Laser Beam-Arc Plasma Interaction and Combined Discharge
In the numerous processes of laser-arc welding and treatment of materials considered in Chapter 1, the laser beam passes a certain distance in the arc column plasma. Interaction between the laser beam and the arc plasma occurring in this case can lead to a fundamental change in the energy balance of the arc discharge. The local character of heating the plasma by a focused laser beam induces substantial changes not only in the integrated, but also in the distributed, characteristics of the arc plasma. In addition, due to absorption and refraction of laser radiation in the plasma, there is redistribution of the intensity of the laser beam interacting with this plasma. If the power input into the arc provided by laser radiation is comparable with the electric power of the arc, a special type of discharge, i.e. combined laser-arc discharge, is realised . The properties of this discharge differ greatly from the properties of a conventional arc discharge, and from properties of an optical discharge maintained by laser radiation.