应用改进脉冲电声法的空间电荷波形恢复技术

An Improved Technique for the Space Charge Distribution Recovery on the Basis of the PEA Measurement

脉冲电声法(pulsed electro-acoustic,PEA)测量信号因压力波的衰减与色散,传感器与外电路的滤波作用而产生畸变。介质内部体电荷产生的相对较弱信号会受到电极–介质界面处面电荷的干扰。现有信号恢复技术由于无法得到可靠的高频区压力波衰减与色散因子,其只能处理低频范围内的PEA信号。采用频率幂函数规律和时间因果理论,得到了适用于较宽频带范围的衰减与色散因子;同时,构造出除去界面面电荷对体电荷信号干扰作用的新反卷积方程,采用结合后验停止规则的迭代正则化ν方法求解该反卷积方程。通过对低密度聚乙烯PEA信号的恢复处理,验证了该文提出的改进方法。

The pulsed electro-acoustic （PEA） signal is distorted by the attenuation and dispersion of the pressure wave, and filtered by the transducer and external circuit. The weak signals produced by the internal volume charges can be interfered by the surface charges at the contacts. Existing recovery techniques are incapable of processing the signals with high frequency components due to the unreliable attenuation and dispersion factors. In this paper, the frequency power law and the time causal theory were utilized to obtain reliable attenuation and dispersion data in a wide spectrum. A new deconvolution equation is proposed, which removes the influence imposed by the surface charges at the contact on the internal volume charges. The iterative regularization v method with a posteriori stopping rule was employed to solve the new deconvolution problem. The validity of the improved recovery technique was verified by its application to the PEA signal recovery of low density polyethylene （LDPE）.