Characteristic of probe coil systems for the application of the pulsed eddy current techniques

In relation to applications of the pulsed eddy current techniques the essential features of probe coil systems are evaluated by measurements on test specimen with artificial defects. For cracklike defects which are open to the surface of testing the characteristic of the signal voltage as a function of the crack depth and the local resolution for defects that are close together are typical qualities which determine the field of application of a coil device. As characterizing parameter the use of the effective coil width is discussed. The explanations are completed by some examples of practical applications. (orig.)