceedings ; 458 , 1 ; 471-476
1999-01-22
6 pages
Conference paper
Electronic Resource
English
Thermophysical Property Measurements on International Space Station
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