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University of New Hampshire

Coronal Mass Ejection Research Group

2004

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New Theoretical And Observational Results On Transverse Magnetic Fluctuations Near The Magnetopause, G. Gnavi, Charlie J. Farrugia, F. T. Gratton Dec 2004

New Theoretical And Observational Results On Transverse Magnetic Fluctuations Near The Magnetopause, G. Gnavi, Charlie J. Farrugia, F. T. Gratton

Coronal Mass Ejection Research Group

Electromagnetic ion cyclotron waves in the plasma depletion layer measured by Wind on three inbound passes of the magnetosheath near the stagnation streamline are modeled using theoretical results from Gnavi et al., J. Geophys. Res., 105, 20973, 2000. The kinetic dispersion relation in a plasma composed of electrons, protons, and alpha particles, is solved with each species modeled by a bi-Maxwellian distribution function with parameters taken from observations, where available, and from average values found in the literature. While one pass was under substantially high solar wind dynamic pressure (~ 6.4 nPa), the other two passes were under normal dynamic …


On The Mhd Boundary Of Kelvin-Helmholtz Stability Diagram At Large Wavelengths, F. T. Gratton, G. Gnavi, Charlie J. Farrugia, L. Bender Dec 2004

On The Mhd Boundary Of Kelvin-Helmholtz Stability Diagram At Large Wavelengths, F. T. Gratton, G. Gnavi, Charlie J. Farrugia, L. Bender

Coronal Mass Ejection Research Group

Working within the domain of inviscid incompressible MHD theory, we found that a tangential discontinuity (TD) separating two uniform regions of different density, velocity and magnetic field may be Kelvin-Helmholtz (KH) stable and yet a study of a transition between the same constant regions given by a continuous velocity profile shows the presence of the instability with significant growth rates. Since the cause of the instability stems from the velocity gradient, and since a TD may be considered as the ultimate limit of such gradient, the statement comes as a surprise. In fact, a long wavelength (lambda) boundary for the …