Control of the Physical and Technical Properties of Water in Technological Processes

The physical and technical properties of water activated by the electrochemical treatment in a two-chamber electrolizer are investigated. The regularities of changes inthe values of acidity, redox potential, ionic composition, concentration of oxygen, structural organization of catholyte and anolyte are revealed. The possibility of controlling the properties of the liquid for more efficient extraction of polymetallic minerals by flotation is described

Quantitative phase analysis of modified hardened cement paste

The relevance of this research is stipulated by the opportunity to control the properties of construction materials through introducing nanomodifying additives. The study of structure parameters of the crystalline phase of hardened cement paste modified by microsilica and Ts38 additives is of great scientific and applied importance

Optical pump–terahertz probe study of HR GaAs:Cr and SI GaAs:El2 structures with long charge carrier lifetimes

The time dynamics of nonequilibrium charge carrier relaxation processes in SI GaAs:EL2 (semi-insulating gallium arsenide compensated with EL2 centers) and HR GaAs:Cr (high-resistive gallium arsenide compensated with chromium) were studied by the optical pump–terahertz probe technique. Charge carrier lifetimes and contributions from various recombination mechanisms were determined at different injection levels using the model, which takes into account the influence of surface and volume Shockley–Read–Hall (SRH) recombination, interband radiative transitions and interband and trap-assisted Auger recombination. It was found that, in most cases for HR GaAs:Cr and SI GaAs:EL2, Auger recombination mechanisms make the largest contribution to the recombination rate of nonequilibrium charge carriers at injection levels above ~(0.5–3)·1018 cm−3, typical of pump–probe experiments. At a lower photogenerated charge carrier concentration, the SRH recombination prevails. The derived charge carrier lifetimes, due to the SRH recombination, are approximately 1.5 and 25 ns in HR GaAs:Cr and SI GaAs:EL2, respectively. These values are closer to but still lower than the values determined by photoluminescence decay or charge collection efficiency measurements at low injection levels. The obtained results indicate the importance of a proper experimental data analysis when applying terahertz time-resolved spectroscopy to the determination of charge carrier lifetimes in semiconductor crystals intended for the fabrication of devices working at lower injection levels than those at measurements by the optical pump–terahertz probe technique. It was found that the charge carrier lifetime in HR GaAs:Cr is lower than that in SI GaAs:EL2 at injection levels > 1016 cm−3.В ст. ошибочно: Irina A. Kolesnikov

Observation of the plasma channel dynamics and Coulomb explosion in the interaction of a high-intensity laser pulse with a He gas jet

We report the first interferometric observations of the dynamics of electron-ion cavitation of relativistically self-focused intense 4 TW, 400 fs laser pulse in a He gas jet. The electron density in a channel 1 mm long and 30 μm in diameter drops by a factor of approximately 10 from the maximum value of ∼8×10 19 cm −3 . A high radial velocity of the plasma expansion, ∼3.8×10 8 cm/s, corresponding to an ion energy of about 300 keV, is observed. The total energy of fast ions is estimated to be 6% of the laser pulse energy. The high-velocity radial plasma expulsion is explained by a charge separation due to the strong ponderomotive force. This experiment demonstrates a new possibility for direct transmission of a significant portion of the energy of a laser pulse to ions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45800/1/11448_2006_Article_813.pd

Pion production under the action of intense ultrashort laser pulse on a solid target

Two-dimensional “particle-in-cell” modeling was carried out to determine the laser intensity threshold for pion production by protons accelerated by the relativistically strong short laser pulses acting on a solid target. The pion production yield was determined as a function of laser intensity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45801/1/11448_2006_Article_1758.pd

On the design of experiments for the study of relativistic nonlinear optics in the limit of single-cycle pulse duration and single-wavelength spot size

We propose a set of experiments with the aim of studying for the first time relativistic nonlinear optics in the fundamental limits of single-cycle pulse duration and single-wavelength spot size. The laser system that makes this work possible is now operating at the Center for Ultrafast Optical Science at the University of Michigan. Its high repetition rate (1 kHz) will make it possible to perform a detailed investigation of relativistic effects in this novel regime. This study has the potential to make the field of relativistic optics accessible to a wider community and to open the door for real-world applications of relativistic optics, such as electron/ion acceleration and neutron and positron production.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45803/1/11452_2005_Article_253.pd