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Freiburg 2008 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 8: The Sun and Heliosphere II

EP 8.2: Talk

Tuesday, March 4, 2008, 17:00–17:15, KGI-Aula

Proton core heating and beam formation via parametrically unstable Alfvén-cyclotron wavesJaime Araneda1, •Eckart Marsch2, and Adolfo Viñas31Departmento 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.

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