Observation of a 3D Magnetic Null Point

Magnetoacoustic shock formation near a magnetic null point

Aims. We investigate the interaction of nonlinear fast magnetoacoustic waves with a magnetic null point in connection with the triggering of solar flares. Methods. We model the propagation of fast, initially axisymmetric waves towards a two-dimensional isothermal magnetic null point in terms of ideal magnetohydrodynamic equations. The numerical simulations are carried out with the Lagrangian re...

MHD Mode Conversion around a 2D Magnetic Null Point

Mode conversion occurs when a wave passes through a region where the sound and Alfvén speeds are equal. At this point there is a resonance, which allows some of the incident wave to be converted into a different mode. We study this phenomenon in the vicinity of a twodimensional, coronal null point. As a wave approaches the null it passes from lowto high-β plasma, allowing conversion to take pla...

Charged-particle orbits near a magnetic null point

An approximate analytical expression is obtained for the orbits of a charged particle moving in a cusp magnetic field. The particle orbits pass close to or through a region of zero magnetic field before being reflected in regions where the magnetic field is strong. Comparison with numerically evaluated orbits shows that the analytical formula is surprisingly good and captures all the main featu...

Observation of Bloch-point domain walls in cylindrical magnetic nanowires

null-point method

The rate ofunidirectional efflux of45Ca from rat liver microsomal vesicles loaded with 45Ca and then treated with thapsigargin is not inhibited by increased [Ca2+] in the external medium, although the net efflux rate is substantially inhibited. We have used this property to measure the electrochemical gradient of Ca2+ from the inside to the outside of the vesicles at a series of Ca2+ loadings, ...