The reactivity of titanium–vanadium containing groups in the synthesis of two-component monolayers on silica surfaces

The coating of silica surfaces with two-component VOCl₃ and TiCl₄ monolayers was studied with respect to the composition of the products and the kinetics of interaction. The titanium and vanadium-containing groups were found to be able to replace each other equivalently. Surface sites were found to determine reactivity, as were lateral interactions in the monolayer. The results found the presence of two kinds of active center; with the estimated ratio of such groups correlating with data from chemical analyses of the concentrations of groups covalently linked to the surface by different numbers of bonds.     

Minimization of Diffraction Losses in Big Gaps of Multi-Mode Waveguides

A systematic approach to design of low-loss miter bends and quasi-optical gaps in multi-mode waveguides is proposed. Several examples illustrate the approach. A mode filter based on a quasi-optical gap in the 31.75 mm diameter corrugated waveguide at frequency 84 GHz has been tested in low (mW) and high-power (200 kW, CW) experiments.     

AFM application for in situ study of adsorption processes

Comparison of calculated and experimental data allows us to assume the following mechanism of H₂O adsorption in dynamic conditions at high temperature: during the adsorption of the first portions of sorbate on the silica gel surface, the thin film of water overlaps the access to intrapore space and the adsorption proceeds only on the exterior surface of the sorbent. The text was submitted by the authors in English.     

NEW FREQUENCY STEP-TUNABLE ECRH SYSTEM FOR ASDEX UPGRADE

A new broadband ECRH (Electron Cyclotron Resonance Heating) system is currently under construction at the ASDEX Upgrade tokamak. This system will employ multi-frequency gyrotrons step-tunable in the range 105–140 GHz. In its final stage the system will consist of 4 gyrotrons with a total power of 4 MW and a pulse length of 10 s. It employs a fast steerable launcher for feedback controlled deposition that allows for poloidal steering of 10° within 100 ms. Transmission line elements, such as corrugated waveguides, polarizer mirrors and vacuum windows, are designed to cope for this frequency band.     

Determination of the Mode Content in Spurious Microwave Radiation of the Gyrotron with a Straight Axisymmetric Output

The method for determination of the mode content of a spurious microwave radiation of the gyrotron with a straight circular axisymmetrical output is discussed. As demonstrated, in the test task accuracy of this method is several percents. The experimental results on the determination of the mode content at the output of the coaxial gyrotron, operating on the mode TE _14.8 are in a good agreement with the theoretical calculations.     

Recommendations for calculating the thermal creep properties of uranium dioxide when analyzing fuel-element serviceability

Recommendations for calculating the thermal creep properties of uranium dioxide for fuel element serviceability analysis programs are developed on the basis of a physical model. The deformation processes in the model include diffusion and diffusion-controlled motion of dislocations. It is shown on the basis of the analysis of the thermodynamics of point defects in ionic crystals that the diffusion of ions is controlled by a vacancy mechanism and that the diffusion coefficient depends on the temperature and oxygen coefficient. The model includes the influence of temperature, stress, fuel density, grain size, and oxygen ratio on the creep rate. The relations obtained in the this work have made it possible to improve by approximately a factor of 10 the agreement between the calculations and experimental data as compared with the empirical relation used previously to describe the characteristics of creep.