Lasersolid interaction and dynamics of the laserablated materials
Abstract
Rapid transformations through the liquid and vapor phases induced by lasersolid interactions are described by the authors' thermal model with the ClausiusClapeyron equation to determine the vaporization temperature under different surface pressure condition. Hydrodynamic behavior of the vapor during and after ablation is described by gas dynamic equations. These two models are coupled. Modeling results show that lower background pressure results lower laser energy density threshold for vaporization. The ablation rate and the amount of materials removed are proportional to the laser energy density above its threshold. The authors also demonstrate a dynamic source effect that accelerates the unsteady expansion of laserablated material in the direction perpendicular to the solid. A dynamic partial ionization effect is studied as well. A selfsimilar theory shows that the maximum expansion velocity is proportional to c(sub s)(alpha), where 1  alpha is the slope of the velocity profile. Numerical hydrodynamic modeling is in good agreement with the theory. With these effects, alpha is reduced. Therefore, the expansion front velocity is significantly higher than that from conventional models. The results are consistent with experiments. They further study how the plume propagates in high background gas condition. Under appropriate conditions, the plume is slowed down, separates with the background, is backward moving, and hits the solid surface. Then, it splits into two parts when it rebounds from the surface. The results from the modeling will be compared with experimental observations where possible.
 Publication:

Presented at the Spring Meeting of the Materials Research Society (MRS
 Pub Date:
 1995
 Bibcode:
 1995mrs..meet...17C
 Keywords:

 Gas Dynamics;
 Gas Lasers;
 GasSolid Interactions;
 Laser Ablation;
 Laser Target Interactions;
 Solid Surfaces;
 Vapor Deposition;
 Vapor Phases;
 Hydrodynamics;
 Mathematical Models;
 Plumes;
 Pressure;
 Vaporizing;
 Velocity Distribution;
 Lasers and Masers