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M.L. Khodachenko, G. Haerendel, E. Rieger (MPE, Garching, Germany)
MHD reaction of plasma on the low solar atmosphere to a changing current system of a flaring magnetic tube, containing a beam of fast non-thermal electrons, is studied. We estimate locally the disturbances of a current system of magnetic tube when the beam is injected into it, using the classical idea of a return current. We note that any changes of current density in magnetic tube change the Joule heating and disturb thermodynamical equilibrium of the tube. Heating of plasma destroys as well the force balance and starts the process of a complex dynamics of the whole plasma-magnetic structure. Impulsive character of a beam injection causes two natural stages of dynamical behavior of the tube. In the first one, characterized by the presence of a beam, the preliminary equilibrium state of the magnetic tube is disturbed and the complex dynamics of plasma starts in the region of beam propagation, during the second stage, when injection of the beam is already over, plasma and magnetic field continue to evolve from the disturbed state and gradually relax to the equilibrium state. The dynamical behavior of a magnetic tube is studied on the basis of known self-similar solutions of plasma MHD.
M.L.Khodachenko is grateful to the Max-Planck-Gesellschaft for the research fellowship supporting his work in 1999-2001 years.