49 research outputs found
Stucture and mechanical characteristics of vacuum arc TiN coatings deposited with high-voltage high frequency pulses on the substrate
Effect of Ion Irradiation on the Structural State of the Vacuum-Arc Nitride Coatings
The effect of irradiation with ions Ar+ (energy of 1 MeV and 1.8 MeV) and He (energy of 0.6 MeV) on
the structure and mechanical properties of the vacuum-arc nitride coatings. It is shown that the level of
exposure to radiation materials can be divided into 3 classes: a) “the most persistent” - significant changes
occur only on the substructure level (as an example - multi-element system Ti-Zr-V-Hf-Nb-Ta-N), b) “the
medium resistance “- significant changes occur in the macro stress-strained state (as an example - the system
Ti-N), c) “structural variable” – significant changes in the macro-level and phase composition (as an
example, the system Mo-N).
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3513
Low Threshold Parametric Decay Instabilities in ECRH experiments at toroidal devices
The experimental conditions leading to substantial reduction of
backscattering decay instability threshold in ECRH experiments in toroidal
devices are analyzed. It is shown that drastic decrease of threshold is
provided by non monotonic behaviour of plasma density, which is often observed
due to so-called density-pump-out effect or presence of magnetic islands, and
by poloidal magnetic field inhomogeniety making possible localization of ion
Bernstein decay waves. The corresponding ion Bernstein wave gain and the
parametric decay instability pump power threshold is calculated. The possible
experimental consequences of easy backscattering decay instability excitation
are discussed.Comment: 12 pages, 8 figures, submitted to Nuclear Fusio
Formation of MoO₃ crystals in electric arc plasma source
Formation of molybdenum trioxide crystals by electric arc discharge between molybdenum electrodes is considered. Molybdenum oxide crystals were deposited on side surface of anode. Observation of crystals formation zone was used for determination of main formations stages. Plasma temperature was estimated by optical emission spectroscopy method. The resulting products were studied by X-rays diffraction, time-of-flight laser mass-spectrometry and optical microscopy methods. It was found, that self-organizing vapor-deposition process of MoO₃ crystals formation has place. The resulting product is colorless sparkling prisms and platelets, which are mainly consist of orthorhombic α-MoO₃ phase. Optical microscopy indicates the formation of closely packed feather-like pin structures by vapor-solid process.Рассматривается формирование кристаллов триоксида молибдена при помощи электродугового разряда между молибденовыми электродами. Кристаллы формировались на боковой поверхности анода во время горения дуги. Эти кристаллы представляют собой прозрачные блестящие призмы и пластинки, состоящие, главным образом, из орторомбической фазы MoO₃. Для определения основных этапов формирования кристаллов, их химического состава и структуры применялись наблюдение зоны роста, рентгеноструктурный анализ, времяпролетная масс-спектрометрия и микроскопические исследования.Розглянуто формування кристалів триоксиду молібдену за допомогою електродугового розряду між молібденовими електродами. Кристали формувались на боковій поверхні анода під час горіння вільноіснуючої електричної дуги. Ці кристали являли собою прозорі блискучі призми та пластинки, які складались, головним чином, із орторомбічної фази MoO₃. Для визначення основних етапів формування кристалів, їх хімічного складу та структури застосовувались спостереження зони росту
The use of negative bias potential for structural engineering of vacuum-arc nitride coatings based on high-entropy alloys
The effect of negative bias potential (Ub = -40, -110, and -200 V) during the deposition of multi-element coatings on their composition, structure and mechanical properties was studied. It was established that during the transition from a multi-element alloy to a nitride, a single-phase state possible to form on its basis (based on the fcc metal lattice, structural type NaCl). In this case, the composition (FeCoNiCuAlCrV)N of coatings with increasing Ub is depleted by the element with the lowest enthalpy of formation of nitride (Cu). In (AlCrTiNbSi)N and (AlCrTiZrNbV)N coatings, the content of low-mass elements (Si and Al) decreases with increasing Ub. In (TiZrHfVNb)N coatings of strong nitride-forming elements with increasing Ub to 200 V, the composition practically does not change. The structure of such coatings is characterized by the presence of a texture with the [111] axis. The presence of weak nitride-forming elements in (FeCoNiCuAlCrV)N coatings leads to the formation of texture [110] for large Ub = 110…200 V. In such coatings, the hardness does not exceed 35 GPa. It is shown that to achieve high hardness at high Ub it is necessary to increase the content in the high-entropy alloy of elements with high nitrideforming ability. In this case, in (TiZrHfVNb)N coatings (made of strong nitride-forming elements with a large mass) at Ub = 200 V, the hardness exceeds 45 GPa.Досліджено вплив негативного потенціалу зміщення (Ub = -40, -110 і -200 В) при осадженні багатоелементних покриттів на їх склад, структуру і механічні властивості. Встановлено, що при переході від багатоелементного сплаву до нітриду на його основі можливе формування однофазного стану (на основі ГЦК металевої решітки структурний тип NaCl). При цьому склад (FeCoNiCuAlCrV)N-покриттів зі збільшенням Ub збіднюється елементом з найменшою ентальпією утворення нітриду (Cu). У (AlCrTiNbSi)N- і (AlCrTiZrNbV)N-покриттях зі збільшенням Ub зменшується вміст елементів з малою масою (Si і Al). У (TiZrHfVNb)N-покриттях, що складаються з сильних нітрідоутворюючих елементів з великою масою, при збільшенні Ub до 200 В склад практично не змінюється. Структура таких покриттів характеризується наявністю текстури з віссю [111]. Наявність слабких нітрідоутворюючих елементів у (FeCoNiCuAlCrV)Nпокриттях призводить при великих Ub = 110…200 В до формування текстури [110]. У таких покриттях твердість не перевищує 35 ГПа. Показано, що для досягнення високої твердості при великих Ub необхідно збільшувати вміст у високоентропійному сплаві елементів з високою нітрідоутворюючою здатністю. При цьому в (TiZrHfVNb)N-покриттях (з сильних нітрідоутворюючих елементів з великою масою) при Ub = 200 В твердість перевищує 45 ГПа.Исследовано влияние отрицательного потенциала смещения (Ub = -40, -110 и -200 В) при осаждении многоэлементных покрытий на их состав, структуру и механические свойства. Установлено, что при переходе от многоэлементного сплава к нитриду на его основе возможно формирование однофазного состояния (на основе ГЦК металлической решетки - структурный тип NaCl). При этом состав (FeCoNiCuAlCrV)Nпокрытий с увеличением Ub обедняется элементом с наименьшей энтальпией образования нитрида (Cu). В (AlCrTiNbSi)N- и (AlCrTiZrNbV)N-покрытиях с увеличением Ub уменьшается содержание элементов с малой массой (Si и Al). В (TiZrHfVNb)N-покрытиях из сильных нитридообразующих элементов с большой массой при увеличении Ub до 200 В состав практически не изменяется. Структура таких покрытий характеризуется наличием текстуры с осью [111]. Наличие слабых нитридообразующих элементов в (FeCoNiCuAlCrV)N-покрытиях приводит при больших Ub =110…200 В к формированию текстуры [110]. В таких покрытиях твердость не превышает 35 ГПа. Показано, что для достижения высокой твердости при больших Ub необходимо увеличивать содержание в высокоэнтропийном сплаве элементов с высокой нитридообразующей способностью. При этом в (TiZrHfVNb)N-покрытиях (из сильных нитридообразующих элементов с большой массой) при Ub = 200 В твердость превышает 45 ГПа
Competing orders in a magnetic field: spin and charge order in the cuprate superconductors
We describe two-dimensional quantum spin fluctuations in a superconducting
Abrikosov flux lattice induced by a magnetic field applied to a doped Mott
insulator. Complete numerical solutions of a self-consistent large N theory
provide detailed information on the phase diagram and on the spatial structure
of the dynamic spin spectrum. Our results apply to phases with and without
long-range spin density wave order and to the magnetic quantum critical point
separating these phases. We discuss the relationship of our results to a number
of recent neutron scattering measurements on the cuprate superconductors in the
presence of an applied field. We compute the pinning of static charge order by
the vortex cores in the `spin gap' phase where the spin order remains
dynamically fluctuating, and argue that these results apply to recent scanning
tunnelling microscopy (STM) measurements. We show that with a single typical
set of values for the coupling constants, our model describes the field
dependence of the elastic neutron scattering intensities, the absence of
satellite Bragg peaks associated with the vortex lattice in existing neutron
scattering observations, and the spatial extent of charge order in STM
observations. We mention implications of our theory for NMR experiments. We
also present a theoretical discussion of more exotic states that can be built
out of the spin and charge order parameters, including spin nematics and phases
with `exciton fractionalization'.Comment: 36 pages, 33 figures; for a popular introduction, see
http://onsager.physics.yale.edu/superflow.html; (v2) Added reference to new
work of Chen and Ting; (v3) reorganized presentation for improved clarity,
and added new appendix on microscopic origin; (v4) final published version
with minor change
Conformal and Affine Hamiltonian Dynamics of General Relativity
The Hamiltonian approach to the General Relativity is formulated as a joint
nonlinear realization of conformal and affine symmetries by means of the Dirac
scalar dilaton and the Maurer-Cartan forms. The dominance of the Casimir vacuum
energy of physical fields provides a good description of the type Ia supernova
luminosity distance--redshift relation. Introducing the uncertainty principle
at the Planck's epoch within our model, we obtain the hierarchy of the Universe
energy scales, which is supported by the observational data. We found that the
invariance of the Maurer-Cartan forms with respect to the general coordinate
transformation yields a single-component strong gravitational waves. The
Hamiltonian dynamics of the model describes the effect of an intensive vacuum
creation of gravitons and the minimal coupling scalar (Higgs) bosons in the
Early Universe.Comment: 37 pages, version submitted to Gen. Rel. Gra
Role of turbulence and electric fields in the establishment of improved confinement in tokamak plasmas
An extensive (INTAS) research programme started in 2002 to investigate the correlations between on the one hand the occurrence of
transport barriers and improved confinement in the medium-size tokamaks TEXTOR and T-10 and on the smaller tokamaks FT-2,
TUMAN-3M and CASTOR, and on the other hand electric fields, modified magnetic shear and electrostatic and magnetic turbulence
using advanced diagnostics with high spatial and temporal resolution and of various active means to externally control plasma transport .
This has been done in a strongly coordinated way and exploiting the complementarity of TEXTOR and T-10 and the backup potential of
the three other tokamaks, which together have all the relevant experimental tools and theoretical expertise
Total Cross Section Measurements With π- , Σ- And Protons On Nuclei And Nucleons Around 600 Gev/c
Total cross sections for Σ- and π- on beryllium, carbon, polyethylene and copper as well as total cross sections for protons on beryllium and carbon have been measured in a broad momentum range around 600GeV/c . These measurements were performed with a transmission technique in the SELEX hyperon-beam experiment at Fermilab. We report on results obtained for hadron-nucleus cross sections and on results for σtot(Σ-N) and σtot(π-N) , which were deduced from nuclear cross sections. © 2000 Elsevier Science B.V.57901/02/15277312Langland, J.L., (1995) Ph.D. Thesis, , University of IowaKleinfelder, S.A., (1988) IEEE Trans. Nucl. Sci., 35 (1)Dersch, U., (1998) Ph.D. Thesis, HeidelbergBiagi, S.F., (1981) Nucl. Phys. B, 186, pp. 1-21Bellettini, G., (1966) Nucl. Phys., 79, pp. 609-624Schiz, A.M., (1980) Phys. Rev. D, 21, pp. 3010-3022Murthy, P.V.R., (1975) Nucl. Phys. B, 92, pp. 269-308Caso, C., (1998) Eur. Phys. J. C, 3. , http://pdg.lbl.gov/1998/contents_plots.html, and data on total cross sections from computer readable filesSchiz, A.M., (1979) Ph.D. Thesis, , Yale University(1973) Landolt Börnstein Tables, 7. , Springer editionEngler, J., (1970) Phys. Lett. B, 32, pp. 716-719Babaev, A., (1974) Phys. Lett. B, 51, pp. 501-504Glauber, R.J., (1959) Boulder Lectures, pp. 315-413Franco, V., (1972) Phys. Rev. C, 6, pp. 748-757Karmanov, V.A., Kondratyuk, L.A., (1973) JETP Lett., 18, pp. 266-268Burq, J.P., (1983) Nucl. Phys. B, 217, pp. 285-335Gross, D., (1978) Phys. Rev. Lett., 41, pp. 217-220Beznogikh, G.G., (1972) Phys. Lett. B, 39, pp. 411-413Vorobyov, A.A., (1972) Phys. Lett. B, 41, pp. 639-641Foley, K.J., (1967) Phys. Rev. Lett., 19, pp. 857-859Fajardo, L.A., (1981) Phys. Rev. D, 24, pp. 46-65Jenni, P., (1977) Nucl. Phys. B, 129, pp. 232-252Breedon, R.E., (1989) Phys. Rev. Lett. B, 216, pp. 459-465Amos, N., (1983) Phys. Rev. Lett. B, 128, pp. 343-348Amaldi, U., (1977) Phys. Rev. Lett. B, 66, pp. 390-394Amos, N., (1985) Nucl. Phys. B, 262, pp. 689-714Akopin, V.D., (1977) Sov. J. Nucl. Phys., 25, pp. 51-55Amirkhanov, I.V., (1973) Sov. J. Nucl. Phys., 17, pp. 636-637Foley, K.J., (1969) Phys. Rev., 181, pp. 1775-1793Apokin, V.D., (1976) Nucl. Phys. B, 106, pp. 413-429Burq, J.P., (1982) Phys. Lett. B, 109, pp. 124-127Dakhno, L.G., (1983) Sov. J. Nucl. Phys., 37, pp. 590-598Kazarinov, M., (1976) Sov. Phys. JETP, 43, pp. 598-606De Jager, C.W., (1974) At. Data Nucl. Data Tables, 14, pp. 479-508Donnachie, A., Landshoff, P.V., (1992) Phys. Lett. B, 296, pp. 227-232Lipkin, H., (1975) Phys. Rev. D, 11, pp. 1827-1831Barnett, R.M., (1996) Phys. Rev. D, 54, pp. 191-192Carroll, A.S., (1979) Phys. Lett. B, 80, pp. 423-427Badier, J., (1972) Phys. Lett. B, 41, pp. 387-39