Vector potential coil and transformer

This study aims to demonstrate a vector-potential coil and a vector-potential transformer that each use a long flexible solenoid wound around a hollow cylinder. These devices generate a curl-free vector potential without magnetic field. In the space within the cylinder where no magnetic field exists, the vector potential is detected by observing a voltage across a secondary conductor that is proportional to the time rate of change of the primary current. The input-output characteristics of the vector-potential transformer and the transparent properties of the vector potential are investigated.