J. Phys. Colloques
Volume 41, Numéro C9, Novembre 1980Third International Symposium on Gas-Flow and Chemical Lasers
|Page(s)||C9-129 - C9-135|
J. Phys. Colloques 41 (1980) C9-129-C9-135
EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION OF PULSED LASER ENERGY TRANSMISSION THROUGH THE ATMOSPHEREM. Autric, J.P. Caressa, P. Vigliano, Ph. Bournot, D. Dufresne et G. Inglesakis
Institute of Fluid Mechanics, 1, rue Honnorat, 13003 Marseille, France.
An experimental study has been conducted and compared with a computed numerical model in order to determine the limitations induced by the air breakdown on the transmission of a high energy laser pulse through the standard atmosphere. The 10.6 µm CO2 laser displays up to 300 J in a 2.5 µsec pulse with a high power peak (typically 5x108 W ; 50 ns F W H M) followed by a high energy tail. The laser beam is focused by means of a 5 X telescope at 67.5 m (f/D = 135) outside the laboratory. Envelope of the beam and energy density distribution in the focal plane are presented. Aerosol concentration and size distribution measurements are obtained by means of a particle optical counter (Knollenberg axially scattering spectrometer probe : 0.5 µm < d > 45 µm). Energy and fluence transmitted through the air breakdown - induced plasma for given atmospherical conditions are measured as a function of time and incident fluence and then compared with results of a computed numerical hydrodynamic bi-dimensional model.