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Author: Fortov, V. E. ×

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    Dynamic vortex dust structures in a nuclear-track plasma
    ([London] : IOP, 2003) Rykov, V. A.; Khudyakov, A. V.; Filinov, V. S.; Vladimirov, V. I.; Deputatova, L. V.; Krutov, D. V.; Fortov, V. E.
    Results are presented from Monte Carlo calculations of the electric charge on dust grains in a plasma produced during the slowing down of radioactive decay products of californium nuclei in neon. The dust grain charging is explained as being due to the drift of electrons and ions in an external electric field. It is shown that the charges of the grains depend on their coordinates and strongly fluctuate with time. The time-averaged grain charges agree with the experimental data obtained on ordered liquid-like dust structures in a nuclear-track plasma. The time-averaged dust grain charges are used to carry out computer modelling of the formation of dynamic vortex structures observed in experiments. Evidence is obtained for the fact that the electrostatic forces experienced by the dust grains are potential in character. The paper is supplemented by a video clip showing the typical dynamics of the simulated vortex dust structure.
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    Dynamics of dust grains in an electron-dust plasma induced by solar radiation under microgravity conditions
    ([London] : IOP, 2003) Fortov, V. E.; Nefedov, A. P.; Vaulina, O. S.; Petrov, O. F.; Dranzhevski, I. E.; Lipaev, A. M.; Semenov, Yu. P.
    In this paper the results of experimental investigation of the dynamic behaviour of macroparticles charged via photoemission are presented. The experimental data have been obtained for bronze particles subjected to solar radiation under conditions of microgravity (on board the Mir space station). The distribution of velocity, temperatures and charge, as well as the friction coefficient and diffusion constants, have been found. The analysis of the results obtained has shown that the polarization effects of opposite charges may appreciably influence the transport processes in a two-component electron-dust plasma, consisting of positively charged dust and emitted electrons.
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    Self-excited motions in dusty plasmas with gradient of charge of macroparticles
    ([London] : IOP, 2003) Vaulina, O. S.; Samarian, A. A.; Petrov, O. F.; James, B. W.; Fortov, V. E.
    Various self-excited motions in dusty plasmas involving spatial variations of macroparticle charge are considered. Two basic types of instabilities in these systems are examined numerically and analytically. The main attention is given to the vortex motions of macroparticles. Conditions suitable for creating the instabilities examined are discussed. Experimental observations of self-excited oscillations in dc-glow, and capacitive rf, discharges are presented. It is shown that spatial variation of dust charge can account for many phenomena observed in inhomogeneous laboratory dusty plasmas.
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    The dynamics of macroparticles in a direct current glow discharge plasma under micro-gravity conditions
    ([London] : IOP, 2003) Nefedov, A. P.; Vaulina, O. S.; Petrov, O. F.; Molotkov, V. I.; Torchinskii, V. M.; Fortov, V. E.; Chernyshev, A. V.; Lipaev, A. M.; Ivanov, A. I.; Kaleri, A. Yu.; Semenov, Yu. P.; Zaletin, S. V.
    The dynamics of large-sized (70-180 μm) spherical bronze particles in a direct current glow discharge plasma was studied experimentally under microgravitation conditions. The temperatures, velocities, pair correlation functions and self-diffusion coefficients of macroparticles were measured at various discharge currents. The charges of dust particles (on the order of 106 e) corresponded to high surface potentials of about 30-40 V.
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    Formation and behaviour of dust particle clouds in a radio-frequency discharge: Results in the laboratory and under microgravity conditions
    ([London] : IOP, 2003) Mikikian, M.; Boufendi, L.; Bouchoule, A.; Thomas, H. M.; Morfill, G. E.; Nefedov, A. P.; Fortov, V. E.; PKE-Nefedov Team
    In this paper we report the first observation on submicron dust particle clouds grown in a radio-frequency sputtering discharge under microgravity conditions. These results have been obtained in the PKE-Nefedov (Plasma Kristall Experiment) chamber in the framework of a French-German-Russian programme. A dust-free region, usually called the 'void', is observed in the laboratory and under microgravity conditions even with submicron particles. In this region, successive generations of particles can be grown, leading to the coexistence of particles with various sizes. Each generation of particles constitutes a cloud separated from the others by a definite sheath. Dynamics of these clouds have been investigated showing vortex-like motions or independent behaviour of small heaps of particles, emphasizing both attractive and repulsive effects between dust clouds. As these particles drastically influence the plasma properties, the growth kinetics is followed through the evolution of the discharge current.