1999 Volume 16 Issue 1 Pages 45-
Diamond thin-film was synthesized under microgravity using Japanese free-flyer (SFU, Space Flyer Unit) launched in March 1995. This program achieved the first space-based production of diamond by Chemical Vapor Deposition (CVD). The DC plasma excitation method was applied to hydrogen-methane mixed gas within the pressure range of 2.66~6.55 X 103 Pa. Remarkable differences of the electron temperature of hydrogen plasma were confirmed between the microgravity and the on-ground experiments. The intensity ratio of CH/Ha measured by emission spectroscopy was found as a sensitive indicator of gravity effects on gaseous chemistry and diamond quality.