A post-MHD for the solar atmosphereA post-MHD for the solar atmosphere
Faculty of Sciences. Physics
Department of Physics
Physics of Chromospheric Plasmas
Coimbra Solar Physics Meeting on the Physics of Chromospheric Plasmas, OCT 09-13, 2006, Univ Coimbra, Coimbra, PORTUGAL
368(2007), p. 193-196
University of Antwerp
In magnetohydrodynamics (MHD) one neglects the displacement current, which is usually an excellent approximation. However, when dealing with fast phenomena (often small ones) this displacement current plays a role. Using Callebaut's exact solution of the MHD evolution equation, one may verify the approximation by using Maxwell's equations to calculate the displacement current and the charges associated with it. An example is given. An iteration may yield a further improvement. This post-MHD may be particularly relevant in connection with work by Callebaut and Karugila, showing that the accumulation of some small oscillations (however, including the nonlinear terms) may lead, in narrow strips to very large, even divergent, velocities leading to turbulence and thus reducing the MHD dissipation time. This may explain the short explosion times for flares, CMEs, etc.