Investigation of laser-induced bubble dynamics in water at high hydrostatic pressures

Hydrostatic pressure is a key factor that influences laser-induced bubble dynamics in water. In this work, we investigated laser-induced bubble dynamics at high hydrostatic pressures up to 53.2 MPa, by using a high-pressure chamber combined with the shadowgraph imaging technique. It was shown that at the atmosphere pressure, the bubble evolution agrees well with the Keller-Miksis model during the free expansion and collapse phase. As the ambient pressure increases, both the size and the oscillation period of the bubble decreases dramatically as a consequence of faster dynamics. The maximum bubble radius, as well as the collapse time, decrease nonlinearly with the increasing pressure; while the pressurization effect on bubble expansion before 100 ns is negligible due to the high internal bubble pressure in the early stage. Time-resolved plasma emission images were also taken with an ICCD camera to illustrate the plasma evolution at high hydrostatic pressures. It was demonstrated that at a high pressure above 40 MPa, the plasma can gain energy from the bubble collapse, while the bubble will lose its energy, which may lead to a shorter collapse time than that obtained from the numerical calculation. This work provides insight into laser-induced bubble dynamics and the plasma-bubble interaction at high hydrostatic pressures.