Toroidal vector-potential transformer

• Main Author: Daibo, Masahiro
• Format: Conference Proceeding
• Language: English
• Subjects: component; Conductors; Electric potential; Electro-magnetic Shield; Integral equations; Magnetic fields; Magnetic flux; Solenoids; Toroidal; Transformer; Vector-potential; Wounds
• ISSN: 2156-8073
• DOI: 10.1109/ICSensT.2017.8304422

We investigated the characteristics of a triple coil comprising a very long, thin, flexible solenoid coil wound around a hollow toroid. In ordinal magnetic-toroidal coils, the current flows in the poloidal direction, generating magnetic field in toroidal direction, but in our vector-potential coil, the magnetic flux flows in the poloidal direction, generating a vector-potential in the toroidal direction. A flexible solenoid was used as a primary coil and an alternating current was applied to it. The hollow toroid is made of brass and its wall thickness is thicker than the skin depth in the test-frequency range. Therefore, the brass hollow toroid functions as an electromagnetic shield. In the space inside the brass hollow toroid, a secondary coil was placed to form a transformer. Since the flexible solenoid does not generate a magnetic field outside of it and electromagnetic shielding is provided between the primary coil and the secondary coil, there is no magnetic field at all in the place where the secondary coil was placed. When an alternating current was applied to the primary coil, a voltage proportional to the time derivative of the primary current was observed in the secondary coil. We provide a theory for the design of this transformer.