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2008Babich, L.P., Donskoy, E.N., Kutsyk, I.M. Analysis of atmospheric gamma - ray flashes detected in near space with allowance for the transport of photons in the atmosphere // Journal of Experimental and Theoretical Physics, 2008, Volume 107, Issue 1, Pages 49 - 60 RFNC - VNIIEF, Sarov, Russian Federation Monte Carlo simulations of transport of the bremsstrahlung produced by relativistic runaway electron avalanches are performed for altitudes up to the orbit altitudes where terrestrial gamma - ray flashes ( TGFs ) have been detected aboard satellites. The photon flux per runaway electron and angular distribution of photons on a hemisphere of radius similar to that of the satellite orbits are calculated as functions of the source altitude z. The calculations yield general results, which are recommended for use in TGF data analysis. The altitude z and polar angle are determined for which the calculated bremsstrahlung spectra and mean photon energies agree with TGF measurements. The correlation of TGFs with variations of the vertical dipole moment of a thundercloud is analyzed. We show that, in agreement with observations, the detected TGFs can be produced in the fields of thunderclouds with charges much smaller than 100 C and that TGFs are not necessarily correlated with the occurrence of blue jets and red sprites. Siemon, R.E.a, Bauer, B.S.a, Awe, T.J.a, Angelova, M.A.a, Fuelling, S.a, Goodrich, T.a, Lindemuth, I.R.a, Makhin, V.a, Atchison, W.L.b, Faehl, R.J.b, Reinovsky, R.E.b, Turchi, P.J.b, Degnan, J.H.c, Ruden, E.L.c, Frese, M.H.d, Garanin, S.F.e, Mokhov, V.N.e The Challenge of Wall - Plasma Interaction with Pulsed Megagauss Magnetic Fields // Journal of Fusion Energy, 2008, Pages 1 - 3 ( article in press ) a University of Nevada, Reno, United States A method is described for choosing experimental parameters in studies of high - energy - density ( HED ) physics relevant to fusion energy, as well as other applications. An important HED issue for magneto - inertial fusion ( MIF ) is the interaction of metal pusher materials with megagauss ( MG ) magnetic fields during liner compression of magnetic flux and fusion fuel. The experimental approach described here is to study a stationary conductor when a pulsed current generates MG fields at the surface, instead of studying the inner surface of a moving liner. This places less demand upon the pulsed power system, and significantly improves diagnostic access. Thus the deceptively simple geometry chosen for this work is that of a z pinch composed of a metal cylinder carrying large current. Consideration of well known stability issues for the z pinch shows that for given peak current and rise time from a particular power supply, there is a minimum radius and thus maximum B field that can be created without disruption of the conductor before peak current. The reasons are reviewed why MG levels of magnetic field, as required for MIF, result in high temperatures and plasma formation at the surface of the metal in response to Ohmic heating. The distinction is noted between the liner regime obtained with cylindrical rods, which have a skin depth small compared to the conductor radius, and the exploding thin - wire regime, which has skin depth larger than the wire radius. A means of diagnostic development is described using a small facility ( DPM15 ) built at the University of Nevada, Reno. It is argued that surface plasma temperature measurements in the 10 - eV range are feasible based on the intensity of visible light emission. Kosyakov, B.P. Massless interacting particles // Journal of Physics A: Mathematical and Theoretical, 2008, Volume 41, Issue 46, art. no. 465401 RFNC - VNIIEF, Sarov, Russian Federation We show that classical electrodynamics of massless charged particles and the Yang - Mills theory of massless quarks do not experience rearranging their initial degrees of freedom into dressed particles and radiation. Massless particles do not radiate. We propose a conformally invariant version of the direct interparticle action theory for these systems. Sabirova, Z.A.a, Danilova, M.M.a, Zaikovskii, V.I.a, Kuzin, N.A.a, Kirillov, V.A.a, Kriger, T.A.a, Meshcheryakov, V.D.a, Rudina, N.A.a, Brizitskii, O.F.b, Khrobostov, L.N.b Nickel catalysts based on porous nickel for methane steam reforming // Kinetics and Catalysis, 2008, Volume 49, Issue 3, Pages 428 - 434 a Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russian Federation The influence of synthesis conditions on the phase composition and texture of porous nickel supports as plates with a magnesium oxide underlayer were investigated by X - ray diffraction, low - temperature nitrogen absorption, and electron microscopy combined with X - ray microanalysis. Nickel catalysts supported on these plates were studied. Thermal treatment of Mg( NO3 )2 in nitrogen yields a magnesium oxide underlayer with a small specific surface area ( support I ). The replacement of nitrogen with hydrogen leads to a larger surface area ( support II ). The formation of MgO is accompanied by the incorporation of Ni 2+ cations from the oxide film into the underlayer. Upon subsequent reduction with hydrogen or under the action of the reaction medium, these cations form fine crystallites of nickel. The supports having an oxide underlayer show a higher activity in methane steam reforming than the initial metallic nickel. Nickel catalysts on supports I and II show similar activities. The activity of the catalysts was stable throughout 50 - h - long tests; no carbon deposits were detected by TEM. Molchanov, V.V.a, Shchuchkin, M.N.b, Zaikovskii, V.I.a, Bogdanov, S.V.a, Zaitseva, N.A.a Sorbents and supports based on nanoporous carbon xerogels // Kinetics and Catalysis, 2008, Volume 49, Issue 5, Pages 702 - 707 a Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russian Federation The physicochemical properties of nanoporous carbon materials ( TUMaNs ) prepared by the carbonization of porous phenol - formaldehyde resin were studied. According to high - resolution electron microscopic data, these materials are nanographites composed of 5 - to 10 - µm globules, which form chaotically arranged microblocks 3 - 4 graphene layers in thickness. The materials have a developed system of 1,5 - to 3,0 - nm micropores and a specific surface area of 450 - 700 m2/g. According to X - ray diffraction analysis, the samples consisted of strongly disordered graphite with uniquely large interlayer distances of 0,375 - 0,390 nm. The sorption properties of TUMaN toward hydrogen and light hydrocarbons were studied. The amount of absorbed hydrogen was higher than analogous values for materials with comparable or even larger specific surface areas. With respect to the sorption of light hydrocarbons, the properties of TUMaN were similar to those of silica and alumina. Nickel supported on TUMaN exhibited an unusually high activity and selectivity in butadiene hydrogenation to butenes. Palladium on TUMaN was highly effective in the hydrofining of ethylene for the removal of acetylene impurities. Markov, P.V.a, Pribytkov, A.S.a, Tolkachev, N.N.a, Stakheev, A.Yu.a, Kustov, L.M.a, Golubeva, V.N.b, Tel'nov, A.V.b Effect of electron beam irradiation on the formation of active sites in the Pt/H pentasil catalyst // Kinetics and Catalysis, 2008, Volume 49, Issue 5, Pages 765 - 769 a Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 119991, Russian Federation The influence of preirradiation with an electron beam from a linear resonance electron accelerator in flowing argon on the structure and properties of the 1% Pt / H pentasil catalyst was studied. The support structure was studied by x - ray diffraction and low - temperature nitrogen adsorption. No changes in the crystal structure and pentasil specific surface area were observed in the irradiation dose range from 120 to 900 Mrad at an average electron energy of 7.7 MeV. The electron beam treatment resulted in a considerable increase in the catalytic activity of the Pt / H pentasil in gas - phase toluene hydrogenation as a model reaction. The results obtained by IR spectroscopy of adsorbed CO and X - ray diffraction data suggested that the increase in the catalyst activity after electron beam irradiation is due to changes in the size and charge of the Pt particles. Garanin, S.G. High - power lasers at the Russian Federal Nuclear Center ( VNIIEF ) // Laser Physics, 2008, Volume 18, Issue 4, Pages 387 - 392 RFNC - VNIIEF, Sarov, Russian Federation The development of laser plants with different purposes, which originally began in the mid - 1960s, are being successfully carried out at the Laser Physics Research Institute ( LPRI ). Investigations of the physical fundamentals of the laser operation, nonlinear optics, and the properties of high - temperature dense plasma that is formed under the action of the intensive laser emission on matter are realized at these plants. Smolyakov, A.A.a , Solovyev, V.P.a, Korshunov, A.I.a, Enikeev, N.A.b,c Three - dimensional numerical simulations of multi - pass equal - channel angular pressing by a variation difference method and comparison with experiment // Materials Science and Engineering A, 2008, Volume 493, Issue 1 - 2, Pages 148 - 159 a RFNC - VNIIEF, Sarov, Russian Federation A variation - difference method ( VDM ) of solving continuum mechanics equations has been implemented for simulation of the equal - channel angular pressing ( ECAP ) process. Application of the developed DRAKON code ( RFNC - VNIIEF, Russia ) for numerical study of multi - pass ECAP allowed processes of severe plastic deformation to be described in three - dimensional ( 3D ) continuum approximation in the field of low strain rates and high - pressure levels in terms of contact interaction. The influence of ECAP processing parameters on stress - strain field distribution over the ECAP sample's cross - section is studied in 3D formulation. The model validation is performed by comparison of simulation results with various experimental data. Deformation histories provided by DRAKON were used together with a polycrystal plasticity model ( viscoplastic self - consistent model ) allowing simulation of texture evolution during ECAP with account to macro - parameters of the process. It is shown that the VDM - based model possesses good predictive capabilities for 3D simulation of severe plastic deformation processes involving strain - path changes. Korshunov, A., Kravchenko, T., Polyakov, L., Smolyakov, A., Vedernikova, I., Morozov, A. Effects of the number of equal - channel angular pressing passes on the anisotropy of ultra - fine titanium // Materials Science and Engineering A, 2008, Volume 493, Issue 1 - 2, Pages 160 - 163 RFNC - VNIIEF, Sarov, Russian Federation Annealed commercially pure titanium was processed by four passes of equal - channel angular pressing at a temperature of 450°C using route BC . Pressed samples had a square section with a side length of 8 mm. Anisotropy was analyzed based on the conventional yield strength at compression in three mutually perpendicular directions. Compression tests were performed with static loading at room temperature and at 450°C. The tests were conducted with the as - received material, and after 1, 2, 3 and 4 passes. Anisotropy of the as - received condition holds out at further pressing and makes about 25%. Anisotropy after all the passes is similar both for room and elevated temperature. Anisotropy characteristics are observed to change during the third pass. The anomalous change in anisotropy during the third pass is also evidenced by the analysis of microhardness measurements in different section planes of the samples.
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