Probing the Limits of Cavitation, Sonoluminescence, and Mechanoluminescence

Abstract : The overall goal in this research proposal was to probe the limits of acoustic cavitation and sonoluminescence to develop a fundamental understanding of the nature of acoustic cavitation at its most extreme. We specifically explored the consequences of the shockwaves internal to the collapsing bubble produced during cavitation. This convergent shockwave generates a high temperature plasma inside the bubble, which is optically opaque and only from whose outer surface may one see emission (i.e., the plasma line emission observed during SBSL in ionic liquids (e.g., concentrated sulfuric acid). We completed time-resolved SBSL spectroscopic studies and have demonstrated the rise and fall of internal temperature during the formation of a plasma inside a collapsing bubble on a sub-ns timeframe. In addition, we made unsuccessful attempts to find evidence for the formation of X-rays created during cavitation using nanoscale scintillators to down-convert X-rays to visible light emitters.