Kinetics of physical vapor transport at low pressure under microgravity conditions: I. DCMF flight hardware and experimental conditions

An autonomously operating apparatus has been developed for the measurement of the transport rate of mercuric iodide vapor. It was flown aboard the Space Shuttle STS-77 mission in May 1996. The results of the diffusion coefficient measurement facility (DCMF) space experiment provide a breakthrough in the understanding of the transport phenomena during the physical vapor transport under low total pressures (0.5–3.5 mbar). The comparison of the transport data in microgravity and on earth could reliably be made only due to the sophisticated hardware development. The design, construction and the technical performance of the apparatus are presented in Part I whereas the major results are discussed in Part II.