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Masahiko Arakawa - One of the best experts on this subject based on the ideXlab platform.
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Laboratory impact experiments and numerical simulations on Shock Pressure attenuation in water ice
Journal of Geophysical Research, 2008Co-Authors: Kei Shirai, M. Kato, Noriko K. Mitani, Masahiko ArakawaAbstract:[1] High-velocity impact experiments of water ice were conducted to measure the Shock Pressure profile at various distances from the impact point. A numerical simulation of Shock wave propagation in water ice was also conducted for comparison with the experimental results. The numerical model was improved to fit the measured profiles, and it was found that a tensile strength of Yc = 1 MPa was necessary to reproduce the Shock Pressure profiles above the Hugoniot Elastic Limit. This improved numerical model was then used to study the Shock Pressure attenuation in water ice at various impact conditions and to refine the crater scaling law. The late-stage effective energy (LE) is the product of initial Shock Pressure (P0) and the third power of the projectile size (Lp3). The impact conditions with the same late-stage effective energy can produce the same Shock Pressure distribution far from the impact point (so-called late-stage equivalence). These impact conditions were investigated by numerical calculations with different projectiles and impact velocities. As a result of our calculation for water ice impacts, we found that a power law index of 2.2 instead of 3, as adopted by previous studies, is suitable for reproducing the late-stage equivalence in water ice (i.e., LE is proportional to P0 · Lp2.2). By using this improved LE, we can reconcile the inconsistency between the crater size and the LE indicated by previous studies. By using this improved LE, the crater volume Vcr formed on water ice is expressed by the following equation, Vcr = 1.0 exp (ln/2450), with Vcr in cm3, wherein ln (in Pa m2.2) is a constant derived from a fit to the data.
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Shock Pressure attenuation in water ice at a Pressure below 1 GPa
Journal of Geophysical Research: Planets, 2001Co-Authors: M. Kato, Kei Shirai, Michiya Higa, Yuichi Iijima, Tatsuya Kiyono, Satoru Nakazawa, Masahiko ArakawaAbstract:Shock Pressure attenuation in water ice was studied at an impact Pressure below 1 GPa and a temperature of 255 K. The observed Shock wave showed a multiple Shock wave structure: A precursor wave was followed by a main wave, which had a longer rise time and higher amplitude. The Hugoniot elastic limit (HEL) of water ice was measured to be in the range from 0.1 to 0.3 GPa when associated with precursor waves traveling at 3.86 km/s. The peak amplitude of the main wave Pm was observed to decrease with its propagation x from 3 to 60 mm (from 0.4 to 8 times as large as a projectile radius) in two series of experiments in which initial Shock Pressures Pi at the impact point were 0.60 and 0.87 GPa. The Pm was described as the power law relation Pm/Pi = (x/2.6 mm)−89. The precursor wave disappears as the Pm attenuated to a Pressure
P S Decarli - One of the best experts on this subject based on the ideXlab platform.
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the mineralogy of Shock induced melt vein in martian meteorite zagami Shock Pressure and ejection mechanism
Bulletin of Mineralogy Petrology and Geochemistry, 2008Co-Authors: T G Sharp, P S DecarliAbstract:The observations by transmission electron microscopy showed that the 125 μm wide Shock-induced melt vein in Martian meteorite Zagami consisting of abundant long-shaped stishovite needles plus minor troilite droplets and pyroxenes in the background of silicate glass.This is the first report of Post-stishovite was found in zagami meteorite in the maskelynite outside of Shock-induced melt vein.The mineralogy assemblages of melt vein,including stishovite,pyroxene and other high-Pressure phases reported by others,indicated the melt-vein crystallization Pressure and Shock Pressure were smaller than 25 GPa.The occurrence of post-stishovite indicated post-stishovite is a production of a solid-state transformation.The Martian meteorite apparently were ejected from Mars during hypervelocity impact event,accelerated to great than the Martian escape velocity(5 km/s)to escape from Martian gravity,and captured by Earth later.The 5 km/s velocity requires a Shock Pressure of at least 65 GPa in high-Pressure ejection mechanism which is inconsistent with Martian meteorite have been subjected to the Pressure of less than 25 GPa in general.Although a popular spall mechanism claimed a low-Pressure high-velocity ejection,due to the limitation of its simulation calculation code,it is actually still a high-Pressure ejection mechanism.The entrainment mechanism,hypervelocity vapor formed in the hypervelocity impact event escapes through cracks and entrains lightly Shocked surface rocks to escape from Mars,can explain the Pressure range of Martian meteorite very well.However,more detail studies are much needed.
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high Pressure phases in a Shock induced melt vein of the tenham l6 chondrite constraints on Shock Pressure and duration
Geochimica et Cosmochimica Acta, 2006Co-Authors: T G Sharp, P S DecarliAbstract:Abstract The microtexture and mineralogy of a 580-μm-wide melt vein in the Tenham L6 chondrite were investigated using field-emission scanning electron microscopy and transmission electron microscopy to better understand the Shock conditions. The melt vein consists of a matrix of silicate plus metal-sulfide grains that crystallized from immiscible melts, and sub-rounded fragments of the host chondrite that have been entrained in the melt and transformed to polycrystalline high-Pressure silicates. The melt-vein matrix contains two distinct textures and mineral assemblages corresponding to the vein edge and interior. The 30-μm-wide vein edge consists of vitrified silicate perovskite + ringwoodite + akimotoite + majorite with minor metal-sulfide. The 520-μm-wide vein interior consists of majorite + magnesiowustite with irregular metal-sulfide blebs. Although these mineral assemblages are distinctly different, the Pressure stabilities of both assemblages are consistent with crystallization from similar Pressure conditions: the melt-vein edge crystallized at about 23–25 GPa and the vein interior crystallized at about 21–25 GPa. This relatively narrow Pressure range suggests that the melt vein either crystallized at a constant equilibrium Shock Pressure of ∼25 GPa or during a relatively slow Pressure release. Using a finite element heat transfer program to model the thermal history of this melt vein during Shock, we estimate that the time required to quench this 580-μm-wide vein was ∼40 ms. Because the entire vein contains high-Pressure minerals that crystallized from the melt, the Shock-Pressure duration was at least 40 ms. Using a synthetic Hugoniot for Tenham and assuming that the sample experienced a peak-Shock Pressure of 25 GPa near the impact site, we estimate that the Tenham parent body experienced an impact with collision velocity ∼2 km/s. Based on a one-dimensional planar impact model, we estimate that the projectile size was >150 m in thickness.
Paul S. De Carli - One of the best experts on this subject based on the ideXlab platform.
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Estimating Shock Pressures based on high-Pressure minerals in Shock-induced melt veins of L chondrites
Meteoritics & Planetary Science, 2006Co-Authors: Z. Xie, Thomas G. Sharp, Paul S. De CarliAbstract:Here we report the transmission electron microscopy (TEM) observations of the mineral assemblages and textures in Shock-induced melt veins from seven L chondrites of Shock stages ranging from S3 to S6. The mineral assemblages combined with phase equilibrium data are used to constrain the crystallization Pressures, which can be used to constrain Shock Pressure in some cases. Thick melt veins in the TenhamL6 chondrite contain majorite and magnesiowstite in the center, and ringwoodite, akimotoite, vitrified silicate-perovskite, and majorite in the edge of the vein, indicating crystallization Pressure of ~25 GPa. However, very thin melt veins (5-30 μm wide) in Tenham contain glass, olivine, clinopyroxene, and ringwoodite, suggesting crystallization during transient low-Pressure excursions as the Shock Pressure equilibrated to a continuum level. Melt veins of Umbarger include ringwoodite, akimotoite, and clinopyroxene in the vein matrix, and Fe2SiO4-spinel and stishovite in SiO2-FeO-rich melt, indicating a crystallization Pressure of ~18 GPa. The silicate melt veins in Roy contain majorite plus ringwoodite, indicating Pressure of ~20 GPa. Melt veins of Ramsdorf and Nakhon Pathon contain olivine and clinoenstatite, indicating Pressure of less than 15 GPa. Melt veins of Kunashak and La Lande include albite and olivine, indicating crystallization at less than 2.5 GPa. Based upon the assemblages observed, crystallization of Shock veins can occur before, during, or after Pressure release. When the assemblage consists of high-Pressure minerals and that assemblage is constant across a larger melt vein or pocket, the crystallization Pressure represents the equilibrium Shock Pressure.
Kei Shirai - One of the best experts on this subject based on the ideXlab platform.
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Laboratory impact experiments and numerical simulations on Shock Pressure attenuation in water ice
Journal of Geophysical Research, 2008Co-Authors: Kei Shirai, M. Kato, Noriko K. Mitani, Masahiko ArakawaAbstract:[1] High-velocity impact experiments of water ice were conducted to measure the Shock Pressure profile at various distances from the impact point. A numerical simulation of Shock wave propagation in water ice was also conducted for comparison with the experimental results. The numerical model was improved to fit the measured profiles, and it was found that a tensile strength of Yc = 1 MPa was necessary to reproduce the Shock Pressure profiles above the Hugoniot Elastic Limit. This improved numerical model was then used to study the Shock Pressure attenuation in water ice at various impact conditions and to refine the crater scaling law. The late-stage effective energy (LE) is the product of initial Shock Pressure (P0) and the third power of the projectile size (Lp3). The impact conditions with the same late-stage effective energy can produce the same Shock Pressure distribution far from the impact point (so-called late-stage equivalence). These impact conditions were investigated by numerical calculations with different projectiles and impact velocities. As a result of our calculation for water ice impacts, we found that a power law index of 2.2 instead of 3, as adopted by previous studies, is suitable for reproducing the late-stage equivalence in water ice (i.e., LE is proportional to P0 · Lp2.2). By using this improved LE, we can reconcile the inconsistency between the crater size and the LE indicated by previous studies. By using this improved LE, the crater volume Vcr formed on water ice is expressed by the following equation, Vcr = 1.0 exp (ln/2450), with Vcr in cm3, wherein ln (in Pa m2.2) is a constant derived from a fit to the data.
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Shock Pressure attenuation in water ice at a Pressure below 1 GPa
Journal of Geophysical Research: Planets, 2001Co-Authors: M. Kato, Kei Shirai, Michiya Higa, Yuichi Iijima, Tatsuya Kiyono, Satoru Nakazawa, Masahiko ArakawaAbstract:Shock Pressure attenuation in water ice was studied at an impact Pressure below 1 GPa and a temperature of 255 K. The observed Shock wave showed a multiple Shock wave structure: A precursor wave was followed by a main wave, which had a longer rise time and higher amplitude. The Hugoniot elastic limit (HEL) of water ice was measured to be in the range from 0.1 to 0.3 GPa when associated with precursor waves traveling at 3.86 km/s. The peak amplitude of the main wave Pm was observed to decrease with its propagation x from 3 to 60 mm (from 0.4 to 8 times as large as a projectile radius) in two series of experiments in which initial Shock Pressures Pi at the impact point were 0.60 and 0.87 GPa. The Pm was described as the power law relation Pm/Pi = (x/2.6 mm)−89. The precursor wave disappears as the Pm attenuated to a Pressure
M. Kato - One of the best experts on this subject based on the ideXlab platform.
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Laboratory impact experiments and numerical simulations on Shock Pressure attenuation in water ice
Journal of Geophysical Research, 2008Co-Authors: Kei Shirai, M. Kato, Noriko K. Mitani, Masahiko ArakawaAbstract:[1] High-velocity impact experiments of water ice were conducted to measure the Shock Pressure profile at various distances from the impact point. A numerical simulation of Shock wave propagation in water ice was also conducted for comparison with the experimental results. The numerical model was improved to fit the measured profiles, and it was found that a tensile strength of Yc = 1 MPa was necessary to reproduce the Shock Pressure profiles above the Hugoniot Elastic Limit. This improved numerical model was then used to study the Shock Pressure attenuation in water ice at various impact conditions and to refine the crater scaling law. The late-stage effective energy (LE) is the product of initial Shock Pressure (P0) and the third power of the projectile size (Lp3). The impact conditions with the same late-stage effective energy can produce the same Shock Pressure distribution far from the impact point (so-called late-stage equivalence). These impact conditions were investigated by numerical calculations with different projectiles and impact velocities. As a result of our calculation for water ice impacts, we found that a power law index of 2.2 instead of 3, as adopted by previous studies, is suitable for reproducing the late-stage equivalence in water ice (i.e., LE is proportional to P0 · Lp2.2). By using this improved LE, we can reconcile the inconsistency between the crater size and the LE indicated by previous studies. By using this improved LE, the crater volume Vcr formed on water ice is expressed by the following equation, Vcr = 1.0 exp (ln/2450), with Vcr in cm3, wherein ln (in Pa m2.2) is a constant derived from a fit to the data.
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Shock Pressure attenuation in water ice at a Pressure below 1 GPa
Journal of Geophysical Research: Planets, 2001Co-Authors: M. Kato, Kei Shirai, Michiya Higa, Yuichi Iijima, Tatsuya Kiyono, Satoru Nakazawa, Masahiko ArakawaAbstract:Shock Pressure attenuation in water ice was studied at an impact Pressure below 1 GPa and a temperature of 255 K. The observed Shock wave showed a multiple Shock wave structure: A precursor wave was followed by a main wave, which had a longer rise time and higher amplitude. The Hugoniot elastic limit (HEL) of water ice was measured to be in the range from 0.1 to 0.3 GPa when associated with precursor waves traveling at 3.86 km/s. The peak amplitude of the main wave Pm was observed to decrease with its propagation x from 3 to 60 mm (from 0.4 to 8 times as large as a projectile radius) in two series of experiments in which initial Shock Pressures Pi at the impact point were 0.60 and 0.87 GPa. The Pm was described as the power law relation Pm/Pi = (x/2.6 mm)−89. The precursor wave disappears as the Pm attenuated to a Pressure
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Shock reaction of hexane at 77, 193, and 273 K with special reference to Shock Pressure
Shock Waves, 1998Co-Authors: Koichi Mimura, M. Kato, M. Ohashi, Ryuichi SugisakiAbstract:Shock waves generated by projectile impacts were transmitted into hexane and the Shocked hexane was analyzed by TCD-GC, FID-GC, GCMS, and FABMS for produced aliphatic hydrocarbons. The projectile length and its velocity were varied from 10 to 40 mm and from 220 to 1040 m/s, respectively. The initial temperature of the hexane was 77, 193 and 273 K. The major products detected throughout the reactions were hydrogen, light alkanes from C\(_1\) to C\(_4\), and light alkenes from C\(_2\) to C\(_3\). The minor products were heavy alkanes from C\(_8\) to C\(_{12}\) and soot-like materials. Experiments with varied projectile length revealed that the Shock reaction occurred only while the Shock wave was transmitted through hexane (about \(10^{-6}\) seconds). This short reaction time may be responsible for a lower yield of branched products in the Shock reaction compared with yield produced by hexane pyrolysis in previous studies. In the Shock reaction of hexane, the dehydrogenation was one of the important reactions and the recombination of hexyl radicals might play a role in the formation of \(n\)-C\(_{12}\). Experiments with varied initial temperature suggested that the molar yield of products depends not on the Shock temperature but on the Shock Pressure, and that the reaction mechanisms for solid hexane and for liquid hexane are not identical. As the Shock Pressure increased, the relative yield of heavy products increased while that of light products decreased. This could be interpreted mainly by considering the activation volumes of the reaction involved.