Self-action of ultrasonic beams for biological applications

Theoretical and experimental investigations of powerful ultrasonic beams se lf-focusing in liquids are described. Calculations of the conditions to obs erve self-action as a result of sound-induced heating of liquids are report ed. The effects of controlled self-action of ultrasonic waves in high-visco sity liquids are demonstrated in experiments. A hydrodynamic mechanism of t he acoustic dispersion technique is developed. The rate of this process, as a function of ultrasound intensity, including the effects of self-focusing and self-transparency, is evaluated. (C) 1999 Elsevier Science B.V. All ri ghts reserved.