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相控阵在聚焦超声治疗应用中不可避免地受到非线性影响,提出了采用高斯叠代法计算相控阵的非线性声场。在该方法中,利用预设焦点参数并应用伪逆矩阵算法得到阵元的激励参数;然后将阵元近似拟合成一组高斯声束的叠加,通过高斯声束叠代计算非线性声场。数值计算中以64阵元一维相控阵为研究对象;线性条件下,高斯叠代法结果与菲涅耳积分结果的误差低于0.5%,验证了该方法的可行性;单焦点及双焦点模式的相控阵非线性声场结果表明非线性效应能提高焦点聚焦性能,并且非线性效应与激励声压及激励频率成正比。
Phased array in the application of focused ultrasound inevitably affected by the nonlinear, the use of Gaussian iterative method to calculate the nonlinear phased array sound field. In this method, the excitation parameters of the array element are obtained by using the preset focus parameters and the pseudo-inverse matrix algorithm. Then the array elements are approximated to a superposition of a set of Gaussian beam and the nonlinear sound field is calculated by Gaussian beam iteration. In the numerical calculation, the 64-element one-dimensional phased array is taken as the research object. Under the linear condition, the error between Gauss iteration method and Fresnel integral is less than 0.5%, which verifies the feasibility of this method. The focus mode phased array nonlinear field results show that the nonlinear effect can improve the focusing performance, and the nonlinear effect is proportional to the excitation sound pressure and excitation frequency.