International cooperation of polish researchers with partners from abroad: A scientometric study

Publications resulting from international cooperation and included in seven SCI annual files 1987–1989 and 1992–1995 were analyzed. It was observed that after the political changes of the turn of 1980s considerable increase in the number of publications was accompanied by the geographic development of co-authorship. Information coming from SCI 1992–1995, elaborated, completed and encoded were entered into an own database designed for analytical purposes. During these four years above 9600 papers were published in over 1600 prestige journals, of which almost 2200 publications resulted from multilateral cooperation. Altogether the foreign coauthors came from 102 countries, but over 80% of international papers were published in cooperation with the partners from 11 countries. The domestic participants came from over 200 research and educational organizations. It was found that the biggest share of papers within this multidisciplinary file represented physics (≈40%), chemistry (≈21%), and biomedical research (≈11%).     

Mechanical behavior of Zr-based bulk metallic glasses

Bulk metallic glasses have a very high corrosion resistance and mechanical strength. Bulk metallic glasses show elastic-perfectly plastic behavior with an extended region of elastic strain (≈ 2%). But at room temperature their macroscopic plasticity is weak even though a local plastic strain is observed in shear bands. A relaxation analysis allowed studying micro-mechanisms of plastic deformation and estimating the apparent activation volume (≈ 2000 ų). __________ Translated from Problemy Prochnosti, No. 1, pp. 167–170, January–February, 2008.     

Controlling the wavelength of InGaAs/GaAs/InGaP lasers by ion implantation

The possibility of controlling the wavelength of emission from an InGaAs/GaAs/InGaP laser heterostructure with strained quantum wells (QWs) using medium-energy proton implantation followed by thermal annealing has been studied. It is established that the optimum proton energy is related to the arrangement of QWs in the structure (e.g., 150 keV for QWs at a depth of ≈1.3 μm). Proton irradiation to a total dose of 6 × 10¹⁴ cm⁻² followed by annealing at 700°C allows the wavelength of emission from the modified region to be decreased by 8–10 nm at minimum losses in the output intensity. The observed effect can be used to obtain two-band emission from the same chip and has good prospects for use in the development of new optoelectronic schemes.     

Electron parameters in Xe-Ne mixtures

The effect made by xenon concentration and by reduced electric field on the parameters of electrons in Xe-Ne mixtures is numerically studied. It is demonstrated that the increase in xenon concentration in mixture leads to a decrease in the average electron energy, to an increase in the frequency of collisions of electrons with gas atoms, and to variation of the transport coefficients of electrons. The increase in xenon concentration in mixture above ≈10% leads to an abrupt slowing down of the rates of excitation of xenon atoms. The efficiency of ionization increases with the xenon concentration increasing to ≈7%. The fraction of electron energy spent for excitation of xenon decreases with increasing electric field, and more energy is put into the ionization of xenon and into excitation and ionization of neon. The results of calculation of parameters of electrons make it possible to limit the search for xenon concentrations in Xe-Ne mixture, which are optimal for vacuum ultraviolet radiation, to the range of 1–10%.     

Efficient lasing of a mixture of organic dyes at 610 and 670 nm

The efficiency of the lasing regime of a pulsed tunable laser at the “exotic” wavelengths of 610 and 670 nm, which are needed in nuclear physics, is investigated. A method for performing model calculations of the active media for such a laser, i.e., working mixtures of high-molecular-weight dyes, is developed. The conditions specifying a quasiequilibrium window, in which the achievement of high output characteristics is possible for such a mixture at assigned wavelengths, are derived. It is interpreted on the basis of the law of alternating nonequilibria in the theory of nonequilibrium states. The results obtained are verified experimentally: a high-power miniature pulsed laser with an active medium consisting of a mixture of dye solutions with high output characteristics at the assigned wavelengths of 610 and 670 nm is created. Pis’ma Zh. Tekh. Fiz. 25, 1–7 (April 26, 1999)     

Highly efficient high-power continuous extreme ultraviolet source for irradiating samples with a large total area

An original arc-discharge source of cw extreme ultraviolet (10–75 nm) radiation is described, which provides an output power level of ∼10 kW at an efficiency of ∼10% (at least, in the 30–70 nm range). The source is simple to manufacture, possesses a working life of ∼1000 h, and is capable of irradiating samples with a total exposed area of 0.1–1 m².     

Comparative study of generation characteristics of CdS crystal laser pumped by low- and high-energy electron beams

A CdS crystal has been excited by radially converging pulsed electron beam with an electron energy of up to E ≈ 18 keV, a beam current density at the target of up to 4 kA/cm², and a pulse full width at half maximum within τ ≈ 12–100 ns. For comparison, the same crystal was pumped by electrons with E = 170 keV at τ = 2.2 ns. A specific distinctive feature of the excitation by powerful low- and high-voltage electron beams is the appearance of previously unreported long-wavelength generation with a peak at λ ≈ 535 nm in the electron-hole plasma band. In the region of the interband transition with a peak at λ ≈ 515 nm, the generation spectra are similar to those known from the literature.     

The design of a laboratory experiment to detect new forces

An experiment to detect new interactions, described by a Yukawa-type potential, on equipment with a uniform gravitational field is considered. It is shown that in the Yukawa α-λ potential parameter space a sensitivity can be achieved at a level of α ≈ 10⁻¹⁰ in a range of values of λ ≈ 0.1–10⁷ m. __________ Translated from Izmeritel’naya Tekhnika, No. 6, pp. 3–8, June, 2007.     

Results of testing a centrifugal bubble singlet-oxygen generator

The results of parametric tests of a centrifugal bubble singlet-oxygen generator based on the reaction of chlorine with an alkaline hydrogen peroxide solution have been given. The utilization of chlorine grows with bubble-layer height, whereas the relative content of O₂(¹Δ) remains constant. Growth in centrifugal acceleration leads to a more efficient utilization of chlorine. A specific oxygen output of more than 1 mmole·cm⁻²·sec⁻¹ from the bubble layer for a degree of chlorine utilization of ∼95% and a singlet-oxygen yield of more than 50% has been attained. It has been shown that a centrifugal bubble singlet-oxygen generator is an efficient energy source for an oxygen-iodine laser. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 3, pp. 121–128, May–June, 2007.     

Emissive characteristics of mesa-stripe lasers (λ=3.0–3.6 μm) made from InGaAsSb/InAsSbP double heterostructures

The directional patterns, current-voltage characteristics, and spectral characteristics of mesastripe lasers with InGaAsSb active layers, emitting at λ=3.0–3.6 μm (77 K) and having threshold currents ≥15 mA (j _th≥200 A/cm²), are investigated. The maximum output power is 1.4 mW (λ∼3.3 μm), the differential quantum efficiency ∼3%(τ=5–30 μs, f=500 Hz) for lasing in a longitudinal mode with beam divergences ΔΘ∥∼15° and ΔΘ ⊥ ∼30°. The relationship of the differential quantum efficiency to the order of the spatial mode of the lasing is demonstrated. A single-mode, current-tunable (−30 cm⁻¹/A) laser is used to measure the transmission of methane in the region of the ν ₃ absorption band. Pis’ma Zh. Tekh. Fiz. 24, 40–45 (June 26, 1998)     

Synthesis, sintering and expansion of Al0.8Mg0.6Ti1.6O5: a low-thermal-expansion material resistant to thermal decomposition

A low-thermal-expansion ceramic with the composition Al0.8Mg0.6Ti1.6O5 that is isostructural to aluminium titanate Al2TiO5, was prepared by solid-state reaction of a mixture of α-Al2O3, MgO and TiO2-rutile. The synthesized material does not decompose after annealing for 250 h in the temperature range of 900–1175°C. The ceramic sintered at 1350°C has a 97% relative density, a grain size of ≈5 μm and an average thermal expansion coefficient between 80 and 1000°C of ≈2×10−6 K−1. Materials with the same composition, but obtained by reaction sintering, have a higher thermal expansion coefficient (4×10−6 K−1) and showed the presence of secondary phases. This revised version was published online in November 2006 with corrections to the Cover Date.     

Optimization of pulsed-periodic neodymium glass lasers

Results of an investigation aimed at improving the efficiency of pulsed-periodic neodymium glass lasers are presented. The choice of the efficiency criterion of the laser system as the product of the radiation power and the Strehl number made it possible to formulate and substantiate several practical recommendations on the choice of optimum operating-mode—structure parameters of a pulsed-periodic laser. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 6, pp. 1085–1091, November–December, 1998.     

Processing maps for Fe–24Ni–11Cr–3Ti–1Mo superalloy

Hot deformation characteristics of a Fe-base superalloy were studied at various temperatures from 1000–1200°C under strain rates from 0·001–1 s^− 1 using hot compression tests. Processing maps for hot working are developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate and interpreted by a dynamic materials model. Hot deformation equation was given to characterize the dependence of peak stress on deformation temperature and strain rate. Hot deformation apparent activation energy of the Fe–24Ni–11Cr–1Mo–3Ti superalloy was determined to be about 499 kJ/mol. The processing maps obtained in a strain range of 0·1–0·7 were essentially similar, indicating that strain has no significant influence on it. The processing maps exhibited a clear domain with a maximum of about 40–48% at about 1150°C and 0·001 s^− 1.     

Observation of a negative characteristic temperature for the threshold current of diode lasers for the 2.8 /gmm spectral range

A decrease in the lasing threshold with increasing temperature has been observed in InAs/InAsSbP laser heterostructures for the 2.7–2.9 μm spectral range at cryogenic temperatures (T=32–85 K). At temperatures below 50 K a negative characteristic temperature, T ₀=−70 K, was obtained for the threshold current. Characteristics of the temperature dependence of the threshold current and the laser output power were investigated. Pis#x2019;ma Zh. Tekh. Fiz. 23, 72–79 (November 26, 1997)     

Quantum-dot cw heterojunction injection laser operating at room temperature with an output power of 1 W

This paper describes a new cw laser with tunnel-coupled vertically aligned InGaAs quantum dots in an AlGaAs matrix with a room-temperature output power of ∼ 1 W at both mirrors. The maximum operating temperature of the heat sink is ∼ 75 °C. Pis’ma Zh. Tekh. Fiz. 23, 51–54 (February 26, 1997)     

Two-channel interferometer based on inter-laser detection of reflected radiation

A novel laser interferometer is proposed. It successively generates two quadrature output signals at a high carrier frequency, combining a two-beam principle with a point spread function possessing a high slope. The interferometer is based on a dual-mode Zeeman He−Ne laser with a wavelength of 3.39 μm. It is used to present experimental investigations of an erosion capillary discharge in air produced by means of a grind-faced graphite employed as the reflector. Translated from Izmeriell’naya Tekhnika, No. 7, pp. 36–39, July, 1999.     

Polarization switching time for semiconductor laser radiation

Expressions are derived for the polarization switching time for semiconductor laser radiation. These expressions can be used to assess the influence of the laser diode parameters on the polarization switching time of the output radiation. The results of an analysis of these expressions show that the main parameters influencing the polarization switching of the output radiation from a semiconductor laser are the nonlinear gains. Pis’ma Zh. Tekh. Fiz. 23, 87–95 (May 12, 1997)     

AlGaAs/GaAs-heterostructure cw laser diodes with a working output optical power of 3 W (λ=0.81 μm) and an operating life of 2000 hours

Qantum-well AlGaAs/GaAs heterostructures with separate confinement have been used to fabricate laser diodes emitting at 0.81 μm, with a cw output optical power of 4 W and an operating life of more than 2000 h at a power of 3 W and a temperature of +20°C. Pis’ma Zh. Tekh. Fiz. 23, 90–94 (April 26, 1997)     

X-ray spectroscopic methods for measuring the parameters of high-temperature dense plasma

X-ray spectroscopic methods are considered for measuring the parameters of dense high-temperature plasma having a transient ionization state from the relative intensities of spectral lines belonging to different ionization sequences. It is shown that there are presently more than ten different x-ray spectroscopic methods for measuring the electron temperature T_e and density N_e of the plasma ionization, state in a wide range of T_e≈10–3000 eV and N_e≈10¹⁵–10²⁵ cm⁻³. Typical errors of plasma parameter measurements are discussed. Translated from Izmeritel'naya Tekhnika, No. 1, pp. 64–68, January, 1997.