Recoil pulse under conditions of nonstationary surface evaporation of water

Acoustic disturbances, arising when a pulse of electromagnetic radiation is observed in the surface layer of water, are studied experimentally and theoretically. The nonstationary equations of heat conduction for a liquid with a moving evaporation boundary and the equations of gas dynamics for the expanding vapor are solved simultaneously taking into account the counterpressure and jumps in the parameters of the vapor in the Knudsen layer. The acoustic signal associated with the recoil pulse of the vapor turned out to be much longer than the electromagnetic radiation pulse. The dependence of the maximum pressure on the incident energy density has a threshold piecewise-linear character for the experimental conditions studied. A quantitative comparison of the computed and experimentally determined amplitudes and forms of the acoustic signal is made.