In arc-discharge, carbon atoms are evaporated by a helium plasma initiated by high currents passed through an opposing carbon anode and cathode. Arc-discharge has been developed into an excellent method for producing both high quality MW-CNTs and SW-CNTs. For the growth of SW-CNTs, a metal catalyst is needed in the arc-discharge system. The first success in producing substantial amount of SW-CNTs by arc-discharge was achieved by BETHUNE and coworkers in 1993 , by using a carbon anode containing a small percentage of cobalt in the discharge experiment.
The growth of high quality SW-CNTs was achieved by SMALLEY and coworkers using a laser ablation method . The method utilized intense laser pulses to ablate a carbon target containing 0.5 atomic percent of nickel and cobalt. The target was placed in a tube-furnace heated to 1200°C.
In SW-CNT growth by arc-discharge and laser ablation, typical by-products
include fullerene, graphitic polyhedrons with enclosed metal particles, and
amorphous carbon in the form of particles or over-coating on the CNT sidewalls.