Experimental and Numerical Studies of Heat Convection in the Synthesis of Single-Walled Carbon Nanotubes by Arc Vaporization

Numerical analysis on heat convection in the synthesis of single-walled carbon nanotubes (SWNTs) by arc vaporization is carried out to calculate the cooling rate of carbon clusters and the temperature distribution of the buffer gas (helium) during the synthesis. The effects of three factors, gravity (G = 1, 2, and 3g0, where 1g0 is normal earth gravity), input power (P = 500, 1000, 2000, and 3000 W), and buffer gas pressure ( p = 40, 50, 80, and 100 kPa) are investigated. By comparing the calculated results with those of a previous synthesis experiment under gravity conditions of G = 1, 2, and 3g0, it is clarified that differences in the cooling rate and the shape of the high-temperature region of the buffer gas cause considerable changes in both the yield and quality of SWNTs produced. The similarity of the heat convection under different input powers and buffer gas pressures is also considered.