High intensity ultrasound waves from a strongly focused circular source

• Autorzy: Kamakura T. , Akiyma M.
• Języki publikacji: EN

Abstrakty

EN

To verify the effectiveness of the spheroidal beam eguation (SBE) [J.Acoust. Soc.Am. 107, 3035-3046 (2000)] that is promisingly applicable to a theoretical pre-diction of strongly focused nonlinear beams, experiments are carried out in water using a 1.6MHz focused transducer with a circular aperture of 73mm in diameter and a focal length of 75mm. The aperture half-opening angle becomes 29o, which exceeds the upper limit of the applicability of the KZK model eguation. At the maximum, peak pressure attains about lOMPa at the focus. For such intense waves, the pressure levels of the first three harmonics are in fairly good agreement with the theory. The focused source is highly excited by a sinusoidal tone-burst signal with. three periods to study nonlinear propagation of an ultrasonic pulse. For such a transient wave, the SBE theory agrees well with experiments. Significant distortion appears in the direct wave than the edge wave in the post-focal region, in particular, for the wave passing through a sheet of silicone rubber near the focus.

• Wydawca: Polskie Towarzystwo Akustyczne. Oddział Gdański
• Czasopismo: Hydroacoustics
• Rocznik: 2001
• Tom: Vol. 4
• Strony: 109--118
• Opis fizyczny: Bibliogr. 10 poz., rys.

Twórcy

autor

Kamakura T.

• The University of Electro-Communications l-S-l, Chofugaoka, Chofu-shi, Tokyo 182-8585, Japan

autor

Akiyma M.

• The University of Electro-Communications l-S-l, Chofugaoka, Chofu-shi, Tokyo 182-8585, Japan

Bibliografia

• 1. M. F. Hamilton and C. L. Morfey, "Model equations," in Nonlinear Acoustics, edited by M. F. Hamilton and D. T. Blackstock (Academic Press, Calif.,1998), Chapt.
• 2. J. Naze Tjotta, S. Tjotta, and E. H. Yefring, "Effects of focusing on the nonlinear inter-action between two collinear finite amplitude sound beams," 1. Acoust, Soc. Am. 89,1017-1027 (1991).
• 3. B. Ystad and J. Berntsen, "Numerical solution of parabolic equations for strongly curved focusing sources," ACUSTICA • acta acustica 82, 698-706 (1996).
• 4. T. Kamakura, T. Ishiwata, and K. Matsuda," Model equation for strongly focused finite-amplitude sound beams," J.Acoust.Soc.Am. 107,3035-3046(2000).
• 5. T. Kamakura, K. Aoki, and T. Ishiwata, "Nonlinear propagation of focused ultrasound beams from a wide-angle aperture,"ACUSTICA • acta acustica 86, 446- 456 (2000).
• 6. B. Ystad and J. Bemtsen, "Numerical solution of the KZK equation for focusing sourees," acta acustica 3, 323-330(1995).
• 7. T. S. H art and M. F. Hamilton," Nonlinear effects in focused sound beams," J.Acoust.Soc.Am. 84,1488-1496 (1988).
• 8. M. F. Hamilton, "Comparison of three transient solutions for the axial pressure in a focused sound beam," J. Acoust. Soc. Am. 92, 527-532 (1992).
• 9. H. Hobrek and B. Ystad," Experimental and numerical investigation of shock wave propagation in the post focal region of a focused sound field," ACUSTICA • acta acustica 83, 978-986 (1997).
• 10. J. D. Ryder, P. H. Rogers, and J. Jarzynski,"Radiation of difference-frequency sound generared by nonlinear interaction in asilicone rubber cylinder," J. Acoust. Soc. Am. 59,1077-1086 (1976).