Acoustic modes in a dusty plasma

The propagation of the dust ion acoustic and dust acoustic modes in a dusty plasma is studied. The effect of the coupling of the charge fluctuation on the dust particles to the modes is taken into account self-consistently. It is found that the charge fluctuation leads to frequency down shift as well as dissipation of the modes. For the dust ion acoustic modes, these are significant only when the frequency characterizing the rate of capture of electrons by the dust particles in the equilibrium state is of the order of the frequency of the mode, and the mode can propagate without significant dissipation only when its frequency is well above this characteristic frequency. For the dust acoustic modes, these are significant only when the frequency characterizing the rate of capture of ions by the dust particles in the equilibrium state is of the order of the frequency of the mode, and the mode can propagate without significant dissipation only when its frequency is well above this characteristic frequency.     

Thermally excited modes in a pure electron plasma

Thermally excited plasma modes are observed in near-thermal-equilibrium pure electron plasmas over a temperature range of 0.05相似文献   

Normal modes of a resistive nonuniform plasma

The propagation and dissipation properties of magnetohydrodynamic waves in a nonuniform, highlyconducting plasma, is investigated with a normal mode approach. The interaction between the perturbation and the non-uniform supporting medium is analyzed as the main mechanism able to produce the small scale spatial structure necessary to dissipate efficiently the wave energy. Two fundamental classes of modes are found, characterized by their resistive or ideal asymptotic behavior; the damping rates are shown to be orders of magnitude larger than those obtained when the plasma is perfectly homogeneous, and an application to the problem of solar coronal heating is discussed.Astronomia e Scienza dello spazio, Universitá di Firenze, Italy. Observatoire de Paris-Meudon (DESPA), France. Published in Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 5, pp. 563–579, May, 1994.     

Transverse modes of a relativistic quantum plasma

The dispersion relation for long-wavelength transverse plasma weves propagating in a one-component relativistic quantum plasma is derived from the relativistic Boltzmann-Vlasov equation. The result is consistent with the one obtained from quantum electrodynamics by the method of dielectric response, but at variance with hydrodynamical calculations. The discrepancy is explained by making a distinction between collective and collision dominated plasmas.     

Normal modes of a relativistic quantum plasma; The one-component plasma

The normal modes of a relativistic electron gas are studied on the basis of the Boltzmann-Vlasov kinetic equation via a projection operator formalism. A general framework is constructed in which the fully relativistic Vlasov self-consistent force term appears as a symmetric operator acting in the Hilbert space of one-particle states. The plasma-dynamical equations are obtained by projecting onto the subspace consisting of the charge, energy and momentum densities, plus the nonconserved current density. The eigenmodes of these equations include two transverse and two longitudinal plasma modes, and one damped heat mode. They are explicitly calculated up to second order in the wave vector and to first order in the collision frequency.     

Engineering three-dimensional maximally entangled states for two modes in a bimodal cavity

An alternative scheme is proposed for engineering three-dimensional maximally entangled states for two modes of a superconducting microwave cavity. In this scheme, an appropriately prepared four-level atom is sent through a bimodal cavity. During its passing through the cavity, the atom is coupled resonantly with two cavity modes simultaneously and addressed by a classical microwave pulse tuned to the required transition. Then the atomic states are detected to collapse two modes onto a three-dimensional maximally entangled state. The scheme is different from the previous one in which two nonlocal cavities are used. A comparison between them is also made.     

Generation of zonal flows by interchange modes in a plasma

The generation of zonal flows by flute-like interchange modes in a nonuniform magnetoplasma is considered. The guiding center particle drifts are then used to derive a system of coupled mode equations. The latter are Fourier analyzed to obtain a nonlinear dispersion relation, which exhibits the excitation of zonal flows by the ponderomotive force of the interchange modes. The growth rate of the parametrically driven zonal flows is obtained. Received 26 July 2002 Published online 24 September 2002 RID="a" ID="a"e-mail: ps@tp4.ruhr-uni-bochum.de     

Surface magnetoplasmons in a structure with a two- and three-dimensional plasma

Collective oscillations of a two-component structure consisting of a plasma half-space with a two-dimensional plasma layer at its boundary in the presence of a magnetic field have been studied. Possible variants of the spectra of surface magnetoplasmons have been analyzed for three main mutual orientations of the magnetic field, wavevector, and normal to the surface. The case of the field parallel to the boundary where the frequency is an odd function of the wavevector has been discussed in detail.     

Small amplitude variable charge dust Bernstein-Greene-Kruskal double layers

A first theoretical attempt is made to investigate small amplitude, variable charge dust Bernstein-Greene-Kruskal (BGK) double layers (DLs). The nature of the dust BGK-DLs (compressive or rarefactive), their strength and thickness depend sensitively on the net negative charge residing on the grain surface, the dust grain dynamics and, more interestingly, on the ion-to-electron temperatures ratio.     

Electron eigen-oscillations and ballistic modes of a stable plasma

Relation between the plasma responses on singular and regular initial perturbations is established. Time scaling is introduced that separates periods for which eigen-oscillations (Landau solutions) are dominant from those, where ballistic modes prevail. The enhanced role of the ballistic modes for a plasma initially free of a perturbation field is demonstrated, too, including the phenomenon of plasma waves echoes.     

Observation of arc modes in a magnetically rotating arc plasma generator

An arc plasma can present various forms under the influence of an external magnetic field. In this study, a magnetically rotating arc plasma generator has been developed to produce three arc modes, namely rigid arc, distorted arc, and diffuse arc, which are obtained by controlling the gas flow rate. The evolution of these arc modes are experimentally studied and discussed. Results show that, as the gas flow rate increases, the arc mode is first transformed from the rigid to the distorted mode, and then to the diffuse mode. Comparisons show that the location of the arc attachment is a key factor in determining the rigid and distorted modes. The diffuse arc is observed under larger gas flow rates, but the completely diffuse arc can exist only within a narrow range of gas flow rates. Compared to the distorted arc, the diffuse arc has not only better stability but also a wider high‐temperature plasma zone, which indicates that the diffuse mode may be more useful in industry.     

Nonlinear propagation of ultra-low-frequency electromagnetic modes in a magnetized dusty plasma

A theoretical investigation has been made of nonlinear propagation of ultra-low-frequency electromagnetic waves in a magnetized two fluid (negatively charged dust and positively charged ion fluids) dusty plasma. These are modified Alfvén waves for small value of and are modified magnetosonic waves for large , where is the angle between the directions of the external magnetic field and the wave propagation. A nonlinear evolution equation for the wave magnetic field, which is known as Korteweg de Vries (K-dV) equation and which admits a stationary solitary wave solution, is derived by the reductive perturbation method. The effects of external magnetic field and dust characteristics on the amplitude and the width of these solitary structures are examined. The implications of these results to some space and astrophysical plasma systems, especially to planetary ring-systems, are briefly mentioned. Received 8 July 1999 and Received in final form 11 October 1999     

Neutron excitation of landau and collective modes in a magnetized plasma

Summary The response function for magnetic neutron scattering off electrons forming a one-component plasma, or jellium model, subject to a steady magnetic field, is calculated in the semi-classical limit in which Boltzmann statistics apply to the electron states. A complete expression for the response of an ideal plasma is given in a compact, closed form, amenable to numerical investigation, and including the dependence on electron parameters such as effective mass and gyromagnetic ratio. Effects due to the Coulomb interaction are discussed within the limitations of the random phase approximation. The theoretical results are used to predict the conditions that must obtain for the observation of neutron excitation of Landau and collective modes.

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Riassunto La funzione di risposta per lo scattering magnetico dei neutroni dagli elettroni che forma un plasma ad un componente, o modello di jellio, soggetto ad un campo magnetico fisso, è calcolata nel limite semiclassico nel quale la statistica di Boltzmann si applichi agli stati elettronici. Si dà un’espressione completa per la risposta di un plasma ideale in una forma compatta e chiusa adatta alla ricerca numerica e che include la dipendenza dai parametri elettronici come la massa efficace ed il rapporto giromagnetico. Si discutono gli effetti dovuti all’interazione di Coulomb entro i limiti dell’approssimazione di fase random. I risultati teorici sono usati per prevedere le condizioni che devono essere ottenute dall’osservazione dell’eccitazione dei neutroni di Landau e dei modi collettivi.

     

External helical modes of a solitary current in an unconfined plasma

Siberian Institute of Terrestrial Magnetism, the Ionosphere, and Radio Propagation, Siberian Branch, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 10, pp. 1168–1175, October, 1990.