Long-lasting stable cavitation

Stable cavitation is produced on the surface of a special target, i.e., an abrasive foil with a grain size of about 15 Am, insonified by a 473 kHz focused beam. Cavitation bubbles are first created by a pressure of about 2 MPa: Progressive reduction of the pressure to about 100 kPa leads to a state of stable cavitation characterized by strong stable emission of the half-order subharmonic. This state can be maintained-for five hours if the defining parameters (position and pressure) are optimized and constant to within a few percent. There is strong evidence for the presence of "latent" cavitation bubbles, which can persist for a few minutes without being excited. (C) 2003 Acoustical Society of America.