Institute of Electrophysics UB RAS

Yekaterinburg, Russia

Institute of Electrophysics UB RAS

Yekaterinburg, Russia
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Ulmasculov M.R.,Institute of Electrophysics UB RAS | Sharypov K.A.,Institute of Electrophysics UB RAS | Shunailov S.A.,Institute of Electrophysics UB RAS | Shpak V.G.,Institute of Electrophysics UB RAS | And 3 more authors.
Journal of Physics: Conference Series | Year: 2017

Results of testing of a generator based on a solid-state drive and the parallel gyromagnetic nonlinear transmission lines with external bias are presented. Stable rf-modulated high-voltage nanosecond pulses were shaped in each of the four channels in 1 s packets with 1000 Hz repetition frequencies. Pulse amplitude reaches -175 kV, at a modulation depth of rf-oscillations to 50 % and the effective frequency ∼4 GHz.


Bagayev S.N.,RAS Institute of Laser Physics | Osipov V.V.,Institute of Electrophysics UB RAS | Vatnik S.M.,RAS Institute of Laser Physics | Shitov V.A.,Institute of Electrophysics UB RAS | And 4 more authors.
Optical Materials | Year: 2015

We fabricate Ho:YAG transparent ceramics based on nanopowders produced by laser ablation method via two approaches. Higher transmittance (82% in the infrared region) is achieved in ceramics prepared with an additional round of pre-calcining before sintering. We evaluate the average volume of the scattering centers in the ceramics and their distribution along the sample depth by the direct count method using an optical microscope and by the novel method of collinear two-photon interband photoexcitation, respectively. The laser characteristics of the 1% Ho:YAG ceramics are investigated using an intracavity pumping scheme. The slope efficiency is ∼40% relative to the absorbed pumping power at 1.85 μm. © 2015 Elsevier B.V.


Bagayev S.N.,RAS Institute of Laser Physics | Osipov V.V.,Institute of Electrophysics UB RAS | Shitov V.A.,Institute of Electrophysics UB RAS | Pestryakov E.V.,RAS Institute of Laser Physics | And 6 more authors.
Journal of the European Ceramic Society | Year: 2012

In this article, we report on the fabrication and optical properties of highly transparent yttria ceramics for lasers active media with broadband gain profile. Laser synthesis method was used to produce Y 2O 3-based nanopowders doped with 1mol.% Nd 3+ or Yb 3+ for these transparent ceramics. The additives of sesquioxides Lu 2O 3 and Sc 2O 3 were used along with ZrO 2 to disorder the crystalline structure. The porosity and average grain size decrease with these additives and the emission bandwidths of Nd 3+ ( 4F 3/2→ 4I 11/2) and Yb 3+ ( 2F 5/2→ 2F 7/2) transitions widen to 40 and 60nm, respectively. Laser operation with the slope efficiency of 29% was obtained in [(Yb 0.01Lu 0.24Y 0.75) 2O 3] 0.88(ZrO 2) 0.12 ceramic sample. © 2012 Elsevier Ltd.


Osipov V.V.,Institute of Electrophysics UB RAS | Shitov V.A.,Institute of Electrophysics UB RAS | Maksimov R.N.,Ural Federal University | Solomonov V.I.,Institute of Electrophysics UB RAS
Optical Materials | Year: 2015

Neodymium or ytterbium-doped transparent yttrium oxide ceramics with different tetravalent sintering additives (ZrO2, HfO2, or CeO2) were fabricated from nanopowders produced by laser ablation method. Phase composition and distribution of dopants in the synthesized nanopowders and ceramics were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX) spectroscopy. The tetravalent additives led to a decrease in grain size and an improvement in transmittance at the lasing wavelengths. However, an excess of tetravalent ions led to the formation of dispersed scattering volumes. We observed particles with modulated composition for nanopowder of Nd:Y2O3 doped by 10 mol% HfO2. The estimations based on Rayleigh light scattering showed that the maximum size of the dispersed scattering volume is below 20 nm. © 2015 Elsevier B.V.


Kijko V.S.,Ural Federal University | Maksimov R.N.,Ural Federal University | Shitov V.A.,Institute of Electrophysics UB RAS | Demakov S.L.,Ural Federal University | Yurovskikh A.S.,Ural Federal University
Journal of Alloys and Compounds | Year: 2015

Abstract Transparent Yb-doped Lu2O3 ceramic samples were fabricated via conventional vacuum and spark plasma sintering. Nanoparticles synthesized by laser ablation method were used as starting material. The morphology and phase evolution of the nanopowder were studied by transmission electron microscopy, simultaneous thermal analysis and X-ray diffraction. The obtained nanoparticles exhibited the monoclinic phase and were fully converted into the main cubic phase after calcination at 1100 °C for 1 h. Conventional vacuum sintering of Yb:Lu2O3 powder compact at 1780 °C for 20 h resulted in a fully-dense ceramics with an average grain size of 1.6 μm and optical transmittance of 79.3% at 1080 nm. Spark plasma sintering of the calcined Yb:Lu2O3 nanoparticles at 1450 °C and 15 kN for 40 min led to a 0.2 μm-grained ceramics exhibiting an optical transmittance of 75.6% at 1080 nm. © 2015 Elsevier B.V. All rights reserved.


Osipov V.V.,Institute of Electrophysics UB RAS | Orlov A.N.,Institute of Electrophysics UB RAS | Maksimov R.N.,Institute of Electrophysics UB RAS | Lisenkov V.V.,Ural Federal University | Platonov V.V.,Institute of Electrophysics UB RAS
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2013

Transparent yttria ceramics were fabricated by sintering a mixture of 1 at.% Nd:Y2O3 and HfO2 nanopowders produced by laser synthesis method. The best transmittance was 80.96% at the wavelength of λ=1080 nm in 6 mol.% HfO2 doped sample (1.5 mm thick). The additives of hafnium broaden both pumping and luminescence bands of Nd3+ ion in yttria ceramics. The luminescence intensity of 4F3/2→4I11/2 transition was little affected by hafnium concentration. The effective lifetime of 4F3/2 level in Nd:Y2O3 ceramics enhanced by 30% at 10 mol.% HfO2 doping concentration and the decay kinetics of laser transition attains Förster's behavior. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sharypov K.A.,Institute of Electrophysics UB RAS | Shpak V.G.,Institute of Electrophysics UB RAS | Shunailov S.A.,Institute of Electrophysics UB RAS | Ul'Masculov M.R.,Institute of Electrophysics UB RAS | Yalandin M.I.,Institute of Electrophysics UB RAS
Review of Scientific Instruments | Year: 2013

The construction and characterization of a measuring module for high voltage time-domain reflectometry with picosecond resolution is presented. The device provides registration of low-distortion reflections from the load at conditions of irregular shape and pronounced instability of an incident probing pulse with amplitude of hundreds of kilovolts and a width/front up to ∼2 ns. This is achieved with registration of differential reflecting signals by using two voltage probes, whose original signals are shifted in time and have a calibrated delay. Specially designed voltage dividers based on coaxial coupled lines with equalized dielectric constant of insulation meet the requirements of voltage probes identity. Reflectometry allows one to study dynamic changes of the loads for a specific time range of ∼10-10 s and faster. An example of reflectometry-based analysis for variations in breakdown development rate of atmospheric discharge gap supplied with the pulses of ∼100-kV amplitude and a front slope of ∼4 × 1014 V/s is presented. © 2013 AIP Publishing LLC.


Osipov V.V.,Institute of Electrophysics UB RAS | Shitov V.A.,Institute of Electrophysics UB RAS | Maksimov R.N.,Ural Federal University | Solomonov V.I.,Institute of Electrophysics UB RAS
Optical Materials | Year: 2015

Neodymium or ytterbium-doped transparent yttrium oxide ceramics with different tetravalent sintering additives (ZrO2, HfO2, or CeO2) were fabricated from nanopowders produced by laser ablation method. Phase composition and distribution of dopants in the synthesized nanopowders and ceramics were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX) spectroscopy. The tetravalent additives led to a decrease in grain size and an improvement in transmittance at the lasing wavelengths. However, an excess of tetravalent ions led to the formation of dispersed scattering volumes. We observed particles with modulated composition for nanopowder of Nd:Y2O3 doped by 10mol% HfO2. The estimations based on Rayleigh light scattering showed that the maximum size of the dispersed scattering volume is below 20nm. © 2015 Elsevier B.V.


Turmyshev I.S.,Institute of Electrophysics UB RAS | Murzakaev A.M.,Institute of Electrophysics UB RAS | Timoshenkova O.R.,Institute of Electrophysics UB RAS
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV | Year: 2012

Silicon nanowires were suggested as a material in production of field emission spot like cathodes. Field emission properties of high purity silicon nanowires produced by method of melt's electrolysis of the mixture KCl-KF-K 2SiF6-SiO2 were investigated. The diameters dispersion of nanowires under consideration were approximately from 10 nm to 100 nm. Nanowires originally produced as 'wisp' on carbon substrate firstly were separated from substrate then were reduced to fragments and further were strengthened to tungsten cathode in a shape of spike with curvature radius approximately 0.1-1 mcm by organic binder which was evaporated in a vacuum immediately before measurements. The volt- ampere characteristics the cathodes patterns were measured for voltages from 0,5 kV to 1,5 kV. The maximum achieved stable work current was 5 μA for a voltage 3.95 kV. The threshold current leading to dramatic destruction of the wires was estimated by 10 μA. As soon as this threshold had been reached spark discharge occurred and thin film of Si on tungsten tip formed in some experiments. In this case field emission became stable up to 25 μA and started with emission voltages of 300 V. The energy distributions of emitted electrons was obtained for silicon nanowires and nanoparticles of Si on tungsten tip. © 2012 IEEE.


Turmyshev I.S.,Institute of Electrophysics UB RAS | Murzakaev A.M.,Institute of Electrophysics UB RAS | Timoshenkova O.R.,Institute of Electrophysics UB RAS
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV | Year: 2012

Thermofield emission cathodes based on ZrO2/W heterostructures are widely used as a point electron source nowadays. At present issue results of simultaneous study of Volt-Ampere characteristics (VACH) and energy spectra of such cathodes are discussed just under field emission terms. Firstly, needle shaped tungsten cathodes were coated by thin (∼ 10 nm) film of ZrO 2 by means of thermo-field diffusion methods under ultra high vacuum conditions. In this case the tungsten emitters were used as reference patterns and their characteristics were measured before the coating process. It is shown that VACH of coated emitters plotted in Fowler-Nordheim coordinates has non-linear character contrarily to 'metallic' VACH. Such behavior of VACH may be attributed to complicated energy spectra obtained during VACH measurement and complex electronic structure of thin film. There are two peaks on the spectra plot with 3-5 eV distance between them depending on emission voltage. It is shown that energy spectra of coated cathodes may have fine structure. Finally, the work function of the coated cathodes is lower by 2 eV in comparison to pure W cathodes. © 2012 IEEE.

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