Investigation of the foil destruction dynamics in an explosively formed fuse opening switch by proton radiography

The dynamics of mechanical destruction of a conductor in an explosively formed fuse opening switch on a finned obstacle under the action of detonation products is studied in the injection channel of the U-70 proton synchrotron. Protonograms are recorded with digital multiframe electron-optic cameras. The exposure time per frame, about 30 ns, is determined by the duration of a proton bunch. The time from the beginning of motion of the conductor to its destruction is about 3 ??s. It is shown that the switch with typical sizes of the obstacle (the thickness of the fin is 1.5 mm, and the width and depth of the groove are 1.5 and 4.5 mm, respectively) provides operation with satisfactory gasdynamic parameters.     

Development of a submerged turbulent isothermal jet and the minimum entropy-production principle

It is shown in the example of a submerged turbulent isothermal jet that the process of turbulent mixing of gas jets can evolve in accordance with, the principle of minimum entropy production.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 52–58, July–August, 1978.     

Synthesis of rigidly linked triad molecules based on octaalkylporphyrin,capable of multistep electron transfer

Summary We have designed and carried out the synthesis of triad model systems containing octaalkylporphyrin, benzoquinone, and trichlorobenzoquinone with an oxidation-reduction potential gradient in the molecule. The quinone moieties are fixed relative to the porphyrin using spirof4,4]nonane and methylene spacers.Translated from Khimiya Geterotsildicheskikh Soedinenii, No. 8, pp. 1052-1062, August, 1994.     

Gamma-ray bursts from evaporating primordial black holes

It is believed that the detection of gamma-ray bursts from evaporating primordial black holes is highly improbable in the near future since the expected photon flux, consisting mainly of photons with energies ? GeV, is too low. Contrary to this point of view, we show that a large fraction of the black hole power at the final stage of evaporation (the last 10³ s) can be liberated as a burst of soft γ-ray emission of duration 10^?1–10³ s and luminosity 10²⁸–10³¹ erg/s in the energy range 0.1–1 MeV. According to our calculations of the black hole evaporation rate (within the Standard Model of elementary particles), when the black hole temperature exceeds approximately 10 GeV, the charged particle outflow from a black hole forms a well-defined plasma and can be described in the hydrodynamic approximation. In this case more than half of the rest energy of a black hole can be converted into soft gamma-rays due to the presence of the magnetic field with energy density comparable to that of charged particles. We consider various mechanisms leading to such transformation and estimate their efficiency. It is shown that, at least, some of the gamma-ray bursts detected by BATSE can be associated with evaporating black holes.     

Study of the gas-filled injector of a plasma opening switch

A plasma injector with pulsed gas filling is investigated experimentally. Interferometric measurements of the formation dynamics of the plasma channel are carried out. Under optimal operating conditions, the injector is capable of producing a plasma channel 4 cm in diameter with an electron density of ∼10¹⁷ cm⁻³. The effect of the cathode diameter of the plasma opening switch on the conductivity of the plasma channel is studied. It is shown that the current flowing through the plasma channel of a single injector attains 400 kA.     

Integro-Local and Integral Limit Theorems on the Large Deviations of Sums of Random Vectors: Regular Distributions

We study the asymptotics of the probability that the sum of random vectors belongs to a relatively small cube in the range of large deviations.     

Nanoaggregates of copper porphyrazine in floating layers and Langmuir-Schaefer films

Aggregation behavior of unsubstituted copper porphyrazine (CuPaz) on the water surface was studied by analysis of compression curves, Brewster angle microscopy (BAM), and optical spectroscopy. The structure and stability of the CuPaz aqua aggregates in the floating layers are determined by hydration degree that depends on initial surface concentration and surface pressure. Langmuir-Schaefer (LS) films of CuPaz were prepared by deposition of the variously structured floating layers and studied by X-ray scattering technique and optical spectroscopy. Stable and labile structures were detected and compared with the floating CuPaz aqua aggregates. Conditions of formation of the stable four-stacked nanoaggregates in LS films were determined. A model comprising both nucleation of CuPaz on the water surface and structural transformations in the solid films is proposed.     

Synthesis and structures of new metallocene derivatives of lanthanides. Molecular structures of the complexes (C13H9)2Eu(THF)2 and (C5Me4H)2YbI(THF)

The divalent europium bis-fluorenyl complex (C₁₃H₉)₂Eu(THF)₂ was synthesized by the metathesis reaction of EuI₂(THF)₂ with two equivalents of fluorenylpotassium and by the protolytic substitution of the naphthalene ligand in the (C₁₀H₈)Eu(THF)₂ complex using the reaction with fluorene. According to X-ray diffraction data, the complex displays a skewed sandwich structure, in which one fluorenyl ligand is η⁵-coordinated to the metal atom, whereas the η³-coordination mode makes a great contribution to the coordination of another ligand. The (C₅Me₄H)₂YbI(THF) complex was synthesized by the reaction of YbI₃(THF)₂ with two equivalents of (C₅Me₄H)K. The structure of the complex was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 530–534, March, 2008.