Ion Anisotropy-Driven Waves in the Earth'S Magnetosheath and Plasma Depletion Layer
- J. L. Burch and
- J. H. Waite Jr.
Published Online: 18 MAR 2013
Copyright 1994 by the American Geophysical Union
Solar System Plasmas in Space and Time
How to Cite
Denton, R. E., Anderson, B. J., Fuselier, S. A., Gary, S. P. and Hudson, M. K. (1994) Ion Anisotropy-Driven Waves in the Earth'S Magnetosheath and Plasma Depletion Layer, in Solar System Plasmas in Space and Time (eds J. L. Burch and J. H. Waite), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM084p0111
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1994
Print ISBN: 9780875900414
Online ISBN: 9781118663851
- Solar wind;
- Space plasmas;
Recent studies of low-frequency waves (ω ≤ Ω p , where Ω p is the proton gyrofrequency) observed by AMPTE/CCE in the plasma depletion layer and magnetosheath proper are reviewed. These waves are shown to be well identified with ion cyclotron and mirror mode waves. By statistically analyzing the transitions between the magnetopause and time intervals with ion cyclotron and mirror mode waves, it is established that the regions in which ion cyclotron waves occur are between the magnetopause and the regions where the mirror mode is observed. This result is shown to follow from the fact that the wave spectral properties are ordered with respect to the proton parallel beta, β∥p . The later result is predicted by linear Vlasov theory using a simple model for the magnetosheath and plasma depletion layer. Thus, the observed spectral type can be associated with relative distance from the magnetopause. The anisotropy-beta relation, Ap ≡ (T ⟂/T ∥) p − 1 = 0.85β∥p −0.48, results from the fact that the waves pitch angle scatter the particles so that the plasma is near marginal stability, and is a fundamental constraint on the plasma.