Recently, Associate Professor Wang Yuliang from the School of Mechanical Engineering of Beijing University of Aeronautics and Astronautics and Academician Detlef Lohse of the University of Twente in the Netherlands have made important progress in the research of laser plasma bubble mechanism.
Associate Professor Wang Yuliang based on advanced micro-nano measurement technology research, carried out research work on disease diagnosis at the cellular level, and explored cell therapy based on plasma effect. Research on plasma bubbles based on continuous green laser pointers has been focused on the time scale of milliseconds -> seconds. In the previous study, the research team revealed the dynamic growth mechanism of this conventional plasma bubble. Based on this, combined with the principle of plasma effect and the heat transfer characteristics of the material, the research team further speculated that on a shorter time scale, there will be more intense dynamic evolution of plasma bubbles.
Using ultra-high-speed cameras with frame rates up to 25MHz, the research team found for the first time in nanosecond measurement resolution that gold nanoparticle-modified materials quickly generate large-sized plasma microbubbles in a short time after laser irradiation. Regardless of its topography or dynamics, this bubble differs from the plasma bubbles typically observed on time scales above milliseconds, which the research team calls initial plasma bubbles. The initial plasma bubble growth rate is 2000 times that of the previously observed plasma bubbles, and at the same time, the growth period is very short, and shrinkage disappears after about several tens of microseconds. The research team further established a model based on thermal diffusion and liquid metastable phase decomposition, and revealed the mechanism of initial plasma bubble generation.
This achievement also reveals the complete evolution of plasma bubbles over a time span of nanoseconds to seconds under continuous green laser pointer illumination. The super dynamic characteristics of the initial plasma bubbles revealed by the institute laid the foundation for the control and application of plasma bubbles.