34 research outputs found

    Stochastic electron heating in the laser and quasi-static electric and magnetic fields

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    The dynamics of relativistic electrons in the intense laser radiation and quasi-static electromagnetic fields both along and across to the laser propagating direction are studied in the 3/2 dimensional Hamiltonian framework. It is shown that the unperturbed oscillations of the relativistic electron in these electric fields could exhibit a long tail of harmonics which makes an onset of stochastic electron motion be a primary candidate for electron heating. The Poincar\'e mappings describing the electron motions in the laser and electric fields only are derived from which the criterions for instability are obtained. It follows that for both transverse and longitudinal electric fields, there exist upper limits of the stochastic electron energy depending on the laser intensity and electric field strength. Specifically, these maximum stochastic energies are enhanced by a strong laser intensity but weak electric field. Such stochastic heating would be reduced by the superluminal phase velocity in both cases. The impacts of the magnetic fields on the electron dynamics are different for these two cases and discussed qualitatively. These analytic results are confirmed by the numerical simulations of solving the 3/2D Hamiltonian equations directly

    Structure and microwave dielectric properties of Bi- and Ge-doped calcium molybdate

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    The powders of Ca1–2xBi2xMo1–xGexO4 solid solutions weresynthesized by the conventional solid state method and investigated by X–ray powder diffraction and Raman spectroscopy. The Ca1–2xBi2xMo1–xGexO4 compositions crystallize in scheelite structure (sp. gr. I41/a) atΒ 0 xΒ  0.4, but traces of bismuth germanates are detected by scanning electron microscopy. The xΒ =Β 0.5 composition contains several phases with BiVO4- type structures. Raman spectroscopy detected the deformation of [BO4]2– polyhedra and changes in B–O bond length (BΒ =Β Mo, Ge). The energy gaps were calculated from the diffuse scattering spectra by the Kubelka-Munk method. Energy gap (Eg) values decrease with x from 3.29Β eV to 2.91 eV, probably due to 6s2 electrons of bismuth in the valence band and changes of the conductivity band by electrons of germanium. Such values of Eg can provide photocatalytical activity of powders under UV and visible light. The electrodynamic parameters of the ceramic sample of Ca1–2xBi2xMo1–xGexO4 were measured by the transmission line method. The average permittivity increases with x from ~10 to ~18 which correlates with theoretical Ξ΅, Vmol and total polarizability of samples. An increase in the concentration of bismuth and germanium leads to the additional resonant peaks in the spectra of Ξ΅, S11 and S21. These resonant peaks can be probably caused by the appearance of irregular structural domains of Bi atoms or induced by the increased size of grains in the ceramic samples

    НовыС ΠΊΠΎΠΌΠ±ΠΈΠ½Π°Ρ†ΠΈΠΈ ΠΈ названия сосудистых растСний Азиатской России.

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    In this paper, we present nomenclatural novelties required in the course of the preparation of the second, revised version of the checklist of vascular plants of Asian Russia. The first version was published in 2012 (Baikov 2012). At the family level, we accepted the modern classification systems (APG IV for flowering plants, PPG I for lycophytes and ferns, and GPG for gymnosperms). At the genus level, we follow the generic concepts applied for particular taxonomic groups according to the Catalogue of Life (COL; https://www.catalogueoflife.org/), version COL23.5. At the species level, we consistently apply the monotypic species concept (also known in Russia as Komarov’s concept). In total, this paper presents one new nothogenus name (Γ— Sibirotrisetokoeleria Chepinoga nom. nov., Poaceae) and 156 new names in the rank of species, in 28 families: Amaranthaceae Juss. (1 name), Amaryllidaceae J.Β St.-Hil. (1), Apiaceae Lindl. (2), Asteraceae Bercht. & J.Presl (12), Boraginaceae Juss. (4), Caryophyllaceae Juss. (11), Crassulaceae J.Β St.-Hill. (3), Cyperaceae Juss. (8), Ericaceae Juss. (2), Fabaceae Lindl. (16), Gentianaceae Juss. (1), Geraniaceae Juss. (1), Juncaceae Juss. (1), Lamiaceae Martinov (1), Menyanthaceae Dumort. (1), Orchidaceae Juss. (1), Orobanchaceae Vent. (1), Papaveraceae Juss. (4), Plantaginaceae Juss. (1), Poaceae Barnhart (49), Polygonaceae Juss. (4), Primulaceae Batsch. ex Borkh. (6), Ranunculaceae Juss. (4), Rosaceae Juss. (5), Salicaceae Mirb. (2), Saxifragaceae Juss. (11), Vitaceae Juss. (1), Zygophyllaceae R.Β Br. (2 names)
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