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G. S. Sarkisov - One of the best experts on this subject based on the ideXlab platform.
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Effect of hydration on the electrical explosion of a fine palladium wire in a vacuum
Physics of Plasmas, 2017Co-Authors: G. S. SarkisovAbstract:Experiments with fast electric explosion of a hydrated palladium wire in vacuum show a significant decrease in Joule Deposited Energy, expansion rate, and voltage amplitude at breakdown. An increase in the density of diffused hydrogen and oxygen at the wire surface leads to an early generation of plasma due to evaporation impurity and rapid development of avalanche breakdown along the wire surface. The non-hydrated Pd wire demonstrates a longer resistive time, higher voltage peak, greater Energy and expansion speed. The decrease in the Deposited Energy was ∼35%, and the expansion rate was ∼18%. The peak of light emission during voltage breakdown was twice higher for a hydrated Pd wire than for a bare one.
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Effect of Deposited Energy on the structure of an exploding tungsten wire core in a vacuum
Physics of Plasmas, 2005Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Dillon H. McdanielAbstract:The experiments demonstrate the full range of transformations of an exploding tungsten wire core from a solid state to total vaporization. These states are correlated with the value of Deposited Energy before voltage breakdown. If the Deposited Energy is less than the solid-state enthalpy, the wire remains solid. If the Deposited Energy is between the solid- and liquid-state enthalpy, the wire disintegrates into solid macroscopic-sized pieces. If the voltage breakdown happens during the liquid state, the wire expands. In this case, the expansion velocity of the wire (0.1–1km∕s) is almost a linear function of the Deposited Energy. The expanding wire core is homogeneous for a Deposited Energy more than 4eV∕atom and nonhomogeneous (100–200 μm scale “spots”) for Deposited Energy less than 4eV∕atom. For homogeneous expansion, the wire core consists mainly of hot liquid microdrops of submicron size [G. S. Sarkisov, P. V. Sasorov, K. W. Struve et al., J. Appl. Phys. 96, 1674 (2004)]. For Deposited Energy higher ...
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State of the metal core in nanosecond exploding wires and related phenomena
Journal of Applied Physics, 2004Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Pavel V. Sasorov, Dillon H. McdanielAbstract:Experiments show that an expanding metal wire core that results from a nanosecond electrical explosion in vacuum consists primarily of three different states: solid, microdrop, and gas-plasma. The state of the wire core depends both on the amount of Energy Deposited before the voltage breakdown and on the heating conditions. For small amounts of Deposited Energy (on the order of solid-stage enthalpy), the wire core remains in a solid state or is partially disintegrated. For a high level of Deposited Energy (more than vaporization Energy) the wire core is in a gas-plasma state. For an intermediate level of Deposited Energy (more than melting but less than vaporization), the wire disintegrates into hot liquid microdrops or clusters of submicron size. For a wire core in the cluster state, interferometry demonstrates weak (or even absent) phaseshift. Light emission shows a "firework effect"—the long late-time radiation related to the emission by the expanding cylinder of hot microparticles. For the wire core ...
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Polarity effect for exploding wires in a vacuum.
Physical Review E, 2002Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Dillon H. Mcdaniel, Pavel V. Sasorov, A. N. Gribov, G. M. OleinikAbstract:Experimental evidence for a strong influence of the radial electric field on Energy deposition into thin metal wires during their electrical explosion in vacuum is presented. Explosion of the metal wire with a positive polarity when the radial electric field "pushes" electrons into the wire results in twice as much Deposited Energy than with the negative polarity when the radial field "expels" electrons from the wires. Moreover, the axial structure of the Deposited Energy changes. This effect can be explained by the influence of radial electric field on electronic emission and on vapor breakdown along the wire surface.
Dillon H. Mcdaniel - One of the best experts on this subject based on the ideXlab platform.
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Effect of Deposited Energy on the structure of an exploding tungsten wire core in a vacuum
Physics of Plasmas, 2005Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Dillon H. McdanielAbstract:The experiments demonstrate the full range of transformations of an exploding tungsten wire core from a solid state to total vaporization. These states are correlated with the value of Deposited Energy before voltage breakdown. If the Deposited Energy is less than the solid-state enthalpy, the wire remains solid. If the Deposited Energy is between the solid- and liquid-state enthalpy, the wire disintegrates into solid macroscopic-sized pieces. If the voltage breakdown happens during the liquid state, the wire expands. In this case, the expansion velocity of the wire (0.1–1km∕s) is almost a linear function of the Deposited Energy. The expanding wire core is homogeneous for a Deposited Energy more than 4eV∕atom and nonhomogeneous (100–200 μm scale “spots”) for Deposited Energy less than 4eV∕atom. For homogeneous expansion, the wire core consists mainly of hot liquid microdrops of submicron size [G. S. Sarkisov, P. V. Sasorov, K. W. Struve et al., J. Appl. Phys. 96, 1674 (2004)]. For Deposited Energy higher ...
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State of the metal core in nanosecond exploding wires and related phenomena
Journal of Applied Physics, 2004Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Pavel V. Sasorov, Dillon H. McdanielAbstract:Experiments show that an expanding metal wire core that results from a nanosecond electrical explosion in vacuum consists primarily of three different states: solid, microdrop, and gas-plasma. The state of the wire core depends both on the amount of Energy Deposited before the voltage breakdown and on the heating conditions. For small amounts of Deposited Energy (on the order of solid-stage enthalpy), the wire core remains in a solid state or is partially disintegrated. For a high level of Deposited Energy (more than vaporization Energy) the wire core is in a gas-plasma state. For an intermediate level of Deposited Energy (more than melting but less than vaporization), the wire disintegrates into hot liquid microdrops or clusters of submicron size. For a wire core in the cluster state, interferometry demonstrates weak (or even absent) phaseshift. Light emission shows a "firework effect"—the long late-time radiation related to the emission by the expanding cylinder of hot microparticles. For the wire core ...
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Polarity effect for exploding wires in a vacuum.
Physical Review E, 2002Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Dillon H. Mcdaniel, Pavel V. Sasorov, A. N. Gribov, G. M. OleinikAbstract:Experimental evidence for a strong influence of the radial electric field on Energy deposition into thin metal wires during their electrical explosion in vacuum is presented. Explosion of the metal wire with a positive polarity when the radial electric field "pushes" electrons into the wire results in twice as much Deposited Energy than with the negative polarity when the radial field "expels" electrons from the wires. Moreover, the axial structure of the Deposited Energy changes. This effect can be explained by the influence of radial electric field on electronic emission and on vapor breakdown along the wire surface.
Andreas Schäfer - One of the best experts on this subject based on the ideXlab platform.
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Erratum: Transverse Energy density fluctuations in heavy-ion collisions in a Gaussian model [Phys. Rev. D 85, 114030 (2012)]
Physical Review D, 2017Co-Authors: Berndt Müller, Andreas SchäferAbstract:We calculate the transverse correlation of fluctuations of the Deposited Energy density in nuclear collisions in the framework of the Gaussian color glass condensate model.
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Transverse Energy Density Fluctuations in Heavy-Ion Collisions in a Gaussian Model
Physical Review D, 2012Co-Authors: Berndt Müller, Andreas SchäferAbstract:We calculate the transverse correlation of fluctuations of the Deposited Energy density in nuclear collisions in the framework of a Gaussian model similar to the color glass condensate model.
Kenneth W. Struve - One of the best experts on this subject based on the ideXlab platform.
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Effect of Deposited Energy on the structure of an exploding tungsten wire core in a vacuum
Physics of Plasmas, 2005Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Dillon H. McdanielAbstract:The experiments demonstrate the full range of transformations of an exploding tungsten wire core from a solid state to total vaporization. These states are correlated with the value of Deposited Energy before voltage breakdown. If the Deposited Energy is less than the solid-state enthalpy, the wire remains solid. If the Deposited Energy is between the solid- and liquid-state enthalpy, the wire disintegrates into solid macroscopic-sized pieces. If the voltage breakdown happens during the liquid state, the wire expands. In this case, the expansion velocity of the wire (0.1–1km∕s) is almost a linear function of the Deposited Energy. The expanding wire core is homogeneous for a Deposited Energy more than 4eV∕atom and nonhomogeneous (100–200 μm scale “spots”) for Deposited Energy less than 4eV∕atom. For homogeneous expansion, the wire core consists mainly of hot liquid microdrops of submicron size [G. S. Sarkisov, P. V. Sasorov, K. W. Struve et al., J. Appl. Phys. 96, 1674 (2004)]. For Deposited Energy higher ...
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State of the metal core in nanosecond exploding wires and related phenomena
Journal of Applied Physics, 2004Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Pavel V. Sasorov, Dillon H. McdanielAbstract:Experiments show that an expanding metal wire core that results from a nanosecond electrical explosion in vacuum consists primarily of three different states: solid, microdrop, and gas-plasma. The state of the wire core depends both on the amount of Energy Deposited before the voltage breakdown and on the heating conditions. For small amounts of Deposited Energy (on the order of solid-stage enthalpy), the wire core remains in a solid state or is partially disintegrated. For a high level of Deposited Energy (more than vaporization Energy) the wire core is in a gas-plasma state. For an intermediate level of Deposited Energy (more than melting but less than vaporization), the wire disintegrates into hot liquid microdrops or clusters of submicron size. For a wire core in the cluster state, interferometry demonstrates weak (or even absent) phaseshift. Light emission shows a "firework effect"—the long late-time radiation related to the emission by the expanding cylinder of hot microparticles. For the wire core ...
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Polarity effect for exploding wires in a vacuum.
Physical Review E, 2002Co-Authors: G. S. Sarkisov, Kenneth W. Struve, Dillon H. Mcdaniel, Pavel V. Sasorov, A. N. Gribov, G. M. OleinikAbstract:Experimental evidence for a strong influence of the radial electric field on Energy deposition into thin metal wires during their electrical explosion in vacuum is presented. Explosion of the metal wire with a positive polarity when the radial electric field "pushes" electrons into the wire results in twice as much Deposited Energy than with the negative polarity when the radial field "expels" electrons from the wires. Moreover, the axial structure of the Deposited Energy changes. This effect can be explained by the influence of radial electric field on electronic emission and on vapor breakdown along the wire surface.
Chang Shuo Chang - One of the best experts on this subject based on the ideXlab platform.
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surface quality microstructure and mechanical properties of the skd 61 tool steel with prior heat treatment affected by single and double pass continuous wave laser polishing
The International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Chang Shuo Chang, Kai Shiang Yang, C K ChungAbstract:This study is made to investigate the effects of applying double-pass continuous wave laser polishing on the parameters of areal average surface roughness, two mechanical properties, and microstructure of SKD 61 tool steel. These parameters are partly compared to those in the single-pass specimens. The specimens before conducting double-pass laser polishing are prepared using the conditions of the specimen with the smallest surface roughness in the single-pass specimens, with the aim of examining the possibility of further reducing surface roughness. The smallest surface roughness value of the double-pass specimens has a value slightly larger than that of the single-pass specimens. An appropriate shallow melting for a substantial reduction in the grinding marks of the as-received specimen is used to prepare the single-pass and double-pass specimens with the smallest surface roughness. The surface roughness value is controlled by the contents and intensities of α-ferrite and γ-austenite in the sample, thus the composite grain size. In the single-pass specimens, the austenite lattices appear when the Deposited Energy is higher than the critical value, laying between 60.75 and 66.81 J/mm2. In the double-pass specimens, the austenite lattices disappear when Deposited Energy is higher than the critical value between 81.00 and 91.13 J/mm2. The growth of γ-austenite can increase the composite grain size. These two kinds of polishing show the same characteristic, which is that the growth of γ-austenite can increase the composite grain size. The intensity of the γ-austenite and the composite grain size are two of the governing factors with regard to the surface roughness of the specimen. Either a decrease in Deposited Energy in the double-pass specimens or an increase in Deposited Energy in the single-pass specimen is favorable for an increase in surface roughness in the non-zero intensity region of austenite.
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surface quality microstructure mechanical properties and tribological results of the skd 61 tool steel with prior heat treatment affected by the Deposited Energy of continuous wave laser micro polishing
Journal of Materials Processing Technology, 2016Co-Authors: Chang Shuo Chang, C K ChungAbstract:Abstract SKD 61 tool steel specimens hardened by heat treatment are subjected to continuous wave laser micro-polishing (CWLμP). A total of 46 specimens are classified into three groups in order to find the operating conditions to minimize the areal average surface roughness (Sa) via a three-stage process. Deposited Energy per area (DE, unit: J/mm 2 ) is defined as a composite parameter of laser power (P), laser beam scanning velocity (V), and focused spot diameter (SS). The parameters of Sa and the sum of the thickness sum of the melt zone (MZ) and heat-affected zone (HAZ), as well as the mechanical properties of hardness (H) and reduced modulus (E r ), are then expressed as a function of DE. Appropriate choices of laser operating conditions allow the Sa corresponding to the DE value at about 70 J/mm 2 to be the smallest for these specimens. Due to the complex behavior involved in the thermocapillary flow, the only controlling parameter that Sa increases monotonically with is the hatch distance. Decreases in focal offset (FO) and laser power (P) cause a decrease in the highest amplitude of the polished surface in the spatial frequency analyses. The highest amplitude cannot decrease if the scanning velocity is excessively high or low. The core roughness depth (S k ) and the reduced peak height (S pk ) and valley depth (S vk ) are found to be linearly proportional to Sa. The H and E r values of the specimens are lowered by increasing the applied Deposited Energy, although DE is not the sole governing parameter. The mean values of H and Er in the MZ, HAZ, and base material are found to increase by increasing the depth beneath the top surface of a specimen. The smaller wear rate in the specimens of CWLμP compared to that of the as-received specimen can be attributed to the lubrication effect arising in the tribo-contacts of specimens with a grain size greater than the critical value. The differences in several properties between the as-received specimens with and without heat treatment are compared and discussed.