A Linear Eddy-Current Array Driven by a Whip Excitation
In eddy-current inspection, it is often desirable to use an array of sensors. An array can alleviate problems such as excessive scanning time and difficulties in positioning the sensors. Our “whip” excitation source, a single loop of wire carrying current, is used to excite a workpiece for an eight-sensor array of air-core, inductive, pancake coils. The whip is designed such that it produces an excitation similar to that produced by a single uni-directional wire carrying current. This design is accomplished by forming a loop of rectangular cross-section, placed tangentially to the surface of the test material. Figure 1 shows a conceptual drawing of the whip excitation. Due to its proximity to the test material, the closest side of the whip to the material has a much greater excitation effect than the current’s return path.