A plume consisting of vapor and ionized particles of the workpiece is usually formed in many laser materials processing. The characteristics of this laser-plasma plume depend on a large number of parameters such as the laser power, spot size, scanning speed, material properties and shielding gas. The temperature, degree of ionization, absorption coefficient and pressure of the plume are calculated for different process parameters. The absorption coefficient of the plume given by the Kramers-Unsold relation equation and the ionization fraction given by the Saha-Eggert equation are used to determine the plume pressure. The quality of materials processing can be assessed by the plume properties, and the plume pressure monitoring can be used as a diagnostic tool for process automation and reproducibility of product quality.

Topics
Optical absorption, Laser materials processing, Laser-induced plasma, Materials synthesis and processing
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© 1997 Laser Institute of America.
1997
Laser Institute of America
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