Shock waves in laser-pulse-irradiated metals

In an earlier paper [1] the temperature as a function of time and distance from the surface of a metal after the application of a laser pulse had been calculated. The assumption was made that only heat conduction is responsible for the dissipation of energy provided that the input fluence of the laser pulse is below the threshold for ablation. In this investigation an estimate for the pressure in the shock wave as a function of time and distance is presented. The assumption mentioned above is valid up to an input fluence of about φ=10 mJ/cm². For larger fluences (but below the ablation threshold) a correction for the dissipation of acoustic energy must be applied. The effect of surface evaporation on T_max and p_max of metals with high melting point is discussed. With fast pulses and/or relatively low velocities of sound, maximum pressures p_max of the shock wave are calculated which are higher than the corresponding stationary values (see (4)). Received: 27 April 2000 / Final version: 6 June 2000 / Accepted: 8 June 2000 / Published online: 13 September 2000