Numerical analysis on the dispersion process of carbon clusters synthesized by gas evaporation using dc arc

The dispersion process of typical carbon cluster synthesized by gas evaporation using (dc) arc was numerically investigated under normal gravity (1 G) and nongravity (0 G) conditions to clarify the effect of natural convection. Calculated pressure dependence of residence time of C60 in the temperature state between 1000 and 2000 K under 1 G took a maximum value of about 260 ms at the pressure around 0.06 atm in helium, while under 0 G, it increased almost linearly with pressure. Such features in the pressure dependence of residence time of C60 under both 1 and 0 G were related to its yield by a simple model based on an annealing of imperfect C60 to perfect C60 structure. According to this model, experimentally observed secondary increase of C60 yield was consistently explained in terms of the effect of natural convection.