4,695 research outputs found

    The Nondipole Part of the Geomagnetic Field is Manifest at Magnetosphere Boundary

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    Nondipole part of geomagnetic field located at magnetosphere boundar

    Structure of the solar corpuscular stream and its interaction with the earth's magnetosphere

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    Structure of solar corpuscular stream and its interaction with earth magnetospher

    Experimental Study of the Effect of External Signal on Microwave Oscillations in a Nonrelativistic Electron Beam with Virtual Cathode

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    The effect of an external harmonic signal on the characteristics of microwave generation in a nonrelativistic electron beam with virtual cathode (VC) formed in a static retarding electric field (low-voltage vircator system) has been experimentally studied. A significant increase in the vircator generation power is observed when the frequency of the external signal is close to the frequency of VC oscillations. At large detunings, a broadband chaotic generation is observed.Comment: 3 pages, 2 figure

    Experimental and Theoretical Investigation into the Effect of the Electron Velocity Distribution on Chaotic Oscillations in an Electron Beam under Virtual Cathode Formation Conditions

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    The effect of the electron transverse and longitudinal velocity spread at the entrance to the interaction space on wide-band chaotic oscillations in intense multiple-velocity beams is studied theoretically and numerically under the conditions of formation of a virtual cathode. It is found that an increase in the electron velocity spread causes chaotization of virtual cathode oscillations. An insight into physical processes taking place in a virtual cathode multiple velocity beam is gained by numerical simulation. The chaotization of the oscillations is shown to be associated with additional electron structures, which were separated out by constructing charged particle distribution functions.Comment: 9 pages, 8 figure

    Optimal polymer slugs injection curves

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    In the paper we study miscible injection of liquids with decreasing viscosity in two-dimensional geometry. Polymer flooding of oil fields is our prototype model. Based on several one-dimensional approximate models we give rigorous formulation of the graded viscosity banks (GVB) technology which helps to save polymer by injecting several slugs with gradual decrease of viscosity instead of one slug. Limiting injection curves when number of slugs tends to infinity is calculated

    Suppression of Octahedral Tilts and Associated Changes of Electronic Properties at Epitaxial Oxide Heterostructure Interfaces

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    Epitaxial oxide interfaces with broken translational symmetry have emerged as a central paradigm behind the novel behaviors of oxide superlattices. Here, we use scanning transmission electron microscopy to demonstrate a direct, quantitative unit-cell-by-unit-cell mapping of lattice parameters and oxygen octahedral rotations across the BiFeO3-La0.7Sr0.3MnO3 interface to elucidate how the change of crystal symmetry is accommodated. Combined with low-loss electron energy loss spectroscopy imaging, we demonstrate a mesoscopic antiferrodistortive phase transition and elucidate associated changes in electronic properties in a thin layer directly adjacent to the interface
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