Laser light absorption of high-temperature metal surfaces

Area of Science:

• Materials Science
• Physics
• Thermodynamics

Background:

• Laser beam absorption is fundamental to many high-temperature processes.
• Experimental data for metal absorption at extreme temperatures is scarce, often relying on theoretical models.
• Existing models may not accurately predict absorption behavior above metal boiling points.

Purpose of the Study:

• To experimentally determine laser light absorption values for liquid metals at temperatures exceeding their boiling points.
• To investigate the underlying physical mechanisms governing laser absorption in these extreme conditions.
• To challenge and refine existing theoretical predictions of metal absorption.

Main Methods:

• Development of a novel experimental setup for measuring laser light absorption on liquid metal surfaces.
• Conducting measurements at temperatures above the boiling point of the metals.
• Deriving absorption values and analyzing the data in conjunction with theoretical considerations.

Main Results:

• Measured laser absorption values for liquid metals at temperatures above their boiling points.
• Demonstrated the significant role of interband absorption, even at these extreme temperatures.
• Observed nearly constant absorption depth and values between melting and boiling points.

Conclusions:

• Interband absorption is a critical factor in laser light absorption of metals at temperatures above boiling, contradicting common theoretical assumptions.
• The balance between increased atomic spacing (reduced absorption volume) and enhanced conduction electron availability (Fermi band broadening) maintains consistent absorption.
• The findings necessitate a revision of theoretical models for laser-metal interactions at extreme temperatures.