A FUNDAMENTAL PLASMA BASED MODEL FOR ENERGY-TRANSFER IN LASER MATERIAL PROCESSING

In most applications of lasers for material processing a plasma is detected above the hot surface of the workpiece. Since in certain ranges of temperature and density plasmas are able to absorb a significant part of the incident laser power, the physical processes which supply this energy into the workpiece are of special interest. In this paper the energy supply of a collisional plasma with a low degree of ionisation is considered in the steady state in a one-dimensional geometry. The dominant energy transport process is found to be the release of kinetic and ionisation energy of charged particles being absorbed and then recombining at the wall. Finally, a numerical example is given for the case of laser welding involving the presence of a plasma whose electron temperature and density are predicted. © 1990 IOP Publishing Ltd.