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Proceedings Paper

Processing of mercurous chloride in space
Author(s): C. Watson; N. B. Singh; A. Thomas; A. E. Nelson; T. O. Rolin; J. Griffin; G. Haulenbeek; N. Daniel; J. Seaquist; C. Cacioppo; Jerry Weber; Maria Ittu Zugrav; R. J. Naumann
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Paper Abstract

Mercurous chloride is an acoustical optical material with an unusually low acoustic velocity and high acousto-optical figure of merit, which makes it an interesting candidate for optical delay lines and Bragg cells for optical signal processors. It also has a broad range of spectral transmissivity which makes it an ideal candidate for wide band acoustically tuned optical filter (ATOF) applications. Single crystals of this material can be readily grown in normal gravity by closed-tube physical vapor transport, but the crystals appear to contain structural inhomogeneities which degrade the optical performance. The nature of these defects is not known, but their degree appears to correlate with the Rayleigh number that characterizes their growth; hence, it is suspected that uncontrolled convection may play a role in the defect structure. This prompted a space flight experiment to determine if these defects could be further reduced by virtually eliminating the buoyancy-driven convective flows which are always present to a degree in normal gravity. Single crystals of mercurous chloride (Hg2Cl2) were grown in the Space Experiment Facility (SEF) transparent furnace developed by the University of Alabama in Huntsville, Consortium for Materials Development in Space. The Northrop- Grumman Science and Technology Center provided the highly purified starting material and analyzed the crystals that were grown. This experiment was flown on Spacehab 4 (STS-77) in May 1996. The SEF is a transparent furnace which allowed the progress of the growth to be recorded by video. Extensive furnace profiling and modeling has been carried out to relate the growth front location to the thermal environment and to the crystal quality. The results of the flight experiment as well as the ground control experiments are presented.

Paper Details

Date Published: 7 July 1997
PDF: 12 pages
Proc. SPIE 3123, Materials Research in Low Gravity, (7 July 1997); doi: 10.1117/12.277725
Show Author Affiliations
C. Watson, Univ. of Alabama in Huntsville (United States)
N. B. Singh, Northrop Grumman Corp. (United States)
A. Thomas, NASA Johnson Space Ctr. (United States)
A. E. Nelson, Univ. of Alabama in Huntsville (United States)
T. O. Rolin, Univ. of Alabama in Huntsville (United States)
J. Griffin, Univ. of Alabama in Huntsville (United States)
G. Haulenbeek, Univ. of Alabama in Huntsville (United States)
N. Daniel, Univ. of Alabama in Huntsville (United States)
J. Seaquist, Univ. of Alabama in Huntsville (United States)
C. Cacioppo, Univ. of Alabama in Huntsville (United States)
Jerry Weber, SHOT Inc. (United States)
Maria Ittu Zugrav, Univ. of Alabama in Huntsville (United States)
R. J. Naumann, Univ. of Alabama in Huntsville (United States)

Published in SPIE Proceedings Vol. 3123:
Materials Research in Low Gravity
Narayanan Ramachandran, Editor(s)

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