Accession Number : ADA259387

Title :   Assessment of Single-Pulse Laser Damage to Structural Materials for Spacecraft,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Stonesifer, F. R. ; Randles, P. W. ; Nemes, J. A.

Report Date : 24 DEC 1992

Pagination or Media Count : 27

Abstract : Laser radiation damage to structural or shielding materials can occur by several quite different mechanisms. For continuous-wave and repetitively-pulsed radiation, the damage has been found to be primarily thermal. However, for a single laser pulse of very high intensity and short duration, spalling and mechanical damage become the principal failure mechanism and time does not allow extensive thermal degradation. In exposure of opaque materials to a high-energy short-duration laser pulse, an expanding plasma is formed on the material surface and a mechanical pulse is transmitted into the remaining target material. This compression wave, attenuated by the target material, reflects off the free or low impedance boundary at the back surface as a tension wave. If conditions are favorable, both front and back faces may spall causing complete penetration of the material. The magnitude of the dynamic stress pulse is dependent on intensity, wave length, and pulse duration as well as the target-material properties and thickness. A discussion of pressure/impulse, wave attenuation, and spallation is presented. Equations are developed. Experimental data available in the literature, from both flyer-plate and laser shock tests, are plotted and compared for various classes of thin structural materials.... Laser damage, Single-pulse shock, Spacecraft materials, Spallation.

Descriptors :   *LASER DAMAGE, *MATERIALS, *PULSES, *RADIATION, *SPACECRAFT, *STRUCTURAL COMPONENTS, ATTENUATION, BOUNDARIES, COMPRESSION, CONTINUOUS WAVES, DAMAGE, DEGRADATION, DYNAMICS, ENERGY, EQUATIONS, EXPERIMENTAL DATA, FAILURE, FLYER PLATES, HIGH ENERGY, HIGH INTENSITY, IMPEDANCE, INTENSITY, LASERS, LENGTH, PENETRATION, PLATES, PRESSURE, RADIATION DAMAGE, SHIELDING, SHOCK, SHOCK TESTS, SPALLATION, SURFACES, TARGETS, TENSION, TEST AND EVALUATION, THERMAL DEGRADATION, THICKNESS, TIME, PLASMAS(PHYSICS), WAVES, STRESSES, HYDRODYNAMICS.

Subject Categories : Lasers and Masers
      Radiation and Nuclear Chemistry
      Unmanned Spacecraft
      Manned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE