Energetic Cavitation Collapse

Abstract

The collapse of a spherical cavity in liquid can focus energy in space and time, generating extreme thermodynamic states and emitting light and a strong shock wave. Such events, generally at the micro-scale, are of interest in diverse applications including ultrasonic cleaning and drilling, medical lithotripsy, and sono-chemistry. However, detailed measurements of the stagnation event are typically precluded by its sub-micron size and picosecond time scale, and it is poorly understood.

In this dissertation a new method is presented for generating controlled, symmetric cavitation collapse at arbitrary scale, and employed to drive a millimeter scale vapor bubble in water at over 20 bar of pressure. This leads to an optically accessible event with energy one million times greater than typically achieved in the laboratory. Direct time resolved diagnostic measurements are consistent with numerical simulation and reveal a stagnation plasma over 20 microns in radius at a temperature well above 10,000 K and an unprecedented pressure above one million atmospheres. Such conditions are found at the center of giant planets such as Jupiter. This result opens a new opportunity for the study of dynamically compressed materials, high energy density plasmas, and the fundamental dynamics of energetic spherical implosions.