We investigate the heating of the quiet corona by measuring the increase of coronal luminosity with the amount of magnetic flux in the underlying network at solar minimum when there were no active regions on the face of the Sun. The coronal luminosity is measured from Fe ix/x–Fe xii pairs of coronal images from SOHO/EIT, under the assumption that practically all of the coronal luminosity in our...

In magnetic resonance electrical impedance tomography (MREIT), we try to reconstruct a cross-sectional resistivity (or conductivity) image of a subject. When we inject a current through surface electrodes, it generates a magnetic field. Using a magnetic resonance imaging (MRI) scanner, we can obtain the induced magnetic flux density from MR phase images of the subject. We use recessed electrode...

We investigate the origin of the matching effect observed in superconducting Nb films containing regular arrays of holes near the zero-field critical temperature. We find “dips” in the resistance vs magnetic field curves at matching fields where the magnitude of the magnetic flux threading each unit cell is an integer number of the flux quantum. By comparing the magnetic field dependences of th...

We present non-linear mean-field α dynamo simulations in spherical geometry with simplified profiles of kinetic α effect and shear. We take magnetic helicity evolution into account by solving a dynamical equation for the magnetic α effect. This gives a consistent description of the quenching mechanism in mean-field dynamo models. The main goal of this work is to explore the effects of this quen...

Ca II H emission is a well-known indicator of magnetic activity in the Sun and other stars. It is also viewed as an important signature of chromospheric heating. However, the Ca II H line has not been used as a diagnostic of magnetic flux emergence from the solar interior. Here we report on Hinode observations of chromospheric Ca II H brightenings associated with a repeated, small-scale flux em...

INDEX OF SYMBOLS B Magnetic flux density (Tesla) c Speed of light ≈ 3×10 m/s Co Capacitance per unit length (F/m) Em Magnetic energy storage (Joules) H Magnetic field intensity (A/m) I Current (A) J Current density (A/m) K Surface current density (A/m) Lo Inductance per unit length (H/m) L Inductance (H) N Coil turns R Reluctance (A-turns/Wb) Φ Flux (Weber) λ Flux linkage (Weber-turns) εo Permi...

We present a study on fractional flux periodicity of the ground state in planar systems made from a square lattice whose boundary is compacted into a torus. The ground-state energy and persistent currents show a fractional period of the fundamental unit of magnetic flux depending on the twist around the torus axis. We discuss the possible relationship between the twist and genus of a torus. The...

We demonstrate that the inclusion of the helicity flux in the magnetic helicity balance in the nonlinear stage of galactic dynamo action results in a radical change in the magnetic field dynamics. The equilibrium value of the large-scale magnetic field is then approximately the equipartition level. This is in contrast to the situation without the flux of helicity, when the magnetic helicity is ...