title: Covert cavitation: Spectral peak suppression in the acoustic emissions from spatially configured nucleations.
abstract: Dual laser-nucleation is used to precisely configure two cavitation bubbles within a focused ultrasound field of f0= 692 kHz, in proximity to the tip of a needle hydrophone. With both bubbles responding in the f0/2 sub-harmonic regime, confirmed via ultra-high speed shadowgraphic imaging, an emission spectrum with no sub-harmonic content is demonstrated, for an inter-bubble spacing ≈λ0. A spectral model for periodic shock waves from multiple nucleations demonstrates peak suppressions at nf0/2 when applied to the experiment, via a windowing effect in the frequency domain. Implications for single-element passive detection of cavitation are discussed.
authors.affiliation: Cavitation Laboratory (CavLab), Medical and Industrial Ultrasonics, School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom JaeHee.Song@glasgow.ac.uk, k.johansen.1@research.gla.ac.uk, Paul.Prentice@glasgow.ac.uk.
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Song
authors.affiliation: Cavitation Laboratory (CavLab), Medical and Industrial Ultrasonics, School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom JaeHee.Song@glasgow.ac.uk, k.johansen.1@research.gla.ac.uk, Paul.Prentice@glasgow.ac.uk.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Johansen
authors.affiliation: Cavitation Laboratory (CavLab), Medical and Industrial Ultrasonics, School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom JaeHee.Song@glasgow.ac.uk, k.johansen.1@research.gla.ac.uk, Paul.Prentice@glasgow.ac.uk.
authors.forename: Paul
authors.initials: P
authors.lastname: Prentice