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EP: Extraterrestrische Physik
EP 4: Magnetosph
ären und Plasmen
EP 4.7: Vortrag
Dienstag, 19. März 2002, 12:35–12:50, HS 15
Proton pitch-angle diffusion rate and mirror wave turbulence in the Earth’s magnetosheath — •Claudia-Veronika Meister1, Mikhail Pudovkin2, Bruno Besser3, Wolfgang Baumjohann3, Svetlana Zaitseva2, Valentina Lebedeva2, and A. Maulini2 — 1Space Plasma Physics, Potsdam, Germany — 2St. Petersburg State University, Russia — 3Space Research Institute, Graz, Austria
Various models of the proton temperature anisotropy evolution and the problem of the proton pitch-angle diffusion rate are discussed for the case of the plasma across the Earth’s magnetosheath. The value of the characteristic relaxation time of the proton temperature anisotropy is estimated from experimental data. The obtained values need a theoretical explanation, which is at present greatly embarrassed by the absence of a sufficiently developed non-linear theory of the plasma wave turbulence. It is shown that the obtained values of the relaxation time have a tendency to decrease with the increase of the intensity of the magnetic field oscillations. Besides the relaxation time is found to depend on the intensity of mirror-wave-like turbulence, which is in accordance with the supposition by Hill et al. [J. Geophys. Res, 1995, 100, 9575] on a significant role of mirror waves in the pitch-angle scattering of protons in the magnetosheath plasma. Further it is shown that observed periods of abnormally low values of the temperature anisotropy in some cases correspond to the periods of relatively high intensive magnetic field oscillations which have most probably an external origin.