Application of Real Time Inverse Eddy Current Analysis

Abstract

Rapid reduction of multifrequency eddy current data to direct material properties of conductivity and dimension has been a task for a number of years by Wallace et al. (1) and Seigfried (2,3). The direct solution of the electromagnetic boundary value problem and fitting data to experimental data can be accomplished but is slow and tedious(4,5,6). The direct solution approach has a slow cycle time and reduces both the spontaneous interaction of the operator to the test in progress and the resulting understanding of the process. The inverse approach of taking the raw eddy current data and producing physical data rapidly opens two possibilities for the measurement technique. In the area of process development and in difficult environments such as crystal growers, chemical reactors or heat treatment furnaces. It is possible to detect and stimulate transient events and isolate these reaction rapidly. Extending this application to automated operation one can use the resulting inverse data for control particularly in temperature measurement, where there is a conductivity dependence on temperature.