A Toy Model for Magnetic Field Configurations in Black Hole Accretion Discs

We discuss the feature of the magnetic field configuration arising from double counter oriented electric current-rings in the accretion disc around a Kerr black hole (BH). We discuss the relevant physical quantities corresponding to this configuration: (1) the power and torque transferred by the large-scale magnetic field, (2) the angular momentum and energy fluxes transferred from the BH to the inner disc, (3) the radiation flux from the disc. In addition, we discuss the possibility that the closed magnetic field anchored at the disc probably evolves to the open magnetic field, which is helpful to produce the jet from the disc.