Author:
POKHOTELOV O. A.,ONISHCHENKO O. G.,SHUKLA P. K.,STENFLO L.
Abstract
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.
Publisher
Cambridge University Press (CUP)
Cited by
7 articles.
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