Diamagnetic current does not produce an instability in the solar coronaJ. Vranjes and S. Poedts
Center for Plasma Astrophysics, and Leuven Mathematical Modeling and Computational Science Center (LMCC), Celestijnenlaan 200 B, 3001 Leuven, Belgium
e-mail: [Jovo.Vranjes; Stefaan.Poedts]@wis.kuleuven.be
Received 16 November 2008 / Accepted 12 June 2009
Context. The solar atmosphere contains density irregularities of various sizes embedded in magnetic fields. In the case of a density gradient perpendicular to the magnetic field vector, the plasma supports drift waves that are usually growing as a result of the free energy stored in the density gradient.
Aims. Some basic features of the drift wave are discussed here and, in particular, the gyro-viscosity stress tensor effects and the properties of the diamagnetic drift. Also, the recently proposed “new” instability due to the diamagnetic drift is checked.
Methods. This analysis involves a calculation that considers some terms missing in previous calculations that have appeared in the literature.
Results. It is shown that the diamagnetic drift, which is essential for the recently proposed new physical phenomenon, cannot contribute to the flux in the continuity equation. Moreover, the part of the ion polarization drift contribution to the ion flux cancels out exactly with the contribution of the part of the stress tensor drift to the same flux.
Conclusions. Thus, the ion diamagnetic current does not produce an instability in the solar corona.
Key words: Sun: corona -- waves -- instabilities
© ESO 2009