Title

Comparison Of Thermal Coupling Threshold Intensities To Minimum Vaporization Intensities For Metals Subject To Laser Irradiation

Abstract

The delivery of energy from laser irradiation to a solid surface is enhanced by thermal coupling. This process has been studied but is not yet fully understood. It has been observed that for metals, that in a range of intensities from 106 - 107 W/cm2, there exists a 'threshold intensity', above which a dramatic rise in energy delivery to the surface has been observed (Maher and Hall, 1980). This energy is greater than the amount that would be delivered by ordinary surface absorption phenomena, given by the product of absorptivity and incident intensity. One theory to explain this enhancement of thermal coupling suggests that a plasma produced over the surface makes a significant contribution to the energy delivery process. If this theory is correct, the threshold intensity should correspond to the intensity required to initiate vaporization. A two-dimensional, cylindrical, transient, finite differencing, conduction model with phase change was used to test that the intensity required to initiate vaporization of the material is related to the threshold intensity. The minimum intensity for vaporization of a target was calculated by running the model for a range of intensities and noting the intensity at which vaporization started to occur. This intensity was compared to the thermal coupling threshold intensity for aluminum and copper. Predictions of the minimum vaporization intensities showed good agreement with experimental measurements of the threshold intensity.

Publication Date

1-1-1991

Publication Title

American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD

Volume

162

Number of Pages

67-73

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

0025807502 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0025807502

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