Experimental measurements of the coherent field resulting from the interaction of an ultrasonic shock wave with a multiple scattering medium

12th Anglo-French Physical Acoustics Conference

Viard, Nicolas^1 ; Gianmarinaro, Bruno^1 ; Derode, Arnaud^1 ; Barrière, Christophe^1

Institut Langevin, 1 rue Jussieu, 75005 Paris, France^1

关键词: Central frequency;    Ensemble-averaged;    Long-distance propagation;    Multiple-scattering medium;    Scattering medium;    Transmitted field;    Transmitted waves;    Ultrasonic shock waves;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/498/1/012006/pdf
DOI  :  10.1088/1742-6596/498/1/012006

来源: IOP

【 摘 要 】

Whereas multiple scattering and shock wave formation are known to be antagonistic phenomena, this work concentrates on the interaction of an ultrasonic shock wave with a random multiple scattering medium. The shock wave is generated by long distance propagation of a short pulse (4 periods at a 3.5 MHz central frequency) in water before it encounters the scattering medium (a slab-shaped random set of parallel metallic rods). Transmitted waves are recorded over hundreds of positions along the lateral dimension of the slab to estimate the ensemble-averaged transmitted field φ(t), also known as the coherent wave. Experiments are repeated for different thicknesses L of the slab and different emission amplitudes. The elastic mean free path le (i.e the typical distance for the decreasing of the coherent intensity |φ(t)|2due to scattering) is determined as well as the harmonic rate of the averaged transmitted wave. Experimental results are discussed and compared to the linear case.