Arc-discharge method- SWNTs

A common technique for the production of Single Walled Carbon Nanotubes (SWNTs) is the electric arc discharge method in which carbon is vaporized between two carbon electrodes. Small diameter, single-wall nanotubes can be synthesized using a Miller XTM 304 dc arc welder to maintain the optimal settings between two horizontal electrodes in helium or argon atmospheres. The voltage is controlled by an automatic feedback loop that senses the voltage differences between the two electrodes and adjusts them accordingly. The feedback system contains a motor connected to a control box. The control box is connected to the motor and arc welder. The desired voltage must be set on the control box which signals the motor to separate or the electrodes to increase the voltage or bring the electrodes close together to decrease the voltage.