|Date||November 6, 2012||Time||4:00 - 5:00 pm|
|Location||Baylor Sciences Building, Room C.206|
Dr. Oleg F.Petrov
The problems associated with the transport phenomena in dissipative systems of interacting dust particles are of significant interest in various fields of science and technology. The transport coefficients are fundamental parameters that reflect the nature of the inter-particle potentials, and the phase state of the systems.
In the present work dust structures are studied experimentally in dc glow discharge plasmas in mixtures of “light” and “heavy” gases (helium and krypton). Characteristic feature of the dusty plasma structures observed was the formation of linear, chain-like dust structures with strong grain–grain interaction in the ion drift direction. The results of simulations performed for a mixture containing a “heavy”, easily ionized gas suggest a strong effect of gas composition on dust structure formation in discharge plasmas.
Dense dust structures in a dc glow discharge are considered at gas cryogenic temperatures (LN2 and LHe). Results on the experimental investigations of new phenomenon of cryogenic “spheroidizing” were presented. The “spheroidizing” is process of the dust structure transition to compact globular (spherical) shape at cryogenic temperatures.
Experimental study of the kinematic viscosity has been carried out for dust particles of different sizes in weakly ionized plasma. Results of measurements of viscosity for weakly correlated dusty-plasma systems in a wide range of coupling parameters are presented. Comparison of the measured viscosity constants with the theoretical estimations and the numerical data are presented.
For confinement and investigation of strongly coupled Coulomb systems (SCCS) from charged dust particles, we propose to use a trap based on the known possibility of the levitation of diamagnetic bodies in a nonuniform steady-state magnetic field. The SCCS formation from large number (~104) of charged diamagnetic dust particles in a cusp magnetic trap under microgravity conditions has been experimentally studied. The experiments have performed onboard the International Space Station. Using the data of the videorecording of the positions of the particles in the magnetic trap, the magnetic susceptibility and charge of the particles have been estimated. The superhigh charging of dust particles under direct stimulation by an electron beam is experimentally investigated. The energy of beam electrons amounts to 25 keV, with the typical diameter of dust particles employed in the experiment of 100 µm. The charge acquired by a dust particle amounts to 5·107 electron charges, which is more than two orders of magnitude higher than the values of the charge of dust particles in gas discharges.
We have carried out numerical simulations of the lunar plasma-dust exosphere caused by action of solar ultraviolet radiation and the incoming solar wind on the lunar surface. The influence of the solar wind flux on the near-surface photoelectron sheath formation as well as conditions of dust levitation above the lunar surface have been studied.
An original method for the simultaneous recovery of the interparticle interaction potential and the electrostatic confining potential in plasma-dust systems has been developed. The method is based on solving the inverse problem, which describes particle motion by system Langevin equations.
|vCal||Download this event|