The effect of gamma radiation on structure of struvite-К

The effect of gamma radiation upon functional characteristics of nanostructural struvite-K is analyzed. Spectra of absorption struvite-K have been measured in infra-red area. Results of a microstructure of samples after of a gamma irradiation to a dose 1.35·10⁵Gy are described. It has shown that after gamma irradiation the phase composition of the sample essentially does not change, and there is a crystallization of amorphous phosphate and the structural or-dering of struvite-K and magnesite occurs.Аналізується вплив гамма-випромінювання на функціональні характеристики наноструктурного струвіту-K. Були виміряні спектри поглинання струвиту-K в інфрачервоній області. Описано результати мікроструктури зразків після гамма-опромінення до дози 1.35·10⁵Град. Було показано, що після гамма-опромінення фазовий склад зразка істотно не змінюється, а відбувається кристалізація аморфного фосфату і структурне впорядкування струвіту-К і магнезиту.Анализируется влияние гамма-излучения на функциональные характеристики наноструктурного струвита-K. Были измерены спектры поглощения струвита-K в инфракрасной области. Описаны результаты микроструктуры образцов после гамма облучения до дозы 1.35·10⁵Град. Было показано, что после гамма-облучения фазовый состав образца существенно не меняется, а происходит кристаллизация аморфного фосфата и структурное упорядочение струвита-К и магнезита

Cesium, strontium and sodium diffusion in magnesium kalium phosphates system

Nuclear-physical methods have been used for determination of diffusion coefficient of Cs, Na, Sr and Ga in samples on the basis of Ceramicrete which contained simulators of a liquid radioactive waste of "Hanford-1", KW and KE Basin sludge, 10% wollastonite and 0.3% of boric acid. After an irradiation of investigated samples by electrons and brake radiation to a dose 100 and 1 MGy, accordingly, leaching was conducted at temperature 37°C. Values of diffusion coefficient of Cs, Sr, Na changed in process of leaching from units of 10⁻¹⁰ cm²/s till 10⁻¹⁶ ... 10⁻¹⁷ cm²/s, for Ga - from units of 10⁻¹³ cm²/s to 10⁻¹⁶ cm²/s. Decreasing of weight of ceramics in process of leaching during 858 hours irradiated by electrons to a dose 100 MGy, on 14.6 and 18.5% with simulators KE and KW is revealed, accordingly. Decreasing of weight of ceramics in process of leaching during 858 hours, irradiated brake radiation to a dose 1 MGy, on 19.9 and 21.6% with simulators KW and KE, accordingly is revealed. The sums of relations of diffusion coefficient of Na concerning Cs and Sr are in antagonistic dependence on the Cs and Sr content in a matrix on the basis of Ceramicrete.Ядерно-физические методы были использованы для определения коэффициентов диффузии Cs, Na, Sr и Ga в образцах на основе керамики Ceramicrete, которые содержали имитаторы жидких радиоактивных отходов "Хенфорд-1", KW и KE Basin sludge, 10% волластонита и 0.3% борной кислоты. После облучения исследуемых образцов электронами и тормозным излучением до дозы 100 и 1 МГр, соответственно, было проведено выщелачивание при температуре 37°C. Значения коэффициентов диффузии цезия, стронция, натрия изменялись в процессе выщелачивания от единиц 10⁻¹⁰ см²/с до 10⁻¹⁶ ... 10⁻¹⁷ см²/с, для галлия от единиц 10⁻¹³ см²/с до 10⁻¹⁶ см²/с. Обнаружено уменьшение веса керамики в процессе выщелачивания в течение 858 часов, облученных электронами до дозы 100 МГp, на 14,6 и 18,5% с имитаторами KE и KW, соответственно. Обнаружено уменьшение веса керамики в процессе выщелачивания в течение 858 часа, облученной гамма-квантами до дозы 1 МГp, на 19,9 и 21,6% с имитаторами KW и KE, соответственно. Обнаружено, что суммы отношений коэффициента диффузии натрия относительно цезия и стронция находятся в антагонистической зависимости от содержания цезия и стронция в матрице на основе Ceramicrete.Ядерно-фiзичнi методи були використанi для визначення коефiцiєнтiв дифузiї Cs, Na, Sr i Ga в зразках на основi керамiки Ceramicrete, якi мiстили iмiтатори рiдких радiоактивних вiдходiв "Хенфорд-1", KW i KE Basin sludge, 10 % волластонiтy i 0.3% борної кислоти. Пiсля опромiнення дослiджуваних зразкiв електронами i гальмiвним випромiнюванням до дози 100 i 1 МГр, вiдповiдно, було проведено вилуговування при температурi 37°C. Значення коефiцiєнтiв дифузiї цезiю, стронцiю, натрiю змiнювалися в процесi вилуговування вiд одиниць 10⁻¹⁰ см²/с до 10⁻¹⁶ ... 10⁻¹⁷ см²/с, для галiю вiд одиниць 10⁻¹³ см²/с до 10⁻¹⁶ см²/с. Виявлено зменшення ваги керамiки в процесi вилуговування протягом 858 годин, опромiнених електронами до дози 100 МГp, на 14,6 i 18,5% з iмiтаторами KE i KW, вiдповiдно. Виявлено зменшення ваги керамiки в процесi вилуговування протягом 858 години, опромiненої гама-квантами до дози 1 МГp, на 19,9 i 21,6% з iмiтаторами KW i KE, вiдповiдно. Виявлено, що суми вiдносин коефiцiєнта дифузiї натрiю до цезiю та стронцiю знаходяться в антагонiстичної залежностi вiд вмiсту цезiю та стронцiю в матрицi на основi Ceramicrete

Markov Properties of Electrical Discharge Current Fluctuations in Plasma

Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma. Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate the Kramers-Moyal's coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation. In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties compared with the observed in the experiment. We also provide an exact decomposition of temporal correlation function by using Kramers-Moyal's coefficients. We show that for the stationary time series, the two point temporal correlation function has an exponential decaying behavior with a characteristic correlation time scale. Our results confirm that, there is no definite relation between correlation and Markov time scales. However both of them behave as monotonic increasing function of discharge current intensity. Finally to complete our analysis, the multifractal behavior of reconstructed time series using its Keramers-Moyal's coefficients and original data set are investigated. Extended self similarity analysis demonstrates that fluctuations in our experimental setup deviates from Kolmogorov (K41) theory for fully developed turbulence regime.Comment: 25 pages, 9 figures and 4 tables. V3: Added comments, references, figures and major correction

The First Distant X-ray Quasars (z ~ 4) among the Sources Discovered by the eROSITA Telescope of the SRG Orbital Observatory during a Deep Lockman Hole Survey

© 2020, Pleiades Publishing, Inc. Abstract: During a deep extragalactic Lockman Hole sky survey with an area of 18.5 sq. deg, which was conducted when the SRG observatory was flying to the Lagrange point L2, the eROSITA telescope detected ~7000 X-ray sources. These objects were then provisionally identified and classified using the publicly accessible data of optical and infrared sky surveys by the SRGz machine learning system developed for this purpose at the Space Research Institute of the Russian Academy of Sciences. As a result, a number of new candidates for distant quasars (z ~ 4) have been selected. The spectroscopic observations of the first two candidates from this list carried out with the 1.6-m AZT-33IK telescope of the Sayan Solar Observatory have confirmed that these objects are actually distant quasars at redshifts 3.878 and 4.116 and are characterized by a high X-ray luminosity ~1045 erg s-1 (2–10 keV). The results obtained allow one to count on the detection of a large number of distant quasars during a four-year all-sky survey of the SRG observatory begun in December 2019

Optical Identification of Candidates for Active Galactic Nuclei Detected by the Mikhail Pavlinsky ART-XC Telescope Onboard the SRG Observatory during an All-Sky X-ray Survey

Abstract: We present the results of our identification of eight objects from the preliminary catalogue of X-ray sources detected in the 4–12 keV energy band by the Mikhail Pavlinsky ART-XC telescope onboard the SRG observatory during the first all-sky survey. Three of them (SRGA J005751.0+210846, SRGA J014157.0-032915, SRGA J232446.8+440756) have been discovered by the ART-XC telescope, while five have already been known previously as X-ray sources, but their nature has remained unestablished. The last five sources have also been detected in soft X-rays by the eROSITA telescope of the SRG observatory. Our optical observations have been carried out at the 1.6-m AZT-33IK telescope of the Sayan Observatory and the 1.5-m Russian–Turkish telescope (RTT-150). All of the investigated objects have turned out to be active galactic nuclei (AGNs) at redshifts from 0.019 to 0.283. Six of them are Seyfert 2 galaxies (including one Seyfert 1.9 galaxy), one (SRGA J005751.0+210846) is a ‘‘hidden’’ AGN (in an edge-on galaxy), and one (SRGA J224125.9+760343) is a narrow-line Seyfert 1 galaxy. The latter object is characterized by a high X-ray luminosity (~(2-13) × 1044 erg s-1 in the 4–12 keV band) and, according to our black hole mass estimate (~2 × 107Mꙩ), an accretion rate close to the Eddington limit. All three AGNs discovered by the ART-XC telescope (which are not detected by the eROSITA telescope) are characterized by a high absorption column density (Formula presented.). The results obtained confirm the expectations that the ART-XC telescope is an efficient instrument in searching for heavily obscured and other interesting AGNs in the nearby (Formula presented.) Universe. The SRG sky survey will last for another 3 years or more, which must allow many such objects to be discovered

Advances in modelling of plasma pedestal behaviour and ELM control in ITER reference plasma scenarios,

Progress in the modelling of the edge pedestal plasma behaviour in ITER plasmas including linear and non-linear MHD stability analysis, ELM triggering by pellet injection and vertical plasma oscillations and ELM control by the application of 3-D fields is described. These activities are implemented under the framework of ITER Scientist Fellow Network Pedestal Group to improve the understanding of the physics processes that dominate ITER pedestal plasmas thus providing a firmer physics base to evaluate the edge plasma properties in ITER H-mode plasmas and for the physics-based extrapolation of results obtained in present experiments to ITER

Ideal MHD stability computations of plasma in the Galatea trap 'Trimix'

Abstract: MHD plasma stability of plasmas in Galatea traps was calculated using the equilibrium and stability codes for axisymmetric configurations on unstructured computational grids. For equilibrium configurations in the Trimix magnetic trap the dependence of the growth rates of ideal MHD modes with different toroidal wave numbers on the pressure magnitude was investigated.Note: Research direction:Mathematical modelling in actual problems of science and technic

Optical Spectroscopy of SRG/eROSITA Objects with 2.5-m Telescope at the Caucasus Mountain Observatory of the SAI MSU

© 2020, Pleiades Publishing, Inc. Based on observations with the new transient double-beam spectrograph (TDS) at the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU, we have determined the types and found the redshifts for six new X-ray sources (four quasars and two galaxy clusters) detected by the SRG space observatory during the Lockman Hole observations at the eROSITA performance verification phase. We show that the TDS allows the spectra of objects ~20m to be taken in 2 h of observations with a signal-tonoise ratio higher than 5 and a resolution R ~1500. The types and redshifts of the objects determined from our spectroscopic observations agree well with the predictions based on photometric data using the SRGz automatic classification system