6 July 1999 Diagnostic study of plasma CVD under microgravity
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Abstract
Diamond synthesis under microgravity was successfully executed using Japanese free-flyer (SFU, Space Flyer Unit) launched in 1995. This program achieved the space-based production of diamond by plasm-assisted Chemical Vapor Deposition (CVD). The results showed the better quality of diamond than that of earth-grown diamond and the microgravity effects on gaseous chemistry of CVD processes. To obtain a detailed understanding of plasma processes under microgravity, the post flight experiments of the SFU program were executed. A diagnostic study of hydrogen-methane plasma was applied to the CVD experiments using the 4.5s drop-shift facility in Toki, Japan. We found the direct effects of microgravity on the pattern formation of plasma discharge. The plasma instabilities affected the emission characteristics of plasma. Plasma temperature was estimated based on the emission spectra as a function of position from anode. Remarkable differences of the electron temperature of plasma were confirmed between the microgravity and the normal-gravity conditions.
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Masamichi Ishikawa, Shin-ichi Kamei, Naokiyo Koshikawa, Naoji Fujimori, Yoichiro Sato, "Diagnostic study of plasma CVD under microgravity", Proc. SPIE 3792, Materials Research in Low Gravity II, (6 July 1999); doi: 10.1117/12.351288; https://doi.org/10.1117/12.351288
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