Ablation of material by front surface spallation

Conference · Tue Jan 01 04:00:00 EST 1991

DOI:https://doi.org/10.1007/BFb0048369· OSTI ID:5638065

Dingus, R S; Scammon, R J

Laser irradiation can be utilized to remove (i.e., ablate) material in a controlled manner by a hydrodynamic process, referred to as front surface spallation. In this process, a thin layer next to a free surface is heated to a level (below vaporization) so rapidly that it cannot undergo thermal expansion during laser heating. This generates a stress pulse, which propagates both inward and toward the free surface, with an initial amplitude that can be calculated using the Grueneisen coefficient. As the pulse reflects from the free surface, a tensile tail can develop of sufficient amplitude, exceeding the material strength, that a layer will be spalled off, taking much of the laser-deposited energy with it. To achieve spallation conditions, the laser wavelength, pulselength and fluence must be tailored to the absorption depth, Grueneisen coefficient, and spall strength. Hydrodynamic calculations and analytical modeling are presented to explain the process and illustrate conditions under which it should be expected to occur. Under some conditions, front surface spallation can have advantages over ablation by thermal vaporization, where residual temperatures are generally higher. 9 refs., 7 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5638065
• Report Number(s): LA-UR-91-1911; CONF-9104192--12; ON: DE91014773
• Country of Publication: United States
• Language: English

Related Subjects

656003* -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ABLATION
ALUMINIUM
ANALYTICAL SOLUTION
COMPUTER CALCULATIONS
ELASTICITY
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUID MECHANICS
HYDRODYNAMICS
LASER RADIATION
MECHANICAL PROPERTIES
MECHANICS
METALS
NUCLEAR REACTIONS
RADIATIONS
SPALLATION
SURFACES
TENSILE PROPERTIES
THERMOELASTICITY