Berlin 2005 – wissenschaftliches Programm
EP 1.3: Vortrag
Freitag, 4. März 2005, 10:30–10:45, TU BH349
Solitary waves in ion-beam plasmas: Application to CLUSTER foreshock observations — •Konrad Sauer and Eduard Dubinin — Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
Hall-MHD solitons have recently been studied in a single-ion plasma with respect to the interpretation of No-dqmagnetic holesNo-dq. In case of oblique propagation to the ambient magnetic field they appear in the No-dqgap regionNo-dq of the phase velocity versus wavenumber diagram, in which only evanescent waves (k2<0) exist. In plasmas with two or more ion populations the picture becomes more complex, and a new type of stationary, nonlinear wave appears which has a soliton-type structure superimposed by spatial oscillations (No-dqoscillitonsNo-dq). If a beam is present, both types of stationary waves may develop from the linearly unstable configuration. In addition, the soliton/oscilliton profiles may experience significant modifications of their basic structure if one of the wave modes of the multi-ion plasma is in resonance with the nonlinear wave. As consequence, strongly rippled solitary structures may be generated. Analysis of the magnetic field and plasma data from the CLUSTER spacecraft measurements shows that a great variety of coherent wave events can be isolated which seem to belong to different classes of solitary waves found in searching stationary, nonlinear solutions of the Hall-MHD equations of an ion-beam plasma system. It has been found that the polarization of the measured waves is of great significance for their classification. Arc-polarization ,e.g., arises if a No-dqbrightNo-dq and No-dqdarkNo-dq soliton merge due to coupling with a beam.