Eddy Current Induced in a Finite-Length Tube by a C-Core Sensor in Arbitrary Axial Position

The enhanced truncated region eigenfunction expansion (enhanced TREE) method is employed to derive an analytical model of a finite-length metal tube tested by a C-core coil in an arbitrary axial position. The vector potential and the coil impedance variation are calculated. To develop an efficient algorithm, the 1-D finite element method (1-D FEM), vector normalization, and Clenshaw-Curtis quadrature are integrated. To improve the computation performance of the complex eigenvalues with large imaginary parts, a coordinate transformation technique is implemented within the Arnoldi iteration. The efficacy of the proposed approach is validated by comparing the theoretical predictions with experimental results.