Influence of intensity on mechanical effect of laser plasma shock wave

The dependence of the mechanics effect to the target induced by laser on laser intensity was reported.The experiments were performed by focusing output pulses of the Nd:YAG laser(10ns pulse width at 1.06 μm wavelength and 42mJ～320mJ pulse energy) on aluminum targets mounted on a ballistic pendulum.The data showed that there were different optimum intensities which gave a maximum Cm at different extant of depart from the focus(χ).And the impulse coupling coefficients(Cm) was determined by similar functions of intensity in the different χ.The Cm increases slowly with the increasing of laser intensity and decreases after it gets maximum quantity.According to the absorption of the plasma and the different laser-target interaction mechanisms at the different χ,the results show that there is the maximum Cm because of the plasma shielding effect;the optimum intensity is largest at the focus because of the effect caused by the rare faction wave and the maximum Cm at χ0 is smaller than the others due to the energy consuming of the air breakdown at the focus.