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Femtosecond X-ray Lasers at λ=32.8 and 44.4 nm in a Plasma Formed by Optical Field Ionization in a Krypton Cluster Jet
Issue:
Volume 9, Issue 5, September 2021
Pages:
102-109
Received:
15 July 2021
Accepted:
4 August 2021
Published:
10 September 2021
Abstract: Due to high efficiency, X-ray lasers based on transitions of Ni-like krypton (Kr8+) are being actively studied. The main focus is on an X-ray laser based on the conventional 3d5/24d5/2 [J=0] – 3d3/24p1/2 [J=1] transition at λ=32.8 nm. Gaseous krypton targets or krypton cluster jets are used in various experiments. X-ray lasers at 32.8 nm in a plasma formed by optical field ionization in a krypton cluster jet are widely used for research of nanoobjects. In this article, the possibility of creating an efficient X-ray laser in Ni-like krypton based on a transition with optical self-pumping 3d3/24f5/2 [J=1] – 3d3/24d5/2 [J=1] at λ=44.4 nm is predicted for the first time. The plasma filament is excited upon interaction of a jet of krypton clusters with an intense pump laser pulse. Optimal conditions to achieve the duration tlas ≤300 fs of the X-ray laser radiation are determined. The optimal electron density is in a rather narrow interval in the range ne ~ 1021 - 2×1021 cm-3. The optimal electron temperature is several keV. It is likely that this explains the fact that no X-ray laser has been observed on this transition in Kr8+ so far. The conversion factor per pulse is found to be ~5×10-5. For an X-ray laser operating on the conventional transition 3d5/24d5/2 [J=0] – 3d3/24p1/2 [J=1] at λ=32.8 nm, tlas ≤ 300 fs can also be achieved; however, the conversion factor for this transition is times ~5 smaller than that for the former transition.
Abstract: Due to high efficiency, X-ray lasers based on transitions of Ni-like krypton (Kr8+) are being actively studied. The main focus is on an X-ray laser based on the conventional 3d5/24d5/2 [J=0] – 3d3/24p1/2 [J=1] transition at λ=32.8 nm. Gaseous krypton targets or krypton cluster jets are used in various experiments. X-ray lasers at 32.8 nm in a plasm...
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2D Surface Spin Waves in Dynamic Magnonic Crystals Created by a Surface Acoustic Wave in YIG Films
Issue:
Volume 9, Issue 5, September 2021
Pages:
110-115
Received:
16 August 2021
Accepted:
16 September 2021
Published:
27 September 2021
Abstract: Some results of the study of 2D propagation of surface magnetostatic spin waves (SMSW) in dynamic magnonic crystals (DMC) created by a surface acoustic wave (SAW) in a structure with a yttrium-iron garnet (YIG) film are presented. Such studies are interesting from the practical point of view of creating real relatively complex devices on spin waves when they propagate in different directions, and not only in the 1D case. The methods of experimental research are presented, in particular, the features of the method of excitation of SAW in the structure that do not lead to the appearance of additional magnetic anisotropy in it, a method for measuring the angular dependencies of SMSW using mobile antenna–probes is presented. The angular dependences of the magnonic band gap frequencies are measured. It is established that the transmission bands with the transformation of the reflected SMSW into other types of magnetostatic waves (MSW) exist at any angle values, while the intervals in which there are no SMSW transformations during reflections occur in a certain narrower range of angles. The angles of the directions of the wave vectors and the Poynting vector of the reflected SMSW were also measured. A satisfactory agreement was obtained with the calculation performed using the method of isofrequency curves and the laws of inelastic scattering SMSW on SAW.
Abstract: Some results of the study of 2D propagation of surface magnetostatic spin waves (SMSW) in dynamic magnonic crystals (DMC) created by a surface acoustic wave (SAW) in a structure with a yttrium-iron garnet (YIG) film are presented. Such studies are interesting from the practical point of view of creating real relatively complex devices on spin waves...
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Development of a Unified Numerical Kinetic Approach, Taking into Account Many-Particle Interactions in Liquid-Vapor Systems
Irina Shishkova,
Alexei Kryukov
Issue:
Volume 9, Issue 5, September 2021
Pages:
116-120
Received:
4 September 2021
Accepted:
24 September 2021
Published:
30 September 2021
Abstract: The study of evaporation and condensation should include consideration of heat and mass transfer processes inside the liquid, in the inter-phase transition domain, in the Knudsen layer, and in the outer area. Possible way to realize it is to use the conjugate approach, in which the description of these regions is carried out employing a single computational method. This method allows us to consider the condensed phase and gas as a single system and use the solution of kinetic equations throughout the region. Currently, processes in the gas phase have been studied quite well. The greatest obstacle to the use of kinetic equations in the condensed phase is the description of collisions involving multiple particles at the same time. In this paper a procedure is proposed to take the multi-particulate interactions within the condensed phase into account. Such approach is applied to the test study of the thermal conductivity problem for argon, neon, xenon, and krypton. Values of thermal conductivity coefficients for different quantities of interacting particles have been obtained. The comparison with corresponding experimental data is presented. Thus, the integral of paired collisions in the Boltzmann kinetic equation can be replaced by the proposed computational procedure. This approach provides a description of both liquid and gas at the level of the distribution function and ensures that the conditions at the interface are set correctly.
Abstract: The study of evaporation and condensation should include consideration of heat and mass transfer processes inside the liquid, in the inter-phase transition domain, in the Knudsen layer, and in the outer area. Possible way to realize it is to use the conjugate approach, in which the description of these regions is carried out employing a single comp...
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Influencing Factors on Measuring Surface Residual Stress of Steel Bars by X-ray Diffraction Method
Wu Yiwen,
Li Sijin,
Zhu Pei,
Wang Xiaoyu
Issue:
Volume 9, Issue 5, September 2021
Pages:
121-126
Received:
7 September 2021
Accepted:
4 October 2021
Published:
15 October 2021
Abstract: The surface residual stress of mechanical parts and large mechanical components has an important influence on their fatigue strength, stress corrosion resistance and service life. X-ray diffraction method is used to measure the surface residual stress of steel bars and the influence of factors such as testing methods, testing equipment status and sample status on testing results is discussed in this paper. The results show that the testing parameters such as the target material, filter, diffraction angle and the minimum step shall be selected according to the material type and crystal structure under the premise of stable operation of the equipment in testing process. After that, the data treatment is under consideration. The peak determination is a very important part of data processing. The cross-correlation method is widely used because it uses all the original test data for the calculation, and the accuracy of the peak determination is high in this test. It also shows that the sampling process and specimen protection can also affect the testing results of the residual stress. The structure state of materials will have a great impact on testing results. For example, the texture will cause excessive errors of the testing results. It is recommended to understand the material properties in detail before testing so as to ensure sufficient margin when sampling, to apply the strict protection for the test surface of the sample, and to add a swing angle appropriately when the material is with texture.
Abstract: The surface residual stress of mechanical parts and large mechanical components has an important influence on their fatigue strength, stress corrosion resistance and service life. X-ray diffraction method is used to measure the surface residual stress of steel bars and the influence of factors such as testing methods, testing equipment status and s...
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Workflow of Fracture Prediction Using Curvature-Related Attributes and a Case Study
Chang Deshuang,
Chen Zhigang,
Xu Jianguo,
Han Yuchun,
Sun Xing,
Guo Jianming
Issue:
Volume 9, Issue 5, September 2021
Pages:
127-132
Received:
26 July 2021
Accepted:
4 August 2021
Published:
28 October 2021
Abstract: Fracture is a kind of important reservoir in petroleum exploration, which usually exist in the carbonate rock or igneous rock. However, it is always difficult to predict the fracture with the seismic data. In this paper, based on curvature attributes, we develop a workflow for the prediction of fractured zone, fracture orientation, and open fractures. We begin with curvature calculation to predict fractured reservoirs and then calculate rose diagrams using curvature data. Fracture orientation is established by comparing the rose diagrams from imaging logs and the analogues from curvature data. We identify two principal orientations and calculate the azimuth intensity in these two directions using the curvature data. As per the crossplots of azimuth intensity in two directions and productivity, the azimuth with good correlation is the open azimuth of fractures. We apply this method to a Kazakhstan oilfield K and predict fractured-vuggy reservoirs in the eastern field and fractured reservoirs in the western field. In accordance with the prediction, there are two groups of fractures, one in a northeast direction and the other in a northwest direction. NE fractures are open in the northern field, and NW fractures are open in the southern field. We suggest two sites for well drilling, which obtain economic oil flow.
Abstract: Fracture is a kind of important reservoir in petroleum exploration, which usually exist in the carbonate rock or igneous rock. However, it is always difficult to predict the fracture with the seismic data. In this paper, based on curvature attributes, we develop a workflow for the prediction of fractured zone, fracture orientation, and open fractur...
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