Pre-Breakdown Laser Target Vaporization and Enhanced Thermal Coupling
Final technical rept.
AVCO EVERETT RESEARCH LAB INC EVERETT MA
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Vaporization of metallic targets under the influence of pulsed CO2 laser radiation is observed prior to breakdown plasma formation using the techniques of atomic absorption spectroscopy and time resolved emission spectroscopy. Aluminum targets vaporize in times short compared to predictions based on bulk thermal properties, a behavior which may be attributable to microsurface imperfections. Plasma formation times are consistent with models that assume the presence of metallic vapor. Aluminum targets that experienced plasma breakdown exhibited cratering vs little visible surface damage to targets irradiated at fluxes just below the breakdown threshold. Thermal energy deposition per unit incident energy was increased by a factor of three when the breakdown threshold was exceeded.
- Lasers and Masers
- Plasma Physics and Magnetohydrodynamics