刚性球形微粒在超声波聚焦区内的散射

声散射问题的研究一般建立在入射波为平面波的基础上。而在医学诊断和工业无损检测领域中广泛采用的是超声聚焦换能器，因此有必要进行聚焦区内的散射场分析。以凹球面超声换能器为研究对象，假设聚焦区存在一刚性球形微粒，对此时的散射场进行分析。通过分析聚焦声场的特性，得到了聚焦区附近的瞬时声压表达式。建立了散射边界条件，并运用柱函数的加法定理，通过理论推导得到了聚焦区内刚性球形微粒的散射声压表达式。最后对其散射远场声压的空问分布特性进行了数值计算。

ACOUSTIC SCATTERING BY THE SOLID SPHERE IN ULTRASONIC FOCAL AREA

Previous research on acoustic scattering was generally on the premise that the incident waves were plane waves. Ultrasonic focusing transducer was widely applied in the field of medical diagnosis and nondestructive testing, and it was necessary to analyze the scattering characteristic of the focusing area. On the assumption that there was a small solid sphere in the focusing area, the scattering field of concave sphere ultrasonic transducer was analyzed. The expression for instantaneous pressure near the focusing area was obtained by analyzing the characteristic of focusing acoustic field. After the scattering boundary conditions were set up, the scattering pressure expression of the solid sphere in the focusing area was derived by column function addition theorem. Finally, the space distribution characteristic of scattered far-field pressure was calculated and plotted numerically.