Response of a dusty plasma system to external charge perturbations

The excitation of nonlinear wave structures in a dusty plasma caused by a moving external charge perturbation is examined in this work, which uses a 1-D flux corrected transport simulation. The plasma responds uniquely to different nature of the moving charge, depending on which, for small amplitude perturbations, pinned envelope solitons are generated and electrostatic dispersive ion-acoustic shock waves are formed for a large amplitude perturbation. The presence of dust particles is found to suppress the formation of dispersive shocks at low velocity of the external charge debris. The results are also investigated theoretically as a solution to the generalized Gross-Piteavskii equation, which broadly supports the simulation results.Comment: 19 pages, 11 figure

The possibility of hypersonic electrostatic solitons in a plasma with turbulence heating

Here, we show that electrostatic solitons in a plasma with turbulent heating of the electrons through an accelerating electric field, can form with very high velocities, reaching up to several order of magnitudes larger than the ion-sound speed. We call these solitons hypersonic solitons. The possible parameter regime, where this work may be relevant, can be found the so-called ``dead zones'' of a protoplanetary disk. These zones are stable to magnetorotational instability but the resultant turbulence can in effect heat the electrons make them follow a highly non-Maxwellian velocity distribution. We show that these hypersonic solitons can also reach very high velocities. With electron velocity distribution described by Davydov distribution function, we argue that these solitons can be an effective mechanism for energy equilibration in such a situation through soliton decay and radiation.Comment: 12 pages, 5 figure

Driven dust-charge fluctuation and chaotic ion dynamics in the plasma sheath and pre-sheath regions

Possible existence of chaotic oscillations in ion dynamics in the sheath and pre-sheath regions of a dusty plasma, induced by externally driven dust-charge fluctuation, is presented in this work. In a complex plasma, dust charge fluctuation occurs continuously with time due to the variation of electron and ions current flowing into the dust particles. In most of the works related to dust-charge fluctuation, theoretically it is assumed that the average dust-charge fluctuation follows the the plasma perturbation, while in reality, the dust-charge fluctuation is a semi-random phenomena, fluctuating about some average value. The very cause of dust-charge fluctuation in a dusty plasma also points to the fact that these fluctuations can be driven externally by changing electron and ion currents to the dust particles. With the help of a \emph{hybrid}-Particle in Cell-Monte Carlo (\emph{h}-PIC-MCC) code in this work, we use the plasma sheath as a candidate for driving the dust-charge fluctuation by periodically exposing the sheath-side wall to UV radiation, causing photoemission of electrons, which in turn drive the dust-charge fluctuation. We show that this \emph{driven} dust-charge fluctuation can induce a chaotic response in the ion dynamics in the sheath and the pre-sheath regions.Comment: 16 pages, 11 figure

Thermal instability of an expanding dusty plasma with equilibrium cooling

We present an analysis of radiation induced instabilities in an expanding plasma with considerable presence of dust particles and equilibrium cooling. We have shown that the equilibrium expansion and cooling destabilize the radiation condensation modes and the presence of dust particles enhances this effect. We have examined our results in the context of ionized, dusty-plasma environments such as those found in planetary nebulae (PNe). We show that due to the non-static equilibrium and finite equilibrium cooling, small-scale localized structures formed out of thermal instability, become transient, which agrees with the observational results. The dust-charge fluctuation is found to heavily suppress these instabilities, though in view of non-availability of convincing experimental data, a definitive conclusion could not be made.Comment: 23 pages, 14 figure

Plasma Dynamics

Contains table of contents for Section 2 and reports on two research projects.Princeton University/National Spherical Torus Experiment Grant S04020G PPPLU.S. Department of Energy Grant DE-FGO2-91-ER-54109National Science Foundation Grant ECS 94-24282Los Alamos National Laboratory Grant No. E29060017