Plasma instability and optimum utilization of laser energy in laser materials processing

Franz-Josef Kahlen; Hermann Emminger; Srikanth Sankaranarayanan; Aravinda Kar

doi:10.1117/12.377016

7 February 2000 Plasma instability and optimum utilization of laser energy in laser materials processing

Franz-Josef Kahlen, Hermann Emminger, Srikanth Sankaranarayanan, Aravinda Kar

Proceedings Volume 3888, High-Power Lasers in Manufacturing; (2000) https://doi.org/10.1117/12.377016
Event: Advanced High-Power Lasers and Applications, 1999, Osaka, Japan

Abstract

A plume consisting of vapor and ionized particles of the workpiece is usually formed during various types of laser materials processing. The process parameters such as the laser power, spot diameter, scanning speed, material properties and shielding gas affect the properties of this plume. A one- dimensional model is presented to understand the effects of the vapor-plasma plume in continuous wave (cw) laser materials processing. A model for pulsed laser materials processing is also discussed. These models are used to analyze the transmission of the laser beam through the plume and the deposition of energy on the melt pool at the substrate surface. An experimental technique described as the pinhole experiment is devised for pulsed laser operations to measure the partitioning of laser energy between the plume and workpiece and to identify the process parameter regime for efficient energy transfer from the laser beam to the workpiece. The attenuation coefficient of the vapor-plasma plume was measured during cw CO₂ laser-assisted metal deposition conditions by directing a CO₂ probe laser beam horizontally through the plume and determining the ratio of irradiance of the beam after and before the plume. Assuming an isotropic attenuation coefficient through the plume, the energy partitioning between the plume and workpiece was determined.

Citation Download Citation

Franz-Josef Kahlen, Hermann Emminger, Srikanth Sankaranarayanan, and Aravinda Kar "Plasma instability and optimum utilization of laser energy in laser materials processing", Proc. SPIE 3888, High-Power Lasers in Manufacturing, (7 February 2000); https://doi.org/10.1117/12.377016

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