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Information × Registration Number 0221U102577, 0116U005034 , R & D reports Title Formation of nanostructures and kinetic processes in condensed helium at low and ultralow temperatures popup.stage_title Head Sokolov Sviatoslav S, д.ф.-м.н. Registration Date 05-02-2021 Organization B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine popup.description2 A new quantum mechanism of solid 3He creep is revealed when the temperature decreases to 0.2 K, when the thermoactivation dependence of the creep rate of 3He crystals changes to temperature-independent, which can be explained by the transition to a new type of substance motion associated with tunneling potential barriers. New results on nuclear magnetization and 3He diffusion processes in the pores of the MSM-41 nanostructured material with a channel size of 25 nm were obtained by pulsed NMR. Two limited diffusion processes have been identified, in which the diffusion coefficients differ by an order of magnitude and which correspond to two different layered phases, formed in a narrow channel. The flow of liquid 4He excited by oscillations of a quartz tuning fork in the conditions of transition from laminar to turbulent mode of fluid motion has been studied. For the first time, the frequency dependence of the attached mass of a liquid was established, and the contribution of ballistic and multiple scattering of phonons on quantized vortices to the flow resistance coefficient was observed. For the first time, the nonlinear mode of tuning fork oscillations was investigated using the Duffing equation. New effects have been discovered in the study of fluid flow in superfluid solutions 3He - 4He with a concentration of 3He up to 15 %. The contributions of viscous friction, the first and second sounds to the dissipative processes that accompany the movement of the tuning fork in the liquid solution have been established. Temperature dependences of the critical velocity of transition between laminar and turbulent fluid flow for hydrodynamic fluid motion are obtained. For the first time in modeling in a numerical experiment of systems from several charge lines, characteristic oscillation frequencies in the system were found. The frequency values coincide well with the theoretical laws of dispersion of plasma modes obtained by the method of equations of motion. Product Description popup.authors popup.nrat_date 2021-02-05 Close