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Drift–Alfvén vortices in dusty plasmas with non-zero ion-temperature effects

Published online by Cambridge University Press:  29 May 2001

O. A. POKHOTELOV
Affiliation:
Institute of Physics of the Earth, 123810 Moscow, Russia
O. G. ONISHCHENKO
Affiliation:
Institute of Physics of the Earth, 123810 Moscow, Russia
P. K. SHUKLA
Affiliation:
Institut für Theoretische Physik IV, Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
L. STENFLO
Affiliation:
Department of Plasma Physics, Umeå University, S-90187 Umeå, Sweden

Extract

Reduced two-fluid equations governing the nonlinear dynamics of drift–Alfvén waves in dusty plasmas with non-zero ion temperature are derived. In the linear limit, we find a dispersion relation that shows the coupling between the ion-drift–Shukla–Varma mode, and electron-drift (magnetostatic) and (inertial or kinetic) Alfvén waves due to the finite collisionless electron skin depth or Larmorradius corrections. In contrast to the case of an electron–ion plasma, when the nonlinear drift–Alfvén vortices are weakly localized, i.e. decrease at infinity as r−1, the presence of the charged dust grains makes exponential localization possible. The physical meaning of such a localization is connected with the fact that charged massive dust granules provide an additional screening that results in stronger localization of the vortex. In several intermediate-β plasmas with 1 [Gt ] β [Gt ] me/mi (me,i is the electron or ion mass), the localization length approaches a minimum value when the vortex velocity is of the order of the ion diamagnetic drift. It then reaches the value ρiδ−1/4d where ρi is the ion Larmor radius and δd is the ratio of the dust to ion densities multiplied by the dust charge number Zd. In the case of very low plasma pressure, β [Lt ] me/mi, the vortex is localized with typical scale (λeρi)1/2δ−1/4d where λe is the electron skin depth. Our investigation can thus predict the velocities of coherent nonlinear structures in space plasmas.

Type
Research Article
Copyright
© 2000 Cambridge University Press

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