[charlie]

The voltage displayed in the A-scan is the probe voltage measured during the acquisition phase to which is applied gain. The behavior is different to that of a coil discharge as what is measured is the response of the inspected component itsekf.

The A-scan has two distinct phases, the first phase is best described as a power law. During this phase, the eddy currents diffuse as if they were in an infinite wall. The signal comes from the component surface and weather jacket. This phase shows as a rapid drop on a log-lin scale.

During the second phase, the signal comes from the bulk of the material. This portion of the signal is best described s an exponential decay and is characterized by a decay time (best known as CDT). On the A-scan log-lin scale, this phase is shown as a slope.

If you would like to know more on Pulsed Eddy Current, you may reach out to me at [email protected] or enjoy a free introduction course to Pulsed Eddy Current on the Eddyci academy available here: https://academy.eddyfi.com/free-courses