Space charge dynamics investigation based on Kerr electro-optic measurements and processing of CCD images
Space charge dynamics investigation based on Kerr electro-optic measurements and processing of CCD images
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DOI：
10.1109/tdei.2013.6508764
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发表时间：
2013-05
影响因子：
3.1
通讯作者：
Jian Shi;Qing Yang;W. Sima;L. Liao;Sisi Huang;M. Zahn
中科院分区：
文献类型：
--
作者：
Jian Shi;Qing Yang;W. Sima;L. Liao;Sisi Huang;M. Zahn
用克尔电光技术研究了克尔常数B_(≈)为1.22×10~(-12)m/V~2的大克尔常数碳酸亚丙酯介质液体的电场和空间电荷效应。然而，提高这项技术测量空间电荷分布的精度仍然是一个重要的目标。本文描述了从克尔测量中获得精确的空间电荷分布的反演算法研究。为了改进计算，将原始的电荷耦合器件(CCD)光强图像转换为灰度值。通过二维傅里叶变换将灰度图像变换到频域。边缘增强算法采用巴特沃斯滤波技术。计算空间电荷分布最重要的参数是由CCD相机测量的明、暗条纹序列中的整数条纹数n。研究了改进算法与传统方法计算不锈钢平行板电极间电场和空间电荷分布的比较。对处理后的CCD图像进行了空间电荷动力学计算，并进行了改进。结果表明，脉冲高压作用初期电场基本均匀。这种均匀性表明，在早期的瞬变间隔中没有空间电荷，而在后来的时间段，在电极之间的中心区域发现了双极电荷注入。随着时间的延长，电场和空间电荷的分布逐渐趋于均匀。灰度处理和巴特沃斯滤波在改进算法以获得更好的图像质量和边缘增强方面发挥了重要作用。
The Kerr electro-optic technique is used to investigate electric field and space charge effects using large Kerr constant propylene carbonate as the dielectric liquid with Kerr constant B≈1.22×10-12 m/V2. However, improved accuracy of this technique to measure space charge distributions remains an important goal. This paper describes inversion algorithm research on obtaining accurate space charge distributions from Kerr measurements. The original charge-coupled device (CCD) image of light intensity was converted into grayscale values for improved calculation. The grayscale CCD image was transformed into the frequency domain through a two-dimensional Fourier transformation. Butterworth filtering techniques were employed for edge enhancement algorithms. The most important parameter for calculation of space charge distributions are the integer fringe numbers n in the sequence of light and dark fringes measured by the CCD camera. Comparison of the improved algorithm and traditional methods for calculating electric field and space charge distributions between a pair of stainless steel parallel plate electrodes was investigated. The space charge dynamics were also calculated after processing the CCD images with some improvements. The results showed the electric field was essentially uniform at early times of pulsed high voltages. This uniformity indicated the absence of space charge during the early transient interval, while a bipolar charge injection was found in the central region between electrodes at later times. For longer times the electric field and space charge distributions slowly became uniform again. Grayscale processing and Butterworth filtering played an important role in the improvement of the algorithm for better image quality and edge enhancement.