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EP: Extraterrestrische Physik

EP 6: Kosmische Strahlung und Heliosph
äre

EP 6.7: Vortrag

Samstag, 5. März 2005, 16:00–16:15, TU BH349

Diamagnetic solar wind ions and their influence on the MHD termination shock conditions — •Hans Fahr and Klaus Scherer — Institut für Astrophysik und Extraterrestrische Forschung

At heliospheric distances covered by the VOYAGER spaceprobes at present it not only is of interest to study the changing particle environments but as well to study changes in the interplanetary magnetic fields. In this respect it is interesting to recognize the up to now forgotten fact that hot ions, especially ions of the pick-up ion type, act in a diamagnetic form on the local magnetic fields by partly compensating the local frozen-in magnetic field due to diamagnetic magnetic moments. We consider this effect in detail and analyse the effect this plasma diamagnetism has on the MHD shock relations considered to be valid at the solar wind termination shock. As it turns out we derive a magnetic field compression ratio which, depending on upstream Alfvenic and sonic Mach numbers of the solar wind flow, differ substantially from the predictions given by the classical MHD shock relations. This new fact may naturally explain why at the most recently claimed shock passage of VOYAGER-1 a change of the particle environments was detected as claimed by the classical theory, but nearly no change in the magnetic field magnitude was found.