Near-field electromagnetic tomography applied to current density reconstruction in metallized capacitors

A nonintrusive method of current cartography inside a component is presented. The measurement of the current density in metallized film capacitors has numerous applications, including nondestructive testing, new component design, and validation of existing models on current distribution in capacitors. The method is based upon the measurement of the magnetic field created by a capacitor and the current density reconstruction by means of inverse problem methodology. The experimental setup comprises of a radio-frequency generator operating between 10 to 1000 MHz, a near-field probe, an XY positioning table and a computer used for control and data acquisition. The first results confirm that, near some frequencies, the current density in the capacitor becomes nonhomogeneous and increases dramatically in some areas.