Investigation of the characteristics of a large reflector antenna via a correlation radioastronomical method

The experimental characteristics of a 25-m reflector antenna used as part of a radiointerferometer with a base of 100 m are presented. The radiointerferometer operates in the 10-cm wave band on the basis of signals from natural extraterrestrial radio sources and artificial satellites. Measurement techniques and corresponding hardware are developed and investigated.     

Measuring the mechanical recoil impulse of a polymeric target upon impact of a high power electron beam

A method for measuring the mechanical recoil impulse of a target produced by the relativistic electron beam of the Calamary accelerator is described. A detector based on a piezoelectric sensor is used in measurements. Results of measurements are presented for the mechanical recoil impulse produced by the relativistic electron beam with an energy as high as 300 keV, a current of up to 30 kA, and a duration of ~100 ns that is incident on an epoxy target. The energy flux density on the target surface is varied in the range of 1–10 GW/cm². The maximum measured impulse value is 0.32 N · s at an energy flux density of 10 GW/cm² (an energy fluence of 810 J/cm2).     

Domain Wall Motion Across Various Grain Boundaries in Ferroelectric Thin Films

Domain wall movement at and near engineered 10°, 15°, and 24° tilt and 10° and 30° twist grain boundaries was measured by band excitation piezoresponse force microscopy for Pb(Zr,Ti)O₃ films with Zr/Ti ratio of 45/55 and 52/48. A minimum in nonlinear response was observed at the grain boundary for the highest angle twist and tilt grain boundaries, while a maximum in nonlinear response was observed at the 10° tilt grain boundaries. The observed nonlinear response was correlated with the domain configurations imaged in cross section by transmission electron microscopy.     

Special features of seamless flux-cored wires for gas-shielded welding

The properties of flux-cored wires of the rutile and metal-powder type for welding and surfacing in industry and constructional engineering are examined. It is shown that flux-cored wires have obvious advantages in comparison with solid section wires both in the welding and technological properties of the welded joints. They are recommended for wide use.     

Marine Corrosion and Protection of Aluminum Alloys According to Their Composition and Structure

Based on long-term tests of aluminum alloys in seawater of various climatic zones from the Arctic to the tropics, the peculiarities of their corrosion behavior are revealed. In contrast to other alloys, hydrogen sulfide has a beneficial effect on their corrosion resistance due to the passivation. However, deep in the Black Sea, the alloys, which are susceptible to structural types of corrosion, were subjected to strong exfoliation corrosion, because hydrogen sulfide excluded fouling with microorganisms that inhibits exfoliation corrosion. Alloys of the Al-Mg system exhibit the highest corrosion resistance in seawater. Alloy of an AMr61 type (σ_ul = 340 MPa, σ_0.2 = 180–210 MPa, δ = 11–15%) has shown a good performance. Alloying with scandium and thermomechanical treatment make possible further simultaneous improvement of mechanical properties and corrosion resistance. It is shown that crevice corrosion is more typical of corrosion-resistant low aluminum alloys possessing lower free-corrosion and pitting potentials compared to high alloys, which are susceptible to structural types of corrosion, in particular, exfoliation corrosion. The methods of the aluminum alloys protection against marine corrosion are considered. It is shown that, in contrast to carbon steels, the anodic-cathodic protection is used for aluminum alloys.__________Translated from Zashchita Metallov, Vol. 41, No. 4, 2005, pp. 347–359.Original Russian Text Copyright © 2005 by Sinyavskii, Kalinin.     

A spectroscopic complex for time-resolved registration of plasma-jet parameters at the PF-3 facility

A spectroscopic complex for measuring the parameters of plasma jets that are generated in a facility of the plasma-focus type and the parameters of a stationary gas in which these jets propagate is described. The complex consists of an STE-1 crossed-dispersion spectrograph and a K008 streak camera, which is placed together with a notebook computer and a no-break power unit inside a shielding box for protection against electromagnetic noise. The K008 camera is equipped with an additional image intensifier on the basis of an EP-10 image-converter tube. The spectrum image is recorded with a standard SU-05M video camera and processed with the Klen-5m dedicated program, which automatically corrects the distortion and scan nonuniformities and subtracts regular noise. The complex makes it possible to obtain the time dependences of the intensities and shapes of several spectral lines in a range of scans from a few nanoseconds to milliseconds and to promptly tune the system to the required spectral ranges. Within one discharge of the facility, a digital image of the time-integral spectrum is simultaneously recorded in the entire visible region.