A fundamental plasma based model for energy transfer in laser material processing

Abstract
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.

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