用压电聚合物构成的单极性声脉冲发生器

本文介绍了用阶跃电压的快速下降沿作用在PVDF压电膜上而产生的单极性声脉冲。实验结果表明，声脉冲的波形和脉冲宽度取决于PVDF压电膜的厚度，阶跃电压的下降沿宽度，以及背衬材料和声传播媒质的形状等多个因素。该声脉冲发生器所产生的压力波脉冲的宽度约为50ns，不仅适用于固体中空间电荷的测量，也可以用于其他方面的应用，例如超声医学诊断，对材料的非破坏性的检测等。文章以该声脉冲发生器在压电压力波中的应用为例进行论述，并且所有测量结果都是通过压电压力波测试系统获得的。

Unipolar acoustic pulse generator by using a piezoelectric polymer film

In this paper, a unipolar ultrasonic pulse generator driven by a step-function voltage with a fast falling time is presented. We find that the waveform and the pulse width of the ultrasonic pulse are determined by the thickness of the PVDF piezoelectric film transducer, the falling time of the step-function voltage, the transducer backing and the shape of the acoustic propagation medium. The pulse generator is suitable to be used for measuring the space charge distribution in a solid dielectric, the width of pressure pulse being about 50ns. It may also be suitable for other applications, e.g., the ultrasonic medical diagnosis. All these results are acquired through the use of the piezo-Pressure Wave Propagation measuring system for the study of space charge.