Effect of ambient gas and pressure on fullerene synthesis in induction thermal plasma

Abstract

Fabrication of fullerenes (C 60, C 70, etc.) by direct evaporation of C–Si mixed powder using radio frequency inductively coupled thermal plasma were made to find a suitable gas kind and pressure for fullerene synthesis. The results showed that: (1) 150 Torr lower pressure and He/Ar mixed gas are more suitable for fullerene synthesis than higher pressure and pure Ar gas, and (2) it is important for fullerenes synthesis that the radiation intensity of C 2 and C spectra is stronger at 10 mm below coil end, i.e. high-temperature plasma torch region, and it becomes very weak at 150 mm below coil end, i.e. inside the reactor chamber. Furthermore, numerical simulation was carried out to derive the temperature and gas flow fields in the plasma torch and reactor chamber. The calculation results indicate that He mixing into Ar gas can increase the temperature-gradient at the center axis of the plasma torch, and that pressure has a distinct effect on plasma axial velocity distribution.