Comparative Study on Planetary Magnetosphere in the Solar System

The magnetospheric responses to solar wind of Mercury, Earth, Jupiter and Uranus arecompared via magnetohydrodynamic (MHD) simulations. The tilt angle of each planetary field andthe polarity of solar wind are also considered. Magnetic reconnection is illustrated and explicatedwith the interaction between the magnetic field distributions of the solar wind and the magnetosphere.

Model of driven and decaying magnetic turbulence in a cylinder

Using mean-field theory, we compute the evolution of the magnetic field in a cylinder with outer perfectly conducting boundaries and imposed axial magnetic and electric fields. The thus injected magnetic helicity in the system can be redistributed by magnetic helicity fluxes down the gradient of the local current helicity of the small-scale magnetic field. A weak reversal of the axial magnetic field is found to be a consequence of the magnetic helicity flux in the system. Such fluxes are known to alleviate so-called catastrophic quenching of the α effect in astrophysical applications. A stronger field reversal can be obtained if there is also a significant kinetic α effect. Application to the reversed field pinch in plasma confinement devices is discussed.