Calibrating high-vacuum gauges

Translated from Izmeritel'naya Tekhnika, No. 6, pp. 19–20, June, 1989.     

Stages of surface erosion under ion irradiation

Initial stages of surface erosion have been studied for NaCl and LiF single crystals bombarded by Ar⁺ ions with 20 keV. For irradiation with doses D=10¹⁰-10¹¹ ions/cm², exoelectron emission has been used, whereas for higher doses, we have used electron microscopy. Two stages of initial surface erosion have been identified; for small doses, there is slow development of atomic-scale roughening, which reaches its peak when areas damaged by closest incident ions start to overlap, and then, beginning with D=10¹⁶ ions/cm², there is rapid etching, deep into the crystal, followed by the emergence of secondary microscopic structure, i.e. caverns, concentric closed steps and terraces. Ion-induced surface structure of alkali halide crystals has been shown to depend strongly on the presence of foreign particles on the surface, as well as on segregation. Topography of thin carbon films and some metals have been discussed.     

Enhancement of bending strength of heat-resistant steel by ion carbonitriding

The heat-resistant steel 20Kh3MVF-Sh is used for toothed gears employed in pumps of turbojet engines. In service, the working surface of the gears is subjected to intensive wear. Using gas-phase carburizing to case-harden such gears has proven to be insufficiently effective. In this work we have investigated the structure, the chemical composition, and the wear resistance of 20Kh3MVF-Sh steel after ion carbonitriding. We have obtained regression equations relating the wear resistance characteristics to the carbon and nitrogen concentration and the hardness of the diffusion layer. We have developed a combination process for ion carbonitriding which increases the wear resistance or steel 20Kh3MVF-Sh.N. É. Bauman State Technical University, Moscow. MAKB TEMP. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 9–13, June, 1994.     

The current of an annular electron beam behind virtual cathode

The output current I _out of a magnetized annular electron beam transported in a homogeneous drift tube of a SINUS-7 setup has been studied as a function of the injected beam current I _inj. The electron beam was injected via an anode inset of smaller radius and had a current above the Fedosov limit for the given drift tube (I _inj ≥ I _F). It is established that, to within the experimental uncertainty, a virtual cathode (VC) is formed when the injected beam current exceeds the corresponding limiting I _lim. In this state, the current transmitted behind VC is approximately equal to the limiting value (I _out ≈ I _lim).     

The virtual cathode velocity during electron beam transport in a drift tube

Technical Physics Letters - A solution corresponding to a thin annular electron beam in a homogeneous drift tube featuring a uniformly moving virtual cathode (VC) has been obtained. The dependence...     

New Generation of Microfuel-Based Fuel Elements for VVÉR Reactors

The results of development work on a new generation of fuel elements based on microfuel for VVÉR reactors using the basic data from post-reactor investigations and bench tests in experiments simulating LOCA for existing fuel elements with ceramic fuel are presented. It is shown that cermet fuel elements will make it possible to realize most fully the advantages of such fuel, specifically, to develop a sealed first loop and to simplify and reduce the cost of safety, automatic control, radiation protection, coolant puification, and other systems. For example, cermet fuel elements in VVÉR-1500 reactors can improve safety under various operating conditions, maneuverability, vibrational strength, fuel assembly lifetime, and geometric stability of fuel elements.     

Microstructure and properties of α-tricalcium phosphate-based bone cement

This paper examines the physicochemical properties and microstructure of brushite calcium phosphate cements possessing strength acceptable for application in surgery (15–20 MPa) and ensuring an optimal acidity (pH 6.5–7.5) of solutions in contact with them. Holding in a physiological saline produces significant changes in the microstructure of the cement relative to that before immersion in the solution: it causes a transformation of the most soluble components into platelike hydroxyapatite crystals.     

Increasing the rated capacity of power units installed at Russian nuclear power stations equipped with VVER-1000 reactors

Safe operation of the Balakovo nuclear power station’s Unit 2 built around a VVER-1000 reactor at a thermal power output of 3120 MW with meeting of the safety criteria and compliance with the requirements of existing regulatory documents is substantiated. Results from measurements of process parameters at a power output equal to 104% of its nominal value are presented.     

New approach to the determination of the lowest achievable effectiveness of emergency shielding of VVÉR reactors

A conceptual approach is proposed to determining the minimum achievable number of control organs in the safety and control system and the minimum effectiveness of emergency shielding of VVéR reactors. This approach includes a new probabilistic method of determining the effectiveness of emergency shielding with failures of different numbers of control organs and a decrease in the excess conservatism in performing thermohydraulic analysis. The modern safety ideology is used. For VVéR-1000, it is shown that emergency shielding with 49 control organs is sufficient for the determining anticipated accident with steam-pipe rupture. __________ Translated from Atomnaya énergiya, Vol. 100, No. 3, pp. 184–197, March, 2006.     

Optimization of Twisting Technology in Processing of Polypropylene Film Sewing Thread

Regression equations and graphic dependences demonstrating the effect of selected factors (first and second twist value) on the physicomechanical properties of PP film sewing thread are obtained. The optimum parameters of twisting of PP film sewing thread are determined.