球形腔聚焦换能器是一种特殊形式的聚焦换能器。为理论证实球形腔聚焦换能器能突破传统超声聚焦在聚焦精度和聚焦增益上的限制,采用Westervelt非线性方程并结合时域有限差分法,建立了球形腔聚焦换能器的非线性声场的数值模型。数值计算了直径为120 mm的0.6 MHz球形腔聚焦换能器的非线性声场,并与传统球壳形聚焦换能器进行了对比。当激励声压为100 kPa时,球形腔聚焦换能器与同尺寸壳形聚焦换能器相比,焦点正声压增益提高约8.5倍,且焦域精度更高,-6 dB聚焦区域在z方向减小约20倍,达到次波长尺度。研究表明球形腔聚焦换能器在高强度聚焦超声精细治疗上具有潜在的应用前景。 Spherical cavity focusing transducer is a special form of focusing transducer. In order to prove that the spherical cavity focusing transducer can overcome the limitations of conventional ultrasonic focusing and focusing gain, the Westervelt nonlinear equation and the finite difference time domain method are used to establish the nonlinear acoustic field of the spherical cavity focusing transducer Numerical model. The nonlinear sound field of a 0.6 MHz spherical cavity focused transducer with a diameter of 120 mm is numerically calculated and compared with that of a conventional spherical-shell focused transducer. When the excitation sound pressure is 100 kPa, the spherical cavity focusing transducer has a gain of about 8.5 times the positive sound pressure gain of the focal spot and a higher focusing area accuracy with a -6 dB focusing area at The z-direction is reduced by about 20 times to the sub-wavelength scale. The research shows that spherical cavity focusing transducer has potential application prospect in high intensity focused ultrasound fine treatment.