Freiburg 2008 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 8: The Sun and Heliosphere II
EP 8.2: Vortrag
Dienstag, 4. März 2008, 17:00–17:15, KGI-Aula
Proton core heating and beam formation via parametrically unstable Alfvén-cyclotron waves — Jaime Araneda1, •Eckart Marsch2, and Adolfo Viñas3 — 1Departmento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Chile — 2Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany — 3Nasa/Goddard Space Flight Center, Greenbelt, MD, USA
Vlasov theory and one-dimensional hybrid simulations are used to study the effects that compressible fluctuations driven by parametric instabilities of Alfvén/cyclotron waves have on proton velocity distributions. Field-aligned proton beams are generated during the saturation phase of the wave-particle interaction, with a drift speed which is slightly greater than the Alfvén speed and is maintained until the end of the simulation. The main part of the distribution becomes anisotropic due to phase mixing as is typically observed in the velocity distributions measured in the fast solar wind. We identify the key instabilities and also find that even in the parameter regime where fluid theory appears to be appropiate strong kinetic effects still prevail.