Physics
Scientific paper
May 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agusmsm43b..03m&link_type=abstract
American Geophysical Union, Spring Meeting 2004, abstract #SM43B-03
Physics
2134 Interplanetary Magnetic Fields, 2154 Planetary Bow Shocks, 2159 Plasma Waves And Turbulence, 2752 Mhd Waves And Instabilities, 2784 Solar Wind/Magnetosphere Interactions
Scientific paper
Gyrating Backstreaming ions displaying gyrophase-bunching around the local magnetic field are frequently observed by the CLUSTER CIS experiment upstream of the Earth's bow shock in association with quasi-monochromatic low-frequency waves. The analysis of the 3D angular distributions indicates that field-aligned beam ions are observed at the onset of each event. Later on, the angular distribution is gyrophase-bunched and peaked at a nearly constant pitch-angle value during the interval of wave occurrence. The waves are left-handed (in the spacecraft frame) and propagate nearly along the ambient magnetic field; we have found that they are fast mode waves in cyclotron resonance with (and likely generated by) the field-aligned beam observed just upstream. By solving the linear Maxwell-Vlasov dispersion relation with the observed parameters as input we confirm that the field-aligned beam drives an ion-ion instability at the observed frequency and wavenumber. Two types of gyrophase-bunched ion events can be observed. For the first type, the pitch-angle distribution is peaked at α 0 ˜ θ BN. This is consistent with specular reflection at the shock and the observed particle flux-modulation is interpreted in term of θ BN changes at the shock due to the low frequency waves. For the second type, the gyrophase bunching is due to the nonlinear coherent disruption of the field-aligned beam by the low frequency waves through cyclotron resonant wave-particle interaction: the pitch-angle α 0 of the ion distribution is explained by a wave-trapping process and is directly dependent on the amplitude of the waves. From a statistical study of their occurrence, we discuss the relative importance of these two mechanisms in the foreshock.
Bosqued J.
Dandouras Iannis
Eastwood Jonathan P.
Le Queau Dominique
Mazelle Christian
No associations
LandOfFree
Gyrophase-bunched Ions and Low Frequency Waves in the Earth's Foreshock: Production Mechanisms does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Gyrophase-bunched Ions and Low Frequency Waves in the Earth's Foreshock: Production Mechanisms, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gyrophase-bunched Ions and Low Frequency Waves in the Earth's Foreshock: Production Mechanisms will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1179425