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EP: Fachverband Extraterrestrische Physik
EP 8: Sonne
EP 8.8: Talk
Wednesday, March 28, 2007, 15:45–16:00, H46
high frequency electron/electron modes in solar plasma: linear approach — •kuang wu lee1, nina elkina1,2, and jörg büchner1 — 1Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Str.2, 37191 Katlenburg-Lindau, Germany. — 2M.V. Keldysh Institute for Applied Mathematics Miusskaya sq., 4 Moscow 125047, Russia
RHESSI and the spacecraft observations have shown that during solar flares a large amount of nonthermal electromagnetic radiation is emitted from the corona. This implies the generation of energetic electron beams, eventually radiates X-rays through bremsstrahlung mechanisms. Kinetic turbulence exited by two-electron-streams (current-neutralized) configuration modifies the distribution function and generate emission. We perform parametric studies by means of linear stability analysis in a wide range of possible parameters (density, temperature, velocity ratio). Earlier work in analysis of plasma-beam systems concentrated mainly on a limited one-dimensional case with a highly diluted electron beam, which the maximal linear growth rate of beam-driven mode is parallel to the beam propagation direction (magnetic field). We study the linearly unstable modes of beam-plasma configuration with different densities, and also the general electromagnetic three-dimensional magnetized plasma, i.e. for arbitrary propagation angles, referred to the direction of magnetic field and drift velocity. Different high-frequency modes such as electron-acoustic waves become unstable as well. We discuss the possible role of such instabilities for generating the observed X-ray radiation.