184 results on '"N. V. Sakharov"'
Search Results
52. Development of composite ceramic materials with improved thermal conductivity and plasticity based on garnet-type oxides
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V. N. Chuvil’deev, L.S. Golovkina, A. I. Orlova, A. V. Nokhrin, N. V. Sakharov, D. Staicu, R.J.M. Konings, and Maksim Boldin
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010302 applied physics ,Nuclear and High Energy Physics ,Materials science ,Oxide ,Spark plasma sintering ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Indentation hardness ,chemistry.chemical_compound ,Nickel ,Fracture toughness ,Thermal conductivity ,Nuclear Energy and Engineering ,chemistry ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,General Materials Science ,Ceramic ,Composite material ,0210 nano-technology ,Wet chemistry - Abstract
Powders based on the complex garnet-type oxide Y2.5Nd0.5Al5O12 - x wt. % Ni (x = 0, 10, 20) were prepared using wet chemistry methods. Ceramics based on these compounds were obtained by Spark Plasma Sintering (SPS) with a relative densities: 99%. 4% (TD = 4.77 g/cm3 (0%)), 97.6% (TD = 4.88 g/cm3 (10%)), 94.4% (TD = 5.06 g/cm3 (20%)). The influence of nickel concentration on the mechanical (fracture toughness, microhardness) and thermophysical (thermal conductivity) properties of the composites was studied.
- Published
- 2017
53. Spark plasma sintering of tungsten carbide nanopowders obtained through DC arc plasma synthesis
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N. V. Sakharov, Yu. V. Blagoveshchenskiy, S. V. Shotin, A. V. Nokhrin, E. A. Lantsev, O. A. Belkin, A. A. Popov, V. N. Chuvil’deev, N. V. Isaeva, Maksim Boldin, and E. S. Smirnova
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Materials science ,020502 materials ,Mechanical Engineering ,Metallurgy ,Metals and Alloys ,Nanoparticle ,Sintering ,Spark plasma sintering ,02 engineering and technology ,Abnormal grain growth ,021001 nanoscience & nanotechnology ,Grain growth ,chemistry.chemical_compound ,Fracture toughness ,0205 materials engineering ,chemistry ,Mechanics of Materials ,Tungsten carbide ,Materials Chemistry ,Grain boundary diffusion coefficient ,0210 nano-technology - Abstract
The paper dwells on the research conducted into high-rate consolidation of pure tungsten carbide (WC) nanopowders using the Spark Plasma Sintering technology. Studies included the effect that the original size of WC nanoparticles and their preparation modes have on density, structure parameters, and mechanical properties of tungsten carbide. Samples of high-density nanostructured tungsten carbide characterized by high hardness (up to 31–34 GPa) and improved fracture toughness (4.3–5.2 MPa m 1/2 ) were obtained. It has been found that materials that show abnormal grain growth during sintering have lower values of sintering activation energy as compared to materials the structure of which is more stable during high-rate heating. A qualitative model is proposed that explains this effect through the dependence of the grain boundary diffusion coefficient on the grain boundary migration rate.
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- 2017
54. Characteristics of major plasma discharge disruption in the Globus-M spherical tokamak
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M. I. Patrov, N. V. Sakharov, A. A. Kavin, V. K. Gusev, S. N. Kamenshchikov, A. D. Iblyaminova, K.M. Lobanov, S. Yu. Tolstyakov, A.B. Mineev, G. S. Kurskiev, and Yu. V. Petrov
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Electron density ,Materials science ,Toroid ,Tokamak ,Physics and Astronomy (miscellaneous) ,Plasma ,Spherical tokamak ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Ion ,law.invention ,Physics::Plasma Physics ,law ,0103 physical sciences ,Diamagnetism ,Atomic physics ,Current (fluid) ,010306 general physics - Abstract
The characteristics of the major disruption of plasma discharges in the Globus-M spherical tokamak are analyzed. The process of current quench is accompanied by the loss of the vertical stability of the plasma column. The plasma boundary during the disruption is reconstructed using the algorithm of movable filaments. The plasma current decay is preceded by thermal quench, during which the profiles of the temperature and electron density were measured. The data on the time of disruption, the plasma current quench rate, and the toroidal current induced in the tokamak vessel are compared for hydrogen and deuterium plasmas. It is shown that the disruption characteristics depend weakly on the ion mass and the current induced in the vessel increases with the disruption time. The decay rate of the plasma toroidal magnetic flux during the disruption is determined using diamagnetic measurements. Such a decay is a source of the poloidal current induced in the vessel; it may also cause poloidal halo currents.
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- 2017
55. GLOBUS-M EXPERIMENTS WITH PRE-DAMAGED TUNGSTEN DIVERTOR
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N.V. Litunovsky, A. A. Gervash, B. Ya. Ber, Electrochemistry Ras, R. Kh. Zalavutdinov, E. E. Mukhin, A. N. Novokhatsky, Pavel N. Brunkov, A. V. Voronin, S.A. Grigoriev, V.E. Kuznetsov, S. Yu. Tolstyakov, V.N. Tanchuk, I.V. Mazul, A.E. Gorodetsky, A.P. Zakharov, V. K. Gusev, A. Makhankov, R.V. Sokolov, N. V. Sakharov, Yu. V. Petrov, T. V. Rybkina, and V. L. Bukhovets
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Nuclear and High Energy Physics ,Materials science ,Nuclear Energy and Engineering ,chemistry ,Nuclear engineering ,Divertor ,0103 physical sciences ,chemistry.chemical_element ,Tungsten ,010306 general physics ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas - Published
- 2017
56. STUDY OF KINETIC PARAMETERS OF GLOBUS-M PLASMA BY THOMSON SCATTERING USING ADVANCED DIGITAL POLYCHROMATOR
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Vladimir V. Semenov, E.E. Mukhin, A.N. Koval, S.V. Masyukevich, P.V. Chernakov, G. S. Kurskiev, An.P. Chernakov, A.N. Bazhenov, A.G. Razdobarin, V.V. Solokha, N.A. Babinov, A. M. Dmitriev, M.M. Kochergin, N. V. Sakharov, A.E. Litvinov, V. K. Gusev, I.M. Bukreev, V.A. Solovey, D.S. Samsonov, S. Yu. Tolstyakov, Al.P. Chernakov, and Yu. V. Petrov
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010302 applied physics ,Physics ,Nuclear and High Energy Physics ,Thomson scattering ,business.industry ,Plasma ,Condensed Matter Physics ,Kinetic energy ,01 natural sciences ,010305 fluids & plasmas ,Polychromator ,Optics ,Nuclear Energy and Engineering ,0103 physical sciences ,business - Published
- 2017
57. The Effect of Low-Frequency Magnetohydrodynamic Modes on the Development of Filaments in the Globus-M Tokamak
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M. I. Patrov, V. B. Minaev, D. V. Prisyazhnyuk, Yu. V. Petrov, A. Yu. Yashin, A. V. Petrov, N.A. Khromov, V. V. Solokha, V. K. Gusev, V. V. Bulanin, N. V. Sakharov, G. S. Kurskiev, and S. Yu. Tolstyakov
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Tokamak ,Physics and Astronomy (miscellaneous) ,macromolecular substances ,02 engineering and technology ,Spherical tokamak ,01 natural sciences ,Quantitative Biology::Cell Behavior ,law.invention ,Quantitative Biology::Subcellular Processes ,Protein filament ,symbols.namesake ,Physics::Plasma Physics ,law ,0103 physical sciences ,Tearing ,Magnetohydrodynamic drive ,010302 applied physics ,Physics ,Toroid ,Plasma ,021001 nanoscience & nanotechnology ,Computational physics ,Physics::Space Physics ,symbols ,0210 nano-technology ,Doppler effect - Abstract
Experimental data are presented that indicate the effect of the magnetohydrodynamic tearing mode in the Globus-M spherical tokamak on the occurrence of filamentary structures (filaments). The filaments are recorded by the Doppler backscattering method. The groups of filaments localized in the toroidal direction are discovered, the appearance of which is synchronized with the propagation of the tearing mode. Possible causes of the effect of low-frequency magnetohydrodynamic oscillations on the occurrence of filament groups are considered.
- Published
- 2019
58. The study of filaments by the Doppler backscattering method in the 'Globus-M' tokamak
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D. Prisiazhniuk, Yu. V. Petrov, G. S. Kurskiev, N. V. Sakharov, M. A. Petrov, N. A. Khromov, A. Yu. Yashin, V. V. Bulanin, V. B. Minaev, S. Yu. Tolstyakov, A. V. Petrov, M. I. Patrov, and V. K. Gusev
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Physics ,Nuclear and High Energy Physics ,symbols.namesake ,Optics ,Tokamak ,business.industry ,law ,symbols ,Condensed Matter Physics ,Edge-localized mode ,business ,Doppler effect ,law.invention - Published
- 2019
59. Thermal expansion of scheelite-like molybdate powders and ceramics
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S. A. Khainakov, Santiago García-Granda, E. A. Lantsev, V. N. Chuvil’deev, N. V. Sakharov, A. A. Murashov, E. A. Potanina, M. G. Tokarev, Maksim Boldin, A. I. Orlova, A. V. Nokhrin, and Russian Science Foundation
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010302 applied physics ,Range (particle radiation) ,Materials science ,General Chemical Engineering ,Metals and Alloys ,Analytical chemistry ,Spark plasma sintering ,02 engineering and technology ,Molybdate ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,01 natural sciences ,Thermal expansion ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,visual_art ,Scheelite ,0103 physical sciences ,Materials Chemistry ,visual_art.visual_art_medium ,Ceramic ,0210 nano-technology ,Solid solution - Abstract
NaxSr1 – 2xNdxMoO4 (x = 0–0.5, Δx = 0.1) solid solutions with the scheelite structure have been synthesized for the first time and their crystallographic parameters have been determined as functions of composition and temperature. Their thermal expansion coefficients have been determined in the temperature range 25–1000°C: αa = (12.9–14.9) × 10–6 °C–1 and αc = (24.9–25.9) × 10–6 °C–1. Using spark plasma sintering at tmax ≈ 872–985°C and τ ≈ 650–750 s, we have prepared ceramics with relative densities in the range 97–99%., This work was supported by the Russian Science Foundation, project no. 16-13-10464: Promising Mineral-Like Ceramic Materials with Improved and Controlled Functional Characteristics: Development, Synthesis, and Characterization.
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- 2019
60. Globus-M2 experiments in scope of fusion-fission reactor development
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N. N. Bakharev, N. A. Khromov, P. B. Shchegolev, A. N. Konovalov, V. A. Tokarev, E. A. Tukhmeneva, V. B. Minaev, A. D. Melnik, F. V. Chernyshev, A. Yu. Telnova, A. V. Voronin, I. V. Miroshnikov, N. V. Sakharov, V. V. Dyachenko, A. N. Novokhatsky, S. Yu. Tolstyakov, G. S. Kurskiev, V. I. Varfolomeev, E. O. Kiselev, Yu. V. Petrov, M. I. Patrov, and V. K. Gusev
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Materials science ,Toroid ,Physics::Plasma Physics ,Nuclear engineering ,Fusion fission ,Neutron ,Plasma ,Spherical tokamak ,Current (fluid) ,Lower hybrid oscillation ,Magnetic field - Abstract
A new generation spherical tokamak Globus-M2 was launched in 2018. It keeps size of Globus-M, however new electromagnetic system allows achieving higher toroidal magnetic field and plasma current. First experimental campaign with the toroidal magnetic field 0.7 T and plasma current up to 300 kA was carried out in 2019. Increase in the toroidal magnetic field and plasma current resulted in overall improvement of the discharge parameters. Significant plasma temperature growth and neutron rate increase was obtained. Record stored energy, which is approximately one and a half times higher than in the Globus-M experiments, was reached. Toroidal lower hybrid wave launch provided noticeable current drive. Preparation for the next experimental campaigns with the higher toroidal magnetic field and plasma current are on the way.
- Published
- 2019
61. Tenfold increase in the fusion triple product caused by doubling of toroidal magnetic field in the spherical tokamak Globus-M2
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N. V. Sakharov, I. M. Balachenkov, I V Miroshnikov, M. I. Patrov, F. V. Chernyshev, V. B. Minaev, Yu. V. Petrov, N. A. Khromov, A. A. Petrov, N. N. Bakharev, N.S. Zhiltsov, E. O. Kiselev, Sergey Tolstyakov, V. A. Tokarev, A. A. Kavin, P. B. Shchegolev, G. S. Kurskiev, Ann Yu Telnova, V. I. Varfolomeev, E. A. Tukhmeneva, Alexander Yashin, V. V. Bulanin, and V. K. Gusev
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Physics ,Nuclear and High Energy Physics ,Fusion ,Toroid ,Triple product ,Spherical tokamak ,Condensed Matter Physics ,Magnetic field ,Computational physics - Abstract
The current work reports on the significant rise of the fusion triple product in experiments carried out on the compact spherical tokamak (ST) Globus-M2 with a twofold increase in the toroidal magnetic field. A tenfold rise in the n . T . τ E product was recorded during an increase in the magnetic field from 0.4 to 0.8 T and the plasma current from 0.25 to 0.4 MA at an unchanged auxiliary heating power value. Limited reasons may affect this positive trend, among which are energy confinement improvement and an increase in the efficiency of neutral beam heating. Despite the increase in the magnetic field, the neutral beam injection (NBI) led to clear and reproducible transition to the H-mode accompanied by a decrease in the turbulence level at the plasma edge. It was experimentally confirmed that strong dependence of the energy confinement time on the magnetic field value is conserved at a higher magnetic field approaching 0.8 T. Enhancement of energy confinement is connected to a collisionality (ν *) decrease. While for conventional tokamaks the confinement dependence on collisionality becomes weaker with decreasing ν * dependence, in the ST, in contrast, we observe its strengthening.
- Published
- 2021
62. Control of tokamak discharge parameters using a plasma jet
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A. N. Novokhatsky, N. V. Sakharov, V. K. Gusev, A. V. Voronin, V. Yu. Goryainov, Yu. V. Petrov, and V. B. Minaev
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History ,Tokamak ,Materials science ,law ,Nuclear engineering ,Plasma jet ,Computer Science Applications ,Education ,law.invention - Abstract
Results of the experimental study of the ability of plasma jet of coaxial accelerator to breakdown and ionization the working gas at the initial discharge phase in Globus-M2 spherical tokamak are presented. Studies of the development of the initial stage of discharge initiated with a plasma jet showed that the plasma current in the discharge began to grow earlier by 2 ms than using the standard inductive breakdown. The breakdown voltage decreased from 6.1 to 3.1 V (-49%) at 4.7 kV accelerator electrode voltage. The emission intensity of line Dα decreased during formation of the discharge with the help of plasma jet without additional gas puffing. Radiation level CIII in the discharge generated by the plasma jet was the same as the radiation in discharge produced by induction breakdown of the gas. At the stage of increase in the plasma current the most intense visible radiation of the plasma was found near duct through which the jet was injected. Discharge radiation decreased and spread out along the cross section of the plasma column during plasma current plateau.
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- 2020
63. Influence of increased magnetic field on Alfvén eigenmodes on upgraded spherical tokamak Globus-M2
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N. N. Bakharev, P. B. Shchegolev, A. Yu. Yashin, V. V. Dyachenko, E. O. Kiselev, M. I. Patrov, A. N. Konovalov, V. K. Gusev, V. B. Minaev, A. M. Ponomarenko, I. M. Balachenkov, S. V. Krikunov, G. S. Kurskiev, V. V. Bulanin, A. Yu. Telnova, Yu. V. Petrov, N.S. Zhiltsov, N. V. Sakharov, A. V. Petrov, and V. I. Varfolomeev
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Physics ,History ,Spherical tokamak ,Computer Science Applications ,Education ,Magnetic field ,Computational physics - Abstract
During modernization of the Globus-M tokamak, toroidal magnetic field and plasma current were increased, and a number of diagnostics were upgraded, which made it possible to study phenomena associated with the excitation of Alfvén waves in a spherical tokamak in a wider range of plasma parameters. In the experiments with neutral beam injection, the dependences of fast particle losses initiated by the toroidal Alfvén eigenmodes (TAE) on their magnitude in the magnetic field range of 0.4 – 0.7 T and currents of 180 – 330 kA were acquired. Resulting dependences confirm previously obtained results and indicate a decrease in losses with increasing magnetic field and plasma current. At the same time, a number of new phenomena, that have never been observed on Globus-M were detected. In experiments with neutral beam injection at the current ramp up stage, Alfvén cascades (AC) in the frequency range of 100 – 300 kHz were observed for the first time. By means of the Doppler backscattering diagnostics (DBS), it was shown that ACs are localized closer to magnetic axis unlike TAE. Also, during low hybrid wave current drive (LHCD) experiments, global Alfvén eigenmodes (GAE) were detected at a frequency close to 1 MHz, apparently driven in the resonance with runaway electron beam. Detected global eigenmodes are also able to arise in ohmic discharges, however, their magnitude is lower.
- Published
- 2020
64. Investigation of the plasma radiation power in the Globus-M tokamak by means of SPD silicon photodiodes
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S. Yu. Tolstyakov, N. V. Sakharov, V. V. Zabrodsky, N. N. Bakharev, Yu. V. Petrov, A. D. Iblyaminova, V. K. Gusev, P. B. Shchegolev, M. I. Patrov, P. N. Aruev, G. S. Kurskiev, V. B. Minaev, G. F. Avdeeva, and I. V. Miroshnikov
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010302 applied physics ,Tokamak ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Time evolution ,Plasma ,Radiation ,Condensed Matter Physics ,01 natural sciences ,Neutral beam injection ,010305 fluids & plasmas ,law.invention ,Power (physics) ,Photodiode ,Optics ,law ,0103 physical sciences ,Atomic physics ,business ,Ohmic contact - Abstract
Radiation losses from the plasma of the Globus-M tokamak are studied by means of SPD silicon photodiodes developed at the Ioffe Institute, Russian Academy of Sciences. The results from measurements of radiation losses in regimes with ohmic and neutral beam injection heating of plasmas with different isotope compositions are presented. The dependence of the radiation loss power on the plasma current and plasma–wall distance is investigated. The radiation power in different spectral ranges is analyzed by means of an SPD spectrometric module. Results of measurements of radiation losses before and after tokamak vessel boronization are presented. The time evolution of the sensitivity of the SPD photodiode during its two-year exploitation in Globus-M is analyzed.
- Published
- 2016
65. Lanthanide (Nd, Gd) compounds with garnet and monazite structures. Powders synthesis by 'wet' chemistry to sintering ceramics by Spark Plasma Sintering
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A. V. Nokhrin, Ludmila Golovkina, N. V. Sakharov, A. I. Orlova, Maksim Boldin, and Ekaterina Potanina
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010302 applied physics ,Lanthanide ,Nuclear and High Energy Physics ,Materials science ,Metallurgy ,Sintering ,Spark plasma sintering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Grain growth ,Nuclear Energy and Engineering ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Grain boundary diffusion coefficient ,General Materials Science ,Ceramic ,0210 nano-technology ,Wet chemistry ,Sol-gel - Abstract
Complex oxide Y 2.5 Nd 0.5 Al 5 O 12 with garnet structure and phosphates NdPO 4 and GdPO 4 with monazite structure were obtained by using precipitation methods. Ceramics Y 2.5 Nd 0.5 Al 5 O 12 and NdPO 4 were processed by Spark Plasma Sintering (SPS). Relative density more 98%, sintering time did not exceed 8 min, sintering temperature 1330–1390 °C. Leaching rates of elements from ceramics were 10 −6 –10 −7 g/(cm 2 d). The process of ceramics sintering has two-stage character: the first step of sintering-compaction process is related to the plastic flow of the material, the second step–to the process of grain boundary diffusion and grain growth.
- Published
- 2016
66. A ZERO-DIMENTIONAL MODEL TO STUDY PLASMA HEATING EFFICIENCY AND THERMAL INSULATION AT THE GLOBUS-M TOKAMAK IN OHMIC HEATED REGIMES
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N. N. Bakharev, G. F. Avdeeva, V. B. Minaev, V. K. Gusev, Yu. V. Petrov, G. S. Kurskiev, A. Yu. Telnova, A. D. Iblyaminova, M. I. Patrov, P. B. Schegolev, S. Yu. Tolstyakov, I. V. Miroshnikov, E. O. Kiselev, V. A. Tokarev, and N. V. Sakharov
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Nuclear and High Energy Physics ,Tokamak ,Materials science ,Plasma heating ,business.industry ,Zero (complex analysis) ,Mechanics ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Nuclear Energy and Engineering ,law ,Thermal insulation ,0103 physical sciences ,010306 general physics ,business ,Ohmic contact - Published
- 2016
67. Reconstruction of equilibrium magnetic configurations in the Globus-M spherical tokamak
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A. A. Kavin, A. V. Voronin, V. K. Gusev, N. V. Sakharov, P. B. Shchegolev, S. N. Kamenshchikov, Yu. V. Petrov, A.N. Novokhatsky, M. I. Patrov, V. B. Minaev, and K.M. Lobanov
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Surface (mathematics) ,Physics ,Toroid ,Physics and Astronomy (miscellaneous) ,Divertor ,Plasma ,Spherical tokamak ,Condensed Matter Physics ,Neutral beam injection ,Computational physics ,Grad–Shafranov equation ,Physics::Plasma Physics ,Electric current ,Atomic physics - Abstract
The results of reconstruction of equilibrium magnetic configurations in the Globus-M spherical tokamak by means of the EFIT code and by the method of movable filaments with the use of the data from magnetic measurements are compared. The EFIT code allows one to completely reconstruct the magnetic configuration by solving the Grad−Shafranov equation. In the method of movable filaments, the distribution of the toroidal current flowing through the plasma is described by a set of infinitely thin current-carrying rings. In this method, the last closed magnetic surface (LCMS) and the open surfaces lying beyond the LCMS are calculated. Using both methods, the coordinates of the regions where the separatrix strikes the divertor plates were determined. The results obtained agree well with the distributions of the temperature over the tungsten divertor tiles measured using an IR camera.
- Published
- 2015
68. Ion temperature measurements in a tokamak using active neutral particle analyzers diagnostics
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A. D. Melnik, M. I. Mironov, O. M. Skrekel, E. O. Kiselev, N. V. Sakharov, F. V. Chernyshev, M. M. Larionova, I. V. Miroshnikov, V. I. Varfolomeev, Yu. V. Petrov, G. S. Kurskiev, V. K. Gusev, P. B. Shchegolev, A. Yu. Telnova, E. A. Tukhmeneva, V. B. Minaev, and N. N. Bakharev
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Tokamak ,Materials science ,Nuclear Energy and Engineering ,Physics::Plasma Physics ,law ,Ion temperature ,Atomic physics ,Condensed Matter Physics ,Neutral particle ,law.invention - Abstract
Active ion temperature measurement in the core plasma of a tokamak using active neutral particle analyzers (NPA) diagnostics is considered. Two approaches for local ion temperature reconstruction are reviewed: semi-analytical and iterative. A semi-analytical approach allows the calculation of ion temperature using simple expression, while a more complex iterative approach provides more flexibility. Problems associated with active NPA measurements and their possible solutions are discussed. An example of the core ion temperature profile reconstruction in the compact spherical tokamak Globus-M2 using both approaches is shown. Problems associated with active ion temperature measurements in a compact reactor and possible solutions are considered.
- Published
- 2020
69. Fabrication of fine-grained CeO2-SiC ceramics for inert fuel matrices by Spark Plasma Sintering
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V. N. Chuvil’deev, Eugeniy Lantsev, N. V. Sakharov, Lyudmila Alekseeva, Maksim Boldin, A. V. Nokhrin, and A. I. Orlova
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Inert ,Nuclear and High Energy Physics ,Fabrication ,Materials science ,Composite number ,chemistry.chemical_element ,Spark plasma sintering ,Sintering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,010305 fluids & plasmas ,Cerium ,Nuclear Energy and Engineering ,chemistry ,Chemical engineering ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,General Materials Science ,Ceramic ,0210 nano-technology - Abstract
The possibility to fabricate highly dense (95.3–95.8% of theoretical density) composite ceramics CeO2 – x α-SiC (x = 10, 20 vol %) as a promising mineral-like material for the inert fuel matrices (IFM) by Spark Plasma Sintering (SPS) has been explored. The kinetics of SPS of the CeO2 – SiC composites in the heating-up conditions was found to have a multi-stage character. The introduction of the α-SiC particles resulted in a shift of the characteristic sintering temperatures towards higher values, allows forming the highly dense fine-grained structure, and leads to increasing of the thermal conductivity of the cerium dioxide – based ceramics.
- Published
- 2020
70. Digital filter polychromator for Thomson scattering applications
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A.V. Lukoyanova, P.V. Chernakov, A. V. Gorshkov, V. I. Varfolomeev, V.A. Solovey, A.N. Bazhenov, V. K. Gusev, E.E. Mukhin, N.S. Zhiltsov, V. B. Minaev, Al.P. Chernakov, S. Yu. Tolstyakov, I. S. Bel’bas, A. N. Novokhatsky, M. I. Patrov, V.A. Senichenkov, G.M. Asadulin, G. S. Kurskiev, E. O. Kiselev, N. V. Sakharov, Yu. V. Petrov, S.E. Aleksandrov, and A.N. Koval
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Physics ,Nuclear and High Energy Physics ,Optical fiber ,business.industry ,Stray light ,Noise (signal processing) ,Thomson scattering ,Gigabit Ethernet ,Signal ,law.invention ,Polychromator ,Optics ,Data acquisition ,law ,business ,Instrumentation - Abstract
The paper describes the digital filter polychromator developed for Thomson scattering (TS) diagnostics. The device having ultra-low noise, high-speed detection system and up to 7 spectral channels is equipped with digitizer and single board computer for system control and data processing. The data acquisition system is capable to detect very short laser pulses of few ns width with low magnitude. This feature opens up new possibilities for the TS diagnostics design in modern fusion devices, which includes: operation with high background illumination, measurement of very low electron temperature and density at the plasma edge and scrape-off layer (SOL), separation of the TS signal and the stray light coming with a delay of several ns. The analysis of the TS signal waveform also gives a possibility to distinguish the TS and Mie scattering from the dust particles that is important for measurements in SOL. Owing to compactness and ultra-low energy consumption both optical and data processing units interfaced with optical Gigabit Ethernet were combined in a stand-alone device. Such all-in-one design with optical fiber input and optical digital output provides enhanced resistance to electromagnetic disturbances and simplify operation. A set of such polychromators can be mounted in a standard 19” rack and can be integrated with outer CODAC (Control, Data Access and Communication) system. Testing of the polychromators at the Globus-M2 tokamak has shown excellent performance of the developed serial devices.
- Published
- 2020
71. Ion heat transport study in the Globus-M spherical tokamak
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M. I. Patrov, A. Yu. Telnova, G. S. Kurskiev, Yu. V. Petrov, E. A. Tukhmeneva, V. K. Gusev, S. Yu. Tolstyakov, N. V. Sakharov, I V Miroshnikov, E. O. Kiselev, D M Larionova, V. A. Tokarev, M. M. Larionova, A D Sladkomedova, N. N. Bakharev, P. B. Shchegolev, V. B. Minaev, and N. A. Khromov
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Materials science ,Nuclear Energy and Engineering ,Atomic physics ,Spherical tokamak ,Condensed Matter Physics ,Ion - Published
- 2020
72. Plasma effective charge diagnostics at the Globus-M2 tokamak
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E. A. Tukhmeneva, N. N. Bakharev, Yu. V. Petrov, P. B. Shegolev, S. Yu. Tolstyakov, A. Yu. Telnova, V. B. Minaev, G. S. Kurskiev, E. O. Kiselev, N. V. Sakharov, and V. K. Gusev
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Physics ,History ,Thesaurus (information retrieval) ,Tokamak ,law ,business.industry ,Plasma ,Aerospace engineering ,business ,Effective nuclear charge ,Computer Science Applications ,Education ,law.invention - Abstract
The conventional method for determining the effective ion charge Zeff is based on measurements of the bremsstrahlung intensity in the spectral regions free from line radiation. This paper describes the design of the Zeff diagnostics at the Globus-M tokamak as well as the results of the first measurements. With allowance for the emission intensity estimates, the geometry of the experiment was chosen; the filter monochromators for recording bremsstrahlung were designed and manufactured. Using the Thomson scattering data on T e (R) and n e (R) profiles, time dependences Zeff (t) were obtained in several shots of the Globus-M tokamak. The results of simulations Z eff performed using the ASTRA transport code are consistent with these measurements.
- Published
- 2019
73. Calculations of anisotropic distribution function of fast particles in plasma of the Globus-M spherical tokamak using the NUBEAM code
- Author
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V. K. Gusev, M. I. Patrov, A. Yu. Telnova, I. V. Miroshnikov, P. R. Goncharov, V. A. Tokarev, N. A. Khromov, V. B. Minaev, G. S. Kurskiev, E. O. Kiselev, N. V. Sakharov, Yu. V. Petrov, E. A. Tukhmeneva, N. N. Bakharev, A. D. Melnik, P. B. Schegolev, and S. Yu. Tolstyakov
- Subjects
Physics ,History ,Code (set theory) ,Distribution function ,Physics::Plasma Physics ,Plasma ,Spherical tokamak ,Anisotropy ,Computer Science Applications ,Education ,Computational physics - Abstract
The results from calculations of the anisotropic fast particle distribution function in the Globus-M/M2 spherical tokamaks are presented. The calculations were performed using the NUEBAM code, the reasons for the anisotropy occurrence are discussed (injection geometry, low toroidal magnetic field and plasma current, presence of neutral particles). It is shown that the anisotropy decreases with increasing toroidal magnetic field and plasma current: the density of the slowed down fast ions with energies of E < 4 keV almost doubles and the averaged perpendicular velocity of fast ions increases.
- Published
- 2019
74. CXRS measurements of ion temperature profile in NBI shots of the Globus-M spherical tokamak
- Author
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M. I. Patrov, N. N. Bakharev, V. B. Minaev, A. Yu. Telnova, I. V. Miroshnikov, N. V. Sakharov, M. M. Larionova, V. K. Gusev, P. B. Schegolev, and Yu. V. Petrov
- Subjects
History ,Materials science ,Physics::Plasma Physics ,Ion temperature ,Atomic physics ,Spherical tokamak ,Computer Science Applications ,Education - Abstract
Ion temperature is one of the most important parameters of high-temperature plasma. Information on the ion temperature spatial distribution is necessary for understanding and modelling of particle and energy transport processes, evaluating the effectiveness of plasma heating system operation. Active spectroscopy also known as CXRS (Charge eXchange Recombination Spectroscopy) is a powerful diagnostic tool for measurements of local values of ion temperature, and is widely used in experiments with magnetic confinement of high-temperature plasma. Active spectroscopy diagnostics on the Globus-M tokamak utilizes a tangentially injected heating beam of neutrals (hydrogen or deuterium atoms). The CXRS-system setup is described. The results of ion temperature measurements for the last Globus-M experimental campaign before the machine shutdown and further upgrading to higher values of magnetic field and plasma current are presented. Ion temperature significant rise in the experiments with moderate increasing of toroidal magnetic field and plasma current is detected and discussed.
- Published
- 2019
75. Fast scanning probe for the Globus-M2 tokamak
- Author
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V. B. Minaev, P. B. Shegolev, N. V. Sakharov, N. A. Khromov, V. K. Gusev, A. Yu. Telnova, M. I. Patrov, Yu. V. Petrov, N. N. Bakharev, G. S. Kurskiev, E. O. Kiselev, V. A. Tokarev, and V. I. Varfolomeev
- Subjects
History ,Optics ,Tokamak ,Materials science ,business.industry ,law ,Fast scanning ,business ,Computer Science Applications ,Education ,law.invention - Abstract
A fast scanning probe which can penetrate inside the separatrix during discharge was developed for Globus-M2. The probe has been designed to move various sensor pins into the scrape-off layer. The driving force is provided by a crank-slider mechanism which is ensured maximum linear speed about 4 m/s. The paper presents probe head and drive system description.
- Published
- 2019
76. Preparation of NZP-type Ca0.75+0.5xZr1.5Fe0.5(PO4)3-x(SiO4)x powders and ceramic, thermal expansion behavior
- Author
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Maksim Boldin, E. A. Lantsev, Santiago García-Granda, A. A. Murashov, A. V. Nokhrin, A. A. Aleksandrov, S. A. Khainakov, A. I. Orlova, V. N. Chuvil’deev, N. V. Sakharov, and D. O. Savinykh
- Subjects
010302 applied physics ,Materials science ,General Chemical Engineering ,Metals and Alloys ,Analytical chemistry ,Infrared spectroscopy ,Spark plasma sintering ,02 engineering and technology ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,01 natural sciences ,Thermal expansion ,Inorganic Chemistry ,Differential scanning calorimetry ,visual_art ,0103 physical sciences ,X-ray crystallography ,Materials Chemistry ,visual_art.visual_art_medium ,Ceramic ,0210 nano-technology ,Solid solution - Abstract
Ca0.75 + 0.5xZr1.5Fe0.5(PO4)3 –x(SiO4)x (x = 0–0.5) solid solutions have been synthesized by a sol–gel process and characterized by X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. As expected, the synthesized phosphatosilicates crystallize in a NaZr2(PO4)3-type structure (trigonal symmetry, sp. gr. R $$\bar {3}$$ c). The thermal expansion of the solid solutions has been studied by high-temperature X-ray diffraction in the temperature range from 25 to 800°C. Their thermal expansion parameters have been calculated and analyzed as functions of composition. High-density ceramics based on the Ca0.875Zr1.5Fe0.5(PO4)2.75(SiO4)0.25 phosphatosilicate have been produced by spark plasma sintering and their structure and properties have been studied in detail.
- Published
- 2018
77. Methods of compacting nanostructured tungsten–cobalt alloys from Nanopowders obtained by plasma chemical synthesis
- Author
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S. V. Shotin, Yu. V. Blagoveshchenskiy, A. V. Nokhrin, Ye. S. Smirnov, N. V. Blagoveshchenskaya, Yu. I. Mel'nik, G. M. Voldman, Yu. V. Levinsky, V. N. Chuvildeyev, N. V. Sakharov, Maksim Boldin, and N. V. Isayeva
- Subjects
Materials science ,Metallurgy ,General Engineering ,Compaction ,chemistry.chemical_element ,Spark plasma sintering ,Sintering ,Tungsten ,Grain size ,chemistry.chemical_compound ,Fracture toughness ,chemistry ,Tungsten carbide ,General Materials Science ,Cobalt - Abstract
The paper summarizes the experience of using traditional and modern methods of sintering WC–Co nanopowders obtained by plasma chemical synthesis. A comparative analysis of structure formation processes occurring at sintering WC–Co nanopowders in a quasi-steady and high-speed heating is carried out. It is shown that the basic regularities of structure evolution during sintering are rather general in nature and are similar both to conventional vacuum sintering and to high-energy compaction methods. It was established that, under high-speed heating conditions, a significant contribution to the acceleration of the sintering of nanopowder materials at low temperatures is made not only by a small grain size but also the process of grainboundary diffusion. It is shown that the samples of hard alloys sintered from tungsten carbide nanopowders produced by plasma chemical synthesis have significantly higher hardness and fracture toughness than those produced using conventional synthesis techniques and compacting. Using the technology of plasma chemical synthesis and spark plasma sintering, nanostructured WC and WC–Co samples with significantly better mechanical properties (hardness, fracture toughness) than those of conventional fine materials were obtained.
- Published
- 2015
78. Pioneering experiments on atomic-beam-assisted generation of drag currents in the Globus-M spherical tokamak
- Author
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P. B. Shchegolev, V. K. Gusev, M. I. Patrov, Yu. V. Petrov, N. V. Sakharov, V. B. Minaev, N. N. Bakharev, and G. S. Kurskiev
- Subjects
Materials science ,Tokamak ,Physics and Astronomy (miscellaneous) ,Deuterium ,Drag ,law ,Divertor ,Plasma ,Atomic physics ,Spherical tokamak ,Ion source ,Beam (structure) ,law.invention - Abstract
Research data for drag currents in the Globus-M spherical tokamak are presented. The currents are generated by injecting atomic beams of hydrogen and deuterium. Experiments were carried out in the hydrogen and deuterium plasma of the tokamak. It has a divertor configuration with a lower X-point, a displacement along the larger radius from–1.0 to–2.5 cm, and a toroidal field of 0.4 T at a plasma current of 0.17–0.23 MA. The beam is injected into the tokamak in the equatorial plane tangentially to the magnetic axis of the plasma filament with an impact diameter of 32 cm. To provide a 28-keV 0.5-MW atomic beam with geometrical sizes of 4 × 20 cm (at a power level of 1/e), an IPM-2 ion source is used. The generation of noninductive currents is detected from a rise in the loop current and a simultaneous dip of the loop voltage. The injection of the hydrogen and deuterium atomic beams into the deuterium plasma results in a noticeable and reproducible dip of the loop voltage (up to 0.5 V). Using the ASTRA transport code, a model is constructed that allows rapid calculation of noninductive currents. Calculations performed for a specific discharge confirm that the model adequately describes the effect of drag current generation.
- Published
- 2015
79. Preparation and investigation of ultrafine-grained tungsten carbide with high hardness and fracture toughness
- Author
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N. V. Isaeva, Yu. V. Blagoveshchenskii, Maksim Boldin, E. S. Smirnova, Yu. G. Lopatin, N. V. Sakharov, S. V. Shotin, A. V. Nokhrin, and V. N. Chuvil’deev
- Subjects
chemistry.chemical_compound ,Fracture toughness ,Materials science ,chemistry ,Mechanics of Materials ,Tungsten carbide ,Computational Mechanics ,General Physics and Astronomy ,Sintering ,Nanoparticle ,Composite material - Abstract
High-density samples of ultrafine-grained tungsten carbide with high hardness (up to 31–34 GPa) and increased fracture toughness (up to 5.2–6.4 MPa m1/2) are obtained using the technology of electropulse plasma sintering. The influence of the initial size of nanoparticles of α-WC prepared by plasmachemical synthesis on the density, structural parameters, and mechanical properties of tungsten carbide is investigated.
- Published
- 2015
80. Sparking plasma sintering of tungsten carbide nanopowders
- Author
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N. V. Sakharov, A. A. Popov, V. N. Chuvil’deev, Yu. G. Lopatin, Yu. V. Blagoveshchenskiy, A. V. Semenycheva, E. S. Smirnova, O. A. Belkin, Maksim Boldin, S. V. Shotin, A. V. Nokhrin, and N. V. Isaeva
- Subjects
Materials science ,Metallurgy ,General Engineering ,Nanoparticle ,Sintering ,Spark plasma sintering ,Abnormal grain growth ,Condensed Matter Physics ,Grain size ,chemistry.chemical_compound ,chemistry ,Tungsten carbide ,Volume fraction ,General Materials Science ,Grain boundary - Abstract
Spark Plasma Sintering studies of the high-speed consolidation of pure tungsten carbide WC nanopowders have been carried out. The influence of the initial size of the WC nanoparticles and modes of their receiption the density, structural parameters, and mechanical properties of tungsten carbide are studied. Samples of high-density nanostructured tungsten carbide with high hardness (up to 31–34 GPa) and an increased crack resistance (4.3–5.2 MPa m1/2) are obtained. It is found that the effect of accelerating tungsten carbide nanopowder sintering under conditions of high-speed heating is associated with the acceleration of diffusion along grain boundaries in the sintered material. It is shown that the nonmonotonic dependence of the optimal sintering temperature on the initial grain size is caused by a change in grain-boundary diffusion coefficient in conditions of abnormal grain growth. It is found that the size of abnormally large grains in spark plasma sintering depends on the volume fraction of particles of the nonstoichiometric phase.
- Published
- 2015
81. High-strength ultrafine-grained tungsten-carbide-based materials obtained by spark plasma sintering
- Author
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N. V. Isaeva, V. N. Chuvil’deev, N. V. Sakharov, Maksim Boldin, E. S. Smirnova, Yu. G. Lopatin, S. V. Shotin, Yu. V. Blagoveshchenskii, O. A. Belkin, and A. V. Nokhrin
- Subjects
chemistry.chemical_compound ,Cracking ,Materials science ,Physics and Astronomy (miscellaneous) ,chemistry ,Tungsten carbide ,Diffusion ,Metallurgy ,Spark plasma sintering ,Sintering ,Nanoparticle - Abstract
Ultrafine-grained (UFG) tungsten carbide (WC) samples with high hardness (up to 34 GPa) and increased cracking resistance have been obtained by the method of spark plasma sintering (SPS). Initial powders have been prepared by two-stage plasmachemical synthesis. The influence of the initial size of WC nanoparticles on the density, structural parameters, and mechanical properties of UFG tungsten carbide obtained by SPS has been studied. It is established that the phenomenon of accelerated sintering of WC powder is related to enhanced grain-boundary diffusion.
- Published
- 2015
82. Bicoherence analysis of geodesic acoustic modes in the Tuman-3M and Globus-M Tokamaks
- Author
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V. K. Gusev, A. Yu. Yashin, M. I. Patrov, V. V. Bulanin, A. V. Petrov, S. Yu. Tolstyakov, L. G. Askinazi, N. V. Sakharov, G. S. Kurskiev, A. S. Tukachinskii, V. A. Kornev, Yu. V. Petrov, A. A. Belokurov, S. V. Lebedev, and V. B. Minaev
- Subjects
Physics ,Tokamak ,Physics and Astronomy (miscellaneous) ,Geodesic ,Turbulence ,business.industry ,Plasma ,Spectral line ,law.invention ,Computational physics ,symbols.namesake ,Optics ,law ,Electric field ,symbols ,business ,Doppler effect ,Bicoherence - Abstract
We present the results of a comparative investigation of geodesic acoustic modes (GAMs) by the method of bicoherence analysis in tokamaks (Tuman-3M and Globus-M) with different aspect ratios. The obtained data provide indirect evidence of the mutual influence of GAMs and background turbulence of tokamak plasma. The cross-bicoherence spectra were calculated using the signals of Doppler reflectometers and temporal dependences of the velocity of plasma rotation in the electric field of GAMs. The level of bicoherence in both tokamaks increases before transition to the H-mode and then decays down to the noise level in the H-mode.
- Published
- 2015
83. Structure and properties of advanced materials obtained by Spark Plasma Sintering
- Author
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S. V. Shotin, A. V. Nokhrin, N. V. Sakharov, Maksim Boldin, V. N. Chuvil’deev, D.V. Panov, D. N. Kotkov, and Yu. V. Blagoveshchensky
- Subjects
Materials science ,Metallurgy ,Alloy ,Direct current ,Aerospace Engineering ,Sintering ,Spark plasma sintering ,Advanced materials ,engineering.material ,Mechanical pressure ,visual_art ,visual_art.visual_art_medium ,engineering ,Ceramic - Abstract
This paper provides an overview of Spark Plasma Sintering (SPS), which is an advanced technology for high-speed sintering of powder materials by applying mechanical pressure to the powder compact and heating it using a pulsed direct current. Some examples of the successful application of the SPS technology in producing materials with high strength characteristics are shown. By optimizing the SPS regimes, the hardness of pure WC ceramics Hv=30÷31 GPa (20% higher than that of conventional materials), hardness of pure Al2O3 ceramics Hv=23.5 GPa (50% higher than that of conventional materials) and limit strength of the heavy alloy W–Ni–Fe σT=2500 MPa (2 times higher than that of conventional materials) are achievable.
- Published
- 2015
84. The influence of toroidal Alfvén modes on the confinement of fast particles in the Globus-M spherical tokamak
- Author
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N. V. Sakharov, A. D. Melnik, P. B. Shchegolev, Yu. V. Petrov, V. A. Kornev, N. N. Bakharev, V. K. Gusev, V. B. Minaev, M. I. Patrov, S. Yu. Tolstyakov, G. S. Kurskiev, and F. V. Chernyshev
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Hydrogen ,chemistry.chemical_element ,Plasma ,Spherical tokamak ,Neutral beam injection ,Deuterium ,chemistry ,Physics::Plasma Physics ,Neutron flux ,Physics::Atomic Physics ,Atomic physics ,Neutral particle ,Beam (structure) - Abstract
Neutral beam injection into the Globus-M spherical tokamak at the early stage of discharge leads to the development of instabilities in a frequency range of 50–200 kHz, which have been identified as toroidal Alfven eigenmodes (TAEs) [1]. The influence of these modes on the confinement of fast particles has been studied with the aid of a neutral particle analyzer (NPA) and a neutron detector. The isotope effect was studied using hydrogen and deuterium both in the injected beam and in the target plasma. A correlation analysis of signals from magnetic probes showed that the observed modes in most cases contain a single harmonic with toroidal number n = 1. Upon the injection of deuterium into deuterium plasma, the development of TAEs led to a decrease in the neutron flux by 25%, whereas the fluxes of high-energy recharge atoms decreased by 75%. After the injection of hydrogen, a decrease in the flux measured by NPA did not exceed 25%.
- Published
- 2014
85. High-speed electropulse plasma sintering of nanostructured tungsten carbide: Part 1. Experiment
- Author
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N. V. Sakharov, V. N. Chuvil’deev, Yu. G. Lopatin, Maksim Boldin, Yu. V. Blagoveshchenskii, N. V. Isaeva, D. N. Kotkov, A. V. Pisklov, S. V. Shotin, A. V. Nokhrin, and A. V. Moskvicheva
- Subjects
Materials science ,Metallurgy ,Metals and Alloys ,Spark plasma sintering ,Sintering ,Nanoparticle ,Plasma ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Tungsten carbide ,Metallic materials ,Crack resistance - Abstract
The high-temperature consolidation of nanopowders of pure tungsten carbide by electropulse plasma sintering (spark plasma sintering) is investigated. The influence of the initial size of WC nanoparticles and their preparation modes on the density, structural parameters, and mechanical properties of tungsten carbide are investigated. Samples of high-density nanostructured tungsten carbide with high hardness (to 31 GPa) and crack resistance (5.2 MPa m1/2) are fabricated.
- Published
- 2014
86. PHENOMENA OF LIMIT-CYCLE OSCILLATIONS IN THE GLOBUS-M SPHERICAL TOKAMAK
- Author
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V V Bulanin, V K Gusev, G S Kurskiev, M I Patrov, A V Petrov, M A Petrov, Petrov, Yu V, N V Sakharov, S Yu Tolstyakov, and A Yu Yashin
- Published
- 2017
- Full Text
- View/download PDF
87. Globus-M2 spherical tokamak and its mission in developing of compact fusion neutron source
- Author
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N. A. Khromov, A. N. Saveliev, V. I. Varfolomeev, G. S. Kurskiev, V. K. Gusev, N. N. Bakharev, V. A. Rozhansky, P. B. Shchegolev, A.B. Mineev, V. V. Dyachenko, Yu. V. Petrov, I.V. Shikhovtsev, F. V. Chernyshev, N. V. Sakharov, and V. B. Minaev
- Subjects
Nuclear physics ,Physics ,Fusion neutron ,QC1-999 ,0103 physical sciences ,Astrophysics ,Spherical tokamak ,010306 general physics ,01 natural sciences ,010305 fluids & plasmas - Published
- 2017
88. FILAMENT INVESTIGATION VIA DOPPLER BACKSCATTERING DIAGNOSTIC IN THE GLOBUS-M TOKAMAK
- Author
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V V Bulanin, V K Gusev, N A Khromov, G S Kurskiev, V B Minaev, M I Patrov, A V Petrov, M A Petrov, Petrov, Yu V, D Prisiazhniuk, N V Sakharov, S Yu Tolstyakov, and A Yu Yashin
- Published
- 2017
- Full Text
- View/download PDF
89. Praseodymium and neodymium phosphates Ca9Ln(PO4)7 of whitlockite structure. Preparation of a ceramic with a high relative density
- Author
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V. N. Chuvil’deev, N. V. Sakharov, Maksim Boldin, A. V. Nokhrin, N. V. Malanina, and A. I. Orlova
- Subjects
Chemistry ,Praseodymium ,Analytical chemistry ,Mineralogy ,chemistry.chemical_element ,Sintering ,engineering.material ,Microstructure ,Neodymium ,visual_art ,visual_art.visual_art_medium ,Whitlockite ,engineering ,Relative density ,Ceramic ,Particle size ,Physical and Theoretical Chemistry - Abstract
Praseodymium and neodymium phosphates Ca9Ln(PO4)7 of the whitlockite structure were synthesized in the form of powders via solid-phase reactions at high temperatures and in the form of ceramics using the two-step pressing + sintering process and one-step high-rate spark plasma sputtering (SPS) procedure. According to X-ray diffraction data, the phosphates were structural analogs of calcium phosphate, namely, of its low-temperature modification β-Ca3(PO4)2, space group R3c. The particle size in the powders was 80–110 nm. The relative densities of the ceramics reached 99% when using SPS. The optimum conditions were found for obtaining high-density ceramics containing Pr and Nd. Their mechanical characteristics (microhardness, cracking resistance) were determined, and the microstructure was characterized.
- Published
- 2014
90. Sintering of nano- and ultradispersed mechanically activated W-Ni-Fe powders and the manufacture of ultrahigh-strength heavy tungsten alloys
- Author
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V. Yu. Belov, D. N. Kotkov, Maksim Boldin, Yu. G. Lopatin, A. V. Moskvicheva, V. N. Chuvil’deev, N. A. Kozlova, D. A. Konychev, Yu. V. Blagoveshchenskii, G. V. Baranov, N. V. Sakharov, A. V. Nokhrin, and N. V. Isaeva
- Subjects
Materials science ,Metallurgy ,Alloy ,Metals and Alloys ,Spark plasma sintering ,Sintering ,chemistry.chemical_element ,engineering.material ,Tungsten ,chemistry ,Nano ,engineering ,Particle size ,Ball mill ,Solid solution - Abstract
The structure and mechanical properties of nano- and ultradispersed mechanically activated heavy W-Ni-Fe and W-Ni-Fe-Co tungsten alloys (VNZh and VNZhK alloys, respectively) are studied. Mechanically activated nano- and ultradispersed charge powders are sintered by free sintering (thermally activated) and spark plasma sintering. The dependence of the density of the alloys made of the mechanically activated powders on the sintering temperature is found to have a nonmonotonic character with a maximum corresponding to the optimum sintering temperature. It is shown that an increase in the mechanical activation time and the acceleration of the milling bodies during mechanical activation lead to a decrease in the alloy particle size and the formation of nonequilibrium solid solutions and are accompanied by a decrease in the optimum sintering temperature of heavy tungsten alloys. Ultrahigh-strength tungsten alloys the mechanical properties of which are substantially higher than those of standard coarse-grained analogs are fabricated due to the optimization of the conditions of ball milling and high-rate spark plasma sintering of W-Ni-Fe powders.
- Published
- 2014
91. Phosphate Ca1/4Sr1/4Zr2(PO4)3 of the NaZr2(PO4)3 structure type: Synthesis of a dense ceramic material and its radiation testing
- Author
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D.M. Bykov, Maksim Boldin, A. V. Nokhrin, D. A. Mikhailov, A. I. Orlova, V. N. Chuvil’deev, Vladimir A. Skuratov, V. Yu. Volgutov, and N. V. Sakharov
- Subjects
Nuclear and High Energy Physics ,Materials science ,Annealing (metallurgy) ,Analytical chemistry ,Mineralogy ,Spark plasma sintering ,Fluence ,Isothermal process ,Amorphous solid ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,visual_art ,visual_art.visual_art_medium ,General Materials Science ,Irradiation ,Ceramic ,Ethylene glycol - Abstract
The powder of phosphate Ca1/4Sr1/4Zr2(PO4)3 was synthesized by sol–gel processes in the presence of citric acid and ethylene glycol. Ceramic samples were prepared from this powder by Spark Plasma Sintering (SPS), their relative densities were found to be 99.5 ± 0.3% after the isothermal treatment at 860 °С for 3 min. Sintered disc-shaped ceramic samples (d = 10 mm, h = 4 mm) were bombarded at 300 K by 167 MeV Xe26+ ions with fluences ranging from 6 ⋅ 1010 to 1 ⋅ 1013 ions/cm2. It was found that exposure to the highest fluence (1013 ion/cm2) led to a complete amorphization of the irradiated layer. The observed phase transition is ascribed to the formation of amorphous latent tracks via dense electronic excitations. Postradiation heat treatment revealed that the transformation from metamict to crystalline form took place after annealing at T = 200, 300, 400, 500, 600 and 800 °С and t = 3, 13, 11, 5, 17 and 15 h, respectively.
- Published
- 2014
92. Phosphorus-containing cesium compounds of pollucite structure. Preparation of high-density ceramic and its radiation tests
- Author
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A. V. Nokhrin, V. N. Chuvil’deev, Vladimir A. Skuratov, Maksim Boldin, A. N. Troshin, A. I. Orlova, N. V. Sakharov, D. A. Mikhailov, and N. S. Kirilkin
- Subjects
Analytical chemistry ,chemistry.chemical_element ,Spark plasma sintering ,Mineralogy ,Sintering ,engineering.material ,Ion ,chemistry ,Caesium ,visual_art ,Pollucite ,visual_art.visual_art_medium ,engineering ,Ceramic ,Irradiation ,Physical and Theoretical Chemistry ,Radiation resistance - Abstract
Multicomponent oxides of pollucite structure, containing Cs and Ba, were synthesized as powders and ceramics. Their chemical compositions, Cs[MgAl0.5P1.5O6] and Cs0.875Ba0.125[Li0.125Zn0.875Al0.5P1.5O6], were modeled on the basis of the known structural features, taking into account the principles of iso- and heterovalent isomorphism of cations. From powdered samples synthesized using sol-gel process, a ceramic was prepared by spark plasma sintering (SPS). The sintering time was 3–4 min in the temperature interval 600–850°C. The relative densities were 97 and 99%. To evaluate the radiation resistance of the ceramics, the samples were irradiated with 132Xe26+ ions (E = 167 MeV) in the fluence interval from 6 × 1010 to 1 × 1013 cm−2 (ion flux density ∼109 s−1 cm−2). The amorphization took place at fluences of (1.2–1.3) × 1012 cm−2. This fact suggests the decisive role of the ion energy loss for ionization in the generation of radiation defects. Conditions were found for the transition of the metamict form into the crystalline form on heating.
- Published
- 2014
93. Influence of the safety factor profile on the particle and heat transport in the Globus-M spherical tokamak
- Author
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N. N. Bakharev, V B Miinaev, N. V. Sakharov, I V Miroshnikov, V. A. Tokarev, A D Sladkomedova, E. A. Tukhmeneva, V. K. Gusev, S. Yu. Tolstyakov, P. B. Shchegolev, E. O. Kiselev, G. S. Kurskiev, M. I. Patrov, S. Yu. Medvedev, V.V. Solokha, A. Yu. Telnova, N. A. Khromov, and Yu. V. Petrov
- Subjects
Physics ,Safety factor ,Particle ,Mechanics ,Spherical tokamak ,Condensed Matter Physics - Published
- 2019
94. Development of Z eff diagnostic system on the Globus-M (M2) tokamak and the first experimental results
- Author
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G. S. Kurskiev, N. V. Sakharov, V. K. Gusev, E. A. Tukhmeneva, P. B. Shchegolev, A. Yu. Telnova, S. Yu. Tolstyakov, E. O. Kiselev, Yu. V. Petrov, V. B. Minaev, and N. N. Bakharev
- Subjects
Nuclear physics ,Physics ,Tokamak ,law ,Magnetic confinement fusion ,Condensed Matter Physics ,Diagnostic system ,law.invention - Published
- 2019
95. Studying the interaction of high-energy deuterons with plasma in the Globus-M spherical tokamak
- Author
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M. I. Patrov, N. A. Khromov, V. K. Gusev, F. V. Chernyshev, G. S. Kurskiev, V. B. Minaev, A. D. Iblyaminova, S. Yu. Tolstyakov, A. D. Melnik, P. B. Shchegolev, F. Wagner, Yu. V. Petrov, V. A. Kornev, N. V. Sakharov, and N. N. Bakharev
- Subjects
Physics ,Tokamak ,Physics and Astronomy (miscellaneous) ,Plasma parameters ,Magnetic confinement fusion ,Plasma ,Spherical tokamak ,Neutral beam injection ,law.invention ,Nuclear physics ,Deuterium ,Physics::Plasma Physics ,law ,Atomic physics ,Beam (structure) - Abstract
Plasma parameters in the Globus-M spherical tokamak have been measured upon injection of a deuteron beam with energy about 30 keV and a power of up to 700 kW. Dependences of the ion temperature and neutron yield on the plasma current and density and the gap width between the wall and plasma are considered. Possible characteristics of fast-ion confinement in the modified Globus-M2 tokamak are discussed.
- Published
- 2013
96. Synthesis and structure of alkali metal zirconium vanadate phosphates
- Author
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E. Yu. Borovikova, N. V. Sakharov, M. M. Ermilova, V. S. Kurazhkovskaya, N. V. Orekhova, Vladimir Pet'kov, M. V. Sukhanov, and A. S. Shipilov
- Subjects
Materials Science (miscellaneous) ,Inorganic chemistry ,Vanadium ,chemistry.chemical_element ,Crystal structure ,Alkali metal ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,chemistry ,Tungstate ,Vanadate ,Lithium ,Scandium ,Physical and Theoretical Chemistry ,Solid solution - Abstract
Mixed vanadate phosphates in the systems MZr2(VO4)x(PO4)3 − x, where M is an alkali metal, were synthesized and studied by X-ray diffraction, electron probe microanalysis, and IR spectroscopy. Substitutional solid solutions with the structure of the mineral kosnarite (NZP) are formed at the compositions 0 ≤ x ≤ 0.2 for M = Li; 0 ≤ x ≤ 0.4 for M = Na; 0 ≤ x ≤ 0.5 for M = K; 0 ≤ x ≤ 0.3 for M = Rb; and 0 ≤ x ≤ 0.2 for M = Cs. Apart from the high-temperature NZP modification, lithium vanadate phosphates LiZr2(VO4)x(PO4)3 − x with 0 ≤ x ≤ 0.8 synthesized at temperatures not exceeding 840°C crystallize in the scandium tungstate type structure. The crystal structures of LiZr2(VO4)0.8(PO4)2.2 (space group P21/n, a = 8.8447(6) A, b = 8.9876(7) A, c = 12.3976(7) A, β = 90.821(4)○, V = 985.4(1) A3, Z = 4) and NaZr2(VO4)0.4(PO4)2.6 (space group \(R\bar 3c\) = 8.8182(3) A, c = 22.7814(6) A, V = 1534.14(1) A3, Z = 6) were refined by the Rietvield method. The framework of the vanadate phosphate structure is composed of tetrahedra (that are statistically occupied by vanadium and phosphorus atoms) and ZrO6 octahedra. The alkali metal atoms occupy extra-framework sites.
- Published
- 2013
97. Efficient 2.1‐μm lasers based on Tm 3+: Lu 2 O 3 ceramics pumped by 800–nm laser diodes
- Author
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M. O. Marychev, A. A. Lagatskii, N G Zakharov, A. A. Novikov, Oleg L. Antipov, N. V. Sakharov, M. V. Kruglova, A.P. Zinoviev, O. N. Gorshkov, and H. Yagi
- Subjects
Pulse repetition frequency ,Materials science ,business.industry ,Graphene ,Slope efficiency ,Pulse duration ,Condensed Matter Physics ,Laser ,law.invention ,Mode-locking ,law ,visual_art ,visual_art.visual_art_medium ,Optoelectronics ,Ceramic ,business ,Diode - Abstract
Structural, optical and spectroscopic properties of Tm3+:Lu2O3 ceramics were studied. CW laser operation at 2068 nm with an output power of up to 34 W and a slope efficiency of 44% was obtained. Q-switched ocsilation with a pulse duration of 100-150 ns and a repetition rate of 1-10 kHz was achieved. Passive mode locking was achieved using an ion-implanted InGaAsSb quantum-well based SESAM or single graphene layer. Transform-limited pulses as short as 180 fs are generated at 2076 nm with an average output power of 400 mW and a pulse repetition frequency of 121.2 MHz. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
- Published
- 2013
98. Noninductive plasma generation and current drive in the Globus-M spherical tokamak
- Author
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A. E. Shevelev, A. A. Kavin, V. K. Gusev, M. M. Larionov, V. V. Rozhdestvenskii, N. A. Khromov, F. V. Chernyshev, V. V. Dyachenko, A. N. Novokhatskii, O. N. Shcherbinin, S. A. Khitrov, S.E. Bender, K.M. Lobanov, A. D. Melnik, N. V. Sakharov, Yu. V. Petrov, and A. Yu. Stepanov
- Subjects
Physics ,Tokamak ,Physics and Astronomy (miscellaneous) ,Field (physics) ,Plasma ,Spherical tokamak ,Condensed Matter Physics ,Lower hybrid oscillation ,Computational physics ,Magnetic field ,law.invention ,law ,Electric field ,Current (fluid) ,Atomic physics - Abstract
Experimental results on the generation and maintenance of the toroidal current in the Globus-M spherical tokamak by using waves in the lower hybrid frequency range without applying an inductive vortex electric field are presented. For this purpose, the original ridge guide antennas forming a field distribution similar to that produced by multiwaveguide grills were used. The high-frequency field (900 MHz) was used for both plasma generation and current drive. The magnitude of the generated current reached 21 kA, and its direction depended on the direction of the vertical magnetic field. Analysis of the experimental results indicates that the major fraction of the current is carried by the suprathermal electron beam.
- Published
- 2013
99. Study of the structure and mechanical properties of nano- and ultradispersed mechanically activated heavy tungsten alloys
- Author
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A. V. Moskvicheva, S. V. Shotin, Maksim Boldin, A. V. Nokhrin, D. N. Kotkov, N. V. Sakharov, N. V. Melekhin, G. V. Baranov, Yu. V. Blagoveshchenskii, V. Yu. Belov, and V. N. Chuvil’deev
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Materials science ,Alloy ,Metallurgy ,General Engineering ,Sintering ,chemistry.chemical_element ,Spark plasma sintering ,engineering.material ,Tungsten ,Condensed Matter Physics ,Stress (mechanics) ,chemistry ,Nano ,engineering ,Particle ,General Materials Science ,Composite material ,Solid solution - Abstract
Mechanisms of sintering and the structure and mechanical properties of nano- and ultradispersed W-Ni-Fe (WNF) and W-Ni-Fe-Co (WNFC) heavy tungsten alloys are investigated. The effect of tungsten particle sizes on the optimal sintering temperature is studied. The size of particles has been changed by the mechanical activation (MA) of the source W-Ni-Fe coarse-grained (CG) charge and by adding ultradispersed particles obtained using plasmochemical synthesis. Nanodispersed powders and ultradispersed powders (UDPs) have been sintered using the techniques of free sintering and pulse plasma sintering (PPS). It has been revealed that the dependence of the alloy density on heating temperature is nonmonotonic, with the maximum corresponding to the optimum sintering temperature. It has been shown that an increase in the time of MA and acceleration of grinding bodies in the process of MA accompanied by a decrease in the size of alloy particles and formation of nonequilibrium solid solutions lead to a reduction in the optimal sintering temperature. It has been shown that, using planetary high-energy milling methods and high-rate spark plasma sintering, it is possible to obtain ultrastrong tungsten alloys whose mechanical properties (macroelasticity stress and yield stress) substantially exceed analogous properties of commercial alloys.
- Published
- 2013
100. Conception of ion cyclotron plasma heating in the Globus-M2 spherical tokamak
- Author
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Yu. V. Petrov, N. V. Sakharov, V. K. Gusev, V. I. Varfolomeev, O. N. Shcherbinin, and V. V. Dyachenko
- Subjects
Physics ,Toroid ,Tokamak ,Physics and Astronomy (miscellaneous) ,Cyclotron ,Plasma ,Spherical tokamak ,law.invention ,Magnetic field ,Physics::Plasma Physics ,law ,Physics::Space Physics ,Atomic physics ,Antenna (radio) ,Electrical impedance ,Computer Science::Information Theory - Abstract
The impedance of the coupling between the antenna and the plasma of the Globus-M2 tokamak with an increase in the toroidal magnetic field and profiles of HF power absorption by plasma components are calculated. The concept of an antenna for the input of fast magnetosonic waves into plasma is discussed.
- Published
- 2012
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