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Indian Journal of Pure & Applied Physics (IJPAP) >
IJPAP Vol.44 [2006] >
IJPAP Vol.44(12) [December 2006] >
| Title: | Generation of kinetic Alfven wave by velocity shear in the plasma sheet boundary layer during substorm |
| Authors: | Tiwari, B V
Mishra, Ruchi
Varma, P
Tiwari, M S |
| Keywords: | Kinetic Alfven wave
Plasma sheet boundary layer
Substorm event
Weak and strong velocity shear
Landau damping
Loss of poynting flux |
| Issue Date: | Dec-2006 |
| Publisher: | CSIR |
| IPC Code: | H05H |
| Abstract: | The kinetic Alfven
wave (KAW) driven by velocity shear in the plasma sheet boundary layer (PSBL)
has been investigated. Expressions for the dispersion relation and growth rate
of the kinetic Alfven wave have been derived for the two regimes separately
i.e., for the case of weak shear and strong shear. It is found that for both
weak and strong shear regimes the resonant electrons act as the main energy
source whereas; the ion longitudinal motion suppresses the instability in case
of the strong shear. The results explain the generation of energetic KAWs in
the PSBL during the substorm onset by the weak velocity shear. As the shear
becomes strong during the substorm the energy of the KAWs is transferred to the
plasma particles through the Landau damping of the wave, which may then lead to
the parallel energisation of the electrons observed recently by Polar
satellite. The loss of the Poynting flux, as observed by Polar and Akebono
satellite, is also explained in terms of the Landau damping of the KAW by the
strong shear of substorm. The temperature anisotropy and density of the plasma
particles enhance the growth rate of shear driven KAW at the onset of the
substorm. |
| Page(s): | 917-926 |
| ISSN: | 0975-1041 (Online); 0019-5596 (Print) |
| Source: | IJPAP Vol.44(12) [December 2006]
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