WorldWideScience

Sample records for laser-supported detonation waves

  1. Laser-supported detonation waves and pulsed laser propulsion

    International Nuclear Information System (INIS)

    Kare, J.

    1990-01-01

    A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10 4 K, 10 2 atmospheres, 10 7 w/cm 2 ) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition of the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the Program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research question still outstanding in this area

  2. Laser-Supported Detonation Concept as a Space Thruster

    International Nuclear Information System (INIS)

    Fujiwara, Toshi; Miyasaka, Takeshi

    2004-01-01

    Similar to the concept of pulse detonation engine (PDE), a detonation generated in the 'combustion chamber' due to incoming laser absorption can produce the thrust basically much higher than the one that a laser-supported deflagration wave can provide. Such a laser-supported detonation wave concept has been theoretically studied by the first author for about 20 years in view of its application to space propulsion. The entire work is reviewed in the present paper. The initial condition for laser absorption can be provided by increasing the electron density using electric discharge. Thereafter, once a standing/running detonation wave is formed, the laser absorption can continuously be performed by the classical absorption mechanism called Inverse Bremsstrahlung behind a strong shock wave

  3. Laser driven detonation waves above a solid target

    International Nuclear Information System (INIS)

    Emmony, D.C.

    1975-01-01

    The interaction of a TEA CO 2 laser pulse with a carbon target in an argon atmosphere (p approximately mmHg) is shown to produce a double detonation wave system. The laser driven detonation wave becomes the most important as the gas pressure is increased. Calculation of the energy in the detonation waves is in good agreement with the incident laser energy at different times during the main laser pulse and the long tail. The observation of the incident laser detonation wave accounts for the anomalous energies reported previously. (Auth.)

  4. Internal structure of laser supported detonation waves by two-wavelength Mach-Zehnder interferometer

    International Nuclear Information System (INIS)

    Shimamura, Kohei; Kawamura, Koichi; Fukuda, Akio; Wang Bin; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Hatai, Keigo; Fukui, Akihiro; Arakawa, Yoshihiro

    2011-01-01

    Characteristics of the internal structure of the laser supported detonation (LSD) waves, such as the electron density n e and the electron temperature T e profiles behind the shock wave were measured using a two-wavelength Mach-Zehnder interferometer along with emission spectroscopy. A TEA CO 2 laser with energy of 10 J/pulse produced explosive laser heating in atmospheric air. Results show that the peak values of n e and T e were, respectively, about 2 x 10 24 m -3 and 30 000 K, during the LSD regime. The temporal variation of the laser absorption coefficient profile estimated from the measured properties reveals that the laser energy was absorbed perfectly in a thin layer behind the shock wave during the LSD regime, as predicted by Raizer's LSD model. However, the absorption layer was much thinner than a plasma layer, the situation of which was not considered in Raizer's model. The measured n e at the shock front was not zero while the LSD was supported, which implies that the precursor electrons exist ahead of the shock wave.

  5. Influence of laser-supported detonation waves on metal drilling with pulsed CO2 lasers

    International Nuclear Information System (INIS)

    Stuermer, E.; von Allmen, M.

    1978-01-01

    Drilling of highly reflective metals in an ambient atmosphere with single TEA-CO 2 -laser pulses of fluences between 300 and 6000 J/cm 2 is reported. The drilling process was investigated by measuring the time-resolved laser power reflected specularly from the targets during the interaction and by analyzing the craters produced. Experiments were performed in ambient air, argon, and helium. Target damage was found to be strongly influenced by a laser-supported detonation (LSD) wave in the ambient gas. If the laser fluence exceeded a material-dependent damage threshold (copper: 300 J/cm 2 ), drilling occurred, but the efficiency was inversely related to the duration of the LSD wave. Efficient material removal is possible if the LSD wave can be dissipated within a small fraction of the laser pulse duration. This was achieved by small-F-number focusing of TEM 00 laser pulses of 5-μs duration. Replacing the ambient air at the target by a gas of lower density results in a further significant reduction of LSD-wave lifetime, and a correlated increase of the drilling yield. On copper targets a maximum drilling yield of 10 -5 cm 3 /J was observed in ambient helium at a laser fluence of 1 kJ/cm 2

  6. Numerical Analysis on Thermal Non-Equilibrium Process of Laser-Supported Detonation Wave in Axisymmetric Nozzle

    International Nuclear Information System (INIS)

    Shiraishi, Hiroyuki

    2008-01-01

    Numerical Analyses on Laser-Supported Plasma (LSP) have been performed for researching the mechanism of laser absorption occurring in the laser propulsion system. Above all, Laser-Supported Detonation (LSD), categorized as one type of LSP, is considered as one of the most important phenomena because it can generate high pressure and high temperature for performing highly effective propulsion. For simulating generation and propagation of LSD wave, I have performed thermal non-equilibrium analyses by Navier-stokes equations, using a CO 2 gasdynamic laser into an inert gas, where the most important laser absorption mechanism for LSD propagation is Inverse Bremsstrahlung. As a numerical method, TVD scheme taken into account of real gas effects and thermal non-equilibrium effects by using a 2-temperature model, is applied. In this study, I analyze a LSD wave propagating through a conical nozzle, where an inner space of an actual laser propulsion system is simplified

  7. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    International Nuclear Information System (INIS)

    Gan, Li; Mousen, Cheng; Xiaokang, Li

    2014-01-01

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter

  8. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Li, E-mail: ligan0001@gmail.com; Mousen, Cheng; Xiaokang, Li [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha (China)

    2014-03-15

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

  9. A physical model for laser metal vapour interactions and laser supported detonation waves

    International Nuclear Information System (INIS)

    Liu Chenghai; Pei Wenbing; Yan Jun; Fan Furu

    1990-05-01

    A physical model for laser metal-vapour interactions has been developed in this paper. The model developed by authors has been used to study numerically the Laser Supported Detonation Waves (LSDWs) in vapour in front of metal targets, and some good results about LSDWs, such as ignition mechanism, threshold, propagation law and so on, have been obtained numerically with the model. In the model developed, a assumption for non-equilibrium between electrons and ions has been taken, and the target vapour has been discribed with two-temperature hydrodynamic equations of electrons and ions in the Euler space. The ionization-equilibrium assumption has been taken, and the Saha equations have been solved. The laser energy is absorbed due to inverse bremsstrahlung. Energy exchange between electrons and ions is by Coulomb scattering, and energy exchange between electrons and neutral particles is by way of electron-neutral elastic scattering. Electron and ion (including neutral particle) thermal conductions are taken respectively. The LSDWs threshold obtained is in agreement with experement reasonably, and a power law between LSDWs threshold and laser pulse duration, I th ∞τ p -1/2 , has been obtained. Some useful results about the LSDWs shield effects have also been obtained. In the developping phase of LSDWs, the optical thickness of front of LSDWs may reach 5 ∼ 10 in order of magnitude. It is shown that the LSDWs are able to play a very strong shield role

  10. Detonation Wave Profile

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Laboratory

    2015-12-14

    The Zel’dovich-von Neumann-Doering (ZND) profile of a detonation wave is derived. Two basic assumptions are required: i. An equation of state (EOS) for a partly burned explosive; P(V, e, λ). ii. A burn rate for the reaction progress variable; d/dt λ = R(V, e, λ). For a steady planar detonation wave the reactive flow PDEs can be reduced to ODEs. The detonation wave profile can be determined from an ODE plus algebraic equations for points on the partly burned detonation loci with a specified wave speed. Furthermore, for the CJ detonation speed the end of the reaction zone is sonic. A solution to the reactive flow equations can be constructed with a rarefaction wave following the detonation wave profile. This corresponds to an underdriven detonation wave, and the rarefaction is know as a Taylor wave.

  11. Photoionization in the Precursor of Laser Supported Detonation by Ultraviolet Radiation

    International Nuclear Information System (INIS)

    Shimamura, Kohei; Michigami, Keisuke; Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2011-01-01

    The propagation mechanism of laser-supported detonation (LSD) is important for designing laser propulsion for a detonation type thruster. The purpose of this work to was to confirm that photo-ionization in precursor is the predominant LSD sustainment mechanism. First of all, we tried to investigate the dependency of LSD duration on ambient gas species, air and argon. We took a series of high-speed images using the laser shadow-graphy. Besides, to estimate the UV photons emitted from the plasma, we used plasma emission spectroscopy and determined the electron temperature and density. As a result, the LSD duration of argon plasma and air plasma are 0.7 μs and 0.3 μs, resp. Besides, argon plasma emitted 10 10 to 10 14 photons/seconds, which was higher than air plasma. These results reveal that LSD propagation depends on the photon-contributing photoionization. The threshold photon-emission rate of LSD termination gives the elucidation of the LSD termination condition.

  12. SSS: A code for computing one dimensional shock and detonation wave propagation

    International Nuclear Information System (INIS)

    Sun Chengwei

    1986-01-01

    The one-dimensional hydrodynamic code SSS for shock and detonation wave propagation in inert and reactive media is described. The elastic-plastic-hydrodynamic model and four burn techniques (the Arrhenius law, C-J volume, sharp shock and Forest Fire) are used. There are HOM and JWL options for the state equation of detonation products. Comparing with the SIN code published by LANL, the SSS code has several new options: laser effects, blast waves, diverging and instantaneous detonation waves with arbitrary initiation positions. Two examples are given to compare the SSS and SIN calculations with the experimental data

  13. 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

  14. Gaseous detonation initiation via wave implosion

    Science.gov (United States)

    Jackson, Scott Irving

    Efficient detonation initiation is a topic of intense interest to designers of pulse detonation engines. This experimental work is the first to detonate propane-air mixtures with an imploding detonation wave and to detonate a gas mixture with a non-reflected, imploding shock. In order to do this, a unique device has been developed that is capable of generating an imploding toroidal detonation wave inside of a tube from a single ignition point without any obstruction to the tube flow path. As part of this study, an initiator that creates a large-aspect-ratio planar detonation wave in gas-phase explosive from a single ignition point has also been developed. The effectiveness of our initiation devices has been evaluated. The minimum energy required by the imploding shock for initiation was determined to scale linearly with the induction zone length, indicating the presence of a planar initiation mode. The imploding toroidal detonation initiator was found to be more effective at detonation initiation than the imploding shock initiator, using a comparable energy input to that of current initiator tubes.

  15. Simulation of laser interaction with ablative plasma and hydrodynamic behavior of laser supported plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tong Huifeng; Yuan Hong [Institute of Fluid Physics, Chinese Academy of Engineering Physics, P.O. Box 919-101, Mianyang, Sichuan 621900 (China); Tang Zhiping [CAS Key Laboratory for Mechanical Behavior and Design of Materials, Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei 230026 (China)

    2013-01-28

    When an intense laser beam irradiates on a solid target, ambient air ionizes and becomes plasma, while part of the target rises in temperature, melts, vaporizes, ionizes, and yet becomes plasma. A general Godunov finite difference scheme WENO (Weighted Essentially Non-Oscillatory Scheme) with fifth-order accuracy is used to simulate 2-dimensional axis symmetrical laser-supported plasma flow field in the process of laser ablation. The model of the calculation of ionization degree of plasma and the interaction between laser beam and plasma are considered in the simulation. The numerical simulations obtain the profiles of temperature, density, and velocity at different times which show the evolvement of the ablative plasma. The simulated results show that the laser energy is strongly absorbed by plasma on target surface and that the velocity of laser supported detonation (LSD) wave is half of the ideal LSD value derived from Chapman-Jouguet detonation theory.

  16. Shock wave interactions with detonable clouds

    International Nuclear Information System (INIS)

    Ripley, R.C.; Josey, T.; Donahue, L.; Whitehouse, D.R.

    2004-01-01

    This paper presents results from the numerical simulation of compressible multi-species gases in an unstructured mesh CFD code called Chinook. Multiple species gases are significant to a wide range of CFD applications that involve chemical reactions, in particular detonation. The purpose of this paper is to investigate the interaction of shock waves with localized regions of reactive and non-reactive gas species. Test cases are chosen to highlight shock reflection and acceleration through combustion products resulting from the detonation of an explosive charge, and detonation wave propagation through a fuel-air cloud. Computations are performed in a 2D axi-symmetric framework. (author)

  17. Rotary wave-ejector enhanced pulse detonation engine

    Science.gov (United States)

    Nalim, M. R.; Izzy, Z. A.; Akbari, P.

    2012-01-01

    The use of a non-steady ejector based on wave rotor technology is modeled for pulse detonation engine performance improvement and for compatibility with turbomachinery components in hybrid propulsion systems. The rotary wave ejector device integrates a pulse detonation process with an efficient momentum transfer process in specially shaped channels of a single wave-rotor component. In this paper, a quasi-one-dimensional numerical model is developed to help design the basic geometry and operating parameters of the device. The unsteady combustion and flow processes are simulated and compared with a baseline PDE without ejector enhancement. A preliminary performance assessment is presented for the wave ejector configuration, considering the effect of key geometric parameters, which are selected for high specific impulse. It is shown that the rotary wave ejector concept has significant potential for thrust augmentation relative to a basic pulse detonation engine.

  18. Shock wave and flame front induced detonation in a rapid compression machine

    Science.gov (United States)

    Wang, Y.; Qi, Y.; Xiang, S.; Mével, R.; Wang, Z.

    2018-05-01

    The present study focuses on one mode of detonation initiation observed in a rapid compression machine (RCM). This mode is referred to as shock wave and flame front-induced detonation (SWFID). Experimental high-speed imaging and two-dimensional numerical simulations with skeletal chemistry are combined to unravel the dominant steps of detonation initiation under SWFID conditions. It is shown that the interaction between the shock wave generated by the end-gas auto-ignition and the spherical flame creates a region of high pressure and temperature which enables the acceleration of the flame front and the detonation onset. The experimental observation lacks adequate spatial and temporal resolution despite good reproducibility of the detonation onset. Based on the numerical results, phenomenological interpretation of the event within the framework of shock wave refraction indicates that the formation of a free-precursor shock wave at the transition between regular and irregular refraction may be responsible for detonation onset. The present results along with previous findings on shock wave reflection-induced detonation in the RCM indicate that super-knock occurs after the interaction of the shock wave generated by end-gas auto-ignition with the RCM walls, preignition flame, or another shock wave.

  19. Diagnostic Imaging of Detonation Waves for Waveshaper Development

    Science.gov (United States)

    2009-07-01

    it is difficult to determine the depth of the detonation wave (due to the translucency of the sensitised nitromethane) and when it reaches the bottom...Charges For Use against Concrete Targerts, DSTO Client Report, DSTO-CR-2005-0164, 2005. [2] M. J. Murphy, R. M. Kuklo, T. A. Rambur, L. L. Switzer & M...Resnyansky, S. A. Weckert & T. Delaney, Shaping of Detonation Waves in Shaped Charges for Use against Concrete Targets: Part II, in preparation

  20. Shock wave science and technology reference library. Vol. 4. Heterogeneous detonation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan (ed.) [Defence Research and Development Canada, Suffield, AB (Canada)

    2009-07-01

    This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov). Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a timely reference, for graduate students as well as professional scientists and engineers, by laying out the foundations and discussing the latest developments including yet unresolved challenging problems. (orig.)

  1. Supporting Structure of the LSD Wave in an Energy Absorption Perspective

    International Nuclear Information System (INIS)

    Fukui, Akihiro; Hatai, Keigo; Cho, Shinatora; Arakawa, Yoshihiro; Komurasaki, Kimiya

    2008-01-01

    In Repetitively Pulsed (RP) Laser Propulsion, laser energy irradiated to a vehicle is converted to blast wave enthalpy during the Laser Supported Detonation (LSD) regime. Based on the measured post-LSD electron number density profiles by two-wavelength Mach Zehnder interferometer in a line-focusing optics, electron temperature and absorption coefficient were estimated assuming Local Thermal Equilibrium. A 10J/pulse CO 2 laser was used. As a result, laser absorption was found completed in the layer between the shock wave and the electron density peak. Although the LSD-termination timing was not clear from the shock-front/ionization-front separation in the shadowgraph images, there observed drastic changes in the absorption layer thickness from 0.2 mm to 0.5 mm and in the peak heating rate from 12-17x10 13 kW/m 3 to 5x10 13 kW/m 3 at the termination

  2. Research on laser detonation pulse circuit with low-power based on super capacitor

    Science.gov (United States)

    Wang, Hao-yu; Hong, Jin; He, Aifeng; Jing, Bo; Cao, Chun-qiang; Ma, Yue; Chu, En-yi; Hu, Ya-dong

    2018-03-01

    According to the demand of laser initiating device miniaturization and low power consumption of weapon system, research on the low power pulse laser detonation circuit with super capacitor. Established a dynamic model of laser output based on super capacitance storage capacity, discharge voltage and programmable output pulse width. The output performance of the super capacitor under different energy storage capacity and discharge voltage is obtained by simulation. The experimental test system was set up, and the laser diode of low power pulsed laser detonation circuit was tested and the laser output waveform of laser diode in different energy storage capacity and discharge voltage was collected. Experiments show that low power pulse laser detonation based on super capacitor energy storage circuit discharge with high efficiency, good transient performance, for a low power consumption requirement, for laser detonation system and low power consumption and provide reference light miniaturization of engineering practice.

  3. Exhaust Gas Emissions from a Rotating Detonation-wave Engine

    Science.gov (United States)

    Kailasanath, Kazhikathra; Schwer, Douglas

    2015-11-01

    Rotating detonation-wave engines (RDE) are a form of continuous detonation-wave engines. They potentially provide further gains in performance than an intermittent or pulsed detonation-wave engine (PDE). The overall flow field in an idealized RDE, primarily consisting of two concentric cylinders, has been discussed in previous meetings. Because of the high pressures involved and the lack of adequate reaction mechanisms for this regime, previous simulations have typically used simplified chemistry models. However, understanding the exhaust species concentrations in propulsion devices is important for both performance considerations as well as estimating pollutant emissions. Progress towards addressing this need will be discussed in this talk. In this approach, an induction parameter model is used for simulating the detonation but a more detailed finite-chemistry model including NOx chemistry is used in the expansion flow region, where the pressures are lower and the uncertainties in the chemistry model are greatly reduced. Results show that overall radical concentrations in the exhaust flow are substantially lower than from earlier predictions with simplified models. The performance of a baseline hydrogen/air RDE increased from 4940 s to 5000 s with the expansion flow chemistry, due to recombination of radicals and more production of H2O, resulting in additional heat release. Work sponsored by the Office of Naval Research.

  4. Standing detonation wave engine

    KAUST Repository

    Kasimov, Aslan

    2015-01-01

    A detonation engine can detonate a mixture of fuel and oxidizer within a cylindrical detonation region to produce work. The detonation engine can have a first and a second inlet having ends fluidly connected from tanks to the detonation engine

  5. Photographic investigation into the mechanism of combustion in irregular detonation waves

    Science.gov (United States)

    Kiyanda, C. B.; Higgins, A. J.

    2013-03-01

    Irregular detonations are supersonic combustion waves in which the inherent multi-dimensional structure is highly variable. In such waves, it is questionable whether auto-ignition induced by shock compression is the only combustion mechanism present. Through the use of high-speed schlieren and self-emitted light photography, the velocity of the different components of detonation waves in a {{ CH}}_4+2{ O}_2 mixture is analyzed. The observed burn-out of unreacted pockets is hypothesized to be due to turbulent combustion.

  6. The development of laser ignited deflagration-to-detonation transition (DDT) detonators and pyrotechnic actuators

    Energy Technology Data Exchange (ETDEWEB)

    Merson, J.A.; Salas, F.J.; Harlan, J.G.

    1993-11-01

    The use of laser ignited explosive components has been recognized as a safety enhancement over existing electrical explosive devices (EEDs). Sandia has been pursuing the development of optical ordnance for many years with recent emphasis on developing optical deflagration-to-detonation (DDT) detonators and pyrotechnic actuators. These low energy optical ordnance devices can be ignited with either a semiconductor diode laser, laser diode arrays or a solid state rod laser. By using a semiconductor laser diode, the safety improvement can be made without sacrificing performance since the input energy required for the laser diode and the explosive output are similar to existing electrical systems. The use of higher powered laser diode arrays or rod lasers may have advantages in fast DDT applications or lossy optical environments such as long fiber applications and applications with numerous optical connectors. Recent results from our continued study of optical ignition of explosive and pyrotechnic materials are presented. These areas of investigation can be separated into three different margin categories: (1) the margin relative to intended inputs (i.e. powder performance as a function of laser input variation), (2) the margin relative to anticipated environments (i.e. powder performance as a function of thermal environment variation), and (3) the margin relative to unintended environments (i.e. responses to abnormal environments or safety).

  7. Critical deflagration waves leading to detonation onset under different boundary conditions

    International Nuclear Information System (INIS)

    Lin Wei; Zhou Jin; Lin Zhi-Yong; Fan Xiao-Hua

    2015-01-01

    High-speed turbulent critical deflagration waves before detonation onset in H 2 –air mixture propagated into a square cross section channel, which was assembled of optional rigid rough, rigid smooth, or flexible walls. The corresponding propagation characteristic and the influence of the wall boundaries on the propagation were investigated via high-speed shadowgraph and a high-frequency pressure sampling system. As a comprehensive supplement to the different walls effect investigation, the effect of porous absorbing walls on the detonation propagation was also investigated via smoke foils and the high-frequency pressure sampling system. Results are as follows. In the critical deflagration stage, the leading shock and the closely following turbulent flame front travel at a speed of nearly half the CJ detonation velocity. In the preheated zone, a zonary flame arises from the overlapping part of the boundary layer and the pressure waves, and then merges into the mainstream flame. Among these wall boundary conditions, the rigid rough wall plays a most positive role in the formation of the zonary flame and thus accelerates the transition of the deflagration to detonation (DDT), which is due to the boost of the boundary layer growth and the pressure wave reflection. Even though the flexible wall is not conducive to the pressure wave reflection, it brings out a faster boundary layer growth, which plays a more significant role in the zonary flame formation. Additionally, the porous absorbing wall absorbs the transverse wave and yields detonation decay and velocity deficit. After the absorbing wall, below some low initial pressure conditions, no re-initiation occurs and the deflagration propagates in critical deflagration for a relatively long distance. (paper)

  8. Standing detonation wave engine

    KAUST Repository

    Kasimov, Aslan

    2015-10-08

    A detonation engine can detonate a mixture of fuel and oxidizer within a cylindrical detonation region to produce work. The detonation engine can have a first and a second inlet having ends fluidly connected from tanks to the detonation engine. The first and second inlets can be aligned along a common axis. The inlets can be connected to nozzles and a separator can be positioned between the nozzles and along the common axis.

  9. Laser-supported ionization wave in under-dense gases and foams

    International Nuclear Information System (INIS)

    Gus'kov, S. Yu.; Limpouch, J.; Nicolaie, Ph.; Tikhonchuk, V. T.

    2011-01-01

    Propagation of laser-supported ionization wave in homogeneous and porous materials with a mean density less than the critical plasma density is studied theoretically in the one-dimensional geometry. It is shown that the velocity of the ionization wave in a foam is significantly decreased in comparison with the similar wave in a homogeneous fully ionized plasma of the same density. That difference is attributed to the ionization and hydro-homogenization processes forming an under-critical density environment in the front of ionization wave. The rate of energy transfer from laser to plasma is found to be in a good agreement with available experimental data.

  10. Laser image recording on detonation nanodiamond films

    International Nuclear Information System (INIS)

    Mikheev, G M; Mikheev, K G; Mogileva, T N; Puzyr, A P; Bondar, V S

    2014-01-01

    A focused He – Ne laser beam is shown to cause local blackening of semitransparent detonation nanodiamond (DND) films at incident power densities above 600 W cm -2 . Data obtained with a Raman spectrometer and low-power 632.8-nm laser source indicate that the blackening is accompanied by a decrease in broadband background luminescence and emergence of sharp Raman peaks corresponding to the structures of nanodiamond and sp 2 carbon. The feasibility of image recording on DND films by a focused He – Ne laser beam is demonstrated. (letters)

  11. Laser image recording on detonation nanodiamond films

    Energy Technology Data Exchange (ETDEWEB)

    Mikheev, G M; Mikheev, K G; Mogileva, T N [Institute of Mechanics, Ural Branch of the Russian Academy of Sciences, Izhevsk (Russian Federation); Puzyr, A P; Bondar, V S [Institute of Biophysics, Siberian Branch of the Russian Academy of Sciences (Russian Federation)

    2014-01-31

    A focused He – Ne laser beam is shown to cause local blackening of semitransparent detonation nanodiamond (DND) films at incident power densities above 600 W cm{sup -2}. Data obtained with a Raman spectrometer and low-power 632.8-nm laser source indicate that the blackening is accompanied by a decrease in broadband background luminescence and emergence of sharp Raman peaks corresponding to the structures of nanodiamond and sp{sup 2} carbon. The feasibility of image recording on DND films by a focused He – Ne laser beam is demonstrated. (letters)

  12. 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.

  13. Characterization of laser-induced plasmas as a complement to high-explosive large-scale detonations

    Directory of Open Access Journals (Sweden)

    Clare Kimblin

    2017-09-01

    Full Text Available Experimental investigations into the characteristics of laser-induced plasmas indicate that LIBS provides a relatively inexpensive and easily replicable laboratory technique to isolate and measure reactions germane to understanding aspects of high-explosive detonations under controlled conditions. Spectral signatures and derived physical parameters following laser ablation of aluminum, graphite and laser-sparked air are examined as they relate to those observed following detonation of high explosives and as they relate to shocked air. Laser-induced breakdown spectroscopy (LIBS reliably correlates reactions involving atomic Al and aluminum monoxide (AlO with respect to both emission spectra and temperatures, as compared to small- and large-scale high-explosive detonations. Atomic Al and AlO resulting from laser ablation and a cited small-scale study, decay within ∼10-5 s, roughly 100 times faster than the Al and AlO decay rates (∼10-3 s observed following the large-scale detonation of an Al-encased explosive. Temperatures and species produced in laser-sparked air are compared to those produced with laser ablated graphite in air. With graphite present, CN is dominant relative to N2+. In studies where the height of the ablating laser’s focus was altered relative to the surface of the graphite substrate, CN concentration was found to decrease with laser focus below the graphite surface, indicating that laser intensity is a critical factor in the production of CN, via reactive nitrogen.

  14. The Universal Role of Tubulence in the Propagation of Strong Shocks and Detonation Waves

    Science.gov (United States)

    Lee, John H.

    2001-06-01

    The passage of a strong shock wave usually results in irreversible physical and chemical changes in the medium. If the chemical reactions are sufficiently exothermic, the shock wave can be self-propagating, i.e., sustained by the chemical energy release via the expansion work of the reaction products. Although shocks and detonations can be globally stable and propagate at constant velocities (in the direction of motion), their structure may be highly unstable and exhibit large hydrodynamic fluctuations, i.e., turbulence. Recent investigations on plastic deformation of polycrystalline material behind shock waves have revealed particle velocity dispersion at the mesoscopic level, a result of vortical rotational motion similar to that of turbulent fluid flows at high Reynolds number.1 Strong ionizing shocks in noble gases2, as well as dissociating shock waves in carbon dioxide,3 also demonstrate a turbulent density fluctuation in the non-equilibrium shock transition zone. Perhaps the most thoroughly investigated unstable structure is that of detonation waves in gaseous explosives.4 Detonation waves in liquid explosives such as nitromethane also take on similar unstable structure as gaseous detonations.5 There are also indications that detonations in solid explosives have a similar unsteady structure under certain conditions. Thus, it appears that it is more of a rule than an exception that the structure of strong shocks and detonations are unstable and exhibit turbulent-like fluctuations as improved diagnostics now permit us to look more closely at the meso- and micro-levels. Increasing attention is now devoted to the understanding of the shock waves at the micro-scale level in recent years. This is motivated by the need to formulate physical and chemical models that contain the correct physics capable of describing quantitatively the shock transition process. It should be noted that, in spite of its unstable 3-D structure, the steady 1-D conservation laws (in the

  15. Controlling the position of a stabilized detonation wave in a supersonic gas mixture flow in a plane channel

    Science.gov (United States)

    Levin, V. A.; Zhuravskaya, T. A.

    2017-03-01

    Stabilization of a detonation wave in a stoichiometric hydrogen-air mixture flowing at a supersonic velocity into a plane symmetric channel with constriction has been studied in the framework of a detailed kinetic mechanism of the chemical interaction. Conditions ensuring the formation of a thrust-producing f low with a stabilized detonation wave in the channel are determined. The inf luence of the inf low Mach number, dustiness of the combustible gas mixture supplied to the channel, and output cross-section size on the position of a stabilized detonation wave in the f low has been analyzed with a view to increasing the efficiency of detonation combustion of the gas mixture. It is established that thrust-producing flow with a stabilized detonation wave can be formed in the channel without any energy consumption.

  16. Necessary conditions for the initiation and propagation of nuclear-detonation waves in plane atmospheres

    International Nuclear Information System (INIS)

    Weaver, T.A.; Wood, L.

    1979-01-01

    The basic conditions for the initiation of a nuclear-detonation wave in an atmosphere having plane symmetry (e.g., a thin, layered fluid envelope on a planet or star) are developed. Two classes of such a detonation are identified: those in which the temperature of the plasma is comparable to that of the electromagnetic radiation permeating it, and those in which the temperature of the plasma is much higher. Necessary conditions are developed for the propagation of such detonation waves for an arbitrarily great distance. The contribution of fusion chain reactions to these processes is evaluated. By means of these considerations, it is shown that neither the atmosphere nor oceans of the Earth may be made to undergo propagating nuclear detonation under any circumstances

  17. Light-initiated detonation systems

    Science.gov (United States)

    Cooper, Stafford S.; Malone, Philip G.; Bartholomew, Stephen W.; Necker, William J.

    1986-09-01

    Numerous light sources could be employed in detonation systems, but lasers have the most efficient coupling to optical fibers and can generate energetic light pulses required for detonation. Flash lamp-pumped, solid state lasers are presently the most useful light source for explosive initiation. Laser diodes in current production cannot generate enough energy for practical applications. The most useful optical fiber for blast line application is a step index fiber with a large core-to-cladding ratio. The large core minimizes energy losses due to misalignment core of fibers in connectors. Couplers that involve mechanically crimped connectors and cleaved fibers, rather than the epoxy-cemented connectors with polished fibers, provide superior energy transmission due to the reduced carbonization at the fiber end. Detonators for optical initiation systems are similar in basic construction to those employed in electrical initiation systems. Explosive and pyrotechnic charges can also be similar. Either primary or secondary explosives can be initiated in present laser-based systems. Two laser detonation systems are presently accessible; a multiple-shot laser with a single-shot, single fiber system designed for use with detonators containing primary explosives. Additional research related to development of low-energy, photoreactive detonators, continuity checking techniques and improved connectors and fibers can produce significant improvements in presently fielded systems.

  18. Combustion, detonation, shock waves. Proceedings of the Zel'dovich memorial - International conference on combustion. Volume 1

    International Nuclear Information System (INIS)

    Merzhanov, A.G.; Frolov, S.M.

    1995-01-01

    This book contains lectures by the experts in various fields of modern research in combustion, detonation and shock waves, presented at the Zel'dovich memorial - International conference on combustion dedicated to the 80-th birthday of academician Ya.B. Zel'dovich. There are eight chapters discussing the state-of-the-art in combustion kinetics, ignition and steady-state flame propagation, diffusion and heterogeneous combustion, turbulent combustion, unsteady combustion, detonation, combustion and detonation analogies, intense shock waves and extreme states of matter [ru

  19. Chemical Kinetics in the expansion flow field of a rotating detonation-wave engine

    Science.gov (United States)

    Kailasanath, Kazhikathra; Schwer, Douglas

    2014-11-01

    Rotating detonation-wave engines (RDE) are a form of continuous detonation-wave engines. They potentially provide further gains in performance than an intermittent or pulsed detonation-wave engine (PDE). The overall flow field in an idealized RDE, primarily consisting of two concentric cylinders, has been discussed in previous meetings. Because of the high pressures involved and the lack of adequate reaction mechanisms for this regime, previous simulations have typically used simplified chemistry models. However, understanding the exhaust species concentrations in propulsion devices is important for both performance considerations as well as estimating pollutant emissions. A key step towards addressing this need will be discussed in this talk. In this approach, an induction parameter model is used for simulating the detonation but a more detailed finite-chemistry model is used in the expansion flow region, where the pressures are lower and the uncertainties in the chemistry model are greatly reduced. Results show that overall radical concentrations in the exhaust flow are substantially lower than from earlier predictions with simplified models. The performance of a baseline hydrogen/air RDE increased from 4940 s to 5000 s with the expansion flow chemistry, due to recombination of radicals and more production of H2O, resulting in additional heat release.

  20. Numerical Study of Detonation Wave Propagation in the Variable Cross-Section Channel Using Unstructured Computational Grids

    Directory of Open Access Journals (Sweden)

    Alexander Lopato

    2018-01-01

    Full Text Available The work is dedicated to the numerical study of detonation wave initiation and propagation in the variable cross-section axisymmetric channel filled with the model hydrogen-air mixture. The channel models the large-scale device for the utilization of worn-out tires. Mathematical model is based on two-dimensional axisymmetric Euler equations supplemented by global chemical kinetics model. The finite volume computational algorithm of the second approximation order for the calculation of two-dimensional flows with detonation waves on fully unstructured grids with triangular cells is developed. Three geometrical configurations of the channel are investigated, each with its own degree of the divergence of the conical part of the channel from the point of view of the pressure from the detonation wave on the end wall of the channel. The problem in consideration relates to the problem of waste recycling in the devices based on the detonation combustion of the fuel.

  1. Experimental study on incident wave speed and the mechanisms of deflagration-to-detonation transition in a bent geometry

    Science.gov (United States)

    Li, L.; Li, J.; Teo, C. J.; Chang, P. H.; Khoo, B. C.

    2018-03-01

    The study of deflagration-to-detonation transition (DDT) in bent tubes is important with many potential applications including fuel pipeline and mine tunnel designs for explosion prevention and detonation engines for propulsion. The aim of this study is to exploit low-speed incident shock waves for DDT using an S-shaped geometry and investigate its effectiveness as a DDT enhancement device. Experiments were conducted in a valveless detonation chamber using ethylene-air mixture at room temperature and pressure (303 K, 1 bar). High-speed Schlieren photography was employed to keep track of the wave dynamic evolution. Results showed that waves with velocity as low as 500 m/s can experience a successful DDT process through this S-shaped geometry. To better understand the mechanism, clear images of local explosion processes were captured in either the first curved section or the second curved section depending on the inlet wave velocity, thus proving that this S-shaped tube can act as a two-stage device for DDT. Owing to the curved wall structure, the passing wave was observed to undergo a continuous compression phase which could ignite the local unburnt mixture and finally lead to a local explosion and a detonation transition. Additionally, the phenomenon of shock-vortex interaction near the wave diffraction region was also found to play an important role in the whole process. It was recorded that this interaction could not only result in local head-on reflection of the reflected wave on the wall that could ignite the local mixture, and it could also contribute to the recoupling of the shock-flame complex when a detonation wave is successfully formed in the first curved section.

  2. Comparison of detailed and reduced kinetics mechanisms of silane oxidation in the basis of detonation wave structure problem

    Science.gov (United States)

    Fedorov, A. V.; Tropin, D. A.; Fomin, P. A.

    2018-03-01

    The paper deals with the problem of the structure of detonation waves in the silane-air mixture within the framework of mathematical model of a nonequilibrium gas dynamics. Detailed kinetic scheme of silane oxidation as well as the newly developed reduced kinetic model of detonation combustion of silane are used. On its basis the detonation wave (DW) structure in stoichiometric silane - air mixture and dependences of Chapman-Jouguet parameters of mixture on stoichiometric ratio between the fuel (silane) and an oxidizer (air) were obtained.

  3. Thermonuclear detonation

    International Nuclear Information System (INIS)

    Feoktistov, L.P.

    1998-01-01

    The characteristics of, and energy transfer mechanisms involved in, thermonuclear detonation are discussed. What makes the fundamental difference between thermonuclear and chemical detonation is that the former has a high specific energy release and can therefore be employed for preliminary compressing the thermonuclear mixture ahead of the burning wave. Consequently, with moderate (mega joule) initiation energies, a steady-state detonation laboratory experiment with unlimited energy multiplication becomes a possibility

  4. Thermonuclear detonation

    International Nuclear Information System (INIS)

    Feoktistov, L P

    1998-01-01

    The characteristics of, and energy transfer mechanisms involved in, thermonuclear detonation are discussed. What makes the fundamental difference between thermonuclear and chemical detonation is that the former has a high specific energy release and can therefore be employed for preliminarily compressing the thermonuclear mixture ahead of the burning wave. Consequently, with moderate (megajoule) initiation energies, a steady-state detonation laboratory experiment with unlimited energy multiplication becomes a possibility. (from the history of physics)

  5. Utilizing Near-IR Tunable Laser Absorption Spectroscopy to Study Detonation and Combustion Systems

    Science.gov (United States)

    2014-03-27

    A Hencken burner, Rotating Detonation Engine ( RDE ), and a detonation tube were studied using a Time-Devision Multiplexed Tunable Diode Laser...for the three systems. Velocity was calculated for the RDE system using the Doppler shift of the spectral lines. To perform the calculations necessary...however, the CH4 flame did not match as well. The exhaust of the RDE was studied at various equivalence ratios using a hydrogen-air mixture (H2-air

  6. Qualitative and Asymptotic Theory of Detonations

    KAUST Repository

    Faria, Luiz

    2014-11-09

    Shock waves in reactive media possess very rich dynamics: from formation of cells in multiple dimensions to oscillating shock fronts in one-dimension. Because of the extreme complexity of the equations of combustion theory, most of the current understanding of unstable detonation waves relies on extensive numerical simulations of the reactive compressible Euler/Navier-Stokes equations. Attempts at a simplified theory have been made in the past, most of which are very successful in describing steady detonation waves. In this work we focus on obtaining simplified theories capable of capturing not only the steady, but also the unsteady behavior of detonation waves. The first part of this thesis is focused on qualitative theories of detonation, where ad hoc models are proposed and analyzed. We show that equations as simple as a forced Burgers equation can capture most of the complex phenomena observed in detonations. In the second part of this thesis we focus on rational theories, and derive a weakly nonlinear model of multi-dimensional detonations. We also show, by analysis and numerical simulations, that the asymptotic equations provide good quantitative predictions.

  7. Ultrafast Fiber Bragg Grating Interrogation for Sensing in Detonation and Shock Wave Experiments.

    Science.gov (United States)

    Rodriguez, George; Gilbertson, Steve M

    2017-01-27

    Chirped fiber Bragg grating (CFBG) sensors coupled to high speed interrogation systems are described as robust diagnostic approaches to monitoring shock wave and detonation front propagation tracking events for use in high energy density shock physics applications. Taking advantage of the linear distributed spatial encoding of the spectral band in single-mode CFBGs, embedded fiber systems and associated photonic interrogation methodologies are shown as an effective approach to sensing shock and detonation-driven loading processes along the CFBG length. Two approaches, one that detects spectral changes in the integrated spectrum of the CFBG and another coherent pulse interrogation approach that fully resolves its spectral response, shows that 100-MHz-1-GHz interrogation rates are possible with spatial resolution along the CFBG in the 50 µm to sub-millimeter range depending on the combination of CFBG parameters (i.e., length, chirp rate, spectrum) and interrogator design specifics. Results from several dynamic tests are used to demonstrate the performance of these high speed systems for shock and detonation propagation tracking under strong and weak shock pressure loading: (1) linear detonation front tracking in the plastic bonded explosive (PBX) PBX-9501; (2) tracking of radial decaying shock with crossover to non-destructive CFBG response; (3) shock wave tracking along an aluminum cylinder wall under weak loading accompanied by dynamic strain effects in the CFBG sensor.

  8. Initiation of Gaseous Detonation by Conical Projectiles

    Science.gov (United States)

    Verreault, Jimmy

    Initiation and stabilization of detonation by hypersonic conical projectiles launched into combustible gas mixtures is investigated. This phenomenon must be understood for the design and optimization of specific hypersonic propulsion devices, such as the oblique detonation wave engine and the ram accelerator. The criteria for detonation initiation by a projectile is also related to fundamental aspects of detonation research, such as the requirement for direct initiation of a detonation by a blast wave. Experimental results of this problem also offer useful references for validation of numerical and theoretical modeling. Projectiles with cone half angles varying from 15° to 60° were launched into stoichiometric mixtures of hydrogen/oxygen with 70% argon dilution at initial pressures between 10 and 200 kPa. The projectiles were launched from a combustion-driven gas gun at velocities up to 2.2 km/s (corresponding to 133% of the Chapman Jouguet velocity). Pictures of the flowfields generated by the projectiles were taken via Schlieren photography. Five combustion regimes were observed about the projectile ranging from prompt and delayed oblique detonation wave formation, combustion instabilities, a wave splitting, and an inert shock wave. Two types of transition from the prompt oblique detonation wave regime to the inert shock regime were observed. The first (the delayed oblique detonation wave regime) showed an inert shock attached to the tip of the projectile followed by a sharp kink at the onset of an oblique detonation wave; this regime occurred by decreasing the cone angle at high mixture pressures. The second (the combustion instabilities regime) exhibited large density gradients due to combustion ignition and quenching phenomena; this regime occurred by decreasing the mixture pressure at large cone angles. A number of theoretical models were considered to predict critical conditions for the initiation of oblique detonations. The Lee-Vasiljev model agreed

  9. Reduced detonation kinetics and detonation structure in one- and multi-fuel gaseous mixtures

    Science.gov (United States)

    Fomin, P. A.; Trotsyuk, A. V.; Vasil'ev, A. A.

    2017-10-01

    Two-step approximate models of chemical kinetics of detonation combustion of (i) one-fuel (CH4/air) and (ii) multi-fuel gaseous mixtures (CH4/H2/air and CH4/CO/air) are developed for the first time. The models for multi-fuel mixtures are proposed for the first time. Owing to the simplicity and high accuracy, the models can be used in multi-dimensional numerical calculations of detonation waves in corresponding gaseous mixtures. The models are in consistent with the second law of thermodynamics and Le Chatelier’s principle. Constants of the models have a clear physical meaning. Advantages of the kinetic model for detonation combustion of methane has been demonstrated via numerical calculations of a two-dimensional structure of the detonation wave in a stoichiometric and fuel-rich methane-air mixtures and stoichiometric methane-oxygen mixture. The dominant size of the detonation cell, determines in calculations, is in good agreement with all known experimental data.

  10. Detonation Jet Engine. Part 2--Construction Features

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. Detonation engines of various concepts, pulse detonation, rotational and engine with stationary detonation wave, are reviewed. Main trends in detonation engine development are discussed. The most important works that carried out…

  11. Confined detonations with cylindrical and spherical symmetry

    International Nuclear Information System (INIS)

    Linan, A.; Lecuona, A.

    1979-01-01

    An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/pγ-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs

  12. Influence of sweeping detonation-wave loading on damage evolution during spallation loading of tantalum in both a planar and curved geometry

    Energy Technology Data Exchange (ETDEWEB)

    Gray, George Thompson III [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hull, Lawrence Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Livescu, Veronica [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Faulkner, James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Briggs, Matthew E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meyer, Ross Keith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Andrews, Heather Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hare, Steven John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jakulewicz, Micah Shawn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shinas, Michael A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-30

    Widespread research over the past five decades has provided a wealth of experimental data and insight concerning the shock hardening, damage evolution, and the spallation response of materials subjected to square-topped shock-wave loading profiles. However, fewer quantitative studies have been conducted on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (unsupported shocks) loading on the shock hardening, damage evolution, or spallation response of materials. Systematic studies quantifying the effect of sweeping-detonation wave loading are yet sparser. In this study, the damage evolution and spallation response of Ta is shown to be critically dependent on the peak shock stress, the geometry of the sample (flat or curved plate geometry), and the shock obliquity during sweeping-detonation-wave shock loading. Sweepingwave loading in the flat-plate geometry is observed to: a) yield a lower spall strength than previously documented for 1-D supported-shock-wave loading, b) exhibit increased shock hardening as a function of increasing obliquity, and c) lead to an increased incidence of deformation twin formation with increasing shock obliquity. Sweeping-wave loading of a 10 cm radius curved Ta plate is observed to: a) lead to an increase in the shear stress as a function of increasing obliquity, b) display a more developed level of damage evolution, extensive voids and coalescence, and lower spall strength with obliquity in the curved plate than seen in the flat-plate sweeping-detonation wave loading for an equivalent HE loading, and c) no increased propensity for deformation twin formation with increasing obliquity as seen in the flat-plate geometry. The overall observations comparing and contrasting the flat versus curved sweeping-wave spall experiments with 1D loaded spallation behavior suggests a coupled influence of obliquity and geometry on dynamic shock-induced damage evolution and spall strength. Coupled experimental and modeling research

  13. A novel method for the measurement of the von Neumann spike in detonating high explosives

    Science.gov (United States)

    Sollier, A.; Bouyer, V.; Hébert, P.; Doucet, M.

    2016-06-01

    We present detonation wave profiles measured in T2 (97 wt. % TATB) and TX1 (52 wt. % TATB and 45 wt. % HMX) high explosives. The experiments consisted in initiating a detonation wave in a 15 mm diameter cylinder of explosive using an explosive wire detonator and an explosive booster. Free surface velocity wave profiles were measured at the explosive/air interface using a Photon Doppler Velocimetry system. We demonstrate that a comparison of these free surface wave profiles with those measured at explosive/window interfaces in similar conditions allows to bracket the von Neumann spike in a narrow range. For T2, our measurements show that the spike pressure lies between 35.9 and 40.1 GPa, whereas for TX1, it lies between 42.3 and 47.0 GPa. The numerical simulations performed in support to these measurements show that they can be used to calibrate reactive burn models and also to check the accuracy of the detonation products equation of state at low pressure.

  14. Effects of Injection Scheme on Rotating Detonation Engine Operation

    Science.gov (United States)

    Chacon, Fabian; Duvall, James; Gamba, Mirko

    2017-11-01

    In this work, we experimentally investigate the operation and performance characteristics of a rotating detonation engine (RDE) operated with different fuel injection schemes and operating conditions. In particular, we investigate the detonation and operation characteristics produced with an axial flow injector configuration and semi-impinging injector configurations. These are compared to the characteristics produced with a canonical radial injection system (AFRL injector). Each type produces a different flowfield and mixture distribution, leading to a different detonation initiation, injector dynamic response, and combustor pressure rise. By using a combination of diagnostics, we quantify the pressure loses and gains in the system, the ability to maintain detonation over a range of operating points, and the coupling between the detonation and the air/fuel feed lines. We particularly focus on how this coupling affects both the stability and the performance of the detonation wave. This work is supported by the DOE/UTSR program under project DE-FE0025315.

  15. Flow Visualization of a Rotating Detonation Engine

    Science.gov (United States)

    2016-10-05

    SUPPLEMENTARY NOTES 14. ABSTRACT The rotating detonation engine ( RDE ) is a propulsion system that obtains thrust using continuously existing...2014 – 12/4/2015 Summary: The rotating detonation engine ( RDE ) is a propulsion system that obtains thrust using continuously existing detonation...structure. Studies have been conducted on rotating detonation engines ( RDE ) that obtain thrust from the continuously propagating detonation waves in the

  16. Comparative study of the expansion dynamics of laser-driven plasma and shock wave in in-air and underwater ablation regimes

    Science.gov (United States)

    Nguyen, Thao T. P.; Tanabe, Rie; Ito, Yoshiro

    2018-03-01

    We compared the expansion characteristics of the plasma plumes and shock waves generated in laser-induced shock process between the two ablation regimes: in air and under water. The observation was made from the initial moment when the laser pulse hit the target until 1.5 μs. The shock processes were driven by focusing a single laser pulse (1064 nm, FWHM = 13 ns) onto the surface of epoxy-resin blocks using a 40-mm focal length lens. The estimated laser intensity at the target plane is approximate to 9 ×109Wcm-2 . We used the fast-imaging technique to observe the expansion of the plasma plume and a custom-designed time-resolved photoelasticity imaging technique to observe the propagation of shock waves with the time resolution of nanoseconds. We found that at the same intensity of the laser beam, the plasma expansion during the laser pulse follows different mechanisms: the plasma plume that grows in air follows a radiation-wave model while a detonation-wave model can explain the expansion of the plasma plume induced in water. The ideal blast wave theory can be used to predict the decay of the shock wave in air but is not appropriate to describe the decay of the shock wave induced under water.

  17. Detonation and fragmentation modeling for the description of large scale vapor explosions

    International Nuclear Information System (INIS)

    Buerger, M.; Carachalios, C.; Unger, H.

    1985-01-01

    The thermal detonation modeling of large-scale vapor explosions is shown to be indispensable for realistic safety evaluations. A steady-state as well as transient detonation model have been developed including detailed descriptions of the dynamics as well as the fragmentation processes inside a detonation wave. Strong restrictions for large-scale vapor explosions are obtained from this modeling and they indicate that the reactor pressure vessel would even withstand explosions with unrealistically high masses of corium involved. The modeling is supported by comparisons with a detonation experiment and - concerning its key part - hydronamic fragmentation experiments. (orig.) [de

  18. Influence of ignition energy, ignition location, and stoichiometry on the deflagration-to-detonation distance in a Pulse Detonation Engine

    OpenAIRE

    Robinson, John P.

    2000-01-01

    The feasibility of utilizing detonations for air-breathing propulsion is the subject of a significant research effort headed by the Office of Naval Research. Pulse Detonation Engines (PDE) have a theoretically greater efficiency than current combustion cycles. However, pulse detonation technology must mature beginning with research in the fundamental process of developing a detonation wave. This thesis explores various ignition conditions which minimize the deflagration-to- detonation transit...

  19. Experiments and Observations on Intense Alfven Waves in the Laboratory and in Space

    International Nuclear Information System (INIS)

    Gekelman, W.; VanZeeland, M.; Vincena, S.; Pribyl, P.

    2003-01-01

    There are many situations, which occur in space (coronal mass ejections, supernovas), or are man-made (upper atmospheric detonations) in which a dense plasma expands into a background magnetized plasma that can support Alfven waves. The LArge Plasma Device (LAPD) is a machine, at UCLA, in which Alfven wave propagation in homogeneous and inhomogeneous plasmas has been studied. These will be briefly reviewed. A new class of experiments which involve the expansion of a dense (initially, δn/no>>1) laser-produced plasma into an ambient highly magnetized background plasma capable of supporting Alfven waves will be presented. Measurements are used to estimate the coupling efficiency of the laser energy and kinetic energy of the dense plasma into wave energy. The wave generation mechanism is due to field aligned return currents, coupled to the initial electron current, which replace fast electrons escaping the initial blast

  20. Toward a microscopic theory of detonations in energetic crystals

    International Nuclear Information System (INIS)

    Peyrard, M.; Odiot, S.

    1991-01-01

    Investigations of microscopic structure of detonation waves are useful for extending our basic understanding of the solid state. In a detonation wave, a crystal cell can be compressed to one-half of its equilibrium size. As a result, detonations probe regions of the atom-atom interaction potential curves that can hardly be investigated by any other means. In this paper the authors describe the first investigations of energetic materials after discussing briefly the molecular dynamics techniques themselves and presenting their application to shock waves in solids. We then focus on two particular topics in which molecular dynamics has brought new insights to the propagation of a detonation wave in a crystal, the role of the crystal structure, and the effects of the different steps in the chemistry. Section V presents a new approach that combines a model for the chemistry with standard molecular dynamics techniques, an approach that extends the domain of investigation of the numerical simulations and provides a step toward a microscopic theory of the propagation of a detonation wave. Section VI discusses the results and the future of these approaches

  1. Dynamic Load on a Pipe Caused by Acetylene Detonations – Experiments and Theoretical Approaches

    Directory of Open Access Journals (Sweden)

    Axel Sperber

    1999-01-01

    Full Text Available The load acting on the wall of a pipe by a detonation, which is travelling through, is not yet well characterized. The main reasons are the limited amount of sufficiently accurate pressure time history data and the requirement of considering the dynamics of the system. Laser vibrometry measurements were performed to determine the dynamic response of the pipe wall on a detonation. Different modelling approaches were used to quantify, theoretically, the radial displacements of the pipe wall. There is good agreement between measured and predicted values of vibration frequencies and the propagation velocities of transverse waves. Discrepancies mainly due to wave propagation effects were found in the amplitudes of the radial velocities. They might be overcome by the use of a dynamic load factor or improved modelling methods.

  2. Numerical Optimisation in Non Reacting Conditions of the Injector Geometry for a Continuous Detonation Wave Rocket Engine

    Science.gov (United States)

    Gaillard, T.; Davidenko, D.; Dupoirieux, F.

    2015-06-01

    The paper presents the methodology and the results of a numerical study, which is aimed at the investigation and optimisation of different means of fuel and oxidizer injection adapted to rocket engines operating in the rotating detonation mode. As the simulations are achieved at the local scale of a single injection element, only one periodic pattern of the whole geometry can be calculated so that the travelling detonation waves and the associated chemical reactions can not be taken into account. Here, separate injection of fuel and oxidizer is considered because premixed injection is handicapped by the risk of upstream propagation of the detonation wave. Different associations of geometrical periodicity and symmetry are investigated for the injection elements distributed over the injector head. To analyse the injection and mixing processes, a nonreacting 3D flow is simulated using the LES approach. Performance of the studied configurations is analysed using the results on instantaneous and mean flowfields as well as by comparing the mixing efficiency and the total pressure recovery evaluated for different configurations.

  3. Oblique interactions of detonation waves with explosive/metal interfaces

    International Nuclear Information System (INIS)

    Walsh, J.M.

    1982-12-01

    The interaction of a detonation wave with an explosive/metal interface is considered. Theoretical models are discussed, and calculated results are given for PBX 9501 onto uranium, tantalum, copper, 304 stainless steel, aluminum, and nickel. For PBX 9501 onto aluminum and copper, regular shock reflection (in the PBX 9501) at small angles changes to regular rarefaction reflection (Prandtl-Meyer flow) at large angles, and the curve of metal-shock pressure vs incidence angle is smooth. For the other metals, there is a discontinuity in shock pressure where low-angle, regular reflection transists to Mach reflection, and a smaller discontinuity where the Mach reflection changes back to high-angle regular reflection

  4. Effects of injection nozzle exit width on rotating detonation engine

    Science.gov (United States)

    Sun, Jian; Zhou, Jin; Liu, Shijie; Lin, Zhiyong; Cai, Jianhua

    2017-11-01

    A series of numerical simulations of RDE modeling real injection nozzles with different exit widths are performed in this paper. The effects of nozzle exit width on chamber inlet state, plenum flowfield and detonation propagation are analyzed. The results are compared with that using an ideal injection model. Although the ideal injection model is a good approximation method to model RDE inlet, the two-dimensional effects of real nozzles are ignored in the ideal injection model so that some complicated phenomena such as the reflected waves caused by the nozzle walls and the reversed flow into the nozzles can not be modeled accurately. Additionally, the ideal injection model overpredicts the block ratio. In all the cases that stabilize at one-wave mode, the block ratio increases as the nozzle exit width gets smaller. The dual-wave mode case also has a relatively high block ratio. A pressure oscillation in the plenum with the same main frequency with the rotating detonation wave is observed. A parameter σ is applied to describe the non-uniformity in the plenum. σ increases as the nozzle exit width gets larger. Under some condition, the heat release on the interface of fresh premixed gas layer and detonation products can be strong enough to induce a new detonation wave. A spontaneous mode-transition process is observed for the smallest exit width case. Due to the detonation products existing in the premixed gas layer before the detonation wave, the detonation wave will propagate through reactants and products alternately, and therefore its strength will vary with time, especially near the chamber inlet. This tendency gets weaker as the injection nozzle exit width increases.

  5. A summary of hydrogen-air detonation experiments

    International Nuclear Information System (INIS)

    Guirao, C.M.; Knystautas, R.; Lee, J.H.

    1989-05-01

    Dynamic detonation parameters are reviewed for hydrogen-air-diluent detonations and deflagration-to-detonation transitions (DDT). These parameters include the characteristic chemical length scale, such as the detonation cell width, associated with the three-dimensional cellular structure of detonation waves, critical transmission conditions of confined detonations into unconfined environments, critical initiation energy for unconfined detonations, detonability limits, and critical conditions for DDT. The detonation cell width, which depends on hydrogen and diluent concentrations, pressure, and temperature, is an important parameter in the prediction of critical geometry-dependent conditions for the transmission of confined detonations into unconfined environments and the critical energies for the direct initiation of unconfined detonations. Detonability limits depend on both initial and boundary conditions and the limit has been defined as the onset of single head spin. Four flame propagation regimes have been identified and the criterion for DDT in a smooth tube is discussed. 108 refs., 28 figs., 5 tabs

  6. Radio controlled detonators and sequential real time blast applications

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, T.; Laboz, J.M. [Delta Caps International, Nice (France)

    1995-12-31

    Among the numerous technical evolutions in the blasting environment the authors are going to describe below the concept of electronic detonator sequenced by radio waves, and also its numerous applications. Three major technologies are used in the initiation environment: fused-initiated detonators; electric detonators; and non-electric detonators. The last two technologies were made available under multiple variants. Two major innovations are going to substantially change the way traditional detonators operate: pyrotechnic delays are replaced by electronic delays (greater accuracy); and triggering orders, passing through a cable, is now replaced by radio-waves transmission (possibility to do real time delay pattern). Such a new product provided all the features offered by current detonators, but also allows mastering specific cases that were difficult to control with the current technology, such as: vibration control; underground blast; and building demolition.

  7. Characterization of initiation and detonation by Lagrange gage techniques. Final report

    International Nuclear Information System (INIS)

    Cowperthwaite, M.

    1983-08-01

    The work on reactive flow Lagrange analysis (RFLA) was concerned with Lagrange particle velocity histories that exhibit double maxima similar to those recorded in RX26 and PBX9404. Conditions for particle velocity histories to exhibit extrema were formulated in terms of envelopes formed by Lagrange pressure histories. Lagrange analysis of the flow produced by the expansion of a detonation wave at a free surface was proposed to extend the determination of the release adiabat of detonation products from the Chapman-Jouguet (CJ) state to zero pressure. Solutions were constructed for steady-state nonideal detonation waves propagating in polytropic explosive with two reacting components. Overdriven detonation was treated both as a reactive discontinuity and as a Zeldovich-von Neumann-Doering (ZND) wave. The Rankine-Hugoniot (RH) jump conditions were used to calculate the first and second derivatives on the detonation velocity versus particle velocity Hugoniot at the CJ point. Methods of differential geometry were used to determine the conditions that allow the flow equations and RH boundary conditions to admit similarity solutions for overdriven detonation waves

  8. Detonation waves in melt-coolant interaction. Part 2. Applied analysis

    International Nuclear Information System (INIS)

    Kolev, N.I.; Hulin, H.

    2001-01-01

    Making use of the detonation theory presented in part 1 for melt-water interaction, detonation solutions for different melt-water pairs at different conditions are compared to each other. Discussion is provided on the existence of detonation solutions for water droplet - melt droplet - gas systems. The conclusion is made that even if such solution can be realized in the nature, which is highly questionable, the resulting detonation pressures will be below 200 bar. This is an important result for judging the risk of the melt-water disperse mixtures in nuclear safety analysis. In addition, the detonation pressures for alumna-continuous water systems have been found to be stronger then those for urania-continuous water systems, in agreement with the experimental observations and seems to give finally the searched for a long time explanation why alumna-water systems detonate much more violent than urania-water systems. (orig.) [de

  9. Simulation of detonation cell kinematics using two-dimensional reactive blast waves

    Science.gov (United States)

    Thomas, G. O.; Edwards, D. H.

    1983-10-01

    A method of generating a cylindrical blast wave is developed which overcomes the disadvantages inherent in the converging-diverging nozzle technique used by Edwards et al., 1981. It is demonstrated than an exploding wire placed at the apex of a two-dimensional sector provides a satisfactory source of the generation of blast waves in reactive systems. The velocity profiles of the blast waves are found to simulate those in freely propagating detonations very well, and this method does not suffer from the disadvantage of having the mass flow at the throat as in the nozzle method. The density decay parameter is determined to have a constant value of 4 in the systems investigated, and it is suggested that this may be a universal value. It is proposed that suitable wedges could be used to create artificial Mach stems in the same manner as Strehlow and Barthel (1971) without the attendant disadvantages of the nozzle method.

  10. Numerical Computation of Detonation Stability

    KAUST Repository

    Kabanov, Dmitry

    2018-06-03

    Detonation is a supersonic mode of combustion that is modeled by a system of conservation laws of compressible fluid mechanics coupled with the equations describing thermodynamic and chemical properties of the fluid. Mathematically, these governing equations admit steady-state travelling-wave solutions consisting of a leading shock wave followed by a reaction zone. However, such solutions are often unstable to perturbations and rarely observed in laboratory experiments. The goal of this work is to study the stability of travelling-wave solutions of detonation models by the following novel approach. We linearize the governing equations about a base travelling-wave solution and solve the resultant linearized problem using high-order numerical methods. The results of these computations are postprocessed using dynamic mode decomposition to extract growth rates and frequencies of the perturbations and predict stability of travelling-wave solutions to infinitesimal perturbations. We apply this approach to two models based on the reactive Euler equations for perfect gases. For the first model with a one-step reaction mechanism, we find agreement of our results with the results of normal-mode analysis. For the second model with a two-step mechanism, we find that both types of admissible travelling-wave solutions exhibit the same stability spectra. Then we investigate the Fickett’s detonation analogue coupled with a particular reaction-rate expression. In addition to the linear stability analysis of this model, we demonstrate that it exhibits rich nonlinear dynamics with multiple bifurcations and chaotic behavior.

  11. Detonation velocity in poorly mixed gas mixtures

    Science.gov (United States)

    Prokhorov, E. S.

    2017-10-01

    The technique for computation of the average velocity of plane detonation wave front in poorly mixed mixture of gaseous hydrocarbon fuel and oxygen is proposed. Here it is assumed that along the direction of detonation propagation the chemical composition of the mixture has periodic fluctuations caused, for example, by layered stratification of gas charge. The technique is based on the analysis of functional dependence of ideal (Chapman-Jouget) detonation velocity on mole fraction (with respect to molar concentration) of the fuel. It is shown that the average velocity of detonation can be significantly (by more than 10%) less than the velocity of ideal detonation. The dependence that permits to estimate the degree of mixing of gas mixture basing on the measurements of average detonation velocity is established.

  12. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    Science.gov (United States)

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

  13. Mechanisms of detonation formation due to a temperature gradient

    Science.gov (United States)

    Kapila, A. K.; Schwendeman, D. W.; Quirk, J. J.; Hawa, T.

    2002-12-01

    Emergence of a detonation in a homogeneous, exothermically reacting medium can be deemed to occur in two phases. The first phase processes the medium so as to create conditions ripe for the onset of detonation. The actual events leading up to preconditioning may vary from one experiment to the next, but typically, at the end of this stage the medium is hot and in a state of nonuniformity. The second phase consists of the actual formation of the detonation wave via chemico-gasdynamic interactions. This paper considers an idealized medium with simple, rate-sensitive kinetics for which the preconditioned state is modelled as one with an initially prescribed linear gradient of temperature. Accurate and well-resolved numerical computations are carrried out to determine the mode of detonation formation as a function of the size of the initial gradient. For shallow gradients, the result is a decelerating supersonic reaction wave, a weak detonation, whose trajectory is dictated by the initial temperature profile, with only weak intervention from hydrodynamics. If the domain is long enough, or the gradient less shallow, the wave slows down to the Chapman-Jouguet speed and undergoes a swift transition to the ZND structure. For sharp gradients, gasdynamic nonlinearity plays a much stronger role. Now the path to detonation is through an accelerating pulse that runs ahead of the reaction wave and rearranges the induction-time distribution there to one that bears little resemblance to that corresponding to the initial temperature gradient. The pulse amplifies and steepens, transforming itself into a complex consisting of a lead shock, an induction zone, and a following fast deflagration. As the pulse advances, its three constituent entities attain progressively higher levels of mutual coherence, to emerge as a ZND detonation. For initial gradients that are intermediate in size, aspects of both the extreme scenarios appear in the path to detonation. The novel aspect of this study

  14. Propagation of Axially Symmetric Detonation Waves

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R L; Roeske, F; Souers, P C; Tarver, C M; Chow, C T S; Lee, R S; McGuire, E M; Overturf, G E; Vitello, P A

    2002-06-26

    We have studied the non-ideal propagation of detonation waves in LX-10 and in the insensitive explosive TATB. Explosively-driven, 5.8-mm-diameter, 0.125-mm-thick aluminum flyer plates were used to initiate 38-mm-diameter, hemispherical samples of LX-10 pressed to a density of 1.86 g/cm{sup 3} and of TATB at a density of 1.80 g/cm{sup 3}. The TATB powder was a grade called ultrafine (UFTATB), having an arithmetic mean particle diameter of about 8-10 {micro}m and a specific surface area of about 4.5 m{sup 2}/g. Using PMMA as a transducer, output pressure was measured at 5 discrete points on the booster using a Fabry-Perot velocimeter. Breakout time was measured on a line across the booster with a streak camera. Each of the experimental geometries was calculated using the Ignition and Growth Reactive Flow Model, the JWL++ Model and the Programmed Burn Model. Boosters at both ambient and cold (-20 C and -54 C) temperatures have been experimentally and computationally studied. A comparison of experimental and modeling results is presented.

  15. Ultraviolet versus infrared: Effects of ablation laser wavelength on the expansion of laser-induced plasma into one-atmosphere argon gas

    International Nuclear Information System (INIS)

    Ma Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu Jin; Lei Wenqi; Bai Xueshi; Zheng Lijuan; Zeng Heping

    2012-01-01

    Laser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV: 355 nm) or infrared (IR: 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy.

  16. Numerical Study on Critical Wedge Angle of Cellular Detonation Reflections

    International Nuclear Information System (INIS)

    Gang, Wang; Kai-Xin, Liu; De-Liang, Zhang

    2010-01-01

    The critical wedge angle (CWA) for the transition from regular reflection (RR) to Mach reflection (MR) of a cellular detonation wave is studied numerically by an improved space-time conservation element and solution element method together with a two-step chemical reaction model. The accuracy of that numerical way is verified by simulating cellular detonation reflections at a 19.3° wedge. The planar and cellular detonation reflections over 45°–55° wedges are also simulated. When the cellular detonation wave is over a 50° wedge, numerical results show a new phenomenon that RR and MR occur alternately. The transition process between RR and MR is investigated with the local pressure contours. Numerical analysis shows that the cellular structure is the essential reason for the new phenomenon and the CWA of detonation reflection is not a certain angle but an angle range. (fundamental areas of phenomenology(including applications))

  17. Pulse Detonation Assessment for Alternative Fuels

    Directory of Open Access Journals (Sweden)

    Muhammad Hanafi Azami

    2017-03-01

    Full Text Available The higher thermodynamic efficiency inherent in a detonation combustion based engine has already led to considerable interest in the development of wave rotor, pulse detonation, and rotating detonation engine configurations as alternative technologies offering improved performance for the next generation of aerospace propulsion systems, but it is now important to consider their emissions also. To assess both performance and emissions, this paper focuses on the feasibility of using alternative fuels in detonation combustion. Thus, the standard aviation fuels Jet-A, Acetylene, Jatropha Bio-synthetic Paraffinic Kerosene, Camelina Bio-synthetic Paraffinic Kerosene, Algal Biofuel, and Microalgae Biofuel are all asessed under detonation combustion conditions. An analytical model accounting for the Rankine-Hugoniot Equation, Rayleigh Line Equation, and Zel’dovich–von Neumann–Doering model, and taking into account single step chemistry and thermophysical properties for a stoichiometric mixture, is applied to a simple detonation tube test case configuration. The computed pressure rise and detonation velocity are shown to be in good agreement with published literature. Additional computations examine the effects of initial pressure, temperature, and mass flux on the physical properties of the flow. The results indicate that alternative fuels require higher initial mass flux and temperature to detonate. The benefits of alternative fuels appear significant.

  18. Theory of spin and lattice wave dynamics excited by focused laser pulses

    Science.gov (United States)

    Shen, Ka; Bauer, Gerrit E. W.

    2018-06-01

    We develop a theory of spin wave dynamics excited by ultrafast focused laser pulses in a magnetic film. We take into account both the volume and surface spin wave modes in the presence of applied, dipolar and magnetic anisotropy fields and include the dependence on laser spot exposure size and magnetic damping. We show that the sound waves generated by local heating by an ultrafast focused laser pulse can excite a wide spectrum of spin waves (on top of a dominant magnon–phonon contribution). Good agreement with recent experiments supports the validity of the model.

  19. Detonation mode and frequency analysis under high loss conditions for stoichiometric propane-oxygen

    KAUST Repository

    Jackson, Scott

    2016-03-24

    The propagation characteristics of galloping detonations were quantified with a high-time-resolution velocity diagnostic. Combustion waves were initiated in 30-m lengths of 4.1-mm inner diameter transparent tubing filled with stoichiometric propane-oxygen mixtures. Chemiluminescence from the resulting waves was imaged to determine the luminous wave front position and velocity every 83.3 μ. As the mixture initial pressure was decreased from 20 to 7 kPa, the wave was observed to become increasingly unsteady and transition from steady detonation to a galloping detonation. While wave velocities averaged over the full tube length smoothly decreased with initial pressure down to half of the Chapman-Jouguet detonation velocity (DCJ) at the quenching limit, the actual propagation mechanism was seen to be a galloping wave with a cycle period of approximately 1.0 ms, corresponding to a cycle length of 1.3-2.0 m or 317-488 tube diameters depending on the average wave speed. The long test section length of 7300 tube diameters allowed observation of up to 20 galloping cycles, allowing for statistical analysis of the wave dynamics. In the galloping regime, a bimodal velocity distribution was observed with peaks centered near 0.4 DCJ and 0.95 DCJ. Decreasing initial pressure increasingly favored the low velocity mode. Galloping frequencies ranged from 0.8 to 1.0 kHz and were insensitive to initial mixture pressure. Wave deflagration-to-detonation transition and detonation failure trajectories were found to be repeatable in a given test and also across different initial mixture pressures. The temporal duration of wave dwell at the low and high velocity modes during galloping was also quantified. It was found that the mean wave dwell duration in the low velocity mode was a weak function of initial mixture pressure, while the mean dwell time in the high velocity mode depended exponentially on initial mixture pressure. Analysis of the velocity histories using dynamical systems ideas

  20. Development of a Detonation Profile Test for Studying Aging Effects in LX-17

    International Nuclear Information System (INIS)

    Tran, T; Lewis, P; Tarver, C; Maienschein, J; Druce, R; Lee, R; Roeske, F

    2002-01-01

    A new small-scale Detonation Profile Test (DPT) is being developed to investigate aging effects on the detonation behavior of insensitive high explosives. The experiment involves initiating a small LX-17 cylindrical charge (12.7-19.1 mm diameter x 25.4-33 mm long) and measuring the velocity and curvature of the emerging detonation wave using a streak camera. Results for 12.7 mm diameter unconfined LX-17 charges show detonation velocity in the range between 6.79 and 7.06 km/s for parts up to 33 mm long. Since LX-17 can not sustain detonation at less than 7.3 km/s, these waves were definitely failing. Experiments with confined 12.7 mm diameter and unconfined 19.1 mm diameter samples showed wave velocities in the range of 7.4-7.6 km/s, values approaching steady state conditions at infinite diameter. Experiments with unconfined 19.1 mm diameter specimens are expected to provide reproducible and useful range of detonation parameters suitable for studying aging effects

  1. Development of a Detonation Profile Test for Studying Aging Effects in LX-17

    Energy Technology Data Exchange (ETDEWEB)

    Tran, T; Lewis, P; Tarver, C; Maienschein, J; Druce, R; Lee, R; Roeske, F

    2002-03-25

    A new small-scale Detonation Profile Test (DPT) is being developed to investigate aging effects on the detonation behavior of insensitive high explosives. The experiment involves initiating a small LX-17 cylindrical charge (12.7-19.1 mm diameter x 25.4-33 mm long) and measuring the velocity and curvature of the emerging detonation wave using a streak camera. Results for 12.7 mm diameter unconfined LX-17 charges show detonation velocity in the range between 6.79 and 7.06 km/s for parts up to 33 mm long. Since LX-17 can not sustain detonation at less than 7.3 km/s, these waves were definitely failing. Experiments with confined 12.7 mm diameter and unconfined 19.1 mm diameter samples showed wave velocities in the range of 7.4-7.6 km/s, values approaching steady state conditions at infinite diameter. Experiments with unconfined 19.1 mm diameter specimens are expected to provide reproducible and useful range of detonation parameters suitable for studying aging effects.

  2. Shock tubes and waves; Proceedings of the Sixteenth International Symposium, Rheinisch-Westfaelische Technische Hochschule, Aachen, Federal Republic of Germany, July 26-31, 1987

    Science.gov (United States)

    Groenig, Hans

    Topics discussed in this volume include shock wave structure, propagation, and interaction; shocks in condensed matter, dusty gases, and multiphase media; chemical processes and related combustion and detonation phenomena; shock wave reflection, diffraction, and focusing; computational fluid dynamic code development and shock wave application; blast and detonation waves; advanced shock tube technology and measuring technique; and shock wave applications. Papers are presented on dust explosions, the dynamics of shock waves in certain dense gases, studies of condensation kinetics behind incident shock waves, the autoignition mechanism of n-butane behind a reflected shock wave, and a numerical simulation of the focusing process of reflected shock waves. Attention is also given to the equilibrium shock tube flow of real gases, blast waves generated by planar detonations, modern diagnostic methods for high-speed flows, and interaction between induced waves and electric discharge in a very high repetition rate excimer laser.

  3. Shock and Detonation Physics at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, David L [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve A [Los Alamos National Laboratory

    2012-08-22

    WX-9 serves the Laboratory and the Nation by delivering quality technical results, serving customers that include the Nuclear Weapons Program (DOE/NNSA), the Department of Defense, the Department of Homeland Security and other government agencies. The scientific expertise of the group encompasses equations-of-state, shock compression science, phase transformations, detonation physics including explosives initiation, detonation propagation, and reaction rates, spectroscopic methods and velocimetry, and detonation and equation-of-state theory. We are also internationally-recognized in ultra-fast laser shock methods and associated diagnostics, and are active in the area of ultra-sensitive explosives detection. The facility capital enabling the group to fulfill its missions include a number of laser systems, both for laser-driven shocks, and spectroscopic analysis, high pressure gas-driven guns and powder guns for high velocity plate impact experiments, explosively-driven techniques, static high pressure devices including diamond anvil cells and dilatometers coupled with spectroscopic probes, and machine shops and target fabrication facilities.

  4. Confined detonations with cylindrical and spherical symmetry; Detonaciones confinadas con simetria esferica y cilindrica

    Energy Technology Data Exchange (ETDEWEB)

    Linan, A; Lecuona, A

    1979-07-01

    An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/p{gamma}-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs.

  5. On the deflagration-to-detonation transition (DDT) process with added energetic solid particles for pulse detonation engines (PDE)

    Science.gov (United States)

    Nguyen, V. B.; Li, J.; Chang, P.-H.; Phan, Q. T.; Teo, C. J.; Khoo, B. C.

    2018-01-01

    In this paper, numerical simulations are performed to study the dynamics of the deflagration-to-detonation transition (DDT) in pulse detonation engines (PDE) using energetic aluminum particles. The DDT process and detonation wave propagation toward the unburnt hydrogen/air mixture containing solid aluminum particles is numerically studied using the Eulerian-Lagrangian approach. A hybrid numerical methodology combined with appropriate sub-models is used to capture the gas dynamic characteristics, particle behavior, combustion characteristics, and two-way solid-particle-gas flow interactions. In our approach, the gas mixture is expressed in the Eulerian frame of reference, while the solid aluminum particles are tracked in the Lagrangian frame of reference. The implemented computer code is validated using published benchmark problems. The obtained results show that the aluminum particles not only shorten the DDT length but also reduce the DDT time. The improvement of DDT is primarily attributed to the heat released from surface chemical reactions on the aluminum particles. The temperatures associated with the DDT process are greater than the case of non-reacting particles added, with an accompanying rise in the pressure. For an appropriate range of particle volume fraction, particularly in this study, the higher volume fraction of the micro-aluminum particles added in the detonation chamber can lead to more heat energy released and more local instabilities in the combustion process (caused by the local high temperature), thereby resulting in a faster DDT process. In essence, the aluminum particles contribute to the DDT process of successfully transitioning to detonation waves for (failure) cases in which the fuel gas mixture can be either too lean or too rich. With a better understanding of the influence of added aluminum particles on the dynamics of the DDT and detonation process, we can apply it to modify the geometry of the detonation chamber (e.g., the length of

  6. Instrumentation techniques for monitoring shock and detonation waves

    Science.gov (United States)

    Dick, R. D.; Parrish, R. L.

    1985-09-01

    CORRTEX (Continuous Reflectometry for Radius Versus Time Experiments), SLIFER (Shorted Location Indication by Frequency of Electrical Resonance), and pin probes were used to monitor several conditions of blasting such as the detonation velocity of the explosive, the functioning of the stemming column confining the explosive, and rock mass motion. CORRTEX is a passive device that employs time-domain reflectometry to interrogate the two-way transit time of a coaxial cable. SLIFER is an active device that monitors the changing frequency resulting from a change in length of a coaxial cable forming an element of an oscillator circuit. Pin probes in this application consist of RG-174 coaxial cables, each with an open circuit, placed at several known locations within the material. Each cable is connected to a pulse-forming network and a voltage source. When the cables are shorted by the advancing wave, time-distance data are produced from which a velocity can be computed. Each technique, installation of the gauge, examples of the signals, and interpretation of the records are described.

  7. The effect of initial pressure on detonation propagation across a mixture

    Directory of Open Access Journals (Sweden)

    Yao-Chung Hsu

    2016-07-01

    Full Text Available This study determines the effect of the initial pressure on the propagation of a Chapman–Jouguet detonation wave from a stoichiometric C3H8/O2 mixture (donor to a stoichiometric C3H8/air mixture (acceptor. Depending on the initial pressure ratio in the donor and the acceptor, the result can be a smooth transmission, a re-initiated detonation wave, or a transmitted shock wave. When the donor is divided into a driver donor and a driven donor, the degree of overdrive in a driven donor varies with the donor pressure ratio. There must be a greater degree of overdrive in the driven donor for re-initiation of a detonation wave in the acceptor, particularly if the initial pressure in the driven donor is lower than the Chapman–Jouguet pressure in the acceptor. The bi-dimensional effect is also another major factor.

  8. Reinforced concrete wall under hydrogen detonation

    International Nuclear Information System (INIS)

    Saarenheimo, A.

    2000-11-01

    The structural integrity of a reinforced concrete wall in the BWR reactor building under hydrogen detonation conditions has been analysed. Of particular interest is whether the containment integrity can be jeopardised by an external hydrogen detonation. The load carrying capacity of a reinforced concrete wall was studied. The detonation pressure loads were estimated with computerised hand calculations assuming a direct initiation of detonation and applying the strong explosion theory. The results can be considered as rough and conservative estimates for the first shock pressure impact induced by a reflecting detonation wave. Structural integrity may be endangered due to slow pressurisation or dynamic impulse loads associated with local detonations. The static pressure following the passage of a shock front may be relatively high, thus this static or slowly decreasing pressure after a detonation may damage the structure severely. The mitigating effects of the opening of a door on pressure history and structural response were also studied. The non-linear behaviour of the wall was studied under detonations corresponding a detonable hydrogen mass of 0.5 kg and 1.428 kg. Non-linear finite element analyses of the reinforced concrete structure were carried out by the ABAQUS/Explicit program. The reinforcement and its non-linear material behaviour and the tensile cracking of concrete were modelled. Reinforcement was defined as layers of uniformly spaced reinforcing bars in shell elements. In these studies the surrounding structures of the non-linearly modelled reinforced concrete wall were modelled using idealised boundary conditions. Especially concrete cracking and yielding of the reinforcement was monitored during the numerical simulation. (au)

  9. Chemical kinetics of detonation in some liquid mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Raikova, Vlada M.; Likholatov, Evgeny A. [Mendeleev University of Chemical Technology, Moscow (Russian Federation)

    2005-09-01

    The main objective of this work is to study the chemical kinetics of detonation reactions in some nitroester mixtures and solutions of nitrocompounds in concentrated nitric acid. The main source of information on chemical kinetics in the detonation wave was the experimental dependence of failure diameter on composition of mixtures. Calculations were carried out in terms of classic theory of Dremin using the SGKR computer code. Effective values for the activation energies and pre-exponential factors for detonation reactions in the mixtures under investigation have been defined. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  10. Near-limit propagation of gaseous detonations in narrow annular channels

    Science.gov (United States)

    Gao, Y.; Ng, H. D.; Lee, J. H. S.

    2017-03-01

    New results on the near-limit behaviors of gaseous detonations in narrow annular channels are reported in this paper. Annular channels of widths 3.2 and 5.9 mm were made using circular inserts in a 50.8 mm-diameter external tube. The length of each annular channel was 1.8 m. Detonations were initiated in a steel driver tube where a small volume of a sensitive C2H2+ 2.5O2 mixture was injected to facilitate detonation initiation. A 2 m length of circular tube with a 50.8 mm diameter preceded the annular channel so that a steady Chapman-Jouguet (CJ) detonation was established prior to entering the annular channel. Four detonable mixtures of C2H2 {+} 2.5O2 {+} 85 % Ar, C2H2 {+} 2.5O2 {+} 70 % Ar, C3H8 {+} 5O2, and CH4 {+} 2O2 were used in the present study. Photodiodes spaced 10 cm throughout the length of both the annular channel and circular tube were used to measure the detonation velocity. In addition, smoked foils were inserted into the annular channel to monitor the cellular structure of the detonation wave. The results show that, well within the detonability limits, the detonation wave propagates along the channel with a small local velocity fluctuation and an average global velocity can be deduced. The average detonation velocity has a small deficit of 5-15 % far from the limits and the velocity rapidly decreases to 0.7V_{CJ}-0.8V_{CJ} when the detonation propagates near the limit. Subsequently, the fluctuation of local velocity also increases as the decreasing initial pressure approaches the limit. In the two annular channels used in this work, no galloping detonations were observed for both the stable and unstable mixtures tested. The present study also confirms that single-headed spinning detonation occurs at the limit, as in a circular tube, rather than the up and down "zig zag" mode in a two-dimensional, rectangular channel.

  11. The structure and evolution of galacto-detonation waves - Some analytic results in sequential star formation models of spiral galaxies

    Science.gov (United States)

    Cowie, L. L.; Rybicki, G. B.

    1982-01-01

    Waves of star formation in a uniform, differentially rotating disk galaxy are treated analytically as a propagating detonation wave front. It is shown, that if single solitary waves could be excited, they would evolve asymptotically to one of two stable spiral forms, each of which rotates with a fixed pattern speed. Simple numerical solutions confirm these results. However, the pattern of waves that develop naturally from an initially localized disturbance is more complex and dies out within a few rotation periods. These results suggest a conclusive observational test for deciding whether sequential star formation is an important determinant of spiral structure in some class of galaxies.

  12. Traveling wave laser system

    International Nuclear Information System (INIS)

    Gregg, D.W.; Kidder, R.E.; Biehl, A.T.

    1975-01-01

    The invention broadly involves a method and means for generating a traveling wave laser pulse and is basically analogous to a single pass light amplifier system. However, the invention provides a traveling wave laser pulse of almost unlimited energy content, wherein a gain medium is pumped in a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)

  13. SLAG CHARACTERIZATION AND REMOVAL USING PULSE DETONATION TECHNOLOGY DURING COAL GASIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    DR. DANIEL MEI; DR. JIANREN ZHOU; DR. PAUL O. BINEY; DR. ZIAUL HUQUE

    1998-07-30

    Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. Conventional slag removal methods including soot blowers and water lances have great difficulties in removing slags especially from the down stream areas of utility power plant boilers. The detonation wave technique, based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. A slight increase in the boiler efficiency, due to more effective ash/deposit removal and corresponding reduction in plant maintenance downtime and increased heat transfer efficiency, will save millions of dollars in operational costs. Reductions in toxic emissions will also be accomplished due to reduction in coal usage. Detonation waves have been demonstrated experimentally to have exceptionally high shearing capability, important to the task of removing slag and fouling deposits. The experimental results describe the parametric study of the input parameters in removing the different types of slag and operating condition. The experimental results show that both the single and multi shot detonation waves have high potential in effectively removing slag deposit from boiler heat transfer surfaces. The results obtained are encouraging and satisfactory. A good indication has also been obtained from the agreement with the preliminary computational fluid dynamics analysis that the wave impacts are more effective in removing slag deposits from tube bundles rather than single tube. This report presents results obtained in effectively removing three different types of slag (economizer, reheater, and air-heater) t a distance of up to 20 cm from the exit of the detonation tube. The experimental results show that the softer slags can be removed more easily. Also closer the slag to the exit of

  14. Coupling Detonation Shock Dynamics in a Consistent Manner to Equations of State

    Science.gov (United States)

    Belfield, William

    2017-06-01

    In hydrocode simulations, detonating high explosives (HE) are often modelled using programmed burn. Each HE cell is assigned a ``burn time'' at which it should begin to behave as HE products in the subsequent simulation. Traditionally, these burn times were calculated using a Huygens construction to propagate the detonation wave at a constant speed corresponding to the planar Chapman-Jouguet (CJ) velocity. The Detonation Shock Dynamics (DSD) model improves upon this approach by treating the local detonation velocity as a function of wave curvature, reflecting that the detonation speed is not constant in reality. However, without alterations being made, this variable detonation velocity is inconsistent with the CJ velocity associated with the HE products equation of state (EOS). Previous work has shown that the inconsistency can be resolved by modifying the HE product EOS, but this treatment is empirical in nature and has only been applied to the JWL EOS. This work investigates different methods to resolve the inconsistency that are applicable both to JWL and to tabular HE product EOS, and their impact on hydrocode simulations.

  15. A transient model to the thermal detonation

    International Nuclear Information System (INIS)

    Karachalios, K.

    1987-04-01

    The model calculates the escalation dynamics and the long time behavior of thermal detonation waves depending on the initial and boundary conditions (data of the premixture, ignition at a solid wall or at an open end, etc.). Especially, for a given mixture and a certain fragmentation behavior more than one stable steady-state cases resulted, depending on the applied ignition energy. Investigations showed a very good consistency between the transient model and a steady-state model which is based on the same physical description and includes an additional stability criterion. Also the influence of effects such as e.g. non-homogeneous coolant heating, spherical instead of plane wave propagation and inhomogeneities of the premixture on the development of the wave were investigated. Comparison calculations with large scale experiments showed that they can be well explained by means of the thermal detonation theory, especially considering the transient phase of the wave development. (orig./HP) [de

  16. Escalation and propagation of thermal detonation in the corium-water systems

    International Nuclear Information System (INIS)

    Melikhov, O.I.; Melikhov, V.I.; Sokolin, A.V.

    2001-01-01

    The thermal detonation taking into account micro-interaction processes model has been applied to study thermal detonation wave escalation and propagation in the corium-water mixture. Transient escalation stage and subsequent steady-state propagation stage of the thermal detonation have been calculated. The essential decrease of the escalation length in comparison with the previous results calculated without micro-interaction concept has been obtained. (authors)

  17. Control of a laser front wave

    International Nuclear Information System (INIS)

    Akaoka, K.; Wakaida, I.

    1996-01-01

    We controlled the laser wave front through a laser beam simulation experiment propagating through medium. Thus, we confirmed that the RMS, defined as the quadratic mean of the laser beam wave front, dropped to the 1/3 - 1/6 of the pre-control value

  18. Carbon deflagration supernova, an alternative to carbon detonation

    Energy Technology Data Exchange (ETDEWEB)

    Nomoto, K; Sugimoto, D [Tokyo Univ. (Japan). Coll. of General Education; Neo, S [Kyoto Univ. (Japan). Dept. of Physics

    1976-02-01

    As an alternative to the carbon detonation, a carbon deflagration supernova model is presented by a full hydrodynamic computation. A deflagration wave, which propagates through the core due to convective heat transport, does not grow into detonation. Though it results in a complete disruption of the star, the difficulty of overproduction of iron peak elements can be avoided if the deflagration is relatively slow.

  19. Study of a Model Equation in Detonation Theory

    KAUST Repository

    Faria, Luiz; Kasimov, Aslan R.; Rosales, Rodolfo R.

    2014-01-01

    Here we analyze properties of an equation that we previously proposed to model the dynamics of unstable detonation waves [A. R. Kasimov, L. M. Faria, and R. R. Rosales, Model for shock wave chaos, Phys. Rev. Lett., 110 (2013), 104104]. The equation

  20. Numerical simulations of cellular detonation diffraction in a stable gaseous mixture

    Directory of Open Access Journals (Sweden)

    Jian Li

    2016-09-01

    Full Text Available In this paper, the diffraction phenomenon of gaseous cellular detonations emerging from a confined tube into a sudden open space is simulated using the reactive Euler equations with a two-step Arrhenius chemistry model. Both two-dimensional and axisymmetric configurations are used for modeling cylindrical and spherical expansions, respectively. The chemical parameters are chosen for a stable gaseous explosive mixture in which the cellular detonation structure is highly regular. Adaptive mesh refinement (AMR is used to resolve the detonation wave structure and its evolution during the transmission. The numerical results show that the critical channel width and critical diameter over the detonation cell size are about 13±1 and 25±1, respectively. These numerical findings are comparable with the experimental observation and confirm again that the critical channel width and critical diameter differ essentially by a factor close to 2, equal to the geometrical scaling based on front curvature theory. Unlike unstable mixtures where instabilities manifested in the detonation front structure play a significant role during the transmission, the present numerical results and the observed geometrical scaling provide again evidence that the failure of detonation diffraction in stable mixtures with a regular detonation cellular pattern is dominantly caused by the global curvature due to the wave divergence resulting in the global decoupling of the reaction zone with the expanding shock front.

  1. Fundamental Structure of High-Speed Reacting Flows: Supersonic Combustion and Detonation

    Science.gov (United States)

    2016-04-30

    interim, memorandum, master’s thesis , progress, quarterly, research, special, group study, etc. 3. DATES COVERED. Indicate the time during which the...liquid rocket engines, studied the concept of rotating detonation rocket engine in both gaseous and two-phase propellants . Recently, there have been...detonation waves. 4.2 Experimental Setup The linear model detonation engine (LDME) serves as an “unwrapped” RDE test bed, shown in Fig. 4.1. Design

  2. TRENDS IN THE DEVELOPMENT OF DETONATION ENGINES FOR HIGH-SPEED AEROSPACE AIRCRAFTS AND THE PROBLEM OF TRIPLE CONFIGURATIONS OF SHOCK WAVES. Part II - Research of counterpropagating shock waves and triple shock wave configurations

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2016-03-01

    Full Text Available The paper deals with current issues of the interference theory development of gas-dynamic discontinuities as applied to a problem of propulsion refinement for the air-spacecrafts, designed for hypersonic flight speeds. In the first part of the review we have presented the history of detonation study and different concepts of detonation engines, as well as air intakes designed for hypersonic flight speeds. The second part provides an overview of works on the interference theory development for gas-dynamic discontinuities. We report about classification of the gas-dynamic discontinuities, shock wave propagation, shock-wave structures and triple configurations of shock waves. We have shown that many of these processes are accompanied by a hysteresis phenomenon, there are areas of ambiguity; therefore, in the design of engines and air intakes optimal shock-wave structures should be provided and their sustainability should be ensured. Much attention has recently been given to the use of the air intakes in the shock-wave structures with the rereflection of shock waves and the interference of shock waves in the opposite directions. This review provides increased focus on it, contains references to landmark works, the last calculated and experimental results. Unfortunately, foreign surveys missed many landmark works of the Soviet and Russian researchers, as they were not published in English. At the same time, it was the Soviet school of gas dynamics that has formulated the interference theory of gas-dynamic discontinuities in its present form. To fill this gap is one of this review scopes. The review may be recommended for professionals, engineers and scientists working in the field of aerospace engineering.

  3. Qualitative modeling of the dynamics of detonations with losses

    KAUST Repository

    Faria, Luiz; Kasimov, Aslan R.

    2015-01-01

    We consider a simplified model for the dynamics of one-dimensional detonations with generic losses. It consists of a single partial differential equation that reproduces, at a qualitative level, the essential properties of unsteady detonation waves, including pulsating and chaotic solutions. In particular, we investigate the effects of shock curvature and friction losses on detonation dynamics. To calculate steady-state solutions, a novel approach to solving the detonation eigenvalue problem is introduced that avoids the well-known numerical difficulties associated with the presence of a sonic point. By using unsteady numerical simulations of the simplified model, we also explore the nonlinear stability of steady-state or quasi-steady solutions. © 2014 The Combustion Institute.

  4. Rapid detonation initiation by sparks in a short duct: a numerical study

    Science.gov (United States)

    Hu, Z. M.; Dou, H. S.; Khoo, B. C.

    2010-06-01

    Rapid onset of detonation can efficiently increase the working frequency of a pulse detonation engine (PDE). In the present study, computations of detonation initiation in a duct are conducted to investigate the mechanisms of detonation initiation. The governing equations are the Euler equations and the chemical kinetic model consists of 19 elementary reactions and nine species. Different techniques of initiation have been studied for the purpose of accelerating detonation onset with a relatively weak ignition energy. It is found that detonation ignition induced by means of multiple sparks is applicable to auto-ignition for a PDE. The interaction among shock waves, flame fronts and the strip of pre-compressed fresh (unburned) mixture plays an important role in rapid onset of detonation.

  5. Laser control of electron matter waves

    NARCIS (Netherlands)

    Jones, E.; Becker, M.; Luiten, O.J.; Batelaan, H.

    2016-01-01

    In recent years laser light has been used to control the motion of electron waves. Electrons can now be diffracted by standing waves of light. Laser light in the vicinity of nanostructures is used to affect free electrons, for example, femto-second and atto-second laser-induced electrons are emitted

  6. Sensor for electromagnetic waves caused by nuclear detonation

    International Nuclear Information System (INIS)

    Weischedel, R.C.

    1980-01-01

    An electronic sensor is disclosed, having circuits for identifying electromagnetic radiation signals caused by nuclear detonations. Circuits also are provided for discriminating against false indications due to electromagnetic radiation caused by lightning

  7. Impulse generation by detonation tubes

    Science.gov (United States)

    Cooper, Marcia Ann

    partially filled detonation tubes was compiled and analyzed with models investigating concepts of energy conservation and unsteady gas dynamics. A model to predict the specific impulse was developed for partially filled tubes. The role of finite chemical kinetics in detonation products was examined through numerical simulations of the flow in nonsteady expansion waves.

  8. Numerical modelling of continuous spin detonation in rich methane-oxygen mixture

    International Nuclear Information System (INIS)

    Trotsyuk, A V

    2016-01-01

    A numerical simulation of a two-dimensional structure of the detonation wave (DW) in a rich (equivalence ratio φ=1.5) methane-air mixture at normal initial condition has been conducted. The computations have been performed in a wide range of channel heights. From the analysis of the flow structure and the number of primary transverse waves in the channel, the dominant size of the detonation cell for studied mixture has been determined to be 45÷50 cm. Based on the fundamental studies of multi-front (cellular) structure of the classical propagating DW in methane mixtures, numerical simulation of continuous spin detonation (CSD) of rich (φ=1.2) methane-oxygen mixture has been carried out in the cylindrical detonation chamber (DC) of the rocket-type engine. We studied the global flow structure in DC, and the detailed structure of the front of the rotating DW. Integral characteristics of the detonation process - the distribution of average values of static and total pressure along the length of the DC, and the value of specific impulse have been obtained. The geometric limit of stable existence of CSD has been determined. (paper)

  9. Experimental study of detonation of large-scale powder-droplet-vapor mixtures

    Science.gov (United States)

    Bai, C.-H.; Wang, Y.; Xue, K.; Wang, L.-F.

    2018-05-01

    Large-scale experiments were carried out to investigate the detonation performance of a 1600-m3 ternary cloud consisting of aluminum powder, fuel droplets, and vapor, which were dispersed by a central explosive in a cylindrically stratified configuration. High-frame-rate video cameras and pressure gauges were used to analyze the large-scale explosive dispersal of the mixture and the ensuing blast wave generated by the detonation of the cloud. Special attention was focused on the effect of the descending motion of the charge on the detonation performance of the dispersed ternary cloud. The charge was parachuted by an ensemble of apparatus from the designated height in order to achieve the required terminal velocity when the central explosive was detonated. A descending charge with a terminal velocity of 32 m/s produced a cloud with discernably increased concentration compared with that dispersed from a stationary charge, the detonation of which hence generates a significantly enhanced blast wave beyond the scaled distance of 6 m/kg^{1/3}. The results also show the influence of the descending motion of the charge on the jetting phenomenon and the distorted shock front.

  10. Propagating Structure Of A Microwave Driven Shock wave Inside A Tube

    International Nuclear Information System (INIS)

    Shimada, Yutaka; Shibata, Teppei; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Arakawa, Yoshihiro

    2010-01-01

    The thrust generation process of a microwave rocket is similar to a pulse detonation engine, and understanding the interactions between microwave plasma and shock waves is important. Shadowgraph images of the microwave plasma generated in a tube under atmospheric air were taken. The observed plasma and shock wave were propagating one-dimensionally at constant velocity inside the tube. In order to understand the flow field inside the rocket, one-dimensional CFD analysis was conducted. With the change of microwave power density, the structure of the flow field was classified into two regimes: Microwave Supported Combustion (MSC), and Microwave Supported Detonation (MSD). The structure of the MSD was different from the structure of a chemical detonation, which implied the existence of a preheating in front of the shock wave. Furthermore, the flight performance was estimated by calculating the momentum coupling coefficient. It was confirmed that the efficiency was nearly constant in the MSD regime, with the increase of microwave power density.

  11. Three Dimensional Analysis of Induced Detonation of Cased Explosive

    Science.gov (United States)

    2014-10-16

    hardness and ductility . RHA steel is largely used in military applications to manufacture armoured vehicles. The Johnson Cook (JC) constitutive...armour (RHA) steel were investigated through the LS-DYNA. The investigation focused on shock to detonation simulations of Composition B, with the... hot spots caused by the compression of the explosive from the initial shockwave. Detonation was also caused by pressure waves reflecting against the

  12. A Semi-analytic Criterion for the Spontaneous Initiation of Carbon Detonations in White Dwarfs

    International Nuclear Information System (INIS)

    Garg, Uma; Chang, Philip

    2017-01-01

    Despite over 40 years of active research, the nature of the white dwarf progenitors of SNe Ia remains unclear. However, in the last decade, various progenitor scenarios have highlighted the need for detonations to be the primary mechanism by which these white dwarfs are consumed, but it is unclear how these detonations are triggered. In this paper we study how detonations are spontaneously initiated due to temperature inhomogeneities, e.g., hotspots, in burning nuclear fuel in a simplified physical scenario. Following the earlier work by Zel’Dovich, we describe the physics of detonation initiation in terms of the comparison between the spontaneous wave speed and the Chapman–Jouguet speed. We develop an analytic expression for the spontaneous wave speed and utilize it to determine a semi-analytic criterion for the minimum size of a hotspot with a linear temperature gradient between a peak and base temperature for which detonations in burning carbon–oxygen material can occur. Our results suggest that spontaneous detonations may easily form under a diverse range of conditions, likely allowing a number of progenitor scenarios to initiate detonations that burn up the star.

  13. A Semi-analytic Criterion for the Spontaneous Initiation of Carbon Detonations in White Dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Garg, Uma; Chang, Philip, E-mail: umagarg@uwm.edu, E-mail: chang65@uwm.edu [Department of Physics, University of Wisconsin-Milwaukee, 3135 North Maryland Avenue, Milwaukee, WI 53211 (United States)

    2017-02-20

    Despite over 40 years of active research, the nature of the white dwarf progenitors of SNe Ia remains unclear. However, in the last decade, various progenitor scenarios have highlighted the need for detonations to be the primary mechanism by which these white dwarfs are consumed, but it is unclear how these detonations are triggered. In this paper we study how detonations are spontaneously initiated due to temperature inhomogeneities, e.g., hotspots, in burning nuclear fuel in a simplified physical scenario. Following the earlier work by Zel’Dovich, we describe the physics of detonation initiation in terms of the comparison between the spontaneous wave speed and the Chapman–Jouguet speed. We develop an analytic expression for the spontaneous wave speed and utilize it to determine a semi-analytic criterion for the minimum size of a hotspot with a linear temperature gradient between a peak and base temperature for which detonations in burning carbon–oxygen material can occur. Our results suggest that spontaneous detonations may easily form under a diverse range of conditions, likely allowing a number of progenitor scenarios to initiate detonations that burn up the star.

  14. Ignition and Growth Modeling of Detonating LX-04 (85% HMX / 15% VITON) Using New and Previously Obtained Experimental Data

    Science.gov (United States)

    Tarver, Craig

    2017-06-01

    An Ignition and Growth reactive flow model for detonating LX-04 (85% HMX / 15% Viton) was developed using new and previously obtained experimental data on: cylinder test expansion; wave curvature; failure diameter; and laser interferometric copper and tantalum foil free surface velocities and LiF interface particle velocity histories. A reaction product JWL EOS generated by the CHEETAH code compared favorably with the existing, well normalized LX-04 product JWL when both were used with the Ignition and Growth model. Good agreement with all existing experimental data was obtained. Keywords: LX-04, HMX, detonation, Ignition and Growth PACS:82.33.Vx, 82.40.Fp This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  15. Laser shock wave and its applications

    Science.gov (United States)

    Yang, Chaojun; Zhang, Yongkang; Zhou, Jianzhong; Zhang, Fang; Feng, Aixin

    2007-12-01

    The technology of laser shock wave is used to not only surface modification but also metal forming. It can be divided into three parts: laser shock processing, laser shock forming (LSF) and laser peenforming(LPF). Laser shock processing as a surface treatment to metals can make engineering components have a residual compressive stress so that it obviously improves their fatigue strength and stress corrosion performances, while laser shock forming (LSF) is a novel technique that is used in plastic deformation of sheet metal recently and Laser peen forming (LPF) is another new sheet metal forming process presented in recent years. They all can be carried out by a high-power and repetition pulse Nd:Glass laser device made by Jiangsu University. Laser shock technology has characterized of ultrahigh pressure and high strain rate (10 6 - 10 7s -1). Now, for different materials, we are able to form different metals to contours and shapes and simultaneity leave their surfaces in crack-resistant compressive stress state. The results show that the technology of laser shock wave can strengthen surface property and prolong fatigue life and especially can deform metals to shapes that could not be adequately made using conventional methods. With the development of the technology of laser shock wave, the applied fields of laser will become greater and greater.

  16. The development and testing of pulsed detonation engine ground demonstrators

    Science.gov (United States)

    Panicker, Philip Koshy

    2008-10-01

    The successful implementation of a PDE running on fuel and air mixtures will require fast-acting fuel-air injection and mixing techniques, detonation initiation techniques such as DDT enhancing devices or a pre-detonator, an effective ignition system that can sustain repeated firing at high rates and a fast and capable, closed-loop control system. The control system requires high-speed transducers for real-time monitoring of the PDE and the detection of the detonation wave speed. It is widely accepted that the detonation properties predicted by C-J detonation relations are fairly accurate in comparison to experimental values. The post-detonation flow properties can also be expressed as a function of wave speed or Mach number. Therefore, the PDE control system can use C-J relations to predict the post-detonation flow properties based on measured initial conditions and compare the values with those obtained from using the wave speed. The controller can then vary the initial conditions within the combustor for the subsequent cycle, by modulating the frequency and duty cycle of the valves, to obtain optimum air and fuel flow rates, as well as modulate the energy and timing of the ignition to achieve the required detonation properties. Five different PDE ground demonstrators were designed, built and tested to study a number of the required sub-systems. This work presents a review of all the systems that were tested, along with suggestions for their improvement. The PDE setups, ranged from a compact PDE with a 19 mm (3/4 in.) i.d., to two 25 mm (1 in.) i.d. setups, to a 101 mm (4 in.) i.d. dual-stage PDE setup with a pre-detonator. Propane-oxygen mixtures were used in the smaller PDEs. In the dual-stage PDE, propane-oxygen was used in the pre-detonator, while propane-air mixtures were used in the main combustor. Both rotary valves and solenoid valve injectors were studied. The rotary valves setups were tested at 10 Hz, while the solenoid valves were tested at up to 30 Hz

  17. The role of multidimensional instabilities in direct initiation of gaseous detonations in free space

    KAUST Repository

    Shen, Hua

    2017-01-20

    We numerically investigate the direct initiation of detonations driven by the propagation of a blast wave into a unconfined gaseous combustible mixture to study the role played by multidimensional instabilities in direct initiation of stable and unstable detonations. To this end, we first model the dynamics of unsteady propagation of detonation using the one-dimensional compressible Euler equations with a one-step chemical reaction model and cylindrical geometrical source terms. Subsequently, we use two-dimensional compressible Euler equations with just the chemical reaction source term to directly model cylindrical detonations. The one-dimensional results suggest that there are three regimes in the direct initiation for stable detonations, that the critical energy for mildly unstable detonations is not unique, and that highly unstable detonations are not self-sustainable. These phenomena agree well with one-dimensional theories and computations available in the literature. However, our two-dimensional results indicate that one-dimensional approaches are valid only for stable detonations. In mildly and highly unstable detonations, one-dimensional approaches break down because they cannot take the effects and interactions of multidimensional instabilities into account. In fact, instabilities generated in multidimensional settings yield the formation of strong transverse waves that, on one hand, increase the risk of failure of the detonation and, on the other hand, lead to the initiation of local over-driven detonations that enhance the overall self-sustainability of the global process. The competition between these two possible outcomes plays an important role in the direct initiation of detonations.

  18. Some recent advances of shock wave physics research at the Laboratory for Shock Wave and Detonation Physics Research

    CERN Document Server

    Jing Fu Qian

    2002-01-01

    Progress made in recent years on three topics that have been investigated at the Laboratory for Shock Wave and Detonation Physics Research are presented in this report. (1) A new equation of state (EOS) has been derived which can be used from a standard state to predict state variable change along an isobaric path. Good agreements between calculations for some representative metals using this new EOS and experiments have been found, covering a wide range from hundreds of MPa to hundreds of GPa and from ambient temperature to tens of thousands of GPa. (2) An empirical relation of Y/G = constant (Y is yield strength, G is shear modulus) at HT-HP has been reinvestigated and confirmed by shock wave experiment. 93W alloy was chosen as a model material. The advantage of this relation is that it is beneficial to formulate a kind of simplified constitutive equation for metallic solids under shock loading, and thus to faithfully describe the behaviours of shocked solids through hydrodynamic simulations. (3) An attempt...

  19. Laser-driven Mach waves for gigabar-range shock experiments

    Science.gov (United States)

    Swift, Damian; Lazicki, Amy; Coppari, Federica; Saunders, Alison; Nilsen, Joseph

    2017-10-01

    Mach reflection offers possibilities for generating planar, supported shocks at higher pressures than are practical even with laser ablation. We have studied the formation of Mach waves by algebraic solution and hydrocode simulation for drive pressures at much than reported previously, and for realistic equations of state. We predict that Mach reflection continues to occur as the drive pressure increases, and the pressure enhancement increases monotonically with drive pressure even though the ``enhancement spike'' characteristic of low-pressure Mach waves disappears. The growth angle also increases monotonically with pressure, so a higher drive pressure seems always to be an advantage. However, there are conditions where the Mach wave is perturbed by reflections. We have performed trial experiments at the Omega facility, using a laser-heated halfraum to induce a Mach wave in a polystyrene cone. Pulse length and energy limitations meant that the drive was not maintained long enough to fully support the shock, but the results indicated a Mach wave of 25-30 TPa from a drive pressure of 5-6 TPa, consistent with simulations. A similar configuration should be tested at the NIF, and a Z-pinch driven configuration may be possible. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  20. Study of a Model Equation in Detonation Theory

    KAUST Repository

    Faria, Luiz

    2014-04-24

    Here we analyze properties of an equation that we previously proposed to model the dynamics of unstable detonation waves [A. R. Kasimov, L. M. Faria, and R. R. Rosales, Model for shock wave chaos, Phys. Rev. Lett., 110 (2013), 104104]. The equation is ut+ 1/2 (u2-uu (0-, t))x=f (x, u (0-, t)), x > 0, t < 0. It describes a detonation shock at x = 0 with the reaction zone in x > 0. We investigate the nature of the steady-state solutions of this nonlocal hyperbolic balance law, the linear stability of these solutions, and the nonlinear dynamics. We establish the existence of instability followed by a cascade of period-doubling bifurcations leading to chaos. © 2014 Society for Industrial and Applied Mathematics.

  1. Study on guided waves in semiconductor lasers

    International Nuclear Information System (INIS)

    Pudensi, M.A.A.

    1980-01-01

    In This work we studied the guided waves in semiconductor lasers. In the first part we carried on the experimental measurements on lasers with stripe nonorthogonal to the mirrors. In the second part we developed a matrix method for the study of propagation and reflection of guided waves in lasers. (author) [pt

  2. Deflagration-to-detonation transition in gases in tubes with cavities

    Science.gov (United States)

    Smirnov, N. N.; Nikitin, V. F.; Phylippov, Yu. G.

    2010-12-01

    The existence of a supersonic second combustion mode — detonation — discovered by Mallard and Le Chatelier and by Berthélot and Vieille in 1881 posed the question of mechanisms for transition from one mode to the other. In the period 1959-1969, experiments by Salamandra, Soloukhin, Oppenheim, and their coworkers provided insights into this complex phenomenon. Since then, among all the phenomena related to combustion processes, deflagration-to-detonation transition is, undoubtedly, the most intriguing one. Deflagration-to-detonation transition (DDT) in gases is connected with gas and vapor explosion safety issues. Knowing mechanisms of detonation onset control is of major importance for creating effective mitigation measures addressing two major goals: to prevent DDT in the case of mixture ignition, or to arrest the detonation wave in the case where it has been initiated. A new impetus to the increase in interest in deflagration-to-detonation transition processes was given by the recent development of pulse detonation devices. The probable application of these principles to creation of a new generation of engines put the problem of effectiveness of pulse detonating devices at the top of current research needs. The effectiveness of the pulse detonation cycle turned out to be the key factor characterizing the Pulse Detonation Engine (PDE), whose operation modes were shown to be closely related to periodical onset and degeneration of a detonation wave. Those unsteady-state regimes should be self-sustained to guarantee a reliable operation of devices using the detonation mode of burning fuels as a constitutive part of their working cycle. Thus deflagration-to-detonation transition processes are of major importance for the issue. Minimizing the predetonation length and ensuring stability of the onset of detonation enable one to increase the effectiveness of a PDE. The DDT turned out to be the key factor characterizing the PDE operating cycle. Thus, the problem of

  3. A detonation model of high/low velocity detonation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shaoming; Li, Chenfang; Ma, Yunhua; Cui, Junmin [Xian Modern Chemistry Research Institute, Xian, 710065 (China)

    2007-02-15

    A new detonation model that can simulate both high and low velocity detonations is established using the least action principle. The least action principle is valid for mechanics and thermodynamics associated with a detonation process. Therefore, the least action principle is valid in detonation science. In this model, thermodynamic equilibrium state is taken as the known final point of the detonation process. Thermodynamic potentials are analogous to mechanical ones, and the Lagrangian function in the detonation process is L=T-V. Under certain assumptions, the variation calculus of the Lagrangian function gives two solutions: the first one is a constant temperature solution, and the second one is the solution of an ordinary differential equation. A special solution of the ordinary differential equation is given. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  4. Process Investigation of Tube Expansion by Gas Detonation

    OpenAIRE

    Bach, F.-W.; Beerwald, C.; Brosius, A.; Gershteyn, G.; Hermes, M.; Kleiner, M.; Olivier, H.; Weber, M.

    2006-01-01

    The present paper deals with the expansion of tubes by direct application of gas detonation waves, i.e. the gas is both pressure medium and energy source. After an introduction to gas detonation forming, measurements of the motion process and the internal pressures are presented. Results of free expansion and of forming into a die are thoroughly studied and compared to the results of quasi-static burst tests and hydroforming. Using pure aluminum Al99.5 and a medium strength alloy AlMgSi1, ...

  5. Development of a Gas-Fed Pulse Detonation Research Engine

    Science.gov (United States)

    Litchford, Ron J.; Hutt, John (Technical Monitor)

    2001-01-01

    In response to the growing need for empirical data on pulse detonation engine performance and operation, NASA Marshall Space Flight Center has developed and placed into operation a low-cost gas-fed pulse detonation research engine. The guiding design strategy was to achieve a simple and flexible research apparatus, which was inexpensive to build and operate. As such, the engine was designed to operate as a heat sink device, and testing was limited to burst-mode operation with run durations of a few seconds. Wherever possible, maximum use was made of standard off-the-shelf industrial or automotive components. The 5-cm diameter primary tube is about 90-cm long and has been outfitted with a multitude of sensor and optical ports. The primary tube is fed by a coaxial injector through an initiator tube, which is inserted directly into the injector head face. Four auxiliary coaxial injectors are also integrated into the injector head assembly. All propellant flow is controlled with industrial solenoid valves. An automotive electronic ignition system was adapted for use, and spark plugs are mounted in both tubes so that a variety of ignition schemes can be examined. A microprocessor-based fiber-optic engine control system was developed to provide precise control over valve and ignition timing. Initial shakedown testing with hydrogen/oxygen mixtures verified the need for Schelkin spirals in both the initiator and primary tubes to ensure rapid development of the detonation wave. Measured pressure wave time-of-flight indicated detonation velocities of 2.4 km/sec and 2.2 km/sec in the initiator and primary tubes, respectively. These values implied a fuel-lean mixture corresponding to an H2 volume fraction near 0.5. The axial distribution for the detonation velocity was found to be essentially constant along the primary tube. Time-resolved thrust profiles were also acquired for both underfilled and overfilled tube conditions. These profiles are consistent with previous time

  6. Saturation of Langmuir waves in laser-produced plasmas

    International Nuclear Information System (INIS)

    Baker, K.L.

    1996-04-01

    This dissertation deals with the interaction of an intense laser with a plasma (a quasineutral collection of electrons and ions). During this interaction, the laser drives large-amplitude waves through a class of processes known as parametric instabilities. Several such instabilities drive one type of wave, the Langmuir wave, which involves oscillations of the electrons relative to the nearly-stationary ions. There are a number of mechanisms which limit the amplitude to which Langmuir waves grow. In this dissertation, these mechanisms are examined to identify qualitative features which might be observed in experiments and/or simulations. In addition, a number of experiments are proposed to specifically look for particular saturation mechanisms. In a plasma, a Langmuir wave can decay into an electromagnetic wave and an ion wave. This parametric instability is proposed as a source for electromagnetic emission near half of the incident laser frequency observed from laser-produced plasmas. This interpretation is shown to be consistent with existing experimental data and it is found that one of the previous mechanisms used to explain such emission is not. The scattering version of the electromagnetic decay instability is shown to provide an enhanced noise source of electromagnetic waves near the frequency of the incident laser

  7. Combustion and Magnetohydrodynamic Processes in Advanced Pulse Detonation Rocket Engines

    Science.gov (United States)

    Cole, Lord Kahil

    A number of promising alternative rocket propulsion concepts have been developed over the past two decades that take advantage of unsteady combustion waves in order to produce thrust. These concepts include the Pulse Detonation Rocket Engine (PDRE), in which repetitive ignition, propagation, and reflection of detonations and shocks can create a high pressure chamber from which gases may be exhausted in a controlled manner. The Pulse Detonation Rocket Induced Magnetohydrodynamic Ejector (PDRIME) is a modification of the basic PDRE concept, developed by Cambier (1998), which has the potential for performance improvements based on magnetohydrodynamic (MHD) thrust augmentation. The PDRIME has the advantage of both low combustion chamber seeding pressure, per the PDRE concept, and efficient energy distribution in the system, per the rocket-induced MHD ejector (RIME) concept of Cole, et al. (1995). In the initial part of this thesis, we explore flow and performance characteristics of different configurations of the PDRIME, assuming quasi-one-dimensional transient flow and global representations of the effects of MHD phenomena on the gas dynamics. By utilizing high-order accurate solvers, we thus are able to investigate the fundamental physical processes associated with the PDRIME and PDRE concepts and identify potentially promising operating regimes. In the second part of this investigation, the detailed coupling of detonations and electric and magnetic fields are explored. First, a one-dimensional spark-ignited detonation with complex reaction kinetics is fully evaluated and the mechanisms for the different instabilities are analyzed. It is found that complex kinetics in addition to sufficient spatial resolution are required to be able to quantify high frequency as well as low frequency detonation instability modes. Armed with this quantitative understanding, we then examine the interaction of a propagating detonation and the applied MHD, both in one-dimensional and two

  8. Dynamics of the formation of the condensed phase particles at detonation of high explosives

    CERN Document Server

    Evdokov, O V; Kulipanov, G N; Luckjanchikov, L A; Lyakhov, N Z; Mishnev, S I; Sharafutdinov, M R; Sheromov, M A; Ten, K A; Titov, V M; Tolochko, B P; Zubkov, P I

    2001-01-01

    The article presents the results of the experimental study SAXS on condensed carbon particles that appear at the detonation of a high explosive. It was shown that the SAXS signal rises for 1.5-4 mu s after the detonation front passing. The SAXS signal in trotyl and its alloys with hexogen starts just after the compression of the material in the detonation wave. In octogen, hexogen and PETN, the SAXS signal appears in 0.5 mu s and is much smaller than the signal at the detonation of trotyl and its alloys with hexogen.

  9. Seismic waves travel-time curve, basing on the results of signal detection from chemical explosions detonated at Semipalatinsk Test Site

    International Nuclear Information System (INIS)

    Mikhajlova, N.N.; Aristova, I.L.; Germanova, T.I.

    2001-01-01

    A large amount of digital seismic data from the permanent and temporary seismic stations was acquired in the result of detonation of large chemical explosions at Semipalatinsk Test Site. All the records were collected, systematized and processed, and databases were created. Travel-time curves for regional Pn, Pg, Sn and Lg waves were created and compared with the ones used in routine earthquake processing practice. (author)

  10. A state of the art report on flame acceleration and transition to detonation in hydrogen/air/diluent mixtures

    International Nuclear Information System (INIS)

    Chan, C.K.; Tennankore, K.N.

    1991-12-01

    Accidental ignition in pockets of flammable hydrogen/air/diluent mixtures will lead to a deflagration wave (slow flame). Particular conditions can accelerate this flame and cause a transition from deflagration to a detonation wave (rapid flame), with its associated spatially non-uniform and very high pressures. In this report, the differences between deflagration and detonation are outlined, and the various flame acceleration mechanisms, along with the related research results, are reviewed. The current understanding of transition to detonation as a two-step process, a local explosion followed by an amplification of the resulting blast wave into a detonation wave, is described in detail. Occurrence of a local explosion in hot spots generated by the focussing of shock waves existing ahead of a fast flame, or in high-reactivity centres generated by turbulence-induced rapid mixing of flame and unburnt gas, and the resulting local quenching of the flame, are described and relevant publications are cited. The current models for flame acceleration are listed and their limitations are identified. Also, the available qualitative criteria for assessing the likelihood of transition to detonation under given conditions are briefly discussed. The feasibility of developing a quantitative methodology for assessing this likelihood is discussed, and further more work required to complete this development is outlined. The development of a quantitative methodology is recommended

  11. Development and application of theoretical models for Rotating Detonation Engine flowfields

    Science.gov (United States)

    Fievisohn, Robert

    As turbine and rocket engine technology matures, performance increases between successive generations of engine development are becoming smaller. One means of accomplishing significant gains in thermodynamic performance and power density is to use detonation-based heat release instead of deflagration. This work is focused on developing and applying theoretical models to aid in the design and understanding of Rotating Detonation Engines (RDEs). In an RDE, a detonation wave travels circumferentially along the bottom of an annular chamber where continuous injection of fresh reactants sustains the detonation wave. RDEs are currently being designed, tested, and studied as a viable option for developing a new generation of turbine and rocket engines that make use of detonation heat release. One of the main challenges in the development of RDEs is to understand the complex flowfield inside the annular chamber. While simplified models are desirable for obtaining timely performance estimates for design analysis, one-dimensional models may not be adequate as they do not provide flow structure information. In this work, a two-dimensional physics-based model is developed, which is capable of modeling the curved oblique shock wave, exit swirl, counter-flow, detonation inclination, and varying pressure along the inflow boundary. This is accomplished by using a combination of shock-expansion theory, Chapman-Jouguet detonation theory, the Method of Characteristics (MOC), and other compressible flow equations to create a shock-fitted numerical algorithm and generate an RDE flowfield. This novel approach provides a numerically efficient model that can provide performance estimates as well as details of the large-scale flow structures in seconds on a personal computer. Results from this model are validated against high-fidelity numerical simulations that may require a high-performance computing framework to provide similar performance estimates. This work provides a designer a new

  12. Thermodynamic Calculations of Hydrogen-Oxygen Detonation Parameters for Various Initial Pressures

    Science.gov (United States)

    Bollinger, Loren E.; Edse, Rudolph

    1961-01-01

    Composition, temperature, pressure and density behind a stable detonation wave and its propagation rate have been calculated for seven hydrogen-oxygen mixture at 1, 5, 25 and 100 atm initial pressure, and at an initial temperature of 40C. For stoichiometric mixtures that calculations also include an initial temperature of 200C. According to these calculations the detonation velocities of hydrogen-oxygen mixtures increase with increasing initial pressure, but decrease slightly when the initial temperature is raised from 40 to 200 C. The calculated detonation velocities agree satisfactorily with values determined experimentally. These values will be published in the near future.

  13. Structures in Detonation Waves in Low-Pressure H2–O2–Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

    Directory of Open Access Journals (Sweden)

    Ralf Deiterding

    2011-01-01

    Full Text Available Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniques in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.

  14. Modeling Hemispheric Detonation Experiments in 2-Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Howard, W M; Fried, L E; Vitello, P A; Druce, R L; Phillips, D; Lee, R; Mudge, S; Roeske, F

    2006-06-22

    Experiments have been performed with LX-17 (92.5% TATB and 7.5% Kel-F 800 binder) to study scaling of detonation waves using a dimensional scaling in a hemispherical divergent geometry. We model these experiments using an arbitrary Lagrange-Eulerian (ALE3D) hydrodynamics code, with reactive flow models based on the thermo-chemical code, Cheetah. The thermo-chemical code Cheetah provides a pressure-dependent kinetic rate law, along with an equation of state based on exponential-6 fluid potentials for individual detonation product species, calibrated to high pressures ({approx} few Mbars) and high temperatures (20000K). The parameters for these potentials are fit to a wide variety of experimental data, including shock, compression and sound speed data. For the un-reacted high explosive equation of state we use a modified Murnaghan form. We model the detonator (including the flyer plate) and initiation system in detail. The detonator is composed of LX-16, for which we use a program burn model. Steinberg-Guinan models5 are used for the metal components of the detonator. The booster and high explosive are LX-10 and LX-17, respectively. For both the LX-10 and LX-17, we use a pressure dependent rate law, coupled with a chemical equilibrium equation of state based on Cheetah. For LX-17, the kinetic model includes carbon clustering on the nanometer size scale.

  15. Computational Magnetohydrodynamics of General Materials in Generalized Coordinates and Applications to Laser-Target Interactions

    Science.gov (United States)

    MacGillivray, Jeff T.; Peterkin, Robert E., Jr.

    2003-10-01

    We have developed a multiblock arbitrary coordinate Hydromagnetics (MACH) code for computing the time-evolution of materials of arbitrary phase (solid, liquid, gas, and plasma) in response to forces that arise from material and magnetic pressures. MACH is a single-fluid, time-dependent, arbitrary Lagrangian-Eulerian (ALE) magnetohydrodynamic (MHD) simulation environment. The 2 1/2 -dimensional MACH2 and the parallel 3-D MACH3 are widely used in the MHD community to perform accurate simulation of the time evolution of electrically conducting materials in a wide variety of laboratory situations. In this presentation, we discuss simulations of the interaction of an intense laser beam with a solid target in an ambient gas. Of particular interest to us is a laser-supported detonation wave (blast wave) that originates near the surface of the target when the laser intensity is sufficiently large to vaporize target material within the focal spot of the beam. Because the MACH3 simulations are fully three-dimensional, we are able to simulate non-normal laser incidence. A magnetic field is also produced from plasma energy near the edge of the focal spot.

  16. STUDY OF THE DETONATION PHASE IN THE GRAVITATIONALLY CONFINED DETONATION MODEL OF TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Meakin, Casey A.; Townsley, Dean; Jordan, George C.; Truran, James; Lamb, Don; Seitenzahl, Ivo

    2009-01-01

    We study the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia) through the detonation phase and into homologous expansion. In the GCD model, a detonation is triggered by the surface flow due to single-point, off-center flame ignition in carbon-oxygen white dwarfs (WDs). The simulations are unique in terms of the degree to which nonidealized physics is used to treat the reactive flow, including weak reaction rates and a time-dependent treatment of material in nuclear statistical equilibrium (NSE). Careful attention is paid to accurately calculating the final composition of material which is burned to NSE and frozen out in the rapid expansion following the passage of a detonation wave over the high-density core of the WD; and an efficient method for nucleosynthesis postprocessing is developed which obviates the need for costly network calculations along tracer particle thermodynamic trajectories. Observational diagnostics are presented for the explosion models, including abundance stratifications and integrated yields. We find that for all of the ignition conditions studied here a self-regulating process comprised of neutronization and stellar expansion results in final 56 Ni masses of ∼1.1 M sun . But, more energetic models result in larger total NSE and stable Fe-peak yields. The total yield of intermediate mass elements is ∼0.1 M sun and the explosion energies are all around 1.5 x 10 51 erg. The explosion models are briefly compared to the inferred properties of recent SN Ia observations. The potential for surface detonation models to produce lower-luminosity (lower 56 Ni mass) SNe is discussed.

  17. Laser driven shock wave experiments for equation of state studies at megabar pressures

    CERN Document Server

    Pant, H C; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 mu m wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments.

  18. Laser driven shock wave experiments for equation of state studies at megabar pressures

    International Nuclear Information System (INIS)

    Pant, H C; Shukla, M; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 μm wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments

  19. Studies on the radioactive contamination due to nuclear detonations III. On the method of estimating the probable time of nuclear detonation from the measurements of gross-activity

    Energy Technology Data Exchange (ETDEWEB)

    Nishiwaki, Yasushi [Nuclear Reactor Laboratory, Tokyo Institute of Technology, Tokyo (Japan); Nuclear Reactor Laboratoroy, Kinki University, Fuse City, Osaka Precture (Japan)

    1961-11-25

    Since it has been observed in Spring of 1954 that a considerable amount of fission products mixture fell with the rain following a large scale nuclear detonation conducted in Bikini area in the South Pacific by the United States Atomic Energy Commission, it has become important, especially from the health physics standpoint, to estimate the effective average age of the fission products mixture after the nuclear detonation. If the energy transferred to the atmospheric air at the time of nuclear detonation is large enough (order of megaton at the distance of about 4000 km), the probable time and test site of nuclear detonation may be estimated with considerable accuracy, from the records of the pressure wave caused by the detonation in the microbarographs at different meteorological stations. Even in this case, in order to estimate the possible correlation between the artificial radioactivity observed in the rain and the probable detonation, it is often times desirable to estimate the effective age of the fission products mixture in the rain from the decay measurement of the radioactivity.

  20. Studies on the radioactive contamination due to nuclear detonations III. On the method of estimating the probable time of nuclear detonation from the measurements of gross-activity

    International Nuclear Information System (INIS)

    Nishiwaki, Yasushi

    1961-01-01

    Since it has been observed in Spring of 1954 that a considerable amount of fission products mixture fell with the rain following a large scale nuclear detonation conducted in Bikini area in the South Pacific by the United States Atomic Energy Commission, it has become important, especially from the health physics standpoint, to estimate the effective average age of the fission products mixture after the nuclear detonation. If the energy transferred to the atmospheric air at the time of nuclear detonation is large enough (order of megaton at the distance of about 4000 km), the probable time and test site of nuclear detonation may be estimated with considerable accuracy, from the records of the pressure wave caused by the detonation in the microbarographs at different meteorological stations. Even in this case, in order to estimate the possible correlation between the artificial radioactivity observed in the rain and the probable detonation, it is often times desirable to estimate the effective age of the fission products mixture in the rain from the decay measurement of the radioactivity

  1. GPU-based simulation of the two-dimensional unstable structure of gaseous oblique detonations

    Energy Technology Data Exchange (ETDEWEB)

    Teng, H.H.; Kiyanda, C.B.; Ng, H.D. [Department of Mechanical and Industrial Engineering, Concordia University, Montréal, QC, H3G 1M8 (Canada); Morgan, G.H.; Nikiforakis, N. [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE (United Kingdom)

    2015-03-10

    In this paper, the two-dimensional structure of unstable oblique detonations induced by the wedge from a supersonic combustible gas flow is simulated using the reactive Euler equations with a one-step Arrhenius chemistry model. A wide range of activation energy of the combustible mixture is considered. Computations are performed on the Graphical Processing Unit (GPU) to reduce the simulation runtimes. A large computational domain covered by a uniform mesh with high grid resolution is used to properly capture the development of instabilities and the formation of different transverse wave structures. After the initiation point, where the oblique shock transits into a detonation, an instability begins to manifest and in all cases, the left-running transverse waves first appear, followed by the subsequent emergence of right-running transverse waves forming the dual-head triple point structure. This study shows that for low activation energies, a long computational length must be carefully considered to reveal the unstable surface due to the slow growth rate of the instability. For high activation energies, the flow behind the unstable oblique detonation features the formation of unburnt gas pockets and strong vortex-pressure wave interaction resulting in a chaotic-like vortical structure.

  2. Traveling wave laser system

    International Nuclear Information System (INIS)

    Gregg, D.W.; Kidder, R.E.; Biehl, A.T.

    1975-01-01

    A method is described for generating a traveling wave laser pulse of almost unlimited energy content wherein a gain medium is pumped into a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)

  3. Numerical investigation of unsteady detonation waves in combustion chamber using Shchelkin spirals

    Directory of Open Access Journals (Sweden)

    Repaka Ramesh

    2016-09-01

    Full Text Available : Pulse Detonation Engine (PDE is considered to be a propulsive system of future air vehicles. The main objective is to minimizing the Deflagration to Detonation transition run-up distance and time by placing Shchelkin spiral with varying pitch length. Here we have considered blockage-area ratio is 0.5 as optimal value from review of previous studies. In the present study the detonation initiation and propagation is modeled numerically using commercial CFD codes GAMBIT and FLUENT. The unsteady and two-dimensional compressible Reynolds Averaged Navier-Stokes equation is used to simulate the model. Fuel-air mixture of Hydrogen-air is used for better efficiency of PDE. It is very simple straight tube with Shchelkin spirals, one of the methods which is used to initiate detonation is creation of high pressure and temperature chamber region with 0.5cm from closed end of tube where shock will generate and transition into low pressure and temperature region propagates towards end of the tube. Two different zones namely high and low pressure zones are used as interface in modeling and patching has been used to fill the zones with hydrogen and oxygen with different pressure and temperatures hence shock leads to propagate inside the combustion chamber.

  4. Turbulent deflagrations, autoignitions, and detonations

    KAUST Repository

    Bradley, Derek

    2012-09-01

    Measurements of turbulent burning velocities in fan-stirred explosion bombs show an initial linear increase with the fan speed and RMS turbulent velocity. The line then bends over to form a plateau of high values around the maximum attainable burning velocity. A further increase in fan speed leads to the eventual complete quenching of the flame due to increasing localised extinctions because of the flame stretch rate. The greater the Markstein number, the more readily does flame quenching occur. Flame propagation along a duct closed at one end, with and without baffles to increase the turbulence, is subjected to a one-dimensional analysis. The flame, initiated at the closed end of the long duct, accelerates by the turbulent feedback mechanism, creating a shock wave ahead of it, until the maximum turbulent burning velocity for the mixture is attained. With the confining walls, the mixture is compressed between the flame and the shock plane up to the point where it might autoignite. This can be followed by a deflagration to detonation transition. The maximum shock intensity occurs with the maximum attainable turbulent burning velocity, and this defines the limit for autoignition of the mixture. For more reactive mixtures, autoignition can occur at turbulent burning velocities that are less than the maximum attainable one. Autoignition can be followed by quasi-detonation or fully developed detonation. The stability of ensuing detonations is discussed, along with the conditions that may lead to their extinction. © 2012 by Pleiades Publishing, Ltd.

  5. Characterizing the energy output generated by a standard electric detonator using shadowgraph imaging

    Science.gov (United States)

    Petr, V.; Lozano, E.

    2017-09-01

    This paper overviews a complete method for the characterization of the explosive energy output from a standard detonator. Measurements of the output of explosives are commonly based upon the detonation parameters of the chemical energy content of the explosive. These quantities provide a correct understanding of the energy stored in an explosive, but they do not provide a direct measure of the different modes in which the energy is released. This optically based technique combines high-speed and ultra-high-speed imaging to characterize the casing fragmentation and the detonator-driven shock load. The procedure presented here could be used as an alternative to current indirect methods—such as the Trauzl lead block test—because of its simplicity, high data accuracy, and minimum demand for test repetition. This technique was applied to experimentally measure air shock expansion versus time and calculating the blast wave energy from the detonation of the high explosive charge inside the detonator. Direct measurements of the shock front geometry provide insight into the physics of the initiation buildup. Because of their geometry, standard detonators show an initial ellipsoidal shock expansion that degenerates into a final spherical wave. This non-uniform shape creates variable blast parameters along the primary blast wave. Additionally, optical measurements are validated using piezoelectric pressure transducers. The energy fraction spent in the acceleration of the metal shell is experimentally measured and correlated with the Gurney model, as well as to several empirical formulations for blasts from fragmenting munitions. The fragment area distribution is also studied using digital particle imaging analysis and correlated with the Mott distribution. Understanding the fragmentation distribution plays a critical role when performing hazard evaluation from these types of devices. In general, this technique allows for characterization of the detonator within 6-8% error

  6. Reflection Patterns Generated by Condensed-Phase Oblique Detonation Interaction with a Rigid Wall

    Science.gov (United States)

    Short, Mark; Chiquete, Carlos; Bdzil, John; Meyer, Chad

    2017-11-01

    We examine numerically the wave reflection patterns generated by a detonation in a condensed phase explosive inclined obliquely but traveling parallel to a rigid wall as a function of incident angle. The problem is motivated by the characterization of detonation-material confiner interactions. We compare the reflection patterns for two detonation models, one where the reaction zone is spatially distributed, and the other where the reaction is instantaneous (a Chapman-Jouguet detonation). For the Chapman-Jouguet model, we compare the results of the computations with an asymptotic study recently conducted by Bdzil and Short for small detonation incident angles. We show that the ability of a spatially distributed reaction energy release to turn flow streamlines has a significant impact on the nature of the observed reflection patterns. The computational approach uses a shock-fit methodology.

  7. Biological effects of laser-induced stress waves

    International Nuclear Information System (INIS)

    Doukas, A.; Lee, S.; McAuliffe, D.

    1995-01-01

    Laser-induced stress waves can be generated by one of the following mechanisms: Optical breakdown, ablation or rapid heating of an absorbing medium. These three modes of laser interaction with matter allow the investigation of cellular and tissue responses to stress waves with different characteristics and under different conditions. The most widely studied phenomena are those of the collateral damage seen in photodisruption in the eye and in 193 run ablation of cornea and skin. On the other hand, the therapeutic application of laser-induced stress waves has been limited to the disruption of noncellular material such as renal stones, atheromatous plaque and vitreous strands. The effects of stress waves to cells and tissues can be quite disparate. Stress waves can fracture tissue, damage cells, and increase the permeability of the plasma membrane. The viability of cell cultures exposed to stress waves increases with the peak stress and the number of pulses applied. The rise time of the stress wave also influences the degree of cell injury. In fact, cell viability, as measured by thymidine incorporation, correlates better with the stress gradient than peak stress. Recent studies have also established that stress waves induce a transient increase of the permeability of the plasma membrane in vitro. In addition, if the stress gradient is below the damage threshhold, the cells remain viable. Thus, stress waves can be useful as a means of drug delivery, increasing the intracellular drug concentration and allowing the use of drugs which are impermeable to the cell membrane. The present studies show that it is important to create controllable stress waves. The wavelength tunability and the micropulse structure of the free electron laser is ideal for generating stress waves with independently adjustable parameters, such as rise time, duration and peak stress

  8. Laser-Bioplasma Interaction: Excitation and Suppression of the Brain Waves by the Multi-photon Pulsed-operated Fiber Lasers in the Ultraviolet Range of Frequencies

    Science.gov (United States)

    Stefan, V. Alexander; IAPS-team Team

    2017-10-01

    The novel study of the laser excitation-suppression of the brain waves is proposed. It is based on the pulsed-operated multi-photon fiber-laser interaction with the brain parvalbumin (PV) neurons. The repetition frequency matches the low frequency brain waves (5-100 Hz); enabling the resonance-scanning of the wide range of the PV neurons (the generators of the brain wave activity). The tunable fiber laser frequencies are in the ultraviolet frequency range, thus enabling the monitoring of the PV neuron-DNA, within the 10s of milliseconds. In medicine, the method can be used as an ``instantaneous-on-off anesthetic.'' Supported by Nikola Tesla Labs, Stefan University.

  9. Towards Integrated Pulse Detonation Propulsion and MHD Power

    Science.gov (United States)

    Litchford, Ron J.; Thompson, Bryan R.; Lineberry, John T.

    1999-01-01

    The interest in pulse detonation engines (PDE) arises primarily from the advantages that accrue from the significant combustion pressure rise that is developed in the detonation process. Conventional rocket engines, for example, must obtain all of their compression from the turbopumps, while the PDE provides additional compression in the combustor. Thus PDE's are expected to achieve higher I(sub sp) than conventional rocket engines and to require smaller turbopumps. The increase in I(sub sp) and the decrease in turbopump capacity must be traded off against each other. Additional advantages include the ability to vary thrust level by adjusting the firing rate rather than throttling the flow through injector elements. The common conclusion derived from these aggregated performance attributes is that PDEs should result in engines which are smaller, lower in cost, and lighter in weight than conventional engines. Unfortunately, the analysis of PDEs is highly complex due to their unsteady operation and non-ideal processes. Although the feasibility of the basic PDE concept has been proven in several experimental and theoretical efforts, the implied performance improvements have yet to be convincingly demonstrated. Also, there are certain developmental issues affecting the practical application of pulse detonation propulsion systems which are yet to be fully resolved. Practical detonation combustion engines, for example, require a repetitive cycle of charge induction, mixing, initiation/propagation of the detonation wave, and expulsion/scavenging of the combustion product gases. Clearly, the performance and power density of such a device depends upon the maximum rate at which this cycle can be successfully implemented. In addition, the electrical energy required for direct detonation initiation can be significant, and a means for direct electrical power production is needed to achieve self-sustained engine operation. This work addresses the technological issues associated

  10. Wave function of free electron in a strong laser plasma

    International Nuclear Information System (INIS)

    Zhu Shitong; Shen Wenda; Guo Qizhi

    1993-01-01

    The wave function of free electron in a strong laser plasma is obtained by solving exactly the Dirac equation in a curved space-time with optical metric for the laser plasma. When the laser field is diminished to zero, the wave function is naturally reduced to relativistic wave function of free electron. The possible application of the wave function is discussed

  11. The equation of state of predominant detonation products

    Science.gov (United States)

    Zaug, Joseph; Crowhurst, Jonathan; Bastea, Sorin; Fried, Laurence

    2009-06-01

    The equation of state of detonation products, when incorporated into an experimentally grounded thermochemical reaction algorithm can be used to predict the performance of explosives. Here we report laser based Impulsive Stimulated Light Scattering measurements of the speed of sound from a variety of polar and nonpolar detonation product supercritical fluids and mixtures. The speed of sound data are used to improve the exponential-six potentials employed within the Cheetah thermochemical code. We will discuss the improvements made to Cheetah in terms of predictions vs. measured performance data for common polymer blended explosives. Accurately computing the chemistry that occurs from reacted binder materials is one important step forward in our efforts.

  12. Propagation velocities of laser-produced plasmas from copper wire targets and water droplets

    Science.gov (United States)

    Song, Kyo-Dong; Alexander, Dennis R.

    1994-01-01

    Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire target (75 microns diameter) and water droplets (75 microns diameter) at irradiance levels ranging from 25 to 150 GW/sq cm. Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximately = 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/sq cm, the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(exp 5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/sq cm showed a quantitative agreement within approximately 50% while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma liquid droplets obtained by previous research are compared with current work.

  13. Shock wave science and technology reference library

    CERN Document Server

    2009-01-01

    This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov) Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a t...

  14. Detonative propagation and accelerative expansion of the Crab Nebula shock front.

    Science.gov (United States)

    Gao, Yang; Law, Chung K

    2011-10-21

    The accelerative expansion of the Crab Nebula's outer envelope is a mystery in dynamics, as a conventional expanding blast wave decelerates when bumping into the surrounding interstellar medium. Here we show that the strong relativistic pulsar wind bumping into its surrounding nebula induces energy-generating processes and initiates a detonation wave that propagates outward to form the current outer edge, namely, the shock front, of the nebula. The resulting detonation wave, with a reactive downstream, then provides the needed power to maintain propagation of the shock front. Furthermore, relaxation of the curvature-induced reduction of the propagation velocity from the initial state of formation to the asymptotic, planar state of Chapman-Jouguet propagation explains the observed accelerative expansion. Potential richness in incorporating reactive fronts in the description of various astronomical phenomena is expected. © 2011 American Physical Society

  15. LIGO: the Laser Interferometer Gravitational-Wave Observatory

    International Nuclear Information System (INIS)

    Abbott, B P; Abbott, R; Adhikari, R; Anderson, S B; Araya, M; Armandula, H; Aso, Y; Ballmer, S; Ajith, P; Allen, B; Aulbert, C; Allen, G; Amin, R S; Anderson, W G; Armor, P; Arain, M A; Aston, S; Aufmuth, P; Babak, S; Baker, P

    2009-01-01

    The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves (GWs) of astrophysical origin. Direct detection of GWs holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black holes and neutron stars and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech-MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than one part in 10 21 . With this unprecedented sensitivity, the data are being analyzed to detect or place limits on GWs from a variety of potential astrophysical sources.

  16. Stabilized lasers for advanced gravitational wave detectors

    International Nuclear Information System (INIS)

    Willke, B; Danzmann, K; Kwee, P; Seifert, F; Frede, M; Kracht, D; Puncken, O; Schulz, B; Veltkamp, C; Wagner, S; Wessels, P; Winkelmann, L; King, P; Savage, R L Jr

    2008-01-01

    Second generation gravitational wave detectors require high power lasers with more than 100 W of output power and with very low temporal and spatial fluctuations. To achieve the demanding stability levels required, low noise techniques and adequate control actuators have to be part of the high power laser design. In addition feedback control and passive noise filtering is used to reduce the fluctuations in the so-called prestabilized laser system (PSL). In this paper, we discuss the design of a 200 W PSL which is under development for the Advanced LIGO gravitational wave detector and will present the first results. The PSL noise requirements for advanced gravitational wave detectors will be discussed in general and the stabilization scheme proposed for the Advanced LIGO PSL will be described

  17. Plasma wave amplitude measurement created by guided laser wakefield

    International Nuclear Information System (INIS)

    Wojda, Franck

    2010-01-01

    The interaction of an intense laser pulse of short duration with a plasma produces a plasma wave with large amplitude in its wake, which is associated with a longitudinal electric field. It can be used to accelerate relativistic electrons injected into the wave to energies in the GeV range over distances of the order of a few centimeters, short compared to acceleration lengths in conventional accelerators. The control of the electron beam characteristics during the acceleration process is fundamental for achieving a usable laser-plasma acceleration stage. The main result of this thesis is the creation and characterization of a plasma wave in a weakly nonlinear regime over a length of several centimeters. Capillary tubes are used to guide the laser beam over these distances, while maintaining a large enough intensity (∼ 10 17 W/cm 2 ). The guided laser beam ionizes the gas in the tube and creates the plasma wave. A diagnostic based on the modification of the laser pulse spectrum was used to determine the amplitude of the plasma wave along the tube. The amplitude of the plasma wave was studied as a function of gas filling pressure, length of the capillary and laser energy. Experimental results are compared; they are in excellent agreement with analytical results and modeling. They show that the electric field associated with the plasma wave is between 1 and 10 GV/m over a length of up to 8 cm. This work has demonstrated the ability to create a controlled plasma wave in a weakly nonlinear regime. (author)

  18. Effect of turbulence on deflagration to detonation transition

    Energy Technology Data Exchange (ETDEWEB)

    Radford, D D; Chan, C K [Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Labs.; Azad, R S [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Mechanical Engineering

    1996-12-31

    The interaction of a turbulent jet and an expanding flame kernel was examined using spark-schlieren photography and piezoelectric pressure transducers. Experiments were performed in a 9 by 9 cm, 4-m-long shock channel. Results show that an expanding flame kernel can be locally, or partially, quenched by flame stretching. The mixing of the hot combustion products, containing reactive species, with the unburnt gas in the turbulent flame-jet, created pockets of sensitized mixture. The subsequent re-ignition of the sensitized mixture could result in a local explosion. In a number of experiments the blast waves produced in the local explosion developed into detonation waves. A local explosion occurred only if there was partial quenching of the flame kernel. Partial quenching occurs when the Karlovitz-Kovaszney factor approaches unity and, therefore, it is possible to establish a set of conditions in terms of turbulent parameters for the transition to detonation. (author). 16 refs., 13 figs.

  19. Effect of turbulence on deflagration to detonation transition

    International Nuclear Information System (INIS)

    Radford, D.D.; Chan, C.K.; Azad, R.S.

    1995-01-01

    The interaction of a turbulent jet and an expanding flame kernel was examined using spark-schlieren photography and piezoelectric pressure transducers. Experiments were performed in a 9 by 9 cm, 4-m-long shock channel. Results show that an expanding flame kernel can be locally, or partially, quenched by flame stretching. The mixing of the hot combustion products, containing reactive species, with the unburnt gas in the turbulent flame-jet, created pockets of sensitized mixture. The subsequent re-ignition of the sensitized mixture could result in a local explosion. In a number of experiments the blast waves produced in the local explosion developed into detonation waves. A local explosion occurred only if there was partial quenching of the flame kernel. Partial quenching occurs when the Karlovitz-Kovaszney factor approaches unity and, therefore, it is possible to establish a set of conditions in terms of turbulent parameters for the transition to detonation. (author). 16 refs., 13 figs

  20. Transmission of an overdriven plane detonation in lean hydrogen-air mixtures

    International Nuclear Information System (INIS)

    Desbordes, D.; Lannoy, A.

    1988-01-01

    This paper deals with hydrogen-air explosions hazards in nuclear power plants, if PWR Loss Of Coolant Accident occurs. The main objective concerns the determination of the size of the critical diameter of transmission of a detonation propagating in a near stoechiometric H 2 -Air mixture. In such a situation the diffracting detonation is an overdriven wave. Laboratory scale simulations are described which emphasize the importance of a negative step of concentration of combustible in a mixture (stoechio to lean) on plane detonation characteristics of the lean mixture, especially the drastric reduction (i) of the size of its inrinsic tridimensional structure and (ii) correlatively that of the critical diameter of transmission of the mixture

  1. Investigations into detonations of coal dust suspensions in oxygen-nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.; Fearnley, P.; Nettleton, M.

    1987-03-01

    The effect of particle size (practically monodispersed), volatile content and composition of gaseous oxygen-nitrogen mixtures on initiating flame acceleration rates in coal dust suspensions is investigated experimentally. Description is given of apparatus, material used and experiments carried out. The authors discusses: microwave interferograms, pressure oscillograms for various oxygen-nitrogen mixtures; development of ionization front speed in relation to distance from diaphragm; effect of composition on shock wave advance rates. It is concluded that: microwave interferometry can successfully be used in recording initiation of coal dust suspension detonations; ignition of confined coal dust suspensions by shock waves originated by detonation front in stoichiometric oxyacetylene mixtures can be explained by heating of coal particles in shock compression stream to ignition temperature (1000 K) by combined convection and radiation heat transfer. 16 refs.

  2. Optical phase locking of two infrared continuous wave lasers separated by 100 THz

    Czech Academy of Sciences Publication Activity Database

    Chiodo, N.; Du-Burck, F.; Hrabina, Jan; Lours, M.; Chea, E.; Acef, O.

    2014-01-01

    Roč. 39, č. 10 (2014), s. 2936-2939 ISSN 0146-9592 R&D Projects: GA ČR GPP102/11/P820; GA MŠk ED0017/01/01; GA MŠk EE2.4.31.0016; GA MŠk(CZ) LO1212; GA MŠk(CZ) 7AMB14FR040 Institutional support: RVO:68081731 Keywords : Continuous wave lasers * Frequency allocation * Harmonic generation * Laser optics Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.292, year: 2014

  3. High-resolution Hydrodynamic Simulation of Tidal Detonation of a Helium White Dwarf by an Intermediate Mass Black Hole

    Science.gov (United States)

    Tanikawa, Ataru

    2018-05-01

    We demonstrate tidal detonation during a tidal disruption event (TDE) of a helium (He) white dwarf (WD) with 0.45 M ⊙ by an intermediate mass black hole using extremely high-resolution simulations. Tanikawa et al. have shown tidal detonation in results of previous studies from unphysical heating due to low-resolution simulations, and such unphysical heating occurs in three-dimensional (3D) smoothed particle hydrodynamics (SPH) simulations even with 10 million SPH particles. In order to avoid such unphysical heating, we perform 3D SPH simulations up to 300 million SPH particles, and 1D mesh simulations using flow structure in the 3D SPH simulations for 1D initial conditions. The 1D mesh simulations have higher resolutions than the 3D SPH simulations. We show that tidal detonation occurs and confirm that this result is perfectly converged with different space resolution in both 3D SPH and 1D mesh simulations. We find that detonation waves independently arise in leading parts of the WD, and yield large amounts of 56Ni. Although detonation waves are not generated in trailing parts of the WD, the trailing parts would receive detonation waves generated in the leading parts and would leave large amounts of Si group elements. Eventually, this He WD TDE would synthesize 56Ni of 0.30 M ⊙ and Si group elements of 0.08 M ⊙, and could be observed as a luminous thermonuclear transient comparable to SNe Ia.

  4. Response of a reactor building due to detonation of flat layered gas clouds

    International Nuclear Information System (INIS)

    Frik, G.

    1984-05-01

    The stress of the containment of a PWR plant of today is calculated for the loading of three detonating flat layered gas clouds. The dynamic response of the structure due to the blast wave is determined and comparisons are made with previous results of the detonating stochiometric gas cloud and with results of the individual task 11A (GRS). The calculations were realized with the method of modal superposition and linear elastic material laws. The stress conditions of the structure were comprehended by three loading cases of the flat, layered gas clouds. The first loading case B(a) leads to high stresses, which are not interpretable with a linear analysis. On the other hand, the loading case B(b) leads to stresses which are not much above and B(c) to stresses which are not much below the yield stress. It is demonstrated for a linear analysis, that the structure will not be injured by the detonation wave of case B(c). (orig./HP) [de

  5. Phase velocity of nonlinear plasma waves in the laser beat-wave accelerator

    International Nuclear Information System (INIS)

    Spence, W.L.

    1985-01-01

    The suggested plasma-laser accelerator is an attempt to achieve a very high energy gradient by resonantly exciting a longitudinal wave traveling at close to the speed of light in cold plasma by means of the beat-wave generated by the transverse fields in two laser beams. Previous calculations to all orders in v/sub z/ have been done essentially from the laboratory frame point of view and have treated the plasma wave as having sharply defined phase velocity equal to the speed of light. However a high energy particle beam undergoing acceleration sees the plasma wave from a nearly light-like frame of reference and hence is very sensitive to small deviations in its phase velocity. Here the authors introduce a calculational scheme that includes all orders in v/sub z/ and in the plasma density, and additionally takes into account the influence of plasma nonlinearities on the wave's phase velocity. The main assumption is that the laser frequencies are very large compared to the plasma frequency - under which they are able to in essence formally sum up all orders of forward Raman scattering. They find that the nonlinear plasma wave does not have simply a single phase velocity - it is really a superposition of many - but that the beat-wave which drives it is usefully described by a non-local effective phase velocity function

  6. Amplification of pressure waves in laser-assisted endodontics with synchronized delivery of Er:YAG laser pulses.

    Science.gov (United States)

    Lukač, Nejc; Jezeršek, Matija

    2018-05-01

    When attempting to clean surfaces of dental root canals with laser-induced cavitation bubbles, the resulting cavitation oscillations are significantly prolonged due to friction on the cavity walls and other factors. Consequently, the collapses are less intense and the shock waves that are usually emitted following a bubble's collapse are diminished or not present at all. A new technique of synchronized laser-pulse delivery intended to enhance the emission of shock waves from collapsed bubbles in fluid-filled endodontic canals is reported. A laser beam deflection probe, a high-speed camera, and shadow photography were used to characterize the induced photoacoustic phenomena during synchronized delivery of Er:YAG laser pulses in a confined volume of water. A shock wave enhancing technique was employed which consists of delivering a second laser pulse at a delay with regard to the first cavitation bubble-forming laser pulse. Influence of the delay between the first and second laser pulses on the generation of pressure and shock waves during the first bubble's collapse was measured for different laser pulse energies and cavity volumes. Results show that the optimal delay between the two laser pulses is strongly correlated with the cavitation bubble's oscillation period. Under optimal synchronization conditions, the growth of the second cavitation bubble was observed to accelerate the collapse of the first cavitation bubble, leading to a violent collapse, during which shock waves are emitted. Additionally, shock waves created by the accelerated collapse of the primary cavitation bubble and as well of the accompanying smaller secondary bubbles near the cavity walls were observed. The reported phenomena may have applications in improved laser cleaning of surfaces during laser-assisted dental root canal treatments.

  7. Comparison of acoustic shock waves generated by micro and nanosecond lasers for a smart laser surgery system

    Science.gov (United States)

    Nguendon Kenhagho, Hervé K.; Rauter, Georg; Guzman, Raphael; C. Cattin, Philippe; Zam, Azhar

    2018-02-01

    Characterization of acoustic shock wave will guarantee efficient tissue differentiation as feedback to reduce the probability of undesirable damaging (i.e. cutting) of tissues in laser surgery applications. We ablated hard (bone) and soft (muscle) tissues using a nanosecond pulsed Nd:YAG laser at 532 nm and a microsecond pulsed Er:YAG laser at 2.94 μm. When the intense short ns-pulsed laser is applied to material, the energy gain causes locally a plasma at the ablated spot that expands and propagates as an acoustic shock wave with a rarefaction wave behind the shock front. However, when using a μs-pulsed Er:YAG laser for material ablation, the acoustic shock wave is generated during the explosion of the ablated material. We measured and compared the emitted acoustic shock wave generated by a ns-pulsed Nd:YAG laser and a μs-pulsed Er:YAG laser measured by a calibrated microphone. As the acoustic shock wave attenuates as it propagates through air, the distance between ablation spots and a calibrated microphone was at 5 cm. We present the measurements on the propagation characteristics of the laser generated acoustic shock wave by measuring the arrival time-of-flight with a calibrated microphone and the energy-dependent evolution of acoustic parameters such as peak-topeak pressure, the ratio of the peak-to-peak pressures for the laser induced breakdown in air, the ablated muscle and the bone, and the spectral energy.

  8. On detonation dynamics in hydrogen-air-steam mixtures: Theory and application to Olkiluoto reactor building

    International Nuclear Information System (INIS)

    Silde, A.; Lindholm, I.

    2000-02-01

    This report consists of the literature study of detonation dynamics in hydrogen-air-steam mixtures, and the assessment of shock pressure loads in Olkiluoto 1 and 2 reactor building under detonation conditions using the computer program DETO developed during this work at VTT. The program uses a simple 1-D approach based on the strong explosion theory, and accounts for the effects of both the primary or incident shock and the first (oblique or normal) reflected shock from a wall structure. The code results are also assessed against a Balloon experiment performed at Germany, and the classical Chapman-Jouguet detonation theory. The whole work was carried out as a part of Nordic SOS-2.3 project, dealing with severe accident analysis. The initial conditions and gas distribution of the detonation calculations are based on previous severe accident analyses by MELCOR and FLUENT codes. According to DETO calculations, the maximum peak pressure in a structure of Olkiluoto reactor building room B60-80 after normal shock reflection was about 38.7 MPa if a total of 3.15 kg hydrogen was assumed to burned in a distance of 2.0 m from the wall structure. The corresponding pressure impulse was about 9.4 kPa-s. The results were sensitive to the distance used. Comparison of the results to classical C-J theory and the Balloon experiments suggested that DETO code represented a conservative estimation for the first pressure spike under the shock reflection from a wall in Olkiluoto reactor building. Complicated 3-D phenomena of shock wave reflections and focusing, nor the propagation of combustion front behind the shock wave under detonation conditions are not modeled in the DETO code. More detailed 3-D analyses with a specific detonation code are, therefore, recommended. In spite of the code simplifications, DETO was found to be a beneficial tool for simple first-order assessments of the structure pressure loads under the first reflection of detonation shock waves. The work on assessment

  9. High-order shock-fitted detonation propagation in high explosives

    Science.gov (United States)

    Romick, Christopher M.; Aslam, Tariq D.

    2017-03-01

    A highly accurate numerical shock and material interface fitting scheme composed of fifth-order spatial and third- or fifth-order temporal discretizations is applied to the two-dimensional reactive Euler equations in both slab and axisymmetric geometries. High rates of convergence are not typically possible with shock-capturing methods as the Taylor series analysis breaks down in the vicinity of discontinuities. Furthermore, for typical high explosive (HE) simulations, the effects of material interfaces at the charge boundary can also cause significant computational errors. Fitting a computational boundary to both the shock front and material interface (i.e. streamline) alleviates the computational errors associated with captured shocks and thus opens up the possibility of high rates of convergence for multi-dimensional shock and detonation flows. Several verification tests, including a Sedov blast wave, a Zel'dovich-von Neumann-Döring (ZND) detonation wave, and Taylor-Maccoll supersonic flow over a cone, are utilized to demonstrate high rates of convergence to nontrivial shock and reaction flows. Comparisons to previously published shock-capturing multi-dimensional detonations in a polytropic fluid with a constant adiabatic exponent (PF-CAE) are made, demonstrating significantly lower computational error for the present shock and material interface fitting method. For an error on the order of 10 m /s, which is similar to that observed in experiments, shock-fitting offers a computational savings on the order of 1000. In addition, the behavior of the detonation phase speed is examined for several slab widths to evaluate the detonation performance of PBX 9501 while utilizing the Wescott-Stewart-Davis (WSD) model, which is commonly used in HE modeling. It is found that the thickness effect curve resulting from this equation of state and reaction model using published values is dramatically more steep than observed in recent experiments. Utilizing the present fitting

  10. A Study on non-contact measurements of laser-generated lamb waves

    International Nuclear Information System (INIS)

    Jang, Tae Seong; Lee, Jung Ju; Lee, Seung Seok

    2002-01-01

    Generation and detection of Lamb waves offer an effective non-destructive testing technique that will detect defects quickly and reliably. Lamb waves are generated in a thin plate by Q-switched Nd:YAG pulsed laser. Symmetric and antisymmetric Lamb modes in low-frequency-thickness regime are excited by illuminating a thin plate with an array of laser-generated line sources. The propagation of laser-generated Lamb waves is detected by measuring the out-of-plane displacements in a non-contact manner using the fiber optic Sagnac interferometer and all commercial adaptive reference-beam interferometer. The characteristics of laser-generated Lamb wave due to its frequency are investigated. Fundamental understanding of laser-generated Lamb modes is presented.

  11. Effect of the three-dimensional structure of laser emission on the dynamics of low-threshold optical breakdown plasmas

    Science.gov (United States)

    Anisimov, V. N.; Arutiunian, R. V.; Bol'Shov, L. A.; Derkach, O. N.; Kanevskii, M. F.

    1989-03-01

    The effect of the transverse structure of pulsed CO2 laser emission on the dynamics of laser-induced detonation waves propagating from a metal surface and on plasma transparency recovery is investigated theoretically and experimentally. Particular attention is given to breakdown initiation near the surface. It is suggested that the inclusion of refraction in the plasma into a self-consistent numerical mode is essential for the adequate quantitative description of experimental data on the interaction of laser emission with low-threshold optical breakdown plasmas.

  12. Hypersonic wave drag reduction performance of cylinders with repetitive laser energy depositions

    International Nuclear Information System (INIS)

    Fang, J; Hong, Y J; Li, Q; Huang, H

    2011-01-01

    It has been widely research that wave drag reduction on hypersonic vehicle by laser energy depositions. Using laser energy to reduce wave drag can improve vehicle performance. A second order accurate scheme based on finite-difference method and domain decomposition of structural grid is used to compute the drag performance of cylinders in a hypersonic flow of Mach number 2 at altitude of 15km with repetitive energy depositions. The effects of frequency on drag reduction are studied. The calculated results show: the recirculation zone is generated due to the interaction between bow shock over the cylinder and blast wave produced by energy deposition, and a virtual spike which is supported by an axis-symmetric recirculation, is formed in front of the cylinder. By increasing the repetitive frequency, the drag is reduced and the oscillation of the drag is decreased; however, the energy efficiency decreases by increasing the frequency.

  13. Dynamics of Laser-Driven Shock Waves in Solid Targets

    Science.gov (United States)

    Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J.; Schmitt, A. J.; Obenschain, S. P.; Grun, J.; Metzler, N.; Zalesak, S. T.; Gardner, J. H.; Oh, J.; Harding, E. C.

    2009-11-01

    Accurate shock timing is a key issue of both indirect- and direct-drive laser fusions. The experiments on the Nike laser at NRL presented here were made possible by improvements in the imaging capability of our monochromatic x-ray diagnostics based on Bragg reflection from spherically curved crystals. Side-on imaging implemented on Nike makes it possible to observe dynamics of the shock wave and ablation front in laser-driven solid targets. We can choose to observe a sequence of 2D images or a continuous time evolution of an image resolved in one spatial dimension. A sequence of 300 ps snapshots taken using vanadium backlighter at 5.2 keV reveals propagation of a shock wave in a solid plastic target. The shape of the shock wave reflects the intensity distribution in the Nike beam. The streak records with continuous time resolution show the x-t trajectory of a laser-driven shock wave in a 10% solid density DVB foam.

  14. Precursors in detonations in porous explosives

    International Nuclear Information System (INIS)

    Spaulding, R.L. Jr.

    1981-01-01

    Photographs of detonation waves in low-density HMX and PETN, made with an image-intensifier camera, show a brilliant band of light in front of the pressure jump. The radiation temperature is estimated to be 12,000 to 14,000 0 K. The spectrum of this light is continuous. A quartz gauge shows a gradual buildup of pressure from the material producing the light. The material has little effect on the propagation of detonation. Further observations, using pellets of plastic-bonded HMX and single crystals of PETN, show that the material thrown off the free surface is transparent, with a leading edge moving at approximately 20 mm/μs. Collision of this material with polymethyl methacrylate (PMMA) produces a brilliant light with a spectrum that is initially a narrow H/sub α/ line. Quartz gauges measure the rate of pessure buildup of this material

  15. Toward continuous-wave operation of organic semiconductor lasers

    Science.gov (United States)

    Sandanayaka, Atula S. D.; Matsushima, Toshinori; Bencheikh, Fatima; Yoshida, Kou; Inoue, Munetomo; Fujihara, Takashi; Goushi, Kenichi; Ribierre, Jean-Charles; Adachi, Chihaya

    2017-01-01

    The demonstration of continuous-wave lasing from organic semiconductor films is highly desirable for practical applications in the areas of spectroscopy, data communication, and sensing, but it still remains a challenging objective. We report low-threshold surface-emitting organic distributed feedback lasers operating in the quasi–continuous-wave regime at 80 MHz as well as under long-pulse photoexcitation of 30 ms. This outstanding performance was achieved using an organic semiconductor thin film with high optical gain, high photoluminescence quantum yield, and no triplet absorption losses at the lasing wavelength combined with a mixed-order distributed feedback grating to achieve a low lasing threshold. A simple encapsulation technique greatly reduced the laser-induced thermal degradation and suppressed the ablation of the gain medium otherwise taking place under intense continuous-wave photoexcitation. Overall, this study provides evidence that the development of a continuous-wave organic semiconductor laser technology is possible via the engineering of the gain medium and the device architecture. PMID:28508042

  16. Investigations on deflagration to detonation transition in porous energetic materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States)

    1999-07-01

    The research carried out by this contract was part of a larger effort funded by LANL in the areas of deflagration to detonation in porous energetic materials (DDT) and detonation shock dynamics in high explosives (DSD). In the first three years of the contract the major focus was on DDT. However, some researchers were carried out on DSD theory and numerical implementation. In the last two years the principal focus of the contract was on DSD theory and numerical implementation. However, during the second period some work was also carried out on DDT. The paper discusses DDT modeling and DSD modeling. Abstracts are included on the following topics: modeling deflagration to detonation; DSD theory; DSD wave front tracking; and DSD program burn implementation.

  17. Guided-wave tomography imaging plate defects by laser-based ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun Pil; Lim, Ju Young; Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Pusan (Korea, Republic of)

    2014-12-15

    Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

  18. The elimination of pump depletion in laser-plasma beat-wave accelerators

    International Nuclear Information System (INIS)

    Ma Jinxiu; Xu Zhizhan

    1988-01-01

    The pump depletion is a severe problem which hinders the laser-plasma beat-wave accelerator concept from being practical. Starting with the weak relativistic equation of beat-wave excitation of electron plasma waves, the authors have derived the condition for eliminating the pump depletion in the fame moving with the light pulse for arbitrary pulse shapes. It is shown that the depletion can be eliminated by a phase jump of π at the center of the pump pulse and by the appropriated choice of initial plasma density detuning. The numerical calculation have yielded the dependence of the initial detuning on the pump intensity for square pump pulses, and have supported the methods used in this paper

  19. Improved ion acceleration via laser surface plasma waves excitation

    Energy Technology Data Exchange (ETDEWEB)

    Bigongiari, A. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); TIPS/LULI, Université Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilée, 94200 Ivry-sur-Seine (France); Raynaud, M. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Riconda, C. [TIPS/LULI, Université Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilée, 94200 Ivry-sur-Seine (France); Héron, A. [CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2013-05-15

    The possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10λ{sub 0}), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities ranging from 10{sup 19} to 10{sup 20} Wcm{sup −2}μm{sup 2}. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find an enhancement of the maximum ion energy of a factor ∼2 compared to the cases where the target surface is flat.

  20. Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target

    Czech Academy of Sciences Publication Activity Database

    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.; Krouský, Eduard; Labate, L.; Parys, P.; Pfeifer, Miroslav; Renner, Oldřich; Šmíd, Michal; Rosinski, M.; Skála, Jiří; Dudžák, Roman; Ullschmied, Jiří; Pisarczyk, P.

    2014-01-01

    Roč. 21, č. 1 (2014), 012708/1-012708/7 ISSN 1070-664X R&D Projects: GA MŠk LM2010014; GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : Energy transfer * laser ablation * shock waves * plasma waves * laser beam effects Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (FZU-D) Impact factor: 2.142, year: 2014 http://scitation.aip.org/content/aip/journal/pop/21/1/10.1063/1.4862784

  1. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.; Gerlach, L.; Malliakos, A.

    1995-01-01

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant product,s and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below

  2. Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.

    1996-01-01

    The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant products, and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below

  3. Simulating sympathetic detonation using the hydrodynamic models and constitutive equations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Hoon; Kim, Min Sung; Yoh, Jack J. [Dept. of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Sun, Tae Boo [Hanwha Corporation Defense Rand D Center, Daejeon (Korea, Republic of)

    2016-12-15

    A Sympathetic detonation (SD) is a detonation of an explosive charge by a nearby explosion. Most of times it is unintended while the impact of blast fragments or strong shock waves from the initiating donor explosive is the cause of SD. We investigate the SD of a cylindrical explosive charge (64 % RDX, 20 % Al, 16 % HTPB) contained in a steel casing. The constitutive relations for high explosive are obtained from a thermo-chemical code that provides the size effect data without the rate stick data typically used for building the rate law and equation of state. A full size SD test of eight pallet-packaged artillery shells is performed that provides the pressure data while the hydrodynamic model with proper constitutive relations for reactive materials and the fragmentation model for steel casing is conducted to replicate the experimental findings. The work presents a novel effort to accurately model and reproduce the sympathetic detonation event with a reduced experimental effort.

  4. Analysis of supercritical vapor explosions using thermal detonation wave theory

    Energy Technology Data Exchange (ETDEWEB)

    Shamoun, B.I.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States)

    1995-09-01

    The interaction of certain materials such as Al{sub 2}O{sub 3} with water results in vapor explosions with very high (supercritical) pressures and propagation velocities. A quasi-steady state analysis of supercritical detonation in one-dimensional multiphase flow was applied to analyze experimental data of the KROTOS (26-30) set of experiments conducted at the Joint Research Center at Ispra, Italy. In this work we have applied a new method of solution which allows for partial fragmentation of the fuel in the shock adiabatic thermodynamic model. This method uses known experiment values of the shock pressure and propagation velocity to estimate the initial mixing conditions of the experiment. The fuel and coolant were both considered compressible in this analysis. In KROTOS 26, 28, 29, and 30 the measured values of the shock pressure by the experiment were found to be higher than 25, 50, 100, and 100 Mpa respectively. Using the above data for the wave velocity and our best estimate for the values of the pressure, the predicted minimum values of the fragmented mass of the fuel were found to be 0.026. 0.04, 0.057, and 0.068 kg respectively. The predicted values of the work output corresponding to the above fragmented masses of the fuel were found to be 40, 84, 126, and 150 kJ respectively, with predicted initial void fractions of 112%, 12.5%, 8%, and 6% respectively.

  5. Optical wave microphone measurement during laser ablation of Si

    Energy Technology Data Exchange (ETDEWEB)

    Mitsugi, Fumiaki, E-mail: mitsugi@cs.kumamoto-u.ac.jp [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto, 860-8555 (Japan); Ide, Ryota; Ikegami, Tomoaki [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto, 860-8555 (Japan); Nakamiya, Toshiyuki; Sonoda, Yoshito [Graduate School of Industrial Engineering, Tokai University, 9-1-1 Toroku, Kumamoto, 862-8652 (Japan)

    2012-10-30

    Pulsed laser irradiation is used for surface treatment of a solid and ablation for particle formation in gas, liquid or supercritical phase media. When a pulsed laser is used to irradiate a solid, spatial refractive index variations (including photothermal expansion, shockwaves and particles) occur, which vary depending on the energy density of the pulsed laser. We focused on this phenomenon and applied an unique method for detection of refractive index variation using an optical wave microphone based on Fraunhofer diffraction. In this research, we analyzed the waveforms and frequencies of refractive index variations caused by pulsed laser irradiation of silicon in air and measured with an optical wave microphone.

  6. Blast-Wave Generation and Propagation in Rapidly Heated Laser-Irradiated Targets

    Science.gov (United States)

    Ivancic, S. T.; Stillman, C. R.; Nilson, P. M.; Solodov, A. A.; Froula, D. H.

    2017-10-01

    Time-resolved extreme ultraviolet (XUV) spectroscopy was used to study the creation and propagation of a >100-Mbar blast wave in a target irradiated by an intense (>1018WWcm2 cm2) laser pulse. Blast waves provide a platform to generate immense pressures in the laboratory. A temporal double flash of XUV radiation was observed when viewing the rear side of the target, which is attributed to the emergence of a blast wave following rapid heating by a fast-electron beam generated from the laser pulse. The time-history of XUV emission in the photon energy range of 50 to 200 eV was recorded with an x-ray streak camera with 7-ps temporal resolution. The heating and expansion of the target was simulated with an electron transport code coupled to 1-D radiation-hydrodynamics simulations. The temporal delay between the two flashes measured in a systematic study of target thickness and composition was found to evolve in good agreement with a Sedov-Taylor blast-wave solution. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and Department of Energy Office of Science Award Number DE-SC-0012317.

  7. Influence of acoustic waves on TEA CO2 laser performance

    CSIR Research Space (South Africa)

    Von Bergmann, H

    2007-01-01

    Full Text Available In this paper the author’s present results on the influence of acoustic waves on the output laser beam from high repetition rate TEA CO2 lasers. The authors show that acoustic waves generated inside the cavity lead to deterioration in beam quality...

  8. Fine Tuning the CJ Detonation Speed of a High Explosive products Equation of State

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-12

    For high explosive (HE) simulations, inaccuracies of a per cent or two in the detonation wave speed can result from not suficiently resolving the reaction zone width or from small inaccuracies in calibrating the products equation of state (EOS) or from variation of HE lots. More accurate detonation speeds can be obtained by ne tuning the equation of state to compensate. Here we show that two simple EOS transformations can be used to adjust the CJ detonation speed by a couple of per cent with minimal effect on the CJ release isentrope. The two transformations are (1) a shift in the energy origin and (2) a linear scaling of the speci c volume. The effectiveness of the transformations is demonstrated with simulations of the cylinder test for PBX 9502 starting with a products EOS for which the CJ detonation speed is 1 per cent too low.

  9. The study of waves, instabilities, and turbulence using Thomson scattering in laser plasmas

    International Nuclear Information System (INIS)

    Drake, R.P.

    1995-01-01

    Much basic work in plasma physics has been devoted to the study of wave properties in plasmas, one of the nonlinear development of driven waves, and of the instabilities in which such waves may participate. The use of laser-plasma techniques has allowed one to extend such studies into new regimes. Such techniques and their results are the subject here. Once one chooses a physical problem within this subject area, it is now possible to design a laser-plasma experiment that is optimized for the study of that problem. The plasma can be designed to have a variety of density and flow-velocity profiles, the damping of ion acoustic waves and of electron plasma waves can be independently controlled, and the waves can be driven weakly or strongly. By using Nd-glass lasers and their harmonics one can non-invasively drive and diagnose the waves, using separate laser beams to produce the plasma, drive the waves, and diagnose their properties. The author uses as examples some recent work with his collaborators, including the first experimental detection of ion plasma waves and the first direct observation of the plasma wave driven by the acoustic decay of laser light

  10. Evaluation of Straight and Swept Ramp Obstacles on Enhancing Deflagration-to-Detonation Transition in Pulse Detonation Engines

    Science.gov (United States)

    2006-12-01

    This led to the work of H. Le Chatelier and E. Mallard, who in 1883 conducted experiments to examine the detonation process more closely. Their work...describes the history of research into detonation and the principles that govern detonation theory. A. DETONATION HISTORY 1. Early Research in...these favorable properties and for a propulsion system and is a principle means of detonation initiation in pulse detonation engines. DDT refers to a

  11. Traveling-wave laser-produced-plasma energy source for photoionization laser pumping and lasers incorporating said

    Science.gov (United States)

    Sher, Mark H.; Macklin, John J.; Harris, Stephen E.

    1989-09-26

    A traveling-wave, laser-produced-plasma, energy source used to obtain single-pass gain saturation of a photoionization pumped laser. A cylindrical lens is used to focus a pump laser beam to a long line on a target. Grooves are cut in the target to present a surface near normal to the incident beam and to reduce the area, and hence increase the intensity and efficiency, of plasma formation.

  12. Shock Waves Science and Technology Library

    CERN Document Server

    2012-01-01

    This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with the fundamental theory of detonation physics in gaseous and condensed phase reactive media. The detonation process involves complex chemical reaction and fluid dynamics, accompanied by intricate effects of heat, light, electricity and magnetism - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The seven extensive chapters contained in this volume are: - Chemical Equilibrium Detonation (S. Bastea and LE Fried) - Steady One-Dimensional Detonations (A Higgins) - Detonation Instability (HD Ng and F Zhang) - Dynamic Parameters of Detonation (AA Vasiliev) - Multi-Scaled Cellular Detonation (D Desbordes and HN Presles) - Condensed Matter Detonation: Theory and Practice (C Tarver) - Theory of Detonation Shock Dynamics (JB Bdzil and DS Stewart) The chapters are thematically interrelated in a systematic descriptive appro...

  13. Improved estimates of separation distances to prevent unacceptable damage to nuclear power plant structures from hydrogen detonation for gaseous hydrogen storage. Technical report

    International Nuclear Information System (INIS)

    1994-05-01

    This report provides new estimates of separation distances for nuclear power plant gaseous hydrogen storage facilities. Unacceptable damage to plant structures from hydrogen detonations will be prevented by having hydrogen storage facilities meet separation distance criteria recommended in this report. The revised standoff distances are based on improved calculations on hydrogen gas cloud detonations and structural analysis of reinforced concrete structures. Also, the results presented in this study do not depend upon equivalencing a hydrogen detonation to an equivalent TNT detonation. The static and stagnation pressures, wave velocity, and the shock wave impulse delivered to wall surfaces were computed for several different size hydrogen explosions. Separation distance equations were developed and were used to compute the minimum separation distance for six different wall cases and for seven detonating volumes (from 1.59 to 79.67 lbm of hydrogen). These improved calculation results were compared to previous calculations. The ratio between the separation distance predicted in this report versus that predicted for hydrogen detonation in previous calculations varies from 0 to approximately 4. Thus, the separation distances results from the previous calculations can be either overconservative or unconservative depending upon the set of hydrogen detonation parameters that are used. Consequently, it is concluded that the hydrogen-to-TNT detonation equivalency utilized in previous calculations should no longer be used

  14. Detonation mode and frequency analysis under high loss conditions for stoichiometric propane-oxygen

    KAUST Repository

    Jackson, Scott; Lee, Bok Jik; Shepherd, Joseph E.

    2016-01-01

    The propagation characteristics of galloping detonations were quantified with a high-time-resolution velocity diagnostic. Combustion waves were initiated in 30-m lengths of 4.1-mm inner diameter transparent tubing filled with stoichiometric propane

  15. Resolution Enhancement of Scanning Laser Acoustic Microscope Using Transverse Wave

    International Nuclear Information System (INIS)

    Ko, D. S.; Park, J. S.; Kim, Y. H.

    1997-01-01

    We studied the resolution enhancement of a novel scanning laser acoustic microscope (SLAM) using transverse waves. Mode conversion of the ultrasonic wave takes place at the liquid-solid interface and some energy of the insonifying longitudinal waves in the water will convert to transverse wave energy within the solid specimen. The resolution of SLAM depends on the size of detecting laser spot and the wavelength of the insonifying ultrasonic waves. Science the wavelength of the transverse wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution by using transverse waves. In order to operate SLAM in the transverse wave mode, we made wedge for changing the incident angle. Our experimental results with model 2140 SLAM and an aluminum specimen showed higher contrast of the SLAM image in the transverse wave mode than that in the longitudinal wave mode

  16. GLINT. Gravitational-wave laser INterferometry triangle

    Science.gov (United States)

    Aria, Shafa; Azevedo, Rui; Burow, Rick; Cahill, Fiachra; Ducheckova, Lada; Holroyd, Alexa; Huarcaya, Victor; Järvelä, Emilia; Koßagk, Martin; Moeckel, Chris; Rodriguez, Ana; Royer, Fabien; Sypniewski, Richard; Vittori, Edoardo; Yttergren, Madeleine

    2017-11-01

    When the universe was roughly one billion years old, supermassive black holes (103-106 solar masses) already existed. The occurrence of supermassive black holes on such short time scales are poorly understood in terms of their physical or evolutionary processes. Our current understanding is limited by the lack of observational data due the limits of electromagnetic radiation. Gravitational waves as predicted by the theory of general relativity have provided us with the means to probe deeper into the history of the universe. During the ESA Alpach Summer School of 2015, a group of science and engineering students devised GLINT (Gravitational-wave Laser INterferometry Triangle), a space mission concept capable of measuring gravitational waves emitted by black holes that have formed at the early periods after the big bang. Morespecifically at redshifts of 15 big bang) in the frequency range 0.01 - 1 Hz. GLINT design strain sensitivity of 5× 10^{-24} 1/√ { {Hz}} will theoretically allow the study of early black holes formations as well as merging events and collapses. The laser interferometry, the technology used for measuring gravitational waves, monitors the separation of test masses in free-fall, where a change of separation indicates the passage of a gravitational wave. The test masses will be shielded from disturbing forces in a constellation of three geocentric orbiting satellites.

  17. Guided-wave tomographic imaging of plate defects by laser-based ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junpil; Lim, Ju Young; Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

    2016-12-15

    Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

  18. Effect of pre-combustion characteristics in pulse detonation engine using shchelkin spiral

    Directory of Open Access Journals (Sweden)

    C. T. Dheeraj Kumar Singh

    2016-09-01

    Full Text Available Pulse detonation engines are the modern propulsive device which provides high thrust. They are unsteady propulsive devices which has multi cycle operations in it. In this multi cycle process for every cycle fuel and air are initiated and a shock wave is generated in combustion chamber in form of deflagration. Combustion chamber is maintained with high pressure and high temperature which leads to combustion of reactants. This deflagration transmits to detonation with high velocity and increasing Mach number. Deflagration propagates forward by taking all unburned species and products formed after combustion. Propagation of Deflagration – Detonation Transition (DDT shock wave studies is a pioneering research concept. In the present study, simulation of PDE with Shchelkin spiral geometry is considered with two mass flow inlets has been used in which one is for fuel inlet and other for oxidizer. Geometry and meshing has been done in Gambit. Fuel used is gaseous fuel hydrogen and oxidizer is air mixture of O2, N2 work has been performed for different mass flow rates of fuel and oxidizer. Energy equation, Species transport equation to be solved in Fluent. Comparison results of DDT in parameters of mach number, velocity, pressure and temperatures depending on different time steps have been observed

  19. Investigations on detonation shock dynamics and related topics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States). Dept. of Theoretical and Applied Mechanics

    1993-11-01

    This document is a final report that summarizes the research findings and research activities supported by the subcontract DOE-LANL-9-XG8-3931P-1 between the University of Illinois (D. S. Stewart Principal Investigator) and the University of California (Los Alamos National Laboratory, M-Division). The main focus of the work has been on investigations of Detonation Shock Dynamics. A second emphasis has been on modeling compaction of energetic materials and deflagration to detonation in those materials. The work has led to a number of extensions of the theory of Detonation Shock Dynamics (DSD) and its application as an engineering design method for high explosive systems. The work also enhanced the hydrocode capabilities of researchers in M-Division by modifications to CAVEAT, an existing Los Alamos hydrocode. Linear stability studies of detonation flows were carried out for the purpose of code verification. This work also broadened the existing theory for detonation. The work in this contract has led to the development of one-phase models for dynamic compaction of porous energetic materials and laid the groundwork for subsequent studies. Some work that modeled the discrete heterogeneous behavior of propellant beds was also performed. The contract supported the efforts of D. S. Stewart and a Postdoctoral student H. I. Lee at the University of Illinois.

  20. Excitation of accelerating plasma waves by counter-propagating laser beams

    International Nuclear Information System (INIS)

    Shvets, Gennady; Fisch, Nathaniel J.; Pukhov, Alexander

    2002-01-01

    The conventional approach to exciting high phase velocity waves in plasmas is to employ a laser pulse moving in the direction of the desired particle acceleration. Photon downshifting then causes momentum transfer to the plasma and wave excitation. Novel approaches to plasma wake excitation, colliding-beam accelerator (CBA), which involve photon exchange between the long and short counter-propagating laser beams, are described. Depending on the frequency detuning Δω between beams and duration τ L of the short pulse, there are two approaches to CBA. First approach assumes (τ L ≅2/ω p ). Photons exchanged between the beams deposit their recoil momentum in the plasma driving the plasma wake. Frequency detuning between the beams determines the direction of the photon exchange, thereby controlling the phase of the plasma wake. This phase control can be used for reversing the slippage of the accelerated particles with respect to the wake. A variation on the same theme, super-beatwave accelerator, is also described. In the second approach, a short pulse with τ L >>ω p -1 detuned by Δω∼2ω p from the counter-propagating beam is employed. While parametric excitation of plasma waves by the electromagnetic beatwave at 2ω p of two co-propagating lasers was first predicted by Rosenbluth and Liu [M. N. Rosenbluth and C. S. Liu, Phys. Rev. Lett. 29, 701 (1972)], it is demonstrated that the two excitation beams can be counter-propagating. The advantages of using this geometry (higher instability growth rate, insensitivity to plasma inhomogeneity) are explained, and supporting numerical simulations presented

  1. Detonation of hydrogen-air mixtures

    International Nuclear Information System (INIS)

    Lee, J.H.S.; Knystautas, R.; Benedick, W.B.

    1983-01-01

    The detonation of a hydrogen-air cloud subsequent to an accidental release of hydrogen into ambient surroundings cannot be totally ruled out in view of the relative sensitivity of the hydrogen-air system. The present paper investigates the key parameters involved in hydrogen-air detonations and attempts to establish quantitative correlations between those that have important practical implications. Thus, for example, the characteristic length scale lambda describing the cellular structure of a detonation front is measured for a broad range of hydrogen-air mixtures and is quantitatively correlated with the key dynamic detonation properties such as detonability, transmission and initiation

  2. Stabilized High Power Laser for Advanced Gravitational Wave Detectors

    International Nuclear Information System (INIS)

    Willke, B; Danzmann, K; Fallnich, C; Frede, M; Heurs, M; King, P; Kracht, D; Kwee, P; Savage, R; Seifert, F; Wilhelm, R

    2006-01-01

    Second generation gravitational wave detectors require high power lasers with several 100W of output power and with very low temporal and spatial fluctuations. In this paper we discuss possible setups to achieve high laser power and describe a 200W prestabilized laser system (PSL). The PSL noise requirements for advanced gravitational wave detectors will be discussed in general and the stabilization scheme proposed for the Advanced LIGO PSL will be described. Special emphasis will be given to the most demanding power stabilization requirements and new results (RIN ≤ 4x10 -9 /√Hz) will be presented

  3. Cw hyper-Raman laser and four-wave mixing in atomic sodium

    Science.gov (United States)

    Klug, M.; Kablukov, S. I.; Wellegehausen, B.

    2005-01-01

    Continuous wave hyper-Raman (HR) generation in a ring cavity on the 6s → 4p transition at 1640 nm in sodium is realized for the first time by two-photon excitation of atomic sodium on the 3s → 6s transition with a continuous wave (cw) dye laser at 590 nm and a single frequency argon ion laser at 514 nm. It is shown, that the direction and efficiency of HR lasing depends on the propagation direction of the pump waves and their frequencies. More than 30% HR gain is measured at 250 mW of pump laser powers for counter-propagating pump waves and a medium length of 90 mm. For much shorter interaction lengths and corresponding focussing of the pump waves a dramatic increase of the gain is predicted. For co-propagating pump waves, in addition, generation of 330 nm radiation on the 4p → 3s transition by a four-wave mixing (FWM) process is observed. Dependencies of HR and parametric four-wave generation have been investigated and will be discussed.

  4. Model for Shock Wave Chaos

    KAUST Repository

    Kasimov, Aslan R.

    2013-03-08

    We propose the following model equation, ut+1/2(u2−uus)x=f(x,us) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x=0 for any t≥0. Here, us(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

  5. Development of SMM wave laser scattering apparatus for the measurements of waves and turbulences in the tokamak plasma

    International Nuclear Information System (INIS)

    Saito, T.; Hamada, Y.; Yamashita, T.; Ikeda, M.; Nakamura, M.

    1980-01-01

    The SMM wave laser scattering apparatus has been developed for the measurement of the waves and turbulences in the plasma. This apparatus will help greatly to clarify the physics of RF heating of the tokamak plasma. The present status of main parts of the apparatus, the SMM wave laser and the Schottky barrier diode mixer for the heterodyne receiver, are described. (author)

  6. Optical wave microphone measurements of laser ablation of copper in supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Mitsugi, Fumiaki, E-mail: mitsugi@cs.kumamoto-u.ac.jp [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Ikegami, Tomoaki [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Nakamiya, Toshiyuki; Sonoda, Yoshito [Graduate School of Industrial Engineering, Tokai University, 9-1-1 Toroku, Kumamoto 862-8652 (Japan)

    2013-11-29

    Laser ablation plasma in a supercritical fluid has attracted much attention recently due to its usefulness in forming nanoparticles. Observation of the dynamic behavior of the supercritical fluid after laser irradiation of a solid is necessary for real-time monitoring and control of laser ablation. In this study, we utilized an optical wave microphone to monitor pulsed laser irradiation of a solid in a supercritical fluid. The optical wave microphone works based on Fraunhofer diffraction of phase modulation of light by changes in refractive index. We hereby report on our measurements for pulsed laser irradiation of a Cu target in supercritical carbon dioxide using an optical wave microphone. Photothermal acoustic waves which generated after single pulsed laser irradiation of a Cu target were detectable in supercritical carbon dioxide. The speed of sound around the critical point of supercritical carbon dioxide was clearly slower than that in gas. The optical wave microphone detected a signal during laser ablation of Cu in supercritical carbon dioxide that was caused by shockwave degeneration. - Highlights: • Photothermal acoustic wave in supercritical fluid was observed. • Sound speed around the critical point was slower than that in gas. • Optical wave microphone detected degeneration of a shockwave. • Ablation threshold of a solid in supercritical fluid can be estimated. • Generation of the second shockwave in supercritical phase was suggested.

  7. Estimating heats of detonation and detonation velocities of aromatic energetic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Keshavarz, Mohammad Hossein [Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr, P. O. Box 83145/115 (Iran)

    2008-12-15

    A new method is introduced to predict reliable estimation of heats of detonation of aromatic energetic compounds. At first step, this procedure assumes that the heat of detonation of an explosive compound of composition C{sub a}H{sub b}N{sub c}O{sub d} can be approximated as the difference between the heat of formation of all H{sub 2}O-CO{sub 2} arbitrary (H{sub 2}O, CO{sub 2}, N{sub 2}) detonation products and that of the explosive, divided by the formula weight of the explosive. Overestimated results based on (H{sub 2}O-CO{sub 2} arbitrary) can be corrected in the next step. Predicted heats of detonation of pure energetic compounds with the product H{sub 2}O in the liquid state for 31 aromatic energetic compounds have a root mean square (rms) deviation of 2.08 and 0.34 kJ g{sup -1} from experiment for (H{sub 2}O-CO{sub 2} arbitrary) and new method, respectively. The new method also gives good results as compared to the second sets of decomposition products, which consider H{sub 2},N{sub 2}, H{sub 2}O,CO, and CO{sub 2} as major gaseous products. It is shown here how the predicted heats of detonation by the new method can be used to obtain reliable estimation of detonation velocity over a wide range of loading densities. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  8. The hydrodynamic theory of detonation

    Science.gov (United States)

    Langweiler, Heinz

    1939-01-01

    This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed. The latent energy of the explosive passes into the steadily growing detonation zone - the region between the detonation front and the rarefaction front. The conclusions lead to a new definition of the concept of shattering power. The calculations are based on the behavior of trinitrotoluene.

  9. Laser amplitude stabilization for advanced interferometric gravitational wave detectors

    International Nuclear Information System (INIS)

    Barr, B W; Strain, K A; Killow, C J

    2005-01-01

    We present results of experiments into the stabilization of the amplitude of Nd:YAG lasers for use in advanced gravitational wave detectors. By feeding back directly to the pump-diode driving current we achieved shot-noise-limited stabilization at frequencies up to several kHz with some residual noise at lower frequencies (sub ∼100 Hz). The method used is applicable to higher powered laser systems planned for advanced interferometric gravitational wave detectors

  10. On the fast gas ionization wave in an intense laser beam

    International Nuclear Information System (INIS)

    Fisher, V.I.

    1980-01-01

    The transfer of the adsorption zone of laser radiation along a beam is considered. It is shown that for a sufficiently strong laser beam intensity, q 0 >q tilde, the conditions of wave propagation differ principally from those known previously. In particular, the plasma temperature behind the wave front Tsup(*) decreases with the increase of q 0 , whereas the wave velocity D(q 0 ) grows faster than a linear function. The structure and laws of propagation of the ionization wave are determined

  11. Equations of state of detonation products: ammonia and methane

    Science.gov (United States)

    Lang, John; Dattelbaum, Dana; Goodwin, Peter; Garcia, Daniel; Coe, Joshua; Leiding, Jeffery; Gibson, Lloyd; Bartram, Brian

    2015-06-01

    Ammonia (NH3) and methane (CH4) are two principal product gases resulting from explosives detonation, and the decomposition of other organic materials under shockwave loading (such as foams). Accurate thermodynamic descriptions of these gases are important for understanding the detonation performance of high explosives. However, shock compression data often do not exist for molecular species in the dense gas phase, and are limited in the fluid phase. Here, we present equation of state measurements of elevated initial density ammonia and methane gases dynamically compressed in gas-gun driven plate impact experiments. Pressure and density of the shocked gases on the principal Hugoniot were determined from direct particle velocity and shock wave velocity measurements recorded using optical velocimetry (Photonic Doppler velocimetry (PDV) and VISAR (velocity interferometer system for any reflector)). Streak spectroscopy and 5-color pyrometry were further used to measure the emission from the shocked gases, from which the temperatures of the shocked gases were estimated. Up to 0.07 GPa, ammonia was not observed to ionize, with temperature remaining below 7000 K. These results provide quantitative measurements of the Hugoniot locus for improving equations of state models of detonation products.

  12. Wireless guided wave and impedance measurement using laser and piezoelectric transducers

    International Nuclear Information System (INIS)

    Park, Hyun-Jun; Sohn, Hoon; Yun, Chung-Bang; Chung, Joseph; Lee, Michael M S

    2012-01-01

    Guided-wave- and impedance-based structural health monitoring (SHM) techniques have gained much attention due to their high sensitivity to small defects. One of the popular devices commonly used for guided wave and impedance measurements is a lead zirconate titanate (PZT) transducer. This study proposes a new wireless scheme where the power and data required for PZT excitation and sensing are transmitted via laser. First, a modulated laser beam is wirelessly transmitted to the photodiode connected to a PZT on a structure. Then, the photodiode converts the laser light into an electric signal, and it is applied to the PZT for excitation. The corresponding responses, impedance at the same PZT or guided waves at another PZT, are measured, re-converted into laser light, and wirelessly transmitted back to the other photodiode located in the data interrogator for signal processing. The feasibility of the proposed wireless guided wave and impedance measurement schemes has been examined through circuit analyses and experimentally investigated in a laboratory setup. (paper)

  13. Turbulent flame acceleration and detonation quenching and reinitiation - modelling and validation

    International Nuclear Information System (INIS)

    Fischer, M.; Kratzel, T.; Pantow, E.

    1997-01-01

    For both, the reactor safety in an accidental release of hydrogen into containment compartments and also for the industrial safety of the production, storage and transport of combustibles like hydrogen, propane, methane and others in the Petroleum, Petrochemical and Pharmaceutical Industries, it is of great interest to know how the pressure forces of fast hydrogen combustion processes can be reduced. The numerical study of highly turbulent or detonation driven flame propagation processes is relatively recent because it depends on the availability of high performance computers and specialized numerical algorithms to solve the governing equations of reactive fluid dynamic processes. Numerical simulation can be used at a number of levels to study turbulent combustion and detonations. What is needed is both, to use modelling and numerical simulation to investigate fundamental interactions, and using modelling and numerical simulation as a tool to predict turbulent flame accelerating processes and decoupling or re-initiation of detonation waves in complex geometries of technical applications. Today, modelling and simulation show good agreement with a variety of fast combustion phenomena observed in experiments. Results of reactive computational fluid dynamics codes deliver inputs to reduce experimental parameters and provide the basis for an innovative design of arresters for deflagration and detonation processes. (author)

  14. Advanced Sine Wave Modulation of Continuous Wave Laser System for Atmospheric CO2 Differential Absorption Measurements

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.

    2014-01-01

    NASA Langley Research Center in collaboration with ITT Exelis have been experimenting with Continuous Wave (CW) laser absorption spectrometer (LAS) as a means of performing atmospheric CO2 column measurements from space to support the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission.Because range resolving Intensity Modulated (IM) CW lidar techniques presented here rely on matched filter correlations, autocorrelation properties without side lobes or other artifacts are highly desirable since the autocorrelation function is critical for the measurements of lidar return powers, laser path lengths, and CO2 column amounts. In this paper modulation techniques are investigated that improve autocorrelation properties. The modulation techniques investigated in this paper include sine waves modulated by maximum length (ML) sequences in various hardware configurations. A CW lidar system using sine waves modulated by ML pseudo random noise codes is described, which uses a time shifting approach to separate channels and make multiple, simultaneous online/offline differential absorption measurements. Unlike the pure ML sequence, this technique is useful in hardware that is band pass filtered as the IM sine wave carrier shifts the main power band. Both amplitude and Phase Shift Keying (PSK) modulated IM carriers are investigated that exibit perfect autocorrelation properties down to one cycle per code bit. In addition, a method is presented to bandwidth limit the ML sequence based on a Gaussian filter implemented in terms of Jacobi theta functions that does not seriously degrade the resolution or introduce side lobes as a means of reducing aliasing and IM carrier bandwidth.

  15. Theoretical investigations on the fragmentation of drops of melt with respect to the description of thermal detonations (vapor explosions) and their application in the code Frademo

    International Nuclear Information System (INIS)

    Burger, M.; Carachalios, C.; Kim, D.S.; Unger, H.

    1986-01-01

    Vapor explosions caused by the contact of molten core material with coolant are an important issue within reactor safety analysis, because they could produce an early threat to the containment during a core melt accident. The case of steady-state propagation of a detonation wave through a coarse premixture of melt and coolant represents the most severe case of a large scale vapor explosion under reactor conditions with the highest rate and largest heat release and therefore also the highest yield of mechanical energy. The present contribution starts with the description of the integral model of the detonation wave. The fragmentation processes, which are decisive for these exchange terms and the detonation process as a whole, are dealt with also. Hydrodynamic fragmentation processes as well as a thermally induced one are considered. The processes which take place inside a detonation wave, especially the fragmentation of the drops of melt and the velocity equilibration between the melt and the coolant, determine the behavior of the wave. In the present model these processes are described within a three-phase approach, considering the drops of melt, the fragments and the coolant as separate flow phases. In the frame of this work, the computer code FRADEMO has been developed. It consists of an overall description of the processes inside a steady-state detonation wave in combination with a full description of the detailed models on hydrodynamic and thermal fragmentation presented in this report. Some useful information for the potential code user is given in the appendix of the detailed report also

  16. Room temperature continuous wave operation of quantum cascade laser at λ ~ 9.4 μm

    Science.gov (United States)

    Hou, Chuncai; Zhao, Yue; Zhang, Jinchuan; Zhai, Shenqiang; Zhuo, Ning; Liu, Junqi; Wang, Lijun; Liu, Shuman; Liu, Fengqi; Wang, Zhanguo

    2018-03-01

    Continuous wave (CW) operation of long wave infrared (LWIR) quantum cascade lasers (QCLs) is achieved up to a temperature of 303 K. For room temperature CW operation, the wafer with 35 stages was processed into buried heterostructure lasers. For a 2-mm-long and 10-μm-wide laser with high-reflectivity (HR) coating on the rear facet, CW output power of 45 mW at 283 K and 9 mW at 303 K is obtained. The lasing wavelength is around 9.4 μm locating in the LWIR spectrum range. Project supported by the National Key Research And Development Program (No. 2016YFB0402303), the National Natural Science Foundation of China (Nos. 61435014, 61627822, 61574136, 61774146, 61674144, 61404131), the Key Projects of Chinese Academy of Sciences (Nos. ZDRW-XH-2016-4, QYZDJ-SSW-JSC027), and the Beijing Natural Science Foundation (No. 4162060, 4172060).

  17. Research on large-aperture primary mirror supporting way of vehicle-mounted laser communication system

    Science.gov (United States)

    Meng, Lixin; Meng, Lingchen; Zhang, Yiqun; Zhang, Lizhong; Liu, Ming; Li, Xiaoming

    2018-01-01

    In the satellite to earth laser communication link, large-aperture ground laser communication terminals usually are used in order to realize the requirement of high rate and long distance communication and restrain the power fluctuation by atmospheric scintillation. With the increasing of the laser communication terminal caliber, the primary mirror weight should also be increased, and selfweight, thermal deformation and environment will affect the surface accuracy of the primary mirror surface. A high precision vehicular laser communication telescope unit with an effective aperture of 600mm was considered in this paper. The primary mirror is positioned with center hole, which back is supported by 9 floats and the side is supported by a mercury band. The secondary mirror adopts a spherical adjusting mechanism. Through simulation analysis, the system wave difference is better than λ/20 when the primary mirror is in different dip angle, which meets the requirements of laser communication.

  18. Shock-to-detonation transition of RDX and NTO based composite high explosives: experiments and modeling

    Science.gov (United States)

    Baudin, Gerard; Roudot, Marie; Genetier, Marc

    2013-06-01

    Composite HMX and NTO based high explosives (HE) are widely used in ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside HE. Comparing to a pressed HE, a composite HE is not porous and the hot-spots are mainly located at the grain - binder interface leading to a different behavior during shock-to-detonation transition. An investigation of how shock-to-detonation transition occurs inside composite HE containing RDX and NTO is proposed in this lecture. Two composite HE have been studied. The first one is HMX - HTPB 82:18. The second one is HMX - NTO - HTPB 12:72:16. These HE have been submitted to plane sustained shock waves at different pressure levels using a laboratory powder gun. Pressure signals are measured using manganin gauges inserted at several distances inside HE. The corresponding run-distances to detonation are determined using wedge test experiments where the plate impact is performed using a powder gun. Both HE exhibit a single detonation buildup curve in the distance - time diagram of shock-to-detonation transition. This feature seems a common shock-to-detonation behavior for composite HE without porosity. This behavior is also confirmed for a RDX - HTPB 85:15 based composite HE. Such a behavior is exploited to determine the heterogeneous reaction rate versus the shock pressure using a method based on the Cauchy-Riemann problem inversion. The reaction rate laws obtained allow to compute both run-distance to detonation and pressure signals.

  19. Eccentric H2 detonation in a nuclear power plant steel containment

    International Nuclear Information System (INIS)

    Maresca, G.; Pino, G.

    1992-01-01

    At present, studies are in progress at ENEA-DISP to assess the performance of a steel containment under hydrogen detonation. Although considered unprobable to occur, this event is studied as a load on the safe side challenging the containment. A complete model to simulate the shock wave behavior and the fluid-structure interaction between the containment atmosphere and the containment wall has been set up at ENEA-DISP and a monodimensional axisymmetric case already studied. In the present paper the two-dimensional extension of the numerical model has been used. A plane slice of the wall and of the atmosphere filling the containment is considered. A cylindrical detonation wave is supposed to start from a source located eccentrically with respect to the containment axis. Because of the exploratory nature of the numerical model, a period of only 20 msec has been considered, although 100 msec should be considered as a minimum in a large metal containment to exclude further growing of plastic strains produced by consecutive reflections. At variance with the axisymmetric case bending stresses are developed now. The use of the model in order to assess a strain failure criterion to be applied at the dynamic portion of the H 2 detonation load is considered. In the paper the influence of different initial values of the relevant parameters (pressure, temperature, hydrogen concentration and source location) is examined in order to assess a range of equivalent conditions

  20. Relativistic reversal of the ponderomotive force in a standing laser wave

    International Nuclear Information System (INIS)

    Pokrovsky, A.L.; Kaplan, A.E.

    2005-01-01

    Effect of relativistic reversal of the ponderomotive force (PF), reported earlier for a collinear configuration of electron and laser standing wave [A. E. Kaplan and A. L. Pokrovsky, Phys. Rev. Lett., 95, 053601 (2005)], is studied here theoretically for various types of polarizations of the laser beam. We demonstrated that the collinear configuration, in which the laser wave is linearly polarized with electric field E-vector parallel to the initial electron momentum p-vector 0 , is the optimal configuration for the relativistic reversal. In that case, the transverse PF reverses its direction when the incident momentum is p 0 =mc. The reversal effect vanishes in the cases of circular and linear with E-vector perpendicular p-vector 0 polarizations. We have discovered, however, that the counter-rotating circularly polarized standing waves develop attraction and repulsion areas along the axis of laser, in the laser field whose intensity is homogeneous in that axis, i.e., has no field gradient

  1. In situ measurement of plasma and shock wave properties inside laser-drilled metal holes

    Science.gov (United States)

    Brajdic, Mihael; Hermans, Martin; Horn, Alexander; Kelbassa, Ingomar

    2008-10-01

    High-speed imaging of shock wave and plasma dynamics is a commonly used diagnostic method for monitoring processes during laser material treatment. It is used for processes such as laser ablation, cutting, keyhole welding and drilling. Diagnosis of laser drilling is typically adopted above the material surface because lateral process monitoring with optical diagnostic methods inside the laser-drilled hole is not possible due to the hole walls. A novel method is presented to investigate plasma and shock wave properties during the laser drilling inside a confined environment such as a laser-drilled hole. With a novel sample preparation and the use of high-speed imaging combined with spectroscopy, a time and spatial resolved monitoring of plasma and shock wave dynamics is realized. Optical emission of plasma and shock waves during drilling of stainless steel with ns-pulsed laser radiation is monitored and analysed. Spatial distributions and velocities of shock waves and of plasma are determined inside the holes. Spectroscopy is accomplished during the expansion of the plasma inside the drilled hole allowing for the determination of electron densities.

  2. Applications of nanosecond, kilojoule lasers to the basic physics of waves in plasmas

    International Nuclear Information System (INIS)

    Drake, R.P.

    1992-01-01

    Plasmas can sustain many normal modes of oscillation (waves), including both electromagnetic and electrostatic modes. These waves can interact by a wide variety of linear and nonlinear mechanisms, including mode coupling, mixing, and instabilities. Furthermore, such mechanisms compete, so that a given wave might be absorbed, might mode convert, or might decay by one of several instabilities, depending upon the specific circumstances in which it is produced. Moreover, such waves are important in many applications, including for example laser fusion, x-ray lasers, plasma accelerators, and ionospheric heating. Laser-produced plasmas can provide an effective medium for the studies of such waves and the related mechanisms. New opportunities will be made possible by the advent of comparatively inexpensive nanosecond, kilojoule lasers. One can now contemplate affordable experiments, not limited by programmatic constraints, that could study such the basic physics of the waves in such plasmas with unprecedented precision and in unprecedented detail

  3. Unlimited electron acceleration in laser-driven plasma waves

    International Nuclear Information System (INIS)

    Katsouleas, T.; Dawson, J.M.

    1983-01-01

    It is shown that the limitation to the energy gain of 2(ω/ω/sub p/) 2 mc 2 of an electron in the laser-plasma beat-wave accelerator can be overcome by imposing a magnetic field of appropriate strength perpendicular to the plasma wave. This accelerates particles parallel to the phase fronts of the accelerating wave which keeps them in phase with it. Arbitrarily large energy is theoretically possible

  4. The role of multidimensional instabilities in direct initiation of gaseous detonations in free space

    KAUST Repository

    Shen, Hua; Parsani, Matteo

    2017-01-01

    We numerically investigate the direct initiation of detonations driven by the propagation of a blast wave into a unconfined gaseous combustible mixture to study the role played by multidimensional instabilities in direct initiation of stable

  5. Proceedings of the International Symposium on Detonation (8th) Held in Albuquerque, New Mexico on 15-19 Jul 1985

    Science.gov (United States)

    1985-07-19

    AT, H2 dependency of the H2 and 002 concentrations increases and CO2 decreases, see Tables 4, 5, in conjunction with a rising Al content, starting 12...A.W. Gibb DETONATION PROPERTIES OF LIQUID NITRIC OXIDE ...................... 422 W.C. Davis, W.C. Chiles CHARACTERIZATION OF STRONG DETONATION WAVES...Elban, F. Santiago PARAMAGNETIC DECOMPOSITION PRODUCTS FROM ENERGETIC M A T E R IA L S

  6. MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS

    Directory of Open Access Journals (Sweden)

    Mario Dobrilović

    2005-12-01

    Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.

  7. 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.

  8. Detonability of H2-air-diluent mixtures

    International Nuclear Information System (INIS)

    Tieszen, S.R.; Sherman, M.P.; Benedick, W.B.; Berman, M.

    1987-06-01

    This report describes the Heated Detonation Tube (HDT). Detonation cell width and velocity results are presented for H 2 -air mixtures, undiluted and diluted with CO 2 and H 2 O for a range of H 2 concentration, initial temperature and pressure. The results show that the addition of either CO 2 or H 2 O significantly increases the detonation cell width and hence reduces the detonability of the mixture. The results also show that the detonation cell width is reduced (detonability is increased) for increased initial temperature and/or pressure

  9. Laser-driven shock-wave propagation in pure and layered targets

    International Nuclear Information System (INIS)

    Salzmann, D.; Eliezer, S.; Krumbein, A.D.; Gitter, L.

    1983-01-01

    The propagation properties of laser-driven shock waves in pure and layered polyethylene and aluminum slab targets are studied for a set of laser intensities and pulse widths. The laser-plasma simulations were carried out by means of our one-dimensional Lagrangian hydrodynamic code. It is shown that the various parts of a laser-driven compression wave undergo different thermodynamic trajectories: The shock front portion is on the Hugoniot curve whereas the rear part is closer to an adiabat. It is found that the shock front is accelerated into the cold material till troughly-equal0.8tau (where tau is the laser pulse width) and only later is a constant velocity propagation attained. The scaling laws obtained for the pressure and temperature of the compression wave in pure targets are in good agreement with those published in other works. In layered targets, high compression and pressure were found to occur at the interface of CH 2 on Al targets due to impedance mismatch but were not found when the layers were reversed. The persistence time of the high pressure on the interface in the CH 2 on Al case is long enough relative to the characteristic times of the plasma to have an appreciable influence on the shock-wave propagation into the aluminum layer. This high pressure and compression on the interface can be optimized by adjusting the CH 2 layer thickness

  10. Exergetic efficiency analysis of hydrogen–air detonation in pulse detonation combustor using computational fluid dynamics

    Directory of Open Access Journals (Sweden)

    Pinku Debnath

    2017-03-01

    Full Text Available Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital role in the analysis of the exergetic efficiency of combustion process. Detonation is thermodynamically more efficient than deflagration mode of combustion. Detonation combustion technology inside the pulse detonation engine using hydrogen as a fuel is energetic propulsion system for next generation. In this study, the main objective of this work is to quantify the exergetic efficiency of hydrogen–air combustion for deflagration and detonation combustion process. Further detonation parameters are calculated using 0.25, 0.35, and 0.55 of H2 mass concentrations in the combustion process. The simulations have been performed for converging the solution using commercial computational fluid dynamics package Ansys Fluent solver. The details of combustion physics in chemical reacting flows of hydrogen–air mixture in two control volumes were simulated using species transport model with eddy dissipation turbulence chemistry interaction. From these simulations it was observed that exergy loss in the deflagration combustion process is higher in comparison to the detonation combustion process. The major observation was that pilot fuel economy for the two combustion processes and augmentation of exergetic efficiencies are better in the detonation combustion process. The maximum exergetic efficiency of 55.12%, 53.19%, and 23.43% from deflagration combustion process and from detonation combustion process, 67.55%, 57.49%, and 24.89%, are obtained from aforesaid H2 mass fraction. It was also found that for lesser fuel mass fraction higher exergetic efficiency was observed.

  11. Ion temperature via laser scattering on ion Bernstein waves

    International Nuclear Information System (INIS)

    Wurden, G.A.; Ono, M.; Wong, K.L.

    1981-10-01

    Hydrogen ion temperature has been measured in a warm toroidal plasma with externally launched ion Bernstein waves detected by heterodyne CO 2 laser scattering. Radial scanning of the laser beam allows precise determination of k/sub perpendicular to/ for the finite ion Larmor radius wave (ω approx. less than or equal to 2Ω/sub i/). Knowledge of the magnetic field strength and ion concentration then give a radially resolved ion temperature from the dispersion relation. Probe measurements and Doppler broadening of ArII 4806A give excellent agreement

  12. Research of the elastic waves generated by a pulse laser. Excitation mechanism of elastic waves and application to nondestructive testing; Pulse laser de reikishita danseiha ni kansuru kenkyu. Danseiha reiki no mechanism to hihakai kensa eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H.; Takemoto, M. [Aoyama Gakuin University, Tokyo (Japan). College of Science and Engineering

    1994-07-20

    A bulk wave is generated when a pulse laser is irradiated to the material, and the characteristics of a Young`s modulus and Poisson`s ratio can be nondestructively estimated from the bulk wave. The generation mechanism of laser ultrasonic waves must be first clarified for such application. In this paper, fundamental research was conducted to study the generation mechanism of the elastic waves excited by a Q-switched Nd-YAG laser, and the generation method and characteristics of Rayleigh waves. The following result was obtained. A bulk wave is generated by the disk-like adiabatic expansion near the surface if the laser power is small when a spot-shape pulse laser was irradiated. A bulk wave is generated by the thin disk-like adiabatic expansion beneath the surface due to the thermal diffusion in the depth direction of a base material when the laser power becomes large. Moreover, a bulk wave is generated by the impact force due to abrasion and plasma when the power becomes still larger. The information on the bulk wave characteristics and Rayleigh wave was also obtained. 25 refs., 15 figs., 1 tab.

  13. Ignition-and-Growth Modeling of NASA Standard Detonator and a Linear Shaped Charge

    Science.gov (United States)

    Oguz, Sirri

    2010-01-01

    The main objective of this study is to quantitatively investigate the ignition and shock sensitivity of NASA Standard Detonator (NSD) and the shock wave propagation of a linear shaped charge (LSC) after being shocked by NSD flyer plate. This combined explosive train was modeled as a coupled Arbitrary Lagrangian-Eulerian (ALE) model with LS-DYNA hydro code. An ignition-and-growth (I&G) reactive model based on unreacted and reacted Jones-Wilkins-Lee (JWL) equations of state was used to simulate the shock initiation. Various NSD-to-LSC stand-off distances were analyzed to calculate the shock initiation (or failure to initiate) and detonation wave propagation along the shaped charge. Simulation results were verified by experimental data which included VISAR tests for NSD flyer plate velocity measurement and an aluminum target severance test for LSC performance verification. Parameters used for the analysis were obtained from various published data or by using CHEETAH thermo-chemical code.

  14. Effect of laser beam filamentation on plasma wave localization and stimulated Raman scattering

    International Nuclear Information System (INIS)

    Purohit, Gunjan; Sharma, R. P.

    2013-01-01

    This paper presents the effect of laser beam filamentation on the localization of electron plasma wave (EPW) and stimulated Raman scattering (SRS) in unmagnitized plasma when both relativistic and ponderomotive nonlinearities are operative. The filamentary dynamics of laser beam is studied and the splitted profile of the laser beam is obtained due to uneven focusing of the off-axial rays. The localization of electron plasma wave takes place due to nonlinear coupling between the laser beam and EPW. Stimulated Raman scattering of this EPW is studied and backreflectivity has been calculated. The localization of EPW also affects the eigenfrequency and damping of plasma wave; consequently, mismatch and modified enhanced Landau damping lead to the disruption of SRS process and a substantial reduction in the backreflectivity. The new enhanced damping of the plasma wave has been calculated and it is found that the SRS process gets suppressed due to the localization of plasma wave in laser beam filamentary structures. For typical laser beam and plasma parameters with wavelength λ (=1064 nm), power flux (=10 16 W/cm 2 ) and plasma density (n/n cr ) = 0.2; the SRS back reflectivity is found to be suppressed by a factor of around 5%. (author)

  15. Shock wave generation in laser ablation studied using pulsed digital holographic interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Amer, Eynas; Gren, Per; Sjoedahl, Mikael [Division of Experimental Mechanics, Luleaa University of Technology, SE-971 87 Luleaa (Sweden)], E-mail: eynas.amer@ltu.se, E-mail: per.gren@ltu.se, E-mail: mikael.sjodahl@ltu.se

    2008-11-07

    Pulsed digital holographic interferometry has been used to study the shock wave induced by a Q-switched Nd-YAG laser ({lambda} = 1064 nm and pulse duration 12 ns) on a polycrystalline boron nitride (PCBN) ceramic target under atmospheric air pressure. A special setup based on using two synchronized wavelengths from the same laser for processing and measurement simultaneously has been introduced. Collimated laser light ({lambda} = 532 nm) passed through the volume along the target and digital holograms were recorded for different time delays after processing starts. Numerical data of the integrated refractive index field were calculated and presented as phase maps showing the propagation of the shock wave generated by the process. The location of the induced shock wave front was observed for different focusing and time delays. The amount of released energy, i.e. the part of the incident energy of the laser pulse that is eventually converted to a shock wave has been estimated using the point explosion model. The released energy is normalized by the incident laser pulse energy and the energy conversion efficiency between the laser pulse and PCBN target has been calculated at different power densities. The results show that the energy conversion efficiency seems to be constant around 80% at high power densities.

  16. Shock wave science and technology reference library

    CERN Document Server

    2009-01-01

    This book is the second of several volumes on solids in the Shock Wave Science and Technology Reference Library. These volumes are primarily concerned with high-pressure shock waves in solid media, including detonation and high-velocity impact and penetration events. Of the four extensive chapters in this volume, the first two describe the reactive behavior of condensed phase explosives, - Condensed-Phase Explosives: Shock Initiation and Detonation Phenomena (SA Sheffield and R Engelke) - First Principles Molecular Simulations of Energetic Materials at High-Pressures (F Zhang, S Alavi, and TK Woo), and the remaining two discuss the inert, mechanical response of solid materials. - Combined Compression and Shear Plane Waves (ZP Tang and JB Aidun), and - Dynamic Fragmentation of Solids (D Grady). All chapters are each self-contained, and can be read independently of each other. They offer a timely reference, for beginners as well as professional scientists and engineers, on the foundations of detonation phenomen...

  17. Quantitative analysis for the determination of aluminum percentage and detonation performance of aluminized plastic bonded explosives by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rezaei, A. H.; Keshavarz, M. H.; Kavosh Tehrani, M.; Darbani, S. M. R.

    2018-06-01

    The aluminized plastic-bonded explosive (PBX) is a composite material in which solid explosive particles are dispersed in a polymer matrix, which includes three major components, i.e. polymeric binder, metal fuel (aluminum) and nitramine explosive. This work introduces a new method on the basis of the laser-induced breakdown spectroscopy (LIBS) technique in air and argon atmospheres to investigate the determination of aluminum content and detonation performance of aluminized PBXs. Plasma emissions of aluminized PBXs are recorded where atomic lines of Al, C and H as well as molecular bands of AlO and CN are identified. The experimental results demonstrate that a good discrimination and separation between the aluminized PBXs is possible using LIBS and principle component analysis, although they have similar atomic composition. Relative intensity of the AlO/Al is used to determine aluminum percentage of the aluminized PBXs. The obtained quantitative calibration curve using the relative intensity of the AlO/Al is better than the resulting calibration curve using only the intensity of Al. By using the LIBS method and the measured intensity ratio of CN/C, an Al content of 15% is found to be the optimum value in terms of velocity of detonation of the RDX/Al/HTPB standard samples.

  18. Controlling of the electromagnetic solitary waves generation in the wake of a two-color laser

    Science.gov (United States)

    Pan, K. Q.; Li, S. W.; Guo, L.; Yang, D.; Li, Z. C.; Zheng, C. Y.; Jiang, S. E.; Zhang, B. H.; He, X. T.

    2018-05-01

    Electromagnetic solitary waves generated by a two-color laser interaction with an underdense plasma are investigated. It is shown that, when the former wave packet of the two-color laser is intense enough, it will excite nonlinear wakefields and generate electron density cavities. The latter wave packets will beat with the nonlinear wakefield and generate both high-frequency and low-frequency components. When the peak density of the cavities exceeds the critical density of the low-frequency component, this part of the electromagnetic field will be trapped to generate electromagnetic solitary waves. By changing the laser and plasma parameters, we can control the wakefield generation, which will also control the generation of the solitary waves. One-dimensional particle-in-cell simulations are performed to prove the controlling of the solitary waves. The simulation results also show that solitary waves generated by higher laser intensities will become moving solitary waves. The two-dimensional particle-in-cell also shows the generation of the solitary waves. In the two-dimensional case, solitary waves are distributed in the transverse directions because of the filamentation instability.

  19. Experimental study of a laser-heated solenoid

    International Nuclear Information System (INIS)

    Rutkowski, H.L.

    1975-01-01

    An experimental investigation was made of the interaction of an intense CO 2 laser beam with a column of initially uv-ionized hydrogen immersed in a steady magnetic field of up to 100 kG. Under the intense laser radiation, the gas becomes ionized and heated to temperatures as high as 150 eV (1.6 x 10 6 0 K). The primary purpose of the investigation was to determine the properties of the dense, hot plasma formed in this manner. Time and space resolved measurements of the plasma electron density were made using holographic interferometry along the axis and Mach--Zehnder interferometry across the column. The temperature was determined by measuring the decay rate of a line from CV in the quartz uv. These measurements were supplemented by streak photography to provide data on the development of the luminosity of the plasma column, radially and axially, as a function of time. From these various diagnostic techniques, it was possible to determine that a density minimum is formed on-axis within a few tens of nanoseconds after initiation of the laser pulse. This effectively produces a light pipe which traps the beam, and suggests that long columns can be formed by laser irradiation. The beam energy was efficiently absorbed and plasma loss rates appeared to be those expected from classical MHD modelling. While a completely unambiguous answer as to the mode of laser discharge propagation occurring in the experiment was not obtained, the bulk of the evidence suggests a ''bleaching wave'' rather than a laser driven detonator. In summary, the experiment was successful in demonstrating the creation of dense, slender columns by laser breakdown, in support of the ''laser-heated solenoid'' fusion concept

  20. Gravitational wave detection using laser interferometry beyond the standard quantum limit

    Science.gov (United States)

    Heurs, M.

    2018-05-01

    Interferometric gravitational wave detectors (such as advanced LIGO) employ high-power solid-state lasers to maximize their detection sensitivity and hence their reach into the universe. These sophisticated light sources are ultra-stabilized with regard to output power, emission frequency and beam geometry; this is crucial to obtain low detector noise. However, even when all laser noise is reduced as far as technically possible, unavoidable quantum noise of the laser still remains. This is a consequence of the Heisenberg Uncertainty Principle, the basis of quantum mechanics: in this case, it is fundamentally impossible to simultaneously reduce both the phase noise and the amplitude noise of a laser to arbitrarily low levels. This fact manifests in the detector noise budget as two distinct noise sources-photon shot noise and quantum radiation pressure noise-which together form a lower boundary for current-day gravitational wave detector sensitivities, the standard quantum limit of interferometry. To overcome this limit, various techniques are being proposed, among them different uses of non-classical light and alternative interferometer topologies. This article explains how quantum noise enters and manifests in an interferometric gravitational wave detector, and gives an overview of some of the schemes proposed to overcome this seemingly fundamental limitation, all aimed at the goal of higher gravitational wave event detection rates. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

  1. Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

    Science.gov (United States)

    Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

    2015-05-01

    194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

  2. Particle-in-cell studies of laser-driven hot spots and a statistical model for mesoscopic properties of Raman backscatter

    International Nuclear Information System (INIS)

    Albright, B.J.; Yin, L.; Bowers, K.J.; Kline, J.L.; Montgomery, D.S.; Fernandez, J.C.; Daughton, W.

    2006-01-01

    The authors use explicit particle-in-cell simulations to model stimulated scattering processes in media with both solitary and multiple laser hot spots. These simulations indicate coupling among hot spots, whereby scattered light, plasma waves, and hot electrons generated in one laser hot spot may propagate to neighboring hot spots, which can be destabilized to enhanced backscatter. A nonlinear statistical model of a stochastic beam exhibiting this coupled behavior is described here. Calibration of the model using particle-in-cell simulations is performed, and a threshold is derived for 'detonation' of the beam to high reflectivity. (authors)

  3. Stability of cosmological detonation fronts

    Science.gov (United States)

    Mégevand, Ariel; Membiela, Federico Agustín

    2014-05-01

    The steady-state propagation of a phase-transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very close to the Jouguet point, where our approach breaks down.

  4. Ripplon laser through stimulated emission mediated by water waves

    Science.gov (United States)

    Kaminski, Samuel; Martin, Leopoldo L.; Maayani, Shai; Carmon, Tal

    2016-12-01

    Lasers rely on stimulated electronic transition, a quantum phenomenon in the form of population inversion. In contrast, phonon masers depend on stimulated Raman scattering and are entirely classical. Here we extend Raman lasers to rely on capillary waves, which are unique to the liquid phase of matter and relate to the attraction between intimate fluid particles. We fabricate resonators that co-host capillary and optical modes, control them to operate at their non-resolved sideband and observe stimulated capillary scattering and the coherent excitation of capillary resonances at kilohertz rates (which can be heard in audio files recorded by us). By exchanging energy between electromagnetic and capillary waves, we bridge the interfacial tension phenomena at the liquid phase boundary to optics. This approach may impact optofluidics by allowing optical control, interrogation and cooling of water waves.

  5. Attosecond Electron Wave Packet Dynamics in Strong Laser Fields

    International Nuclear Information System (INIS)

    Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier, A.; Lopez-Martens, R.; Valentin, C.; Balcou, Ph.; Kazamias, S.; Mauritsson, J.; Gaarde, M. B.; Schafer, K. J.; Mairesse, Y.; Wabnitz, H.; Salieres, P.

    2005-01-01

    We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (∼20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes

  6. Time variation in the reaction-zone structure of two-phase spray detonations.

    Science.gov (United States)

    Pierce, T. H.; Nicholls, J. A.

    1973-01-01

    A detailed theoretical analysis of the time-varying detonation structure in a monodisperse spray is presented. The theory identifies experimentally observed reaction-zone overpressures as deriving from blast waves formed therein by the explosive ignition of the spray droplets, and follows in time the motion, change in strength, and interactions of these blast waves with one another, and with the leading shock. The results are compared with experimental data by modeling the motion of a finite-size circular pressure transducer through the theoretical data field in an x-t space.

  7. Generation of ultrasound in materials using continuous-wave lasers.

    Science.gov (United States)

    Caron, James N; DiComo, Gregory P; Nikitin, Sergei

    2012-03-01

    Generating and detecting ultrasound is a standard method of nondestructive evaluation of materials. Pulsed lasers are used to generate ultrasound remotely in situations that prohibit the use of contact transducers. The scanning rate is limited by the repetition rates of the pulsed lasers, ranging between 10 and 100 Hz for lasers with sufficient pulse widths and energies. Alternately, a high-power continuous-wave laser can be scanned across the surface, creating an ultrasonic wavefront. Since generation is continuous, the scanning rate can be as much as 4 orders of magnitude higher than with pulsed lasers. This paper introduces the concept, comparing the theoretical scanning speed with generation by pulsed laser. © 2012 Optical Society of America

  8. Blast effects physical properties of shock waves

    CERN Document Server

    2018-01-01

    This book compiles a variety of experimental data on blast waves. The book begins with an introductory chapter and proceeds to the topic of blast wave phenomenology, with a discussion Rankine-Hugoniot equations and the Friedlander equation, used to describe the pressure-time history of a blast wave. Additional topics include arrival time measurement, the initiation of detonation by exploding wires, a discussion of TNT equivalency, and small scale experiments. Gaseous and high explosive detonations are covered as well. The topics and experiments covered were chosen based on the comparison of used scale sizes, from small to large. Each characteristic parameter of blast waves is analyzed and expressed versus scaled distance in terms of energy and mass. Finally, the appendix compiles a number of polynomial laws that will prove indispensable for engineers and researchers.

  9. Induction of subterahertz surface waves on a metal wire by intense laser interaction with a foil

    Science.gov (United States)

    Teramoto, Kensuke; Inoue, Shunsuke; Tokita, Shigeki; Yasuhara, Ryo; Nakamiya, Yoshihide; Nagashima, Takeshi; Mori, Kazuaki; Hashida, Masaki; Sakabe, Shuji

    2018-02-01

    We have demonstrated that a pulsed electromagnetic wave (Sommerfeld wave) of subterahertz frequency and 11-MV/m field strength can be induced on a metal wire by the interaction of an intense femtosecond laser pule with an adjacent metal foil at a laser intensity of 8.5 × 1018W /c m2 . The polarity of the electric field of this surface wave is opposite to that obtained by the direct interaction of the laser with the wire. Numerical simulations suggest that an electromagnetic wave associated with electron emission from the foil induces the surface wave. A tungsten wire is placed normal to an aluminum foil with a gap so that the wire is not irradiated and damaged by the laser pulse, thus making it possible to generate surface waves on the wire repeatedly.

  10. Excimer laser irradiation of metal surfaces

    Science.gov (United States)

    Kinsman, Grant

    In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

  11. Novel uses of detonator diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, John R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wilde, Zakary Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tasker, Douglas George [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Francois, Elizabeth Green [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nakamoto, Teagan Kanakanui Junichi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Dalton Kay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trujillo, Christopher J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-15

    A novel combination of diagnostics is being used to research the physics of detonator initiation. The explosive PETN (Pentaerythritol tetranitrate) commonly used in detonators, is also a piezo-electric material that, when sufficiently shocked, emits an electromagnetic field in the radio frequency (RF) range, along crystal fracture planes. In an effort to capture this RF signal, a new diagnostic was created. A copper foil, used as an RF antenna, was wrapped around a foam fixture encompassing a PETN pellet. Rogowski coils were used to obtain the change in current with respect to time (di/dt) the detonator circuit, in and polyvinylidene difluoride (PVDF) stress sensors were used to capture shockwave arrival time. The goal of these experiments is to use these diagnostics to study the reaction response of a PETN pellet of known particle size to shock loading with various diagnostics including an antenna to capture RF emissions. Our hypothesis is that RF feedback may signify the rate of deflagration to detonation transition (DDT) or lack thereof. The new diagnostics and methods will be used to determine the timing of start of current, bridge burst, detonator breakout timing and RF generated from detonation. These data will be compared to those of currently used diagnostics in order to validate the accuracy of these new methods. Future experiments will incorporate other methods of validation including dynamic radiography, optical initiation and use of magnetic field sensors.

  12. Contribution to the beam plasma material interactions during material processing with TEA CO2 laser radiation

    Science.gov (United States)

    Jaschek, Rainer; Konrad, Peter E.; Mayerhofer, Roland; Bergmann, Hans W.; Bickel, Peter G.; Kowalewicz, Roland; Kuttenberger, Alfred; Christiansen, Jens

    1995-03-01

    The TEA-CO2-laser (transversely excited atmospheric pressure) is a tool for the pulsed processing of materials with peak power densities up to 1010 W/cm2 and a FWHM of 70 ns. The interaction between the laser beam, the surface of the work piece and the surrounding atmosphere as well as gas pressure and the formation of an induced plasma influences the response of the target. It was found that depending on the power density and the atmosphere the response can take two forms. (1) No target modification due to optical break through of the atmosphere and therefore shielding of the target (air pressure above 10 mbar, depending on the material). (2) Processing of materials (air pressure below 10 mbar, depending on the material) with melting of metallic surfaces (power density above 0.5 109 W/cm2), hole formation (power density of 5 109 W/cm2) and shock hardening (power density of 3.5 1010 W/cm2). All those phenomena are usually linked with the occurrence of laser supported combustion waves and laser supported detonation waves, respectively for which the mechanism is still not completely understood. The present paper shows how short time photography and spatial and temporal resolved spectroscopy can be used to better understand the various processes that occur during laser beam interaction. The spectra of titanium and aluminum are observed and correlated with the modification of the target. If the power density is high enough and the gas pressure above a material and gas composition specific threshold, the plasma radiation shows only spectral lines of the background atmosphere. If the gas pressure is below this threshold, a modification of the target surface (melting, evaporation and solid state transformation) with TEA-CO2- laser pulses is possible and the material specific spectra is observed. In some cases spatial and temporal resolved spectroscopy of a plasma allows the calculation of electron temperatures by comparison of two spectral lines.

  13. A study on laser-based ultrasonic technique by the use of guided wave tomographic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junpil, E-mail: jpp@pusan.ac.kr; Lim, Juyoung, E-mail: jpp@pusan.ac.kr [Graduate school, School of Mechanical Engineering, Pusan National University (Korea, Republic of); Cho, Younho [School of Mechanical Engineering, Pusan National University (Korea, Republic of); Krishnaswamy, Sridhar [Center for Quality Engineering and Failure Prevention, Northwestern University, Evanston, IL (United States)

    2015-03-31

    Guided wave tests are impractical for investigating specimens with limited accessibility and coarse surfaces or geometrically complicated features. A non-contact setup with a laser ultrasonic transmitter and receiver is the classic attractive for guided wave inspection. The present work was done to develop a non-contact guided-wave tomography technique by laser ultrasonic technique in a plate-like structure. A method for Lam wave generation and detection in an aluminum plate with a pulse laser ultrasonic transmitter and a Michelson interferometer receiver has been developed. In the images obtained by laser scanning, the defect shape and area showed good agreement with the actual defect. The proposed approach can be used as a non-contact-based online inspection and monitoring technique.

  14. High-order harmonics from bow wave caustics driven by a high-intensity laser

    International Nuclear Information System (INIS)

    Pirozhkov, A.S.; Kando, M.; Esirkepov, T.Zh.

    2012-01-01

    We propose a new mechanism of high-order harmonic generation during an interaction of a high-intensity laser pulse with underdense plasma. A tightly focused laser pulse creates a cavity in plasma pushing electrons aside and exciting the wake wave and the bow wave. At the joint of the cavity wall and the bow wave boundary, an annular spike of electron density is formed. This spike surrounds the cavity and moves together with the laser pulse. Collective motion of electrons in the spike driven by the laser field generates high-order harmonics. A strong localization of the electron spike, its robustness to oscillations imposed by the laser field and, consequently, its ability to produce high-order harmonics is explained by catastrophe theory. The proposed mechanism explains the experimental observations of high-order harmonics with the 9 TW J-KAREN laser (JAEA, Japan) and the 120 TW Astra Gemini laser (CLF RAL, UK) [A. S. Pirozhkov, et al., arXiv:1004.4514 (2010); A. S. Pirozhkov et al, AIP Proceedings, this volume]. The theory is corroborated by high-resolution two-and three-dimensional particle-in-cell simulations.

  15. Harmonic emission due to the nonlinear coupling of a Gaussian laser and a plasma wave

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, R; Jain, R K [Department of Mathematics, SSL Jain College, Vidisha, MP, 464001 (India); Parashar, J [Department of Physics, Samrat Ashok Technological Institute, Vidisha, MP, 464001 (India)

    2010-04-15

    A high-power Gaussian laser propagating through a plasma couples with a large-amplitude plasma wave and undergoes scattering to produce harmonics. The process is sensitive to the phase matching angle between the laser and plasma wave numbers and the plasma wave frequency. For larger harmonics, the phase matching angle is high. The efficiency of the process is comparatively high at higher plasma wave frequencies.

  16. Broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity

    Science.gov (United States)

    Li, Q.; Jia, Z. X.; Weng, H. Z.; Li, Z. R.; Yang, Y. D.; Xiao, J. L.; Chen, S. W.; Huang, Y. Z.; Qin, W. P.; Qin, G. S.

    2018-05-01

    We demonstrate broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm and a frequency separation of ~9.28 GHz generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity. By using one continuous-wave laser as the pump source, multi-wavelength Brillouin lasers with an operating wavelength range of 1554–1574 nm were generated via cascaded Brillouin scattering and four-wave mixing. Interestingly, when pumped by two continuous-wave lasers with an appropriate frequency separation, the operating wavelength range of the multi-wavelength Brillouin lasers was increased to 1500–1600 nm due to cavity-enhanced cascaded four-wave mixing among the frequency components generated by two pump lasers in the dual wavelength Brillouin laser cavity.

  17. Sub-wavelength patterning of organic monolayers via nonlinear processing with continuous-wave lasers

    Energy Technology Data Exchange (ETDEWEB)

    Mathieu, Mareike; Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Fakultaet fuer Chemie, Universitaet Duisburg-Essen, 45117 Essen (Germany); CeNIDE-Center for Nanointegration Duisburg-Essen, 47048 Duisburg (Germany); NETZ-NanoEnergieTechnikZentrum, 47048 Duisburg (Germany)

    2010-12-15

    In recent years, nonlinear processing with continuous-wave lasers has been demonstrated to be a facile means of rapid nanopatterning of organic monolayers down to the sub-100 nm range. In this study, we report on laser patterning of thiol-based organic monolayers with sub-wavelength resolution. Au-coated silicon substrates are functionalized with 1-hexadecanethiol. Irradiation with a focused beam of an Ar{sup +} laser operating at {lambda}=514 nm allows one to locally remove the monolayer. Subsequently, the patterns are transferred into the Au film via selective etching in a ferri-/ferrocyanide solution. Despite a 1/e{sup 2} spot diameter of about 2.8 {mu}m, structures with lateral dimensions down to 250 nm are fabricated. The underlying nonlinear dependence of the patterning process on laser intensity is traced back to the interplay between the laser-induced transient local temperature rise and the thermally activated desorption of the thiol molecules. A simple thermokinetic analysis of the data allows us to determine the effective kinetic parameters. These results complement our previous work on photothermal laser patterning of ultrathin organic coatings, such as silane-based organic monolayers, organo/silicon interfaces and supported membranes. A general introduction to nonlinear laser processing of organic monolayers is presented.

  18. Detonation Jet Engine. Part 1--Thermodynamic Cycle

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. The efficiency advantages of thermodynamic detonative combustion cycle over Humphrey combustion cycle at constant volume and Brayton combustion cycle at constant pressure were demonstrated. An ideal Ficket-Jacobs detonation cycle, and…

  19. Parametric Excitations of Fast Plasma Waves by Counter-propagating Laser Beams

    International Nuclear Information System (INIS)

    Shvets, G.; Fisch, N.J.

    2001-01-01

    Short- and long-wavelength plasma waves can become strongly coupled in the presence of two counter-propagating laser pump pulses detuned by twice the cold plasma frequency. What makes this four-wave interaction important is that the growth rate of the plasma waves occurs much faster than in the more obvious co-propagating geometry

  20. Study on the detonation properties of explosives in bore hole and precise controlled blasting; Happa konai no bakuyaku no bakugosei to seimitsu seigyo happa ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-08

    In order to perform efficient and safe controlled blasting, attaining sufficient detonation from explosive is important. Therefore, a mechanism of detonation in a bore hole was studied. Two detonation phenomenon measuring methods were established: one is a continuous detonation speed measuring method by using a resistance wire probe, and another is a detonation mark observing and evaluating method using aluminum and metallic lead plates. Assuming delay blastings in multiple bore holes used practically, discussions were given on detonation phenomena of explosives under pressurized condition. Under dynamic pressure condition, size of the pressurization and delay time of the detonations affected largely the detonation. Discussions were given on blasting effect and safety according to difference in forward initiation and reverse initiation. The reverse initiation method was verified to have excellent blasting effect, maintain good face conditions, and assure safety against inflammable gases. A precision initiation method was developed, which can control the initiation time of a detonator more precisely. The initiation accuracy is more than 1000 times greater than the ordinary instantaneously detonating electric detonator. The precision control of the initiation time proved to develop greater crack propagation. Vibration and stone scattering were also controlled. This paper also describes application of the method to a rock elastic wave exploration technique. 136 refs., 99 figs., 13 tabs.

  1. Continuous-wave ceramic Nd:YAG laser at 1123 nm

    International Nuclear Information System (INIS)

    Zhang, S S; Wang, Q P; Zhang, X Y; Cong, Z H; Fan, S Z; Liu, Z J; Sun, W J

    2009-01-01

    Ceramic Nd:YAG (cNd:YAG) materials are employed to generate 1123-nm laser. A fiber-coupled continuous-wave (CW) 808-nm diode laser is used as the pumping source. With an incident diode power of 26.1 W, a CW output power of up to 10.8 W is obtained with a 10-mm-long ceramic Nd:YAG rod (1.0 at.%-Nd-doped). The conversion efficiency from diode power to 1123-nm laser power is 41.4%. The laser performance of another 10-mm-long cNd:YAG rod with a Nd-doping concentration of 0.6 at.% is studied as a comparison

  2. Computer Modeling of a Rotating Detonation Engine in a Rocket Configuration

    Science.gov (United States)

    2015-03-01

    detonation engine ( RDE ) has one or more shock waves rotating around an annulus. The RDE can theoretically be 20% more thermally efficient than a traditional...deflagration- based cycle. An RDE was modeled in Numerical Propulsion System Simulation (NPSS) based on a model developed in Microsoft Excel. The...thermodynamic analysis of the RDE in these models is broken into four streams. Empirical models were used to find the per- centage of the total flow in each

  3. Meteorological requirements and operational fallout prediction techniques for Plowshare nuclear detonations

    International Nuclear Information System (INIS)

    Mueller, H.F.

    1969-01-01

    Meteorological support requirements for Plowshare nuclear detonations are shown to depend on a number of factors. The importance of adequate support to the effective planning and safe conduct of a nuclear detonation is described. An example of the influence of atmospheric conditions on radioactive cloud development and local transport and fallout of radioactive debris is presented. Prediction of the future state of atmospheric wind structure, required for fallout predictions depends on an adequate definition of its initial state and its rate of change. This definition, in turn, is shown to depend on an upper wind-sounding network of appropriate station density. An operational technique currently used for nuclear cratering fallout predictions is described and shown to produce results of useful accuracy. (author)

  4. Meteorological requirements and operational fallout prediction techniques for Plowshare nuclear detonations

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, H F [Air Resources Laboratory, Environmental Science Services Administration, Las Vegas, NV (United States)

    1969-07-01

    Meteorological support requirements for Plowshare nuclear detonations are shown to depend on a number of factors. The importance of adequate support to the effective planning and safe conduct of a nuclear detonation is described. An example of the influence of atmospheric conditions on radioactive cloud development and local transport and fallout of radioactive debris is presented. Prediction of the future state of atmospheric wind structure, required for fallout predictions depends on an adequate definition of its initial state and its rate of change. This definition, in turn, is shown to depend on an upper wind-sounding network of appropriate station density. An operational technique currently used for nuclear cratering fallout predictions is described and shown to produce results of useful accuracy. (author)

  5. Carbon Condensation during High Explosive Detonation with Time Resolved Small Angle X-ray Scattering

    Science.gov (United States)

    Hammons, Joshua; Bagge-Hansen, Michael; Nielsen, Michael; Lauderbach, Lisa; Hodgin, Ralph; Bastea, Sorin; Fried, Larry; May, Chadd; Sinclair, Nicholas; Jensen, Brian; Gustavsen, Rick; Dattelbaum, Dana; Watkins, Erik; Firestone, Millicent; Ilavsky, Jan; van Buuren, Tony; Willey, Trevor; Lawrence Livermore National Lab Collaboration; Los Alamos National Laboratory Collaboration; Washington State University/Advanced Photon Source Team

    Carbon condensation during high-energy detonations occurs under extreme conditions and on very short time scales. Understanding and manipulating soot formation, particularly detonation nanodiamond, has attracted the attention of military, academic and industrial research. An in-situ characterization of these nanoscale phases, during detonation, is highly sought after and presents a formidable challenge even with today's instruments. Using the high flux available with synchrotron X-rays, pink beam small angle X-ray scattering is able to observe the carbon phases during detonation. This experimental approach, though powerful, requires careful consideration and support from other techniques, such as post-mortem TEM, EELS and USAXS. We present a comparative survey of carbon condensation from different CHNO high explosives. This work was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344.

  6. High speed video shooting with continuous-wave laser illumination in laboratory modeling of wind - wave interaction

    Science.gov (United States)

    Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Sergeev, Daniil; Vdovin, Maxim

    2014-05-01

    Three examples of usage of high-speed video filming in investigation of wind-wave interaction in laboratory conditions is described. Experiments were carried out at the Wind - wave stratified flume of IAP RAS (length 10 m, cross section of air channel 0.4 x 0.4 m, wind velocity up to 24 m/s) and at the Large Air-Sea Interaction Facility (LASIF) - MIO/Luminy (length 40 m, cross section of air channel 3.2 x 1.6 m, wind velocity up to 10 m/s). A combination of PIV-measurements, optical measurements of water surface form and wave gages were used for detailed investigation of the characteristics of the wind flow over the water surface. The modified PIV-method is based on the use of continuous-wave (CW) laser illumination of the airflow seeded by particles and high-speed video. During the experiments on the Wind - wave stratified flume of IAP RAS Green (532 nm) CW laser with 1.5 Wt output power was used as a source for light sheet. High speed digital camera Videosprint (VS-Fast) was used for taking visualized air flow images with the frame rate 2000 Hz. Velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave profile. The mean wind velocity profiles were retrieved using conditional in phase averaging like in [1]. In the experiments on the LASIF more powerful Argon laser (4 Wt, CW) was used as well as high-speed camera with higher sensitivity and resolution: Optronics Camrecord CR3000x2, frame rate 3571 Hz, frame size 259×1696 px. In both series of experiments spherical 0.02 mm polyamide particles with inertial time 7 ms were used for seeding airflow. New particle seeding system based on utilization of air pressure is capable of injecting 2 g of particles per second for 1.3 - 2.4 s without flow disturbance. Used in LASIF this system provided high particle density on PIV-images. In combination with high-resolution camera it allowed us to obtain momentum fluxes directly from

  7. Sub-Chandrasekhar-mass White Dwarf Detonations Revisited

    Science.gov (United States)

    Shen, Ken J.; Kasen, Daniel; Miles, Broxton J.; Townsley, Dean M.

    2018-02-01

    The detonation of a sub-Chandrasekhar-mass white dwarf (WD) has emerged as one of the most promising Type Ia supernova (SN Ia) progenitor scenarios. Recent studies have suggested that the rapid transfer of a very small amount of helium from one WD to another is sufficient to ignite a helium shell detonation that subsequently triggers a carbon core detonation, yielding a “dynamically driven double-degenerate double-detonation” SN Ia. Because the helium shell that surrounds the core explosion is so minimal, this scenario approaches the limiting case of a bare C/O WD detonation. Motivated by discrepancies in previous literature and by a recent need for detailed nucleosynthetic data, we revisit simulations of naked C/O WD detonations in this paper. We disagree to some extent with the nucleosynthetic results of previous work on sub-Chandrasekhar-mass bare C/O WD detonations; for example, we find that a median-brightness SN Ia is produced by the detonation of a 1.0 {M}ȯ WD instead of a more massive and rarer 1.1 {M}ȯ WD. The neutron-rich nucleosynthesis in our simulations agrees broadly with some observational constraints, although tensions remain with others. There are also discrepancies related to the velocities of the outer ejecta and light curve shapes, but overall our synthetic light curves and spectra are roughly consistent with observations. We are hopeful that future multidimensional simulations will resolve these issues and further bolster the dynamically driven double-degenerate double-detonation scenario’s potential to explain most SNe Ia.

  8. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.

    2014-11-07

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations are carried out in order to explore the stability of the steady-state solutions. It is found that both collapsing and expanding two-dimensional cellular detonations exist. The latter can be stabilized by putting several rigid obstacles in the flow downstream of the steady-state sonic locus. The problem of initiation of standing detonation stabilized in the radial flow is also investigated numerically. © 2014 Cambridge University Press.

  9. Laser-generated acoustic wave studies on tattoo pigment

    Science.gov (United States)

    Paterson, Lorna M.; Dickinson, Mark R.; King, Terence A.

    1996-01-01

    A Q-switched alexandrite laser (180 ns at 755 nm) was used to irradiate samples of agar embedded with red, black and green tattoo dyes. The acoustic waves generated in the samples were detected using a PVDF membrane hydrophone and compared to theoretical expectations. The laser pulses were found to generate acoustic waves in the black and green samples but not in the red pigment. Pressures of up to 1.4 MPa were produced with irradiances of up to 96 MWcm-2 which is comparable to the irradiances used to clear pigment embedded in skin. The pressure gradient generated across pigment particles was approximately 1.09 X 1010 Pam-1 giving a pressure difference of 1.09 +/- 0.17 MPa over a particle with mean diameter 100 micrometers . This is not sufficient to permanently damage skin which has a tensile strength of 7.4 MPa.

  10. Propagation of bulk longitudinal waves in thin films using laser ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yun Young [Dept. of Mechanical Engineering, Dong-eui University, Busan (Korea, Republic of)

    2016-08-15

    This paper presents the investigation of the propagation behavior of bulk longitudinal waves generated by an ultrafast laser system in thin films. A train of femtosecond laser pulses was focused onto the surface of a 150-nm thick metallic (chromium or aluminum) film on a silicon substrate to excite elastic waves, and the change in thermoreflectance at the spot was monitored to detect the arrival of echoes from the film/substrate interface. The experimental results show that the film material characteristics such as the wave velocity and Young's modulus can be evaluated through curve-fitting in numerical solutions. The material properties of nanoscale thin films are difficult to measure using conventional techniques. Therefore, this research provides an effective method for the nondestructive characterization of nanomaterials.

  11. Nonlinear Waves on Stochastic Support: Calcium Waves in Astrocyte Syncytia

    Science.gov (United States)

    Jung, P.; Cornell-Bell, A. H.

    Astrocyte-signaling has been observed in cell cultures and brain slices in the form of Calcium waves. Their functional relevance for neuronal communication, brain functions and diseases is, however, not understood. In this paper, the propagation of intercellular calcium waves is modeled in terms of waves in excitable media on a stochastic support. We utilize a novel method to decompose the spatiotemporal patterns into space-time clusters (wave fragments). Based on this cluster decomposition, a statistical description of wave patterns is developed.

  12. Modeling and analysis of hydrogen detonation events in the Advanced Neutron Source reactor containment

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.; Georgevich, V.; Kim, S.H.; Valenti, S.N.; Simpson, D.B.; Sawruk, W.

    1994-07-01

    This paper describes salient aspects of the modeling, analyses, and evaluations for hydrogen detonation in selected regions of the Advanced Neutron Source (ANS) containment during hypothetical severe accident conditions. Shock wave generation and transport modeling and analyses were conducted for two stratified configurations in the dome region of the high bay. Principal tools utilized for these purposes were the CTH and CET89 computer codes. Dynamic pressure loading functions were generated for key locations and used for evaluating structural response behavior for which a finite-element model was developed using the ANSYS code. For the range of conditions analyzed in the two critical dome regions, it was revealed that the ANS containment would be able to withstand detonation loads without failure

  13. Modeling and analysis of hydrogen detonation events in the advanced neutron source reactor containment

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.; Georgevich, V.; Kim, S.H.; Valenti, S.; Simpson, D.B.; Sawruk, W.

    1994-01-01

    This paper describes salient aspects of the modeling, analyses, and evaluations for hydrogen detonation in selected regions of the Advanced Neutron Source (ANS) containment during hypothetical severe accident conditions. Shock wave generation and transport modeling and analyses were conducted for two stratified configurations in the dome region of the high bay. Principal tools utilized for these purposes were the CTH and CET89 computer codes. Dynamic pressure loading functions were generated for key locations and used for evaluating structural response behavior for which a finite-element model was developed using the ANSYS code. For the range of conditions analyzed in the two critical dome regions, it was revealed that the ANS containment would be able to withstand detonation loads without failure. (author)

  14. Energetic, spectral, and temporal characteristics of a two-wave CO/sub 2/ laser

    Energy Technology Data Exchange (ETDEWEB)

    Bertel' , I.M.; Petukhov, V.O.; Prokopov, A.P.; Tochitskii, S.Ya.; Churakov, V.V.

    1987-09-01

    This work studies the energetic and temporal parameters of a pulsed two-wave TEA CO/sub 2/ laser's radiation and the means for controlling these parameters. Obtaining the two-wave generation regime in CO/sub 2/ lasers uses, as is known, spatial splitting of the radiation, different variants of operating diffraction gratings, and placing a cell with selectively absorbing gas in the resonator. To realize the simultaneous two-wave generation regime in the present work, a double-resonant scheme is used with mutually orthogonal polarizers to spatially separate the radiation.

  15. Detonation engine fed by acetylene-oxygen mixture

    Science.gov (United States)

    Smirnov, N. N.; Betelin, V. B.; Nikitin, V. F.; Phylippov, Yu. G.; Koo, Jaye

    2014-11-01

    The advantages of a constant volume combustion cycle as compared to constant pressure combustion in terms of thermodynamic efficiency has focused the search for advanced propulsion on detonation engines. Detonation of acetylene mixed with oxygen in various proportions is studied using mathematical modeling. Simplified kinetics of acetylene burning includes 11 reactions with 9 components. Deflagration to detonation transition (DDT) is obtained in a cylindrical tube with a section of obstacles modeling a Shchelkin spiral; the DDT takes place in this section for a wide range of initial mixture compositions. A modified ka-omega turbulence model is used to simulate flame acceleration in the Shchelkin spiral section of the system. The results of numerical simulations were compared with experiments, which had been performed in the same size detonation chamber and turbulent spiral ring section, and with theoretical data on the Chapman-Jouguet detonation parameters.

  16. Deflagration to detonation transition in thermonuclear supernovae

    International Nuclear Information System (INIS)

    Charignon, Camille

    2013-01-01

    Type Ia supernovae are an important tool to determine the expansion history of our Universe. Thus, considerable attention has been given to both observations and models of these events. The most popular explosion model is the central ignition of a deflagration in the dense C+O interior of a Chandrasekhar mass white dwarf, followed by a transition to a detonation (TDD). We study in this thesis a new mechanism for this transition. The most robust and studied progenitor model and the postulated mechanism for the TDD, the so called 'Zel'dovich gradient mechanism', are presented. State of the art 3D simulations of such a delayed detonation, at the price of some adjustments, can indeed reproduce observables. But due to largely unresolved physical scales, such simulations cannot explain the TDD by themselves, and especially, the physical mechanism which triggers this transition - which is not yet understood, even on Earth, for unconfined media. It is then discussed why the current Zel'dovich mechanism might be too constraining for a SN Ia model, pointing to a new approach, which is the core result of this thesis.In the final part, our alternative model for DDT in supernovae, the acoustic heating of the pre-supernova envelope, is presented. A planar model first proves that small amplitude acoustic perturbations (generated by a turbulent flame) are actually amplified in a steep density gradient, up to a point where they turn into shocks able to trigger a detonation. Then, this mechanism is applied to more realistic models, taking into account, in spherical geometry, the expanding envelope. A parametric study demonstrates the validity of the model for a reasonable range of acoustic wave amplitudes and frequencies.To conclude, some exploratory 2D and 3D MHD simulations, seeking for realistic acoustic source compatible with our mechanism, are presented. (author) [fr

  17. Heat wave propagation in a thin film irradiated by ultra-short laser pulses

    International Nuclear Information System (INIS)

    Yoo, Jae Gwon; Kim, Cheol Jung; Lim, C. H.

    2004-01-01

    A thermal wave solution of a hyperbolic heat conduction equation in a thin film is developed on the basis of the Green's function formalism. Numerical computations are carried out to investigate the temperature response and the propagation of the thermal wave inside a thin film due to a heat pulse generated by ultra-short laser pulses with various laser pulse durations and thickness of the film

  18. POWER SCALING IN CONTINUOUS-WAVE YB:YAG MICROCHIP LASER FOR MEASURING APPLICATIONS

    Directory of Open Access Journals (Sweden)

    A. M. Ivashko

    2017-01-01

    Full Text Available Characteristics optimization of lasers used in different measuring systems is of great interest up to now. Diode-pumped microchip lasers is one of the most perspective ways for development of solid-state light sources with minimal size and weight together with low energy power consumption. Increasing of output power with good beam quality is rather difficult task for such type of lasers due to thermal effects in the gain crystal under high pump power.The investigation results of continuous-wave longitudinally diode-pumped Yb:YAG microchip laser are presented. In the presented laser radiation from multiple pump laser diodes were focused into the separate zone in one gain crystal that provides simultaneous generation of multiple laser beams. The energy and spatial laser beam characteristics were investigated.Influence of neighboring pumped regions on energy and spatial laser beams parameters both for separate and for sum laser output was observed. The dependences of laser output power from distance between neighboring pumped regions and their number were determined. Decreasing of laser output power was demonstrated with corresponding distance shortening between pumped regions and increasing their quantity with simultaneous improvement of laser beam quality.Demonstrated mutual influence of neighboring pumped regions in the longitudinally diode pumped Yb:YAG microchip laser allow as to generate diffraction limited Gaussian beam with 2W of continuous-wave output power that 30 % higher than in case of one pumped zone. 

  19. Modes in light wave propagating in semiconductor laser

    Science.gov (United States)

    Manko, Margarita A.

    1994-01-01

    The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

  20. The measurement of capillary waves on a weldpool formed by a Nd:YAG laser

    International Nuclear Information System (INIS)

    Deam, R.T.; Brandt, M.; Harris, J.

    2002-01-01

    Experiments were performed using an on-line pyrometer to measure the capillary waves on a weldpool formed by a Nd: YAG laser. The surface temperature measurements taken from the weldpool revealed strong temporal fluctuations. Fourier transform of the pyrometer data revealed distinct peaks, consistent with calculated resonant frequencies for capillary surface waves on the weldpool formed by the laser. The possibility of using on-line measurement of surface temperature fluctuations to control weldpool depth in laser welds is discussed. The work forms part of an on-going programme to develop closed loop control for laser processing at Swinburne University

  1. Bragg-Scattering Four-Wave Mixing in Nonlinear Fibers with Intracavity Frequency-Shifted Laser Pumps

    Directory of Open Access Journals (Sweden)

    Katarzyna Krupa

    2012-01-01

    Full Text Available We experimentally study four-wave mixing in highly nonlinear fibers using two independent and partially coherent laser pumps and a third coherent signal. We focus our attention on the Bragg-scattering frequency conversion. The two pumps were obtained by amplifying two Intracavity frequency-shifted feedback lasers working in a continuous wave regime.

  2. TUMOR-GROWTH DELAY BY LASER-GENERATED SHOCK-WAVES

    NARCIS (Netherlands)

    de Reijke, T. M.; Schamhart, D. H.; Kurth, K. H.; Löwik, C. W.; Donkers, L. H.; Sterenborg, H. J.

    1994-01-01

    The antiproliferative effect of laser-generated shock waves (L-SW) was investigated on a human renal cell carcinoma, RC-8, grown subcutaneously in the nu/nu mouse. The RC-8 is characterized by the syndrome of humoral hypercalcemia of malignancy (HHM) associated with profound cachexia, increase of

  3. Histologic evaluation of laser lipolysis comparing continuous wave vs pulsed lasers in an in vivo pig model.

    Science.gov (United States)

    Levi, Jessica R; Veerappan, Anna; Chen, Bo; Mirkov, Mirko; Sierra, Ray; Spiegel, Jeffrey H

    2011-01-01

    To evaluate acute and delayed laser effects of subdermal lipolysis and collagen deposition using an in vivo pig model and to compare histologic findings in fatty tissue after continuous wave diode (CW) vs pulsed laser treatment. Three CW lasers (980, 1370, and 1470 nm) and 3 pulsed lasers (1064, 1320, and 1440 nm) were used to treat 4 Göttingen minipigs. Following administration of Klein tumescent solution, a laser cannula was inserted at the top of a 10 × 2.5-cm rectangle and was passed subdermally to create separate laser "tunnels." Temperatures at the surface and at intervals of 4-mm to 20-mm depths were recorded immediately after exposure and were correlated with skin injury. Full-thickness cutaneous biopsy specimens were obtained at 1 day, 1 week, and 1 month after exposure and were stained with hematoxylin-eosin and trichrome stain. Qualitative and semiquantitative histopathologic evaluations were performed with attention to vascular damage, lipolysis, and collagen deposition. Skin surface damage occurred at temperatures exceeding 46°C. Histologic examination at 1 day after exposure showed hemorrhage, fibrous collagen fiber coagulation, and adipocyte damage. Adipocytes surrounded by histiocytes, a marker of lipolysis, were present at 1 week and 1 month after exposure. Collagen deposition in subdermal fatty tissue and in reticular dermis of some specimens was noted at 1 week and had increased at 1 month. Tissue treated with CW laser at 1470 nm demonstrated greater hemorrhage and more histiocytes at damage sites than tissue treated with pulsed laser at 1440 nm. There was a trend toward more collagen deposition with pulsed lasers than with CW lasers, but this was not statistically significant. Histopathologic comparison between results of CW laser at 980 nm vs pulsed laser at 1064 nm showed the same trend. Hemorrhage differences may result from pulse duration variations. A theoretical calculation estimating temperature rise in vessels supported this

  4. Formation and decay of laser-generated shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Cottet, F.; Romain, J.P.

    1982-01-01

    The process of formation and decay of laser-generated shock waves is described by a hydrodynamic model. Measurements of shock velocities are performed on copper foils for incident intensities between 3 x 10/sup 11/ and 3 x 10/sup 12/ W/cm/sup 2/, with the use of piezoelectric detectors. Maximum induced pressures are found between 0.5 and 1.2 Mbar in the intensity range considered. Analysis of the results with the shock-evolution model outlines the importance of the decay process of laser-generated shocks.

  5. Detonation measurements on damaged LX-04

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Peter; Souers, P.C.; Chidester, Steve; Alvarez, John; De Haven, Martin; Garza, Raul; Harwood, Pat; Maienschein, Jon [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)

    2007-12-15

    We have applied thermal insults on LX-04 at 185 C and found that the material expanded significantly, resulting in a bulk density reduction of 12%. Subsequent detonation experiments (three cylinder tests) were conducted on the thermally damaged LX-04 samples and pristine low-density LX-04 samples and the results showed that the fractions reacted were close to 1.0. The thermally damaged LX-04 and pristine low-density LX-04 showed detonation velocities of 7.7-7.8 mm {mu}s{sup -1}, significantly lower than that (8.5 mm {mu}s{sup -1}) of pristine high-density LX-04. Detonation energy densities for the damaged LX-04, low-density pristine LX-04, and hot cylinder shot of LX-04 were 6.48, 6.62, and 6.58 kJ cm{sup -3}, respectively, lower than the detonation energy density of 8.11 kJ cm{sup -3} for the high density pristine LX-04. The break-out curves for the detonation fronts showed that the damaged LX-04 had longer edge lags than the high density pristine LX-04, indicating that the damaged explosive is less ideal. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  6. Second-order interference of two independent and tunable single-mode continuous-wave lasers

    International Nuclear Information System (INIS)

    Liu Jianbin; Chen Hui; Zheng Huaibin; Xu Zhuo; Wei Dong; Zhou Yu; Gao Hong; Li Fu-Li

    2016-01-01

    The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by employing two-photon interference in Feynman’s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra. (paper)

  7. THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, G. C. IV; Graziani, C.; Weide, K.; Norris, J.; Hudson, R.; Lamb, D. Q. [Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States); Fisher, R. T. [Department of Physics, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02740 (United States); Townsley, D. M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Meakin, C. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Reid, L. B. [NTEC Environmental Technology, Subiaco WA 6008 (Australia)

    2012-11-01

    We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.

  8. Status of advanced ground-based laser interferometers for gravitational-wave detection

    Science.gov (United States)

    Dooley, K. L.; Akutsu, T.; Dwyer, S.; Puppo, P.

    2015-05-01

    Ground-based laser interferometers for gravitational-wave (GW) detection were first constructed starting 20 years ago and as of 2010 collection of several years’ worth of science data at initial design sensitivities was completed. Upgrades to the initial detectors together with construction of brand new detectors are ongoing and feature advanced technologies to improve the sensitivity to GWs. This conference proceeding provides an overview of the common design features of ground-based laser interferometric GW detectors and establishes the context for the status updates of each of the four gravitational-wave detectors around the world: Advanced LIGO, Advanced Virgo, GEO 600 and KAGRA.

  9. 30 CFR 56.6402 - Deenergized circuits near detonators.

    Science.gov (United States)

    2010-07-01

    ... Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not be deenergized between 25 to 50 feet of the electric detonators if stray current tests, conducted as frequently...

  10. 30 CFR 57.6402 - Deenergized circuits near detonators.

    Science.gov (United States)

    2010-07-01

    ... Electric Blasting-Surface and Underground § 57.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not be deenergized between 25 to 50 feet of the electric detonators if stray current tests...

  11. Damage Detection on Thin-walled Structures Utilizing Laser Scanning and Standing Waves

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Se Hyeok; Jeon, Jun Young; Kim, Du Hwan; Park, Gyuhae [Chonnam Nat’l Univ., Gwangju (Korea, Republic of); Kang, To; Han, Soon Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-05-15

    This paper describes wavenumber filtering for damage detection using single-frequency standing wave excitation and laser scanning sensing. An embedded piezoelectric sensor generates ultrasonic standing waves, and the responses are measured using a laser Doppler vibrometer and mirror tilting device. After scanning, newly developed damage detection techniques based on wavenumber filtering are applied to the full standing wave field. To demonstrate the performance of the proposed techniques, several experiments were performed on composite plates with delamination and aluminum plates with corrosion damage. The results demonstrated that the developed techniques could be applied to various structures to localize the damage, with the potential to improve the damage detection capability at a high interrogation speed.

  12. Guided Wave Sensing In a Carbon Steel Pipe Using a Laser Vibrometer System

    Science.gov (United States)

    Ruíz Toledo, Abelardo; Salazar Soler, Jordi; Chávez Domínguez, Juan Antonio; García Hernández, Miguel Jesús; Turó Peroy, Antoni

    2010-05-01

    Non-Destructive Evaluation (NDE) techniques have achieved a great development during the last decades as a valuable tool for material characterization, manufacturing control and structural integrity tests. Among these tools, the guided wave technology has been rapidly extended because it reduces inspection time and costs compared to the ordinary point by point testing in large structures, as well as because of the possibility of inspecting under insulation and coating conditions. This fast development has motivated the creation of several inspection and material characterization systems including different technologies which can be combined with this technique. Different measurements systems based on laser techniques have been presented in order to inspect pipes, plates and diverse structures. Many of them are experimental systems of high cost and complexity which combine the employment of a laser for generation of waves in the structure and an interferometer for detection. Some of them employ air-coupled ultrasound generation transducers, with high losses in air and which demand high energy for exciting waves in materials of high stiffness. The combined employment of a commercial vibrometer system for Lamb wave sensing in plates has been successfully shown in the literature. In this paper we present a measurement system based on the combined employment of a piezoelectric wedge transducer and a laser vibrometer to sense guided acoustic waves in carbon steel pipes. The measurement system here presented is mainly compounded of an angular wedge transducer, employed to generate the guided wave and a commercial laser vibrometer used in the detection process. The wedge transducer is excited by means of a signal function generator whose output signal has been amplified with a power signal amplifier. A high precision positioning system is employed to place the laser beam at different points through the pipe surface. The signal detected by the laser vibrometer system is

  13. 30 CFR 75.1311 - Transporting explosives and detonators.

    Science.gov (United States)

    2010-07-01

    ... noncombustible materials. (c) When explosives and detonators are transported on conveyor belts— (1) Containers of... explosives or detonators, a person shall be at each transfer point between belts and at the unloading location; and (4) Conveyor belts shall be stopped before explosives or detonators are loaded or unloaded...

  14. 30 CFR 57.6400 - Compatibility of electric detonators.

    Science.gov (United States)

    2010-07-01

    ... Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar electrical... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compatibility of electric detonators. 57.6400...

  15. 30 CFR 56.6400 - Compatibility of electric detonators.

    Science.gov (United States)

    2010-07-01

    ... Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar electrical firing characteristics. ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compatibility of electric detonators. 56.6400...

  16. Decay of a laser generated shock wave in an aluminium target

    International Nuclear Information System (INIS)

    Werdiger, M.

    1993-09-01

    When a shock wave arrives at the near surface of a solid material, a radical and fast change occurs in the reflection properties of the material. The phenomenon is used in the present work in order to develop a new way to measure the transit time of a shock wave in a target. A 10 milliwatt He:Ne laser is directed toward the rear surface of the target. The reflected beam arrives at a photo-diode with a fast rise time of 150 psec which detects the instant of the change in the reflection. This technique, called 'continuous back lightning', is used in experiments with aluminium foil thickness in the range of 40μm ≤x≥ 1000μm. The shock wave is induced by a laser pulse of an intensity of 3*10 13 W/cm 2 . The results show two main physical regimes: in the first one 40μ ≤x≥ 210μm, there is a constant shock wave velocity which in our experiments was measured to be (12.81±0.67)km/s. In the second range of the thickness where 300μm there is a decay of the shock velocity. For x ≥ 210μm the geometry is one dimensional for our experimental conditions, while for x ≥ 300μm the 1-D geometry changes to 2 dimensional (2-D) geometry. The 2-D shock wave decay asymptotically (x→∞ to an acoustic wave. shock wave is described by a pressure scaling as x -n (n is a positive constant). The phenomenological equation of the state is taken to be P=A**u s + B*u s 2 +Bu s , where P is the pressure, u s - the shock velocity, A and B are constants. Applying our experimental results to the solution of the differential equation in this model A*x 2 ± B*x=C*x -n yields a value of n in the range 3.16 ≤n≥ 3.51. This pressure scaling law agrees with the self-similar solution of a concentrated impact on a surface between two media. This situation is well simulated by the laser deposition energy on a metal surface. In the experiment a 5% accuracy is achieved. Such a good accuracy has not been achieved so far in a laser induced shock-wave measurements in solids. (author). 52 refs

  17. The influence of the gaseous by-products from detonation and inert additives to explosives on the efficiency of mining rock breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Komir, V.M.; Chebenko, V.N.; Napadailo, V.I.; Rodak, S.N.

    1981-01-01

    Results are given from experiments to determine the influence of inert additives to explosives on the intensity of crushing mining rock. The mechanism of the blast action during the destruction of the samples using carbonic acid and sand as the additives is examined. An analysis of the experimental results demonstrated that the disjoining action of the detonation products is the result of the determinate role of the radial cracks in increasing the radius of the zone--these waves are generated by the shock wave. The efficiency of the blast may be increased by using easily-decomposing additives in the explosive that during explosion, evaporate, and both give off a large amount of gas and decrease the temperature of the detonation products, and consequently, the intensity of heat exchange with the rock.

  18. Laser-generated shock-wave experiments in metals above 1 TPa

    International Nuclear Information System (INIS)

    Trainor, R.J.; Shaner, J.W.; Auerbach, J.M.; Phillion, D.W.

    1978-01-01

    Some initial experiments are described which form part of a new program aimed at significantly extending the range of high pressures and densities which may be explored in laboratory equation-of-state (EOS) experiments. These experiments will utilize high-energy lasers, such as those employed in the Laser Fusion Program at Lawrence Livermore Laboratory (LLL), to generate intense shock waves in materials of interest

  19. Photonic synthesis of continuous‐wave millimeter‐wave signals using a passively mode‐locked laser diode and selective optical filtering

    DEFF Research Database (Denmark)

    Acedo, P.; Carpintero, G.; Criado, A.R.

    2012-01-01

    We report a photonic synthesis scheme for continuous wave millimeter‐wave signal generation using a single passively mode‐locked laser diode (PMLLD), optical filtering and photomixing in a fast photodiode.The phase noise of the photonically synthesized signals is evaluated and inherits...

  20. A diode-end-pumped Nd:GYSGG continuous wave laser at 1104 nm

    International Nuclear Information System (INIS)

    Shen, B J; Kang, H X; Zhang, C G; Chen, P; Gao, R L; Liang, J; Gao, H J; Zhang, Q L; Sun, D L; Yin, S T; Luo, J Q

    2013-01-01

    The continuous wave (CW) laser performance of Nd:GYSGG at 1104 nm is investigated for the first time, to our knowledge. A CW laser output power of 4.7 W is obtained when the pump power of the 808 nm fiber coupled laser diode is 19.1 W, corresponding to a conversion efficiency of 24.6% and slope efficiency of 37%. (paper)

  1. Insensitive detonator apparatus for initiating large failure diameter explosives

    Science.gov (United States)

    Perry, III, William Leroy

    2015-07-28

    A munition according to a preferred embodiment can include a detonator system having a detonator that is selectively coupled to a microwave source that functions to selectively prime, activate, initiate, and/or sensitize an insensitive explosive material for detonation. The preferred detonator can include an explosive cavity having a barrier within which an insensitive explosive material is disposed and a waveguide coupled to the explosive cavity. The preferred system can further include a microwave source coupled to the waveguide such that microwaves enter the explosive cavity and impinge on the insensitive explosive material to sensitize the explosive material for detonation. In use the preferred embodiments permit the deployment and use of munitions that are maintained in an insensitive state until the actual time of use, thereby substantially preventing unauthorized or unintended detonation thereof.

  2. 14 CFR 33.47 - Detonation test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Detonation test. 33.47 Section 33.47 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.47 Detonation test. Each engine...

  3. Performance and environmental impact assessment of pulse detonation based engine systems

    Science.gov (United States)

    Glaser, Aaron J.

    diverging ejector pressure distribution shows that the diverging section acts as a subsonic diffuser. To provide a better explanation of the observed performance trends, shadowgraph images of the detonation wave and starting vortex interacting with the ejector inlet were obtained. The acoustic signature of a pulse detonation engine was characterized in both the near-field and far-field regimes. Experimental measurements were performed in an anechoic test facility designed for jet noise testing. Both shock strength and speed were mapped as a function of radial distance and direction from the PDE exhaust plane. It was found that the PDE generated pressure field can be reasonably modeled by a theoretical point-source explosion. The effect of several exit nozzle configurations on the PDE acoustic signature was studies. These included various chevron nozzles, a perforated nozzle, and a set of proprietary noise attenuation mufflers. Experimental studies were carried out to investigate the performance of a hybrid propulsion system integrating an axial flow turbine with multiple pulse detonation combustors. The integrated system consisted of a circular array of six pulse detonation combustor (PDC) tubes exhausting through an axial flow turbine. Turbine component performance was quantified by measuring the amount of power generated by the turbine section. Direct comparisons of specific power output and turbine efficiency between a PDC-driven turbine and a turbine driven by steady-flow combustors were made. It was found that the PDC-driven turbine had comparable performance to that of a steady-burner-driven turbine across the operating map of the turbine.

  4. Introduction to Physics and Chemistry of Combustion Explosion, Flame, Detonation

    CERN Document Server

    Liberman, Michael A

    2008-01-01

    Most of the material covered in this book deals with the fundamentals of chemistry and physics of key processes and fundamental mechanisms for various combustion and combustion related phenomena in gaseous combustible mixture. It provides the reader with basic knowledge of burning processes and mechanisms of reaction wave propagation. The combustion of a gas mixture (flame, explosion, detonation) is necessarily accompanied by motion of the gas. The process of combustion is therefore not only a chemical phenomenon but also one of gas dynamics. The material selection focuses on the gas phase and

  5. Acoustic waves in transversely excited atmospheric CO2 laser discharges: effect on performance and reduction techniques

    CSIR Research Space (South Africa)

    von Bergmann, HM

    2008-08-01

    Full Text Available Results are presented on the influence of acoustic waves on the performance of high-repetition-rate TEA CO2 lasers. It is shown that acoustic waves generated inside the laser cavity lead to nonuniform discharges, resulting in a deterioration...

  6. rhoCentralRfFoam: An OpenFOAM solver for high speed chemically active flows - Simulation of planar detonations -

    Science.gov (United States)

    Gutiérrez Marcantoni, L. F.; Tamagno, J.; Elaskar, S.

    2017-10-01

    A new solver developed within the framework of OpenFOAM 2.3.0, called rhoCentralRfFoam which can be interpreted like an evolution of rhoCentralFoam, is presented. Its use, performing numerical simulations on initiation and propagation of planar detonation waves in combustible mixtures H2-Air and H2-O2-Ar, is described. Unsteady one dimensional (1D) Euler equations coupled with sources to take into account chemical activity, are numerically solved using the Kurganov, Noelle and Petrova second order scheme in a domain discretized with finite volumes. The computational code can work with any number of species and its corresponding reactions, but here it was tested with 13 chemically active species (one species inert), and 33 elementary reactions. A gaseous igniter which acts like a shock-tube driver, and powerful enough to generate a strong shock capable of triggering exothermic chemical reactions in fuel mixtures, is used to start planar detonations. The following main aspects of planar detonations are here, treated: induction time of combustible mixtures cited above and required mesh resolutions; convergence of overdriven detonations to Chapman-Jouguet states; detonation structure (ZND model); and the use of reflected shocks to determine induction times experimentally. The rhoCentralRfFoam code was verified comparing numerical results and it was validated, through analytical results and experimental data.

  7. Numerical study of laser-induced blast wave coupled with unsteady ionization processes

    International Nuclear Information System (INIS)

    Ogino, Y; Ohnishi, N; Sawada, K

    2008-01-01

    We present the results of the numerical simulation of laser-induced blast wave coupled with rate equations to clarify the unsteady property of ionization processes during pulse heating. From comparison with quasi-steady computations, the plasma region expands more widely, which is sustained by the inverse-bremsstrahlung since an ionization equilibrium does not establish at the front of the plasma region. The delayed relaxation leads to the rapid expansion of the driving plasma and enhances the energy conversion efficiency from a pulse heating laser to the blast wave

  8. Status of advanced ground-based laser interferometers for gravitational-wave detection

    International Nuclear Information System (INIS)

    Dooley, K L; Akutsu, T; Dwyer, S; Puppo, P

    2015-01-01

    Ground-based laser interferometers for gravitational-wave (GW) detection were first constructed starting 20 years ago and as of 2010 collection of several years’ worth of science data at initial design sensitivities was completed. Upgrades to the initial detectors together with construction of brand new detectors are ongoing and feature advanced technologies to improve the sensitivity to GWs. This conference proceeding provides an overview of the common design features of ground-based laser interferometric GW detectors and establishes the context for the status updates of each of the four gravitational-wave detectors around the world: Advanced LIGO, Advanced Virgo, GEO 600 and KAGRA. (paper)

  9. Numerical Investigation on the Propagation Mechanism of Steady Cellular Detonations in Curved Channels

    International Nuclear Information System (INIS)

    Li Jian; Ning Jian-Guo; Zhao Hui; Wang Cheng; Hao Li

    2015-01-01

    The propagation mechanism of steady cellular detonations in curved channels is investigated numerically with a detailed chemical reaction mechanism. The numerical results demonstrate that as the radius of the curvature decreases, detonation fails near the inner wall due to the strong expansion effect. As the radius of the curvature increases, the detonation front near the inner wall can sustain an underdriven detonation. In the case where detonation fails, a transverse detonation downstream forms and re-initiates the quenched detonation as it propagates toward the inner wall. Two kinds of propagation modes exist as the detonation is propagating in the curved channel. One is that the detonation fails first, and then a following transverse detonation initiates the quenched detonation and this process repeats itself. The other one is that without detonation failure and re-initiation, a steady detonation exists which consists of an underdriven detonation front near the inner wall subject to the diffraction and an overdriven detonation near the outer wall subject to the compression. (paper)

  10. First-Principles Petascale Simulations for Predicting Deflagration to Detonation Transition in Hydrogen-Oxygen Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Khokhlov, Alexei [Univ. of Chicago, IL (United States). Dept. of Astronomy and Astrophysics. Enrico Fermi Inst.; Austin, Joanna [Argonne National Lab. (ANL), Argonne, IL (United States). Argonne Leadership Computing Facility; Bacon, C. [Univ. of Illinois, Urbana, IL (United States). Dept. of Aerospace Engineering

    2015-03-02

    Hydrogen has emerged as an important fuel across a range of industries as a means of achieving energy independence and to reduce emissions. DDT and the resulting detonation waves in hydrogen-oxygen can have especially catastrophic consequences in a variety of industrial and energy producing settings related to hydrogen. First-principles numerical simulations of flame acceleration and DDT are required for an in-depth understanding of the phenomena and facilitating design of safe hydrogen systems. The goals of this project were (1) to develop first-principles petascale reactive flow Navier-Stokes simulation code for predicting gaseous high-speed combustion and detonation (HSCD) phenomena and (2) demonstrate feasibility of first-principles simulations of rapid flame acceleration and deflagration-to-detonation transition (DDT) in stoichiometric hydrogen-oxygen mixture (2H2 + O2). The goals of the project have been accomplished. We have developed a novel numerical simulation code, named HSCD, for performing first-principles direct numerical simulations of high-speed hydrogen combustion. We carried out a series of validating numerical simulations of inert and reactive shock reflection experiments in shock tubes. We then performed a pilot numerical simulation of flame acceleration in a long pipe. The simulation showed the transition of the rapidly accelerating flame into a detonation. The DDT simulations were performed using BG/Q Mira at the Argonne National Laboratory, currently the fourth fastest super-computer in the world.

  11. Detection of Fatigue Damage by Using Frequency Attenuation of a Laser Ultrasonic Longitudinal Wave

    International Nuclear Information System (INIS)

    Park, Seung-Kyu; Baik, Sung-Hoon; Jung, Hyun-Kyu; Joo, Young-Sang; Cha, Hyung-Ki; Kang, Young-June

    2006-01-01

    The measurement of fatigue damage in nuclear power plant components is very important to prevent a catastrophic accident and the subsequent severe losses. Specifically, it is preferred to detect at an early stage of the fatigue damage. If the fatigue damage that is in danger of growing into a fracture is accurately detected, an appropriate treatment could be carried out to improve the condition. Although most engineers and designers take precautions against fatigue, some breakdowns of nuclear power plant components still occur due to fatigue damage. It is considered that ultrasound testing technique is the most promising method to detect the fatigue damage in many nondestructive testing methods. Ultrasound testing method has a variety of elastic waves, such as a longitudinal wave, a shear wave, a surface wave and a lamb wave. Also we can use various analysis methods, such as a velocity variation and a signal attenuation. Laser ultrasonic testing has attracted attention as a non-contact testing technique. This system consists of a pulse laser to remotely generate ultrasound and a laser interferometer to remotely measure the surface displacement due to the generated ultrasound. This noncontact testing technique has the following advantages over the conventional piezoelectric transducers. Firstly, the inspection system can be remotely operated for a structure in hostile environments, such as in high radioactivity, high temperatures and narrow spaces. Secondly, we can obtain lots of information from the received ultrasonic waveforms because the laser ultrasonic technique does not require fluid couplant which disturbs the ultrasonic waveforms. Thirdly, laser ultrasound has a wideband spectrum and a high spatial resolution. Therefore, the laser ultrasound provides more accurate information for a testing material and has potential for the detection of fatigue damage in various metals composing a nuclear power plant

  12. Plasmas and intense laser light

    International Nuclear Information System (INIS)

    Kennedy, E.T.

    1984-01-01

    The present article begins with a description of the laser technology required to reach the high irradiances of interest and provides a brief outline of the more important diagnostic techniques used in investigating the plasmas. An introduction to plasma waves is given and the linear and nonlinear excitation of waves is discussed. The remainder of the article describes some of the experimental evidence supporting the interpretation of the plasma behaviour at high laser-light intensities in terms of the excitation of plasma waves and the subsequent heating of plasma by these waves. (author)

  13. A library of prompt detonation reaction zone data

    Energy Technology Data Exchange (ETDEWEB)

    Souers, P. C., LLNL

    1998-06-01

    Tables are given listing literature data that allows calculation of sonic reaction zones at or near steady-state for promptly detonating explosive cylinders. The data covers homogeneous, heterogeneous, composite, inorganic and binary explosives and allows comparison across the entire explosive field. Table 1 lists detonation front curvatures. Table 2 lists Size Effect data, i.e. the change of detonation velocity with cylinder radius. Table 3 lists failure radii and detonation velocities. Table 4 lists explosive compositions. A total of 51 references dating back into the 1950`s are given. Calculated reaction zones, radii of curvature and growth rate coefficients are listed.

  14. Allowable propagation of short pulse laser beam in a plasma channel and electromagnetic solitary waves

    International Nuclear Information System (INIS)

    Zhang, Shan; Hong, Xue-Ren; Wang, Hong-Yu; Xie, Bai-Song

    2011-01-01

    Nonparaxial and nonlinear propagation of a short intense laser beam in a parabolic plasma channel is analyzed by means of the variational method and nonlinear dynamics. The beam propagation properties are classified by five kinds of behaviors. In particularly, the electromagnetic solitary wave for finite pulse laser is found beside the other four propagation cases including beam periodically oscillating with defocussing and focusing amplitude, constant spot size, beam catastrophic focusing. It is also found that the laser pulse can be allowed to propagate in the plasma channel only when a certain relation for laser parameters and plasma channel parameters is satisfied. For the solitary wave, it may provide an effective way to obtain ultra-short laser pulse.

  15. Inverse free electron laser beat-wave accelerator research

    International Nuclear Information System (INIS)

    Marshall, T.C.; Bhattacharjee, A.

    1993-09-01

    A calculation on the stabilization of the sideband instability in the free electron laser (FEL) and inverse FEL (IFEL) was completed. The issue arises in connection with the use of a tapered (''variable-parameter'') undulator of extended length, such as might be used in an ''enhanced efficiency'' traveling-wave FEL or an IFEL accelerator. In addition, the FEL facility at Columbia was configured as a traveling wave amplifier for a 10-kW signal from a 24-GHz magnetron. The space charge field in the bunches of the FEL was measured. Completed work has been published

  16. Comparative study of acute lateral skin damage during radio wave and laser exposure

    Directory of Open Access Journals (Sweden)

    Dubensky V.V.

    2017-09-01

    Full Text Available The purpose was to study the depth and nature of the zones of thermal damage to the skin under radio wave and laser skin dissection during experiment. Material and Methods. The model of acute thermal damage was full-liner skin wounds of 20 nonlinear rats that were divided into 2 groups and operated by different methods. In the 1st group, the incisions were made by the apparatus of radio wave surgery (Surgitron DF S5, in the 2nd group the animals were operated with a laser surgical apparatus. The magnitude and structure of the lateral thermal damage was evaluated when analyzing the biopsy material. Results. During the study of experimental wounds, the extent of carbonation in the first group (operated with Surgitron DF S5 was 11.56±3.056 urn, coagulation necrosis 116.5±26.78 urn, and the hyper-thermiazone 148.42±60.171 urn. In the group of animals operated with a laser apparatus, the carbonization zone was 22.58±6.62 urn, the coagulation necrosis zone was 331.1±79.08 urn, and the hyperthermia extent was 376.2±53.27 urn. Conclusion. A comparative study of lateral skin damage in radio wave and laser skin dissection revealed a deeper thermal change in the skin and an increase in the extent of thermally altered structures under laser action: the carbonization zone was larger than for radio waves by 11.02 urn, coagulation necrosis by 214.6 urn, and the hyperthermia zone by 227.78 urn.

  17. Confined Detonations and Pulse Detonation Engines

    Science.gov (United States)

    2003-01-01

    detonation. Actes du Colloque International Berthelot-Vieille- Mallard- Le Chatelier Proceedings. Bordeaux, France 2:437-42. 13. Edwards, D., G. Hooper, and R...A.A. Vasil’ev 1 Introduction ... ... .... ... .... . .. .. .. .. 41 2 Principles of DDT Acceleration ............... 42 3 Construction of DDT...Universit6 de Poitiers 1, Avenue Clement Ader E. DANIAU BP 40109, 86961 Futuroscope Cedex, France MBDA-F 8, rue Le Brix, BP 35 S.M. FROLOV 18020

  18. Energy of a shock wave generated in different metals under irradiation by a high-power laser pulse

    International Nuclear Information System (INIS)

    Gus'kov, S. Yu.; Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Skala, J.; Pisarczyk, P.

    2007-01-01

    The energies of a shock wave generated in different metals under irradiation by a high-power laser beam were determined experimentally. The experiments were performed with the use of targets prepared from a number of metals, such as aluminum, copper, silver and lead (which belong to different periods of the periodic table) under irradiation by pulses of the first and third harmonics of the PALS iodine laser at a radiation intensity of approximately 10 14 W/cm 2 . It was found that, for heavy metals, like for light solid materials, the fraction of laser radiation energy converted into the energy of a shock wave under irradiation by a laser pulse of the third harmonic considerably (by a factor of 2-3) exceeds the fraction of laser radiation energy converted under irradiation by a laser pulse of the first harmonic. The influence of radiation processes on the efficiency of conversion of the laser energy into the energy of the shock wave was analyzed

  19. Dynamics of electron acceleration in laser-driven wakefields. Acceleration limits and asymmetric plasma waves

    Energy Technology Data Exchange (ETDEWEB)

    Popp, Antonia

    2011-12-16

    The experiments presented in this thesis study several aspects of electron acceleration in a laser-driven plasma wave. High-intensity lasers can efficiently drive a plasma wave that sustains electric fields on the order of 100 GV/m. Electrons that are trapped in this plasma wave can be accelerated to GeV-scale energies. As the accelerating fields in this scheme are 3-4 orders of magnitude higher than in conventional radio-frequency accelerators, the necessary acceleration distance can be reduced by the same factor, turning laser-wakefield acceleration (LWFA) into a promising compact, and potentially cheaper, alternative. However, laser-accelerated electron bunches have not yet reached the parameter standards of conventional accelerators. This work will help to gain better insight into the acceleration process and to optimize the electron bunch properties. The 25 fs, 1.8 J-pulses of the ATLAS laser at the Max-Planck-Institute of Quantum Optics were focused into a steady-state flow gas cell. This very reproducible and turbulence-free gas target allows for stable acceleration of electron bunches. Thus the sensitivity of electron parameters to subtle changes of the experimental setup could be determined with meaningful statistics. At optimized experimental parameters, electron bunches of {approx}50 pC total charge were accelerated to energies up to 450 MeV with a divergence of {approx}2 mrad FWHM. As, in a new design of the gas cell, its length can be varied from 2 to 14 mm, the electron bunch energy could be evaluated after different acceleration distances, at two different electron densities. From this evolution important acceleration parameters could be extracted. At an electron density of 6.43. 10{sup 18} cm{sup -3} the maximum electric field strength in the plasma wave was determined to be {approx}160 GV/m. The length after which the relativistic electrons outrun the accelerating phase of the electric field and are decelerated again, the so-called dephasing length

  20. Dynamics of electron acceleration in laser-driven wakefields. Acceleration limits and asymmetric plasma waves

    International Nuclear Information System (INIS)

    Popp, Antonia

    2011-01-01

    The experiments presented in this thesis study several aspects of electron acceleration in a laser-driven plasma wave. High-intensity lasers can efficiently drive a plasma wave that sustains electric fields on the order of 100 GV/m. Electrons that are trapped in this plasma wave can be accelerated to GeV-scale energies. As the accelerating fields in this scheme are 3-4 orders of magnitude higher than in conventional radio-frequency accelerators, the necessary acceleration distance can be reduced by the same factor, turning laser-wakefield acceleration (LWFA) into a promising compact, and potentially cheaper, alternative. However, laser-accelerated electron bunches have not yet reached the parameter standards of conventional accelerators. This work will help to gain better insight into the acceleration process and to optimize the electron bunch properties. The 25 fs, 1.8 J-pulses of the ATLAS laser at the Max-Planck-Institute of Quantum Optics were focused into a steady-state flow gas cell. This very reproducible and turbulence-free gas target allows for stable acceleration of electron bunches. Thus the sensitivity of electron parameters to subtle changes of the experimental setup could be determined with meaningful statistics. At optimized experimental parameters, electron bunches of ∼50 pC total charge were accelerated to energies up to 450 MeV with a divergence of ∼2 mrad FWHM. As, in a new design of the gas cell, its length can be varied from 2 to 14 mm, the electron bunch energy could be evaluated after different acceleration distances, at two different electron densities. From this evolution important acceleration parameters could be extracted. At an electron density of 6.43. 10 18 cm -3 the maximum electric field strength in the plasma wave was determined to be ∼160 GV/m. The length after which the relativistic electrons outrun the accelerating phase of the electric field and are decelerated again, the so-called dephasing length, was found to be 4.9 mm

  1. Laser Generated Leaky Acoustic Waves for Needle Visualization.

    Science.gov (United States)

    Wu, Kai-Wen; Wang, Yi-An; Li, Pai-Chi

    2018-04-01

    Ultrasound (US)-guided needle operation is usually used to visualize both tissue and needle position such as tissue biopsy and localized drug delivery. However, the transducer-needle orientation is limited due to reflection of the acoustic waves. We proposed a leaky acoustic wave method to visualize the needle position and orientation. Laser pulses are emitted on top of the needle to generate acoustic waves; then, these acoustic waves propagate along the needle surface. Leaky wave signals are detected by the US array transducer. The needle position can be calculated by phase velocities of two different wave modes and their corresponding emission angles. In our experiments, a series of needles was inserted into a tissue mimicking phantom and porcine tissue to evaluate the accuracy of the proposed method. The results show that the detection depth is up to 51 mm and the insertion angle is up to 40° with needles of different diameters. It is demonstrated that the proposed approach outperforms the conventional B-mode US-guided needle operation in terms of the detection range while achieving similar accuracy. The proposed method reveals the potentials for further clinical applications.

  2. Traveling waves in a free-electron laser with an electromagnetic wiggler

    International Nuclear Information System (INIS)

    Olumi, Mohsen; Maraghechi, B; Rouhani, M H

    2011-01-01

    The propagation of electromagnetic traveling wave in a free-electron laser (FEL) with an electromagnetic wiggler is investigated using the relativistic fluid-Maxwell formulation. By adapting the traveling-wave ansatz, three coupled, nonlinear ordinary differential equations are obtained describing the nonlinear propagation of the coupled wave. These equations may be used to study saturation in FELs. By linearizing the nonlinear equations dispersion relations for the traveling wave are obtained. Numerical solution of the small-signal traveling dispersion relation reveals the coupling of radiation to both slow and fast space-charge waves. It is shown that the traveling wave, which is not a normal mode in a laboratory frame, becomes a normal mode in terms of a transformed variable.

  3. Reactive flow modeling of small scale detonation failure experiments for a baseline non-ideal explosive

    Energy Technology Data Exchange (ETDEWEB)

    Kittell, David E.; Cummock, Nick R.; Son, Steven F. [School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2016-08-14

    Small scale characterization experiments using only 1–5 g of a baseline ammonium nitrate plus fuel oil (ANFO) explosive are discussed and simulated using an ignition and growth reactive flow model. There exists a strong need for the small scale characterization of non-ideal explosives in order to adequately survey the wide parameter space in sample composition, density, and microstructure of these materials. However, it is largely unknown in the scientific community whether any useful or meaningful result may be obtained from detonation failure, and whether a minimum sample size or level of confinement exists for the experiments. In this work, it is shown that the parameters of an ignition and growth rate law may be calibrated using the small scale data, which is obtained from a 35 GHz microwave interferometer. Calibration is feasible when the samples are heavily confined and overdriven; this conclusion is supported with detailed simulation output, including pressure and reaction contours inside the ANFO samples. The resulting shock wave velocity is most likely a combined chemical-mechanical response, and simulations of these experiments require an accurate unreacted equation of state (EOS) in addition to the calibrated reaction rate. Other experiments are proposed to gain further insight into the detonation failure data, as well as to help discriminate between the role of the EOS and reaction rate in predicting the measured outcome.

  4. Rapidly tunable continuous-wave optical parametric oscillator pumped by a fiber laser

    NARCIS (Netherlands)

    Klein, M.E.; Gross, P.; Boller, Klaus J.; Auerbach, M.; Wessels, P.; Fallnich, C.

    2003-01-01

    We report on rapid, all-electronically controlled wavelength tuning of a continuous-wave (cw) optical parametric oscillator (OPO) pumped by an ytterbium fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled lithium niobate crystal in a

  5. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    Science.gov (United States)

    Baker, John; Thorpe, Ira

    2012-01-01

    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  6. Haemocompatibility Of Non-Functionalized And Plasmachemical Functionalized Detonation Nanodiamond Particles

    Directory of Open Access Journals (Sweden)

    Mitura K.

    2015-09-01

    Full Text Available The purpose of this paper is to present the innovative design of microwave plasma system for modification of detonation nanodiamond particles (DNP using a special rotating drum placed inside the reactor. Nanodiamond particles manufactured by detonation method reveal the biological activity depending on surface functionalization. Plasmachemical modification of detonation nanodiamond particles gives the possibility of controlling surface of nanodiamonds particles in biological tests. In this paper we would like to compare detonation nanodiamond (the grain sizes from 2 to 5 nm with modified detonation nanodiamond in rotary reactor chamber, by microwave plasma activated chemical vapour deposition (MW PACVD method in materials research (Raman and FT-IR spectroscopy and in vitro examinations with full of human blood. The results indicate haemocompatibility of non-modified detonation nanodiamond and modified nanodiamond by MW PACVD method in rotary reactor chamber (modified ND-3 and the presence of haemolysis in commercial detonation nanodiamond.

  7. Ultrafast streak and framing technique for the observation of laser driven shock waves in transparent solid targets

    International Nuclear Information System (INIS)

    Van Kessel, C.G.M.; Sachsenmaier, P.; Sigel, R.

    1975-01-01

    Shock waves driven by laser ablation in plane transparent plexiglass and solid hydrogen targets have been observed with streak and framing techniques using a high speed image converter camera, and a dye laser as a light source. The framing pictures have been made by mode locking the dye laser and using a wide streak slit. In both materials a growing hemispherical shock wave is observed with the maximum velocity at the onset of laser radiation. (author)

  8. Hydroxyapatite Reinforced Coatings with Incorporated Detonationally Generated Nanodiamonds

    International Nuclear Information System (INIS)

    Pramatarova, L.; Pecheva, E.; Hikov, T.; Fingarova, D.; Dimitrova, R.; Spassov, T.; Krasteva, N.; Mitev, D.

    2010-01-01

    We studied the effect of the substrate chemistry on the morphology of hydroxyapatite-detonational nanodiamond composite coatings grown by a biomimetic approach (immersion in a supersaturated simulated body fluid). When detonational nanodiamond particles were added to the solution, the morphology of the grown for 2 h composite particles was porous but more compact then that of pure hydroxyapatite particles. The nanodiamond particles stimulated the hydroxyapatite growth with different morphology on the various substrates (Ti, Ti alloys, glasses, Si, opal). Biocompatibility assay with MG63 osteoblast cells revealed that the detonational nanodiamond water suspension with low and average concentration of the detonational nanodiamond powder is not toxic to living cells.

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

    Science.gov (United States)

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

    2015-06-01

    Spatio-temporal evolution of Laser ablative shock waves (LASWs) from one dimensional periodic structured surfaces (1D-PSS) of Aluminum is studied using time resolved defocused shadowgraphy technique. LASWs are generated by focusing 7 ns pulses from second harmonic of Nd:YAG (532 nm, 10 Hz) laser on to 1D-PSS with sinusoidal and triangular modulations of varying periodicity. An expanded He-Ne laser (632.8 nm) is used as probe beam for shadowgraphy. Evolution of ablative shock front (SF) with 1.5 ns temporal resolution is used to measure position of the SF, its nature, density and pressure behind the SF. The effect of surface modulation on the LASW and contact front dynamics was compared to those from a flat surface (FS) of Aluminum. SWs from FS and PSS obeyed Taylor's solution for spherical and planar nature, respectively. The velocity of SF from 1D PSS had a twofold increase compared to the FS. This was further enhanced for structures whose periodicity is of the order of excitation wavelength. Variation of SF properties with varying periodicity over a range of 3.3 μm to 0.55 μm has the potential to tailor shockwaves of required parameters. The work is supported by Defence Research and Developement Organization, India through Grants-in-Aid Program. The periodic surfaces were procured with financial support from BRFST project No. NFP-MAT-A12-04.

  10. Influence of plasma shock wave on the morphology of laser drilling in different environments

    Science.gov (United States)

    Zhai, Zhaoyang; Wang, Wenjun; Mei, Xuesong; Wang, Kedian; Yang, Huizhu

    2017-05-01

    Nanosecond pulse laser was used to study nickel-based alloy drilling and compare processing results of microholes in air environment and water environment. Through analysis and comparison, it's found that environmental medium had obvious influence on morphology of laser drilling. High-speed camera was used to shoot plasma morphology during laser drilling process, theoretical formula was used to calculate boundary dimension of plasma and shock wave velocity, and finally parameters were substituted into computational fluid dynamics simulation software to obtain solutions. Obtained analysis results could intuitively explain different morphological features and forming reasons between laser drilling in air environment and water environment in the experiment from angle of plasma shock waves. By comparing simulation results and experimental results, it could help to get an understanding of formation mechanism of microhole morphology, thus providing basis for further improving process optimization of laser drilling quality.

  11. Support minimized inversion of acoustic and elastic wave scattering

    International Nuclear Information System (INIS)

    Safaeinili, A.

    1994-01-01

    This report discusses the following topics on support minimized inversion of acoustic and elastic wave scattering: Minimum support inversion; forward modelling of elastodynamic wave scattering; minimum support linearized acoustic inversion; support minimized nonlinear acoustic inversion without absolute phase; and support minimized nonlinear elastic inversion

  12. Quantitative evaluation of the mechanical strength of titanium/composite bonding using laser-generated shock waves

    Science.gov (United States)

    Ducousso, M.; Bardy, S.; Rouchausse, Y.; Bergara, T.; Jenson, F.; Berthe, L.; Videau, L.; Cuvillier, N.

    2018-03-01

    Intense acoustic shock waves were applied to evaluate the mechanical strength of structural epoxy bonds between a TA6V4 titanium alloy and a 3D woven carbon/epoxy composite material. Two bond types with different mechanical strengths were obtained from two different adhesive reticulations, at 50% and 90% of conversion, resulting in longitudinal static strengths of 10 and 39 MPa and transverse strengths of 15 and 35 MPa, respectively. The GPa shock waves were generated using ns-scale intense laser pulses and reaction principles to a confined plasma expansion. Simulations taking into account the laser-matter interaction, plasma relaxation, and non-linear shock wave propagation were conducted to aid interpretation of the experiments. Good correlations were obtained between the experiments and the simulation and between different measurement methods of the mechanical strength (normalized tests vs laser-generated shock waves). Such results open the door toward certification of structural bonding.

  13. Development and testing of pulsed and rotating detonation combustors

    Science.gov (United States)

    St. George, Andrew C.

    Detonation is a self-sustaining, supersonic, shock-driven, exothermic reaction. Detonation combustion can theoretically provide significant improvements in thermodynamic efficiency over constant pressure combustion when incorporated into existing cycles. To harness this potential performance benefit, countless studies have worked to develop detonation combustors and integrate these devices into existing systems. This dissertation consists of a series of investigations on two types of detonation combustors: the pulse detonation combustor (PDC) and the rotating detonation combustor (RDC). In the first two investigations, an array of air-breathing PDCs is integrated with an axial power turbine. The system is initially operated with steady and pulsed cold air flow to determine the effect of pulsed flow on turbine performance. Various averaging approaches are employed to calculate turbine efficiency, but only flow-weighted (e.g., mass or work averaging) definitions have physical significance. Pulsed flow turbine efficiency is comparable to steady flow efficiency at high corrected flow rates and low rotor speeds. At these conditions, the pulse duty cycle expands and the variation of the rotor incidence angle is constrained to a favorable range. The system is operated with pulsed detonating flow to determine the effect of frequency, fill fraction, and rotor speed on turbine performance. For some conditions, output power exceeds the maximum attainable value from steady constant pressure combustion due to a significant increase in available power from the detonation products. However, the turbine component efficiency estimated from classical thermodynamic analysis is four times lower than the steady design point efficiency. Analysis of blade angles shows a significant penalty due to the detonation, fill, and purge processes simultaneously imposed on the rotor. The latter six investigations focus on fundamental research of the RDC concept. A specially-tailored RDC data

  14. Modeling deflagration waves out of hot spots

    Science.gov (United States)

    Partom, Yehuda

    2017-01-01

    It is widely accepted that shock initiation and detonation of heterogeneous explosives comes about by a two-step process known as ignition and growth. In the first step a shock sweeping through an explosive cell (control volume) creates hot spots that become ignition sites. In the second step, deflagration waves (or burn waves) propagate out of those hot spots and transform the reactant in the cell into reaction products. The macroscopic (or average) reaction rate of the reactant in the cell depends on the speed of those deflagration waves and on the average distance between neighboring hot spots. Here we simulate the propagation of deflagration waves out of hot spots on the mesoscale in axial symmetry using a 2D hydrocode, to which we add heat conduction and bulk reaction. The propagation speed of the deflagration waves may depend on both pressure and temperature. It depends on pressure for quasistatic loading near ambient temperature, and on temperature at high temperatures resulting from shock loading. From the simulation we obtain deflagration fronts emanating out of the hot spots. For 8 to 13 GPa shocks, the emanating fronts propagate as deflagration waves to consume the explosive between hot spots. For higher shock levels deflagration waves may interact with the sweeping shock to become detonation waves on the mesoscale. From the simulation results we extract average deflagration wave speeds.

  15. Detonation Synthesis of Alpha-Variant Silicon Carbide

    Science.gov (United States)

    Langenderfer, Martin; Johnson, Catherine; Fahrenholtz, William; Mochalin, Vadym

    2017-06-01

    A recent research study has been undertaken to develop facilities for conducting detonation synthesis of nanomaterials. This process involves a familiar technique that has been utilized for the industrial synthesis of nanodiamonds. Developments through this study have allowed for experimentation with the concept of modifying explosive compositions to induce synthesis of new nanomaterials. Initial experimentation has been conducted with the end goal being synthesis of alpha variant silicon carbide (α-SiC) in the nano-scale. The α-SiC that can be produced through detonation synthesis methods is critical to the ceramics industry because of a number of unique properties of the material. Conventional synthesis of α-SiC results in formation of crystals greater than 100 nm in diameter, outside nano-scale. It has been theorized that the high temperature and pressure of an explosive detonation can be used for the formation of α-SiC in the sub 100 nm range. This paper will discuss in detail the process development for detonation nanomaterial synthesis facilities, optimization of explosive charge parameters to maximize nanomaterial yield, and introduction of silicon to the detonation reaction environment to achieve first synthesis of nano-sized alpha variant silicon carbide.

  16. Supersonic propagation of ionization waves in an underdense, laser-produced plasma

    International Nuclear Information System (INIS)

    Constantin, C.; Back, C.A.; Fournier, K.B.; Gregori, G.; Landen, O.L.; Glenzer, S.H.; Dewald, E.L.; Miller, M.C.

    2005-01-01

    A laser-driven supersonic ionization wave propagating through a millimeter-scale plasma of subcritical density up to 2-3 keV electron temperatures was observed. Propagation velocities initially ten times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a two-dimensional radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat-wave propagation

  17. Temporal and spatial dynamics of laser-induced aluminum plasma in argon background at atmospheric pressure: Interplay with the ambient gas

    International Nuclear Information System (INIS)

    Ma, Q.L.; Motto-Ros, V.; Lei, W.Q.; Boueri, M.; Bai, X.S.; Zheng, L.J.; Zeng, H.P.; Yu, J.

    2010-01-01

    Laser ablation in background gas implies supplementary complexities with respect to what happens in the vacuum. It is however essential to understand in detail the involved mechanisms for a number of applications requiring the ablation to be performed in an ambient gas at relative high pressure, such as pulsed-laser deposition, or laser-induced breakdown spectroscopy. In this paper, the expansion of a vapor plume ablated from an aluminum target into an argon gas at atmospheric pressure is experimentally investigated using time- and space-resolved emission spectroscopy. The obtained results provide a detailed description of the interplay between the vapor and the gas. The electron density, the temperature and the number densities (and therefore the partial pressures) of aluminum vapor and argon gas have been measured in and surrounding the vapor plume. Our observations show a confinement of the vapor plume by the gas, which is expected as predicted by the usual hydrodynamics models. The result is a plasma core with quite uniform distributions in electron density, temperature and number densities. Such plasma core presents an ideal emission source for spectroscopic applications. It is however evidenced by our observations that a large amount of argon is mixed into the aluminum plume in the plasma core, which invalidates in the experimental conditions that we used, the hydrodynamic 'piston' model where the background gas is pushed out by the shock wave surrounding the vapor plume. Instead, other mechanisms such as laser-supported detonation wave should play important roles in the early stage of the expansion of the plasma for the determination of its morphology at longer delays.

  18. Pulse Detonation Physiochemical and Exhaust Relaxation Processes

    Science.gov (United States)

    2006-05-01

    based on total time to detonation and detonation percentage. Nomenclature A = Arrehenius Constant Ea = Activation Energy Ecrit = Critical...the precision uncertainties vary for each data point. Therefore, the total experimental uncertainty will vary by data point. A comprehensive bias

  19. INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-05-01

    Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

  20. Measurements of the parametric decay of CO2 laser radiation into plasma waves at quarter critical density using ruby laser Thomson scattering

    International Nuclear Information System (INIS)

    Schuss, J.J.; Chu, T.K.; Johnson, L.C.

    1977-11-01

    We report the results of small-angle ruby laser Thomson scattering measurements of the parametric excitation of plasma waves by CO 2 laser radiation at quarter-critical density in a laser-heated gas target plasma. From supplementary data obtained from interferometry and large-angle ruby laser scattering we infer that the threshold conditions for a convective decay are satisfied

  1. Measurement of the development and evolution of shock waves in a laser-induced gas breakdown plasma

    International Nuclear Information System (INIS)

    Chu, T.K.; Johnson, L.C.

    1975-01-01

    Space- and time-resolved interferometric measurements of electron density in CO 2 -laser produced plasmas in helium or hydrogen are made near the laser focal spot. Immediately after breakdown, a rapidly growing region of approximately uniform plasma density appears at the focal spot. After a few tens of nanoseconds, shock waves are formed, propagating both transverse and parallel to the incident laser beam direction. Behind the transverse propagating shock is an on-axis density minimum, which results in laser-beam self-trapping. The shock wave propagating toward the focusing lens effectively shields the interior plasma from the incident beam because the lower plasma temperature and higher plasma density in the shock allow strong absorption of the incident beam energy. By arranging the laser radiation-plasma interaction to begin at a plasma-vacuum interface at the exit of a free-expansion jet, this backward propagating shock wave is eliminated, thus permitting efficient energy deposition in the plasma interior

  2. The numerical simulation of Lamb wave propagation in laser welding of stainless steel

    Science.gov (United States)

    Zhang, Bo; Liu, Fang; Liu, Chang; Li, Jingming; Zhang, Baojun; Zhou, Qingxiang; Han, Xiaohui; Zhao, Yang

    2017-12-01

    In order to explore the Lamb wave propagation in laser welding of stainless steel, the numerical simulation is used to show the feature of Lamb wave. In this paper, according to Lamb dispersion equation, excites the Lamb wave on the edge of thin stainless steel plate, and presents the reflection coefficient for quantizing the Lamb wave energy, the results show that the reflection coefficient is increased with the welding width increasing,

  3. Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

    International Nuclear Information System (INIS)

    Wang, Hsin; Porter, Wallace D.; Dinwiddie, Ralph Barton

    2017-01-01

    We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.

  4. Theory of weakly nonlinear self-sustained detonations

    KAUST Repository

    Faria, Luiz

    2015-11-03

    We propose a theory of weakly nonlinear multidimensional self-sustained detonations based on asymptotic analysis of the reactive compressible Navier-Stokes equations. We show that these equations can be reduced to a model consisting of a forced unsteady small-disturbance transonic equation and a rate equation for the heat release. In one spatial dimension, the model simplifies to a forced Burgers equation. Through analysis, numerical calculations and comparison with the reactive Euler equations, the model is demonstrated to capture such essential dynamical characteristics of detonations as the steady-state structure, the linear stability spectrum, the period-doubling sequence of bifurcations and chaos in one-dimensional detonations and cellular structures in multidimensional detonations.

  5. Welding induced residual stress evaluation using laser-generated Rayleigh waves

    Science.gov (United States)

    Ye, Chong; Zhou, Yuanlai; Reddy, Vishnu V. B.; Mebane, Aaron; Ume, I. Charles

    2018-04-01

    Welding induced residual stress could affect the dimensional stability, fatigue life, and chemical resistance of the weld joints. Ultrasonic method serves as an important non-destructive tool for the residual stress evaluation due to its easy implementation, low cost and wide application to different materials. Residual stress would result in the ultrasonic wave velocity variation, which is the so called acoustoelastic effect. In this paper, Laser/EMAT ultrasonic technique was proposed to experimentally study the relative velocity variation ΔV/V of Rayleigh wave, which has the potential to evaluate surface/subsurface longitudinal residual stress developed during the Gas Metal Arc Welding process. Broad band ultrasonic waves were excited by pulsed Q-Switched Nd: YAG laser. An electromagnetic acoustic transducer (EMAT) attached to the welded plates was used to capture the Rayleigh wave signals propagating along the weld seam direction. Different time of flight measurements were conducted by varying the distance between the weld seam and Rayleigh wave propagating path in the range of 0 to 45 mm. The maximum relative velocity difference was found on the weld seam. With the increasing distance away from the weld seam, the relative velocity difference sharply decreased to negative value. With further increase in distance, the relative velocity difference slowly increased and approached zero. The distribution of relative velocity variations indicates that tensile stress appears in the melted zone as it becomes compressive near the heat-affected zone.

  6. Pump depletion limited evolution of the relativistic plasma wave-front in a forced laser-wakefield accelerator

    International Nuclear Information System (INIS)

    Fang, F; Clayton, C E; Marsh, K A; Pak, A E; Ralph, J E; Joshi, C; Lopes, N C

    2009-01-01

    In a forced laser-wakefield accelerator experiment (Malka et al 2002 Science 298 1596) where the length of the pump laser pulse is a few plasma periods long, the leading edge of the laser pulse undergoes frequency downshifting and head erosion as the laser energy is transferred to the wake. Therefore, after some propagation distance, the group velocity of the leading edge of the pump pulse-and thus of the driven electron plasma wave-will slow down. This can have implications for the dephasing length of the accelerated electrons and therefore needs to be understood experimentally. We have carried out an experimental investigation where we have measured the velocity v f of the 'wave-front' of the plasma wave driven by a nominally 50 fs (full width half maximum), intense (a 0 ≅ 1), 0.815 μm laser pulse. To determine the speed of the wave front, time- and space-resolved refractometry, interferometry and Thomson scattering were used. Although a laser pulse propagating through a relatively low-density plasma (n e = 1.3 x 10 19 cm -3 ) showed no measurable changes in v f over 1.3 mm (and no accelerated electrons), a high-density plasma (n e = 5 x 10 19 cm -3 ) generated accelerated electrons and showed a continuous change in v f as the laser pulse propagated through the plasma. Possible causes and consequences of the observed v f evolution are discussed.

  7. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode.

    Science.gov (United States)

    Chang, Feng-Yu; Tsai, Meng-Tsan; Wang, Zu-Yi; Chi, Chun-Kai; Lee, Cheng-Kuang; Yang, Chih-Hsun; Chan, Ming-Che; Lee, Ya-Ju

    2015-11-16

    Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

  8. Experimental realization of millimeter-wave amplification by a sheet beam free electron laser

    International Nuclear Information System (INIS)

    Zhang, Z.; Destler, W.W.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Rodgers, J.; Cheng, S.

    1994-01-01

    We report an observation of millimeter-wave (94 GHz) amplification in a sheet beam, short period, planar wiggler, free electron laser amplifier. The observed gain is about 5 dB for a 530 keV, 4 A beam through a 54 cm wiggler. Wave energy absorption was also observed when the beam energy is off-resonance. Experimental results are in good agreement with numerical simulation. This amplifier configuration has potential for producing equally high output power but at relatively low voltage compared with longer period free electron lasers

  9. Theory of the corrugation instability of a piston-driven shock wave.

    Science.gov (United States)

    Bates, J W

    2015-01-01

    We analyze the two-dimensional stability of a shock wave driven by a steadily moving corrugated piston in an inviscid fluid with an arbitrary equation of state. For h≤-1 or h>h(c), where h is the D'yakov parameter and h(c) is the Kontorovich limit, we find that small perturbations on the shock front are unstable and grow--at first quadratically and later linearly--with time. Such instabilities are associated with nonequilibrium fluid states and imply a nonunique solution to the hydrodynamic equations. The above criteria are consistent with instability limits observed in shock-tube experiments involving ionizing and dissociating gases and may have important implications for driven shocks in laser-fusion, astrophysical, and/or detonation studies.

  10. Experimental and numerical investigations of shock and shear wave propagation induced by femtosecond laser irradiation in epoxy resins

    International Nuclear Information System (INIS)

    Ecault, Romain; Touchard, Fabienne; Boustie, Michel; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Voillaume, Hubert

    2015-01-01

    In this work, original shock experiments are presented. Laser-induced shock and shear wave propagations have been observed in an epoxy resin, in the case of femtosecond laser irradiation. A specific time-resolved shadowgraphy setup has been developed using the photoelasticimetry principle to enhance the shear wave observation. Shear waves have been observed in epoxy resin after laser irradiation. Their propagation has been quantified in comparison with the main shock propagation. A discussion, hinging on numerical results, is finally given to improve understanding of the phenomenon. (paper)

  11. Supersonic Heat Wave Propagation in Laser-Produced Underdense Plasma for Efficient X-Ray Generation

    International Nuclear Information System (INIS)

    Tanabe, M.; Nishimura, H.; Fujioka, S.; Nagai, K.; Iwamae, A.; Ohnishi, N.; Fournier, K.B.; Girard, F.; Primout, M.; Villette, B.; Tobin, M.; Mima, K.

    2008-01-01

    We have observed supersonic heat wave propagation in a low-density aerogel target (ρ ∼ 3.2 mg/cc) irradiated at the intensity of 4 x 10 14 W/cm 2 . The heat wave propagation was measured with a time-resolved x-ray imaging diagnostics, and the results were compared with simulations made with the two-dimensional radiation-hydrodynamic code, RAICHO. Propagation velocity of the ionization front gradually decreased as the wave propagates into the target. The reason of decrease is due to increase of laser absorption region as the front propagates and interplay of hydrodynamic motion and reflection of laser propagation. These features are well reported with the simulation

  12. Reflection and diffraction of atomic de Broglie waves by evanescent laser waves. Bare-state method

    International Nuclear Information System (INIS)

    Feng, Xiaoping; Witte, N.S.; Hollenberg, C.L.; Opat, G.

    1994-01-01

    Two methods are presented for the investigation of the reflection and diffraction of atoms by gratings formed either by standing or travelling evanescent laser waves. Both methods use the bare-state rather than dressed-state picture. One method is based on the Born series, whereas the other is based on the Laplace transformation of the coupled differential equations. The two methods yield the same theoretical expressions for the reflected and diffracted atomic waves in the whole space including the interaction and the asymptotic regions. 1 ref., 1 fig

  13. Excitation of Accelerating Plasma Waves by Counter-propagating Laser Beams

    International Nuclear Information System (INIS)

    Gennady Shvets; Nathaniel J. Fisch; Alexander Pukhov

    2001-01-01

    Generation of accelerating plasma waves using two counter-propagating laser beams is considered. Colliding-beam accelerator requires two laser pulses: the long pump and the short timing beam. We emphasize the similarities and differences between the conventional laser wakefield accelerator and the colliding-beam accelerator (CBA). The highly nonlinear nature of the wake excitation is explained using both nonlinear optics and plasma physics concepts. Two regimes of CBA are considered: (i) the short-pulse regime, where the timing beam is shorter than the plasma period, and (ii) the parametric excitation regime, where the timing beam is longer than the plasma period. Possible future experiments are also outlined

  14. Detonability of containment building atmospheres during core-meltdown accidents

    International Nuclear Information System (INIS)

    Jaung, R.; Berlad, L.; Pratt, W.

    1983-01-01

    During Core-Meltdown Accidents in Light Water Reactors, significant quantities of combustible gases could be released to the containment building. The highest possible peak pressure fields that may occur through combustion processes are associated with detonation phenomena. Accordingly, it is necessary to understand and identify the possible ways in which detonations may or may not occur. Although no comprehensive theory of detonation is currently available, there are useful guidelines, which can be derived from current theoretical concepts and the body of experimental data. This paper examines these guidelines and indicates how they may be used to evaluate the possible occurrence of detonation-related combustion processes. In particular, this study identifies three features that an initiation source must achieve if it is to ultimately result in a stable detonation. One of these features requires post-shock initial conditions that lead to very short ignition delays. This concept is used to examine the possibility of achieving quasi-steady detonation phenomena in nuclear reactor containment buildings during postulated core-melt accidents

  15. Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength

    OpenAIRE

    Savochkin, I. V.; J?ckl, M.; Belotelov, V. I.; Akimov, I. A.; Kozhaev, M. A.; Sylgacheva, D. A.; Chernov, A. I.; Shaposhnikov, A. N.; Prokopov, A. R.; Berzhansky, V. N.; Yakovlev, D. R.; Zvezdin, A. K.; Bayer, M.

    2017-01-01

    Currently spin waves are considered for computation and data processing as an alternative to charge currents. Generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, focused laser spot works as a point source for spin waves and allows for directional control of spin waves and switching between their different types. For further progress in this direction it is important to manipulate with ...

  16. Qualitative and quantitative analysis of detonation products

    International Nuclear Information System (INIS)

    Xie Yun

    2005-01-01

    Different sampling and different injection method were used during analyzing unknown detonation products in a obturator. The sample analyzed by gas chromatography and gas chromatography/mass spectrum. Qualitative analysis was used with CO, NO, C 2 H 2 , C 6 H 6 and so on, qualitative analysis was used with C 3 H 5 N, C 10 H 10 , C 8 H 8 N 2 and so on. The method used in the article is feasible. The results show that the component of detonation in the study is negative oxygen balance, there were many pollutants in the detonation products. (authors)

  17. Investigation of hydrogen-deflagration/-detonation

    International Nuclear Information System (INIS)

    Breitung, W.; Redlinger, R.; Werle, H.; Moeschke, M.

    1992-01-01

    The static and dynamic loads of a PWR-containment from hydrogen combustion are investigated theoretically and experimentally. The primary goal is the determination of realistic, not too conservative, upper bounds. The load data are needed to define design requirements for a core-melt resistant containment structure. The following work was performed in 1991: balloon tests; design of a medium scale detonation tube; development of a 1D detonation code; analytical study with SNL/Albuquerque, USA and documentation and presentation of results. (orig./DG)

  18. Transmission characteristics of the kinematics of the laser-plasma shock wave in air in compton scattering

    International Nuclear Information System (INIS)

    Hao Dongshan; Xie Hongjun

    2006-01-01

    By comparing the kinematical equation of a shock wave in free air, the study of transmission characteristics of the laser plasma shock wave in Compton scattering is presented. The results show that the attenuation course of the kinematics of he laser plasma shock wave is related not only with the explosion fountainhead and the characteristics of the explosion course, total energy release, air elastic, but also with multi-photon nonlinear Compton scattering. Because of the scattering the initial radius of the shock wave increases, the attenuation course shortens, the energy metastasis efficiency rises. The results of the numerical analysis and the actual values of the shock waves in air by a way intense explosion are very tallying. (authors)

  19. Efficacy observation on multiple wave length laser for diabetic retinopathy and central retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    Tao Tian

    2014-07-01

    Full Text Available AIM:To observe the efficacy of the multiple wave length laser in treating diabetic retinopathy combined with central retinal vein occlusion. METHODS:Totally 95 cases(100 eyeswith diabetic retinopathy combined with central retinal vein occlusion were treated by multiple wave length laser. Krypton yellow laser was used for macular edema in focal photocoagulation and diffuse photocoagulation. For peripheral retina, krypton green or krypton red laser were used. Visual acuity, slit-lamp biomicroscopy, ophthalmoscopy and fundus fluorescein angiography were performed preoperatively and postoperatively. The patients were followed up for 12 to 48wk. In this study, change in visual acuity and macular edema were observed in both groups, and statistical analysis was performed. RESULTS:The effective rate was 61.2% in diffuse macular edema group and 86.3% in focal macular edema group. The general effective rate of later was higher than the former, while the treatment effect had significant statistical difference(PCONCLUSION: Multiple wave length laser is an effective and safe way to treat diabetic macular edema of diabetic retinopathy combined with central retinal vein occlusion,which is worth widely applying in clinical practice.

  20. Pump depletion limited evolution of the relativistic plasma wave-front in a forced laser-wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Fang, F; Clayton, C E; Marsh, K A; Pak, A E; Ralph, J E; Joshi, C [Department of Electrical Engineering, University of California, Los Angeles, CA 90095 (United States); Lopes, N C [Grupo de Lasers e Plasmas, Instituto Superior Tecnico, Lisbon (Portugal)], E-mail: cclayton@ucla.edu

    2009-02-15

    In a forced laser-wakefield accelerator experiment (Malka et al 2002 Science 298 1596) where the length of the pump laser pulse is a few plasma periods long, the leading edge of the laser pulse undergoes frequency downshifting and head erosion as the laser energy is transferred to the wake. Therefore, after some propagation distance, the group velocity of the leading edge of the pump pulse-and thus of the driven electron plasma wave-will slow down. This can have implications for the dephasing length of the accelerated electrons and therefore needs to be understood experimentally. We have carried out an experimental investigation where we have measured the velocity v{sub f} of the 'wave-front' of the plasma wave driven by a nominally 50 fs (full width half maximum), intense (a{sub 0} {approx_equal} 1), 0.815 {mu}m laser pulse. To determine the speed of the wave front, time- and space-resolved refractometry, interferometry and Thomson scattering were used. Although a laser pulse propagating through a relatively low-density plasma (n{sub e} = 1.3 x 10{sup 19} cm{sup -3}) showed no measurable changes in v{sub f} over 1.3 mm (and no accelerated electrons), a high-density plasma (n{sub e} = 5 x 10{sup 19} cm{sup -3}) generated accelerated electrons and showed a continuous change in v{sub f} as the laser pulse propagated through the plasma. Possible causes and consequences of the observed v{sub f} evolution are discussed.

  1. Electron plasma waves in CO/sub 2/ laser plasma interactions

    International Nuclear Information System (INIS)

    Baldis, H.A.; Villeneuve, D.M.; Walsh, C.J.

    1984-01-01

    During the past few years, the use of Thomson scattering in CO/sub 2/ laser produced plasmas has permitted the identification and study of electron plasma waves and ion waves, driven by various instabilities in the plasma corona, such as Stimulated Raman Scattering (SRS), two plasmon decay, and Stimulated Brillouin Scattering (SBS). Since these instabilities may coexist in the plasma, the density fluctuations associated with one wave may influence the behaviour of one or more of the other instabilities. The authors discuss the experimental evidence of such effects and, in particular, the consequences of a recent experiment in which the ion waves driven by SBS were observed to adversely affect the production of the electron plasma waves driven by SRS. In that experiment, a strong correlation was observed between the onset of SBS and the disappearance of the electron plasma waves driven by SRS at low densities (n/sub e/ n/sub e/ > 0.05 n/sub c/)

  2. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wenfu; Li, Xingwen, E-mail: xwli@mail.xjtu.edu.cn; Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi 710049 (China)

    2014-08-15

    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.

  3. The Experimental Study about the Effect of Operating Conditions on Multi-tube Pulse Detonation Engine Performance

    Science.gov (United States)

    Kim, Jung-Min; Han, Hyung-Seok; Choi, Jeong-Yeol

    2018-04-01

    This study examines a multi-tube pulse detonation engine (PDE) which has a type of constant volume combustion. We designed and made the multi-tube PDE and then conducted an experiment in various operating frequencies and equivalence ratios. First, experiments with operating frequencies of 40, 80, 120, 160, and 200 Hz resulted in an average thrust and specific impulse 23.14 N and 42.34 s. The next experiment resulted in the equivalence ratio varying from 0.81 to 1.38, which resulted in an average thrust and specific impulse 22.36 N and 40.11 s. The average detonation velocity was 8% lower than that calculated according to C-J theory. The incidence ratios of the detonation wave were stable with the exception of the operating frequency of 200 Hz. However, at 200 Hz, the incidence ratio was less than 50%. We assumed that a low fill fraction occurred for this problem. The thrust of the PDE increased with the operating frequency. However, the thrust increase was at a lower rate than in previous studies, because of a lost thrust output result from the slow response time of the load cell amplifier.

  4. Contribution to the study of detonation initiation by shock in solid explosives (1961); Contribution a l'etude de l'initiation de la detonation par choc dans les explosifs solides (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Fauquignon, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-05-15

    When a shock wave is induced in an explosive, it can initiate chemical reactions which lead more or less rapidly to a stable detonation state. In this study more particular attention was paid to the transition phase, in which has been evaluated the increases in the wave velocity, the pressure, and the electrical conductivity. The influence of the nature of the medium in front of the wave and in contact with the explosive has also been the subject of an experimental study designed to determine the extent to which its nature can be ignored and, subsequently, to characterise the initiation conditions using only the shock intensity induced in the explosive. Finally, the results were generalized for various explosive compositions and led to the development of a possible mechanism for shock initiation. (author) [French] Lorsqu'une onde de choc est induite dans un explosif, elle peut y amorcer des reactions chimiques qui conduisent plus ou moins rapidement a un regime de detonation stable. Dans cette etude, on s'est interesse plus particulierement a la phase transitoire dans laquelle on a evalue l'accroissement de la vitesse d'onde, de la pression et de la conductibilite electrique. L'influence du milieu amont, au contact de l'explosif, a egalement fait l'objet de recherches experimentales de facon a determiner dans quelle mesure on pouvait s'affranchir de sa nature et, par suite, caracteriser les conditions d'initiation par la seule intensite du choc induit dans l'explosif. Enfin, les resultats ont ete generalises a diverses compositions explosives et ont conduit a l'elaboration d'un schema possible du mecanisme de l'initiation par choc. (auteur)

  5. An improved method to experimentally determine temperature and pressure behind laser-induced shock waves at low Mach numbers

    International Nuclear Information System (INIS)

    Hendijanifard, Mohammad; Willis, David A

    2011-01-01

    Laser-matter interactions are frequently studied by measuring the propagation of shock waves caused by the rapid laser-induced material removal. An improved method for calculating the thermo-fluid parameters behind shock waves is introduced in this work. Shock waves in ambient air, induced by pulsed Nd : YAG laser ablation of aluminium films, are measured using a shadowgraph apparatus. Normal shock solutions are applied to experimental data for shock wave positions and used to calculate pressure, temperature, and velocity behind the shock wave. Non-dimensionalizing the pressure and temperature with respect to the ambient values, the dimensionless pressure and temperature are estimated to be as high as 90 and 16, respectively, at a time of 10 ns after the ablation pulse for a laser fluence of F = 14.5 J cm -2 . The results of the normal shock solution and the Taylor-Sedov similarity solution are compared to show that the Taylor-Sedov solution under-predicts pressure when the Mach number of the shock wave is small. At a fluence of 3.1 J cm -2 , the shock wave Mach number is less than 3, and the Taylor-Sedov solution under-predicts the non-dimensional pressure by as much as 45%.

  6. Laser-generated shock wave attenuation aimed at microscale pyrotechnic device design

    Directory of Open Access Journals (Sweden)

    Hyeonju Yu

    2016-05-01

    Full Text Available To meet the rising demand for miniaturizing the pyrotechnic device that consists of donor/acceptor pair separated by a bulkhead or a thin gap, the shock initiation sensitivity in the microscale gap test configuration is investigated. For understanding the shock attenuation within a gap sample (304 stainless steel thickness of 10∼800 μm, the laser-generated shock wave in water confinement is adopted. The shock properties are obtained from the free surface velocity by making use of a velocity interferometer system for any reflector (VISAR. Analytical models for plasma generation in a confined geometry and for evolution and decay of shock waves during the propagation are considered. The shape and amplitude of the laser-driven initial pressure load and its attenuation pattern in the gap are effectively controlled for targeting the microscale propagation distance and subsequent triggering pressure for the acceptor charge. The reported results are important in the precise controlling of the shock strength during the laser initiation of microscale pyrotechnic devices.

  7. Coherent Wave Measurement Buoy Arrays to Support Wave Energy Extraction

    Science.gov (United States)

    Spada, F.; Chang, G.; Jones, C.; Janssen, T. T.; Barney, P.; Roberts, J.

    2016-02-01

    Wave energy is the most abundant form of hydrokinetic energy in the United States and wave energy converters (WECs) are being developed to extract the maximum possible power from the prevailing wave climate. However, maximum wave energy capture is currently limited by the narrow banded frequency response of WECs as well as extended protective shutdown requirements during periods of large waves. These limitations must be overcome in order to maximize energy extraction, thus significantly decreasing the cost of wave energy and making it a viable energy source. Techno-economic studies of several WEC devices have shown significant potential to improve wave energy capture efficiency through operational control strategies that incorporate real-time information about local surface wave motions. Integral Consulting Inc., with ARPA-E support, is partnering with Sandia National Laboratories and Spoondrift LLC to develop a coherent array of wave-measuring devices to relay and enable the prediction of wave-resolved surface dynamics at a WEC location ahead of real time. This capability will provide necessary information to optimize power production of WECs through control strategies, thereby allowing for a single WEC design to perform more effectively across a wide range of wave environments. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000514.

  8. Visual and refractive outcomes of LASIK with the SCHWIND ESIRIS and WaveLight ALLEGRETTO WAVE Eye-q excimer lasers: a prospective, contralateral study.

    Science.gov (United States)

    Mearza, Ali A; Muhtaseb, Mohammed; Aslanides, Ioannis M

    2008-11-01

    To compare the safety, efficacy, and predictability of LASIK with the SCHWIND ESIRIS and WaveLight ALLEGRETTO WAVE Eye-Q excimer laser platforms. This prospective study comprised 44 eyes of 22 consecutive patients who were treated with LASIK using the Moria M2 microkeratome. One eye was treated with the SCHWIND ESIRIS laser and the fellow eye treated with the WaveLight ALLEGRETTO WAVE Eye-Q laser. All eyes operated with the SCHWIND ESIRIS were treated with standard aspheric ablation, whereas the eyes operated with the WaveLight ALLEGRETTO WAVE Eye-Q received treatment with three different ablation types according to the common practice at our clinic. Outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and proximity to target refraction at 6-month follow-up. At 6 months postoperative, mean decimal UCVA was 0.96+/-0.22 (range: 0.3 to 1.2) for ESIRIS eyes and 0.98+/-0.17 (range: 0.6 to 1.2) for ALLEGRETTO eyes (P=.57). Mean postoperative spherical equivalent refraction was -0.02+/-0.28 diopters (D) (range: -0.75 to +0.75 D) for ESIRIS eyes and 0.11+/-0.91 D (range: -1.00 to +3.88 D) for ALLEGRETTO eyes (P=.49). Of the ESIRIS eyes, 20/22 (91%) were within +/-1.00 D of target refraction and 20/22 (91%) were within +/-0.50 D of target refraction. Of the ALLEGRETTO eyes, 20/22 (91%) and 19/22 (86%) were within +/-1.00 D and +/-0.50 D, respectively, of target refraction. No patient lost > or =2 lines of BSCVA in either group. No differences were seen in safety and efficacy outcome parameters between the SCHWIND ESIRIS and WaveLight ALLEGRETTO WAVE Eye-Q excimer lasers when used according to a previously established treatment algorithm at our clinic in the treatment of refractive error.

  9. Resonantly diode-pumped continuous-wave and Q-switched Er:YAG laser at 1645 nm.

    Science.gov (United States)

    Chang, N W H; Simakov, N; Hosken, D J; Munch, J; Ottaway, D J; Veitch, P J

    2010-06-21

    We describe an efficient Er:YAG laser that is resonantly pumped using continuous-wave (CW) laser diodes at 1470 nm. For CW lasing, it emits 6.1 W at 1645 nm with a slope efficiency of 36%, the highest efficiency reported for an Er:YAG laser that is pumped in this manner. In Q-switched operation, the laser produces diffraction-limited pulses with an average power of 2.5 W at 2 kHz PRF. To our knowledge this is the first Q-switched Er:YAG laser resonantly pumped by CW laser diodes.

  10. Influence of standing-wave electric field pattern on the laser damage resistance of HfO sub 2 thin films

    CERN Document Server

    Protopapa, M L; De Tomasi, F; Di Giulio, M; Perrone, M R; Scaglione, S

    2002-01-01

    The standing-wave electric field pattern that forms inside an optical coating as a consequence of laser irradiation is one of the factors influencing the coating laser-induced damage threshold. The influence of the standing-wave electric field profile on the damage resistance to ultraviolet radiation of hafnium dioxide (HfO sub 2) thin films was investigated in this work. To this end, HfO sub 2 thin films of different thicknesses deposited by the electron beam evaporation technique at the same deposition conditions were analyzed. Laser damage thresholds of the samples were measured at 308 nm (XeCl laser) by the photoacoustic beam deflection technique and microscopic inspections. The dependence of the laser damage threshold on the standing-wave electric field pattern was analyzed.

  11. Simulations of pulsating one-dimensional detonations with true fifth order accuracy

    International Nuclear Information System (INIS)

    Henrick, Andrew K.; Aslam, Tariq D.; Powers, Joseph M.

    2006-01-01

    A novel, highly accurate numerical scheme based on shock-fitting coupled with fifth order spatial and temporal discretizations is applied to a classical unsteady detonation problem to generate solutions with unprecedented accuracy. The one-dimensional reactive Euler equations for a calorically perfect mixture of ideal gases whose reaction is described by single-step irreversible Arrhenius kinetics are solved in a series of calculations in which the activation energy is varied. In contrast with nearly all known simulations of this problem, which converge at a rate no greater than first order as the spatial and temporal grid is refined, the present method is shown to converge at a rate consistent with the fifth order accuracy of the spatial and temporal discretization schemes. This high accuracy enables more precise verification of known results and prediction of heretofore unknown phenomena. To five significant figures, the scheme faithfully recovers the stability boundary, growth rates, and wave-numbers predicted by an independent linear stability theory in the stable and weakly unstable regime. As the activation energy is increased, a series of period-doubling events are predicted, and the system undergoes a transition to chaos. Consistent with general theories of non-linear dynamics, the bifurcation points are seen to converge at a rate for which the Feigenbaum constant is 4.66 ± 0.09, in close agreement with the true value of 4.669201... As activation energy is increased further, domains are identified in which the system undergoes a transition from a chaotic state back to one whose limit cycles are characterized by a small number of non-linear oscillatory modes. This result is consistent with behavior of other non-linear dynamical systems, but not typically considered in detonation dynamics. The period and average detonation velocity are calculated for a variety of asymptotically stable limit cycles. The average velocity for such pulsating detonations is found

  12. Simple model for decay of laser generated shock waves

    International Nuclear Information System (INIS)

    Trainor, R.J.

    1980-01-01

    A simple model is derived to calculate the hydrodynamic decay of laser-generated shock waves. Comparison with detailed hydrocode simulations shows good agreement between calculated time evolution of shock pressure, position, and instantaneous pressure profile. Reliability of the model decreases in regions of the target where superthermal-electron preheat effects become comparable to shock effects

  13. Study of laser-driven shock wave propagation in Plexiglas targets

    International Nuclear Information System (INIS)

    Dhareshwar, L.J.; Naik, P.A.; Pant, H.C.; Kaushik, T.C.

    1992-01-01

    An experimental study of laser-driven shock wave propagation in a transparent material such as Plexiglas using a high-speed optical shadowgraphy technique is presented in this paper. A Nd: glass laser was used to produce laser intensity in the range 10 12 -10 14 W/cm 2 on the target. Optical shadowgrams of the propagating shock front were recorded with a second-harmonic (0.53-μm) optical probe beam. Shock pressures were measured at various laser intensities, and the scaling was found to agree with the theoretically predicted value. Shock pressure values have also been obtained from a one-dimensional Lagrangian hydrodynamic simulation, and they match well with experimental results. Shadowgrams of shock fronts produced by nonuniform spatial laser beam irradiation profiles have shown complete smoothing when targets with a thin coating of a material of high atomic number such as gold were used. Shock pressures in such coated targets are also found to be considerably higher compared with those in uncoated targets. (Author)

  14. Crack Detection in Single-Crystalline Silicon Wafer Using Laser Generated Lamb Wave

    Directory of Open Access Journals (Sweden)

    Min-Kyoo Song

    2013-01-01

    Full Text Available In the semiconductor industry, with increasing requirements for high performance, high capacity, high reliability, and compact components, the crack has been one of the most critical issues in accordance with the growing requirement of the wafer-thinning in recent years. Previous researchers presented the crack detection on the silicon wafers with the air-coupled ultrasonic method successfully. However, the high impedance mismatching will be the problem in the industrial field. In this paper, in order to detect the crack, we propose a laser generated Lamb wave method which is not only noncontact, but also reliable for the measurement. The laser-ultrasonic generator and the laser-interferometer are used as a transmitter and a receiver, respectively. We firstly verified the identification of S0 and A0 lamb wave modes and then conducted the crack detection under the thermoelastic regime. The experimental results showed that S0 and A0 modes of lamb wave were clearly generated and detected, and in the case of the crack detection, the estimated crack size by 6 dB drop method was almost equal to the actual crack size. So, the proposed method is expected to make it possible to detect the crack in the silicon wafer in the industrial fields.

  15. Detonation-synthesis nanodiamonds: synthesis, structure, properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Dolmatov, Valerii Yu [Federal State Unitary Enterprise Special Design-Technology Bureau (FSUE SDTB) ' ' Tekhnolog' ' at the St Petersburg State Institute of Technology (Technical University) (Russian Federation)

    2007-04-30

    The review outlines the theoretical foundations and industrial implementations of modern detonation synthesis of nanodiamonds and chemical purification of the nanodiamonds thus obtained. The structure, key properties and promising fields of application of detonation-synthesis nanodiamonds are considered.

  16. Detonation-synthesis nanodiamonds: synthesis, structure, properties and applications

    International Nuclear Information System (INIS)

    Dolmatov, Valerii Yu

    2007-01-01

    The review outlines the theoretical foundations and industrial implementations of modern detonation synthesis of nanodiamonds and chemical purification of the nanodiamonds thus obtained. The structure, key properties and promising fields of application of detonation-synthesis nanodiamonds are considered.

  17. Strong shock wave and areal mass oscillations associated with impulsive loading of planar laser targets

    International Nuclear Information System (INIS)

    Velikovich, A.L.; Schmitt, A.J.; Metzler, N.; Gardner, J.H.

    2003-01-01

    When a rippled surface of a planar target is irradiated with a short (subnanosecond) laser pulse, the shock wave launched into the target and the mass distribution of the shocked plasma will oscillate. These oscillations are found to be surprisingly strong compared, for example, to the case when the laser radiation is not turned off but rather keeps pushing the shock wave into the target. Being stronger than the areal mass oscillations due to ablative Richtmyer-Meshkov instability and feedout in planar targets, which have recently been observed at the Naval Research Laboratory (NRL) [Aglitskiy et al., Phys. Plasmas 9, 2264 (2002)], these oscillations should therefore be directly observable with the same diagnostic technique. Irradiation of a target with a short laser pulse represents a particular case of an impulsive loading, a fast release of finite energy in a thin layer near the surface of a target. Renewed interest to the impulsive loading in the area of direct-drive laser fusion is due to the recent proposals of using a short pulse prior to the drive pulse to make the target more resistant to laser imprint and Rayleigh-Taylor growth. Impulsive loading produces a shock wave that propagates into the target and is immediately followed by an expansion wave, which gradually reduces the shock strength. If the irradiated surface is rippled, then, while the shock wave propagates through the target, its modulation amplitude grows, exceeding the initial ripple amplitude by a factor of 2 or more. The oscillating areal mass reaches the peak values that exceed the initial mass modulation amplitude (density times ripple height) by a factor of 5-7 or more, and reverses its phase several times after the laser pulse is over. The oscillatory growth is more pronounced in fluids with higher shock compressibility and is probably related to the Vishniac's instability of a blast wave. Frequency of the oscillations is determined by the speed of sound in the shocked material, and

  18. Nonlinear plasma wave models in 3D fluid simulations of laser-plasma interaction

    Science.gov (United States)

    Chapman, Thomas; Berger, Richard; Arrighi, Bill; Langer, Steve; Banks, Jeffrey; Brunner, Stephan

    2017-10-01

    Simulations of laser-plasma interaction (LPI) in inertial confinement fusion (ICF) conditions require multi-mm spatial scales due to the typical laser beam size and durations of order 100 ps in order for numerical laser reflectivities to converge. To be computationally achievable, these scales necessitate a fluid-like treatment of light and plasma waves with a spatial grid size on the order of the light wave length. Plasma waves experience many nonlinear phenomena not naturally described by a fluid treatment, such as frequency shifts induced by trapping, a nonlinear (typically suppressed) Landau damping, and mode couplings leading to instabilities that can cause the plasma wave to decay rapidly. These processes affect the onset and saturation of stimulated Raman and Brillouin scattering, and are of direct interest to the modeling and prediction of deleterious LPI in ICF. It is not currently computationally feasible to simulate these Debye length-scale phenomena in 3D across experimental scales. Analytically-derived and/or numerically benchmarked models of processes occurring at scales finer than the fluid simulation grid offer a path forward. We demonstrate the impact of a range of kinetic processes on plasma reflectivity via models included in the LPI simulation code pF3D. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  19. Thrust Vectoring of a Continuous Rotating Detonation Engine by Changing the Local Injection Pressure

    International Nuclear Information System (INIS)

    Liu Shi-Jie; Lin Zhi-Yong; Sun Ming-Bo; Liu Wei-Dong

    2011-01-01

    The thrust vectoring ability of a continuous rotating detonation engine is numerically investigated, which is realized via increasing local injection stagnation pressure of half of the simulation domain compared to the other half. Under the homogeneous injection condition, both the flow-field structure and the detonation wave propagation process are analyzed. Due to the same injection condition along the inlet boundary, the outlines of fresh gas zones at different moments are similar to each other. The main flow-field features under thrust vectoring cases are similar to that under the baseline condition. However, due to the heterogeneous injection system, both the height of the fresh gas zone and the pressure value of the fresh gas in the high injection pressure zone are larger than that in the low injection pressure zone. Thus the average pressure in half of the engine is larger than that in the other half and the thrust vectoring adjustment is realized. (fundamental areas of phenomenology(including applications))

  20. Oscillator and system development on the VULCAN glass laser system for the plasma beat-wave program

    International Nuclear Information System (INIS)

    Danson, C.N.

    1990-03-01

    This thesis describes the oscillator and system development on the VULCAN glass laser undertaken in support of the RAL Plasma Beat-wave experiments. This program seeks to evaluate advanced particle acceleration schemes for a new generation of machines for fundamental research in high energy physics. The experiments required two synchronised high power laser pulses of slightly different wavelength. These pulses were generated using two different laser media; Nd:YAG and Nd:YLF operating at 1.064 and 1.053 microns respectively. The first oscillator system developed operated with both lasing media housed in the same laser cavity. Problems with the stability of the optical output required the development of a second system which housed the two lasing media in separate cavities. The second aspect of the development work, described in this thesis, was the reconfiguration of the VULCAN glass laser system to amplify the two laser pulses to power levels of 0.5 TW per pulse. The first scheduled experiment required the two pulses to be propagated co-linearly. To amplify the pulses to the high output powers required two amplifying media to be used which preferentially amplify the two lasing wavelengths. For the later experiments the two laser pulses were amplified in separate amplifier chains which required the design of an efficient beam combiner. (author)

  1. Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

    Science.gov (United States)

    Maxwell, Eric J; Tong, William G

    2016-05-01

    An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2. Copyright © 2016. Published by Elsevier B.V.

  2. Reduced chemical kinetic model of detonation combustion of one- and multi-fuel gaseous mixtures with air

    Science.gov (United States)

    Fomin, P. A.

    2018-03-01

    Two-step approximate models of chemical kinetics of detonation combustion of (i) one hydrocarbon fuel CnHm (for example, methane, propane, cyclohexane etc.) and (ii) multi-fuel gaseous mixtures (∑aiCniHmi) (for example, mixture of methane and propane, synthesis gas, benzene and kerosene) are presented for the first time. The models can be used for any stoichiometry, including fuel/fuels-rich mixtures, when reaction products contain molecules of carbon. Owing to the simplicity and high accuracy, the models can be used in multi-dimensional numerical calculations of detonation waves in corresponding gaseous mixtures. The models are in consistent with the second law of thermodynamics and Le Chatelier's principle. Constants of the models have a clear physical meaning. The models can be used for calculation thermodynamic parameters of the mixture in a state of chemical equilibrium.

  3. Research on Formation Mechanism of Dynamic Response and Residual Stress of Sheet Metal Induced by Laser Shock Wave

    Science.gov (United States)

    Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang

    2018-01-01

    In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the formation mechanism of residual stress induced by laser shock wave. In this paper, the latest research trends on the surface residual stress of laser shock processing technology were elaborated. The main progress of laser shock wave propagation mechanism and dynamic response, laser shock, and surface residual stress were discussed. It is pointed out that the multi-scale characterization of laser and material, surface residual stress and microstructure change is a new hotspot in laser shock strengthening technology.

  4. Generation of hemispherical fast electron waves in the presence of preplasma in ultraintense laser-matter interaction

    Czech Academy of Sciences Publication Activity Database

    Yang, H.X.; Ma, Y.Y.; Xu, H.; Shao, F.Q.; Yu, M.Y.; Yin, Y.; Zhuo, H.B.; Borghesi, Marco

    2013-01-01

    Roč. 31, č. 3 (2013), s. 379-386 ISSN 0263-0346 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : betatron resonance * electron plasma waves * ponderomotive force * preplasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.701, year: 2013

  5. Detonation of Meta-stable Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.

    2008-05-31

    We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

  6. Spatio-temporal evolution of magnetosonic wave in the laser plasma interaction

    International Nuclear Information System (INIS)

    Sharma, R. P.; Singh, Ram Kishor; Sharma, Swati; Tiwary, Prem Pyari; Modi, K. V.; Satsangi, V. R.

    2015-01-01

    This paper presents a theoretical model for the transient response of nonlinear coupling between magnetosonic wave and ion acoustic wave in the overdense plasma. Filamentation of magnetosonic wave has been considered to be responsible for magnetic turbulence during the laser plasma interaction. The ion acoustic wave gets excited due to the ponderomotive force exerted by magnetosonic wave and this ion acoustic wave in turn generates perturbation in the background density in the form of spatial density harmonics. Numerical simulation has been carried out for dimensionless coupled equations of magnetosonic wave and ion acoustic wave; and the results show quite complex localized structures that grow with time. The power spectrum has also been studied which shows that the spectral index follows an approximate scaling of the order of ∼k −2.4 at smaller scales. The data obtained from numerical simulation are used in semi analytical model to better understand the mechanism of nonlinear evolution of magnetosonic wave. The results indicate considerable randomness in the spatial structure of the magnetic field profile which gives sufficient indication of turbulence

  7. Spatio-temporal evolution of magnetosonic wave in the laser plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R. P., E-mail: rpsharma@ces.iitd.ac.in; Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, Swati, E-mail: swati.sharma704@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Tiwary, Prem Pyari, E-mail: prempyari@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Department of Physics and Computer Science, Dayal Bagh Educational Institute(Deemed University), DayalBagh, Agra 282005 (India); Modi, K. V., E-mail: kvmodi.iitd@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Mechanical Engineering Department, Government Engineering College Valsad, Gujarat 396001 (India); Satsangi, V. R. [Department of Physics and Computer Science, Dayal Bagh Educational Institute(Deemed University), DayalBagh, Agra 282005 (India)

    2015-05-15

    This paper presents a theoretical model for the transient response of nonlinear coupling between magnetosonic wave and ion acoustic wave in the overdense plasma. Filamentation of magnetosonic wave has been considered to be responsible for magnetic turbulence during the laser plasma interaction. The ion acoustic wave gets excited due to the ponderomotive force exerted by magnetosonic wave and this ion acoustic wave in turn generates perturbation in the background density in the form of spatial density harmonics. Numerical simulation has been carried out for dimensionless coupled equations of magnetosonic wave and ion acoustic wave; and the results show quite complex localized structures that grow with time. The power spectrum has also been studied which shows that the spectral index follows an approximate scaling of the order of ∼k{sup −2.4} at smaller scales. The data obtained from numerical simulation are used in semi analytical model to better understand the mechanism of nonlinear evolution of magnetosonic wave. The results indicate considerable randomness in the spatial structure of the magnetic field profile which gives sufficient indication of turbulence.

  8. Research on design and firing performance of Si-based detonator

    Directory of Open Access Journals (Sweden)

    Rui-zhen Xie

    2014-03-01

    Full Text Available For the chip integration of MEMS (micro-electromechanical system safety and arming device, a miniature detonator needs to be developed to reduce the weight and volume of explosive train. A Si-based micro-detonator is designed and fabricated, which meets the requirement of MEMS safety and arming device. The firing sensitivity of micro-detonator is tested according to GJB/z377A-94 sensitivity test methods: Langlie. The function time of micro-detonator is measured using wire probe and photoelectric transducer. The result shows the average firing voltage is 6.4 V when the discharge capacitance of firing electro-circuit is 33 μF. And the average function time is 5.48 μs. The firing energy actually utilized by Si-based micro-detonator is explored.

  9. Thermal wave propagation in the pulsed laser irradiation of media with thermal memory

    International Nuclear Information System (INIS)

    Galovic, S.; Kostoski, D.; Stamboliev, G.; Suljovrujic, E.

    2002-01-01

    Complete text of publication follows. If a sample is exposed to the influence of laser radiation part of its energy is absorbed and converted in heat. The heat generated in this way is transferred through the sample as heat waves, resulting in various effects (so called photothermal effects). A large number of nondestructive diagnostic methods are based on recording of these effects. It is necessary to create a good model in order to understand and correctly describe the measured results of heat transfer in different media. In a certain number of materials and structures, such as complex biological materials, polymers, metals excited by very short laser pulses etc., the property of thermal memory has been experimentally observed. Starting with the hyperbolic equation that describes heat transfer processes of such media, in this paper has been developed a model of laser-excited heat waves propagation in order to enable application of photothermal techniques in characterization of these media. The cases of optically opaque and transparent samples are considered. The influence of various backings on photothermal waves has also been analyzed. The results are compared to the previous models

  10. Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength.

    Science.gov (United States)

    Savochkin, I V; Jäckl, M; Belotelov, V I; Akimov, I A; Kozhaev, M A; Sylgacheva, D A; Chernov, A I; Shaposhnikov, A N; Prokopov, A R; Berzhansky, V N; Yakovlev, D R; Zvezdin, A K; Bayer, M

    2017-07-18

    Currently spin waves are considered for computation and data processing as an alternative to charge currents. Generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, focused laser spot works as a point source for spin waves and allows for directional control of spin waves and switching between their different types. For further progress in this direction it is important to manipulate with the spectrum of the optically generated spin waves. Here we tackle this problem by launching spin waves by a sequence of femtosecond laser pulses with pulse interval much shorter than the relaxation time of the magnetization oscillations. This leads to the cumulative phenomenon and allows us to generate magnons in a specific narrow range of wavenumbers. The wavelength of spin waves can be tuned from 15 μm to hundreds of microns by sweeping the external magnetic field by only 10 Oe or by slight variation of the pulse repetition rate. Our findings expand the capabilities of the optical spin pump-probe technique and provide a new method for the spin wave generation and control.

  11. Laser biostimulation therapy planning supported by imaging

    Science.gov (United States)

    Mester, Adam R.

    2018-04-01

    Ultrasonography and MR imaging can help to identify the area and depth of different lesions, like injury, overuse, inflammation, degenerative diseases. The appropriate power density, sufficient dose and direction of the laser treatment can be optimally estimated. If required minimum 5 mW photon density and required optimal energy dose: 2-4 Joule/cm2 wouldn't arrive into the depth of the target volume - additional techniques can help: slight compression of soft tissues can decrease the tissue thickness or multiple laser diodes can be used. In case of multiple diode clusters light scattering results deeper penetration. Another method to increase the penetration depth is a second pulsation (in kHz range) of laser light. (So called continuous wave laser itself has inherent THz pulsation by temporal coherence). Third solution of higher light intensity in the target volume is the multi-gate technique: from different angles the same joint can be reached based on imaging findings. Recent developments is ultrasonography: elastosonography and tissue harmonic imaging with contrast material offer optimal therapy planning. While MRI is too expensive modality for laser planning images can be optimally used if a diagnostic MRI already was done. Usual DICOM images offer "postprocessing" measurements in mm range.

  12. Simulation of hydrogen deflagration and detonation in a BWR reactor building

    International Nuclear Information System (INIS)

    Manninen, M.; Silde, A.; Lindholm, I.; Huhtanen, R.; Sjoevall, H.

    2002-01-01

    A systematic study was carried out to investigate the hydrogen behaviour in a BWR reactor building during a severe accident. BWR core contains a large amount of Zircaloy and the containment is relatively small. Because containment leakage cannot be totally excluded, hydrogen can build up in the reactor building, where the atmosphere is normal air. The objective of the work was to investigate, whether hydrogen can form flammable and detonable mixtures in the reactor building, evaluate the possibility of onset of detonation and assess the pressure loads under detonation conditions. The safety concern is, whether the hydrogen in the reactor building can detonate and whether the external detonation can jeopardize the containment integrity. The analysis indicated that the possibility of flame acceleration and deflagration-to-detonation transition (DDT) in the reactor building could not be ruled out in case of a 20 mm 2 leakage from the containment. The detonation analyses indicated that maximum pressure spike of about 7 MPa was observed in the reactor building room selected for the analysis

  13. Comparison of photosensitivity in germanium doped silica fibers using 244 nm and 266 nm continuous wave lasers

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo; Varming, Poul; Liu, B.

    2001-01-01

    Diode pumped continuous-wave UV lasers offer an interesting alternative to frequency doubled argon-ion lasers. We report the first photosensitivity comparison using these lasers on deuterium loaded standard telecommunication fibers and unloaded experimental fibers....

  14. Streak-photographic investigation of shock wave emission after laser-induced plasma formation in water

    Science.gov (United States)

    Noack, Joachim; Vogel, Alfred

    1995-05-01

    The shock wave emission after dielectric breakdown in water was investigated to assess potential shock wave effects in plasma mediated tissue ablation and intraocular photodisruption. Of particular interest was the dependence of shock wave pressure as a function of distance from the plasma for different laser pulse energies. We have generated plasmas in water with a Nd:YAG laser system delivering pulses of 6 ns duration. The pulses, with energies between 0.4 and 36 mJ (approximately equals 180 times threshold), were focused into a cuvette containing distilled water. The shock wave was visualized with streak photography combined with a schlieren technique. An important advantage of this technique is that the shock position as a function of time can directly be obtained from a single streak and hence a single event. Other methods (e.g. flash photography or passage time measurements between fixed locations) in contrast rely on reproducible events. Using the shock wave speed obtained from the streak images, shock wave peak pressures were calculated providing detailed information on the propagation of the shock. The shock peak pressure as a function of distance r from the optical axis was found to decrease faster than 1/r2 in regions up to distances of 100-150 micrometers . For larger distances it was found to be roughly proportional to 1/r. The scaling law for maximum shock pressure p, at a given distance was found to be proportional to the square root of the laser pulse energy E for distances of 50-200 micrometers from the optical axis.

  15. Measurements of millimeter wave radar transmission and backscatter during dusty infrared test 2, dirt 2

    Science.gov (United States)

    Petito, F. C.; Wentworth, E. W.

    1980-05-01

    Recently there has been much interest expressed to determine the ability of millimeter wave radar to perform target acquisition during degraded visibility conditions. In this regard, one of the primary issues of concern has been the potential of high-explosive artillery barrages to obscure the battlefield from millimeter wave radar systems. To address this issue 95 GHz millimeter wave radar measurements were conducted during the Dusty Infrared Test 2 (DIRT 2). This test was held at White Sands Missile Range, NM, 18-28 July 1979. Millimeter wave transmission and backscatter measurements were performed during singular live firings and static detonations of 155 mm and 105 mm high-explosive artillery rounds in addition to static detonations of C-4 explosives. A brief description of the millimeter wave portion of the test and instrumentation is given. The data along with some preliminary conclusions are presented.

  16. Axisymmetric Numerical Modeling of Pulse Detonation Rocket Engines

    Science.gov (United States)

    Morris, Christopher I.

    2005-01-01

    Pulse detonation rocket engines (PDREs) have generated research interest in recent years as a chemical propulsion system potentially offering improved performance and reduced complexity compared to conventional rocket engines. The detonative mode of combustion employed by these devices offers a thermodynamic advantage over the constant-pressure deflagrative combustion mode used in conventional rocket engines and gas turbines. However, while this theoretical advantage has spurred considerable interest in building PDRE devices, the unsteady blowdown process intrinsic to the PDRE has made realistic estimates of the actual propulsive performance problematic. The recent review article by Kailasanath highlights some of the progress that has been made in comparing the available experimental measurements with analytical and numerical models. In recent work by the author, a quasi-one-dimensional, finite rate chemistry CFD model was utilized to study the gasdynamics and performance characteristics of PDREs over a range of blowdown pressure ratios from 1-1000. Models of this type are computationally inexpensive, and enable first-order parametric studies of the effect of several nozzle and extension geometries on PDRE performance over a wide range of conditions. However, the quasi-one-dimensional approach is limited in that it cannot properly capture the multidimensional blast wave and flow expansion downstream of the PDRE, nor can it resolve nozzle flow separation if present. Moreover, the previous work was limited to single-pulse calculations. In this paper, an axisymmetric finite rate chemistry model is described and utilized to study these issues in greater detail. Example Mach number contour plots showing the multidimensional blast wave and nozzle exhaust plume are shown. The performance results are compared with the quasi-one-dimensional results from the previous paper. Both Euler and Navier-Stokes solutions are calculated in order to determine the effect of viscous

  17. The masonry behaviour under contact detonation

    Directory of Open Access Journals (Sweden)

    Marin Lupoae

    2017-03-01

    Full Text Available Breaching in masonry wall as a process of quick intervention of special forces in emergency cases, may require the use of explosive charges. In order to maximize the explosive effects on the wall and to minimize the shock wave and fragments propulsion, such breaching systems usually use a water layer which cover the explosive charge. The thickness of the water layer has a significant influence both on the mitigation of unwanted effects and enhancing the demolition effect, but also increases the mass of the system which can have negative consequences on the maneuverability and rapidity of intervention, respectivly. In this respect, the paper under consideration addresses numerical and experimental research on masonry walls to determine the behavior of mortar and brick under contact detonation and to establish an optimal water layer thickness to balance the breaching system requirement related to the mass on the one hand and effects and offered protection on the other hand.

  18. Generation of narrowband elastic waves with a fiber laser and its application to the imaging of defects in a plate.

    Science.gov (United States)

    Hayashi, Takahiro; Ishihara, Ken

    2017-05-01

    Pulsed laser equipment can be used to generate elastic waves through the instantaneous reaction of thermal expansion or ablation of the material; however, we cannot control the waveform generated by the laser in the same manner that we can when piezoelectric transducers are used as exciters. This study investigates the generation of narrowband tone-burst waves using a fiber laser of the type that is widely used in laser beam machining. Fiber lasers can emit laser pulses with a high repetition rate on the order of MHz, and the laser pulses can be modulated to a burst train by external signals. As a consequence of the burst laser emission, a narrowband tone-burst elastic wave is generated. We experimentally confirmed that the elastic waves agreed well with the modulation signals in time domain waveforms and their frequency spectra, and that waveforms can be controlled by the generation technique. We also apply the generation technique to defect imaging with a scanning laser source. In the experiments, with small laser emission energy, we were not able to obtain defect images from the signal amplitude due to low signal-to-noise ratio, whereas using frequency spectrum peaks of the tone-burst signals gave clear defect images, which indicates that the signal-to-noise ratio is improved in the frequency domain by using this technique for the generation of narrowband elastic waves. Moreover, even for defect imaging at a single receiving point, defect images were enhanced by taking an average of distributions of frequency spectrum peaks at different frequencies. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Numerical computation of linear instability of detonations

    Science.gov (United States)

    Kabanov, Dmitry; Kasimov, Aslan

    2017-11-01

    We propose a method to study linear stability of detonations by direct numerical computation. The linearized governing equations together with the shock-evolution equation are solved in the shock-attached frame using a high-resolution numerical algorithm. The computed results are processed by the Dynamic Mode Decomposition technique to generate dispersion relations. The method is applied to the reactive Euler equations with simple-depletion chemistry as well as more complex multistep chemistry. The results are compared with those known from normal-mode analysis. We acknowledge financial support from King Abdullah University of Science and Technology.

  20. Hybrid fiber-rod laser

    Science.gov (United States)

    Beach, Raymond J.; Dawson, Jay W.; Messerly, Michael J.; Barty, Christopher P. J.

    2012-12-18

    Single, or near single transverse mode waveguide definition is produced using a single homogeneous medium to transport both the pump excitation light and generated laser light. By properly configuring the pump deposition and resulting thermal power generation in the waveguide device, a thermal focusing power is established that supports perturbation-stable guided wave propagation of an appropriately configured single or near single transverse mode laser beam and/or laser pulse.

  1. Aspects of electron acoustic wave physics in laser backscatter from plasmas

    International Nuclear Information System (INIS)

    Sircombe, N J; Arber, T D; Dendy, R O

    2006-01-01

    Recent experimental results from the Trident laser confirm the importance of kinetic effects in determining laser reflectivities at high intensities. Examples observed include scattering from low frequency electron acoustic waves (EAWs) and the first few stages of a cascade towards turbulence through the Langmuir decay instability. Interpretive and predictive computational capability in this area is assisted by the development of Vlasov codes, which offer high velocity space resolution in high energy regions of particle phase space and do not require analytical pre-processing of the fundamental equations. A direct Vlasov solver, capable of resolving these kinetic processes, is used here to address fundamental aspects of the existence and stability of the electron acoustic wave, together with its collective scattering properties. These simulations are extended to realistic laser and plasma parameters characteristic of single hot-spot experiments. Results are in qualitative agreement with experiments displaying both stimulated Raman and stimulated electron acoustic scattering. The amplitude of simulated EAWs is greater than that observed experimentally and is accompanied by a higher phase velocity. These minor differences can be attributed to the limitations of a one-dimensional collisionless model

  2. Manipulation of the polarization of intense laser beams via optical wave mixing in plasmas

    Science.gov (United States)

    Michel, Pierre; Divol, Laurent; Turnbull, David; Moody, John

    2014-10-01

    When intense laser beams overlap in plasmas, the refractive index modulation created by the beat wave via the ponderomotive force can lead to optical wave mixing phenomena reminiscent of those used in crystals and photorefractive materials. Using a vector analysis, we present a full analytical description of the modification of the polarization state of laser beams crossing at arbitrary angles in a plasma. We show that plasmas can be used to provide full control of the polarization state of a laser beam, and give simple analytical estimates and practical considerations for the design of novel photonics devices such as plasma polarizers and plasma waveplates. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  3. High-temperature hydrogen-air-steam detonation experiments in the BNL small-scale development apparatus

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsburg, T.; Boccio, J.; Economos, C.; Finfrock, C.; Gerlach, L.; Sato, K.; Kinoshita, M.

    1994-08-01

    The Small-Scale Development Apparatus (SSDA) was constructed to provide a preliminary set of experimental data to characterize the effect of temperature on the ability of hydrogen-air-steam mixtures to undergo detonations and, equally important, to support design of the larger scale High-Temperature Combustion Facility (HTCF) by providing a test bed for solution of a number of high-temperature design and operational problems. The SSDA, the central element of which is a 10-cm inside diameter, 6.1-m long tubular test vessel designed to permit detonation experiments at temperatures up to 700K, was employed to study self-sustained detonations in gaseous mixtures of hydrogen, air, and steam at temperatures between 300K and 650K at a fixed initial pressure of 0.1 MPa. Hydrogen-air mixtures with hydrogen composition from 9 to 60 percent by volume and steam fractions up to 35 percent by volume were studied for stoichiometric hydrogen-air-steam mixtures. Detonation cell size measurements provide clear evidence that the effect of hydrogen-air gas mixture temperature, in the range 300K-650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The hydrogen-air detonability limits for the 10-cm inside diameter SSDA test vessel, based upon the onset of single-head spin, decreased from 15 percent hydrogen at 300K down to between 9 and 10 percent hydrogen at 650K. The one-dimensional ZND model does a very good job at predicting the overall trends in the cell size data over the range of hydrogen-air-steam mixture compositions and temperature studied in the experiments

  4. Observation of laser-induced elastic waves in agar skin phantoms using a high-speed camera and a laser-beam-deflection probe.

    Science.gov (United States)

    Laloš, Jernej; Gregorčič, Peter; Jezeršek, Matija

    2018-04-01

    We present an optical study of elastic wave propagation inside skin phantoms consisting of agar gel as induced by an Er:YAG (wavelength of 2.94 μm) laser pulse. A laser-beam-deflection probe is used to measure ultrasonic propagation and a high-speed camera is used to record displacements in ablation-induced elastic transients. These measurements are further analyzed with a custom developed image recognition algorithm utilizing the methods of particle image velocimetry and spline interpolation to determine point trajectories, material displacement and strain during the passing of the transients. The results indicate that the ablation-induced elastic waves propagate with a velocity of 1 m/s and amplitudes of 0.1 mm. Compared to them, the measured velocities of ultrasonic waves are much higher, within the range of 1.42-1.51 km/s, while their amplitudes are three orders of magnitude smaller. This proves that the agar gel may be used as a rudimental skin and soft tissue substitute in biomedical research, since its polymeric structure reproduces adequate soft-solid properties and its transparency for visible light makes it convenient to study with optical instruments. The results presented provide an insight into the distribution of laser-induced elastic transients in soft tissue phantoms, while the experimental approach serves as a foundation for further research of laser-induced mechanical effects deeper in the tissue.

  5. 303 nm continuous wave ultraviolet laser generated by intracavity frequency-doubling of diode-pumped Pr3+:LiYF4 laser

    Science.gov (United States)

    Zhu, Pengfei; Zhang, Chaomin; Zhu, Kun; Ping, Yunxia; Song, Pei; Sun, Xiaohui; Wang, Fuxin; Yao, Yi

    2018-03-01

    We demonstrate an efficient and compact ultraviolet laser at 303 nm generated by intracavity frequency doubling of a continuous wave (CW) laser diode-pumped Pr3+:YLiF4 laser at 607 nm. A cesium lithium borate (CLBO) crystal, cut for critical type I phase matching at room temperature, is used for second-harmonic generation (SHG) of the fundamental laser. By using an InGaN laser diode array emitting at 444.3 nm with a maximum incident power of 10 W, as high as 68 mW of CW output power at 303 nm is achieved. The output power stability in 4 h is better than 2.85%. To the best of our knowledge, this is high efficient UV laser generated by frequency doubling of an InGaN laser diode array pumped Pr3+:YLiF4 laser.

  6. Ignition Study on a Rotary-valved Air-breathing Pulse Detonation Engine

    Science.gov (United States)

    Wu, Yuwen; Han, Qixiang; Shen, Yujia; Zhao, Wei

    2017-05-01

    In the present study, the ignition effect on detonation initiation was investigated in the air-breathing pulse detonation engine. Two kinds of fuel injection and ignition methods were applied. For one method, fuel and air was pre-mixed outside the PDE and then injected into the detonation tube. The droplet sizes of mixtures were measured. An annular cavity was used as the ignition section. For the other method, fuel-air mixtures were mixed inside the PDE, and a pre-combustor was utilized as the ignition source. At firing frequency of 20 Hz, transition to detonation was obtained. Experimental results indicated that the ignition position and initial flame acceleration had important effects on the deflagration-to-detonation transition.

  7. Thermal properties and continuous-wave laser performance of Yb:LuVO4 crystal

    Science.gov (United States)

    Cheng, Y.; Zhang, H. J.; Yu, Y. G.; Wang, J. Y.; Tao, X. T.; Liu, J. H.; Petrov, V.; Ling, Z. C.; Xia, H. R.; Jiang, M. H.

    2007-03-01

    A laser crystal of Yb:LuVO4 with high optical quality was grown by the Czochralski technique. Its thermal properties including specific heat, thermal expansion coefficients, and thermal conductivities along the a- and c-axis have been measured for the first time. Continuous-wave laser output up to 3.5 W at 1031 nm was obtained at room temperature through end-pumping by a high-power diode laser. The corresponding optical conversion efficiency was 43% and the slope efficiency was 72%.

  8. Pulsed-laser-activated impulse response encoder: Sensitive detection of surface elastic waves on biomimetic microsized gel spheres

    Science.gov (United States)

    Yasukuni, Ryohei; Fukushima, Ryosuke; Iino, Takanori; Hosokawa, Yoichiroh

    2017-11-01

    A femtosecond-laser-induced impulsive force was applied to microsized calcium alginate (CaAlg) gel spheres as an external force to excite elastic waves. To evaluate elasticity, atomic force microscopy (AFM) was applied to detect vibration propagation. The sphere size dependence of the vibration was well reproduced by finite element method (FEM) simulation for pressure waves and surface acoustic waves. The obtained results indicate that the pulsed-laser-activated impulse response encoder (PLAIRE) enables the sensitive detection of elasticities, not only on inside but also on the surface.

  9. Laser Induced Shock Waves and Vaporization in Biological System and Material Science

    National Research Council Canada - National Science Library

    Gerstman, Bernard S

    2008-01-01

    .... We have developed a computational model that allows the calculation of damage resulting from a laser pulse of any duration or energy due to temperature rise, explosive bubble formation, and shock wave production...

  10. Laser ultrasound and simulated time reversal on bulk waves for non destructive control

    International Nuclear Information System (INIS)

    Diot, G; Walaszek, H; Kouadri-David, A; Guégan, S; Flifla, J

    2014-01-01

    Laser welding of aluminium generally creates embedded welding defects, such as porosities or cracks. Non Destructive Inspection (NDI) after processing may ensure an acceptable weld quality by defect detection. Nowadays, NDI techniques used to control the inside of a weld are mainly limited to X-Rays or ultrasonics. The current paper describes the use of a Laser Ultrasound (LU) technique to inspect porosities in 2 and 4-mm thick sheet lap welds. First experimentations resulted in the detection of 0.5-mm drilled holes in bulk aluminium sheets. The measurement of the depth of these defects is demonstrated too. Further experimentations shows the applicability of the LU technique to detect porosities in aluminium laser welds. However, as the interpretation of raw measures is limiting the detection capacity of this technique, we developed a signal processing using Time-Reversal capabilities to enhance detection capacities. Furthermore, the signal processing output is a geometrical image of the material's inner state, increasing the ease of interpretation. It is based on a mass-spring simulation which enables the back-propagation of the acquired ultrasound signal. The spring-mass simulation allows the natural generation of all the different sound waves and thus enables the back-propagation of a raw signal without any need of filtering or wave identification and extraction. Therefore the signal processing uses the information contained in the compression wave as well as in the shear wave

  11. Design study of a traveling-wave Thomson-scattering experiment for the realization of optical free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Steiniger, Klaus; Loeser, Markus; Pausch, Richard; Schramm, Ulrich [Helmholtz-Zentrum Dresden-Rossendorf (Germany); Technische Universitaet Dresden (Germany); Albach, Daniel; Debus, Alexander; Roeser, Fabian; Siebold, Matthias; Bussmann, Michael [Helmholtz-Zentrum Dresden-Rossendorf (Germany)

    2016-07-01

    We present an experimental setup strategy for the realization of an optical free-electron laser (OFEL) in the Traveling-Wave Thomson-Scattering geometry (TWTS). In TWTS, the electric field of petawatt class, pulse-front tilted laser pulses is used to provide an optical undulator field. This is passed by a relativistic electron bunch so that electron direction of motion and laser propagation direction enclose an interaction angle. The combination of side scattering and pulse-front tilt provides continuous overlap of electrons and laser pulse over meter scale distances which are achieved with centimeter wide laser pulses. An experimental challenge lies in shaping of these wide laser pulses in terms of laser dispersion compensation along the electron trajectory and focusing. In the talk we show how diffraction gratings in combination with mirrors are used to introduce and control dispersion of the laser in order to provide a plane wave laser field along the electron trajectory. Furthermore we give tolerance limits on alignment errors to operate the OFEL. Example setups illustrate functioning and demonstrate feasibility of the scheme.

  12. Laser Shock Wave-Assisted Patterning on NiTi Shape Memory Alloy Surfaces

    Science.gov (United States)

    Ilhom, Saidjafarzoda; Seyitliyev, Dovletgeldi; Kholikov, Khomidkohodza; Thomas, Zachary; Er, Ali O.; Li, Peizhen; Karaca, Haluk E.; San, Omer

    2018-01-01

    Shape memory alloys (SMAs) are a unique class of smart materials and they were employed in various applications in engineering, biomedical, and aerospace technologies. Here, we report an advanced, efficient, and low-cost direct imprinting method with low environmental impact to create thermally controllable surface patterns. Patterned microindents were generated on Ni50Ti50 (at. %) SMAs using an Nd:YAG laser with 1064 nm wavelength at 10 Hz. Laser pulses at selected fluences were focused on the NiTi surface and generated pressure pulses of up to a few GPa. Optical microscope images showed that surface patterns with tailorable sizes can be obtained. The depth of the patterns increases with laser power and irradiation time. Upon heating, the depth profile of SMA surfaces changed where the maximum depth recovery ratio of 30% was observed. Recovery ratio decreased and stabilized when the number of pulses and thus the well depth were further increased. A numerical simulation of pressure evolution in shape memory alloys showed a good agreement with the experimental results. The stress wave closely followed the rise time of the laser pulse to its peak value and initial decay. Rapid attenuation and dispersion of the stress wave were found in our simulation.

  13. Laser Shock Wave-Assisted Patterning on NiTi Shape Memory Alloy Surfaces

    Science.gov (United States)

    Ilhom, Saidjafarzoda; Seyitliyev, Dovletgeldi; Kholikov, Khomidkohodza; Thomas, Zachary; Er, Ali O.; Li, Peizhen; Karaca, Haluk E.; San, Omer

    2018-03-01

    Shape memory alloys (SMAs) are a unique class of smart materials and they were employed in various applications in engineering, biomedical, and aerospace technologies. Here, we report an advanced, efficient, and low-cost direct imprinting method with low environmental impact to create thermally controllable surface patterns. Patterned microindents were generated on Ni50Ti50 (at. %) SMAs using an Nd:YAG laser with 1064 nm wavelength at 10 Hz. Laser pulses at selected fluences were focused on the NiTi surface and generated pressure pulses of up to a few GPa. Optical microscope images showed that surface patterns with tailorable sizes can be obtained. The depth of the patterns increases with laser power and irradiation time. Upon heating, the depth profile of SMA surfaces changed where the maximum depth recovery ratio of 30% was observed. Recovery ratio decreased and stabilized when the number of pulses and thus the well depth were further increased. A numerical simulation of pressure evolution in shape memory alloys showed a good agreement with the experimental results. The stress wave closely followed the rise time of the laser pulse to its peak value and initial decay. Rapid attenuation and dispersion of the stress wave were found in our simulation.

  14. RANKINE-HUGONIOT RELATIONS IN RELATIVISTIC COMBUSTION WAVES

    International Nuclear Information System (INIS)

    Gao Yang; Law, Chung K.

    2012-01-01

    As a foundational element describing relativistic reacting waves of relevance to astrophysical phenomena, the Rankine-Hugoniot relations classifying the various propagation modes of detonation and deflagration are analyzed in the relativistic regime, with the results properly degenerating to the non-relativistic and highly relativistic limits. The existence of negative-pressure downstream flows is noted for relativistic shocks, which could be of interest in the understanding of the nature of dark energy. Entropy analysis for relativistic shock waves is also performed for relativistic fluids with different equations of state (EoS), denoting the existence of rarefaction shocks in fluids with adiabatic index Γ < 1 in their EoS. The analysis further shows that weak detonations and strong deflagrations, which are rare phenomena in terrestrial environments, are expected to exist more commonly in astrophysical systems because of the various endothermic reactions present therein. Additional topics of relevance to astrophysical phenomena are also discussed.

  15. Phenomenological Model for Infrared Emissions from High-Explosive Detonation Fireballs

    Science.gov (United States)

    2007-09-01

    meterological data collected near the time of this detonation event. . . . . . . . . . . . . . . . . . . . . . . . . 26 6 Brilliant Flash II test geometry...from meterological data collected near the time of this detonation event. Most of the absorption features are due to water vapor; a few regions are noted...profile computed from meterological data collected near the time of this detonation event. of the instrument. Examination of the imaginary component does

  16. Investigations on flexural wave propagation and attenuation in a modified one-dimensional acoustic black hole using a laser excitation technique

    Science.gov (United States)

    Ji, Hongli; Luo, Jing; Qiu, Jinhao; Cheng, Li

    2018-05-01

    Acoustic Black Holes (ABHs), as a new type of passive structure for vibration damping enhancement and noise attenuation, have been drawing increasing attentions of many researchers. Due to the difficulty in manufacturing the sharp edges required by the ABH structures, it is important to understand the wave propagation and attenuation process in the presence of damping layers in non-ideal ABHs with a truncated edge. In this paper, an analytical expression of the wave reflection coefficient in a modified one-dimensional ABH is derived and a time-domain experimental method based on a laser excitation technique is used to visualize the wave propagation. In the experimental studies, the flexural waves in the ABH were excited by a scanning pulse laser and measured by a Laser Doppler Vibrometer (LDV). The incident wave and reflected wave were separated from the measured original wave field and the decrease of the wave velocity in the ABH was exhibited. The reflection coefficient was calculated from the ratio of the amplitude of the reflected wave to that of the incident wave for different ABH parameters and different thicknesses of the damping layer. The measured reflection coefficients were used to identify the unknown coefficients in the theoretical formula. The results confirm that there exists an optimal thickness for the damping layer, which leads to the minimum wave reflection. Based on the laser-induced visualization technique and various signal processing and feature extraction methods, the entire process of the wave propagation in a non-ideal one-dimensional ABH structure can be visualized and scrutinized.

  17. Comb-Resolved Dual-Comb Spectroscopy Stabilized by Free-Running Continuous-Wave Lasers

    Science.gov (United States)

    Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

    2012-11-01

    We demonstrate dual-comb spectroscopy with relatively phase-locked two frequency combs, instead of frequency combs firmly fixed to the absolute frequency references. By stabilizing two beat frequencies between two mode-locked lasers at different wavelengths observed via free-running continuous-wave (CW) lasers, two combs are tightly phase locked to each other. The frequency noise of the CW lasers barely affects the performance of dual-comb spectroscopy because of the extremely fast common-mode noise rejection. Transform-limited comb-resolved dual-comb spectroscopy with a 6 Hz radio frequency linewidth is demonstrated by the use of Yb-fiber oscillators.

  18. Nitinol laser cutting: microstructure and functional properties of femtosecond and continuous wave laser processing

    Science.gov (United States)

    Biffi, C. A.; Tuissi, A.

    2017-03-01

    Thermal processing can affect the properties of smart materials, and the correct selection of the best manufacturing technology is fundamental for producing high tech smart devices, containing embedded functional properties. In this work cutting of thin superelastic Nitinol plates using a femtosecond (fs) and continuous wave (CW) laser was studied. Diamond shaped elements were cut to characterize the kerf qualitative features; microstructural analysis of the cross sections allowed identification of thermal damage characteristics introduced into the material during the laser processes. A thermally undamaged microstructure was observed for fs laser cutting, while CW was seen to be characterized by a large heat-affected zone. Functional properties were investigated by differential scanning calorimetry and tensile testing of laser cut microelements and of the reference material. It was seen that the martensitic transformation behavior of Nitinol is not affected by fs regime, while cw cutting provokes an effect equivalent to a high temperature thermal treatment in the material surrounding the cutting kerf, degradating the material properties. Finally, tensile testing indicated that superelastic performances were guaranteed by fs regime, while strong reduction of the recoverable strain was detected in the CW processed sample.

  19. Munitions having an insensitive detonator system for initiating large failure diameter explosives

    Science.gov (United States)

    Perry, III, William Leroy

    2015-08-04

    A munition according to a preferred embodiment can include a detonator system having a detonator that is selectively coupled to a microwave source that functions to selectively prime, activate, initiate, and/or sensitize an insensitive explosive material for detonation. The preferred detonator can include an explosive cavity having a barrier within which an insensitive explosive material is disposed and a waveguide coupled to the explosive cavity. The preferred system can further include a microwave source coupled to the waveguide such that microwaves enter the explosive cavity and impinge on the insensitive explosive material to sensitize the explosive material for detonation. In use the preferred embodiments permit the deployment and use of munitions that are maintained in an insensitive state until the actual time of use, thereby substantially preventing unauthorized or unintended detonation thereof.

  20. Confinement effects of shock waves on laser-induced plasma from a graphite target

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Feiling; Liang, Peipei; Yang, Xu; Cai, Hua; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian, E-mail: jsun@fudan.edu.cn [Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China)

    2015-06-15

    The spatial confinement effects of shock waves on the laser-induced plasma (LIP) from a graphite target in air were studied by probe beam deflection (PBD) measurements and optical emission spectroscopy (OES). A clear relationship between the confinement of the LIP by the shock wave and the effects on the LIP emission was observed, and the underlying mechanisms are discussed. PBD monitoring revealed that the laser-ablation induced shock wave could be well analogized to the shock wave generated by a point explosion and would be reflected by a block. OES measurements indicated that the optical emission of the LIP exhibited significant variations with the block placement. A first enhancement and then a fast decay of CN molecular emission as well as a suppression of carbon atomic emission were observed in the presence of the block. The results revealed that the reflected shock wave spatially confined the expansion of the LIP and compressed the LIP after encountering it, pushing back the species of the LIP and changing the density of the LIP species including luminous carbon atoms and CN molecules. It is suggested that the change of the LIP emission is attributed to the density variation of the LIP species due to the compression of the LIP and the reactions occurring in the plasma.

  1. Explosive vaporization induced by high-power CO2-laser target interactions

    International Nuclear Information System (INIS)

    Hugenschmidt, M.; Vollrath, K.

    1976-01-01

    The interactions of high-power laser pulses with targets such as metals or dielectric materials causes a series of optical, thermal, and mechanical processes. Thereby, heating, melting, and vaporization can take place in a short time. At power densities of about 10 7 to several 10 8 W/cm 2 this can even be produced explosively. As compared to continuous ablation, this type of interaction can remove greater masses from the bulk of material. The investigations are performed by using an electron-beam preionized CO 2 -laser acting on different target materials. The energy of the laser pulses is about 30 J, the pulse-half-widths of the long-tail pulses 4 to 6 μs. Optical measurements yield some information on threshold values for these processes, for the formation and expansion of plasmas, and for the ejection of material in form of greater particles. High speed photographic techniques include a rotating mirror- and an image converter camera. Starting from shock-wave theory, gas dynamic equations (in unidimensional approximation) allow for a quantitative determination of the specific internal energies and pressures in the case of optical detonation. (orig.) [de

  2. 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.

  3. 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.

  4. Hybrid localized waves supported by resonant anisotropic metasurfaces

    DEFF Research Database (Denmark)

    Bogdanov, A. A.; Yermakov, O. Y.; Ovcharenko, A. I.

    2016-01-01

    We study both theoretically and experimentally a new class of surface electromagnetic waves supported by resonant anisotropic metasurface. At certain frequency this type of metasurface demonstrates the topological transition from elliptical to hyperbolic regime.......We study both theoretically and experimentally a new class of surface electromagnetic waves supported by resonant anisotropic metasurface. At certain frequency this type of metasurface demonstrates the topological transition from elliptical to hyperbolic regime....

  5. Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Xiankai Meng

    2017-01-01

    Full Text Available The laser shock wave (LSW generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations.

  6. Formation mechanisms and characteristics of transition patterns in oblique detonations

    Science.gov (United States)

    Miao, Shikun; Zhou, Jin; Liu, Shijie; Cai, Xiaodong

    2018-01-01

    The transition structures of wedge-induced oblique detonation waves (ODWs) in high-enthalpy supersonic combustible mixtures are studied with two-dimensional reactive Euler simulations based on the open-source program AMROC (Adaptive Mesh Refinement in Object-oriented C++). The formation mechanisms of different transition patterns are investigated through theoretical analysis and numerical simulations. Results show that transition patterns of ODWs depend on the pressure ratio Pd/Ps, (Pd, Ps are the pressure behind the ODW and the pressure behind the induced shock, respectively). When Pd/Ps > 1.3, an abrupt transition occurs, while when Pd/Ps 1.02Φ∗ (Φ∗ is the critical velocity ratio calculated with an empirical formula).

  7. Laser shock wave consolidation of nanodiamond powders on aluminum 319

    Energy Technology Data Exchange (ETDEWEB)

    Molian, Pal [Laboratory for Lasers, MEMS, and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)], E-mail: molian@iastate.edu; Molian, Raathai; Nair, Rajeev [Laboratory for Lasers, MEMS, and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)

    2009-01-01

    A novel coating approach, based on laser shock wave generation, was employed to induce compressive pressures up to 5 GPa and compact nanodiamond (ND) powders (4-8 nm) on aluminum 319 substrate. Raman scattering indicated that the coating consisted of amorphous carbon and nanocrystalline graphite with peaks at 1360 cm{sup -1} and 1600 cm{sup -1} respectively. Scanning electron microscopy revealed a wavy, non-uniform coating with an average thickness of 40 {mu}m and absence of thermal effect on the surrounding material. The phase transition from nanodiamond to other phases of carbon is responsible for the increased coating thickness. Vicker's microhardness test showed hardness in excess of 1000 kg{sub f}/mm{sup 2} (10 GPa) while nanoindentation test indicated much lower hardness in the range of 20 MPa to 2 GPa. Optical surface profilometry traces displayed slightly uneven surfaces compared to the bare aluminum with an average surface roughness (R{sub a}) in the range of 1.5-4 {mu}m depending on the shock wave pressure and type of confining medium. Ball-on-disc tribometer tests showed that the coefficient of friction and wear rate were substantially lower than the smoother, bare aluminum sample. Laser shock wave process has thus aided in the generation of a strong, wear resistant, durable carbon composite coating on aluminum 319 substrate.

  8. Shock waves and cavitation bubbles in water and isooctane generated by Nd:YAG laser: experimental and theoretical results

    Science.gov (United States)

    Muller, Milos; Garen, Walter; Koch, Sandra; Marsik, Frantisek; Neu, Walter; Saburov, Eduado

    2004-04-01

    Temporal evolution of laser generated cavitation bubbles and shock waves were studied. Q-switched Nd-Yag laser pulses at 1064 nm are focused into the liquid. An Imager 3 CCD camera with multi exposure mode allows recording of 10 images with minimal exposure delay of 100 ns and minimal exposure time of 100 ns. Illumination is provided by xenon flash lamp for single exposure (shock wave recording) and by halogen lamp for multi exposure mode (bubble recording). Distilled water and a retrograde fluid, isooctane, have been under investigation to identify the differences in the cavitation process and shock wave propagation. The calculation of the shock wave velocities in water and isooctane are based on image recording at constant exposure time of 100 ns and using laser differential interferometry. Strong differences of bubble oscillation were observed in water and isooctane. Gilmore's model is used for numerical simulation of bubble dynamics.

  9. Precision improvement of frequency-modulated continuous-wave laser ranging system with two auxiliary interferometers

    Science.gov (United States)

    Shi, Guang; Wang, Wen; Zhang, Fumin

    2018-03-01

    The measurement precision of frequency-modulated continuous-wave (FMCW) laser distance measurement should be proportional to the scanning range of the tunable laser. However, the commercial external cavity diode laser (ECDL) is not an ideal tunable laser source in practical applications. Due to the unavoidable mode hopping and scanning nonlinearity of the ECDL, the measurement precision of FMCW laser distance measurements can be substantially affected. Therefore, an FMCW laser ranging system with two auxiliary interferometers is proposed in this paper. Moreover, to eliminate the effects of ECDL, the frequency-sampling method and mode hopping influence suppression method are employed. Compared with a fringe counting interferometer, this FMCW laser ranging system has a measuring error of ± 20 μm at the distance of 5.8 m.

  10. Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material

    International Nuclear Information System (INIS)

    Ecault, Romain; Boustie, Michel; Touchard, Fabienne; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Mercier, Patrick; Benier, Jacky

    2013-01-01

    The propagation of laser-induced shock waves in a transparent epoxy sample is investigated by optical shadowgraphy. The shock waves are generated by a focused laser (3 ns pulse duration—1.2 to 3.4 TW cm −2 ) producing pressure from 44 to 98.9 GPa. It is observed that the shock wave and the release wave created by the shock reverberation at the rear face are both followed by a dark zone in the pictures. This corresponds to the creation of a tensile zone resulting from the crossing on the loading axis of the release waves coming from the edge of the impact area (2D effects). After the laser shock experiment, the residual stresses in the targets are identified and quantified through a photoelasticimetry analysis of the recovered samples. This work results in a new set of original data which can be directly used to validate numerical models implemented to reproduce the behaviour of epoxy under extreme strain rate loading. The residual stresses observed prove that the high-pressure shocks can modify the pure epoxy properties, which could have an influence on the use made of these materials. (paper)

  11. Effects of Medium Characteristics on Laser RCS of Airplane with E-Wave Polarization

    Directory of Open Access Journals (Sweden)

    Hosam El-Ocla

    2015-01-01

    Full Text Available Plane wave incidence should be postulated to have an authentic target detection. Practically, the plane wave is incapable usually of keeping its power in the far field especially when propagating through an inhomogeneous medium. Consequently, we assume an incident beam wave with a finite width around the target. In this work, we calculate numerically a laser radar cross section (LRCS of conducting targets having smooth cross sections with inflection points such as airplane in random media. Effects of fluctuations intensity of random media on the LRCS performance are studied in this paper. E-wave polarization (E-wave incidence is considered while the mean target size is approximately twice the wavelength.

  12. Quasi-monoenergetic ion beam acceleration by laser-driven shock and solitary waves in near-critical plasmas

    International Nuclear Information System (INIS)

    Zhang, W. L.; Qiao, B.; Huang, T. W.; Shen, X. F.; You, W. Y.; Yan, X. Q.; Wu, S. Z.; Zhou, C. T.; He, X. T.

    2016-01-01

    Ion acceleration in near-critical plasmas driven by intense laser pulses is investigated theoretically and numerically. A theoretical model has been given for clarification of the ion acceleration dynamics in relation to different laser and target parameters. Two distinct regimes have been identified, where ions are accelerated by, respectively, the laser-induced shock wave in the weakly driven regime (comparatively low laser intensity) and the nonlinear solitary wave in the strongly driven regime (comparatively high laser intensity). Two-dimensional particle-in-cell simulations show that quasi-monoenergetic proton beams with a peak energy of 94.6 MeV and an energy spread 15.8% are obtained by intense laser pulses at intensity I_0 = 3 × 10"2"0" W/cm"2 and pulse duration τ = 0.5 ps in the strongly driven regime, which is more advantageous than that got in the weakly driven regime. In addition, 233 MeV proton beams with narrow spread can be produced by extending τ to 1.0 ps in the strongly driven regime.

  13. Quasi-monoenergetic ion beam acceleration by laser-driven shock and solitary waves in near-critical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W. L.; Qiao, B., E-mail: bqiao@pku.edu.cn; Huang, T. W.; Shen, X. F.; You, W. Y. [Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006 (China); Yan, X. Q. [Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Wu, S. Z. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Zhou, C. T.; He, X. T. [Center for Applied Physics and Technology, HEDPS, and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)

    2016-07-15

    Ion acceleration in near-critical plasmas driven by intense laser pulses is investigated theoretically and numerically. A theoretical model has been given for clarification of the ion acceleration dynamics in relation to different laser and target parameters. Two distinct regimes have been identified, where ions are accelerated by, respectively, the laser-induced shock wave in the weakly driven regime (comparatively low laser intensity) and the nonlinear solitary wave in the strongly driven regime (comparatively high laser intensity). Two-dimensional particle-in-cell simulations show that quasi-monoenergetic proton beams with a peak energy of 94.6 MeV and an energy spread 15.8% are obtained by intense laser pulses at intensity I{sub 0} = 3 × 10{sup 20 }W/cm{sup 2} and pulse duration τ = 0.5 ps in the strongly driven regime, which is more advantageous than that got in the weakly driven regime. In addition, 233 MeV proton beams with narrow spread can be produced by extending τ to 1.0 ps in the strongly driven regime.

  14. Support structures for optical components in the Laser Demonstration Facility

    International Nuclear Information System (INIS)

    Finucane, R.G.

    1985-01-01

    The laser system in the Laser Demonstration Facility is mounted on an array of 108 support columns. This milestone report describes the design, analyses, testing, fabrication, installation, and performance characteristics of these supports

  15. Stability design considerations for mirror support systems in ICF lasers

    International Nuclear Information System (INIS)

    Tietbohl, G.L.; Sommer, S.C.

    1996-10-01

    Some of the major components of laser systems used for Inertial Confinement Fusion (ICF) are the large aperture mirrors which direct the path of the laser. These mirrors are typically supported by systems which consist of mirror mounts, mirror enclosures, superstructures, and foundations. Stability design considerations for the support systems of large aperture mirrors have been developed based on the experience of designing and evaluating similar systems at the Lawrence Livermore National Laboratory (LLNL). Examples of the systems developed at LLNL include Nova, the Petawatt laser, Beamlet, and the National Ignition Facility (NIF). The structural design of support systems of large aperture mirrors has typically been controlled by stability considerations in order for the large laser system to meet its performance requirements for alignment and positioning. This paper will discuss the influence of stability considerations and will provide guidance on the structural design and evaluation of mirror support systems in ICF lasers so that this information can be used on similar systems

  16. LASER PLASMA AND LASER APPLICATIONS: Plasma transparency in laser absorption waves in metal capillaries

    Science.gov (United States)

    Anisimov, V. N.; Kozolupenko, A. P.; Sebrant, A. Yu

    1988-12-01

    An experimental investigation was made of the plasma transparency to heating radiation in capillaries when absorption waves propagated in these capillaries as a result of interaction with a CO2 laser pulse of 5-μs duration. When the length of the capillary was in excess of 20 mm, total absorption of the radiation by the plasma was observed at air pressures of 1-100 kPa. When the capillary length was 12 mm, a partial recovery of the transparency took place. A comparison was made with the dynamics and recovery of the plasma transparency when breakdown of air took place near the free surface.

  17. Nonlinear dynamic effects in a two-wave CO2 laser

    International Nuclear Information System (INIS)

    Gorobets, V A; Kozlov, K V; Kuntsevich, B F; Petukhov, V O

    1999-01-01

    Theoretical and experimental investigations were made of nonlinear dynamic regimes of the operation of a two-wave CO 2 laser with cw excitation in an electric discharge and loss modulation in one of the channels. Nonlinear amplitude - frequency characteristics of each of the laser channels have two low-frequency resonance spikes, associated with forced linear oscillations of two coupled oscillators, and high-frequency spikes, corresponding to doubling of the period of the output radiation oscillations. At low loss-modulation frequencies the intensity oscillations of the output radiation in the coupled channels are in antiphase, whereas at high modulation frequencies the dynamics is cophasal. Nonlinear dynamic effects, such as doubling of the period and of the repetition frequency of the pulses and chaotic oscillations of the output radiation intensity, are observed for certain system parameters. (control of laser radiation parameters)

  18. Multistage reaction pathways in detonating high explosives

    International Nuclear Information System (INIS)

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya

    2014-01-01

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N 2 and H 2 O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N 2 and H 2 O productions

  19. Multistage reaction pathways in detonating high explosives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2014-11-17

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N{sub 2} and H{sub 2}O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N{sub 2} and H{sub 2}O productions.

  20. Contribution to the study of detonation initiation by shock in solid explosives (1961); Contribution a l'etude de l'initiation de la detonation par choc dans les explosifs solides (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Fauquignon, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-05-15

    When a shock wave is induced in an explosive, it can initiate chemical reactions which lead more or less rapidly to a stable detonation state. In this study more particular attention was paid to the transition phase, in which has been evaluated the increases in the wave velocity, the pressure, and the electrical conductivity. The influence of the nature of the medium in front of the wave and in contact with the explosive has also been the subject of an experimental study designed to determine the extent to which its nature can be ignored and, subsequently, to characterise the initiation conditions using only the shock intensity induced in the explosive. Finally, the results were generalized for various explosive compositions and led to the development of a possible mechanism for shock initiation. (author) [French] Lorsqu'une onde de choc est induite dans un explosif, elle peut y amorcer des reactions chimiques qui conduisent plus ou moins rapidement a un regime de detonation stable. Dans cette etude, on s'est interesse plus particulierement a la phase transitoire dans laquelle on a evalue l'accroissement de la vitesse d'onde, de la pression et de la conductibilite electrique. L'influence du milieu amont, au contact de l'explosif, a egalement fait l'objet de recherches experimentales de facon a determiner dans quelle mesure on pouvait s'affranchir de sa nature et, par suite, caracteriser les conditions d'initiation par la seule intensite du choc induit dans l'explosif. Enfin, les resultats ont ete generalises a diverses compositions explosives et ont conduit a l'elaboration d'un schema possible du mecanisme de l'initiation par choc. (auteur)

  1. Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers.

    Science.gov (United States)

    Eigenwillig, Christoph M; Wieser, Wolfgang; Todor, Sebastian; Biedermann, Benjamin R; Klein, Thomas; Jirauschek, Christian; Huber, Robert

    2013-01-01

    Ultrafast lasers have a crucial function in many fields of science; however, up to now, high-energy pulses directly from compact, efficient and low-power semiconductor lasers are not available. Therefore, we introduce a new approach based on temporal compression of the continuous-wave, wavelength-swept output of Fourier domain mode-locked lasers, where a narrowband optical filter is tuned synchronously to the round-trip time of light in a kilometre-long laser cavity. So far, these rapidly swept lasers enabled orders-of-magnitude speed increase in optical coherence tomography. Here we report on the generation of ~60-70 ps pulses at 390 kHz repetition rate. As energy is stored optically in the long-fibre delay line and not as population inversion in the laser-gain medium, high-energy pulses can now be generated directly from a low-power, compact semiconductor-based oscillator. Our theory predicts subpicosecond pulses with this new technique in the future.

  2. Simulation study and guidelines to generate Laser-induced Surface Acoustic Waves for human skin feature detection

    Science.gov (United States)

    Li, Tingting; Fu, Xing; Chen, Kun; Dorantes-Gonzalez, Dante J.; Li, Yanning; Wu, Sen; Hu, Xiaotang

    2015-12-01

    Despite the seriously increasing number of people contracting skin cancer every year, limited attention has been given to the investigation of human skin tissues. To this regard, Laser-induced Surface Acoustic Wave (LSAW) technology, with its accurate, non-invasive and rapid testing characteristics, has recently shown promising results in biological and biomedical tissues. In order to improve the measurement accuracy and efficiency of detecting important features in highly opaque and soft surfaces such as human skin, this paper identifies the most important parameters of a pulse laser source, as well as provides practical guidelines to recommended proper ranges to generate Surface Acoustic Waves (SAWs) for characterization purposes. Considering that melanoma is a serious type of skin cancer, we conducted a finite element simulation-based research on the generation and propagation of surface waves in human skin containing a melanoma-like feature, determine best pulse laser parameter ranges of variation, simulation mesh size and time step, working bandwidth, and minimal size of detectable melanoma.

  3. Searching for Fast Radio Bursts with the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)

    Science.gov (United States)

    Fisher, Ryan Patrick; Hughey, Brennan; Howell, Eric; LIGO Collaboration

    2018-01-01

    Although Fast Radio Bursts (FRB) are being detected with increasing frequency, their progenitor systems are still mostly a mystery. We present the plan to conduct targeted searches for gravitational-wave counterparts to these FRB events in the data from the first and second observing runs of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO).

  4. Resonant Laser Ignition Study of HAN-HEHN Propellant Mixture (Preprint)

    National Research Council Canada - National Science Library

    Alfano, Angelo J; Mills, Jeffrey D; Vaghjiani, Ghanshyam L

    2008-01-01

    ...) - hydroxyethylhydrazinium nitrate (HEHN) mixtures. This prototypical ionic liquid propellant was successfully and reliably ignited/detonated under confinement with single laser pulses in the mid IR at 2.94 and 10.6 microns...

  5. Demonstration of optical rogue waves using a laser diode emitting at 980  nm and a fiber Bragg grating.

    Science.gov (United States)

    Lee, Min Won; Baladi, Fadwa; Burie, Jean-René; Bettiati, Mauro A; Boudrioua, Azzedine; Fischer, Alexis P A

    2016-10-01

    Rogue waves are observed for the first time, to the best of our knowledge, in a 980 nm laser diode subject to filtered optical feedback via a fiber Bragg grating. By counting the number of rogue waves in a fixed time window, a rogue wave map is established experimentally as a function of both the optical feedback ratio and the laser current. The comparison with low frequency fluctuations (LFFs) reveals that the rogue waves observed in our system are, in fact, LFF jump-ups.

  6. Effect of temperature on electrical conductance of inkjet-printed silver nanoparticle ink during continuous wave laser sintering

    International Nuclear Information System (INIS)

    Lee, Dae-Geon; Kim, Dong Keun; Moon, Yoon-Jae; Moon, Seung-Jae

    2013-01-01

    To determine the effect of temperature on the specific electrical conductance of inkjet-printed ink during continuous wave laser sintering, the temperature of the sintered ink was estimated. The ink, which contained 34 wt.% silver nanoparticles with an average size of approximately 50 nm, was inkjet-printed onto a liquid crystal display glass substrate. The printed ink was irradiated with a 532 nm continuous wave laser for 60 s with various laser intensities. During laser irradiation, the in-situ electrical conductance of the sintered ink was measured to estimate the transient thermal conductivity of the ink. The electrical conductance and thermal conductivity of the ink was coupled to obtain the transient temperature by applying the Wiedemann–Franz law to a two-dimensional transient heat conduction equation. The electrical conductance of laser-sintered ink was highly dependent on the sintering temperature of the ink. - Highlights: • The in-situ electrical conductance was measured during the laser sintering process. • Wiedemann–Franz law coupled the electrical conductance with transient temperature. • The transient temperature of the laser-sintered Ag nanoparticle ink was estimated

  7. Lightning-resistant, low-inductance detonator cables

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R.L.; Lee, R.S.; Moua, K.

    1994-04-01

    A lightning strike on a flat detonator cable in close proximity to a high explosive (HE) main charge poses a possible detonation hazard if the electrical explosion of the cable launches the dielectric cover coat of the cable at a high enough velocity to shock-initiate the HE. The detonator cable for the W87 system has been demonstrated to be incapable of initiating LX-17 main-charge explosive even for a 99 percentile negative lightning strike (1). The W87 cable is a relatively high inductance cable, unsuitable for use with low-inductance firesets. We have performed tests on a low-inductance cable designed for the W89 program, which show it to be marginal in its ability to withstand a lightning strike without the possibility of initiating a heated LX-17 main charge HE. A new cable design, proposed by R.E. Lee of LLNL has been tested and shown to be capable of withstanding a 99 percentile negative lightning strike without initiating LX-17 heated to 250{degree}C.

  8. Geometry-specific scaling of detonation parameters from front curvature

    International Nuclear Information System (INIS)

    Jackson, Scott I.; Short, Mark

    2011-01-01

    It has previously been asserted that classical detonation curvature theory predicts that the critical diameter and the diameter-effect curve of a cylindrical high-explosive charge should scale with twice the thickness of an analogous two-dimensional explosive slab. The varied agreement of experimental results with this expectation have led some to question the ability of curvature-based concepts to predict detonation propagation in non-ideal explosives. This study addresses such claims by showing that the expected scaling relationship (hereafter referred to d = 2w) is not consistent with curvature-based Detonation Shock Dynamics (DSD) theory.

  9. Comparative performance analysis of combined-cycle pulse detonation turbofan engines (PDTEs

    Directory of Open Access Journals (Sweden)

    Sudip Bhattrai

    2013-09-01

    Full Text Available Combined-cycle pulse detonation engines are promising contenders for hypersonic propulsion systems. In the present study, design and propulsive performance analysis of combined-cycle pulse detonation turbofan engines (PDTEs is presented. Analysis is done with respect to Mach number at two consecutive modes of operation: (1 Combined-cycle PDTE using a pulse detonation afterburner mode (PDA-mode and (2 combined-cycle PDTE in pulse detonation ramjet engine mode (PDRE-mode. The performance of combined-cycle PDTEs is compared with baseline afterburning turbofan and ramjet engines. The comparison of afterburning modes is done for Mach numbers from 0 to 3 at 15.24 km altitude conditions, while that of pulse detonation ramjet engine (PDRE is done for Mach 1.5 to Mach 6 at 18.3 km altitude conditions. The analysis shows that the propulsive performance of a turbine engine can be greatly improved by replacing the conventional afterburner with a pulse detonation afterburner (PDA. The PDRE also outperforms its ramjet counterpart at all flight conditions considered herein. The gains obtained are outstanding for both the combined-cycle PDTE modes compared to baseline turbofan and ramjet engines.

  10. Molecular dynamics simulation of shock wave and spallation phenomena in metal foils irradiated by femtosecond laser pulse

    Science.gov (United States)

    Zhakhovsky, Vasily; Demaske, Brian; Inogamov, Nail; Oleynik, Ivan

    2010-03-01

    Femtosecond laser irradiation of metals is an effective technique to create a high-pressure frontal layer of 100-200 nm thickness. The associated ablation and spallation phenomena can be studied in the laser pump-probe experiments. We present results of a large-scale MD simulation of ablation and spallation dynamics developing in 1,2,3μm thick Al and Au foils irradiated by a femtosecond laser pulse. Atomic-scale mechanisms of laser energy deposition, transition from pressure wave to shock, reflection of the shock from the rear-side of the foil, and the nucleation of cracks in the reflected tensile wave, having a very high strain rate, were all studied. To achieve a realistic description of the complex phenomena induced by strong compression and rarefaction waves, we developed new embedded atom potentials for Al and Au based on cold pressure curves. MD simulations revealed the complex interplay between spallation and ablation processes: dynamics of spallation depends on the pressure profile formed in the ablated zone at the early stage of laser energy absorption. It is shown that the essential information such as material properties at high strain rate and spall strength can be extracted from the simulated rear-side surface velocity as a function of time.

  11. Evaluation of Heat Losses Behind the Front of the Detonation Moving Along the Metallic Porous Surface

    Directory of Open Access Journals (Sweden)

    S. V. Golovastov

    2016-01-01

    Full Text Available The paper considers a computational technique of the heat flow from the hot products of detonation combustion into the porous coating and estimates the efficiency of the coating layer that results in slowing the flame front down with disregard the transverse displacement of the combustion products weight of a hydrogen-air mixture.Initial thermodynamic parameters of combustion products on the porous coating surface have been estimated. A drag (stagnation temperature of flow was determined.The statement of task was to calculate the heat flow into the long cylindrical metal fiber with radius of 15 μm. The reference values of heat capacity and heat diffusivity were used to estimate a thermal diffusivity in a wide range of temperatures. An approximation of the parameters is given for a wide range of temperatures.The calculation algorithm using an explicit four-point scheme is presented. The convergence and accuracy of the results were confirmed. The theoretical estimation using cylindrical Bessel functions was made to prove the accuracy of the results.Total heat loss was estimated using the photos of moving detonation front and hot combustion gases.Comparison of the total heat loss and the amount of energy absorbed by a single fiber allowed us to find that the porous coating thickness, resulting in attenuation of detonation wave, is efficient.

  12. A new method for detection of the electron temperature in laser-plasma short wave cut off of stimulated Raman scattering spectrum

    International Nuclear Information System (INIS)

    Zhang Jiatai

    1994-01-01

    From the theory of stimulated Raman scattering (SRS) three wave interaction, a new method of detecting the electron temperature in laser-plasma is obtained. SRS spectrum obtained from Shenguang No. 12 Nd-laser experiments are analysed. Using the wave length of short wave cut off of SRS, the electron temperature in corona plasma region is calculated consistently. These results agree reasonable with X-ray spectrum experiments

  13. Fractional Ablative Laser Followed by Transdermal Acoustic Pressure Wave Device to Enhance the Drug Delivery of Aminolevulinic Acid: In Vivo Fluorescence Microscopy Study.

    Science.gov (United States)

    Waibel, Jill S; Rudnick, Ashley; Nousari, Carlos; Bhanusali, Dhaval G

    2016-01-01

    Topical drug delivery is the foundation of all dermatological therapy. Laser-assisted drug delivery (LAD) using fractional ablative laser is an evolving modality that may allow for a greater precise depth of penetration by existing topical medications, as well as more efficient transcutaneous delivery of large drug molecules. Additional studies need to be performed using energy-driven methods that may enhance drug delivery in a synergistic manner. Processes such as iontophoresis, electroporation, sonophoresis, and the use of photomechanical waves aid in penetration. This study evaluated in vivo if there is increased efficacy of fractional CO2 ablative laser with immediate acoustic pressure wave device. Five patients were treated and biopsied at 4 treatment sites: 1) topically applied aminolevulinic acid (ALA) alone; 2) fractional ablative CO2 laser and topical ALA alone; 3) fractional ablative CO2 laser and transdermal acoustic pressure wave device delivery system; and 4) topical ALA with transdermal delivery system. The comparison of the difference in the magnitude of diffusion with both lateral spread of ALA and depth diffusion of ALA was measured by fluorescence microscopy. For fractional ablative CO2 laser, ALA, and transdermal acoustic pressure wave device, the protoporphyrin IX lateral fluorescence was 0.024 mm on average vs 0.0084 mm for fractional ablative CO2 laser and ALA alone. The diffusion for the acoustic pressure wave device was an order of magnitude greater. We found that our combined approach of fractional ablative CO2 laser paired with the transdermal acoustic pressure wave device increased the depth of penetration of ALA.

  14. Preliminary Pressure Records from a detonator initiated f.c.i

    International Nuclear Information System (INIS)

    Board, Simon John

    1976-01-01

    On the theory of Board, Hall and Hall (1975) it should be possible, given a suitable trigger, to achieve a very efficient thermal explosion in which a self-sustaining shock wave passes through a course initial mixture, causes fine fragmentation. We describe briefly an experiment in which a rather dilute mixture of tine and water, confined in a strong tube, was triggered by a No. 6 detonator; the progress of the explosion was monitored by four pressure transducers in the tube wall. The Kistler 603B transducers were connected to an Ampex FR1300A tape recorder with 40 kHz bandwidth, in parallel with U/V recorder galvanometers of 5 kHz resonant frequency. The presence of the metal was detected by the shorting of two parallel meshes at the mouth of the tube. Detailed comparison between the tape recorded traces and those in the U/V recorder show good agreement, with no evidence of transient overload. We may make the following preliminary observations. The negative feature travelling at ∼10 5 cm/s is presumably a compression wave travelling on the walls of the strong tube. There are several reasons for thinking that substantial energy release took place in the region around transducer 2 (1 being the nearest to the detonator). Firstly we know from earlier visualisation experiments that the metal is concentrated (in ∼1/3 cm drops) in this region of the tube. Secondly the pressure-time integral under record 2 is substantially greater than that under 1. Thirdly the rise time of 100 μs for record 2 is of the order of that expected for collapse of a vapour blanket on a 1/3 cm drop under 60 bars overpressure. Further up the tube the pressure pulse decays slightly, and also steepens; this is consistent with there being considerably less vapour and metal in this region. In the total volume of the tube (600 cc) there are ∼100 cc of metal - assuming an equal quantity of vapour, and a mean front velocity of 5 x 10 4 cm/s we find a differential velocity of ∼ 10 4 cm/s, which

  15. Infrared skin damage thresholds from 1319-nm continuous-wave laser exposures

    Science.gov (United States)

    Oliver, Jeffrey W.; Vincelette, Rebecca; Noojin, Gary D.; Clark, Clifton D.; Harbert, Corey A.; Schuster, Kurt J.; Shingledecker, Aurora D.; Kumru, Semih S.; Maughan, Justin; Kitzis, Naomi; Buffington, Gavin D.; Stolarski, David J.; Thomas, Robert J.

    2013-12-01

    A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.0, 2.5, and 10 s and beam diameters of ˜0.6 and 1 cm. Thermal imagery data provided a time-dependent surface temperature response from the laser. A damage endpoint of fifty percent probability of a minimally visible effect was used to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a numerical model of optical-thermal interaction. Resultant trends with respect to exposure duration and beam diameter are compared with current standardized exposure limits for laser safety. Mathematical modeling agreed well with experimental data, predicting that though laser safety standards are sufficient for exposures <10 s, they may become less safe for very long exposures.

  16. On a stabilization mechanism for low-velocity detonations

    KAUST Repository

    Sow, Aliou; Semenko, Roman E.; Kasimov, Aslan R.

    2017-01-01

    We use numerical simulations of the reactive Lula equations to analyse the nonlinear stability of steady-state one-dimensional solutions for gaseous detonations in the presence of both momentum and heat losses. Our results point to a possible stabilization mechanism for the low-velocity detonations in such systems. The mechanism stems from the existence of a one-parameter family of solutions found in Semenko el al.

  17. On a stabilization mechanism for low-velocity detonations

    KAUST Repository

    Sow, Aliou

    2017-03-08

    We use numerical simulations of the reactive Lula equations to analyse the nonlinear stability of steady-state one-dimensional solutions for gaseous detonations in the presence of both momentum and heat losses. Our results point to a possible stabilization mechanism for the low-velocity detonations in such systems. The mechanism stems from the existence of a one-parameter family of solutions found in Semenko el al.

  18. A discussion of the kamlet-jacobs formula for the detonation pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kazandjian, Luc; Danel, Jean-Francois [Commissariat a l' Energie Atomique, Centre CEA-DIF, B. P. 12, F-91680 Bruyeres-le-Chatel (France)

    2006-02-15

    The main features of the Kamlet-Jacobs formula for the detonation pressure of C-H-N-O explosives are analytically derived from a BKW (Becker-Kistiakowsky-Wilson) equation of state of the detonation products. In the derivation, well-known typical values at the Chapman-Jouguet state, in particular the nearly constant value of the relative volume of the detonation products, are used. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  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. Investigation of cellular detonation structure formation via linear stability theory and 2D and 3D numerical simulations

    Science.gov (United States)

    Borisov, S. P.; Kudryavtsev, A. N.

    2017-10-01

    Linear and nonlinear stages of the instability of a plane detonation wave (DW) and the subsequent process of formation of cellular detonation structure are investigated. A simple model with one-step irreversible chemical reaction is used. The linear analysis is employed to predict the DW front structure at the early stages of its formation. An emerging eigenvalue problem is solved with a global method using a Chebyshev pseudospectral method and the LAPACK software library. A local iterative shooting procedure is used for eigenvalue refinement. Numerical simulations of a propagation of a DW in plane and rectangular channels are performed with a shock capturing WENO scheme of 5th order. A special method of a computational domain shift is implemented in order to maintain the DW in the domain. It is shown that the linear analysis gives certain predictions about the DW structure that are in agreement with the numerical simulations of early stages of DW propagation. However, at later stages, a merger of detonation cells occurs so that their number is approximately halved. Computations of DW propagation in a square channel reveal two different types of spatial structure of the DW front, "rectangular" and "diagonal" types. A spontaneous transition from the rectangular to diagonal type of structure is observed during propagation of the DW.

  1. Continuous-wave generation and tunability of eye-safe resonantly diode-pumped Er:YAG laser

    Science.gov (United States)

    Němec, Michal; Indra, Lukás.; Šulc, Jan; Jelínková, Helena

    2016-03-01

    Laser sources generating radiation in the spectral range from 1.5 to 1.7 μm are very attractive for many applications such as satellite communication, range finding, spectroscopy, and atmospheric sensing. The goal of our research was an investigation of continuous-wave generation and wavelength tuning possibility of diode pumped eye-safe Er:YAG laser emitting radiation around 1645 nm. We used two 0.5 at. % doped Er:YAG active media with lengths of 10 mm and 25 mm (diameter 5 mm). As a pumping source, a fibre-coupled 1452 nm laser-diode was utilized, which giving possibility of the in-band pumping with a small quantum defect and low thermal stress of the active bulk laser material. The 150 mm long resonator was formed by a pump mirror (HT @ 1450 nm, HR @ 1610 - 1660 nm) and output coupler with 96 % reflectivity at 1610 - 1660 nm. For continuous-wave generation, the maximal output powers were 0.7 W and 1 W for 10 mm and 25 mm long laser crystals, respectively. The corresponding slope efficiencies with respect to absorbed pump power for these Er:YAG lasers were 26.5 % and 37.8 %, respectively. The beam spatial structure was close to the fundamental Gaussian mode. A wavelength tunability was realized by a birefringent plate and four local spectral maxima at 1616, 1633, 1645, and 1657 nm were reached. The output characteristics of the designed and realized resonantly diode-pumped eye-safe Er:YAG laser show that this compact system has a potential for usage mainly in spectroscopic fields.

  2. Angular characteristics of the stimulated-Brillouin-scattering spectrum from a laser plasma with strong acoustic-wave damping

    International Nuclear Information System (INIS)

    Saikia, P.

    1981-01-01

    The spectrum of stimulated Brillouin scattering from an inhomogeneous moving laser plasma is analyzed. The damping of acoustic waves and scattered electromagnetic waves is taken into account. Spectra are derived for various scattering angles and for various radii of the laser beam. For all observation angles the center of the spectral line is at an unshifted frequency. As the observation angle increases, the width of the red wing in the spectrum increases. The intensity of the scattered light is very anisotropic

  3. Atomic motion in a high-intensity standing wave laser field

    International Nuclear Information System (INIS)

    Saez Ramdohr, L.F.

    1987-01-01

    This work discusses the effect of a high-intensity standing wave laser field on the motion of neutral atoms moving with a relatively high velocity. The analysis involves a detailed calculation of the force acting on the atoms and the calculation of the diffusion tensor associated with the fluctuations of the quantum force operator. The high-intensity laser field limit corresponds to a Rabi frequency much greater than the natural rate of the atom. The general results are valid for any atomic velocity. Results are then specialized to the case of slow and fast atoms where the Doppler shift of the laser frequency due to the atomic motion is either smaller or larger than the natural decay rate of the atom. The results obtained for the force and diffusion tensor are applied to a particular ideal experiment that studies the evolution of a fast atomic beam crossing a high-intensity laser beam. The theories developed previously, for a similar laser configuration, discuss only the low atomic velocities case and not the more realistic case of fast atoms. Here, an approximate solution of the equation for the distribution is obtained. Starting from the approximate distribution function, the deflection angle and dispersion angle for the atomic beam with respect to the free motion are calculated

  4. Thermal stability of detonation-produced micro and nanodiamonds

    Science.gov (United States)

    Efremov, V. P.; Zakatilova, E. I.; Maklashova, I. V.; Shevchenko, N. V.

    2018-01-01

    Detonation nanodiamonds are produced at utilization of high explosives. When an explosive blasts in a water environment, the detonation products contain microdiamonds, and in a gaseous medium, nanodiamonds. It is known that with decreasing size the influence of the surface energy of particles on their properties increases. Thus, it is interesting to compare the properties of detonation nano and microdiamonds. In this study, we have examined the thermal stability of diamond materials by synchronous thermal analysis. The experiments were performed at atmospheric pressure in argon flow for different heating rates in a range from room temperature to 1500 °C. Samples of initial and annealed micro and nanomaterials were studied using electron microscopy, x-ray and x-ray-fluorescence analysis. It was established that thermal and structural properties of micro and nanodiamonds differ substantially.

  5. Watt-Level Continuous-Wave Emission from a Bi-Functional Quantum Cascade Laser/Detector

    Science.gov (United States)

    2017-04-18

    cally authorized by the U.S. Government may violate any copyrights that exist in this work. Watt-level continuous- wave emission from a bi- functional ... wave bi- functional devices, opens the perspective of on-chip dual comb spectroscopy. Also for discrete sens- ing setups, one can switch to lasers...seas.harvard.edu Abstract Bi- functional active regions, capable of light generation and detection at the same wavelength, allow a straightforward realization of

  6. Laser ablative nanostructuring of Au in liquid ambience in continuous wave illumination regime

    Science.gov (United States)

    Kucherik, A. O.; Kutrovskaya, S. V.; Arakelyan, S. M.; Ryabchikov, Y. V.; Al-Kattan, A.; Kabashin, A. V.; Itina, T. E.

    2016-03-01

    Gold nanoparticles (Au NPs) attract particular attention because of their unique size-dependent chemical, physicochemical and optical properties and, hence, their potential applications in catalysis, nanoelectronics, photovoltaics and medicine. In particular, laser-produced colloidal nanoparticles are not only biocompatible, but also reveal unique chemical properties. Different laser systems can be used for synthesis of these colloids, varying from continuous wave (CW) to ultra-short femtosecond lasers. The choice of an optimum laser system is still a challenge in application development. To bring more light at this issue, we investigate an influence of laser parameters on nanoparticle formation from a gold target immersed in deionized water. First, an optical diagnostics of laser-induced hydrodynamic processes taking place near the gold surface is performed. Then, gold nanoparticle colloids with average particle sizes smaller than 10 nm and a very narrow dispersion are shown to be formed by CW laser ablation. The obtained results are compared with the ones obtained by using the second harmonics and with previous results obtained by using femtosecond laser systems.

  7. Continuous wave room temperature external ring cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Revin, D. G., E-mail: d.revin@sheffield.ac.uk; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W. [Physics and Astronomy Department, The University of Sheffield, S3 7RH Sheffield (United Kingdom); Hempler, N.; Maker, G. T.; Malcolm, G. P. A. [M Squared Lasers Ltd., G20 0SP Glasgow (United Kingdom)

    2015-06-29

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

  8. Continuous wave room temperature external ring cavity quantum cascade laser

    International Nuclear Information System (INIS)

    Revin, D. G.; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W.; Hempler, N.; Maker, G. T.; Malcolm, G. P. A.

    2015-01-01

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm −1 is realized by the incorporation of a diffraction grating into the cavity

  9. Toward the Extreme Ultra Violet Four Wave Mixing Experiments: From Table Top Lasers to Fourth Generation Light Sources

    OpenAIRE

    Riccardo Cucini; Andrea Battistoni; Filippo Bencivenga; Alessandro Gessini; Riccardo Mincigrucci; Erika Giangrisostomi; Emiliano Principi; Flavio Capotondi; Emanuele Pedersoli; Michele Manfredda; Maya Kiskinova; Claudio Masciovecchio

    2015-01-01

    Three different Transient Grating setups are presented, with pulsed and continuous wave probe at different wavelengths, ranging from infrared to the extreme ultra violet region. Both heterodyne and homodyne detections are considered. Each scheme introduces variations with respect to the previous one, allowing moving from classical table top laser experiments towards a new four wave mixing scheme based on free electron laser radiation. A comparison between the various setups and the first resu...

  10. HERMES: A Model to Describe Deformation, Burning, Explosion, and Detonation

    Energy Technology Data Exchange (ETDEWEB)

    Reaugh, J E

    2011-11-22

    HERMES (High Explosive Response to MEchanical Stimulus) was developed to fill the need for a model to describe an explosive response of the type described as BVR (Burn to Violent Response) or HEVR (High Explosive Violent Response). Characteristically this response leaves a substantial amount of explosive unconsumed, the time to reaction is long, and the peak pressure developed is low. In contrast, detonations characteristically consume all explosive present, the time to reaction is short, and peak pressures are high. However, most of the previous models to describe explosive response were models for detonation. The earliest models to describe the response of explosives to mechanical stimulus in computer simulations were applied to intentional detonation (performance) of nearly ideal explosives. In this case, an ideal explosive is one with a vanishingly small reaction zone. A detonation is supersonic with respect to the undetonated explosive (reactant). The reactant cannot respond to the pressure of the detonation before the detonation front arrives, so the precise compressibility of the reactant does not matter. Further, the mesh sizes that were practical for the computer resources then available were large with respect to the reaction zone. As a result, methods then used to model detonations, known as {beta}-burn or program burn, were not intended to resolve the structure of the reaction zone. Instead, these methods spread the detonation front over a few finite-difference zones, in the same spirit that artificial viscosity is used to spread the shock front in inert materials over a few finite-difference zones. These methods are still widely used when the structure of the reaction zone and the build-up to detonation are unimportant. Later detonation models resolved the reaction zone. These models were applied both to performance, particularly as it is affected by the size of the charge, and to situations in which the stimulus was less than that needed for reliable

  11. Electronic defect levels in continuous wave laser annealed silicon metal oxide semiconductor devices

    Science.gov (United States)

    Cervera, M.; Garcia, B. J.; Martinez, J.; Garrido, J.; Piqueras, J.

    1988-09-01

    The effect of laser treatment on the bulk and interface states of the Si-SiO2 structure has been investigated. The annealing was performed prior to the gate metallization using a continuous wave Ar+ laser. For low laser powers the interface state density seems to decrease slightly in comparison with untreated samples. However, for the highest irradiating laser powers a new bulk level at 0.41 eV above the valence band with concentrations up to 1015 cm-3 arises probably due to the electrical activation of the oxygen diluted in the Czochralski silicon. Later postmetallization annealings reduce the interface state density to values in the 1010 cm-2 eV-1 range but leave the concentration of the 0.41-eV center nearly unchanged.

  12. Supersonic Ionization Wave Driven by Radiation Transport in a Short-Pulse Laser-Produced Plasma

    International Nuclear Information System (INIS)

    Ditmire, T.; Gumbrell, E.T.; Smith, R.A.; Mountford, L.; Hutchinson, M.H.

    1996-01-01

    Through the use of an ultrashort (2ps) optical probe, we have time resolved the propagation of an ionization wave into solid fused silica. This ionization wave results when a plasma is created by the intense irradiation of a solid target with a 2ps laser pulse. We find that the velocity of the ionization wave is consistent with radiation driven thermal transport, exceeding the velocity expected from simple electron thermal conduction by nearly an order of magnitude. copyright 1996 The American Physical Society

  13. 30th International Symposium on Shock Waves

    CERN Document Server

    Sadot, Oren; Igra, Ozer

    2017-01-01

    These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...

  14. 532 nm continuous wave mode-locked Nd:GdVO4 laser with SESAM

    International Nuclear Information System (INIS)

    Li, L; Liu, J; Liu, M; Liu, S; Chen, F; Wang, W; Wang, Y

    2009-01-01

    We obtain continuous wave mode-locked Nd:GdVO 4 -KTP laser with a SESAM. This is the first report of CW mode-locked Nd:GdVO 4 -KTP laser with a SESAM to our knowledge. 396 mw CW mode-locked pulse is achieved at the incident power of 7.653 W, with the repetition about 95 MHz. The pulse duration is assumed to be 5.5 ps, this is the shortest green pulse of 532 nm with SESAM

  15. Modulated Sine Waves for Differential Absorption Measurements Using a CW Laser System

    Science.gov (United States)

    Campbell, Joel F. (Inventor); Lin, Bing (Inventor); Nehrir, Amin R. (Inventor)

    2015-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  16. Development of laser-induced grating spectroscopy for underwater temperature measurement in shock wave focusing regions

    Science.gov (United States)

    Gojani, Ardian B.; Danehy, Paul M.; Alderfer, David W.; Saito, Tsutomu; Takayama, Kazuyoshi

    2004-02-01

    In Extracorporeal Shock Wave Lithotripsy (ESWL) underwater shock wave focusing generates high pressures at very short duration of time inside human body. However, it is not yet clear how high temperatures are enhanced at the spot where a shock wave is focused. The estimation of such dynamic temperature enhancements is critical for the evaluation of tissue damages upon shock loading. For this purpose in the Interdisciplinary Shock Wave Research Center a technique is developed which employs laser induced thermal acoustics or Laser Induced Grating Spectroscopy. Unlike most of gas-dynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm 3 and 400 ns, respectively. Preliminary experiments in still water demonstrated that this method detected sound speed and hence temperature in water ranging 283 K to 333 K with errors of 0.5%. These results are used to empirically establish the equation of states of water, gelatin or agar cell which will work as alternatives of human tissues.

  17. Effect of Mixture Pressure and Equivalence Ratio on Detonation Cell Size for Hydrogen-Air Mixtures

    Science.gov (United States)

    2015-06-01

    In order to design combustion chambers for detonating engines, specifically PDEs and RDEs , the cell size is needed. Higher than atmospheric...8 Figure 4. RDE dimensions ................................................................................................ 11...Technology DDT Deflagration to Detonation MAPE Mean Absolute Percent Error PDE Pulsed Detonation Engine RDE Rotating Detonation Engine ZND

  18. Analysis of laser ablation: Contribution of ionization energy to the plasma and shock wave properties

    International Nuclear Information System (INIS)

    Wen, S.-B.; Mao Xianglei; Greif, Ralph; Russo, Richard E.

    2007-01-01

    By fitting simulation results with experimentally measured trajectories of the shock wave and the vapor/background gas contact surface, we found that inclusion of ionization energy in the analysis leads to a change in the evolution of the pressure, mass density, electron number density, and temperature of the vapor plume. The contribution of ionization energy to both the plasma and shock wave has been neglected in most studies of laser ablation. Compared to previous simulations, the densities, pressures, and temperatures are lower shortly after the laser pulse ( 50 ns). The predicted laser energy conversion ratio also showed about a 20% increase (from 35% to 45%) when the ionization energy is considered. The changes in the evolution of the physical quantities result from the retention of the ionization energy in the vapor plume, which is then gradually transformed to kinetic and thermal energies. When ionization energy is included in the simulation, the vapor plume attains higher expansion speeds and temperatures for a longer time after the laser pulse. The better determination of the temperature history of the vapor plume not only improves the understanding of the expansion process of the laser induced vapor plume but also is important for chemical analysis. The accurate temperature history provides supplementary information which enhances the accuracy of chemical analysis based on spectral emission measurements (e.g., laser induced breakdown spectroscopy)

  19. LED provides engineering and electrooptics support to the Laser Program

    International Nuclear Information System (INIS)

    Pehrson, D.

    1985-01-01

    The work of the Laser Engineering Division is reviewed. The division provides engineering and electrooptics support to the laser program. The laser program has been an integral part of the efforts to explore the potential of lasers in harnessing thermonuclear fusion for energy and for defense-related physics studies and in efficiently separating fissile fuels

  20. Unsteady Specific Work and Isentropic Efficiency of a Radial Turbine Driven by Pulsed Detonations

    Science.gov (United States)

    2012-06-14

    rotating detonation combustor RDE = rotating detonation engine SDC = steady deflagration combustor SiC = silicon carbide TDLAS = tunable diode...rotating detonation engine ( RDE ) configuration, illustrated in Fig. 80, has been proposed as an alternative to the axial pulsed detonation tube...arrangement (Bykovskii, et al. 2006; Daniau, et al. 2005; Hayashi, et al. 2009). The RDE contains an annular duct with one open end for exhausting

  1. Sub-parts-per-quadrillion-level graphite furnace atomic absorption spectrophotometry based on laser wave mixing.

    Science.gov (United States)

    Mickadeit, Fritz K; Berniolles, Sandrine; Kemp, Helen R; Tong, William G

    2004-03-15

    Nonlinear laser wave mixing in a common graphite furnace atomizer is presented as a zeptomole-level, sub-Doppler, high-resolution atomic absorption spectrophotometric method. A nonplanar three-dimensional wave-mixing optical setup is used to generate the signal beam in its own space. Signal collection is efficient and convenient using a template-based optical alignment. The graphite furnace atomizer offers advantages including fast and convenient introduction of solid, liquid, or gas analytes, clean atomization environment, and minimum background noise. Taking advantage of the unique features of the wave-mixing optical method and those of the graphite furnace atomizer, one can obtain both excellent spectral resolution and detection sensitivity. A preliminary concentration detection limit of 0.07 parts-per-quadrillion and a preliminary mass detection limit of 0.7 ag or 8 zmol are determined for rubidium using a compact laser diode as the excitation source.

  2. Cavitation and shock waves emission on the rigid boundary of water under mid-IR nanosecond laser pulse excitation

    Science.gov (United States)

    Pushkin, A. V.; Bychkov, A. S.; Karabutov, A. A.; Potemkin, F. V.

    2018-06-01

    The processes of conversion of light energy into mechanical energy under mid-IR nanosecond laser excitation on a rigid boundary of water are investigated. Strong water absorption of Q-switched Cr:Yb:Ho:YSGG (2.85 µm, 6 mJ, 45 ns) laser radiation provides rapid energy deposition of ~8 kJ cm‑3 accompanied with strong mechanical transients. The evolution of shock waves and cavitation bubbles is studied using the technique of shadowgraphy and acoustic measurements, and the conversion efficiency into these energy channels for various laser fluence (0.75–2.0 J cm‑2) is calculated. For 6 mJ laser pulse with fluence of 2.0 J cm‑2, the conversion into shock wave energy reaches 67%. The major part of the shock wave energy (92%) is dissipated when the shock front travels the first 250 µm, and the remaining 8% is transferred to the acoustic far field. The calculated pressure in the vicinity of water-silicon interface is 0.9 GPa. Cavitation efficiency is significantly less and reaches up to 5% of the light energy. The results of the current study could be used in laser parameters optimization for micromachining and biological tissue ablation.

  3. Diode-laser-pumped high efficiency continuous-wave operation at 912 nm laser in Nd:GdVO4 crystal

    International Nuclear Information System (INIS)

    Yu, X; Chen, F; Gao, J; Li, X D; Yan, R P; Zhang, K; Yu, J H; Zhang, Z H

    2009-01-01

    High efficiency operation on continuous-wave (cw) 912 nm laser at room temperature in Nd:GdVO 4 crystal pumped by 808 nm diode-laser is reported in this letter. The maximum output power of 8.0 W was obtained at the incident un-polarized pump power of 47.0 W, giving the corresponding optical-to-optical conversion efficiency of 17.0% and the average slope efficiency of 22.9%. Further tests show that the lasing threshold is reduced and the efficiency is increased evidently when using the π-polarized 808 nm pump source. 4.8 W 912 nm laser was achieved at the polarized pump power of 21.8 W, optical-to-optical conversion efficiency is increased to 22.0% and average slope efficiency is up to 33.6%

  4. Generation of narrow energy spread ion beams via collisionless shock waves using ultra-intense 1 um wavelength laser systems

    Science.gov (United States)

    Albert, Felicie; Pak, A.; Kerr, S.; Lemos, N.; Link, A.; Patel, P.; Pollock, B. B.; Haberberger, D.; Froula, D.; Gauthier, M.; Glenzer, S. H.; Longman, A.; Manzoor, L.; Fedosejevs, R.; Tochitsky, S.; Joshi, C.; Fiuza, F.

    2017-10-01

    In this work, we report on electrostatic collisionless shock wave acceleration experiments that produced proton beams with peak energies between 10-17.5 MeV, with narrow energy spreads between Δ E / E of 10-20%, and with a total number of protons in these peaks of 1e7-1e8. These beams of ions were created by driving an electrostatic collisionless shock wave in a tailored near critical density plasma target using the ultra-intense ps duration Titan laser that operates at a wavelength of 1 um. The near critical density target was produced through the ablation of an initially 0.5 um thick Mylar foil with a separate low intensity laser. A narrow energy spread distribution of carbon / oxygen ions with a similar velocity to the accelerated proton distribution, consistent with the reflection and acceleration of ions from an electrostatic field, was also observed. This work was supported by Lawrence Livermore National Laboratory's Laboratory Directed Research and Development program under project 15-LW-095, and the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA2734.

  5. Surface chemistry of water-dispersed detonation nanodiamonds modified by atmospheric DC plasma afterglow

    Czech Academy of Sciences Publication Activity Database

    Štenclová, Pavla; Celedova, V.; Artemenko, Anna; Jirásek, Vít; Jíra, Jaroslav; Rezek, B.; Kromka, Alexander

    2017-01-01

    Roč. 7, č. 62 (2017), s. 38973-38980 ISSN 2046-2069 R&D Projects: GA ČR GA15-01687S Institutional support: RVO:68378271 Keywords : diamond nanoparticles * explosive detonation * barrier discharge * absorption * oxidation Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.108, year: 2016

  6. Interferometric investigation of shock waves induced by a TEA-CO2 laser produced plasma in air in front of a solid target

    International Nuclear Information System (INIS)

    Apostol, D.; Apostol, I.; Cojocaru, E.; Draganescu, V.; Mihailescu, N.I.; Morjan, I.; Konov, I.V.

    1979-06-01

    The shock waves induced in the surrounding atmosphere by an air plasma were investigated by laser interferometry. The air breakdown plasma was produced by a TEA-CO 2 laser in front of a solid target. The results were compared to the predictions of theory of intense explosions in gases and a good agreement was inferred. It was also determined that the symmetry of the expansion of the initial shock wave is determined by the plasma source shape and, accordingly, depends on the laser power density incident on the target surface. However, for further stages all the shock waves expand spherically. (author)

  7. IMPLODING IGNITION WAVES. I. ONE-DIMENSIONAL ANALYSIS

    International Nuclear Information System (INIS)

    Kushnir, Doron; Waxman, Eli; Livne, Eli

    2012-01-01

    We show that converging spherical and cylindrical shock waves may ignite a detonation wave in a combustible medium, provided the radius at which the shocks become strong exceeds a critical radius, R crit . An approximate analytic expression for R crit is derived for an ideal gas equation of state and a simple (power-law-Arrhenius) reaction law, and shown to reproduce the results of numerical solutions. For typical acetylene-air experiments we find R crit ∼ 100 μm (spherical) and R crit ∼ 1 mm (cylindrical). We suggest that the deflagration to detonation transition (DDT) observed in these systems may be due to converging shocks produced by the turbulent deflagration flow, which reaches sub- (but near) sonic velocities on scales >>R crit . Our suggested mechanism differs from that proposed by Zel'dovich et al., in which a fine-tuned spatial gradient in the chemical induction time is required to be maintained within the turbulent deflagration flow. Our analysis may be readily extended to more complicated equations of state and reaction laws. An order of magnitude estimate of R crit within a white dwarf at the pre-detonation conditions believed to lead to Type Ia supernova explosions is 0.1 km, suggesting that our proposed mechanism may be relevant for DDT initiation in these systems. The relevance of our proposed ignition mechanism to DDT initiation may be tested by both experiments and numerical simulations.

  8. Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.

    Science.gov (United States)

    Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P

    2016-06-01

    We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.

  9. First targeted search for gravitational-wave bursts from core-collapse supernovae in data of first-generation laser interferometer detectors

    NARCIS (Netherlands)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Phythian-Adams, A.T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.T.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, R.D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, M.J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, A.L.S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, J.G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, T.C; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, A.D.; Brown, D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderon; Callister, T. A.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglia, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Baiardi, L. Cerboni; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, D. S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Qian; Chua, S. E.; Chung, E.S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P. -F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corpuz, A.; Corsi, A.; Cortese, S.; Costa, A.C.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, A.L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Debra, D.; Debreczeni, G.; Degallaix, J.; De laurentis, M.; Deleglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.A.; Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Diaz, M. C.; Di Fiore, L.; Giovanni, M.G.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H. -B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, T. M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.M.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.P.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzalez, R.G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Lee-Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.M.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Buffoni-Hall, R.; Hall, E. D.; Hammond, G.L.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, P.J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C. -J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J. -M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, D.H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jimenez-Forteza, F.; Johnson, W.; Jones, I.D.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalmus, P.; Kalogera, V.; Kamaretsos, I.; Kandhasamy, S.; Kang, G.H.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kefelian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.E.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan., S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Krolak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C.H.; Lee, K.H.; Lee, M.H.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Loew, K.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lueck, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marka, S.; Marka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R.M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B.C.; Moore, J.C.; Moraru, D.; Gutierrez Moreno, M.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, S.D.; Mukherjee, S.; Mukund, K. N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P.G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Gutierrez-Neri, M.; Neunzert, A.; Newton-Howes, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J.; Oh, S. H.; Ohme, F.; Oliver, M. B.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.S; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Pereira, R.R.; Perreca, A.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Purrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosinska, D.; Rowan, S.; Ruediger, A.; Ruggi, P.; Ryan, K.A.; Sachdev, P.S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Santamaria, L.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J; Schmidt, P.; Schnabel, R.B.; Schofield, R. M. S.; Schoenbeck, A.; Schreiber, K.E.C.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, M.S.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.M.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, António Dias da; Simakov, D.; Singer, A; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, R. J. E.; Smith, N.D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, J.R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepanczyk, M. J.; Tacca, M.D.; Talukder, D.; Tanner, D. B.; Tapai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, W.R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Toyra, D.; Travasso, F.; Traylor, G.; Trifiro, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.G.; van den Brand, J. F. J.; Van Den Broeck, C.F.F.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasuth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P.J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Vicere, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, MT; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.M.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, D.R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J.L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; Zadrozny, A.; Zangrando, L.; Zanolin, M.; Zendri, J. -P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.

    2016-01-01

    We present results from a search for gravitational-wave bursts coincident with two core-collapse supernovae observed optically in 2007 and 2011. We employ data from the Laser Interferometer Gravitational-wave Observatory (LIGO), the Virgo gravitational-wave observatory, and the GEO 600

  10. Polarization-resolved characterization of plasmon waves supported by an anisotropic metasurface

    DEFF Research Database (Denmark)

    Samusev, Anton; Mukhin, Ivan; Malureanu, Radu

    2017-01-01

    Optical metasurfaces have great potential to form a platform for manipulation of surface waves. A plethora of advanced surface-wave phenomena such as negative refraction, self-collimation and channeling of 2D waves can be realized through on-demand engineering of dispersion properties of a periodic...... metasurface. In this letter, we report on polarization-resolved measurement of dispersion of plasmon waves supported by an anisotropic metasurface. We demonstrate that a subdiffractive array of strongly coupled resonant plasmonic nanoparticles supports both TE and TM plasmon modes at optical frequencies...... polarization degree of freedom for surface waves, our results open new routes for designing planar on-chip devices for surface photonics....

  11. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.; Korneev, Svyatoslav

    2014-01-01

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations

  12. Continuous-wave, single-frequency 229  nm laser source for laser cooling of cadmium atoms.

    Science.gov (United States)

    Kaneda, Yushi; Yarborough, J M; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi

    2016-02-15

    Continuous-wave output at 229 nm for the application of laser cooling of Cd atoms was generated by the fourth harmonic using two successive second-harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56 W of output at 229 nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458 nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By applying a tapered amplifier (TA) as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes Cd111 and Cd113, which are applicable to optical lattice clocks.

  13. Influence of condensation on heat flux and pressure measurements in a detonation-based short-duration facility

    Science.gov (United States)

    Haase, S.; Olivier, H.

    2017-10-01

    Detonation-based short-duration facilities provide hot gas with very high stagnation pressures and temperatures. Due to the short testing time, complex and expensive cooling techniques of the facility walls are not needed. Therefore, they are attractive for economical experimental investigations of high-enthalpy flows such as the flow in a rocket engine. However, cold walls can provoke condensation of the hot combustion gas at the walls. This has already been observed in detonation tubes close behind the detonation wave, resulting in a loss of tube performance. A potential influence of condensation at the wall on the experimental results, like wall heat fluxes and static pressures, has not been considered so far. Therefore, in this study the occurrence of condensation and its influence on local heat flux and pressure measurements has been investigated in the nozzle test section of a short-duration rocket-engine simulation facility. This facility provides hot water vapor with stagnation pressures up to 150 bar and stagnation temperatures up to 3800 K. A simple method has been developed to detect liquid water at the wall without direct optical access to the flow. It is shown experimentally and theoretically that condensation has a remarkable influence on local measurement values. The experimental results indicate that for the elimination of these influences the nozzle wall has to be heated to a certain temperature level, which exclusively depends on the local static pressure.

  14. Computational Study of Thrust Generation from Laser-Driven Blast Wave

    International Nuclear Information System (INIS)

    Ohnishi, Naofumi; Ogino, Yousuke

    2008-01-01

    We have performed axisymmetric simulations in order to investigate the thrust generation resulting from the interference between the projectile and the blast wave produced by a pulsed laser. The results obtained by our numerical code well agree for the pressure history and the momentum coupling coefficient with the experimental data. In such analysis, it is found that the approximate impulse estimated only by the pressure history at the projectile base is difficult to predict the actual one. Since the shock wave rapidly attenuates in low fill pressure, and the interaction with the projectile almost finishes in the shroud, a high momentum coupling coefficient can be achieved unlike the case of high fill pressure in which the projectile experiences the subsequent negative thrust

  15. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect photon bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference - only in that frame is the speed of light isotropic, but also fluctuations/turbulence (gravitational waves in the flow of the dynamical 3-space relative to local systems/observers. So the APOLLO facility can act as an effective "gravitational wave" detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave/turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  16. Fatigue crack localization using laser nonliner wave modulation spectroscopy (LNWMS)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Peipei; Sohn, Hoon [Dept. of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kundu, Tribikram [Dept. of Civil Engineering and Engineering Mechanics, University of Arizona, Tucson (United States)

    2016-12-15

    Nonlinear features of ultrasonic waves are more sensitive to the presence of a fatigue crack than their linear counterparts are. For this reason, the use of nonlinear ultrasonic techniques to detect a fatigue crack at its early stage has been widely investigated. Of the different proposed techniques, laser nonlinear wave modulation spectroscopy (LNWMS) is unique because a pulse laser is used to exert a single broadband input and a noncontact measurement can be performed. Broadband excitation causes a nonlinear source to exhibit modulation at multiple spectral peaks owing to interactions among various input frequency components. A feature called maximum sideband peak count difference(MSPCD), which is extracted from the spectral plot, measures the degree of crack- induced material nonlinearity. First, the ratios of spectral peaks whose amplitudes are above a moving threshold to the total number of peaks are computed for spectral signals obtained from the pristine and the current state of a target structure. Then, the difference of these ratios are computed as a function of the moving threshold. Finally, the MSPCD is defined as the maximum difference between these ratios. The basic premise is that the MSPCD will increase as the nonlinearity of the material increases. This technique has been used successfully for localizing fatigue cracks in metallic plates.

  17. Fatigue crack localization using laser nonlinear wave modulation spectroscopy (LNWMS)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Peipei; Sohn, Hoon [Dept. of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kundu, Tribikram [Dept. of Civil Engineering and Engineering Mechanics, University of Arizona, Tucson (United States)

    2014-12-15

    Nonlinear features of ultrasonic waves are more sensitive to the presence of a fatigue crack than their linear counterparts are. For this reason, the use of nonlinear ultrasonic techniques to detect a fatigue crack at its early stage has been widely investigated. Of the different proposed techniques, laser nonlinear wave modulation spectroscopy (LNWMS) is unique because a pulse laser is used to exert a single broadband input and a noncontact measurement can be performed. Broadband excitation causes a nonlinear source to exhibit modulation at multiple spectral peaks owing to interactions among various input frequency components. A feature called maximum sideband peak count difference (MSPCD), which is extracted from the spectral plot, measures the degree of crack-induced material nonlinearity. First, the ratios of spectral peaks whose amplitudes are above a moving threshold to the total number of peaks are computed for spectral signals obtained from the pristine and the current state of a target structure. Then, the difference of these ratios are computed as a function of the moving threshold. Finally, the MSPCD is defined as the maximum difference between these ratios. The basic premise is that the MSPCD will increase as the nonlinearity of the material increases. This technique has been used successfully for localizing fatigue cracks in metallic plates.

  18. Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gravity wave detection using space-based long-baseline laser interferometric sensors imposes stringent noise requirements on the system components, including the...

  19. Theoretical study of the influence of intense femtosecond laser field on the evolution of the wave packet and the population of NaRb molecule

    International Nuclear Information System (INIS)

    Ning, Ma; Mei-Shan, Wang; Chuan-Lu, Yang; Xiao-Guang, Ma; De-Hua, Wang

    2010-01-01

    Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the population of ground and double-minimum electronic states of the NaRb molecule. For the different laser wavelengths, the evolution of the wave packet of 6 1 σ + state with time and internuclear distance is different, and the different laser intensity brings different influences on the population of the electronic states of the NaRb molecule. One can control the evolutions of wave packet and the population in each state by varying the laser parameters appropriately, which will be a benefit for the light manipulation of atomic and molecular processes. (atomic and molecular physics)

  20. The analysis of thermal stability of detonation nanodiamond

    International Nuclear Information System (INIS)

    Efremov, V P; Zakatilova, E I

    2016-01-01

    The detonation nanodiamond is a new perspective material. Ammunition recycling with use of high explosives and obtaining nanodiamond as the result of the detonation synthesis have given a new motivation for searching of their application areas. In this work nanodiamond powder has been investigated by the method of synchronous thermal analysis. Experiments have been carried out at atmospheric pressure in the environment of argon. Nanodiamond powder has been heated in the closed corundum crucible at the temperature range of 30-1500 °C. The heating rates were varied from 2 K/min to 20 K/min. After the heat treatment, the samples have been studied by the x-ray diffraction and the electron microscopy. As one of the results of this work, it has been found that the detonation nanodiamond has not started the transition into graphite at the temperature below 800 °C. (paper)