Study on sheath formation in astroplasmas under Coriolis force and behavior of levitated dust grains forming nebulon around Moon

Abstract

Pseudopotential analysis has been employed to derive a modified Sagdeev potential-like wave equation for studying the sheath formation in astroplasma problems. Complexity in process urges to derive the new findings numerically by using fourth-order Runge-Kutta method. Main emphasis has been given to investigate the role of Coriolis force on the formation and changes on coherent structures of sheath suitably thought for the configuration of astroplasma. Study determines the sheath thickness and potential variation with the interaction of Coriolis force and thereby finds dynamical behavior of levitated dust grains into the evaluated sheath region. This leads to find the dust size, and corresponding forces generated on dust grain with a view to relate theoretical observations to real astrophysical phenomena and could be of interest to explain formation of dust clouds in spaces. To support the observations, we some thoughtful numeric plasma parameters for the case of Earth's Moon, have taken for graphical presentations. Overall observations expect the study could be of interest as an advanced knowledge in rotating astroplasmas, and expecting many salient features which are yet to be known.

Dynamical behavior of size-graded dust grains levitated in rotating magnetized astroplasmas

“…In order to employ the situation, we first have taken, as a degenerate case, an ideal model of the atmosphere of the Moon without having the effect of the magnetic field. The properties of nonlinear waves as sheath formation have been evaluated expeditiously elsewhere (Das and Chakraborty 2011), and thus we are reluctant to repeat it all, rather the gist will be highlighted to compare with the present observations. The controversial predictions on the evidence of the magnetic field leads to the following additional cases: (i) dynamics in the presence of magnetic fields but no rotational effect and (ii) the effect of both magnetic field and rotation in the dynamics.…”

“…Under this configuration, the basic equations are the equations of continuity and motion supplemented by the Boltzmann distribution of electron density and, following Das and Chakraborty (2011), are written in the following normalized equation:…”

“…To get the observations that also are related to astrophysical problems, we make the crucial approximation of having small amplitude wave with the quasineutrality condition in the plasma. This condition is based on the assumption that the electron Debye length is much smaller than the ion gyro-radius and leads us to derive the ion density (Baishya and Das 2003;Das and Chakraborty 2011) as…”

“…The fourth order Runge-Kutta method has been employed to solve the sheath equation with the initial boundary condition for the wall potential Φ w at the surface (i.e. at ξ = 0) (Das and Chakraborty 2011). We have…”

“…Recently Das and Chakraborty (2011) have shown the characteristic formation of sheath, and dust levitation has been forming a stable dust cloud called a nebulon, showing the influence of the Coriolis force in isolation. But a recent NASA Report (2007) has highlighted the fact that the magnetic field on Moon ranges in 0-100 nano Tesla and hence cannot be ignored; rather proper account of both magnetic field and rotation should be taken.…”