COMBINED LASER AND PLASMA ARC WELDING TORCH

A welding torch which combines features of both laser and plasma-arc welding torches. A laser beam is directed by an objective lens so that it is colinear with the central axis of a plasma-arc torch. The laser beam passes through a pla nar or conical cathode electrode placed at the bottom orifice of the torch. A coaxial a perture having a diameter less than that of the laser beam is drilled into the cathode t o allow the laser beam to pass through the cathode. A constricting nozzle is placed unde r the cathode, with the laser beam passing through the axis of the nozzle. As with a standard plasma-arc torch, a gas is forced through a chamber having the cathode and nozzle at its bottom end. As the cathode is heated by the laser radiation, the g as is ionized and a plasma-arc is formed. As the laser beam passes through the nozzle, it comes to a focus and interacts with the plasma-arc formed between the cathode an d a workpiece. The resulting interactions between the plasma-arc and laser beam form a plasma-laser discharge which acts to additionally constrict the laser beam and p lasma-arc and increase the energy density of the welding spot formed on the workpiece.