Effect of thermomechanical treatment on damping capacity of titanium alloys

This paper gives the results of experimental studies of the influence of thermomechanical treatment and post-annealing on the level of damping capacity of titanium alloys VT3-1 and VT8. We subjected VT3-1 alloy to both treatment modes, and VT8 alloy to only one. We evaluated the efficiency of the thermomechanical treatment modes by the vibration strength criterion (σ_aδ). Translated from Problemy Prochnosti, No. 1, pp. 95–101, January–February, 1999.     

The method of assessment of the of friction contact fatigue parameters of technological ceramics and crystals

Two formulas were derived earlier using the theory of wear of I.V. Kraguelskii to calculate the wear resistance of friction pairs. To use them it was necessary to determine the friction contact fatigue parameters. The present paper deals with the method of experimental calculated assessment of these parameters and the results of its validation using wear resistant nanostructured alloyed zirconium dioxide crystals and engineering ceramics.     

Electroreflectance study of the effect of γ radiation on the optical properties of epitaxial GaN films

Experimental data on the electroreflectance spectra of γ-irradiated epitaxial GaN films on sapphire are reported. The irradiation doses are 10⁵−2 × 10⁶ rad. The theoretical electroreflectance spectra calculated on the basis of a model of three types of transitions are in agreement with experimental data with reasonable accuracy. The energies and broadenings of the transitions derived in the context of the model give grounds to infer that, in the GaN films, there are internal stresses dependent on the γ-irradiation dose.     

Optical monitoring of substrate temperature and etching speed of multilayered structures during plasmochemical etching

Using weakly coherent tandem interferometry, the possibility of simultaneous temperature and film thickness measurements in plasmochemical etching processes of silicon on insulator structure is demonstrated. It is shown that changes of the structure’s total optical thickness related to temperature variation can be separated from a change of the physical film thickness. For that purpose we have to take in account changes of zeros interference peak amplitude caused by changes of the interferentional conditions inside the film when its thickness is changing. Temperature measurement precision is ±1°C. Thickness measurement precision is ±10 nm. The results of process monitoring closely correlate with the results of a stair’s profile obtained with a profilometer.     

A secondary beam separator: A combination of the COMBAS fragment separator with the ion catcher

The development of an experimental facility based on the high-luminosity COMBAS fragment separator and a fast ion catcher is discussed. The main characteristics of the COMBAS fragment separator and the ion catcher determining the advantages of the proposed combination are presented. The developed facility is expected to allow production of secondary radioactive beams with a quality higher than the quality of beams obtained using the in-flight separation technique. It is planned that the facility will be used in a tandem with a post-accelerator for producing single-isotope and monochromatic high-intensity secondary radioactive beams in a wide range of mass numbers A and atomic numbers Z. A list of perspective scientific problems requiring high-intensity and high-quality secondary beams of exotic nuclei is proposed.     

A parallel plate avalanche detector for low energy ion identification

A setup for identifying low-energy (1–10 MeV) ions with charges Z ≥ 1 by simultaneously measuring the energy losses and the time of flight is described. The setup is composed of a multiwire proportional chamber and a strip silicon detector, which are used to measure the ion energy, and two low-pressure avalanche wireless detectors for measuring the energy losses and the time of flight. Results obtained in measuring α particles from ²²⁶Ra source and p, Be, C, and O ions produced on the ITs-100 cyclotron at the Flerov Laboratory of Nuclear Reactions are presented.     

Attractive manifolds in end milling

The attractive manifolds formed in end milling are analyzed. Such states are formed if the trajectories of steady periodic deformational tool displacements are unstable overall or in individual sections. In the dynamic milling system, attractive manifolds in the form of limit cycles, invariant tori, and strange (chaotic) attractors may appear. Bifurcations of attractive manifolds in parameter space are analyzed at length, with examples. Interest centers on how attractive manifolds affect manufacturing quality.     

Spectroscopic studies of intense pulse discharge in hydrogen

Spectroscopic methods were used to study the properties of intense pulse discharge in a gas. It is shown that in the initial stage of the process, while the discharge is contracting onto the axis of the chamber, the velocity of the luminous front is as high as 6–8 · 10⁶ cm/sec. A calculation of the number of ionized atoms is carried out. Experiments in which the luminosity of the pulse discharge plasma was investigated are described. The results of intensity measurements on the spectral lines of a hydrogen plasma are presented.The authors take this opportunity to express their sincere indebtedness to L. A. Artsimovich and M. A, Leontovich for valuable discussions and for their constant interest in the work.