Nonlinear focal shift beyond the geometrical focus in moderately focused acoustic beams.

摘要: The phenomenon of the displacement position along axis pressure, intensity, and radiation force maxima focused acoustic beams under increasing driving voltages (nonlinear focal shift) is studied for case a moderately beam. theoretical experimental results show existence this shift when initial pressure in transducer increases until field reaches fully developed nonlinear regime propagation. Experimental data that at high amplitudes moderate focusing, on-axis maximum can surpass geometrical length. On contrary, minimum approaches voltages, distance between positive negative peak These are agreement with numerical KZK model predictions existed other authors be explained according to effect self-refraction characteristic