Energy density, temperature, and pressure upon generation and collapse of spherical cavitation bubbles in water produced by femtosecond optical breakdown

Optical breakdown and spherical bubble collapse are two different nonlinear mechanisms producing a large energy density within a small spatial region. Extreme states of matter with pressures p up to 107 MPa (100 Megabar) for femtosecond optical breakdown, and temperatures T ranging from 10⁴ up to 10⁸ K for the collapse of bubbles oscillating in a sound field have been reported. However, because of the small spatial and temporal scale on which the extremes occur, it is impossible to directly measure p and T but they have to be inferred from other experimental information and equation of state (EOS) data, which is a challenging task.