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The physics of dusty plasmas in high magnetic field is an area of current interest, spurred by the development of experiments in this area. Dust acoustic (or dust density) waves have been observed in many laboratory dusty plasmas where there is either no or weak magnetic field. These waves may be excited by the flow of ions relative to dust. The effects of high magnetic field on the excitation of dust waves have been considered in the theoretical literature, including instabilities driven by ions streaming either along or across the magnetic field. We review and extend prior theory work on such instabilities, exploring their behavior as the magnetization of the ions is varied, while the electrons are strongly magnetized and the dust is unmagnetized. It is shown that when the ions are magnetized, there can be structure in the unstable wavenumber spectrum under certain conditions. Application to possible experimental parameters is discussed.

Recently it has been proposed to alter the interaction between dust grains in a plasma by applying ac electric fields to distort the Debye spheres surrounding the grains, which may lead to interaction potentials with a Lennard-Jones form under certain conditions (e.g., Kompaneets et al., Phys. Plasmas 16, 043705 (2009)). Motivated by this, we consider the dispersion relations of longitudinal and transverse waves in a dusty plasma liquid where the grains interact via a Lennard-Jones potential. We use the Quasi-Localized Charge approximation combined with an analytic expression for the pair distribution function for Lennard-Jones fluids (Matteoli and Mansoori, J. Chem. Phys. 103, 4672 (1995)). Possible dusty plasma experimental parameters are considered. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Magnetized Dusty Plasma Experiment (MDPX) device is a newly constructed research instrument for the study of dusty (complex) plasmas. The MDPX device is envisioned as an experimental platform in which the dynamical behavior of all three charged plasma components, the electrons, ions, and charged microparticles (i.e., the ‘dust’) will be significantly influenced by the magnetic force. This brief paper will provide a short overview of the design, magnetic performance, and initial plasma measurements in the MDPX device.

We report experimental observations of a low-frequency (≪ ion gyrofrequency) electrostatic wave mode in a magnetized cylindrical (Q machine) plasma containing positive ions, very few electrons and a relatively large fraction (n−/ne > 103) of heavy negative ions (m−/m+ ≈ 10), and no magnetic field-aligned current. The waves propagate nearly perpendicular to B with a multiharmonic spectrum. The maximum wave amplitude coincided spatially with the region of largest density gradient suggesting that the waves were excited by a drift instability in a nearly electron-free positive ion–negative ion plasma

Drift wave instability in a magnetized plasma composed of positive ions and negative ions is considered using linear kinetic theory in the local approximation. We consider the case where the mass (temperature) of the negative ions is much larger (smaller) than that of the positive ions, and where the gyroradii of the two ion species are comparable. Weak collisional effects are taken into account. Application to possible laboratory parameters is discussed.

In a magnetized plasma containing charged dust whose motion is magnetized, one of the fundamental collective modes that could occur is the electrostatic dust cyclotron (EDC) wave with frequency near the dust cyclotron frequency. The EDC wave propagates nearly perpendicular to the magnetic field with a small parallel wave number, so that it can be driven unstable by ion flow along the magnetic field. Because unstable parallel wavelengths can be relatively large, this places constraints on the plasma device size. In this paper, we use linear kinetic theory to investigate the excitation of higher harmonic EDC waves that have wavelengths smaller than that of the fundamental mode. Collisions of charged particles with neutrals and Coulomb collisions including dust–dust collisions are taken into account. Constraints on possible parameter ranges arising from collisional effects or from requiring stability of other waves are discussed. Numerical results are presented for possible sets of laboratory dusty plasma parameters.

This paper discusses the design of the new Magnetized Dusty Plasma eXperiment (MDPX) device that is currently under construction at Auburn University. This device, which is envisioned to be operated as a multiuser facility, has incorporated many of the features of current dusty plasma experiments that make use of strong magnetic fields while adding new features-such as an extended plasma volume, programmable linear magnetic field gradients, and variable magnetic field geometries-that will greatly extend the operating space of the new device. This paper discusses the physics criteria used to define the operating parameters of the MDPX device and presents a discussion of the initial configuration of the experiment.

We consider theoretically the possible wavelength selective absorption of mid or far infrared radiation in a plasma containing micrometer-sized dust grains having surface phonon resonances in these wavelength regimes. Issues related to grain heating and charging are also discussed.

One dimensional Particle in Cell simulations of a dust- dust counter-streaming instability in a plasma containing dust grains of opposite charge polarity are presented. This dust-dust instability has potentially the lowest threshold drift for a dust wave instability in an unmagnetized dusty plasma. The linear and nonlinear development of the dusty plasma instability is investigated, including the effects of collisions with background neutrals, and a background electric field which acts as a driver to impart the drift velocities of the counter streaming charged dust particles. The saturation of the linear instability appears to be dust heating related to dust trapping. Potential double layer formation from dust-dust turbulence is observed in cases with a high neutral collision rate. A comparative study is done with varying collision rates and background electric fields to explore the nonlinear development as a function of collision rate and background electric field. These simulation results could help guide future laboratory and micro-gravity dusty plasma experiments on this instability. The results could also relate to similar counter-streaming instabilities in pair plasmas and negative ion plasmas

It is generally assumed that negatively charged icy dust particles in the mesosphere are charged by the collection of thermal plasma particles. However, there are some indications that there may be a population of hyperthermal electrons in the D-region under auroral activity under certain conditions (e.g. Margot-Chaker and McNamara, Planetary and Space Science 32, 391, 1984). In this brief communication, we speculate on the effect of a hyperthermal distribution of electrons on dust charging, and how this might affect prevailing turbulence scattering theory for polar summer mesophere echoes.

A strongly coupled Yukawa liquid is a system of charged particles which interact via a screened Coulomb interaction and in which the electrostatic energy between neighboring particles is larger than their thermal energy but not large enough for crystallization. Various plasma systems including ultracold neutral plasmas and complex (dusty) plasmas can exist in this strongly coupled liquid phase.Here we investigate instabilities driven by the relative streaming of plasma components in three-dimensional Yukawa liquids with a focus on complex plasmas. This includes a dust acoustic instability driven by weakly coupled ions streaming through the dust liquid, and a dust-dust instability driven by the counter-streaming of strongly coupled dust grains. Compared to the Vlasov behavior we find there can be a substantial modification of the unstable wavenumber spectrum due to strong coupling effects (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The effect of radial boundaries on the ion-dust streaming instability is investigated. Possible applications of our work to certain low-temperature dusty plasma experiments are discussed.

Ion waves excited by charged dust beams streaming across or along the geomagnetic field in the ionosphere may be generated by plasma instabilities during aerosol release experiments. The injection speed of the dust and gas is comparable to or larger than the ion thermal speed in the background plasma. The dust grains can get charged by plasma collection from the ambient ionosphere, and can thus act as a charged beam that excites instabilities in the background plasma. The theory is applied to relatively early time scales of the order of ∼0.1–1s in the dust–gas cloud expansion, with wave frequencies that are larger than the ion gyrofrequency, and collisions with neutrals are included.

We present a kinetic theory analysis of the electrostatic ion cyclotron (EIC) instability in a plasma containing positive ions, electrons, and negative ions that are much more massive than the positive ions. Conditions are investigated for exciting the fundamental and the higher harmonic EIC waves associated with each ion species. We find that as the concentration of heavy negative ions increases, the wave frequencies increase, the unstable spectrum in general shifts to longer perpendicular wavelengths, and the growth of higher harmonic EIC waves tends to increase within certain parameter ranges. Applications to possible laboratory plasmas are discussed.

In this paper, we use Mie theory to investigate the temperature-dependent emissivity of small particles composed of a fusion device relevant metal, lithium. We also use classical electromagnetic theory to estimate the high temperature emissivity of flat surfaces of liquid lithium and several metals, such as beryllium, being considered as plasma facing components in fusion devices. We use a Drude theory model for the temperature dependence of the optical constants of the metals. The results may have application to modeling or diagnosing the temperature of various metallic components in fusion environments.

Recently, the sputtering of fast meteoroids by impinging atmospheric particles, and the subsequent interaction of the sputtered material with the atmosphere, has been proposed to explain the meteor luminosity observed at high altitudes. In this brief communication, we consider the possibility of a lower hybrid instability driven by the ionized component of the material sputtered from a fast large meteoroid at high altitudes.

In this work we analyze the size (radius) distribution function of dust particles in tokamak plasmas during a steady state discharge. A relation between the radius distribution function of dust in the plasma and the radius distribution of dust injected from tokamak walls is obtained using a Green's function formalism. Numerical simulations of the dust radius distribution function in a tokamak plasma with the Dust Transport (DUSTT) code are used to obtain the analytical form of the Green's function semi-empirically. It is demonstrated that the Green's function obtained can be used to predict qualitatively the dust size distributions in the tokamak plasmas. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Recently, there has been interest in the properties of strongly coupled dusty plasmas in the liquid phase. Here, we consider theoretically a possible way to generate and detect a dense dusty plasma liquid. The idea is to use noble metal submicron dust particles and detect the dust by scattering at the surface plasmon resonance frequency of the dust. Parameters that may be relevant to possible laboratory dusty plasma experiments are discussed.

The ion-acoustic instability in a dusty negative ion plasma is investigated, focusing on the parameter regime in which the negative ion density is much larger than the electron density. The dynamics of the massive dust grains are neglected, but collisions of electrons and ions with dust grains in addition to other collisional processes are taken into account. The presence of a population of charged dust can change the frequency of the fast wave, lead to additional damping due to ion–dust collisions, and change the conditions for wave growth. Applications to dusty negative ion plasmas in the laboratory and in space are discussed.

We report comparative studies on collective excitations in 2-D complex plasmas, in which particles interact through the Yukawa potential, encompassing both the solid and the strongly coupled liquid states. Dispersion and polarization of the collective modes in the solid state are calculated through the lattice summations, while in the liquid state, through molecular dynamics (MD) simulations in conjunction with the theoretical quasi-localized charge approximation analysis. The latter closely emulates the dispersion, resulting from an angular averaging in the lattice. In general, however, the lattice dispersion is substantially different from that of the liquid. The MD simulations show the dramatic transformation of the anisotropic phonon dispersion of the crystal lattice near the solid-liquid transition into the isotropic liquid dispersion

The beam-plasma instability displays new properties when either the beam or the plasma, or both, are strongly interacting. We have considered theoretically the case when the plasma is in the crystalline phase and forms a lattice, and the beam is moving in the lattice plane. We consider a 2-D plasma crystal in which both the grains and the beam particles interact through a realistic Yukawa potential. The beam particles are assumed to be weakly coupled to each other and to the lattice. Using the full phonon spectrum for a 2-D hexagonal Yukawa lattice, we determine and compare the transverse and longitudinal growth rates. The relationship between the beam speed and the longitudinal and transverse sound speeds, and the direction of the beam with respect to the principle axes of the lattice determine the qualitative behavior of the growth rates. For beam speeds between the longitudinal and transverse sound speeds, the transverse instability could be more important, because it appears at lower wavenumbers

The understanding of the theoretical structure of phonon dispersion in Yukawa lattices and the relationship between these perfect lattice phonons on the one hand, and the excitations in the disordered and liquid states on the other, is an important issue in analysing experimental and simulation results on plasma crystals. As the first step in this programme, we have numerically calculated the full phonon spectrum for 2D triangular Yukawa lattices, for a wide range of κ (screening parameter) values and along different propagation angles. Earlier calculations of the excitation spectra of the 2D and 3D Yukawa liquids were based on the quasilocalized charge approximation (QLCA), whose implicit premise is that the spectrum of an average distribution (governed by the isotropic liquid pair correlation function) is a good representation of the actual spectrum. To see the implications of this model more clearly, we compare the high r (near crystallization) QLCA phonon spectra with the angle-averaged phonon spectra of the lattice phonons.

Various interactions can play a role between the mesoscopic dust grains of a complex plasma. We study a system composed of dust grains that have both an electric charge and a permanent magnetic dipole moment. It is assumed that the grains occupy lattice sites, as dictated by their Coulomb interaction. In addition, they possess a spin degree of freedom (orientation of magnetic dipole moment) that is not constrained by the Coulomb interaction, thus allowing for the possibility of equilibrium orientational ordering and 'wobbling' about the equilibrium orientations. As a result, collective modes develop. We identify in-plane and out-of-plane wobbling modes and discuss their dispersion characteristics both in the ferromagnetic and in the anti-ferromagnetic ground state.

The well-known problem of beam–plasma instability acquires new aspects when one or both of the two components (the beam and the plasma) are strongly interacting. We have now theoretically considered the case when the plasma is in the solid phase and forms a lattice. In this situation, the inherent anisotropy of the lattice leads to a coupling between the longitudinal and transverse polarizations. One of the novel features of the beam–plasma instability in this scenario is the possible excitation of transverse modes, which should be an experimentally observable signature of the instability. We have initially concentrated on a 2D toy model with the beam lying in the lattice plane. At the same time, we have initiated a molecular dynamics simulation program for studying various aspects of the penetration of a beam into a plasma lattice. The beam parameters can be adjusted in order to see the effects of increasing coupling strength within the beam and to distinguish between collective phenomena and scattering on individual particles. When both components are strongly interacting, a number of remarkable phenomena—trapping of beam particles, creation of dislocations, local melting of the lattice—may be observed.

The conventional Vlasov treatment of beam-plasma instabilities is inappropriate when the plasma is strongly coupled. In the strongly coupled liquid state, the strong correlations between the dust grains fundamentally affect the conditions for instability. In the crystalline state, the inherent anisotropy couples the longitudinal and transverse polarizations, and results in unstable excitations in both polarizations. We summarize analyses of resonant and non-resonant, as well as resistive instabilities. We consider both ion-dust streaming and dust beam-plasma instabilities. Strong coupling, in general, leads to an enhancement of the growth rates. In the crystalline phase, a resonant transverse instability can be excited.

The use of dust plasma crystals as filters of electromagnetic waves in the far-infrared or submillimeter wavelength regime is investigated theoretically. The analysis is based on previous analyses of crystalline colloid array filters that make use of dynamical diffraction theory coupled with theory for electromagnetic wave scattering from small spheres. Theoretical bandwidths, attenuation factors, and limits on wave intensity are considered.

Theoretical studies of dusty plasmas have been performed by focusing attention principally on collective phenomena and on grain motion. This thesis consists of a collection of seven published papers that explore both the collective behavior of a complex plasma system as well as the dynamics of grains in plasmas. In paper 1, a mechanism that explains the energy gain which leads to the self excited grain oscillations is theoretically formulated. The newly developed mechanism explains the observed self excited oscillations through the coupling of plasma sheath fluctuations with the electrostatic force, which holds the dust grain. In paper 2, theoretical and simulation studies have been conducted to study the vertical oscillations of dust grains that are levitated in plasma sheaths, under low pressure conditions. The oscillations were driven either by an external force or by a plasma number density modulation. The proposed model gives a full picture of the dust grains dynamics and is capable of successfully explaining the experimental observations. Paper 3 explores both theoretically and numerically the origin of the nonlinearities that lead to the observed oscillation resonances. The feature of the confining potential well which traps the grain, the influence of an electrode voltage modulation on the trapping well, and hence on the grain dynamics, and the resulting nonlinear resonances are analyzed in detail. The numerical simulations presented successfully reproduce a broad range of dynamical phenomena, including the self excited oscillations, for a range of different parameters. Paper 4 is dedicated to the analysis of the propagation of Dust Acoustic Waves (DAW) in a medium with an equilibrium dust density distribution. It has been theoretically shown that only some harmonics of the dust density distribution will influence the propagation of the DAW, thus modifying its frequency. Paper 5 presents a theoretical and numerical analysis of the excitation of higher harmonics of electrostatic dust cyclotron waves. The instability is driven by the ion and electron currents flowing along the magnetic field. The dispersion relation and the wave instability conditions have been derived, and a detailed numerical analysis has been performed. In Paper 6, we explore theoretically some cross field instabilities of low frequency, long wavelength electrostatic modes in fully and weakly ionized plasmas. It is shown that in a magnetoplasma with a transverse equilibrium dc electric field, the energy associated with the cross field motion of the plasma particles can be coupled to low frequency electrostatic waves. Paper 7 explores the properties and instabilities of low frequency electrostatic waves propagating in a current carrying magnetoplasma with equilibrium density and field aligned ion flow with a transverse gradient. The paper contains previous results as limiting cases, together with additional instabilities related to the equilibrium plasma density distribution.

In this paper, we consider theoretically conditions for forming crystals of positively charged dust, when the dust is heated by a laser or by a strong infrared source and emits electrons thermionically. We discuss parameters for grains dispersed in an inert gas at pressure of a few mbar. We briefly discuss levitation by forces associated with gas flow or photon flux. A possible experimental scheme for achieving such a crystal is briefly outlined.

The use of ultraviolet (UV) radiation to reduce the negative charge on dust particles and modify force balance in particle traps in processing plasmas is investigated theoretically. Possible photophoresis associated with the UV flux is also discussed. The use of UV to facilitate moving contaminant particles from traps is considered.

The Magnetized Dusty Plasma Experiment at Auburn University has been operational for over one year. In that time, a number of experiments have been performed at magnetic fields up to B = 2.5 T to explore the interaction between magnetized plasmas and charged, micron-sized dust particles. This paper reports on the initial results from studies of: (a) the formation of imposed, ordered structures, (b) the properties of dust wave waves in a rotating frame, and (c) the generation of plasma filaments.

A previous model for secondary electron emission from small grains is modified to calculate yields for micron sized grains, both spherical and cylindrical, when the primary electrons constitute a high energy parallel beam. It is found that, in general, the secondary electron yield is significantly higher than for the case of normal incidence. Moreover, the equilibrium potentials of the grain are always positive due to this enhanced secondary emission. These results are compared with experimental data recently available for micron sized glass particles, and equilibrium potentials, calculated based on the model presented here, and are found to be in reasonably good agreement with their measured potentials. >

It is shown that, for a moderately long time scale, two‐body collisions can actually help in maintaining a non‐Maxwellian ion velocity distribution in a plasma. This effect occurs when the ions have orbits large enough to transit spatial regions with different physical parameters in a single collision time. The effect is applied to ions confined in a spherically convergent ion focus (SCIF), where collisions at the edge of a spherical potential well help maintain convergent non‐Maxwellian flow in the rest of the device.

A brief, critical review of dust-plasma interactions in the cosmic environment is presented, with emphasis on certain results. Both single-particle (e.g., gravitoelectrodynamics) and collective (e.g., appearance of new wave models) effects are discussed and some areas in which further research is needed are pointed out. The pressing need for laboratory studies, both to provide the necessary data for the theoretical studies and to test the predictions of these theories, is emphasized. >

金沢大学理工研究域電子情報学系, Influence of thermal radiation emissivity on the lifetime of a dust particle in plasmas is investigated for different fusion relevant metals (Li, Be, Mo, and W). The thermal radiation is one of main cooling mechanisms of the dust in plasmas especially for dust with evaporation temperature higher than 2500 K. In this paper, the temperature- and radius-dependent emissivity of dust particles is calculated using Mie theory and temperature-dependent optical constants for the above metallic materials. The lifetime of a dust particle in uniform plasmas is estimated with the calculated emissivity using the dust transport code DUSTT [A. Pigarov, Physics of Plasmas 12, 122508 (2005)], considering other dust cooling and destruction processes such as physical and chemical sputtering, melting and evaporation, electron emission etc. The use of temperature-dependent emissivity calculated with Mie theory provides a longer lifetime of the refractory metal dust particle compared with that obtained using conventional emissivity constants in the literature. The dynamics of heavy metal dust particles are also presented using the calculated emissivity in a tokamak plasma. © 2008 American Institute of Physics.

Conditions are investigated for forming a Coulomb lattice of dust grains which are charged positively by the ultraviolet induced photoemission of electrons. >

Heavy negatively charged ions have recently been detected at relatively high altitudes in the ionosphere of Titan, and it has been suggested that perhaps they are supported by electric fields. In this short communication, we discuss the possibility of ion-acoustic instability in this environment.

Secondary dust density waves were observed in conjunction with high amplitude (nd/nd0>2) dust acoustic waves (DAW) that were spontaneously excited in a dc glow discharge dusty plasma in the moderately coupled, Γ∼1, state. The high amplitude dust acoustic waves produced large dust particle oscillations, displacements, and trapping. Secondary dust density waves were excited in the wave troughs of the high amplitude DAWs. The waveforms, amplitudes, wavelengths, and wave speeds of the primary DAWs and the secondary waves were measured. A dust-dust streaming instability is discussed as a possible mechanism for the production of the secondary waves.

Ion-dust streaming instability in a plasma containing dust grains with large thermal speeds is considered using kinetic theory. The results are compared with experimental measurements of the dispersion relation of dust acoustic waves performed at the University of Iowa and Auburn University.

The determination of dust radius distributions from the measurement of laser scattering intensity in tokamaks is presented. The analysis takes into account non-Rayleigh regimes of light scattering for different complex refractive indices of dust materials, as well as dust evaporation due to heating by laser radiation. The model is applied to calculate the dust particle radius distribution in tokamaks during normal plasma operation. It is shown that a relatively small amount of large dust particles in the distribution may play a significant role for estimation of the dust mass inventory in tokamaks.