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Sample records for laser induced shock

  1. Multiple structure of a laser-induced underwater shock wave

    CERN Document Server

    Tagawa, Yoshiyuki; Hayasaka, Keisuke; Kameda, Masaharu

    2015-01-01

    The structure of a laser-induced underwater shock wave is examined. Plasma formation, shock-wave expansion, and temporal evolution of shock pressure are observed simultaneously using a combined measurement system that obtains high-resolution nanosecond-order image sequences. In contrast to a well-known spherical-shock model, these detailed measurements reveal a non-spherically-symmteric distribution of pressure peak for a wide range of experimental parameters. The structure is determined to be a collection of multiple spherical shocks originated from elongated plasmas.

  2. Unraveling shock-induced chemistry using ultrafast lasers

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David S [Los Alamos National Laboratory

    2009-01-01

    The exquisite time synchronicity between shock and diagnostics needed to unravel chemical events occurring in picoseconds has been achieved using a shaped ultrafast laser pulse to both drive the shocks and interrogate the sample via a multiplicity of optical diagnostics. The shaped laser drive pulse can produce well-controlled shock states of sub-ns duration with sub-10 ps risetimes, sufficient for investigation of fast reactions or phase transformations in a thin layer with picosecond time resolution. The shock state is characterized using ultrafast dynamic ellipsometry (UDE) in either planar or Gaussian spatial geometries, the latter allowing measurements of the equation of state of materials at a range of stresses in a single laser pulse. Time-resolved processes in materials are being interrogated using UDE, ultrafast infrared absorption, ultrafast UV/visible absorption, and femtosecond stimulated Raman spectroscopy. Using these tools we showed that chemistry in an energetic thin film starts only after an induction time of a few tens of ps, an observation that allows differentiation between proposed shock-induced reaction mechanisms. These tools are presently being applied to a variety of energetic and reactive sample systems, from nitromethane and carbon disulfide, to micro-engineered interfaces in tunable energetic mixtures.

  3. Dynamic response of shear thickening fluid under laser induced shock

    Science.gov (United States)

    Wu, Xianqian; Zhong, Fachun; Yin, Qiuyun; Huang, Chenguang

    2015-02-01

    The dynamic response of the 57 vol./vol. % dense spherical silica particle-polyethylene glycol suspension at high pressure was investigated through short pulsed laser induced shock experiments. The measured back free surface velocities by a photonic Doppler velocimetry showed that the shock and the particle velocities decreased while the shock wave transmitted in the shear thickening fluid (STF), from which an equation of state for the STF was obtained. In addition, the peak stress decreased and the absorbed energy increased rapidly with increasing the thickness for a thin layer of the STF, which should be attributed to the impact-jammed behavior through compression of particle matrix, the deformation or crack of the hard-sphere particles, and the volume compression of the particles and the polyethylene glycol.

  4. Laser light scattering in a laser-induced argon plasma: Investigations of the shock wave

    Energy Technology Data Exchange (ETDEWEB)

    Pokrzywka, B. [Obserwatorium Astronomiczne na Suhorze, Uniwersytet Pedagogiczny, ulica Podchorazych 2, 30-084 Krakow (Poland); Mendys, A., E-mail: agata.mendys@uj.edu.pl [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Dzierzega, K.; Grabiec, M. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Pellerin, S. [GREMI, site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France)

    2012-08-15

    Shock wave produced by a laser induced spark in argon at atmospheric pressure was examined using Rayleigh and Thomson scattering. The spark was generated by focusing a laser pulse from the second harmonic ({lambda} = 532 nm) of a nanosecond Nd:YAG laser using an 80 mm focal length lens, with a fluence of 2 kJ{center_dot}cm{sup -2}. Images of the spark emission were recorded for times between 30 ns and 100 {mu}s after the laser pulse in order to characterize its spatial evolution. The position of the shock wave at several instants of its evolution and for several plasma regions was determined from the Rayleigh-scattered light of another nanosecond Nd:YAG laser (532 nm, 40 J{center_dot}cm{sup -2} fluence). Simultaneously, Thomson scattering technique was applied to determine the electron density and temperature in the hot plasma core. Attempts were made to describe the temporal evolution of the shock wave within a self-similar model, both by the simple Sedov-Taylor formula as well as its extension deduced by de Izarra. The temporal radial evolution of the shock position is similar to that obtained within theory taking into account the counter pressure of the ambient gas. Density profiles just behind the shock front are in qualitative agreement with those obtained by numerically solving the Euler equations for instantaneous explosion at a point with counter pressure. - Highlights: Black-Right-Pointing-Pointer We investigated shock wave evolution by Rayleigh scattering method. Black-Right-Pointing-Pointer 2D map of shockwave position for several times after plasma generation is presented. Black-Right-Pointing-Pointer Shock wave evolution is not satisfactorily described within self-similar models. Black-Right-Pointing-Pointer Evolution of shock position similar to theory taking into account counter pressure. Black-Right-Pointing-Pointer Density profile behind the shock similar to numerical solution of Euler equations.

  5. Mechanism of laser-induced plasma shock wave evolution in air

    Institute of Scientific and Technical Information of China (English)

    Zhao Rui; Liang Zhong-Cheng; Han Bing; Zhang Hong-Chao; Xu Rong-Qing; Lu Jian; Ni Xiao-Wu

    2009-01-01

    A theoretical model is proposed to describe the mechanism of laser-induced plasma shock wave evolution in air. To verify the validity of the theoretical model, an optical beam deflection technique is employed to track the plasma shock wave evolution process. The theoretical model and the experimental signals are found to be in good agreement with each other. It is shown that the laser-induced plasma shock wave undergoes formation, increase and decay processes; the increase and the decay processes of the laser-induced plasma shock wave result from the overlapping of the compression wave and the rarefaction wave, respectively. In addition, the laser-induced plasma shock wave speed and pressure distributions, both a function of distance, are presented.

  6. Velocity Measurement of Induced Flow by a Laser Focusing Shock Wave

    Institute of Scientific and Technical Information of China (English)

    Hiroyuki HIRAHARA; Masaru FUJINAMI; Masaaki KAWAHASHI

    2006-01-01

    The objective of this study is to apply the shock wave for control in a micro channel. The shock wave was generated by a laser focusing of pulsed laser beam in the channel. Using a pulse laser to generate a shock wave,a non-stationary flow was induced in the small space between the parallel plates. The spherical and cylindrical shock propagations were observed with schlieren method. The shock Mach number decreases with time and approaches to unity. As reported in the previous investigations, the shock speed was attenuated in a short distance and time. In the present experiment, It was not found a remarkable difference in the shock speed between the spherical and cylindrical shock experiments. Subsequently, the flow induced by the cylindrical shock wave was studied using PIV technique. A smoke tracer was used in the experiment and its velocity was measured within 100 μs. A numerical simulation was carried out to investigate the momentum relaxation between the gas and smoke particle. A suitable shock initiation model was introduced in the simulation. The experimental results show that a wide acceleration and deceleration zone exist behind the shock wave. Also,the relaxation distance in the experimental data is much longer than that in numerical simulation.

  7. Effects of liquid properties on the dynamics of under-liquid laser-induced shock process

    Science.gov (United States)

    Nguyen, Thao Thi Phuong; Tanabe, Rie; Ito, Yoshiro

    2016-09-01

    We compared the shock processes induced when focusing a single laser pulse (1064 nm, FWHM = 13 ns) onto the surface of epoxy resin blocks immersed in glycerol, water, liquid paraffin, and silicone oils. A custom-designed time-resolved photoelasticity imaging technique was applied to observe the strength of stress wave induced inside the solid target and the propagation of shock waves in the liquid with time resolution of nanoseconds. We demonstrated that the shock impedance of the liquid caused a noticeable effect on the strength of laser-induced stress wave: Ablation in the liquid with a higher shock impedance resulted in a stronger stress. By using glycerol instead of water as the confining medium, the pulse energy required to induce a certain level of stress was reduced by about 20 %. The dynamical behaviors of the main shock wave and the reflected wave in inverted V-shape in each liquid are also discussed in details.

  8. Microstructure and properties of plastic deformed martensite induced by laser shock processing

    Institute of Scientific and Technical Information of China (English)

    Jichang Yang(杨继昌); Yinqun Hua(花银群); Ruifang Chen(陈瑞芳); Lan Cai(蔡兰); Yongkang Zhang(张永康); Hong Yan(颜红)

    2004-01-01

    Firstly, 45# steel was quenched by the NEL-2500A rapidly axial flow CO2 laser. The experimental parameters were the laser power of 750 W, the laser beam diameter of 4 mm, the scanning velocity of 7 mm/s.The thickness of coating layer was 0.1 mm and the width was 8 mm. Secondly, the martensite induced by laser quench was shocked by Nd:YAG laser. The parameters of laser shock processing were the wavelength of 1.06 μm, the pulse duration of 23 ns, and the output energy of 16-20 J. The laser was focused on a spot of φ7 mm. K9 optical glass was used as confinement. The sample was coated with black paint 86-1 (the thickness is about 0.025 mm). By testing and analysis of samples which were treated by laser quench and laser quench+shock with transmission electron microscope (TEM), it was discovered that the surface layer of martensite was deformed plastically by laser shock processing. In the secondary hardened zones,there were a lot of slender secondary twin crystal martensites, dislocation tangles, and cellular dislocations.Compared with that of the hardened zones through laser quench only, the residual stress and mechanical properties of the secondary hardened zones were improved and increased through laser compound method.

  9. Study of laser-induced plasma shock waves by the probe beam deflection technique

    Institute of Scientific and Technical Information of China (English)

    Yan Qian; Jian Lu; Xiaowu Ni

    2009-01-01

    Laser probe beam deflection technique is used for the analysis of laser-induced plasma shock waves in air and distilled water.The temporal and spatial variations of the parameters on shock fronts are studied as funotions of focal lens position and laser energy.The influences of the characteristics of media are investigated on the well-designed experimental setup.It is found that the shock wave in distilled water attenuates to an acoustic wave faster than in air under the same laser energy.Good agreement is obtained between our experimental results and those attained with other techniques.This technique is versatile,economic,and simple to implement,being a pronmising diagnostic tool for pulsed laser processing.

  10. Influence of exothermic chemical reactions on laser-induced shock waves.

    Science.gov (United States)

    Gottfried, Jennifer L

    2014-10-21

    Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time.

  11. Fabricating micro embossments on the metal surface through spatially modulating laser-induced shock wave

    Science.gov (United States)

    Ye, Y. X.; Xuan, T.; Lian, Z. C.; Hua, X. J.; Fu, Y. H.

    2015-12-01

    In this paper, we propose one improved method to fabricate micro embossments on the metal surface through laser shock processing. One mapping layer with holes must be actively designed and produced on the metal surface, with which, laser-induced shock wave will be spatially modulated. Laser shock experiments were conducted. Then the surface morphologies, and metallographic microstructures were characterized. The forming process of the micro embossments was simulated with ABAQUS. The results show that under the spatially modulated shock loading, the surface material flows from the high-pressure zone to the low-pressure zone, which is responsible for forming the micro embossments. The shapes, sizes and arrangements of the micro embossments conform to those of the mapping holes. The hardnesses on the entire laser-shocked zones improve remarkably due to the plastic deformation at a high strain rate. The influences of the laser energy and mask pattern on the embossed structures are presented. Within certain limits, increasing laser energy is beneficial for making the embossment more convex. However, further excessively increasing the laser energy, the embossment will exhibit the height saturation due to the pressure rise within the closed mapping hole. The transverse sizes of the mapping holes also can influence the embossment heights significantly. Process parameters need to be chosen carefully to suppress the severe adiabatic compression of the gas within the mapping holes, and then avoid weakening the mechanical properties of the micro embossments. This method has a potential application in manufacturing protruded structures on the metal surface.

  12. Laser Driven Compression to Investigate Shock-Induced Melting of Metals

    Directory of Open Access Journals (Sweden)

    Thibaut de Rességuier

    2014-10-01

    Full Text Available High pressure shock compression induces a large temperature increase due to the dissipation within the shock front. Hence, a solid sample subjected to intense shock loading can melt, partially or fully, either on compression or upon release from the shocked state. In particular, such melting is expected to be associated with specific damage and fragmentation processes following shock propagation. In this paper, we show that laser driven shock experiments can provide a procedure to investigate high pressure melting of metals at high strain rates, which is an issue of key interest for various engineering applications as well as for geophysics. After a short description of experimental and analytical tools, we briefly review some former results reported for tin, then we present more recent observations for aluminum and iron.

  13. FEM SIMULATION OF RESIDUAL STRESSES INDUCED BY LASER SHOCK WITH OVERLAPPING LASER SPOTS

    Institute of Scientific and Technical Information of China (English)

    Y.X. Hu; Z.Q. Yao

    2008-01-01

    The finite element method is presented to attain the numerical simulation of the residual stresses field in the material treated by laser shock processing. The distribution of residual stresses generated by a single laser shock with square and round laser spot is predicted and validated by experimental results. With the Finite Element Method (FEM) model, effects of different overlapping rates and impact sequences on the distribution of residual stresses are simulated. The results indicate that: (1) Overlapping laser shock can increase the compressive residual stresses. However, it is not effective on the growth of plastically affected depth; (2) Overlapping rate should be optimized and selected carefully for the large area treatment. Appropriate overlapping rate is beneficial to obtain a homogeneous residual stress field; (3) The impact sequence has a great effect on the residual stress field. It can greatly attenuate the phenomenon of the "residual stress hole" to obtain a homogeneous residual stress field.

  14. MARTENSITE TRANSFORMATION MICROSTRUCTURE OF 40Cr STEEL COMPLEXLY INDUCED BY LASER SHOCK

    Institute of Scientific and Technical Information of China (English)

    CHEN Ruifang; HUA Yinqun; CAI Lan

    2007-01-01

    40Cr steel is laser quenched by the NEL-2500A rapidly axial flow CO2 laser. Then the martensite induced by laser quenched is shocked by Nd:YAG laser again. Through comparing and analyzing the appearance and size ofmartensite, the dislocation density in microstructure between the treated zones by laser quenched and by laser quenched plus laser shock, the following results are shown: The second martensite obtained by laser compound treatment is more finer compared with those obtained by laser quenched; In the hardened zones obtained by compound treatment, a lot of slender second twin crystal martensites are induced; A lot of more high density dislocation tangles and cellular dislocations are generated. From the transmission electron microscope (TEM) micrograph after compound treatment, there are not only long lath and short nubbly martensites arranged in cross direction, but also massive nubbly and small short nubbly martensites arranged in longitudinal direction. Some martensites look like the broken blocks of quenched martensites. These new martensites are inserted transversely in the quenched martensites with large tangle. And they make quenched martensites break into pieces. Compared with the quenched martensites, the size of fresh martensites are smaller, about 0.3~0.5 μm.

  15. Ultrafast ignition with relativistic shock waves induced by high power lasers

    Institute of Scientific and Technical Information of China (English)

    Shalom; Eliezer; Noaz; Nissim; Shirly; Vinikman; Pinhasi; Erez; Raicher; José; Maria; Martinez; Val

    2014-01-01

    In this paper we consider laser intensities greater than 1016 W cm-2where the ablation pressure is negligible in comparison with the radiation pressure.The radiation pressure is caused by the ponderomotive force acting mainly on the electrons that are separated from the ions to create a double layer(DL).This DL is accelerated into the target,like a piston that pushes the matter in such a way that a shock wave is created.Here we discuss two novel ideas.Firstly,the transition domain between the relativistic and non-relativistic laser-induced shock waves.Our solution is based on relativistic hydrodynamics also for the above transition domain.The relativistic shock wave parameters,such as compression,pressure,shock wave and particle flow velocities,sound velocity and rarefaction wave velocity in the compressed target,and temperature are calculated.Secondly,we would like to use this transition domain for shockwave-induced ultrafast ignition of a pre-compressed target.The laser parameters for these purposes are calculated and the main advantages of this scheme are described.If this scheme is successful a new source of energy in large quantities may become feasible.

  16. Transient bond scission of polytetrafluoroethylene under laser-induced shock compression studied by nanosecond time-resolved Raman spectroscopy

    Science.gov (United States)

    Nakamura, Kazutaka; Wakabayashi, Kunihiko; Konodo, Ken-Ichi

    2001-06-01

    Nanosecond time-resolved Raman spectroscopy has been performed to study polymer films, polytetrafluoroethylene (PTFE), under laser driven shock compression at laser power density of 4.0 GW/cm^2. The overtone-mode line of PTFE showed red shift (18 cm-1) at delay time of 9.3 ns due to the shock compression and corresponding pressure was estimated to be approximately 2.7 GPa by analyzing static and shock compression data. The estimated pressure was in good agreement with that estimated by ablation pressure in glass-confined geometry. A new vibrational line at 1900 cm-1 appeared only under shock compression and was assigned to the C=C streching in transient species such as a monomer (C_2F_4) produced by the shock-induced bond scission. Intensity of the new line increased with increasing delay time along propagation of the shock compression with a shock velocity of 2.5 km/s.

  17. Application of background-oriented schlieren (BOS) technique to a laser-induced underwater shock wave

    CERN Document Server

    Yamamoto, Shota; Kameda, Masaharu

    2015-01-01

    We build an ultra-high-speed imaging system based on the background-oriented schlieren (BOS) technique in order to capture a laser-induced underwater shock wave. This BOS technique is able to provide two-dimensional density-gradient field of fluid and requires a simple setup. The imaging system consists of an ultra-high speed video camera, a laser stroboscope, and a patterned background. This system takes images every 0.2 $\\mu$s. Furthermore, since the density change of water disturbed by the shock is exceedingly small, the system has high spatial resolution $\\sim$ 10 $\\mu$m/pixel. Using this BOS system, we examine temporal position of a shock wave. The position agrees well with that measured by conventional shadowgraph, which indicates that the high-speed imaging system can successfully capture the instantaneous position of the underwater shock wave that propagates with the speed of about 1500 m/s. The local density gradient can be determined up to $O$(10$^3$ kg/m$^4$), which is confirmed by the gradient est...

  18. Fibre-Coupling Zig-Zag Beam Deflection Technology for Investigation of Attenuation Process of Laser-Induced Shock Waves

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping; BIAN Bao-Min; LI Zhen-Hua

    2005-01-01

    @@ A novel fibre-coupling zig-zag beam deflection technology is developed to investigate the attenuation process of laser-induced shock waves in air. Utilizing ordinal reflections of probe beams by a pair of parallel mirrors,a zig-zag beam field is formed, which has eleven probe beams in the horizontal plane. When a laser-induced shock wave propagates through the testing field, it causes eleven deflection signals one after another. The whole attenuation process of the shock wave in air can be detected and illuminated clearly on one experimental curve.

  19. Characteristics of laser-induced shock wave injury to the inner ear of rats

    Science.gov (United States)

    Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

    2014-12-01

    Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

  20. High-power laser shock-induced dynamic fracture of aluminum and microscopic observation of samples

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2015-01-01

    Full Text Available High-power laser induced shocks generated by “ShenGuang II” laser facility has been used to study spall fracture of polycrystalline aluminum at strain rates more than 106/s. The free surface velocity histories of shock-loaded samples, 150 μm thick and with initial temperature from 293 K to 873 K, have been recorded using velocity interferometer system for any reflector (VISAR. From the free surface velocity profile, spall strength and yield stress are calculated, it demonstrates that spall strength will decline and yield strength increase with initial temperature. The loaded samples are recovered to obtain samples' section and free surface metallographic pictures through Laser Scanning Confocal Microscopy. It is found that there are more micro-voids and more opportunity to appear bigger voids near the spall plane and the grain size increases with temperature slowly but smoothly except the sharply change at 893 K (near melting point. Besides, the fracture mechanisms change from mainly intergranular fracture to transgranular fracture with the increase of initial temperature.

  1. Shock induced damage and damage threshold of optical K9 glass investigated by laser-driven shock wave

    Science.gov (United States)

    Song, Yunfei; Yu, Guoyang; Jiang, Lilin; Zheng, Xianxu; Liu, Yuqiang; Yang, Yanqiang

    2011-04-01

    The shock wave driven by short laser pulse is used to study the damage of brittle material K9 glass. The damage morphology of K9 glass surface indicates that the material has experienced different loading modes, respectively, at the central area and the surrounding area of the shock wave. At the central area of shock wave, the wavefront is plane and has a uniform pressure distribution, the material mainly suffers a longitudinal shock pressure; but on the edge the shock wave, the wavefront is approximately spherical, besides longitudinal pressure, transverse tensile stress will emerge inside the material. In the latter case, the damage threshold of the material is much smaller than that in the case of compressing by longitudinal pressure only. According to the relationship between damage area and shock pressure, an experimental method is proposed to measure the damage threshold of materials under shock loading. The damage threshold of K9 glass under spherical shock wave is measured to be about 1.12 GPa; and the damage threshold under plane shock wave is estimated to be between 1.82 and 1.98 GPa. They are much bigger than the damage threshold under static pressure. This method could also be used to measure the damage threshold of other materials when loaded by dynamic pressure.

  2. Numerical Analysis of Interaction Between Single-Pulse Laser-Induced Plasma and Bow Shock in a Supersonic Flow

    Institute of Scientific and Technical Information of China (English)

    FANG Juan; HONG Yanji; LI Qian

    2012-01-01

    The interaction of laser-induced plasma and bow shock over a blunt body is inves- tigated numerically in an M∞ =6.5 supersonic flow. A ray-tracing method is used for simulating the process of laser focusing. The gas located at the focused zone is ionized and broken down and transformed into plasma. In a supersonic flow the plasma moves downstream and begins to interact with the bow shock when it approaches the surface of the blunt body. The parameters of flowfield and blunt body surface are changed due to the interaction. By analyzing phenomena occurring in the complex unsteady flowfield during the interaction in detail, we can better under- stand the change of pressure on the blunt body surface and the mechanism of drag reduction by laser energy deposition. The results show that the bow shock is changed into an oblique shock due to the interaction of the laser-induced low-density zone with the bow shock, so the wave drag of the blunt body is reduced.

  3. Supersaturation dependence of glycine polymorphism using laser-induced nucleation, sonocrystallization and nucleation by mechanical shock.

    Science.gov (United States)

    Liu, Yao; van den Berg, Mees H; Alexander, Andrew J

    2017-07-26

    The nucleation of glycine from aqueous supersaturated solution has been studied using non-photochemical laser-induced nucleation (NPLIN), ultrasound (sonocrystallization), and mechanical shock of sample vials. It was found that at higher supersaturation, samples were more susceptible to nucleation and produced more of the γ-glycine polymorph. The results are described in terms of a mechanism common to all three nucleation methods, involving the induction of cavitation events and pressure shockwaves. The switch in preference from α- to γ-glycine was observed to occur over a narrower range of supersaturation values for NPLIN. We attribute this to induction of cavitation events with higher energies, which result in higher localized pressures and supersaturations. Experiments on NPLIN using circularly versus linearly polarized light showed no evidence for binary polarization switching control of glycine polymorphism.

  4. Shock dynamics induced by double-spot laser irradiation of layered targets

    Directory of Open Access Journals (Sweden)

    Aliverdiev Abutrab A.

    2015-06-01

    Full Text Available We studied the interaction of a double-spot laser beam with targets using the Prague Asterix Laser System (PALS iodine laser working at 0.44 μm wavelength and intensity of about 1015 W/cm2. Shock breakout signals were recorder using time-resolved self-emission from target rear side of irradiated targets. We compared the behavior of pure Al targets and of targets with a foam layer on the laser side. Results have been simulated using hydrodynamic numerical codes.

  5. Structural Modifications in Fused Silica Due to Laser Damage Induced Shock Compression

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, A; Davila, L; Caturla, M J; Stolken, J S; Sadigh, B; Quong, A; Rubenchik, A; Feit, M D

    2001-12-05

    High power laser pulses can produce damage in high quality fused silica optics that can lead to its eventual obscuration and failure. Current models suggest the initiation of a plasma detonation due to absorbing initiators and defects, leading to the formation of shock waves. Recent experiments have found a densified layer at the bottom of damage sites, as evidence of the laser-damage model. We have studied the propagation of shock waves through fused silica using molecular dynamics. These simulations show drastic modifications in the structure and topology of the network, in agreement with experimental observations.

  6. The use of laser-induced shock wave plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmadjid, Syahrun Nur, E-mail: syahrun-madjid@yahoo.com; Lahna, Kurnia, E-mail: kurnialahna@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, Aceh (Indonesia); Desiyana, Lydia Septa, E-mail: lydia-septa@yahoo.com [Department of Pharmacy, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, Aceh (Indonesia)

    2016-03-11

    An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma induced by Nd-YAG laser at a low pressure of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-Induced Shock Wave Plasma Spectroscopy (LISPS), the shock wave has a significant role in inducing atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablated atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-induced plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.

  7. Molecular dynamics simulation of laser shock phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Ichirou [Japan Atomic Energy Research Inst., Kansai Research Establishment, Advanced Photon Research Center, Neyagawa, Osaka (Japan).

    2001-10-01

    Recently, ultrashort-pulse lasers with high peak power have been developed, and their application to materials processing is expected as a tool of precision microfabrication. When a high power laser irradiates, a shock wave propagates into the material and dislocations are generated. In this paper, laser shock phenomena of the metal were analyzed using the modified molecular dynamics method, which has been developed by Ohmura and Fukumoto. The main results obtained are summarized as follows: (1) The shock wave induced by the Gaussian beam irradiation propagates radially from the surface to the interior. (2) A lot of dislocations are generated at the solid-liquid interface by the propagation of a shock wave. (3) Some dislocations are moved instantaneously with the velocity of the longitudinal wave when the shock wave passes, and their velocity is not larger than the transverse velocity after the shock wave has passed. (author)

  8. Single cell manipulation utilizing femtosecond laser-induced shock and stress waves

    Science.gov (United States)

    Hosokawa, Yoichiroh

    2017-02-01

    When an intense femtosecond laser pulse is focused into a culture medium through an objective lens, an impulsive force is loaded on the cells with generations of the shock and stress waves at the laser focal point. The shock and stress waves were acted to single cells in the vicinity of the laser focal point as an impulsive force. We have applied the impulsive force to manipulate single cells. As the transient intensity of the impulsive force is over 1000 times stronger than the force due to optical tweezers, drastic single manipulation which is difficult by the optical tweezers can be realized. The generation process of the impulsive force and behavior of animal cell after loading the impulsive force were reviewed, and then our original quantification method of the impulsive force utilizing atomic force microscope (AFM) was introduced with its applications for evaluating adhesions between animal cells and between sub-organelles in plant cell.

  9. Pulsed laser-induced liquid jet: evolution from shock/bubble interaction to neurosurgical application

    Science.gov (United States)

    Nakagawa, A.; Kumabe, T.; Ogawa, Y.; Hirano, T.; Kawaguchi, T.; Ohtani, K.; Nakano, T.; Sato, C.; Yamada, M.; Washio, T.; Arafune, T.; Teppei, T.; Atsushi, K.; Satomi, S.; Takayama, K.; Tominaga, T.

    2016-11-01

    The high-speed liquid (water) jet has distinctive characteristics in surgical applications, such as tissue dissection without thermal damage and small blood vessel preservation, that make it advantageous over more conventional instruments. The continuous pressurized jet has been used since the first medical application of water jets to liver surgery in the 1980s, but exhibited drawbacks partly related to the excess water supply required and unsuitability for application to microsurgical instruments intended for deep, narrow lesions (endoscopic instrumentation and catheters) due to limitations in miniaturization of the device. To solve these issues, we initiated work on the pulsed micro-liquid jet. The idea of the pulsed micro-liquid jet originated from the observation of tissue damage by shock/bubble interactions during extracorporeal shock wave lithotripsy and evolved into experimental application for recanalization of cerebral embolisms in the 1990s. The original method of generating the liquid jet was based on air bubble formation and microexplosives as the shock wave source, and as such could not be applied clinically. The air bubble was replaced by a holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced bubble. Finally, the system was simplified and the liquid jet was generated via irradiation from the Ho:YAG laser within a liquid-filled tubular structure. A series of investigations revealed that this pulsed laser-induced liquid jet (LILJ) system has equivalent dissection and blood vessel preservation characteristics, but the amount of liquid usage has been reduced to less than 2 μ l per shot and can easily be incorporated into microsurgical, endoscopic, and catheter devices. As a first step in human clinical studies, we have applied the LILJ system for the treatment of skull base tumors through the transsphenoidal approach in 9 patients (7 pituitary adenomas and 2 chordomas), supratentorial glioma (all high grade glioma) in 8 patients, including one with

  10. Pulsed laser-induced liquid jet: evolution from shock/bubble interaction to neurosurgical application

    Science.gov (United States)

    Nakagawa, A.; Kumabe, T.; Ogawa, Y.; Hirano, T.; Kawaguchi, T.; Ohtani, K.; Nakano, T.; Sato, C.; Yamada, M.; Washio, T.; Arafune, T.; Teppei, T.; Atsushi, K.; Satomi, S.; Takayama, K.; Tominaga, T.

    2017-01-01

    The high-speed liquid (water) jet has distinctive characteristics in surgical applications, such as tissue dissection without thermal damage and small blood vessel preservation, that make it advantageous over more conventional instruments. The continuous pressurized jet has been used since the first medical application of water jets to liver surgery in the 1980s, but exhibited drawbacks partly related to the excess water supply required and unsuitability for application to microsurgical instruments intended for deep, narrow lesions (endoscopic instrumentation and catheters) due to limitations in miniaturization of the device. To solve these issues, we initiated work on the pulsed micro-liquid jet. The idea of the pulsed micro-liquid jet originated from the observation of tissue damage by shock/bubble interactions during extracorporeal shock wave lithotripsy and evolved into experimental application for recanalization of cerebral embolisms in the 1990s. The original method of generating the liquid jet was based on air bubble formation and microexplosives as the shock wave source, and as such could not be applied clinically. The air bubble was replaced by a holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced bubble. Finally, the system was simplified and the liquid jet was generated via irradiation from the Ho:YAG laser within a liquid-filled tubular structure. A series of investigations revealed that this pulsed laser-induced liquid jet (LILJ) system has equivalent dissection and blood vessel preservation characteristics, but the amount of liquid usage has been reduced to less than 2 μ l per shot and can easily be incorporated into microsurgical, endoscopic, and catheter devices. As a first step in human clinical studies, we have applied the LILJ system for the treatment of skull base tumors through the transsphenoidal approach in 9 patients (7 pituitary adenomas and 2 chordomas), supratentorial glioma (all high grade glioma) in 8 patients, including one with

  11. Recoverable stress induced two-way shape memory effect on NiTi surface using laser-produced shock wave

    Science.gov (United States)

    Seyitliyev, Dovletgeldi; Li, Peizhen; Kholikov, Khomidkhodza; Grant, Byron; Thomas, Zachary; Alal, Orhan; Karaca, Haluk E.; Er, Ali O.

    2017-02-01

    The surfaces of Ni50Ti50 shape memory alloys (SMAs) were patterned by laser scribing. This method is more simplistic and efficient than traditional indentation techniques, and has also shown to be an effective method in patterning these materials. Different laser energy densities ranging from 5 mJ/pulse to 56 mJ/pulse were used to observe recovery on SMA surface. The temperature dependent heat profiles of the NiTi surfaces after laser scribing at 56 mJ/pulse show the partially-recovered indents, which indicate a "shape memory effect (SME)" Experimental data is in good agreement with theoretical simulation of laser induced shock wave propagation inside NiTi SMAs. Stress wave closely followed the rise time of the laser pulse to its peak values and initial decay. Further investigations are underway to improve the SME such that the indents are recovered to a greater extent.

  12. Influence of laser induced hot electrons on the threshold for shock ignition of fusion reactions

    Science.gov (United States)

    Colaïtis, A.; Ribeyre, X.; Le Bel, E.; Duchateau, G.; Nicolaï, Ph.; Tikhonchuk, V.

    2016-07-01

    The effects of Hot Electrons (HEs) generated by the nonlinear Laser-Plasma Interaction (LPI) on the dynamics of Shock Ignition Inertial Confinement Fusion targets are investigated. The coupling between the laser beam, plasma dynamics and hot electron generation and propagation is described with a radiative hydrodynamics code using an inline model based on Paraxial Complex Geometrical Optics [Colaïtis et al., Phys. Rev. E 92, 041101 (2015)]. Two targets are considered: the pure-DT HiPER target and a CH-DT design with baseline spike powers of the order of 200-300 TW. In both cases, accounting for the LPI-generated HEs leads to non-igniting targets when using the baseline spike powers. While HEs are found to increase the ignitor shock pressure, they also preheat the bulk of the imploding shell, notably causing its expansion and contamination of the hotspot with the dense shell material before the time of shock convergence. The associated increase in hotspot mass (i) increases the ignitor shock pressure required to ignite the fusion reactions and (ii) significantly increases the power losses through Bremsstrahlung X-ray radiation, thus rapidly cooling the hotspot. These effects are less prominent for the CH-DT target where the plastic ablator shields the lower energy LPI-HE spectrum. Simulations using higher laser spike powers of 500 TW suggest that the CH-DT capsule marginally ignites, with an ignition window width significantly smaller than without LPI-HEs, and with three quarters of the baseline target yield. The latter effect arises from the relation between the shock launching time and the shell areal density, which becomes relevant in presence of a LPI-HE preheating.

  13. Experimental study on pressure, stress state, and temperature-dependent dynamic behavior of shear thickening fluid subjected to laser induced shock

    Science.gov (United States)

    Wu, Xianqian; Yin, Qiuyun; Huang, Chenguang

    2015-11-01

    The dynamic response of the 57 vol./vol. % dense spherical silica particle-polyethylene glycol suspension at high pressure was investigated through short pulsed laser induced shock experiments by measuring the back free surface velocities of aluminum-shear thickening fluid (STF)-aluminum assembled targets. The results showed that the attenuation behavior of shock wave in the STF was dependent on shock pressure, stress state, and test temperature. The measured back free particle velocities of the targets and shock wave velocities in the STF decreased with the decrease in shock pressure while shocked at the same stress state and the same test temperature. In addition, two types of dragging mechanisms in the STF were observed while shocked at different stress states. For a uniaxial strain state, the impact induced jamming behavior in the STF is the dragging mechanism for the attenuation of shock wave, and a critical shock pressure was required for the impact induced thickening behavior. However, while the shock wave transformed from a uniaxial strain state to a dilatation state after transmitted to a certain distance, beside the dragging effect of impact induced jamming behavior, a strong dragging effect, induced by shear induced thickening behavior, was also observed.

  14. Effect of an absorbent overlay on the residual stress field induced by laser shock processing on aluminum samples

    Energy Technology Data Exchange (ETDEWEB)

    Rubio-Gonzalez, C. [Centro de Ingenieria y Desarrollo Industrial, Pie de la Cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130 (Mexico)]. E-mail: crubio@cidesi.mx; Gomez-Rosas, G. [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de los Lagos, Universidad de Guadalajara. Lagos de Moreno Jal. (Mexico); Ocana, J.L. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain); Molpeceres, C. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain); Banderas, A. [Centro de Ingenieria y Desarrollo Industrial, Pie de la Cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130 (Mexico); Porro, J. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain); Morales, M. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain)

    2006-07-15

    Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto aluminum samples. Density of 2500 pulses/cm{sup 2} with infrared (1064 nm) radiation was used. The effect of an absorbent overlay on the residual stress field using this LSP setup and this energy level is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the overlay makes the compressive residual stress profile move to the surface. This effect is explained on the basis of the vaporization of the coat layer suppressing thermal effects on the metallic substrate. The effect of coating the specimen surface before LSP treatment may have advantages on improving wear and contact fatigue properties of this aluminum alloy.

  15. Optical-flow-based background-oriented schlieren technique for measuring a laser-induced underwater shock wave

    CERN Document Server

    Hayasaka, Keisuke; Liu, Tianshu; Kameda, Masaharu

    2016-01-01

    The background-oriented schlieren (BOS) technique with the physics-based optical flow method (OF-BOS) is developed for measuring the pressure field of a laser-induced underwater shock wave. Compared to BOS with the conventional cross-correlation method in PIV (called PIV-BOS), by using the OF-BOS, the displacement field generated by the small density gradient in water can be obtained at the spatial resolution of one vector per pixel. The corresponding density and pressure fields can be further extracted. It is particularly demonstrated that the sufficiently high spatial resolution of the extracted displacement vector field is required in the tomographic reconstruction to correctly infer the pressure field of the spherical underwater shock wave. The capability of the OF-BOS is critically evaluated based on synchronized hydrophone measurements. Special emphasis is placed on direct comparison between the OF-BOS with the PIV-BOS.

  16. Optical-flow-based background-oriented schlieren technique for measuring a laser-induced underwater shock wave

    Science.gov (United States)

    Hayasaka, Keisuke; Tagawa, Yoshiyuki; Liu, Tianshu; Kameda, Masaharu

    2016-12-01

    The background-oriented schlieren (BOS) technique with the physics-based optical flow method (OF-BOS) is developed for measuring the pressure field of a laser-induced underwater shock wave. Compared to BOS with the conventional cross-correlation method that is also applied for particle image velocimetry (here called PIV-BOS), by using the OF-BOS, the displacement field generated by a small density gradient in water can be obtained at the spatial resolution of one vector per pixel. The corresponding density and pressure fields can be further extracted. It is demonstrated in particular that the sufficiently high spatial resolution of the extracted displacement vector field is required in the tomographic reconstruction to correctly infer the pressure field of the spherical underwater shock wave. The capability of the OF-BOS method is critically evaluated based on synchronized hydrophone measurements. Special emphasis is placed on direct comparison between the OF-BOS and PIV-BOS methods.

  17. Mechanical effects induced by shock waves generated by high energy laser pulses

    Science.gov (United States)

    Fournier, J.; Ballard, P.; Merrien, P.; Barralis, J.; Castex, L.; Fabbro, R.

    1991-09-01

    Specimens made of low alloy and non alloyed medium carbon steels were subjected to high energy laser pulses. Direct ablation and confined plasma procedures were both investigated. An optimum impulse momentum transfer to the material is attained with a pulse duration of 30 ns and a power density of 10 GW .cm^2. Fatigue testing shows that the fatigue strengths of the selected materials are significantly increased. This can be related to the fact that laser shock processing generates an appropriate residual compressive stress field in a sufficiently thick layer and does not alter the initial surface roughness. In addition, the use of cumulative laser impacts and of dual treatment combining thermal and mechanical effects of the laser beam have been investigated and shown to result in an enhanced fatigue strength. Des échantillons d'acier éventuellement faiblement allié sont irradiés par un ou plusieurs pulses laser ayant une intensité comprise entre 1 et 100 GW/cm^2 et une durée d'émission laser de 3 ou 30 ns, les deux configurations d'ablation directe ou de plasma confiné étant utilisées. Les contraintes résiduelles résultant du passage de l'onde de choc sont analysées à l'aide de la technique de diffraction de rayons X. D'après cette étude, il apparaît clairement que les valeurs d'intensité et de durée d'émission laser les plus appropriées sont respectivement 10 GW/cm^2 et 30 ns. Ces valeurs correspondent à l'optimum de transfert d'impulsion. De plus, l'influence du nombre d'impacts laser utilisés est discuté et un essai de fatigue montre que ce traitement mécanique de surface augmente de manière significative la limite d'endurance du matériau étudié.

  18. Investigation of the crater-like microdefects induced by laser shock processing with aluminum foil as absorbent layer

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Y.X., E-mail: yeyunxia@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Xuan, T.; Lian, Z.C.; Feng, Y.Y.; Hua, X.J. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China)

    2015-06-01

    Highlights: • Crater-like microdefects formed on metal surface during laser shock process. • The air bubbles in the bonding material are responsible for forming microdefects. • Adiabatic compression of the air bubbles increases the temperature effectively. • Secondary shock wave induced by air bubbles is responsible for forming the defects. • Temperature increases due to shock heat and plastic deformation are limited. - Abstract: This paper reports that 3D crater-like microdefects form on the metal surface when laser shock processing (LSP) is applied. LSP was conducted on pure copper block using the aluminum foil as the absorbent material and water as the confining layer. There existed the bonding material to attach the aluminum foil on the metal target closely. The surface morphologies and metallographs of copper surfaces were characterized with 3D profiler, the optical microscopy (OM) or the scanning electron microscopy (SEM). Temperature increases of metal surface due to LSP were evaluated theoretically. It was found that, when aluminum foil was used as the absorbent material, and if there existed air bubbles in the bonding material, the air temperatures within the bubbles rose rapidly because of the adiabatic compression. So at the locations of the air bubbles, the metal materials melted and micromelting pool formed. Then under the subsequent expanding of the air bubbles, a secondary shock wave was launched against the micromelting pool and produced the crater-like microdefects on the metal surface. The temperature increases due to shock heat and high-speed deformation were not enough to melt the metal target. The temperature increase induced by the adiabatic compression of the air bubbles may also cause the gasification of the metal target. This will also help form the crater-like microdefects. The results of this paper can help to improve the surface quality of a metal target during the application of LSP. In addition, the results provide another

  19. Shadowgraph studies of laser-assisted non-thermal structuring of thin layers on flexible substrates by shock-wave-induced delamination processes

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Pierre, E-mail: pierre.lorenz@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Smausz, Tomi [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); MTA-SZTE Research Group on Photoacoustic Spectroscopy, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Csizmadia, Tamas [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Ehrhardt, Martin; Zimmer, Klaus [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Hopp, Bela [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

    2015-05-01

    Highlights: • The shock-wave-induced film delamination (SWIFD) is a laser patterning process. • The SWIFD process of CIGS solar cells was studied by shadowgraph measurements. • The study presented that SWIFD allows the structuring of CIGS solar cells. • The dynamics of the delamination process was analyzed. - Abstract: The laser-assisted microstructuring of thin films especially for electronic applications without damaging the layers or the substrates is a challenge for the laser micromachining techniques. The laser-induced thin-film patterning by ablation of the polymer substrate at the rear side that is called ‘SWIFD’ – shock-wave-induced film delamination patterning has been demonstrated. This study focuses on the temporal sequence of processes that characterize the mechanism of this SWIFD process on a copper indium gallium selenide (CIGS) solar cell stacks on polyimide. For this purpose high-speed shadowgraph experiments were performed in a pump probe experimental set-up using a KrF excimer laser for ablating the rear side of the polyimide substrate and measuring the shock wave generation at laser ablation of the polymer substrate as well as the thin-film delamination. The morphology and size of the thin-film structures were studied by scanning electron microscopy (SEM). Furthermore, the composition after the laser treatment was analyzed by energy dispersive X-ray (EDX) spectroscopy. The shadowgraph experiments allow the time-dependent identification and evaluation of the shock wave formation, substrate bending, and delamination of the thin film in dependence on the laser parameters. These results will contribute to improve the physical understanding of the laser-induced delamination effect for thin-film patterning.

  20. Structural and mechanical modifications induced on Zr-based bulk metallic glass by laser shock peening

    Science.gov (United States)

    Zhu, Yunhu; Fu, Jie; Zheng, Chao; Ji, Zhong

    2016-12-01

    In this study, surface modification of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 (vit1) bulk metallic glass (BMG) has been studied in an effort to improve the mechanical properties by laser shock peening (LSP) treatment. The phase structure, mechanical properties, and microstructural evolution of the as-cast and LSP treated specimens were systematically investigated. It was found that the vit1 BMG still consisted of fully amorphous structure after LSP treatment. Measurements of the heat relaxation indicate that a large amount of free volume is introduced into vit1 BMG during LSP process. LSP treatment causes a decrease of hardness attributable to generation of free volume. The plastic deformation ability of vit1 BMG was investigated under three-point bending conditions. The results demonstrate that the plastic strain of LSP treated specimen is 1.83 times as large as that of the as-cast specimen. The effect of LSP technology on the hardness and plastic deformation ability of vit1 BMG is discussed on the basis of free volume theory. The high dense shear bands on the side surface, the increase of striations and critical shear displacement on the tensile fracture region, and more uniform dimples structure on the compressive fracture region also demonstrate that the plasticity of vit1 BMG can be enhanced by LSP.

  1. Microjet Penetrator - medical use of laser induced shock waves and bubbles

    Science.gov (United States)

    Yoh, Jack

    2013-06-01

    The laser-driven microjet penetrator system accelerates liquids drug and delivers them without a needle, which is shown to overcome the weaknesses of existing piston-driven jet injectors. The system consists of two back-to-back chambers separated by a rubber membrane, one containing ``driving'' water behind another of the liquid drug to be delivered. The laser pulse is sent once, and a bubble forms in the water chamber, which puts elastic strain on the membrane, causing the drug to be forcefully ejected from a miniature nozzle in a narrow jet of 150 micron in diameter. The impacting jet pressure is higher than the skin tensile strength and thus causes the jet to penetrate into the targeted depth underneath the skin. Multiple pulses of the laser increase the desired dosage. The experiments are performed with commercially available Nd:YAG and Er:YAG lasers for clinical applications in laser dermatology and dentistry. The difference in bubble behavior within the water chamber comes from pulse duration and wavelength. For Nd:YAG laser, the pulse duration is very short relative to the bubble lifetime making the bubble behavior close to that of a cavitation bubble (inertial), while in Er:YAG case the high absorption in water and the longer pulse duration change the initial behavior of the bubble making it close to a vapor bubble (thermal). The contraction and subsequent rebound for both cases were seen typical of cavitation bubble. The laser-induced microjet penetrators generate velocities which are sufficient for delivery of drug into a guinea-pig skin for both laser beams of different pulse duration and wavelength. We estimate the typical velocity within 30-80 m/s range and the breakup length to be larger than 1 mm, thus making it a contamination-free medical procedure. Hydrodynamic theory confirms the nozzle exit jet velocity obtained by the microjet system. A significant increase in the delivered dose of drugs is achieved with multiple pulses of a 2.9 μm Er

  2. Dynamic response and residual stress fields of Ti6Al4V alloy under shock wave induced by laser shock peening

    Science.gov (United States)

    Sun, Rujian; Li, Liuhe; Zhu, Ying; Zhang, Lixin; Guo, Wei; Peng, Peng; Li, Bo; Guo, Chao; Liu, Lei; Che, Zhigang; Li, Weidong; Sun, Jianfei; Qiao, Hongchao

    2017-09-01

    Laser shock peening (LSP), an innovative surface treatment technique, generates compressive residual stress on the surface of metallic components to improve their fatigue performance, wear resistance and corrosion resistance. To illustrate the dynamic response during LSP and residual stress fields after LSP, this study conducted FEM simulations of LSP in a Ti6Al4V alloy. Results showed that when power density was 7 GW cm-2, a plastic deformation occurred at 10 ns during LSP and increased until the shock pressure decayed below the dynamic yield strength of Ti6Al4V after 60 ns. A maximum tensile region appeared beneath the surface at around 240 ns, forming a compressive-tensile-compressive stress sandwich structure with a thickness of 98, 1020 and 606 μm for each layer. After the model became stabilized, the value of the surface residual compressive stress was 564 MPa at the laser spot center. Higher value of residual stress across the surface and thicker compressive residual stress layers were achieved by increasing laser power density, impact times and spot sizes during LSP. A ‘Residual stress hole’ occurred with a high laser power density of 9 GW cm-2 when laser pulse duration was 10 ns, or with a long laser pulse duration of 20 ns when laser power density was 7 GW cm-2 for Ti6Al4V. This phenomenon occurred because of the permanent reverse plastic deformation generated at laser spot center.

  3. Targeted gene expression without a tissue-specific promoter: creating mosaic embryos using laser-induced single-cell heat shock

    Science.gov (United States)

    Halfon, M. S.; Kose, H.; Chiba, A.; Keshishian, H.

    1997-01-01

    We have developed a method to target gene expression in the Drosophila embryo to a specific cell without having a promoter that directs expression in that particular cell. Using a digitally enhanced imaging system to identify single cells within the living embryo, we apply a heat shock to each cell individually by using a laser microbeam. A 1- to 2-min laser treatment is sufficient to induce a heat-shock response but is not lethal to the heat-shocked cells. Induction of heat shock was measured in a variety of cell types, including neurons and somatic muscles, by the expression of beta-galactosidase from an hsp26-lacZ reporter construct or by expression of a UAS target gene after induction of hsGAL4. We discuss the applicability of this technique to ectopic gene expression studies, lineage tracing, gene inactivation studies, and studies of cells in vitro. Laser heat shock is a versatile technique that can be adapted for use in a variety of research organisms and is useful for any studies in which it is desirable to express a given gene in only a distinct cell or clone of cells, either transiently or constitutively, at a time point of choice.

  4. Laser shock cleaning of radioactive particulates from glass surface

    Science.gov (United States)

    Kumar, Aniruddha; Prasad, Manisha; Bhatt, R. B.; Behere, P. G.; Afzal, Mohd.; Kumar, Arun; Nilaya, J. P.; Biswas, D. J.

    2014-06-01

    Efficient removal of Uranium-di-oxide (UO2) particulates from glass surface was achieved by Nd-YAG laser induced airborne plasma shock waves. The velocity of the generated shock wave was measured by employing the photo-acoustic probe deflection method. Experiments were carried out to study the effect of laser pulse energy, number of laser exposures and the separation between the substrate surface and the onset point of the shock wave on the de-contamination efficiency. The efficacy of the process was estimated monitoring the alpha activity of the samples before and after laser shock cleaning using a ZnS (Ag) scintillation detector. Significant cleaning efficiency could be achieved when the substrate was exposed to multiple laser shocks that could be further improved by geometrically confining the plasma. No visual damage or loss in optical quality was observed when the shock cleaned surfaces were analysed by optical microscopy and spectrophotometry. The area cleaned by laser shock cleaning was found to be significantly larger than that possible by conventional laser cleaning. Theoretical estimate of the shock force generated has been found to exceed the van der Waal`s binding force for spherical contaminant particulate.

  5. A parametric study of laser spot size and coverage on the laser shock peening induced residual stress in thin aluminium samples

    Directory of Open Access Journals (Sweden)

    M. Sticchi

    2015-07-01

    Full Text Available Laser Shock Peening is a fatigue enhancement treatment using laser energy to induce compressive Residual Stresses (RS in the outer layers of metallic components. This work describes the variations of introduced RS-field with peen size and coverage for thin metal samples treated with under-water-LSP. The specimens under investigation were of aluminium alloy AA2024-T351, AA2139-T3, AA7050-T76 and AA7075-T6, with thickness 1.9 mm. The RS were measured by using Hole Drilling with Electronic Speckle Pattern Interferometry and X-ray Diffraction. Of particular interest are the effects of the above mentioned parameters on the zero-depth value, which gives indication of the amount of RS through the thickness, and on the value of the surface compressive stresses, which indicates the magnitude of induced stresses. A 2D-axisymmetrical Finite Element model was created for a preliminary estimation of the stress field trend. From experimental results, correlated with numerical and analytical analysis, the following conclusions can be drawn: increasing the spot size the zero-depth value increases with no significant change of the maximum compressive stress; the increase of coverage leads to significant increase of the compressive stress; thin samples of Al-alloy with low Hugoniot Elastic Limit (HEL reveal deeper compression field than alloy with higher HEL value.

  6. Shock induced cavity collapse

    Science.gov (United States)

    Skidmore, Jonathan; Doyle, Hugo; Tully, Brett; Betney, Matthew; Foster, Peta; Ringrose, Tim; Ramasamy, Rohan; Parkin, James; Edwards, Tom; Hawker, Nicholas

    2016-10-01

    Results from the experimental investigation of cavity collapse driven by a strong planar shock (>6km/s) are presented. Data from high speed framing cameras, laser backlit diagnostics and time-resolved pyromety are used to validate the results of hydrodynamic front-tracking simulations. As a code validation exercise, a 2-stage light gas gun was used to accelerate a 1g Polycarbonate projectile to velocities exceeding 6km/s; impact with a PMMA target containing a gas filled void results in the formation of a strong shockwave with pressures exceeding 1Mbar. The subsequent phenomena associated with the collapse of the void and excitation of the inert gas fill are recorded and compared to simulated data. Variation of the mass density and atomic number of the gas fill is used to alter the plasma parameters furthering the extent of the code validation.

  7. The Role of Sub-Target in the Transversely Excited Atmospheric Pressure CO 2 Laser-Induced Shock-Wave Plasma

    Science.gov (United States)

    Suliyanti, Maria; Hedwig, Rinda; Kurniawan, Hendrik; Kagawa, Kiichiro

    1998-12-01

    A transversely excited atmospheric pressure (TEA) CO2 laser pulse (50 mJ, 100 ns) was focused on silicon grease which is painted on a copper plate as a subtarget with a power density of 6 GW/cm2 under reduced pressure. The comparison of the characteristics of the induced laser plasma between two cases, with subtarget and without subtarget was made. It is proved that the emission spectrum assigned to the silicon atom can be detected only for the case with the subtarget. It is also proved that in the absence of the subtarget, the gushing speed of the atom is very low, while for the case with subtarget, the gushing speed of atoms becomes very fast. It is shown that the setting of subtarget is very effective for producing laser-induced shock wave plasma and it is very effective for the realize quantitative analysis of a soft material.

  8. Prepulse-induced shock waves in the gas jet target of a laser plasma EUV radiation source

    Science.gov (United States)

    Garbaruk, A. V.; Gritskevich, M. S.; Kalmykov, S. G.; Mozharov, A. M.; Sasin, M. E.

    2017-01-01

    In experiments with a laser-plasma EUV-radiation source, the main IR Nd:YAG laser pulse was preceded by that of a UV KrF excimer laser. Dramatic modulations of EUV plasma emissivity have been observed at long interpulse times, from hundreds of nanoseconds up to microseconds. To discover the nature of these prepulse-produced long-living perturbations of the target, a fluid dynamics numerical simulation of the Xe gas jet has been carried out. The prepulse has been found to generate a quasi-spherical shock wave with a thin dense front layer and a vast rarefied inside area. In the course of time, the front expands and simultaneously drifts downstream along with the gas. Depending on the interpulse time, the IR laser beam either intersects the dense layer or propagates within the rarefied gas cavity whereby the above-mentioned variations in the plasma emission can be explained. The possibilities of making use of the discovered phenomena to enhance the observed EUV plasma brightness are discussed.

  9. Numerical Simulation Research on Laser Shock Forming of Thin Metal Sheet

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; YAO Zhen-qiang

    2007-01-01

    Laser shock forming (LSF) of sheet metal is a new technique realized by applying an impulsive pressure generated by laser-induced shock wave on the surface of metal sheet.LSF of brass sheet metal was investigated using a Q-switched Nd:YAG laser with an energy per pulse of 15~50 joules.ABAQUS software was used to simulate laser shock forming process.The central displacement of the shocked region is measured and compared with the simulation.The higher pulse energy, the higher central displacement of the shocked region were obtained.The deformation of the simulation matches the experiment quite well.

  10. Laser Irradiated Impact Experiments Show that Nanophase Iron Particles Formed by Shock-Induced Melting Rather than Vapor Deposition

    Science.gov (United States)

    Li, Y.; Li, S. J.; Xie, Z. D.; Li, X. Y.

    2016-08-01

    As the laser irradiated results of chondrite, Impact melting fractionation of ferromagnesian silicates induced by meteorites may be the major origin of np-Fe0, rather than vapour deposition origin only, especially for np-Fe0 in agglutinatic glasses.

  11. Soda-lime glass behavior under laser shock

    Science.gov (United States)

    Loison, D.; Guin, J.-P.; Sangleboeuf, J.-C.; Nivard, M.; Lescoute, E.; Sollier, A.; Seisson, G.; Hebert, D.; Berthe, L.; Boustie, M.

    2017-01-01

    Understanding and modeling the behavior of glass is an issue for certain aeronautical, military and civil applications. For example, parts of satellites and shuttles are made of glasses. During their lifetime, they are subjected to potentially damaging high velocity impacts. To determine the behavior of these structures during and after impact we used instrumented laser driven shock loading performed on high power intensity laser facilities. Transverse shadowgraphs of the front wave propagating inside the transparent material are collected at different times. These shadowgraphs provide information regarding the shock wave velocity. PDV or VISAR measurements provide time-resolved free surface velocity to determine material velocity when the shock wave breakout occurs. For some laser shots, shock wave corresponds to elastic wave then Hugoniot elastic limit may be determined. Under high pressure conditions glass permanently densifies and traces of such a plastic deformation are looked for on the path of the shock wave. Those experimental data are necessary to characterize the material behavior under such conditions and to model the mechanical behavior of glass structures. In this presentation we will present experimental results obtained for soda-lime silica glass samples loaded by laser induced shock.

  12. Laser Shock Processing of Metal Sheet and Welded Joints

    Institute of Scientific and Technical Information of China (English)

    ZOU Shi-kun; TAN Yong-sheng; ZHANG Xiao-bin; LIU Fang-jun

    2004-01-01

    In order to study the application of laser shock processing(LSP) as a post weld treatment technology and a strengthening technology, a series experiments and analysis were taken in this paper. The hardness of the laser shock processed zone of Al-Li alloy was measured, and the microstructure and mechanical properties of the welded joints of the Ni-based superalloy GH30 and the Austenitic stainless steel 1Cr18Ni9Ti were compared with those without LSP in this paper. The results showed that the size of strengthened zone was similar to that of laser spot and strengthened layer was about 1mm deep, and the high intense dislocations and twins produced in the shocked zone. Plastic strain also gained surface residual compress stress, which is benefit for the fatigue properties of welded zones. In this test, the surface hardness of welding zone of the superalloy GH30 improved obviously and tensile strength increased by 12%, but the improvement of fatigue life was not obvious; Martensite phase is formed in plasma welding 1Cr18Ni9Ti, which reduced the effect of strain deformation martensite induced by laser shock processing, but the surface residual compress stress gained by laser shock processing can obviously improve the fatigue life of 1Cr1 8Ni9Ti welded joints.

  13. Laser Shock Processing of Metal Sheet and Welded Joints

    Institute of Scientific and Technical Information of China (English)

    ZOUShi-kun; TANYong-sheng; ZHANGXiao-bin; LIUFang-jun

    2004-01-01

    In order to study the application of laser shock processing(LSP) as a post weld treatment technology and a strengthening technology, a series experiments and analysis were taken in this paper. The hardness of the laser shock processed zone of A1-Li alloy was measured, and the microstructure and mechanical properties of the welded joints of the Ni-based superalloy GH30 and the Austenitic stainless steel 1Crl8Ni9Ti were compared with those without LSP in this paper. The results showed that the size of strengthened zone was similar to that of laser spot and strengthened layer was about lmm deep, and the high intense dislocations and twins produced in the shocked zone. Plastic strain also gained surface residual compress stress, which is benefit for the fatigue properties of welded zones. In this test, the surface hardness of welding zone of the superalloy GH30 improved obviously and tensile strength increased by 12%, but the improvement of fatigue life was not obvious; Martensite phase is formed in plasma welding 1Crl8Ni9Ti, which reduced the effect of strain deformation martensite induced by laser shock processing, but the surface residual compress stress gained by laser shock processing can obviously improve the fatigue life of 1Crl 8Ni9Ti welded joints.

  14. Laser Shock Processing of Surface Copperize on Arc-Meshes Gear

    Institute of Scientific and Technical Information of China (English)

    马德毅; 刘继光; 宋丹路

    2004-01-01

    This paper presents surface modifications of aluminum-alloy induced by laser-shock processing (LSP). In the first part, the basic principles are discussed to provide an overview of the physical processes involved in laser shock processing, and to introduce pressure loadings generated by different laser generators. In the second part, emphases are given to the effects of laser intensity, target material, laser pulse duration and laser wavelength, and uniform and localized modeling of fatigue behavior after LSP. In the third part,experimental results are given to show the laser-induced pure mechanical effects on aluminum-alloy by using LSP.

  15. Characterization of Fuel-Cladding Bond Strength Using Laser Shock

    Energy Technology Data Exchange (ETDEWEB)

    James A. Smith; David L. Cottle; Barry H. Rabin

    2014-04-01

    This paper describes new laser-based capabilities for characterization of fuel-cladding bond strength in nuclear fuels, and presents preliminary results obtained from studies on as-fabricated monolithic fuel consisting of uranium-10 wt.% molybdenum alloys clad in 6061 aluminum by hot isostatic pressing. Two complementary experimental methods are employed, laser-shock testing and laser-ultrasonic imaging. Measurements are spatially localized, non-contacting and require minimum specimen preparation, and are therefore ideally suited for applications involving radioactive materials, including irradiated materials. The theoretical principles and experimental approaches employed in characterization of nuclear fuel plates are described. The ability to measure layer thicknesses, elastic properties of the constituents, and the location and nature of laser-shock induced debonds is demonstrated, and preliminary bond strength measurement results are discussed.

  16. Advances in Microscale Laser Shock Peening

    Institute of Scientific and Technical Information of China (English)

    CHEN Hongqiang; WANG Youneng; KYSAR Jeffrey W.; YAO Y.Lawrence

    2004-01-01

    The response of materials after microscale laser shock peening (μLSP) was experimentally characterized and compared with the theoretical prediction from the finite element method (FEM) analysis in microlength level. X-ray micro-diffraction technique was applied to the post-peened single crystal aluminum of (001) and (110) orientations, and X-ray profile was analyzed by sub-profiling and Fourier analysis method. Spatially resolved residual stress and strain deviation was quantified and explained in terms of the heterogeneous dislocation cell structure. In-plane crystal lattice rotation induced by μLSP was measured by electron backscatter diffraction (EBSD) and compared with the FEM simulation. Average mosaic size was evaluated from X-ray profile Fourier analysis and compared with the result from EBSD. Surface strength increase and dislocation cell structure formation were studied. The systematical characterization will lay the ground work for better understanding the effect of μLSP in microlength level and developing more realistic simulations.

  17. Real-time optical diagnosis of the rat brain exposed to a laser-induced shock wave: observation of spreading depolarization, vasoconstriction and hypoxemia-oligemia.

    Directory of Open Access Journals (Sweden)

    Shunichi Sato

    Full Text Available Despite many efforts, the pathophysiology and mechanism of blast-induced traumatic brain injury (bTBI have not yet been elucidated, partially due to the difficulty of real-time diagnosis and extremely complex factors determining the outcome. In this study, we topically applied a laser-induced shock wave (LISW to the rat brain through the skull, for which real-time measurements of optical diffuse reflectance and electroencephalogram (EEG were performed. Even under conditions showing no clear changes in systemic physiological parameters, the brain showed a drastic light scattering change accompanied by EEG suppression, which indicated the occurrence of spreading depression, long-lasting hypoxemia and signal change indicating mitochondrial energy impairment. Under the standard LISW conditions examined, hemorrhage and contusion were not apparent in the cortex. To investigate events associated with spreading depression, measurement of direct current (DC potential, light scattering imaging and stereomicroscopic observation of blood vessels were also conducted for the brain. After LISW application, we observed a distinct negative shift in the DC potential, which temporally coincided with the transit of a light scattering wave, showing the occurrence of spreading depolarization and concomitant change in light scattering. Blood vessels in the brain surface initially showed vasodilatation for 3-4 min, which was followed by long-lasting vasoconstriction, corresponding to hypoxemia. Computer simulation based on the inverse Monte Carlo method showed that hemoglobin oxygen saturation declined to as low as ∼35% in the long-term hypoxemic phase. Overall, we found that topical application of a shock wave to the brain caused spreading depolarization/depression and prolonged severe hypoxemia-oligemia, which might lead to pathological conditions in the brain. Although further study is needed, our findings suggest that spreading depolarization/depression is one of

  18. Analysis and experiment on deformation of sheet metal by laser shock wave

    Institute of Scientific and Technical Information of China (English)

    YANG Chao-jun; ZHANG Yong-kang; ZHOU Jian-zhong; NI Ming-xiong; DU Jian-jun; HUANG Shu; FENG Ai-xin; ZHANG Lei-hong

    2006-01-01

    The mechanism of laser shock deformation and the reason for the production of the shockwave are introduced.An evaluation formula of the detonation wave pressure in the system of laser,energy transferring-medium and sheet metal is built according to the theory of detonation wave and blasting gas-dynamics.The minimal energy of the laser pulse is evaluated on the basis of the formula of the laser shock pressure and evaluation of dynamic yielding strength.The experiment is also validated.The result shows that the quantity of sheet metal deforming is nonlinearly increased with laser energy,i.e.,pressure of the laser shock wave.Under a laser-induced ultra-high pressure and high strain rate,structural steels and composite materials undergo plastic deformation.

  19. Measurement of dynamic characteristics of metal sheet under laser shock

    Institute of Scientific and Technical Information of China (English)

    Hongbing Yao; Zhusheng Zhou; Bo Xing; Guilin Ding; Yanqun Tong; Jie Ping; Liangwan Li; Yongkang Zhang

    2012-01-01

    A new approach is developed to measure the dynamic characteristics of metal sheet under laser shock,including deformation velocity,strain,and strain rate.The detecting laser beam is partially shaded by the target deformation induced by the laser action.A photodiode transforms the received beam intensity real time into an electrical signal which could record the process of the target deformation.The functional relation between the electrical signal and the deformation of the metal sheet is derived.The deformation curve of a thin aluminum and the velocity curve of its deformation are also obtained during the experiment.The results indicate that the average velocity of the elastic deformation of the target can reach 2.999×103 m/s in the central area.This new method provides an approach in the study of the effect of strain rate on deformation.

  20. Shock-induced chemistry in organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve [Los Alamos National Laboratory; Engelke, Ray [Los Alamos National Laboratory; Manner, Virginia [Los Alamos National Laboratory; Chellappa, Raja [Los Alamos National Laboratory; Yoo, Choong - Shik [WASHINGTON STATE UNIV

    2011-01-20

    The combined 'extreme' environments of high pressure, temperature, and strain rates, encountered under shock loading, offer enormous potential for the discovery of new paradigms in chemical reactivity not possible under more benign conditions. All organic materials are expected to react under these conditions, yet we currently understand very little about the first bond-breaking steps behind the shock front, such as in the shock initiation of explosives, or shock-induced reactivity of other relevant materials. Here, I will present recent experimental results of shock-induced chemistry in a variety of organic materials under sustained shock conditions. A comparison between the reactivity of different structures is given, and a perspective on the kinetics of reaction completion under shock drives.

  1. Diffusive shock acceleration at laser driven shocks: studying cosmic-ray accelerators in the laboratory

    CERN Document Server

    Reville, B; Gregori, G

    2012-01-01

    The non-thermal particle spectra responsible for the emission from many astrophysical systems are thought to originate from shocks via a first order Fermi process otherwise known as diffusive shock acceleration. The same mechanism is also widely believed to be responsible for the production of high energy cosmic rays. With the growing interest in collisionless shock physics in laser produced plasmas, the possibility of reproducing and detecting shock acceleration in controlled laboratory experiments should be considered. The various experimental constraints that must be satisfied are reviewed. It is demonstrated that several currently operating laser facilities may fulfil the necessary criteria to confirm the occurrence of diffusive shock acceleration of electrons at laser produced shocks. Successful reproduction of Fermi acceleration in the laboratory could open a range of possibilities, providing insight into the complex plasma processes that occur near astrophysical sources of cosmic rays.

  2. Benjamin Franklin and Shock-Induced Amnesia

    Science.gov (United States)

    Finger, Stanley; Zaromb, Franklin

    2006-01-01

    Shock-induced amnesia received considerable attention after Cerletti popularized electroconvulsive shock therapy in the late 1930s. Yet, often overlooked is the fact that Benjamin Franklin recognized that passing electricity through the head could affect memory for the traumatic event. Franklin described his findings on himself and others in…

  3. Ultrafast dynamic ellipsometry and spectroscopies of laser shocked materials

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrane, Shawn David [Los Alamos National Laboratory; Bolme, Cindy B [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

    2010-01-01

    Ultrafast ellipsometry and transient absorption spectroscopies are used to measure material dynamics under extreme conditions of temperature, pressure, and volumetric compression induced by shock wave loading with a chirped, spectrally clipped shock drive pulse.

  4. Shock propagation and attenuation in high-power excimer lasers

    Science.gov (United States)

    Holzwarth, Achim; Berger, Peter; Huegel, Helmut

    1993-05-01

    Theoretical and experimental investigations on the propagation, reflection, and attenuation of shock waves as they occur in excimer lasers have been performed. The numerical simulations have been carried out using a two-dimensional, unsteady finite difference scheme. The experimental setup is a piston driven shock tube with a rectangular cross section working in air at atmospheric pressure. The shocks were detected interferometrically as well as by means of pressure transducers. This shock tube allows us to investigate basic phenomena of shock diffraction which can be used to confirm the computational results in the range of weak shock waves. In particular, the influence of the shape of the wall contour on the reflection of shock waves has been investigated theoretically. The decay time of pressure and density perturbations differs for various wall configurations in such a way that short electrodes accelerate the attenuation as well as does a strong area increase in the vicinity of them. After each laser pulse there is a shock travelling into the laser channel. Experiments have been carried out on the reflection of this shock at a specially formed bend that is able to focus the shock into a muffling element.

  5. Experimental Analysis of Microscale Laser Shock Processing on Metallic Material Using Excimer Laser

    Institute of Scientific and Technical Information of China (English)

    Zhigang Che; Liangcai Xiong; Tielin Shi; Huayang Cheng; Likun Yang

    2009-01-01

    Microscale laser shock processing (μLSP), also known as laser shock processing in microscale, is a technique that uses microscale focused laser beam to induce high pressure plasma and generates plastic deformation and compressive residual stress in target materials, thus improves fatigue or stress corrosion cracking resistance of MEMS (Micro Electromechanical Systems) devices made of such a material. Many works have been reported about the research and experiment for μLSP. But the diameters of 50-200 μm were used at the first time for this field, which was useful for treating micro-device components with larger area and curved surface. The excimer laser was used firstly on μLSP for shorter wavelength than that of used in previous researches. The determination method of laser spot size at micro-level spatial resolution was presented. Under these conditions, plastic deformation, the stress analysis and microhardness with different pulse number, pulse energy and pulse spacing were investigated. Especially the residual stress distribution with depth treated by μLSP, was first investigated. Experiment results showed that the material performance was improved remarkably after μLSP.

  6. Central residual compressive stress drop on metal materials after laser induced shock wave%激光冲击波加载金属材料中心压应力缺失效应

    Institute of Scientific and Technical Information of China (English)

    王波; 陈东林; 周留成; 何卫锋

    2014-01-01

    纳秒脉冲、千兆瓦级激光辐照金属材料产生高压等离子体冲击波,作用于金属材料表面并向内传播,产生残余压应力场。但在单次冲击加载时,残余压应力场中心出现的残余压应力值小于加载边缘,应用理论分析和实验测试的方法解释了这一过程,并结合激光诱导冲击波Fabbro方程和TC4钛合金动态响应模型,建立了不同形式冲击波加载TC4钛合金的数值仿真模型,分析了冲击波压力、作用时间和加载形式对中心压应力缺失的影响。%The high pressure plasma shock wave induced by nanosecond pulse and 1 000 MW laser irradiation on the metal materials will propagate into the materials and impart residual compressive stresses. But when shock wave was singly loaded, the lower residual stress at the center of the loading zone compared to those away from the center will be induced. This process is proved by theorems and experiments. Moreover, the Fabbro equation of plasma shock wave and dynamic response of TC4 titanium alloy was calculated in the numerical model of different shock wave loading, the influence of the shock wave pressure, the actuation duration and the loading shape on residual stress drop at the center was discussed.

  7. Shock-induced devolatilization of calcite

    Science.gov (United States)

    Boslough, M. B.; Ahrens, T. J.; Vizgirda, J.; Becker, R. H.; Epstein, S.

    1982-01-01

    Experimental measurements of the release adiabats by Vizgirda (1981) indicate that substantial vaporization takes place upon release from shock pressures of 37 GPa for calcite and 14 GPa for aragonite. The present investigation includes the first controlled partial vaporization experiments on calcite. The experiments were conducted to test the predictions of the release adiabat experiments. The quantities of the gaseous species produced from shocked calcite and their carbon and oxygen isotopic compositions were determined, and the shock-induced effect on the Mn(2+) electron spin resonance spectrum in the shock-recovered calcite was observed. On the basis of the obtained results, it is concluded that shock stresses at the 17-18 GPa level give rise to volatilization of 0.03-0.3 (mole) percent of calcite to CO2 and CO. The devolatilization of calcite occurs at low pressure at significantly lower entropy densities than predicted on the basis of thermodynamic continuum models.

  8. Synergistic skin heat shock protein expression in response to combined laser treatment with a diode laser and ablative fractional lasers.

    Science.gov (United States)

    Paasch, Uwe; Sonja, Grunewald; Haedersdal, Merete

    2014-06-01

    Diode laser-based skin heating has been shown to minimise scars by interfering with wound healing responses through the induction of heat shock proteins (HSP). HSP are also induced after ablative fractional laser (AFXL) wound healing. AFXL itself is highly recommended for scar treatment. Therefore, the sequential combination of both modalities may produce superior outcomes. The aim of this study was to examine the pretreatment effects of a diode laser before AFXL on wound healing responses in terms of HSP up-regulation in an in vitro model. Immediate responses and responses on days 1, 3 or 6 post-procedure were studied in an in vitro porcine skin model (n = 240). Untreated samples served as control. Immunohistochemical investigation (Hsp70) was performed in all untreated controls, diode laser-, AFXL-, and in diode laser + AFXL-treated samples. Hsp70 was shown to be up-regulated by all interventions between days 1 and 6 after interventions. The largest effect was caused by the combination of a diode laser and an AFXL procedure. Diode laser exposure induces a skin HSP response that can be further enhanced by sequential AFXL treatment. Clinical studies are necessary to investigate the dose response of HSP on scar formation and refine suitable laser exposure settings.

  9. Laser-shocked energetic materials with metal additives: evaluation of chemistry and detonation performance.

    Science.gov (United States)

    Gottfried, Jennifer L; Bukowski, Eric J

    2017-01-20

    A focused, nanosecond-pulsed laser has been used to ablate, atomize, ionize, and excite milligram quantities of metal-doped energetic materials that undergo exothermic reactions in the laser-induced plasma. The subsequent shock wave expansion in the air above the sample has been monitored using high-speed schlieren imaging in a recently developed technique, laser-induced air shock from energetic materials (LASEM). The method enables the estimation of detonation velocities based on the measured laser-induced air-shock velocities and has previously been demonstrated for organic military explosives. Here, the LASEM technique has been extended to explosive formulations with metal additives. A comparison of the measured laser-induced air-shock velocities for TNT, RDX, DNTF, and LLM-172 doped with Al or B to the detonation velocities predicted by the thermochemical code CHEETAH for inert or active metal participation demonstrates that LASEM has potential for predicting the early time (<10  μs) participation of metal additives in detonation events. The LASEM results show that while Al is mostly inert at early times in the detonation event (confirmed from large-scale detonation testing), B is active-and reducing the amount of hydrogen present during the early chemical reactions increases the resulting estimated detonation velocities.

  10. Experimental study on laser shock processing of brass

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Laser shock processing (LSP) is a new surface treatment technique for improving hardness, wear resistance, and fatigue.In this paper, basic theories were introduced and the influence of laser pulse intensity on the laser shock processing of brass specimens was investigated by experiments. Microhardness, roughness, microstructure, wear resistance, friction coefficient evolution, and residual stress were examined with different laser pulse intensities of LSP. The results show that the microhardness increases after LSP treatment, and the higher the pulse intensity, the higher the microhardness. Though the microstructure shows no remarkable change, the roughness and wear resistance increase with the increase in pulse density. Laser shock processing has great potential as a means to improve the mechanical properties of components.

  11. Study of mechanism of strengthening materials with laser shock processing

    Institute of Scientific and Technical Information of China (English)

    郭大浩; 吴鸿兴; 王声波; 洪昕; 王劼; 戴宇生; 夏小平; 张永康; 张宏; 唐亚新; 余承业

    1999-01-01

    The material of surface layer absorbs the energy of laser and produces plasma, when the high power laser radiates the surface of material. The plasma blows up and produces an intense shock wave. When the surface of material is covered with a confining medium and an absorptive coating layer, the shock wave can be strengthened greatly. There-fore a huge momentum is exerted on the surface of material. There is a plastic deformation layer in the material when the shock stress exceeds the dynamic yield strength of material. Due to the residual compressive stress, the high density of dislocation in the plastic layer, the anti-fatigue life of material is prolonged.

  12. Electron Weibel Instability Mediated Laser Driven Electromagnetic Collisionless Shock

    Science.gov (United States)

    Jia, Qing; Mima, Kunioki; Cai, Hong-Bo; Taguchi, Toshihiro; Nagatomo, Hideo; He, X. T.

    2015-11-01

    As a fundamental nonlinear structure, collisionless shock is widely studied in astrophysics. Recently, the rapidly-developing laser technology provides a good test-bed to study such shock physics in laboratory. In addition, the laser driven shock ion acceleration is also interested due to its potential applications. We explore the effect of external parallel magnetic field on the collisionless shock formation and resultant particle acceleration by using the 2D3V PIC simulations. We show that unlike the electrostatic shock generated in the unmagnetized plasma, the shock generated in the weakly-magnetized laser-driven plasma is mostly electromagnetic (EM)-like with higher Mach number. The generation mechanism is due to the stronger transverse magnetic field self-generated at the nonlinear stage of the electron Weibel instability which drastically scatters particles and leads to higher energy dissipation. Simulation results also suggest more ions are reflected by this EM shock and results in larger energy transfer rate from the laser to ions, which is of advantage for applications such as neutron production and ion fast ignition.

  13. Shock-induced mixing of nonhomogeneous density turbulent jets

    Science.gov (United States)

    Hermanson, J. C.; Cetegen, B. M.

    2000-05-01

    An experimental study of the mixing enhancement and changes in flow structure arising from the interaction of weak normal shock waves with turbulent jets was conducted. The experimental configuration was an axisymmetric jet processed by weak normal shock waves propagating in a shock tube along the jet axis. Experiments involved three different jet gases: helium, air, and carbon dioxide, each in a coflowing air stream, with nominal jet fluid to ambient density ratios of 0.14, 1.00, and 1.52, respectively. The jet local Reynolds number was Reδ≈25 000 and the nominal oncoming shock Mach numbers were 1.23 and 1.45. Planar laser Mie light scattering from mineral oil smoke was utilized for flow visualization and for obtaining jet fluid concentration distributions across diametric planes of jets. Analysis of the spatial probability density function (pdf) of jet fluid concentration indicates that the average helium jet fluid concentration levels decrease and become more uniform in the regions processed by the shock waves. The degree of mixing enhancement increases with increasing shock strength, and amounts to nearly 30% for the stronger shock (M=1.45). The passage of a shock through low-density (helium) jets induces the formation of a flow structure that resembles a large-scale, toroidal vortex. The air and carbon dioxide jets exhibit neither a vortex-like structure or a significant change in mixing upon shock passage, unlike the helium jets. A comparison of the results for the helium and carbon dioxide jets indicates that the reversal of the density ratio between the jet and the surroundings, and the consequent change in the sign of baroclinic vorticity does not yield similar effects in terms of flow structure or mixing enhancement. The average concentration behind the shock wave decreases for both air and helium jets with increasing distance behind the shock. These features are explained qualitatively in terms of a simple characteristic time scale argument. The

  14. Mechanical analysis of a heat-shock induced developmental defect

    Science.gov (United States)

    Crews, Sarah M.; McCleery, W. Tyler; Hutson, M. Shane

    2014-03-01

    Embryonic development in Drosophila is a complex process involving coordinated movements of mechanically interacting tissues. Perturbing this system with a transient heat shock can result in a number of developmental defects. In particular, a heat shock applied during the earliest morphogenetic movements of gastrulation can lead to apparent recovery, but then subsequent morphogenetic failure 5-6 hours later during germ band retraction. The process of germ band retraction requires an intact amnioserosa - a single layered extra-embryonic epithelial tissue - and heat shock at gastrulation can induce the later opening of holes in the amnioserosa. These holes are highly correlated with failures of germ band retraction. These holes could be caused by a combination of mechanical weakness in the amnioserosa or local increases in mechanical stress. Here, we assess the role of mechanical stress using confocal imaging to compare cell and tissue morphology in the amnioserosa of normal and heat-shocked embryos and laser hole drilling to map the stress field around the times and locations at which heat-shock induced holes open.

  15. Laser induced nuclear reactions

    Science.gov (United States)

    Ledingham, Ken; McCanny, Tom; Graham, Paul; Fang, Xiao; Singhal, Ravi; Magill, Joe; Creswell, Alan; Sanderson, David; Allott, Ric; Neely, David; Norreys, Peter; Santala, Marko; Zepf, Matthew; Watts, Ian; Clark, Eugene; Krushelnick, Karl; Tatarakis, Michael; Dangor, Bucker; Machecek, Antonin; Wark, Justin

    1998-12-01

    Dramatic improvements in laser technology since 1984 have revolutionised high power laser technology. Application of chirped-pulse amplification techniques has resulted in laser intensities in excess of 1019W/cm2. In the mid to late eighties, C. K. Rhodes and K. Boyer discussed the possibility of shining laser light of this intensity onto solid surfaces and to cause nuclear transitions. In particular, irradiation of a uranium target could induce electro- and photofission in the focal region of the laser. In this paper it is shown that μCi of 62Cu can be generated via the (γ,n) reaction by a laser with an intensity of about 1019Wcm-2.

  16. Laser-shocked energetic materials with metal additives: evaluation of detonation performance

    Science.gov (United States)

    Gottfried, Jennifer; Bukowski, Eric

    A focused, nanosecond-pulsed laser with sufficient energy to exceed the breakdown threshold of a material generates a laser-induced plasma with high peak temperatures, pressures, and shock velocities. Depending on the laser parameters and material properties, nanograms to micrograms of material is ablated, atomized, ionized and excited in the laser-induced plasma. The subsequent shock wave expansion into the air above the sample has been monitored using high-speed schlieren imaging in a recently developed technique, laser-induced air shock from energetic materials (LASEM). The estimated detonation velocities using LASEM agree well with published experimental values. A comparison of the measured shock velocities for various energetic materials including RDX, DNTF, and LLM-172 doped with Al or B to the detonation velocities predicted by CHEETAH for inert or active metal participation demonstrates that LASEM has potential for predicting the early time participation of metal additives in detonation events. The LASEM results show that reducing the amount of hydrogen present in B formulations increases the resulting detonation velocities

  17. EXPERIMENTAL RESEARCH AND NUMERICAL SIMULATION OF LASER SHOCK FORMING OF TA2 TITANIUM SHEET

    Institute of Scientific and Technical Information of China (English)

    F. Wang; Z.Q. Yao; J. Hu; Q.L. Deng

    2006-01-01

    Laser shock forming (LSF) was a new technique realized by applying an impulsive pressure generated by laser-induced shock wave on the surface of metal sheet. LSF of metal sheet was investigated with experiments and numerical simulation. The basic theories were introduced; the surface quality and deformation of the processed titanium sample (TA2) were examined; ABAQUS was used to sinulate LSF and the central displacement of the shocked region was measured and compared with the simulation. Overlapped LSF treatment was experimentally carried out to produce groove and simulation. The results showed that the surface quality and the microstructure with single laser pulse had no remarkable change, and ablation was observed on the surface of the sample with overlapped pulses. The deformation observed in the numerical simulation agreeed with that observed in the experimental measurement quite well.

  18. Comparison of warm laser shock peening and laser shock peening techniques in lengthening the fatigue life of welded joints made of aluminum alloy

    Science.gov (United States)

    Su, Chun; Zhou, Jianzhong; Meng, Xiankai; Sheng, Jie

    2017-07-01

    Welded joints made of 6061-T6 Al alloy were studied to evaluate warm laser shock peening (WLSP) and laser shock peening (LSP) processes. The estimation model of laser-induced surface residual stress was examined by means of experiments and numerical analysis. The high-cycle fatigue lives of welded joint specimens treated with WLSP and LSP were estimated by conducting tensile fatigue tests. The fatigue fracture mechanisms of these specimens are studied by surface integrity and fracture surface tests. Experimental results and analysis indicated that the fatigue life of the specimens processed by WLSP was higher than that with LSP. The large increase in fatigue life appeared to be the result of the larger residual stress, more uniform microstructure refinement and the lower surface roughness of the WLSP specimens.

  19. High-power laser experiments to study collisionless shock generation

    Science.gov (United States)

    Sakawa, Y.; Kuramitsu, Y.; Morita, T.; Kato, T.; Tanji, H.; Ide, T.; Nishio, K.; Kuwada, M.; Tsubouchi, T.; Ide, H.; Norimatsu, T.; Gregory, C.; Woolsey, N.; Schaar, K.; Murphy, C.; Gregori, G.; Diziere, A.; Pelka, A.; Koenig, M.; Wang, S.; Dong, Q.; Li, Y.; Park, H.-S.; Ross, S.; Kugland, N.; Ryutov, D.; Remington, B.; Spitkovsky, A.; Froula, D.; Takabe, H.

    2013-11-01

    A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008)]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

  20. High-power laser experiments to study collisionless shock generation

    Directory of Open Access Journals (Sweden)

    Sakawa Y.

    2013-11-01

    Full Text Available A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

  1. Shock induced crystallization of amorphous Nickel powders

    Science.gov (United States)

    Cherukara, Mathew; Strachan, Alejandro

    2015-06-01

    Recent experimental work has shown the efficacy of amorphous Ni/crystalline Al composites as energetic materials, with flame velocities twice that of a comparable crystalline Ni/crystalline Al system. Of further interest is the recrystallization mechanisms in the pure amorphous Ni powders, both thermally induced and mechanically induced. We present large-scale molecular dynamics simulations of shock-induced recrystallization in loosely packed amorphous Nickel powders. We study the time dependent nucleation and growth processes by holding the shocked samples at the induced pressures and temperatures for extended periods following the passage of the shock (up to 6 ns). We find that the nanostructure of the recrystallized Ni and time scales of recrystallization are dependent on the piston velocity. At low piston velocities, nucleation events are rare, leading to long incubation times and a relatively coarse nanostructure. At higher piston velocities, local variations in temperature due to jetting phenomena and void collapse, give rise to multiple nucleation events on time scales comparable to the passage of the shock wave, leading to the formation of a fine-grained nanostructure. Interestingly, we observe that the nucleation and growth process occurs in two steps, with the first nuclei crystallizing into the BCC structure, before evolving over time into the expected FCC structure. U.S. Defense Threat Reduction Agency, HDTRA1-10-1-0119 (Program Manager Suhithi Peiris).

  2. Biophoton emission induced by heat shock.

    Directory of Open Access Journals (Sweden)

    Katsuhiro Kobayashi

    Full Text Available Ultraweak biophoton emission originates from the generation of reactive oxygen species (ROS that are produced in mitochondria as by-products of cellular respiration. In healthy cells, the concentration of ROS is minimized by a system of biological antioxidants. However, heat shock changes the equilibrium between oxidative stress and antioxidant activity, that is, a rapid rise in temperature induces biophoton emission from ROS. Although the rate and intensity of biophoton emission was observed to increase in response to elevated temperatures, pretreatment at lower high temperatures inhibited photon emission at higher temperatures. Biophoton measurements are useful for observing and evaluating heat shock.

  3. Study of spallation by sub-picosecond laser driven shocks in metals

    Directory of Open Access Journals (Sweden)

    Combis P.

    2011-01-01

    Full Text Available Spallation induced by a laser driven shock has been studied for two decades on time scales of nanosecond order. The evolution of laser technologies now provides access to sources whose pulse duration is under the picosecond, corresponding to characteristic times of numerous microscopic phenomena. In this ultra-short irradiation regime, spallation experiments have been performed with time-resolved measurements of the free surface. In this solicitation type, damage occurs at small scale, leading to micrometric spalls. The VISAR measurements have been complemented with post-test observations and microtomography and compared with numerical simulations to check the models consistency of the laser-matter interaction, shock wave propagation and the dynamic damage criteria ability to reproduce spallation at this ultra-short time scale, inducing strong tensile stress states at very high strain rates.

  4. Counter-streaming radiative shock experiments on the Orion laser

    Science.gov (United States)

    Suzuki-Vidal, F.; Clayson, T.; Swadling, G. F.; Patankar, S.; Burdiak, G. C.; Lebedev, S. V.; Smith, R. A.; Stehle, C.; Chaulagain, U.; Singh, R. L.; Larour, J.; Kozlova, M.; Spindloe, C.; Foster, J.; Skidmore, J.; Gumbrell, E.; Graham, P.; Danson, C.

    2016-10-01

    The formation of radiative shocks, shocks in which the structure of density and temperature is affected by radiation from the shock-heated matter, is ubiquitous in many astrophysical scenarios. Experiments were performed at the Orion laser using a new target configuration that allows studying the formation of single and counter-streaming radiative shocks in gas-filled targets (Ne, Ar, Kr, Xe), with initial pressures 0.1-1 bar and a driver intensity of 6x1014 W/cm2 . The shocks propagate at velocities >60 km/s and were diagnosed with optical interferometry (streaked and time-resolved) and point-projection X-ray backlighting allowing to probe simultaneously the pre-shock radiative precursor and the shock front itself. Besides varying the extent of the radiative precursor the results show that different gases seem to have an effect on the shock front as evidenced by a number of spatial features. The results are compared with radiative hydrodynamics simulations in 1-D (HELIOS) and 2-D (NYM/PETRA). Supported by Orion Academic Access, the Royal Society, EPSRC, Labex PLAS@PAR. Currently at (2) LLNL, USA, (3) ELI, CZ, (4) First Light Fusion, UK.

  5. Laser shocking of 2024 and 7075 aluminum alloys

    Science.gov (United States)

    Clauer, A. H.; Fairand, B. P.; Slater, J. E.

    1977-01-01

    The effect of laser generated stress waves on the microstructure, hardness, strength and stress corrosion resistance of 2024 and 7075 aluminum alloys was investigated. Pulsed CO2 and neodymium-glass lasers were used to determine the effect of wavelength and pulse duration on pressure generation and material property changes. No changes in material properties were observed with CO2 laser. The strength and hardness of 2024-T351 and the strength of 7075-T73 aluminum alloys were substantially improved by the stress wave environments generated with the neodymium-glass laser. The mechanical properties of 2024-T851 and 7075-T651 were unchanged by the laser treatment. The correlation of the laser shock data with published results of flyer plate experiments demonstrated that a threshold pressure needed to be exceeded before strengthening and hardening could occur. Peak pressures generated by the pulsed laser source were less than 7.0 GPa which was below the threshold pressure required to change the mechanical properties of 2024-T851 and 7075-T651. Corrosion studies indicated that laser shocking increased the resistance to local attack in 2024-T351 and 7075-T651.

  6. Investigation of Laser Shock Processing. Volume 2

    Science.gov (United States)

    1980-08-01

    added to the original test plan during the course of the program. Specimens 20A and 21A were so designated to avoid duplication of numbers in test...from interaction of the laser beam with the target. . zoe Produccion Ozone is produced whenever flashlamps, which are used to pump the laser medium

  7. The behavior of iron under ultrafast shock loading driven by a femtosecond laser

    Science.gov (United States)

    Ashitkov, S. I.; Zhakhovsky, V. V.; Inogamov, N. A.; Komarov, P. S.; Agranat, M. B.; Kanel, G. I.

    2017-01-01

    The results of experimental and theoretical investigations of shock-wave propagation in bcc iron under ultra-short loads driven by femtosecond laser pulses are presented. Chirped pulse interferometry was used for continuous diagnostics of movement in a picosecond range of the rear-side surface of thin iron films. The evolution of ultra-short elastic-plastic shock waves in samples with different thicknesses and purity has been studied. The obtained HEL and spall strength are close to ultimate values of shear and tensile stresses. Response of single-crystal iron to ultra-short shock loading/unloading was also explored in micron-sized films by molecular dynamics simulations. The experimental and simulation results on shock-induced elastic-plastic transformation and phase transition from bcc to hcp iron in a picosecond range of loading are discussed.

  8. Directional amorphization of boron carbide subjected to laser shock compression

    Science.gov (United States)

    Zhao, Shiteng; Kad, Bimal; Remington, Bruce A.; LaSalvia, Jerry C.; Wehrenberg, Christopher E.; Behler, Kristopher D.; Meyers, Marc A.

    2016-10-01

    Solid-state shock-wave propagation is strongly nonequilibrium in nature and hence rate dependent. Using high-power pulsed-laser-driven shock compression, unprecedented high strain rates can be achieved; here we report the directional amorphization in boron carbide polycrystals. At a shock pressure of 45˜50 GPa, multiple planar faults, slightly deviated from maximum shear direction, occur a few hundred nanometers below the shock surface. High-resolution transmission electron microscopy reveals that these planar faults are precursors of directional amorphization. It is proposed that the shear stresses cause the amorphization and that pressure assists the process by ensuring the integrity of the specimen. Thermal energy conversion calculations including heat transfer suggest that amorphization is a solid-state process. Such a phenomenon has significant effect on the ballistic performance of B4C.

  9. Effects of laser polarizations on shock generation and shock ion acceleration in overdense plasmas

    Science.gov (United States)

    Kim, Young-Kuk; Kang, Teyoun; Jung, Moon Youn; Hur, Min Sup

    2016-09-01

    The effects of laser-pulse polarization on the generation of an electrostatic shock in an overdense plasma were investigated using particle-in-cell simulations. We found, from one-dimensional simulations, that total and average energies of reflected ions from a circular polarization- (CP) driven shock front are a few times higher than those from a linear polarization- (LP) driven one for a given pulse energy. Moreover, it was discovered that the pulse transmittance is the single dominant factor for determining the CP-shock formation, while the LP shock is affected by the plasma scale length as well as the transmittance. In two-dimensional simulations, it is observed that the transverse instability, such as Weibel-like instability, can be suppressed more efficiently by CP pulses.

  10. Collisionless electrostatic shock formation and ion acceleration in intense laser interactions with near critical density plasmas

    CERN Document Server

    Liu, M; Li, Y T; Yuan, D W; Chen, M; Mulser, P; Sheng, Z M; Murakami, M; Yu, L L; Zheng, X L; Zhang, J

    2016-01-01

    Laser-driven collisonless electrostatic shock formation and the subsequent ion acceleration have been studied in near critical density plasmas. Particle-in-cell simulations show that both the speed of laser-driven collisionless electrostatic shock and the energies of shock-accelerated ions can be greatly enhanced due to fast laser propagation in near critical density plasmas. However, a response time longer than tens of laser wave cycles is required before the shock formation in a near critical density plasma, in contrast to the quick shock formation in a highly overdense target. More important, we find that some ions can be reflected by the collisionless shock even if the electrostatic potential jump across the shock is smaller than the ion kinetic energy in the shock frame, which seems against the conventional ion-reflection condition. These anomalous ion reflections are attributed to the strongly time-oscillating electric field accompanying laser-driven collisionless shock in a near critical density plasma...

  11. Material measurement method based on femtosecond laser plasma shock wave

    Science.gov (United States)

    Zhong, Dong; Li, Zhongming

    2017-03-01

    The acoustic emission signal of laser plasma shock wave, which comes into being when femtosecond laser ablates pure Cu, Fe, and Al target material, has been detected by using the fiber Fabry-Perot (F-P) acoustic emission sensing probe. The spectrum characters of the acoustic emission signals for three kinds of materials have been analyzed and studied by using Fourier transform. The results show that the frequencies of the acoustic emission signals detected from the three kinds of materials are different. Meanwhile, the frequencies are almost identical for the same materials under different ablation energies and detection ranges. Certainly, the amplitudes of the spectral character of the three materials show a fixed pattern. The experimental results and methods suggest a potential application of the plasma shock wave on-line measurement based on the femtosecond laser ablating target by using the fiber F-P acoustic emission sensor probe.

  12. Investigation of surface acoustic waves in laser shock peened metals

    Institute of Scientific and Technical Information of China (English)

    Ling Yuan; Gang Yan; Zhonghua Shen; Hangwei Xu; Xiaowu Ni; Jian Lu

    2008-01-01

    Laser shock peening is a well-known method for extending the fatigue life of metal components by introducing near-surface compressive residual stress. The surface acoustic waves (SAWs) are dispersive when the near-surface properties of materials are changed. So the near-surface properties (such as the thickness of hardened layers, elastic properties, residual stresses, etc.) can be analyzed by the phase velocity dispersion. To study the propagation of SAWs in metal samples after peening, a more reasonable experimental method of broadband excitation and reception is introduced. The ultrasonic signals are excited by laser and received by polyvinylindene fluoride (PVDF) transducer. The SAW signals in aluminum alloy materials with different impact times by laser shock peening are detected. Signal spectrum and phase velocity dispersion curves of SAWs are analyzed. Moreover, reasons for dispersion are discussed.

  13. Laser-driven shock acceleration of monoenergetic ion beams

    CERN Document Server

    Fiuza, F; Boella, E; Fonseca, R A; Silva, L O; Haberberger, D; Tochitsky, S; Gong, C; Mori, W B; Joshi, C

    2012-01-01

    We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate $\\sim 200$ MeV proton beams with state-of-the-art 100 TW class laser systems.

  14. Cavitation bubble oscillation period as a process diagnostic during the laser shock peening process

    Science.gov (United States)

    Glaser, D.; Polese, C.

    2017-09-01

    Laser shock peening (LSP) technology is a laser-induced shock process implemented as a surface enhancement technique to introduce beneficial compressive residual stresses into metallic components. The process employs water to confine and enhance the pressure pulse delivered to the target. For thick water layers, or fully water immersed LSP, a cavitation bubble is generated by the surface vaporization of the LSP laser pulse. This research shows that the first bubble oscillation period of the cavitation bubble can be used to characterize effective and repeatable energy delivery to the target. High-speed shadowgraphy is implemented to show that variations in the bubble period occur before visual observations of dielectric breakdown in water. The diagnostic potential of the first bubble oscillation period is used to identify the dielectric breakdown threshold of water, which shows an increase with increasing water quality measured by water conductivity.

  15. Numerical simulation and experiment of TA2 sheet forming under laser shock

    Institute of Scientific and Technical Information of China (English)

    Li Gao; Jiayang Yu; Yongkang Zhang

    2006-01-01

    @@ The effects of laser energy and different shock spaces and shock times on the TA2 titanium sheet deformation are investigated experimentally and simulated numerically by ABAQUS software. The results indicate that the amount of TA2 sheet deformation increases with the increase of laser energy, varies with shock order and shock path, and is the greatest when the shocks are along the length of sheet and symmetrical.The numerically simulative results are consistent with the experimental data.

  16. Experimental investigation on: Laser shock micro-forming process using the mask and flexible pad

    Science.gov (United States)

    Wang, Xiao; Li, Liyin; Shen, Zongbao; Sha, Chaofei; Gao, Shuai; Li, Cong; Sun, Xianqing; Ma, Youjuan; Liu, Huixia

    2017-01-01

    A forming process called the mask and flexible pad laser shock forming was proposed to fabricate the micro-features on the copper foil. In this process, the mask and laser beam were used as rigid punches. Shock waves induced by plasma were used as the source of loading and plasticine was used as a flexible pad. This was a micro scale and high strain rate forming process and the traditional forming method with micro-mold was changed. In the experiment, surface morphology of formed parts was represented and it was found that the mask played a significant role in the forming process. In order to understand the forming process in the experiment, process parameters, including laser pulse energy, numbers of laser pulse and grain size, were analyzed. The experimental results showed that different parameters had different effects on formed parts. The surface quality and the thickness distribution of formed parts were investigated. It was found that formed parts could keep good surface quality after laser shocking and the reasons were explored. The thickness distribution was measured and the thickness thinning rate was calculated. There was no local tightening or rupture in the forming area. In this paper, the micro-features could be obtained on metallic foils and the method of mold-free was proved to be feasible.

  17. Laser-plasma interaction physics for shock ignition

    Directory of Open Access Journals (Sweden)

    Goyon C.

    2013-11-01

    Full Text Available In the shock ignition scheme, the ICF target is first compressed with a long (nanosecond pulse before creating a convergent shock with a short (∼100 ps pulse to ignite thermonuclear reactions. This short pulse is typically (∼2.1015–1016 W/cm2 above LPI (Laser Plasma Instabilities thresholds. The plasma is in a regime where the electron temperature is expected to be very high (2–4 keV and the laser coupling to the plasma is not well understood. Emulating LPI in the corona requires large and hot plasmas produced by high-energy lasers. We conducted experiments on the LIL (Ligne d'Integration Laser, 10 kJ at 3ω and the LULI2000 (0.4 kJ at 2ω facilities, to approach these conditions and study absorption and LPI produced by a high intensity beam in preformed plasmas. After introducing the main risks associated with the short pulse propagation, we present the latest experiment we conducted on LPI in relevant conditions for shock ignition.

  18. Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy

    Science.gov (United States)

    Wang, Jenny; Huie, Philip; Dalal, Roopa; Lee, Seungjun; Tan, Gavin; Lee, Daeyoung; Lavinksy, Daniel; Palanker, Daniel

    2016-03-01

    Unlike conventional photocoagulation, non-damaging retinal laser therapy (NRT) limits laser-induced heating to stay below the retinal damage threshold and therefore requires careful dosimetry. Without the adverse effects associated with photocoagulation, NRT can be applied to critical areas of the retina and repeatedly to manage chronic disorders. Although the clinical benefits of NRT have been demonstrated, the mechanism of therapeutic effect and width of the therapeutic window below damage threshold are not well understood. Here, we measure activation of heat shock response via laser-induced hyperthermia as one indication of cellular response. A 577 nm laser is used with the Endpoint Management (EpM) user interface, a titration algorithm, to set experimental pulse energies relative to a barely visible titration lesion. Live/dead staining and histology show that the retinal damage threshold in rabbits is at 40% of titration energy on EpM scale. Heat shock protein 70 (HSP70) expression in the retinal pigment epithelium (RPE) was detected by whole-mount immunohistochemistry after different levels of laser treatment. We show HSP70 expression in the RPE beginning at 25% of titration energy indicating that there is a window for NRT between 25% and 40% with activation of the heat shock protein expression in response to hyperthermia. HSP70 expression is also seen at the perimeter of damaging lesions, as expected based on a computational model of laser heating. Expression area for each pulse energy setting varied between laser spots due to pigmentation changes, indicating the relatively narrow window of non-damaging activation and highlighting the importance of proper titration.

  19. EBSD analysis of plastic deformation of copper foils by flexible pad laser shock forming

    Energy Technology Data Exchange (ETDEWEB)

    Nagarajan, Balasubramanian; Castagne, Sylvie [Nanyang Technological University, SIMTech-NTU Joint Laboratory (Precision Machining), Singapore (Singapore); Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore (Singapore); Wang, Zhongke; Zheng, H.Y. [Nanyang Technological University, SIMTech-NTU Joint Laboratory (Precision Machining), Singapore (Singapore); Singapore Institute of Manufacturing Technology, Machining Technology Group, Singapore (Singapore)

    2015-11-15

    Flexible pad laser shock forming (FPLSF) is a new mold-free microforming process that induces high-strain-rate plastic deformation in thin metallic foils using laser-induced shock pressure and a hyperelastic flexible pad. This paper studies the plastic deformation behavior of copper foils formed through FPLSF by investigating surface hardness and microstructure. The microstructure of the foil surface before and after FPLSF is analyzed by electron backscatter diffraction technique using grain size distribution and grain boundary misorientation angle as analysis parameters. The surface hardness of the craters experienced a significant improvement after FPLSF; the top crater surface being harder than the bottom surface. The microstructure of the copper foil surface after FPLSF was found to be dominated by grain elongation, along with minor occurrences of subgrain formation, grain refinement, and high dislocation density regions. The results indicate that the prominent plastic deformation mechanism in FPLSF is strain hardening behavior rather than the typical adiabatic softening effect known to be occurring at high-strain-rates for processes such as electromagnetic forming, explosive forming, and laser shock forming. This significant difference in FPLSF is attributed to the concurrent reduction in plastic strain, strain rate, and the inertia effects, resulting from the FPLSF process configuration. Correspondingly, different deformation behaviors are experienced at top and bottom surfaces of the deformation craters, inducing the change in surface hardness and microstructure profiles. (orig.)

  20. Pressure measurements and an analytical model for laser-generated shock waves in solids at low irradiance

    CERN Document Server

    Romain, J P; Dayma, G; Boustie, M; Resseguier, T D; Combis, P

    2002-01-01

    Low amplitude shock waves (from 1 to 300 bar) have been generated in gold layers deposited on a quartz substrate, by laser pulses at an incident fluence from 0.4 to 4.0 J cm sup - sup 2. The quartz was used as a pressure gauge for recording the induced shock profile. At a fluence <1.4 J cm sup - sup 2 , the shock pressure does not exceed 10 bar and the shock front is followed by a tension peak typical of an absorption in solid state. An analytical model of the compression-tension process has been developed, accounting for shock pressure and shock profile evolution as a function of irradiation conditions and material properties. From this model a mechanical interpretation is given to previous observations of spalling of the irradiated target surface.

  1. Laser Shock Compression and Spalling of Reactive Ni-Al Laminate Composites

    Science.gov (United States)

    Wei, C. T.; Maddox, B. R.; Weihs, T. P.; Stover, A. K.; Nesterenko, V. F.; Meyers, M. A.

    2009-12-01

    Reactive laminates produced by successive rolling and consisting of alternate layers of Ni and Al (with bi-layer thicknesses of 5 and 30 μm) were investigated by subjecting them to laser shock-wave loading. The laser intensity was varied between ˜2.68×1011 W/cm2 (providing an initial estimated pressure P˜25 GPa) and ˜1.28×1013 W/cm2 (P˜333 GPa) with two distinct initial pulse durations: 3 ns and 8 ns. Hydrodynamic calculations (using commercial code HYADES) were conducted to simulate the behavior of shock-wave propagation in the laminate structures. SEM, and XRD were carried out on the samples to study the reaction initiation, and the intermetallic compounds. It was found that the thinner bilayer thickness (5 μm) laminate exhibited the most intensive localized interfacial reaction at the higher laser intensity (1.28×1013 W/cm2); the reaction products were identified as NiAl and other Al-rich intermetallic compounds. The reaction front and the formation of intermetallic compounds extend into the sample with a thinner bilayer thickness (5 μm) to a depth of about 50 μm. Increase in the duration of laser shock wave induces increased reaction, which occurs also in the thicker bilayer laminate samples (30 μm bi-layer thickness). It is demonstrated that the methodology of laser shock is well suited to investigate the threshold conditions for dynamic mechanical reaction initiation caused by high intensity laser irradiation.

  2. Laser Shock Peening of Aluminum Alloy 7050 for Fatigue Life Improvement

    Institute of Scientific and Technical Information of China (English)

    Qian; Ming; Lian; Ying; Zou; Shikun; Gong; Shuili

    2007-01-01

    The effects of laser shock peening (LSP) on improving fatigue life of aluminum alloy 7050 are investigated.Surface hardness is increased corresponding to a high dislocation density induced by LSP.The X-ray diffraction stress measurement shows that LSP results in prominent increase of surface compressive stress,quasi-symmetrically distributed in the laser peened region.The fatigue life of the alloy 7050 in rivet fastener hole structure is notably improved owing to LSP.The sequence of LSP and fastener hole preparation also influence the fatigue cycle life of the alloy.

  3. Effects of simulation parameters on residual stresses for laser shock peening finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Hee [Korea Military Academy, Seoul (Korea, Republic of); Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Kim, Joung Soo [KAERI, Daejeon (Korea, Republic of)

    2013-07-15

    By using finite element analysis, we proposed an applicable finite element method of laser shock peening (LSP) and discussed various parameters, such as solution time, stability limit, dynamic yield stress, peak pressure, pressure pulse duration, laser spot size, and multiple LSP. The effects of parameters related to the finite element simulation of the LSP process on the residual stresses of 35CD4 30HRC steel alloy are discussed. Parametric sensitivity analyses were performed to establish the optimum processing variables of the LSP process. In addition, we evaluated the effects of initial residual stress, such as welding-induced residual stress field.

  4. Effect of multipath laser shock processing on microhardness, surface roughness, and wear resistance of 2024-T3 Al alloy.

    Science.gov (United States)

    Kadhim, Abdulhadi; Salim, Evan T; Fayadh, Saeed M; Al-Amiery, Ahmed A; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

    2014-01-01

    Laser shock processing (LSP) is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. LSP is based on the application of a high intensity pulsed laser beam (I > 1 GW/cm(2); t surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The shock wave induces plastic deformation and a residual stress distribution in the target material. In this paper we study the increase of microhardness and surface roughness with the increase of laser pulse energy in 2024-T3 Al alloy. The influence of the thickness of the confining layer (water) on microhardness and surface roughness is also studied. In addition, the effect of LSP treatment with best conditions on wear behaviors of the alloy was investigated.

  5. Intense laser driven collision-less shock and ion acceleration in magnetized plasmas

    Science.gov (United States)

    Mima, K.; Jia, Q.; Cai, H. B.; Taguchi, T.; Nagatomo, H.; Sanz, J. R.; Honrubia, J.

    2016-05-01

    The generation of strong magnetic field with a laser driven coil has been demonstrated by many experiments. It is applicable to the magnetized fast ignition (MFI), the collision-less shock in the astrophysics and the ion shock acceleration. In this paper, the longitudinal magnetic field effect on the shock wave driven by the radiation pressure of an intense short pulse laser is investigated by theory and simulations. The transition of a laminar shock (electro static shock) to the turbulent shock (electromagnetic shock) occurs, when the external magnetic field is applied in near relativistic cut-off density plasmas. This transition leads to the enhancement of conversion of the laser energy into high energy ions. The enhancement of the conversion efficiency is important for the ion driven fast ignition and the laser driven neutron source. It is found that the total number of ions reflected by the shock increases by six time when the magnetic field is applied.

  6. Laser Accelerated Ions from a Shock Compressed Gas Foil

    CERN Document Server

    Helle, M H; Kaganovich, D; Chen, Y; Palastro, J P; Ting, A

    2016-01-01

    We present results of energetic laser-ion acceleration from a tailored, near solid density gas target. Colliding hydrodynamic shocks compress a pure hydrogen gas jet into a 70 {\\mu}m thick target prior to the arrival of the ultra-intense laser pulse. A density scan reveals the transition from a regime characterized by a wide angle, low energy beam to one of a more focused beam with a high energy halo. In the latter case, three dimensional simulations show the formation of a Z-pinch driven by the axial current resulting from laser wakefield accelerated electrons. Ions at the rear of the target are then accelerated by a combination of space charge fields from accelerated electrons and Coulombic repulsion as the pinch dissipates.

  7. PLIF thermometry in shock tunnel flows using a Raman-shifted tunable excimer laser

    Science.gov (United States)

    Palma, P. C.; McIntyre, T. J.; Houwing, A. F. P.

    Planar laser-induced fluorescence is performed in a free-piston shock tunnel by using a Raman-shifted tunable excimer laser to excite nitric oxide molecules in the flow. Two different flowfields are examined to test the difficulties associated with applying the technique to shock tunnels: the bluff body flow produced by a 25 mm diameter cylinder; and the oblique shock and expansion fan produced by a 35° half-angle wedge. For the cylinder, the maximum flow enthalpy was limited to 4.1 MJ kg -1 due to high flow luminosity which is produced by metallic contaminants in the flow. A reflective filter is used to reduce the influence of flow luminosity making these measurements feasible. Freestream temperature measurements are in excellent agreement with those predicted from numerical flow calculations. Large uncertainties were observed for the high-temperature post-shock results. Several higher enthalpy shots (14 MJ kg -1) were also performed with the wedge and showed an insignificant amount of contaminant emission.

  8. Laser Shock Processing of Surface Copperize on Arc-Meshes Gear%齿轮啮合线表面镀铜层的激光强化处理

    Institute of Scientific and Technical Information of China (English)

    马德毅; 刘继光; 宋丹路

    2004-01-01

    This paper presents surface modifications of aluminum-alloy induced by laser-shock processing (LSP). In the first part, the basic principles are discussed to provide an overview of the physical processes involved in laser shock processing, and to introduce pressure loadings generated by different laser generators. In the second part, emphases are given to the effects of laser intensity, target material, laser pulse duration and laser wavelength, and uniform and localized modeling of fatigue behavior after LSP. In the third part,experimental results are given to show the laser-induced pure mechanical effects on aluminum-alloy by using LSP.

  9. Investigating Vaporization of Silica through Laser Driven Shock Wave Experiments

    Science.gov (United States)

    Kraus, R. G.; Swift, D. C.; Stewart, S. T.; Smith, R.; Bolme, C. A.; Spaulding, D. K.; Hicks, D.; Eggert, J.; Collins, G.

    2010-12-01

    Giant impacts melt and vaporize a significant amount of the bolide and target body. However, our ability to determine how much melt or vapor a given impact creates depends strongly on our understanding of the liquid-vapor phase boundary of geologic materials. Our current knowledge of the liquid-vapor equilibrium for one of the most important minerals, SiO2, is rather limited due to the difficulty of performing experiments in this area of phase space. In this study, we investigate the liquid-vapor coexistence region by shocking quartz into a supercritical fluid state and allowing it to adiabatically expand to a state on the liquid-vapor phase boundary. Although shock compression and release has been used to study the liquid-vapor equilibrium of metals [1], few attempts have been made at studying geologic materials by this method [2]. Shock waves were produced by direct ablation of the quartz sample using the Jupiter Laser Facility of Lawrence Livermore National Laboratory. Steady shock pressures of 120-360 GPa were produced in the quartz samples: high enough to force the quartz into a supercritical fluid state. As the shock wave propagates through the sample, we measure the shock velocity using a line imaging velocity interferometer system for any reflector (VISAR) and shock temperature using a streaked optical pyrometer (SOP). When the shock wave reaches the free surface of the sample, the material adiabatically expands. Upon breakout of the shock at the free surface, the SOP records a distinct drop in radiance due to the lower temperature of the expanded material. For a subset of experiments, a LiF window is positioned downrange of the expanding silica. When the expanding silica impacts the LiF window, the velocity at the interface between the expanding silica and LiF window is measured using the VISAR. From the shock velocity measurements, we accurately determine the shocked state in the quartz. The post-shock radiance measurements are used to constrain the

  10. Laser-Shock Experiments: Calorimetry Measurements to TPa Pressures

    Science.gov (United States)

    Jeanloz, R.

    2012-12-01

    Laser-driven shock experiments are more like calorimetry measurements, characterized by determinations of Hugoniot temperature (TH) as a function of shock velocity (US), rather than the equation-of-state measurements afforded by mechanical-impact experiments. This is because particle velocity (up) is often not accessible to direct measurement in laser-shock experiments, so must be inferred with reference to a material having a well-determined, independently calibrated Hugoniot equation of state (up is obtained from the impact velocity in traditional shock experiments, and the combination of US and up yields the pressure-density equation of state for the sample). Application of a Mie-Grüneisen model shows that the isochoric specific heat for a given phase is: CV = (US - c0)2 {s2US (dTH/dUS) + γ0 c0 s (TH/US)}-1 with US = c0 + s up, and γ0 is the zero-pressure Grüneisen parameter (γ/V = constant is assumed here). This result is a generalization to TH-US variables of the Walsh and Christian (1955) formula for the temperature rise along the Hugoniot of a given phase (identified here with a US - up relation that is locally linear); it can be analytically integrated to give TH(US) in terms of an average value of CV, if no phase transition takes place. Analysis of the TH-US slopes obtained from laser-shock measurements on MgO yields specific-heat values ranging from 1.02 (± 0.05) kJ/kg/K at 320-345 GPa and TH = 7700-9000 K to 1.50 (± 0.05) kJ/kg/K at 350-380 GPa and TH = 8700-9500 K. A fit to the absolute values of TH(US) in this pressure-temperature range gives CV = 1.26 (± 0.10) kJ/kg/K, in good accord with the Dulong-Petit value CV = 1.24 kJ/kg/K.

  11. Direct observations of reaction zone structure in shock-induced ignition of methane air mixture

    Institute of Scientific and Technical Information of China (English)

    WANG GaoFeng; MA ChengBiao; WANG BaoYuan; LIN QiZhao

    2009-01-01

    Ignition of methane/air mixture by the passage of a shock wave is an important issue for understanding more details of its gaseous detonation.The experiments of shock-induced ignition of stoichiometric methane/air mixture were conducted on a shock tube platform.The reaction zone structure in weak and strong ignition cases were investigated by digital chemiluminescence imaging and planar laser induced fluorescence (PLIF) techniques.Due to smaller gradients in induced time in weak ignition,which provided more time to nonlinear chemical reaction process,the results show that the reaction structures are highly nonuniform in those weak ignition cases,which become more regular while induced shock waves become stronger.In strong ignition case,it gives a typical detonation structure.The characteristics of reaction zone released by single-pulsed OH PLIF technique agreed well with other experimental measurements in this paper and were also in accord with the conclusions of previous researches.The successful implementation of the PLIF system has explored a new high temporally and spatially resolved method for the study of interaction between shock wave and gaseous matter in shock tube.

  12. Laser shocking of materials: Toward the national ignition facility

    Science.gov (United States)

    Meyers, M. A.; Remington, B. A.; Maddox, B.; Bringa, E. M.

    2010-01-01

    In recent years a powerful experimental tool has been added to the arsenal at the disposal of the materials scientist investigating materials response at extreme regimes of strain rates, temperatures, and pressures: laser compression. This technique has been applied successfully to mono-, poly-, and nanocrystalline metals and the results have been compared with predictions from analytical models and molecular dynamics simulations. Special flash x-ray radiography and flash x-ray diffraction, combined with laser shock propagation, are yielding the strength of metals at strain rates on the order of 107-108 s-1 and resolving details of the kinetics of phase transitions. A puzzling result is that experiments, analysis, and simulations predict dislocation densities that are off by orders of magnitude. Other surprises undoubtedly await us as we explore even higher pressure/strain rate/temperature regimes enabled by the National Ignition Facility.

  13. Effect of laser shock processing on fatigue crack growth of duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Rubio-Gonzalez, C., E-mail: crubio@cidesi.mx [Centro de Ingenieria y Desarrollo Industrial, Pie de la Cuesta, 702, Desarrollo San Pablo, Queretaro, Qro., 76130 (Mexico); Felix-Martinez, C. [Centro de Ingenieria y Desarrollo Industrial, Pie de la Cuesta, 702, Desarrollo San Pablo, Queretaro, Qro., 76130 (Mexico); Gomez-Rosas, G. [Universidad de Guadalajara, Guadalajara, Jal (Mexico); Ocana, J.L.; Morales, M.; Porro, J.A. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I., Universidad Politecnica de Madrid (Spain)

    2011-01-25

    Research highlights: {yields} LSP is an effective surface treatment to improve fatigue properties of duplex stainless steel. {yields} Increasing pulse density, fatigue crack growth rate is reduced. {yields} Microstructure is not affected by LSP. {yields} Compressive residual stresses increases increasing pulse density. - Abstract: Duplex stainless steels have wide application in different fields like the ship, petrochemical and chemical industries that is due to their high strength and excellent toughness properties as well as their high corrosion resistance. In this work an investigation is performed to evaluate the effect of laser shock processing on some mechanical properties of 2205 duplex stainless steel. Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switched Nd:YAG laser, operating at 10 Hz with infrared (1064 nm) radiation. The pulses are focused to a diameter of 1.5 mm. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is determined by the contour method. It is observed that the higher the pulse density the greater the compressive residual stress. Pulse densities of 900, 1600 and 2500 pul/cm{sup 2} are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness if this steel.

  14. Collisionless shock experiments with lasers and observation of Weibel instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.-S., E-mail: park1@llnl.gov; Huntington, C. M.; Fiuza, F.; Levy, M. C.; Pollock, B. B.; Remington, B. A.; Ross, J. S.; Ryutov, D. D.; Turnbull, D. P.; Weber, S. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Drake, R. P.; Kuranz, C. C. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Froula, D. H.; Rosenberg, M. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14636 (United States); Gregori, G.; Meinecke, J. [University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Koenig, M. [LULI, Ecole Polytechnique, Palaiseau (France); Kugland, N. L. [Lam Research Corporation, Fremont, California 94538 (United States); Lamb, D. Q.; Tzeferacos, P. [University of Chicago, Chicago, California 94538 (United States); and others

    2015-05-15

    Astrophysical collisionless shocks are common in the universe, occurring in supernova remnants, gamma ray bursts, and protostellar jets. They appear in colliding plasma flows when the mean free path for ion-ion collisions is much larger than the system size. It is believed that such shocks could be mediated via the electromagnetic Weibel instability in astrophysical environments without pre-existing magnetic fields. Here, we present laboratory experiments using high-power lasers and investigate the dynamics of high-Mach-number collisionless shock formation in two interpenetrating plasma streams. Our recent proton-probe experiments on Omega show the characteristic filamentary structures of the Weibel instability that are electromagnetic in nature with an inferred magnetization level as high as ∼1% [C. M. Huntington et al., “Observation of magnetic field generation via the weibel instability in interpenetrating plasma flows,” Nat. Phys. 11, 173–176 (2015)]. These results imply that electromagnetic instabilities are significant in the interaction of astrophysical conditions.

  15. Experimental and numerical investigation of laser shock synchronous welding and forming of Copper/Aluminum

    Science.gov (United States)

    Wang, Xiao; Zhang, Hongfeng; Shen, Zongbao; Li, Jianwen; Qian, Qing; Liu, Huixia

    2016-11-01

    A novel laser shock synchronous welding and forming method is introduced, which utilizes laser-induced shock waves to accelerate the flyer plate towards the base plate to achieve the joining of dissimilar metals and forming in a specific shape of mold. The samples were obtained with different laser energies and standoff distances. The surface morphology and roughness of the samples were greatly affected by the laser energy and standoff distances. Fittability was investigated to examine the forming accuracy. The results showed that the samples replicate the mold features well. Straight and wavy interfaces with un-bonded regions in the center were observed through metallographic analysis. Moreover, Energy Disperse Spectroscopy analysis was conducted on the welding interface, and the results indicated that a short-distance elemental diffusion emerged in the welding interface. The nanoindentation hardness of the welding regions was measured to evaluate the welding interface. In addition, the Smoothed Particle Hydrodynamics method was employed to simulate the welding and forming process. It was shown that different standoff distances significantly affected the size of the welding regions and interface waveform characteristics. The numerical analysis results indicated that the opposite shear stress direction and effective plastic strain above a certain threshold are essential to successfully obtain welding and forming workpiece.

  16. Improvement of mechanical properties and life extension of high reliability structural components by laser shock processing

    Science.gov (United States)

    Ocaña, J. L.; Morales, M.; Porro, J. A.; Iordachescu, D.; Díaz, M.; Ruiz de Lara, L.; Correa, C.

    2011-05-01

    Profiting by the increasing availability of laser sources delivering intensities above 109 W/cm2 with pulse energies in the range of several Joules and pulse widths in the range of nanoseconds, laser shock processing (LSP) is being consolidating as an effective technology for the improvement of surface mechanical and corrosion resistance properties of metals and is being developed as a practical process amenable to production engineering. The main acknowledged advantage of the laser shock processing technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Following a short description of the theoretical/computational and experimental methods developed by the authors for the predictive assessment and experimental implementation of LSP treatments, experimental results on the residual stress profiles and associated surface properties modification successfully reached in typical materials (specifically Al and Ti alloys) under different LSP irradiation conditions are presented. In particular, the analysis of the residual stress profiles obtained under different irradiation parameters and the evaluation of the corresponding induced surface properties as roughness and wear resistance are presented.

  17. On the scaling and unsteadiness of shock induced separation

    NARCIS (Netherlands)

    Souverein, L.J.

    2010-01-01

    Shock wave boundary layer interactions (SWBLI) are a common phenomenon in transonic and supersonic flows. The presence of shock waves, induced by specific geometrical configurations, causes a rapid increase of the pressure, which can lead to flow separation. Examples of such interactions are found i

  18. Unfocused Extracorporeal Shock Waves Induce Anabolic Effects in Rat Bone

    NARCIS (Netherlands)

    O.P. van der Jagt (Olav); T.M. Piscaer (Tom); W. Schaden (Wolfgang); J. Li; N. Kops (Nicole); H. Jahr (Holger); J.C. van der Linden (Jacqueline); J.H. Waarsing (Jan); J.A.N. Verhaar (Jan); M. de Jong (Marion); H.H. Weinans (Harrie)

    2011-01-01

    textabstractAbstract. BACKGROUND: Extracorporeal shock waves are known to stimulate the differentiation of mesenchymal stem cells toward osteoprogenitors and induce the expression of osteogenic-related growth hormones. The aim of this study was to investigate if and how extracorporeal shock waves af

  19. Unfocused Extracorporeal Shock Waves Induce Anabolic Effects in Rat Bone

    NARCIS (Netherlands)

    O.P. van der Jagt (Olav); T.M. Piscaer (Tom); W. Schaden (Wolfgang); J. Li; N. Kops (Nicole); H. Jahr (Holger); J.C. van der Linden (Jacqueline); J.H. Waarsing (Jan); J.A.N. Verhaar (Jan); M. de Jong (Marion); H.H. Weinans (Harrie)

    2011-01-01

    textabstractAbstract. BACKGROUND: Extracorporeal shock waves are known to stimulate the differentiation of mesenchymal stem cells toward osteoprogenitors and induce the expression of osteogenic-related growth hormones. The aim of this study was to investigate if and how extracorporeal shock waves

  20. MINKOWSKI FUNCTIONALS FOR QUANTITATIVE ASSESSMENTS OF SHOCK-INDUCED MIXING FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    STRELITZ, RICHARD A. [Los Alamos National Laboratory; KAMM, JAMES R. [Los Alamos National Laboratory

    2007-01-22

    We describe the morphological descriptors known as Minkowski Functionals (MFs) on a shock-induced mixing problem. MFs allow accurate and compact characterization of complex images. MFs characterize connectivity, size, and shape of disordered structures. They possess several desirable properties, such as additivity, smoothness, and a direct relationship to certain physical properties. The scalar MFs that we describe can be extended to a moment-based tensor form that allows more thorough image descriptions. We apply MFs to experimental data for shock-induced mixing experiments conducted at the LANL shock tube facility. Those experiments, using low Mach number shock waves in air to induce the Richtmyer-Meshkov instability on air-SF{sub 6} interfaces, provide high-resolution, quantitative planar laser-induced fluorescence (PLIF) images. We describe MFs and use them to quantify experimental PLIF images of shock-induced mixing. This method can be used as a tool fo r validation, i.e., the quantitative comparison of simulation results against experimental data.

  1. Shock-induced melting and rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Nellis, W.J.; Gourdin, W.H.; Maple, M.B.

    1987-08-01

    Model calculations are presented to estimate that approx.50 GPa is required to completely shock melt metal powders with quenching at rates up to 10/sup 8/ K/s. Experiments are discussed for powders of a Cu-Zr alloy compacted in the usual way at 16 GPa and melted by shocking to 60 GPa. 12 refs.

  2. Weibel-instability-mediated collisionless shocks in laboratory with ultraintense lasers

    CERN Document Server

    Fiuza, F; Tonge, J; Mori, W B; Silva, L O

    2012-01-01

    The formation of non-relativistic collisionless shocks in laboratory with ultrahigh intensity lasers is studied via \\emph{ab initio} multi-dimensional particle-in-cell simulations. The microphysics behind shock formation and dissipation, and the detailed shock structure are analyzed, illustrating that the Weibel instability plays a crucial role in the generation of strong subequipartition magnetic fields that isotropize the incoming flow and lead to the formation of a collisionless shock, similarly to what occurs in astrophysical scenarios. The possibility of generating such collisionless shocks in laboratory opens the way to the direct study of the physics associated with astrophysical shocks.

  3. Investigation of Corrosion Behaviour of Aluminium Alloy Subjected to Laser Shock Peening without a Protective Coating

    Directory of Open Access Journals (Sweden)

    U. Trdan

    2015-01-01

    Full Text Available The effect of shock waves and strain hardening of laser shock peening without protective coating (LSPwC on alloy AA 6082-T651 was investigated. Analysis of residual stresses confirmed high compression in the near surface layer due to the ultrahigh plastic strains and strain rates induced by multiple laser shock waves. Corrosion tests in a chloride environment were carried out to determine resistance to localised attack, which was also verified on SEM/EDS. OCP transients confirmed an improved condition, that is, a more positive and stable potential after LSPwC treatment. Moreover, polarisation resistance of the LSPwC treated specimen was by a factor of 25 higher compared to the untreated specimen. Analysis of voltammograms confirmed an improved enhanced region of passivity and significantly smaller anodic current density of the LSPwC specimen compared to the untreated one. Through SEM, reduction of pitting attack at the LSPwC specimen surface was confirmed, despite its increased roughness.

  4. Shock priming enhances the efficacy of SSRIs in the foot shock-induced ultrasonic vocalization test.

    Science.gov (United States)

    Kassai, Ferenc; Gyertyán, István

    2012-01-10

    Data on the effect of acutely administered serotonin reuptake inhibitors (SSRIs) in animal anxiety models have been inconsistent. In some of the models these compounds showed anxiolytic properties, while in others they were ineffective or even anxiogenic. In the foot shock-induced ultrasonic vocalization (USV) test in the adult rat, SSRIs were reported to be effective, however, they were only tested with protocols using multiple shocking design. In the present study, anxiolytic effects of various SSRI compounds (sertraline, fluoxetine, paroxetine, escitalopram) were tested in three distinct USV test protocols in comparison with alprazolam and 8-OH-DPAT. In the single shocking protocol, animals were exposed to one shocking session after the drug treatment. In the multiple shocking protocol, rats went through a foot shock priming session before each drug test. On priming days animals received foot shocks without drug treatment. On the test day (the day after), rats received drug treatment and then were shocked again. In the context conditioning protocol animals were exposed to foot shocks on two consecutive days before the drug test. On the third, test day, after drug treatment animals were replaced to the shocking chamber, but this time shocks were not delivered. SSRIs were ineffective using the single shocking protocol. In the context conditioned protocol, all SSRIs showed linear dose-response relationship with ED50 values of 8.5, 2.2, 0.77 and 0.93 mg/kg i.p. for fluoxetine, sertraline, paroxetine and escitalopram, respectively. Using the multiple shocking protocol, SSRIs were only partially effective with maximum inhibitions ranging between 44% and 62%. In contrast to SSRIs, the benzodiazepine anxiolytics, alprazolam showed anxiolytic activity with linear dose-response relationship in all of the test protocols, with ED50 values varying from 1.3 to 4.0 mg/kg i.p. The serotonin 5HT1A receptor antagonist 8-OH-DPAT also showed linear dose-response relationship in all

  5. Laser shock experiments to investigate and to model various aspects of the response of metals to shock loading

    Directory of Open Access Journals (Sweden)

    Berthe L.

    2011-01-01

    Full Text Available Laser driven shocks allow studying the dynamic behaviour of condensed matter over small spatial (∼μm to mm-order and temporal (∼ps to ns-order scales, at extremely high strain rates (∼107 s−1. They can be used to test the predictive capability of constitutive models over wide ranges of loading pressures and pulse durations. We present experimental results in laser shock-loaded metals (iron, gold, tin, based on various, complementary techniques including time-resolved velocity measurements, transverse shadowgraphy and post-shock analyses of recovered samples. The data are used to investigate several shock wave processes such as yielding and polymorphic transformations, melting, spall fracture and dynamic fragmentation in both solid and melted states. On the basis of comparisons with numerical simulations, the abilities and limitations of several models are briefly discussed.

  6. Laser Indirect Shock Welding of Fine Wire to Metal Sheet.

    Science.gov (United States)

    Wang, Xiao; Huang, Tao; Luo, Yapeng; Liu, Huixia

    2017-09-12

    The purpose of this paper is to present an advanced method for welding fine wire to metal sheet, namely laser indirect shock welding (LISW). This process uses silica gel as driver sheet to accelerate the metal sheet toward the wire to obtain metallurgical bonding. A series of experiments were implemented to validate the welding ability of Al sheet/Cu wire and Al sheet/Ag wire. It was found that the use of a driver sheet can maintain high surface quality of the metal sheet. With the increase of laser pulse energy, the bonding area of the sheet/wire increased and the welding interfaces were nearly flat. Energy dispersive spectroscopy (EDS) results show that the intermetallic phases were absent and a short element diffusion layer which would limit the formation of the intermetallic phases emerging at the welding interface. A tensile shear test was used to measure the mechanical strength of the welding joints. The influence of laser pulse energy on the tensile failure modes was investigated, and two failure modes, including interfacial failure and failure through the wire, were observed. The nanoindentation test results indicate that as the distance to the welding interface decreased, the microhardness increased due to the plastic deformation becoming more violent.

  7. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Science.gov (United States)

    Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Winske, D.; Gekelman, W.; Niemann, C.

    2015-11-01

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  8. Laser induced structural vibration

    Science.gov (United States)

    Koss, L. L.; Tobin, R. C.

    1983-01-01

    A technique is described for exciting structural vibration by using a focussed laser beam to vaporize material from a target attached to the structure. The rapid ejection of material results in an impulsive reaction to the target which is transmitted to the structure. The method has been studied with a Nd: glass laser, operated in the long pulse mode, in combination with a bismuth target attached in turn to a ballistic pendulum and cantilever beam. The specific mechanical energy was found to be proportional to the laser pulse energy raised to a power in the range 2.5-2.9. The highest efficiency of energy transfer achieved for the first vibrational mode of the cantilever was about 2 millipercent for the maximum laser pulse energy used, 1.5 J, the signal to noise ratio then being about 40 dB.

  9. Turbulence measurements in shock induced flow using hot wire anemometry

    Science.gov (United States)

    Hartung, Lin C.; Duffy, Robert E.; Trolier, James W.

    1988-01-01

    Heat transfer measurements over various geometric shapes have been made by immersing models in shock-induced flows. The heat transfer to a body is strongly dependent on the turbulence level of the stream. The interpretation of such heat transfer measurements requires a knowledge of the turbulence intensity. Turbulence intensity measurements, using hot-wire anemometry, have been successfully carried out in shock-induced flows. The experimental procedures for making such measurements and the techniques required are discussed.

  10. Collisionless electrostatic shock formation and ion acceleration in intense laser interactions with near critical density plasmas

    Science.gov (United States)

    Liu, M.; Weng, S. M.; Li, Y. T.; Yuan, D. W.; Chen, M.; Mulser, P.; Sheng, Z. M.; Murakami, M.; Yu, L. L.; Zheng, X. L.; Zhang, J.

    2016-11-01

    Laser-driven collisionless electrostatic shock formation and the subsequent ion acceleration have been studied in near critical density plasmas. Particle-in-cell simulations show that both the speed of laser-driven collisionless electrostatic shock and the energies of shock-accelerated ions can be greatly enhanced due to fast laser propagation in near critical density plasmas. However, a response time longer than tens of laser wave cycles is required before the shock formation in a near critical density plasma, in contrast to the quick shock formation in a highly overdense target. More important, we find that some ions can be reflected by the collisionless shock even if the electrostatic potential jump across the shock is smaller than the ion kinetic energy in the shock frame, which seems against the conventional ion-reflection condition. These anomalous ion reflections are attributed to the strong time-oscillating electric field accompanying the laser-driven collisionless shock in a near critical density plasma.

  11. Laser shocks: A tool for experimental simulation of damage into materials

    Energy Technology Data Exchange (ETDEWEB)

    Boustie, M.; Cuq Lelandais, J. P.; Berthe, L.; Ecault, R. [Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France); CEA-DAM Valduc, 21120 Is-sur-Tille (France); Laboratoire Procedes et Ingenierie en Mecanique et Materiaux (CNRS), Arts et Metiers ParisTech, 151 bd de l' Hopital, 75013 PARIS (France); Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France)

    2012-07-30

    High power laser irradiation of solids results in a strong shock wave propagation, driving very high amplitude pressure loadings with very short durations. These particular characteristics offer the possibility to study the behaviour of matter under extreme dynamic conditions in continuity with what is possible with the conventional generators of shock (launchers of projectiles, explosives). An advantage of laser shocks is a possible recovery of the shocked samples presenting the metallurgical effects of the shock in most cases. We introduce the principle of the laser shock generation, the characterization of these shocks, the principal mechanisms and effects associated with their propagation in the solids. We show how laser shocks can be a laboratory tool for simulating shock effects at ultra high strain rate, providing a high in information experimental layout for validation of damage modelling on an extended strain rate range compared to conventional shock generators. New data have been obtained with ultra short femtosecond range irradiation. Experimental data gathered through post mortem observation, time resolved velocity measurement are shown along with numerical associated simulations, showing the possibility to predict the damage behaviour of metallic targets under extreme strain rate up to 10{sup 8} s{sup -1}.

  12. Kelvin-Helmholtz turbulence associated with collisionless shocks in laser produced plasmas.

    Science.gov (United States)

    Kuramitsu, Y; Sakawa, Y; Dono, S; Gregory, C D; Pikuz, S A; Loupias, B; Koenig, M; Waugh, J N; Woolsey, N; Morita, T; Moritaka, T; Sano, T; Matsumoto, Y; Mizuta, A; Ohnishi, N; Takabe, H

    2012-05-11

    We report the experimental results of a turbulent electric field driven by Kelvin-Helmholtz instability associated with laser produced collisionless shock waves. By irradiating an aluminum double plane target with a high-power laser, counterstreaming plasma flows are generated. As the consequence of the two plasma interactions, two shock waves and the contact surface are excited. The shock electric field and transverse modulation of the contact surface are observed by proton radiography. Performing hydrodynamic simulations, we reproduce the time evolutions of the reverse shocks and the transverse modulation driven by Kelvin-Helmholtz instability.

  13. Characteristics of Plasma Shock Waves Generated in the Pulsed Laser Ablation Process

    Institute of Scientific and Technical Information of China (English)

    李智华; 张端明; 郁伯铭; 关丽

    2002-01-01

    We modify the Sedov theory to describe plasma shock waves generated in a pulsed laser ablating process. We also study the propagation characteristics of plasma shock waves during the preparation process of functional thin films deposited by a pulsed laser. In particular, we discuss in detail the temporal behaviour of energy causing the difference of the propagation characteristics between the plasma shock wave and the ideal shock wave in the point explosion model. Under the same experimental conditions, the theoretical results calculated with our modified Sedov theory are in good agreement with the existing experimental data.

  14. Effect of laser shock peening on bending fatigue performance of AISI 9310 steel spur gear

    Science.gov (United States)

    Peng, Chong; Xiao, Yuzhe; Wang, Yanzhong; Guo, Wei

    2017-09-01

    The effect of laser shock peening (LSP) on bending fatigue performance of AISI 9310 steel spur gear has been investigated in this study. To help to explain bending fatigue test results, residual stress distribution induced by LSP is studied by means of finite element modelling, results of which are verified by X-ray diffraction analysis. It is found that a compressive layer of desirable depth can be induced on the gear root fillet after LSP, and both magnitude and depth of compressive stress increase with laser energy. The bending fatigue test is conducted using the single-tooth bending method to compare fatigue performance of laser peened teeth and non-peened teeth, which is followed by relevant statistical analysis. S-N curves acquired from the fatigue test reveal that bending fatigue lives of gear teeth has been significantly improved after LSP in comparison with those non-peened teeth, and the bending fatigue limit is enhanced correspondingly. It is noticeable that higher laser energy does not necessarily lead to much better fatigue performance of test gears.

  15. Laser-driven shock experiments in pre-compressed water: Implications for magnetic field generation in Icy Giant planets

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K; Benedetti, L R; Jeanloz, R; Celliers, P M; Eggert, J H; Hicks, D G; Moon, S J; Mackinnon, A; Henry, E; Koenig, M; Benuzzi-Mounaix, A; Collins, G W

    2005-11-10

    Laser-driven shock compression of pre-compressed water (up to 1 GPa precompression) produces high-pressure, -temperature conditions in the water inducing two optical phenomena: opacity and reflectivity in the initially transparent water. The onset of reflectivity at infrared wavelengths can be interpreted as a semi-conductor to electronic conductor transition in water and is found at pressures above {approx}130 GPa for single-shocked samples pre-compressed to 1 GPa. This electronic conduction provides an additional contribution to the conductivity required for magnetic field generation in Icy Giant planets like Uranus and Neptune.

  16. Improving friction performance of cast iron by laser shock peening

    Science.gov (United States)

    Feng, Xu; Zhou, Jianzhong; Huang, Shu; Sheng, Jie; Mei, Yufen; Zhou, Hongda

    2015-05-01

    According to different purpose, some high or low friction coefficient of the material surface is required. In this study, micro-dent texture was fabricated on cast iron specimens by a set of laser shock peening (LSP) experiments under different laser energy, with different patterns of micro dimples in terms of the depth over diameter. The mechanism of LSP was discussed and surface morphology of the micro dimples were investigated by utilizing a Keyence KS-1100 3D optical surface profilometer. The tests under the conditions of dry and lubricating sliding friction were accomplished on the UMT-2 apparatus. The performance of treated samples during friction and wear tests were characterized and analyzed. Based on theoretical analysis and experimental study, friction performance of textured and untextured samples were studied and compared. Morphological characteristics were observed by scanning electron microscope (SEM) and compared after friction tests under dry condition. The results showed that friction coefficient of textured samples were obvious changed than smooth samples. It can be seen that LSP is an effective way to improve the friction performance of cast iron by fabricating high quality micro dimples on its surface, no matter what kind of engineering application mentioned in this paper.

  17. Time-resolved lattice measurements of shock-induced phase transitions in polycrystalline materials

    Science.gov (United States)

    Milathianaki, Despina

    The response of materials under extreme temperature and pressure conditions is a topic of great significance because of its relevance in astrophysics, geophysics, and inertial confinement fusion. In recent years, environments exceeding several hundred gigapascals in pressure have been produced in the laboratory via laser-based dynamic loading techniques. Shock-loading is of particular interest as the shock provides a fiducial for measuring time-dependent processes in the lattice such as phase transitions. Time-resolved x-ray diffraction is the only technique that offers an insight into these shock-induced processes at the relevant spatial (atomic) and temporal scales. In this study, nanosecond resolution x-ray diffraction techniques were developed and implemented towards the study of shock-induced phase transitions in polycrystalline materials. More specifically, the capability of a focusing x-ray diffraction geometry in high-resolution in situ lattice measurements was demonstrated by probing shock-compressed Cu and amorphous metallic glass samples. In addition, simultaneous lattice and free surface velocity measurements of shock-compressed Mg in the ambient hexagonal close packed (hcp) and shock-induced body centered cubic (bcc) phases between 12 and 45 GPa were performed. These measurements revealed x-ray diffraction signals consistent with a compressed bcc lattice above a shock pressure of 26.2+/-1.3 GPa, thus capturing for the first time direct lattice evidence of a shock-induced hcp to bcc phase transition in Mg. Our measurement of the hcp-bcc phase boundary in Mg was found to be consistent with the calculated boundary from generalized pseudopotential theory in the pressure and temperature region intersected by the principal shock Hugoniot. Furthermore, the subnanosecond timescale of the phase transition implied by the shock-loading conditions was in agreement with the kinetics of a martensitic transformation. In conclusion, we report on the progress and

  18. Thomson scattering measurement of a shock in laser-produced counter-streaming plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Morita, T.; Kuramitsu, Y.; Moritaka, T. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Sakawa, Y.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Tomita, K.; Nakayama, K.; Inoue, K.; Uchino, K. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Ide, T.; Tsubouchi, K. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishio, K.; Ide, H.; Kuwada, M. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan)

    2013-09-15

    We report the first direct measurement of temporally and spatially resolved plasma temperatures at a shock as well as its spatial structure and propagation in laser-produced counter-streaming plasmas. Two shocks are formed in counter-streaming collisionless plasmas early in time, and they propagate opposite directions. This indicates the existence of counter-streaming collisionless flows to keep exciting the shocks, even though the collisional effects increase later in time. The shock images are observed with optical diagnostics, and the upstream and downstream plasma parameters of one of the shocks are measured using Thomson scattering technique.

  19. Shock Induced Starting of Gasdynamic Laser Nozzles.

    Science.gov (United States)

    1977-12-01

    Operating Frequency, Hertz y Ratio of Specific Heat at Constant Pressure to Specific Heat at Constant Volume Hg Mercury hir Measured Mercury Manometer Column...Heraeus type E-70 vacuum pump and measured with a mercury manometer . Minimum attainable pressure was approximately 2.0 inches of mercury absolute. The...P4/ . Atm Pressurization P I Bleed Valve P Valve Gage Atm Shutoff P4 Bleed Valve Valve P Gage Shutoff Valve P4 Gage P 1 Mercury Manometer 0-30 in Hg

  20. Examination of KNK437- and quercetin-mediated inhibition of heat shock-induced heat shock protein gene expression in Xenopus laevis cultured cells.

    Science.gov (United States)

    Manwell, Laurie A; Heikkila, John J

    2007-11-01

    We examined the effect of quercetin (3,3',4',5,7-pentahydroxyflavon) and KNK437 (N-formyl-3,4-methylenedioxy-benzylidene-gamma-butyrolactam), a benzylidene lactam compound, on heat-induced heat shock protein (hsp) gene expression in Xenopus laevis A6 kidney epithelial cells. In previous studies, both quercetin and KNK437 inhibited heat shock factor activity resulting in a repression of hsp mRNA and protein accumulation in human cultured cells. In this first study of the effect of these hsp gene expression inhibitors in a non-mammalian cell line, we report that both quercetin and KNK437 reduced the heat shock-induced accumulation of hsp30, hsp47 and hsp70 mRNA in X. laevis cultured cells. However, these inhibitors had no effect on the relative level of a non-heat shock protein mRNA, ef1alpha, in either control or heat shocked cells. Western blot and immunocytochemical analyses revealed that quercetin partially inhibited HSP30 protein accumulation. In contrast, HSP30 protein was not detectable in KNK437-treated cells. Finally, treatment of A6 cells with KNK437 inhibited the heat shock-induced acquisition of thermotolerance, as determined by preservation of actin filaments and cellular morphology using immunocytochemistry and laser scanning confocal microscopy.

  1. Treatment of Laser-Induced Retinal Injuries

    Science.gov (United States)

    1989-06-29

    Distribution List (enclosed) bI’TF rruIoN STATEMEN A Approved for publi reljaso Disatbunon Unlimited TREATMENT OF LASER-INDUCED RETINAL INJURIES FINAL...suprathreshold retinal laser lesions II. Subthreshold retinal laser lesions III. Effect of steroid treatment on laser-induced retinal injury Discussion and...In the present study we investigated the effect of corticosteroid treatment of argon laser-induced retinal injury on vitreal accumulation of both

  2. Chromosome Behavior of Heat Shock Induced Triploid in Fenneropenaeus Chinensis

    Institute of Scientific and Technical Information of China (English)

    张晓军; 李富花; 相建海

    2003-01-01

    Triploidy was induced in Chinese shrimp Fenneropenaeus chinensis by 30 + 0.5 ℃ heat shock treatment (initiated at 20 min after fertilization) for 10 min to inhibit the release of PB2 at 18.0℃ . The highest triploid rate obtained was 84.5% in nauplius stage. The effect of heat shock treatment on meiosis and cleavage of eggs was investigated in this work aimed to establish ef ficient procedures for triploid induction and to gain understanding of the mechanism of triploid production. Three pronuclei that could be observed in the treated eggs under fluorescence microscope developed into triploid embryos. Some abnormal chromosome behavior was observed in heat shocked eggs.

  3. Shock Wave Induced Separation Control by Streamwise Vortices

    Institute of Scientific and Technical Information of China (English)

    Ryszard SZWABA

    2005-01-01

    Control of shock wave and boundary layer interaction finds still a lot of attention. Methods of this interaction control have been especially investigated in recent decade. This research was mostly concerned with flows without separation. However, in many applications shock waves induce separation often leads to strong unsteady effects. In this context it is proposed to use streamwise vortices for the interaction control. The results of experimental investigations are presented here. The very promising results were obtained, meaning that the incipient separation was postponed and the separation size was reduced for the higher Mach numbers. The decrease of the RMS of average shock wave oscillation was also achieved.

  4. Increased expression of heat shock protein 70 and heat shock factor 1 in chronic dermal ulcer tissues treated with laser-aided therapy

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jian-da; LUO Cheng-qun; XIE Hui-qing; NIE Xin-min; ZHAO Yan-zhong; WANG Shao-hua; XU Yi; Pashupati Babu Pokharel; XU Dan

    2008-01-01

    Background Chronic dermal ulcers are also referred to as refractory ulcers, This study was conducted to elucidate the therapeutic effect of laser on chronic dermal ulcers and the induced expression of heat shock factor 1 (HSF1) and heat shock protein 70 (HSP70) in wound tissues.Methods Sixty patients with 84 chronic dermal ulcers were randomly divided into traditional therapy and laser therapy groups. Laser treatment was performed in addition to traditional therapy in the laser therapy group. The treatment efficacy was evaluated after three weeks. Five tissue sections of healing wounds were randomly collected along with five normal skin sections as controls. HSP70-positive cells from HSP70 immunohistochemical staining were counted and the gray scale of positive cells was measured for statistical analysis. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to determine the mRNA and protein expressions of HSF1 and HSP70.Results The cure rate of the wounds and the total efficacy in the laser therapy group were significantly higher than those in the traditional therapy group (P<0.05, P<0.01, respectively). Immunohistochemical staining revealed that the HSP70-positive cell count was significantly higher in laser therapy group than those in the traditional therapy group and controls (P<0.01), and the gray scale of the cell signal was obviously lower than traditional therapy group and controls (P <0.05). By contrast, the traditional therapy group and the control group were not significantly different. The RNA levels of HSF1 and HSP70 were higher in the laser therapy group by RT-PCR, but very low in normal skin and the traditional therapy group. The analysis on the gray scale of the Western blot bands indicated that the expression of HSF1 and HSP70 in the laser therapy group was significantly higher than in the traditional therapy group and the control group (P <0.01), and the expression in the traditional therapy group was also

  5. Collisionless shocks and particle acceleration in laser-driven laboratory plasmas

    Science.gov (United States)

    Fiuza, Frederico

    2012-10-01

    Collisionless shocks are pervasive in space and astrophysical plasmas, from the Earth's bow shock to Gamma Ray Bursters; however, the microphysics underlying shock formation and particle acceleration in these distant sites is not yet fully understood. Mimicking these extreme conditions in laboratory is a grand challenge that would allow for a better understanding of the physical processes involved. Using ab initio multi-dimensional particle-in-cell simulations, shock formation and particle acceleration are investigated for realistic laboratory conditions associated with the interaction of intense lasers with high-energy-density plasmas. Weibel-instability-mediated shocks are shown to be driven by the interaction of an ultraintense laser with overcritical plasmas. In this piston regime, the laser generates a relativistic flow that is Weibel unstable. The strong Weibel magnetic fields deflect the incoming flow, compressing it, and forming a shock. The resulting shock structure is consistent with previous simulations of relativistic astrophysical shocks, demonstrating for the first time the possibility of recreating these structures in laboratory. As the laser intensity is decreased and near-critical density plasmas are used, electron heating dominates over radiation pressure and electrostatic shocks can be formed. The electric field associated with the shock front can reflect ions from the background accelerating them to high energies. It is shown that high quality 200 MeV proton beams, required for tumor therapy, can be generated by using an exponentially decaying plasma profile to control competing accelerating fields. These results pave the way for the experimental exploration of space and astrophysical relevant shocks and particle acceleration with current laser systems.

  6. Intermittency and Topology of Shock Induced Mixing

    Science.gov (United States)

    Tellez, Jackson; Redondo, Jose M.; Ben Mahjoub, Otman; Malik, Nadeem; Vila, Teresa

    2016-04-01

    The advance of a Rayleigh-Taylor front is described in Linden & Redondo (1991),[1-3] and may be shown to follow a quadratic law in time where the width of the growing region of instability depends on the local mixing efficiency of the different density fluids that accelerate against each other g is the acceleration and A is the Atwood number defined as the diference of densities divided by their sum. This results show the independence of the large amplitude structures on the initial conditions the width of the mixing region depends also on the intermittency of the turbulence. Then dimensional analysis may also depend on the relevant reduced acceleration driven time and the molecular reactive time akin to Damkholer number and the fractal structure of the contact zone [2,4]. Detailed experiments and simulations on RT and RM shock induced fronts analized with respect to structure functions are able to determine which mechanisms are most effective in local mixing which increase the effective fractal dimension, as well as the effect of higher order geometrical parameters, such as the structure functions, in non-homogeneous fluids (Mahjoub et al 1998)[5]. The structure of a Mixing blob shows a relatively sharp head with most of the mixing taking place at the sides due to what seems to be shear instability very similar to the Kelvin-Helmholtz instabilities, but with sideways accelerations. The formation of the blobs and spikes with their secondary instabilities produces a turbulent cascade, evident just after about 1 non-dimensional time unit, from a virtual time origin that takes into account the linear growth phase, as can be seen by the growth of the fractal dimension for different volume fractions. Two-dimensional cuts of the 3D flow also show that vortex flows have closed or spiral streamlines around their core. Examples of such flows can be also seen in the laboratory, for example at the interface of atwo-layer stratified fluid in a tank in which case streamlines

  7. Temperature measurement using ultraviolet laser absorption of carbon dioxide behind shock waves.

    Science.gov (United States)

    Oehlschlaeger, Matthew A; Davidson, David F; Jeffries, Jay B

    2005-11-01

    A diagnostic for microsecond time-resolved temperature measurements behind shock waves, using ultraviolet laser absorption of vibrationally hot carbon dioxide, is demonstrated. Continuous-wave laser radiation at 244 and 266 nm was employed to probe the spectrally smooth CO2 ultraviolet absorption, and an absorbance ratio technique was used to determine temperature. Measurements behind shock waves in both nonreacting and reacting (ignition) systems were made, and comparisons with isentropic and constant-volume calculations are reported.

  8. Picosecond Laser Shock Peening of Nimonic 263 at 1064 nm and 532 nm Wavelength

    Directory of Open Access Journals (Sweden)

    Sanja Petronic

    2016-02-01

    Full Text Available The paper presents a study on the surface modifications of nickel based superalloy Nimonic 263 induced by laser shock peening (LSP process. The process was performed by Nd3+:Yttrium Aluminium Garnet (YAG picosecond laser using the following parameters: pulse duration 170 ps; repetition rate 10 Hz; pulse numbers of 50, 100 and 200; and wavelength of 1064 nm (with pulse energy of 2 mJ, 10 mJ and 15 mJ and 532 nm (with pulse energy of 25 mJ, 30 mJ and 35 mJ. The following response characteristics were analyzed: modified surface areas obtained by the laser/material interaction were observed by scanning electron microscopy; elemental composition of the modified surface was evaluated by energy-dispersive spectroscopy (EDS; and Vickers microhardness tests were performed. LSP processing at both 1064 nm and 532 nm wavelengths improved the surface structure and microhardness of a material. Surface morphology changes of the irradiated samples were determined and surface roughness was calculated. These investigations are intended to contribute to the study on the level of microstructure and mechanical properties improvements due to LSP process that operate in a picosecond regime. In particular, the effects of laser wavelength on the microstructural and mechanical changes of a material are studied in detail.

  9. The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

    Directory of Open Access Journals (Sweden)

    Yinghong Li, Liucheng Zhou, Weifeng He, Guangyu He, Xuede Wang, Xiangfan Nie, Bo Wang, Sihai Luo and Yuqin Li

    2013-01-01

    Full Text Available We investigated the strengthening mechanism of laser shock processing (LSP at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation.

  10. Heterogeneous nuclear ribonucleoprotein K inhibits heat shock-induced transcriptional activity of heat shock factor 1.

    Science.gov (United States)

    Kim, Hee-Jung; Lee, Jae-Jin; Cho, Jin-Hwan; Jeong, Jaeho; Park, A Young; Kang, Wonmo; Lee, Kong-Joo

    2017-08-04

    When cells are exposed to heat shock and various other stresses, heat shock factor 1 (HSF1) is activated, and the heat shock response (HSR) is elicited. To better understand the molecular regulation of the HSR, we used 2D-PAGE-based proteome analysis to screen for heat shock-induced post-translationally modified cellular proteins. Our analysis revealed that two protein spots typically present on 2D-PAGE gels and containing heterogeneous nuclear ribonucleoprotein K (hnRNP K) with trioxidized Cys(132) disappeared after the heat shock treatment and reappeared during recovery, but the total amount of hnRNP K protein remained unchanged. We next tested whether hnRNP K plays a role in HSR by regulating HSF1 and found that hnRNP K inhibits HSF1 activity, resulting in reduced expression of hsp70 and hsp27 mRNAs. hnRNP K also reduced binding affinity of HSF1 to the heat shock element by directly interacting with HSF1 but did not affect HSF1 phosphorylation-dependent activation or nuclear localization. hnRNP K lost its ability to induce these effects when its Cys(132) was substituted with Ser, Asp, or Glu. These findings suggest that hnRNP K inhibits transcriptional activity of HSF1 by inhibiting its binding to heat shock element and that the oxidation status of Cys(132) in hnRNP K is critical for this inhibition. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Effect of Laser Shock Peening on surface properties and residual stress of Al6061-T6

    Science.gov (United States)

    Salimianrizi, A.; Foroozmehr, E.; Badrossamay, M.; Farrokhpour, H.

    2016-02-01

    The purpose of this study is to investigate the effects of Laser Shock Peening (LSP) on Al 6061-T6. The confined LSP regime using Nd: YAG laser with 1200 mJ of energy per pulse and 8 ns of pulse width were applied. The treated specimens were evaluated by means of surface integrity with optical microscopy, scanning electron microscope, microhardness, surface roughness and induced residual stress using an X-ray diffraction method. Results showed that by the use of LSP, compressive residual stress could effectively be induced on the surface of treated material. It was also revealed that the hardened depth of the material, up to a maximum depth of 1875 μm, could be achieved due to work hardening and grain refinement. In addition, surface roughness measurements showed that the LSP could deteriorate surface quality depending on the LSP parameters. The influences of beam overlap rates, number of laser shots and scanning pattern on microhardness as well as surface roughness are discussed.

  12. Shock-induced turbulent flow in baffle systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A.L. [Lawrence Livermore National Lab., CA (United States); Reichenbach, H. [Fraunhofer-Institut fuer Kurzzeitdynamik - Ernst-Mach-Institut (EMI), Freiburg im Breisgau (Germany)

    1993-07-01

    Experiments are described on shock propagation through 2-D aligned and staggered baffle systems. Flow visualization was provided by shadow and schlieren photography, recorded by the Cranz-Schardin camera. Also single-frame, infinite-fringe, color interferograms were used. Intuition suggests that this is a rather simple 2-D shock diffraction problem. However, flow visualization reveals that the flow rapidly evolved into a complex 3-D turbulent mixing problem. Mushroom-shaped mixing regions blocked the flow into the next baffle orifice. Thus energy was transferred from the directed kinetic energy (induced by the shock) to rotational energy of turbulent mixing, and then dissipated by molecular effects. These processes dramatically dissipate the strength of the shock wave. The experiments provide an excellent test case that could be used to assess the accuracy of computer code calculations of such problems.

  13. Mechanisms of shock-induced reactions in high explosives

    Science.gov (United States)

    Kay, Jeffrey J.

    2017-01-01

    Understanding the mechanisms by which shock waves initiate chemical reactions in explosives is key to understanding their unique and defining property: the ability to undergo rapid explosive decomposition in response to mechanical stimulus. Although shock-induced reactions in explosives have been studied experimentally and computationally for decades, the nature of even the first chemical reactions that occur in response to shock remain elusive. To predictively understand how explosives respond to shock, the detailed sequence of events that occurs - mechanical deformation, energy transfer, bond breakage, and first chemical reactions - must be understood at the quantum-mechanical level. This paper reviews recent work in this field and ongoing experimental and theoretical work at Sandia National Laboratories in this important area of explosive science.

  14. Ultra-intense laser-plasma interaction toward Weibel-mediated collisionless shocks formation

    Science.gov (United States)

    Grassi, Anna; Grech, M.; Amiranoff, F.; Macchi, A.; Riconda, C.

    2016-10-01

    The rapid developments in laser technology will soon offer the opportunity to study in the laboratory the processes driving Weibel-mediated collisionless shocks, typical of various astrophysical scenarii. The interaction of an ultra-intense laser with an overdense plasma has been identified as the preferential configuration. Yet, the experimental requirements still need to be properly investigated. High performance computing simulations are a necessary tool for this study. In this work, we present a series of kinetic simulations performed with the PIC code SMILEI, varying the laser and plasma parameters. In particular, we will study the effect of the laser polarisation and plasma density to obtain the best conditions for the creation of a collisionless shock. The role of the electrons heated at the interaction surface and of particles accelerated via the Hole Boring (laser-piston) mechanism on the generation of the current filamentation instability and the subsequent shock front formation will be highlighted.

  15. Exploration of the fragmentation of laser shock-melted aluminum using x-ray backlighting

    Science.gov (United States)

    Zhang, Lin; Li, Ying-Hua; Li, Xue-Mei; Ye, Xiang-Ping; Zhang, Zu-Gen; Cheng, Jin-Ming; Cai, Ling-Cang

    2016-05-01

    The fragmentation of shock-melted metal material is an important scientific problem in shock physics and is suitable for experimentally investigating by the laser-driven x-ray backlighting technique. This letter reports on the exploration of laser shock-melted aluminum fragmentation by means of x-ray backlighting at the SGII high energy facility in China. High-quality and high-resolution radiographs with negligible motion blur were obtained and these images enabled analysis of the mass distribution of the fragmentation product.

  16. Kinetics of shock-induced polymorphic phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, D.B.

    1976-01-01

    Shock-loading induces polymorphic phase transitions in some solids if the pressure exceeds that at which phase transition occurs under quasi-static compression. Volume changes in shock-induced transitions must occur very rapidly to produce the structured shock waves observed, so transition rates are large under these dynamic conditions. By contrast, the same transition might require minutes or hours under quasi-static loading. If shock-induced transition is so rapid that kinetic effects can be ignored, a steady two-wave structure is propagated. The first wave, of amplitude equal to the transition pressure, shocks the material to the phase boundary but produces no transition; the second, slower wave produces the transformed phase. When kinetic effects are important, this two-wave structure does not form immediately but by an evolutionary process which produces transients in the amplitudes and rise times of the stress waves. By measuring these transient effects, some facts about the kinetics of phase transitions have been inferred. Comprehensive studies on phase-transition kinetics in antimony, iron, and potassium chloride are described, with emphasis on a thermodynamic description of the intermediate states during transition. Complicating effects such as shear strength and wave perturbations due to free surfaces are discussed.

  17. Effect of Multipath Laser Shock Processing on Microhardness, Surface Roughness, and Wear Resistance of 2024-T3 Al Alloy

    Directory of Open Access Journals (Sweden)

    Abdulhadi Kadhim

    2014-01-01

    Full Text Available Laser shock processing (LSP is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. LSP is based on the application of a high intensity pulsed laser beam (I>1 GW/cm2;  t<50 ns at the interface between the metallic target and the surrounding medium (a transparent confining material, normally water forcing a sudden vaporization of the metallic surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The shock wave induces plastic deformation and a residual stress distribution in the target material. In this paper we study the increase of microhardness and surface roughness with the increase of laser pulse energy in 2024-T3 Al alloy. The influence of the thickness of the confining layer (water on microhardness and surface roughness is also studied. In addition, the effect of LSP treatment with best conditions on wear behaviors of the alloy was investigated.

  18. Weibel instability mediated collisionless shocks using intense laser-driven plasmas

    Science.gov (United States)

    Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald; Fernandez, Juan; Ma, Wenjun; Schreiber, Jorg; LANL Collaboration; LMU Team

    2016-10-01

    The origin of cosmic rays remains a long-standing challenge in astrophysics and continues to fascinate physicists. It is believed that ``collisionless shocks'' - where the particle Coulomb mean free path is much larger that the shock transition - are a dominant source of energetic cosmic rays. These shocks are ubiquitous in astrophysical environments such as gamma-ray bursts, supernova remnants, pulsar wind nebula and coronal mass ejections from the sun. Several spacecraft observations have revealed acceleration of charged particles, mostly electrons, to very high energies with in the shock front. There is now also clear observational evidence that supernova remnant shocks accelerate both protons and electrons. The understanding of the microphysics behind collisionless shocks and their particle acceleration is tightly related with nonlinear basic plasma processes and remains a grand challenge. In this poster, we will present results from recent experiments at the LANL Trident laser facility studying collisionless shocks using intense ps laser (80J, 650 fs - peak intensity of 1020 W/cm2) driven near-critical plasmas using carbon nanotube foam targets. A second short pulse laser driven protons from few microns thick aluminum foil is used to image the laser-driven plasma.

  19. A piston-actuated shock-tube, with laser-Schlieren diagnostics

    Science.gov (United States)

    Hurst, S. M.; Bauer, S. H.

    1993-01-01

    The essential construction features of a piston actuated shock tube are described, and its advantages relative to the conventional use of diaphragm ruptures for shock initiation are listed. Typical operational parameters are presented to illustrate the levels of reproducibility achieved. Tests with He and N2 drivers into about 99 percent Ar covered shock speeds from 1.539 +/- 0.002-0.8143 +/- 0.002 mm/microsec, corresponding to 2390-847 K incident shock temperatures. Application of this tube for recording postshock front density gradients of the endoergic dissociation of ethane and the exoergic condensation of iron atoms via the laser-Schlieren technique is described.

  20. Laser-induced tobacco protoplast fusion

    Institute of Scientific and Technical Information of China (English)

    李银妹; 关力劼; 楼立人; 崔国强; 姚湲; 王浩威; 操传顺; 鲁润龙; 陈曦

    1999-01-01

    Laser tweezers can manipulate small particles, such as cells and organdies. When coupling them with laser microbeam selective fusion of two tobacco protoplasts containing some chloroplast was achieved. Physical and biological variables that affect laser trapping and laser-induced fusion were also discussed. The results show that the effect of chloroplast content and distribution on the yield of cell fusion is remarkable.

  1. Studying astrophysical collisionless shocks with counterstreaming plasmas from high power lasers

    Science.gov (United States)

    Park, Hye-Sook; Ryutov, D. D.; Ross, J. S.; Kugland, N. L.; Glenzer, S. H.; Plechaty, C.; Pollaine, S. M.; Remington, B. A.; Spitkovsky, A.; Gargate, L.; Gregori, G.; Bell, A.; Murphy, C.; Sakawa, Y.; Kuramitsu, Y.; Morita, T.; Takabe, H.; Froula, D. H.; Fiksel, G.; Miniati, F.; Koenig, M.; Ravasio, A.; Pelka, A.; Liang, E.; Woolsey, N.; Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.

    2012-03-01

    Collisions of high Mach number flows occur frequently in astrophysics, and the resulting shock waves are responsible for the properties of many astrophysical phenomena, such as supernova remnants, Gamma Ray Bursts and jets from Active Galactic Nuclei. Because of the low density of astrophysical plasmas, the mean free path due to Coulomb collisions is typically very large. Therefore, most shock waves in astrophysics are "collisionless", since they form due to plasma instabilities and self-generated magnetic fields. Laboratory experiments at the laser facilities can achieve the conditions necessary for the formation of collisionless shocks, and will provide a unique avenue for studying the nonlinear physics of collisionless shock waves. We are performing a series of experiments at the Omega and Omega-EP lasers, in Rochester, NY, with the goal of generating collisionless shock conditions by the collision of two high-speed plasma flows resulting from laser ablation of solid targets using ˜1016 W/cm2 laser irradiation. The experiments will aim to answer several questions of relevance to collisionless shock physics: the importance of the electromagnetic filamentation (Weibel) instabilities in shock formation, the self-generation of magnetic fields in shocks, the influence of external magnetic fields on shock formation, and the signatures of particle acceleration in shocks. Our first experiments using Thomson scattering diagnostics studied the plasma state from a single foil and from double foils whose flows collide "head-on". Our data showed that the flow velocity and electron density were 108 cm/s and 1019 cm-3, respectively, where the Coulomb mean free path is much larger than the size of the interaction region. Simulations of our experimental conditions show that weak Weibel mediated current filamentation and magnetic field generation were likely starting to occur. This paper presents the results from these first Omega experiments.

  2. Intensity improvement of shock waves induced by liquid electrical discharges

    Science.gov (United States)

    Liu, Yi; Li, Zhi-Yuan; Li, Xian-Dong; Liu, Si-Wei; Zhou, Gu-Yue; Lin, Fu-Chang

    2017-04-01

    When shock waves induced by pulsed electrical discharges in dielectric liquids are widely applied in industrial fields, it is necessary to improve the energy transfer efficiency from electrical energy to mechanical energy to improve the shock wave intensity. In order to investigate the effect of the plasma channel length created by the liquid electrical discharge on the shock wave intensity, a test stand of dielectric liquid pulsed electrical discharge is designed and constructed. The main capacitor is 3 μF, and the charging voltage is 0-30 kV. Based on the needle-needle electrode geometry with different gap distances, the intensities of shock waves corresponding to the electrical parameters, the relationship between the plasma channel length and the deposited energy, and the time-resolved observation of the plasma channel development by a high speed camera are presented and compared. The shock wave intensity is closely related to the power and energy dissipated into the plasma channel. The longer plasma channel and the quicker arc expansion can lead to a higher power and energy deposited into the plasma channel, which can activate a stronger shock wave.

  3. Prediction of Shock-Induced Cavitation in Water

    Science.gov (United States)

    Brundage, Aaron

    2013-06-01

    Fluid-structure interaction problems that require estimating the response of thin structures within fluids to shock loading has wide applicability. For example, these problems may include underwater explosions and the dynamic response of ships and submarines; and biological applications such as Traumatic Brain Injury (TBI) and wound ballistics. In all of these applications the process of cavitation, where small cavities with dissolved gases or vapor are formed as the local pressure drops below the vapor pressure due to shock hydrodynamics, can cause significant damage to the surrounding thin structures or membranes if these bubbles collapse, generating additional shock loading. Hence, a two-phase equation of state (EOS) with three distinct regions of compression, expansion, and tension was developed to model shock-induced cavitation. This EOS was evaluated by comparing data from pressure and temperature shock Hugoniot measurements for water up to 400 kbar, and data from ultrasonic pressure measurements in tension to -0.3 kbar, to simulated responses from CTH, an Eulerian, finite volume shock code. The new EOS model showed significant improvement over pre-existing CTH models such as the SESAME EOS for capturing cavitation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy/NNSA under contract DE-AC04-94AL85000.

  4. Nanosecond x-ray Laue diffraction apparatus suitable for laser shock compression experiments.

    Science.gov (United States)

    Suggit, Matthew; Kimminau, Giles; Hawreliak, James; Remington, Bruce; Park, Nigel; Wark, Justin

    2010-08-01

    We have used nanosecond bursts of x-rays emitted from a laser-produced plasma, comprised of a mixture of mid-Z elements, to produce a quasiwhite-light spectrum suitable for performing Laue diffraction from single crystals. The laser-produced plasma emits x-rays ranging in energy from 3 to in excess of 10 keV, and is sufficiently bright for single shot nanosecond diffraction patterns to be recorded. The geometry is suitable for the study of laser-shocked crystals, and single-shot diffraction patterns from both unshocked and shocked silicon crystals are presented.

  5. CREBH determines the severity of sulpyrine-induced fatal shock.

    Directory of Open Access Journals (Sweden)

    Naganori Kamiyama

    Full Text Available Although the pyrazolone derivative sulpyrine is widely used as an antipyretic analgesic drug, side effects, including fatal shock, have been reported. However, the molecular mechanism underlying such a severe side effect is largely unclear. Here, we report that the transcription factor CREBH that is highly expressed in the liver plays an important role in fatal shock induced by sulpyrine in mice. CREBH-deficient mice were resistant to experimental fatal sulpyrine shock. We found that sulpyrine-induced expression of cytochrome P450 2B (CYP2B family genes, which are involved in sulpyrine metabolism, in the liver was severely impaired in CREBH-deficient mice. Moreover, introduction of CYP2B in CREBH-deficient liver restored susceptibility to sulpyrine. Furthermore, ectopic expression of CREBH up-regulated CYP2B10 promoter activity, and in vivo knockdown of CREBH in wild-type mice conferred a significant resistance to fatal sulpyrine shock. These data demonstrate that CREBH is a positive regulator of CYP2B in response to sulpyrine administration, which possibly results in fatal shock.

  6. Analyzing the effect of high repetition laser shock peening on dynamic corrosion rate of magnesium

    Science.gov (United States)

    Caralapatti, Vinodh Krishna; Narayanswamy, Sivakumar

    2017-08-01

    Magnesium as implant material is being investigated extensively due to its superior suitability. With corrosion rate being the major obstacle, this paper aims to determine the effects of high repetition laser shock peening (HRLSP) on the dynamic corrosion rate of magnesium. While there is lot of research on corrosion of magnesium, in this work, a specially designed test bench was used for characterization of dynamic corrosion to mimic the physiological conditions experienced by the implant inside human body. From the results, it can be inferred that corrosion rate of peened samples reduced by at least 6 times compared to unpeened sample and sample peened with 66% overlap 1 scans exhibited the least corrosion. The wettability of the samples was also determined as a measure to analyze the effects of HRLSP on biocompatibility. In addition, peening is seen to induce surface corrosion, which minimizes the risks of implant failure.

  7. Experiment on laser interaction with a planar target for conditions relevant to shock ignition

    Science.gov (United States)

    Maheut, Y.; Antonelli, L.; Atzeni, S.; Badziak, J.; Baffigi, F.; Batani, D.; Cecchetti, C.; Chodukowski, T.; Consoli, F.; Cristoforetti, G.; De Angelis, R.; Folpini, G.; Gizzi, L. A.; Kalinowska, Z.; Kucharik, M.; Köster, P.; Krousky, E.; Labate, L.; Levato, T.; Liska, R.; Malka, G.; Marocchino, A.; Nicolaï, P.; O'Dell, T.; Parys, P.; Pisarczyk, T.; Rączka, P.; Renner, O.; Rhee, Y. J.; Ribeyre, X.; Richetta, M.; Rosinski, M.; Ryć, L.; Skala, J.; Schiavi, A.; Schurtz, G.; Smid, M.; Spindloe, C.; Ullschmied, J.; Wolowski, J.; Zaraś, A.

    2014-05-01

    We report the experiment conducted on the Prague Asterix Laser System (PALS) laser facility dedicated to make a parametric study of the laser-plasma interaction under the physical conditions corresponding to shock ignition thermonuclear fusion reactions. Two laser beams have been used: the auxiliary beam, for preplasma creation on the surface of a plastic foil, and the main beam to launch a strong shock. The ablation pressure is inferred from the volume of the crater in the Cu layer situated behind the plastic foil and by shock breakout chronometry. The population of fast electrons is analyzed by Kα emission spectroscopy and imaging. The preplasma is characterized by three-frame interferometry, x-ray spectroscopy and ion diagnostics. The numerical simulations constrained with the measured data gave a maximum pressure in the plastic layer of about 90 Mbar.

  8. Laser driven single shock compression of fluid deuterium from 45 to 220 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, D; Boehly, T; Celliers, P; Eggert, J; Moon, S; Meyerhofer, D; Collins, G

    2008-03-23

    The compression {eta} of liquid deuterium between 45 and 220 GPa under laser-driven shock loading has been measured using impedance matching to an aluminum (Al) standard. An Al impedance match model derived from a best fit to absolute Hugoniot data has been used to quantify and minimize the systematic errors caused by uncertainties in the high-pressure Al equation of state. In deuterium below 100 GPa results show that {eta} {approx_equal} 4.2, in agreement with previous impedance match data from magnetically-driven flyer and convergent-explosive shock wave experiments; between 100 and 220 GPa {eta} reaches a maximum of {approx}5.0, less than the 6-fold compression observed on the earliest laser-shock experiments but greater than expected from simple extrapolations of lower pressure data. Previous laser-driven double-shock results are found to be in good agreement with these single-shock measurements over the entire range under study. Both sets of laser-shock data indicate that deuterium undergoes an abrupt increase in compression at around 110 GPa.

  9. Effects of laser polarization on electrostatic shock ion acceleration in near-critical plasmas

    Science.gov (United States)

    Kim, Young-Kuk; Kang, Teyoun; Hur, Min Sup

    2016-10-01

    Ion acceleration from laser-driven collisionless electrostatic shock (CES) is attracting much attention, as quasi-monoenergetic, tens of MeV ion beams are expected to be available from relatively moderate laser power and near-critical density plasmas. For generation of a high-speed shock by a laser pulse, it is important to compress a high-contrast density layer by hole-boring process, and to heat the electrons in the upstream, where the hole-boring speed should match the Mach number condition 1.5 boring speed is higher in lower density plasmas, we observed consistently higher speed of the shock and accelerated ion energy when driven by CP pulses. Interesting point is that the CP-shock generation is determined predominantly by the transmittance only, while the LP-shock formation depends on other parameters such as plasma scale length. In 2D simulations, we found that Weibel instability is less effective in CP than LP, which enables more stable shock formation for given conditions of the laser and plasma. This work was supported by the Basic Science Research Program (NRF-2013R1A1A2006353) and the Creative Allied Project (CAP-15-06-ETRI).

  10. Recent results from experimental studies on laser-plasma coupling in a shock ignition relevant regime

    Science.gov (United States)

    Koester, P.; Antonelli, L.; Atzeni, S.; Badziak, J.; Baffigi, F.; Batani, D.; Cecchetti, C. A.; Chodukowski, T.; Consoli, F.; Cristoforetti, G.; De Angelis, R.; Folpini, G.; Gizzi, L. A.; Kalinowska, Z.; Krousky, E.; Kucharik, M.; Labate, L.; Levato, T.; Liska, R.; Malka, G.; Maheut, Y.; Marocchino, A.; Nicolai, P.; O'Dell, T.; Parys, P.; Pisarczyk, T.; Raczka, P.; Renner, O.; Rhee, Y. J.; Ribeyre, X.; Richetta, M.; Rosinski, M.; Ryc, L.; Skala, J.; Schiavi, A.; Schurtz, G.; Smid, M.; Spindloe, C.; Ullschmied, J.; Wolowski, J.; Zaras, A.

    2013-12-01

    Shock ignition (SI) is an appealing approach in the inertial confinement scenario for the ignition and burn of a pre-compressed fusion pellet. In this scheme, a strong converging shock is launched by laser irradiation at an intensity Iλ2 > 1015 W cm-2 µm2 at the end of the compression phase. In this intensity regime, laser-plasma interactions are characterized by the onset of a variety of instabilities, including stimulated Raman scattering, Brillouin scattering and the two plasmon decay, accompanied by the generation of a population of fast electrons. The effect of the fast electrons on the efficiency of the shock wave production is investigated in a series of dedicated experiments at the Prague Asterix Laser Facility (PALS). We study the laser-plasma coupling in a SI relevant regime in a planar geometry by creating an extended preformed plasma with a laser beam at ˜7 × 1013 W cm-2 (250 ps, 1315 nm). A strong shock is launched by irradiation with a second laser beam at intensities in the range 1015-1016 W cm-2 (250 ps, 438 nm) at various delays with respect to the first beam. The pre-plasma is characterized using x-ray spectroscopy, ion diagnostics and interferometry. Spectroscopy and calorimetry of the backscattered radiation is performed in the spectral range 250-850 nm, including (3/2)ω, ω and ω/2 emission. The fast electron production is characterized through spectroscopy and imaging of the Kα emission. Information on the shock pressure is obtained using shock breakout chronometry and measurements of the craters produced by the shock in a massive target. Preliminary results show that the backscattered energy is in the range 3-15%, mainly due to backscattered light at the laser wavelength (438 nm), which increases with increasing the delay between the two laser beams. The values of the peak shock pressures inferred from the shock breakout times are lower than expected from 2D numerical simulations. The same simulations reveal that the 2D effects play a

  11. Time-resolved study of laser initiated shock wave propagation in superfluid 4He

    Science.gov (United States)

    Garcia, Allan; Buelna, Xavier; Popov, Evgeny; Eloranta, Jussi

    2016-09-01

    Intense shock waves in superfluid 4He between 1.7 and 2.1 K are generated by rapidly expanding confined plasma from laser ablation of a metal target immersed in the liquid. The resulting shock fronts in the liquid with initial velocities up to ca. Mach 10 are visualized by time-resolved shadowgraph photography. These high intensity shocks decay within 500 ns into less energetic shock waves traveling at Mach 2, which have their lifetime in the microsecond time scale. Based on the analysis using the classical Rankine-Hugoniot theory, the shock fronts created remain in the solid phase up to 1 μs and the associated thermodynamic state appears outside the previously studied region. The extrapolated initial shock pressure of 0.5 GPa is comparable to typical plasma pressures produced during liquid phase laser ablation. A secondary shock originating from fast heat propagation on the metal surface is also observed and a lower limit estimate for the heat propagation velocity is measured as 7 × 104 m/s. In the long-time limit, the high intensity shocks turn into liquid state waves that propagate near the speed of sound.

  12. Ultraviolet Laser-induced ignition of RDX single crystal

    Science.gov (United States)

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-02-01

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm2. The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique.

  13. Ultrasound induced by CW laser cavitation bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Korneev, N; Montero, P Rodriguez; Ramos-Garcia, R; Ramirez-San-Juan, J C; Padilla-Martinez, J P, E-mail: korneev@inaoep.mx [Instituto Nacional de Astrofisica, Optica y Electronica, Apt. Postal 51 y 216 CP72000, Puebla, Pue. (Mexico)

    2011-01-01

    The generation of ultrasound by a collapsing single cavitation bubble in a strongly absorbing liquid illuminated with a moderate power CW laser is described. The ultrasound shock wave is detected with hydrophone and interferometric device. To obtain a stronger pulse it is necessary to adjust a liquid absorption and a beam diameter. Their influence can be qualitatively understood with a simple model.

  14. Laser-induced damage in optical materials

    CERN Document Server

    Ristau, Detlev

    2014-01-01

    Dedicated to users and developers of high-powered systems, Laser-Induced Damage in Optical Materials focuses on the research field of laser-induced damage and explores the significant and steady growth of applications for high-power lasers in the academic, industrial, and military arenas. Written by renowned experts in the field, this book concentrates on the major topics of laser-induced damage in optical materials and most specifically addresses research in laser damage that occurs in the bulk and on the surface or the coating of optical components. It considers key issues in the field of hi

  15. Simulation of Experiments Generating Collisionless Shocks With Intense Lasers Using the CRASH Code

    Science.gov (United States)

    Grosskopf, M. J.; Drake, R. P.; Kuranz, C. C.; Rutter, E. M.; Park, H. S.; Kugland, N. L.; Pollaine, S.; Ross, J. S.; Remington, B. A.; Ryutov, D.; Spitkovsky, A.; Gargate, L.; Gregori, G.; Bell, A.; Murphy, C.; Sakawa, Y.; Kuramitsu, Y.; Takabe, H.; Froula, D. H.; Fiksel, G.; Miniati, F.; Koenig, M.; Ravasio, A.; Liang, E.; Woosley, N.

    2011-10-01

    Collisionless shocks, shocks generated by plasma wave interactions in regions where the collisional mean-free-path for particles is long compared to the length scale for shock interaction, are found ubiquitously in astrophysics. Experiments to investigate collisionless shocks in a laboratory-scale system are being carried out on intense lasers; measuring the density, temperature, magnetic field, and velocity of counter-streaming flows generated by laser ablation. This poster reports hydrodynamic simulations modeling the ablative flow of plasma generated in order to assess potential designs and infer properties of collected data from previous single foil experiments. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52-08NA28616.

  16. Shock-induced damage in rocks: Application to impact cratering

    Science.gov (United States)

    Ai, Huirong

    Shock-induced damage beneath impact craters is studied in this work. Two representative terrestrial rocks, San Marcos granite and Bedford limestone, are chosen as test target. Impacts into the rock targets with different combinations of projectile material, size, impact angle, and impact velocity are carried out at cm scale in the laboratory. Shock-induced damage and fracturing would cause large-scale compressional wave velocity reduction in the recovered target beneath the impact crater. The shock-induced damage is measured by mapping the compressional wave velocity reduction in the recovered target. A cm scale nondestructive tomography technique is developed for this purpose. This technique is proved to be effective in mapping the damage in San Marcos granite, and the inverted velocity profile is in very good agreement with the result from dicing method and cut open directly. Both compressional velocity and attenuation are measured in three orthogonal directions on cubes prepared from one granite target impacted by a lead bullet at 1200 m/s. Anisotropy is observed from both results, but the attenuation seems to be a more useful parameter than acoustic velocity in studying orientation of cracks. Our experiments indicate that the shock-induced damage is a function of impact conditions including projectile type and size, impact velocity, and target properties. Combined with other crater phenomena such as crater diameter, depth, ejecta, etc., shock-induced damage would be used as an important yet not well recognized constraint for impact history. The shock-induced damage is also calculated numerically to be compared with the experiments for a few representative shots. The Johnson-Holmquist strength and failure model, initially developed for ceramics, is applied to geological materials. Strength is a complicated function of pressure, strain, strain rate, and damage. The JH model, coupled with a crack softening model, is used to describe both the inelastic response of

  17. Comparison of transcatheter laser and direct-current shock ablation of endocardium near tricuspid anulus

    Science.gov (United States)

    Zhang, Yu-Zhen; Wang, Shi-Wen; Li, Junheng

    1993-03-01

    Forty to eighty percent of the patients with accessory pathways (APs) manifest themselves by tachyarrhythmias. Many of these patients needed either life-long medical therapy or surgery. In order to avoid the discomfort and expenses in surgical procedures, closed chest percutaneous catheter ablation of APs became a potentially desirable therapeutic approach. Many investigations indicated that ablation of right APs by transcatheter direct current (dc) shock could cause life-threatening arrhythmias, right coronary arterical (RCA) spasm, etc. With the development of transcatheter laser technique, it has been used in drug-incurable arrhythmias. The results show that laser ablation is much safer than surgery and electric shock therapy. The purpose of this study is to explore the effectiveness, advantages, and complications with transcatheter Nd:YAG laser and dc shock in the ablation of right atrioventricular accessory pathways in the atrium near the tricuspid annulus (TA) in 20 dogs.

  18. A technique to decrease surface roughness in overlapping laser shock peening

    Science.gov (United States)

    Dai, Fengze; Zhou, Jianzhong; Lu, Jinzhong; Luo, Xinmin

    2016-05-01

    A technique called elastic contact laser shock peening (ECLSP) is presented in this paper. In this technique, a metal foil with high dynamic yield strength is fixed between absorbing layer and workpiece, and the peak pressure of laser shock wave is a little less than the dynamic yield strength of metal foil, but higher than the Hugoniot Elastic Limit (HEL) of work piece. Surface roughness, microhardness and residual stress are investigated. Compared with regular laser shock peening (LSP), ECLSP can reduce the depth and area of secondary plastic deformation of overlapping region. This can effectively reduce surface roughness in overlapping LSP. Measurement of microhardness and residual stress shows that the work hardening effects and strengthening effect are similar as regular LSP.

  19. Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

    Energy Technology Data Exchange (ETDEWEB)

    Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)

    2013-12-15

    Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

  20. Accretion Shocks in the Laboratory: Using the OMEGA Laser to Study Star Formation

    Science.gov (United States)

    Young, R. P.; Kuranz, C. C.; Li, C. K.; Hartigan, P.; Froula, D.; Fiksel, G.; Ross, J. S.; Chang, P. Y.; Klein, S.; Zylstra, A.; Sio, H. W.; Liao, A.; Barnak, D.

    2016-10-01

    We present an on-going series of experiments using the OMEGA laser (Laboratory for Laser Energetics) to study star formation. Spectra of young stars show evidence of hotspots created when streams of accreting material impact at the surface of the star to create accretion shocks. These accretion shocks are poorly understood, as the surfaces of young stars cannot be spatially resolved. Our experiment series creates a scaled ``accretion shock'' on the OMEGA laser by driving a plasma jet (the ``accretion stream'') into a solid block (the ``stellar surface''), in the presence of a parallel magnetic field analogous to the star's local field. Thus far, visible image data from this experimental series either shows very thin accretion shocks forming or does not show them forming at all. We intend to present this data, provide possible explanations for why shocks may not have formed, and discuss potential improvements to the experimental design. This work is funded by the U.S. Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, Grant Number DE-NA0002956, and the National Laser User Facility Program, Grant Number DE-NA0002719.

  1. Plastic deformation mechanism of polycrystalline copper foil shocked with femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Y.X., E-mail: yeyunxia@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Feng, Y.Y.; Lian, Z.C.; Hua, Y.Q. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 21203 (China)

    2014-08-01

    Plastic deformation mechanism of polycrystalline copper foil shocked with femtosecond (fs) laser has been characterized through optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Experiments of ns laser shocking copper (Cu) and fs laser shocking aluminum (Al) were also conducted for comparison. Dislocations arranged in multiple forms, profuse twins and stacking faults (SFs) coexist in the fs laser shocked copper. At small strain condition, dislocation slip is the dominant deformation mode and small amount of SFs act as complementary mechanism. With strain increasing, profuse twins and SFs form to accommodate the plastic deformation. Furthermore, new formed SFs incline to locate around the old ones because the dislocation densities there are more higher. So there is a high probability for new SFs overlapping on old ones to form twins, or connecting old ones to lengthen them, which eventually produce the phenomena that twins connect with each other or twins connect with SFs. Strain greatly influences the dislocation density. Twins and SFs are more dependent on strain rate and shock pressure. Medium stacking fault energy (SFE) of copper helps to extend partial dislocations and provides sources for forming SFs and twins.

  2. Modeling of laser induced periodic surface structures

    NARCIS (Netherlands)

    Skolski, J.Z.P.; Römer, G.R.B.E.; Huis in 't Veld, A.J.; Mitko, V.S.; Obona, J.V.; Ocelik, V.; Hosson, J.T.M. de

    2010-01-01

    In surfaces irradiated by short laser pulses, Laser Induced Periodic Surface Structures (LIPSS) have been observed on all kind of materials for over forty years. These LIPSS, also referred to as ripples, consist of wavy surfaces with periodicity equal or smaller than the wavelength of the laser radi

  3. Effect of laser shock processing on fatigue crack growth and fracture toughness of 6061-T6 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rubio-Gonzalez, C. [Centro de Ingenieria y Desarrollo Industrial, Pie de la cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130 (Mexico)]. E-mail: crubio@cidesi.mix; Ocana, J.L. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain); Gomez-Rosas, G. [Centro de Ingenieria y Desarrollo Industrial, Pie de la cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130 (Mexico); Molpeceres, C. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain); Paredes, M. [Centro de Ingenieria y Desarrollo Industrial, Pie de la cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130, Mexico (Mexico); Banderas, A. [Centro de Ingenieria y Desarrollo Industrial, Pie de la cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130, Mexico (Mexico); Porro, J. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain); Morales, M. [Departamento de Fisica Aplicada a la Ingenieria Industrial, E.T.S.I.I. Universidad Politecnica de Madrid (Spain)

    2004-11-25

    Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 1.2 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto a water-immersed type aluminum samples. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the higher the pulse density the larger the zone size with compressive residual stress. Densities of 900, 1350 and 2500 pulses/cm{sup 2} with infrared (1064 nm) radiation are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. Fatigue crack growth rate is compared in specimens with and without LSP process. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness in the 6061-T6 aluminum alloy.

  4. Combined effects of laser and non-thermal electron beams on hydrodynamics and shock formation in the Shock Ignition scheme

    Science.gov (United States)

    Nicolai, Ph.; Feugeas, J. L.; Touati, M.; Breil, J.; Dubroca, B.; Nguyen-Buy, T.; Ribeyre, X.; Tikhonchuk, V.; Gus'kov, S.

    2014-10-01

    An issue to be addressed in Inertial Confinement Fusion (ICF) is the detailed description of the kinetic transport of relativistic or non-thermal electrons generated by laser within the time and space scales of the imploded target hydrodynamics. We have developed at CELIA the model M1, a fast and reduced kinetic model for relativistic electron transport. The latter has been implemented into the 2D radiation hydrodynamic code CHIC. In the framework of the Shock Ignition (SI) scheme, it has been shown in simplified conditions that the energy transferred by the non-thermal electrons from the corona to the compressed shell of an ICF target could be an important mechanism for the creation of ablation pressure. Nevertheless, in realistic configurations, taking the density profile and the electron energy spectrum into account, the target has to be carefully designed to avoid deleterious effects on compression efficiency. In addition, the electron energy deposition may modify the laser-driven shock formation and its propagation through the target. The non-thermal electron effects on the shock propagation will be analyzed in a realistic configuration.

  5. Laser shock peening of steam turbine blade for enhanced service life

    Indian Academy of Sciences (India)

    R Sundar; B K Pant; Harish Kumar; P Ganesh; D C Nagpure; P Haedoo; Rakesh Kaul; K Ranganathan; K S Bindra; S M Oak; L M Kukreja

    2014-02-01

    Fretting-fatigue is an important factor influencing service life of turbine blades. The present paper describes laser shock peening of potential crack nucleation site in the root region of steam turbine blade for its enhanced service life. The experimental study, performed with an in-house developed 2.5 J/7 ns Nd:YAG laser demonstrated that laser peening introduced a residual surface compressive stress of −260 to −390 MPa. Case depth of laser peened surface layer was found to be more than 900 m.

  6. Laser Shock Processing of Metallic Materials: Coupling of Laser-Plasma Interaction and Material Behaviour Models for the Assessment of Key Process Issues

    Science.gov (United States)

    Ocaña, J. L.; Morales, M.; Molpeceres, C.; Porro, J. A.

    2010-10-01

    Profiting by the increasing availability of laser sources delivering intensities above 109 W/cm2 with pulse energies in the range of several Joules and pulse widths in the range of nanoseconds, laser shock processing (LSP) is consolidating as an effective technology for the improvement of surface mechanical and corrosion resistance properties of metals. The main advantage of the laser shock processing technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Although significant work from the experimental side has been contributed to explore the optimum conditions of application of the treatments and to assess their ultimate capability to provide enhanced mechanical behaviour to work-pieces of typical materials, only limited attempts have been developed in the way of full comprehension and predictive assessment of the characteristic physical processes and material transformations with a specific consideration of real material properties. In the present paper, a review on the physical issues dominating the development of LSP processes from a high intensity laser-matter interaction point of view is presented along with the theoretical and computational methods developed by the authors for their predictive assessment and practical results at laboratory scale on the application of the technique to different materials.

  7. Dynamics of laser ablative shock waves from one dimensional periodic structured surfaces

    Science.gov (United States)

    Chelikani, Leela; Pinnoju, Venkateshwarlu; Paturi, Prem Kiran

    2017-01-01

    Laser ablative shock waves (LASWs) from one dimensional periodic structured surfaces (1D-PSS) on Aluminum metal is studied using time resolved shadowgraphy technique. 1D-PSS of triangular and sinusoidal periodic density profiles consisting of 288 lines per laser focal spot diameter (lp2ω0) with periodicity of 0.83 μm are used as targets. The SW properties such as propagation distance, velocity and pressure behind the shock front were compared with flat Aluminum surface of the target under the same experimental conditions. The possibility of tailoring the nature of LASWs with varying density profile on the surface is presented.

  8. Laser Beam Propagation Through Inhomogeneous Media with Shock-Like Profiles: Modeling and Computing

    Science.gov (United States)

    Adamovsky, Grigory; Ida, Nathan

    1997-01-01

    Wave propagation in inhomogeneous media has been studied for such diverse applications as propagation of radiowaves in atmosphere, light propagation through thin films and in inhomogeneous waveguides, flow visualization, and others. In recent years an increased interest has been developed in wave propagation through shocks in supersonic flows. Results of experiments conducted in the past few years has shown such interesting phenomena as a laser beam splitting and spreading. The paper describes a model constructed to propagate a laser beam through shock-like inhomogeneous media. Numerical techniques are presented to compute the beam through such media. The results of computation are presented, discussed, and compared with experimental data.

  9. Effects of laser polarization on electrostatic shock ion acceleration in near-critical plasmas

    Science.gov (United States)

    Kim, Young-Kuk; Kang, Teyoun; Hur, Min Sup

    2016-10-01

    Collisionless electrostatic shock ion acceleration has become a major regime of laser-driven ion acceleration owing to generation of quasi-monoenergetic ion beams from moderate parametric conditions of lasers and plasmas in comparison with target-normal-sheath-acceleration or radiation pressure acceleration. In order to construct the shock, plasma heating is an essential condition for satisfying Mach number condition 1.5 Weibel instability. This work was supported by the Basic Science Research Program (NRF- 2013R1A1A2006353) and the Creative Allied Project (CAP-15-06-ETRI).

  10. Shock-Induced Flows through Packed Beds: Transient Regimes

    CERN Document Server

    Shtemler, Yuri M; Britan, Alex

    2006-01-01

    The early stage of the transient regimes in the shock-induced flows within solid-packed beds are investigated in the linear longwave and high-frequency approximation. The transient resistance law is refined as the Duhameltime integral that follows from the general concept of dynamic tortuosity and compressibility of the packed beds. A closed-form solution is expected to describe accurately the early stage of the transient regime flow and is in qualitative agreement with available experimental data.

  11. Liquid explosions induced by X-ray laser pulses

    Science.gov (United States)

    Stan, Claudiu A.; Milathianaki, Despina; Laksmono, Hartawan; Sierra, Raymond G.; McQueen, Trevor A.; Messerschmidt, Marc; Williams, Garth J.; Koglin, Jason E.; Lane, Thomas J.; Hayes, Matt J.; Guillet, Serge A. H.; Liang, Mengning; Aquila, Andrew L.; Willmott, Philip R.; Robinson, Joseph S.; Gumerlock, Karl L.; Botha, Sabine; Nass, Karol; Schlichting, Ilme; Shoeman, Robert L.; Stone, Howard A.; Boutet, Sébastien

    2016-10-01

    Explosions are spectacular and intriguing phenomena that expose the dynamics of matter under extreme conditions. We investigated, using time-resolved imaging, explosions induced by ultraintense X-ray laser pulses in water drops and jets. Our observations revealed an explosive vaporization followed by high-velocity interacting flows of liquid and vapour, and by the generation of shock trains in the liquid jets. These flows are different from those previously observed in laser ablation, owing to a simpler spatial pattern of X-ray absorption. We show that the explosion dynamics in our experiments is consistent with a redistribution of absorbed energy, mediated by a pressure or shock wave in the liquid, and we model the effects of explosions, including their adverse impact on X-ray laser experiments. X-ray laser explosions have predictable dynamics that may prove useful for controlling the state of pure liquids over broad energy scales and timescales, and for triggering pressure-sensitive molecular dynamics in solutions.

  12. Radiative Shock-Induced Collapse of Intergalactic Clouds

    CERN Document Server

    Fragile, P C; Anninos, P; Van Breugel, W; Murray, Stephen D.; Anninos, Peter; Breugel, Wil van

    2004-01-01

    Accumulating observational evidence for a number of radio galaxies suggests an association between their jets and regions of active star formation. The standard picture is that shocks generated by the jet propagate through an inhomogeneous medium and trigger the collapse of overdense clouds, which then become active star-forming regions. In this contribution, we report on recent hydrodynamic simulations of radiative shock-cloud interactions using two different cooling models: an equilibrium cooling-curve model assuming solar metallicities and a non-equilibrium chemistry model appropriate for primordial gas clouds. We consider a range of initial cloud densities and shock speeds in order to quantify the role of cooling in the evolution. Our results indicate that for moderate cloud densities (>1 cm^{-3}) and shock Mach numbers (0.01 and total H_2 mass fractions of >10^{-5} for the cloud gas. Finally, we compare our results with the observations of jet-induced star formation in ``Minkowski's Object.'' We conclude...

  13. Surgical Treatment of Laser Induced Eye Injuries

    Science.gov (United States)

    1990-12-05

    AD-A234 849 CONTRACT NO.: DAMD17-89-C-9026 TITLE: SURGICAL TREATMENT OF LASER INDUCED EYE INJURIES AUTHORS: Leonard M. Hjelmeland, Maurice B. Landers...62787A 62787A878 BA JDA318205 11. TITLE (Include Secirity Classification) (U) Surgical Treatment of Laser Induced Eye Injuries 12. PERSONAL AUTHOR(S...TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP RA 3; Lasers; Eye injury ; Surgery 09 03 06 04 19. ABSTRACT

  14. Laser-Induced Energy Transfer in Solids

    NARCIS (Netherlands)

    Morsink, J.B.W.; Rullmann, Johan; Wiersma, Douwe

    1981-01-01

    Laser-induced energy transfer was observed and studied in the system pentacene doped into naphthalene. The transfer spectrum shows a remarkable correspondence with the host density of states function. The rate for laser-induced energy transfer is given and it is concluded that most likely, intermole

  15. A cylindrical converging shock tube for shock-interface studies.

    Science.gov (United States)

    Luo, Xisheng; Si, Ting; Yang, Jiming; Zhai, Zhigang

    2014-01-01

    A shock tube facility for generating a cylindrical converging shock wave is developed in this work. Based on the shock dynamics theory, a specific wall profile is designed for the test section of the shock tube to transfer a planar shock into a cylindrical one. The shock front in the converging part obtained from experiment presents a perfect circular shape, which proves the feasibility and reliability of the method. The time variations of the shock strength obtained from numerical simulation, experiment, and theoretical estimation show the desired converging effect in the shock tube test section. Particular emphasis is then placed on the problem of shock-interface interaction induced by cylindrical converging shock waves. For this purpose, membrane-less gas cylinder is adopted to form the interface between two different fluids while the laser sheet technique to visualize the flow field. The result shows that it is convenient to perform such experiments in this facility.

  16. Interaction of single-pulse laser energy with bow shock in hypersonic flow

    Directory of Open Access Journals (Sweden)

    Hong Yanji

    2014-04-01

    Full Text Available Pressure sensing and schlieren imaging with high resolution and sensitivity are applied to the study of the interaction of single-pulse laser energy with bow shock at Mach 5. An Nd:YAG laser operated at 1.06 μm, 100 mJ pulse energy is used to break down the hypersonic flow in a shock tunnel. Three-dimensional Navier–Stokes equations are solved with an upwind scheme to simulate the interaction. The pressure at the stagnation point on the blunt body is measured and calculated to examine the pressure variation during the interaction. Schlieren imaging is used in conjunction with the calculated density gradients to examine the process of the interaction. The results show that the experimental pressure at the stagnation point on the blunt body and schlieren imaging fit well with the simulation. The pressure at the stagnation point on the blunt body will increase when the transmission shock approaches the blunt body and decrease with the formation of the rarefied wave. Bow shock is deformed during the interaction. Quasi-stationary waves are formed by high rate laser energy deposition to control the bow shock. The pressure and temperature at the stagnation point on the blunt body and the wave drag are reduced to 50%, 75% and 81% respectively according to the simulation. Schlieren imaging has provided important information for the investigation of the mechanism of the interaction.

  17. Verification of a characterization method of the laser-induced selective activation based on industrial lasers

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Tang, Peter T.

    2013-01-01

    In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser-machine...

  18. Microscale nanosecond laser-induced optical breakdown in water.

    Science.gov (United States)

    Kudryashov, Sergey I; Zvorykin, Vladimir D

    2008-09-01

    Microscale optical breakdown induced in bulk pure water by high-power nanosecond KrF laser pulses was studied using optical transmission and contact broadband photoacoustic techniques. The breakdown has been identified as a sharp transmission drop coinciding with the appearance of unipolar compressive acoustic pulses, both indicating a thresholdlike rise of local intrinsic absorption in the micrometer-scale laser focal volume. The acoustic pulses, which are much broader than the exciting laser pulse and show a strongly reduced far-field diffraction effect, result from breakdown-induced millimeter-sized steam bubbles. The acoustic pulse amplitudes exhibit a sub-linear ( proportional, variantI(3/4)) pressure dependence on the laser intensity I characteristic of subcritical electron-ion plasma and demonstrating the avalanche enhancement of two-photon ionization above the breakdown threshold until the appearance of the critical plasma. In the critical plasma regime, where the transmission and the acoustic signals slowly vary as a function of laser intensity, the main acoustic pulse is preceded by nanosecond and sub- micros prepulses, where the first one represents a GPa-level plasma-driven shock wave and the second one adjacent to the main pulse appears due to weak submillimeter-long heating of water surrounding the hot plasma by its bremsstrahlung radiation, indicating significant dissociation of water molecules in the plasma.

  19. High Mach-number collisionless shock driven by a laser with an external magnetic field

    Directory of Open Access Journals (Sweden)

    Morita T.

    2013-11-01

    Full Text Available Collisionless shocks are produced in counter-streaming plasmas with an external magnetic field. The shocks are generated due to an electrostatic field generated in counter-streaming laser-irradiated plasmas, as reported previously in a series of experiments without an external magnetic field [T. Morita et al., Phys. Plasmas, 17, 122702 (2010, Kuramitsu et al., Phys. Rev. Lett., 106, 175002 (2011] via laser-irradiation of a double-CH-foil target. A magnetic field is applied to the region between two foils by putting an electro-magnet (∼10 T perpendicular to the direction of plasma expansion. The generated shocks show different characteristics later in time (t > 20ns.

  20. Experimental Research on Plasma Induced by TEA CO2 Laser Propulsion

    Institute of Scientific and Technical Information of China (English)

    LU Hong; CHENG Zuhai; ZUO Duluo; ZHAI Bingjie; YU Liangying; ZHU Haihong

    2008-01-01

    Results in the air-breathing propulsion experiments with a parabolic light craft and a self-made UV-preionized 100 J TEA CO2 laser device are presented. Air disturbance and the spectrum of the plasma after the interaction of pulsed laser radiation with the light craft were studied. It was found that the focal length of the parabolic light craft had a significant effect on the air-disturbance. Two shock waves were detected for the longer focal length, while only one shock wave detected for the short focal length. The spectrum of the laser-induced plasma, the distribution of the characteristic lines, and the temporal behaviors of the air plasma were studied in detail. The results showed that, the evolution of the laser-induced plasma lasted 20 μs, and the plasma spectrum would reach the maximum intensity at 7 μs.

  1. Fatigue behavior of superferritic stainless steel laser shock treated without protective coating

    Science.gov (United States)

    Spadaro, L.; Gomez-Rosas, G.; Rubio-González, C.; Bolmaro, R.; Chavez-Chavez, A.; Hereñú, S.

    2017-08-01

    The laser shock peening (LSP) is a new technique that improves the fatigue life of metallic components by inducing deep compressive residual stresses through the surface. However, the beneficial effects of LSP depend on the persistence and stability of such residual stress fields under cyclic loading and temperature. Moreover, if no absorbent coating is used in LSP operation, thermal effects can occur on the metallic substrate. The purpose of this work is to study the influence of LSP, without protective coating and with different pulse densities, on the low cyclic fatigue behavior of a superferritic stainless steel UNS S 44600. These results are correlated with observations performed by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with electron diffraction spectroscopy (EDS). The hole-drilling method is used to measure residual stresses. The micro-hardness and roughness profiles are also presented. This paper shows that LSP without coating produces beneficial compression residual stresses. However, in the first 10 μm beneath the surface, thermal effects occur that induce intergranular corrosion. This intergranular corrosion deteriorates the fatigue properties of a superferritic stainless steel UNS S 44600.

  2. [Mathematical modeling of laser-induced selective destruction of labyrinthine vestibular receptors].

    Science.gov (United States)

    Antonian, R G; Iakovlev, G V; Bakaliarov, A M; Garov, E V

    2006-01-01

    Basing on mathematical modeling, we tried to investigate in humans the ability of laser energy to suppress the function of the ampullar receptors of the semicircular canels and otolith receptors; to elicit mechanism of action of laser energy on labyrinthine receptors. Modeling has shown that in 1 mm thickness of the canal wall laser impact raises temperature of the liquid to 120 degrees C. Temperature higher than 100 degrees C stands in it up to 120 ms. This induces a distinct hydrodynamic shock which suppresses function of labyrinthine ampullar and otolith receptors. The heat factor of the laser impact causes destruction of the receptor sensory cells lasting for about a year.

  3. Field enhancement induced laser ablation

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures...

  4. Influence of air pressure on mechanical effect of laser plasma shock wave

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu-Zhu; Wang Guang-An; Zhu Jin-Rong; Shen Zhong-Hua; Ni Xiao-Wu; Lu Jian

    2007-01-01

    The influence of air pressure on mechanical effect of laser plasma shock wave in a vacuum chamber produced by a Nd:YAG laser has been studied. The laser pulses with pulse width of 10ns and pulse energy of about 320mJ at 1.06μm wavelength is focused on the aluminium target mounted on a ballistic pendulum, and the air pressure in the chamber changes from 2.8 × 103 to 1.01×105pa. The experimental results show that the impulse coupling coefficient changes as the air pressure and the distance of the target from focus change. The mechanical effects of the plasma shock wave on the target are analysed at different distances from focus and the air pressure.

  5. Influence of air pressure on mechanical effect of laser plasma shock wave

    Science.gov (United States)

    Zhang, Yu-Zhu; Wang, Guang-An; Zhu, Jin-Rong; Shen, Zhong-Hua; Ni, Xiao-Wu; Lu, Jian

    2007-09-01

    The influence of air pressure on mechanical effect of laser plasma shock wave in a vacuum chamber produced by a Nd:YAG laser has been studied. The laser pulses with pulse width of 10ns and pulse energy of about 320mJ at 1.06μm wavelength is focused on the aluminium target mounted on a ballistic pendulum, and the air pressure in the chamber changes from 2.8 × 103 to 1.01 × 105Pa. The experimental results show that the impulse coupling coefficient changes as the air pressure and the distance of the target from focus change. The mechanical effects of the plasma shock wave on the target are analysed at different distances from focus and the air pressure.

  6. Shock wave mediated plume chemistry for molecular formation in laser ablation plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Brumfield, Brian E.; Cannon, Bret D.; Phillips, Mark C.

    2016-02-16

    Laser ablation is used in a variety of applications albeit formation mechanisms of molecules and nanoclusters are not well understood. We investigated the formation mechanisms of AlO molecules during complex interactions between an Al laser plume expanding into ambient air at atmospheric pressure levels. To produce the plasma a high-purity Al target was ablated using 1064 nm, 6 ns laser pulses. Our results show that the plasma chemistry leading to the formation of AlO is mediated by shock waves. During the early times of plasma expansion, the generated shock waves at the plume edges act as a barrier for the combustion process and the molecular formation is prevalent after the shockwave collapse. The temporally and spatially resolved contour mapping of Al and AlO highlight the formation routes and persistence of species in the plasma and its relation to plume hydrodynamics.

  7. Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

    Institute of Scientific and Technical Information of China (English)

    LU Jinzhong; ZHANG Yongkang; KONG Dejun; REN Xudong; GE Tao; ZOU Shikun

    2007-01-01

    The surface of TC4 titanium alloy welding line by electron beam welding (EBW) was processed by high power Q-switched and repetition-rate Nd: glass laser. Effects of laser power and spot diameter on residual stress and microhardness of the TC4 alloy welding line by laser shock processing (LSP) have been analyzed. Results show that residual stresses almost do not change as laser poweris 45.9 J,spot diameter is φ9 mm; While laser power is 45.9 J, spot diameter less than φ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress increase obviously with spot diameter decrease. When power density is bigger than 1.8×1010W/cm2, residual stresses of electron beam welding line occur change by LSP,which improve obviously residual stress distribution; while laser power is bigger than 1.2×1010W/cm2, the surface micro-hardness of electron beam welding line occurs change by LSP, which improve obviously micro-hardness distribution. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP, which provides experimental foundation for further controlling the distributions of residual stress and micro-hardness during laser shock processing.

  8. Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

    2013-10-15

    Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 10{sup 14} to 1.8 × 10{sup 15} W/cm{sup 2}. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

  9. Experimental and theoretical investigations on shock wave induced phase transitions

    Science.gov (United States)

    Gupta, Satish C.; Sikka, S. K.

    2001-06-01

    Shock wave loading of a material can cause variety of phase transitions, like polymorphism, amorphization, metallization and molecular dissociations. As the shocked state lasts only for a very short duration (about a few microseconds or less), in-situ microscopic measurements are very difficult. Although such studies are beginning to be possible, most of the shock-induced phase transitions are detected using macroscopic measurements. The microscopic nature of the transition is then inferred from comparison with static pressure data or interpreted by theoretical methods. For irreversible phase transitions, microscopic measurements on recovered samples, together with orientation relations determined from selected area electron diffraction and examination of the morphology of growth of the new phase can provide insight into mechanism of phase transitions. On theoretical side, the current ab initio band structure techniques based on density functional formalism provide capability for accurate computation of the small energy differences (a few mRy or smaller) between different plausible structures. Total energy calculation along the path of a phase transition can furnish estimates of activation barrier, which has implications for understanding kinetics of phase transitions. Molecular dynamics calculations, where the new structure evolves naturally, are becoming increasingly popular especially for understanding crystal to amorphous phase transitions. Illustrations from work at our laboratory will be presented.

  10. Shock-Induced Chemical Reactions in Structural Energetic Materials

    Science.gov (United States)

    Narayanan, V.; Lu, X.; Hanagud, S.

    2006-07-01

    Various powder mixtures like intermetallic mixtures and mixtures of metals and metal oxides have potential applications as structural energetic materials (SEMs). Technologies of varying the compositions and the powder sizes and their synthesis are being investigated to provide multiple desirable characteristics, like high strength and high energy content. In this paper, we formulate a model for SEMs for their application in shock conditions, in the framework of nonequilibrium thermodynamics and continuum mechanics. A mixture of Al and KClO4 is selected as the example for SEMs. A mixture, pore collapse and chemical reaction model are included. By adapting energy barriers for reaction as a function of temperature, particle size and pressure and introducing a relaxation mechanism in the reaction model, a shock-induced chemical reaction model is developed. The variation of the relaxation mechanism is also modeled. The initiation and propagation of chemical reactions are studied. The time and spatial dependency of chemical reaction on the shock wave conditions are investigated.

  11. Experimental particle acceleration by water evaporation induced by shock waves

    Science.gov (United States)

    Scolamacchia, T.; Alatorre Ibarguengoitia, M.; Scheu, B.; Dingwell, D. B.; Cimarelli, C.

    2010-12-01

    Shock waves are commonly generated during volcanic eruptions. They induce sudden changes in pressure and temperature causing phase changes. Nevertheless, their effects on flowfield properties are not well understood. Here we investigate the role of gas expansion generated by shock wave propagation in the acceleration of ash particles. We used a shock tube facility consisting of a high-pressure (HP) steel autoclave (450 mm long, 28 mm in internal diameter), pressurized with Ar gas, and a low-pressure tank at atmospheric conditions (LP). A copper diaphragm separated the HP autoclave from a 180 mm tube (PVC or acrylic glass) at ambient P, with the same internal diameter of the HP reservoir. Around the tube, a 30 cm-high acrylic glass cylinder, with the same section of the LP tank (40 cm), allowed the observation of the processes occurring downstream from the nozzle throat, and was large enough to act as an unconfined volume in which the initial diffracting shock and gas jet expand. All experiments were performed at Pres/Pamb ratios of 150:1. Two ambient conditions were used: dry air and air saturated with steam. Carbon fibers and glass spheres in a size range between 150 and 210 μm, were placed on a metal wire at the exit of the PVC tube. The sudden decompression of the Ar gas, due to the failure of the diaphragm, generated an initial air shock wave. A high-speed camera recorded the processes between the first 100 μsec and several ms after the diaphragm failure at frame rates ranging between 30,000 and 50,000 fps. In the experiments with ambient air saturated with steam, the high-speed camera allowed to visualize the condensation front associated with the initial air shock; a maximum velocity of 788 m/s was recorded, which decreases to 524 m/s at distance of 0.5 ±0.2 cm, 1.1 ms after the diaphragm rupture. The condensation front preceded the Ar jet front exhausting from the reservoir, by 0.2-0.5 ms. In all experiments particles velocities following the initial

  12. Laser shock peening of Ti-17 titanium alloy: Influence of process parameters

    Energy Technology Data Exchange (ETDEWEB)

    Cellard, C.; Retraint, D.; Francois, M. [University of Technology of Troyes (UTT), Charles Delaunay Institute, LASMIS, UMR CNRS 6279, 12 Rue Marie Curie, BP2060, 10010 Troyes Cedex (France); Rouhaud, E., E-mail: rouhaud@utt.fr [University of Technology of Troyes (UTT), Charles Delaunay Institute, LASMIS, UMR CNRS 6279, 12 Rue Marie Curie, BP2060, 10010 Troyes Cedex (France); Le Saunier, D. [SNECMA Evry - Corbeil, Route Henry Auguste Desbrueres, 91003 Evry (France)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Laser shock peening parameters studied through a design of experiments. Black-Right-Pointing-Pointer Laser fluence, pulse duration, number of impacts and sample thickness are studied. Black-Right-Pointing-Pointer The observed work hardening is low, the roughness is lightly affected. Black-Right-Pointing-Pointer A significant part of hardness increase is due to compressive residual stresses. Black-Right-Pointing-Pointer High tensile residual stresses can appear on thin laser shocked specimens. - Abstract: The influence of the process parameters of laser shock peening was investigated on specimens made of an aeronautic titanium alloy: Ti-5Al-2Sn-2Zr-4Cr-4Mo (Ti-17). In order to quantify the effect of relevant process parameters, an experimental design was carried out. It is based on a full factorial design with four factors (laser fluence, pulse duration, number of impacts and thickness of the sample) and two levels for each factor. The process is characterised with the following variables: the depth of the impacts, the roughness of the treated surface, the hardening of the material (itself evaluated with the hardness and X-ray diffraction peak width), the residual stresses left in the sample and the global curvature of the sample. It is found that all the parameters have an influence on the residual stresses and that laser shock peening has no influence on roughness and low influence on work-hardening. The variables are then analysed in order to evaluate correlations. The increase in hardness is found to be essentially due to compressive residual stresses, cold work-hardening having only a small effect. In thin specimens, the stress redistribution due to self-equilibrium leads to tensile residual stresses at the treated surface and to large deformations of the specimens.

  13. Heat Shock Protein 96 Induces Maturation of Dendritic Cells

    Institute of Scientific and Technical Information of China (English)

    Chunxia Cao; Wei Yang; Yonglie Chu; Qingguang Liu; Liang Yu; Cheng'en Pan

    2006-01-01

    Objective: Heat shock protein (HSP) has the promiscuous abilities to chaperone and present a broad repertoire of tumor antigens to antigen presenting cells including DCs. In this report, we analyzed the modulation of immature DC by HSP 96 (gp96).Method: Murine bone marrow-derived DC was induced by GM-CSF plus IL-4, which aped the immunostimulatory effects of DC.Cocultured DC and gp96-peptide complexes (gp96-PC) or inactivated H22 cells, the expression of MHC class Ⅱ, CD40, CD80 was quantified by flow cytometry. The concentration of IL-12 and TNF- in culture supernatants were determined by ELISA.[51] Cr release assay was used to test specific cytotoxic T cell. Results: Our study demonstrated that the extent of DC maturation induced by gp96-PC, which was reflected in surface density of costimulatory and MHC Ⅱ molecules, was correlated with the secretion of IL-12 and with the T cellactivating potential in vitro. Conclusion: Heat shock protein 96 could be isolated and purified from H22 cells and could induce maturation of dendritic cell. Our findings might be relevance to the use of DC vaccine in therapy of human tumors.

  14. Thalidomide protects mice against LPS-induced shock

    Directory of Open Access Journals (Sweden)

    Moreira A.L.

    1997-01-01

    Full Text Available Thalidomide has been shown to selectively inhibit TNF-a production in vitro by lipopolysaccharide (LPS-stimulated monocytes. TNF-a has been shown to play a pivotal role in the pathophysiology of endotoxic shock. Using a mouse model of LPS-induced shock, we investigated the effects of thalidomide on the production of TNF-a and other cytokines and on animal survival. After injection of 100-350 µg LPS into mice, cytokines including TNF-a, IL-6, IL-10, IL-1ß, GM-CSF and IFN-g were measured in the serum. Administration of 200 mg/kg thalidomide to mice before LPS challenge modified the profile of LPS-induced cytokine secretion. Serum TNF-a levels were reduced by 93%, in a dose-dependent manner, and TNF-a mRNA expression in the spleens of mice was reduced by 70%. Serum IL-6 levels were also inhibited by 50%. Thalidomide induced a two-fold increase in serum IL-10 levels. Thalidomide treatment did not interfere with the production of GM-CSF, IL-1ß or IFN-g. The LD50 of LPS in this model was increased by thalidomide pre-treatment from 150 µg to 300 µg in 72 h. Thus, at otherwise lethal doses of LPS, thalidomide treatment was found to protect animals from death

  15. Atomistic modeling of shock-induced void collapse in copper

    Energy Technology Data Exchange (ETDEWEB)

    Davila, L P; Erhart, P; Bringa, E M; Meyers, M A; Lubarda, V A; Schneider, M S; Becker, R; Kumar, M

    2005-03-09

    Nonequilibrium molecular dynamics (MD) simulations show that shock-induced void collapse in copper occurs by emission of shear loops. These loops carry away the vacancies which comprise the void. The growth of the loops continues even after they collide and form sessile junctions, creating a hardened region around the collapsing void. The scenario seen in our simulations differs from current models that assume that prismatic loop emission is responsible for void collapse. We propose a new dislocation-based model that gives excellent agreement with the stress threshold found in the MD simulations for void collapse as a function of void radius.

  16. Shock wave induced martensitic transformations and morphology changes in Fe-Pd ferromagnetic shape memory alloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, A. J., E-mail: alina.bischoff@iom-leipzig.de; Arabi-Hashemi, A.; Ehrhardt, M.; Lorenz, P.; Zimmer, K. [Leibniz Institute for Surface Modification, Permoserstr. 15, 04318 Leipzig (Germany); Mayr, S. G., E-mail: stefan.mayr@iom-leipzig.de [Leibniz Institute for Surface Modification, Permoserstr. 15, 04318 Leipzig (Germany); Department of Physics and Earth Sciences, Leipzig University, Linnéstr. 5, 04103 Leipzig (Germany)

    2016-04-11

    Combining experimental methods and classical molecular dynamics (MD) computer simulations, we explore the martensitic transformation in Fe{sub 70}Pd{sub 30} ferromagnetic shape memory alloy thin films induced by laser shock peening. X-ray diffraction and scanning electron microscope measurements at shock wave pressures of up to 2.5 GPa reveal formation of martensitic variants with preferred orientation of the shorter c-axis of the tetragonal unit cell perpendicular to the surface plane. Moreover, consequential merging of growth islands on the film surface is observed. MD simulations unveil the underlying physics that are characterized by an austenite-martensite transformation with a preferential alignment of the c-axis along the propagation direction of the shock wave, resulting in flattening and in-plane expansion of surface features.

  17. Fragment size distribution statistics in dynamic fragmentation of laser shock-loaded tin

    Directory of Open Access Journals (Sweden)

    Weihua He

    2017-06-01

    Full Text Available This work investigates the geometric statistics method to characterize the size distribution of tin fragments produced in the laser shock-loaded dynamic fragmentation process. In the shock experiments, the ejection of the tin sample with etched V-shape groove in the free surface are collected by the soft recovery technique. Subsequently, the produced fragments are automatically detected with the fine post-shot analysis techniques including the X-ray micro-tomography and the improved watershed method. To characterize the size distributions of the fragments, a theoretical random geometric statistics model based on Poisson mixtures is derived for dynamic heterogeneous fragmentation problem, which reveals linear combinational exponential distribution. The experimental data related to fragment size distributions of the laser shock-loaded tin sample are examined with the proposed theoretical model, and its fitting performance is compared with that of other state-of-the-art fragment size distribution models. The comparison results prove that our proposed model can provide far more reasonable fitting result for the laser shock-loaded tin.

  18. Shock

    Science.gov (United States)

    Shock can be caused by any condition that reduces blood flow, including: Heart problems (such as heart attack or heart failure ) Low blood volume (as with heavy bleeding or dehydration ) Changes in blood vessels (as with infection ...

  19. Liquid explosions induced by X-ray laser pulses

    Science.gov (United States)

    Stan, Claudiu; Laksmono, Hartawan; Sierra, Raymond; McQueen, Trevor; Milathianaki, Despina; Koglin, Jason; Lane, Thomas; Messerschmidt, Marc; Williams, Garth; Hayes, Matt; Guillet, Serge; Botha, Sabine; Nass, Karol; Schlichting, Ilme; Shoeman, Robert; Stone, Howard; Boutet, Sébastien

    2015-11-01

    Sudden generation and release of enough energy to vaporize matter are encountered in systems that range from supernovae explosions and asteroid impacts to applications in fusion energy generation, materials processing, and laser surgery. Understanding these strong explosions is important to both fundamental science and technical applications. We studied a new type of microexplosion, induced by absorption of X-ray pulses from a free-electron laser in micron-sized drops and jets of water. These explosions are related to, but different from, those observed in experiments performed with optical lasers. Unlike explosions caused by optical lasers, X-ray laser explosions produce symmetric expansion patterns that are simpler to rationalize. The release of energy initially concentrated in a small region inside drops and jets leads to ballistic vapor flow and inertial liquid flow. The kinematics of these flows indicates that the conversion of the energy deposited by X-rays into flow has a scaling that is similar to the one encountered in shock waves.

  20. Laser shock processing of FCC metals micro-structural strengthening mechanism

    CERN Document Server

    Zhang, Yongkang; Luo, Kaiyu

    2013-01-01

    Laser shock processing (LSP) is a new and promising surface treatment technique for improving the fatigue durability, corrosion, wear resistance and other mechanical properties of metals and alloys. During LSP, the generated shock wave can introduce a deep compressive residual stress into the material, due to its high-pressure (GPa-TPa), ultra-fast (several tens nanoseconds), ultra-high strain-rate and high-energy. The overall properties and behavior of metal materials subjected to LSP were significantly improved because a refined surface layer was successfully obtained. Nevertheless, up to no

  1. Solid state amorphization of nanocrystalline nickel by cryogenic laser shock peening

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Chang, E-mail: cye@uakron.edu; Ren, Zhencheng; Zhao, Jingyi; Hou, Xiaoning; Dong, Yalin [Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325 (United States); Liu, Yang; Sang, Xiahan [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-10-07

    In this study, complete solid state amorphization in nanocrystalline nickel has been achieved through cryogenic laser shock peening (CLSP). High resolution transmission electron microscopy has revealed the complete amorphous structure of the sample after CLSP processing. A molecular dynamic model has been used to investigate material behavior during the shock loading and the effects of nanoscale grain boundaries on the amorphization process. It has been found that the initial nanoscale grain boundaries increase the initial Gibbs free energy before plastic deformation and also serve as dislocation emission sources during plastic deformation to contribute to defect density increase, leading to the amorphization of pure nanocrystalline nickel.

  2. Synchronized turbo apoptosis induced by cold-shock

    Science.gov (United States)

    Fransen, J. H.; Dieker, J. W.; Hilbrands, L. B.; Berden, J. H.

    2010-01-01

    In our research on the role of apoptosis in the pathogenesis of the autoimmune disease systemic lupus erythematosus (SLE), we aim to evaluate the effects of early and late apoptotic cells and blebs on antigen presenting cells. This requires the in vitro generation of sufficiently large and homogeneous populations of early and late apoptotic cells. Here, we present a quick method encountered by serendipity that results in highly reproducible synchronized homogeneous apoptotic cell populations. In brief, granulocytic 32Dcl3 cells are incubated on ice for 2 h and subsequently rewarmed at 37°C. After 30–90 min at 37°C more than 80–90% of the cells become early apoptotic (Annexin V positive/propidium iodide negative). After 24 h of rewarming at 37°C 98% of the cells were late apoptotic (secondary necrotic; Annexin V positive/propidium iodide positive). Cells already formed apoptotic blebs at their cell surface after approximately 20 min at 37°C. Inter-nucleosomal chromatin cleavage and caspase activation were other characteristics of this cold-shock-induced process of apoptosis. Consequently, apoptosis could be inhibited by a caspase inhibitor. Finally, SLE-derived anti-chromatin autoantibodies showed a high affinity for apoptotic blebs generated by cold-shock. Overall, cold-shock induced apoptosis is achieved without the addition of toxic compounds or antibodies, and quickly leads to synchronized homogeneous apoptotic cell populations, which can be applied for various research questions addressing apoptosis. PMID:20972831

  3. [Role of renal sympathetic nerve and oxidative stress in foot shock-induced hypertension in rats].

    Science.gov (United States)

    Jiang, Ren-Di; Zhang, Zhe; Xu, Jian-Bing; Dong, Tao; Zhang, Guo-Xing

    2015-06-25

    The present study was aimed to investigate the roles of renal sympathetic nerve and oxidative stress in the development of foot shock-induced hypertension. Ninety rats were divided into 6 groups (the number of each group was 15): control group, foot shock group, denervation of renal sympathetic nerve group, denervation of renal sympathetic nerve + foot shock group, Tempol treatment + foot shock group, denervation of renal sympathetic nerve + Tempol treatment + foot shock group. Rats were received electrical foot shock for 14 days (2-4 mA, 75 V, shocks of 50-100 ms every 30 s, for 4 h each session through an electrified grid floor every day). Renal sympathetic ablation was used to remove bilateral renal sympathetic nerve in rats (rats were allowed to recover for one week before the beginning of the foot shock procedure). The antioxidant Tempol was injected intraperitoneally at 1 h before foot shock. Systolic blood pressure was measured at 1 h after foot shock on day 0, 3, 7, 10 and 14. Contents of thiobarbituric acid reactive substance (TBARS), renin, angiotensin II (AngII) and glutathione peroxidase (GSH-Px) in plasma were measured by ELISA after 14-day foot shock. The results showed that systolic blood pressure of foot shock group was significantly increased (P indirectly activate renin-angiotensin-aldosterone system, so the foot shock-induced high blood pressure may be maintained and hypertension may therefore be produced.

  4. Counter-propagating radiative shock experiments on the Orion laser facility

    Science.gov (United States)

    Clayson, T.; Suzuki-Vidal, F.; Lebedev, S. V.; Swadling, G. F.; Burdiak, G. C.; Patankar, S.; Smith, R. A.; Foster, J.; Skidmore, J.; Gumbrell, E.; Graham, P.; Danson, C.; Stehlé, C.; Singh, R. L.; Chaulagain, U.; Larour, J.; Kozlova, M.; Spindloe, C.

    2016-10-01

    The Orion high-power laser facility, at AWE Aldermaston UK, was used to produce hyper-sonic radiative shocks, travelling at 60km/s, in noble gases, between 0.1 and 1.0 bar. These experiments aimed to study the radiative precursor, a heat and ionization wave preceding the shock front, and dynamics of colliding radiative shocks. X-ray backlighting and optical self-emission streak imaging were used to study the shock front and collision dynamics, while multi-frame and streaked interferometry were used to simultaneously study the radiative precursor. These experiments compared the shock and collision dynamics in different gases (e.g. Ne, Ar, Kr, Xe), while maintaining a constant mass density, to vary the strength of the radiative precursor. Some shocks exhibited features suggesting the formation of hydrodynamic or radiative instabilities. The experimental data is in good agreement with 2-D rad-hydro simulations and provides a new benchmark for codes to be tested against. Supported by Orion Academic Access, the Royal Society, EPSRC, Labex PLAS@PAR.

  5. Experimental and Numerical Simulation Research on Micro-Gears Fabrication by Laser Shock Punching Process

    Directory of Open Access Journals (Sweden)

    Huixia Liu

    2015-07-01

    Full Text Available The aim of this paper is to fabricate micro-gears via laser shock punching with Spitlight 2000 Nd-YAG Laser, and to discuss effects of process parameters namely laser energy, soft punch properties and blank-holder on the quality of micro-gears deeply. Results show that dimensional accuracy is the best shocked at 1690 mJ. Tensile fracture instead of shear fracture is the main fracture mode under low laser energy. The soft punch might cause damage to punching quality when too high energy is employed. Appropriate thickness and hardness of soft punch is necessary. Silica gel with 200 µm in thickness is beneficial to not only homogenize energy but also propagate the shock wave. Polyurethane films need more energy than silica gel with the same thickness. In addition, blank-holders with different weight levels are used. A heavier blank-holder is more beneficial to improve the cutting quality. Furthermore, the simulation is conducted to reveal typical stages and the different deformation behavior under high and low pulse energy. The simulation results show that the fracture mode changes under lower energy.

  6. Uniformity of spherical shock wave dynamically stabilized by two successive laser profiles in direct-drive inertial confinement fusion implosions

    Energy Technology Data Exchange (ETDEWEB)

    Temporal, M., E-mail: mauro.temporal@hotmail.com [Centre de Mathématiques et de Leurs Applications, ENS Cachan and CNRS, 61 Av. du President Wilson, F-94235 Cachan Cedex (France); Canaud, B. [CEA, DIF, F-91297 Arpajon Cedex (France); Garbett, W. J. [AWE plc, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Ramis, R. [ETSI Aeronáutica y del Espacio, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2015-10-15

    The implosion uniformity of a directly driven spherical inertial confinement fusion capsule is considered within the context of the Laser Mégajoule configuration. Two-dimensional (2D) hydrodynamic simulations have been performed assuming irradiation with two laser beam cones located at 49° and 131° with respect to the axis of symmetry. The laser energy deposition causes an inward shock wave whose surface is tracked in time, providing the time evolution of its non-uniformity. The illumination model has been used to optimize the laser intensity profiles used as input in the 2D hydro-calculations. It is found that a single stationary laser profile does not maintain a uniform shock front over time. To overcome this drawback, it is proposed to use two laser profiles acting successively in time, in order to dynamically stabilize the non-uniformity of the shock front.

  7. Laser-Based Alkene Sensors for Shock Tube Kinetics

    Science.gov (United States)

    2016-06-28

    laser absorption, ethylene , iso-butene REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8...during pyrolysis and oxidation should be feasible. These state-of-the-art sensors will also be used in the training and education of the next generation...6  Effect on graduate education

  8. Eliminating welding residual stress by laser shock%激光冲击消除焊接残余应力

    Institute of Scientific and Technical Information of China (English)

    王学德; 胡雅骥; 王路成; 张东方

    2012-01-01

    The different viewpoints of welding residual stress were analyzed and the feasibility of erasing the welding residual stress by laser shock was discussed. Nanosecond pulse and 1000MW laser irradiation on the materials could induce the high pres-sure plasma shock wave and generate the plastic deformation, thus it could effectively eliminate welding residual tensile stress. The experiments of 12Cr2Ni4A steel welding joints processed with different welding materials and methods under laser shock pro-cessing (LSP) were designed, and conducted through four different welding statuses. Results showed that laser shock could erase the welding residual tensile stress caused by argon arc welding and plasma welding, and also could improve the distribution of force on the surface of welding joints. Using NAK80 welding material and plasma welding, the compression stress reached to 848MPa, which led to a sharp increase of mechanical properties of the weld joint.%对现有焊接残余应力的理论进行分析,讨论激光冲击处理消除焊接残余应力的可行性,认为短脉冲高峰值功率密度的激光冲击焊接接头产生的等离子体冲击波,可使焊接接头表面产生塑性应变,能有效消除焊接残余拉应力.文章设计了激光冲击强化12Cr2Ni4A钢焊接接头试验,通过选择不同焊接材料和焊接方式,设计了4种焊接状态,分别进行激光冲击强化.试验结果表明,激光冲击强化均能肖除氩弧焊和等离子焊等焊接方式的焊接残余拉应力,改善焊接接头表面的力学分布,在选用NAK80焊材和等离子体焊方式时,形成的残余压应力幅值高达884MPa,极大提升了焊接接头的力学性能.

  9. Laser induced white lighting of graphene foam

    Science.gov (United States)

    Strek, Wieslaw; Tomala, Robert; Lukaszewicz, Mikolaj; Cichy, Bartlomiej; Gerasymchuk, Yuriy; Gluchowski, Pawel; Marciniak, Lukasz; Bednarkiewicz, Artur; Hreniak, Dariusz

    2017-01-01

    Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.

  10. Laser induced white lighting of graphene foam

    Science.gov (United States)

    Strek, Wieslaw; Tomala, Robert; Lukaszewicz, Mikolaj; Cichy, Bartlomiej; Gerasymchuk, Yuriy; Gluchowski, Pawel; Marciniak, Lukasz; Bednarkiewicz, Artur; Hreniak, Dariusz

    2017-01-01

    Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources. PMID:28112254

  11. Laser-Induced Incandescence: Excitation Intensity

    Science.gov (United States)

    Vander Wal, Randall L.; Jensen, Kirk A.

    1998-03-01

    Assumptions of theoretical laser-induced incandescence (LII) models along with possible effects of high-intensity laser light on soot aggregates and the constituent primary particles are discussed in relation to selection of excitation laser fluence. Ex situ visualization of laser-heated soot by use of transmission electron microscopy reveals significant morphological changes (graphitization) induced by pulsed laser heating. Pulsed laser transmission measurements within a premixed laminar sooting flame suggest that soot vaporization occurs for laser fluences greater than 0.5 J cm 2 at 1064 nm. Radial LII intensity profiles at different axial heights in a laminar ethylene gas jet diffusion flame reveal a wide range of signal levels depending on the laser fluence that is varied over an eight fold range. Results of double-pulse excitation experiments in which a second laser pulse heats in situ the same soot that was heated by a prior laser pulse are detailed. These two-pulse measurements suggest varying degrees of soot structural change for fluences below and above a vaporization threshold of 0.5 J cm 2 at 1064 nm. Normalization of the radial-resolved LII signals based on integrated intensities, however, yields self-similar profiles. The self-similarity suggests robustness of LII for accurate relative measurement of soot volume fraction despite the morphological changes induced in the soot, variations in soot aggregate and primary particle size, and local gas temperature. Comparison of LII intensity profiles with soot volume fractions ( f v ) derived by light extinction validates LII for quantitative determination of f v upon calibration for laser fluences ranging from 0.09 to 0.73 J cm 2 .

  12. Evaluation of the microcirculation in a rabbit hemorrhagic shock model using laser Doppler imaging.

    Science.gov (United States)

    Luo, Zhenchun; Wang, Pengfei; Zhang, An; Zuo, Guoqing; Zheng, Yuanyi; Huang, Yan

    2015-01-01

    The aim of this study is to evaluate the feasibility of Laser Doppler imaging (LDI) for noninvasive and dynamic assessment of hemorrhagic shock in a rabbit model. A rabbit model of hemorrhagic shock was generated and LDI of the microcirculation in the rabbit ears was performed before and at 0, 30, 60, and 90 min after hemorrhage. The CCD (Charge Coupled Device) image of the ears, the mean arterial pressure (MAP) and the heart rate (HR) were monitored. The mean LDI flux was calculated. The HR of rabbits was significantly (p 0.05). Both the flux numbers and the red-to-blue color changes on LDI imaging showed the reduction of the microcirculation. LDI imaging is a noninvasive and non-contact approach to evaluate the microcirculation and may offer benefits in the diagnosis and treatment of hemorrhage shock. Further studies are needed to confirm its effectiveness in clinical practice.

  13. Evaluation of the microcirculation in a rabbit hemorrhagic shock model using laser Doppler imaging.

    Directory of Open Access Journals (Sweden)

    Zhenchun Luo

    Full Text Available The aim of this study is to evaluate the feasibility of Laser Doppler imaging (LDI for noninvasive and dynamic assessment of hemorrhagic shock in a rabbit model. A rabbit model of hemorrhagic shock was generated and LDI of the microcirculation in the rabbit ears was performed before and at 0, 30, 60, and 90 min after hemorrhage. The CCD (Charge Coupled Device image of the ears, the mean arterial pressure (MAP and the heart rate (HR were monitored. The mean LDI flux was calculated. The HR of rabbits was significantly (p 0.05. Both the flux numbers and the red-to-blue color changes on LDI imaging showed the reduction of the microcirculation. LDI imaging is a noninvasive and non-contact approach to evaluate the microcirculation and may offer benefits in the diagnosis and treatment of hemorrhage shock. Further studies are needed to confirm its effectiveness in clinical practice.

  14. Shock induced chemical reactions in energetic structural materials

    Science.gov (United States)

    Reding, Derek J.

    Energetic structural materials (ESMs) constitute a new class of materials that provide dual functions of strength and energetic characteristics. ESMs are typically composed of micron-scale or nano-scale intermetallic mixtures or mixtures of metals and metal oxides, polymer binders, and structural reinforcements. Voids are included to produce a composite with favorable chemical reaction characteristics. In this thesis, a continuum approach is used to simulate gas-gun or explosive loading experiments where a strong shock is induced in the ESM by an impacting plate. Algorithms are developed to obtain equations of state of mixtures. It is usually assumed that the shock loading increases the energy of the ESM and causes the ESM to reach the transition state. It is also assumed that the activation energy needed to reach the transition state is a function of the temperature of the mixture. In this thesis, it is proposed that the activation energy is a function of temperature and the stress state of the mixture. The incorporation of such an activation energy is selected in this thesis. Then, a multi-scale chemical reaction model for a heterogeneous mixture is introduced. This model incorporates reaction initiation, propagation, and extent of completed reaction in spatially heterogeneous distributions of reactants. A new model is proposed for the pore collapse of mixtures. This model is formulated by modifying the Carol, Holt, and Nesterenko spherically symmetric model to include mixtures and compressibility effects. Uncertainties in the model result from assumptions in formulating the models for continuum relationships and chemical reactions in mixtures that are distributed heterogeneously in space and in numerical integration of the resulting equations. It is important to quantify these uncertainties. In this thesis, such an uncertainty quantification is investigated by systematically identifying the physical processes that occur during shock compression of ESMs which are

  15. Vlasov modelling of laser-driven collisionless shock acceleration of protons

    Energy Technology Data Exchange (ETDEWEB)

    Svedung Wettervik, B.; DuBois, T. C.; Fülöp, T. [Department of Applied Physics, Chalmers University of Technology, Gothenburg (Sweden)

    2016-05-15

    Ion acceleration due to the interaction between a short high-intensity laser pulse and a moderately overdense plasma target is studied using Eulerian Vlasov–Maxwell simulations. The effects of variations in the plasma density profile and laser pulse parameters are investigated, and the interplay of collisionless shock and target normal sheath acceleration is analyzed. It is shown that the use of a layered-target with a combination of light and heavy ions, on the front and rear side, respectively, yields a strong quasi-static sheath-field on the rear side of the heavy-ion part of the target. This sheath-field increases the energy of the shock-accelerated ions while preserving their mono-energeticity.

  16. Shock wave acceleration of protons in inhomogeneous plasma interacting with ultrashort intense laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Lecz, Zs. [ELI-ALPS, ELI-HU Nkft., Szeged (Hungary); Andreev, A. [ELI-ALPS, ELI-HU Nkft., Szeged (Hungary); Max-Born Institute, Berlin (Germany)

    2015-04-15

    The acceleration of protons, triggered by solitary waves in expanded solid targets is investigated using particle-in-cell simulations. The near-critical density plasma is irradiated by ultrashort high power laser pulses, which generate the solitary wave. The transformation of this soliton into a shock wave during propagation in plasma with exponentially decreasing density profile is described analytically, which allows to obtain a scaling law for the proton energy. The high quality proton bunch with small energy spread is produced by reflection from the shock-front. According to the 2D simulations, the mechanism is stable only if the laser pulse duration is shorter than the characteristic development time of the parasitic Weibel instability.

  17. Investigation of shock-induced and shock-assisted chemical reactions in molybdenum-silicon powder mixtures

    Science.gov (United States)

    Vandersall, Kevin Stewart

    1999-10-01

    In this research, chemical reactions occurring in molybdenum and silicon powder mixtures under "shock-induced" (those occurring during the high-pressure shock state) and "shock-assisted" (those occurring subsequent to the shock event, but due to bulk temperature increases) conditions were investigated. Differences in the densities and yield strengths of the two constituents, in addition to the large heat of reaction associated with molybdenum disilicide (MoSi2) formation can lead to shock-induced as well as shock-assisted reactions, which make this an ideal system to delineate the kinetics and mechanisms of reactions occurring in shock-compressed powder mixtures. Shock recovery experiments performed on Mo + 2 Si powder mixtures employing cylindrical implosion geometry showed thermally initiated reactions. A mixed phase eutectic type microstructure of MoSi2 and Mo 5Si3, resulting from reaction occurring due to melting of both reactants, was observed in axial regions of the cylindrical compacts. In regions surrounding the mach stem, melting of only silicon and reaction occurring via dissolution and re-precipitation forming MoSi2 spherules surrounding molybdenum particles in a melted and solidified silicon matrix was observed. The planar pressure shock recovery geometry showed a single phase MoSi2, microstructure formed due to a solid-state pressure-induced reaction process. The time-resolved instrumented experiments were performed using a single stage gas gun in the velocity range of 500 m/s to 1 km/s, and employed poly-vinyl di-flouride (PVDF) stress gauges placed at the front and rear surfaces of the powder to determine the crush strength, densification history, and reaction initiation threshold conditions. Time-resolved experiments performed on ˜58% dense Mo + 2 Si powder mixtures at input stresses less than 4 GPa, showed characteristics of powder densification and dispersed propagated wave stress profiles with rise time >˜40 nanoseconds. At input stress between

  18. Density bump formation in a collisionless electrostatic shock wave in a laser-ablated plasma

    CERN Document Server

    Garasev, M A; Kocharovsky, V V; Malkov, Yu A; Murzanev, A A; Nechaev, A A; Stepanov, A N

    2016-01-01

    The emergence of a density bump at the front of a collisionless electrostatic shock wave have been observed experimentally during the ablation of an aluminium foil by a femtosecond laser pulse. We have performed numerical simulations of the dynamics of this phenomena developing alongside the generation of a package of ion-acoustic waves, exposed to a continual flow of energetic electrons, in a collisionless plasma. We present the physical interpretation of the observed effects and show that the bump consists of transit particles, namely, the accelerated ions from the dense plasma layer, and the ions from the diluted background plasma, formed by a nanosecond laser prepulse during the ablation.

  19. Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Device

    Energy Technology Data Exchange (ETDEWEB)

    Schaeffer, D. B., E-mail: dschaeffer@physics.ucla.edu; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Vincena, S.; Van Compernolle, B.; Tripathi, S. K. P.; Gekelman, W.; Niemann, C. [Department of Physics and Astronomy, University of California - Los Angeles, Los Angeles, California 90095 (United States); Winske, D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2014-05-15

    The interaction of a laser-driven super-Alfvénic magnetic piston with a large, preformed magnetized ambient plasma has been studied by utilizing a unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at the University of California, Los Angeles. This platform provides experimental conditions of relevance to space and astrophysical magnetic collisionless shocks and, in particular, allows a detailed study of the microphysics of shock formation, including piston-ambient ion collisionless coupling. An overview of the platform and its capabilities is given, and recent experimental results on the coupling of energy between piston and ambient ions and the formation of collisionless shocks are presented and compared to theoretical and computational work. In particular, a magnetosonic pulse consistent with a low-Mach number collisionless shock is observed in a quasi-perpendicular geometry in both experiments and simulations.

  20. Exploring Astrophysically Relevant Bow Shocks Using MIFEDS and the OMEGA Laser

    Science.gov (United States)

    Levesque, Joseph; Kuranz, Carolyn; Young, Rachel; Fiksel, Gennady; Manuel, Mario; Trantham, Matthew; Klein, Sallee; Hartigan, Patrick; Liao, Andy; Li, Chikang

    2016-10-01

    We present current experiments using the Omega Laser Facility and their magneto-inertial fusion electrical discharge system (MIFEDS) to observe the effect of magnetic pressure on bow shock dynamics in an astrophysically relevant regime. Astrophysical bow shocks are an interesting phenomenon in which a shock forms when incident supersonic flow encounters a sufficiently magnetized medium surrounding an object. The most well-known example of this phenomena is the interaction of the solar wind with the Earth's magnetic field, which creates our magnetosphere. In our experiment the magnetosphere will be emulated by a current flowing through a curved wire to create an azimuthal magnetic field. To create the analogous solar wind, lasers rear-irradiate two opposing graphite targets so the plasma outflows collide and then expand along the collision plane toward the magnetized wires. We use the UV Thomson scattering diagnostic technique to determine plasma parameters along with optical imaging and proton radiography to characterize the plasma flow and the bow shock that forms. This work is supported by the U.S. DOE, through NNSA Grants DE-NA0002956 (SSAA) and DE-NA0002719 (NLUF), by the LLE under DE-NA0001944, and by the LLNL under subcontract B614207 to DE-AC52-07NA27344.

  1. An Experimental Study on Micro Clinching of Metal Foils with Cutting by Laser Shock Forming

    OpenAIRE

    Xiao Wang; Cong Li; Youjuan Ma; Zongbao Shen; Xianqing Sun; Chaofei Sha; Shuai Gao; Liyin Li; Huixia Liu

    2016-01-01

    This paper describes a novel technique for joining similar and dissimilar metal foils, namely micro clinching with cutting by laser shock forming. A series of experiments were conducted to study the deformation behavior of single layer material, during which many important process parameters were determined. The process window of the 1060 pure aluminum foils and annealed copper foils produced by micro clinching with cutting was analyzed. Moreover, similar material combination (annealed copper...

  2. Effects on Microstructure and Properties of Brass Treated by Laser Shock Processing

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; YAO Zhen-qiang

    2007-01-01

    Laser shock processing (LSP) has been proposed as a new surface treatment for improving hardness,wear resistance and fatigue. In this paper, the effect of LSP on brass is investigated with experiment. Micro-hardness, roughness, microstructure, wear resistance and friction coefficient evolution are investigated for different parameters of LSP. The result shows that the roughness increases after LSP; no ablation is observed; the microstructure has no remarkable change; hardness and the wear resistance increase as the pulse density increases.

  3. Are vasopressors useful in toxin-induced cardiogenic shock?

    Science.gov (United States)

    Skoog, Cassandra A; Engebretsen, Kristin M

    2017-04-01

    Overdoses with cardio-depressive medications can result in toxin-induced cardiogenic shock (TICS), a life-threatening condition characterized by severe hypotension and ineffective tissue perfusion. Vasopressors are often employed in the treatment of shock to increase heart rate and blood pressure. We sought to conduct a systematic review of the literature to evaluate the effectiveness of vasopressors in improving hemodynamic function and survival in the treatment of TICS. We searched PubMed, EMBASE, TOXLINE, and International Pharmaceutical Abstracts. We included studies evaluating the use of vasopressors in humans or animals with TICS. We limited human study types to randomized controlled trials, clinical trials, observational studies, and case reports. Our search yielded 913 citations and 144 of these met our inclusion criteria. 130 were human case reports and 14 were animal studies. Human case report data showed vasopressors were ineffective more often than they were partially or fully effective. In the majority of animal studies, vasopressor treatment failed to improve hemodynamic parameters and resulted in decreased survival. Human case reports and controlled animal experiments lead to different conclusions about vasopressors in TICS. Most animal studies indicate that vasopressors impair hemodynamic function and increase mortality. In contrast, human case reports suggest that vasopressors are often ineffective but not necessarily harmful.

  4. Studies on the robustness of shock-ignited laser fusion targets

    Science.gov (United States)

    Atzeni, S.; Schiavi, A.; Marocchino, A.

    2011-03-01

    Several aspects of the sensitivity of a shock-ignited inertial fusion target to variation of parameters and errors or imperfections are studied by means of one-dimensional and two-dimensional numerical simulations. The study refers to a simple all-DT target, initially proposed for fast ignition (Atzeni et al 2007 Phys. Plasmas 7 052702) and subsequently shown to be also suitable for shock ignition (Ribeyre et al 2009 Plasma Phys. Control. Fusion 51 015013). It is shown that the growth of both Richtmyer-Meshkov and Rayleigh-Taylor instability (RTI) at the ablation front is reduced by laser pulses with an adiabat-shaping picket. An operating window for the parameters of the ignition laser spike is described; the threshold power depends on beam focusing and synchronization with the compression pulse. The time window for spike launch widens with beam power, while the minimum spike energy is independent of spike power. A large parametric scan indicates good tolerance (at the level of a few percent) to target mass and laser power errors. 2D simulations indicate that the strong igniting shock wave plays an important role in reducing deceleration-phase RTI growth. Instead, the high hot-spot convergence ratio (ratio of initial target radius to hot-spot radius at ignition) makes ignition highly sensitive to target mispositioning.

  5. Shock-induced termination of reentrant cardiac arrhythmias: Comparing monophasic and biphasic shock protocols

    Energy Technology Data Exchange (ETDEWEB)

    Bragard, Jean, E-mail: jbragard@unav.es; Simic, Ana; Elorza, Jorge [Department of Physics and Applied Math., University of Navarra, Pamplona (Spain); Grigoriev, Roman O.; Fenton, Flavio H. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Cherry, Elizabeth M. [School of Mathematical Sciences, Rochester Institute of Technology, Rochester, New York 14623 (United States); Gilmour, Robert F. [University of Prince Edward Island, Charlottetown C1A 4P3 (Canada); Otani, Niels F. [School of Mathematical Sciences, Rochester Institute of Technology, Rochester, New York 14623 (United States); Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 (United States)

    2013-12-15

    In this article, we compare quantitatively the efficiency of three different protocols commonly used in commercial defibrillators. These are based on monophasic and both symmetric and asymmetric biphasic shocks. A numerical one–dimensional model of cardiac tissue using the bidomain formulation is used in order to test the different protocols. In particular, we performed a total of 4.8 × 10{sup 6} simulations by varying shock waveform, shock energy, initial conditions, and heterogeneity in internal electrical conductivity. Whenever the shock successfully removed the reentrant dynamics in the tissue, we classified the mechanism. The analysis of the numerical data shows that biphasic shocks are significantly more efficient (by about 25%) than the corresponding monophasic ones. We determine that the increase in efficiency of the biphasic shocks can be explained by the higher proportion of newly excited tissue through the mechanism of direct activation.

  6. Experimental and Theoretical Investigation of Shock-Induced Reactions in Energetic Materials.

    Energy Technology Data Exchange (ETDEWEB)

    Kay, Jeffrey J; Park, Samuel; Kohl, Ian Thomas; Knepper, Robert

    2017-09-01

    In this work, shock-induced reactions in high explosives and their chemical mechanisms were investigated using state-of-the-art experimental and theoretical techniques. Experimentally, ultrafast shock interrogation (USI, an ultrafast interferometry technique) and ultrafast absorption spectroscopy were used to interrogate shock compression and initiation of reaction on the picosecond timescale. The experiments yielded important new data that appear to indicate reaction of high explosives on the timescale of tens of picoseconds in response to shock compression, potentially setting new upper limits on the timescale of reaction. Theoretically, chemical mechanisms of shock-induced reactions were investigated using density functional theory. The calculations generated important insights regarding the ability of several hypothesized mechanisms to account for shock-induced reactions in explosive materials. The results of this work constitute significant advances in our understanding of the fundamental chemical reaction mechanisms that control explosive sensitivity and initiation of detonation. * Principal Investigator. jjkay@sandia.gov

  7. Sequential shock induced switch tests for Eglin Air Force Base

    Energy Technology Data Exchange (ETDEWEB)

    Cech, R.D.

    1994-08-11

    Tests were performed at EG&G Mound Applied Technologies to investigate the effect of using the tangential shock wave from detonating Extex explosive to cause shock conduction of a Kapton dielectric. Two voltages (600 and 4000) were switched from a 600 pF capacitor. Timing between four shock switches and four pin switches was found and compared during a single detonation event. Electrical conduction was observed between shock switches and the current paths were found.

  8. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  9. Effects of biliverdin administration on acute lung injury induced by hemorrhagic shock and resuscitation in rats.

    Directory of Open Access Journals (Sweden)

    Junko Kosaka

    Full Text Available Hemorrhagic shock and resuscitation induces pulmonary inflammation that leads to acute lung injury. Biliverdin, a metabolite of heme catabolism, has been shown to have potent cytoprotective, anti-inflammatory, and anti-oxidant effects. This study aimed to examine the effects of intravenous biliverdin administration on lung injury induced by hemorrhagic shock and resuscitation in rats. Biliverdin or vehicle was administered to the rats 1 h before sham or hemorrhagic shock-inducing surgery. The sham-operated rats underwent all surgical procedures except bleeding. To induce hemorrhagic shock, rats were bled to achieve a mean arterial pressure of 30 mmHg that was maintained for 60 min, followed by resuscitation with shed blood. Histopathological changes in the lungs were evaluated by histopathological scoring analysis. Inflammatory gene expression was determined by Northern blot analysis, and oxidative DNA damage was assessed by measuring 8-hydroxy-2' deoxyguanosine levels in the lungs. Hemorrhagic shock and resuscitation resulted in prominent histopathological damage, including congestion, edema, cellular infiltration, and hemorrhage. Biliverdin administration prior to hemorrhagic shock and resuscitation significantly ameliorated these lung injuries as judged by histopathological improvement. After hemorrhagic shock and resuscitation, inflammatory gene expression of tumor necrosis factor-α and inducible nitric oxide synthase were increased by 18- and 8-fold, respectively. Inflammatory gene expression significantly decreased when biliverdin was administered prior to hemorrhagic shock and resuscitation. Moreover, after hemorrhagic shock and resuscitation, lung 8-hydroxy-2' deoxyguanosine levels in mitochondrial DNA expressed in the pulmonary interstitium increased by 1.5-fold. Biliverdin administration prior to hemorrhagic shock and resuscitation decreased mitochondrial 8-hydroxy-2' deoxyguanosine levels to almost the same level as that in the

  10. A study on micro hydroforming using shock wave of 355 nm UV-pulsed laser

    Science.gov (United States)

    Je, Gyeongju; Malka, Dror; Kim, Hyesu; Hong, Sungmoo; Shin, Bosung

    2017-09-01

    In this paper, we proposed a new manufacturing technology of micro hydroforming using 355 nm ultraviolet(UV)-pulsed laser. Hydroforming is known as a well-established technology to manufacture metallic parts, in particular for mass production of sheet metal, for several industrial applications such as automobiles, battery and military products. In addition laser shock processing(LSP) has been developed as the expanded applications of electrical and mechatronic devices. When the material was exposed to laser beam, multiple phenomena like the photochemical, the photothermal and the photomechanical effect are simultaneously occurred at the spot area. Especially, the photothermal effect due to laser heat transfer makes it hard to improve the accuracy of laser processing. To reduce the thermal effect and to enhance the photomechanical effect, the laser was irradiated under water in this paper. Strong forming pressure of LSP was provided by the higher density of water than air, which could help directly manufacture the thin sheet metal materials like as laser direct writing. We also conducted computer simulation using finite element method(FEM) to demonstrate its deformation behaviour with and without the strain rate effect of 104-105 (sec-1). Compared with conventional processing technology, this new method can provide high selectivity, excellent hydroforming efficiency and lower cost to achieve micro grooving pattern on the surface of thin metal sheet.

  11. Random-type scanning patterns in laser shock peening without absorbing coating in 2024-T351 Al alloy: A solution to reduce residual stress anisotropy

    Science.gov (United States)

    Correa, C.; Peral, D.; Porro, J. A.; Díaz, M.; Ruiz de Lara, L.; García-Beltrán, A.; Ocaña, J. L.

    2015-10-01

    Laser Shock Peening (LSP) is considered as an alternative technology to shot peening (SP) for the induction of compressive residual stresses in metallic alloys in order to improve their fatigue, corrosion and wear resistance. Since laser pulses generated by high-intensity laser systems cover only a small area, laser pulses are generally overlapped and scanned in a zigzag-type pattern to cover completely the surface to be treated. However, zigzag-type scanning patterns induce residual stress anisotropy as collateral effect. The purpose of this paper is to describe and explain, for the first time and with the aid of the numerical model developed by the authors, the influence of the scanning pattern directionality on the residual stress tensor. As an effective solution, the authors propose the application of random-type scanning patterns instead of zigzag-type in order to reduce the mentioned residual stress anisotropy.

  12. The Effect of Shock Stress and Field Strength on Shock-Induced Depoling of Normally Poled PZT 95/5

    Energy Technology Data Exchange (ETDEWEB)

    CHHABILDAS,LALIT C.; FURNISH,MICHAEL D.; MONTGOMERY,STEPHEN T.; SETCHELL,ROBERT E.

    1999-09-01

    Shock-induced depoling of the ferroelectric ceramic PZT 95/5 is utilized in a number of pulsed power devices. Several experimental and theoretical efforts are in progress in order to improve numerical simulations of these devices. In this study we have examined the shock response of normally poled PZT 95/5 under uniaxial strain conditions. On each experiment the current produced in an external circuit and the transmitted waveform at a window interface were recorded. The peak electrical field generated within the PZT sample was varied through the choice of external circuit resistance. Shock pressures were varied from 0.6 to 4.6 GPa, and peak electrical fields were varied from 0.2 to 37 kV/cm. For a 2.4 GPa shock and the lowest peak field, a nearly constant current governed simply by the remanent polarization and the shock velocity was recorded. Both decreasing the shock pressure and increasing the electrical field resulted in reduced current generation, indicating a retardation of the depoling kinetics.

  13. Intraluminal bubble dynamics induced by lithotripsy shock wave

    Science.gov (United States)

    Song, Jie; Bai, Jiaming; Zhou, Yufeng

    2016-12-01

    Extracorporeal shock wave lithotripsy (ESWL) has been the first option in the treatment of calculi in the upper urinary tract since its introduction. ESWL-induced renal injury is also found after treatment and is assumed to associate with intraluminal bubble dynamics. To further understand the interaction of bubble expansion and collapse with the vessel wall, the finite element method (FEM) was used to simulate intraluminal bubble dynamics and calculate the distribution of stress in the vessel wall and surrounding soft tissue during cavitation. The effects of peak pressure, vessel size, and stiffness of soft tissue were investigated. Significant dilation on the vessel wall occurs after contacting with rapid and large bubble expansion, and then vessel deformation propagates in the axial direction. During bubble collapse, large shear stress is found to be applied to the vessel wall at a clinical lithotripter setting (i.e. 40 MPa peak pressure), which may be the mechanism of ESWL-induced vessel rupture. The decrease of vessel size and viscosity of soft tissue would enhance vessel deformation and, consequently, increase the generated shear stress and normal stresses. Meanwhile, a significantly asymmetric bubble boundary is also found due to faster axial bubble expansion and shrinkage than in radial direction, and deformation of the vessel wall may result in the formation of microjets in the axial direction. Therefore, this numerical work would illustrate the mechanism of ESWL-induced tissue injury in order to develop appropriate counteractive strategies for reduced adverse effects.

  14. Heat pump processes induced by laser radiation

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.

    1980-01-01

    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  15. Argon laser-induced damage in the goldfish (C. auratus) retina following whole-body hyperthermia

    Science.gov (United States)

    Deaton, Michael A.; Lund, David J.; Schuschereba, Steven T.; Dahlberg, Ann M.; Cowan, Beth L.; Lester, Paul; Odom, Daniel G.

    1990-07-01

    The heat shock response is a phenomenon common to all cells and is characterized by an increase in the rate of synthesis of intracellular heat shock proteins (HSPs) . The response occurs following rapid transient increases in terrerature sufficient to cause stress but not cell death. HSPs appear to perform protective functions that raise the cell''s tolerance to diverse noxious stimuli. Thus we postulated that we could limit laser-induced retinal darriage through induction of the heat shock -response. Corrmon goldfish (C. auratus) made hyperthermic by immersion in 35C water for 15 minutes and radiolabeled with [355]methionine showed retinal liSPs with apparent molecular weights of 110 90 70 and 35 kilodaltons. To test the protective effects of HSPs against laser injury goldfish were made hyperthermic and 4 and 24 hr later their retinas were irradiated with argon laser light (51 4 . 5 nm spot size at the cornea 3. 0 mm irradiance 125 mW/cm2) . NonhyperLhermic animals served as controls. Following 24 hr of recovery fish were terminated and retinas fixed for histology. Fundus photographs were taken irrunediately after laser exposure . Lesion diameters were measured from fundus photographs and evaluated statistically. The mean retinal lesion diameters of fish not subjected to hyperthermJ. a laser exposed 4 hr post hyperLhermia and laser exposed 24 hr post hyperthermia were 10. 25 1. 4 SD 8. 82 2. 1 SD and 6. 78

  16. Laser plasma physics in shock ignition – transition from collisional to collisionless absorption

    Directory of Open Access Journals (Sweden)

    Klimo O.

    2013-11-01

    Full Text Available Shock Ignition is considered as a relatively robust and efficient approach to inertial confinement fusion. A strong converging shock, which is used to ignite the fuel, is launched by a high power laser pulse with intensity in the range of 1015 − 1016 W/cm2 (at the wavelength of 351 nm. In the lower end of this intensity range the interaction is dominated by collisions while the parametric instabilities are playing a secondary role. This is manifested in a relatively weak reflectivity and efficient electron heating. The interaction is dominated by collective effects at the upper edge of the intensity range. The stimulated Brillouin and Raman scattering (SBS and SRS respectively take place in a less dense plasma and cavitation provides an efficient collisionless absorption mechanism. The transition from collisional to collisionless absorption in laser plasma interactions at higher intensities is studied here with the help of large scale one-dimensional Particle-in-Cell (PIC simulations. The relation between the collisional and collisionless processes is manifested in the energy spectrum of electrons transporting the absorbed laser energy and in the spectrum of the reflected laser light.

  17. Molecular shock response of explosives: electronic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrne, Shawn D [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory; Eakins, Daniel E [Los Alamos National Laboratory

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  18. Heat shock transcription factors regulate heat induced cell death in a rat histiocytoma

    Indian Academy of Sciences (India)

    Kolla V, P Rasad; Aftab Taiyab; D Jyothi; Usha K Srinivas; Amere S Sreedhar

    2007-04-01

    Heat shock response is associated with the synthesis of heat shock proteins (Hsps) which is strictly regulated by different members of heat shock transcription factors (HSFs). We previously reported that a rat histiocytoma, BC-8 failed to synthesize Hsps when subjected to typical heat shock conditions (42°C, 60 min). The lack of Hsp synthesis in these cells was due to a failure in HSF1 DNA binding activity. In the present study we report that BC-8 tumor cells when subjected to heat shock at higher temperature (43°C, 60 min) or incubation for longer time at 42°C, exhibited necrosis characteristics; however, under mild heat shock (42°C, 30 min) conditions cells showed activation of autophagy. Mild heat shock treatment induced proteolysis of HSF1, and under similar conditions we observed an increase in HSF2 expression followed by its enhanced DNA binding activity. Inhibiting HSF1 proteolysis by reversible proteasome inhibition failed to inhibit heat shock induced autophagy. Compromising HSF2 expression but not HSF1 resulted in the inhibition of autophagy, suggesting HSF2 dependent activation of autophagy. We are reporting for the first time that HSF2 is heat inducible and functions in heat shock induced autophagic cell death in BC-8 tumor cells.

  19. Laser-Accelerated Ions from a Shock-Compressed Gas Foil

    Science.gov (United States)

    Helle, M. H.; Gordon, D. F.; Kaganovich, D.; Chen, Y.; Palastro, J. P.; Ting, A.

    2016-10-01

    We present results of energetic laser-ion acceleration from a tailored, near solid density gas target. Colliding hydrodynamic shocks compress a pure hydrogen gas jet into a 70 μ m thick target prior to the arrival of the ultraintense laser pulse. A density scan reveals the transition from a regime characterized by a wide angle, low-energy beam (target normal sheath acceleration) to one of a more focused beam with a high-energy halo (magnetic vortex acceleration). In the latter case, three-dimensional simulations show the formation of a Z pinch driven by the axial current resulting from laser wakefield accelerated electrons. Ions at the rear of the target are then accelerated by a combination of space charge fields from accelerated electrons and Coulombic repulsion as the pinch dissipates.

  20. Athermal Annealing of Semiconductors Using Shock Waves Generated by a Laser-Plasma

    Science.gov (United States)

    Fischer, R. P.; Grun, J.; Mignogna, R.; Donnelly, D. W.; Covington, B.

    2004-07-01

    We are investigating an annealing technique in which shock or sound waves generated by a laser-plasma are used to anneal a semiconductor. The athermal annealing (AA) process occurs very rapidly, which results in almost no diffusion of. dopants. A HeNe laser is used to measure the reflectivity of the silicon as a function of time. Measurements show that the annealing occurs in 1.8 μsec, which is the acoustic time scale for waves to propagate from the focus through the AA region. A knife-edge technique is employed to study acoustic waves in the sample by measuring the deflection of the probe beam. Initial results for aluminum samples irradiated at modest laser intensities (200 mJ, 50 nsec) show well-defined surface acoustic waves. However, both silicon and GaAs have more complicated structure which resemble Lamb (plate) waves.

  1. Spatial confinement in laser-induced breakdown spectroscopy

    Science.gov (United States)

    Li, Xingwen; Yang, Zefeng; Wu, Jian; Wei, Wenfu; Qiu, Yan; Jia, Shenli; Qiu, Aici

    2017-01-01

    The spatial confinement of plasma produced by a nanosecond laser is investigated using time resolved spectroscopy, fast imaging, interferometry, and numerical computation. The dynamics of the plasma, depending on shock waves, laser power, and wall distances, are studied. Experimental results confirm that the plasma is constricted by the reflected shock associated with a temperature and density gradient. The peak laser power determines the initial plasma parameters which affect the spectral intensities and the velocity of the reflective shock waves. The wall distance determines the reflection time of the shocks, which in turn influences the time delay of the collision between the two reflective shocks. The numerical results reveal a fast propagation process surrounding the reflective shocks, which indicates that the velocity of the reflective shock wave is influenced by the density of the plasma. The maximum enhancement factor ~5.2 is realized at a delay time of 11.7 µs under a pulse laser energy of 180 mJ and a wall distance of 9 mm.

  2. Optodynamic analysis of pulsed-laser processing with a Nd:YAG laser

    OpenAIRE

    Strgar, Simon; Možina, Janez

    2015-01-01

    Laser drilling and laser marking of metals with a pulsed Nd:YAG laser are discussed. Some characteristics of pulsed-laser processing and the possibilities of process optodynamic analysis are presented for the laser-drilling of aluminium. The optodynamic analysis is based on observation of generated shock waves, which propagate in the material as well as in the surrounding air during laser processing. For the detection of laser-induced shock waves in the air and for measurements of their chara...

  3. Treatment of Laser Induced Retinal Injuries.

    Science.gov (United States)

    1986-04-02

    END 1.0 1.18 Yl(-ROCOPY Ri yjTuION If ’,! (HART !. UIH; iLruud @ N TREATMENT OF LASER INDUCED RETINAL INJURIES (ANNUAL REPORT 00 DTIC Michael Belkin...NO. CCESSION NO _______________________________61102A I102BS1O0 CF 1i. 446 TITLE (Indude S*.curny Claifkaion) TREATMENT OF LASER INDUCED RETINAL... INJURIES PERSONAL AUTHOR(S) M. BELKIN N. NAVEH a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Mont. D y) S. PAGE COUNT FROM Xaj& TO l 2Ann

  4. Three suspected cases of sugammadex-induced anaphylactic shock.

    Science.gov (United States)

    Takazawa, Tomonori; Tomita, Yukinari; Yoshida, Nagahide; Tomioka, Akihiro; Horiuchi, Tatsuo; Nagata, Chie; Orihara, Masaki; Yamada, Makiko Hardy; Saito, Shigeru

    2014-01-01

    Sugammadex has a unique mechanism of action and is widely used because of its safety and efficacy. A few recent reports have described allergic reactions to clinical doses of sugammadex. We hereby describe another series of cases of possible anaphylaxis to sugammadex. We present three suspected cases of sugammadex-induced anaphylactic shock, including a 13-year-old boy who underwent laparoscopic appendectomy, a 75-year-old woman who underwent left knee arthroplasty, and a 34-year-old man who underwent left pansinectomy for sinobronchitis. All three patients received general anesthesia with rocuronium and their tracheas were intubated. Shortly after injection of sugammadex for reversal of rocuronium, all of them experienced a decrease in blood pressure along with mucocutaneous erythema. In the most severe case, reintubation after extubation was required due to difficulty in manual ventilation. All patients recovered with anti-allergic therapy. On later investigation, all three patients had a positive skin reaction to sugammadex. Our results suggest that physicians using sugammadex should be aware of the possibility of sugammadex-induced anaphylaxis.

  5. Fe78Si9B13非晶带材的激光冲击成形%Laser Shock Forming of Thin Film Fe78Si9B13 Metallic

    Institute of Scientific and Technical Information of China (English)

    林乐嘉; 季忠; 任振锋; 郑超; 刘韧

    2011-01-01

    激光冲击成形是在激光冲击强化基础上发展而来的,利用高能短脉冲激光诱导的等离子体爆炸所致的高压冲击波的力效应使板料产生塑性变形的新技术,目前已被广泛应用于铝、铜等金属薄板的成形中,而对于室温下脆性较大的非晶材料却很少涉及。本文对0.03mm厚的Fe78Si9B13非晶合金进行了激光冲击成形,利用X射线衍射仪(XRD)对冲击前后非晶带的结构进行研究,发现激光冲击后带材的非晶结构未发生变化。对激光冲击产生的弯曲角度进行研究发现随着冲击次数的增加,弯曲角度逐渐增大,但是增幅逐渐减少。%Laser shock forming (LSF) is a high strain rate plastic forming technology, which applies high-amplitude shock wave pressure induced by pulsed laser irradiation to form microparts or to adjust finished shapes. It has been extensively used for the forming of aluminum, copper and other ductile sheet metals. For metallic glasses, laser shock forming is more difficult to be implemented because amorphous alloys exhibit little macroscopic plasticity at room temperature especially under uniaxial compressive, high strain rate, or tensile conditions. In this paper, Fe78Si9B13 metallic glass films with a thickness of 0.03 mm are used for laser shock forming. Structural changes of the glass film before and after laser shock forming are studied by X-ray diffraction (XRD), the X-ray diffraction curves show that no crystallization is observed when the films were subjected to laser shock forming. Besides, the bending angles caused by laser shocks are investigated under the microscope, which show that the bending angle increases with the increase of the number of laser shocks and with the increase of the overlapping rate of laser spots, but the rate of increase decreases gradually. Moreover, large plastic bending deformation of Fe78Si9B13 metallic glass films has been achieved by laser shock.

  6. Shock-induced spall in copper: the effects of anisotropy, temperature, loading pulse and defect

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Shengnian [Los Alamos National Laboratory; Germann, Timothy C [Los Alamos National Laboratory; An, Qi [Los Alamos National Laboratory; Han, Li - Bo [USTC

    2009-07-28

    Shock-induced spall in Cu is investigated with molecular dynamics simulations. We examine spallation in initially perfect crystals and defective solids with grain boundaries (columnar bicrystals), stacking faults or vacancies, as well as the effect of temperature and loading pulses. Spall in single crystal Cu is anisotropic, and defects and high temperature may reduce the spall strength. Taylor-wave (triangular shock-release wave) loading is explored in comparison with square wave shock loading.

  7. Blast-Induced Acceleration in a Shock Tube: Distinguishing Primary and Tertiary Blast Injury

    Science.gov (United States)

    2014-10-01

    Annual, Year 2 3. DATES COVERED 4. TITLE AND SUBTITLE Blast-Induced Acceleration in a Shock Tube : Distinguishing Primary and Tertiary 5a...Using a highly characterized shock tube simulation of blast, rats will be exposed to BOP with varied peak amplitudes and impulse in association...understanding of the relation of the former to the latter. As the use of shock tubes has greatly expanded in recent years for biomedical research

  8. Structure and Dynamics of Shock-Induced Nanobubble Collapse in Water

    Science.gov (United States)

    Vedadi, Mohammad; Choubey, Amit; Nomura, Ken-Ichi; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya; van Duin, Adri

    2011-03-01

    Structure of water under shock and shock-induced collapse of nanobubbles in water are investigated with molecular dynamics simulations based on a reactive force field. Shock induces dramatic structural changes, including an ice-VII-like structural motif at a particle velocity of 1 km/s. The incipient ice VII formation and the calculated Hugoniot curve are in good agreement with experimental results. In the presence of a nanobubble, we observe a focused nanojet at the onset of nanobubble shrinkage and a secondary shock wave upon nanobubble collapse. The secondary shock wave propagates spherically backwards and induces high pressure as it propagates. Both the propagation velocity and the induced pressure are larger than those of the primary shock. We explored effects of nanobubble radius and shock amplitude on nanojet formation. The nanojet size increases by increasing particle velocity but the effect of increasing radius is more significant. The jet length scales linearly with the nanobubble radius, as observed in experiments on micron-to-millimeter size bubbles. Shock-induced collapse of a nanobubble in the vicinity of a cell membrane creates a transient nanopore when the nanojet impacts the membrane. Transient cell poration has potential applications in drug delivery.

  9. Laser-induced spark ignition of H2/O2/Ar mixtures

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Laser-induced spark ignition of hydrogen-oxygen-argon mixtures was experimentally investigated using a Q-swiched Nd:YAG laser to break down the gas at 532 nm. The laser-based high-speed schlieren system was employed to record flame front evolution for the gas mixtures with different initial pressure or laser output energy or argon dilution. The results show that the breakdown of the gas leads to the generation of ellipsoidal plasma. The rarefaction waves create the toroidal rings at the leading and trailing edges of the plasma, which provides a reasonable explanation for inward wrinkle of the plasma and the resultant flame. The toroidal rings at leading edge decays more rapidly and a gas lobe is generated that moves towards the laser. The hot gas in the plasma induces the generation of the spark kernel. Affected by the very weak shock wave or compression waves reflected off the wall, the initial laminar flame decelerates. The arc flame front interactions with the wall, reversed shock wave or compression waves, rarefaction waves, etc. induce the transition from laminar flame to turbulent one. These induce the transition from laminar flame to turbulent flame. For stoichiometric hydrogen-oxygen mixtures diluted by 76.92% argon at an initial pressure of 53.33 kPa, the minimum output energy of the laser is 15 mJ for successful laser-induced spark ignition. With increasing initial pressure or the output energy of the laser, or decreasing argon dilution, the speed of the flame front increases.

  10. Skew photonic Doppler velocimetry to investigate the expansion of a cloud of droplets created by micro-spalling of laser shock-melted metal foils

    Energy Technology Data Exchange (ETDEWEB)

    Loison, D.; Resseguier, T. de; Dragon, A. [Institut P' , UPR 3346, CNRS, Universite de Poitiers, ISAE-ENSMA - 1, av Clement Ader, 86961 Futuroscope (France); Mercier, P.; Benier, J.; Deloison, G.; Lescoute, E.; Sollier, A. [CEA, DAM, DIF - 91297 Arpajon (France)

    2012-12-01

    Dynamic fragmentation in the liquid state after shock-induced melting, usually referred to as micro-spallation, is an issue of great interest for both basic and applied sciences. Recent efforts have been devoted to the characterization of the resulting ejecta, which consist in a cloud of fine molten droplets. Major difficulties arise from the loss of free surface reflectivity at shock breakout and from the wide distribution of particle velocities within this cloud. We present laser shock experiments on tin and aluminium, to pressures ranging from about 70 to 160 GPa, with complementary diagnostics including a photonic Doppler velocimeter set at a small tilt angle from the normal to the free surface, which enables probing the whole cloud of ejecta. The records are roughly consistent with a one-dimensional theoretical description accounting for laser shock loading, wave propagation, phase transformations, and fragmentation. The main discrepancies between measured and calculated velocity profiles are discussed in terms of edge effects evidenced by transverse shadowgraphy.

  11. High-pressure phases in shock-induced melt of the unique highly shocked LL6 chondrite Northwest Africa 757

    Science.gov (United States)

    Hu, Jinping; Sharp, Thomas G.

    2016-07-01

    Northwest Africa 757 is unique in the LL chondrite group because of its abundant shock-induced melt and high-pressure minerals. Olivine fragments entrained in the melt transform partially and completely into ringwoodite. Plagioclase and Ca-phosphate transform to maskelynite, lingunite, and tuite. Two distinct shock-melt crystallization assemblages were studied by FIB-TEM analysis. The first melt assemblage, which includes majoritic garnet, ringwoodite plus magnetite-magnesiowüstite, crystallized at pressures of 20-25 GPa. The other melt assemblage, which consists of clinopyroxene and wadsleyite, solidified at ~15 GPa, suggesting a second veining event under lower pressure conditions. These shock features are similar to those in S6 L chondrites and indicate that NWA 757 experienced an intense impact event, comparable to the impact event that disrupted the L chondrite parent body at 470 Ma.

  12. Sensitive and rapid laser diagnostic for shock tube kinetics studies using cavity-enhanced absorption spectroscopy.

    Science.gov (United States)

    Sun, Kai; Wang, Shengkai; Sur, Ritobrata; Chao, Xing; Jeffries, Jay B; Hanson, Ronald K

    2014-04-21

    We report the first application of cavity-enhanced absorption spectroscopy (CEAS) using a coherent light source for sensitive and rapid gaseous species time-history measurements in a shock tube. Off-axis alignment and fast scanning of the laser wavelength were used to minimize coupling noise in a low-finesse cavity. An absorption gain factor of 83 with a measurement time resolution of 20 µs was demonstrated for C2H2 detection using a near-infrared transition near 1537 nm, corresponding to a noise-equivalent detection limit of 20 ppm at 296 K and 76 ppm at 906 K at 50 kHz. This substantial gain in signal, relative to conventional single-pass absorption, will enable ultra-sensitive species detection in shock tube kinetics studies, particularly useful for measurements of minor species and for studies of dilute reactive systems.

  13. The dynamic properties of shock-waves formed during laser ablation at sub-atmospheric pressures

    Science.gov (United States)

    Kapitan, D.; Coutts, D. W.

    2002-01-01

    The Sedov-Taylor-von Neumann (STN) theory has been shown to accurately describe the dynamic properties of shock-waves generated during pulsed-laser ablation of solid aluminium targets at visible wavelengths (510/578 nm) with 40 ns pulses with energies up to 3.5 mJ. A ballistic pendulum is used to measure the integrated recoil pressure in various inert atmospheres (He, Ne, Ar, Kr, Xe, N2, CO2, SF6) with pressures of 10-2 - 103 mbar. This recoil momentum is found to scale linearly with the background gas pressure P1 and with the square root of the molecular weight M1. More interestingly, the scaling with the ratio of heat capacities γ is verified to be a monotonically increasing function dependent on the form factor of the shock-wave. The validity of a modified STN theory which accounts for the piston mass is assessed.

  14. Evolution of Elastic X-ray Scattering in Laser-Shocked Warm Dense Li

    Energy Technology Data Exchange (ETDEWEB)

    Kugland, N L; Gregori, G; Bandyopadhyay, S; Brenner, C; Brown, C; Constantin, C; Glenzer, S H; Khattak, F; Kritcher, A L; Niemann, C; Otten, A; Pasley, J; Pelka, A; Roth, M; Spindloe, C; Riley, D

    2009-06-02

    We have studied the dynamics of warm dense Li with near-elastic x-ray scattering. Li foils were heated and compressed using shock waves driven by 4 ns long laser pulses. Separate 1 ns long laser pulses were used to generate a bright source of 2.96 keV Cl Ly-{alpha} photons for x-ray scattering, and the spectrum of scattered photons was recorded at a scattering angle of 120{sup o} using a HOPG crystal operated in the von Hamos geometry. A variable delay between the heater and backlighter laser beams measured the scattering time evolution. Comparison with radiation hydrodynamics simulations shows that the plasma is highly coupled during the first several nanoseconds, then relaxes to a moderate coupling state at later times. Near-elastic scattering amplitudes have been successfully simulated using the screened one-component plasma model. Our main finding is that the near-elastic scattering amplitudes are quite sensitive to the mean ionization state {bar Z}, and by extension to the choice of ionization model in the radiation-hydrodynamics simulations used to predict plasma properties within the shocked Li.

  15. Exercise-induced ROS in heat shock proteins response.

    Science.gov (United States)

    Dimauro, Ivan; Mercatelli, Neri; Caporossi, Daniela

    2016-09-01

    Cells have evolved multiple and sophisticated stress response mechanisms aiming to prevent macromolecular (including proteins, lipids, and nucleic acids) damage and to maintain or re-establish cellular homeostasis. Heat shock proteins (HSPs) are among the most highly conserved, ubiquitous, and abundant proteins in all organisms. Originally discovered more than 50 years ago through heat shock stress, they display multiple, remarkable roles inside and outside cells under a variety of stresses, including also oxidative stress and radiation, recognizing unfolded or misfolded proteins and facilitating their restructuring. Exercise consists in a combination of physiological stresses, such as metabolic disturbances, changes in circulating levels of hormones, increased temperature, induction of mild to severe inflammatory state, increased production of reactive oxygen and nitrogen species (ROS and RNS). As a consequence, exercise is one of the main stimuli associated with a robust increase in different HSPs in several tissues, which appears to be also fundamental in facilitating the cellular remodeling processes related to the training regime. Among all factors involved in the exercise-related modulation of HSPs level, the ROS production in the contracting muscle or in other tissues represents one of the most attracting, but still under discussion, mechanism. Following exhaustive or damaging muscle exercise, major oxidative damage to proteins and lipids is likely involved in HSP expression, together with mechanically induced damage to muscle proteins and the inflammatory response occurring several days into the recovery period. Instead, the transient and reversible oxidation of proteins by physiological concentrations of ROS seems to be involved in the activation of stress response following non-damaging muscle exercise. This review aims to provide a critical update on the role of HSPs response in exercise-induced adaptation or damage in humans, focusing on experimental

  16. Laser Induced Damage Studies in Borosilicate Glass Using nanosecond and sub nanosecond pulses

    CERN Document Server

    Rastogi, Vinay; Munda, D S

    2016-01-01

    The damage mechanism induced by laser pulse of different duration in borosilicate glass widely used for making confinement geometry targets which are important for laser driven shock multiplication and elongation of pressure pulse, is studied. We measured the front and rear surface damage threshold of borosilicate glass and their dependency on laser parameters. In this paper, we also study the thermal effects on the damage diameters, generated at the time of plasma formation. These induced damage width, geometries and microstructure changes are measured and analyzed with optical microscope, scanning electron microscope and Raman spectroscopy. The results show that at low energies symmetrical damages are found and these damage width increases nonlinearly with laser intensity. The emitted optical spectrum during the process of breakdown is also investigated and is used for the characterization of emitted plasma such as plasma temperature and free electron density. Optical emission lines from Si I at 500 nm, Si ...

  17. Investigation of laser induced breakdown in liquid nitromethane using nanosecond shadowgraphy

    Science.gov (United States)

    Guo, Wencan; Zheng, Xianxu; Yu, Guoyang; Zhao, Jun; Zeng, Yangyang; Liu, Cangli

    2016-09-01

    A nanosecond time-resolved shadowgraphy is performed to observe a laser-induced breakdown in nitromethane. The digital delays are introduced between a pump beam and an illumination light to achieve a measuring range from 40 ns to 100 ms, which enable us to study the shock wave propagation, bubble dynamics, and other process of the laser-induced breakdown. Compared with distilled water, there are two obvious differences observed in nitromethane: (1) the production of a non-evaporative gas at the final stage, and (2) an absence of the secondary shock wave after the first collapse of the bubble. We also calculated the bubble energy in nitromethane and distilled water under a different incident energy. The results indicate that the bubble energy in nitromethane is more than twice as large as that in water. It is suggested that chemical reactions contribute to the releasing of energy.

  18. Intranasal Rapamycin Rescues Mice from Staphylococcal Enterotoxin B-Induced Shock

    Science.gov (United States)

    2012-09-18

    Mice from Staphylococcal Enterotoxin B-Induced Shock Teresa Krakauer * and Marilyn Buckley Integrated Toxicology Division, U.S. Army Medical...2012 / Published: 18 September 2012 Abstract: Staphylococcal enterotoxin B (SEB) and related exotoxins produced by Staphylococcus aureus are...allowing a wider therapeutic window. Keywords: intranasal rapamycin; staphylococcal enterotoxin B; shock 1. Introduction Staphylococcal

  19. Proof-of-principle experiment of a shock-induced combustion ramjet

    NARCIS (Netherlands)

    Veraar, R.G.; Mayer, A.E.H.J.; Verreault, J.; Stowe, R.A.; Farinaccio, R.; Harris, P.G.

    2010-01-01

    By injecting and mixing the fuel upstream of the combustor and initiating the combustion of the fuel-air mixture by a shock wave in the combustor, shock-induced combustion ramjets offer the potential to drastically reduce the length and mass of scramjet propulsion systems. Based on extensive numeric

  20. Proof-of-principle experiment of a shock-induced combustion ramjet

    NARCIS (Netherlands)

    Veraar, R.G.; Mayer, A.E.H.J.; Verreault, J.; Stowe, R.A.; Farinaccio, R.; Harris, P.G.

    2009-01-01

    By injecting and mixing the fuel upstream of the combustor and initiating the combustion of the fuel-air mixture by a shock wave in the combustor, shock-induced combustion ramjets offer the potential to drastically reduce the length and mass of scramjet propulsion systems. Based on extensive numeric

  1. Proof-of-principle experiment of a shock-induced combustion ramjet

    NARCIS (Netherlands)

    Veraar, R.G.; Mayer, A.E.H.J.; Verreault, J.; Stowe, R.A.; Farinaccio, R.; Harris, P.G.

    2009-01-01

    By injecting and mixing the fuel upstream of the combustor and initiating the combustion of the fuel-air mixture by a shock wave in the combustor, shock-induced combustion ramjets offer the potential to drastically reduce the length and mass of scramjet propulsion systems. Based on extensive

  2. Proof-of-principle experiment of a shock-induced combustion ramjet

    NARCIS (Netherlands)

    Veraar, R.G.; Mayer, A.E.H.J.; Verreault, J.; Stowe, R.A.; Farinaccio, R.; Harris, P.G.

    2010-01-01

    By injecting and mixing the fuel upstream of the combustor and initiating the combustion of the fuel-air mixture by a shock wave in the combustor, shock-induced combustion ramjets offer the potential to drastically reduce the length and mass of scramjet propulsion systems. Based on extensive

  3. UV Laser-Induced DNA Photochemistry

    Science.gov (United States)

    1991-05-13

    nicking of DNA) can be described by a Poisson distribution (Armitage, 1971; Kroeber and LaForge, 1980). Such a distribution can be used to determine...specificity of the alkali-sensitive lesions induced in DNA by high intensity ultraviolet laser radiation", Photochem. Photohiol. 52:509-517 Kroeber , D.W

  4. Laser-Induced Fluorescence in Gaseous [I[subscript]2] Excited with a Green Laser Pointer

    Science.gov (United States)

    Tellinghuisen, Joel

    2007-01-01

    A green laser pointer could be used in a flashy demonstration of laser-induced fluorescence in the gas phase by directing the beam of the laser through a cell containing [I[subscript]2] at its room temperature vapor pressure. The experiment could be used to provide valuable insight into the requirements for laser-induced fluorescence (LIF) and the…

  5. Laser-induced axion photoproduction

    Science.gov (United States)

    Brodsky, S. J.; Mottola, E.; Muzinich, I. J.; Soldate, M.

    1986-01-01

    Axion photoproduction is suggested as a systematic technique for investigating the coupling of new elementary pseudoscalar or scalar particles in the megaelectronvolt mass range to leptons, photons, and hadronic matter. The experiments involve a configuration where a low-energy photon collides with a relativistic electron beam. Threshold production energies of 300 GeV can be accomplished with an optical laser, and those of 14.5-50 GeV can be achieved with wigglers directed onto an electron beam. With this scheme, at least 10 to the -7th of the electrons can be converted to axions, providing a 1-100 thousand/s relativistic beam of axions.

  6. Shock Induced Shear Strength in Two HMX Based Polymer Bonded Explosives

    Science.gov (United States)

    Millett, Jeremy; Taylor, Peter; Appleby-Thomas, Gareth

    2015-06-01

    The response of energetic materials to shock loading has largely concentrated on their detonation behaviour. However, they can also be considered to be structural materials in their own right, and hence their response to a purely mechanical shock loading is also of interest. Therefore we present results from two HMX based polymer bonded explosives, EDC37 and EDC32, where we investigate the shock induced shear strength behind the shock front. Results are discussed in terms of microstructure and differences of the binder phases.

  7. Heat-shock-induced cellular responses to temperature elevations occurring during orthopaedic cutting

    OpenAIRE

    Dolan, E. B.; Haugh, M. G.; Tallon, D.; Casey, C.; McNamara, L.M.

    2012-01-01

    Severe heat-shock to bone cells caused during orthopaedic procedures can result in thermal damage, leading to cell death and initiating bone resorption. By contrast, mild heat-shock has been proposed to induce bone regeneration. In this study, bone cells are exposed to heat-shock for short durations occurring during surgical cutting. Cellular viability, necrosis and apoptosis are investigated immediately after heat-shock and following recovery of 12, 24 h and 4 days, in osteocyte-like MLO-Y4 ...

  8. Shock-Induced Borehole Waves and Fracture Effects

    NARCIS (Netherlands)

    Fan, H.; Smeulders, D.M.

    2011-01-01

    We perform wave experiments using a vertical shock tube setup. Shock waves are generated by the rupture of a thin membrane. In the test section, the incident pressure waves generate borehole-guided waves along water-saturated samples. The tube is equipped with side wall gages and a mobile pressure p

  9. Shock-Induced Borehole Waves and Fracture Effects

    NARCIS (Netherlands)

    Fan, H.; Smeulders, D.M.

    2011-01-01

    We perform wave experiments using a vertical shock tube setup. Shock waves are generated by the rupture of a thin membrane. In the test section, the incident pressure waves generate borehole-guided waves along water-saturated samples. The tube is equipped with side wall gages and a mobile pressure p

  10. Cell detachment method using shock-wave–induced cavitation

    NARCIS (Netherlands)

    Junge, L.; Ohl, C.D.; Wolfrum, B.; Arora, M.; Ikink, R.

    2003-01-01

    The detachment of adherent HeLa cells from a substrate after the interaction with a shock wave is analyzed. Cavitation bubbles are formed in the trailing, negative pressure cycle following the shock front. We find that the regions of cell detachment are strongly correlated with spatial presence of c

  11. Observation of extremely strong shock waves in solids launched by petawatt laser heating

    Science.gov (United States)

    Lancaster, K. L.; Robinson, A. P. L.; Pasley, J.; Hakel, P.; Ma, T.; Highbarger, K.; Beg, F. N.; Chen, S. N.; Daskalova, R. L.; Freeman, R. R.; Green, J. S.; Habara, H.; Jaanimagi, P.; Key, M. H.; King, J.; Kodama, R.; Krushelnick, K.; Nakamura, H.; Nakatsutsumi, M.; MacKinnon, A. J.; MacPhee, A. G.; Stephens, R. B.; Van Woerkom, L.; Norreys, P. A.

    2017-08-01

    Understanding hydrodynamic phenomena driven by fast electron heating is important for a range of applications including fast electron collimation schemes for fast ignition and the production and study of hot, dense matter. In this work, detailed numerical simulations modelling the heating, hydrodynamic evolution, and extreme ultra-violet (XUV) emission in combination with experimental XUV images indicate shock waves of exceptional strength (200 Mbar) launched due to rapid heating of materials via a petawatt laser. We discuss in detail the production of synthetic XUV images and how they assist us in interpreting experimental XUV images captured at 256 eV using a multi-layer spherical mirror.

  12. EFFECTS OF LASER SHOCK PEENING ON SCC BEHAVIOR OF ALLOY 600

    Energy Technology Data Exchange (ETDEWEB)

    Abhishek Telang; Amrinder Gill; S.R.Mannava; Vijay K. Vasudevan; Dong Qian; Sebastien P. Teysseyre

    2013-08-01

    In this study, the effects of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of Alloy 600 in tetrathionate solution were investigated. The degree of sensitization was quantified using double loop electrochemical potentiokinetic reactivation (DLEPR) tests. The sensitized Alloy 600 was demonstrated to be susceptible to intergranular SCC in tetrathionate solution. Following LSP, residual stresses and the amount of plastic strain introduced in Alloy 600 were characterized. The effects of LSP on SCC susceptibility of Alloy 600 in tetrathionate solution were evaluated by slow strain rate tests and constant load tests. Results indicate a significant increase in resistance to crack initiation and decreased susceptibility to SCC after LSP.

  13. Laser-Generated Shocks and Bubbles as Laboratory-Scale Models of Underwater Explosions

    Directory of Open Access Journals (Sweden)

    Theodore G. Jones

    2003-01-01

    Full Text Available Underwater shocks and bubbles were generated using a high energy pulsed laser system. The advantages of this experimental approach are: (1 precisely controlled and measured experimental conditions; (2 improved diagnostics, including extensive imaging capabilities; (3 unique experiments, including a simultaneously detonated line charge; and (4 the ability to provide validation quality data for hydrodynamic simulation codes. Bubble sensitivity to variation of several experimental parameters was examined. Numerical simulations were performed corresponding to the experimental shots, showing that empirical bubble theory, experimental bubble data, and simulations were all in good agreement.

  14. Shock isolator for operating a diode laser on a closed-cycle refrigerator

    Science.gov (United States)

    Jennings, D. E. (Inventor)

    1979-01-01

    A diode laser mounted within a helium refrigerator is mounted using a braided copper ground strap which provides good impact shock isolation from the refrigerator cold-tip while also providing a good thermal link to the cold-tip. The diode mount also contains a rigid stand-off assembly consisting of alternate sections of nylon and copper which serve as cold stations to improve thermal isolation from the vaccum housing mounting structure. Included in the mount is a Pb-In alloy wafer inserted between the cold-tip and the diode to damp temperature fluctuations occurring at the cold-tip.

  15. Numerical investigation of shock induced bubble collapse in water

    Science.gov (United States)

    Apazidis, N.

    2016-04-01

    A semi-conservative, stable, interphase-capturing numerical scheme for shock propagation in heterogeneous systems is applied to the problem of shock propagation in liquid-gas systems. The scheme is based on the volume-fraction formulation of the equations of motion for liquid and gas phases with separate equations of state. The semi-conservative formulation of the governing equations ensures the absence of spurious pressure oscillations at the material interphases between liquid and gas. Interaction of a planar shock in water with a single spherical bubble as well as twin adjacent bubbles is investigated. Several stages of the interaction process are considered, including focusing of the transmitted shock within the deformed bubble, creation of a water-hammer shock as well as generation of high-speed liquid jet in the later stages of the process.

  16. Shock induced porous barrier flows, with underlying wall pressure amplification

    Science.gov (United States)

    Skews, B. W.; Bugarin, S.

    The flow field resulting from the impact of a shock wave on a variety of sheets of permeable material is studied. Earlier studies examined the flow through stationary sheets. It has, however, been found that if the sheet is placed a short distance in front of a surface, and can move under the shock loading, the pressure on the surface is amplified following shock impact, compared to the pressures that would be experienced with no covering. An important application to consider is the effect that textile clothing may have on a persons body when exposed to a blast environment. Single and multiple layers of a range of textiles have been tested. It was established that the heavier, more impermeable textiles such as Kevlar can amplify the shock wave pressure by as much as 400%. Experiments were also done with the textiles placed at an angle to the incoming shock wave and the mechanism for the amplification established through schlieren photography and pressure measurements.

  17. Effect of power density and pulse repetition on laser shock peening of Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Smith, P.R.; Shepard, M.J.; Prevey, P.S. III; Clauer, A.H.

    2000-02-01

    Laser shock peening (LSP) was applied to Ti-6Al-4V (wt.%) simulated airfoil specimens using a Nd:Glass laser. Laser shock peening processing parameters examined in the present study included power density (5.5, 7, and 9 GW/cm{sup 2}) and number of laser pulses per spot (one and three pulses/spot). The LSP's Ti-6Al-4V samples were examined using x-ray diffraction techniques to determine the residual stress distribution and percent cold work as a function of depth. It was found that the residual stress state and percent of cold work were relatively independent of LSP power density. However, the number of laser pulses per spot had a significant effect on both residual stress and percent of cold work for a given power density level. In addition, there was a strong correlation between the magnitude of residual compressive stresses generated and the percent cold work measured.

  18. Laser-induced lipolysis on adipose cells

    Science.gov (United States)

    Solarte, Efrain; Gutierrez, O.; Neira, Rodrigo; Arroyave, J.; Isaza, Carolina; Ramirez, Hugo; Rebolledo, Aldo F.; Criollo, Willian; Ortiz, C.

    2004-10-01

    Recently, a new liposuction technique, using a low-level laser (LLL) device and Ultrawet solution prior to the procedure, demonstrated the movement of fat from the inside to the outside of the adipocyte (Neira et al., 2002). To determine the mechanisms involved, we have performed Scanning and Transmission Electron Microscopy studies; Light transmittance measurements on adipocyte dilutions; and a study of laser light propagation in adipose tissue. This studies show: 1. Cellular membrane alterations. 2. LLL is capable to reach the deep adipose tissue layer, and 3. The tumescence solution enhances the light propagation by clearing the tissue. MRI studies demonstrated the appearance of fat on laser treated abdominal tissue. Besides, adipocytes were cultivated and irradiated to observe the effects on isolated cells. These last studies show: 1. 635 nm-laser alone is capable of mobilizing cholesterol from the cell membrane; this action is enhanced by the presence of adrenaline and lidocaine. 2. Intracellular fat is released from adipocytes by co joint action of adrenaline, aminophyline and 635 nm-laser. Results are consistent with a laser induced cellular process, which causes fat release from the adipocytes into the intercellular space, besides the modification of the cellular membranes.

  19. BH3-only protein BIM mediates heat shock-induced apoptosis.

    Science.gov (United States)

    Mahajan, Indra M; Chen, Miao-Der; Muro, Israel; Robertson, John D; Wright, Casey W; Bratton, Shawn B

    2014-01-01

    Acute heat shock can induce apoptosis through a canonical pathway involving the upstream activation of caspase-2, followed by BID cleavage and stimulation of the intrinsic pathway. Herein, we report that the BH3-only protein BIM, rather than BID, is essential to heat shock-induced cell death. We observed that BIM-deficient cells were highly resistant to heat shock, exhibiting short and long-term survival equivalent to Bax(-/-)Bak(-/-) cells and better than either Bid(-/-) or dominant-negative caspase-9-expressing cells. Only Bim(-/-) and Bax(-/-)Bak(-/-) cells exhibited resistance to mitochondrial outer membrane permeabilization and loss of mitochondrial inner membrane potential. Moreover, while dimerized caspase-2 failed to induce apoptosis in Bid(-/-) cells, it readily did so in Bim(-/-) cells, implying that caspase-2 kills exclusively through BID, not BIM. Finally, BIM reportedly associates with MCL-1 following heat shock, and Mcl-1(-/-) cells were indeed sensitized to heat shock-induced apoptosis. However, pharmacological inhibition of BCL-2 and BCL-X(L) with ABT-737 also sensitized cells to heat shock, most likely through liberation of BIM. Thus, BIM mediates heat shock-induced apoptosis through a BAX/BAK-dependent pathway that is antagonized by antiapoptotic BCL-2 family members.

  20. Collisionless shocks driven by 800 nm laser pulses generate high-energy carbon ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.; Shen, B. F., E-mail: bfshen@mail.shcnc.ac.cn; Wang, W. P.; Xu, Y.; Liu, Y. Q.; Liang, X. Y.; Leng, Y. X.; Li, R. X., E-mail: ruxinli@mail.shcnc.ac.cn; Xu, Z. Z. [State Key Laboratory of High Filed Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Yan, X. Q.; Chen, J. E. [State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China)

    2015-01-15

    We present experimental studies on ion acceleration from diamond-like carbon (DLC) foils irradiated by 800 nm, linearly polarized laser pulses with peak intensity of 1.7 × 10{sup 19 }W/cm{sup 2} to 3.5 × 10{sup 19 }W/cm{sup 2} at oblique incidence. Diamond-like carbon foils are heated by the prepulse of a high-contrast laser pulse and expand to form plasmas of near-critical density caused by thermal effect before the arrival of the main pulse. It is demonstrated that carbon ions are accelerated by a collisionless shock wave in slightly overdense plasma excited by forward-moving hot electrons generated by the main pulse.

  1. Experimental investigation of the shock-induced distortion of a spherical gas inhomogeneity

    Science.gov (United States)

    Ranjan, Devesh

    In a high load capability vertical shock tube, a series of experiments have been carried out to characterize the interaction of a planar shock wave with discrete gas inhomogeneities. Eleven scenarios have been considered covering the Atwood (A) and Mach (M) number ranges -0.8 soap bubble. The shock wave strength, leading to a post-shock compressible regime, allows the study of instability development in an intermediary regime between low Mach number shock tube experiments and high Mach number laser-driven experiments that has not been investigated previously. Flow visualizations are obtained using planar laser diagnostics. The imaging technique used here takes advantage of the atomization of the liquid bubble film by the incident shock wave, and up to five shocked bubble images are captured per run, enhancing the investigation of the evolution of the instability during a single experiment. Quantitative analyses of the experimental data include the vortex velocity, and subsequent circulation calculations, along with a new set of relevant geometrical length scales. As the planar shock passes over the bubble, intense vortical and nonlinear acoustic phenomena are observed, including vortex ring formation, mixing, and growth of turbulence-like features. At late-times, experimental images show the presence of secondary features in the flow field at high Mach numbers, some of which were predicted previously but, until now, not confirmed experimentally. In the case of a low Atwood number, the late time flow field is dominated by coherent vortical structures while, in the case of a high Atwood number, the shocked bubble is effectively reduced to a small core of compressed fluid, which trails behind a plume-like structure indicative of a well-developed mixing region. Dimensionless analysis of trends in the bubble length scales and other features shows that no universal timescale exists, but for each feature, a unique velocity scale is appropriate as a basis for timescaling

  2. Laser induced ponderomotive convection in water

    CERN Document Server

    Shneider, M N

    2015-01-01

    A new mechanism for inducing convection during IR laser interaction with water or any absorbing polar liquid is described theoretically. The numerical simulations performed using the developed model show that the ponderomotive force produces water flow in the direction of the laser beam propagation. In the later stage of interaction, when water temperature rises, the Archimedes force becomes first comparable and then dominant producing convection directed against the vector of gravitational acceleration (upward). The theoretical estimates and the numerical simulations predict fluid dynamics that is similar to the observed in the previous experiments.

  3. Laser induced forward transfer of soft materials

    Science.gov (United States)

    Palla-Papavlu, A.; Dinca, V.; Luculescu, C.; Shaw-Stewart, J.; Nagel, M.; Lippert, T.; Dinescu, M.

    2010-12-01

    A strong research effort is presently aimed at patterning methodologies for obtaining controlled defined micrometric polymeric structures for a wide range of applications, including electronics, optoelectronics, sensors, medicine etc. Lasers have been identified as appropriate tools for processing of different materials, such as ceramics and metals, but also for soft, easily damageable materials (biological compounds and polymers). In this work we study the dynamics of laser induced forward transfer (LIFT) with a gap between the donor and the receiver substrates, which is the basis for possible applications that require multilayer depositions with high spatial resolution.

  4. Laser induced fluorescence technique for environmental applications

    Science.gov (United States)

    Utkin, Andrei B.; Felizardo, Rui; Gameiro, Carla; Matos, Ana R.; Cartaxana, Paulo

    2014-08-01

    We discuss the development of laser induced fluorescence sensors and their application in the evaluation of water pollution and physiological status of higher plants and algae. The sensors were built on the basis of reliable and robust solid-state Nd:YAG lasers. They demonstrated good efficiency in: i) detecting and characterizing oil spills and dissolved organic matter; ii) evaluating the impact of stress on higher plants (cork oak, maritime pine, and genetically modified Arabidopsis); iii) tracking biomass changes in intertidal microphytobenthos; and iv) mapping macroalgal communities in the Tagus Estuary.

  5. Study on the dynamic behavior of matters using laser-driven shock waves in the water confinement

    Science.gov (United States)

    Yu, Hyeonju; Yoh, Jack J.

    2015-06-01

    The strain rates achievable in laser-driven shock experiments overlap with gas gun and can reach much higher values. The laser-based method also has advantages in terms of system size, cost, repeatability, and controllability. In this research, we aim to measure equation of state, Hugoniot elastic limit, strain rate, and compressive yield strength of target samples by making use of the velocity interferometer or the VISAR. High pressure shock wave is generated by a Q-switched Nd:YAG laser operating at 1.064 μm wavelength with pulse energy up to 3 joules and 9 ns pulse duration. All the experiments are conducted in the water confinement to increase the peak stresses to an order of GPa. Furthermore, quantitative comparisons are made to the existing shock data in order to emphasize the novelty of the proposed setup which is relatively simple and reliable. Corresponding author.

  6. Generation and Evolution of High-Mach-Number Laser-Driven Magnetized Collisionless Shocks in the Laboratory

    Science.gov (United States)

    Schaeffer, D. B.; Fox, W.; Haberberger, D.; Fiksel, G.; Bhattacharjee, A.; Barnak, D. H.; Hu, S. X.; Germaschewski, K.

    2017-07-01

    We present the first laboratory generation of high-Mach-number magnetized collisionless shocks created through the interaction of an expanding laser-driven plasma with a magnetized ambient plasma. Time-resolved, two-dimensional imaging of plasma density and magnetic fields shows the formation and evolution of a supercritical shock propagating at magnetosonic Mach number Mms≈12 . Particle-in-cell simulations constrained by experimental data further detail the shock formation and separate dynamics of the multi-ion-species ambient plasma. The results show that the shocks form on time scales as fast as one gyroperiod, aided by the efficient coupling of energy, and the generation of a magnetic barrier between the piston and ambient ions. The development of this experimental platform complements present remote sensing and spacecraft observations, and opens the way for controlled laboratory investigations of high-Mach number collisionless shocks, including the mechanisms and efficiency of particle acceleration.

  7. Generation and Evolution of High-Mach Number, Laser-Driven Magnetized Collisionless Shocks in the Laboratory

    CERN Document Server

    Schaeffer, Derek; Haberberger, Dan; Fiksel, Gennady; Bhattacharjee, Amitava; Barnak, Daniel; Hu, Suxing; Germaschewski, Kai

    2016-01-01

    Shocks act to convert incoming supersonic flows to heat, and in collisionless plasmas the shock layer forms on kinetic plasma scales through collective electromagnetic effects. These collisionless shocks have been observed in many space and astrophysical systems [Smith 1975, Smith 1980, Burlaga 2008, Sulaiman 2015], and are believed to accelerate particles, including cosmic rays, to extremely high energies [Kazanas 1986, Loeb 2000, Bamba 2003, Masters 2013, Ackermann 2013]. Of particular importance are the class of high-Mach number, supercritical shocks [Balogh 2013] ($M_A\\gtrsim4$), which must reflect significant numbers of particles back into the upstream to accommodate entropy production, and in doing so seed proposed particle acceleration mechanisms [Blandford 1978, McClements 2001, Caprioli 2014, Matsumoto 2015]. Here we present the first laboratory generation of high-Mach number magnetized collisionless shocks created through the interaction of an expanding laser-driven plasma with a magnetized ambient ...

  8. Prevention of Trauma/Hemorrhagic Shock-Induced Mortality, Apoptosis, Inflammation and Mitochondrial Dysfunction

    Science.gov (United States)

    2015-02-01

    Award Number: W81XWH-11-2-0018 TITLE:“Prevention of Trauma/Hemorrhagic Shock-Induced Mortality, Apoptosis, Inflammation and Mitochondrial ...3. DATES COVERED (From - To) 05 Nov 2010 – 04 Nov 2014 4. TITLE AND SUBTITLE Inflammation and Mitochondrial Dysfunction” 5a. CONTRACT NUMBER...W81XWH-11-2-0018 “Prevention of Trauma/Hemor hagic Shock-Induced Mortality, Apoptosis,Inflammation and Mitochondrial Dysfunction” 5b. GRANT NUMBER

  9. Large-Eddy/Reynolds-Averaged Navier-Stokes Simulation of Shock-Train Development in a Coil-Laser Diffuser

    Science.gov (United States)

    2014-09-06

    AFRL-RD-PS- AFRL-RD-PS- TR-2014-0029 TR-2014-0029 LARGE - EDDY /REYNOLDS-AVERAGED NAVIER- STOKES SIMULATION OF SHOCK-TRAIN DEVELOPMENT IN A COIL...CONTRACT NUMBER FA9451-13-1-0262 Large - Eddy /Reynolds-Averaged Navier-Stokes Simulation of Shock-Train 5b. GRANT NUMBER Development in a COIL –Laser...NOTES 14. ABSTRACT This report describes the application of a hybrid large - eddy simulation / Reynolds-averaged Navier-Stokes method to predict shock

  10. Microscopic Effects of Shock Metamorphism in Crystalline Rocks Correlated With Shock Induced Changes in Density, Haughton Impact Structure

    Science.gov (United States)

    Singleton, A. C.; Osinski, G.; Moser, D.

    2009-05-01

    Asteroid and comet impacts are an important geological process on all solid planetary bodies, including Earth, and involve pressures and temperatures that may reach several hundred GPa and several thousand K [1] over very limited spatial and temporal scales. This results in shock metamorphism and alters the target material on both megascopic and microscopic scales [2]. Many shock metamorphic features are unique to hypervelocity impact environments and are, therefore, diagnostic of such an event [1,2]. Of particular interest for this study is the effect of hypervelocity impact on the density of the target material. In the case of crystalline target rocks, shock metamorphism results in an increase of pore space and impact induced fractures which act to decrease the density. The Haughton impact structure is a well-preserved late Eocene (39 ± 2 Ma) complex impact structure, situated near the western end of Devon Island (75°22'N, 89°41'W) [3]. The geology of the area consists of a sedimentary sequence unconformably overlying crystalline Precambrian gneisses of the Canadian Shield. Since the impact, Devon Island has remained tectonically stable and Haughton remains well-preserved despite being subjected to several glaciations. The excellent preservation of the structure is largely due to the primarily cold and relatively dry environment that has existed in the Arctic since the Eocene [3]. Samples of crystalline material were collected from 36 sites within the impact breccia unit of the Haughton impact structure. These samples display a wide range of density and physical appearance. The type of shock effect(s) created depends upon the pressures and temperatures involved as well as the composition, density and material's location in the target. The samples found in the Haughton impact structure show a wide range of shock effects and thus were exposed to a variety of different conditions likely due to their in-situ positions relative to the impact. Polished thin sections

  11. A physics informed emulator for laser-driven radiating shock simulations

    KAUST Repository

    McClarren, Ryan G.

    2011-09-01

    This work discusses the uncertainty quantification aspect of quantification of margin and uncertainty (QMU) in the context of two linked computer codes. Specifically, we present a physics based reduction technique to deal with functional data from the first code and then develop an emulator for this reduced data. Our particular application deals with conditions created by laser deposition in a radiating shock experiment modeled using the Lagrangian, radiation-hydrodynamics code Hyades. Our goal is to construct an emulator and perform a sensitivity analysis of the functional output from Hyades to be used as an initial condition for a three-dimensional code that will compute the evolution of the radiating shock at later times. Initial attempts at purely statistical data reduction techniques, were not successful at reducing the number of parameters required to describe the Hyades output. We decided on an alternate approach using physical arguments to decide what features/locations of the output were relevant (e.g., the location of the shock front or the location of the maximum pressure) and then used a piecewise linear fit between these locations. This reduced the number of outputs needed from the emulator to 40, down from the O(1000) points in the Hyades output. Then, using Bayesian MARS and Gaussian process regression, we were able to build emulators for Hyades and study sensitivities to input parameters. © 2011 Elsevier Ltd. All rights reserved.

  12. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    Energy Technology Data Exchange (ETDEWEB)

    Rességuier, T. de, E-mail: resseguier@ensma.fr [Institut PPRIME, UPR 3346, CNRS, ENSMA, Université de Poitiers, 1 ave. Clément Ader, 86961 Futuroscope Cedex (France); Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P. [CEA, DAM, DIF, 91297 Arpajon (France)

    2014-01-28

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates.

  13. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    Science.gov (United States)

    de Rességuier, T.; Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P.

    2014-01-01

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates.

  14. Sensitive Mid-IR Laser Sensor Development and Mass Spectrometric Measurements in Shock Tube and Flames

    KAUST Repository

    Alquaity, Awad

    2016-11-01

    With global emission regulations becoming stringent, development of new combustion technologies that meet future emission regulations is essential. In this vein, this dissertation presents the application of sensitive diagnostic tools to validate and improve chemical kinetic mechanisms that play a fundamental role in the design of new combustion technologies. First, a novel high sensitivity laser-based sensor with a wide frequency tuning range (900 – 1000 cm-1) was developed utilizing pulsed cavity ringdown spectroscopy (CRDS) technique. The novel laser-based sensor was illustrated by measuring trace amounts of multiple combustion intermediates, namely ethylene, propene, allene, and 1-butene in a static cell at ambient conditions. Subsequently, pulsed CRDS technique was utilized to develop an ultra-fast, high sensitivity diagnostic to monitor trace concentrations of ethylene in shock tube pyrolysis experiments. This diagnostic represented the first ever successful application of CRDS technique to transient species measurements in a shock tube. The high sensitivity and fast time response (10μs) diagnostic may be utilized for measuring other key neutrals and radicals which are crucial in the oxidation chemistry of practical fuels. Secondly, a quadrupole mass spectrometer (QMS) was employed to measure relative cation mole fractions in atmospheric and low-pressure (30 Torr) flames of methane/oxygen diluted in argon. Lean, stoichiometric and rich flames were 4 examined to evaluate the dependence of ion chemistry on flame stoichiometry. Spatial distribution of cations was compared with predictions of an existing ion chemistry model. Based on the extensive measurements carried out in this work, modifications were suggested to improve the ion chemistry model to enhance the fidelity of such mechanisms. In-depth understanding of flame ion chemistry is vital to model the interaction of flames with electric fields and thereby pave the way to enable active combustion control

  15. Identification of Laser-induced Lamb waves

    Energy Technology Data Exchange (ETDEWEB)

    Castro C, M.; Lopez, J.A. [Physics Department, U. 1: El Paso, El Paso, TX 79968 (United States); Osegueda, R. [FAST Center, Burgess Hall, U. 1: El Paso, El Paso, TX 79968 (United States)

    2007-07-01

    We studied experimentally the ultrasonic propagating modes produced by a laser pulse of 532 nm while impinging on an aluminum plate. The beam, shaped as a line, induced various Lamb modes whose relative power varied with the laser line length. Identification of their mode was performed by detecting the ultrasonic modes with piezoelectric detectors along a propagation direction orthogonal to the line, and using two dimensional fast Fourier transform. Good agreement is observed between theoretical and experimental dispersion curves for the first fundamental symmetric and anti-symmetric modes. Results are shown for 12 and 24 mm laser line-length at 13.6 and 16.8 ns pulse-width. (Author)

  16. High level compressive residual stresses produced in aluminum alloys by laser shock processing

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Rosas, G. [Centro de Ingenieria y Desarrollo Industrial, CIDESI, Av. Playa Pie de la Cuesta, 702 Desarrollo San Pablo, c.p. 76130 Santiago de Queretaro, Queretaro (Mexico)]. E-mail: ggomez@cidesi.mx; Rubio-Gonzalez, C. [Centro de Ingenieria y Desarrollo Industrial, CIDESI, Av. Playa Pie de la Cuesta, 702 Desarrollo San Pablo, c.p. 76130 Santiago de Queretaro, Queretaro (Mexico); Ocana, J.L [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain); Molpeceres, C. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain); Porro, J.A. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain); Chi-Moreno, W. [Instituto Tecnologico de Morelia (Mexico); Morales, M. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain)

    2005-11-15

    Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results for metal surface treatments in underwater laser irradiation at 1064 nm. A convergent lens is used to deliver 1.2 J/cm{sup 2} in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG, two laser spot diameters were used: 0.8 and 1.5 mm. Results using pulse densities of 2500 pulses/cm{sup 2} in 6061-T6 aluminum samples and 5000 pulses/cm{sup 2} in 2024 aluminum samples are presented. High level of compressive residual stresses are produced -1600 MPa for 6061-T6 Al alloy, and -1400 MPa for 2024 Al alloy. It has been shown that surface residual stress level is higher than that achieved by conventional shot peening and with greater depths. This method can be applied to surface treatment of final metal products.

  17. Laser Shock Processing of 6061-T6 Al alloy with 1064 nm and 532 nm wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Rosas, G., E-mail: gomezrg@hotmail.com [Departamento de Fisica, Centro Universitario de Ciencias Exactas e Ingenierias, CUCEI, Universidad de Guadalajara, Blvd. Marcelino Garcia Barragan 1421, Guadalajara, Jalisco 44430 (Mexico); Rubio-Gonzalez, C. [Centro de Ingenieria y Desarrollo Industrial, Pie de la cuesta No. 702, Desarrollo San Pablo, Queretaro, Qro. 76130 (Mexico); Ocana, J.L.; Molpeceres, C.; Porro, J.A.; Morales, M. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII. Universidad Politecnica de Madrid (Spain); Casillas, F.J. [Departamento de Ciencias Exactas y Tecnologicas, Universidad de Guadalajara, Lagos de Moreno, Jalisco 47460 (Mexico)

    2010-08-01

    Laser Shock Processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 532 nm and 1064 nm. The purpose of the work is to compare the effect of both wavelengths on the same material. A convergent lens is used to deliver 1.2 J/pulse (1064 nm) and 0.9 J/pulse (532 nm) in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG laser with spots of a 1.5 mm in diameter moving forward along the work piece. A LSP configuration with experimental results using a pulse density of 2500 pulses/cm{sup 2} and 5000 pulses/cm{sup 2} in 6061-T6 aluminum samples are presented. High level compressive residual stresses are produced using both wavelengths. It has been shown that surface residual stress level is comparable to that achieved by conventional shot peening, but with greater depths. This method can be applied to surface treatment of final metal products.

  18. Investigations into mild electric foot shock stress-induced cognitive enhancement: possible role of angiotensin neuropeptides.

    Science.gov (United States)

    Bali, Anjana; Singh, Nirmal; Jaggi, Amteshwar Singh

    2013-09-01

    This study was designed to investigate the role of angiotensin neuropeptides in mild electric foot shock stress-induced cognitive enhancement in mice. Mild stress was induced by applying mild electric foot shocks of 0.15 mA intensity for 0.5 s. The stress-induced alteration in cognition was assessed using a Morris water maze test. The animals were subjected to mild electric foot shocks 5 min before we recorded escape latency time (ELT), an index of learning, during the first 4 days of a 5-day trial in the Morris water maze. The time spent in target quadrant (TSTQ), an index of retrieval, was noted on the fifth day without prior administration of electric foot shock. The angiotensin-converting enzyme inhibitor lisinopril (5, 10 and 20 mg/kg), and telmisartan (1, 2 and 5 mg/kg), an angiotensin II receptor blocker, were employed to assess the role of angiotensin neuropeptides. The application of mild electric shocks significantly decreased ELT and increased TSTQ, indicating enhancement in stress-induced learning and memory. However, administration of lisinopril and telmisartan significantly attenuated the stress-induced decrease in ELT and increase in TSTQ. It may be concluded that mild electric foot shock-induced stress triggers the release of angiotensin neuropeptides that may be responsible for memory enhancement.

  19. K-Shell absorpsion spectroscopy of direct drive, shock compressed aluminum targets at the Omega laser facility

    Science.gov (United States)

    Shepherd, Ronnie; Boehley, Thomas; Bradley, David; Ng, Andrew; Iglesias, Carlos; Moon, Steve; Food, Mark; Collins, Gilbert; Rogers, Forrest; Heeter, Robert; Springer, Paul

    2003-10-01

    We have performed experiments to study plasma effects on bound states. The experiments were performed at the Laboratory for Laser Energetics Omega laser facility. The targets consisted of 25 μ m Be, 15 μ m Si, and 10 μ m of Al with an additional 15 μ m step. The targets were shock compressed using direct drive to form dense, strongly coupled plasmas. The plasma conditions were inferred from equation of state models in conjunction with shock breakout time measurements from VISAR. Time resolved absorption spectroscopy was also performed to study the degree of ionization. Data and simulations will be presented.

  20. Dispersive radiation induced by shock waves in passive resonators.

    Science.gov (United States)

    Malaguti, Stefania; Conforti, Matteo; Trillo, Stefano

    2014-10-01

    We show that passive Kerr resonators pumped close to zero dispersion wavelengths on the normal dispersion side can develop the resonant generation of linear waves driven by cavity (mixed dispersive-dissipative) shock waves. The resonance mechanism can be successfully described in the framework of the generalized Lugiato-Lefever equation with higher-order dispersive terms. Substantial differences with radiation from cavity solitons and purely dispersive shock waves dispersion are highlighted.

  1. Ultrafast Measurement of the Optical Properties of Shocked Nickel and Laser Heated Gold

    Science.gov (United States)

    Funk, David J.; Moore, D. S.; Reho, J. H.; Gahagan, K. T.; McGrane, S. D.; Rabie, R. L.

    2002-07-01

    We have used high-resolution Frequency Domain Interferometry (FDI) to make the first ultrafast measurement of shock-induced changes in the optical properties of thin nickel (approx500 nm) targets. Data taken at several angles of incidence allowed the separation of optical effects from material motion, yielding an effective complex index for the shocked material. In contrast to our previous studies of aluminum, measurements with an 800 nm probe wavelength found a phase shift attributable to optical property changes with the same sign as that due to surface motion, during an 11.5 GPa shock breakout. A similar experiment was attempted with thin gold films (approx180 nm) using Ultrafast Spatial Interferometry (USI). However, since the electron-phonon coupling in gold is extremely weak, a shock is observed as it "forms". Ballistic electrons and electron-electron equilibrium cause fast heating of the electrons in the entire thickness of the thin film, followed by lattice excitation through electron-phonon coupling, eventually leading to melt and frustrated thermal expansion yielding the observed surface motion. We suggest that these experiments offer a new path for observation of phase changes or for temperature measurements, by allowing a determination of the complex index under dynamic loading conditions and comparing the measured values to those obtained under static conditions.

  2. Electron acceleration in collisionless shocks and magnetic reconnection by laser-produced plasma ablation

    Science.gov (United States)

    Park, Jaehong; Spitkovksy, Anatoly; Fox, Will; Bhattacharjee, Amitava

    2016-10-01

    We perform particle-in-cell simulations of collisionless shocks and magnetic reconnection generated by ablated plasma expanding into a magnetized background plasma. We find: (1) The simulated proton radiography produces different morphology of the shock structure depending on the orientation of the magnetic field and can be used to identify a shock in the experiment. Electrons are accelerated by the whistler waves generated at oblique sites of the shock. (2) Forced collisionless magnetic reconnection is induced when the expanding plumes carry opposite magnetic polarities and interact with a background plasma. Electrons are accelerated at the reconnection X line and reveal a power-law distribution as the plasma beta is lowered, β = 0.08 . As the plasma beta is increased, β = 0.32 , the 1st order Fermi mechanism against the two plasma plumes contributes to the electron acceleration as well as the X line acceleration. Using 3-D simulations, we also explore the effect of 3-D instabilities (Weibel instability or drift-kink) on particle acceleration and magnetic field annihilation between the colliding magnetized plumes

  3. Thermochemical model for shock-induced chemical reactions in porous thermite: The heat detonation model

    Energy Technology Data Exchange (ETDEWEB)

    Boslough, M.B.

    1989-01-01

    A thermochemical model has been developed that treats a shock-induced solid state chemical reaction as a special type of detonation, called a ''heat detonation'' to distinguish it from an ordinary explosive detonation and describe the final form that the chemical energy takes. According to shock temperature measurements, chemical energy can be released from porous reactive solids on a time scale shorter than shock-transit times in laboratory samples. By comparing the experimental shock temperature for porous thermite to that calculated by the model, the amount of thermite reacted when shocked to about 4 GPa was estimated to be between 60 and 70%. Calculated shock temperatures are extremely strong functions of the extent of reaction, but are relatively insensitive to the initial porosity and amount of volatile impurities. Thus, shock temperature measurements are the most useful for real-time studies of shock-induced exothermic chemical reactions in solids. 11 refs., 5 figs., 1 tab.

  4. Electric shock-induced associative olfactory learning in Drosophila larvae.

    Science.gov (United States)

    Pauls, Dennis; Pfitzenmaier, Johanna E R; Krebs-Wheaton, Rebecca; Selcho, Mareike; Stocker, Reinhard F; Thum, Andreas S

    2010-05-01

    Associative plasticity is a basic essential attribute of nervous systems. As shown by numerous reports, Drosophila is able to establish simple forms of appetitive and aversive olfactory associations at both larval and adult stages. Whereas most adult studies on aversive learning employed electric shock as a negative reinforcer, larval paradigms essentially utilized gustatory stimuli to create negative associations, a discrepancy that limits the comparison of data. To overcome this drawback, we critically revisited larval odor-electric shock conditioning. First, we show that lithium chloride (LiCl), which was used in all previous larval electric shock paradigms, is not required per se in larval odor-electric shock learning. This is of considerable practical advantage because beside its peculiar effects LiCl is attractive to larvae at low concentration that renders comparative learning studies on genetically manipulated larvae complicated. Second, we confirm that in both a 2-odor reciprocal and a 1-odor nonreciprocal conditioning regimen, larvae are able to associate an odor with electric shock. In the latter experiments, initial learning scores reach an asymptote after 5 training trials, and aversive memory is still detectable after 60 min. Our experiments provide a comprehensive basis for future comparisons of larval olfactory conditioning reinforced by different modalities, for studies aimed at analyzing odor-electric shock learning in the larva and the adult, and for investigations of the cellular and molecular substrate of aversive olfactory learning in the simple Drosophila model.

  5. DNA deposition through laser induced forward transfer.

    Science.gov (United States)

    Colina, M; Serra, P; Fernández-Pradas, J M; Sevilla, L; Morenza, J L

    2005-02-15

    Laser induced forward transfer (LIFT) is a laser direct write technique that appears to be specially adequate for the production of biosensors, since it permits to deposit patterns of biomolecules with high spatial resolution. In the LIFT technique, a laser pulse is focused on a thin film of the material to be transferred through a transparent support, and under the action of the laser pulse, a small fraction of the film is transferred to a receptor substrate that is placed parallel to the film-support system. In the case of biomolecules transfer, the thin film consists in a liquid solution containing the biomolecules. In this work, microarrays of two different cDNAs have been both spotted by LIFT and pin microspotting onto a poly-L-lysine treated glass slide. Once transferred, all the microarrays have been submitted to hybridization with the complementary strands of the spotted cDNAs, each one tagged with a different fluorochrome. Comparative fluorescence scanner analyses have revealed that the microarrays transferred through LIFT are equivalent to those transferred through pin microspotting in terms of signal intensity and gene discrimination capacity, and that the action of the laser pulse does not result in significant damage of the transferred DNA.

  6. High speed optical and X-ray methods for evaluating laser-generated shock-wave in materials

    Energy Technology Data Exchange (ETDEWEB)

    Paisley, D.; Swift, D. [and others

    2000-11-01

    Optical diagnostic techniques including interferometry, electronic streak photography, and transient x-ray diffraction are used to study the dynamic material response to shock loading by direct laser irradiation and impact by laser-launched plates. The Los Alamos Trident laser is one of several lasers that have been used to generate shocks of 10 Kbar to several Mbar in single crystal and polycrystalline materials. Incorporating optical velocity interferometry (line-VISAR and point-VISAR) with transient x-ray diffraction can provide a complete understanding of the dynamic material response to shock compression and release. Laser-launched flyer plates provide an ideal method to generate one-dimensional shocks in materials. The quality of the one-dimensionality of the launch and acceleration of plates is evaluated by line-imaging VISA.R. The line-imaging VISAR images the fringes along a line across the diameter of the plate. Each fringe maxima and minima provide acceleration and velocity information at the specific point on the plate. By varying the fringe constant number of fringes and fringe spacing on the plate, detailed experimental data can be obtained. For our experiments, most plates are 3-mm diameter and accelerated to 0.2-->6 km/sec.

  7. Laser-induced incandescence from laser-heated silicon nanoparticles

    Science.gov (United States)

    Menser, Jan; Daun, Kyle; Dreier, Thomas; Schulz, Christof

    2016-11-01

    This work describes the application of temporally and spectrally resolved laser-induced incandescence to silicon nanoparticles synthesized in a microwave plasma reactor. Optical properties for bulk silicon presented in the literature were extended for nanostructured particles analyzed in this paper. Uncertainties of parameters in the evaporation submodel, as well as measurement noise, are incorporated into the inference process by Bayesian statistics. The inferred nanoparticle sizes agree with results from transmission electron microscopy, and the determined accommodation coefficient matches the values of the preceding study.

  8. Laser-Induced Breakdown Spectroscopy in Africa

    Directory of Open Access Journals (Sweden)

    M. A. Kasem

    2015-01-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS, known also as laser-induced plasma spectroscopy (LIPS, is a well-known spectrochemical elemental analysis technique. The field of LIBS has been rapidly matured as a consequence of growing interest in real-time analysis across a broad spectrum of applied sciences and recent development of commercial LIBS analytical systems. In this brief review, we introduce the contributions of the research groups in the African continent in the field of the fundamentals and applications of LIBS. As it will be shown, the fast development of LIBS in Africa during the last decade was mainly due to the broad environmental, industrial, archaeological, and biomedical applications of this technique.

  9. Laser induced breakdown spectroscopy on meteorites

    Energy Technology Data Exchange (ETDEWEB)

    De Giacomo, A. [Department of Chemistry, University of Bari (Italy); MIP-CNR sec Bari (Italy)], E-mail: alessandro.degiacomo@ba.imip.cnr.it; Dell' Aglio, M.; De Pascale, O. [MIP-CNR sec Bari (Italy); Longo, S.; Capitelli, M. [Department of Chemistry, University of Bari (Italy); MIP-CNR sec Bari (Italy)

    2007-12-15

    The classification of meteorites when geological analysis is unfeasible is generally made by the spectral line emission ratio of some characteristic elements. Indeed when a meteorite impacts Earth's atmosphere, hot plasma is generated, as a consequence of the braking effect of air, with the consequent ablation of the falling body. Usually, by the plasma emission spectrum, the meteorite composition is determined, assuming the Boltzmann equilibrium. The plasma generated during Laser Induced Breakdown Spectroscopy (LIBS) experiment shows similar characteristics and allows one to verify the mentioned method with higher accuracy. On the other hand the study of Laser Induced Breakdown Spectroscopy on meteorite can be useful for both improving meteorite classification methods and developing on-flight techniques for asteroid investigation. In this paper certified meteorites belonging to different typologies have been investigated by LIBS: Dofhar 461 (lunar meteorite), Chondrite L6 (stony meteorite), Dofhar 019 (Mars meteorite) and Sikhote Alin (irony meteorite)

  10. Shock induced chemistry in liquids studied with ultrafast dynamic ellipsometry and visible transient absorption spectroscopy.

    Science.gov (United States)

    Dang, N C; Bolme, C A; Moore, D S; McGrane, S D

    2012-10-25

    The response to ultrafast laser shock loading of nine liquids was monitored in an effort to reveal evidence of chemical changes occurring during the first 350 ps following the shock front. In an effort to compare molecular structures possessing a variety of common bonding patterns, data were acquired for the liquids: cyclohexane, cyclohexene, 1,3-cyclohexadiene, benzene, water, acetonitrile, acrylonitrile, tert-butylacetylene, and phenylacetylene. Transient absorption spectra were measured in the spectral region from 440 to 780 nm over shock stress states from 7 to 20 GPa. Ultrafast dynamic ellipsometry was used to measure the shock and particle velocity as well as the shocked refractive index. Significant transient absorption attributed to chemical reaction was observed for shocked phenylacetylene and acrylonitrile. Evidence of volume decreasing chemical reactions was also observed in the ultrafast dynamic ellipsometry data for phenylacetylene and acrylonitrile. The liquid 1,3-cyclohexadiene exhibited volume decreasing reaction in the ultrafast dynamic ellipsometry data but did not exhibit an increase in the transient absorption spectra. There was no evidence of chemical reaction in cyclohexane, cyclohexene, benzene, water, acetonitrile, or tert-butylacetylene in the first 350 ps, despite the application of shock stress that was in many cases well above the reaction threshold observed at microsecond time scales.

  11. Laser-Induced Breakdown in Liquid Helium

    Science.gov (United States)

    Sirisky, S.; Yang, Y.; Wei, W.; Maris, H. J.

    2017-10-01

    We report on experiments in which focused laser light is used to induce optical breakdown in liquid helium-4. The threshold intensity has been measured over the temperature range from 1.1 to 2.8 K with light of wavelength 1064 nm. In addition to the measurement of the threshold, we have performed experiments to study how the breakdown from one pulse modifies the probability that a subsequent pulse will result in breakdown.

  12. Laser induced nuclear waste transmutation

    CERN Document Server

    Hirlimann, Charles

    2016-01-01

    When producing electricity that collects the mass energy that is available at the time of the induced disintegration of radioactive elements, other unstable elements are produced with half-life span durations ranging from less than one second to hundreds of thousands of years and which are considered as waste. Managing nuclear waste with a half-life of less than 30 years is an easy task, as our societies clearly know how to keep buildings safe for more than a century, the time it takes for the activity to be divided by a factor of 8. High-activity, long-lasting waste that can last for thousands of years or even longer, up to geological time laps, cannot be taken care of for such long durations. Therefore, these types of waste are socially unacceptable; nobody wants to leave a polluted planet to descendants.

  13. Heat-shock-induced cellular responses to temperature elevations occurring during orthopaedic cutting.

    Science.gov (United States)

    Dolan, E B; Haugh, M G; Tallon, D; Casey, C; McNamara, L M

    2012-12-07

    Severe heat-shock to bone cells caused during orthopaedic procedures can result in thermal damage, leading to cell death and initiating bone resorption. By contrast, mild heat-shock has been proposed to induce bone regeneration. In this study, bone cells are exposed to heat-shock for short durations occurring during surgical cutting. Cellular viability, necrosis and apoptosis are investigated immediately after heat-shock and following recovery of 12, 24 h and 4 days, in osteocyte-like MLO-Y4 and osteoblast-like MC3T3-E1 cells, using flow cytometry. The regeneration capacity of heat-shocked Balb/c mesenchymal stem cells (MSCs) and MC3T3-E1s has been investigated following 7 and 14 day's recovery, by quantifying proliferation, differentiation and mineralization. An immediate necrotic response to heat-shock was shown in cells exposed to elevated temperatures (45°C, 47°C and most severe at 60°C). A longer-term apoptotic response is induced in MLO-Y4s and, to a lesser extent, in MC3T3-E1s. Heat-shock-induced differentiation and mineralization by MSCs. These findings indicate that heat-shock is more likely to induce apoptosis in osteocytes than osteoblasts, which might reflect their role as sensors detecting and communicating damage within bone. Furthermore, it is shown for the first time that mild heat-shock (less than equal to 47°C) for durations occurring during surgical cutting can positively enhance osseointegration by osteoprogenitors.

  14. Laser-induced torques in metallic ferromagnets

    Science.gov (United States)

    Freimuth, Frank; Blügel, Stefan; Mokrousov, Yuriy

    2016-10-01

    We study laser-induced torques in bcc Fe, hcp Co, and L 10 FePt based on first-principles electronic structure calculations and the Keldysh nonequilibrium formalism. We find that the torques have two contributions, one from the inverse Faraday effect (IFE) and one from the optical spin-transfer torque (OSTT). Depending on the ferromagnet at hand and on the quasiparticle broadening the two contributions may be of similar magnitude, or one contribution may dominate over the other. Additionally, we determine the nonequilibrium spin polarization in order to investigate its relation to the torque. We find the torques and the perpendicular component of the nonequilibrium spin polarization to be odd in the helicity of the laser light, while the spin polarization that is induced parallel to the magnetization is helicity independent. The parallel component of the nonequilibrium spin polarization is orders of magnitude larger than the perpendicular component. In the case of hcp Co we find good agreement between the calculated laser-induced torque and a recent experiment.

  15. Laser-Driven Ultra-Relativistic Plasmas - Nuclear Fusion in Coulomb Shock Waves, Rouge Waves, and Background Matter

    Science.gov (United States)

    2015-05-05

    AND SUBTITLE LASER-DRIVEN ULTRA-RELATIVISTIC PLASMAS - NUCLEAR FUSION IN COULOMB SHOCK WAVES, ROUGE WAVES, AND BACKGROUND MATTER. 5a.  CONTRACT...blackbody radiation on free electrons .........................9 2.vi. Proposal of ultimate test of laser nuclear fusion efficiency in clusters...domain of energies and temperatures, with applications in particular to controlled nuclear fusion . 2. Final technical report on the grant #F49620-11-1

  16. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    Science.gov (United States)

    Wei, Wenfu; Li, Xingwen; Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici

    2014-08-01

    This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000 ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ˜600 ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

  17. Shock-induced effects in calcite from Cactus Crater

    Science.gov (United States)

    Vizgirda, J.; Ahrens, T. J.; Tsay, F.-D.

    1980-01-01

    The paper discusses shock metamorphism of calcite from coralline limestone samples retrieved from a borehole drilled into rocks beneath Cactus Crater, a nuclear explosion crater at Eniwetok Atoll. The metamorphism was detected and quantified using electron spin resonance (ESR); the ESR spectra of Mn(+) present as a trace constituent in the coral samples, show a consistent decrease in hyperfine peak splitting with decreasing depth of sample. It is suggested that the decrease in hyperfine peak splitting reflects a decrease in crystal field splitting, and therefore, small increases on cation-anion distances produced by mechanical energy input during the shock process. Two alternative crater models suggested by the ESR results are a depiction of a steady decay of the shock wave, and a delineation of a breccia lens with a breccia-bedrock interface at 20 plus or minus 5 m.

  18. Turbulence-induced magnetic fields in shock precursors

    CERN Document Server

    del Valle, Maria Victoria; Santos-Lima, Reinaldo

    2016-01-01

    Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. $10^{15}$ eV. A stronger magnetic field in the pre-shock region could provide the efficiency required. Bell's cosmic-ray nonresonant streaming instability has been claimed to be responsible for the amplification of precursor magnetic fields. However, an alternative mechanism has been proposed in which the cosmic-ray pressure gradient forms the shock precursor and drives turbulence, amplifying the magnetic field via the small-scale dynamo. A key ingredient for the mechanism to operate are the inhomogeneities present in the interstellar medium (ISM). These inhomogeneities are the consequence of turbulence. In this work we explore the magnetic field amplification in different ISM conditions through 3D MHD numerical simulations.

  19. An Experimental Study on Micro Clinching of Metal Foils with Cutting by Laser Shock Forming

    Directory of Open Access Journals (Sweden)

    Xiao Wang

    2016-07-01

    Full Text Available This paper describes a novel technique for joining similar and dissimilar metal foils, namely micro clinching with cutting by laser shock forming. A series of experiments were conducted to study the deformation behavior of single layer material, during which many important process parameters were determined. The process window of the 1060 pure aluminum foils and annealed copper foils produced by micro clinching with cutting was analyzed. Moreover, similar material combination (annealed copper foils and dissimilar material combination (1060 pure aluminum foils and 304 stainless steel foils were successfully achieved. The effect of laser energy on the interlock and minimum thickness of upper foils was investigated. In addition, the mechanical strength of different material combinations joined by micro clinching with cutting was measured in single lap shearing tests. According to the achieved results, this novel technique is more suitable for material combinations where the upper foil is thicker than lower foil. With the increase of laser energy, the interlock increased while the minimum thickness of upper foil decreased gradually. The shear strength of 1060 pure aluminum foils and 304 stainless steel foils combination was three times as large as that of 1060 pure aluminum foils and annealed copper foils combination.

  20. An Experimental Study on Micro Clinching of Metal Foils with Cutting by Laser Shock Forming.

    Science.gov (United States)

    Wang, Xiao; Li, Cong; Ma, Youjuan; Shen, Zongbao; Sun, Xianqing; Sha, Chaofei; Gao, Shuai; Li, Liyin; Liu, Huixia

    2016-07-13

    This paper describes a novel technique for joining similar and dissimilar metal foils, namely micro clinching with cutting by laser shock forming. A series of experiments were conducted to study the deformation behavior of single layer material, during which many important process parameters were determined. The process window of the 1060 pure aluminum foils and annealed copper foils produced by micro clinching with cutting was analyzed. Moreover, similar material combination (annealed copper foils) and dissimilar material combination (1060 pure aluminum foils and 304 stainless steel foils) were successfully achieved. The effect of laser energy on the interlock and minimum thickness of upper foils was investigated. In addition, the mechanical strength of different material combinations joined by micro clinching with cutting was measured in single lap shearing tests. According to the achieved results, this novel technique is more suitable for material combinations where the upper foil is thicker than lower foil. With the increase of laser energy, the interlock increased while the minimum thickness of upper foil decreased gradually. The shear strength of 1060 pure aluminum foils and 304 stainless steel foils combination was three times as large as that of 1060 pure aluminum foils and annealed copper foils combination.

  1. Fabrication of Dish-Shaped Micro Parts by Laser Indirect Shocking Compound Process

    Directory of Open Access Journals (Sweden)

    Huixia Liu

    2016-06-01

    Full Text Available Compound process technology has been investigated for many years on a macro scale, but only a few studies can be found on a micro scale due to the difficulties in tool manufacturing, parts transporting and punch-die alignment. In this paper, a novel technology of combining the laser shock wave and soft punch was introduced to fabricate the dish-shaped micro-parts on copper to solve these difficulties. This compound process includes deep drawing, punching and blanking and these processes can be completed almost at the same time because the duration time of laser is quite short, so the precision of the micro-parts can be ensured. A reasonable laser energy of 1550 mJ made the morphology, depth of deformation, dimensional accuracy and surface roughness achieve their best results when the thickness of the soft punches was 200 μm. In addition, thicker soft punches may hinder the compound process due to the action of unloading waves based on the elastic wave theory. So, the greatest thickness of the soft punches was 200 μm.

  2. Thermal shock tests of $beta;-sic pellets prepared from laser synthesized nanoscale sic powders

    Science.gov (United States)

    Donato, A.; Borsella, E.; Botti, S.; Martelli, S.; Nannetti, C. A.; Mancini, M. R.; Morjan, I.

    1996-10-01

    Nanoscale SiC powders, produced by laser synthesis from gaseous precursors, have been successfully used to prepare sintered pellets. All the sintered samples showed the low temperature β-SiC structures and presented an enhanced thermal conductivity (> 20%) with respect to materials prepared from commercial powders. Samples hardness and toughness, comparable with commercial products, confirmed the good samples quality. The thermal shock tests have been performed by irradiating the pellets with a Nd-YAG pulsed laser (pulse duration and energy: 0.25 μs and 0.18 J or 0.4 ms and 0.65 J). The laser fluence (power density) was increased by reducing the spot size, up to the appearance of a visible surface damage. The threshold values for the structural damage were quantified using a heat flux parameter φ abs√ tp. The measured threshold value rose from ca. 20 MW/m 2 √s for the best materials prepared from commercial SiC powders to ca. 24 MW/m 2√s for the newly developed β-SiC.

  3. Hot electron generation and energy coupling in planar experiments with shock ignition high intensity lasers

    Science.gov (United States)

    Wei, M. S.; Krauland, C.; Alexander, N.; Zhang, S.; Peebles, J.; Beg, F. N.; Theobald, W.; Borwick, E.; Ren, C.; Yan, R.; Haberberger, D.; Betti, R.; Campbell, E. M.

    2016-10-01

    Hot electrons produced in nonlinear laser plasma interactions are critical issues for shock ignition (SI) laser fusion. We conducted planar target experiments to characterize hot electron and energy coupling using the high energy OMEGA EP laser system at SI high intensities. Targets were multilayered foils consisting of an ablator (either plastic or lithium) and a Cu layer to facilitate hot electron detection via fluorescence and bremsstrahlung measurements. The target was first irradiated by multi-kJ, low-intensity UV beams to produce a SI-relevant mm-scale hot ( 1 keV) preformed plasma. The main interaction pulse, either a kJ 1-ns UV pulse with intensity 1.6x1016 Wcm-2 or a kJ 0.1-ns IR pulse with intensity up to 2x1017 Wcm-2was injected at varied timing delays. The high intensity IR beam was found to strongly interact with underdense plasmas breaking into many filaments near the quarter critical density region followed by propagation of those filaments to critical density, producing hot electrons with Thot 70 keV in a well-contained beam. While the high intensity UV beam showed poor energy coupling. Details of the experiments and the complementary PIC modeling results will be presented. Work supported by U.S. DOE under contracts DE-NA0002730 (NLUF) and DE-SC0014666 (HEDLP).

  4. Pulsed laser-induced formation of silica nanogrids

    National Research Council Canada - National Science Library

    Ihlemann, Jürgen; Weichenhain-Schriever, Ruth

    2014-01-01

    ... ) coating through the transparent substrate. A polydimethylsiloxane (PDMS) superstrate (cover layer) coated on top of the SiO x film prior to laser exposure serves as confinement for controlled laser-induced structure formation...

  5. Shock-induced localized amorphization in boron carbide.

    Science.gov (United States)

    Chen, Mingwei; McCauley, James W; Hemker, Kevin J

    2003-03-01

    High-resolution electron microscope observations of shock-loaded boron carbide have revealed the formation of nanoscale intragranular amorphous bands that occur parallel to specific crystallographic planes and contiguously with apparent cleaved fracture surfaces. This damage mechanism explains the measured, but not previously understood, decrease in the ballistic performance of boron carbide at high impact rates and pressures. The formation of these amorphous bands is also an example of how shock loading can result in the synthesis of novel structures and materials with substantially altered properties.

  6. Shock tube study on the thermal decomposition of fluoroethane using infrared laser absorption detection of hydrogen fluoride.

    Science.gov (United States)

    Matsugi, Akira; Shiina, Hiroumi

    2014-08-28

    Motivated by recent shock tube studies on the thermal unimolecular decomposition of fluoroethanes, in which unusual trends have been reported for collisional energy-transfer parameters, the rate constants for the thermal decomposition of fluoroethane were investigated using a shock tube/laser absorption spectroscopy technique. The rate constants were measured behind reflected shock waves by monitoring the formation of HF by IR absorption at the R(1) transition in the fundamental vibrational band near 2476 nm using a distributed-feedback diode laser. The peak absorption cross sections of this absorption line have also been determined and parametrized using the Rautian-Sobel'man line shape function. The rate constant measurements covered a wide temperature range of 1018-1710 K at pressures from 100 to 290 kPa, and the derived rate constants were successfully reproduced by the master equation calculation with an average downward energy transfer, ⟨ΔEdown⟩, of 400 cm(-1).

  7. Shock-induced fine-grained recrystallization of olivine - Evidence against subsolidus reduction of Fe/2+/

    Science.gov (United States)

    Ahrens, T. J.; Tsay, F.-D.; Live, D. H.

    1976-01-01

    Electron spin resonance (ESR) studies have been carried out on three single grains of terrestrial olivine (Fo90) shock loaded along the 010 line to peak pressures of 280, 330, and 440 kbar. The results indicate that neither metallic Fe similar to that observed in returned lunar soils nor paramagnetic Fe(3+) caused by oxidation of Fe(2+) has been produced in these shock experiments. Trace amounts of Mn (2+) have been detected in both shocked and unshocked olivine. The ESR signals of Mn(2+) show spectral features which are found to correlate with the degree of shock-induced recrystallization observed petrographically. The increasing mass fraction of recrystallized olivine correlates with increasing shock pressures. This phenomenon is modelled assuming it results from the progressive effect of the shock-induced transformation of the olivine to a yet unknown high-pressure phase and its subsequent reversion to the low-pressure olivine phase. The mass fraction of recrystallized material is predicted to be nearly linear with shock pressure.

  8. [Osmotic shock induces expression of Vibrio fischeri lux genes in Escherichia coli cells].

    Science.gov (United States)

    Zavil'gel'skiĭ, G B; Kotova, V Iu

    2003-04-01

    The effect of osmotic shock on the expression of genes in the lux regulon of marine bacteria Vibrio fischeri was studied in cells of Escherichia coli. Bioluminescence of cells was shown to drastically increase, when cells were exposed to osmotic shock at the early logarithmic growth phase. The expression of lux genes induced by osmotic shock is determined by the two-component regulatory system RcsC-RcsB. A nucleotide sequence in the regulatory region of the luxR gene homologous to the RcsB-box consensus of E. coli is assumed to be a primary site for this system.

  9. The Effect of Air Humidity on Shock Wave Induced Incipient Spearation

    Institute of Scientific and Technical Information of China (English)

    PiotrDOERFFER; AndrzejSZUMOWSKI; 等

    2000-01-01

    During earlier research on shock wave/boundary layer interaction control,the effect of air humidity on flow separation has been observed.This has inspired a more detailed study on the effect of air humidity on shock induced incipient separation and on the involved preocesses.The phenomenon has a twofold nature.In supersonic flow the condensation of humidity causes flow retadation due to heat addition.The consequent weakenling of the shock wave reduces the tendency towards separatio.On the other hand,the incipient separation is postponed at the same Mach numers of interaction.

  10. Shock formation induced by poloidal flow and its effects on the edge stability in tokamaks

    Science.gov (United States)

    Seol, Jaechun; Shaing, Kerchung; Aydemir, Ahmet

    2016-10-01

    In the high confinement mode of tokamaks, magnitude of the radial electric field increases at the edge. Thus, the poloidal flow inside the transport barrier can be sonic when the edge pressure gradient is not steep enough to make the poloidal flow subsonic. When the poloidal Mach number is close to unity, a shock appears in the low field side and causes a large density perturbation. In this study, we describe a shock induced by the sonic poloidal plasma flow. Then, an entropy production across the shock is calculated. Finally, we introduce a simple model for Type III edge localized modes using the poloidal density variation driven by the sonic poloidal flow.

  11. Simulation of laser-driven, ablated plasma flows in collisionless shock experiments on OMEGA and the NIF

    Science.gov (United States)

    Grosskopf, M. J.; Drake, R. P.; Kuranz, C. C.; Rutter, E. M.; Ross, J. S.; Kugland, N. L.; Plechaty, C.; Remington, B. A.; Spitkovsky, A.; Gargate, L.; Gregori, G.; Bell, A.; Murphy, C. D.; Meinecke, J.; Reville, B.; Sakawa, Y.; Kuramitsu, Y.; Takabe, H.; Froula, D. H.; Fiksel, G.; Miniati, F.; Koenig, M.; Ravasio, A.; Liang, E.; Fu, W.; Woolsey, N.; Park, H.-S.

    2013-03-01

    Experiments investigating the physics of interpenetrating, collisionless, ablated plasma flows have become an important area of research in the high-energy-density field. In order to evaluate the feasibility of designing experiments that will generate a collisionless shock mediated by the Weibel instability on the National Ignition Facility (NIF) laser, computer simulations using the Center for Radiative Shock Hydrodynamics (CRASH) radiation-hydrodynamics model have been carried out. This paper reports assessment of whether the experiment can reach the required scale size while maintaining the low interflow collisionality necessary for the collisionless shock to form. Comparison of simulation results with data from Omega experiments shows the ability of the CRASH code to model these ablated systems. The combined results indicate that experiments on the NIF are capable of reaching the regimes necessary for the formation of a collisionless shock in a laboratory experiment.

  12. An LDA (Laser-Doppler Anemometry) investigation of three-dimensional normal shock wave boundary-layer interactions

    Science.gov (United States)

    Chriss, R. M.; Hingst, W. R.; Strazisar, A. J.; Keith, T. G., Jr.

    1989-01-01

    Nonintrusive measurements were made of a normal shock wave/boundary layer interaction. Two dimensional measurements were made throughout the interaction region while 3-D measurements were made in the vicinity of the shock wave. The measurements were made in the corner of the test section of a continuous supersonic wind tunnel in which a normal shock wave had been stabilized. Laser Doppler Anemometry, surface pressure measurement and flow visualization techniques were employed for two freestream Mach number test cases: 1.6 and 1.3. The former contained separated flow regions and a system of shock waves. The latter was found to be far less complicated. The results define the flow field structure in detail for each case.

  13. Unfocused extracorporeal shock waves induce anabolic effects in osteoporotic rats

    NARCIS (Netherlands)

    van der Jagt, Olav P.; Waarsing, Jan H.; Kops, Nicole; Schaden, Wolfgang; Jahr, Holger; Verhaar, Jan A. N.; Weinans, Harrie

    2013-01-01

    Unfocused extracorporeal shock waves (UESW) have been shown to have an anabolic effect on bone mass. Therefore we investigated the effects of UESW on bone in osteoporotic rats with and without anti-resorptive treatment. Twenty-week-old rats were ovariectomized (n=27). One group was treated with sali

  14. Double shock dynamics induced by the saturation of defocusing nonlinearities

    KAUST Repository

    Crosta, Matteo

    2012-01-01

    We show that the saturation of defocusing nonlinearities leads to qualitative changes in the onset of wave breaking, determining double shock formation whose regularization occurs in terms of antidark solitons. In a given material, the crossover between different regimes can be controlled by changing the input intensity. © 2012 Optical Society of America.

  15. Expression of the heat shock gene clpL of Streptococcus thermophilus is induced by both heat and cold shock

    Directory of Open Access Journals (Sweden)

    Naclerio Gino

    2006-02-01

    Full Text Available Abstract Background Heat and cold shock response are normally considered as independent phenomena. A small amount of evidence suggests instead that interactions may exist between them in two Lactococcus strains. Results We show the occurrence of molecular relationships between the mechanisms of cold and heat adaptations in Streptococcus thermophilus, a lactic acid bacterium widely used in dairy fermentation, where it undergoes both types of stress. We observed that cryotolerance is increased when cells are pre-incubated at high temperature. In addition, the production of a protein, identified as ClpL, a member of the heat-shock ATPase family Clp A/B, is induced at both high and low temperature. A knock-out clpL mutant is deficient in both heat and cold tolerance. However lack of production of this protein does not abolish the positive effect of heat pre-treatment towards cryotolerance. Conclusion Dual induction of ClpL by cold and heat exposure of cells and reduced tolerance to both temperature shocks in a clpL mutant indicates that the two stress responses are correlated in S. thermophilus. However this protein is not responsible by itself for cryotolerance of cells pre-treated at high temperature, indicating that ClpL is necessary for the two phenomena, but does not account by itself for the relationships between them.

  16. Laser-induced fluorescence imaging of bacteria

    Science.gov (United States)

    Hilton, Peter J.

    1998-12-01

    This paper outlines a method for optically detecting bacteria on various backgrounds, such as meat, by imaging their laser induced auto-fluorescence response. This method can potentially operate in real-time, which is many times faster than current bacterial detection methods, which require culturing of bacterial samples. This paper describes the imaging technique employed whereby a laser spot is scanned across an object while capturing, filtering, and digitizing the returned light. Preliminary results of the bacterial auto-fluorescence are reported and plans for future research are discussed. The results to date are encouraging with six of the eight bacterial strains investigated exhibiting auto-fluorescence when excited at 488 nm. Discrimination of these bacterial strains against red meat is shown and techniques for reducing background fluorescence discussed.

  17. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  18. Nanodot formation induced by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Abere, M. J.; Kang, M.; Goldman, R. S.; Yalisove, S. M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Chen, C. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Rittman, D. R. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Phillips, J. D. [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, B. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-10-20

    The femtosecond laser generation of ZnSe nanoscale features on ZnSe surfaces was studied. Irradiation with multiple exposures produces 10–100 nm agglomerations of nanocrystalline ZnSe while retaining the original single crystal structure of the underlying material. The structure of these nanodots was verified using a combination of scanning transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The nanodots continue to grow hours after irradiation through a combination of bulk and surface diffusion. We suggest that in nanodot formation the result of ultrafast laser induced point defect formation is more than an order of magnitude below the ZnSe ultrafast melt threshold fluence. This unique mechanism of point defect injection will be discussed.

  19. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  20. Effect of high repetition laser shock peening on biocompatibility and corrosion resistance of magnesium

    Science.gov (United States)

    Caralapatti, Vinodh Krishna; Narayanswamy, Sivakumar

    2017-02-01

    Magnesium, as a biomaterial has the potential to replace conventional implant materials owing to its numerous advantages. However, high corrosion rate is a major obstacle that has to be addressed for its implementation as implants. This study aims to evaluate the feasibility and effects of High Repetition Laser Shock Peening (HRLSP) on biocompatibility and corrosion resistance of Mg samples and as well as to analyze the effect of operational parameters such as peening with overlap on corrosion rate. From the results obtained using hydrogen evolution and mass loss methods, it was found that corrosion rates of both 0% overlap and 66% overlap peened samples reduced by more than 50% compared to that of unpeened sample and sample peened with 66% overlap exhibited least corrosion. The biocompatibility of peened Mg samples was also enhanced as there was neither rapid pH variation nor large hydrogen bubble formation around samples.

  1. High strength and high ductility behavior of 6061-T6 alloy after laser shock processing

    Science.gov (United States)

    Gencalp Irizalp, Simge; Saklakoglu, Nursen

    2016-02-01

    The plastic deformation behavior of 6061-T6 alloy which was subjected to severe plastic deformation (SPD) at high strain rates during laser shock processing (LSP) was researched. In LSP-treated materials, the near surface microstructural change was examined by TEM and fracture surfaces after tensile testing were examined by SEM. An increase in strength of metallic materials brings about the decrease in ductility. In this study, the results showed that LSP-treated 6061-T6 alloy exhibited both high strength and high ductility. TEM observation showed that stacking fault (SF) ribbon enlarged, deformation twins formed and twin boundary increased in LSP-treated 6061-T6 alloy. This observation was an indication of stacking fault energy (SFE) decrease. Work hardening capability was recovered after LSP impacts.

  2. Laser Heating of Solid Matter by Light-Pressure-Driven Shocks at Ultrarelativistic Intensities

    Energy Technology Data Exchange (ETDEWEB)

    Akli, K.U.; Hansen, S.B.; Kemp, A.J.; Freeman, R.R.; Beg, F.N.; Clark, D.C.; Chen, S.D.; Hey, D.; Hatchett, S.P.; Highbarger, K.; Giraldez, E.; Green, J.S.; Gregori, G.; Lancaster, K.L.; Ma, T.; MacKinnon, A.J.; Norreys, P.; Patel, N.; Pasley, J.; Shearer, C.; Stephens, R.B.; Stoeckl, C.; Storm, M.; Theobald, W.; Van Woerkom, L.D.; Weber, R.; Key, M.H.

    2008-04-29

    The heating of solid targets irradiated by 5 x 10^20 W cm^-2, 0.8 ps, 1.05 um wavelength laser light is studied by x-ray spectroscopy of the K-shell emission from thin layers of Ni, Mo, and V. A surface layer is heated to ~5 keV with an axial temperature gradient of 0.6 um scale length. Images of Ni Ly sub-alpha show the hot region has <25 um diameter. These data are consistent with collisional particle-in-cell simulations using preformed plasma density profiles from hydrodynamic modeling which show that the >100 Gbar light pressure compresses the preformed plasma and dries a shock into the solid, heating a thin layer.

  3. Laser heating of solid matter by light pressure-driven shocks

    Energy Technology Data Exchange (ETDEWEB)

    Akli, K; Hansen, S B; Kemp, A J; Freeman, R R; Beg, F N; Clark, D; Chen, S; Hey, D; Highbarger, K; Giraldez, E; Green, J; Gregori, G; Lancaster, K; Ma, T; MacKinnon, A J; Norreys, P A; Patel, N; Patel, P; Shearer, C; Stephens, R B; Stoeckl, C; Storm, M; Theobald, W; Van Woerkom, L; Weber, R; Key, M H

    2007-05-04

    Heating by irradiation of a solid surface in vacuum with 5 x 10{sup 20} W cm{sup -2}, 0.8 ps, 1.05 {micro}m wavelength laser light is studied by x-ray spectroscopy of the K-shell emission from thin layers of Ni, Mo and V. A surface layer is heated to {approx} 5 keV with an axial temperature gradient of 0.6 {micro}m scale length. Images of Ni Ly{sub {alpha}} show the hot region has a {approx} 25 {micro}m diameter, much smaller than {approx} 70 {micro}m region of K{sub {alpha}} emission. 2D particle-in-cell (PIC) simulations suggest that the surface heating is due to a light pressure driven shock.

  4. Systematic analysis of direct-drive baseline designs for shock ignition with the Laser MégaJoule

    Science.gov (United States)

    Brandon, V.; Canaud, B.; Laffite, S.; Temporal, M.; Ramis, R.

    2013-11-01

    We present direct-drive target design studies for the laser mégajoule using two distinct initial aspect ratios (A = 34 and A = 5). Laser pulse shapes are optimized by a random walk method and drive power variations are used to cover a wide variety of implosion velocities between 260 km/s and 365 km/s. For selected implosion velocities and for each initial aspect ratio, scaled-target families are built in order to find self-ignition threshold. High-gain shock ignition is also investigated in the context of Laser MégaJoule for marginally igniting targets below their own self-ignition threshold.

  5. Turbulent amplification of magnetic fields in laboratory laser-produced shock waves

    Science.gov (United States)

    Meinecke, J.; Doyle, H. W.; Miniati, F.; Bell, A. R.; Bingham, R.; Crowston, R.; Drake, R. P.; Fatenejad, M.; Koenig, M.; Kuramitsu, Y.; C. Kuranz, C.; Lamb, D. Q.; Lee, D.; MacDonald, M. J.; Murphy, C. D.; Park, H.-S.; Pelka, A.; Ravasio, A.; Sakawa, Y.; Schekochihin, A. A.; Scopatz, A.; Tzeferacos, P.; Wan, W. C.; Woolsey, N. C.; Yurchak, R.; Reville, B.; Gregori, G.

    2014-07-01

    X-ray and radio observations of the supernova remnant Cassiopeia A reveal the presence of magnetic fields about 100 times stronger than those in the surrounding interstellar medium. Field coincident with the outer shock probably arises through a nonlinear feedback process involving cosmic rays. The origin of the large magnetic field in the interior of the remnant is less clear but it is presumably stretched and amplified by turbulent motions. Turbulence may be generated by hydrodynamic instability at the contact discontinuity between the supernova ejecta and the circumstellar gas. However, optical observations of Cassiopeia A indicate that the ejecta are interacting with a highly inhomogeneous, dense circumstellar cloud bank formed before the supernova explosion. Here we investigate the possibility that turbulent amplification is induced when the outer shock overtakes dense clumps in the ambient medium. We report laboratory experiments that indicate the magnetic field is amplified when the shock interacts with a plastic grid. We show that our experimental results can explain the observed synchrotron emission in the interior of the remnant. The experiment also provides a laboratory example of magnetic field amplification by turbulence in plasmas, a physical process thought to occur in many astrophysical phenomena.

  6. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  7. Micro-structural strengthening mechanism of multiple laser shock processing impacts on AISI 8620 steel

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Zhong, J.W., E-mail: zjw1033@126.com [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Luo, K.Y.; Zhang, L.; Dai, F.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Chen, K.M. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Q.W.; Zhong, J.S.; Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China)

    2011-07-25

    Highlights: {yields} LSP can clearly refine coarse grains in the shocked region by dislocation movement. {yields} Micro-structural evolution of AISI 8620 steel after LSP impacts is revealed. {yields} LSP on AISI 8620 steel have grain refinement and dispersion strengthening of carbon. {yields} The results can provide some insights on surface modification of low carbon steel. - Abstract: Micro-structural evolution in the near-surface region of AISI 8620 steel subjected to multiple laser shock processing (LSP) impacts were investigated by means of cross-sectional optical microscopy (OM) and transmission electron microscopy (TEM) observations. Micro-structural evolution process subjected to multiple LSP impacts can be described as follows: (i) the parallel lamellar pearlites are broken into bitty pearlites, and dislocation activities simultaneously led to the formation of dislocation lines (DLs) and dislocation pile-ups in original grains; (ii) bitty pearlites were all broken into Fe{sub 3}C granules, and dislocation movement made Fe{sub 3}C granules disperse near subgrain boundaries and led to subgrain boundaries separating individual cells, and (iii) subgrain boundaries were refined to grain boundaries. Multiple LSP impacts on AISI 8620 steel had dual-function: the refinement of coarse grains in the near-surface region by dislocation movement and dispersion strengthening of C atoms which cut cementite and diffused into the ferrite by moving dislocations.

  8. Laser-Induced Incandescence in Microgravity

    Science.gov (United States)

    VanderWal, Randy L.

    1997-01-01

    Knowledge of soot concentration is important due to its presence and impact upon a wide range of combustion processes ranging from diffusion to premixed flames, laminar to turbulent processes and homogeneous to heterogeneous combustion. Measurement of soot volume fraction (f(sub v)) is essential to discerning its formation and growth. The presence of soot also affects other physical and chemical properties of combustion thereby affecting studies not directly concerned with either its formation or growth, such as radiative heat transfer, CO oxidation and fuel vaporization or pyrolysis rates. Microgravity offers unique opportunities for studying both soot growth and the effect of soot radiation upon flame structure and spread. Spatial scales and residence time scales are greatly extended in 0-g facilitating soot growth studies. With the varied geometries, short duration microgravity test times and time-varying processes there is a demand for measurement of f(sub v) with high spatial and temporal resolution. Laser-induced incandescence (LII) has advanced f(sub v) measurements in many 1-g combustion processes. To create laser-induced incandescence, a pulsed high intensity laser heats soot to incandescence temperatures. Using appropriate spectral and temporal detection conditions, the resulting incandescence can be selectively detected apart from the non-laser-heated soot and flame gases. Theoretical modelling and experiments have shown that the resulting incandescence is representative of f(sub v). Using an intensified array camera and a laser sheet for excitation, one- and two-dimensionally resolved LII images of f(sub v) have been obtained in 1-g. LII has been characterized and developed at NASA-Lewis for soot volume fraction determination in a wide range of 1-g combustion applications. Broadly grouped, the characterization work has included studies of excitation intensity, excitation wavelength and the optimum temporal and spectral detection conditions to enable an

  9. A thermochemical model for shock-induced reactions (heat detonations) in solids

    Energy Technology Data Exchange (ETDEWEB)

    Boslough, M.B. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (US))

    1990-02-01

    Recent advances in studies of shock-induced chemistry in reactive solids have led to the recognition of a new class of energetic materials which are unique in their response to shock waves. Experimental work has shown that chemical energy can be released on a time scale shorter than shock-transit times in laboratory samples. However, for many compositions, the reaction products remain in the condensed state upon release from high pressure, and no sudden expansion takes place. Nevertheless, if such a reaction is sufficiently rapid, it can be modeled as a type of detonation, termed heat detonation'' in the present paper. It is shown that unlike an explosive detonation, an unsupported heat detonation will decay to zero unless certain conditions are met. An example of such a reaction is Fe{sub 2}O{sub 3} +2Al+shock{r arrow}Al{sub 2} O{sub 3} +2Fe (the standard thermite reaction). A shock-wave equation of state is determined from a mixture theory for reacted and unreacted porous thermite. The calculated shock temperatures are compared to experimentally measured shock temperatures, demonstrating that a shock-induced reaction takes place. Interpretation of the measured temperature history in the context of the thermochemical model implies that the principal rate-controlling kinetic mechanism is dynamic mixing at the shock front. Despite the similarity in thermochemical modeling of heat detonations to explosive detonations, the two processes are qualitatively very different in reaction mechanism as well as in the form the energy takes upon release, with explosives producing mostly work and heat detonations producing mostly heat.

  10. Effect of laser shock processing on residual stress and fatigue behavior of 6061-T651 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    REN Xu-dong; ZHANG Yong-kang; ZHOU Jian-zhong; FEN Ai-xin

    2006-01-01

    Laser shock processing is a very new technique and an emerging modern process that generates compressive stresses much deeper into the surfaces of metals or alloys. A brief parametric study of the effect of laser parameters on fatigue behavior and residual stress state generated in 6061-T651 alloy specimens was summarized. Residual stress of 6061-T651 alloy was analyzed both before and after laser processing with multishocks. The material remains in compressive residual stress of approximate lmm in depth which is approximately 10 times deeper than that can be achieved with the conventional technique, and the maximal compressive residual stress at the surface of the sampleis about -350MPa. Near the surface, yield strength and hardness are found to be increased by the laser shock. The ratio of fatigue crack initiation life for the laser-shocked to unshocked specimens is found to be 4.9 for specimens. The results clearly show that LSP is an effective surface treatment technique for improving the fatigue performance of aluminum alloys.

  11. Enhanced efficiency of plasma acceleration in the laser-induced cavity pressure acceleration scheme

    Science.gov (United States)

    Badziak, J.; Rosiński, M.; Jabłoński, S.; Pisarczyk, T.; Chodukowski, T.; Parys, P.; Rączka, P.; Krousky, E.; Ullschmied, J.; Liska, R.; Kucharik, M.

    2015-01-01

    Among various methods for the acceleration of dense plasmas the mechanism called laser-induced cavity pressure acceleration (LICPA) is capable of achieving the highest energetic efficiency. In the LICPA scheme, a projectile placed in a cavity is accelerated along a guiding channel by the laser-induced thermal plasma pressure or by the radiation pressure of an intense laser radiation trapped in the cavity. This arrangement leads to a significant enhancement of the hydrodynamic or electromagnetic forces driving the projectile, relative to standard laser acceleration schemes. The aim of this paper is to review recent experimental and numerical works on LICPA with the emphasis on the acceleration of heavy plasma macroparticles and dense ion beams. The main experimental part concerns the research carried out at the kilojoule sub-nanosecond PALS laser facility in Prague. Our measurements performed at this facility, supported by advanced two-dimensional hydrodynamic simulations, have demonstrated that the LICPA accelerator working in the long-pulse hydrodynamic regime can be a highly efficient tool for the acceleration of heavy plasma macroparticles to hyper-velocities and the generation of ultra-high-pressure (>100 Mbar) shocks through the collision of the macroparticle with a solid target. The energetic efficiency of the macroparticle acceleration and the shock generation has been found to be significantly higher than that for other laser-based methods used so far. Using particle-in-cell simulations it is shown that the LICPA scheme is highly efficient also in the short-pulse high-intensity regime and, in particular, may be used for production of intense ion beams of multi-MeV to GeV ion energies with the energetic efficiency of tens of per cent, much higher than for conventional laser acceleration schemes.

  12. Laser-Induced Breakdown Spectroscopy: Capabilities and Applications

    Science.gov (United States)

    2010-07-01

    sample preparation. 14 6. References 1. Cremers D.A.; Radziemski, L. J. Handbook of Laser-Induced Breakdown Spectroscopy; West Sussex, England...30 (21), 2882–2884. 17. Salle, B.; Lacour, J. L.; Vors, E.; Fichet, P.; Maurice, S.; Cremers , D. A.; et al. Laser- Induced Breakdown Spectroscopy...90. Martin , M. Z.; Labbe, N.; Andre, N.; Harris, R.; Ebinger, M.; Wullschleger, S. D.; et al. High Resolution Applications of Laser-Induced

  13. Laser-induced breakdown spectroscopy in Asia

    Science.gov (United States)

    Wang, Zhen-Zhen; Deguchi, Yoshihiro; Zhang, Zhen-Zhen; Wang, Zhe; Zeng, Xiao-Yan; Yan, Jun-Jie

    2016-12-01

    Laser-induced breakdown spectroscopy (LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental composition. LIBS has been extensively studied and developed due to the non-contact, fast response, high sensitivity, real-time and multi-elemental detection features. The development and applications of LIBS technique in Asia are summarized and discussed in this review paper. The researchers in Asia work on different aspects of the LIBS study in fundamentals, data processing and modeling, applications and instrumentations. According to the current research status, the challenges, opportunities and further development of LIBS technique in Asia are also evaluated to promote LIBS research and its applications.

  14. [INVITED] On the mechanisms of single-pulse laser-induced backside wet etching

    Science.gov (United States)

    Tsvetkov, M. Yu.; Yusupov, V. I.; Minaev, N. V.; Akovantseva, A. A.; Timashev, P. S.; Golant, K. M.; Chichkov, B. N.; Bagratashvili, V. N.

    2017-02-01

    Laser-induced backside wet etching (LIBWE) of a silicate glass surface at interface with a strongly absorbing aqueous dye solution is studied. The process of crater formation and the generated optoacoustic signals under the action of single 5 ns laser pulses at the wavelength of 527 nm are investigated. The single-pulse mode is used to avoid effects of incubation and saturation of the etched depth. Significant differences in the mechanisms of crater formation in the "soft" mode of laser action (at laser fluencies smaller than 150-170 J/cm2) and in the "hard" mode (at higher laser fluencies) are observed. In the "soft" single-pulse mode, LIBWE produces accurate craters with the depth of several hundred nanometers, good shape reproducibility and smooth walls. Estimates of temperature and pressure of the dye solution heated by a single laser pulse indicate that these parameters can significantly exceed the corresponding critical values for water. We consider that chemical etching of glass surface (or molten glass) by supercritical water, produced by laser heating of the aqueous dye solution, is the dominant mechanism responsible for the formation of crater in the "soft" mode. In the "hard" mode, the produced craters have ragged shape and poor pulse-to-pulse reproducibility. Outside the laser exposed area, cracks and splits are formed, which provide evidence for the shock induced glass fracture. By measuring the amplitude and spectrum of the generated optoacoustic signals it is possible to conclude that in the "hard" mode of laser action, intense hydrodynamic processes induced by the formation and cavitation collapse of vapor-gas bubbles at solid-liquid interface are leading to the mechanical fracture of glass. The LIBWE material processing in the "soft" mode, based on chemical etching in supercritical fluids (in particular, supercritical water) is very promising for structuring of optical materials.

  15. Numerical study on the suppression of shock induced separation on the non-adiabatic wall

    Science.gov (United States)

    Lee, Doug-Bong

    2000-12-01

    A numerical model is constructed to simulate the interaction of supersonic ( M=2.4) oblique shock wave / turbulent boundary layer on a strongly heated wall. The heated wall temperature is two times higher than the adiabatic wall temperature and the shock wave is strong enough to induce boundary layer separation. The turbulence model is Spalart-Allmaras model. The comparison of the wall pressure distribution with the experimental data ensures the validity of this numerical model. The effect of strong wall heating enlarges the separation region upstream and downstream. In order to eliminate the separation, wall bleeding is applied at the shock foot position. As a result of the parametric study, the best position of the bleeding slot is selected. The position of the bleeding is very important for the separation suppression. If the bleeding is applied upstream of shock foot, then separation reoccurs after the bleeding slot. If the bleeding is applied downstream of shock foot, the upstream boundary layer is little influenced and still separated. The bleeding vent width is about same as the upstream boundary layer thickness and suction mass flow is 20 to 80 % of the flow rate in the upstream boundary layer. The bleeding mass flow rate is very sensitive to the bleeding vent position if we fix the vent outlet pressure. The final configuration of the shock reflection pattern approaches to the non-viscous value when wall bleeding is applied at the shock impinging point.

  16. Hypovolemic shock following induced abortion and spontaneous heterotopic pregnancy

    OpenAIRE

    Abdolghader Pakniyat; Arash Yazdanbakhsh; Ghasem Moshar-mowahed; Fatimah Talebi

    2015-01-01

    Spontaneous heterotopic pregnancy is a rare clinical condition in which intrauterine and extrauterine pregnancies occur at the same time. It is rare, estimated to occur in 1 in 30,000 pregnancies. The case was a 38-year-old woman with spontaneously conceived heterotopic pregnancy. She was admitted to our center with hypovolemic shock. Focused assessment sonography for trauma examination in emergency department showed large amount of free fluid in peritoneal cavity. She was managed surgical la...

  17. Shock tube/laser absorption measurements of the reaction rates of OH with ethylene and propene.

    Science.gov (United States)

    Vasu, Subith S; Hong, Zekai; Davidson, David F; Hanson, Ronald K; Golden, David M

    2010-11-04

    Reaction rates of hydroxyl (OH) radicals with ethylene (C₂H₄) and propene (C₃H₆) were studied behind reflected shock waves. OH + ethylene → products (rxn 1) rate measurements were conducted in the temperature range 973-1438 K, for pressures from 2 to 10 atm, and for initial concentrations of ethylene of 500, 751, and 1000 ppm. OH + propene → products (rxn 2) rate measurements spanned temperatures of 890-1366 K, pressures near 2.3 atm, and initial propene concentrations near 300 ppm. OH radicals were produced by shock-heating tert-butyl hydroperoxide, (CH₃)₃-CO-OH, and monitored by laser absorption near 306.7 nm. Rate constants for the reactions of OH with ethylene and propene were extracted by matching modeled and measured OH concentration time-histories in the reflected shock region. Current data are in excellent agreement with previous studies and extend the temperature range of OH + propene data. Transition state theory calculations using recent ab initio results give excellent agreement with our measurements and other data outside our temperature range. Fits (in units of cm³/mol/s) to the abstraction channels of OH + ethylene and OH + propene are k₁ = 2.23 × 10⁴ (T)(2.745) exp(-1115 K/T) for 600-2000 K and k₂ = 1.94 × 10⁶ (T)(2.229) exp(-540 K/T) for 700-1500 K, respectively. A rate constant determination for the reaction TBHP → products (rxn 3) was also obtained in the range 745-1014 K using OH data from behind both incident and reflected shock waves. These high-temperature measurements were fit with previous low-temperature data, and the following rate expression (0.6-2.6 atm), applicable over the temperature range 400-1050 K, was obtained: k₃ (1/s) = 8.13 × 10⁻¹² (T)(7.83) exp(-14598 K/T).

  18. Laser-excited optical emission response of CdTe quantum dot/polymer nanocomposite under shock compression

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Kang, Zhitao; Summers, Christopher J. [Phosphor Technology Center of Excellence, Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); Bansihev, Alexandr A.; Christensen, James M.; Dlott, Dana D. [School of Chemical Sciences and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Breidenich, Jennifer; Scripka, David A.; Thadhani, Naresh N. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Zhou, Min, E-mail: min.zhou@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States)

    2016-01-04

    Laser-driven shock compression experiments and corresponding finite element method simulations are carried out to investigate the blueshift in the optical emission spectra under continuous laser excitation of a dilute composite consisting of 0.15% CdTe quantum dots by weight embedded in polyvinyl alcohol polymer. This material is a potential candidate for use as internal stress sensors. The analyses focus on the time histories of the wavelength blue-shift for shock loading with pressures up to 7.3 GPa. The combined measurements and calculations allow a relation between the wavelength blueshift and pressure for the loading conditions to be extracted. It is found that the blueshift first increases with pressure to a maximum and subsequently decreases with pressure. This trend is different from the monotonic increase of blueshift with pressure observed under conditions of quasistatic hydrostatic compression. Additionally, the blueshift in the shock experiments is much smaller than that in hydrostatic experiments at the same pressure levels. The differences in responses are attributed to the different stress states achieved in the shock and hydrostatic experiments and the time dependence of the mechanical response of the polymer in the composite. The findings offer a potential guide for the design and development of materials for internal stress sensors for shock conditions.

  19. Sleep deprivation increase the expression of inducible heat shock protein 70 in rat gastric mucosa

    Institute of Scientific and Technical Information of China (English)

    Xi-Zhong Shen1; Marcel W.L. Koo; Chi-Hin Cho

    2001-01-01

    AIM To .investigate if sleep deprivation is able to increase the expression of inducible heat shock protein 70 in gastric mucosa and its possible role in mucosal defense. METHODS Rats for sleep disruption were placed inside a computerized rotating drum, gastric mucosa was taken from rats with 1, 3 and 7 d sleep deprivation. RT-PCR,immunohistochemistry and Western blotting were used to determine the expression of heat shock protein 70.Ethanol (500 mL@ L 1, I.g.) was used to induce gastric muceea damage. RESULTS RT-PCR, Western blotting and immunostaining confirmed that the sleep deprivation as a stress resulted in significantly greater expression of inducible heat shock protein 70 in gastric mucosa of rats. After the 500mL@ L-1 ethanol challenge, the ulcer area found in the rats with 7 d sleep deprivation (19.15 ± 4.2) mm2 was significantly lower (P<0.01) than the corresponding control (53.7 ± 8.1) mm2. CONCLUSION Sleep deprivation as a stress, in addition to lowering the gastric mucosal barrier, is able to stimulate the expression of inducible heat shock protein 70 in gastric mucosa of rats, the heat shock protein 70 may play an important role in gastric mucosal protection.

  20. A shock-induced polymorph of anatase and rutile from the Chesapeake Bay impact structure, Virginia, U.S.A

    Science.gov (United States)

    Jackson, J.C.; Horton, J.W.; Chou, I.-Ming; Belkin, H.E.

    2006-01-01

    A shock-induced polymorph (TiO2II) of anatase and rutile has been identified in breccias from the late Eocene Chesapeake Bay impact structure. The breccia samples are from a recent, partially cored test hole in the central uplift at Cape Charles, Virginia. The drill cores from 744 to 823 m depth consist of suevitic crystalline-clast breccia and brecciated cataclastic gneiss in which the TiO2 phases anatase and rutile are common accessory minerals. Electron-microprobe imaging and laser Raman spectroscopy of TiO2 crystals, and powder X-ray diffraction (XRD) of mineral concentrates, confirm that a high-pressure, ??-PbO2 structured polymorph of TiO2 (TiO2II) coexists with anatase and rutile in matrix-hosted crystals and in inclusions within chlorite. Raman spectra of this polymorph include strong bands at wavenumbers (cm-1) 175, 281, 315, 342, 356, 425, 531, 571, and 604; they appear with anatase bands at 397, 515, and 634 cm-1, and rutile bands at 441 and 608 cm-1. XRD patterns reveal 12 lines from the polymorph that do not significantly interfere with those of anatase or rutile, and are consistent with the TiO2II that was first reported to occur naturally as a shock-induced phase in rutile from the Ries crater in Germany. The recognition here of a second natural shock-induced occurrence of TiO2II suggests that its presence in rocks that have not been subjected to ultrahigh-pressure regional metamorphism can be a diagnostic indicator for confirmation of suspected impact structures.

  1. Laser induced single spot oxidation of titanium

    Science.gov (United States)

    Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-01

    Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels' colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  2. Thermal stresses in functionally graded materials caused by a laser thermal shock

    Energy Technology Data Exchange (ETDEWEB)

    Elperin, T.; Rudin, G. [Department of Mechanical Engineering, Pearlstone Center for Aeronautical Engineering Studies Ben-Gurion University of the Negev, Beer-Sheva (Israel)

    2002-08-01

    Mathematical simulation of a thermal shock method for reliability testing of functionally graded material (FGM) is performed with the end to determine operating parameters of the testing device (power of a laser, laser beam radius, duration of heating) and to investigate the effect of the composition of FGM on a magnitude of thermal stresses in a coating. An analytical method for solution of the thermal elasticity problem is developed whereby the approach of a multilayer plate is used for determining temperature and thermal stresses distributions in a coating. We considered the limiting case of the obtained solution when the thickness of a layer is infinitesimally small and the number of layers tends to infinity. This procedure allowed us to obtain the thermal stresses distribution in a FGM coating. The results for the FGM coating composed of WC (tungsten carbide) ceramics and HS-steel are presented. It is showed that variation of the volume content of ceramics strongly affects thermal stresses in a coating and they decrease significantly in the case of the uniform spatial distribution of ceramics. (orig.)

  3. Influence of deposited energy on shock wave induced by underwater pulsed current discharge

    Science.gov (United States)

    Li, Xian-Dong; Liu, Yi; Liu, Si-Wei; Li, Zhi-Yuan; Zhou, Gu-Yue; Li, Hua; Lin, Fu-Chang; Pan, Yuan

    2016-10-01

    In this paper, an integrated experimental system is established to study the influence of deposited energy on the intensity of the shock wave induced by underwater pulse discharge. Considering the time varying behavior of the arc, the calculation methods of the deposited energy into the plasma channel and the average arc resistance are proposed and presented. The effect of the breakdown process on the deposited energy and the shock wave is analyzed. It can be concluded that the shock wave intensity can be improved by depositing more energy in the first half oscillation period and increasing the arc resistance. It is also found that the energy deposition and the shock wave intensity are significantly influenced by the breakdown time delay and the shape of the initial plasma channel.

  4. Mineralogy and Microstructures of Shock-Induced Melt Veins in Chondrites

    Science.gov (United States)

    Sharp, Thomas G.

    2000-01-01

    The applicability of phase equilibrium data to the interpretation of shock-induced melt veins can only be tested by a detailed study of melt- vein mineralogy to see how high-pressure assemblages vary as a function of shock conditions inferred from other indicators. We have used transmission electron microscopy (TEM), analytical electron microscopy (AEM), scanning electron microscopy (SEM), electron microprobe analysis (EMA) and optical petrography to characterize the mineralogy, microstructures, and compositions of melt veins and associated high-pressure minerals in shocked chondrites and SNC meteorites. In the processes, we have gained a better understanding of what melt veining can tell us about shock conditions and we have discovered new mineral phases in chondritic and SNC meteorites.

  5. Study on Mach stems induced by interaction of planar shock waves on two intersecting wedges

    Institute of Scientific and Technical Information of China (English)

    Gaoxiang Xiang; Chun Wang; Honghui Teng; Yang Yang; Zonglin Jiang

    2016-01-01

    The properties of Mach stems in hypersonic corner flow induced by Mach interaction over 3D inter-secting wedges were studied theoretically and numerically. A new method called “spatial dimension reduction” was used to analyze theoretically the location and Mach num-ber behind Mach stems. By using this approach, the problem of 3D steady shock/shock interaction over 3D intersecting wedges was transformed into a 2D moving one on cross sec-tions, which can be solved by shock-polar theory and shock dynamics theory. The properties of Mach interaction over 3D intersecting wedges can be analyzed with the new method, including pressure, temperature, density in the vicinity of triple points, location, and Mach number behind Mach stems. Theoretical results were compared with numerical results, and good agreement was obtained. Also, the influence of Mach number and wedge angle on the properties of a 3D Mach stem was studied.

  6. Analysis of Residual Stresses in Laser-Shock-Peened and Shot-Peened Marine Steel Welds

    Science.gov (United States)

    Ahmad, Bilal; Fitzpatrick, Michael E.

    2017-02-01

    Laser peening is now the preferred method of surface treatment in many applications. The magnitude and depth of the compressive residual stress induced by laser peening can be influenced strongly by the number of peen layers (the number of laser hits at each point) and by processing conditions including the use of a protective ablative layer. In this study, residual stresses have been characterized in laser and shot-peened marine butt welds with a particular focus at the fatigue crack initiation location at the weld toe. X-ray diffraction, synchrotron X-ray diffraction, incremental center-hole drilling, and the contour method were used for determination of residual stress. Results showed that the use of ablative tape increased the surface compressive stress, and the depth of compressive stress increased with an increase in number of peening layers. A key result is that variation of residual stress profile across laser peen spots was seen, and the residual stress magnitude varies between the center and edges of the spots.

  7. Shock tube/laser absorption studies of the decomposition of methyl formate

    KAUST Repository

    Ren, Wei

    2013-01-01

    Reaction rate coefficients for the major high-temperature methyl formate (MF, CH3OCHO) decomposition pathways, MF → CH3OH + CO (1), MF →CH2O+CH2O (2), and MF→ CH4 + CO2 (3), were directly measured in a shock tube using laser absorption of CO (4.6 μm), CH2O (306 nm) and CH4 (3.4 μm). Experimental conditions ranged from 1202 to 1607 K and 1.36 to 1.72 atm, with mixtures varying in initial fuel concentration from 0.1% to 3% MF diluted in argon. The decomposition rate coefficients were determined by monitoring the formation rate of each target species immediately behind the reflected shock waves and modeling the species time-histories with a detailed kinetic mechanism [12]. The three measured rate coefficients can be well-described using two-parameter Arrhenius expressions over the temperature range in the present study: k1 = 1.1 × 1013 exp(-29556/T, K) s -1, k2 = 2.6 × 1012 exp(-32052/T, K) s-1, and k3 = 4.4 × 1011 exp(-29 078/T, K) s-1, all thought to be near their high-pressure limits. Uncertainties in the k1, k2 and k3 measurements were estimated to be ±25%, ±35%, and ±40%, respectively. We believe that these are the first direct high-temperature rate measurements for MF decomposition and all are in excellent agreement with the Dooley et al. [12] mechanism. In addition, by also monitoring methanol (CH3OH) and MF concentration histories using a tunable CO2 gas laser operating at 9.67 and 9.23 μm, respectively, all the major oxygen-carrying molecules were quantitatively detected in the reaction system. An oxygen balance analysis during MF decomposition shows that the multi-wavelength laser absorption strategy used in this study was able to track more than 97% of the initial oxygen atoms in the fuel. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

  8. The L-type cyclin CYL-1 and the heat-shock-factor HSF-1 are required for heat-shock-induced protein expression in Caenorhabditis elegans.

    Science.gov (United States)

    Hajdu-Cronin, Yvonne M; Chen, Wen J; Sternberg, Paul W

    2004-12-01

    In a screen for suppressors of activated GOA-1 (Galpha(o)) under the control of the hsp-16.2 heat-shock promoter, we identified three genetic loci that affected heat-shock-induced GOA-1 expression. The cyl-1 mutants are essentially wild type in appearance, while hsf-1 and sup-45 mutants have egg-laying defects. The hsf-1 mutation also causes a temperature-sensitive developmental arrest, and hsf-1 mutants have decreased life span. Western analysis indicated that mutations in all three loci suppressed the activated GOA-1 transgene by decreasing its expression. Heat-shock-induced expression of hsp-16.2 mRNA was reduced in cyl-1 mutants and virtually eliminated in hsf-1 and sup-45 mutants, as compared to wild-type expression. The mutations could also suppress other transgenes under heat-shock control. cyl-1 and sup-45, but not hsf-1, mutations suppressed a defect caused by a transgene not under heat-shock control, suggesting a role in general transcription or a post-transcriptional aspect of gene expression. hsf-1 encodes the C. elegans homolog of the human heat-shock factor HSF1, and cyl-1 encodes a cyclin most similar to cyclin L. We believe HSF-1 acts in heat-shock-inducible transcription and CYL-1 acts more generally in gene expression.

  9. Research status of key techniques for shock-induced combustion ramjet(shcramjet) engine

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As one of the most promising propulsion systems in the future,shock-induced combustion ramjet engine can remedy the disadvantages in the integrated design of scramjet engine and airframe.It can shorten the length of the combustor,lighten the structure weight of the engine and keep better performance in a broad range of flight Mach number.The elementary principle of shock-induced combustion ramjet engine is introduced.The key technologies of this kind of propulsion system are described,while their research status is presented in detail.Suggestion on the development of shcramjet engine in China is put forward.

  10. Femtosecond laser induced microripple on PDMS surface

    Institute of Scientific and Technical Information of China (English)

    Jin Xie; Changhe Zhou; Wei Wang; Tengfei Wu

    2009-01-01

    laser pulses and the subsequent cool-down solidification of the melting PDMS along with the movement of the femtosecond laser spot. This result will be helpful to understand the interaction between the femtosecond laser and the polymer.

  11. Time-resolved spectroscopic measurements of shock-wave induced decomposition in cyclotrimethylene trinitramine (RDX) crystals: anisotropic response.

    Science.gov (United States)

    Dang, Nhan C; Dreger, Zbigniew A; Gupta, Yogendra M; Hooks, Daniel E

    2010-11-04

    Plate impact experiments on the (210), (100), and (111) planes were performed to examine the role of crystalline anisotropy on the shock-induced decomposition of cyclotrimethylenetrinitramine (RDX) crystals. Time-resolved emission spectroscopy was used to probe the decomposition of single crystals shocked to peak stresses ranging between 7 and 20 GPa. Emission produced by decomposition intermediates was analyzed in terms of induction time to emission, emission intensity, and the emission spectra shapes as a function of stress and time. Utilizing these features, we found that the shock-induced decomposition of RDX crystals exhibits considerable anisotropy. Crystals shocked on the (210) and (100) planes were more sensitive to decomposition than crystals shocked on the (111) plane. The possible sources of the observed anisotropy are discussed with regard to the inelastic deformation mechanisms of shocked RDX. Our results suggest that, despite the anisotropy observed for shock initiation, decomposition pathways for all three orientations are similar.

  12. Equation of state of laser-shocked compressed iron; Equation d'etat du fer comprime par choc laser

    Energy Technology Data Exchange (ETDEWEB)

    Huser, G

    2004-01-01

    This thesis enters the field of highly compressed materials equation of state studies. In particular, it focuses on the case of laser shock compressed iron. This work indeed aims at getting to the conditions of the earth's core, comprising a solid inner core and a liquid outer core. The understanding of phenomena governing the core's thermodynamics and the geodynamic process requires the knowledge of iron melting line locus around the solid-liquid interface at 3.3 Mbar. Several experiments were performed to that extent. First, an absolute measurement of iron Hugoniot was obtained. Following is a study of partially released states of iron into a window material: lithium fluoride (LiF). This configuration enables direct access to compressed iron optical properties such as reflectivity and self-emission. Interface velocity measurement is dominated by compressed LiF optical properties and is used as a pressure gauge. Using a dual wavelength reflectivity diagnostic, compressed iron electrical conductivity was estimated and found to be in good agreement with previous results found in geophysics literature. Self-emission diagnostic was used to measure temperature of partially released iron and revealed a solid-liquid phase transition at Mbar pressures. (author)

  13. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create opt

  14. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create

  15. Characterization Of High Explosives Detonations Via Laser-Induced Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Aleman, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    One objective of the Department of Energy’s National Security Administration is to develop technologies that can help the United States government to detect foreign nuclear weapons development activities. The realm of high explosive (HE) experiments is one of the key areas to assess the nuclear ambitions of a country. SRNL has participated in the collection of particulates from HE experiments and characterized the material with the purpose to correlate particulate matter with HE. Since these field campaigns are expensive, on-demand simulated laboratory-scale explosion experiments are needed to further our knowledge of the chemistry and particle formation in the process. Our goal is to develop an experimental test bed in the laboratory to test measurement concepts and correlate particle formation processes with the observables from the detonation fireball. The final objective is to use this knowledge to tailor our experimental setups in future field campaigns. The test bed uses pulsed laser-induced plasmas to simulate micro-explosions, with the intent to study the temporal behavior of the fireball observed in field tests. During FY15, a plan was prepared and executed which assembled two laser ablation systems, procured materials for study, and tested a Step-Scan Fourier Transform Infrared Spectrometer (SS-FTIR). Designs for a shadowgraph system for shock wave analysis, design for a micro-particulate collector from ablated pulse were accomplished. A novel spectroscopic system was conceived and a prototype system built for acquisition of spectral/temporal characterization of a high speed event such as from a high explosive detonation. Experiments and analyses will continue into FY16.

  16. Electron dropout echoes induced by interplanetary shock: Van Allen Probes observations

    Science.gov (United States)

    Hao, Y. X.; Zong, Q.-G.; Zhou, X.-Z.; Fu, S. Y.; Rankin, R.; Yuan, C.-J.; Lui, A. T. Y.; Spence, H. E.; Blake, J. B.; Baker, D. N.; Reeves, G. D.

    2016-06-01

    On 23 November 2012, a sudden dropout of the relativistic electron flux was observed after an interplanetary shock arrival. The dropout peaks at ˜1 MeV and more than 80% of the electrons disappeared from the drift shell. Van Allen twin Probes observed a sharp electron flux dropout with clear energy dispersion signals. The repeating flux dropout and recovery signatures, or "dropout echoes", constitute a new phenomenon referred to as a "drifting electron dropout" with a limited initial spatial range. The azimuthal range of the dropout is estimated to be on the duskside, from ˜1300 to 0100 LT. We conclude that the shock-induced electron dropout is not caused by the magnetopause shadowing. The dropout and consequent echoes suggest that the radial migration of relativistic electrons is induced by the strong dusk-dawn asymmetric interplanetary shock compression on the magnetosphere.

  17. Laser induced phase locking of hydrogen plasma striations

    Energy Technology Data Exchange (ETDEWEB)

    Glab, W.; Nayfeh, M.H.

    1982-04-01

    Laser induced transient striations of a hydrogen discharge plasma are studied as a function of the ''detuning'' of the discharge parameters from the steady-state oscillatory response conditions. We observed laser induced phase locking of the steady-state striations.

  18. Laser Induced Selective Activation For Subsequent Autocatalytic Electroless Plating

    DEFF Research Database (Denmark)

    Zhang, Yang

    The subject of this PhD thesis is “Laser induced selective activation for subsequent autocatalytic electroless plating.” The objective of the project is to investigate the process chains for micro structuring of polymer surfaces for selective micro metallization. Laser induced selective activation...

  19. Effect of initial perturbation amplitude on Richtmyer-Meshkov flows induced by strong shocks

    Energy Technology Data Exchange (ETDEWEB)

    Dell, Z.; Abarzhi, S. I., E-mail: snezhana.abarzhi@gmail.com, E-mail: sabarji@andrew.cmu.edu [Mellon College of Science and Carnegie Mellon University – Qatar, Carnegie Mellon University, Pittsburgh, Pennsylvania 15231 (United States); Stellingwerf, R. F. [Stellingwerf Consulting, Huntsville, Alabama 35803 (United States)

    2015-09-15

    We systematically study the effect of the initial perturbation on Richtmyer-Meshkov (RM) flows induced by strong shocks in fluids with contrasting densities. Smooth Particle Hydrodynamics simulations are employed. A broad range of shock strengths and density ratios is considered. The amplitude of the initial single mode sinusoidal perturbation of the interface varies from 0% to 100% of its wavelength. The simulations results are compared, wherever possible, with four rigorous theories, and with other experiments and simulations, achieving good quantitative and qualitative agreement. Our study is focused on early time dynamics of the Richtmyer-Meshkov instability (RMI). We analyze the initial growth-rate of RMI immediately after the shock passage, when the perturbation amplitude increases linearly with time. For the first time, to the authors' knowledge, we find that the initial growth-rate of RMI is a non-monotone function of the initial perturbation amplitude, thus restraining the amount of energy that can be deposited by the shock at the interface. The maximum value of the initial growth-rate depends on the shock strength and the density ratio, whereas the corresponding value of the initial perturbation amplitude depends only slightly on the shock strength and density ratio.

  20. Development of a Heat-Shock Inducible Gene Expression System in the Red Alga Cyanidioschyzon merolae

    Science.gov (United States)

    Sumiya, Nobuko; Fujiwara, Takayuki; Kobayashi, Yusuke; Misumi, Osami; Miyagishima, Shin-ya

    2014-01-01

    The cell of the unicellular red alga Cyanidioschyzon merolae contains a single chloroplast and mitochondrion, the division of which is tightly synchronized by a light/dark cycle. The genome content is extremely simple, with a low level of genetic redundancy, in photosynthetic eukaryotes. In addition, transient transformation and stable transformation by homologous recombination have been reported. However, for molecular genetic analyses of phenomena that are essential for cellular growth and survival, inducible gene expression/suppression systems are needed. Here, we report the development of a heat-shock inducible gene expression system in C. merolae. CMJ101C, encoding a small heat shock protein, is transcribed only when cells are exposed to an elevated temperature. Using a superfolder GFP as a reporter protein, the 200-bp upstream region of CMJ101C orf was determined to be the optimal promoter for heat-shock induction. The optimal temperature to induce expression is 50°C, at which C. merolae cells are able to proliferate. At least a 30-min heat shock is required for the expression of a protein of interest and a 60-min heat shock yields the maximum level of protein expression. After the heat shock, the mRNA level decreases rapidly. As an example of the system, the expression of a dominant negative form of chloroplast division DRP5B protein, which has a mutation in the GTPase domain, was induced. Expression of the dominant negative DRP5B resulted in the appearance of aberrant-shaped cells in which two daughter chloroplasts and the cells are still connected by a small DRP5B positive tube-like structure. This result suggests that the dominant negative DRP5B inhibited the final scission of the chloroplast division site, but not the earlier stages of division site constriction. It is also suggested that cell cycle progression is not arrested by the impairment of chloroplast division at the final stage. PMID:25337786

  1. Laser-induced damage of 1064-nm narrow-band interference filters under different laser modes

    Institute of Scientific and Technical Information of China (English)

    Weidong Gao(高卫东); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)

    2004-01-01

    The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode.The absorption measurement of such coatings has been performed by surface thermal lensing(STL)technique.The relationship between damage morphology and absorption under the two different laser modes was studied in detail.The explanation was given by the standing-wave distribution theory.

  2. Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon

    Science.gov (United States)

    Vaisseau, X.; Morace, A.; Touati, M.; Nakatsutsumi, M.; Baton, S. D.; Hulin, S.; Nicolaï, Ph.; Nuter, R.; Batani, D.; Beg, F. N.; Breil, J.; Fedosejevs, R.; Feugeas, J.-L.; Forestier-Colleoni, P.; Fourment, C.; Fujioka, S.; Giuffrida, L.; Kerr, S.; McLean, H. S.; Sawada, H.; Tikhonchuk, V. T.; Santos, J. J.

    2017-05-01

    Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism—observed only for times before the shock breakout at the inner cone tip—is due to self-generated resistive magnetic fields of ˜0.5 - 1 kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

  3. Generation of laser plasma bunches with a high efficiency of energy concentration for laboratory simulation of collisionless shock waves in magnetised cosmic plasma

    Science.gov (United States)

    Zakharov, Yu P.; Ponomarenko, A. G.; Tishchenko, V. N.; Antonov, V. M.; Melekhov, A. V.; Posukh, V. G.; Prokopov, P. A.; Terekhin, V. A.

    2016-05-01

    We present the results of first experiments on the formation of collisionless shock waves (CSWs) in background plasma by injecting laser plasma bunches transverse to the magnetic field (as a piston) with a maximum energy up to 100 J per unit of solid angle and with a high enough degree of ion magnetisation. With this aim in view, on a unique KI-1 facility at the Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences (ILP), a plastic (polyethylene) target irradiated by a CO2 laser in the most energy-efficient regime (near the plasma formation threshold) and a highly ionised hydrogen plasma with a high concentration in a large volume (not less than 1 m3) have been employed. As a result of model experiments performed on the basis of a model of collisionless interaction of plasma flows, developed at the VNIIEF and being adequate to the problem under consideration, not only an intensive, background-induced, deceleration of a super-Alfven laser plasma flow, but also the formation in that flow of a strong perturbation having the properties of a subcritical CSW and propagating transverse to the magnetic field, have been first registered in the laboratory conditions.

  4. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2013-05-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  5. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2012-11-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon-oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by acids generated by the photo-ionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  6. Irradiation uniformity at the Laser MegaJoule facility in the context of the shock ignition scheme

    Institute of Scientific and Technical Information of China (English)

    Mauro; Temporal; Benoit; Canaud; Warren; J.; Garbett; Rafael; Ramis; Stefan; Weber

    2014-01-01

    The use of the Laser MegaJoule facility within the shock ignition scheme has been considered. In the first part of the study, one-dimensional hydrodynamic calculations were performed for an inertial confinement fusion capsule in the context of the shock ignition scheme providing the energy gain and an estimation of the increase of the peak power due to the reduction of the photon penetration expected during the high-intensity spike pulse. In the second part, we considered a Laser MegaJoule configuration consisting of 176 laser beams that have been grouped providing two different irradiation schemes. In this configuration the maximum available energy and power are 1.3 MJ and 440 TW. Optimization of the laser–capsule parameters that minimize the irradiation non-uniformity during the first few ns of the foot pulse has been performed. The calculations take into account the specific elliptical laser intensity profile provided at the Laser MegaJoule and the expected beam uncertainties. A significant improvement of the illumination uniformity provided by the polar direct drive technique has been demonstrated. Three-dimensional hydrodynamic calculations have been performed in order to analyse the magnitude of the azimuthal component of the irradiation that is neglected in twodimensional hydrodynamic simulations.

  7. Design of a shock-induced combustion experiment in an axisymmetric configuration with hydrogen injection

    NARCIS (Netherlands)

    Verreault, J.; DeChamplain, A.; Mayer, A.E.H.J.; Veraar, R.G.; Stowe, R.A.; Farinaccio, R.; Harris, P.G.

    2007-01-01

    This work presents a design for a shock-induced combustion experiment using a two-angle cone configuration. Three injector geometries were considered: a cone surface, a dual stage configuration with rectangular gaps (DSRG) and a cylindrical ramp (CR). Four parameters were investigated: the

  8. Design of a shock-induced combustion experiment in an axisymmetric configuration with hydrogen injection

    NARCIS (Netherlands)

    Verreault, J.; DeChamplain, A.; Mayer, A.E.H.J.; Veraar, R.G.; Stowe, R.A.; Farinaccio, R.; Harris, P.G.

    2007-01-01

    This work presents a design for a shock-induced combustion experiment using a two-angle cone configuration. Three injector geometries were considered: a cone surface, a dual stage configuration with rectangular gaps (DSRG) and a cylindrical ramp (CR). Four parameters were investigated: the penetrati

  9. Hypovolemic shock following induced abortion and spontaneous heterotopic pregnancy

    Directory of Open Access Journals (Sweden)

    Abdolghader Pakniyat

    2015-01-01

    Full Text Available Spontaneous heterotopic pregnancy is a rare clinical condition in which intrauterine and extrauterine pregnancies occur at the same time. It is rare, estimated to occur in 1 in 30,000 pregnancies. The case was a 38-year-old woman with spontaneously conceived heterotopic pregnancy. She was admitted to our center with hypovolemic shock. Focused assessment sonography for trauma examination in emergency department showed large amount of free fluid in peritoneal cavity. She was managed surgical laparotomy. Considering spontaneous pregnancies, physician should be aware of the possibility of heterotopic pregnancy in all reproductive age women, especially those with history of recent abortion. It can occur without any predisposing risk factors. Patients should be informed about possible side effects of nonprescription medicines, and also the health care centers must be safe peaceful environment for them without severe legal consequences.

  10. Shock induced by spontaneous rupture of a giant thymoma.

    Science.gov (United States)

    Santoprete, Stefano; Ragusa, Mark; Urbani, Moira; Puma, Francesco

    2007-04-01

    Spontaneous bleeding of thymoma is a very rare event. We report the case of a 73-year-old woman who was referred to our hospital for acute onset of chest pain followed by shock. Chest computed tomographic scanning showed a huge mediastinal tumor with abundant left pleural effusion and contralateral shift of the mediastinum. Emergency surgical treatment was carried out through a clamshell incision. At the opening of the left pleura 1,600 mL of fresh blood was found, originating from a rupture of the tumor's capsular veins. The lesion was completely resected, en-bloc with a wide pericardial excision. The postoperative course was uneventful. The pathology report classified the lesion as thymoma AB.

  11. Hypovolemic shock following induced abortion and spontaneous heterotopic pregnancy.

    Science.gov (United States)

    Pakniyat, Abdolghader; Yazdanbakhsh, Arash; Moshar-Mowahed, Ghasem; Talebi, Fatimah

    2015-12-01

    Spontaneous heterotopic pregnancy is a rare clinical condition in which intrauterine and extrauterine pregnancies occur at the same time. It is rare, estimated to occur in 1 in 30,000 pregnancies. The case was a 38-year-old woman with spontaneously conceived heterotopic pregnancy. She was admitted to our center with hypovolemic shock. Focused assessment sonography for trauma examination in emergency department showed large amount of free fluid in peritoneal cavity. She was managed surgical laparotomy. Considering spontaneous pregnancies, physician should be aware of the possibility of heterotopic pregnancy in all reproductive age women, especially those with history of recent abortion. It can occur without any predisposing risk factors. Patients should be informed about possible side effects of nonprescription medicines, and also the health care centers must be safe peaceful environment for them without severe legal consequences.

  12. Numerical Analysis of Shock Induced Separation Delay by Air Humidity

    Institute of Scientific and Technical Information of China (English)

    Piotr DOERFFER; Slawomir DYKAS

    2005-01-01

    @@ In this paper numerical calculations of the dry and humid air flows in the nozzle are presented. The dry air flow (adiabatic flow) and the humid air flow (flow with homogeneous condensation, diabatic flow) are modeled with the use of Reynolds Averaged Navier-Stokes (RANS) equations. The comparison of these two types of flow is carried out. The influence of the air humidity on the shock wave location and its interaction with the boundary layer is examined. Obtained numerical results present a first numerical approach of the condensation and evaporation process in transonic flow of humid air. The phenomena considered here are very complex and complicated and need further in-depth numerical analysis.

  13. Hyperkalemia induced pseudo-myocardial infarction in septic shock

    Directory of Open Access Journals (Sweden)

    S E Pothiawala

    2014-01-01

    Full Text Available Hyperkalemia is an acute life-threatening disorder presenting to the emergency department. Patients with hyperkalemia may manifest characteristic electrocardiographic changes including tented T waves, widening of the QRS complex and loss of P waves, sine wave pattern and eventually asystole. There have been only few reports of hyperkalemia causing ST segment elevation on electrocardiogram simulating an acute myocardial infarction. This case describes pseudo-myocardial infarction due to hyperkalemia and septic shock. Rapid determination of serum potassium levels by bedside blood gas analyzers serves to be a useful guide. ST segment elevation related to hyperkalemia will resolve with successful reduction of the serum potassium levels by appropriate therapy. It is important for physicians to be aware of this condition as this will aid in initiating correct therapy and prevent the patient from unnecessary interventions and the associated risk of complications.

  14. Estimate of the maximum induced magnetic field in relativistic shocks

    Science.gov (United States)

    Ghorbanalilu, M.; Sadegzadeh, S.

    2017-01-01

    The proton-driven Weibel instability is a crucial process for amplifying the generated magnetic fields in gamma-ray bursts. An expression for the saturation level of magnetic fields is estimated in a relativistic shock consisting of electron-proton plasmas. Within the shock transition layer, the plasma is modelled with the waterbag and Maxwell-Jüttner distribution functions for asymmetric counter-propagating proton beams and isotropic background electrons, respectively. The proton-driven Weibel-type instability in the linear phase is investigated thoroughly and then the instability conditions and the stabilization mechanisms are considered in details just after the shutdown of the electron Weibel instability. The growth rate of the instability and the saturated magnetic field strength are obtained in terms of the effective proton beam Mach number, asymmetry parameter, and the background electron temperature. In this paper, fully relativistic kinetic treatment is used to formulate the dispersion relation for the proton Weibel-type instability. Then, by using the magnetic trapping criteria, the saturated magnetic field strength is computed. In the present scenario, the instability includes two stages: in the first stage the electron Weibel instability evolves very rapidly, but in the second one because of the free energy stored in the slow counter-propagating proton beams, the instability is further amplified in the context of electrons with an isotropic distribution function. Increment of the growth rate and saturated magnetic field by increasing (decreasing) the effective proton beam Mach number (the asymmetry parameter) is deduced from the results. It is shown that at the temperatures around 108 K a maximum magnetic field up to around 56 G can be detected by this mechanism after the saturation time.

  15. Effect of native defects and laser-induced defects on multi-shot laser-induced damage in multilayer mirrors

    Institute of Scientific and Technical Information of China (English)

    Ying Wang; Yuanan Zhao; Tanda Shao; Zhengxiu Fan

    2011-01-01

    The roles of laser-induced defects and native defects in multilayer mirrors under multi-shot irradiation condition are investigated. The HfO2/SiO2 dielectric mirrors are deposited by electron beam evaporation (EBE). Laser damage testing is carried out on both the 1-on-l and S-on-1 regimes using 355-nm pulsed laser at a duration of 8 ns. It is found that the single-shot laser-induced damage threshold (LIDT) is much higher than the multi-shot LIDT. In the multi-shot mode, the main factor influencing LIDT is the accumulation of irreversible laser-induced defects and native defects. The surface morphologies of the samples are observed by optical microscopy. Moreover, the number of laser-induced defects affects the damage probability of the samples. A correlative model based on critical conduction band (CB) electron density (ED) is presented to simulate the multi-shot damage behavior.%@@ The roles of laser-induced defects and native defects in multilayer mirrors under multi-shot irradiation condition are investigated.The Hf02/SiO2 dielectric mirrors are deposited by electron beam evaporation (EBE).Laser damage testing is carried out on both the 1-on-1 and S-on-1 regimes using 355-nn pulsed laser at a duration of 8 us.It is found that the single-shot laser-induced damage threshold(LIDT)is much higher than the multi-shot LIDT.In the multi-shot mode,the main factor influencing LIDT is the accumulation of irreversible laser-induced defects and native defects.The surface morphologies of the samples are observed by optical microscopy.Moreover,the number of laser-induced defects affects the damage probability of the samples.A correlative model based on critical conduction band(CB)electron density(ED)is presented to simulate the multi-shot damage behavior.

  16. Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target

    Energy Technology Data Exchange (ETDEWEB)

    Pisarczyk, T.; Kalinowska, Z.; Badziak, J.; Borodziuk, S.; Chodukowski, T.; Kasperczuk, A.; Parys, P.; Rosinski, M. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Gus' kov, S. Yu.; Demchenko, N. N. [P.N. Lebedev Physical Institute of RAS, 53 Leninsky Ave., 119 991 Moscow (Russian Federation); Batani, D.; Antonelli, L.; Folpini, G.; Maheut, Y. [Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, Talence (France); Baffigi, F.; Cristoforetti, G.; Gizzi, L. A.; Koester, P.; Labate, L. [Intense Laser Irradiation Laboratory at INO-CNR, Pisa (Italy); Krousky, E. [Institute of Plasma Physics ASCR, v.v.i., ZaSlovankou 3, 182 00 Prague 8 (Czech Republic); and others

    2014-01-15

    Efficiency of the laser radiation energy transport into the shock wave generated in layered planar targets (consisting of massive Cu over coated by thin CH layer) was investigated. The targets were irradiated using two laser pulses. The 1ω pulse with the energy of ∼50 J produced a pre-plasma, imitating the corona of the pre-compressed inertial confinement fusion target. The second main pulse used the 1ω or 3ω laser harmonics with the energy of ∼200 J. The influence of the pre-plasma on parameters of the shock wave was determined from the crater volume measurements and from the electron density distribution measured by 3-frame interferometry. The experimental results show that the energy transport by fast electrons provides a definite contribution to the dynamics of the ablative process, to the shock wave generation, and to the ablation pressure in dependence on the target irradiation conditions. The strong influence of the pre-plasma on the investigated process was observed in the 1ω case. Theoretical analysis supports the explanation of experimental results.

  17. Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target

    Science.gov (United States)

    Pisarczyk, T.; Gus'kov, S. Yu.; Kalinowska, Z.; Badziak, J.; Batani, D.; Antonelli, L.; Folpini, G.; Maheut, Y.; Baffigi, F.; Borodziuk, S.; Chodukowski, T.; Cristoforetti, G.; Demchenko, N. N.; Gizzi, L. A.; Kasperczuk, A.; Koester, P.; Krousky, E.; Labate, L.; Parys, P.; Pfeifer, M.; Renner, O.; Smid, M.; Rosinski, M.; Skala, J.; Dudzak, R.; Ullschmied, J.; Pisarczyk, P.

    2014-01-01

    Efficiency of the laser radiation energy transport into the shock wave generated in layered planar targets (consisting of massive Cu over coated by thin CH layer) was investigated. The targets were irradiated using two laser pulses. The 1ω pulse with the energy of ˜50 J produced a pre-plasma, imitating the corona of the pre-compressed inertial confinement fusion target. The second main pulse used the 1ω or 3ω laser harmonics with the energy of ˜200 J. The influence of the pre-plasma on parameters of the shock wave was determined from the crater volume measurements and from the electron density distribution measured by 3-frame interferometry. The experimental results show that the energy transport by fast electrons provides a definite contribution to the dynamics of the ablative process, to the shock wave generation, and to the ablation pressure in dependence on the target irradiation conditions. The strong influence of the pre-plasma on the investigated process was observed in the 1ω case. Theoretical analysis supports the explanation of experimental results.

  18. Laser-induced periodic surface structuring of biopolymers

    Science.gov (United States)

    Pérez, Susana; Rebollar, Esther; Oujja, Mohamed; Martín, Margarita; Castillejo, Marta

    2013-03-01

    We report here on a systematic study about the formation of laser-induced periodic surface structures (LIPSS) on biopolymers. Self-standing films of the biopolymers chitosan, starch and the blend of chitosan with the synthetic polymer poly (vinyl pyrrolidone), PVP, were irradiated in air with linearly polarized laser beams at 193, 213 and 266 nm, with pulse durations in the range of 6-17 ns. The laser-induced periodic surface structures were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via Raman spectroscopy. Formation of LIPSS parallel to the laser polarization direction, with periods similar to the laser wavelength, was observed at efficiently absorbed wavelengths in the case of the amorphous biopolymer chitosan and its blend with PVP, while formation of LIPSS is prevented in the crystalline starch biopolymer.

  19. Visualizing electromagnetic fields in laser-produced counter-streaming plasma experiments for collisionless shock laboratory astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Kugland, N. L.; Ross, J. S.; Glenzer, S. H.; Huntington, C.; Martinez, D.; Plechaty, C.; Remington, B. A.; Ryutov, D. D.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Chang, P.-Y.; Fiksel, G.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14636 (United States); Drake, R. P.; Grosskopf, M.; Kuranz, C. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Gregori, G.; Meinecke, J.; Reville, B. [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Koenig, M.; Pelka, A. [Laboratoire pour l' Utilisation des Lasers Intenses (LULI), École Polytechnique-Univ, Paris VI, 91128 Palaiseau (France); and others

    2013-05-15

    Collisionless shocks are often observed in fast-moving astrophysical plasmas, formed by non-classical viscosity that is believed to originate from collective electromagnetic fields driven by kinetic plasma instabilities. However, the development of small-scale plasma processes into large-scale structures, such as a collisionless shock, is not well understood. It is also unknown to what extent collisionless shocks contain macroscopic fields with a long coherence length. For these reasons, it is valuable to explore collisionless shock formation, including the growth and self-organization of fields, in laboratory plasmas. The experimental results presented here show at a glance with proton imaging how macroscopic fields can emerge from a system of supersonic counter-streaming plasmas produced at the OMEGA EP laser. Interpretation of these results, plans for additional measurements, and the difficulty of achieving truly collisionless conditions are discussed. Future experiments at the National Ignition Facility are expected to create fully formed collisionless shocks in plasmas with no pre-imposed magnetic field.

  20. Molecular dissociation and shock-induced cooling in fluid nitrogen at high densities and temperatures

    Science.gov (United States)

    Radousky, H. B.; Nellis, W. J.; Ross, M.; Hamilton, D. C.; Mitchell, A. C.

    1986-01-01

    Radiative temperatures and electrical conductivities were measured for fluid nitrogen compressed dynamically to pressures of 18-90 GPa, temperatures of 4000-14,000 K, and densities of 2-3 g/cu cm. The data show a continuous phase transition above 30 GPa shock pressure and confirm that (delta-P/delta-T)v is less than 0, as indicated previously by Hugoniot equation-of-state experiments. The first observation of shock-induced cooling is also reported. The data are interpreted in terms of molecular dissociation, and the concentration of dissociated molecules is calculated as a function of density and temperature.

  1. Use of hot-wire anemometry for turbulence measurements in shock induced flows

    Science.gov (United States)

    Hartung, L. C.; Duffy, R. E.; Troller, J. W.

    1986-01-01

    A research program is currently being conducted with the aim to investigate the operating environment of future gas turbines. The present paper provides a description of the experimental methods which have been employed in performing turbulence intensity measurements in shock-induced flows. In a discussion of the instrumentation, attention is given to the employed low pressure shock tube, the hot-wire probe, the anemometer, the test facility, the experimental setup, the Kistler pressure transducer, and silicon piezoresistive gages. Aspects of instrumentation calibration are considered along with data corrections, experimental data, and data processing.

  2. Hydrodynamic Flow and Jet Induced Mach Shocks at RHIC and LHC

    CERN Document Server

    Stöcker, H; Rau, P; Betz, Barbara; Rau, Philip; St\\"ocker, Horst

    2007-01-01

    We discuss the present collective flow signals for the phase transition to quark-gluon plasma (QGP) and the collective flow as a barometer for the equation of state (EoS). A study of Mach shocks induced by fast partonic jets propagating through the QGP is given. We predict a significant deformation of Mach shocks in central Au+Au collisions at RHIC and LHC energies as compared to the case of jet propagation in a static medium. Results of a hydrodynamical study of jet energy loss are presented.

  3. Generation of scaled protogalactic seed magnetic fields in laser-produced shock waves

    Science.gov (United States)

    Gregori, G.; Ravasio, A.; Murphy, C. D.; Schaar, K.; Baird, A.; Bell, A. R.; Benuzzi-Mounaix, A.; Bingham, R.; Constantin, C.; Drake, R. P.; Edwards, M.; Everson, E. T.; Gregory, C. D.; Kuramitsu, Y.; Lau, W.; Mithen, J.; Niemann, C.; Park, H.-S.; Remington, B. A.; Reville, B.; Robinson, A. P. L.; Ryutov, D. D.; Sakawa, Y.; Yang, S.; Woolsey, N. C.; Koenig, M.; Miniati, F.

    2012-01-01

    The standard model for the origin of galactic magnetic fields is through the amplification of seed fields via dynamo or turbulent processes to the level consistent with present observations. Although other mechanisms may also operate, currents from misaligned pressure and temperature gradients (the Biermann battery process) inevitably accompany the formation of galaxies in the absence of a primordial field. Driven by geometrical asymmetries in shocks associated with the collapse of protogalactic structures, the Biermann battery is believed to generate tiny seed fields to a level of about 10-21 gauss (refs 7, 8). With the advent of high-power laser systems in the past two decades, a new area of research has opened in which, using simple scaling relations, astrophysical environments can effectively be reproduced in the laboratory. Here we report the results of an experiment that produced seed magnetic fields by the Biermann battery effect. We show that these results can be scaled to the intergalactic medium, where turbulence, acting on timescales of around 700 million years, can amplify the seed fields sufficiently to affect galaxy evolution.

  4. Role of spall in microstructure evolution during laser-shock-driven rapid undercooling and resolidification

    Science.gov (United States)

    Colvin, Jeffrey D.; Jankowski, Alan F.; Kumar, Mukul; MoberlyChan, Warren J.; Reed, Bryan W.; Paisley, Dennis L.; Tierney, Thomas E.

    2009-01-01

    We previously reported [Colvin et al., J. Appl. Phys. 101, 084906 (2007)] on the microstructure morphology of pure Bi metal subjected to rapid laser-shock-driven melting and subsequent resolidification upon release of pressure, where the estimated effective undercooling rates were of the order of 109-1010 K/s. More recently, we repeated these experiments, but with a Bi/Zn alloy (Zn atomic fraction of 2%-4%) instead of elemental Bi and with a change in target design to suppress spall in the Bi/Zn samples. We observed a similar microstructure morphology in the two sets of experiments, with initially columnar grains recrystallizing to larger equiaxed grains. The Bi samples, however, exhibited micron-scale dendrites on the spall surfaces, whereas there were no dendritic structures anywhere in the nonspalled Bi/Zn, even down to the nanometer scale as observed by transmission electron microscopy. We present the simulations and the interferometry data that show that the samples in the two sets of experiments followed nearly identical hydrodynamic and thermodynamic paths apart from the presence of (probably partially liquid) spall in pure Bi. Simulations also show that the spall occurs right at the moving phase front and, hence, the spall itself cuts off the principal direction for latent heat dissipation across the phase boundary. We suggest that it is the liquid spall itself that creates the conditions for dendrite formation.

  5. Laser plasma simulations of the generation processes of Alfven and collisionless shock waves in space plasma

    Science.gov (United States)

    Prokopov, P. A.; Zakharov, Yu P.; Tishchenko, V. N.; Shaikhislamov, I. F.; Boyarintsev, E. L.; Melekhov, A. V.; Ponomarenko, A. G.; Posukh, V. G.; Terekhin, V. A.

    2016-11-01

    Generation of Alfven waves propagating along external magnetic field B0 and Collisionless Shock Waves propagating across B0 are studied in experiments with laser- produced plasma and magnetized background plasma. The collisionless interaction of interpenetrating plasma flows takes place through a so-called Magnetic Laminar Mechanism (MLM) or Larmor Coupling. At the edge of diamagnetic cavity LP-ions produce induction electric field Eφ which accelerates BP-ions while LP-ions rotate in opposite direction. The ions movement generates sheared azimuthal magnetic field Bφ which could launches torsional Alfven wave. In previous experiments at KI-1 large scale facility a generation of strong perturbations propagating across B0 with magnetosonic speed has been studied at a moderate value of interaction parameter δ∼0.3. In the present work we report on experiments at conditions of 5∼R2 and large Alfven-Mach number MA∼10 in which strong transverse perturbations traveling at a scale of ∼1 m in background plasma at a density of ∼3*1013 cm-3 is observed. At the same conditions but smaller MA ∼ 2 a generation, the structure and dynamic of Alfven wave with wavelength ∼0.5 m propagating along fields B0∼100÷500 G for a distance of ∼2.5 m is studied.

  6. Intranasal Rapamycin Rescues Mice from Staphylococcal Enterotoxin B-Induced Shock

    Directory of Open Access Journals (Sweden)

    Teresa Krakauer

    2012-09-01

    Full Text Available Staphylococcal enterotoxin B (SEB and related exotoxins produced by Staphylococcus aureus are potent activators of the immune system and cause toxic shock in humans. Currently there is no effective treatment except for the use of intravenous immunoglobulins administered shortly after SEB exposure. Intranasal SEB induces long-lasting lung injury which requires prolonged drug treatment. We investigated the effects of rapamycin, an immunosuppressive drug used to prevent graft rejection, by intranasal administration in a lethal mouse model of SEB-induced shock. The results show that intranasal rapamycin alone delivered as late as 17 h after SEB protected 100% of mice from lethal shock. Additionally, rapamycin diminished the weight loss and temperature fluctuations elicited by SEB. Intranasal rapamycin attenuated lung MCP-1, IL-2, IL-6, and IFNγ by 70%, 30%, 64%, and 68% respectively. Furthermore, short courses (three doses of rapamycin were sufficient to block SEB-induced shock. Intranasal rapamycin represents a novel use of an immunosuppressant targeting directly to site of toxin exposure, reducing dosages needed and allowing a wider therapeutic window.

  7. Shock induced ignition and DDT in the presence of mechanically driven fluctuations

    Science.gov (United States)

    Wang, Wentian; McDonald, James G.; Radulescu, Matei I.

    2015-11-01

    The present study addresses the problem of shock induced ignition and transition to detonation in the presence of mechanical and thermal fluctuations. These departures from a homogeneous medium are of significant importance in practical situations, where such fluctuations may promote hot-spot ignition and favor the flame transition to detonation. The problem is studied in 1D, where a piston-induced shock ignites the gas. The fluctuations in the shock-compressed medium are controlled by allowing the piston's speed to oscillate around a mean, with controllable frequency and amplitude. A Lagrangian numerical formulation is used, which allows to treat exactly the transient boundary condition at the piston head. The hydrodynamic solver is coupled with the reactive dynamics of the gas using Cantera. The code was verified by comparison with steady state ZND solutions and previous shock induced ignition results in homogeneous media. Results obtained for different fuels illustrate the strong relation of the DDT amplification length to mechanical fluctuations in systems with a high effective activation energy and fast rate of energy deposition, consistent with experiments performed on fast flame acceleration in the presence of strong mechanical perturbations. Financial support from NSERC and Shell, with A. Pekalski and M. Levin as technical monitors, are greatly acknowledged.

  8. Investigation on femto-second laser irradiation assisted shock peening of medium carbon (0.4% C) steel

    Science.gov (United States)

    Majumdar, Jyotsna Dutta; Gurevich, Evgeny L.; Kumari, Renu; Ostendorf, Andreas

    2016-02-01

    In the present study, the effect of femtosecond laser irradiation on the peening behavior of 0.4% C steel has been evaluated. Laser irradiation has been conducted with a 100 μJ and 300 fs laser with multiple pulses under varied energy. Followed by laser irradiation, a detailed characterization of the processed zone was undertaken by scanning electron microscopy, and X-ray diffraction technique. Finally, the residual stress distribution, microhardness and wear resistance properties of the processed zone were also evaluated. Laser processing leads to shock peening associated with plasma formation and its expansion, formation of martensite and ferrito-pearlitic phase in the microstructure. Due to laser processing, there is introduction of residual stress on the surface which varies from high tensile (140 MPa) to compressive (-335 MPa) as compared to 152 MPa of the substrate. There is a significant increase in microhardness to 350-500 VHN as compared to 250 VHN of substrate. The fretting wear behavior against hardened steel ball shows a significant reduction in wear depth due to laser processing. Finally, a conclusion of the mechanism of wear has been established.

  9. Survival of fossils under extreme shocks induced by hypervelocity impacts.

    Science.gov (United States)

    Burchell, M J; McDermott, K H; Price, M C; Yolland, L J

    2014-08-28

    Experimental data are shown for survival of fossilized diatoms undergoing shocks in the GPa range. The results were obtained from hypervelocity impact experiments which fired fossilized diatoms frozen in ice into water targets. After the shots, the material recovered from the target water was inspected for diatom fossils. Nine shots were carried out, at speeds from 0.388 to 5.34 km s(-1), corresponding to mean peak pressures of 0.2-19 GPa. In all cases, fragmented fossilized diatoms were recovered, but both the mean and the maximum fragment size decreased with increasing impact speed and hence peak pressure. Examples of intact diatoms were found after the impacts, even in some of the higher speed shots, but their frequency and size decreased significantly at the higher speeds. This is the first demonstration that fossils can survive and be transferred from projectile to target in hypervelocity impacts, implying that it is possible that, as suggested by other authors, terrestrial rocks ejected from the Earth by giant impacts from space, and which then strike the Moon, may successfully transfer terrestrial fossils to the Moon.

  10. Bezafibrate-induced anaphylactic shock: unusual clinical presentation.

    Science.gov (United States)

    de Barrio, M; Matheu, V; Baeza, M L; Tornero, P; Rubio, M; Zubeldia, J M

    2001-01-01

    We report a case of a patient who suffered generalized urticaria, chest tightness, wheezing, nausea, vomiting, hypotension, and loss of consciousness. Two hours earlier she had taken Eulitop Retard following lunch. She had tolerated all the implicated food after the reaction. Allergy evaluation revealed intense positive responses to intradermal tests with bezafibrate active component and Eulitop Retard (skin tests in control subjects were negative). Specific IgE tests (RAST) to Eulitop Retard were negative. An IgE mechanism is suggested to be responsible for this adverse reaction on the basis of the positive skin tets. The delayed onset (two hours) of this anaphylactic shock is unusual. Although infrequent, it may be caused by the specific pharmacokinetic characteristics of this drug, which is a slow releasing agent, mainly absorbed in the gut. The drug was taken just after lunch, and this concomitant food ingestion could also have produced a delay in gastric drainage and a retarded drug absorption. An IgE-mediated accelerated type reaction could also explain this delay. Apparently the patient reacted after the first contact to the drug, and the absence of a sensitization period is not usual in this type of immune reponse. Finally, we recommend the performance of prick and intradermal skin tests prior to any systemic challenge when allergic reactions to fibric acid derivatives are suspected.

  11. Numerical Study on the Suppression of Shock Induced Separation on the Non Adisbatic Wall

    Institute of Scientific and Technical Information of China (English)

    Doug-DongLEE

    2000-01-01

    A numerical model is constructued to simulate the interaction of supersonic(M=2.4) oblique shock wave/turbulent boundary layer on s trongly heated wall.The heated wall temperature is two times higher than the adiabatic wall temperature and the shock wave is strong enough to induce boundary layer sepqration.The turbulence model is Splanrt-Allmaras model.The comparison of the wall pressure distribution with the experimental data ensures the validity of this numerical model.The effect of strong wall heating enlarges the separation region upstream and downstream.In order to eliminate the separation.wall bleeding is appled at the shock foot position.As a result of the parametric study,the best position of the bleeding slot is selected.The position of the bleeding is very important for the separation suppression.If the bleeding is applied upstream of shock foot,then separation reoccurs after the bleeding slot.If the bleeding is applied downstream of shock foot,the upstream boundary layer is little influenced and still separated.The bleeding vent width is about same as the upstream boundary layer thickness and suction mass flow in 20 to 80% of the flow rate in the upstream boundary layer.The bleeding mass flow rate is very sensitive to the bleeding vent position if we fix the vent outlet pressure.The final configuration of the shock reflection pattern approaches to the non-viscous value when wall bleeding is applied at the shock impinging point.

  12. Improvement in Hemodynamics After Methylene Blue Administration in Drug-Induced Vasodilatory Shock: A Case Report.

    Science.gov (United States)

    Laes, JoAn R; Williams, David M; Cole, Jon B

    2015-12-01

    The purpose of this study is to describe a case where methylene blue improved hemodynamics in a poisoned patient. This is a single case report where a poisoned patient developed vasodilatory shock following ingestion of atenolol, amlodipine, and valsartan. Shock persisted after multiple therapies including vasopressors, high-dose insulin, hemodialysis, and 20% intravenous fat emulsion. Methylene blue (2 mg/kg IV over 30 min) was administered in the ICU with temporal improvement as measured by pulmonary artery catheter hemodynamic data pre- and post-methylene blue administration. Within 1 h of methylene blue administration, systemic vascular resistance improved (240 dyn s/cm5 increased to 1204 dyn s/cm5), and vasopressor requirements decreased with maintenance of mean arterial pressure 60 mmHg. Methylene blue may improve hemodynamics in drug-induced vasodilatory shock and should be considered in critically ill patients poisoned with vasodilatory medications refractory to standard therapies.

  13. Well-posed Euler model of shock-induced two-phase flow in bubbly liquid

    Science.gov (United States)

    Tukhvatullina, R. R.; Frolov, S. M.

    2017-07-01

    A well-posed mathematical model of non-isothermal two-phase two-velocity flow of bubbly liquid is proposed. The model is based on the two-phase Euler equations with the introduction of an additional pressure at the gas bubble surface, which ensures the well-posedness of the Cauchy problem for a system of governing equations with homogeneous initial conditions, and the Rayleigh-Plesset equation for radial pulsations of gas bubbles. The applicability conditions of the model are formulated. The model is validated by comparing one-dimensional calculations of shock wave propagation in liquids with gas bubbles with a gas volume fraction of 0.005-0.3 with experimental data. The model is shown to provide satisfactory results for the shock propagation velocity, pressure profiles, and the shock-induced motion of the bubbly liquid column.

  14. An investigation of passive control methods for shock-induced separation at hypersonic speeds

    Science.gov (United States)

    Rallo, R.; Walsh, M.; Van Leer, Bram

    1992-01-01

    The effectiveness of several passive control techniques on shock-induced boundary-layer separation at hypersonic speed was investigated. Two approaches for alleviating the turbulent separation losses were examined: porous surface mass transfer and surface grooving. A total of four perforated surfaces with varying porosities were evaluated, and three groove orientations with respect to the freestream direction were studied. A comparison of the results from passive control techniques with those from an 'uncontrolled' shock impingement showed that the porous surface with the greatest porosity provided the greatest reduction in the pressure rise across the oblique shock wave. The grooved surface tested were found to be not effective; each of the grooved configurations examined increased the peak pressure value.

  15. Laser induced periodic surface structure formation in germanium above laser damage fluence by mid IR femtosecond laser irradiation

    Science.gov (United States)

    Kafka, Kyle; Austin, Drake; Cheng, Jian; Trendafilov, Simeon; Shvets, Gennady; Li, Hui; Yi, Allen; Blaga, Cosmin I.; DiMauro, L. F.; Chowdhury, Enam

    2014-11-01

    Laser induced periodic surface structures (LIPSS) were generated via interaction of multiple 90 femtosecond 1900 - 3600 nm mid IR laser pulses (3 -10,000) on single crystal Ge targets. For specific laser parameters, both low and high frequency LIPSS are found together, which are oriented perpendicular to each other. Study of polarization dependence of LIPSS revealed that orientation and symmetry of interaction could be controlled by rotating polarization of laser pulses. Low frequency LIPSS formation was consistent with surface plasmon coupling of laser pulses with excited Ge.

  16. Teratogens induce a subset of small heat shock proteins in Drosophila primary embryonic cell cultures.

    Science.gov (United States)

    Buzin, C H; Bournias-Vardiabasis, N

    1984-01-01

    Drosophila embryonic cells placed into culture just after gastrulation differentiate in vitro over the next 24 hr. A number of drugs that are teratogenic in mammalian systems have been found to inhibit muscle or neuron differentiation (or both) in these developing cultures. We have examined, by two-dimensional gel electrophoresis, the effects of these drugs on protein synthesis in embryonic cells. For nine teratogens tested, cells treated for 20 hr with the drug show a dramatic induction of three proteins of about 20 kilodaltons, in addition to the normal proteins synthesized by untreated cells. Three teratogens as well as all eight nonteratogens tested did not show this induction. The induced proteins appear to be identical to three of the heat shock proteins (hsp 23, 22a, and 22b), as shown by electrophoretic mobilities and peptide mapping by partial proteolysis. A 37 degrees C heat shock of the embryonic cells produces the full complement of heat shock proteins, whereas drug-treated cells induce only the subset hsp 23, 22a, and 22b but not hsp 26 or 27. beta-Ecdysterone, the Drosophila molting hormone, also inhibits embryonic differentiation and induces hsp 23, 22a, and 22b, a partial subset of the heat shock proteins (hsp 22, 23, 26, and 27) induced by the hormone in imaginal discs and some Drosophila continuous cell lines. Dose-response studies of several drugs show a correlation between the degree of inhibition of differentiation and the level of induction of hsp 23, 22a, and 22b. The induction of heat shock proteins by drugs may reflect specific types of stress that can also give rise to teratogenesis. Images PMID:6588379

  17. Shock-induced deformation phenomena in magnetite and their consequences on magnetic properties

    Science.gov (United States)

    Reznik, Boris; Kontny, Agnes; Fritz, Jörg; Gerhards, Uta

    2016-06-01

    This study investigates the effects of shock waves on magnetic and microstructural behavior of multidomain magnetite from a magnetite-bearing ore, experimentally shocked to pressures of 5, 10, 20, and 30 GPa. Changes in apparent crystallite size and lattice parameter were determined by X-ray diffraction, and grain fragmentation and defect accumulation were studied by scanning and transmission electron microscopy. Magnetic properties were characterized by low-temperature saturation isothermal remanent magnetization (SIRM), susceptibility measurements around the Verwey transition as well as by hysteresis parameters at room temperature. It is established that the shock-induced refinement of magnetic domains from MD to SD-PSD range is a result of cooperative processes including brittle fragmentation of magnetite grains, plastic deformation with shear bands and twins as well as structural disordering in form of molten grains and amorphous nanoclusters. Up to 10 GPa, a decrease of coherent crystallite size, lattice parameter, saturation magnetization (Ms), and magnetic susceptibility and an increase in coercivity, SIRM, and width of Verwey transition are mostly associated with brittle grain fragmentation. Starting from 20 GPa, a slight recovery is documented in all magnetic and nonmagnetic parameters. In particular, the recovery in SIRM is correlated with an increase of the lattice constant. The recovery effect is associated with the increasing influence of shock heating/annealing at high shock pressures. The strong decrease of Ms at 30 GPa is interpreted as a result of strong lattice damage and distortion. Our results unravel the microstructural mechanisms behind the loss of magnetization and the modification of magnetic properties of magnetite and contribute to our understanding of shock-induced magnetic phenomena in impacted rocks on earth and in meteorites.

  18. Shock-induced thermal history of an EH3 chondrite, Asuka 10164

    Science.gov (United States)

    Kimura, M.; Yamaguchi, A.; Miyahara, M.

    2017-01-01

    Shock-induced features are abundantly observed in meteorites. Especially, shock veins, including high-pressure minerals, characterize many kinds of heavily shocked meteorite. On the other hand, no high-pressure phases have been yet reported from enstatite chondrites. We studied a heavily shocked EH3 chondrite, Asuka 10164, containing a vein, which comprises fragments of fine-grained silicate and opaque minerals, and chondrules. In this vein, we found a silica polymorph, coesite. This is the first discovery of a high-pressure phase in enstatite chondrites. Other high-pressure polymorphs were not observed in the vein. The assemblages and chemical compositions of minerals, and the occurrence of coesite indicate that the vein was subjected to the high-pressure and temperature condition at about 3-10 GPa and 1000 °C. The host also experienced heating for a short time under lower temperature conditions, from 700 to 1000 °C, based on the opaque minerals typical of EH chondrites and textural features. Although the pressure condition of the vein in this chondrite is much lower than those in the other meteorites, our results suggest that all major meteorite groups contain high-pressure polymorphs. Heavy shock events commonly took place in the solar system.

  19. Memory and self-induced shocks in an evolutionary population competing for limited resources.

    Science.gov (United States)

    Kay, Roland; Johnson, Neil F

    2004-11-01

    We present a detailed discussion of the role played by memory, and the nature of self-induced shocks, in an evolutionary population competing for limited resources. Our study builds on a previously introduced multiagent system [Phys. Rev. Lett. 82, 3360 (1999)] which has attracted significant attention in the literature. This system exhibits self-segregation of the population based on the "gene" value p (where 0resource level, and self-induced large changes which spontaneously arise as the dynamical system evolves. We find that the large, macroscopic self-induced shocks that arise are controlled by microscopic changes within extreme subgroups of the population (i.e., subgroups with "gene" values p approximately 0 and p approximately 1).

  20. Tissue tearing caused by pulsed laser-induced ablation pressure.

    Science.gov (United States)

    Cummings, J P; Walsh, J T

    1993-02-01

    Pressure induced by ablative pulses of laser radiation is shown to correlate with the mechanical disruption of tissue. The ablation pressure induced during Er:YSGG laser irradiation of skin, liver, and aorta was calculated from a ballistic pendulum-based measurement of recoil momentum. The ejected material and ablation crater were examined grossly and microscopically after ablation. A gas-dynamic model of laser-induced vaporization was used to understand the measured pressures. The results show that mechanical disruption of tissue occurs when the ablation pressure exceeds the strength of the irradiated tissue at sites of intrinsic weakness.

  1. Systematic analysis of direct-drive baseline designs for shock ignition with the Laser MégaJoule

    Directory of Open Access Journals (Sweden)

    Brandon V.

    2013-11-01

    Full Text Available We present direct-drive target design studies for the laser mégajoule using two distinct initial aspect ratios (A = 34 and A = 5. Laser pulse shapes are optimized by a random walk method and drive power variations are used to cover a wide variety of implosion velocities between 260 km/s and 365 km/s. For selected implosion velocities and for each initial aspect ratio, scaled-target families are built in order to find self-ignition threshold. High-gain shock ignition is also investigated in the context of Laser MégaJoule for marginally igniting targets below their own self-ignition threshold.

  2. Temperature-induced lipocalin (TIL): a shield against stress-inducing environmental shocks in Saccharomyces cerevisiae.

    Science.gov (United States)

    Berterame, Nadia Maria; Bertagnoli, Stefano; Codazzi, Vera; Porro, Danilo; Branduardi, Paola

    2017-09-01

    The yeast Saccharomyces cerevisiae is a well-established workhorse, either for recombinant or natural products, thanks to its natural traits and easily editable metabolism. However, during a bio-based industrial process it meets multiple stresses generated by operative conditions such as non-optimal temperature, pH, oxygenation and product accumulation. The development of tolerant strains is therefore indispensable for the improvement of production, yield and productivity of fermentative processes. In this regard, plants as resilient organisms are a generous source for fishing genes and/or metabolites that can help the cell factory to counteract environmental constraints. Plants possess proteins named temperature-induced lipocalins, TIL, whose levels in the cells correlates with the tolerance to sudden temperature changes and with the scavenging of reactive oxygen species. In this work, the gene encoding for the Arabidopsis thaliana TIL protein was for the first time expressed in S. cerevisiae. The recombinant strain was compared and analysed against the parental counterpart under heat shock, freezing, exposure to organic acid and oxidative agents. In all the tested conditions, TIL expression conferred a higher tolerance to the stress imposed, making this strain a promising candidate for the development of robust cell factories able to overtake the major impairments of industrial processes. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. [The Spectral Analysis of Laser-Induced Plasma in Laser Welding with Various Protecting Conditions].

    Science.gov (United States)

    Du, Xiao; Yang, Li-jun; Liu, Tong; Jiao, Jiao; Wang, Hui-chao

    2016-01-01

    The shielding gas plays an important role in the laser welding process and the variation of the protecting conditions has an obvious effect on the welding quality. This paper studied the influence of the change of protecting conditions on the parameters of laser-induced plasma such as electron temperature and electron density during the laser welding process by designing some experiments of reducing the shielding gas flow rate step by step and simulating the adverse conditions possibly occurring in the actual Nd : YAG laser welding process. The laser-induced plasma was detected by a fiber spectrometer to get the spectral data. So the electron temperature of laser-induced plasma was calculated by using the method of relative spectral intensity and the electron density by the Stark Broadening. The results indicated that the variation of protecting conditions had an important effect on the electron temperature and the electron density in the laser welding. When the protecting conditions were changed, the average electron temperature and the average electron density of the laser-induced plasma would change, so did their fluctuation range. When the weld was in a good protecting condition, the electron temperature, the electron density and their fluctuation were all low. Otherwise, the values would be high. These characteristics would have contribution to monitoring the process of laser welding.

  4. Picosecond laser-induced water condensation in a cloud chamber.

    Science.gov (United States)

    Sun, Haiyi; Liu, Yonghong; Ju, Jingjing; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Du, Shengzhe; Wang, Cheng; Wang, Tiejun; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2016-09-05

    We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament. These tiny particles would grow until precipitation in a super-saturation zone due to laser-induced airflow in a cold region with a large temperature gradient.

  5. Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jaiswal, S., E-mail: surabhijaiswal73@gmail.com; Bandyopadhyay, P.; Sen, A. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2016-08-15

    We report on experimental observations of flow induced large amplitude dust-acoustic shock waves in a complex plasma. The experiments have been carried out in a Π shaped direct current glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change in the gas flow rate is used to trigger the onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a modified Korteweg-de-Vries-Burgers type equation.

  6. Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

    CERN Document Server

    Jaiswal, S; Sen, A

    2016-01-01

    We report on experimental observations of flow induced large amplitude dust-acoustic shock waves (DASW) in a complex plasma. The experiments have been carried out in a $\\Pi$ shaped DC glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change of gas flow rate is used to trigger the onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a m...

  7. X-Ray Laser Induced Photoelectron Spectroscopy for Single-State Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, A J; Dunn, J; van Buuren, T; Hunter, J

    2004-07-14

    We demonstrate single-shot x-ray laser induced time-of-flight photoelectron spectroscopy on metal and semiconductor surfaces with picosecond time resolution. The LLNL COMET compact tabletop x-ray laser source provides the necessary high photon flux (>10{sup 12}/pulse), monochromaticity, picosecond pulse duration, and coherence for probing ultrafast changes in the chemical and electronic structure of these materials. Static valence band and shallow core-level photoemission spectra are presented for ambient temperature polycrystalline Cu foils and Ge(100). Surface contamination was removed by UV ozone cleaning prior to analysis. The ultrafast nature of this technique lends itself to true single-state measurements of shocked and heated materials.

  8. Picosecond laser induced periodic surface structure on copper thin films

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib, E-mail: nadjib.semmar@univ-orleans.fr

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 < N < 10,000) and a fluence of (200 mJ/cm{sup 2} < F < 500 mJ/cm{sup 2}), Low Spatial Frequency LIPSS (LSFL with a spatial period of Λ ∼ 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of Λ ∼ 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ≥ 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  9. Picosecond laser induced periodic surface structure on copper thin films

    Science.gov (United States)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 LIPSS (LSFL with a spatial period of Λ ∼ 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of Λ ∼ 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ≥ 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  10. Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

    Science.gov (United States)

    Xia, Weiguang; Li, Lei; Wei, Yanpeng; Zhao, Aimin; Guo, Yacong; Huang, Chenguang; Yin, Hongxiang; Zhang, Lingchen

    2016-04-01

    Laser shock peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened layer after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened layer were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened layer improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer.

  11. Photography of shock waves during excimer laser ablation of the cornea. Effect of helium gas on propagation velocity.

    Science.gov (United States)

    Krueger, R R; Krasinski, J S; Radzewicz, C; Stonecipher, K G; Rowsey, J J

    1993-07-01

    Shadow photography of shock waves excited by means of a xenon chloride excimer laser was performed to determine the shock wave propagation velocity in air, nitrogen and helium. Energy densities between 500 and 2,000 mJ/cm2 were used to ablate a rotating rubber cylindrical target and porcine corneas. In ablating the rubber cylinder, a shock wave velocity of 3.3 km/s was generated in air and nitrogen at 40 ns; this decreased to 1.4 km/s at 320 ns. When helium was blown on the target, the velocity increased by a factor of approximately two, to 5.9 km/s at 40 ns and 2.7 km/s at 320 ns. We suggest that blowing helium on the surface of the cornea during excimer laser ablation may speed the dissipation of high-energy acoustic waves and gaseous particles, and thus reduce the exposure and transfer of heat energy to the surrounding tissue.

  12. Development of numerical model to investigate the laser driven shock waves from aluminum target into ambient air at atmospheric pressure and its comparison with experiment

    Science.gov (United States)

    Shiva, S. Sai; Leela, Ch.; Chaturvedi, S.; Sijoy, C. D.; Kiran, P. Prem

    2017-01-01

    A one-dimensional, three-temperature (electron, ion and thermal radiation) numerical model was developed to study the laser induced shock wave (LISW) propagation from aluminum target in ambient air at atmospheric pressure. The hydrodynamic equations of mass, momentum and energy are solved by using an implicit scheme in Lagrangian form. The model considers the laser absorption to take place via inverse-bremsstrahlung due to electron-ion (e-i) process. The flux limited electron thermal energy transport due e-i and e-n thermal energy relaxation equations are solved implicitly. The experimental characterization of spatio-temporal evolution of the LISW in air generated by focusing a second harmonic (532 nm, 7ns) of Nd:YAG laser on to surface of Al is performed using shadowgraphy technique with a temporal resolution of 1.5 ns. The velocity of SW observed in the experiments over 0.2 µs-8 µs time scales was compared with the numerical results to understand the SW transition from planar to spherical evolution.

  13. Comparative study of shock wave therapy and Laser therapy effect in elimination of symptoms among patients with myofascial pain syndrome in upper trapezius

    Directory of Open Access Journals (Sweden)

    Parisa Taheri

    2016-01-01

    Results: One man and 19 women, age group of 45.3 ± 7.7 years, were assigned into laser therapy group. Two men and 24 women, average age group of 42.3 ± 10.4 were assigned into shock wave therapy group. A significant difference was found among our study groups before treatment and after starting treatment for VAS, NDI, and SPDI indices, that is, two methods of treatments were effective (P < 0.001. However, among these two treatment methods, laser therapy provided higher effect on VAS and NDI as compared to the radial shock wave method (P < 0.05 in 2 weeks from starting the treatment (consequent to treatment. Conclusion: According to this study results, we can conclude that shock wave and laser therapy results on similar effect in long-term for relieve of pain and eliminating symptoms in patients with myofascial but laser provides a faster optimal results.

  14. Gas permeation and temperature effects in laser-induced delamination

    NARCIS (Netherlands)

    Fedorov, Alexander; Vellinga, Willem-Pier; De Hosson, Jeff

    Laser-induced delamination (LID) is a technique aimed at measuring the work of adhesion of thin polymer coatings on metal substrates. A laser Pulse is used to create a blister that initiates delamination of the film under pressure. The stress fields in the blister wall and the work of adhesion of

  15. Adhesion of polymer coatings studied by laser-induced delamination

    NARCIS (Netherlands)

    Fedorov, A; De Hosson, JTM

    2005-01-01

    This paper concentrates on the laser-induced delamination technique, aimed at measuring the practical work of adhesion of thin polymer coatings on metal substrates. In this technique an infrared laser-pulsed beam is used to create an initial blister. Upon increasing the pulse intensity, the size of

  16. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    Science.gov (United States)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-05-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  17. Towards Friction Control using laser-induced periodic Surface Structures

    NARCIS (Netherlands)

    Eichstädt, J.; Römer, G.R.B.E.; Huis in 't Veld, A.J.

    2011-01-01

    This paper aims at contributing to the study of laser-induced periodic surface structures (LIPSS) and the description of their tribological properties in order to facilitate the knowledge for contact mechanical applications. To obtain laser parameters for LIPSS formation, we propose to execute two D

  18. [Definition of shock types].

    Science.gov (United States)

    Adams, H A; Baumann, G; Gänsslen, A; Janssens, U; Knoefel, W; Koch, T; Marx, G; Müller-Werdan, U; Pape, H C; Prange, W; Roesner, D; Standl, T; Teske, W; Werner, G; Zander, R

    2001-11-01

    Definitions of shock types. Hypovolaemic shock is a state of insufficient perfusion of vital organs with consecutive imbalance of oxygen supply and demand due to an intravascular volume deficiency with critically impaired cardiac preload. Subtypes are haemorrhagic shock, hypovolaemic shock in the narrow sense, traumatic-haemorrhagic shock and traumatic-hypovolaemic shock. Cardiac shock is caused by a primary critical cardiac pump failure with consecutive inadequate oxygen supply of the organism. Anaphylactic shock is an acute failure of blood volume distribution (distributive shock) and caused by IgE-dependent, type-I-allergic, classical hypersensibility, or a physically, chemically, or osmotically induced IgE-independent anaphylactoid hypersensibility. The septic shock is a sepsis-induced distribution failure of the circulating blood volume in the sense of a distributive shock. The neurogenic shock is a distributive shock induced by generalized and extensive vasodilatation with consecutive hypovolaemia due to an imbalance of sympathetic and parasympathetic regulation of vascular smooth muscles.

  19. Unimolecular decomposition of formic and acetic acids: A shock tube/laser absorption study

    KAUST Repository

    Elwardany, A.

    2014-07-16

    The thermal decomposition of formic acid (HCOOH) and acetic acid (CH3COOH), two carboxylic acids which play an important role in oxygenate combustion chemistry, were investigated behind reflected shock waves using laser absorption. The rate constants of the primary decomposition pathways of these acids:(HCOOH → CO + H2 O (R 1); HCOOH → CO2 + H2 (R 2); CH3 COOH → CH4 + CO2 (R 3); CH3 COOH → CH2 CO + H2 O (R 4)) were measured using simultaneous infrared laser absorption of CO, CO2 and H2O at wavelengths of 4.56, 4.18 and 2.93 microns, respectively. Reaction test conditions covered temperatures from 1230 to 1821 K and pressures from 1.0 to 6.5 atm for dilute mixtures of acids (0.25-0.6%) in argon. The rate constants of dehydration (R1) and decarboxylation (R2) reactions of formic acid were calculated by fitting exponential functions to the measured CO, CO2 and H2O time-history profiles. These two decomposition channels were found to be in the fall-off region and have a branching ratio, k1/k2, of approximately 20 over the range of pressures studied here. The best-fit Arrhenius expressions of the first-order rates of R1 and R2 were found to be:(k1 (1 atm) = 1.03 × 1011 exp (- 25651 / T) s- 1 (± 37 %); k1 (6.5 atm) = 9.12 × 1012 exp (- 30275 / T) s- 1 (± 32 %); k2 (1 atm) = 1.79 × 108 exp (- 21133 / T) s- 1 (± 41 %); k2 (6.5 atm) = 2.73 × 108 exp (- 20074 / T) s- 1 (± 37 %)). The rate constants for acetic acid decomposition were obtained by fitting simulated profiles, using an acetic acid pyrolysis mechanism, to the measured species time-histories. The branching ratio, k4/k3, was found to be approximately 2. The decarboxylation and dehydration reactions of acetic acid appear to be in the falloff region over the tested pressure range:(k3 (1 atm) = 3.18 × 1011 exp (- 28679 / T) s- 1 (± 30 %); k3 (6 atm) = 3.51 × 1012 exp (- 31330 / T) s- 1 (± 26 %); k4 (1 atm) = 7.9 × 1011 exp (- 29056 / T) s- 1 (± 34 %); k4 (6 atm) = 6.34 × 1012 exp (- 31330 / T) s

  20. Medical Applications of Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Pathak, A. K.; Rai, N. K.; Singh, Ankita; Rai, A. K.; Rai, Pradeep K.; Rai, Pramod K.

    2014-11-01

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail.

  1. A shock tube laser schlieren study of methyl acetate dissociation in the fall-off regime.

    Science.gov (United States)

    Annesley, Christopher J; Franklin Goldsmith, C; Tranter, Robert S

    2014-04-28

    The pyrolysis of methyl acetate, 2% and 4% dilute in krypton, was investigated in a diaphragmless shock tube (DFST) using laser schlieren densitometry (LS). Experiments were performed at 122 ± 3 and 63 ± 2 Torr over the temperature range of 1492-2266 K. Master equation models for the four main dissociation paths of methyl acetate based on a prior study by Peukert et al. [S. Peukert, R. Sivaramakrishnan, M. Su and J. Michael, Combust. Flame, 2012, 159, 2312-2323] were refined and formed the basis for simulating the LS experiments. The density gradient profiles from the LS experiments indicate that the initial dissociation proceeds predominantly by breakage of the C-O bond leading ultimately to two methyl radicals and CO2, accounting for 83-88% of the methyl acetate loss over this temperature range. Rate coefficients for dissociation of methyl acetate were satisfactorily simulated with a master equation model, with modelled rate coefficients of k120 Torr = 9.06 × 10(81) × T(-19.07) × exp(-61 600K/T) s(-1), k60 Torr = 3.71 × 10(82) × T(-19.34) × exp(-61 200K/T) s(-1), and of k∞ = 1.97 × 10(30) × T(-3.80) × exp(-47 900K/T) s(-1) for the major channel, based on fitting to 120 Torr and 60 Torr data taken in this study. The model also captures the pressure dependency of methyl acetate dissociation and resolves an earlier discrepancy concerning the mechanism of dissociation of methyl acetate.

  2. Compact High Sensitive Laser-Induced Breakdown Spectroscopy Instrument Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser induced breakdown spectroscopy (LIBS) is a versatile tool for in situ substance characterization. Existing LIBS instruments are not compact enough for space...

  3. Thermal desorption from surfaces with laser-induced defects

    Energy Technology Data Exchange (ETDEWEB)

    Szabelski, Pawel; Panczyk, Tomasz; Rudzinski, Wladyslaw

    2002-12-30

    Monte Carlo simulation method was used to mimic surface damage development caused by short laser pulses. The influence of pulsed laser irradiation on the creation of defect concentration was examined in the case of a model surface. In particular, the dependence of the intact surface area on a number of laser scans was studied and compared with the experimental results obtained for Rh(1 1 1) crystal face. Changes in the adsorptivoperties of the surface produced by laser irradiation are explained with the help of a simple geometric model connecting the laser intensity and the disordered area generated by a single laser shot. It was demonstrated that exponential decay of the Low Energy Electron Diffraction (LEED) signal with the number of laser scans, which is observed experimentally, may result directly from the overlapping of the laser spots created on the surface. This effect becomes enhanced when the laser intensity, hence the spot size, increases. The importance of laser-induced defects in the kinetics of catalytic/separation processes was examined in the case of temperature programmed desorption (TPD) spectra from surfaces subjected to a different number of laser shots. The spectra were simulated by employing the Monte Carlo method as well as by application of the absolute rate theory (ART) coupled with the mean field approximation. The results obtained with both methods were in a good agreement even when weak lateral interactions in the adsorbed phase were allowed.

  4. Shock-induced hotspot formation and chemical reaction initiation in PETN containing a spherical void

    Science.gov (United States)

    Shan, Tzu-Ray; Thompson, Aidan P.

    2014-05-01

    We present results of reactive molecular dynamics simulations of hotspot formation and chemical reaction initiation in shock-induced compression of pentaerythritol tetranitrate (PETN) with the ReaxFF reactive force field. A supported shockwave is driven through a PETN crystal containing a 20 nm spherical void at a sub-threshold impact velocity of 2 km/s. Formation of a hotspot due to shock-induced void collapse is observed. During void collapse, NO2 is the dominant species ejected from the upstream void surface. Once the ejecta collide with the downstream void surface and the hotspot develops, formation of final products such as N2 and H2O is observed. The simulation provides a detailed picture of how void collapse and hotspot formation leads to initiation at sub-threshold impact velocities.

  5. Shock-induced collapse of a bubble inside a deformable vessel.

    Science.gov (United States)

    Coralic, Vedran; Colonius, Tim

    2013-07-01

    Shockwave lithotripsy repeatedly focuses shockwaves on kidney stones to induce their fracture, partially through cavitation erosion. A typical side effect of the procedure is hemorrhage, which is potentially the result of the growth and collapse of bubbles inside blood vessels. To identify the mechanisms by which shock-induced collapse could lead to the onset of injury, we study an idealized problem involving a preexisting bubble in a deformable vessel. We utilize a high-order accurate, shock- and interface-capturing, finite-volume scheme and simulate the three-dimensional shock-induced collapse of an air bubble immersed in a cylindrical water column which is embedded in a gelatin/water mixture. The mixture is a soft tissue simulant, 10% gelatin by weight, and is modeled by the stiffened gas equation of state. The bubble dynamics of this model configuration are characterized by the collapse of the bubble and its subsequent jetting in the direction of the propagation of the shockwave. The vessel wall, which is defined by the material interface between the water and gelatin/water mixture, is invaginated by the collapse and distended by the impact of the jet. The present results show that the highest measured pressures and deformations occur when the volumetric confinement of the bubble is strongest, the bubble is nearest the vessel wall and/or the angle of incidence of the shockwave reduces the distance between the jet tip and the nearest vessel surface. For a particular case considered, the 40 MPa shockwave utilized in this study to collapse the bubble generated a vessel wall pressure of almost 450 MPa and produced both an invagination and distention of nearly 50% of the initial vessel radius on a (10) ns timescale. These results are indicative of the significant potential of shock-induced collapse to contribute to the injury of blood vessels in shockwave lithotripsy.

  6. Shock induced shear strength in an HMX based plastic bonded explosive

    Science.gov (United States)

    Millett, J. C. F.; Taylor, P.; Appleby-Thomas, G.

    2017-01-01

    The shock induced mechanical response of an HMX based plastic bonded explosive (PBX) has been investigated in terms of the shear strength. Results show that shear strength increases with impact stress. However comparison with the calculated elastic response of both the PBX and pure HMX suggests that the overall mechanical response is controlled by the HMX crystals, with the near liquid like nature of the binder phase having a minimal contribution.

  7. Velocity measurements within a shock and reshock induced air/SF6 turbulent mixing zone

    Science.gov (United States)

    Haas, Jean-Francois; Bouzgarrou, Ghazi; Bury, Yannick; Jamme, Stephane; Joly, Laurent; Shock-induced mixing Team

    2012-11-01

    A turbulent mixing zone (TMZ) is created in a shock tube (based in ISAE, DAEP) when a Mach 1.2 shock wave in air accelerates impulsively to 70 m/s an air/SF6 interface. The gases are initially separated by a 1 μm thick plastic microfilm maintained flat and parallel to the shock by two wire grids. The upper grid of square spacing 1.8 mm imposes the nonlinear initial perturbation for the Richtmyer-Meshkov instability (RMI). After interaction with a reshock and a rarefaction, the TMZ remains approximately stagnant but much more turbulent. High speed Schlieren visualizations enable the choice of abscissae for Laser Doppler Velocity (LDV) measurements. For a length of the SF6 section equal to 250 mm, the LDV abscissae are 43, 135 and 150 mm from the initial position of the interface. Because of numerous microfilm fragments in the flow and a limited number of olive oil droplets as seeding particles for the LDV, statistical convergence requires the superposition of a least 50 identical runs at each abscissa. The dependence of TMZ structure and velocity field on length of the SF6 section between 100 and 300 mm will be presented. This experimental investigation is carried out in support of modeling and multidimensional simulation efforts at CEA, DAM, DIF. Financial support from CEA is thanksfully appreciated by ISAE.

  8. Fast Quantum Molecular Dynamics Simulations of Shock-induced Chemistry in Organic Liquids

    Science.gov (United States)

    Cawkwell, Marc

    2014-03-01

    The responses of liquid formic acid and phenylacetylene to shock compression have been investigated via quantum-based molecular dynamics simulations with the self-consistent tight-binding code LATTE. Microcanonical Born-Oppenheimer trajectories with precise conservation of the total energy were computed without relying on an iterative self-consistent field optimization of the electronic degrees of freedom at each time step via the Fast Quantum Mechanical Molecular Dynamics formalism [A. M. N. Niklasson and M. J. Cawkwell, Phys. Rev. B, 86, 174308 (2012)]. The conservation of the total energy in our trajectories was pivotal for the capture of adiabatic shock heating as well as temperature changes arising from endo- or exothermic chemistry. Our self-consistent tight-binding parameterizations yielded very good predictions for the gas-phase geometries of formic acid and phenylacetylene molecules and the principal Hugoniots of the liquids. In accord with recent flyer-plate impact experiments, our simulations revealed i) that formic acid reacts at relatively low impact pressures but with no change in volume between products and reactants, and ii) a two-step polymerization process for phenylacetylene. Furthermore, the evolution of the HOMO-LUMO gap tracked on-the-fly during our simulations could be correlated with changes transient absorption measured during laser-driven shock compression experiments on these liquids.

  9. Detecting plant metabolic responses induced by ground shock using hyperspectral remote sensing and physiological contact measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pickles, W.L.; Cater, G.A.

    1996-12-03

    A series of field experiments were done to determine if ground shock could have induced physiological responses in plants and if the level of the response could be observed. The observation techniques were remote sensing techniques and direct contact physiological measurements developed by Carter for detecting pre-visual plant stress. The remote sensing technique was similar to that used by Pickles to detect what appeared to be ground shock induced plant stress above the 1993 Non Proliferation Experiment`s underground chemical explosion. The experiment was designed to provide direct plant physiological measurements and remote sensing ratio images and from the same plants at the same time. The simultaneous direct and remote sensing measurements were done to establish a ground truth dataset to compare to the results of the hyperspectral remote sensing measurements. In addition, the experiment was designed to include data on what was thought to be the most probable interfering effect, dehydration. The experimental design included investigating the relative magnitude of the shock induced stress effects compared to dehydration effects.

  10. Neurotoxicity induced by arsenic in Gallus Gallus: Regulation of oxidative stress and heat shock protein response.

    Science.gov (United States)

    Zhao, Panpan; Guo, Ying; Zhang, Wen; Chai, Hongliang; Xing, Houjuan; Xing, Mingwei

    2017-01-01

    Arsenic, a naturally occurring heavy metal pollutant, is one of the functioning risk factors for neurological toxicity in humans. However, little is known about the effects of arsenic on the nervous system of Gallus Gallus. To investigate whether arsenic induce neurotoxicity and influence the oxidative stress and heat shock proteins (Hsps) response in chickens, seventy-two 1-day-old male Hy-line chickens were treated with different doses of arsenic trioxide (As2O3). The histological changes, antioxidant enzyme activity, and the expressions of Hsps were detected. Results showed slightly histology changes were obvious in the brain tissues exposure to arsenic. The activities of Glutathione peroxidase (GSH-Px) and catalase (CAT) were decreased compared to the control, whereas the malondialdehyde (MDA) content was increased gradually along with increase in diet-arsenic. The mRNA levels of Hsps and protein expressions of Hsp60 and Hsp70 were up-regulated. These results suggested that sub-chronic exposure to arsenic induced neurotoxicity in chickens. Arsenic exposure disturbed the balance of oxidants and antioxidants. Increased heat shock response tried to protect chicken brain tissues from tissues damage caused by oxidative stress. The mechanisms of neurotoxicity induced by arsenic include oxidative stress and heat shock protein response in chicken brain tissues.

  11. Dynamical behavior of laser-induced nanoparticles during remote processing

    Science.gov (United States)

    Scholz, Tobias; Dickmann, Klaus; Ostendorf, Andreas

    2014-02-01

    Laser remote processing is used in a wide field of industrial applications. Among other things, it is characterized by flexible beam guidance in combination with high processing velocities. But in most cases process gas support in the interaction zone is omitted. Consequently, interaction mechanism between the vapor plume and the incident laser radiation can dynamically affect the process stability. Referring to remote welding with high brilliant laser sources having a wavelength around 1 μm, the interaction between the incident laser radiation and formed particles plays an important role. The presented work shows results of the investigation of the laser-induced particle formation during the laser welding of stainless steel with a 2 kW fiber laser under remote conditions. It is therefore concentrated on the dynamical behavior of the laser-induced particle formation and the dependence of the particle formation on the laser beam power. TEM images of formed particles were analyzed. In addition, the radiation of a LED was directed through the vapor plume. On the one hand, the dynamic of the attenuation was considered. On the other hand, the Rayleigh approximation was used in order to evaluate the detected signals.

  12. A suppressor to prevent direct wave-induced cavitation in shock wave therapy devices

    Science.gov (United States)

    Matula, Thomas J.; Hilmo, Paul R.; Bailey, Michael R.

    2005-07-01

    Cavitation plays a varied but important role in lithotripsy. Cavitation facilitates stone comminution, but can also form an acoustic barrier that may shield stones from subsequent shock waves. In addition, cavitation damages tissue. Spark-gap lithotripters generate cavitation with both a direct and a focused wave. The direct wave propagates as a spherically diverging wave, arriving at the focus ahead of the focused shock wave. It can be modeled with the same waveform (but lower amplitude) as the focused wave. We show with both simulations and experiments that bubbles are forced to grow in response to the direct wave, and that these bubbles can still be large when the focused shock wave arrives. A baffle or ``suppressor'' that blocks the propagation of the direct wave is shown to significantly reduce the direct wave pressure amplitude, as well as direct wave-induced bubble growth. These results are applicable to spark-gap lithotripters and extracorporeal shock wave therapy devices, where cavitation from the direct wave may interfere with treatment. A simple direct-wave suppressor might therefore be used to improve the therapeutic efficacy of these devices.

  13. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  14. Water flattens graphene wrinkles: laser shock wrapping of graphene onto substrate-supported crystalline plasmonic nanoparticle arrays.

    Science.gov (United States)

    Hu, Yaowu; Lee, Seunghyun; Kumar, Prashant; Nian, Qiong; Wang, Wenqi; Irudayaraj, Joseph; Cheng, Gary J

    2015-12-21

    Hot electron injection into an exceptionally high mobility material can be realized in graphene-plasmonic nanoantenna hybrid nanosystems, which can be exploited for several front-edge applications including photovoltaics, plasmonic waveguiding and molecular sensing at trace levels. Wrinkling instabilities of graphene on these plasmonic nanostructures, however, would cause reactive oxygen or sulfur species to diffuse and react with the materials, decrease charge transfer rates and block intense hot-spots. No ex situ graphene wrapping technique has been explored so far to control these wrinkles. Here, we present a method to generate seamless integration by using water as a flyer to transfer the laser shock pressure to wrap graphene onto plasmonic nanocrystals. This technique decreases the interfacial gap between graphene and the covered substrate-supported plasmonic nanoparticle arrays by exploiting a shock pressure generated by the laser ablation of graphite and the water impermeable nature of graphene. Graphene wrapping of chemically synthesized crystalline gold nanospheres, nanorods and bipyramids with different field confinement capabilities is investigated. A combined experimental and computational method, including SEM and AFM morphological investigation, molecular dynamics simulation, and Raman spectroscopy characterization, is used to demonstrate the effectiveness of this technique. Graphene covered gold bipyramid exhibits the best result among the hybrid nanosystems studied. We have shown that the hybrid system fabricated by laser shock can be used for enhanced molecular sensing. The technique developed has the characteristics of tight integration, and chemical/thermal stability, is instantaneous in nature, possesses a large scale and room temperature processing capability, and can be further extended to integrate other 2D materials with various 0-3D nanomaterials.

  15. A Previously Unrecognized Example of the Shock-Induced Breakdown of Biotite to Garnet from the Steen River Impact Structure, Canada

    Science.gov (United States)

    Walton, E. L.; Sharp, T. G.; Hu, J.; Tschauner, O.

    2016-08-01

    The novel shock-induced transformation of biotite to almandine garnet accompanied by fluid release and Fe-oxidation is reported from those grains adjacent to shock veins in crystalline basement rocks of the Steen River impact structure.

  16. Electrochemical and pitting corrosion resistance of AISI 4145 steel subjected to massive laser shock peening treatment with different coverage layers

    Science.gov (United States)

    Lu, J. Z.; Han, B.; Cui, C. Y.; Li, C. J.; Luo, K. Y.

    2017-02-01

    The effects of massive laser shock peening (LSP) treatment with different coverage layers on residual stress, pitting morphologies in a standard corrosive solution and electrochemical corrosion resistance of AISI 4145 steel were investigated by pitting corrosion test, potentiodynamic polarisation test, and SEM observations. Results showed massive LSP treatment can effectively cause an obvious improvement of pitting corrosion resistance of AISI 4145 steel, and increased coverage layer can also gradually improve its corrosion resistance. Massive LSP treatment with multiple layers was shown to influence pitting corrosion behaviour in a standard corrosive solution.

  17. Research on laser induced acoustic source based underwater communication system

    Science.gov (United States)

    Lei, Lihua; Zhou, Ju; Zhang, Lei; Wan, Xiaoyun

    2016-10-01

    Acoustic transducers are traditionally used to generate underwater acoustical energy with the device physically immersed in water. Novel methods are required for communicating from an in-air platform or surface vessel to a submerged vessel. One possible noncontact downlink communication system involves the use of laser induced acoustic source. The most common mechanisms of opto-acoustic energy conversion are, by order of increasing laser energy density and efficiency, thermal expansion, surface evaporation and optical breakdown. The laser induced acoustic source inherently bears the obvious advantage of not requiring any physical transducer in the medium. At the same time, acoustic energy propagation is efficient in water, whereas optical energy propagate well in air, leading to a more efficiency opto-acoustic communication method. In this paper, an opto-acoustic underwater Communication system is described, aiming to study and analysis whether laser induced sound could achieve good performance for effective communication in practical application.

  18. Experimental gastric ulcers induced by immobilization and electric shock of rats and their pharmacotherapy

    Science.gov (United States)

    Zabrodin, O. N.

    1980-01-01

    The mechanism of development of experimental gastric ulcers, induced in rats by combined immobilization and electric shock, was analyzed pharmacologically with peripheral neurotropic agents. It is concluded that: (1) The most marked preventive effect in the development of the experimentally induced gastric ulcers was displayed by agents capable of blocking the ascending activation system of the reticular formation. (2) Sympathetic fibers, which disrupt the trophism of the gastric wall, form the efferent portion of the reflex arc. (3) Gastric secretion does not appear to be the primary cause of ulceration.

  19. Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J.A.; Amado, J.M.; Tobar, M.J.; Mateo, M.P.; Yañez, A.; Nicolas, G., E-mail: gines@udc.es

    2015-05-01

    Highlights: • Chemical mapping and profiling by laser-induced breakdown spectroscopy (LIBS) of coatings produced by laser cladding. • Production of laser clads using tungsten carbide (WC) and nickel based matrix (NiCrBSi) powders. • Calibration by LIBS of hardfacing alloys with different WC concentrations. - Abstract: Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

  20. Development And Optical Absorption Properties Of A Laser Induced Plasma During CO2-Laser Processing

    Science.gov (United States)

    Beyer, E.; Bakowsky, L.; Loosen, P.; Poprawe, R.; Herziger, G.

    1984-03-01

    Laser material processing is accompanied by a laser induced plasma in front of the target surface as soon as the laser radiation exceeds a certain critical intensity. For cw CO2-laser machining of metal targets the threshold for plasma onset is about 106 W/cm2. Critical condition for plasma generation at this intensity level is to reach evaporation temperature at the target's surface. At intensity levels exceeding 106 W/cm2 the laser light is interacting with the laser induced plasma and then the plasma in turn interacts with the target. The absorptivity is no longer constant, but increases with increasing intensity of the incident radiation, so that the total amount of power coupled to the target is increasing. This holds up to intensity levels of 2'10 Wicm2. Then the plasma begins to withdraw from the target surface, thus interrupting plasma-target interaction so that the laser power is no longer coupled into the target completely. The results of laser welding (welding depth) in the intensity level of 106 W/cm2 are governed by the product of incident intensity times focus radius, so that welding results are a measure to determine focus radius and laser intensity.

  1. Development of a thermal fatigue test method for thermal barrier coatings by laser excitation using a laser thermal shock facility; Entwicklung eines Pruefverfahrens zur laserinduzierten thermischen Ermuedung thermischer Schutzschichten mittels einer Laser-Thermoschockpruefeinrichtung

    Energy Technology Data Exchange (ETDEWEB)

    Nies, Daniel

    2012-07-13

    cooling, experiments can be completed, where the thermal loads are highly reproducible and comparable to real operation conditions. The development and evolution of delamination damages can be observed by acoustic emission and thermographic methods. Sound location using the acoustic emission data shows the limits of the applied equipment. Good sound location results can be achieved by a time-consuming manual routine, but the results are highly dependent on the signal quality. A reduced zone location algorithm with an automatic analysis shows satisfying results. A combination of the zone location results, the analysis of the acoustic emission data and the thermographic analysis of the infrared camera data allows a very good visualisation of the damage evolution. First experiments showed delaminations located in the ceramic layer near the topcoat-bondcoatboundary, which corresponds to a failure mode induced by high cyclic loads of the samples. The use of a focused laser beam results in a local hot spot at the laser spot during heating. This adds a thermal shock component to the thermo-cyclic load during the experiments.

  2. Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

    Science.gov (United States)

    Varghese, Babu; Bonito, Valentina; Jurna, Martin; Palero, Jonathan; Verhagen, Margaret Hortonand Rieko

    2015-01-01

    We investigated the influence of thermal initiation pathway on the irradiance threshold for laser induced breakdown in transparent, absorbing and scattering phantoms. We observed a transition from laser-induced optical breakdown to laser-induced thermal breakdown as the absorption coefficient of the medium is increased. We found that the irradiance threshold after correction for the path length dependent absorption and scattering losses in the medium is lower due to the thermal pathway for the generation of seed electrons compared to the laser-induced optical breakdown. Furthermore, irradiance threshold gradually decreases with the increase in the absorption properties of the medium. Creating breakdown with lower irradiance threshold that is specific at the target chromophore can provide intrinsic target selectivity and improve safety and efficacy of skin treatment methods that use laser induced breakdown. PMID:25909007

  3. Innovative Drug Injection via Laser Induced Plasma

    Science.gov (United States)

    Han, Tae-hee; Yoh, Jack J.

    2010-10-01

    A laser based needle-free liquid drug injection device has been developed. A laser beam is focused inside the liquid contained in the rubber chamber of micro scale. The focused laser beam causes explosive bubble growth and the sudden volume increase in a sealed chamber drives a microjet of liquid drug through the micronozzle. The exit diameter of the nozzle is 125 um and the injected microjet reaches an average velocity of 264 m/s. This device adds the time-varying feature of microjet to the current state of liquid injection for drug delivery.

  4. Effects of Laser Shock Processing on Morphologies and Mechanical Properties of ANSI 304 Stainless Steel Weldments Subjected to Cavitation Erosion

    Science.gov (United States)

    Zhang, Lei; Lu, Jin-Zhong; Zhang, Yong-Kang; Ma, Hai-Le; Luo, Kai-Yu; Dai, Feng-Ze

    2017-01-01

    Effects of laser shock processing (LSP) on the cavitation erosion resistance of laser weldments were investigated by optical microscope (OM), scanning electron microscope (SEM) observations, roughness tester, micro hardness tester, and X-ray diffraction (XRD) technology. The morphological microstructures were characterized. Cumulative mass loss, incubation period, erosion rate, and damaged surface areas were monitored during cavitation erosion. Surface roughness, micro-hardness, and residual stress were measured in different zones. Results showed that LSP could improve the damage of morphological microstructures and mechanical properties after cavitation erosion. The compressive residual stresses were generated during the process of LSP, which was an effective guarantee for the improvement of the above mentioned properties. PMID:28772652

  5. THE COUNTER-JET FORMATION IN AN AIR BUBBLE INDUCED BY THE IMPACT OF SHOCK WAVES

    Institute of Scientific and Technical Information of China (English)

    BAI Li-xin; XU Wei-lin; LI Chao; GAO Yan-dong

    2011-01-01

    The interaction of an air bubble (isolated in water or attached to a boundary) with shock waves induced by electric sparks is investigated by high-speed photography.The interaction is closely related to the counter-jet induced by the impact of shock waves.The formation of a counter-jet in an air bubble is related to the liquid jet formed in the same air bubble,but the mechanism is different with that of the counter-jet formation in a collapsing cavitation bubble.The formation of a counter-jet in an air bubble is related to discharge energy,air bubble size and radius of shock wave.With a given energy of the spark discharge,the formation of a counter-jet in an air bubble is related to δ/ε (the ratio of the dimensionless bubble-bubble distance to the dimensionless air bubble radius).The counter-jet will only be produced when δ/ε is in the range of 1.2-2.2.The counter-jet in an air bubble is of an important nuclei-generating mechanism.

  6. Septic Shock following Prostate Biopsy: Aggressive Limb Salvage for Extremities after Pressor-Induced Ischemic Gangrene

    Directory of Open Access Journals (Sweden)

    Jocelyn Lu, BS

    2017-09-01

    Full Text Available Summary:. Vasopressors used to treat patients with septic shock can cause ischemic necrosis of appendages such as the ears and nose, as well as the extremities. Cases of quadruple-extremity necrosis have high morbidity and mortality, and a profound negative impact on quality of life. This case report details the successful limb salvage and return to function using free tissue transfer as a means to salvage bilateral lower extremities in a patient who suffered vasopressor-induced ischemia of upper and lower extremities after prostate biopsy–induced septic shock. Septic shock following transrectal ultrasound–guided prostate biopsy is a rare, yet life-threatening complication. Successful treatment included thorough planning and staging of therapies such as awaiting tissue demarcation and serial surgical debridement to adequately prepare the tissue bed for free tissue transfer. Adjunctive treatments such as hyperbaric oxygen therapy, negative-pressure wound therapy, and meticulous wound care played a crucial role in wound healing. This vigilant planning and coordinated care resulted in the successful lower extremity salvage, consisting of bilateral transmetatarsal amputations and free tissue transfer to both limbs. We present our long-term follow-up of a functional ambulatory patient after catastrophic, life-threatening infection and appropriate multidisciplinary care.

  7. Accelerated electronic structure-based molecular dynamics simulations of shock-induced chemistry

    Science.gov (United States)

    Cawkwell, Marc

    2015-06-01

    The initiation and progression of shock-induced chemistry in organic materials at moderate temperatures and pressures are slow on the time scales available to regular molecular dynamics simulations. Accessing the requisite time scales is particularly challenging if the interatomic bonding is modeled using accurate yet expensive methods based explicitly on electronic structure. We have combined fast, energy conserving extended Lagrangian Born-Oppenheimer molecular dynamics with the parallel replica accelerated molecular dynamics formalism to study the relatively sluggish shock-induced chemistry of benzene around 13-20 GPa. We model interatomic bonding in hydrocarbons using self-consistent tight binding theory with an accurate and transferable parameterization. Shock compression and its associated transient, non-equilibrium effects are captured explicitly by combining the universal liquid Hugoniot with a simple shrinking-cell boundary condition. A number of novel methods for improving the performance of reactive electronic structure-based molecular dynamics by adapting the self-consistent field procedure on-the-fly will also be discussed. The use of accelerated molecular dynamics has enabled us to follow the initial stages of the nucleation and growth of carbon clusters in benzene under thermodynamic conditions pertinent to experiments.

  8. Weibel-mediated collisionless shocks in laser-irradiated dense plasmas: Prevailing role of the electrons in generating the field fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Ruyer, C., E-mail: charles.ruyer@polytechnique.edu; Gremillet, L., E-mail: laurent.gremillet@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Bonnaud, G. [CEA, Saclay, INSTN, F-91191 Gif-sur-Yvette (France)

    2015-08-15

    We present a particle-in-cell simulation of the generation of a collisionless strong shock in a dense plasma driven by an ultra-intense, plane-wave laser pulse. A linear theory analysis, based on a multi-waterbag model of the particle distributions, highlights the role of the laser-heated electrons in triggering the Weibel-like instability causing shock formation. It is demonstrated that the return-current electrons play a major role in the instability development as well as in the determination of the saturated magnetic field. By contrast, the ions are found of minor importance in driving the instability and the magnetic field fluctuations responsible for their isotropization. Finally, we show that a Weibel-mediated shock can also be generated by a focused laser pulse of large enough spot size.

  9. Weibel-mediated collisionless shocks in laser-irradiated dense plasmas: Prevailing role of the electrons in generating the field fluctuations

    Science.gov (United States)

    Ruyer, C.; Gremillet, L.; Bonnaud, G.

    2015-08-01

    We present a particle-in-cell simulation of the generation of a collisionless strong shock in a dense plasma driven by an ultra-intense, plane-wave laser pulse. A linear theory analysis, based on a multi-waterbag model of the particle distributions, highlights the role of the laser-heated electrons in triggering the Weibel-like instability causing shock formation. It is demonstrated that the return-current electrons play a major role in the instability development as well as in the determination of the saturated magnetic field. By contrast, the ions are found of minor importance in driving the instability and the magnetic field fluctuations responsible for their isotropization. Finally, we show that a Weibel-mediated shock can also be generated by a focused laser pulse of large enough spot size.

  10. Laser-induced quantum pumping in graphene

    Energy Technology Data Exchange (ETDEWEB)

    San-Jose, Pablo [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, 28006 Madrid (Spain); Prada, Elsa; Kohler, Sigmund [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Schomerus, Henning [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2012-10-08

    We investigate non-adiabatic electron pumping in graphene generated by laser irradiation with linear polarization parallel or perpendicular to the transport direction. Transport is dominated by the spatially asymmetric excitation of electrons from evanescent into propagating modes. For a laser with parallel polarization, the pumping response exhibits a subharmonic resonant enhancement which directly probes the Fermi energy; no such enhancement occurs for perpendicular polarization. The resonance mechanism relies on the chirality of charge carriers in graphene.

  11. Generation of quasi-monoenergetic heavy ion beams via staged shock wave acceleration driven by intense laser pulses in near-critical plasmas

    Science.gov (United States)

    Zhang, W. L.; Qiao, B.; Shen, X. F.; You, W. Y.; Huang, T. W.; Yan, X. Q.; Wu, S. Z.; Zhou, C. T.; He, X. T.

    2016-09-01

    Laser-driven ion acceleration potentially offers a compact, cost-effective alternative to conventional accelerators for scientific, technological, and health-care applications. A novel scheme for heavy ion acceleration in near-critical plasmas via staged shock waves driven by intense laser pulses is proposed, where, in front of the heavy ion target, a light ion layer is used for launching a high-speed electrostatic shock wave. This shock is enhanced at the interface before it is transmitted into the heavy ion plasmas. Monoenergetic heavy ion beam with much higher energy can be generated by the transmitted shock, comparing to the shock wave acceleration in pure heavy ion target. Two-dimensional particle-in-cell simulations show that quasi-monoenergetic {{{C}}}6+ ion beams with peak energy 168 MeV and considerable particle number 2.1 × {10}11 are obtained by laser pulses at intensity of 1.66 × {10}20 {{W}} {{cm}}-2 in such staged shock wave acceleration scheme. Similarly a high-quality {{Al}}10+ ion beam with a well-defined peak with energy 250 MeV and spread δ E/{E}0=30 % can also be obtained in this scheme.

  12. Shock induced endotheliopathy (SHINE) in acute critical illness - a unifying pathophysiologic mechanism

    DEFF Research Database (Denmark)

    Johansson, Pär I.; Stensballe, Jakob; Ostrowski, Sisse Rye

    2017-01-01

    One quarter of patients suffering from acute critical illness such as severe trauma, sepsis, myocardial infarction (MI) or post cardiac arrest syndrome (PCAS) develop severe hemostatic aberrations and coagulopathy, which are associated with excess mortality. Despite the different types of injurious...... "hit", acutely critically ill patients share several phenotypic features that may be driven by the shock. This response, mounted by the body to various life-threatening conditions, is relatively homogenous and most likely evolutionarily adapted. We propose that shock-induced sympatho......-adrenal hyperactivation is a critical driver of endothelial cell and glycocalyx damage (endotheliopathy) in acute critical illness, with the overall aim of ensuring organ perfusion through an injured microvasculature. We have investigated more than 3000 patients suffering from different types of acute critical illness...

  13. Large eddy simulation of a shocked gas cylinder instability induced turbulence

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Navier-Stokes equations for compressible fluid are solved with the operator splitting technique and LES (large eddy simulation) with the Smagorinsky model. A computational code MVFT (multi-viscosity-fluid and turbulence) is developed to study hydrodynamic instability and the induced turbulent mixing for multi compressible fluid. In order to validate the code MVFT,the LANL’s shock tube experiment of shocked SF6 gas cylinder is simulated with the initial state of SF6 gas cylinder described by dissipative ITL (interface transition layer). It is shown that the width and height of gas cylinder calculated with MVFT are closer to the experimental results than RAGE,and that the velocities of upstream edge,downstream edge and vortex edge agree with the experimental results,and are appreciably smaller than the RAGE results. The code MVFT has been pre-liminarily validated.

  14. Molecular dynamics study of accelerated ion-induced shock waves in biological media

    CERN Document Server

    de Vera, Pablo; Currell, Fred J; Solov'yov, Andrey V

    2016-01-01

    We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which lies beyond the possibilities of the analytical model.

  15. Dynamics of shock induced ignition in Fickett's model with chain-branching kinetics: influence of $\\chi$

    CERN Document Server

    Tang, Justin

    2012-01-01

    The problem of shock induced ignition by a piston is addressed in the framework of Fickett's model for reactive compressible flows, i.e., the reactive form of Burgers' equation. An induction-reaction two-step chain-branching model is used to study the coupling between the energy release and the compressible hydrodynamics occurring during the shock ignition transient leading to a detonation. Owing to the model's simplicity, the ignition and acceleration mechanism is explained using the two families of characteristics admitted by the model. The energy release along the particle paths provides the amplification of forward-travelling pressure waves. These waves pre-compress the medium in the induction layer ahead of the reaction zone, therefore changing the induction delays of successive particles. The variation of the induction delay provides the modulation of the amplification of the forward travelling pressure waves by controlling the residence time of the pressure waves in the reaction zone. A closed form ana...

  16. Therapeutic Down-Modulators of Staphylococcal Superantigen-Induced Inflammation and Toxic Shock

    Directory of Open Access Journals (Sweden)

    Teresa Krakauer

    2010-07-01

    Full Text Available Staphylococcal enterotoxin B (SEB and related superantigenic toxins are potent stimulators of the immune system and cause a variety of diseases in humans, ranging from food poisoning to toxic shock. These toxins bind directly to major histocompatibility complex (MHC class II molecules on antigen-presenting cells and specific Vb regions of T-cell receptors (TCR, resulting in hyperactivation of both monocytes/macrophages and T lymphocytes. Activated host cells produce massive amounts of proinflammatory cytokines and chemokines, activating inflammation and coagulation, causing clinical symptoms that include fever, hypotension, and shock. This review summarizes the in vitro and in vivo effects of staphylococcal superantigens, the role of pivotal mediators induced by these toxins in the pathogenic mechanisms of tissue injury, and the therapeutic agents to mitigate the toxic effects of superantigens.

  17. Synergistic effects of glutamine and ciprofloxacin in reduction of Pseudomonas aeruginosa-induced septic shock severity.

    Science.gov (United States)

    Mazloomi, Ebrahim; Jazani, Nima Hosseini; Sohrabpour, Mohammad; Ilkhanizadeh, Behrouz; Shahabi, Shahram

    2011-12-01

    Systemic inflammatory response induced by over expressing inflammatory mediators is the main pathogenic mechanism of septic shock. Glutamine (Gln) has been demonstrated to inhibit pro-inflammatory cytokine release through enhanced heat shock protein (HSP) expression. To assess the effect of co-administration of Gln and antibiotic ciprofloxacin in reduction of septic shock severity caused by Pseudomonas aeruginosa in mice. Six- to eight-week old male BALB/c mice were used. At first, P. aeruginosa susceptibility to ciprofloxacin was determined. Then, 75% lethal dose (LD 75) of P. aeruginosa in a 10-day period was assessed. For determining survival rate, fifty mice were divided into 5 groups which included control (+), control (-), Gln, ciprofloxacin, and "glutamine+ciprofloxacin" group. All mice, except for control (-), were given an LD75 dose of P. aeruginosa and after 30 min each group received its special treatment: control (-) and control (+) groups received only 500λ phosphate buffer saline (PBS). Gln group received 500λ Ala-Gln, Cip group received 500λ ciprofloxacin. The Cip+Gln group received 500λ Gln and ciprofloxacin. Finally serum TNF-α, IL-10 and HSP-70 concentrations were measured and the severity of liver necrosis was examined. Glutamine in combination with ciprofloxacin significantly increased survival rate and serum HSP-70 and IL-10 concentration and significantly decreased serum TNF-α concentration and the liver necrosis severity in comparison to control (+) group. Gln has synergistic effects with ciprofloxacin in reduction of P. aeruginosa-induced septic shock. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Magnetic field generation, Weibel-mediated collisionless shocks, and magnetic reconnection in colliding laser-produced plasmas

    Science.gov (United States)

    Fox, W.; Bhattacharjee, A.; Fiksel, G.

    2016-10-01

    Colliding plasmas are ubiquitous in astrophysical environments and allow conversion of kinetic energy into heat and, most importantly, the acceleration of particles to extremely high energies to form the cosmic ray spectrum. In collisionless astrophysical plasmas, kinetic plasma processes govern the interaction and particle acceleration processes, including shock formation, self-generation of magnetic fields by kinetic plasma instabilities, and magnetic field compression and reconnection. How each of these contribute to the observed spectra of cosmic rays is not fully understood, in particular both shock acceleration processes and magnetic reconnection have been proposed. We will review recent results of laboratory astrophysics experiments conducted at high-power, inertial-fusion-class laser facilities, which have uncovered significant results relevant to these processes. Recent experiments have now observed the long-sought Weibel instability between two interpenetrating high temperature plasma plumes, which has been proposed to generate the magnetic field necessary for shock formation in unmagnetized regimes. Secondly, magnetic reconnection has been studied in systems of colliding plasmas using either self-generated magnetic fields or externally applied magnetic fields, and show extremely fast reconnection rates, indicating fast destruction of magnetic energy and further possibilities to accelerate particles. Finally, we highlight kinetic plasma simulations, which have proven to be essential tools in the design and interpretation of these experiments.

  19. Quantitative Analysis of Liquid by Quick Freezing Into Ice Using Nd-YAG Laser-Induced Atmospheric Plasma

    Directory of Open Access Journals (Sweden)

    Mohamad Infrawan Yulianto Ichwan

    2005-05-01

    Full Text Available A new approach of quantitative analysis of liquid sample using laser ablation technique was developed. The liquid was immediately freezed using the mixture of dry ice and alcohol in weight ratio of 95% : 5%. As a result, an increase of the repulsion force from the sample surface will enable the generation of the laser-induced shock wave plasma which was difficult to carry out on liquid surface. The ice sample was then irradiated using Nd-YAG laser operated in its fundamental wavelength. In order to increase the signal to background ratio and to obtain a sharp atomic line spectra, helium gas was used instead of air. Dynamic characterization of the spatially integrated time profile of the Cu I 521.8 nm, Cu I 510.5 nm and Ha lines shows a shock excitation stage and cooling stage which is corresponded to our shock wave model even when the plasma was generated under atmospheric gas pressure. Further study of the time profile averaged temperature of the atmospheric plasma also shows an increase of temperature during the shock excitation stage followed by diminution of temperature during the cooling stage. An application of this technique was then applied to quantitative analysis of several liquid samples. A linear calibration curve which intercept at 0 point was obtained for all of the elements investigated in this study such as sodium, potassium, lithium, copper, silver, lead and aluminum. A detection limit of around 1 ppm was found for the above element. This new technique will contribute to a great extent of laser atomic emission spectrochemical analysis for liquid samples.

  20. Assessment of the efficacy of laser hyperthermia and nanoparticle-enhanced therapies by heat shock protein analysis

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Fei [Department of Precision Instrument, Tsinghua University, Beijing, 100084 (China); Zhang, Ye; Zhang, Juan; Liu, Ran, E-mail: liuran@tsinghua.edu.cn [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, 100084 (China); Guo, Junwei [Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084 (China)

    2014-03-15

    Tumor thermotherapy is a method of cancer treatment wherein cancer cells are killed by exposing the body tissues to high temperatures. Successful clinical implementation of this method requires a clear understanding and assessment of the changes of the tumor area after the therapy. In this study, we evaluated the effect of near-infrared laser tumor thermotherapy at the molecular, cellular, and physical levels. We used single-walled carbon nanotubes (SWNTs) in combination with this thermotherapy. We established a mouse model for breast cancer and randomly divided the mice into four groups: mice with SWNT-assisted thermotherapy; mice heat treated without SWNT; mice injected with SWNTs without thermotherapy; and a control group. Tumors were irradiated using a near-infrared laser with their surface temperature remaining at approximately 45 °C. We monitored the tumor body growth trend closely by daily physical measurements, immunohistochemical staining, and H and E (hematoxylin-eosin) staining by stage. Our results showed that infrared laser hyperthermia had a significant inhibitory effect on the transplanted breast tumor, with an inhibition rate of 53.09%, and also significantly reduced the expression of the heat shock protein Hsp70. Furthermore, we have found that protein analysis and histological analysis can be used to assess therapeutic effects effectively, presenting broad application prospects for determining the effect of different treatments on tumors. Finally, we discuss the effects of SWNT-assisted near-infrared laser tumor thermotherapy on tumor growth at the molecular, cellular, and physical levels.