chapter
4 Pages

Introduction

However, despite all these advantages, capabilities of the laser as a heat source are limited to a considerable degree. First of all, this is related to the low efficiency of laser radiation in heating metals, caused by their high reflectivity (prior to the formation of a "key-hole") at the wave length bands typical for the majority of industrial lasers. Another factor decreasing the efficiency of utilisation of high-power C0 2-lasers is an over-surface plasma induced by the laser radiation, which greatly reduces the share of the energy introduced by the laser beam into a workpiece. Available are various techniques that can be applied to avoid the above drawbacks, such as, for example, the use of absorbing coatings, and gas jet fed into the treatment zone to blow out the plasma plume. But in such cases, despite some increase in the efficiency of laser methods for metal welding and treatment, the laser is an insuffi­ ciently effective and rather expensive device for realisation of the majority of the said technologies.