Research on the axial responses of ECT sensors

ECT sensors can be categorized into three groups according to their axial guard electrode design, i.e. type 1, with earthed ring guard electrodes; type 2, with driven segmented guard electrodes; and type 3, without axial guard electrodes. Projection data corresponding to a column of high permittivity material located at different axial positions are calculated using finite element analysis. Two-dimension cross-images of permittivity distributions are reconstructed using modified Landweber algorithm. The axial responses of the three kinds of ECT sensors are investigated by comparing these reconstructed images. Research results show that the images reconstructed using type 1 sensor have tomography meaning most.