Does anyone know how AC magnetic fields behave in 'metallic' magnetic induction tomography (MIT). Do they form a magnetic circuit around a metallic specimen or penetrate through it, or both? This would be in respect of the skin effect limiting the penetration of the AC magnetic driving field (primary).
MIT works by an AC magnetic driving field inducing eddy currents in a metallic specimen (to be imaged) and sensors (coils) on the other side of the specimen picking up the secondary magnetic field due to the eddy currents induced in it. It actually senses or picks up the total field (secondary and primary magnetic fields). Sensor coils measure the spatially distributed total fields to be tomographically represented as an image.