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Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas with magnetic fields up to 1.5 T. Plasmas were formed between a powered bottom electrode and a grounded top electrode in which an aluminum wire mesh is fixed in the center. This work will examine the experimental conditions at which imposed, ordered structures form within the dusty plasma. These imposed, ordered structures, as reported in earlier works, are characterized by the alignment of dust particles to the spatial structure of the wire mesh in the top electrode and occur at high magnetic fields (B ≥ 1 T) and low neutral pressure (P ≤ 100 mTorr). A pair of parameters will be established to characterize the degree to which the dust particles are affected by these imposed ordered structures on both long and short time scales. Using these parameters, it will be shown that a correlation exists between the onset of imposed, ordered structures and the magnetization of ions within the plasma.Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas with magnetic fields up to 1.5 T. Plasmas were formed between a powered bottom electrode and a grounded top electrode in which an aluminum wire mesh is fixed in the center. This work will examine the experimental conditions at which imposed, ordered structures form within the dusty plasma. These imposed, ordered structures, as reported in earlier works, are characterized by the alignment of dust particles to the spatial structure of the wire mesh in the top electrode and occur at high magnetic fields (B ≥ 1 T) and low neutral pressure (P ≤ 100 mTorr). A pair of parameters will be established to characterize the degree to which the dust particles are affected by these imposed ordered structures on both long and short time scales. Using these parameters, it will be shown that a correlation exists between the onset of imposed...

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.

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.

Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas at magnetic fields up to 2.5 T where the electrons and ions are strongly magnetized. Plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper electrode supports a dual mesh consisting of #24 brass and #30 aluminum wire cloth. In this experiment, we study the formation of imposed ordered structures and particle dynamics as a function of magnetic field. Through observations of trapped particles and the quasi-discrete (i.e., “hopping”) motion of particles between the trapping locations, it is possible to make a preliminary estimate of the potential structure that confines the particles to a grid structure in the plasma. This information is used to gain insight into the formation of the imposed grid pattern of the dust particles in the plasma.

Dusty plasmas have been studied in argon, rf glow discharge plasmas at magnetic fields up to 2 T, where the electrons and ions are strongly magnetized. In this experiment, plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper, electrically floating electrode supports a semi-transparent, titanium mesh. We report on the formation of an ordered dusty plasma, where the dust particles form a spatial structure that is aligned to the mesh. We discuss possible mechanisms that may lead to the formation of the “dust grid” and point out potential implications and applications of these observations.

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.