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Sample records for fast ignition relevant

  1. Electron Generation and Transport in Intense Relativistic Laser-Plasma Interactions Relevant to Fast Ignition ICF

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tammy Yee Wing [Univ. of California, San Diego, CA (United States)

    2010-01-01

    The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.

  2. Enhanced Model for Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Rodney J. [Research Applications Corporation, Los Alamos, NM (United States)

    2010-10-12

    Laser Fusion is a prime candidate for alternate energy production, capable of serving a major portion of the nation's energy needs, once fusion fuel can be readily ignited. Fast Ignition may well speed achievement of this goal, by reducing net demands on laser pulse energy and timing precision. However, Fast Ignition has presented a major challenge to modeling. This project has enhanced the computer code ePLAS for the simulation of the many specialized phenomena, which arise with Fast Ignition. The improved code has helped researchers to understand better the consequences of laser absorption, energy transport, and laser target hydrodynamics. ePLAS uses efficient implicit methods to acquire solutions for the electromagnetic fields that govern the accelerations of electrons and ions in targets. In many cases, the code implements fluid modeling for these components. These combined features, "implicitness and fluid modeling," can greatly facilitate calculations, permitting the rapid scoping and evaluation of experiments. ePLAS can be used on PCs, Macs and Linux machines, providing researchers and students with rapid results. This project has improved the treatment of electromagnetics, hydrodynamics, and atomic physics in the code. It has simplified output graphics, and provided new input that avoids the need for source code access by users. The improved code can now aid university, business and national laboratory users in pursuit of an early path to success with Fast Ignition.

  3. Fusion ignition via a magnetically-assisted fast ignition approach

    CERN Document Server

    Wang, W -M; Sheng, Z -M; Li, Y T; Zhang, J

    2016-01-01

    Significant progress has been made towards laser-driven fusion ignition via different schemes, including direct and indirect central ignition, fast ignition, shock ignition, and impact ignition schemes. However, to reach ignition conditions, there are still various technical and physical challenges to be solved for all these schemes. Here, our multi-dimensional integrated simulation shows that the fast-ignition conditions could be achieved when two 2.8 petawatt heating laser pulses counter-propagate along a 3.5 kilotesla external magnetic field. Within a period of 5 picoseconds, the laser pulses heat a nuclear fuel to reach the ignition conditions. Furthermore, we present the parameter windows of lasers and magnetic fields required for ignition for experimental test.

  4. Isochoric implosions for fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D S; Tabak, M

    2006-06-05

    Fast Ignition (FI) exploits the ignition of a dense, uniform fuel assembly by an external energy source to achieve high gain. In conventional ICF implosions, however, the fuel assembles as a dense shell surrounding a low density, high-pressure hotspot. Such configurations are far from optimal for FI. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942).] may be employed to implode a dense, quasi-uniform fuel assembly with minimal energy wastage in forming a hotspot. A scheme for realizing these specialized implosions in a practical ICF target is also described.

  5. Laser-plasma interactions for fast ignition

    CERN Document Server

    Kemp, A J; Debayle, A; Johzaki, T; Mori, W B; Patel, P K; Sentoku, Y; Silva, L O

    2013-01-01

    In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the compa...

  6. Isochoric Implosions for Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D S; Tabak, M

    2007-04-04

    Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hot spot ignition counterpart [e.g., S. Atzeni, Phys. Plasmas 6, 3316 (1999); M. Tabak et al., Fusion Sci. & Technology 49, 254 (2006)]. These gain models, however, all assume nearly uniform-density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942)] may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g=cm{sup 3} and areal density of 2.4 g=cm{sup 2} using 485 kJ of laser energy.

  7. Role of fast ignitor in fast-shock ignition concept

    Directory of Open Access Journals (Sweden)

    S. A. Ghasemi

    2014-03-01

    Full Text Available This paper deals with the role of fast ignitor in fast-shock ignition (FSI concept. The semi-analytical model indicates that the FSI target gain is a function of fast ignitor laser wavelength. If the energy of fast ignitor driver is and the laser wavelength is less than 0.53 micron, then with a fuel mass about 2 mg the FSI has a considerable advantage over pure shock ignition and the figure of merit is better than 1.2. When the wavelength of fast ignitor becomes shorter, the approaches , and for wavelengths shorter than 0.25 micron no additional is advantage is obtained.

  8. Theory of Fast Electron Transport for Fast Ignition

    CERN Document Server

    Robinson, A P L; Davies, J R; Gremillet, L; Honrubia, J J; Johzaki, T; Kingham, R J; Sherlock, M; Solodov, A A

    2013-01-01

    Fast Ignition Inertial Confinement Fusion is a variant of inertial fusion in which DT fuel is first compressed to high density and then ignited by a relativistic electron beam generated by a fast (< 20 ps) ultra-intense laser pulse, which is usually brought in to the dense plasma via the inclusion of a re-entrant cone. The transport of this beam from the cone apex into the dense fuel is a critical part of this scheme, as it can strongly influence the overall energetics. Here we review progress in the theory and numerical simulation of fast electron transport in the context of Fast Ignition. Important aspects of the basic plasma physics, descriptions of the numerical methods used, a review of ignition-scale simulations, and a survey of schemes for controlling the propagation of fast electrons are included. Considerable progress has taken place in this area, but the development of a robust, high-gain FI `point design' is still an ongoing challenge.

  9. Fast Ignition Experimental and Theoretical Studies

    Energy Technology Data Exchange (ETDEWEB)

    Akli, Kramer Ugerthen [Univ. of California, Davis, CA (United States)

    2006-01-01

    We are becoming dependent on energy more today than we were a century ago, and with increasing world population and booming economies, sooner or later our energy sources will be exhausted. Moreover, our economy and welfare strongly depends on foreign oil and in the shadow of political uncertainties, there is an urgent need for a reliable, safe, and cheap energy source. Thermonuclear fusion, if achieved, is that source of energy which not only will satisfy our demand for today but also for centuries to come. Today, there are two major approaches to achieve fusion: magnetic confinement fusion (MFE) and inertial confinement fusion (ICF). This dissertation explores the inertial confinement fusion using the fast ignition concept. Unlike the conventional approach where the same laser is used for compression and ignition, in fast ignition separate laser beams are used. This dissertation addresses three very important topics to fast ignition inertial confinement fusion. These are laser-to-electron coupling efficiency, laser-generated electron beam transport, and the associated isochoric heating. First, an integrated fast ignition experiment is carried out with 0.9 kJ of energy in the compression beam and 70 J in the ignition beam. Measurements of absolute Kα yield from the imploded core revealed that about 17% of the laser energy is coupled to the suprathermal electrons. Modeling of the transport of these electrons and the associated isochoric heating, with the previously determined laser-to-electron conversion efficiency, showed a maximum target temperature of 166 eV at the front where the electron flux is higher and the density is lower. The contribution of the potential, induced by charge separation, in opposing the motion of the electrons was moderate. Second, temperature sensitivity of Cu Kα imaging efficiency using a spherical Bragg reflecting crystal is investigated. It was found that due to the shifting and broadening of the K

  10. Implosion Hydrodynamics of Fast Ignition Targets

    Science.gov (United States)

    Stephens, R. B.

    2004-11-01

    The fast ignition (FI) concept requires the generation of a compact, dense, pure fuel mass accessible to an external ignition source. The current baseline FI target is a shell fitted with a reentrant cone extending to near its center. Conventional direct or indirect drive collapses the shell near the tip of the cone and then an ultra-intense laser pulse focused to the inside cone tip generates high-energy electrons to ignite the dense fuel. We have theoretically and experimentally investigated the collapse of such targets, validating modeling and exploring the tradeoffs available, in such an asymmetric geometry, to optimize compaction of the fuel and maintain the integrity of the cone. The collapse is complex. Away from the cone, the shell collapses much as does a conventional implosion, generating a hot, low-density inner core. But because of the open side this hot plasma exhausts out toward the tip of the cone. This hot plasma is advantageous for implosion diagnostics; it can provide protons for angular dependent measurements of the shell wall, neutrons for temperature measurements, and self-emission for contamination measurements. But the hot spot must be controlled; for FI it is a liability. The hot, low-density inner core simply impedes the collapse of the cold fuel, lowering the implosion/burn efficiency and the gain while making ignition more difficult. We discuss approaches to minimizing this effect and experimental tests.

  11. Implosion hydrodynamics of fast ignition targetsa)

    Science.gov (United States)

    Stephens, R. B.; Hatchett, S. P.; Tabak, M.; Stoeckl, C.; Shiraga, H.; Fujioka, S.; Bonino, M.; Nikroo, A.; Petrasso, R.; Sangster, T. C.; Smith, J.; Tanaka, K. A.

    2005-05-01

    The fast ignition (FI) concept requires the generation of a compact, dense, pure fuel mass accessible to an external ignition source. The current base line FI target is a shell fitted with a reentrant cone extending to near its center. Conventional direct- or indirect-drive collapses the shell near the tip of the cone and then an ultraintense laser pulse focused to the inside cone tip generates high-energy electrons to ignite the dense fuel. A theoretical and experimental investigation was undertaken of the collapse of such targets, validating modeling, and exploring the trade-offs available, in such an asymmetric geometry, to optimize compaction of the fuel and maintain the integrity of the cone. The collapse is complex. Away from the cone, the shell collapses much as does a conventional implosion, generating a hot, low-density inner core. But because of the open side, hot plasma exhausts out toward the tip of the cone. This hot plasma is advantageous for implosion diagnostics; it can provide protons for angular dependent measurements of the shell wall, neutrons for temperature measurements, and self-emission for contamination measurements. But for FI it is a liability; the hot, low-density inner core impedes the compaction of the cold fuel, lowering the implosion/burn efficiency and the gain. Approaches to optimizing this shell design are discussed.

  12. Status and Prospects of the Fast Ignition Inertial Fusion Concept

    Energy Technology Data Exchange (ETDEWEB)

    Key, M H

    2006-11-15

    Fast ignition is an alternate concept in inertial confinement fusion, which has the potential for easier ignition and greater energy multiplication. If realized it could improve the prospects for inertial fusion energy. It poses stimulating challenges in science and technology and the research is approaching a key stage in which the feasibility of fast ignition will be determined. This review covers the concepts, the state of the science and technology, the near term prospects and the challenges and risks involved in demonstrating high gain fast ignition.

  13. Advanced Concept Exploration for Fast Ignition Science Program, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Richard Burnite [General Atomics; McLean, Harry M. [Lawrence Livermore National Laboratory; Theobald, Wolfgang [Laboratory for Laser Energetics; Akli, Kramer U. [The Ohio State University; Beg, Farhat N. [University of California, San Diego; Sentoku, Yasuhiko [University of Nevada, Reno; Schumacher, Douglass W. [The Ohio State University; Wei, Mingsheng [General Atomics

    2013-09-04

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional “central hot spot” (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10’s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The physics of fast ignition process was the focus of our Advanced Concept Exploration (ACE) program. Ignition depends critically on two major issues involving Relativistic High Energy Density (RHED) physics: The laser-induced creation of fast electrons and their propagation in high-density plasmas. Our program has developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to advance understanding of the fundamental physics underlying these issues. Our program had three thrust areas: • Understand the production and characteristics of fast electrons resulting from FI relevant laser-plasma interactions and their dependence on laser prepulse and laser pulse length. • Investigate the subsequent fast electron transport in solid and through hot (FI-relevant) plasmas. • Conduct and understand integrated core-heating experiments by comparison to simulations. Over the whole period of this project (three years for this contract), we have greatly advanced our fundamental understanding of the underlying properties in all three areas: • Comprehensive studies on fast electron source characteristics have shown that they are controlled by the laser intensity distribution and the topology and plasma density gradient. Laser pre-pulse induced pre-plasma in front of a solid surface results in increased stand-off distances from the electron origin to the high density

  14. Fast-ignition heavy-ion fusion target by jet impact

    Energy Technology Data Exchange (ETDEWEB)

    Velarde, P. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/ Jose Gutierrez Abascal, 2. 28006 Madrid (Spain)]. E-mail: pedro@din.upm.es; Ogando, F. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/ Jose Gutierrez Abascal, 2. 28006 Madrid (Spain); Universidad Nacional de Educacion a Distancia (Spain); Eliezer, S. [Soreq Nuclear Research Center (Israel); Martinez-Val, J.M. [Soreq Nuclear Research Center (Israel)

    2005-05-21

    A new target design for HIF, based on the fast-ignition principles, is proposed. Unlike the previous designs proposed so far, in this case just one energy source is needed to drive the whole process to ignition. The ultra-fast deposition of energy onto the compressed core is produced in this case by hypervelocity jets generated during the process. The collision of jets converts their kinetic energy into thermal energy of the nuclear fuel, which is expected to produce ignition under proper design. The process is studied in this paper, describing its most relevant features like jet production and later collision.

  15. Liquid Cryogenic Target Development for Fast Ignition*

    Science.gov (United States)

    Hanson, D. L.; Russell, C.; Vesey, R. A.; Schroen, D. G.; Taylor, J. L.; Back, C. A.; Steinman, D.; Nikroo, A.; Kaae, J. L.; Giraldez, E.; Johnston, R. R.; Youngman, K.

    2007-11-01

    As an alternative to foam-stabilized cryogenic solid D-T fuel layers for indirect-drive fast ignitor targets, which will tend to β-layer to a nonuniform distribution in a reentrant cone geometry [1], we are investigating hemispherical cryogenic fast ignition capsules with a liquid fuel layer confined between a thick outer ablator shell and a thin inner shell [2]. The shape and surface quality of the fuel layer is determined entirely by the characteristics of the bounding shells. In the present design, structural support for the thin (4.5 um) hemispherical GDP inner shell is provided by a mounting ring. Fabrication of stronger thin Be hemi-shells is also being investigated. Technology issues for liquid cryogenic fuel capsule development and progress toward demonstration of a working target will be presented. [1] J.K. Hoffer et al., Fusion Sci. Technol. 50, 15 (2006). [2] D.L. Hanson et al., Fusion Sci. Technol. 49, 500 (2006). *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. Experimental investigation to demonstrate Impact Fast Ignition scheme

    Energy Technology Data Exchange (ETDEWEB)

    Watari, T; Azechi, H; Nakai, M; Hironaka, Y; Sakaiya, T; Nakamura, H; Shiraga, H; Shigemori, K; Hosoda, H; Arikawa, Y; Homma, H; Norimatsu, T; Murakami, M; Jhozaki, T [Institute of Laser Engineering, Osaka univ. (Japan); M, Karasik; J, Gardner; J, Bates; D, Colombant, E-mail: twatari@ile.osaka-u.ac.j [Naval Research Laboratory, Washington DC (United States)

    2010-08-01

    We have proposed a new ignition scheme of Fast Ignition, called 'Impact Fast Ignition (IFI)', in which a compressed fuel is ignited by impact collision of a fragment of separately imploded fuel. We performed integrated experiments on impact ignition, in which a portion of a deuterated polystyrene (CD) shell was accelerated to about 600 km/s and was collided with precompressed CD fuel. The shell was imploded using 9 beams and the impactor was accelerated using 3 beams of the GEKKO XII laser system. The laser energy was 350 J per beam. The kinetic energy of the impactor was efficiently converted into thermal energy generating a temperature of about 1.8 keV., Observed maximum neutron yield was 2x10{sup 6}. This yield was 80 times as large as that without impactor. We will present the experimental details and results, demonstrating the high potential of impact ignition for fusion energy production.

  17. Assessment of Potential for Ion Driven Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Logan, B. Grant; Bangerter, Roger O.; Callahan, Debra A.; Tabak,Max; Roth, Markus; Perkins, L. John; Caporaso, George

    2005-05-01

    Critical issues and ion beam requirements are explored for fast ignition using ion beams to provide fuel compression using indirect drive and to provide separate short pulse ignition heating using direct drive. Several ion species with different hohlraum geometries are considered for both accelerator-produced and laser-produced ion ignition beams. Ion-driven fast ignition targets are projected to have modestly higher gains than with conventional heavy-ion fusion, and may offer some other advantages for target fabrication and for use of advanced fuels. However, much more analysis and experiments are needed before conclusions can be drawn regarding the feasibility for meeting the ion beam transverse and longitudinal emittances, focal spots, pulse lengths, and target stand-off distances required for ion-driven fast ignition.

  18. Assessment of Potential for Ion Driven Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Logan, B. Grant; Bangerter, Roger O.; Callahan, Debra A.; Tabak, Max; Roth, Markus; Perkins, L. John; Caporaso, George

    2004-12-01

    Critical issues and ion beam requirements are explored for fast ignition using ion beams to provide fuel compression using indirect drive and to provide separate short pulse ignition heating using direct drive. Several ion species with different hohlraum geometries are considered for both accelerator-produced and laser-produced ion ignition beams. Ion-driven fast ignition targets are projected to have modestly higher gains than with conventional heavy-ion fusion, and may offer some other advantages for target fabrication and for use of advanced fuels. However, much more analysis and experiments are needed before conclusions can be drawn regarding the feasibility for meeting the ion beam transverse and longitudinal emittances, focal spots, pulse lengths, and target standoff distances required for ion-driven fast ignition.

  19. Heat wave fast ignition in inertial confinement energy

    Institute of Scientific and Technical Information of China (English)

    Shalom; Eliezer; Shirly; Vinikman; Pinhasi

    2013-01-01

    An accelerated micro-foil is used to ignite a pre-compressed cylindrical shell containing deuterium–tritium fuel.The well-known shock wave ignition criterion and a novel criterion based on heat wave ignition are developed in this work.It is shown that for heat ignition very high impact velocities are required.It is suggested that a multi-petawatt laser can accelerate a micro-foil to relativistic velocities in a very short time duration(picosecond)of the laser pulse.The cylindrical geometry suggested here for the fast ignition approach has the advantage of geometrically separating the nanosecond lasers that compress the target from the picosecond laser that accelerates the foil.The present model suggests that nuclear fusion by micro-foil impact ignition could be attained with currently existing technology.

  20. Impact of Fast Ignition on Laser Fusion Energy Development

    Science.gov (United States)

    Mirna, Kunioki

    2016-10-01

    Reviewed are the early history of Japanese laser fusion research and the recent achievement of fast ignition research at Institute of Laser Engineering (ILE), Osaka University. After the achievement of high density compression at Osaka University, LLE of University Rochester, and LLNL, the critical issue of Inertial Fusion Energy (IFE) research became the formation of hot spark in a compressed plasma. In this lecture, the history of the fast ignition research will be reviewed and future prospects are presented.

  1. Radiation Driven Capsules for Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, M; Slutz, S A

    2001-06-08

    The energy required to ignite compressed deuterium-tritium fuel is a strong function of the fuel density. Through a series of detailed numerical simulations, peak fuel densities have been calculated as a function of the peak radiation drive temperature. Note that the time dependence of the radiation temperature (pulse shaping) has been optimized to obtain maximum density for each scaling point. A simple analytic scaling is developed, which agrees well with the numerical results. These scaling results are then used to obtain the required ignition energy as a function of peak drive temperature.

  2. Studies of Electron Transport and Isochoric Heating and Their Applicability to Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Key, M H; Amiranoff, F; Andersen, C; Batani, D; Baton, S D; Cowan, T; Fisch, N; Freeman, R; Gremillet, L; Hall, T; Hatchett, S; Hill, J; King, J; Kodama, R; Koch, J; Koenig, M; Lasinski, B; Langdon, B; MacKinnon, A; Martinolli, E; Norreys, P; Parks, P; Perrelli-Cippo, E; Rabec Le Gloahec, M; Rosenbluth, M; Rousseaux, C; Santon, J J; Scianitti, F; Snavely, R; Tabak, M; Tanaka, K; Town, R; Tsutumi, T; Stephens, R

    2003-10-30

    Experimental measurements of electron transport and isochoric heating in 100 J, 1 ps laser irradiation of solid A1 targets are presented. Modeling with a hybrid PIC code is compared with the data and good agreement is obtained using a heuristic model for the electron injection. The relevance for fast ignition is discussed.

  3. Advanced Concept Exploration for Fast Ignition Science Program, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Richard Burnite [General Atomics; McLean, Harry M. [Lawrence Livermore National Laboratory; Theobald, Wolfgang [Laboratory for Laser Energetics; Akli, Kramer U. [The Ohio State University; Beg, Farhat N. [University of California, San Diego; Sentoku, Yasuhiko [University of Nevada, Reno; Schumacher, Douglass W. [The Ohio State University; Wei, Mingsheng [General Atomics

    2013-09-04

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional “central hot spot” (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10’s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The physics of fast ignition process was the focus of our Advanced Concept Exploration (ACE) program. Ignition depends critically on two major issues involving Relativistic High Energy Density (RHED) physics: The laser-induced creation of fast electrons and their propagation in high-density plasmas. Our program has developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to advance understanding of the fundamental physics underlying these issues. Our program had three thrust areas: • Understand the production and characteristics of fast electrons resulting from FI relevant laser-plasma interactions and their dependence on laser prepulse and laser pulse length. • Investigate the subsequent fast electron transport in solid and through hot (FI-relevant) plasmas. • Conduct and understand integrated core-heating experiments by comparison to simulations. Over the whole period of this project (three years for this contract), we have greatly advanced our fundamental understanding of the underlying properties in all three areas: • Comprehensive studies on fast electron source characteristics have shown that they are controlled by the laser intensity distribution and the topology and plasma density gradient. Laser pre-pulse induced pre-plasma in front of a solid surface results in increased stand-off distances from the electron origin to the high density

  4. Cone-guided fast ignition with no imposed magnetic fields

    Directory of Open Access Journals (Sweden)

    Strozzi D.

    2013-11-01

    Full Text Available Simulations are presented of ignition-scale fast ignition targets with the integrated Zuma-Hydra PIC-hydrodynamic capability. We consider a spherical DT fuel assembly with a carbon cone, and an artificially-collimated fast electron source. We study the role of E and B fields and the fast electron energy spectrum. For mono-energetic 1.5 MeV fast electrons, without E and B fields, ignition can be achieved with fast electron energy Efig = 30kJ. This is 3.5× the minimal deposited ignition energy of 8.7 kJ for our fuel density of 450 g/cm3. Including E and B fields with the resistive Ohm's law E = ηJb gives Efig = 20kJ, while using the full Ohm's law gives Efig > 40 kJ. This is due to magnetic self-guiding in the former case, and ∇n ×∇T magnetic fields in the latter. Using a realistic, quasi two-temperature energy spectrum derived from PIC laser-plasma simulations increases Efig to (102, 81, 162 kJ for (no E/B, E = ηJb, full Ohm's law. Such electrons are too energetic to stop in the optimal hot spot depth.

  5. Simulations of electron transport for fast ignition using Lisp

    Energy Technology Data Exchange (ETDEWEB)

    Town, R.P.J. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States)]. E-mail: town2@llnl.gov; Chen, C. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Cottrill, L.A. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Key, M.H. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Kruer, W.L. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Langdon, A.B. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Lasinski, B.F. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Snavely, R.A. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Still, C.H. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Tabak, M. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States); Welch, D.R. [Mission Research Corp., 5001 Indian School Rd NE, Albuquerque, NM 87110-3946 (United States); Wilks, S.C. [Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, CA 94550-9234 (United States)

    2005-05-21

    A crucial issue for the viability of the fast ignition approach to inertial fusion energy is the transport of the ignition pulse energy from the critical surface to the high-density compressed fuel. Experiments have characterized this transport through the interaction of short pulse, high intensity lasers with solid-density targets containing thin K{alpha} fluorescence layers. These experiments show a reasonably well-collimated beam, although with a significantly larger radius than the incident laser beam. We report on LSP calculations of these experiments, which show reasonable agreement with the experimental observations.

  6. Ion beam requirements for fast ignition of inertial fusion targets

    CERN Document Server

    Honrubia, J J

    2015-01-01

    Ion beam requirements for fast ignition are investigated by numerical simulation taking into account new effects such as ion beam divergence not included before. We assume that ions are generated by the TNSA scheme in a curved foil placed inside a re-entrant cone and focused on the cone apex or beyond. From the focusing point to the compressed core ions propagate with a given divergence angle. Ignition energies are obtained for two compressed fuel configurations heated by proton and carbon ion beams. The dependence of the ignition energies on the beam divergence angle and on the position of the ion beam focusing point have been analysed. Comparison between TNSA and quasi-monoenergetic ions is also shown.

  7. Power deposition of deuteron beam in fast ignition

    Science.gov (United States)

    Azadifar, R.; Mahdavi, M.

    2017-02-01

    In ion fast ignition (FI) inertial confinement fusion (ICF), a laser accelerated ion beam called igniter provides energy required for ignition of a fuel pellet. The laser accelerated deuteron beam is considered as igniter. The deuteron beam with Maxwellian energy distribution produced at the distance d = 500 μm, from fuel surface, travels during time t = 20 ps and arrives with power P1D(t,TD) to the fuel surface. Then, the deuteron beam deposits its energy into fuel by Coulomb and nuclear interactions with background plasma particles during time t = 10 ps, with power P2D(t,TD,Tb). Since time and power of the two stages have same order, to calculate the total power deposited by igniter beam, both stages must be considered simultaneously. In this paper, the exact power of each stage has been calculated separately, and the total power Ptotal(t,TD,Tb) has been obtained. The obtained results show that the total power deposition Ptotal(t,TD,Tb) is significantly reduced due to reducing different temperature between projectile and target particles.

  8. Simulation analysis for ion assisted fast ignition using structured targets

    Science.gov (United States)

    Sakagami, H.; Johzaki, T.; Sunahara, A.; Nagatomo, H.

    2016-05-01

    As the heating efficiency by fast electrons in the fast ignition scheme is estimated to be very low due to their large divergence angle and high energy. To mitigate this problem, low-density plastic foam, which can generate not only proton (H+) but also carbon (C6+) beams, can be introduced to currently used cone-guided targets and additional core heating by ions is expected. According to 2D PIC simulations, it is found that the ion beams also diverge by the static electric field and concave surface deformation. Thus structured targets are suggested to optimize ion beam characteristics, and their improvement and core heating enhancement by ion beams are confirmed.

  9. Studies of electron and proton isochoric heating for fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Mackinnon, A; Key, M; Akli, K; Beg, F; Clarke, R; Clarke, D; Chen, M; Chung, H; Chen, S; Freeman, R; Green, J; Gu, P; Gregori, G; Highbarger, K; Habara, H; Hatchett, S; Hey, D; Heathcote, R; Hill, J; King, J; Kodama, R; Koch, J; Lancaster, K; Langdon, B; Murphy, C; Norreys, P; Neely, D; Nakatsutsumi, M; Nakamura, H; Patel, N; Patel, P; Pasley, J; Snavley, R; Stephens, R; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Tanaka, K; Tempo, M; Toley, M; Town, R; Wilks, S; VanWoerkom, L; Weber, R; Yabuuchi, T; Zhang, B

    2006-10-02

    Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu K{alpha} fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced K{alpha}. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed.

  10. Fast ignition integrated experiments and high-gain point design

    Energy Technology Data Exchange (ETDEWEB)

    Shiraga, H. [Osaka Univ., Osaka (Japan); Nagatomo, H. [Osaka Univ., Osaka (Japan); Theobald, W. [Univ. of Rochester, Rochester, NY (United States); Solodov, A. A. [Univ. of Rochester, Rochester, NY (United States); Tabak, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-04-17

    Here, integrated fast ignition experiments were performed at ILE, Osaka, and LLE, Rochester, in which a nanosecond driver laser implodes a deuterated plastic shell in front of the tip of a hollow metal cone and an intense ultrashort-pulse laser is injected through the cone to heat the compressed plasma. Based on the initial successful results of fast electron heating of cone-in-shell targets, large-energy short-pulse laser beam lines were constructed and became operational: OMEGA-EP at Rochester and LFEX at Osaka. Neutron enhancement due to heating with a ~kJ short-pulse laser has been demonstrated in the integrated experiments at Osaka and Rochester. The neutron yields are being analyzed by comparing the experimental results with simulations. Details of the fast electron beam transport and the electron energy deposition in the imploded fuel plasma are complicated and further studies are imperative. The hydrodynamics of the implosion was studied including the interaction of the imploded core plasma with the cone tip. Theory and simulation studies are presented on the hydrodynamics of a high-gain target for a fast ignition point design.

  11. A Concept Exploration Program in Fast Ignition Inertial Fusion — Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Richarad Burnite [General Atomics; Freeman, Richard R. [The Ohio State University; Van Woekom, L. D. [The Ohio State University; Key, M. [Lawrence Livermore National Laboratory; MacKinnon, Andrew J. [Lawrence Livermore National Laboratory; Wei, Mingsheng [General Atomics

    2014-02-27

    The Fast Ignition (FI) approach to Inertial Confinement Fusion (ICF) holds particular promise for fusion energy because the independently generated compression and ignition pulses allow ignition with less compression, resulting in (potentially) higher gain. Exploiting this concept effectively requires an understanding of the transport of electrons in prototypical geometries and at relevant densities and temperatures. Our consortium, which included General Atomics (GA), The Ohio State University (OSU), the University of California, San Diego (UCSD), University of California, Davis (UC-Davis), and Princeton University under this grant (~$850K/yr) and Lawrence Livermore National Laboratory (LLNL) under a companion grant, won awards in 2000, renewed in 2005, to investigate the physics of electron injection and transport relevant to the FI concept, which is crucial to understand electron transport in integral FI targets. In the last two years we have also been preparing diagnostics and starting to extend the work to electron transport into hot targets. A complementary effort, the Advanced Concept Exploration (ACE) program for Fast Ignition, was funded starting in 2006 to integrate this understanding into ignition schemes specifically suitable for the initial fast ignition attempts on OMEGA and National Ignition Facility (NIF), and during that time these two programs have been managed as a coordinated effort. This result of our 7+ years of effort has been substantial. Utilizing collaborations to access the most capable laser facilities around the world, we have developed an understanding that was summarized in a Fusion Science & Technology 2006, Special Issue on Fast Ignition. The author lists in the 20 articles in that issue are dominated by our group (we are first authors in four of them). Our group has published, or submitted 67 articles, including 1 in Nature, 2 Nature Physics, 10 Physical Review Letters, 8 Review of Scientific Instruments, and has been invited to

  12. Elliptical Magnetic Mirror generated via Resistivity Gradients for Fast Ignition ICF

    CERN Document Server

    Robinson, A P L

    2013-01-01

    The elliptical magnetic mirror scheme for guiding fast electrons for Fast Ignition proposed by Schmitz (H.Schmitz et al., {\\it Plasma Phys.Control.Fusion},{\\bf 54} 085016 (2012)) is studied for conditions on the multi-kJ scale which are much closer to full-scale Fast Ignition. When scaled up, the elliptical mirror scheme is still highly beneficial to Fast Ignition. An increase in the coupling effiency by a factor of 3--4 is found over a wide range of fast electron divergence half-angles.

  13. Design of a cone target for fast ignition

    Directory of Open Access Journals (Sweden)

    Sunahara Atsushi

    2013-11-01

    Full Text Available We propose a new type of target for the fast ignition of inertial confinement fusion. Pre-formed plasma inside a cone target can significantly reduce the energy coupling efficiency from the ultra-high intense short-pulse laser to the imploded core plasma. Also, in order to protect the tip of the cone and reduce generation of pre-formed plasma, we propose pointed shaped cone target. In our estimation, the shock traveling time can be delayed 20–30 ps by lower-Z material with larger areal density compared to the conventional gold flat tip. Also, the jet flow can sweep the blow-off plasma from the tip of the cone, and the implosion performance is not drastically affected by the existence of pointed tip. In addition, the self-generated magnetic field is generated along the boundary of cone tip and surrounding CD or DT plasma. This magnetic field can confine fast electrons and focus to the implosion core plasma. Resultant heating efficiency is improved by 30% compared to that with conventional gold flat tip.

  14. Fast Ignition and Stable Combustion of Coarse Coal Particles in a Nonslagging Cyclone Combustor

    Institute of Scientific and Technical Information of China (English)

    BiaoZhou; X.L.Wang; 等

    1995-01-01

    A combustion set-up of an innovative nonalagging cyclone combustor called “Spouting-Cyclone Combustor(SCC)”,,with two-stage combustion,organized in orthogonal vortex flows,was established and the experimental studies on the fast ignition and stable combustion of coarse coal particles in this combustor were carried out.The flame temperature versus ignition time and the practical fast ignition the temperature fields in SCC were obtained.These results whow that it is possible to obtain highly efficient and clean combustion of unground coal particles by using this technology.

  15. Fast Ignition and Sustained Combustion of Ionic Liquids

    Science.gov (United States)

    Joshi, Prakash B. (Inventor); Piper, Lawrence G. (Inventor); Oakes, David B. (Inventor); Sabourin, Justin L. (Inventor); Hicks, Adam J. (Inventor); Green, B. David (Inventor); Tsinberg, Anait (Inventor); Dokhan, Allan (Inventor)

    2016-01-01

    A catalyst free method of igniting an ionic liquid is provided. The method can include mixing a liquid hypergol with a HAN (Hydroxylammonium nitrate)-based ionic liquid to ignite the HAN-based ionic liquid in the absence of a catalyst. The HAN-based ionic liquid and the liquid hypergol can be injected into a combustion chamber. The HAN-based ionic liquid and the liquid hypergol can impinge upon a stagnation plate positioned at top portion of the combustion chamber.

  16. Planar Laser-Plasma Interaction Experiments at Direct-Drive Ignition-Relevant Scale Lengths at the National Ignition Facility

    Science.gov (United States)

    Rosenberg, M. J.; Solodov, A. A.; Seka, W.; Myatt, J. F.; Regan, S. P.; Hohenberger, M.; Epstein, R.; Froula, D. H.; Radha, P. B.; Michel, P. A.; Moody, J. D.; Masse, L.; Goyon, C.; Turnbull, D. P.; Barrios, M. A.; Bates, J. W.; Schmitt, A. J.

    2016-10-01

    The first experiments at the National Ignition Facility to probe laser-plasma interactions and the hot electron production at scale lengths relevant to direct-drive ignition are reported. The irradiation on one side of planar CH foils generated a plasma at the quarter-critical surface with predicted density scale lengths of Ln 600 μm, measured electron temperatures of Te 3.5 to 4.0 keV, and overlapped laser intensities of I 6 to 15 ×1014W/cm2. Optical emission from stimulated Raman scattering (SRS) and at ω/2 are correlated with the time-dependent hard x-ray signal. The fraction of laser energy converted to hot electrons increased from 0.5 % to 2.3 % as the laser intensity increased from 6 to 15 ×1014W/cm2, while the hot electron temperature was nearly constant around 40 to 50 keV. Only a sharp red-shifted feature is observed around ω/2, and both refracted and sidescattered SRS are detected, suggesting that multibeam SRS contributes to, and may even dominate, hot-electron production. These results imply a diminished presence of two-plasmon decay relative to SRS at these conditions, which has implications for hot-electron preheat mitigation strategies for direct-drive ignition. This work is supported by the DOE NNSA under Award Number DE-NA0001944.

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

    Science.gov (United States)

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

    2013-12-01

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

  18. Neutron, electron and photon transport in ICF tragets in direct and fast ignition

    Directory of Open Access Journals (Sweden)

    A. Parvazian

    2005-12-01

    Full Text Available Fusion energy due to inertial confinement has progressed in the last few decades. In order to increase energy efficiency in this method various designs have been presented. The standard scheme for direct ignition and fast ignition fuel targets are considered. Neutrons, electrons and photons transport in targets containing different combinations of Li and Be are calculated in both direct and fast ignition schemes. To compress spherical multilayer targets having fuel in the central part, they are irradiated by laser or heavy ion beams. Neutrons energy deposition in the target is considered using Monte Carlo method code MCNP. A significant amount of neutrons energy is deposited in the target which resulted in growing fusion reactions rates. It is found that Beryllium compared to Lithium is more important. In an introductory consideration of relativistic electron beam transport into central part of a fast ignition target, we have calculated electron energy deposition in highly dense D-T fuel and Beryllium layer of the target. It has been concluded that a fast ignition scheme is preferred to direct ignition because of the absence of hydrodynamic instability.

  19. Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets

    Science.gov (United States)

    Jarrott, L. C.; Wei, M. S.; McGuffey, C.; Solodov, A. A.; Theobald, W.; Qiao, B.; Stoeckl, C.; Betti, R.; Chen, H.; Delettrez, J.; Döppner, T.; Giraldez, E. M.; Glebov, V. Y.; Habara, H.; Iwawaki, T.; Key, M. H.; Luo, R. W.; Marshall, F. J.; McLean, H. S.; Mileham, C.; Patel, P. K.; Santos, J. J.; Sawada, H.; Stephens, R. B.; Yabuuchi, T.; Beg, F. N.

    2016-05-01

    Recent progress in kilojoule-scale high-intensity lasers has opened up new areas of research in radiography, laboratory astrophysics, high-energy-density physics, and fast-ignition (FI) laser fusion. FI requires efficient heating of pre-compressed high-density fuel by an intense relativistic electron beam produced from laser-matter interaction. Understanding the details of electron beam generation and transport is crucial for FI. Here we report on the first visualization of fast electron spatial energy deposition in a laser-compressed cone-in-shell FI target, facilitated by doping the shell with copper and imaging the K-shell radiation. Multi-scale simulations accompanying the experiments clearly show the location of fast electrons and reveal key parameters affecting energy coupling. The approach provides a more direct way to infer energy coupling and guide experimental designs that significantly improve the laser-to-core coupling to 7%. Our findings lay the groundwork for further improving efficiency, with 15% energy coupling predicted in FI experiments using an existing megajoule-scale laser driver.

  20. Fast-ignition design transport studies: realistic electron source, integrated PIC-hydrodynamics, imposed magnetic fields

    CERN Document Server

    Strozzi, D J; Larson, D J; Divol, L; Kemp, A J; Bellei, C; Marinak, M M; Key, M H

    2012-01-01

    Transport modeling of idealized, cone-guided fast ignition targets indicates the severe challenge posed by fast-electron source divergence. The hybrid particle-in-cell [PIC] code Zuma is run in tandem with the radiation-hydrodynamics code Hydra to model fast-electron propagation, fuel heating, and thermonuclear burn. The fast electron source is based on a 3D explicit-PIC laser-plasma simulation with the PSC code. This shows a quasi two-temperature energy spectrum, and a divergent angle spectrum (average velocity-space polar angle of 52 degrees). Transport simulations with the PIC-based divergence do not ignite for > 1 MJ of fast-electron energy, for a modest 70 micron standoff distance from fast-electron injection to the dense fuel. However, artificially collimating the source gives an ignition energy of 132 kJ. To mitigate the divergence, we consider imposed axial magnetic fields. Uniform fields ~50 MG are sufficient to recover the artificially collimated ignition energy. Experiments at the Omega laser facil...

  1. Studying of Laser Plasma Physics Related With Fast Ignition of ICF

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fast ignition(FI) concept of ICF is one of the most attractive application of high intensity ultrashort laser. The UV light has some advantages for applying to fast ignition, the first, as the I λ2 scaling law of hot electron temperature, at the FI required intensity(1020 W/cm2), the long wavelength light will generate >10 MeV electron that can not deposit energy efficiently in the fuel region. Meanwhile the UV light can just generate the electron with the required energy of 1 MeV.

  2. Effect of laser wavelength and intensity on the divergence of hot electrons in fast ignition

    Science.gov (United States)

    Li, Boyuan; Tian, Chao; Zhang, Zhimeng; Zhang, Feng; Shan, Lianqiang; Zhang, Bo; Zhou, Weimin; Zhang, Baohan; Gu, Yuqiu

    2016-09-01

    Recently, the short wavelength laser is believed to have a promising prospect in fast ignition for reducing the conflict between laser energy requirement and electron stopping range. Here we investigate the influence of laser wavelength and intensity in the angular dispersion of hot electrons. Both our theoretical model and numerical simulations show that the angular dispersion would increase rapidly with the shortening of laser wavelength due to the Weibel instability, while the laser intensity has little effect on it. These results have important implications for fast ignition.

  3. Modeling Laser-Plasma Interactions at Direct-Drive Ignition-Relevant Plasma Conditions at the National Ignition Facility

    Science.gov (United States)

    Solodov, A. A.; Rosenberg, M. J.; Myatt, J. F.; Epstein, R.; Seka, W.; Hohenberger, M.; Short, R. W.; Shaw, J. G.; Regan, S. P.; Froula, D. H.; Radha, P. B.; Bates, J. W.; Schmitt, A. J.; Michel, P.; Moody, J. D.; Ralph, J. E.; Turnbull, D. P.; Barrios, M. A.

    2016-10-01

    Laser-plasma interaction instabilities, such as two-plasmon decay (TPD) and stimulated Raman scattering (SRS), can be detrimental for direct-drive inertial confinement fusion because of target preheat by generated high-energy electrons. The radiation-hydrodynamics code DRACO has been used to design planar-target experiments that generate plasma and interaction conditions relevant to direct-drive-ignition designs (IL 1015 W / cm 2 , Te > 3 KeV density gradient scale lengths of Ln 600 μm) . The hot-electron temperature of 40to50keV and the fraction of laser energy converted to hot electrons of 0.5to were inferred based on comparing the simulated and experimentally observed x-ray emission when the laser intensity at the quarter-critical surface increased from 6 to 15 ×1014 W / cm 2 . The measured SRS energy was sufficient to explain the observed total energy in hot electrons. Implications for ignition-scale direct-drive experiments and hot-electron preheat mitigation using mid- Z ablators will be discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  4. Spray ignition measurements in a constant volume combustion vessel under engine-relevant conditions

    Science.gov (United States)

    Ramesh, Varun

    Pressure-based and optical diagnostics for ignition delay (ID) measurement of a diesel spray from a multi-hole nozzle were investigated in a constant volume combustion vessel (CVCV) at conditions similar to those in a conventional diesel engine at the start of injection (SOI). It was first hypothesized that compared to an engine, the shorter ID in a CVCV was caused by NO, a byproduct of premixed combustion. The presence of a significant concentration of NO+NO2 was confirmed experimentally and by using a multi-zone model of premixed combustion. Experiments measuring the effect of NO on ID were performed at conditions relevant to a conventional diesel engine. Depending on the temperature regime and the nature of the fuel, NO addition was found to advance or retard ignition. Constant volume ignition simulations were capable of describing the observed trends; the magnitudes were different due to the physical processes involved in spray ignition, not modeled in the current study. The results of the study showed that ID is sensitive to low NO concentrations (<100 PPM) in the low-temperature regime. A second source of uncertainty in pressure-based ID measurement is the systematic error associated with the correction used to account for the speed of sound. Simultaneous measurements of volumetric OH chemiluminescence (OHC) and pressure during spray ignition found the OHC to closely resemble the pressure-based heat release rate for the full combustion duration. The start of OHC was always found to be shorter than the pressure-based ID for all fuels and conditions tested by 100 ms. Experiments were also conducted measuring the location and timing of high-temperature ignition and the steady-state lift-off length by high-speed imaging of OHC during spray ignition. The delay period calculated using the measured ignition location and the bulk average speed of sound was in agreement with the delay between OHC and the pressure-based ID. Results of the study show that start of OHC

  5. Three dimensional filamentary structures of a relativistic electron beam in Fast Ignition plasmas

    CERN Document Server

    Karmakar, Anupam; Pukhov, Alexander

    2008-01-01

    The filamentary structures and associated electromagnetic fields of a relativistic electron beam have been studied by three dimensional particle-in-cell (PIC) simulations in the context of Fast Ignition fusion. The simulations explicitly include collisions in return plasma current and distinctly examine the effects of beam temperature and collisions on the growth of filamentary structures generated.

  6. Proton Beam Fast Ignition Fusion: Synergy of Weibel and Rayleigh-Taylor Instabilities

    Science.gov (United States)

    Stefan, V. Alexander

    2011-04-01

    The proton beam generation and focusing in fast ignition inertial confinement fusion is studied. The spatial and energy spread of the proton beam generated in a laser-solid interaction is increased due to the synergy of Weibel and Rayleigh-Taylor instabilities. The focal spot radius can reach 100 μm, which is nearly an order of magnitude larger than the optimal value. The energy spread decreases the beam deposition energy in the focal spot. Under these conditions, ignition of a precompressed DT fuel is achieved with the beam powers much higher than the values presently in consideration. Work supported in part by NIKOLA TESLA Laboratories (Stefan University), La Jolla, CA.

  7. Integrated fast ignition simulation of cone-guided target with three codes

    Energy Technology Data Exchange (ETDEWEB)

    Sakagami, H. [Hyogo Univ., Computer Engineering, Himeji, Hyogo (Japan); Johzaki, T.; Nagatomo, H.; Mima, K. [Osaka Univ., Institute of Laser Engineering, Suita, Osaka (Japan)

    2004-07-01

    It was reported that the fuel core was heated up to {approx} 0.8 keV in the fast ignition experiments with cone-guided targets, but they could not theoretically explain heating mechanisms and achievement of such high temperature. Thus simulations should play an important role in estimating the scheme performance, and we must simulate each phenomenon with individual codes and integrate them under the Fast Ignition Integrated Interconnecting code project. In the previous integrated simulations, fast electrons generated by the laser-plasma interaction were too hot to efficiently heat the core and we got only a 0.096 keV temperature rise. Including the density gap at the contact surface between the cone tip and the imploded plasma, the period of core heating became longer and the core was heated by 0.162 keV, about 69% higher increment compared with ignoring the density gap effect. (authors)

  8. X-ray Spectroscopic Characterization of Shock-Ignition-Relevant plasmas

    Directory of Open Access Journals (Sweden)

    Michal Šmíd

    2013-01-01

    Full Text Available Experiments with multilayer plastic/Cu targets performed at a PALS laser system aimed at the study of matter at conditions relevant to a shock ignition ICF scheme, and, in particular, at the investigation of hot electrons generation. Plasma temperature and density were obtained using high-resolution X-ray spectroscopy. 2D-spatially resolved quasi–monochromatic imaging was observing the hot electrons via fluorescence K emission in the copper tracer layer. Found values of plasma temperature 690 ± 10 eV, electron density 3 × 1022 cm-3 and the effective energy of hot electrons 45 ± 20 keV demonstrate the potential of X-ray methods in the characterization of the shock ignition environmental conditions.

  9. Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

    Directory of Open Access Journals (Sweden)

    A Parvazian

    2010-12-01

    Full Text Available Fast ignition is a new method for inertial confinement fusion (ICF in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion (MTF. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0. 25 and 0. 5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. MTF in dual hot spot can be considered as an appropriate substitution for the current ICF techniques.

  10. Generation of high pressure shocks relevant to the shock-ignition intensity regime

    Science.gov (United States)

    Batani, D.; Antonelli, L.; Atzeni, S.; Badziak, J.; Baffigi, F.; Chodukowski, T.; Consoli, F.; Cristoforetti, G.; De Angelis, R.; Dudzak, R.; Folpini, G.; Giuffrida, L.; Gizzi, L. A.; Kalinowska, Z.; Koester, P.; Krousky, E.; Krus, M.; Labate, L.; Levato, T.; Maheut, Y.; Malka, G.; Margarone, D.; Marocchino, A.; Nejdl, J.; Nicolai, Ph.; O'Dell, T.; Pisarczyk, T.; Renner, O.; Rhee, Y. J.; Ribeyre, X.; Richetta, M.; Rosinski, M.; Sawicka, M.; Schiavi, A.; Skala, J.; Smid, M.; Spindloe, Ch.; Ullschmied, J.; Velyhan, A.; Vinci, T.

    2014-03-01

    An experiment was performed using the PALS laser to study laser-target coupling and laser-plasma interaction in an intensity regime ≤1016 W/cm2, relevant for the "shock ignition" approach to Inertial Confinement Fusion. A first beam at low intensity was used to create an extended preformed plasma, and a second one to create a strong shock. Pressures up to 90 Megabars were inferred. Our results show the importance of the details of energy transport in the overdense region.

  11. Control of Electron Beam Using Strong Magnetic Field for Efficient Core Heating in Fast Ignition

    CERN Document Server

    Johzaki, T; Sentoku, Y; Sunahara, A; Nagatomo, H; Sakagami, H; Mima, K; Fujioka, S; Shiraga, H

    2014-01-01

    For enhancing the core heating efficiency in electron-driven fast ignition, we proposed the fast electron beam guiding using externally applied longitudinal magnetic fields. Based on the PIC simulations for the FIREX-class experiments, we demonstrated the sufficient beam guiding performance in the collisional dense plasma by kT-class external magnetic fields for the case with moderate mirror ratio (~<10 ). Boring of the mirror field was found through the formation of magnetic pipe structure due to the resistive effects, which indicates a possibility of beam guiding in high mirror field for higher laser intensity and/or longer pulse duration.

  12. Energy deposition of quasi-two temperature relativistic electrons in fast-shock ignition scenario

    Science.gov (United States)

    Ghasemi, Seyed Abolfazl; Farahbod, Amir Hossein

    2016-10-01

    Previous calculations from Solodov et al. (2008) indicate that classical stopping and scattering dominate electrons energy deposition and transport when the electrons reach the dense plasma in FSI inertial confinement fusion concept [1]. Our calculations show that, by using quasi- two temperature electrons energy distribution function [2] in comparison with exponential [3] or monoenergetic distribution function and also increasing fast electrons energy to about 7 MeV, the ratio of beam blooming to straggling definitely decreases. Our analytical analysis shows that for fuel mass more than 1 mg and for fast ignitor wavelength λif > 0.53 μ m, straggling and beam blooming increases. Meanwhile, by reducing fast ignitor wavelength from 0.53 to 0.35 micron, and for fuel mass about 2 mg, electron penetration into the dense fuel slightly increases. Therefore, reduction of scattering (blooming and straggling) of electrons and enhancement of electron penetration into the dense fuel, can be obtained in relativistic regime with high energy fast electrons of the order of 5 Mev and more. Such derivations can be used in theoretical studies of the ignition conditions and PIC simulations of the electron transport in fast ignition scenario.

  13. Deuterium–tritium catalytic reaction in fast ignition: Optimum parameters approach

    Indian Academy of Sciences (India)

    B Khanbabaei; A Ghasemizad; S Khoshbinfar

    2014-09-01

    One of the main concerns about the currentworking on nuclear power reactors is the potential hazard of their radioactive waste. There is hope that this issue will be reduced in next generation nuclear fusion power reactors. Reactors will release nuclear energy through microexplosions that occur in a mixture of hydrogen isotopes of deuterium and tritium. However, there exist radiological hazards due to the accumulation of tritium in the blanket layer. A catalytic fusion reaction of DT mixture may stand between DD and an equimolar DT approach in which the fusion process continues with a small amount of tritium seed. In this paper, we investigate the possibility of DT reaction in the fast ignition (FI) scheme. The kinematic study of the main mechanism of the energy gain–loss term, which may disturb the ignition and burn process, was performed in FI and the optimum values of precompressed fuel and proton beam driver were derived. The recommended values of fuel parameters are: areal density $ρ R ≥ 5\\cdot$cm-2 and initial tritium fraction ≤ 0.025. For the proton beam, the corresponding optimum interval values are proton average energy $3≤ E_p ≤ 10$ MeV, pulse duration $5 ≤ t_p ≤ 15$ ps and power $5≤ W_p ≤ 12 × 10^{22}$ (keV$\\cdot$cm3$\\cdot$ps-1). It was proved that under the above conditions, a fast ignition DT reaction stays in the catalytic regime.

  14. Three-dimensional fast electron transport for ignition-scale inertial fusion capsules

    CERN Document Server

    Honrubia, J J

    2006-01-01

    Three-dimensional hybrid PIC simulations are presented to study electron energy transport and deposition in a full-scale fast ignition configuration. Multi-prong core heating close to ignition is found when a few GA, few PW beam is injected. Resistive beam filamentation in the corona seeds the 3D current pattern that penetrates the core. Ohmic heating is important in the low-density corona, while classical Coulomb deposition heats the core. Here highest energy densities (few Tbar at 10 keV) are observed at densities above 200 g/cc. Energy coupling to the core ranges from 20 to 30%; it is enhanced by beam collimation and decreases when raising the beam particle energy from 1.5 to 5.5 MeV.

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

    Science.gov (United States)

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

    2014-05-01

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

  16. Fast Ignition Thermonuclear Fusion: Enhancement of the Pellet Gain by the Colossal-Magnetic-Field Shells

    Science.gov (United States)

    Stefan, V. Alexander

    2013-10-01

    The fast ignition fusion pellet gain can be enhanced by a laser generated B-field shell. The B-field shell, (similar to Earth's B-field, but with the alternating B-poles), follows the pellet compression in a frozen-in B-field regime. A properly designed laser-pellet coupling can lead to the generation of a B-field shell, (up to 100 MG), which inhibits electron thermal transport and confines the alpha-particles. In principle, a pellet gain of few-100s can be achieved in this manner. Supported in part by Nikola Tesla Labs, Stefan University, 1010 Pearl, La Jolla, CA 92038-1007.

  17. Final Project Report "Advanced Concept Exploration For Fast Ignition Science Program"

    Energy Technology Data Exchange (ETDEWEB)

    STEPHENS, Richard B.; McLEAN, Harry M.; THEOBALD, Wolfgang; AKLI, Kramer; BEG, Farhat N.; SENTOKU, Yasuiko; SCHUMACHER, Douglas; WEI, Mingsheng S.

    2014-01-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy (IFE) reactors. FI differs from conventional “central hot spot” (CHS) target ignition by decoupling compression from heating: using the laser (or heavy ion beam or Z pinch) drive pulse (10’s of ns) to create a dense fuel and a second, much shorter (~10 ps) high intensity pulse to ignite a small region of it. There are two major physics issues concerning this concept; controlling the laser-induced generation of large electron currents and their propagation through high density plasmas. This project has addressed these two significant scientific issues in Relativistic High Energy Density (RHED) physics. Learning to control relativistic laser matter interaction (and the limits and potential thereof) will enable a wide range of applications. While these physics issues are of specific interest to inertial fusion energy science, they are also important for a wide range of other HED phenomena, including high energy ion beam generation, isochoric heating of materials, and the development of high brightness x-ray sources. Generating, controlling, and understanding the extreme conditions needed to advance this science has proved to be challenging: Our studies have pushed the boundaries of physics understanding and are at the very limits of experimental, diagnostic, and simulation capabilities in high energy density laboratory physics (HEDLP). Our research strategy has been based on pursuing the fundamental physics underlying the Fast Ignition (FI) concept. We have performed comprehensive study of electron generation and transport in fast-ignition targets with experiments, theory, and numerical modeling. A major issue is that the electrons produced in these experiments cannot be measured directly—only effects due to their transport. We focused mainly on x-ray continuum photons from bremsstrahlung

  18. Integrated simulation of magnetic-field-assist fast ignition laser fusion

    Science.gov (United States)

    Johzaki, T.; Nagatomo, H.; Sunahara, A.; Sentoku, Y.; Sakagami, H.; Hata, M.; Taguchi, T.; Mima, K.; Kai, Y.; Ajimi, D.; Isoda, T.; Endo, T.; Yogo, A.; Arikawa, Y.; Fujioka, S.; Shiraga, H.; Azechi, H.

    2017-01-01

    To enhance the core heating efficiency in fast ignition laser fusion, the concept of relativistic electron beam guiding by external magnetic fields was evaluated by integrated simulations for FIREX class targets. For the cone-attached shell target case, the core heating performance deteriorates by applying magnetic fields since the core is considerably deformed and most of the fast electrons are reflected due to the magnetic mirror formed through the implosion. On the other hand, in the case of a cone-attached solid ball target, the implosion is more stable under the kilo-tesla-class magnetic field. In addition, feasible magnetic field configuration is formed through the implosion. As a result, the core heating efficiency doubles by magnetic guiding. The dependence of core heating properties on the heating pulse shot timing was also investigated for the solid ball target.

  19. Integrated simulation of magnetic-field-assist fast ignition laser fusion

    CERN Document Server

    Johzaki, T; Sunahara, A; Sakagami, Y Sentoku H; Hata, M; Taguchi, T; Mima, K; Kai, Y; Ajimi, D; Endo, T; Yogo, A; Arikawa, Y; Fujioka, S; Shiraga, H; Azechi, H

    2016-01-01

    To enhance the core heating efficiency in fast ignition laser fusion, the concept of relativistic electron beam guiding by external magnetic fields was evaluated by integrated simulations for FIREX class targets. For the cone-attached shell target case, the core heating performance is deteriorated by applying magnetic fields since the core is considerably deformed and the most of the fast electrons are reflected due to the magnetic mirror formed through the implosion. On the other hand, in the case of cone-attached solid ball target, the implosion is more stable under the kilo-tesla-class magnetic field. In addition, feasible magnetic field configuration is formed through the implosion. As the results, the core heating efficiency becomes double by magnetic guiding. The dependence of core heating properties on the heating pulse shot timing was also investigated for the solid ball target.

  20. Diffusion of external magnetic fields into the cone-in-shell target in the fast ignition

    Science.gov (United States)

    Sunahara, Atsushi; Johzaki, Tomoyui; Nagatomo, Hideo; Sakata, Shouhei; Matsuo, Kazuki; Lee, Seungho; Fujioka, Shinsuke; Shiraga, Hiroyuki; Azechi, Hiroshi; Firex-Project Team

    2016-10-01

    We simulated the diffusion of externally applied magnetic fields into cone-in-shell target in the fast ignition. In this ignition scheme, the externally magnetic fields up to kilo-Tesla is used to guide fast electrons to the high-dense imploded core, and understanding diffusion of the magnetic field is one of the key issues for increasing the coupling efficiency from the heating laser to the imploded core. In order to study the magnetic field, we have developed 2D cylindrical Maxwell equation solver with Ohm's law, and carried out simulations of diffusion of externally applied magnetic fields into a cone-in-shell target. Also, we estimated the conductivity of the cone and shell target based on the assumption of Saha-ionization equilibrium. We present our results of diffusion of magnetic fields. We also show that the target is heated by the eddy current. Because of the density and temperature dependence of the conductivity, the magnetic fields diffuse into the material with varying conductivity. Consequently, the magnetic fields into the cone-in-shell target depend on the temporal profile of the magnetic fields as well as the electrical and thermal properties of the material.

  1. Implosion and heating experiments of fast ignition targets by Gekko-XII and LFEX lasers

    Directory of Open Access Journals (Sweden)

    Shiraga H.

    2013-11-01

    Full Text Available The FIREX-1 project, the goal of which is to demonstrate fuel heating up to 5 keV by fast ignition scheme, has been carried out since 2003 including construction and tuning of LFEX laser and integrated experiments. Implosion and heating experiment of Fast Ignition targets have been performed since 2009 with Gekko-XII and LFEX lasers. A deuterated polystyrene shell target was imploded with the 0.53- μm Gekko-XII, and the 1.053- μm beam of the LFEX laser was injected through a gold cone attached to the shell to generate hot electrons to heat the imploded fuel plasma. Pulse contrast ratio of the LFEX beam was significantly improved. Also a variety of plasma diagnostic instruments were developed to be compatible with harsh environment of intense hard x-rays (γ rays and electromagnetic pulses due to the intense LFEX beam on the target. Large background signals around the DD neutron signal in time-of-flight record of neutron detector were found to consist of neutrons via (γ,n reactions and scattered gamma rays. Enhanced neutron yield was confirmed by carefully eliminating such backgrounds. Neutron enhancement up to 3.5 × 107 was observed. Heating efficiency was estimated to be 10–20% assuming a uniform temperature rise model.

  2. Limitation on Pre-pulse Level for Cone-Guided Fast-Ignition ICF

    Energy Technology Data Exchange (ETDEWEB)

    MacPhee, A G; Akli, K U; Beg, F N; Chen, C D; Chen, H; Divol, L; Hey, D S; Freeman, R R; Henesian, M; Kemp, A J; Key, M H; Pape, S L; Link, A; Ma, T; Mackinnon, A J; Ovchinnikov, V M; Patel, P K; Phillips, T W; Stephens, R B; Tabak, M; Town, R; Van Woerkom, L D; Wei, M S; Wilks, S C

    2009-09-01

    The viability of fast-ignition (FI) inertial confinement fusion hinges on the efficient transfer of laser energy to the compressed fuel via multi-MeV electrons. Pre-formed plasma due to laser pre-pulse strongly influences ultra-intense laser plasma interactions and hot electron generation in the hollow cone of an FI target. We induced a prepulse and consequent preplasma in copper cone targets and measured the energy deposition zone of the main pulse by imaging the emitted K{sub {alpha}} radiation. An integrated simulation of radiation hydrodynamics for the pre-plasma and particle in cell for the main pulse interactions agree well with the measured deposition zones and provide an insight into the enrgy deposition mechanism and electron distribution. It was demonstrated that a under these conditions a 100mJ pre-pulse completely eliminates the forward going component of {approx}2-4MeV electrons. Consequences for cone-guided fast-ignition are discussed.

  3. WO21.3 Direct Drive Reentrant Cone Targets for Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, R B; Nikroo, A; Hill, D; Smith, J N Jr.; Hatchett, S P; Stoeckl, C; Bonino, M J; Sangster, T C; Shiraga, H; Fujioka, S; Tanaka, K A

    2003-08-23

    Targets designed for fast ignition must have clear access for the ignitor laser to the compressed core. This is provided in current concepts by embedding a reentrant cone in the shell, the tip of the cone close to the center of the shell. We have designed a gas-tight direct-drive FI target as the first step in developing a FI ignition target, and have studied its implosion dynamics at Omega with back-lit and self-emission framing cameras. A step in the cone surface, and Al on the shell was required to make the assembly gas-tight; these assemblies withstood >10 atm and had a typical pressure half-life of 2-6 hrs. The implosion of these targets was substantially different from that of previous indirect drive targets; there was much less vaporization of the Au cone, much clearer structure in the collapsing shells, and a possibility that the hot core could escape around the cone rather than punch in its tip. Additionally self-emission images show the heating of the core gas, and its effect on the cone tip. These results will be compared to simulations.

  4. Electron energy deposition to the fusion target core for fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W M; Sheng, Z M; Li, Y T; Hao, B; Zhang, J [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China); Norreys, P A; Sherlock, M; Trines, R; Robinson, A P L, E-mail: hbwwml@aphy.iphy.ac.e, E-mail: tzmsheng@sjtu.edu.c [Central Laser Facility, CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom)

    2010-08-01

    Heating of the target core for fast ignition by electron beams is investigated by two-dimensional collisional particle-in-cell simulations. It is found that the electron beams emitted from the core surface with the initial energy of 1.4MeV, 2.4MeV, and 4.2MeV can heat most efficiently the core with {rho}r = 0.75g/cm{sup 2}, 1.5g/cm{sup 2}, and 3g/cm{sup 2}, respectively, when taking {rho} = 300g/cm{sup 3}, where {rho} and r are the mass density and radius of the core, respectively.

  5. Hole boring in a DT Pellet and Fast-Ion Ignition with Ultraintense Laser Pulses.

    Science.gov (United States)

    Naumova, N; Schlegel, T; Tikhonchuk, V T; Labaune, C; Sokolov, I V; Mourou, G

    2009-01-16

    Recently achieved high intensities of short laser pulses open new prospects in their application to hole boring in inhomogeneous overdense plasmas and for ignition in precompressed DT fusion targets. A simple analytical model and numerical simulations demonstrate that pulses with intensities exceeding 10;{22} W/cm;{2} may penetrate deeply into the plasma as a result of efficient ponderomotive acceleration of ions in the forward direction. The penetration depth as big as hundreds of microns depends on the laser fluence, which has to exceed a few tens of GJ/cm;{2}. The fast ions, accelerated at the bottom of the channel with an efficiency of more than 20%, show a high directionality and may heat the precompressed target core to fusion conditions.

  6. Enhanced hole boring with two-color relativistic laser pulses in the fast ignition scheme

    Science.gov (United States)

    Yu, Changhai; Deng, Aihua; Tian, Ye; Li, Wentao; Wang, Wentao; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Liu, Jiansheng

    2016-08-01

    A scheme of using two-color laser pulses for hole boring into overdense plasma as well as energy transfer into electron and ion beams has been studied using particle-in-cell simulations. Following an ultra-short ultra-intense hole-boring laser pulse with a short central wavelength in extreme ultra-violet range, the main infrared driving laser pulse can be guided in the hollow channel preformed by the former laser and propagate much deeper into an overdense plasma, as compared to the case using the infrared laser only. In addition to efficiently transferring the main driving laser energy into energetic electrons and ions generation deep inside the overdense plasma, the ion beam divergence can be greatly reduced. The results might be beneficial for the fast ignition concept of inertial confinement fusion.

  7. The status of Fast Ignition Realization Experiment (FIREX) and prospects for inertial fusion energy

    Science.gov (United States)

    Azechi, H.; FIREX Project Team

    2016-05-01

    Here we report recent progress for the fast ignition inertial confinement fusion demonstration. The fraction of low energy (heats the fuel core, increases by a factor of 4 by enhancing pulse contrast of heating laser and removing preformed plasma sources. Kilo-tesla magnetic field is studied to guide the diverging REB to the fuel core. The transport simulation of the REB accelerated by the heating laser in the externally applied and compressed magnetic field indicates that the REB can be guided efficiently to the fuel core. The integrated simulation shows > 4% of the heating efficiency and > 4 keV of ion temperature are achievable by using GEKKO-XII and LFEX, properly designed cone-fuel and an external magnetic field.

  8. High-resolution X-ray imaging in fast ignition experiment using Gekko and LFEX lasers

    Directory of Open Access Journals (Sweden)

    Koga M.

    2013-11-01

    Full Text Available We improved diagnostic instruments to measure X-ray images in a hard X-ray harsh environment and succeeded in obtaining clear images with X-ray framing camera and X-ray streak camera in fast ignition experiment conducted in 2011 (FG-02 Experimental Campaign. We found that high-energy X-ray signals could be used as an indicator of the LFEX laser injection time relative to the imploded core. The LFEX laser injection time was estimated with better than 10 ps accuracy. Time-resolved 2D X-ray images suggested that shapes and motions of imploded core plasmas were improved by changing the configuration of the implosion lasers.

  9. Final Project Report "Advanced Concept Exploration For Fast Ignition Science Program"

    Energy Technology Data Exchange (ETDEWEB)

    STEPHENS, Richard B.; McLEAN, Harry M.; THEOBALD, Wolfgang; AKLI, Kramer; BEG, Farhat N.; SENTOKU, Yasuiko; SCHUMACHER, Douglas; WEI, Mingsheng S.

    2014-01-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy (IFE) reactors. FI differs from conventional “central hot spot” (CHS) target ignition by decoupling compression from heating: using the laser (or heavy ion beam or Z pinch) drive pulse (10’s of ns) to create a dense fuel and a second, much shorter (~10 ps) high intensity pulse to ignite a small region of it. There are two major physics issues concerning this concept; controlling the laser-induced generation of large electron currents and their propagation through high density plasmas. This project has addressed these two significant scientific issues in Relativistic High Energy Density (RHED) physics. Learning to control relativistic laser matter interaction (and the limits and potential thereof) will enable a wide range of applications. While these physics issues are of specific interest to inertial fusion energy science, they are also important for a wide range of other HED phenomena, including high energy ion beam generation, isochoric heating of materials, and the development of high brightness x-ray sources. Generating, controlling, and understanding the extreme conditions needed to advance this science has proved to be challenging: Our studies have pushed the boundaries of physics understanding and are at the very limits of experimental, diagnostic, and simulation capabilities in high energy density laboratory physics (HEDLP). Our research strategy has been based on pursuing the fundamental physics underlying the Fast Ignition (FI) concept. We have performed comprehensive study of electron generation and transport in fast-ignition targets with experiments, theory, and numerical modeling. A major issue is that the electrons produced in these experiments cannot be measured directly—only effects due to their transport. We focused mainly on x-ray continuum photons from bremsstrahlung

  10. Ion acceleration by petawatt class laser pulses and pellet compression in a fast ignition scenario

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C. [Dipartimento di Fisica, Universita di Bologna, INFN sezione di Bologna (Italy)], E-mail: benedetti@bo.infn.it; Londrillo, P. [Dipartimento di Astronomia, Universita di Bologna, INAF sezione di Bologna, INFN sezione di Bologna (Italy); Liseykina, T.V. [Institute for Computational Technologies, SD-RAS, Novosibirsk (Russian Federation); Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Macchi, A. [polyLAB, CNR-INFM, Pisa (Italy); Sgattoni, A.; Turchetti, G. [Dipartimento di Fisica, Universita di Bologna, INFN sezione di Bologna (Italy)

    2009-07-11

    Ion drivers based on standard acceleration techniques have faced up to now several difficulties. We consider here a conceptual alternative to more standard schemes, such as HIDIF (Heavy Ion Driven Inertial Fusion), which are still beyond the present state of the art of particle accelerators, even though the requirements on the total beam energy are lowered by fast ignition scenarios. The new generation of petawatt class lasers open new possibilities: acceleration of electrons or protons for the fast ignition and eventually light or heavy ions acceleration for compression. The pulses of chirped pulse amplification (CPA) lasers allow ions acceleration with very high efficiency at reachable intensities (I{approx}10{sup 21}W/cm{sup 2}), if circularly polarized light is used since we enter in the radiation pressure acceleration (RPA) regime. We analyze the possibility of accelerating carbon ion bunches by interaction of a circularly polarized pulses with an ultra-thin target. The advantage would be compactness and modularity, due to identical accelerating units. The laser efficiency required to have an acceptable net gain in the inertial fusion process is still far from the presently achievable values both for CPA short pulses and for long pulses used for direct illumination. Conversely the energy conversion efficiency from the laser pulse to the ion bunch is high and grows with the intensity. As a consequence the energy loss is not the major concern. For a preliminary investigation of the ions bunch production we have used the PIC code ALaDyn developed to analyze the results of the INFN-CNR PLASMONX experiment at Frascati National Laboratories (Rome, Italy) where the 0.3 PW laser FLAME will accelerate electrons and protons. We present the results of some 1D simulations and parametric scan concerning the acceleration of carbon ions that we suppose to be fully ionized. Circularly polarized laser pulses of 50 J and 50-100 fs duration, illuminating a 100{mu}m{sup 2} area

  11. Development and Benchmarking of a Hybrid PIC Code For Dense Plasmas and Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Witherspoon, F. Douglas [HyperV Technologies Corp.; Welch, Dale R. [Voss Scientific, LLC; Thompson, John R. [FAR-TECH, Inc.; MacFarlane, Joeseph J. [Prism Computational Sciences Inc.; Phillips, Michael W. [Advanced Energy Systems, Inc.; Bruner, Nicki [Voss Scientific, LLC; Mostrom, Chris [Voss Scientific, LLC; Thoma, Carsten [Voss Scientific, LLC; Clark, R. E. [Voss Scientific, LLC; Bogatu, Nick [FAR-TECH, Inc.; Kim, Jin-Soo [FAR-TECH, Inc.; Galkin, Sergei [FAR-TECH, Inc.; Golovkin, Igor E. [Prism Computational Sciences, Inc.; Woodruff, P. R. [Prism Computational Sciences, Inc.; Wu, Linchun [HyperV Technologies Corp.; Messer, Sarah J. [HyperV Technologies Corp.

    2014-05-20

    Radiation processes play an important role in the study of both fast ignition and other inertial confinement schemes, such as plasma jet driven magneto-inertial fusion, both in their effect on energy balance, and in generating diagnostic signals. In the latter case, warm and hot dense matter may be produced by the convergence of a plasma shell formed by the merging of an assembly of high Mach number plasma jets. This innovative approach has the potential advantage of creating matter of high energy densities in voluminous amount compared with high power lasers or particle beams. An important application of this technology is as a plasma liner for the flux compression of magnetized plasma to create ultra-high magnetic fields and burning plasmas. HyperV Technologies Corp. has been developing plasma jet accelerator technology in both coaxial and linear railgun geometries to produce plasma jets of sufficient mass, density, and velocity to create such imploding plasma liners. An enabling tool for the development of this technology is the ability to model the plasma dynamics, not only in the accelerators themselves, but also in the resulting magnetized target plasma and within the merging/interacting plasma jets during transport to the target. Welch pioneered numerical modeling of such plasmas (including for fast ignition) using the LSP simulation code. Lsp is an electromagnetic, parallelized, plasma simulation code under development since 1995. It has a number of innovative features making it uniquely suitable for modeling high energy density plasmas including a hybrid fluid model for electrons that allows electrons in dense plasmas to be modeled with a kinetic or fluid treatment as appropriate. In addition to in-house use at Voss Scientific, several groups carrying out research in Fast Ignition (LLNL, SNL, UCSD, AWE (UK), and Imperial College (UK)) also use LSP. A collaborative team consisting of HyperV Technologies Corp., Voss Scientific LLC, FAR-TECH, Inc., Prism

  12. Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments

    Energy Technology Data Exchange (ETDEWEB)

    MacFarlane, Joseph J [Prism Computational Sciences

    2009-08-07

    This Final Report summarizes work performed under DOE STTR Phase II Grant No. DE-FG02-05ER86258 during the project period from August 2006 to August 2009. The project, “Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments,” was led by Prism Computational Sciences (Madison, WI), and involved collaboration with subcontractors University of Nevada-Reno and Voss Scientific (Albuquerque, NM). In this project, we have: Developed and implemented a multi-dimensional, multi-frequency radiation transport model in the LSP hybrid fluid-PIC (particle-in-cell) code [1,2]. Updated the LSP code to support the use of accurate equation-of-state (EOS) tables generated by Prism’s PROPACEOS [3] code to compute more accurate temperatures in high energy density physics (HEDP) plasmas. Updated LSP to support the use of Prism’s multi-frequency opacity tables. Generated equation of state and opacity data for LSP simulations for several materials being used in plasma jet experimental studies. Developed and implemented parallel processing techniques for the radiation physics algorithms in LSP. Benchmarked the new radiation transport and radiation physics algorithms in LSP and compared simulation results with analytic solutions and results from numerical radiation-hydrodynamics calculations. Performed simulations using Prism radiation physics codes to address issues related to radiative cooling and ionization dynamics in plasma jet experiments. Performed simulations to study the effects of radiation transport and radiation losses due to electrode contaminants in plasma jet experiments. Updated the LSP code to generate output using NetCDF to provide a better, more flexible interface to SPECT3D [4] in order to post-process LSP output. Updated the SPECT3D code to better support the post-processing of large-scale 2-D and 3-D datasets generated by simulation codes such as LSP. Updated atomic physics modeling to provide for

  13. Ion Fast Ignition-Establishing a Scientific Basis for Inertial Fusion Energy --- Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Richard Burnite [General Atomics; Foord, Mark N. [Lawrence Livermore National Laboratory; Wei, Mingsheng [General Atomics; Beg, Farhat N. [University of California, San Diego; Schumacher, Douglass W. [The Ohio State University

    2013-10-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional ?central hot spot? (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10?s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The compressed fuel is opaque to laser light. The ignition laser energy must be converted to a jet of energetic charged particles to deposit energy in the dense fuel. The original concept called for a spray of laser-generated hot electrons to deliver the energy; lack of ability to focus the electrons put great weight on minimizing the electron path. An alternative concept, proton-ignited FI, used those electrons as intermediaries to create a jet of protons that could be focused to the ignition spot from a more convenient distance. Our program focused on the generation and directing of the proton jet, and its transport toward the fuel, none of which were well understood at the onset of our program. We have developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to create a self-consistent understanding of the fundamental physics underlying these issues. Our strategy was to examine the new physics emerging as we added the complexity necessary to use proton beams in an inertial fusion energy (IFE) application. From the starting point of a proton beam accelerated from a flat, isolated foil, we 1) curved it to focus the beam, 2) attached the foil to a superstructure, 3) added a side sheath to protect it from the surrounding plasma, and finally 4) studied the proton beam behavior as it passed through a protective end cap into plasma. We built up, as we proceeded

  14. Development of time-of-flight neutron detector with fast-decay and low-afterglow scintillator for fast ignition experiment

    Directory of Open Access Journals (Sweden)

    Nagai T.

    2013-11-01

    Full Text Available A fast-decay and low-afterglow liquid scintillator was developed for the fast ignition experiment at the Institute of Laser Engineering (ILE. The liquid scintillator was coupled to a gated photomultiplier (PMT, and the gating performance under high-intensity γ-rays was experimentally checked. In 2010, a detector with a high detection efficiency of 10−4 was developed and installed in this experiment. The neutron yield in the fast heating experiment was successfully measured using this detector.

  15. Ignition's glow: Ultra-fast spread of global cortical activity accompanying local "ignitions" in visual cortex during conscious visual perception.

    Science.gov (United States)

    Noy, N; Bickel, S; Zion-Golumbic, E; Harel, M; Golan, T; Davidesco, I; Schevon, C A; McKhann, G M; Goodman, R R; Schroeder, C E; Mehta, A D; Malach, R

    2015-09-01

    Despite extensive research, the spatiotemporal span of neuronal activations associated with the emergence of a conscious percept is still debated. The debate can be formulated in the context of local vs. global models, emphasizing local activity in visual cortex vs. a global fronto-parietal "workspace" as the key mechanisms of conscious visual perception. These alternative models lead to differential predictions with regard to the precise magnitude, timing and anatomical spread of neuronal activity during conscious perception. Here we aimed to test a specific aspect of these predictions in which local and global models appear to differ - namely the extent to which fronto-parietal regions modulate their activity during task performance under similar perceptual states. So far the main experimental results relevant to this debate have been obtained from non-invasive methods and led to conflicting interpretations. Here we examined these alternative predictions through large-scale intracranial measurements (Electrocorticogram - ECoG) in 43 patients and 4445 recording sites. Both ERP and broadband high frequency (50-150 Hz - BHF) responses were examined through the entire cortex during a simple 1-back visual recognition memory task. Our results reveal short latency intense visual responses, localized first in early visual cortex followed (at ∼200 ms) by higher order visual areas, but failed to show significant delayed (300 ms) visual activations. By contrast, oddball image repeat events, linked to overt motor responses, were associated with a significant increase in a delayed (300 ms) peak of BHF power in fronto-parietal cortex. Comparing BHF responses with ERP revealed an additional peak in the ERP response - having a similar latency to the well-studied P3 scalp EEG response. Posterior and temporal regions demonstrated robust visual category selectivity. An unexpected observation was that high-order visual cortex responses were essentially concurrent (at ∼200 ms

  16. Advanced laser particle accelerator development at LANL: from fast ignition to radiation oncology

    Energy Technology Data Exchange (ETDEWEB)

    Flippo, Kirk A [Los Alamos National Laboratory; Gaillard, Sandrine A [Los Alamos National Laboratory; Offermann, D T [Los Alamos National Laboratory; Cobble, J A [Los Alamos National Laboratory; Schmitt, M J [Los Alamos National Laboratory; Gautier, D C [Los Alamos National Laboratory; Kwan, T J T [Los Alamos National Laboratory; Montgomery, D S [Los Alamos National Laboratory; Kluge, Thomas [FZD-GERMANY; Bussmann, Micheal [FZD-GERMANY; Bartal, T [UCSD; Beg, F N [UCSD; Gall, B [UNIV OF MISSOURI; Geissel, M [SNL; Korgan, G [NANOLABZ; Kovaleski, S [UNIV OF MISSOURI; Lockard, T [UNIV OF NEVADA; Malekos, S [NANOLABZ; Schollmeier, M [SNL; Sentoku, Y [UNIV OF NEVADA; Cowan, T E [FZD-GERMANY

    2010-01-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, SN M detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high current and high energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology in conjunction with our partners at the ForschungsZentrum Dresden-Rossendorf (FZD). Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent etliciencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  17. Advanced Laser Particle Accelerator Development at LANL: From Fast Ignition to Radiation Oncology

    Science.gov (United States)

    Flippo, K. A.; Gaillard, S. A.; Kluge, T.; Bussmann, M.; Offermann, D. T.; Cobble, J. A.; Schmitt, M. J.; Bartal, T.; Beg, F. N.; Cowan, T. E.; Gall, B.; Gautier, D. C.; Geissel, M.; Kwan, T. J.; Korgan, G.; Kovaleski, S.; Lockard, T.; Malekos, S.; Montgomery, D. S.; Schollmeier, M.; Sentoku, Y.

    2010-11-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, Special Nuclear Material (SNM) detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high-current and high-energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology. Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent efficiencies of >5% from flat foils, on Trident using only a 5th of the intensity [1] and energy of the Nova Petawatt laser [2]. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world [3]. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  18. Development and Benchmarking of a Hybrid PIC Code For Dense Plasmas and Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Witherspoon, F. Douglas [HyperV Technologies Corp.; Welch, Dale R. [Voss Scientific, LLC; Thompson, John R. [FAR-TECH, Inc.; MacFarlane, Joeseph J. [Prism Computational Sciences Inc.; Phillips, Michael W. [Advanced Energy Systems, Inc.; Bruner, Nicki [Voss Scientific, LLC; Mostrom, Chris [Voss Scientific, LLC; Thoma, Carsten [Voss Scientific, LLC; Clark, R. E. [Voss Scientific, LLC; Bogatu, Nick [FAR-TECH, Inc.; Kim, Jin-Soo [FAR-TECH, Inc.; Galkin, Sergei [FAR-TECH, Inc.; Golovkin, Igor E. [Prism Computational Sciences, Inc.; Woodruff, P. R. [Prism Computational Sciences, Inc.; Wu, Linchun [HyperV Technologies Corp.; Messer, Sarah J. [HyperV Technologies Corp.

    2014-05-20

    Radiation processes play an important role in the study of both fast ignition and other inertial confinement schemes, such as plasma jet driven magneto-inertial fusion, both in their effect on energy balance, and in generating diagnostic signals. In the latter case, warm and hot dense matter may be produced by the convergence of a plasma shell formed by the merging of an assembly of high Mach number plasma jets. This innovative approach has the potential advantage of creating matter of high energy densities in voluminous amount compared with high power lasers or particle beams. An important application of this technology is as a plasma liner for the flux compression of magnetized plasma to create ultra-high magnetic fields and burning plasmas. HyperV Technologies Corp. has been developing plasma jet accelerator technology in both coaxial and linear railgun geometries to produce plasma jets of sufficient mass, density, and velocity to create such imploding plasma liners. An enabling tool for the development of this technology is the ability to model the plasma dynamics, not only in the accelerators themselves, but also in the resulting magnetized target plasma and within the merging/interacting plasma jets during transport to the target. Welch pioneered numerical modeling of such plasmas (including for fast ignition) using the LSP simulation code. Lsp is an electromagnetic, parallelized, plasma simulation code under development since 1995. It has a number of innovative features making it uniquely suitable for modeling high energy density plasmas including a hybrid fluid model for electrons that allows electrons in dense plasmas to be modeled with a kinetic or fluid treatment as appropriate. In addition to in-house use at Voss Scientific, several groups carrying out research in Fast Ignition (LLNL, SNL, UCSD, AWE (UK), and Imperial College (UK)) also use LSP. A collaborative team consisting of HyperV Technologies Corp., Voss Scientific LLC, FAR-TECH, Inc., Prism

  19. Fundamental Studies on the Use of Laser-Driven Proton Beams for Fast Ignition

    Science.gov (United States)

    McGuffey, C.; Kim, J.; Beg, F. N.; Wei, M. S.; Chen, S. N.; Fuchs, J.; Nilson, P. M.; Theobald, W.; Habara, H.; Tanaka, K.; Yabuuchi, T.; Foord, M. E.; Patel, P. K.; McLean, H. S.; Roth, M.; McKenna, P.

    2015-11-01

    A short-pulse-laser-driven intense proton beam remains a candidate for Fast Ignition heater due to its focusability and high current. However, the proton current density necessary for FI in practice has never been produced in the laboratory and there are many physics issues that should be addressed using current and near-term facilities. For example, the extraction of sufficient proton charge from the short-pulse laser target could be evaluated with the multi-kilojoule NIF ARC laser. Transport of the beam through matter, such as a cone tip, and deposition in the fuel must be considered carefully as it will isochorically heat any material it enters and produce a rapidly-evolving, warm dense matter state with uncertain transport and stopping properties. Here we share experimental measurements of the proton spectra after passing through metal cones and foils taken with the kilojoule-class, multi-picosecond OMEGA EP and LFEX lasers. We also present complementary PIC simulations of beam generation and transport to and in the foils. Upcoming experiments to further evaluate proton beam performance in proton FI will also be outlined. This work was supported by the DOE/NNSA NLUF program, Contract DE-NA0002034 and by the AFOSR under Contract FA9550-14-1-0346.

  20. Review of the current status of fast ignition research atthe IAPCM

    Institute of Scientific and Technical Information of China (English)

    Hong-bo; Cai; Si-zhong; Wu; Jun-feng; Wu; Mo; Chen; Hua; Zhang; Min-qing; He; Li-hua; Cao; Cang-tao; Zhou; Shao-ping; Zhu; Xian-tu; He

    2014-01-01

    We review the present status and future prospects of fast ignition(FI) research of the theoretical group at the IAPCM(Institute of Applied Physics and Computational Mathematics, Beijing) as a part of the inertial confinement fusion project. Since the approval of the FI project at the IAPCM, we have devoted our efforts to improving the integrated codes for FI and designing advanced targets together with the experimental group. Recent FI experiments [K. U. Akli et al., Phys. Rev. E 86, 065402(2012)] showed that the petawatt laser beam energy was not efficiently converted into the compressed core because of the beam divergence of relativistic electron beams. The coupling efficiency can be improved in three ways:(1) using a cone–wire-in-shell advanced target to enhance the transport efficiency,(2) using external magnetic fields to collimate fast electrons, and(3) reducing the prepulse level of the petawatt laser beam. The integrated codes for FI, named ICFI, including a radiation hydrodynamic code, a particle-in-cell(PIC) simulation code,and a hybrid fluid–PIC code, have been developed to design this advanced target at the IAPCM. The Shenguang-II upgraded laser facility has been constructed for FI research; it consists of eight beams(in total 24 kJ/3ω, 3 ns) for implosion compression, and a heating laser beam(0.5–1 kJ, 3–5 ps) for generating the relativistic electron beam. A fully integrated FI experiment is scheduled for the 2014 project.

  1. Ion Fast Ignition-Establishing a Scientific Basis for Inertial Fusion Energy --- Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Richard Burnite [General Atomics; Foord, Mark N. [Lawrence Livermore National Laboratory; Wei, Mingsheng [General Atomics; Beg, Farhat N. [University of California, San Diego; Schumacher, Douglass W. [The Ohio State University

    2013-10-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional ?central hot spot? (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10?s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The compressed fuel is opaque to laser light. The ignition laser energy must be converted to a jet of energetic charged particles to deposit energy in the dense fuel. The original concept called for a spray of laser-generated hot electrons to deliver the energy; lack of ability to focus the electrons put great weight on minimizing the electron path. An alternative concept, proton-ignited FI, used those electrons as intermediaries to create a jet of protons that could be focused to the ignition spot from a more convenient distance. Our program focused on the generation and directing of the proton jet, and its transport toward the fuel, none of which were well understood at the onset of our program. We have developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to create a self-consistent understanding of the fundamental physics underlying these issues. Our strategy was to examine the new physics emerging as we added the complexity necessary to use proton beams in an inertial fusion energy (IFE) application. From the starting point of a proton beam accelerated from a flat, isolated foil, we 1) curved it to focus the beam, 2) attached the foil to a superstructure, 3) added a side sheath to protect it from the surrounding plasma, and finally 4) studied the proton beam behavior as it passed through a protective end cap into plasma. We built up, as we proceeded

  2. An electron/ion spectrometer with the ability of low energy electron measurement for fast ignition experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, T.; Sakagami, H. [National Institute for Fusion Science, 322-6, Oroshi, Toki, Gifu 509-5292 (Japan); Kojima, S.; Arikawa, Y.; Shiraga, H.; Fujioka, S. [Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871 (Japan); Kato, R., E-mail: ozaki@nifs.ac.jp [Institute of Scientific and Industrial Research, Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2014-11-15

    An electron energy spectrometer (ESM) is one of the most fundamental diagnostics in the fast ignition experiment. It is necessary to observe the spectra down to a low energy range in order to obtain the accurate deposition efficiency toward the core. Here, we realize the suitable ESM by using a ferrite magnet with a moderate magnetic field of 0.3 T and a rectangular magnetic circuit covered with a steel plate in the inlet side.

  3. Simultaneous-Fault Diagnosis of Automotive Engine Ignition Systems Using Prior Domain Knowledge and Relevance Vector Machine

    Directory of Open Access Journals (Sweden)

    Chi-Man Vong

    2013-01-01

    Full Text Available Engine ignition patterns can be analyzed to identify the engine fault according to both the specific prior domain knowledge and the shape features of the patterns. One of the challenges in ignition system diagnosis is that more than one fault may appear at a time. This kind of problem refers to simultaneous-fault diagnosis. Another challenge is the acquisition of a large amount of costly simultaneous-fault ignition patterns for constructing the diagnostic system because the number of the training patterns depends on the combination of different single faults. The above problems could be resolved by the proposed framework combining feature extraction, probabilistic classification, and decision threshold optimization. With the proposed framework, the features of the single faults in a simultaneous-fault pattern are extracted and then detected using a new probabilistic classifier, namely, pairwise coupling relevance vector machine, which is trained with single-fault patterns only. Therefore, the training dataset of simultaneous-fault patterns is not necessary. Experimental results show that the proposed framework performs well for both single-fault and simultaneous-fault diagnoses and is superior to the existing approach.

  4. Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Y., E-mail: abe-y@ile.osaka-u.ac.jp; Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2014-11-15

    The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

  5. Ultra-fast pulsed microwave plasma breakdown: evidence of various ignition modes

    Science.gov (United States)

    Carbone, Emile; Nijdam, Sander

    2014-02-01

    In this communication, we investigate the ignition of pulsed microwave plasmas in a narrow dielectric tube with an electrodeless configuration. The plasma is generated using a surfatron cavity. The power is modulated as a square wave with a rise-time of 30 ns at variable frequencies from 100 Hz up to 5 MHz. The ignition and plasma propagation inside the 3 mm radius quartz tube are imaged spatially and resolved with nanosecond time resolution using an iCCD camera. The plasma is found to propagate in the form of a front moving from the launcher to the end of the plasma column with the microwave power being gradually absorbed behind it. The velocity of the plasma front decreases while the plasma goes towards a steady state. The ionization front is found to be strongly non-uniform and various structures as a function of the pulse repetition frequency (i.e. power-off time) are shown in the axial and radial directions. At low frequencies, finger-like structures are found. The plasma becomes more hollow at smaller power-off times. At higher repetition frequencies (kHz regime), a critical repetition frequency is found for which the plasma light intensity sharply increases at the head of the propagation front, taking a shape resembling a plasma bullet. This critical frequency depends on the pressure and power. For even higher frequencies, the bullet shape disappears and plasma volume ignition from the launcher to the end of the plasma column is observed. These results bring a new insight into the ignition mechanisms of pulsed microwave plasmas inside dielectric tubes. A wide variety of effects are found which seem to mostly depend on the background ionization degree. Moreover, the results show that only a 3D time-dependent model can, in general, correctly describe the ignition of a pulsed microwave discharge.

  6. Study of shock waves generation, hot electron production and role of parametric instabilities in an intensity regime relevant for the shock ignition

    Science.gov (United States)

    Antonelli, L.; Köster, P.; Folpini, G.; Maheut, Y.; Baffigi, F.; Cristoforetti, G.; Labate, L.; Levato, T.; Gizzi, L. A.; Consoli, F.; De Angelis, R.; Kalinowska, Z.; Chodukowski, T.; Rosinski, M.; Parys, P.; Pisarczyk, T.; Raczka, P.; Ryc, L.; Badziak, J.; Wolowski, J.; Smid, M.; Renner, O.; Krousky, E.; Pfeifer, M.; Skala, J.; Ullschmied, J.; Nicolaï, P.; Ribeyre, X.; Shurtz, G.; Atzeni, S.; Marocchino, A.; Schiavi, A.; Spindloe, C.; Dell, T. O.; Rhee, Y. J.; Richetta, M.; Batani, D.

    2016-03-01

    We present experimental results at intensities relevant to Shock Ignition obtained at the sub-ns Prague Asterix Laser System in 2012. We studied shock waves produced by laser-matter interaction in presence of a pre-plasma. We used a first beam at 1ω (1315 nm) at 7 x 1013 W/cm2 to create a pre-plasma on the front side of the target and a second at 3ω (438 nm) at ∼ 1016 W/cm2 to create the shock wave. Multilayer targets composed of 25 (or 40 µm) of plastic (doped with Cl), 5 µm of Cu (for Kα diagnostics) and 20 µm of Al for shock measurement were used. We used X-ray spectroscopy of Cl to evaluate the plasma temperature, Kα imaging and spectroscopy to evaluate spatial and spectral properties of the fast electrons and a streak camera for shock breakout measurements. Parametric instabilities (Stimulated Raman Scattering, Stimulated Brillouin Scattering and Two Plasmon Decay) were studied by collecting the back scattered light and analysing its spectrum. Back scattered energy was measured with calorimeters. To evaluate the maximum pressure reached in our experiment we performed hydro simulations with CHIC and DUED codes. The maximum shock pressure generated in our experiment at the front side of the target during laser-interaction is 90 Mbar. The conversion efficiency into hot electrons was estimated to be of the order of ∼ 0.1% and their mean energy in the order ∼50 keV.

  7. A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dongxiao; Shan, Lianqiang; Zhou, Weimin; Wu, Yuchi; Zhu, Bin; Zhang, Feng; Bi, Bi; Zhang, Bo; Zhang, Zhimeng; Shui, Min; He, Yingling; Gu, Yuqiu, E-mail: yqgu@caep.cn; Zhang, Baohan [Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Peng, Xiaoshi; Xu, Tao; Wang, Feng; Yang, Zhiwen; Chen, Tao; Chen, Li; Chen, Ming [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); and others

    2016-06-15

    During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.

  8. Generation of high pressure shocks relevant to the shock-ignition intensity regime

    Energy Technology Data Exchange (ETDEWEB)

    Batani, D.; Folpini, G.; Giuffrida, L.; Maheut, Y.; Malka, G.; Nicolai, Ph.; Ribeyre, X. [Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Antonelli, L. [Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Università di Roma “Tor Vergata,” Roma (Italy); Atzeni, S.; Marocchino, A.; Schiavi, A. [Dipartimento SBAI, Université di Roma “La Sapienza” and CNISM, Roma (Italy); Badziak, J.; Chodukowski, T.; Kalinowska, Z.; Pisarczyk, T.; Rosinski, M. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Baffigi, F.; Cristoforetti, G.; Gizzi, L. A.; Koester, P. [Intense Laser Irradiation Laboratory, INO-CNR, Pisa (Italy); and others

    2014-03-15

    An experiment was performed using the PALS laser to study laser-target coupling and laser-plasma interaction in an intensity regime ≤10{sup 16} W/cm{sup 2}, relevant for the “shock ignition” approach to Inertial Confinement Fusion. A first beam at low intensity was used to create an extended preformed plasma, and a second one to create a strong shock. Pressures up to 90 Megabars were inferred. Our results show the importance of the details of energy transport in the overdense region.

  9. Shock Ignition: A New Approach to High Gain Targets for the National Ignition Facility

    Science.gov (United States)

    Perkins, L. John; Lafortune, Kai; Divol, Laurent; Betti, Riccardo

    2008-11-01

    Shock-ignition is being studied as a future option for achieving high target gains on NIF, offering the potential for testing high yield (200MJ), reactor-relevant targets for inertial fusion energy and targets with appreciable gains at drive energies much less than 1MJ. In contrast to conventional hotspot ignition, the assembly and ignition phases are separated by imploding a high mass shell at low velocity. The assembled fuel is then separately ignited by a strong, spherical shock driven by a high intensity spike at the end of the pulse and timed to reach the center as the main fuel is stagnating. Because the implosion velocity is significantly less than that required for hotspot ignition, considerably more fuel mass can be assembled and burned for the same kinetic energy in the shell. Like fast ignition, shock ignition could achieve high gains at low drive energy, but has the advantages of requiring only a single laser with less demanding timing and spatial focusing requirements. We will discuss gain curves for shock-ignited NIF targets in both UV and green light and examine the feasibility of designs that employ indirect drive fuel assembly with direct drive shock ignition

  10. Fast start-up of microchannel fuel processor integrated with an igniter for hydrogen combustion

    Science.gov (United States)

    Ryi, Shin Kun; Park, Jong Soo; Cho, Song Ho; Kim, Sung Hyun

    A Pt-Zr catalyst coated FeCrAlY mesh is introduced into the combustion outlet conduit of a newly designed microchannel reactor (MCR) as an igniter of hydrogen combustion to decrease the start-up time. The catalyst is coated using a wash-coating method. After installing the Pt-Zr/FeCrAlY mesh, the reactor is heated to its running temperature within 1 min with hydrogen combustion. Two plate-type heat-exchangers are introduced at the combustion outlet and reforming outlet conduits of the microchannel reactor in order to recover the heat of the combustion gas and reformed gas, respectively. Using these heat-exchangers, methane steam reforming is carried out with hydrogen combustion and the reforming capacity and energy efficiency are enhanced by up to 3.4 and 1.7 times, respectively. A compact fuel processor and fuel-cell system using this reactor concept is expected to show considerable advancement.

  11. Shock-Ignited High Gain/Yield Targets for the National Ignition Facility

    Science.gov (United States)

    Perkins, L. J.; Lafortune, K. N.; Bedrosiian, P.; Tabak, M.; Miles, A.; Dixit, S.; Betti, R.; Anderson, K.; Zhou, C.

    2006-10-01

    Shock-ignition, a new concept for ICF ignition [C.Zhou, R.Betti Bull APS, v50, 2005], is being studied as a future option for efficiently achieving high gains in large laser facilities such as NIF. Accordingly, this offers the potential for testing: (1)High yield (up to 200MJ), reactor-relevant targets for inertial fusion energy (2)High fusion yield targets for DOE NNSA stockpile application (3)Targets with appreciable gain at low laser drive energies (gains of 10's at 150kJ) (4)Ignition of simple, non-cryo (room temperature) single shell gas targets at (unity gain). By contrast to conventional hotspot ignition, we separate the assembly and ignition phases by initially imploding a massive cryogenic shell on a low adiabat (alpha 0.7) at low velocity (less than 2e7cm/s) using a direct drive pulse of modest total energy. The assembled fuel is then separately ignited by a strong, spherically convergent shock driven by a high intensity spike at the end of the pulse and timed to reach the center as the main fuel is stagnating and starting to rebound. Like fast ignition, shock ignition can achieve high gains with low drive energy, but has the advantages of requiring only a single laser with less demanding timing and spatial focusing requirements.

  12. Study of Rayleigh–Taylor growth in laser irradiated planar SiO{sub 2} targets at ignition-relevant conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hager, J. D.; Collins, T. J. B.; Knauer, J. P.; Meyerhofer, D. D.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Smalyuk, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2013-07-15

    Rayleigh–Taylor (RT) growth experiments were performed on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar SiO{sub 2} targets seeded with a single mode 60-μm wavelength perturbation driven at peak laser intensities up to 9 × 10{sup 14} W/cm{sup 2}. These are the first RT measurements in SiO{sub 2} at conditions relevant to direct-drive inertial confinement fusion ignition. The measured average modulation growth rates agree with the 2-D hydrodynamics code DRACO, providing an important step in the development of target ablators that are robust to RT growth and hot- electron preheat considerations when driven at the intensities required to achieve thermonuclear ignition.

  13. High-energy-density plasmas generation on GEKKO-LFEX laser facility for fast-ignition laser fusion studies and laboratory astrophysics

    Science.gov (United States)

    Fujioka, S.; Zhang, Z.; Yamamoto, N.; Ohira, S.; Fujii, Y.; Ishihara, K.; Johzaki, T.; Sunahara, A.; Arikawa, Y.; Shigemori, K.; Hironaka, Y.; Sakawa, Y.; Nakata, Y.; Kawanaka, J.; Nagatomo, H.; Shiraga, H.; Miyanaga, N.; Norimatsu, T.; Nishimura, H.; Azechi, H.

    2012-12-01

    The world's largest peta watt (PW) laser LFEX, which delivers energy up to 2 kJ in a 1.5 ps pulse, has been constructed beside the GEKKO XII laser at the Institute of Laser Engineering, Osaka University. The GEKKO-LFEX laser facility enables the creation of materials having high-energy-density which do not exist naturally on the Earth and have an energy density comparable to that of stars. High-energy-density plasma is a source of safe, secure, environmentally sustainable fusion energy. Direct-drive fast-ignition laser fusion has been intensively studied at this facility under the auspices of the Fast Ignition Realization Experiment (FIREX) project. In this paper, we describe improvement of the LFEX laser and investigations of advanced target design to increase the energy coupling efficiency of the fast-ignition scheme. The pedestal of the LFEX pulse, which produces a long preformed plasma and results in the generation of electrons too energetic to heat the fuel core, was reduced by introducing an amplified optical parametric fluorescence quencher and saturable absorbers in the front-end system of the LFEX laser. Since fast electrons are scattered and stopped by the strong electric field of highly ionized high-Z (i.e. gold) ions, a low-Z cone was studied for reducing the energy loss of fast electrons in the cone tip region. A diamond-like carbon cone was fabricated for the fast-ignition experiment. An external magnetic field, which is demonstrated to be generated by a laser-driven capacitor-coil target, will be applied to the compression of the fuel capsule to form a strong magnetic field to guide the fast electrons to the fuel core. In addition, the facility offers a powerful means to test and validate astronomical models and computations in the laboratory. As well as demonstrating the ability to recreate extreme astronomical conditions by the facilities, our theoretical description of the laboratory experiment was compared with the generally accepted explanation

  14. Assessment and clinical relevance of non-fasting and postprandial triglycerides

    DEFF Research Database (Denmark)

    Kolovou, Genovefa D; Mikhailidis, Dimitri P; Kovar, Jan

    2011-01-01

    An Expert Panel group of scientists and clinicians met to consider several aspects related to non-fasting and postprandial triglycerides (TGs) and their role as risk factors for cardiovascular disease (CVD). In this context, we review recent epidemiological studies relevant to elevated non-fastin...

  15. Assessment and clinical relevance of non-fasting and postprandial triglycerides

    DEFF Research Database (Denmark)

    Kolovou, Genovefa D; Mikhailidis, Dimitri P; Kovar, Jan

    2011-01-01

    An Expert Panel group of scientists and clinicians met to consider several aspects related to non-fasting and postprandial triglycerides (TGs) and their role as risk factors for cardiovascular disease (CVD). In this context, we review recent epidemiological studies relevant to elevated non...

  16. Assessment and clinical relevance of non-fasting and postprandial triglycerides: an expert panel statement.

    Science.gov (United States)

    Kolovou, Genovefa D; Mikhailidis, Dimitri P; Kovar, Jan; Lairon, Dennis; Nordestgaard, Børge G; Ooi, Teik Chye; Perez-Martinez, Pablo; Bilianou, Helen; Anagnostopoulou, Katherine; Panotopoulos, George

    2011-05-01

    An Expert Panel group of scientists and clinicians met to consider several aspects related to non-fasting and postprandial triglycerides (TGs) and their role as risk factors for cardiovascular disease (CVD). In this context, we review recent epidemiological studies relevant to elevated non-fasting TGs as a risk factor for CVD and provide a suggested classification of non-fasting TG concentration. Secondly, we sought to describe methodologies to evaluate postprandial TG using a fat tolerance test (FTT) in the clinic. Thirdly, we discuss the role of non-fasting lipids in the treatment of postprandial hyperlipemia. Finally, we provide a series of clinical recommendations relating to non-fasting TGs based on the consensus of the Expert Panel: 1). Elevated non-fasting TGs are a risk factor for CVD. 2). The desirable non-fasting TG concentration is fast and should consist of 75 g of fat, 25 g of carbohydrates and 10 g of protein. 4). A single TG measurement 4 h after a FTT meal provides a good evaluation of the postprandial TG response. 5). Preferably, subjects with non-fasting TG levels of 1-2 mmol/l (89-180 mg/dl) should be tested with a FTT. 6). TG concentration ≤ 2.5 mmol/l (220 mg/dl) at any time after a FTT meal should be considered as a desirable postprandial TG response. 7). A higher and undesirable postprandial TG response could be treated by aggressive lifestyle modification (including nutritional supplementation) and/or TG lowering drugs like statins, fibrates and nicotinic acid.

  17. Ion-driver fast ignition: Reducing heavy-ion fusion driver energy and cost, simplifying chamber design, target fab, tritium fueling and power conversion

    Energy Technology Data Exchange (ETDEWEB)

    Logan, G.; Callahan-Miller, D.; Perkins, J.; Caporaso, G.; Tabak, M.; Moir, R.; Meier, W.; Bangerter, Roger; Lee, Ed

    1998-04-01

    Ion fast ignition, like laser fast ignition, can potentially reduce driver energy for high target gain by an order of magnitude, while reducing fuel capsule implosion velocity, convergence ratio, and required precisions in target fabrication and illumination symmetry, all of which should further improve and simplify IFE power plants. From fast-ignition target requirements, we determine requirements for ion beam acceleration, pulse-compression, and final focus for advanced accelerators that must be developed for much shorter pulses and higher voltage gradients than today's accelerators, to deliver the petawatt peak powers and small focal spots ({approx}100 {micro}m) required. Although such peak powers and small focal spots are available today with lasers, development of such advanced accelerators is motivated by the greater likely efficiency of deep ion penetration and deposition into pre-compressed 1000x liquid density DT cores. Ion ignitor beam parameters for acceleration, pulse compression, and final focus are estimated for two examples based on a Dielectric Wall Accelerator; (1) a small target with {rho}r {approx} 2 g/cm{sup 2} for a small demo/pilot plant producing {approx}40 MJ of fusion yield per target, and (2) a large target with {rho}r {approx} 10 g/cm{sup 2} producing {approx}1 GJ yield for multi-unit electricity/hydrogen plants, allowing internal T-breeding with low T/D ratios, >75 % of the total fusion yield captured for plasma direct conversion, and simple liquid-protected chambers with gravity clearing. Key enabling development needs for ion fast ignition are found to be (1) ''Close-coupled'' target designs for single-ended illumination of both compressor and ignitor beams; (2) Development of high gradient (>25 MV/m) linacs with high charge-state (q {approx} 26) ion sources for short ({approx}5 ns) accelerator output pulses; (3) Small mm-scale laser-driven plasma lens of {approx}10 MG fields to provide steep focusing angles

  18. Bremsstrahlung and K(alpha) fluorescence measurements for inferring conversion efficiencies into fast ignition relevant hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C D; Patel, P K; Hey, D S; Mackinnon, A J; Key, M H; Akli, K U; Bartal, T; Beg, F N; Chawla, S; Chen, H; Freeman, R R; Higginson, D P; Link, A; Ma, T Y; MacPhee, A G; Stephens, R B; Van Woerkom, L D; Westover, B; Porkolab, M

    2009-07-24

    The Bremsstrahlung and K-shell emission from 1 mm x 1 mm x 1 mm planar targets irradiated by a short-pulse 3 x 10{sup 18}-8 x 10{sup 19} W/cm{sup 2} laser were measured. The Bremsstrahlung was measured using a filter stack spectrometer with spectral discrimination up to 500 keV. K-shell emission was measured using a single photon counting charge coupled device (CCD). From Monte Carlo modeling of the target emission, conversion efficiencies into 1-3 MeV electrons of 3-12%, representing 20-40% total conversion efficiencies were inferred for intensities up to 8 x 10{sup 19} W/cm{sup 2}. Comparisons to scaling laws using synthetic energy spectra generated from the intensity distribution of the focal spot imply slope temperatures less than the ponderomotive potential of the laser. Resistive transport effects may result in potentials of a few hundred kV in the first few tens of microns in the target. This would lead to higher total conversion efficiencies than inferred from Monte Carlo modeling but lower conversion efficiencies into 1-3 MeV electrons.

  19. Plane thermonuclear detonation waves initiated by proton beams and quasi-one-dimensional model of fast ignition

    CERN Document Server

    Charakhch'yan, Alexander A

    2014-01-01

    The one-dimensional (1D) problem on bilatiral irradiation by proton beams of the plane layer of condensed DT mixture with length $2H$ and density $\\rho_0 \\leqslant 100\\rho_s$, where $\\rho_s$ is the fuel solid-state density at atmospheric pressure and temperature of 4 K, is considered. The proton kinetic energy is 1 MeV, the beam intensity is $10^{19}$ W/cm$^2$ and duration is 50 ps. A mathematical model is based on the one-fluid two-temperature hydrodynamics with a wide-range equation of state of the fuel, electron and ion heat conduction, DT fusion reaction kinetics, self-radiation of plasma and plasma heating by alpha-particles. If the ignition occurs, a plane detonation wave, which is adjacent to the front of the rarefaction wave, appears. Upon reflection of this detonation wave from the symmetry plane, the flow with the linear velocity profile along the spatial variable $x$ and with a weak dependence of the thermodynamic functions of $x$ occurs. An appropriate solution of the equations of hydrodynamics is...

  20. Fast Ignition Realization Experiment with High-Contrast Kilo-Joule Peta-Watt Laser ``LFEX'' and Strong External Magnetic Field

    Science.gov (United States)

    Fujioka, Shinsuke

    2015-11-01

    We report on progresses of the Fast Ignition Realization Experiment (FIREX) project that has been curried out at the Institute of Laser Engineering to assess the feasibility of high density core heating with a high-power, short-pulse laser including the construction of the Kilo-Joule, Petawatt class LFEX laser system. Our recent studies identify three scientific challenges to achieve high heating efficiency in the fast ignition (FI) scheme with the current GEKKO and LFEX laser systems: (i) control of energy distribution of relativistic electron beam (REB), (ii) guiding and focusing of REB to a fuel core, and (iii) formation of a high areal-density core. The control of the electron energy distribution has been experimentally confirmed by improving the intensity contrast of the LFEX laser up to >109 and an ultra-high contrast of 1011 with a plasma mirror. After the contrast improvement, 50% of the total REB energy is carried by a low energy component of the REB, which slope temperature is close to the ponderomotive scaling value (~ 1 MeV). To guide the electron beam, we apply strong external magnetic field to the REB transport region. Guiding of the REB by 0.6 kT field in a planar geometry has already been demonstrated at LULI 2000 laser facility in a collaborative experiment lead by CELIA-Univ. Bordeaux. Considering more realistic FI scenario, we have performed a similar experiment using the Kilo-Joule LFEX laser to study the effect of guiding and magnetic mirror on the electron beam. A high density core of a laser-imploded 200 μm-diameter solid CD ball was radiographed with picosecond LFEX-produced K-alpha backlighter. Comparisons of the experimental results and integrated simulations using hydrodynamic and electron transport codes suggest that 10% of the efficiency can be achievable with the current GEKKO and LFEX laser system with the success of the above challenges. This work is supported by NIFS (Japan), MEXT/JSPS KAKENHI (Japan), JSPS Fellowship (Japan), ANR

  1. Direct numerical simulations of ignition of a lean n-heptane/air mixture with temperature and composition inhomogeneities relevant to HCCI and SCCI combustion

    KAUST Repository

    Luong, Minh Bau

    2015-12-01

    The effects of temperature and composition stratifications on the ignition of a lean n-heptane/air mixture at three initial mean temperatures under elevated pressure are investigated using direct numerical simulations (DNSs) with a 58-species reduced mechanism. Two-dimensional DNSs are performed by varying several key parameters: initial mean temperature, T0, and the variance of temperature and equivalence ratio (T\\' and φ\\') with different T-φcorrelations. It is found that for cases with φ\\' only, the overall combustion occurs more quickly and the mean heat release rate (HRR) increases more slowly with increasing φ\\' regardless of T0. For cases with T\\' only, however, the overall combustion is retarded/advanced in time with increasing T\\' for low/high T0 relative to the negative-temperature coefficient (NTC) regime resulting from a longer/shorter overall ignition delay of the mixture. For cases with uncorrelated T-φfields, the mean HRR is more distributed over time compared to the corresponding cases with T\\' or φ\\' only. For negatively-correlated cases, however, the temporal evolution of the overall combustion exhibits quite non-monotonic behavior with increasing T\\' and φ\\' depending on T0. All of these characteristics are found to be primarily related to the 0-D ignition delays of initial mixtures, the relative timescales between 0-D ignition delay and turbulence, and the dominance of the deflagration mode during the ignition. These results suggest that an appropriate combination of T\\' and φ\\' together with a well-prepared T-φdistribution can alleviate an excessive pressure-rise rate (PRR) and control ignition-timing in homogeneous charge compression-ignition (HCCI) combustion. In addition, critical species and reactions for the ignition of n-heptane/air mixture through the whole ignition process are estimated by comparing the temporal evolution of the mean mass fractions of important species with the overall reaction pathways of n

  2. CVD Diamond Detector Stability Issues for Operation at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, G J; Koch, J A; Moran, M J; Lerche, R A; Izumi, N; Phillips, T W; Glebov, V Y; Sangster, T C; Stoeckl, C

    2003-08-22

    Synthetic diamond crystals produced by the Chemical Vapor Deposition (CVD) technique can serve as fast, radiation hard, neutron sensors for the National Ignition Facility (NIF). Here we explore the stability issues, such as charge trapping and high-flux saturation, that will be relevant to operation at the NIF.

  3. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field

    Science.gov (United States)

    Fujioka, Shinsuke; Arikawa, Yasunobu; Kojima, Sadaoki; Johzaki, Tomoyuki; Nagatomo, Hideo; Sawada, Hiroshi; Lee, Seung Ho; Shiroto, Takashi; Ohnishi, Naofumi; Morace, Alessio; Vaisseau, Xavier; Sakata, Shohei; Abe, Yuki; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Shigemori, Keisuke; Hironaka, Yoichiro; Zhang, Zhe; Sunahara, Atsushi; Ozaki, Tetsuo; Sakagami, Hitoshi; Mima, Kunioki; Fujimoto, Yasushi; Yamanoi, Kohei; Norimatsu, Takayoshi; Tokita, Shigeki; Nakata, Yoshiki; Kawanaka, Junji; Jitsuno, Takahisa; Miyanaga, Noriaki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kondo, Kotaro; Bailly-Grandvaux, Mathieu; Bellei, Claudio; Santos, João Jorge; Azechi, Hiroshi

    2016-05-01

    A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKO-XII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >109. Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused by imploding

  4. Fast food in Ghana’s restaurants: prevalence, characteristics, and relevance : an interdisciplinary perspective

    OpenAIRE

    Omari, R.

    2014-01-01

    Abstract Fast food has been extensively criticised for its link to health and environments problems and for its tendency to undermine traditional food cultures. Notwithstanding these aspects, this study questioned the assumption that fast food by definition has negative impact on health, environment and traditional food cultures for three main reasons. Firstly, fast-food restaurants are spreading quickly in the Accra Metropolitan Area (AMA) of Ghana and have become an important source of urba...

  5. Fast food in Ghana’s restaurants: prevalence, characteristics, and relevance : an interdisciplinary perspective

    NARCIS (Netherlands)

    Omari, R.

    2014-01-01

    Abstract Fast food has been extensively criticised for its link to health and environments problems and for its tendency to undermine traditional food cultures. Notwithstanding these aspects, this study questioned the assumption that fast food by definition has negative impact on he

  6. Fast food in Ghana’s restaurants: prevalence, characteristics, and relevance : an interdisciplinary perspective

    NARCIS (Netherlands)

    Omari, R.

    2014-01-01

    Abstract Fast food has been extensively criticised for its link to health and environments problems and for its tendency to undermine traditional food cultures. Notwithstanding these aspects, this study questioned the assumption that fast food by definition has negative impact on

  7. Fast food in Ghana’s restaurants: prevalence, characteristics, and relevance : an interdisciplinary perspective

    NARCIS (Netherlands)

    Omari, R.

    2014-01-01

    Abstract Fast food has been extensively criticised for its link to health and environments problems and for its tendency to undermine traditional food cultures. Notwithstanding these aspects, this study questioned the assumption that fast food by definition has negative impact on he

  8. Shock ignition: an alternative scheme for HiPER

    Science.gov (United States)

    Ribeyre, X.; Schurtz, G.; Lafon, M.; Galera, S.; Weber, S.

    2009-01-01

    Two main paths are now under investigation that aim at thermonuclear ignition of hydrogen isotopes using lasers: central hot spot self-ignition and externally driven fast ignition of preassembled fuel. A third, intermediate, scheme is shock ignition, which combines the simplicity of self-ignition capsules to the hydrodynamic robustness of the fast ignition fuel assembly. This study addresses the potential of shock ignition for the HiPER project and provides a preliminary assessment of possible detrimental effects. Monodimensional simulations are performed to study the robustness of the ignition scheme in terms of shock launching time and laser power. Bidimensional simulations address the sensitivity of shock ignition to irradiation nonuniformity and to low mode asymmetries of the fuel assembly.

  9. Relevance-based control over visual attention is fast and interdependent with stimulus-driven capture

    DEFF Research Database (Denmark)

    Nordfang, Maria; Bundesen, Claus

    2012-01-01

    An object that is relevant to the current task is more readily encoded than a similar, less relevant object (e.g., Wolfe, Cave, & Franzel, 1989). However, it is highly debated whether relevance-based selection is feasible at short exposure durations (e.g., Theeuwes, 2010). It has been argued that......, the study provided new evidence that both contrast and relevance influence attentional selection at very short exposure durations and the effects of the two factors are interdependent.......An object that is relevant to the current task is more readily encoded than a similar, less relevant object (e.g., Wolfe, Cave, & Franzel, 1989). However, it is highly debated whether relevance-based selection is feasible at short exposure durations (e.g., Theeuwes, 2010). It has been argued...... that high local feature contrast attracts attention independently of task-relevance. Yet, recent studies have provided evidence that effects of task-irrelevant feature contrast interact with the task-relevance of the object in question (Nordfang, 2011). In a new experiment, display size was kept constant...

  10. Clinical relevance of non-fasting and postprandial hypertriglyceridemia and remnant cholesterol

    DEFF Research Database (Denmark)

    Nordestgaard, Børge G; Freiberg, Jacob J

    2011-01-01

    -fasting/postprandial total cholesterol minus low-density lipoprotein (LDL) cholesterol minus high-density lipoprotein (HDL) cholesterol. Elevated levels of non-fasting/postprandial triglycerides directly correlate with elevated remnant cholesterol. In the general population, 38% of men have non......Non-fasting triglycerides are measured at any time within up to 8 h (14 h) after any normal meal, while postprandial triglycerides are measured at a fixed time point within up to 8 h (14 h) of a standardised fat tolerance test. The simplest possible way of evaluating remnant cholesterol is non......-fasting/postprandial triglycerides > 2mmol/L (>176 mg/dL) while 45% of men have non-fasting/postprandial triglyceride levels of 1-2 mmol/L (89-176 mg/dL); corresponding fractions in women are 20% and 47%. Also, 31% of men have remnant cholesterol levels > 1mmol/L (>39 mg/dL) while 46% of men have remnant cholesterol levels of 0...

  11. Clinical relevance of non-fasting and postprandial hypertriglyceridemia and remnant cholesterol

    DEFF Research Database (Denmark)

    Nordestgaard, Børge G; Freiberg, Jacob J

    2011-01-01

    Non-fasting triglycerides are measured at any time within up to 8 h (14 h) after any normal meal, while postprandial triglycerides are measured at a fixed time point within up to 8 h (14 h) of a standardised fat tolerance test. The simplest possible way of evaluating remnant cholesterol is non......-fasting/postprandial total cholesterol minus low-density lipoprotein (LDL) cholesterol minus high-density lipoprotein (HDL) cholesterol. Elevated levels of non-fasting/postprandial triglycerides directly correlate with elevated remnant cholesterol. In the general population, 38% of men have non......-fasting/postprandial triglycerides > 2mmol/L (>176 mg/dL) while 45% of men have non-fasting/postprandial triglyceride levels of 1-2 mmol/L (89-176 mg/dL); corresponding fractions in women are 20% and 47%. Also, 31% of men have remnant cholesterol levels > 1mmol/L (>39 mg/dL) while 46% of men have remnant cholesterol levels of 0...

  12. Characterization of fasted human gastric fluid for relevant rheological parameters and gastric lipase activities

    DEFF Research Database (Denmark)

    Pedersen, Pernille Barbre; Vilmann, Peter; Bar-Shalom, Daniel

    2013-01-01

    be considered important during development of gastric simulated media. Further, the activity of the HGL is active even under fasted gastric conditions and might contribute to the digestion and emulsification of lipid-based drug delivery systems in the entire gastrointestinal tract. HGL should therefore...... be considered in gastric evaluation of lipid-based drug delivery systems....

  13. Image segmentation and classification of white blood cells with the extreme learning machine and the fast relevance vector machine.

    Science.gov (United States)

    Ravikumar, S

    2016-05-01

    White blood cells (WBCs) or leukocytes are an important part of the body's defense against infectious organisms and foreign substances. WBC segmentation is a challenging issue because of the morphological diversity of WBCs and the complex and uncertain background of blood smear images. The standard ELM classification techniques are used for WBC segmentation. The generalization performance of the ELM classifier has not achieved the maximum nearest accuracy of image segmentation. This paper gives a novel technique for WBC detection based on the fast relevance vector machine (Fast-RVM). Firstly, astonishingly sparse relevance vectors (RVs) are obtained while fitting the histogram by RVM. Next, the relevant required threshold value is directly sifted from these limited RVs. Finally, the entire connective WBC regions are segmented from the original image. The proposed method successfully works for WBC detection, and effectively reduces the effects brought about by illumination and staining. To achieve the maximum accuracy of the RVM classifier, we design a search for the best value of the parameters that tune its discriminant function, and upstream by looking for the best subset of features that feed the classifier. Therefore, this proposed RVM method effectively works for WBC detection, and effectively reduces the computational time and preserves the images.

  14. Ultra-fast outflows (aka UFOs) in AGNs and their relevance for feedback

    Science.gov (United States)

    Cappi, Massimo; Tombesi, F.; Giustini, M.; Dadina, M.; Braito, V.; Kaastra, J.; Reeves, J.; Chartas, G.; Gaspari, M.; Vignali, C.; Gofford, J.; Lanzuisi, G.

    2012-09-01

    During the last decade, several observational evidences have been accumulated for the existence of massive, high velocity winds/outflows (aka UFOs) in nearby AGNs and, possibly, distant quasars. I will review here such evidences, present some of the latest results in this field, and discuss the relevance of UFOs for both understanding the physics of accretion/ejection flows on supermassive black holes, and for quantifying the amount of AGN feedback.

  15. [Management and orientation of severely infected patients : relevance of a « Sepsis Fast-Track »].

    Science.gov (United States)

    Juillerat, André; Vivekanantham, Hari; Burger, Raphaël; Hausser, Joëlle; Fumeaux, Thierry

    2017-09-06

    Sepsis is a syndrome defined by a life-threatening organ dysfunction caused by a dysregulated host response to an infection. The early recognition of this syndrome in the emergency department (ED) can lead to a better prognosis, when associated with a standardized management focusing on identification of the infectious source, its treatment, and appropriate organ support. Therefore, the implementation of a « Sepsis Fast Track », by analogy with similar protocols regarding stroke or ST-elevated myocardial infarct, deserves interest. The aim of this article is to review the available evidences that support an implementation of such an initiative, and to identify the key elements that permit its integration in the ED setting of a secondary-care hospital.

  16. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    Science.gov (United States)

    Milanesio, D.; Maggiora, R.

    2015-12-01

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  17. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    Energy Technology Data Exchange (ETDEWEB)

    Milanesio, D., E-mail: daniele.milanesio@polito.it; Maggiora, R. [Politecnico di Torino, Dipartimento di Elettronica e Telecomunicazioni (DET), Torino (Italy)

    2015-12-10

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  18. Response measurement of single-crystal chemical vapor deposition diamond radiation detector for intense X-rays aiming at neutron bang-time and neutron burn-history measurement on an inertial confinement fusion with fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Shimaoka, T., E-mail: t.shimaoka@eng.hokudai.ac.jp; Kaneko, J. H.; Tsubota, M. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Arikawa, Y.; Nagai, T.; Kojima, S.; Abe, Y.; Sakata, S.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H. [Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Isobe, M. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Sato, Y. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Chayahara, A.; Umezawa, H.; Shikata, S. [Diamond Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2015-05-15

    A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 × 10{sup 7} cm/s and 1.0 ± 0.3 × 10{sup 7} cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5–1 keV and neutron yield of more than 10{sup 9} neutrons/shot.

  19. Heat transfer characteristics of igniter output plumes

    Science.gov (United States)

    Evans, N. A.; Durand, N. A.

    Seven types of pyrotechnic igniters were each mounted at one end of a closed cylindrical bore hole representative of the center hole in a thermal battery. Measurements of local bore wall temperature, T(sub w), using commercially available, fast response (10 microsec) sheathed chromel-constantan thermocouples allowed calculation of local heat transfer rates, q, and wall heat flows, Q. The principal charge constituents of all these igniters were titanium and potassium perchlorate, while three types also contained barium styphnate as an ignition sensitizer. Igniter closure disc materials included glass-ceramic, glass, metal (plain, scored, with and without capture cone), and kapton/RTV. All igniters produced the lowest values of T(sub w) and q at the beginning of the bore, and, except for the igniter with the kapton/RTV closure disc, these quantities increased with distance along the bore. For igniters containing only titanium/potassium perchlorate, the rates of increase of Q along the bore length, compared with those for T(sub w) and q, were generally lower and more variable. The inclusion of barium styphnate produced rates of change in Q that were essentially constant to the end of the bore. The highest overall average wall temperatures were achieved by two igniter types with metal closure discs and no capture cone. No clear correlation was established between peak bore pressure and maximum wall temperature.

  20. Heat transfer characteristics of igniter output plumes

    Energy Technology Data Exchange (ETDEWEB)

    Evans, N.A.; Durand, N.A.

    1989-01-01

    Seven types of pyrotechnic igniters were each mounted at one end of a closed cylindrical bore hole representative of the center hole in a thermal battery. Measurements of local bore wall temperature, T/sub w/, using commercially available, fast response (10 /mu/sec) sheathed chromel-constantan thermocouples allowed calculation of local heat transfer rates, q, and wall heat flows, Q. The principal charge constituents of all these igniters were titanium and potassium perchlorate, while three types also contained barium styphnate as an ignition sensitizer. Igniter closure disc materials included glass-ceramic, glass, metal (plain, scored, with and without capture cone), and kapton/RTV. All igniters produced the lowest values of T/sub w/ and q at the beginning of the bore, and, except for the igniter with the kapton/RTV closure disc, these quantities increased with distance along the bore. For igniters containing only titanium/potassium perchlorate, the rates of increase of Q along the bore length, compared with those for T/sub w/ and q, were generally lower and more variable. The inclusion of barium styphnate produced rates of change in Q that were essentially constant to the end of the bore. The highest overall average wall temperatures were achieved by two igniter types with metal closure discs and no capture cone. No clear correlation was established between peak bore pressure and maximum wall temperature. 3 refs., 8 figs., 1 tab.

  1. IGNITION AND FRONTIER SCIENCE ON THE NATIONAL IGNITION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E

    2009-06-22

    of Inertial Fusion Energy (IFE) and will likely focus the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed and has high probability of success. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and Fast Ignition concepts. Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. The NIC will develop the full set of capabilities required to operate NIF as a major national and international user facility. A solicitation for NIF frontier science experiments to be conducted by the academic community is planned for summer 2009. This paper summarizes the design, performance, and status of NIF, experimental plans for NIC, and will present a brief discussion of the unparalleled opportunities to explore frontier basic science that will be available on the NIF.

  2. FAST

    DEFF Research Database (Denmark)

    Zuidmeer-Jongejan, Laurian; Fernandez-Rivas, Montserrat; Poulsen, Lars K.

    2012-01-01

    ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections with aqu......ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections...... with aqueous food extracts may be effective but has proven to be accompanied by too many anaphylactic side-effects. FAST aims to develop a safe alternative by replacing food extracts with hypoallergenic recombinant major allergens as the active ingredients of SIT. Both severe fish and peach allergy are caused...... in depth serological and cellular immune analyses will be performed, allowing identification of novel biomarkers for monitoring treatment efficacy. FAST aims at improving the quality of life of food allergic patients by providing a safe and effective treatment that will significantly lower their threshold...

  3. Self-ignition and oxidation of various hydrocarbons between 600 and 1000 K at high pressure: experimental study with fast compression machine and modeling; Autoinflammation et oxydation de divers hydrocarbures entre 600 et 1000 K a haute pression: etude experimentale en machine a compression rapide et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Ribaucour, M.

    2002-12-01

    Low- and intermediate-temperature oxidation and self-ignition of hydrocarbons play a major role in spark ignition, diesel and HCCI (homogenous charge compression ignition) engines. A deep understanding of the chemistry linked with both phenomena is necessary to improve the engines efficiency and to reduce the formation of pollutants. This document treats of works about the self-ignition and oxidation at high pressure of various hydrocarbons between 600 and 1000 deg. K. The experimental tool used is a fast compression machine fitted with a fast sampling system for the measurement of self-ignition delays and of the concentrations of intermediate oxidation products. The advantages and limitations of this tool are discussed. The self-ignition of various hydrocarbons is compared using pre-defined data which characterize the phenomenologies like cold flames, negative temperature coefficients and self-ignition limits. The hydrocarbons considered are pure or binary mixtures of alkanes, pent-1-ene and n-butyl-benzene. The development of high pressure oxidation reaction schemes of alkanes between 600 and 1000 deg. K is described. It is directly based on the analysis of intermediate oxidation products. This methodology is also applied to pent-1-ene and n-butyl-benzene. The construction of detailed thermo-kinetic models of oxidation and the modeling of phenomena are made for n-butane, n-heptane, for the 3 pentane isomers, for pent-1-ene and n-butyl-benzene. Finally, the perspectives of future works are evoked. They concern new modeling and new methodologies to be applied in more predictive thermo-kinetic models and the reduction of detailed models in order to include them inside fluid dynamics codes. (J.S.)

  4. Local Ignition in Carbon/Oxygen White Dwarfs -- I: One-zone Ignition and Spherical Shock Ignition of Detonations

    CERN Document Server

    Dursi, L J

    2006-01-01

    The details of ignition of Type Ia supernovae remain fuzzy, despite the importance of this input for any large-scale model of the final explosion. Here, we begin a process of understanding the ignition of these hotspots by examining the burning of one zone of material, and then investigate the ignition of a detonation due to rapid heating at single point. We numerically measure the ignition delay time for onset of burning in mixtures of degenerate material and provide fitting formula for conditions of relevance in the Type Ia problem. Using the neon abundance as a proxy for the white dwarf metallicity, we then find that ignition times can decrease by ~20% with addition of even 5% of neon by mass. When temperature fluctuations that successfully kindle a region are very rare, such a reduction in ignition time can increase the probability of ignition by orders of magnitude. We then consider the ignition of a detonation by an explosive energy input in one localized zone, eg a Sedov blast wave leading to a shock-i...

  5. Hydrodynamic modeling and simulations of shock ignition thresholds

    Directory of Open Access Journals (Sweden)

    Lafon M.

    2013-11-01

    Full Text Available The Shock Ignition (SI scheme [1] offers to reduce the laser requirements by relaxing the implosion phase to sub-ignition velocities and later adding an intense laser spike. Depending on laser energy, target characteristics and implosion velocity, high gains are expected [2,3]. Relevant intensities for scaled targets imploded in the velocity range from 150 to 400 km/s are defined at ignition thresholds. A range of moderate implosion velocities is specified to match safe implosions. These conditions for target design are then inferred for relevant NIF and LMJ shock-ignited targets.

  6. Dual coil ignition system

    Energy Technology Data Exchange (ETDEWEB)

    Huberts, Garlan J.; Qu, Qiuping; Czekala, Michael Damian

    2017-03-28

    A dual coil ignition system is provided. The dual coil ignition system includes a first inductive ignition coil including a first primary winding and a first secondary winding, and a second inductive ignition coil including a second primary winding and a second secondary winding, the second secondary winding connected in series to the first secondary winding. The dual coil ignition system further includes a diode network including a first diode and a second diode connected between the first secondary winding and the second secondary winding.

  7. Stability of Ignition Transients

    Directory of Open Access Journals (Sweden)

    V.E. Zarko

    1991-07-01

    Full Text Available The problem of ignition stability arises in the case of the action of intense external heat stimuli when, resulting from the cut-off of solid substance heating, momentary ignition is followed by extinction. Physical pattern of solid propellant ignition is considered and ignition criteria available in the literature are discussed. It is shown that the above mentioned problem amounts to transient burning at a given arbitrary temperature distribution in the condensed phase. A brief survey of published data on experimental and theoretical studies on ignition stability is offered. The comparison between theory and experiment is shown to prove qualitatively the efficiency of the phenomenological approach in the theory. However, the methods of mathematical simulation as well as those of experimental studying of ignition phenomenon, especially at high fluxes, need to be improved.

  8. A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility

    Science.gov (United States)

    Sutcliffe, G. D.; Milanese, L. M.; Orozco, D.; Lahmann, B.; Gatu Johnson, M.; Séguin, F. H.; Sio, H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.; Park, H.-S.; Rygg, J. R.; Casey, D. T.; Bionta, R.; Turnbull, D. P.; Huntington, C. M.; Ross, J. S.; Zylstra, A. B.; Rosenberg, M. J.; Glebov, V. Yu.

    2016-11-01

    CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint of the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.

  9. A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Sutcliffe, G. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Milanese, L. M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Orozco, D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Lahmann, B. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Gatu Johnson, M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Séguin, F. H. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Sio, H. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Frenje, J. A. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Li, C. K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; Park, H. -S. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Rygg, J. R. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Casey, D. T. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Bionta, R. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Turnbull, D. P. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Huntington, C. M. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Ross, J. S. [Lawrence Livermore National Laboratory, Livermore, California 94550, USA; Zylstra, A. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA; Rosenberg, M. J. [Laboratory for Laser Energetics, Rochester, New York 14623, USA; Glebov, V. Yu. [Laboratory for Laser Energetics, Rochester, New York 14623, USA

    2016-08-05

    CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint of the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.

  10. A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Sutcliffe, G. D., E-mail: gdsut@mit.edu; Milanese, L. M.; Orozco, D.; Lahmann, B.; Gatu Johnson, M.; Séguin, F. H.; Sio, H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Park, H.-S.; Rygg, J. R.; Casey, D. T.; Bionta, R.; Turnbull, D. P.; Huntington, C. M.; Ross, J. S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Zylstra, A. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rosenberg, M. J.; Glebov, V. Yu. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States)

    2016-11-15

    CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint of the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.

  11. Experimental study on ignition characteristics of pulverized coal under high-temperature oxygen condition

    Science.gov (United States)

    Liu, G. W.; Liu, Y. H.; Dong, P.

    2016-08-01

    The high-temperature oxygen ignition technology of pulverized coal, which can replace the oil gun and achieve oil-free pulverized coal ignition by mixing the high- temperature oxygen and the pulverized coal stream directly, was proposed and a relevant ignition experimental system was built. The ignition characteristics of pulverized coal under high-temperature oxygen condition were investigated: the ignition process was described and analyzed, the influence of relevant parameters on the pulverized coal stream ignition were obtained and analyzed. The results showed: when the oxygen heating temperature is over 750 °C, the pulverized coal stream could be ignited successfully by high-temperature oxygen; increasing the pulverized coal concentration, primary air temperature and oxygen volume flow rate or decreasing the primary air velocity is helpful for the ignition and combustion of the pulverized coal stream.

  12. Using k-alpha emission to determine fast electron spectra using the Hybrid code ZEPHYROS

    CERN Document Server

    White, Thomas; Gregori, Gianluca

    2014-01-01

    A high intensity laser-solid interaction invariably drives a non-thermal fast electron current through the target, however characterizing these fast electron distributions can prove difficult. An understanding of how these electrons propagate through dense materials is of fundamental interest and has applications relevant to fast ignition schemes and ion acceleration. Here, we utilize an upgraded version of the Hybrid code ZEPHYROS to demonstrate how the resulting k-alpha emission from such an interaction can be used as a diagnostic to obtain the characteristic temperature, divergence and total energy of the fast electron population.

  13. Laser Diode Ignition (LDI)

    Science.gov (United States)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  14. Progress and prospects for an FI relevant point design

    Energy Technology Data Exchange (ETDEWEB)

    Key, M; Amendt, P; Bellei, C; Clark, D; Cohen, B; Divol, L; Ho, D; Kemp, A; Larson, D; Marinak, M; Patel, P; Shay, H; Strozzi, D; Tabak, M

    2011-11-02

    The physics issues involved in scaling from sub ignition to high gain fast ignition are discussed. Successful point designs must collimate the electrons and minimize the stand off distance to avoid multi mega-joule ignition energies. Collimating B field configurations are identified and some initial designs are explored.

  15. Progress and prospects for an IFE relevant FI point design

    Science.gov (United States)

    Key, M.; Amendt, P.; Bellei, C.; Clark, D.; Cohen, B.; Divol, L.; Ho, D.; Kemp, A.; Larson, D.; Marinak, M.; Patel, P.; Shay, H.; Strozzi, D.; Tabak, M.

    2013-11-01

    The physics issues involved in scaling from sub-ignition to high gain fast ignition are discussed. Successful point designs must collimate the electrons and minimise the standoff distance to avoid multi-megajoule ignition energies. Collimating B field configurations are identified and some initial designs are explored.

  16. Ignition of magnetic deflagration in Mn12 acetate

    Science.gov (United States)

    McHugh, Sean; Jaafar, R.; Sarachik, M. P.; Myasoedov, Y.; Finkler, A.; Shtrikman, H.; Zeldov, E.; Bagai, R.; Christou, G.

    2008-03-01

    We study the conditions for the ignition of two types of magnetic avalanches in the molecular magnet Mn12-acetate corresponding to the major species and a fast-relaxing minor species. The minor component, which has a lower anisotropy barrier, exists in these crystals at the level of 5-7%. The ignition temperatures are measured using small (30 x30 μm^2) Ge thermometers. In addition, the magnetization dynamics are measured using an array of Hall sensors of comparable size. Various aspects of the ignition will be discussed, including: the reduction of the ignition threshold due to quantum tunneling, the catalytic effect of the minor species, and the shift of the ignition point as a function of external magnetic field. The work at City College was supported by NSF grant DMR-00451605. E. Z. acknowledges the support of the Israel Ministry of Science, Culture and Sports. Support for G. C. was provided by NSF grant CHE-0414555.

  17. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  18. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  19. Spontaneously Igniting Hybrid Fuel-Oxidiser Systems

    Directory of Open Access Journals (Sweden)

    S. R. Jain

    1995-01-01

    Full Text Available After briefly outlining the recent developments in hybrid rockets, the work carried out by the author on self-igniting (hypergolic solid fuel-liquid oxidiser systems has been reviewed. A major aspect relates to the solid derivatives of hydrazines, which have been conceived as fuels for hybrid rockets. Many of these N-N bonded compounds ignite readily, with very short ignition delays, on coming into contact with liquid oxidisers, like HNO/sub 3/ and N/sub 2/ O/sub 4/. The ignition characteristics have been examined as a function of the nature of the functional group in the fuel molecule, in an attempt to establish a basis for the hypergolic ignition in terms of chemical reactivity of the fuel-oxidiser combination. Important chemical reactions occurring in the pre-ignition stage have been identified by examining the quenched reaction products. Hybrid systems exhibiting synergistic hypergolicity in the presence of metal powders have investigated. An estimation of the rocket performance parameters, experimental determination of the heats of combustion in HNO/sub 3/, thermal decomposition characteristics, temperature profile by thin film thermometry and product identification by the rapid scan FT-IR, are among the other relevant studies made on these systems. A significant recent development has been the synthesis of new N-N bonded viscous binders, capable of rataining the hypergolicity of the fuel powders embedded therein as well as providing the required mechanical strength to the grain. Several of these resins have been characterised. Metallised fuel composites of these resins having high loading of magnesium are found to have short ignition delays and high performance parameters.

  20. The lean burn direct injection jet ignition gas engine

    Energy Technology Data Exchange (ETDEWEB)

    Boretti, Alberto A.; Watson, Harry C. [School of Science and Engineering, University of Ballarat, PO Box 663, Ballarat, Victoria 3353 (Australia)

    2009-09-15

    This paper presents a new in-cylinder mixture preparation and ignition system for various fuels including hydrogen, methane and propane. The system comprises a centrally located direct injection (DI) injector and a jet ignition (JI) device for combustion of the main chamber (MC) mixture. The fuel is injected in the MC with a new generation, fast actuating, high pressure, high flow rate DI injector capable of injection shaping and multiple events. This injector produces a bulk, lean stratified mixture. The JI system uses a second DI injector to inject a small amount of fuel in a small pre-chamber (PC). In the spark ignition (SI) version, a spark plug then ignites a slightly rich mixture. In the auto ignition version, a DI injector injects a small amount of higher pressure fuel in the small PC having a hot glow plug (GP) surface, and the fuel auto ignites in the hot air or when in contact with the hot surface. Either way the MC mixture is then bulk ignited through multiple jets of hot reacting gases. Bulk ignition of the lean, jet controlled, stratified MC mixture resulting from coupling DI with JI makes it possible to burn MC mixtures with fuel to air equivalence ratios reducing almost to zero for a throttle-less control of load diesel-like and high efficiencies over almost the full range of loads. (author)

  1. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter; Etude experimentale de la propagation et du depot d'energie d'electrons rapides dans une cible solide ou comprimee par choc laser: application a l'allumeur rapide

    Energy Technology Data Exchange (ETDEWEB)

    Pisani, F

    2000-02-15

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  2. Fast Prediction with Sparse Multikernel LS-SVR Using Multiple Relevant Time Series and Its Application in Avionics System

    Directory of Open Access Journals (Sweden)

    Yang M. Guo

    2015-01-01

    Full Text Available Health trend prediction is critical to ensure the safe operation of highly reliable systems. However, complex systems often present complex dynamic behaviors and uncertainty, which makes it difficult to develop a precise physical prediction model. Therefore, time series is often used for prediction in this case. In this paper, in order to obtain better prediction accuracy in shorter computation time, we propose a new scheme which utilizes multiple relevant time series to enhance the completeness of the information and adopts a prediction model based on least squares support vector regression (LS-SVR to perform prediction. In the scheme, we apply two innovative ways to overcome the drawbacks of the reported approaches. One is to remove certain support vectors by measuring the linear correlation to increase sparseness of LS-SVR; the other one is to determine the linear combination weights of multiple kernels by calculating the root mean squared error of each basis kernel. The results of prediction experiments indicate preliminarily that the proposed method is an effective approach for its good prediction accuracy and low computation time, and it is a valuable method in applications.

  3. Ignition Studies on Aluminised Propellant.

    Directory of Open Access Journals (Sweden)

    K. A. Bhaskaran

    1996-12-01

    Full Text Available An experimental investigation on the ignition of metallised propellants (APIHTPB/AI has been carried out 10 determine the ignition delay, minimum ignition energy and corresponding heat flux,threshold heat flux for ignition and minimum ignition temperature, Ignition experiments were conductedusing a shock tube under convectiveheating conditions similar to those prevailingin a rocket motor. Heat flux at propellant location was measured by thin film heat flux gauge and also calculated from a ribbon thermocouple output under similar test conditions. The igntion delay was measured as the time lag between the arrival of hot gas at the propellant and the light emission due to actual ignition of the propellant. The experimental results indicate that the ignition delay characteristics are independent of pressure. The minimum energy for ignition obtained for the propellant is 1100J/m2 corresponding to the heat flux range of 80·120 WIcm2 for a gas velocity of 110 mls. The threshold heat flux required to ignite the propellant was 40 W/cm2 at a velocity of 110 mls. Heat flux corresponding to minimum ignition energy and the threshold heat flux increase with gas velocity. The threshold ignition temperature of the propellant was found to be 600 ± 20 K.

  4. The National Ignition Facility (NIF) and the National Ignition Campaign (NIC)

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E

    2009-09-17

    likely focus the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and Fast Ignition concepts. Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. The NIC will develop the full set of capabilities required to operate NIF as a major national and international user facility. A solicitation for NIF frontier science experiments is planned for summer 2009. This paper summarizes the design, performance, and status of NIF and plans for the NIF ignition experimental program. A brief summary of the overall NIF experimental program is also presented.

  5. PETN ignition experiments and models.

    Science.gov (United States)

    Hobbs, Michael L; Wente, William B; Kaneshige, Michael J

    2010-04-29

    Ignition experiments from various sources, including our own laboratory, have been used to develop a simple ignition model for pentaerythritol tetranitrate (PETN). The experiments consist of differential thermal analysis, thermogravimetric analysis, differential scanning calorimetry, beaker tests, one-dimensional time to explosion tests, Sandia's instrumented thermal ignition tests (SITI), and thermal ignition of nonelectrical detonators. The model developed using this data consists of a one-step, first-order, pressure-independent mechanism used to predict pressure, temperature, and time to ignition for various configurations. The model was used to assess the state of the degraded PETN at the onset of ignition. We propose that cookoff violence for PETN can be correlated with the extent of reaction at the onset of ignition. This hypothesis was tested by evaluating metal deformation produced from detonators encased in copper as well as comparing postignition photos of the SITI experiments.

  6. Burner ignition system

    Science.gov (United States)

    Carignan, Forest J.

    1986-01-21

    An electronic ignition system for a gas burner is battery operated. The battery voltage is applied through a DC-DC chopper to a step-up transformer to charge a capacitor which provides the ignition spark. The step-up transformer has a significant leakage reactance in order to limit current flow from the battery during initial charging of the capacitor. A tank circuit at the input of the transformer returns magnetizing current resulting from the leakage reactance to the primary in succeeding cycles. An SCR in the output circuit is gated through a voltage divider which senses current flow through a flame. Once the flame is sensed, further sparks are precluded. The same flame sensor enables a thermopile driven main valve actuating circuit. A safety valve in series with the main gas valve responds to a control pressure thermostatically applied through a diaphragm. The valve closes after a predetermined delay determined by a time delay orifice if the pilot gas is not ignited.

  7. A fast approach for detection of erythemato-squamous diseases based on extreme learning machine with maximum relevance minimum redundancy feature selection

    Science.gov (United States)

    Liu, Tong; Hu, Liang; Ma, Chao; Wang, Zhi-Yan; Chen, Hui-Ling

    2015-04-01

    In this paper, a novel hybrid method, which integrates an effective filter maximum relevance minimum redundancy (MRMR) and a fast classifier extreme learning machine (ELM), has been introduced for diagnosing erythemato-squamous (ES) diseases. In the proposed method, MRMR is employed as a feature selection tool for dimensionality reduction in order to further improve the diagnostic accuracy of the ELM classifier. The impact of the type of activation functions, the number of hidden neurons and the size of the feature subsets on the performance of ELM have been investigated in detail. The effectiveness of the proposed method has been rigorously evaluated against the ES disease dataset, a benchmark dataset, from UCI machine learning database in terms of classification accuracy. Experimental results have demonstrated that our method has achieved the best classification accuracy of 98.89% and an average accuracy of 98.55% via 10-fold cross-validation technique. The proposed method might serve as a new candidate of powerful methods for diagnosing ES diseases.

  8. Shock Tube Ignition Delay Data Affected by Localized Ignition Phenomena

    KAUST Repository

    Javed, Tamour

    2016-12-29

    Shock tubes have conventionally been used for measuring high-temperature ignition delay times ~ O(1 ms). In the last decade or so, the operating regime of shock tubes has been extended to lower temperatures by accessing longer observation times. Such measurements may potentially be affected by some non-ideal phenomena. The purpose of this work is to measure long ignition delay times for fuels exhibiting negative temperature coefficient (NTC) and to assess the impact of shock tube non-idealities on ignition delay data. Ignition delay times of n-heptane and n-hexane were measured over the temperature range of 650 – 1250 K and pressures near 1.5 atm. Driver gas tailoring and long length of shock tube driver section were utilized to measure ignition delay times as long as 32 ms. Measured ignition delay times agree with chemical kinetic models at high (> 1100 K) and low (< 700 K) temperatures. In the intermediate temperature range (700 – 1100 K), however, significant discrepancies are observed between the measurements and homogeneous ignition delay simulations. It is postulated, based on experimental observations, that localized ignition kernels could affect the ignition delay times at the intermediate temperatures, which lead to compression (and heating) of the bulk gas and result in expediting the overall ignition event. The postulate is validated through simple representative computational fluid dynamic simulations of post-shock gas mixtures which exhibit ignition advancement via a hot spot. The results of the current work show that ignition delay times measured by shock tubes may be affected by non-ideal phenomena for certain conditions of temperature, pressure and fuel reactivity. Care must, therefore, be exercised in using such data for chemical kinetic model development and validation.

  9. Experimental Investigation on the Ignition Delay Time of Plasma-Assisted Ignition

    Science.gov (United States)

    Xiao, Yang; Yu, Jin-Lu; He, Li-Ming; Jiang, Yong-Jian; Wu, Yong

    2016-09-01

    This paper investigates the ignition performances of plasma-assisted ignition in propane/air mixture. The results show that a shorter ignition delay time is obtained for the plasma ignition than the spark ignition and the average ignition delay time of plasma-assisted ignition can be reduced at least by 50%. The influence of air flow rate of combustor, the arc current and argon flow rate of plasma igniter on ignition delay time are also investigated. The ignition delay time of plasma-assisted ignition increases with increasing air flow rate in the combustor. By increasing the arc current, the plasma ignition will gain more ignition energy to ignite the mixture more easily. The influence of plasma ignition argon flow rates on the ignition delay time is quite minor.

  10. Ignition target design for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Haan, S.W.; Pollaine, S.M.; Lindl, J.D. [Los Alamos National Laboratory, NM (United States)] [and others

    1996-06-01

    The goal of inertial confinement fusion (ICF) is to produce significant thermonuclear burn from a target driven with a laser or ion beam. To achieve that goal, the national ICF Program has proposed a laser capable of producing ignition and intermediate gain. The facility is called the National Ignition Facility (NIF). This article describes ignition targets designed for the NIF and their modeling. Although the baseline NIF target design, described herein, is indirect drive, the facility will also be capable of doing direct-drive ignition targets - currently being developed at the University of Rochester.

  11. Towards a general turbulent combustion model for spark ignition engines

    Energy Technology Data Exchange (ETDEWEB)

    Naji, H.; Said, R.; Borghi, R.P.

    1989-01-01

    The prediction of combustion within spark ignition engines needs to take into account the interaction of turbulent fluctuations. Previous attempts at this used a model in which the chemical processes were supposed infinitely fast and the combustion was controlled by turbulent mixing only. This paper describes their progress in extending such models in two directions.

  12. Integrated thermodynamic model for ignition target performance

    Directory of Open Access Journals (Sweden)

    Springer P.T.

    2013-11-01

    Full Text Available We have derived a 3-dimensional synthetic model for NIF implosion conditions, by predicting and optimizing fits to a broad set of x-ray and nuclear diagnostics obtained on each shot. By matching x-ray images, burn width, neutron time-of-flight ion temperature, yield, and fuel ρr, we obtain nearly unique constraints on conditions in the hotspot and fuel in a model that is entirely consistent with the observables. This model allows us to determine hotspot density, pressure, areal density (ρr, total energy, and other ignition-relevant parameters not available from any single diagnostic. This article describes the model and its application to National Ignition Facility (NIF tritium–hydrogen–deuterium (THD and DT implosion data, and provides an explanation for the large yield and ρr degradation compared to numerical code predictions.

  13. In-vitro estimation of bioaccessibility of chlorinated organophosphate flame retardants in indoor dust by fasting and fed physiologically relevant extraction tests.

    Science.gov (United States)

    Quintana, José Benito; Rosende, María; Montes, Rosa; Rodríguez-Álvarez, Tania; Rodil, Rosario; Cela, Rafael; Miró, Manuel

    2017-02-15

    This paper reports the evaluation of in-vitro physiologically relevant extraction tests for ascertainment of the bioaccessible fractions of emerging flame retardants from indoor dust in the gastric and gastrointestinal compartments. Standardized bioaccessibility tests under both fasting (UBM-like test) and fed (FOREhST test) conditions simulating the macronutrient composition of an average child diet were harnessed for investigation of the oral bioaccessibility of chlorinated organophosphate esters, namely, tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP) and tris(1,3-dichloro-2-propyl) phosphate (TDCP), in household and automobile cabin dust samples with varying concentration levels of contaminants. Minimal processing of the biomimetic extracts (only protein precipitation using acetonitrile) was proven feasible by analysis with liquid chromatography-mass spectrometric detection (LC-MS/MS). An inversely proportional relationship was identified between log Kow and oral bioaccessibility concentrations for TCEP, TCPP and TDCP in both dust samples with maximum bioaccessibility fractions for TCEP within the range of 50-103%. Non-bioaccessible fractions were determined by matrix-solid phase dispersion. Limits of quantification of LC-MS/MS in surrogate digestive fluids ranging from 0.4-0.8ng/mL suffice for determination of freely dissolved fractions of the two less hydrophobic species. Our results indicate that lipophilic food commodities used under fed-state gastrointestinal extraction conditions do not increase availability of TCEP, TCPP and TDCP in body fluids, and therefore conservative conditions in human health risk explorations for the target moderately polar flame retardants might be obtained with simplified tests under fasting conditions. This also holds true for the UBM/FOREhST bioaccessibility data for SRM 2585 (organic contaminants in house dust). Estimated average daily intake doses for toddlers incorporating oral

  14. Intermediate species measurement during iso-butanol auto-ignition

    KAUST Repository

    Ji, Weiqi

    2015-10-01

    © 2015 The Combustion Institute.Published by Elsevier Inc. All rights reserved. This work presents the time histories of intermediate species during the auto-ignition of iso-butanol at high pressure and intermediate temperature conditions obtained using a rapid compression machine and recently developed fast sampling system. Iso-butanol ignition delays were acquired for iso-butanol/O2 mixture with an inert/O2 ratio of 7.26, equivalence ratio of 0.4, in the temperature range of 840-950 K and at pressure of 25 bar. Fast sampling and gas chromatography were used to acquire and quantify the intermediate species during the ignition delay of the same mixture at P = 25.3 bar and T = 905 K. The ignition delay times and quantitative measurements of the mole fraction time histories of methane, ethene, propene, iso-butene, iso-butyraldehyde, iso-butanol, and carbon monoxide were compared with predictions from the detailed mechanisms developed by Sarathy et al., Merchant et al., and Cai et al. It is shown that while the Sarathy mechanism well predicts the overall ignition delay time, it overpredicts ethene by a factor of 6-10, underpredicts iso-butene by a factor of 2, and overpredicts iso-butyraldehyde by a factor of 2. Reaction path and sensitivity analyses were carried out to identify the reactions responsible for the observed inadequacy. The rates of iso-butanol hydrogen atom abstraction by OH radical and the beta-scission reactions of hydroxybutyl radicals were updated based on recently published quantum calculation results. Significant improvements were achieved in predicting ignition delay at high pressures (25 and 30 bar) and the species concentrations of ethene and iso-butene. However, the updated mechanism still overpredicts iso-butyraldehyde concentrations. Also, the updated mechanism degrades the prediction in ignition delay at lower pressure (15 bar) compared to the original mechanism developed by Sarathy et al.

  15. National Ignition Facility under fire over ignition failure

    Science.gov (United States)

    Allen, Michael

    2016-08-01

    The 3.5bn National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California is no nearer to igniting a sustainable nuclear fusion burn - four years after its initial target date - according to a report by the US National Nuclear Security Administration (NNSA).

  16. Plastic ablator ignition capsule design for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D S; Haan, S W; Hammel, B A; Salmonson, J D; Callahan, D A; Town, R P

    2009-12-01

    The National Ignition Campaign, tasked with designing and fielding targets for fusion ignition experiments on the National Ignition Facility (NIF), has carried forward three complementary target designs for the past several years: a beryllium ablator design, a plastic ablator design, and a high-density carbon or synthetic diamond design. This paper describes current simulations and design optimization to develop the plastic ablator capsule design as a candidate for the first ignition attempt on NIF. The trade-offs in capsule scale and laser energy that must be made to achieve a comparable ignition probability to that with beryllium are emphasized. Large numbers of 1-D simulations, meant to assess the statistical behavior of the target design, as well as 2-D simulations to assess the target's susceptibility to Rayleigh-Taylor growth are presented.

  17. Controlling the fast electron divergence in a solid target with multiple laser pulses

    Science.gov (United States)

    Volpe, L.; Feugeas, J.-L.; Nicolai, Ph.; Santos, J. J.; Touati, M.; Breil, J.; Batani, D.; Tikhonchuk, V.

    2014-12-01

    Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.

  18. Ignition and Inertial Confinement Fusion at The National Ignition Facility

    Science.gov (United States)

    Moses, Edward I.

    2016-10-01

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear bum in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm3-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIP's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY20l0 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

  19. Interpreting Shock Tube Ignition Data

    Science.gov (United States)

    2003-10-01

    times only for high concentrations (of order 1% fuel or greater). The requirements of engine (IC, HCCI , CI and SI) modelers also present a different...Paper 03F-61 Interpreting Shock Tube Ignition Data D. F. Davidson and R. K. Hanson Mechanical Engineering ... Engineering Department Stanford University, Stanford CA 94305 Abstract Chemical kinetic modelers make extensive use of shock tube ignition data

  20. Physics Experiments Planned for the National Ignition Facility

    Science.gov (United States)

    Verdon, Charles P.

    1998-11-01

    This talk will review the current status and plans for high energy density physics experiments to be conducted on the National Ignition Facility (NIF). The NIF a multi-laboratory effort, presently under construction at the Lawrence Livermore National Laboratory, is a 192 beam solid state glass laser system designed to deliver 1.8MJ (at 351nm) in temporal shaped pulses. This review will begin by introducing the NIF in the context of its role in the overall United States Stockpile Stewardship Program. The major focus of this talk will be to describe the physics experiments planned for the NIF. By way of introduction to the experiments a short review of the NIF facility design and projected capabilities will be presented. In addition the current plans and time line for the activation of the laser and experimental facilities will also be reviewed. The majority of this talk will focus on describing the national inertial confinement fusion integrated theory and experimental target ignition plan. This national plan details the theory and experimental program required for achieving ignition and modest thermonuclear gain on the NIF. This section of the presentation will include a status of the current physics basis, ignition target designs, and target fabrication issues associated with the indirect-drive and direct-drive approaches to ignition. The NIF design provides the capabilities to support experiments for both approaches to ignition. Other uses for the NIF, including non ignition physics relevant to the national security mission, studies relevant to Inertial Fusion Energy, and basic science applications, will also be described. The NIF offers the potential to generate new basic scientific understanding about matter under extreme conditions by making available a unique facility for research into: astrophysics and space physics, hydrodynamics, condensed matter physics, material properties, plasma physics and radiation sources, and radiative properties. Examples of

  1. Experimental Investigation of Piston Heat Transfer in a Light Duty Engine Under Conventional Diesel, Homogeneous Charge Compression Ignition, and Reactivity Controlled Compression Ignition Combustion Regimes

    Science.gov (United States)

    2014-01-15

    engine speed and load conditions. The closed-cycle integrated and peak heat transfer rates were found to be lower for HCCI and RCCI when compared to...limit the load of HCCI due to practical engine limitations. Additionally, HCCI lacks a fast-response combustion phasing control, such as spark...cylinder research engine under Conventional Diesel (CDC), Homogeneous Charge Compression Ignition ( HCCI ), and Reactivity Controlled Compression Ignition

  2. On-line coupling of physiologically relevant bioaccessibility testing to inductively coupled plasma spectrometry: Proof of concept for fast assessment of gastrointestinal bioaccessibility of micronutrients from soybeans.

    Science.gov (United States)

    Herrera, Mónica Alejandra; Rosende, María; Arruda, Marco Aurélio Zezzi; Miró, Manuel

    2016-10-05

    In-vitro physiologically relevant gastrointestinal extraction based on the validated Unified BARGE Method (UBM) is in this work hyphenated to inductively coupled plasma optical emission spectrometry in a batch-flow configuration for real-time monitoring of oral bioaccessibility assays with high temporal resolution. A fully automated flow analyzer is designed to foster in-line filtration of gastrointestinal extracts at predefined times (≤15 min) followed by on-line multi-elemental analysis of bioaccessible micro-nutrients, viz., Cu, Fe and Mn, in well-defined volumes of extracts (300 μL) of transgenic and non-transgenic soybean seeds taken as model samples. The hyphenated flow setup allows for recording of temporal extraction profiles to gain full knowledge of the kinetics of the gastrointestinal digestion processes, including element leaching and concomitant precipitation and complexation reactions hindering bioavailability. Simplification of the overall standard procedure is also feasible by identification of steady-state extraction conditions. Our findings indicate that reliable measurement of oral bioaccessible pools of Cu, Fe and Mn in soybean might be obtained in less than 180 min rather than 240 min as endorsed by UBM. Using a matrix-matched external calibration, limits of detection according to the 3s criteria were 0.5 μg/g for Mn, 0.6 μg/g for Cu and 2.3 μg/g for Fe. Trueness of the automatic bioaccessibility method was confirmed by mass balance validation with recoveries ranging from 87 to 116% regardless of the target element and sample. Cu was the micronutrient with the highest oral bioaccessibility ranging from 73% to 83% (7.5-7.9 μg/g) for non-transgenic and transgenic soybeans, respectively, followed by Mn and Fe within the ranges of 29-31% (10.8-11.4 μg/g) and 11-15% (8-14 μg/g), respectively, regardless of transgenesis. The proposed kinetic method is proven suitable for fast and expedient estimation of the nutritional value of

  3. Self-ignition and ignition of aluminum powders in shock waves

    Science.gov (United States)

    Boiko, V. M.; Poplavski, S. V.

    Ignition of fine aluminum powders in reflected shock waves has been studied. Two ignition regimes are found: self-ignition observed at temperatures higher than 1800 K and ``low-temperature'' ignition at temperatures of 1000-1800 K. The possibility of initiating the ignition of aluminum powders in air using combustible liquids has been studied too.

  4. An investigation of the ignition probability and data analysis for the detection of relevant parameters of mechanically generated steel sparks in explosive gas/air-mixtures; Untersuchungen zur Zuendwahrscheinlichkeit und Datenanalyse zur Erfassung der Einflussgroessen mechanisch erzeugter Stahl-Schlagfunktion in explosionsfaehigen Brenngas/Luft-Gemischen

    Energy Technology Data Exchange (ETDEWEB)

    Grunewald, Thomas; Finke, Robert; Graetz, Rainer

    2010-07-01

    Mechanically generated sparks are a potential source of ignition in highly combustible areas. A multiplicity of mechanical and reaction-kinetic influences causes a complex interaction of parameters. It is only little known about their effect on the ignition probability. The ignition probability of mechanically generated sparks with a material combination of unalloyed steel/unalloyed steel and with an kinetic impact energy between 3 and 277 Nm could be determined statistically tolerable. In addition, the explosiveness of not oxidized particles at increased temperatures in excess stoichiometric mixtures was proven. A unique correlation between impact energy and ignition probability as well as a correlation of impact energy and number of separated particles could be determined. Also, a principle component analysis considering the interaction of individual particles could not find a specific combination of measurable characteristics of the particles, which correlate with a distinct increase of the ignition probability.

  5. Ignition studies of two low-octane gasolines

    KAUST Repository

    Javed, Tamour

    2017-07-24

    Low-octane gasolines (RON ∼ 50–70 range) are prospective fuels for gasoline compression ignition (GCI) internal combustion engines. GCI technology utilizing low-octane fuels has the potential to significantly improve well-to-wheel efficiency and reduce the transportation sector\\'s environmental footprint by offsetting diesel fuel usage in compression ignition engines. In this study, ignition delay times of two low-octane FACE (Fuels for Advanced Combustion Engines) gasolines, FACE I and FACE J, were measured in a shock tube and a rapid compression machine over a broad range of engine-relevant conditions (650–1200 K, 20 and 40 bar and ϕ = 0.5 and 1). The two gasolines are of similar octane ratings with anti-knock index, AKI = (RON + MON)/2, of ∼ 70 and sensitivity, S = RON–MON, of ∼ 3. However, the molecular compositions of the two gasolines are notably different. Experimental ignition delay time results showed that the two gasolines exhibited similar reactivity over a wide range of test conditions. Furthermore, ignition delay times of a primary reference fuel (PRF) surrogate (n-heptane/iso-octane blend), having the same AKI as the FACE gasolines, captured the ignition behavior of these gasolines with some minor discrepancies at low temperatures (T < 700 K). Multi-component surrogates, formulated by matching the octane ratings and compositions of the two gasolines, emulated the autoignition behavior of gasolines from high to low temperatures. Homogeneous charge compression ignition (HCCI) engine simulations were used to show that the PRF and multi-component surrogates exhibited similar combustion phasing over a wide range of engine operating conditions.

  6. Simulation of hydrogen and hydrogen-assisted propane ignition in Pt catalyzed microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Seshadri, Vikram; Kaisare, Niket S. [Department of Chemical Engineering, Indian Institute of Technology - Madras, Chennai 600 036 (India)

    2010-11-15

    This paper deals with self-ignition of catalytic microburners from ambient cold-start conditions. First, reaction kinetics for hydrogen combustion is validated with experimental results from the literature, followed by validation of a simplified pseudo-2D microburner model. The model is then used to study the self-ignition behavior of lean hydrogen/air mixtures in a Platinum-catalyzed microburner. Hydrogen combustion on Pt is a very fast reaction. During cold start ignition, hydrogen conversion reaches 100% within the first few seconds and the reactor dynamics are governed by the ''thermal inertia'' of the microburner wall structure. The self-ignition property of hydrogen can be used to provide the energy required for propane ignition. Two different modes of hydrogen-assisted propane ignition are considered: co-feed mode, where the microburner inlet consists of premixed hydrogen/propane/air mixtures; and sequential feed mode, where the inlet feed is switched from hydrogen/air to propane/air mixtures after the microburner reaches propane ignition temperature. We show that hydrogen-assisted ignition is equivalent to selectively preheating the inlet section of the microburner. The time to reach steady state is lower at higher equivalence ratio, lower wall thermal conductivity, and higher inlet velocity for both the ignition modes. The ignition times and propane emissions are compared. Although the sequential feed mode requires slightly higher amount of hydrogen, the propane emissions are at least an order of magnitude lower than the other ignition modes. (author)

  7. The National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Miller, G H; Moses, E I; Wuest, C R

    2004-06-03

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is a stadium-sized facility that, when completed in 2008, will contain a 192-beam, 1.8- Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter-diameter target chamber and room for 100 diagnostics. NIF is the world's largest and most energetic laser experimental system and will provide a scientific center to study inertial confinement fusion and matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} bar; conditions that exist naturally only in the interior of stars and planets. NIF has completed the first phases of its laser commissioning program. The first four beams of NIF have generated 106 kilojoules in 23-ns pulses of infrared light and over 16 kJ in 3.5- ns pulses at the third harmonic (351 nm). NIF's target experimental systems are being commissioned and experiments have begun. This paper provides a detailed look the NIF laser systems, laser and optical performance, and results from recent laser commissioning shots. We follow this with a discussion of NIF's high-energy-density and inertial fusion experimental capabilities, the first experiments on NIF, and plans for future capabilities of this unique facility.

  8. On the Fielding of a High Gain, Shock-Ignited Target on the National Ignitiion Facility in the Near Term

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, L J; Betti, R; Schurtz, G P; Craxton, R S; Dunne, A M; LaFortune, K N; Schmitt, A J; McKenty, P W; Bailey, D S; Lambert, M A; Ribeyre, X; Theobald, W R; Strozzi, D J; Harding, D R; Casner, A; Atzemi, S; Erbert, G V; Andersen, K S; Murakami, M; Comley, A J; Cook, R C; Stephens, R B

    2010-04-12

    Shock ignition, a new concept for igniting thermonuclear fuel, offers the possibility for a near-term ({approx}3-4 years) test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of {approx}60 may be achievable on NIF at laser drive energies around {approx}0.5MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints still apply. In this paper we present initial target performance simulations, delineate the critical issues and describe the immediate-term R&D program that must be performed in order to test the potential of a high gain shock ignition target on NIF in the near term.

  9. Data Analysis, Pre-Ignition Assessment, and Post-Ignition Modeling of the Large-Scale Annular Cookoff Tests

    Energy Technology Data Exchange (ETDEWEB)

    G. Terrones; F.J. Souto; R.F. Shea; M.W.Burkett; E.S. Idar

    2005-09-30

    In order to understand the implications that cookoff of plastic-bonded explosive-9501 could have on safety assessments, we analyzed the available data from the large-scale annular cookoff (LSAC) assembly series of experiments. In addition, we examined recent data regarding hypotheses about pre-ignition that may be relevant to post-ignition behavior. Based on the post-ignition data from Shot 6, which had the most complete set of data, we developed an approximate equation of state (EOS) for the gaseous products of deflagration. Implementation of this EOS into the multimaterial hydrodynamics computer program PAGOSA yielded good agreement with the inner-liner collapse sequence for Shot 6 and with other data, such as velocity interferometer system for any reflector and resistance wires. A metric to establish the degree of symmetry based on the concept of time of arrival to pin locations was used to compare numerical simulations with experimental data. Several simulations were performed to elucidate the mode of ignition in the LSAC and to determine the possible compression levels that the metal assembly could have been subjected to during post-ignition.

  10. ICF Ignition, the Lawson Criterion, and Comparison with MFE Ignition

    Science.gov (United States)

    Betti, R.

    2009-11-01

    The Lawson criterion, which determines the onset of thermonuclear ignition, is usually expressed through the product pτ > 10 atm . s, where p is the plasma pressure in atm and τ is the energy confinement time in seconds. In magnetic fusion devices, both the pressure and confinement time are routinely measured and the performance of each discharge can be assessed by comparing the value of pτ with respect to the ignition value (10 atm . s). In inertial confinement fusion, both p and τ cannot be directly measured and the performance of surrogate and/or subignited ICF implosions cannot be assessed with respect to the ignition condition. This makes it difficult to compare the performance of ICF implosions with that of magnetic fusion energy (MFE) discharges. Here, we define the meaning of ignition in ICF implosions and compare it to MFE ignition. We then show that a multidimensional ignition condition for inertial confinement fusion can be cast in a form that depends on three measurable parameters of the compressed-fuel assembly: the hot-spot ion temperature T, the neutron yield normalized to the 1-D prediction (yield over clean or YOC) and the total areal density ρR, which includes the cold shell's contribution. A family of marginal-ignition curves are derived in the ρR--T plane.footnotetext C. D. Zhou and R. Betti, Phys. Plasmas 15, 102707 (2008). On this plane, hydrodynamic-equivalent curves show how a given implosion would perform with respect to the ignition condition when the laser-driver energy is varied. Such a criterion can be used to measure the ignition marginfootnotetext D. S. Clark, S. W. Haan, and J. D. Salmonson, Phys. Plasmas 15, 056305 (2008). of NIF targets and to predict the performance of OMEGA targets when scaled up to NIF energies. This work has been supported by the US Department of Energy under Cooperative Agreement Nos. DE-FC02-ER54789 and DE-FC52-08NA28302.

  11. Fundamental Interactions in Gasoline Compression Ignition Engines with Fuel Stratification

    Science.gov (United States)

    Wolk, Benjamin Matthew

    ) a 98-species version including nitric oxide formation reactions. Development of reduced mechanisms is necessary because the detailed mechanism is computationally prohibitive in three-dimensional CFD and chemical kinetics simulations. Simulations of Partial Fuel Stratification (PFS), a GCI strategy, have been performed using CONVERGE with the 96-species reduced mechanism developed in this work for a 4-component gasoline surrogate. Comparison is made to experimental data from the Sandia HCCI/GCI engine at a compression ratio 14:1 at intake pressures of 1 bar and 2 bar. Analysis of the heat release and temperature in the different equivalence ratio regions reveals that sequential auto-ignition of the stratified charge occurs in order of increasing equivalence ratio for 1 bar intake pressure and in order of decreasing equivalence ratio for 2 bar intake pressure. Increased low- and intermediate-temperature heat release with increasing equivalence ratio at 2 bar intake pressure compensates for decreased temperatures in higher-equivalence ratio regions due to evaporative cooling from the liquid fuel spray and decreased compression heating from lower values of the ratio of specific heats. The presence of low- and intermediate-temperature heat release at 2 bar intake pressure alters the temperature distribution of the mixture stratification before hot-ignition, promoting the desired sequential auto-ignition. At 1 bar intake pressure, the sequential auto-ignition occurs in the reverse order compared to 2 bar intake pressure and too fast for useful reduction of the maximum pressure rise rate compared to HCCI. Additionally, the premixed portion of the charge auto-ignites before the highest-equivalence ratio regions. Conversely, at 2 bar intake pressure, the premixed portion of the charge auto-ignites last, after the higher-equivalence ratio regions. More importantly, the sequential auto-ignition occurs over a longer time period for 2 bar intake pressure than at 1 bar intake

  12. Multimodal Friction Ignition Tester

    Science.gov (United States)

    Davis, Eddie; Howard, Bill; Herald, Stephen

    2009-01-01

    The multimodal friction ignition tester (MFIT) is a testbed for experiments on the thermal and mechanical effects of friction on material specimens in pressurized, oxygen-rich atmospheres. In simplest terms, a test involves recording sensory data while rubbing two specimens against each other at a controlled normal force, with either a random stroke or a sinusoidal stroke having controlled amplitude and frequency. The term multimodal in the full name of the apparatus refers to a capability for imposing any combination of widely ranging values of the atmospheric pressure, atmospheric oxygen content, stroke length, stroke frequency, and normal force. The MFIT was designed especially for studying the tendency toward heating and combustion of nonmetallic composite materials and the fretting of metals subjected to dynamic (vibrational) friction forces in the presence of liquid oxygen or pressurized gaseous oxygen test conditions approximating conditions expected to be encountered in proposed composite material oxygen tanks aboard aircraft and spacecraft in flight. The MFIT includes a stainless-steel pressure vessel capable of retaining the required test atmosphere. Mounted atop the vessel is a pneumatic cylinder containing a piston for exerting the specified normal force between the two specimens. Through a shaft seal, the piston shaft extends downward into the vessel. One of the specimens is mounted on a block, denoted the pressure block, at the lower end of the piston shaft. This specimen is pressed down against the other specimen, which is mounted in a recess in another block, denoted the slip block, that can be moved horizontally but not vertically. The slip block is driven in reciprocating horizontal motion by an electrodynamic vibration exciter outside the pressure vessel. The armature of the electrodynamic exciter is connected to the slip block via a horizontal shaft that extends into the pressure vessel via a second shaft seal. The reciprocating horizontal

  13. Effect of ignition timing and hydrogen fraction on combustion and emission characteristics of natural gas direct-injection engine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An experimental study on the combustion and emission characteristics of a direct-injection spark-ignited engine fueled with natural gas/hydrogen blends under various ignition timings was conducted.The results show that ignition timing has a significant influence on engine performance,combustion and emissions.The interval between the end of fuel injection and ignition timing is a very important parameter for direct-injection natural gas engines.The turbulent flow in the combustion chamber generated by the fuel jet remains high and relative strong mixture stratification is introduced when decreasing the angle interval between the end of fuel injection and ignition timing giving fast burning rates and high thermal efficiencies.The maximum cylinder gas pressure,maximum mean gas temperature,maximum rate of pressure rise and maximum heat release rate increase with the advancing of ignition timing.However,these parameters do not vary much with hydrogen addition under specific ignition timing indicating that a small hydrogen fraction addition of less than 20% in the present experiment has little influence on combustion parameters under specific ignition timing.The exhaust HC emission decreases while the exhaust CO2 concentration increases with the advancing of ignition timing.In the lean combustion condition,the exhaust CO does not vary much with ignition timing.At the same ignition timing,the exhaust HC decreases with hydrogen addition while the exhaust CO and CO2 do not vary much with hydrogen addition.The exhaust NOx increases with the advancing of' ignition timing and the behavior tends to be more obvious at large ignition advance angle.The brake mean effective pressure and the effective thermal efficiency of natural gas/hydrogen mixture combustion increase compared with those of natural gas combustion when the hydrogen fraction is over 10%.

  14. Options for an ignited tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, J.

    1984-02-01

    It is expected that the next phase of the fusion program will involve a tokamak with the goals of providing an ignited plasma for pulses of hundreds of seconds. A simple model is described in this memorandum which establishes the physics conditions for such a self-sustaining plasma, for given ion and electron thermal diffusivities, in terms of R/a, b/a, I, B/q, epsilon ..beta../sub p/, anti T/sub i/, and anti T/sub e//anti T/sub i/. The model is used to produce plots showing the wide range of tokamaks that may ignite or have a given ignition margin. The constraints that limit this range are discussed.

  15. PITR: Princeton Ignition Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    1978-12-01

    The principal objectives of the PITR - Princeton Ignition Test Reactor - are to demonstrate the attainment of thermonuclear ignition in deuterium-tritium, and to develop optimal start-up techniques for plasma heating and current induction, in order to determine the most favorable means of reducing the size and cost of tokamak power reactors. This report describes the status of the plasma and engineering design features of the PITR. The PITR geometry is chosen to provide the highest MHD-stable values of beta in a D-shaped plasma, as well as ease of access for remote handling and neutral-beam injection.

  16. Büroo Ignite = Ignite office / Priit Põldme, Reet Sepp

    Index Scriptorium Estoniae

    Põldme, Priit, 1971-

    2013-01-01

    Büroo Ignite (Tatari 25, Tallinn) sisekujundusest. Sisearhitektid Priit Põldme ja Reet Sepp (SAB Joonprojekt). Arhitektid Heiki Taras ja Ahti Luhaäär (Arhitektibüroo Pilter ja Taras). Sisearhitekti ja ESLi aastapreemiate žürii esimehe Kaido Kivi arvamus

  17. Büroo Ignite = Ignite office / Priit Põldme, Reet Sepp

    Index Scriptorium Estoniae

    Põldme, Priit, 1971-

    2013-01-01

    Büroo Ignite (Tatari 25, Tallinn) sisekujundusest. Sisearhitektid Priit Põldme ja Reet Sepp (SAB Joonprojekt). Arhitektid Heiki Taras ja Ahti Luhaäär (Arhitektibüroo Pilter ja Taras). Sisearhitekti ja ESLi aastapreemiate žürii esimehe Kaido Kivi arvamus

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

    Science.gov (United States)

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

    2011-03-01

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

  19. Ignition Regime for Fusion in a Degenerate Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Son, S.; Fisch, N.J.

    2005-12-01

    We identify relevant parameter regimes in which aneutronic fuels can undergo fusion ignition in hot-ion degenerate plasma. Because of relativistic effects and partial degeneracy, the self-sustained burning regime is considerably larger than previously calculated. Inverse bremsstrahlung plays a major role in containing the reactor energy. We solve the radiation transfer equation and obtain the contribution to the heat conductivity from inverse bremsstrahlung.

  20. Plasma ignition of LOVA propellants

    NARCIS (Netherlands)

    Driel, C.A. van; Boluijt, A.G.; Schilt, A.

    2010-01-01

    Ignition experiments were performed using a gun simulator which is equipped with a burst disk. This equipment facilitates the application of propellant loading densities which are comparable to those applied in regular ammunitions. For this study the gun simulator was equipped with a plasma jet igni

  1. Plasma ignition of LOVA propellants

    NARCIS (Netherlands)

    Driel, C.A. van; Boluijt, A.G.; Schilt, A.

    2010-01-01

    Ignition experiments were performed using a gun simulator which is equipped with a burst disk. This equipment facilitates the application of propellant loading densities which are comparable to those applied in regular ammunitions. For this study the gun simulator was equipped with a plasma jet

  2. Mechanism of plasma-assisted ignition for H2 and C1-C5 hydrocarbons

    Science.gov (United States)

    Starikovskiy, Andrey; Aleksandrov, Nikolay

    2016-09-01

    Nonequilibrium plasma demonstrates ability to control ultra-lean, ultra-fast, low-temperature flames and appears to be an extremely promising technology for a wide range of applications, including aviation GTEs, piston engines, ramjets, scramjets and detonation initiation for pulsed detonation engines. To use nonequilibrium plasma for ignition and combustion in real energetic systems, one must understand the mechanisms of plasma-assisted ignition and combustion and be able to numerically simulate the discharge and combustion processes under various conditions. A new, validated mechanism for high-temperature hydrocarbon plasma assisted combustion was built and allows to qualitatively describe plasma-assisted combustion close and above the self-ignition threshold. The principal mechanisms of plasma-assisted ignition and combustion have been established and validated for a wide range of plasma and gas parameters. These results provide a basis for improving various energy-conversion combustion systems, from automobile to aircraft engines, using nonequilibrium plasma methods.

  3. Desensitizing nano powders to electrostatic discharge ignition

    Energy Technology Data Exchange (ETDEWEB)

    Steelman, Ryan [Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering; Clark, Billy [Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering; Pantoya, Michelle L. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering; Heaps, Ronald J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Daniels, Michael A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    Electrostatic discharge (ESD) is a main cause for ignition in powder media ranging from grain silos to fireworks. Nanoscale particles are orders of magnitude more ESD ignition sensitive than their micron scale counterparts. This study shows that at least 13 vol. % carbon nanotubes (CNT) added to nano-aluminum and nano-copper oxide particles (nAl + CuO) eliminates ESD ignition sensitivity. The CNT act as a conduit for electric energy and directs electric charge through the powder to desensitize the reactive mixture to ignition. For nanoparticles, the required CNT concentration for desensitizing ESD ignition acts as a diluent to quench energy propagation.

  4. Localized microwave pulsed plasmas for ignition and flame front enhancement

    Science.gov (United States)

    Michael, James Bennett

    Modern combustor technologies require the ability to match operational parameters to rapidly changing demands. Challenges include variable power output requirements, variations in air and fuel streams, the requirement for rapid and well-controlled ignition, and the need for reliability at low fuel mixture fractions. Work on subcritical microwave coupling to flames and to weakly ionized laser-generated plasmas has been undertaken to investigate the potential for pulsed microwaves to allow rapid combustion control, volumetric ignition, and leaner combustion. Two strategies are investigated. First, subcritical microwaves are coupled to femtosecond laser-generated ionization to ignite methane/air mixtures in a quasi-volumetric fashion. Total energy levels are comparable to the total minimum ignition energies for laser and spark discharges, but the combined strategy allows a 90 percent reduction in the required laser energy. In addition, well-defined multi-dimensional ignition patterns are designated with multiple laser passes. Second, microwave pulse coupling to laminar flame fronts is achieved through interaction with chemiionization-produced electrons in the reaction zone. This energy deposition remains well-localized for a single microwave pulse, resulting in rapid temperature rises of greater than 200 K and maintaining flame propagation in extremely lean methane/air mixtures. The lean flammability limit in methane/air mixtures with microwave coupling has been decreased from an equivalence ratio 0.6 to 0.3. Additionally, a diagnostic technique for laser tagging of nitrogen for velocity measurements is presented. The femtosecond laser electronic excitation tagging (FLEET) technique utilizes a 120 fs laser to dissociate nitrogen along a laser line. The relatively long-lived emission from recombining nitrogen atoms is imaged with a delayed and fast-gated camera to measure instantaneous velocities. The emission strength and lifetime in air and pure nitrogen allow

  5. Use of fast neutrons for assessing sarcopenia by measuring body phosphorus: relevance to health and quality of life of the elderly

    Science.gov (United States)

    Kehayias, Joseph J.; Zhuang, Hong; Doherty, Patricia L.

    1997-02-01

    Sarcopenia, defined as the loss of skeletal muscle with age, may lead to frailty, fractures due to falls, and reduced immunity to disease. By understanding the causes of muscle loss with age we will be able to develop ways of maintaining functional capacity and quality of life for the elderly. Elemental Partition Analysis (EPA) is a new approach to body composition assessment. A major element of the body is measured and then, by means of other measurements, is partitioned to the contributing body compartments. We developed a model for measuring total body muscle by applying the EPA method to total body phosphorus (TBP). We measure TBP by in vivo fast neutron activation analysis using the reaction 31P(n,(alpha) )28Al. The main contributors to TBP are bone and skeletal muscle. Adipose tissue and the liver contribute less than 3 percent. We use dual-energy x-ray absorptiometry (DXA) to evaluate the contribution of bone to TBP. COrrections are applied for the small contributions of the liver and adipose tissue to TBP to derive muscle phosphorus. The technique requires high precision measurements for both TBP and DXA. The total body radiation exposure for measuring human subjects is 0.30 mSv.

  6. FAST Real Time PCR for control of intra-species recycling in aquaculture feed, focused to the most relevant fish species farmed in Europe.

    Science.gov (United States)

    Espiñeira, Montserrat; Vieites, Juan M

    2016-08-01

    Recent regulations in animal feed composition prohibit intra-species recycling, the recycling of one given animal species to the same species, in order to avoid potential safety risks to human and animal health. These regulations have generated the need of their control in aquaculture by effective and specific analytical techniques. To date, most studies of species identification and detection in feedstuffs are focused on land species, but few studies are focused on species composition in fish feed. The present work describes five methodologies based in Real Time PCR for detection of the most relevant fish species farmed in Europe: gilthead sea bream (Sparus aurata); sea bass (Dicentrarchus labrax); turbot (Scophthalmus maximus); rainbow trout (Onchorynchus mykiss); and salmon (Salmo salar), in order to guarantee the intra-species recycling regulation in aquaculture feedstuffs.

  7. Facile Thermal and Optical Ignition of Silicon Nanoparticles and Micron Particles.

    Science.gov (United States)

    Huang, Sidi; Parimi, Venkata Sharat; Deng, Sili; Lingamneni, Srilakshmi; Zheng, Xiaolin

    2017-10-11

    Silicon (Si) particles are widely utilized as high-capacity electrodes for Li-ion batteries, elements for thermoelectric devices, agents for bioimaging and therapy, and many other applications. However, Si particles can ignite and burn in air at elevated temperatures or under intense illumination. This poses potential safety hazards when handling, storing, and utilizing these particles for those applications. In order to avoid the problem of accidental ignition, it is critical to quantify the ignition properties of Si particles such as their sizes and porosities. To do so, we first used differential scanning calorimetry to experimentally determine the reaction onset temperature of Si particles under slow heating rates (∼0.33 K/s). We found that the reaction onset temperature of Si particles increased with the particle diameter from 805 °C at 20-30 nm to 935 °C at 1-5 μm. Then, we used a xenon (Xe) flash lamp to ignite Si particles under fast heating rates (∼10(3) to 10(6) K/s) and measured the minimum ignition radiant fluence (i.e., the radiant energy per unit surface area of Si particle beds required for ignition). We found that the measured minimum ignition radiant fluence decreased with decreasing Si particle size and was most sensitive to the porosity of the Si particle bed. These trends for the Xe flash ignition experiments were also confirmed by our one-dimensional unsteady simulation to model the heat transfer process. The quantitative information on Si particle ignition included in this Letter will guide the safe handling, storage, and utilization of Si particles for diverse applications and prevent unwanted fire hazards.

  8. The effect of kerosene injection on ignition probability of local ignition in a scramjet combustor

    Science.gov (United States)

    Bao, Heng; Zhou, Jin; Pan, Yu

    2017-03-01

    The spark ignition of kerosene is investigated in a scramjet combustor with a flight condition of Ma 4, 17 km. Based plentiful of experimental data, the ignition probabilities of the local ignition have been acquired for different injection setups. The ignition probability distributions show that the injection pressure and injection location have a distinct effect on spark ignition. The injection pressure has both upper and lower limit for local ignition. Generally, the larger mass flow rate will reduce the ignition probability. The ignition position also affects the ignition near the lower pressure limit. The reason is supposed to be the cavity swallow effect on upstream jet spray near the leading edge, which will make the cavity fuel rich. The corner recirculation zone near the front wall of the cavity plays a significant role in the stabilization of local flame.

  9. Tritium and ignition target management at the National Ignition Facility.

    Science.gov (United States)

    Draggoo, Vaughn

    2013-06-01

    Isotopic mixtures of hydrogen constitute the basic fuel for fusion targets of the National Ignition Facility (NIF). A typical NIF fusion target shot requires approximately 0.5 mmoles of hydrogen gas and as much as 750 GBq (20 Ci) of 3H. Isotopic mix ratios are specified according to the experimental shot/test plan and the associated test objectives. The hydrogen isotopic concentrations, absolute amounts, gas purity, configuration of the target, and the physical configuration of the NIF facility are all parameters and conditions that must be managed to ensure the quality and safety of operations. An essential and key step in the preparation of an ignition target is the formation of a ~60 μm thick hydrogen "ice" layer on the inner surface of the target capsule. The Cryogenic Target Positioning System (Cryo-Tarpos) provides gas handling, cyro-cooling, x-ray imaging systems, and related instrumentation to control the volumes and temperatures of the multiphase (solid, liquid, and gas) hydrogen as the gas is condensed to liquid, admitted to the capsule, and frozen as a single spherical crystal of hydrogen in the capsule. The hydrogen fuel gas is prepared in discrete 1.7 cc aliquots in the LLNL Tritium Facility for each ignition shot. Post-shot hydrogen gas is recovered in the NIF Tritium Processing System (TPS). Gas handling systems, instrumentation and analytic equipment, material accounting information systems, and the shot planning systems must work together to ensure that operational and safety requirements are met.

  10. Homogeneous charge compression ignition (HCCI) - A comparison with spark ignition (SI) operation

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Magnus

    1997-08-01

    Homogeneous Charge Compression Ignition (HCCI) is the third alternative for combustion in engines. Here a homogeneous premixed charge is used as in a spark ignited engine but the charge is compressed to auto-ignition as in a diesel. The characteristics of HCCI was compared to spark ignition (SI) using a 1.6 liter single cylinder engine. Three different fuels were used; isooctane, ethanol and natural gas. HCCI could be used with all three fuels in a single cylinder engine with a fixed compression ratio. Some remarkable results were noted in the experiments. The indicated efficiency of HCCI was much better than for SI operation. The gross indicated efficiency showed values at 50% for the richer cases. This means that the fuel consumption at part load would be reduced to the half compared to SI operation. Very little NO{sub x} was generated with HCCI, only a few ppm. With isooctane, it ranged from 4 to below 1 ppm and with ethanol even lower values. However, HCCI generated more HC and CO. Operation was noisier with HCCI than with SI. Stable and efficient operation with HCCI could be obtained with {lambda} = 3.5 to 9 using isooctane, 3.5 to 6.5 using ethanol, and 2.5 to 3.5 using natural gas. Cycle to cycle variation of combustion was very low. Isooctane could be operated unthrottled without preheating. The selection of the high compression ratio, 21:1, was dependent on the high octane number for natural gas. The attainable IMEP was 5 bar. The limit to make higher IMEP was the rate of combustion. At IMEP 5 bar the main combustion, 10-90% burn duration, took place in less than 2 crank angle degrees (CAD). This is extremely fast and gives very high rate of pressure rise, which leads to noisy operation and high loads on the engine. The lean limit was given by unstable combustion with cycle to cycle variation of combustion, and with high emissions of unburned hydrocarbons and carbon monoxide Examination paper. 15 refs, 38 figs, 1 tab

  11. Fast ignitor target studies for HiPER

    Energy Technology Data Exchange (ETDEWEB)

    Atzeni, S; Bellei, C; Schiavi, A [Dipartimento di Energetica, Universita di Roma ' La Sapienza' and CNISM (Italy); Davies, J R; Silva, L; Sorasio, G [Instituto Superior Tecnico, Lisbon (Portugal); Evans, R G [The Blackett Laboratory, Imperial College, Prince Consort Road, London (United Kingdom); Honrubia, J J [GIFI, Universidad Politecnica, Madrid (Spain); Nicolai, P; Ribeyre, X; Schurtz, G; Olazabal, M [CELIA, Universite Bordeaux 1, Talence (France); Badziak, J [IPPLM, Euratom Association, Warsaw (Poland); Meyer-ter-Vehn, J [Max-Planck-Institut fuer Quantenoptik, Garching (Germany)], E-mail: javier.honrubia@upm.es

    2008-05-15

    The HiPER facility has been proposed recently to demonstrate fast ignition of laser driven inertial fusion targets. According to the present design, HiPER will have a 3{omega}, multi-beam, multi-ns-pulse of about 250 kJ and a 2{omega} or 3{omega} ignition beam delivering 70 kJ in about 15 ps. We present here studies on laser-driven fast-ignitor targets driven by 100-300 kJ compression pulses, followed by 70-100 kJ ignition pulses.

  12. Self-ignition of diesel spray combustion

    Science.gov (United States)

    Dhuchakallaya, Isares; Watkins, A. P.

    2009-10-01

    This work presents the development and implementation of auto-ignition modelling for DI diesel engines by using the probability density function-eddy break-up (PDF-EBU) model. The key concept of this approach is to combine the chemical reaction rate dealing with low-temperature mode, and the turbulence reaction rate governing the high-temperature part by a reaction progress variable coupling function which represents the level of reaction. The average reaction rate here is evaluated by a PDF averaging approach. In order to assess the potential of this developed model, the well-known Shell ignition model is chosen to compare in auto-ignition analysis. In comparison, the PDF-EBU ignition model yields the ignition delay time in good agreement with the Shell ignition model prediction. However, the ignition kernel location predicted by the Shell model is slightly nearer injector than that by the PDF-EBU model leading to shorter lift-off length. As a result, the PDF-EBU ignition model developed here are fairly satisfactory in predicting the auto-ignition of diesel engines with the Shell ignition model.

  13. Determining Fire Dates and Locating Ignition Points With Satellite Data

    Directory of Open Access Journals (Sweden)

    Akli Benali

    2016-04-01

    Full Text Available Each wildfire has its own “history”, burns under specific conditions and leads to unique environmental impacts. Information on where and when it has started and its duration is important to improve understanding on the dynamics of individual wildfires. This information is typically included in fire databases that are known to have: (i multiple error sources; (ii limited spatial coverage and/or time span, and; (iii often unknown accuracy and uncertainty. Satellite data have a large potential to reduce such limitations. We used active fire data from the MODerate Resolution Imaging Spectroradiometer (MODIS to estimate fire start/end dates and ignition location(s for large wildfires that occurred in Alaska, Portugal, Greece, California and southeastern Australia. We assessed the agreement between satellite-derived estimates and data from fire databases, and determined the associated uncertainty. Fire dates and ignition location(s were estimated for circa 76% of the total burnt area extent for the five study regions. The ability to estimate fire dates and ignitions from satellite data increased with fire size. The agreement between reported and estimated fire dates was very good for start dates (Model efficiency index, MEF = 0.91 and reasonable for end dates (MEF = 0.73. The spatio-temporal agreement between reported and satellite-derived wildfire ignitions showed temporal lags and distances within 12 h and 2 km, respectively. Uncertainties associated with ignition estimates were generally larger than the disagreements with data reported in fire databases. Our results show how satellite data can contribute to improve information regarding dates and ignitions of large wildfires. This contribution can be particularly relevant in regions with scarce fire information, while in well-documented areas it can be used to complement, potentially detect, and correct inconsistencies in existing fire databases. Using data from other existing and/or upcoming

  14. Laser-assisted homogeneous charge ignition in a constant volume combustion chamber

    Science.gov (United States)

    Srivastava, Dhananjay Kumar; Weinrotter, Martin; Kofler, Henrich; Agarwal, Avinash Kumar; Wintner, Ernst

    2009-06-01

    Homogeneous charge compression ignition (HCCI) is a very promising future combustion concept for internal combustion engines. There are several technical difficulties associated with this concept, and precisely controlling the start of auto-ignition is the most prominent of them. In this paper, a novel concept to control the start of auto-ignition is presented. The concept is based on the fact that most HCCI engines are operated with high exhaust gas recirculation (EGR) rates in order to slow-down the fast combustion processes. Recirculated exhaust gas contains combustion products including moisture, which has a relative peak of the absorption coefficient around 3 μm. These water molecules absorb the incident erbium laser radiations ( λ=2.79 μm) and get heated up to expedite ignition. In the present experimental work, auto-ignition conditions are locally attained in an experimental constant volume combustion chamber under simulated EGR conditions. Taking advantage of this feature, the time when the mixture is thought to "auto-ignite" could be adjusted/controlled by the laser pulse width optimisation, followed by its resonant absorption by water molecules present in recirculated exhaust gas.

  15. Polar-direct-drive experiments at the National Ignition Facility

    Science.gov (United States)

    Radha, P. B.; Hohenberger, M.; Marshall, F. J.; Michel, D. T.; Bates, J.; Boehly, T. R.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Dixit, S. N.; Edgell, D. H.; Frenje, J. A.; Froula, D. H.; Goncharov, V. N.; Hu, S. X.; Karasik, M.; Knauer, J. P.; LePape, S.; Marozas, J. A.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Myatt, J. F.; Obenschein, S.; Petrasso, R. D.; Regan, S. P.; Rosenberg, M. J.; Sangster, T. C.; Seka, W.; Shvydky, A.; Sio, H.; Skupsky, S.; Zylstra, A.

    2016-05-01

    Polar-direct-drive experiments at the National Ignition Facility (NIF) are being used to validate direct-drive-implosion models. Energy coupling and fast-electron preheat are the primary issues being studied in planar and imploding geometries on the NIF. Results from backlit images from implosions indicate that the overall drive is well modeled although some differences remain in the thickness of the imploding shell. Implosion experiments to mitigate cross-beam energy transfer and preheat from two-plasmon decay are planned for the next year.

  16. Indirect drive ignition at the National Ignition Facility

    Science.gov (United States)

    Meezan, N. B.; Edwards, M. J.; Hurricane, O. A.; Patel, P. K.; Callahan, D. A.; Hsing, W. W.; Town, R. P. J.; Albert, F.; Amendt, P. A.; Berzak Hopkins, L. F.; Bradley, D. K.; Casey, D. T.; Clark, D. S.; Dewald, E. L.; Dittrich, T. R.; Divol, L.; Döppner, T.; Field, J. E.; Haan, S. W.; Hall, G. N.; Hammel, B. A.; Hinkel, D. E.; Ho, D. D.; Hohenberger, M.; Izumi, N.; Jones, O. S.; Khan, S. F.; Kline, J. L.; Kritcher, A. L.; Landen, O. L.; LePape, S.; Ma, T.; MacKinnon, A. J.; MacPhee, A. G.; Masse, L.; Milovich, J. L.; Nikroo, A.; Pak, A.; Park, H.-S.; Peterson, J. L.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Smalyuk, V. A.; Spears, B. K.; Stadermann, M.; Suter, L. J.; Thomas, C. A.; Tommasini, R.; Turnbull, D. P.; Weber, C. R.

    2017-01-01

    This paper reviews scientific results from the pursuit of indirect drive ignition on the National Ignition Facility (NIF) and describes the program’s forward looking research directions. In indirect drive on the NIF, laser beams heat an x-ray enclosure called a hohlraum that surrounds a spherical pellet. X-ray radiation ablates the surface of the pellet, imploding a thin shell of deuterium/tritium (DT) that must accelerate to high velocity (v  >  350 km s-1) and compress by a factor of several thousand. Since 2009, substantial progress has been made in understanding the major challenges to ignition: Rayleigh Taylor (RT) instability seeded by target imperfections; and low-mode asymmetries in the hohlraum x-ray drive, exacerbated by laser-plasma instabilities (LPI). Requirements on velocity, symmetry, and compression have been demonstrated separately on the NIF but have not been achieved simultaneously. We now know that the RT instability, seeded mainly by the capsule support tent, severely degraded DT implosions from 2009-2012. Experiments using a ‘high-foot’ drive with demonstrated lower RT growth improved the thermonuclear yield by a factor of 10, resulting in yield amplification due to alpha particle heating by more than a factor of 2. However, large time dependent drive asymmetry in the LPI-dominated hohlraums remains unchanged, preventing further improvements. High fidelity 3D hydrodynamic calculations explain these results. Future research efforts focus on improved capsule mounting techniques and on hohlraums with little LPI and controllable symmetry. In parallel, we are pursuing improvements to the basic physics models used in the design codes through focused physics experiments.

  17. Lateral Ignition and Flame Spread Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — Description: This apparatus, developed at EL, determines material properties related to piloted ignition of a vertically oriented sample under constant and uniform...

  18. Understanding Biomass Ignition in Power Plant Mills

    DEFF Research Database (Denmark)

    Schwarzer, Lars; Jensen, Peter Arendt; Glarborg, Peter

    2017-01-01

    Converting existing coal fired power plants to biomass is a readily implemented strategy to increase the share of renewable energy. However, changing from one fuel to another is not straightforward: Experience shows that wood pellets ignite more readily than coal in power plant mills or storages....... This is not very well explained by apply-ing conventional thermal ignition theory. An experimental study at lab scale, using pinewood as an example fuel, was conducted to examine self-heating and self-ignition. Supplemental experiments were performed with bituminous coal. Instead of characterizing ignition...

  19. Flame ignition studies of conventional and alternative jet fuels and surrogate components

    Science.gov (United States)

    Liu, Ning

    Practical jet fuels are widely used in air-breathing propulsion, but the chemical mechanisms that control their combustion are not yet understood. Thousands of components are contained in conventional and alternative jet fuels, making thus any effort to model their combustion behavior a daunting task. That has been the motivation behind the development of surrogate fuels that contain typically a small number of neat components, whose physical properties and combustion behavior mimic those of the real jet fuel, and whose kinetics could be modeled with increased degree of confidence. Towards that end, a large number of experimental data are required both for the real fuels and the attendant surrogate components that could be used to develop and validate detailed kinetic models. Those kinetic models could be used then upon reduction to model a combustor and eventually optimize its performance. Among all flame phenomena, ignition is rather sensitive to the oxidative and pyrolytic propensity of the fuel as well as to its diffusivity. The counterflow configuration is ideal in probing both the fuel reactivity and diffusivity aspects of the ignition process and it was used in the present work to determine the ignition temperatures of premixed and non-premixed flames of a variety of fuels relevant to air-breathing propulsion. The experiments were performed at atmospheric pressure, elevated unburned fuel mixture temperatures, and various strain rates that were measured locally. Several recent kinetic models were used in direct numerical simulations of the experiments and the computed results were tested against the experimental data. Furthermore, through sensitivity, reaction path, and structure analyses of the computed flames, insight was provided into the dominant mechanisms that control ignition. It was found that ignition is primarily sensitive to fuel diffusion and secondarily sensitive to chemical kinetics and intermediate species diffusivities under the low fuel

  20. Large optics for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Baisden, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-01-12

    The National Ignition Facility (NIF) laser with its 192 independent laser beams is not only the world’s largest laser, it is also the largest optical system ever built. With its 192 independent laser beams, the NIF requires a total of 7648 large-aperture (meter-sized) optics. One of the many challenges in designing and building NIF has been to carry out the research and development on optical materials, optics design, and optics manufacturing and metrology technologies needed to achieve NIF’s high output energies and precision beam quality. This paper describes the multiyear, multi-supplier, development effort that was undertaken to develop the advanced optical materials, coatings, fabrication technologies, and associated process improvements necessary to manufacture the wide range of NIF optics. The optics include neodymium-doped phosphate glass laser amplifiers; fused silica lenses, windows, and phase plates; mirrors and polarizers with multi-layer, high-reflectivity dielectric coatings deposited on BK7 substrates; and potassium di-hydrogen phosphate crystal optics for fast optical switches, frequency conversion, and polarization rotation. Also included is a discussion of optical specifications and custom metrology and quality-assurance tools designed, built, and fielded at supplier sites to verify compliance with the stringent NIF specifications. In addition, a brief description of the ongoing program to improve the operational lifetime (i.e., damage resistance) of optics exposed to high fluence in the 351-nm (3ω) is provided.

  1. Vlasov-Fokker-Planck simulations of fast-electron transport with hydrodynamic plasma response

    Energy Technology Data Exchange (ETDEWEB)

    Kingham, R J; Sherlock, M; Ridgers, C P; Evans, R G, E-mail: rj.kingham@imperial.ac.u [Plasma Physics Group, Imperial College London, London SW7 2AZ (United Kingdom)

    2010-08-01

    We report on kinetic simulations of the transport of laser-produced relativistic electron beams (REB) through solid-density plasma, including the hydrodynamic response of the plasma. We consider REBs with parameters relevant to fast-ignition of compressed inertial confinement fusion capsules. We show that over the 10-20ps timescales required for fast-ignition, thermal pressure (from Ohmic heating) can significantly modify the density which in turn strongly affects the propagation of injected fast-electrons; it allows them to re-collimate into a narrow, intense beam under conditions where they initially undergo beam-hollowing. Similar static-density calculations do not show re-collimation. The re-collimation effect is attributed to PdV cooling in the pressure-induced density-channel, which in turn suppresses defocusing magnetic fields generated by resistivity gradients. These simulations have been carried out using the new 2D-3V Vlasov-Fokker-Planck (VFP) code FIDO running in hybrid mode.

  2. Ignition of alkane-rich FACE gasoline fuels and their surrogate mixtures

    KAUST Repository

    Sarathy, Mani

    2015-01-01

    Petroleum derived gasoline is the most used transportation fuel for light-duty vehicles. In order to better understand gasoline combustion, this study investigated the ignition propensity of two alkane-rich FACE (Fuels for Advanced Combustion Engines) gasoline test fuels and their corresponding PRF (primary reference fuel) blend in fundamental combustion experiments. Shock tube ignition delay times were measured in two separate facilities at pressures of 10, 20, and 40 bar, temperatures from 715 to 1500 K, and two equivalence ratios. Rapid compression machine ignition delay times were measured for fuel/air mixtures at pressures of 20 and 40 bar, temperatures from 632 to 745 K, and two equivalence ratios. Detailed hydrocarbon analysis was also performed on the FACE gasoline fuels, and the results were used to formulate multi-component gasoline surrogate mixtures. Detailed chemical kinetic modeling results are presented herein to provide insights into the relevance of utilizing PRF and multi-component surrogate mixtures to reproduce the ignition behavior of the alkane-rich FACE gasoline fuels. The two FACE gasoline fuels and their corresponding PRF mixture displayed similar ignition behavior at intermediate and high temperatures, but differences were observed at low temperatures. These trends were mimicked by corresponding surrogate mixture models, except for the amount of heat release in the first stage of a two-stage ignition events, when observed. © 2014 The Combustion Institute.

  3. Ignition delay time correlation of fuel blends based on Livengood-Wu description

    KAUST Repository

    Khaled, Fathi

    2017-08-17

    In this work, a universal methodology for ignition delay time (IDT) correlation of multicomponent fuel mixtures is reported. The method is applicable over wide ranges of temperatures, pressures, and equivalence ratios. n-Heptane, iso-octane, toluene, ethanol and their blends are investigated in this study because of their relevance to gasoline surrogate formulation. The proposed methodology combines benefits from the Livengood-Wu integral, the cool flame characteristics and the Arrhenius behavior of the high-temperature ignition delay time to suggest a simple and comprehensive formulation for correlating the ignition delay times of pure components and blends. The IDTs of fuel blends usually have complex dependences on temperature, pressure, equivalence ratio and composition of the blend. The Livengood-Wu integral is applied here to relate the NTC region and the cool flame phenomenon. The integral is further extended to obtain a relation between the IDTs of fuel blends and pure components. Ignition delay times calculated using the proposed methodology are in excellent agreement with those simulated using a detailed chemical kinetic model for n-heptane, iso-octane, toluene, ethanol and blends of these components. Finally, very good agreement is also observed for combustion phasing in homogeneous charge compression ignition (HCCI) predictions between simulations performed with detailed chemistry and calculations using the developed ignition delay correlation.

  4. Advanced ignition and propulsion technology program

    Energy Technology Data Exchange (ETDEWEB)

    Oldenborg, R.; Early, J.; Lester, C.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Reliable engine re-ignition plays a crucial role in enabling commercial and military aircraft to fly safely at high altitudes. This project addressed research elements critical to the optimization of laser-based igniter. The effort initially involved a collaborative research and development agreement with B.F. Goodrich Aerospace and Laser Fare, Inc. The work involved integrated experiments with theoretical modeling to provide a basic understanding of the chemistry and physics controlling the laser-induced ignition of fuel aerosols produced by turbojet engine injectors. In addition, the authors defined advanced laser igniter configurations that minimize laser packaging size, weight, complexity and power consumption. These innovative ignition concepts were shown to reliably ignite jet fuel aerosols over a broad range of fuel/air mixture and a t fuel temperatures as low as -40 deg F. The demonstrated fuel ignition performance was highly superior to that obtained by the state-of-the-art, laser-spark ignition method utilizing comparable laser energy. The authors also developed a laser-based method that effectively removes optically opaque deposits of fuel hydrocarbon combustion residues from laser window surfaces. Seven patents have been either issued or are pending that resulted from the technology developments within this project.

  5. Modelling piloted ignition of wood and plastics

    NARCIS (Netherlands)

    Blijderveen, M. van; Bramer, E.A.; Brem, G.

    2012-01-01

    To gain insight in the startup of an incinerator, this article deals with piloted ignition. A newly developed model is described to predict the piloted ignition times of wood, PMMA and PVC. The model is based on the lower flammability limit and the adiabatic flame temperature at this limit. The inco

  6. Laser-plasma interaction physics for shock ignition

    Directory of Open Access Journals (Sweden)

    Goyon C.

    2013-11-01

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

  7. Carbon Deflagration in Type Ia Supernova: I. Centrally Ignited Models

    CERN Document Server

    Ma, H; Malone, C M; Almgren, A; Bell, J B

    2013-01-01

    A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway close to its center and explodes. In a series of papers, we shall explore the consequences of ignition at several locations within such dwarfs. Here we assume central ignition, which has been explored before, however, the problem is worth revisiting, if only to validate those previous studies and to further elucidate the relevant physics for future work. A perturbed sphere of hot iron ash with a radius of ~100 km is initialized at the middle of the star. The subsequent explosion is followed in several simulations using a thickened flame model in which the flame speed is either fixed --- within the range expected from turbulent combustion --- or based on the local turbulent intensity. Global results, including the explosion energy and bulk nucleosynthesis (e.g. 56Ni of 0.48--0.56 $\\Msun$) turn out to be insensitive to this speed. In all completed runs, the energy...

  8. Plasma-assisted ignition and deflagration-to-detonation transition.

    Science.gov (United States)

    Starikovskiy, Andrey; Aleksandrov, Nickolay; Rakitin, Aleksandr

    2012-02-13

    Non-equilibrium plasma demonstrates great potential to control ultra-lean, ultra-fast, low-temperature flames and to become an extremely promising technology for a wide range of applications, including aviation gas turbine engines, piston engines, RAMjets, SCRAMjets and detonation initiation for pulsed detonation engines. The analysis of discharge processes shows that the discharge energy can be deposited into the desired internal degrees of freedom of molecules when varying the reduced electric field, E/n, at which the discharge is maintained. The amount of deposited energy is controlled by other discharge and gas parameters, including electric pulse duration, discharge current, gas number density, gas temperature, etc. As a rule, the dominant mechanism of the effect of non-equilibrium plasma on ignition and combustion is associated with the generation of active particles in the discharge plasma. For plasma-assisted ignition and combustion in mixtures containing air, the most promising active species are O atoms and, to a smaller extent, some other neutral atoms and radicals. These active particles are efficiently produced in high-voltage, nanosecond, pulse discharges owing to electron-impact dissociation of molecules and electron-impact excitation of N(2) electronic states, followed by collisional quenching of these states to dissociate the molecules. Mechanisms of deflagration-to-detonation transition (DDT) initiation by non-equilibrium plasma were analysed. For longitudinal discharges with a high power density in a plasma channel, two fast DDT mechanisms have been observed. When initiated by a spark or a transient discharge, the mixture ignited simultaneously over the volume of the discharge channel, producing a shock wave with a Mach number greater than 2 and a flame. A gradient mechanism of DDT similar to that proposed by Zeldovich has been observed experimentally under streamer initiation.

  9. Theoretical study on ignition compensating temperature sensitivity

    Directory of Open Access Journals (Sweden)

    Mingfang Liu

    2015-09-01

    Full Text Available Temperature sensitivity of the propellant has significant influence on the interior ballistic performance of guns. Many physical and chemical approaches are employed to decrease this temperature sensitivity of the propellant. In this article, it is proposed that the temperature sensitivity of the propellant is changed by altering the factors required to ignition. A one-dimensional two-phase flow interior ballistic model is established to analyze the relation between ignition factors and temperature sensitivity. The simulation results show that the propellant temperature sensitivity is changed by altering the ignition factors. That is, the interior ballistic performance is affected by altering the size of fire hole, breaking liner pressure, and ignition location. Based on the simulation results, the temperature sensitivity can be controlled by matching of charges and intelligent control ignition system.

  10. The Effect of Composition on Nova Ignitions

    CERN Document Server

    Shen, Ken J

    2008-01-01

    The accretion of hydrogen-rich matter onto C/O and O/Ne white dwarfs in binary systems leads to unstable thermonuclear ignition of the accreted envelope, triggering a convective thermonuclear runaway and a subsequent classical, recurrent, or symbiotic nova. Prompted by uncertainties in the composition at the base of the accreted envelope at the onset of convection, as well as the range of abundances detected in nova ejecta, we examine the effects of varying the composition of the accreted material. For high accretion rates and carbon mass fractions 0.002. These different triggering mechanisms, which occur for critical abundances relevant to many nova systems, alter the amount of mass that is accreted prior to a nova, causing the nova rate to depend on accreted composition. Upcoming deep optical surveys such as Pan-STARRS-1, Pan-STARRS-4, and the Large Synoptic Survey Telescope may allow us to detect the dependence of nova rates on accreted composition. Furthermore, the burning and depletion of 3He with a mas...

  11. In depth fusion flame spreading with a deuterium-tritium plane fuel density profile for plasma block ignition

    Institute of Scientific and Technical Information of China (English)

    B.Malekynia; S.S.Razavipour

    2012-01-01

    Solid-state fuel ignition was given by Chu and Bobin according to the hydrodynamic theory at x =0 qualitatively.A high threshold energy flux density,i.e.,E* =4.3 x 1012 J/m2,has been reached.Recently,fast ignition by employing clean petawatt-picosecond laser pulses was performed.The anomalous phenomena were observed to be based on suppression of prepulses.The accelerated plasma block was used to ignite deuterium-tritium fuel at solid-state density.The detailed analysis of the thermonuclear wave propagation was investigated.Also the fusion conditions at x ≠ 0 layers were clarified by exactly solving hydrodynamic equations for plasma block ignition.In this paper,the applied physical mechanisms are determined for nonlinear force laser driven plasma blocks,thermonuclear reaction,heat transfer,electron-ion equilibration,stopping power of alpha particles,bremsstrahlung,expansion,density dependence,and fluid dynamics.New ignition conditions may be obtained by using temperature equations,including thc dcnsity profile that is obtained by the continuity equation and expansion velocity.The density is only a function of x and independent of time.The ignition energy flux density,E*t,for the x ≠ 0 layers is 1.95 × 1012 J/m2.Thus threshold ignition energy in comparison with that at x =0 layers would be reduced to less than 50 percent.

  12. Laser-plasma interactions relevant to Inertial Confinement Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, K.B.

    1998-11-02

    Research into laser-driven inertial confinement fusion is now entering a critical juncture with the construction of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Many of the remaining unanswered questions concerning NIF involve interactions between lasers and plasmas. With the eventual goal of fusion power in mind, laser-plasma interactions relevant to laser fusion schemes is an important topic in need of further research. This work experimentally addresses some potential shortcuts and pitfalls on the road to laser-driven fusion power. Current plans on NIF have 192 laser beams directed into a small cylindrical cavity which will contain the fusion fuel; to accomplish this the beams must cross in the entrance holes, and this intersection will be in the presence of outward-flowing plasma. To investigate the physics involved, interactions of crossing laser beams in flowing plasmas are investigated with experiments on the Nova laser facility at LLNL. It was found that in a flowing plasma, energy is transferred between two crossing laser beams, and this may have deleterious consequences for energy balance and ignition in NIF. Possible solutions to this problem are presented. A recently-proposed alternative to standard laser-driven fusion, the ''fast ignitor'' concept, is also experimentally addressed in this dissertation. Many of the laser-plasma interactions necessary for the success of the fast ignitor have not previously been explored at the relevant laser intensities. Specifically, the transfer of high-intensity laser energy to electrons at solid-target interfaces is addressed. 20-30% conversion efficiencies into forward-propagated electrons were measured, along with an average electron energy that varied with the type of target material. The directionality of the electrons was also measured, revealing an apparent beaming of the highest energy electrons. This work was extended to various intensities and

  13. Development and validation of a fast and simple multi-analyte procedure for quantification of 40 drugs relevant to emergency toxicology using GC-MS and one-point calibration.

    Science.gov (United States)

    Meyer, Golo M J; Weber, Armin A; Maurer, Hans H

    2014-05-01

    Diagnosis and prognosis of poisonings should be confirmed by comprehensive screening and reliable quantification of xenobiotics, for example by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). The turnaround time should be short enough to have an impact on clinical decisions. In emergency toxicology, quantification using full-scan acquisition is preferable because this allows screening and quantification of expected and unexpected drugs in one run. Therefore, a multi-analyte full-scan GC-MS approach was developed and validated with liquid-liquid extraction and one-point calibration for quantification of 40 drugs relevant to emergency toxicology. Validation showed that 36 drugs could be determined quickly, accurately, and reliably in the range of upper therapeutic to toxic concentrations. Daily one-point calibration with calibrators stored for up to four weeks reduced workload and turn-around time to less than 1 h. In summary, the multi-analyte approach with simple liquid-liquid extraction, GC-MS identification, and quantification over fast one-point calibration could successfully be applied to proficiency tests and real case samples.

  14. National Ignition Facility site requirements

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The Site Requirements (SR) provide bases for identification of candidate host sites for the National Ignition Facility (NIF) and for the generation of data regarding potential actual locations for the facilities. The SR supplements the NIF Functional Requirements (FR) with information needed for preparation of responses to queries for input to HQ DOE site evaluation. The queries are to include both documents and explicit requirements for the potential host site responses. The Sr includes information extracted from the NIF FR (for convenience), data based on design approaches, and needs for physical and organization infrastructure for a fully operational NIF. The FR and SR describe requirements that may require new construction or may be met by use or modification of existing facilities. The SR do not establish requirements for NIF design or construction project planning. The SR document does not constitute an element of the NIF technical baseline.

  15. Modelling piloted ignition of wood and plastics.

    Science.gov (United States)

    van Blijderveen, Maarten; Bramer, Eddy A; Brem, Gerrit

    2012-09-01

    To gain insight in the startup of an incinerator, this article deals with piloted ignition. A newly developed model is described to predict the piloted ignition times of wood, PMMA and PVC. The model is based on the lower flammability limit and the adiabatic flame temperature at this limit. The incoming radiative heat flux, sample thickness and moisture content are some of the used variables. Not only the ignition time can be calculated with the model, but also the mass flux and surface temperature at ignition. The ignition times for softwoods and PMMA are mainly under-predicted. For hardwoods and PVC the predicted ignition times agree well with experimental results. Due to a significant scatter in the experimental data the mass flux and surface temperature calculated with the model are hard to validate. The model is applied on the startup of a municipal waste incineration plant. For this process a maximum allowable primary air flow is derived. When the primary air flow is above this maximum air flow, no ignition can be obtained.

  16. The National Ignition Facility project

    Energy Technology Data Exchange (ETDEWEB)

    Paisner, J.A.; Boyes, J.D.; Kumpan, S.A.; Sorem, M.

    1996-06-01

    The Secretary of the U.S. Department of Energy (DOE) commissioned a Conceptual Design Report (CDR) for the National Ignition Facility (NIF) in January 1993 as part of a Key Decision Zero (KD0), justification of Mission Need. Motivated by the progress to date by the Inertial Confinement Fusion (ICF) program in meeting the Nova Technical Contract goals established by the National Academy of Sciences in 1989, the Secretary requested a design using a solid-state laser driver operating at the third harmonic (0.35 {mu}m) of neodymium (Nd) glass. The participating ICF laboratories signed a Memorandum of Agreement in August 1993, and established a Project organization, including a technical team from the Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and the Laboratory for Laser Energetics at the University of Rochester. Since then, the authors completed the NIF conceptual design, based on standard construction at a generic DOE Defense Program`s site, and issued a 7,000-page, 27-volume CDR in May 1994. Over the course of the conceptual design study, several other key documents were generated, including a Facilities Requirements Document, a Conceptual Design Scope and Plan, a Target Physics Design Document, a Laser Design Cost Basis Document, a Functional Requirements Document, an Experimental Plan for Indirect Drive Ignition, and a Preliminary Hazards Analysis (PHA) Document. DOE used the PHA to categorize the NIF as a low-hazard, non-nuclear facility. This article presents an overview of the NIF project.

  17. An analysis of JET fast-wave heating and current drive experiments directly related to ITER

    Energy Technology Data Exchange (ETDEWEB)

    Bhatnagar, V.P.; Eriksson, L.; Gormezano, C.; Jacquinot, J.; Kaye, A.; Start, D.F.H. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    The ITER fast-wave system is required to serve a variety of purposes, in particular, plasma heating to ignition, current profile and burn control and eventually, in conjunction with other schemes, a central non-inductive current drive (CD) for the steady-state operation of ITER. The ICRF heating and current drive data that has been obtained in JET are analyzed in terms of dimensionless parameters, with a view to ascertaining its direct relevance to key ITER requirements. The analysis is then used to identify areas both in physics and technological aspects of ion-cyclotron resonance heating (ICRH) and CD that require further experimentation in ITER-relevant devices such as JET to establish the required data base. (authors). 12 refs., 8 figs.

  18. Ignitable solids having an arrayed structure and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    Adams, David P.; Reeves, Robert V.; Grubbs, Robert K.; Henry, Michael David

    2017-08-08

    The present invention relates to the design and manufacture of an ignitable solid, where the solid is composed of an array of ignitable regions. In some examples, the array provides a three-dimensional periodic arrangement of such ignitable regions. The ignitable region can have any useful geometry and geometric arrangement within the solid, and methods of making such regions are also described herein.

  19. Development status of the ignition system for Vinci

    NARCIS (Netherlands)

    Frenken, G.; Vermeulen, E.; Bouquet, F.; Sanders, H.M.

    2002-01-01

    The development status of ignition system for the new cryogenic upper stage engine Vinci is presented. The concept differs from existing upper stage ignition systems as its functioning is engine independent. The system consists of a spark torch igniter, a highpressure igniter feed system and an exci

  20. Report from the Integrated Modeling Panel at the Workshop on the Science of Ignition on NIF

    Energy Technology Data Exchange (ETDEWEB)

    Marinak, M; Lamb, D

    2012-07-03

    This section deals with multiphysics radiation hydrodynamics codes used to design and simulate targets in the ignition campaign. These topics encompass all the physical processes they model, and include consideration of any approximations necessary due to finite computer resources. The section focuses on what developments would have the highest impact on reducing uncertainties in modeling most relevant to experimental observations. It considers how the ICF codes should be employed in the ignition campaign. This includes a consideration of how the experiments can be best structured to test the physical models the codes employ.

  1. An Exploratory Investigation of the Influence of Igniter Chemistry on Ignition in Porous Bed Gun Propellants

    Science.gov (United States)

    1981-09-01

    NIAOR Dae intldj UNCLASSIFIED SECURIT 4 LAS S1FICATION OF THIS PAGE(WIh.n D.. E rI.,.d) 20. investigate the ignitibility of NACO propellants when sub...4080 2g 0 24P-NO -007 BP-4080 4g 0 24P-NO Increased Igniter Mass to 4g . -008 BP-4080AV 2g 0 24P-YES Added Center Vent to Igniter. lOg of NACO

  2. Shock induced ignition and DDT in the presence of mechanically driven fluctuations

    Science.gov (United States)

    Wang, Wentian; McDonald, James G.; Radulescu, Matei I.

    2015-11-01

    The present study addresses the problem of shock induced ignition and transition to detonation in the presence of mechanical and thermal fluctuations. These departures from a homogeneous medium are of significant importance in practical situations, where such fluctuations may promote hot-spot ignition and favor the flame transition to detonation. The problem is studied in 1D, where a piston-induced shock ignites the gas. The fluctuations in the shock-compressed medium are controlled by allowing the piston's speed to oscillate around a mean, with controllable frequency and amplitude. A Lagrangian numerical formulation is used, which allows to treat exactly the transient boundary condition at the piston head. The hydrodynamic solver is coupled with the reactive dynamics of the gas using Cantera. The code was verified by comparison with steady state ZND solutions and previous shock induced ignition results in homogeneous media. Results obtained for different fuels illustrate the strong relation of the DDT amplification length to mechanical fluctuations in systems with a high effective activation energy and fast rate of energy deposition, consistent with experiments performed on fast flame acceleration in the presence of strong mechanical perturbations. Financial support from NSERC and Shell, with A. Pekalski and M. Levin as technical monitors, are greatly acknowledged.

  3. Experimental study of combustion behavior during continuous hydrogen injection with an operating igniter

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zhe, E-mail: zhe.liang@cnl.ca; Clouthier, Tony; Thomas, Bryan

    2016-03-15

    Highlights: • Combustion during continuous hydrogen release. • Periodical slow burning with a low release rate or weak turbulence. • Fast global burning with stratified hydrogen or strong turbulence. • Initiation of standing flame. - Abstract: Deliberate hydrogen ignition systems have been widely installed in many water cooled nuclear power plants to mitigate hydrogen risk in a loss-of-coolant accident. Experimental studies were performed at a large scale facility to simulate a post-accident containment scenario, where hydrogen is released into a volume (not closed) with an energized igniter. The test chamber had a volume of 60 m{sup 3}. The test parameters included hydrogen injection mass flow rate, injection elevation, igniter elevation, and level of turbulence in the chamber. Several dynamic combustion behaviors were observed. Under certain conditions, slow burning occurred periodically or locally without significant pressurization, and the hydrogen concentration could be maintained near the lean hydrogen flammability limit or a steady hydrogen distribution profile could be formed with a maximum hydrogen concentration less than 9 vol.%. Under other conditions, a global fast burn or a burn moving along the hydrogen dispersion pathway was observed and was followed by an immediate initiation of a standing flame. The study provided a better understanding of the dynamic combustion behavior induced by a deliberate igniter during a continuous hydrogen release. The data can be used for validation of combustion models used for hydrogen safety analysis.

  4. Experiments and simulations on non-plasma ignition of semiconductor bridge igniter

    Science.gov (United States)

    Du, Weiqiang; Zhou, Bin; Liu, Jupeng; Li, Yong; Wang, Jun

    2017-01-01

    Since semiconductor bridge (SCB) igniter has been invented, it is commonly considered as a plasma generator. However, the plasma ignition mechanism may be affected by the hotspot ignition temperature of the primary explosives that is lower than the melting point of SCB in the igniter. In an effort to investigate the non-plasma ignition performance of SCB igniter, a one-dimensional model was established for temperature distribution analysis under constant current and capacitor discharge excitation. The simulation results featured the progress of heat transfer and the energy level required by non-plasma ignition of SCB was estimated. Furthermore, sensitivity experiments were carried out to test simulation results and to obtain the firing current range of SCB igniter with lead styphnate (LTNR). Experiment results indicated that safety conditions are 1.953 A constant current input lasting 1 ms under constant current excitation and 7.072 V voltage input using 47 µF storage capacitor under capacitor discharge excitation. All-firing conditions of non-plasma ignition are 2.035 A constant current input lasting 1 ms under constant current excitation and 7.647 V voltage input using 47 µF storage capacitor under capacitor discharge excitation.

  5. Initial Testing of a Prototype Laser Ignition Chamber

    Science.gov (United States)

    2014-03-01

    investigated for the ignition of many energetic materials, including igniter materials such as black powder, nitrocellulose , M44 propellant (44...nitroglycerin, 52% nitrocellulose ), and numerous other propellants (11–34). Lasers used for these studies included Nd:glass lasers (up to 30 J at 1.054...It was observed that some propellants which do not ignite in air with certain lasers were effectively ignited when enclosed in a laser ignition

  6. MECHANISM ON DISTRIBUTION OF PILOT FUEL SPRAY AND COMPRESSING IGNITION IN PREMIXED NATURAL GAS ENGINE IGNITED BY PILOT DIESEL

    Institute of Scientific and Technical Information of China (English)

    Yao Chunde; Yao Guangtao; Song Jinou; Wang Yinshan

    2005-01-01

    Numerical simulations of pilot fuel spray and compressing ignition for pre-mixed natural gas ignited by pilot diesel are described. By means of these modeling, the dual fuel and diesel fuel ignition mechanism of some phenomena investigated on an optional engine by technology of high-speed CCD is analyzed. It is demonstrated that the longer delay of ignition in dual fuel engine is not mainly caused by change of the mixture thermodynamics parameters. The analysis results illustrate that the ignition of pre-mixed natural gas ignited by pilot diesel taking place in dual fuel engine is a process of homogenous charge compression ignition.

  7. Imploding Ignition Waves. I. One-dimensional Analysis

    Science.gov (United States)

    Kushnir, Doron; Livne, Eli; Waxman, Eli

    2012-06-01

    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 GtR 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. IMPLODING IGNITION WAVES. I. ONE-DIMENSIONAL ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Kushnir, Doron; Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Livne, Eli [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)

    2012-06-20

    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{sub crit}. An approximate analytic expression for R{sub 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{sub crit} {approx} 100 {mu}m (spherical) and R{sub crit} {approx} 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{sub 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{sub 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.

  9. Ignition of Propellants Through Nanostructured Materials

    Science.gov (United States)

    2016-03-31

    case gaseous O2 was introduced in a coaxial flow at a rate of 7 Lit/min with a swirl motion in order to produce an effective fuel and oxidizer mixing...system should be robust, efficient , reliable, simple, low cost, and flexible. Also, an ignition system should initiate combustion under a broad range...discovered that the SWCNT material does not ignite well if wet, so we encapsulated the material to protect it from the fuel spray. To improve the

  10. Dynamic Regime of Ignition of Solid Propellant

    Directory of Open Access Journals (Sweden)

    Zolotorev Nikolay

    2016-01-01

    Full Text Available This article presents a dynamic regime of exposure of the radiant flux on the sample of gun-cotton. Obtained time the ignition of gun-cotton in the heating conditions of increasing heat flux in the range from 0.2 W/cm2 to 22 W/cm2. A comparison of the delay times of the ignition when heated variable and constant heat flux.

  11. IGNITION ACTIVATION ENERGY OF MATERIALS BASED

    OpenAIRE

    Peter RANTUCH; Igor WACHTER; Ivan HRUŠOVSKÝ; Balog, Karol

    2016-01-01

    This contribution is aimed to compare the values of the ignition activation energies of two types of polyamide – Slovamid 6 FRB and Slovamid GF 50 LTS. Samples were isothermally stressed at five different temperatures between 500 °C a 550 °C, while the time to initiation of the flame combustion was monitored. Subsequently from the measured times were compiled Arrhenius plots under which activation energy of ignition of both polymers were calculated. The values of activation energies were 106 ...

  12. Spark Ignition of Monodisperse Fuel Sprays. Ph.D. Thesis

    Science.gov (United States)

    Danis, Allen M.; Cernansky, Nicholas P.; Namer, Izak

    1987-01-01

    A study of spark ignition energy requirements was conducted with a monodisperse spray system allowing independent control of droplet size, equivalent ratio, and fuel type. Minimum ignition energies were measured for n-heptane and methanol sprays characterized at the spark gap in terms of droplet diameter, equivalence ratio (number density) and extent of prevaporization. In addition to sprays, minimum ignition energies were measured for completely prevaporized mixtures of the same fuels over a range of equivalence ratios to provide data at the lower limit of droplet size. Results showed that spray ignition was enhanced with decreasing droplet size and increasing equivalence ratio over the ranges of the parameters studied. By comparing spray and prevaporized ignition results, the existence of an optimum droplet size for ignition was indicated for both fuels. Fuel volatility was seen to be a critical factor in spray ignition. The spray ignition results were analyzed using two different empirical ignition models for quiescent mixtures. Both models accurately predicted the experimental ignition energies for the majority of the spray conditions. Spray ignition was observed to be probabilistic in nature, and ignition was quantified in terms of an ignition frequency for a given spark energy. A model was developed to predict ignition frequencies based on the variation in spark energy and equivalence ratio in the spark gap. The resulting ignition frequency simulations were nearly identical to the experimentally observed values.

  13. Ignition Delay Studies on Hypergolic Fuel Grains

    Directory of Open Access Journals (Sweden)

    S. R. Jain

    1988-07-01

    Full Text Available The ignition delays of several solid hypergolic fuel compositions, casted using various polymeric binders, or as melts, have been determined with fuming nitric acid as oxidizer. The ignition delays of various hypergolic fuel compositions increase drasticaliy on casting with binders like. carboxyl or hydroxyl termninated polybutadiene. Fuel grains cast using some newly syhthesised epoxy  resins with other ingrcdients, such as curing agent, magnesium powder and fuel, have short ignition delays of the order of 200 ms, and also good mechanical strength. Increasing the amount of binder in the composition retards the hypergolicity of the rain. Similar studies have been made on melt-cast systems using low melting hypergolic fuels for casting fuel powders. The ignition delays of the melt-cast grains, are longer than those determined taking the composition in the powder form. The effect of highly hypergolic additives, and metal powders, on the ignition delay of the cast compositions has been determined. Grains having good mechanical strength and short ignition delays have been obtained by optimising the fuel grain composition.

  14. EXPERIMENTAL STUDY OF MINIMUM IGNITION TEMPERATURE

    Directory of Open Access Journals (Sweden)

    Igor WACHTER

    2015-12-01

    Full Text Available The aim of this scientific paper is an analysis of the minimum ignition temperature of dust layer and the minimum ignition temperatures of dust clouds. It could be used to identify the threats in industrial production and civil engineering, on which a layer of combustible dust could occure. Research was performed on spent coffee grounds. Tests were performed according to EN 50281-2-1:2002 Methods for determining the minimum ignition temperatures of dust (Method A. Objective of method A is to determine the minimum temperature at which ignition or decomposition of dust occurs during thermal straining on a hot plate at a constant temperature. The highest minimum smouldering and carbonating temperature of spent coffee grounds for 5 mm high layer was determined at the interval from 280 °C to 310 °C during 600 seconds. Method B is used to determine the minimum ignition temperature of a dust cloud. Minimum ignition temperature of studied dust was determined to 470 °C (air pressure – 50 kPa, sample weight 0.3 g.

  15. 1{sup st} annual workshop proceedings of the collaborative project ''Fast/instant release of safety relevant radionuclides from spent nuclear fuel'' (7{sup th} EC FP CP FIRST-Nuclides)

    Energy Technology Data Exchange (ETDEWEB)

    Kienzler, Bernhard; Metz, Volker; Duro, Lara; Valls, Alba (eds.)

    2013-07-01

    The EURATOM FP7 Collaborative Project ''Fast / Instant Release of Safety Relevant Radionuclides from Spent Nuclear Fuel (CP FIRST-Nuclides)'' started in January 1, 2012 and extends over 3 years. The European nuclear waste management organisations contributing to the Technology Platform ''Implementing Geological Disposal (IGD-TP)'' considered the fast / instant release of safety relevant radionuclides from high burn-up spent nuclear fuel as one of the key topics in the deployment plan. For this reason, the CP FIRST-Nuclides deals with understanding the behaviour of high burn-up uranium oxide (UO{sub 2}) spent nuclear fuels in deep geological repositories. The fast / instant release of radionuclides from spent nuclear fuel was investigated in a series of previous European. In addition, there were several studies mainly of the French research programs that investigated and quantified the rapid. However, several important issues are still open and consequently, the CP FIRST-Nuclides aims on covering this deficiency of knowledge, determining, for example, the ''instant release fraction (IRF)'' values of iodine, chlorine, carbon and selenium that are still largely unknown. Fuel elements from different Light Water Reactors (LWRs), with different enrichments, burn-up and average power rates need to be disposed of in Europe. This waste type represents one of the sources for the release of radionuclides after loss of integrity of a disposed canister. The quantification of time dependent release of radionuclides from spent high burn-up UO{sub 2} fuel is required for safety analyses. The first release fraction consists of radionuclides in gaseous form, and those showing a high solubility in groundwater. LWRs use conventional oxide fuels with initial enrichments of up to 5 wt.% {sup 235}U for reaching average burn-up of ≤ 60 GWd/t{sub HM}. During the use of UO{sub 2} in a reactor, a significantly higher burn-up takes

  16. Ignition and combustion phenomena on a moving grate: with application to the thermal conversion of biomass and municipal solid waste

    NARCIS (Netherlands)

    Blijderveen, M.

    2012-01-01

    Combustion can be defined as a fast oxidation process of a solid, gaseous or liquid fuel at elevated temperatures. In any combustion process, ignition plays an essential role. Not only to initiate the combustion process, but also to maintain it. Especially in solid fuel combustion on a grate, where

  17. Aerospace Laser Ignition/Ablation Variable High Precision Thruster

    Science.gov (United States)

    Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

    2015-01-01

    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

  18. Minitature electro-pyrotechnic igniter, and ignition head for the same

    NARCIS (Netherlands)

    Vliet, L.D. van; Schuurbiers, C.A.H.; Tata Nardini, F.

    2014-01-01

    An electric non-pyrotechnic ignition head (100) suitable for use in an electro- pyrotechnic igniter (1), comprising: a housing (102) defining a front opening (106); - an electrically insulative, thermally conductive bridge filament support body (130) that is at least partly disposed in said front

  19. Performance and Emission Characteristics on Glow Plug Hot Surface Ignition C.I. Engine Using Methanol as Fuel With Additive

    Directory of Open Access Journals (Sweden)

    B.OMPRAKASH

    2015-07-01

    Full Text Available The concept of using alcohol fuels as alternative to diesel fuel in diesel engine is recent one. The scarcity of transportation petroleum fuels due to the fast depletion of the petroleum deposits and frequent rise in their costs in the international market have spurred many efforts to find alternatives. Alcohols were quickly recognized as prime candidates to displace or replace high octane petroleum fuels. Innovative thinking led to find varies techniques by which alcohol can be used as fuel in diesel engine. Amongst the fuel alternative proposed, the most favourest ones are methanol and ethanol. The specific tendency of alcohols to ignite easily from a hot surface makes it suitable to ignite in a diesel engine by different methods. The advantage of this property of alcohols enables to design and construct a new type of engine called surface ignition engine. Methanol and ethanol are very susceptible to surface ignition, this method is very suitable for these fuels. The hot surfaces which, can be used in surface ignition engine are electrically heated glow plug with hot surface. Hence present research work carries the experimental investigation on glow plug hot surface ignition engine, by adding different additives with methanol and ethanol as fuels, with an objective to find the best one performance, emission and compression parameters.

  20. 3rd Conference on Ignition Systems for Gasoline Engines

    CERN Document Server

    Sens, Marc

    2017-01-01

    The volume includes selected and reviewed papers from the 3rd Conference on Ignition Systems for Gasoline Engines in Berlin in November 2016. Experts from industry and universities discuss in their papers the challenges to ignition systems in providing reliable, precise ignition in the light of a wide spread in mixture quality, high exhaust gas recirculation rates and high cylinder pressures. Classic spark plug ignition as well as alternative ignition systems are assessed, the ignition system being one of the key technologies to further optimizing the gasoline engine.

  1. Dark Matter Ignition of Type Ia Supernovae.

    Science.gov (United States)

    Bramante, Joseph

    2015-10-02

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way.

  2. Chemical Kinetics of Hydrocarbon Ignition in Practical Combustion Systems

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C.K.

    2000-07-07

    Chemical kinetic factors of hydrocarbon oxidation are examined in a variety of ignition problems. Ignition is related to the presence of a dominant chain branching reaction mechanism that can drive a chemical system to completion in a very short period of time. Ignition in laboratory environments is studied for problems including shock tubes and rapid compression machines. Modeling of the laboratory systems are used to develop kinetic models that can be used to analyze ignition in practical systems. Two major chain branching regimes are identified, one consisting of high temperature ignition with a chain branching reaction mechanism based on the reaction between atomic hydrogen with molecular oxygen, and the second based on an intermediate temperature thermal decomposition of hydrogen peroxide. Kinetic models are then used to describe ignition in practical combustion environments, including detonations and pulse combustors for high temperature ignition, and engine knock and diesel ignition for intermediate temperature ignition. The final example of ignition in a practical environment is homogeneous charge, compression ignition (HCCI) which is shown to be a problem dominated by the kinetics intermediate temperature hydrocarbon ignition. Model results show why high hydrocarbon and CO emissions are inevitable in HCCI combustion. The conclusion of this study is that the kinetics of hydrocarbon ignition are actually quite simple, since only one or two elementary reactions are dominant. However, there are many combustion factors that can influence these two major reactions, and these are the features that vary from one practical system to another.

  3. Spark ignition of aviation fuel in isotropic turbulence

    Science.gov (United States)

    Krisman, Alex; Lu, Tianfeng; Borghesi, Giulio; Chen, Jacqueline

    2016-11-01

    Turbulent spark ignition occurs in combustion engines where the spark must establish a viable flame kernel that leads to stable combustion. A competition exists between kernel growth, due to flame propagation, and kernel attenuation, due to flame stretch and turbulence. This competition can be measured by the Karlovitz number, Ka, and kernel viability decreases rapidly for Ka >> 1 . In this study, the evolution of an initially spherical flame kernel in a turbulent field is investigated at two cases: Ka- (Ka = 25) and Ka+ (Ka = 125) using direct numerical simulation (DNS). A detailed chemical mechanism for jet fuel (Jet-A) is used, which is relevant for many practical conditions, and the mechanism includes a pyrolysis sub-model which is important for the ignition of large hydrocarbon fuels. An auxiliary non-reacting DNS generates the initial field of isotropic turbulence with a turbulent Reynolds number of 500 (Ka-) and 1,500 (Ka+). The kernel is then imposed at the center of the domain and the reacting DNS is performed. The Ka- case survives and the Ka+ case is extinguished. An analysis of the turbulence chemistry interactions is performed and the process of extinction is described. Department of Energy - Office of Basic Energy Science under Award No. DE-SC0001198.

  4. Ignition threshold for non-Maxwellian plasmas

    CERN Document Server

    Hay, Michael J

    2015-01-01

    An optically thin $p$-$^{11}$B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. The minimum Lawson criterion for thermal $p$-$^{11}$B plasmas and the minimum $\\rho R$ required for ICF volume ignition are calculated. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for this utility, we consider a monoenergetic beam with particle energy selected to maximize the beam- thermal reactivity. Channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and $\\rho R$, improves reactivity at constant pressure, and could be used to remove helium ash. The gains realized with a beam thus establish an upper bound for the reductions in igniti...

  5. Target Visualization at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Daniel Abraham [Univ. of California, Davis, CA (United States)

    2011-01-01

    As the National Ignition Facility continues its campaign to achieve ignition, new methods and tools will be required to measure the quality of the targets used to achieve this goal. Techniques have been developed to measure target surface features using a phase-shifting diffraction interferometer and Leica Microsystems confocal microscope. Using these techniques we are able to produce a detailed view of the shell surface, which in turn allows us to refine target manufacturing and cleaning processes. However, the volume of data produced limits the methods by which this data can be effectively viewed by a user. This paper introduces an image-based visualization system for data exploration of target shells at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. It aims to combine multiple image sets into a single visualization to provide a method of navigating the data in ways that are not possible with existing tools.

  6. Progress on LMJ targets for ignition

    Energy Technology Data Exchange (ETDEWEB)

    Cherfils-Clerouin, C; Boniface, C; Bonnefille, M; Fremerye, P; Galmiche, D; Gauthier, P; Giorla, J; Lambert, F; Laffite, S; Liberatore, S; Loiseau, P; Malinie, G; Masse, L; Masson-Laborde, P E; Monteil, M C; Poggi, F; Seytor, P; Wagon, F; Willien, J L, E-mail: catherine.cherfils@cea.f [CEA, DAM, DIF, F-91297 Arpajon (France)

    2010-08-01

    Targets designed to produce ignition on the Laser MegaJoule are presented. The LMJ experimental plans include the attempt of ignition and burn of an ICF capsule with 160 laser beams, delivering up to 1.4MJ and 380TW. New targets needing reduced laser energy with only a small decrease in robustness have then been designed for this purpose. Working specifically on the coupling efficiency parameter, i.e. the ratio of the energy absorbed by the capsule to the laser energy, has led to the design of a rugby-shaped cocktail hohlraum. 1D and 2D robustness evaluations of these different targets shed light on critical points for ignition, that can be traded off by tightening some specifications or by preliminary experimental and numerical tuning experiments.

  7. Progress on LMJ targets for ignition

    Energy Technology Data Exchange (ETDEWEB)

    Cherfils-Clerouin, C; Boniface, C; Bonnefille, M; Dattolo, E; Galmiche, D; Gauthier, P; Giorla, J; Laffite, S; Liberatore, S; Loiseau, P; Malinie, G; Masse, L; Masson-Laborde, P E; Monteil, M C; Poggi, F; Seytor, P; Wagon, F; Willien, J L, E-mail: catherine.cherfils@cea.f [CEA, DAM, DIF, F-91297 Arpajon (France)

    2009-12-15

    Targets designed to produce ignition on the Laser Megajoule (LMJ) are being simulated in order to set specifications for target fabrication. The LMJ experimental plans include the attempt of ignition and burn of an ICF capsule with 160 laser beams, delivering up to 1.4 MJ and 380 TW. New targets needing reduced laser energy with only a small decrease in robustness have then been designed for this purpose. Working specifically on the coupling efficiency parameter, i.e. the ratio of the energy absorbed by the capsule to the laser energy, has led to the design of a rugby-ball shaped cocktail hohlraum; with these improvements, a target based on the 240-beam A1040 capsule can be included in the 160-beam laser energy-power space. Robustness evaluations of these different targets shed light on critical points for ignition, which can trade off by tightening some specifications or by preliminary experimental and numerical tuning experiments.

  8. Improving the ignition quality of fuels

    KAUST Repository

    Sarathy, Mani

    2017-06-08

    Provided herein are compounds and methods of producing compounds for improving ignition quality and combustion efficiency of fuels, for example fossil fuels. In various aspects we generate highly oxygenated compounds from hydrocarbon feedstocks. The feedstock can be a branched alkane or n-alkane having a chain length greater than or equal to 6, a cycloalkane with a 5 or 6 membered ring structure, or a alkylated cycloalkane with 5 or more carbon atoms. The reactant can be fed in the gas- phase to a partial oxidation reactor (with or without a catalyst), and at a fixed temperature, mixture composition, and residence time. The reactant can be converted to a mixture of products including keto hydroperoxides, diketo hydroperoxides, keto dihydroperoxides, hydroperoxyl cyclic ethers, and alkenyl hydroperoxides. The compounds are inherently unstable and can quickly decompose to highly reactive radical species that can be used to improve the ignition quality of a fuel and advance ignition in an engine.

  9. Ignition of THKP and TKP pyrotechnic powders :

    Energy Technology Data Exchange (ETDEWEB)

    Maharrey, Sean P.; Erikson, William W; Highley, Aaron M.; Wiese-Smith, Deneille; Kay, Jeffrey J

    2014-03-01

    We have conducted Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS) experiments on igniter/actuator pyrotechnic powders to characterize the reactive processes controlling the ignition and combustion behavior of these materials. The experiments showed a complex, interactive reaction manifold involving over ten reaction pathways. A reduced dimensionality reaction manifold was developed from the detailed 10-step manifold and is being incorporated into existing predictive modeling codes to simulate the performance of pyrotechnic powders for NW component development. The results from development of the detailed reaction manifold and reduced manifold are presented. The reduced reaction manifold has been successfully used by SNL/NM modelers to predict thermal ignition events in small-scale testing, validating our approach and improving the capability of predictive models.

  10. Ignition delay of dual fuel engine operating with methanol ignited by pilot diesel

    Institute of Scientific and Technical Information of China (English)

    Hongbo ZOU; Lijun WANG; Shenghua LIU; Yu LI

    2008-01-01

    An investigation on the ignition delay of a dual fuel engine operating with methanol ignited by pilot diesel was conducted on a TY1100 direct-injection diesel engine equipped with an electronic controlled methanol low-pressure injection system. The experimental results show that the polytropic index of compression process of the dual fuel engine decreases linearly while the ignition delay increases with the increase in methanol mass fraction. Compared with the conventional diesel engine, the igni-tion delay increment of the dual fuel engine is about 1.5° at a methanol mass fraction of 62%, an engine speed of 1600 r/min, and full engine load. With the elevation of the intake charge temperature from 20℃ to 40℃ and then to 60℃, the ignition delay of the dual fuel engine decreases and is more obvious at high temperature. Moreover, with the increase in engine speed, the ignition delay of the dual fuel engine by time scale (ms) decreases clearly under all engine operating conditions. However, the ignition delay of the dual fuel engine increases remark-ably by advancing the delivery timing of pilot diesel, espe-cially at light engine loads.

  11. National Ignition Facility Target Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Wavrik, R W; Cox, J R; Fleming, P J

    2000-10-05

    On June 11, 1999 the Department of Energy dedicated the single largest piece of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. The ten (10) meter diameter aluminum target high vacuum chamber will serve as the working end of the largest laser in the world. The output of 192 laser beams will converge at the precise center of the chamber. The laser beams will enter the chamber in two by two arrays to illuminate 10 millimeter long gold cylinders called hohlraums enclosing 2 millimeter capsule containing deuterium, tritium and isotopes of hydrogen. The two isotopes will fuse, thereby creating temperatures and pressures resembling those found only inside stars and in detonated nuclear weapons, but on a minute scale. The NIF Project will serve as an essential facility to insure safety and reliability of our nation's nuclear arsenal as well as demonstrating inertial fusion's contribution to creating electrical power. The paper will discuss the requirements that had to be addressed during the design, fabrication and testing of the target chamber. A team from Sandia National Laboratories (SNL) and LLNL with input from industry performed the configuration and basic design of the target chamber. The method of fabrication and construction of the aluminum target chamber was devised by Pitt-Des Moines, Inc. (PDM). PDM also participated in the design of the chamber in areas such as the Target Chamber Realignment and Adjustment System, which would allow realignment of the sphere laser beams in the event of earth settlement or movement from a seismic event. During the fabrication of the target chamber the sphericity tolerances had to be addressed for the individual plates. Procedures were developed for forming, edge preparation and welding of individual plates. Construction plans were developed to allow the field construction of the target chamber to occur parallel to other NIF construction activities. This

  12. A Computational and Experimental Study of Ignition Behavior of Gasoline Surrogate Fuels Under Low-Temperature Combustion Conditions

    Science.gov (United States)

    Han, J.; Haworth, D. C.; Kalaskar, V. B.; Boehman, A. L.

    2016-11-01

    One strategy for next-generation engines is low-temperature compression ignition of gasoline. Reaction pathways that are not relevant for high-temperature flame propagation are activated under these conditions, and the ignition behavior of these fuels under low-temperature conditions has not been widely explored. Here the ignition behavior of gasoline and two- and three-component surrogates has been studied experimentally and computationally over a range of operating conditions of interest for low-temperature engine combustion. Experiments were performed in a single-cylinder research engine. For each fuel blend, the critical compression ratio (lowest compression ratio at which the main ignition occurs) was determined over a range of operating conditions, by varying one parameter at a time with all other parameters held fixed. A simplified CFD model that considers detailed chemical kinetics was used to simulate the experiment. The focus of the study is to determine which surrogate fuel mixtures and chemical mechanisms are able to capture the ignition behavior of gasoline under these conditions. For example, different ignition behavior is found for different surrogate mixtures that all have the same Research Octane Number, and it is important to capture this behavior in CFD models.

  13. Robustness studies of ignition targets for the National Ignition Facility in two dimensionsa)

    Science.gov (United States)

    Clark, Daniel S.; Haan, Steven W.; Salmonson, Jay D.

    2008-05-01

    Inertial confinement fusion capsules are critically dependent on the integrity of their hot spots to ignite. At the time of ignition, only a certain fractional perturbation of the nominally spherical hot spot boundary can be tolerated and the capsule still achieve ignition. The degree to which the expected hot spot perturbation in any given capsule design is less than this maximum tolerable perturbation is a measure of the ignition margin or robustness of that design. Moreover, since there will inevitably be uncertainties in the initial character and implosion dynamics of any given capsule, all of which can contribute to the eventual hot spot perturbation, quantifying the robustness of that capsule against a range of parameter variations is an important consideration in the capsule design. Here, the robustness of the 300eV indirect drive target design for the National Ignition Facility [Lindl et al., Phys. Plasmas 11, 339 (2004)] is studied in the parameter space of inner ice roughness, implosion velocity, and capsule scale. A suite of 2000 two-dimensional simulations, run with the radiation hydrodynamics code LASNEX, is used as the data base for the study. For each scale, an ignition region in the two remaining variables is identified and the ignition cliff is mapped. In accordance with the theoretical arguments of Levedahl and Lindl [Nucl. Fusion 37, 165 (1997)] and Kishony and Shvarts [Phys. Plasmas 8, 4925 (2001)], the location of this cliff is fitted to a power law of the capsule implosion velocity and scale. It is found that the cliff can be quite well represented in this power law form, and, using this scaling law, an assessment of the overall (one- and two-dimensional) ignition margin of the design can be made. The effect on the ignition margin of an increase or decrease in the density of the target fill gas is also assessed.

  14. Highly Durable Catalysts for Ignition of Advanced Monopropellants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Monopropellants are readily ignited or decomposed over a bed of solid catalyst. A serious limitation of existing catalysts in the ignition of advanced...

  15. National Ignition Facility project acquisition plan revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Clobes, A.R.

    1996-10-01

    The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility M Project. It was prepared for the NIP Prood Office by the NIF Procurement Manager.

  16. Low Energy Electronic Ignition System for NOFBX Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a miniature, low RF noise ignition module for NOFBX propulsion systems. This ignition module is designed utilizing unique properties of the...

  17. IGNITION ACTIVATION ENERGY OF MATERIALS BASED

    Directory of Open Access Journals (Sweden)

    Peter RANTUCH

    2016-06-01

    Full Text Available This contribution is aimed to compare the values of the ignition activation energies of two types of polyamide – Slovamid 6 FRB and Slovamid GF 50 LTS. Samples were isothermally stressed at five different temperatures between 500 °C a 550 °C, while the time to initiation of the flame combustion was monitored. Subsequently from the measured times were compiled Arrhenius plots under which activation energy of ignition of both polymers were calculated. The values of activation energies were 106 kJ.mol-1 and 158.0 kJ.mol-1 for Slovamid 6 FRB 4 and Slovamid 6 GF 50 LTS.

  18. Igniters for Liquid Oxygen/Liquid Methane Technology Development

    Science.gov (United States)

    Osborne, Robin J.; Elam, Sandra K.; Peschel, William P.

    2008-01-01

    As part of NASA's technology development of liquid methane / liquid oxygen engines for future exploration missions, two different igniters were recently studied at NASA Marshall Space Flight Center. The first igniter tested was an impinging injection, spark-initiated torch igniter, and the second was a microwave-generated plasma igniter. The purpose of the ignition tests was to define the ignition limits under vacuum conditions and characterize the transient start-up performance as a function of propellant mixture ratio (MR), mass flow rates, inlet temperatures, and pre-ignition chamber pressure. In addition, for the impinging igniter two different spark plugs were tested, and for the microwave igniter the magnetron filament warm-up time and the magnetron input power were both varied. The results gathered from these tests indicated that the impinging igniter is capable of operating over an MR range of 2 - 27, with methane and oxygen inlet temperatures as low as -161 F and -233 F, respectively. The microwave igniter was tested over an MR range of 2 - 9, with methane and oxygen inlet temperatures as low as -90 F and -200 F, respectively. The microwave igniter achieved ignition over this range, although an upper ignition limit was determined for the oxidizer mass flow rate. In general, the torch exhaust temperatures for the microwave igniter were not as high as those attained with the impinging igniter. The microwave igniter, however, was hot-fired 17 times and was still operational, whereas the impinging igniter spark plugs experienced thermal shock and erosion over nine hot-fire tests. It was concluded that for the microwave igniter better mixing of the propellants might be required in order to both raise the torch exhaust temperature and decrease the required magnetron input power, and for the impinging igniter the spark plug position within the igniter chamber should be varied in future tests to identify a more optimal location. All of the igniter tests were

  19. Laser Ignition Technology for Bi-Propellant Rocket Engine Applications

    Science.gov (United States)

    Thomas, Matt; Bossard, John; Early, Jim; Trinh, Huu; Dennis, Jay; Turner, James (Technical Monitor)

    2001-01-01

    This viewgraph presentation gives an overview of laser ignition technology for bipropellant rocket engines applications. The objectives of this project include: (1) the selection test chambers and flows; (2) definition of the laser ignition setup; (3) pulse format optimization; (4) fiber optic coupled laser ignition system analysis; and (5) chamber integration issues definition. The testing concludes that rocket combustion chamber laser ignition is imminent. Support technologies (multiplexing, window durability/cleaning, and fiber optic durability) are feasible.

  20. 14 CFR 25.981 - Fuel tank ignition prevention.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank ignition prevention. 25.981 Section 25.981 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... ignition prevention. (a) No ignition source may be present at each point in the fuel tank or fuel...

  1. Proton pinhole imaging on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B., E-mail: zylstra@lanl.gov [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Park, H.-S.; Ross, J. S.; Higginson, D. P.; Huntington, C.; Pollock, B.; Remington, B.; Rinderknecht, H. G.; Ryutov, D.; Turnbull, D.; Wilks, S. C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Fiuza, F. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Frenje, J. A.; Li, C. K.; Petrasso, R. D.; Séguin, F. H. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2016-11-15

    Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4 ×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. When the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.

  2. Material Ignition and Suppression Test (MIST) in Space Exploration Atmospheres, Summary of Research

    Science.gov (United States)

    Fernandez-Pello, Carlos

    2013-01-01

    The Material Ignition and Suppression Test (MIST) project has had the objective of evaluating the ease of ignition and the fire suppression of materials used in spacecraft under environmental condition expected in a spacecraft. For this purpose, an experimental and theoretical research program is being conducted on the effect of space exploration atmospheres (SEA) on the piloted ignition of representative combustible materials, and on their fire suppression characteristics. The experimental apparatus and test methodology is derived from the Forced Ignition and Flame Spread Test (FIST), a well-developed bench scale test designed to extract material properties relevant to prediction of material flammability. In the FIST test, materials are exposed to an external radiant flux and the ignition delay and critical mass flux at ignition are determined as a function of the type of material and environmental conditions. In the original MIST design, a small-scale cylindrical flow duct with fuel samples attached to its inside wall was heated by a cylindrical heater located at the central axis of the cylinder. However, as the project evolved it was decided by NASA that it would be better to produce an experimental design that could accommodate other experiments with different experimental concepts. Based on those instructions and input from the requirements of other researchers that may share the hardware in an ISS/CIR experiment, a cylindrical design based on placing the sample at the center of an optically transparent tube with heaters equally spaced along the exterior of the cylinder was developed. Piloted ignition is attained by a hot wire igniter downstream of the fuel sample. Environment variables that can be studied via this experimental apparatus include: external radiant flux, oxidizer oxygen concentration, flow velocity, ambient pressure, and gravity level (if flown in the ISS/CIR). This constitutes the current experimental design, which maintains fairly good

  3. Deep Dive Topic: Approach to ignition

    Energy Technology Data Exchange (ETDEWEB)

    Hurricane, O. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kline, J. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Meezan, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mackinnon, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-14

    The current high-foot and related implosions have adequate CR and implosion velocity to ignite, but require improved finesse particularly in, but not limited to, implosion symmetry. This is being pursued. The challenge of controlling drive symmetry is also motivating lower convergence ratio designs. These require higher velocity implosions and are also being pursued.

  4. Plasma ignition for medium calibre ammunition

    NARCIS (Netherlands)

    Driel, C.A. van; Schilt, A.; Simor, M.; Schaffers, P.; Weise, T.

    2012-01-01

    Gun performance is usually affected by the operating temperature of the ammunition or weapon. This is caused by several factors, amongst which the temperature dependency of the propellant ignition and combustion processes. Compensation of temperature effects on weapon or ammunition performance is po

  5. Impacts assessment for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Bay Area Economics

    1996-12-01

    This report documents the economic and other impacts that will be created by the National Ignition Facility (NIF) construction and ongoing operation, as well as the impacts that may be created by new technologies that may be developed as a result of NIF development and operation.

  6. Dark matter ignition of type Ia supernovae

    CERN Document Server

    Bramante, Joseph

    2015-01-01

    Recent studies of low redshift type Ia supernovae (SNIa) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SNIa progenitors. We show that $0.1-10$ PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SNIa. We combine data on SNIa masses with data on the ages of SNIa-adjacent stars. This combination reveals a $ 3 \\sigma$ inverse correlation between SNIa masses and ignition ages, which could result from increased capture of dark matter in 1.4 versus 1.1 solar mass white dwarfs. Future studies of SNIa in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SNI...

  7. Ignition and Thermonuclear Burn on the National Ignition Facility with Imposed Magnetic Fields

    Science.gov (United States)

    Perkins, L. John; Logan, B. G.; Rhodes, M. A.; Zimmerman, G. B.; Ho, D. D.; Blackfield, D. T.; Hawkins, S. A.

    2016-10-01

    We are studying the impact of highly compressed magnetic fields on enhancing the prospects for ignition and burn on the National Ignition Facility (NIF). Both magnetized room-temperature DT gas targets and cryo-ignition capsules are under study. Applied seed fields of 20-70T that compress to greater than 10000T (100MG) under implosion can reduce hotspot conditions required for ignition and propagating burn through range reduction and magnetic mirror trapping of fusion alpha particles, suppression of electron heat conduction and potential stabilization of hydrodynamic instabilities. The applied field may also reduce hohlraum laser-plasma instabilities and suppress the transport of hot electron preheat to the capsule. These combined B-field attributes may permit recovery of ignition, or at least significant alpha particle heating, in capsules that are otherwise submarginal through adverse hydrodynamic or hohlraum-drive conditions. Simulations indicate that optimum initial fields of 50T may produce multi-MJ-yields when applied to our present best experimental capsules. Proof-of-principle experiments for magnetized ignition capsules and hohlraum physics on NIF are now being designed. This work performed under auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  8. Fundamental Studies of Ignition Process in Large Natural Gas Engines Using Laser Spark Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Azer Yalin; Bryan Willson

    2008-06-30

    Past research has shown that laser ignition provides a potential means to reduce emissions and improve engine efficiency of gas-fired engines to meet longer-term DOE ARES (Advanced Reciprocating Engine Systems) targets. Despite the potential advantages of laser ignition, the technology is not seeing practical or commercial use. A major impediment in this regard has been the 'open-path' beam delivery used in much of the past research. This mode of delivery is not considered industrially practical owing to safety factors, as well as susceptibility to vibrations, thermal effects etc. The overall goal of our project has been to develop technologies and approaches for practical laser ignition systems. To this end, we are pursuing fiber optically coupled laser ignition system and multiplexing methods for multiple cylinder engine operation. This report summarizes our progress in this regard. A partial summary of our progress includes: development of a figure of merit to guide fiber selection, identification of hollow-core fibers as a potential means of fiber delivery, demonstration of bench-top sparking through hollow-core fibers, single-cylinder engine operation with fiber delivered laser ignition, demonstration of bench-top multiplexing, dual-cylinder engine operation via multiplexed fiber delivered laser ignition, and sparking with fiber lasers. To the best of our knowledge, each of these accomplishments was a first.

  9. Direct numerical simulations of the ignition of lean primary reference fuel/air mixtures with temperature inhomogeneities

    KAUST Repository

    Luong, Minhbau

    2013-10-01

    The effects of fuel composition, thermal stratification, and turbulence on the ignition of lean homogeneous primary reference fuel (PRF)/air mixtures under the conditions of constant volume and elevated pressure are investigated by direct numerical simulations (DNSs) with a new 116-species reduced kinetic mechanism. Two-dimensional DNSs were performed in a fixed volume with a two-dimensional isotropic velocity spectrum and temperature fluctuations superimposed on the initial scalar fields with different fuel compositions to elucidate the influence of variations in the initial temperature fluctuation and turbulence intensity on the ignition of three different lean PRF/air mixtures. In general, it was found that the mean heat release rate increases slowly and the overall combustion occurs fast with increasing thermal stratification regardless of the fuel composition under elevated pressure and temperature conditions. In addition, the effect of the fuel composition on the ignition characteristics of PRF/air mixtures was found to vanish with increasing thermal stratification. Chemical explosive mode (CEM), displacement speed, and Damköhler number analyses revealed that the high degree of thermal stratification induces deflagration rather than spontaneous ignition at the reaction fronts, rendering the mean heat release rate more distributed over time subsequent to thermal runaway occurring at the highest temperature regions in the domain. These analyses also revealed that the vanishing of the fuel effect under the high degree of thermal stratification is caused by the nearly identical propagation characteristics of deflagrations of different PRF/air mixtures. It was also found that high intensity and short-timescale turbulence can effectively homogenize mixtures such that the overall ignition is apt to occur by spontaneous ignition. These results suggest that large thermal stratification leads to smooth operation of homogeneous charge compression-ignition (HCCI

  10. Ignition and timing a guide to rebuilding, repair and replacement

    CERN Document Server

    Beever, Colin

    2015-01-01

    An essential guide to ignition and timing, for classic car owners and restorers. Aimed at both keen amateurs and professionals alike, Ignition and Timing covers the history and evolution of the automotive ignition system, and how to fit, modify and maintain your system for optimum timing and maximum performance. Topics covered include understanding and fault-testing the coil ignition system; post-war distributors and aftermarket systems; how to fit electronic ignitions and modify the distributor, including twin-point distributors; rebuilding and maintenance; Lucas, Delco and Bosch systems

  11. Ignition of organic explosives by an electron beam

    Directory of Open Access Journals (Sweden)

    Ivanov Georgy A.

    2015-01-01

    Full Text Available A numerical simulation of the ignition of organic explosives (PETN, HMX, RDX, TATB with an electron beam was performed. A criterion for the ignition of energetic materials with a melting point below the temperature of ignition is obtained. The results of numerical calculations of the critical energy density of the electron beam are consistent with the criterion of ignition. Calculations of the critical energy density of PETN ignition in good agreement with the experiment. The most sensitive is PETN and the most heat-resistant is TATB.

  12. Flame propagation and counterflow nonpremixed ignition of mixtures of methane and ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.; Kelley, A.P.; Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2010-05-15

    The ignition temperature of nitrogen-diluted mixtures of methane and ethylene counterflowing against heated air was measured up to five atmospheres. In addition, the stretch-corrected laminar flame speeds of mixtures of air, methane and ethylene were determined from outwardly-propagating spherical flames up to 10 atmospheres, for extensive range of the lean-to-rich equivalence ratio. These experimental data, relevant to low- to moderately-high-temperature ignition chemistry and high-temperature flame chemistry, respectively, were subsequently compared with calculations using two detailed kinetic mechanisms. A chemical explosive mode analysis (CEMA) was then conducted to identify the dominant ignition chemistry and the role of ethylene addition in facilitating nonpremixed ignition. Furthermore, the hierarchical structure of the associated oxidation kinetics was examined by comparing the sizes and constituents of the skeletal mechanisms of the pure fuels and their mixtures, derived using the method of directed relation graph (DRG). The skeletal mechanism was further reduced by time-scale analysis, leading to a 24-species reduced mechanism from the detailed mechanism of USC Mech II, validated within the parameter space of the conducted experiments. (author)

  13. Post-earthquake ignition vulnerability assessment of Küçükçekmece District

    Science.gov (United States)

    Yildiz, S. S.; Karaman, H.

    2013-12-01

    In this study, a geographic information system (GIS)-based model was developed to calculate the post-earthquake ignition probability of a building, considering damage to the building's interior gas and electrical distribution system and the overturning of appliances. In order to make our model more reliable and realistic, a weighting factor was used to define the possible existence of each appliance or other contents in the given occupancy. A questionnaire was prepared to weigh the relevance of the different components of post-earthquake ignitions using the analytical hierarchy process (AHP). The questionnaire was evaluated by researchers who were experienced in earthquake engineering and post-earthquake fires. The developed model was implemented to HAZTURK's (Hazards Turkey) earthquake loss assessment software, as developed by the Mid-America Earthquake Center with the help of Istanbul Technical University. The developed post-earthquake ignition tool was applied to Küçükçekmece, Istanbul, in Turkey. The results were evaluated according to structure types, occupancy types, the number of storeys, building codes and specified districts. The evaluated results support the theory that post-earthquake ignition probability is inversely proportional to the number of storeys and the construction year, depending upon the building code.

  14. The role of the National Ignition Facility in the development of inertial fusion energy

    Energy Technology Data Exchange (ETDEWEB)

    Logan, B.G.

    1996-06-01

    The authors have completed a conceptual design for a 1.8-MJ, 500-TW, 0.35-{mu}m solid-state laser system for the National Ignition Facility (NIF), which will demonstrate inertial fusion ignition and gain for national security, energy, and science applications. The technical goal of the U.S. Inertial Confinement Fusion (ICF) Program as stated in the current ICF Five-Year Program Plan is {open_quotes}to produce pure fusion ignition and burn in the laboratory, with fusion yields of 200 to 1000 MJ, in support of three missions: (1) to play an essential role in accessing physics regimes of interest in nuclear weapon design...; (2) to provide an above-ground simulation capability for nuclear weapon effects...; and (3) to develop inertial fusion energy for civilian power production.{close_quotes} This article addresses the third goal-- the development of inertial fusion energy (IFE). This article reports a variety of potential contributions the NIF could make to the development of IFE, drawn from a nationally attended workshop held at the University of California at Berkeley in Feb, 1994. In addition to demonstrating fusion ignition as a fundamental basis for IFE, the findings of the workshop, are that the NIF could also provide important data for target physics and fabrication technology, for IFE target chamber phenomena such as materials responses to target emissions, and for fusion power technology-relevant tests.

  15. National direct-drive program on OMEGA and the National Ignition Facility

    Science.gov (United States)

    Goncharov, V. N.; Regan, S. P.; Campbell, E. M.; Sangster, T. C.; Radha, P. B.; Myatt, J. F.; Froula, D. H.; Betti, R.; Boehly, T. R.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Glebov, V. Yu; Harding, D. R.; Hu, S. X.; Igumenshchev, I. V.; Marshall, F. J.; McCrory, R. L.; Michel, D. T.; Seka, W.; Shvydky, A.; Stoeckl, C.; Theobald, W.; Gatu-Johnson, M.

    2017-01-01

    A major advantage of the laser direct-drive (DD) approach to ignition is the increased fraction of laser drive energy coupled to the hot spot and relaxed hot-spot requirements for the peak pressure and convergence ratios relative to the indirect-drive approach at equivalent laser energy. With the goal of a successful ignition demonstration using DD, the recently established national strategy has several elements and involves multiple national and international institutions. These elements include the experimental demonstration on OMEGA cryogenic implosions of hot-spot conditions relevant for ignition at MJ-scale energies available at the National Ignition Facility (NIF) and developing an understanding of laser-plasma interactions and laser coupling using DD experiments on the NIF. DD designs require reaching central stagnation pressures in excess of 100 Gbar. The current experiments on OMEGA have achieved inferred peak pressures of 56 Gbar (Regan et al 2016 Phys. Rev. Lett. 117 025001). Extensive analysis of the cryogenic target experiments and two- and three-dimensional simulations suggest that power balance, target offset, and target quality are the main limiting factors in target performance. In addition, cross-beam energy transfer (CBET) has been identified as the main mechanism reducing laser coupling. Reaching the goal of demonstrating hydrodynamic equivalence on OMEGA includes improving laser power balance, target position, and target quality at shot time. CBET must also be significantly reduced and several strategies have been identified to address this issue.

  16. Characteristics of Syngas Auto-ignition at High Pressure and Low Temperature Conditions with Thermal Inhomogeneities

    KAUST Repository

    Pal, Pinaki

    2015-05-31

    Effects of thermal inhomogeneities on syngas auto-ignition at high-pressure low-temperature conditions, relevant to gas turbine operation, are investigated using detailed one-dimensional numerical simulations. Parametric tests are carried out for a range of thermodynamic conditions (T = 890-1100 K, P = 3-20 atm) and composition (Ф = 0.1, 0.5). Effects of global thermal gradients and localized thermal hot spots are studied. In the presence of a thermal gradient, the propagating reaction front transitions from spontaneous ignition to deflagration mode as the initial mean temperature decreases. The critical mean temperature separating the two distinct auto-ignition modes is computed using a predictive criterion and found to be consistent with front speed and Damkohler number analyses. The hot spot study reveals that compression heating of end-gas mixture by the propagating front is more pronounced at lower mean temperatures, significantly advancing the ignition delay. Moreover, the compression heating effect is dependent on the domain size.

  17. Temporally resolved imaging on quenching and re-ignition of nanosecond underwater discharge

    Directory of Open Access Journals (Sweden)

    Yong Yang

    2012-12-01

    Full Text Available This paper presents the temporally resolved images of plasma discharge in de-ionized water. The discharge was produced by high voltage pulses with 0.3 ns rise time and 10 ns duration. The temporal resolution of the imaging system was one nanosecond. A unique three-stage process, including a fast ignition at the leading edge of the pulse, quenching at the plateau of the pulse, and self re-ignition at the trailing edge of the pulse, was observed in a single pulse cycle. The maximum measured propagation velocity of the plasma discharge was about 1000 km/s. The possibility of direct ionization in water under high reduced electric field conditions was discussed.

  18. Off-site ignition probability of flammable gases.

    Science.gov (United States)

    Rew, P J; Spencer, H; Daycock, J

    2000-01-07

    A key step in the assessment of risk for installations where flammable liquids or gases are stored is the estimation of ignition probability. A review of current modelling and data confirmed that ignition probability values used in risk analyses tend to be based on extrapolation of limited incident data or, in many cases, on the judgement of those conducting the safety assessment. Existing models tend to assume that ignition probability is a function of release rate (or flammable gas cloud size) alone and they do not consider location, density or type of ignition source. An alternative mathematical framework for calculating ignition probability is outlined in which the approach used is to model the distribution of likely ignition sources and to calculate ignition probability by considering whether the flammable gas cloud will reach these sources. Data are collated on the properties of ignition sources within three generic land-use types: industrial, urban and rural. These data are then incorporated into a working model for ignition probability in a form capable of being implemented within risk analysis models. The sensitivity of the model results to assumptions made in deriving the ignition source properties is discussed and the model is compared with other available ignition probability methods.

  19. Comprehensive study of ignition and combustion of single wooden particles

    DEFF Research Database (Denmark)

    Momenikouchaksaraei, Maryam; Yin, Chungen; Kær, Søren Knudsen

    2013-01-01

    How quickly large biomass particles can ignite and burn out when transported into a pulverized-fuel (pf) furnace and suddenly exposed to a hot gas flow containing oxygen is very important in biomass co-firing design and optimization. In this paper, the ignition and burnout of the largest possible...... for all the test conditions. As the particle is further heated up and the volume-weighted average temperature reaches the onset of rapid decomposition of hemicellulose and cellulose, a secondary homogeneous ignition occurs. The model-predicted ignition delays and burnout times show a good agreement...... with the experimental results. Homogeneous ignition delays are found to scale with specific surface areas while heterogeneous ignition delays show less dependency on the areas. The ignition and burnout are also affected by the process conditions, in which the oxygen concentration is found to have a more pronounced...

  20. Combustion characteristics of spark-ignition and pilot flame ignition systems in a model Wankel stratified charge engine

    Energy Technology Data Exchange (ETDEWEB)

    Muroki, T. [Kanagawa Inst. of Technology, Dept. of Mechanical Engineering, Kanagawa (Japan); Moriyoshi, Y. [Chiba Univ., Dept. of Electronics and Mechanical Engineering, Chiba (Japan)

    2000-11-01

    In a stratified charge engine, a glow plug pilot flame ignition system has been compared with a spark-ignition system for a model stratified charge Wankel combustion chamber. A motored two-stroke diesel engine was operated as a rapid compression and expansion machine with the cylinder head replaced by a model Wankel combustion chamber designed to simulate the temporal changes of air flow and pressure fields inside the chamber of an actual engine. It was found that the pilot flame ignition system had better ignitability and improved combustion characteristics, especially in the lean mixture range, relative to the spark-ignition system. (Author)

  1. The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review

    OpenAIRE

    Arcoumanis, C.; Bae, C.; Crookes, R.; Kinoshita, E

    2008-01-01

    This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application. DME’s diesel engine-compatible properties are its high cetane number and low auto-ignition temperature. In a...

  2. How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

    Science.gov (United States)

    Leins, Martina; Gaiser, Sandra; Schulz, Andreas; Walker, Matthias; Schumacher, Uwe; Hirth, Thomas

    2015-01-01

    This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators — a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes. PMID:25938699

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

    Science.gov (United States)

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

    2016-07-01

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

  4. Rapid ignition of fluidized bed boiler

    Science.gov (United States)

    Osborn, Liman D.

    1976-12-14

    A fluidized bed boiler is started up by directing into the static bed of inert and carbonaceous granules a downwardly angled burner so that the hot gases cause spouting. Air is introduced into the bed at a rate insufficient to fluidize the entire bed. Three regions are now formed in the bed, a region of lowest gas resistance, a fluidized region and a static region with a mobile region at the interface of the fluidized and static regions. Particles are transferred by the spouting action to form a conical heap with the carbonaceous granules concentrated at the top. The hot burner gases ignite the carbonaceous matter on the top of the bed which becomes distributed in the bed by the spouting action and bed movement. Thereafter the rate of air introduction is increased to fluidize the entire bed, the spouter/burner is shut off, and the entire fluidized bed is ignited.

  5. Ignition transient analysis of solid rocket motor

    Science.gov (United States)

    Han, Samuel S.

    1991-01-01

    Measurement data on the performance of Space Shuttle Solid Rocket Motor show wide variations in the head-end pressure changes and the total thrust build-up during the ignition transient periods. To analyze the flow and thermal behavior in the tested solid rocket motors, a 1-dimensional, ideal gas flow model via the SIMPLE algorithm was developed. Numerical results showed that burning patterns in the star-shaped head-end segment of the propellant and the erosive burning rate are two important factors controlling the ignition transients. The objective of this study is to extend the model to include the effects of aluminum particle commonly used in solid propellants. To treat the effects of aluminum-oxide particles in the combustion gas, conservation of mass, momentum, and energy equations for the particles are added in the numerical formulation and integrated by an inter-phase-slip algorithm.

  6. Ignitability and explosibility of gases and vapors

    CERN Document Server

    Ma, Tingguang

    2015-01-01

    The book provides a systematic view on flammability and a collection of solved engineering problems in the fields of dilution and purge, mine gas safety, clean burning safety and gas suppression modeling. For the first time, fundamental principles of energy conservation are used to develop theoretical flammability diagrams and are then explored to understand various safety-related mixing problems. This provides the basis for a fully-analytical solution to any flammability problem. Instead of the traditional view that flammability is a fundamental material property, here flammability is discovered to be a result of the explosibility of air and the ignitability of fuel, or a process property. By exploring the more fundamental concepts of explosibility and ignitability, the safety targets of dilution and purge can be better defined and utilized for guiding safe operations in process safety. This book provides various engineering approaches to mixture flammability, benefiting not only the safety students, but al...

  7. National Ignition Facility design, performance, and cost

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, W.J.; Paisner, J.A.; Lowdermilk, W.H. [and others

    1994-09-16

    A conceptual design for the National Ignition Facility (NIF) has been completed and its cost has been estimated by a multilaboratory team. To maximize the performance/cost ratio a compact, segmented amplifier is used in a multipass architecture. Many recent optical and laser technology developments have been incorporated into the final design. The Beamlet project has successfully demonstrated the new concept. The mission of ICF Program using the NEF is to achieve ignition and gain in the laboratory. The facility will be used for defense applications such as weapons physics and weapons effects experiments, and for civilian applications such as inertial fusion energy development and fundamental studies of matter at high energy density.

  8. Conceptual Design - Polar Drive Ignition Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, R

    2012-04-05

    The Laboratory for Laser Energetics (LLE) at the University of Rochester is proposing a collaborative effort with Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratories (LANL), the Naval Research Laboratory (NRL), and General Atomics (GA) with the goal of developing a cryogenic polar drive (PD) ignition platform on the National Ignition Facility (NIF). The scope of this proposed project requires close discourse among theorists, experimentalists, and laser and system engineers. This document describes how this proposed project can be broken into a series of parallel independent activities that, if implemented, could deliver this goal in the 2017 timeframe. This Conceptual Design document is arranged into two sections: mission need and design requirements. Design requirements are divided into four subsystems: (1) A point design that details the necessary target specifications and laser pulse requirements; (2) The beam smoothing subsystem that describes the MultiFM 1D smoothing by spectral dispersion (SSD); (3) New optical elements that include continuous phase plates (CPP's) and distributed polarization rotators (DPR's); and (4) The cryogenic target handling and insertion subsystem, which includes the design, fabrication, testing, and deployment of a dedicated PD ignition target insertion cryostat (PD-ITIC). This document includes appendices covering: the primary criteria and functional requirements, the system design requirements, the work breakdown structure, the target point design, the experimental implementation plan, the theoretical unknowns and technical implementation risks, the estimated cost and schedule, the development plan for the DPR's, the development plan for MultiFM 1D SSD, and a list of acronym definitions. While work on the facility modifications required for PD ignition has been in progress for some time, some of the technical details required to define the specific modifications for a Conceptual Design

  9. Control of Ignition and Combustion of Dimethyl Ether in Homogeneous Charge Compression Ignition Engine

    Science.gov (United States)

    Kim, Kyoung-Oh; Azetsu, Akihiko; Oikawa, Chikashi

    A homogeneous charge compression ignition (HCCI) engine is known to have high thermal efficiency and low nitrogen oxide emission. However, the control of ignition timing and its combustion period over a wide range of engine speeds and loads is one of the barriers to the realization of the engine. On the lean side of the equivalence ratio, control of ignition is difficult due to its long delay of ignition, and there is knocklike problem under high load. In both computations and experiments of HCCI engine operated on dimethyl ether, the operable range (the possible range of fuel input from just ignitable to knock-occurring state) shifted to the rich side with decreasing intake temperature and amount of mixing of carbon dioxide. The range of fuel input was reduced at low intake temperatures, because the hot flame onset angle advanced more quickly than it did at high intake temperatures. However, the mixing of CO2 caused the operable range to shift to the rich side while retaining the same range. The results of this study indicated the possibility of high-load operation or extension of the load range by exhaust gas recirculation.

  10. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    Energy Technology Data Exchange (ETDEWEB)

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  11. The Velocity Campaign for Ignition on NIF

    Science.gov (United States)

    Callahan, Debra

    2011-10-01

    Achieving ignition requires a high velocity implosion since the energy required for ignition scales like 1/v8. Beyond ignition, a higher velocity produces more robust performance, which will be useful for applications of ignition. In the velocity campaign, we will explore three methods for increasing implosion velocity: increased laser power and energy, optimized hohlraum and capsule materials, and optimized capsule thickness. The main issue with increasing the laser power and energy is the way in which LPI (laser plasma interactions) and hot electron preheat will change as we increase the laser power. Based on scalings from previous data and theory, we expect to couple 80-85% of 1.5 MJ at 475-500 TW. We can also increase the velocity by optimizing the hohlraum and capsule materials. In this campaign, we will explore depleted uranium hohlraums to reduce wall loss and optimize the capsule dopant by replacing the germanium dopant with silicon. Those two changes are expected to increase velocity by 6-7%. Finally, we will optimize the capsule thickness. The optimal capsule thickness is a trade-off between velocity and mix. A thinner capsule has higher velocity, but is more susceptible to mix of the ablator material into the hotspot due to hydrodynamic instabilities seeded by ablation surface imperfections. Once we have achieved adequate capsule areal density, we will optimize the velocity/mix trade off by varying the capsule thickness. We will also make direct measure of Rayleigh-Taylor instability growth by backlighting the growth of engineered features on the surface of the capsule. This will allow us to benchmark our models of mix. In this paper, we will describe the designs and experimental results of the velocity campaign. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  12. The National Ignition Campaign: status and progress

    Science.gov (United States)

    Moses, E. I.; Collaborators, the NIC

    2013-10-01

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) has been operational since March 2009 and a variety of experiments have been completed and many more are planned in support of NIF's mission areas: national security, fundamental science, and fusion energy. NIF capabilities and infrastructure are in place to support all of its missions with nearly 60 x-ray, optical and nuclear diagnostic systems and the ability to shoot cryogenic targets and DT layered capsules. The NIF has also been qualified for the use of tritium and other special materials as well as to perform high-yield experiments and classified experiments. Implosions with record indirect-drive neutron yield of 7.5 × 1014 neutrons have been achieved. NIF, a Nd : Glass laser facility, is routinely operating at 1.6 MJ of ultraviolet (3ω) light on target with very high reliability. It recently reached its design goal of 1.8 MJ and 500 TW of 3ω light on target, and has performed target experiments with 1.9 MJ at peak powers of 410 TW. The National Ignition Campaign (NIC), an international effort with the goal of demonstrating thermonuclear burn in the laboratory, is making steady progress towards achieving ignition. Other experiments have been completed in support of high-energy science, materials equation of state, and materials strength. In all cases, records of extreme temperatures and pressures, highest neutron yield and highest energy densities have been achieved. This paper describes the unprecedented experimental capabilities of the NIF and the results achieved so far on the path towards ignition.

  13. Ignition threshold for non-Maxwellian plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hay, Michael J., E-mail: hay@princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Fisch, Nathaniel J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2015-11-15

    An optically thin p-{sup 11}B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for the potential utility of a nonthermal distribution, we consider a monoenergetic beam with particle energy selected to maximize the beam-thermal reactivity. Comparing deuterium-tritium (DT) and p-{sup 11}B, the minimum Lawson criteria and minimum ρR required for inertial confinement fusion (ICF) volume ignition are calculated with and without the nonthermal feature. It turns out that channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and ρR, improves reactivity at constant pressure, and could be used to remove helium ash. On the other hand, the reactivity gains that could be realized in DT plasmas are significant, the excess electron density in p-{sup 11}B plasmas increases the recirculated power cost to maintain a nonthermal feature and thereby constrains its utility to ash removal.

  14. Fielding the NIF Cryogenic Ignition Target

    Energy Technology Data Exchange (ETDEWEB)

    Malsbury, T; Haid, B; Gibson, C; Atkinson, D; Skulina, K; Klingmann, J; Atherton, J; Mapoles, E; Kozioziemski, B; Dzenitis, E

    2008-02-28

    The United States Department of Energy has embarked on a campaign to conduct credible fusion ignition experiments on the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in 2010. The target assembly specified for this campaign requires the formation of a deuterium/tritium (DT) fuel ice layer on the inside of a 2 millimeter diameter capsule positioned at the center of a 9 millimeter long by 5 millimeter diameter cylinder, called a hohlraum. The ice layer requires micrometer level accuracy and must be formed and maintained at temperatures below 19 K. At NIF shot time, the target must be positioned at the center of the NIF 10 meter diameter target chamber, aligned to the laser beam lines and held stable to less than 7 micrometers rms. We have completed the final design and are integrating the systems necessary to create, characterize and field the cryogenic target for ignition experiments. These designs, with emphasis on the challenges of fielding a precision cryogenic positioning system will be presented.

  15. Laser spark distribution and ignition system

    Science.gov (United States)

    Woodruff, Steven; McIntyre, Dustin L.

    2008-09-02

    A laser spark distribution and ignition system that reduces the high power optical requirements for use in a laser ignition and distribution system allowing for the use of optical fibers for delivering the low peak energy pumping pulses to a laser amplifier or laser oscillator. An optical distributor distributes and delivers optical pumping energy from an optical pumping source to multiple combustion chambers incorporating laser oscillators or laser amplifiers for inducing a laser spark within a combustion chamber. The optical distributor preferably includes a single rotating mirror or lens which deflects the optical pumping energy from the axis of rotation and into a plurality of distinct optical fibers each connected to a respective laser media or amplifier coupled to an associated combustion chamber. The laser spark generators preferably produce a high peak power laser spark, from a single low power pulse. The laser spark distribution and ignition system has application in natural gas fueled reciprocating engines, turbine combustors, explosives and laser induced breakdown spectroscopy diagnostic sensors.

  16. The National Ignition Facility Performance Status

    Energy Technology Data Exchange (ETDEWEB)

    Haynam, C; Auerbach, J; Nicola, J D; Dixit, S; Heestand, G; Henesian, M; Jancaitis, K; Manes, K; Marshall, C; Mehta, N; Nostrand, M; Orth, C; Sacks, R; Shaw, M; Sutton, S; Wegner, P; Williams, W; Widmayer, C; White, R; Yang, S; Van Wonterghem, B

    2005-08-30

    The National Ignition Facility (NIF) laser has been designed to support high energy density science (HEDS), including the demonstration of fusion ignition through Inertial Confinement. NIF operated a single ''quad'' of 4 beams from December 2002 through October 2004 in order to gain laser operations experience, support target experiments, and demonstrate laser performance consistent with NIF's design requirement. During this two-year period, over 400 Main Laser shots were delivered at 1{omega} to calorimeters for diagnostic calibration purposes, at 3{omega} to the Target Chamber, and at 1{omega}, 2{omega}, and 3{omega} to the Precision Diagnostics System (PDS). The PDS includes its own independent single beam transport system, NIF design frequency conversion hardware and optics, and laser sampling optics that deliver light to a broad range of laser diagnostics. Highlights of NIF laser performance will be discussed including the results of high energy 2{omega} and 3{omega} experiments, the use of multiple focal spot beam conditioning techniques, the reproducibility of laser performance on multiple shots, the generation on a single beam of a 3{omega} temporally shaped ignition pulse at full energy and power, and recent results on full bundle (8 beamline) performance. NIF's first quad laser performance meets or exceeds NIF's design requirements.

  17. The national ignition facility performance status

    Energy Technology Data Exchange (ETDEWEB)

    Haynam, C.; Auerbach, J.; Bowers, M.; Di-Nicola, J.M.; Dixit, S.; Erbert, G.; Heestand, G.; Henesian, M.; Jancaitis, K.; Manes, K.; Marshall, C.; Mehta, N.; Nostrand, M.; Orth, C.; Sacks, R.; Shaw, M.; Sutton, S.; Wegner, P.; Williams, W.; Widmayer, C.; White, R.; Yang, S.; Van Wonterghem, B. [Lawrence Livermore National Laboratory, Livermore, CA (United States)

    2006-06-15

    The National Ignition Facility (NIF) laser has been designed to support high energy density science, including the demonstration of fusion ignition through Inertial Confinement. NIF operated a single 'quad' of 4 beams from December 2002 through October 2004 in order to gain laser operations experience, support target experiments, and demonstrate laser performance consistent with NIF's design requirement. During this two-year period, over 400 Main Laser shots were delivered at 1{omega} to calorimeters for diagnostic calibration purposes, at 3{omega} to the Target Chamber, and at 1{omega}, 2{omega}, and 3{omega} to the precision diagnostic system (PDS). The PDS includes its own independent single beam transport system, NIF design frequency conversion hardware and optics, and laser sampling optics that deliver light to a broad range of laser diagnostics. Highlights of NIF laser performance will be discussed including the results of high energy 2{omega} and 3{omega} experiments, the use of multiple focal spot beam conditioning techniques, the reproducibility of laser performance on multiple shots, the generation on a single beam of a 3{omega} temporally shaped ignition pulse at full energy and power, and recent results on full bundle (8 beamline) performance. NIF's first quad laser performance meets or exceeds NIF's design requirements. (authors)

  18. Third O2 addition reactions promote the low-temperature auto-ignition of n-alkanes

    KAUST Repository

    Wang, Zhandong

    2016-01-20

    Comprehensive low-temperature oxidation mechanisms are needed to accurately predict fuel auto-ignition properties. This paper studies the effects of a previously unconsidered third O2 addition reaction scheme on the simulated auto-ignition of n-alkanes. We demonstrate that this extended low-temperature oxidation scheme has a minor effect on the simulation of n-pentane ignition; however, its addition significantly improves the prediction of n-hexane auto-ignition under low-temperature rapid compression machine conditions. Additional simulations of n-hexane in a homogeneous charge compression ignition engine show that engine-operating parameters (e.g., intake temperature and combustion phasing) are significantly altered when the third O2 addition kinetic mechanism is considered. The advanced combustion phasing is initiated by the formation and destruction of additional radical chain-branching intermediates produced in the third O2 addition process, e.g. keto-dihydroperoxides and/or keto-hydroperoxy cyclic ethers. Our results indicate that third O2 addition reactions accelerate low-temperature radical chain branching at conditions of relevance to advance engine technologies, and therefore these chemical pathways should also be considered for n-alkanes with 6 or more carbon atoms. © 2015 The Combustion Institute.

  19. Localized flame extinction and re-ignition in turbulent jet ignition assisted combustion

    Science.gov (United States)

    Validi, Abdoulahad; Schock, Harold; Jaberi, Farhad; Computational Fluid Dynamics Laboratory Team

    2016-11-01

    Direct numerical simulations (DNS) of turbulent jet ignition (TJI)-assisted combustion of ultra-lean fuel-air is performed in a three-dimensional planar jet configuration. TJI is a novel ignition enhancement method which facilitates the combustion of lean and ultra-lean mixtures by rapidly exposing them to high temperature combustion products. Fully compressible gas dynamics and species equations are solved with high order finite difference methods. The hydrogen-air reaction is simulated with a detailed chemical kinetics mechanism consisting of 9 species and 38 elementary reactions. The interesting phenomena involved in TJI combustion including localized premixed flame extinction/re-ignition and simultaneous premixed/non-premixed flames are investigated by using the flame heat release, temperature, species concentrations, and a newly defined TJI progress variable.

  20. Ignitor with stable low-energy thermite igniting system

    Science.gov (United States)

    Kelly, Michael D.; Munger, Alan C.

    1991-02-05

    A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

  1. Some Observations on the Ignition of Composite Solid Propellants

    Directory of Open Access Journals (Sweden)

    K. Kishore

    1995-07-01

    Full Text Available Heat-up times derived from studies on the ignition characteristics of a few model composite solid propellants, containing polystyrene, carboxy-terminated polybutadiene, plasticised polyvinyl chloride and polyphenol formaldehyde as binders, show that they are directly proportional to the mass of the sample and inversely proportional to the heat flux. Propellant weight-loss prior to ignition and high pressure ignition temperature data on the propellants, ammonium per chlorate, and binders show that the ignition is governed by the gasification of the binder pyrolysis products. The activation energy for the gasification of the pyrolysed polymer products corresponds to their ignition behaviour suggesting that propellant ignition is controlled by the binder.

  2. Laser diode ignition activities at Sandia National Laboratories

    Science.gov (United States)

    Merson, John A.; Salas, F. Jim; Chow, Weng W.; Clements, J. W.; Kass, William J.

    1993-01-01

    The topics are presented in viewgraph form and include the following: ignition subsystems, enhanced safety, optical ordnance power densities, optical ignition factors, low energy optical ordnance program, absorptance of 2-(5-cyanotetrazolato) pentaaminecobalt(III) perchlorate (CP) near 800 nm, power dependence of doped CP, system operational electrical requirements, dopant concentration effects for different CP particle sizes, ZR/KCLO4 optical ignition thresholds, and electrostatic discharge testing.

  3. Schlieren Imaging and Pulsed Detonation Engine Testing of Ignition by a Nanosecond Repetitively Pulsed Discharge

    Science.gov (United States)

    2016-05-16

    effect of the plasma is to produce active species, which quench to produce O atoms and release heat. The O atoms go on to initiate the fuel oxidation ...strong effect on ignition time for mixtures with MIE larger than the individual pulse energy. Stoichiometric ethylene –air has an MIE of 0.096 mJ... ethylene is so fast with just a single pulse, the effect of additional pulses is not noticeable on the time scale of the present experiments. In addition

  4. Image processing for the Advanced Radiographic Capability (ARC) at the National Ignition Facility

    Science.gov (United States)

    Leach, Richard R.; Awwal, Abdul A. S.; Lowe-Webb, Roger; Miller-Kamm, Victoria; Orth, Charles; Roberts, Randy; Wilhelmsen, Karl

    2016-09-01

    The Advance Radiographic Capability (ARC) at the National Ignition Facility (NIF) is a laser system that employs up to four petawatt (PW) lasers to produce a sequence of short-pulse kilo-Joule laser pulses with controllable delays that generate X-rays to provide backlighting for high-density internal confinement fusion (ICF) capsule targets. Multi-frame, hard-X-ray radiography of imploding NIF capsules is a capability which is critical to the success of NIF's missions. ARC is designed to employ up to eight backlighters with tens-of-picosecond temporal resolution, to record the dynamics and produce an X-ray "motion picture" of the compression and ignition of cryogenic deuterium-tritium targets. ARC will generate tens-of-picosecond temporal resolution during the critical phases of ICF shots. Additionally, ARC supports a variety of other high energy density experiments including fast ignition studies on NIF. The automated alignment image analysis algorithms use digital camera sensor images to direct ARC beams onto the tens-of-microns scale metal wires. This paper describes the ARC automatic alignment sequence throughout the laser chain from pulse initiation to target with an emphasis on the image processing algorithms that generate the crucial alignment positions for ARC. The image processing descriptions and flow diagrams detail the alignment control loops throughout the ARC laser chain beginning in the ARC high-contrast front end (HCAFE), on into the ARC main laser area, and ending in the ARC target area.

  5. EFFICIENCY ANALYSIS OF GAS ENGINES MONOSPARK AND MULTISPARK IGNITION SYSTEMS

    Directory of Open Access Journals (Sweden)

    F. Abramchuk

    2014-02-01

    Full Text Available The results of comparison analysis of gas engine monospark and multispark ignition systems indices are presented. The results of these systems experimental investigation are given.

  6. Review on performance of High energy ignition techniques

    Directory of Open Access Journals (Sweden)

    Jubin V Jose

    2015-12-01

    Full Text Available Ignition systems are the fundamental parts of spark ignition engines which determine the engine efficiency and pollutant emission. With the recent developments in engine technology significantly high spark energies are required. This paper reviews progress in alternative ignition systems that supply high energy sparks and more efficiently transfer energy to the gas mixture. The improvement in performance parameter of a spark plug such as net heat transfer rate, flame development time, exhaust gas emission rate are compared with conventional ignition systems. This paper also tries to identify critical research gap and also the advantages and limitations of advanced systems with reference to the advanced researches reported in this area.

  7. Thermal-Catalytic Ignition Source for Ionic Liquid Monopropellants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Ultramet recently demonstrated rapid, reliable, and repeated ignition of hydroxylammonium nitrate (HAN)-hydroxyethylhydrazinium nitrate (HEHN) monopropellant...

  8. Highly Durable Catalysts for Ignition of Advanced Monopropellants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed SBIR Phase I addresses the development of catalysts and technology for the ignition of advanced monopropellants consisting of mixtures of...

  9. Review of the National Ignition Campaign 2009-2012

    Science.gov (United States)

    Lindl, John; Landen, Otto; Edwards, John; Moses, Ed

    2014-02-01

    The National Ignition Campaign (NIC) was a multi-institution effort established under the National Nuclear Security Administration of DOE in 2005, prior to the completion of the National Ignition Facility (NIF) in 2009. The scope of the NIC was the planning and preparation for and the execution of the first 3 yr of ignition experiments (through the end of September 2012) as well as the development, fielding, qualification, and integration of the wide range of capabilities required for ignition. Besides the operation and optimization of the use of NIF, these capabilities included over 50 optical, x-ray, and nuclear diagnostic systems, target fabrication facilities, experimental platforms, and a wide range of NIF facility infrastructure. The goal of ignition experiments on the NIF is to achieve, for the first time, ignition and thermonuclear burn in the laboratory via inertial confinement fusion and to develop a platform for ignition and high energy density applications on the NIF. The goal of the NIC was to develop and integrate all of the capabilities required for a precision ignition campaign and, if possible, to demonstrate ignition and gain by the end of FY12. The goal of achieving ignition can be divided into three main challenges. The first challenge is defining specifications for the target, laser, and diagnostics with the understanding that not all ignition physics is fully understood and not all material properties are known. The second challenge is designing experiments to systematically remove these uncertainties. The third challenge is translating these experimental results into metrics designed to determine how well the experimental implosions have performed relative to expectations and requirements and to advance those metrics toward the conditions required for ignition. This paper summarizes the approach taken to address these challenges, along with the progress achieved to date and the challenges that remain. At project completion in 2009, NIF lacked

  10. Development of a simulation model for compression ignition engine running with ignition improved blend

    Directory of Open Access Journals (Sweden)

    Sudeshkumar Ponnusamy Moranahalli

    2011-01-01

    Full Text Available Department of Automobile Engineering, Anna University, Chennai, India. The present work describes the thermodynamic and heat transfer models used in a computer program which simulates the diesel fuel and ignition improver blend to predict the combustion and emission characteristics of a direct injection compression ignition engine fuelled with ignition improver blend using classical two zone approach. One zone consists of pure air called non burning zone and other zone consist of fuel and combustion products called burning zone. First law of thermodynamics and state equations are applied in each of the two zones to yield cylinder temperatures and cylinder pressure histories. Using the two zone combustion model the combustion parameters and the chemical equilibrium composition were determined. To validate the model an experimental investigation has been conducted on a single cylinder direct injection diesel engine fuelled with 12% by volume of 2- ethoxy ethanol blend with diesel fuel. Addition of ignition improver blend to diesel fuel decreases the exhaust smoke and increases the thermal efficiency for the power outputs. It was observed that there is a good agreement between simulated and experimental results and the proposed model requires low computational time for a complete run.

  11. Sensitivity of Liquid Monopropellants to Compression Ignition

    Science.gov (United States)

    1982-06-01

    contains a Silicon Rubber Septum through which a Gas Ullage Syringe,i.e., hypodermic needle , passes to introduce a precise loading of air ullage (volume...dumbbell by use of a hypodermic needle during the pre-fill procedure. Both head and rear of the dumbbell are fitted with "O"-ring seals. Thus, should...ignition tests support this theory . Again, returning to Figure 29, the response of a rapid-load pre-pressurized NOS-365 liquid monopropellant nharge (p

  12. Ignition and combustion features of biofuels

    Science.gov (United States)

    Ryzhkov, A. F.; Silin, V. E.; Bogatova, T. F.; Nadir, S. M.

    2011-07-01

    This paper presents the results of experimental investigations of the ignition and combustion of plant biofuels (wood particles, date stones) and products of their mechanical and thermal treatment (pellets, charcoal) at temperatures typical of the burning process in nonforced furnaces and fixed-bed and fluidized-bed gas producers. The influence of the furnace heat treatment of a fuel on its inflammation and combustion has been revealed. The results have been compared with the known data on the burning of pellets, brown coals, and anthracites and with the calculation by the classical diffusion-kinetic model.

  13. Low emissions compression ignited engine technology

    Science.gov (United States)

    Coleman, Gerald N.; Kilkenny, Jonathan P.; Fluga, Eric C.; Duffy, Kevin P.

    2007-04-03

    A method and apparatus for operating a compression ignition engine having a cylinder wall, a piston, and a head defining a combustion chamber. The method and apparatus includes delivering fuel substantially uniformly into the combustion chamber, the fuel being dispersed throughout the combustion chamber and spaced from the cylinder wall, delivering an oxidant into the combustion chamber sufficient to support combustion at a first predetermined combustion duration, and delivering a diluent into the combustion chamber sufficient to change the first predetermined combustion duration to a second predetermined combustion duration different from the first predetermined combustion duration.

  14. Ignition analysis of a porous energetic material. 2. Ignition at a closed heated end

    Energy Technology Data Exchange (ETDEWEB)

    Alexander M. Telegentor; Stephen B. Margolis; Forman A. Williams

    1998-11-01

    A continuation of an ignition analysis for porous energetic materials subjected to a constant energy flux is presented. In the first part, the analysis was developed for the case of an open-end, semi-infinite material such that gas flow, generated by thermal expansion, flowed out of the porous solid, thereby removing energy from the system. In the present study, the case of a closed end is considered, and thus the thermally-induced gas flow is now directed into the solid. In these studies, an asymptotic perturbation analysis, based on the smallness of the gas-to-solid density ratio and the largeness of the activation energy, is utilized to describe the inert and transition stages leading to thermal runaway. In both cases it is found that the effects of porosity provide a leading-order reduction in the time to ignition relative to that for the nonporous problem, arising from the reduced amount of solid material that must be heated and the difference in thermal conductivities of the solid and gaseous phases. A correction to the leading-order ignition-delay time, however, is provided by the convective flow of gas through the solid, and the sign of this correction is shown to depend on the direction of the gas flow. Thus, gas flowing out of an open-end solid was previously shown to give a positive correction to the leading-order time to ignition. Here, however, it is demonstrated that when the flow of gas is directed into the porous solid, the relative transport effects associated with the gas flow serve to preheat the material, resulting in a negative correction and hence a decrease in the ignition-delay time.

  15. High-pressure ignition plasma torch for aerospace testing facilities

    Science.gov (United States)

    Yusupov, D. I.; Kulikov, Yu M.; Gadzhiev, M. Kh; Tyuftyaev, A. S.; Son, E. E.

    2016-11-01

    The present paper discusses the issues of implementation of high-pressure ignition plasma torch in terms of discharge phenomena in compressed gases, dense nitrogen plasma properties and stable arcing power requirements. Contact ignition has been tested in a pressure range p = 1-25 bar and has proved to be a reliable solution for pilot arc burning.

  16. Estimating soil organic carbon through loss on ignition

    NARCIS (Netherlands)

    Hoogsteen, M.J.J.; Lantinga, E.A.; Bakker, E.J.; Groot, J.C.J.; Tittonell, P.A.

    2015-01-01

    Loss on ignition (LOI) is one of the most widely used methods for measuring organic matter content in soils but does not have a universal standard protocol. A large number of factors may influence its accuracy, such as furnace type, sample mass, duration and temperature of ignition and clay conte

  17. Boron Particle Ignition in Secondary Chamber of Ducted Rocket

    Directory of Open Access Journals (Sweden)

    J. X. Hu

    2012-01-01

    Full Text Available In the secondary chamber of ducted rocket, there exists a relative speed between boron particles and air stream. Hence, the ignition laws under static conditions cannot be simply applied to represent the actual ignition process of boron particles, and it is required to study the effect of forced convective on the ignition of boron particles. Preheating of boron particles in gas generator makes it possible to utilize the velocity difference between gas and particles in secondary chamber for removal of the liquid oxide layer with the aid of Stoke's forces. An ignition model of boron particles is formulated for the oxide layer removal by considering that it results from a boundary layer stripping mechanism. The shearing action exerted by the high-speed flow causes a boundary layer to be formed in the surface of the liquid oxide layer, and the stripping away of this layer accounts for the accelerated ignition of boron particles. Compared with the King model, as the ignition model of boron particles is formulated for the oxide layer removal by considering that it results from a boundary layer stripping mechanism, the oxide layer thickness thins at all times during the particle ignition and lower the ignition time.

  18. Hot-wire ignition of AN-based emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Turcotte, Richard; Goldthorp, Sandra; Badeen, Christopher M. [Canadian Explosives Research Laboratory, Natural Resources Canada, Ottawa, Ontario, K1A 0G1 (Canada); Chan, Sek Kwan [Orica Canada Inc., Brownsburg-Chatham, Quebec (Canada)

    2008-12-15

    Emulsions based on ammonium nitrate (AN) and water locally ignited by a heat source do not undergo sustained combustion when the pressure is lower than some threshold value usually called the Minimum Burning Pressure (MBP). This concept is now being used by some manufacturers as a basis of safety. However, before a technique to reliably measure MBP values can be designed, one must have a better understanding of the ignition mechanism. Clearly, this is required to avoid under ignitions which could lead to the erroneous interpretation of failures to ignite as failures to propagate. In the present work, facilities to prepare and characterize emulsions were implemented at the Canadian Explosives Research Laboratory. A calibrated hot-wire ignition system operated in a high-pressure vessel was also built. The system was used to study the ignition characteristics of five emulsion formulations as a function of pressure and ignition source current. It was found that these mixtures exhibit complicated pre-ignition stages and that the appearance of endotherms when the pressure is lowered below some threshold value correlates with the MBP. Thermal conductivity measurements using this hot-wire system are also reported. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  19. 16 CFR Figure 6 to Part 1610 - Igniter

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Igniter 6 Figure 6 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 6 Figure 6 to Part 1610—Igniter ER20OC08.001...

  20. 49 CFR 392.50 - Ignition of fuel; prevention.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Ignition of fuel; prevention. 392.50 Section 392.50 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER... COMMERCIAL MOTOR VEHICLES Fueling Precautions § 392.50 Ignition of fuel; prevention. No driver or...

  1. 33 CFR 159.129 - Safety: Ignition prevention test.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety: Ignition prevention test... prevention test. (a) Components of a device that are a potential ignition source in an explosive atmosphere... locations (46 CFR 111.80-5(a)) need not be subjected to this testing....

  2. Study on the ignition process of a segmented plasma torch

    Science.gov (United States)

    Cao, Xiuquan; Yu, Deping; Xiang, Yong; Li, Chao; Jiang, Hui; Yao, Jin

    2017-07-01

    Direct current plasma torches have been applied to generate unique sources of thermal energy in many industrial applications. Nevertheless, the successful ignition of a plasma torch is the key process to generate the unique source (plasma jet). However, there has been little study on the underlying mechanism of this key process. A thorough understanding of the ignition process of a plasma torch will be helpful for optimizing the design of the plasma torch structure and selection of the ignition parameters to prolong the service life of the ignition module. Thus, in this paper, the ignition process of a segmented plasma torch (SPT) is theoretically and experimentally modeled and analyzed. Corresponding electrical models of different stages of the ignition process are set up and used to derive the electrical parameters, e.g. the variations of the arc voltage and arc current between the cathode and anode. In addition, the experiments with different ignition parameters on a home-made SPT have been conducted. At the same time, the variations of the arc voltage and arc current have been measured, and used to verify the ones derived in theory and to determine the optimal ignition parameters for a particular SPT.

  3. 33 CFR 183.440 - Secondary circuits of ignition systems.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Secondary circuits of ignition systems. 183.440 Section 183.440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Requirements § 183.440 Secondary circuits of ignition systems. (a) Each conductor in a secondary circuit of...

  4. PBXN-9 Ignition Kinetics and Deflagration Rates

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, E; Maienschein, J; Burnham, A; Koerner, J; Hsu, P; Wemhoff, A

    2008-04-24

    The ignition kinetics and deflagration rates of PBXN-9 were measured using specially designed instruments at LLNL and compared with previous work on similar HMX based materials. Ignition kinetics were measured based on the One Dimensional Time-to-Explosion combined with ALE3D modeling. Results of these experiments indicate that PBXN-9 behaves much like other HMX based materials (i.e. LX-04, LX-07, LX-10 and PBX-9501) and the dominant factor in these experiments is the type of explosive, not the type of binder/plasticizer. In contrast, the deflagration behavior of PBXN-9 is quite different from similar high weight percent HMX based materials (i.e LX-10, LX-07 and PBX-9501). PBXN-9 burns in a laminar manner over the full pressure range studied (0-310 MPa) unlike LX-10, LX-07, and PBX-9501. The difference in deflagration behavior is attributed to the nature of the binder/plasticizer alone or in conjunction with the volume of binder present in PBXN-9.

  5. Initial assessments of ignition spherical torus

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Y.K.M.; Borowski, S.K.; Bussell, G.T.; Dalton, G.R.; Gorker, G.E.; Haines, J.R.; Hamilton, W.R.; Kalsi, S.S.; Lee, V.D.; Miller, J.B.

    1985-12-01

    Initial assessments of ignition spherical tori suggest that they can be highly cost effective and exceptionally small in unit size. Assuming advanced methods of current drive to ramp up the plasma current (e.g., via lower hybrid wave at modest plasma densities and temperatures), the inductive solenoid can largely be eliminated. Given the uncertainties in plasma energy confinement times and the effects of strong paramagnetism on plasma pressure, and allowing for the possible use of high-strength copper alloys (e.g., C-17510, Cu-Ni-Be alloy), ignition spherical tori with a 50-s burn are estimated to have major radii ranging from 1.0 to 1.6 m, aspect ratios from 1.4 to 1.7, vacuum toroidal fields from 2 to 3 T, plasma currents from 10 to 19 MA, and fusion power from 50 to 300 MW. Because of its modest field strength and simple poloidal field coil configuration, only conventional engineering approaches are needed in the design. A free-standing toroidal field coil/vacuum vessel structure is assessed to be feasible and relatively independent of the shield structure and the poloidal field coils. This exceptionally simple configuration depends significantly, however, on practical fabrication approaches of the center conductor post, about which there is presently little experience. 19 refs.

  6. National Ignition Facility project acquisition plan

    Energy Technology Data Exchange (ETDEWEB)

    Callaghan, R.W.

    1996-04-01

    The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility (NIF) Project. The scope of the plan describes the procurement activities and acquisition strategy for the following phases of the NIF Project, each of which receives either plant and capital equipment (PACE) or other project cost (OPC) funds: Title 1 and 2 design and Title 3 engineering (PACE); Optics manufacturing facilitization and pilot production (OPC); Convention facility construction (PACE); Procurement, installation, and acceptance testing of equipment (PACE); and Start-up (OPC). Activities that are part of the base Inertial Confinement Fusion (ICF) Program are not included in this plan. The University of California (UC), operating Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory, and Lockheed-Martin, which operates Sandia National Laboratory (SNL) and the University of Rochester Laboratory for Laser Energetics (UR-LLE), will conduct the acquisition of needed products and services in support of their assigned responsibilities within the NIF Project structure in accordance with their prime contracts with the Department of Energy (DOE). LLNL, designated as the lead Laboratory, will have responsibility for all procurements required for construction, installation, activation, and startup of the NIF.

  7. Targets for the National Ignition Campaign

    Science.gov (United States)

    Atherton, L. J.

    2008-05-01

    The National Ignition Facility (NIF) is a 192 beam Nd-glass laser facility presently under construction at Lawrence Livermore National Laboratory (LLNL) for performing inertial confinement fusion (ICF) and experiments studying high energy density (HED) science. When completed in 2009, NIF will be able to produce 1.8 MJ, 500 TW of ultraviolet light for target experiments that will create conditions of extreme temperatures (>108 K), pressures (10 GBar) and matter densities (>100 g/cm3). A detailed program called the National Ignition Campaign (NIC) has been developed to enable ignition experiments in 2010, with the goal of producing fusion ignition and burn of a deuterium-tritium (DT) fuel mixture in millimeter-scale target capsules. The first of the target experiments leading up to these ignition shots will begin in 2008. The targets for the NIC are both complex and precise, and are extraordinarily demanding in materials fabrication, machining, assembly, cryogenics and characterization. The DT fuel is contained in a 2-millimeter-diameter graded copper/beryllium or CH shell. The 75-μm-thick cryogenic ice DT fuel layer is formed to sub-micron uniformity at a temperature of approximately 18 Kelvin. The capsule and its fuel layer sit at the center of a gold/depleted uranium 'cocktail' hohlraum. Researchers at LLNL have teamed with colleagues at General Atomics to lead the development of the technologies, engineering design and manufacturing infrastructure necessary to produce these demanding targets. We are also collaborating with colleagues at the Laboratory for Laser Energetics (LLE) at the University of Rochester in DT layering, and at Fraunhofer in Germany in nano-crystalline diamond as an alternate ablator to Beryllium and CH. The Beryllium capsules and cocktail hohlraums are made by physical vapor deposition onto sacrificial mandrels. These coatings must have high density (low porosity), uniform microstructure, low oxygen content and low permeability. The ablator

  8. Ignition Dynamic Parameters for Coke in Cement Calciners

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mathematical ignition model was established and researches of ignition dynamic parameters for coke in some typical coal samples from cement plants was carried out according to circumstances of coal combusted in cement plants.In order to get the ignitioin temperature Tpi of carbon particles more accurately,the temperature rising experimental method was used and the actual heating circumstances for pulverized coal in calciners(in cement plants)were also considered.With this method,the accurate determination of the ignition temperature of coke in coal was achieved,so as to get some ignition dynamic parameters.These research results provide a theoretical basis for investigating coal ignition characteristics more scientifically and more accurately.

  9. Standard Molded Composite Rocket Pyrogen Igniter - A progress report

    Science.gov (United States)

    Lucy, M. H.

    1978-01-01

    The pyrogen igniter has the function to furnish a controlled, high temperature, high pressure gas to ignite solid propellant surfaces in a rocket motor. Present pyrogens consist of numerous inert components. The Standard Molded Pyrogen Igniter (SMPI) consists of three basic parts, a cap with several integrally molded features, an ignition pellet retainer plate, and a tube with additional integrally molded features. A description is presented of an investigation which indicates that the SMPI concept is a viable approach to the design and manufacture of pyrogen igniters for solid propellant rocket motors. For some applications, combining the structural and thermal properties of molded composites can result in the manufacture of lighter assemblies at considerable cost reduction. It is demonstrated that high strength, thin walled tubes with high length to diameter ratios can be fabricated from reinforced plastic molding compound using the displacement compression process.

  10. Laser Ignition of pyrotechnics - effects of wavelength, composition and confinement

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Sheikh Rafi; Russell, David Anthony [Department of Environmental and Ordnance Systems, Cranfield University, Royal Military College of Science, Shrivenham, Swindon, Wiltshire SN6 8LA (United Kingdom)

    2005-04-01

    Ignition tests were carried out using three different laser systems and three different pyrotechnic compositions. Pyrotechnic materials investigated are: sulfur/charcoal/potassium nitrate based composition (gunpowder, GP), Shellac binder-based boron/potassium nitrate composition (SR 44) and acaroid resin binder based magnesium/potassium nitrate composition (SR 371C). The laser sources were the multimode output from an Ar-ion laser ({lambda}=500 nm average), a high-power commercial diode laser ({lambda}=784 nm) and a small laser diode operating at around the same wavelength but controlled by a customized electronic circuitry. Lasers operating in the visible wavelength range provided more reproducible and quicker ignition than the infrared output from the diode lasers. It was found that unconfined gunpowder exhibits more reproducible ignition for both the visible and the infrared wavelengths compared to the other two compositions. The composition based on magnesium, SR 371C appeared to be very sensitive to laser intensity variations and gave erratic and therefore, irreproducible ignition delay times. The threshold laser energies to initiate reproducible ignition for the different wavelengths were measured and ignition maps were constructed. From these maps, the required laser power density for any value of the ignition delay time, i.e. laser energy density was determined. Tests were also conducted on gunpowder samples, partially confined in a modified pyrogen igniter capsule and a small laser diode. The diode was operated in single pulse mode using a current surge, which was much higher than the recommended value for CW operation. This provided 1 W pulses at the end of a 1 mm diameter fiber optic cable and caused reproducible ignition in the semi-confined pyrotechnic bed within the capsule. The threshold ignition energy under semi-confined conditions was found to be substantially less than that required in the unconfined environment under similar experimental

  11. Antiknock quality and ignition kinetics of 2-phenylethanol, a novel lignocellulosic octane booster

    KAUST Repository

    Shankar, Vijai

    2016-06-28

    High-octane quality fuels are important for increasing spark ignition engine efficiency, but their production comes at a substantial economic and environmental cost. The possibility of producing high anti-knock quality gasoline by blending high-octane bio-derived components with low octane naphtha streams is attractive. 2-phenyl ethanol (2-PE), is one such potential candidate that can be derived from lignin, a biomass component made of interconnected aromatic groups. We first ascertained the blending anti-knock quality of 2-PE by studying the effect of spark advancement on knock for various blends 2-PE, toluene, and ethanol with naphtha in a cooperative fuels research engine. The blending octane quality of 2-PE indicated an anti-knock behavior similar or slightly greater than that of toluene, and ethylbenzene, which could be attributed to either chemical kinetics or charge cooling effects. To isolate chemical kinetic effects, a model for 2-PE auto-ignition was developed and validated using ignition delay times measured in a high-pressure shock tube. Simulated ignition delay times of 2-PE were also compared to those of traditional high-octane gasoline blending components to show that the gas phase reactivity of 2-PE is lower than ethanol, and comparable to toluene, and ethylbenzene at RON, and MON relevant conditions. The gas-phase reactivity of 2-PE is largely controlled by its aromatic ring, while the effect of the hydroxyl group is minimal. The higher blending octane quality of 2-PE compared to toluene, and ethylbenzene can be attributed primarily to the effect of the hydroxyl group on increasing heat of vaporization. © 2016 The Combustion Institute.

  12. Shock ignition: a brief overview and progress in the design of robust targets

    Science.gov (United States)

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

    2015-01-01

    Shock ignition is a laser direct-drive inertial confinement fusion (ICF) scheme in which the stages of compression and hot spot formation are partly separated. The fuel is first imploded at a lower velocity than in conventional ICF, reducing the threats due to Rayleigh-Taylor instability. Close to stagnation, an intense laser spike drives a strong converging shock, which contributes to hot spot formation. This paper starts with a brief overview of the theoretical studies, target design and experimental results on shock ignition. The second part of the paper illustrates original work aiming at the design of robust targets and computation of the relevant gain curves. Following Chang et al (2010 Phys. Rev. Lett. 104 135002) a safety factor for high gain, ITF* (analogous to the ignition threshold factor ITF introduced by Clark et al (2008 Phys. Plasmas 15 056305)), is evaluated by means of parametric 1D simulations with artificially reduced reactivity. SI designs scaled as in Atzeni et al (2013 New J. Phys. 15 045004) are found to have nearly the same ITF*. For a given target, such ITF* increases with implosion velocity and laser spike power. A gain curve with a prescribed ITF* can then be simply generated by upscaling a reference target with that value of ITF*. An interesting option is scaling in size by reducing the implosion velocity to keep the ratio of implosion velocity to self-ignition velocity constant. At a given total laser energy, targets with higher ITF* are driven to higher implosion velocity and achieve a somewhat lower gain. However, a 1D gain higher than 100 is achieved at an (incident) energy below 1 MJ, an implosion velocity below 300 km s-1 and a peak incident power below 400 TW. 2D simulations of mispositioned targets show that targets with a higher ITF* indeed tolerate larger displacements.

  13. Polar direct drive: Proof-of-principle experiments on OMEGA and prospects for ignition on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Craxton, R.S.; Marshall, F.J.; Bonino, M.J.; Epstein, R.; McKenty, P.W.; Skupsky, S.; Delettrez, J.A.; Igumenshchev, I.V.; Jacobs-Perkins, D.W.; Knauer, J.P.; Marozas, J.A.; Radha, P.B.; Seka, W.

    2005-04-15

    Polar direct drive (PDD) shows promise for achieving direct-drive ignition while the National Ignition Facility (NIF) is initially configured for indirect drive. Experiments have been carried out using 40 repointed beams of the 60-beam OMEGA laser system to approximate the NIF PDD configuration.

  14. National Ignition Facility Shot Data Analysis Module Guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, S; Glenn, S; Lopez, A; Warrick, A; Beeler, R

    2007-10-03

    This document provides the guidelines for software development of modules to be included in Shot Data Analysis (SDA) for the National Ignition Facility (NIF). An Analysis Module is a software entity that groups a set of (typically cohesive) functions, procedures and data structures for performing an analysis task relevant to NIF shot operations. Each module must have its own unique identification (module name), clear interface specifications (data inputs and outputs), and internal documentation. It is vitally important to the NIF Program that all shot-related data be processed and analyzed in a consistent way that is reviewed by scientific and engineering experts. SDA is part of a NIF Integrated Product Team (IPT) whose goal is to provide timely and accurate reporting of shot results to NIF campaign experimentalists. Other elements of the IPT include the Campaign Management Tool (CMT) for configuring experiments, a data archive and provisioning system called CMS, a calibration and configuration database (CDMS), and a shot data visualization tool (SDV). We restrict our scope at this time to guidelines for modules written in Interactive Data Language, or IDL1. This document has sections describing example IDL modules and where to find them, how to set up a development environment, IDL programming guidelines, shared IDL procedures for general use, and revision control.

  15. CFD Simulation of Gasoline Compression Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.; Som, Sibendu

    2015-05-01

    Gasoline compression ignition (GCI) is a low temperature combustion (LTC) concept that has been gaining increasing interest over the recent years owing to its potential to achieve diesel-like thermal efficiencies with significantly reduced engine-out nitrogen oxides (NOx) and soot emissions compared to diesel engines. In this work, closed-cycle computational fluid dynamics (CFD) simulations are performed of this combustion mode using a sector mesh in an effort to understand effects of model settings on simulation results. One goal of this work is to provide recommendations for grid resolution, combustion model, chemical kinetic mechanism, and turbulence model to accurately capture experimental combustion characteristics. Grid resolutions ranging from 0.7 mm to 0.1 mm minimum cell sizes were evaluated in conjunction with both Reynolds averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) based turbulence models. Solution of chemical kinetics using the multi-zone approach is evaluated against the detailed approach of solving chemistry in every cell. The relatively small primary reference fuel (PRF) mechanism (48 species) used in this study is also evaluated against a larger 312-species gasoline mechanism. Based on these studies the following model settings are chosen keeping in mind both accuracy and computation costs – 0.175 mm minimum cell size grid, RANS turbulence model, 48-species PRF mechanism, and multi-zone chemistry solution with bin limits of 5 K in temperature and 0.05 in equivalence ratio. With these settings, the performance of the CFD model is evaluated against experimental results corresponding to a low load start of injection (SOI) timing sweep. The model is then exercised to investigate the effect of SOI on combustion phasing with constant intake valve closing (IVC) conditions and fueling over a range of SOI timings to isolate the impact of SOI on charge preparation and ignition. Simulation results indicate that there is an optimum SOI

  16. Preparing for polar-drive ignition on the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    McKenty P.W.

    2013-11-01

    Full Text Available The implementation of polar drive (PD at the National Ignition Facility (NIF will enable the execution of direct-drive implosions while the facility is configured for x-ray drive. The Laboratory for Laser Energetics (LLE, in collaboration with LLNL, LANL and GA, is implementing PD on the NIF. LLE has designed and participates in the use of PD implosions for diagnostic commissioning on the NIF. LLE has an active experimental campaign to develop PD in both warm and cryogenic target experiments on OMEGA. LLE and its partners are developing a Polar Drive Project Execution Plan, which will provide a detailed outline of the requirements, resources, and timetable leading to PD-ignition experiments on the NIF.

  17. Design and modeling of ignition targets for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Haan, S.W.; Pollaine, S.M.; Lindl, J.D.; Suter, L.J.; Berger, R.L.; Powers, L.V.; Alley, W.E.; Amendt, P.A.; Futterman, J.A.; Levedahl, W.K.; Rosen, M.D.; Rowley, D.P.; Sacks, R.A.; Shestakov, A.I.; Strobel, G.L.; Tabak, M.; Weber, S.V.; Zimmerman, G.B. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Krauser, W.J.; Wilson, D.C.; Coggeshall, S.V.; Harris, D.B.; Hoffman, N.M.; Wilde, B.H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1995-06-01

    Several targets are described that in simulations give yields of 1--30 MJ when indirectly driven by 0.9--2 MJ of 0.35 {mu}m laser light. The article describes the targets, the modeling that was used to design them, and the modeling done to set specifications for the laser system in the proposed National Ignition Facility. Capsules with beryllium or polystyrene ablators are enclosed in gold hohlraums. All the designs utilize a cryogenic fuel layer; it is very difficult to achieve ignition at this scale with a noncryogenic capsule. It is necessary to use multiple bands of illumination in the hohlraum to achieve sufficiently uniform x-ray irradiation, and to use a low-{ital Z} gas fill in the hohlraum to reduce filling of the hohlraum with gold plasma. Critical issues are hohlraum design and optimization, Rayleigh--Taylor instability modeling, and laser--plasma interactions.

  18. Enhanced surface acceleration of fast electrons by using sub-wavelength grating targets

    CERN Document Server

    Hu, Guang-yue; Wang, Wen-tao; Wang, Jing-wei; Huang, Lin-gen; Wang, Xin; Xu, Yi; Liu, Jian-sheng; Shen, Bai-fei; Yu, Wei; Li, Ru-xin; Xu, Zhi-zhan

    2010-01-01

    Surface acceleration of fast electrons in intense laser-plasma interaction is improved by using sub-wavelength grating targets. The fast electron beam emitted along the target surface was enhanced by more than three times relative to that by using planar target. The total number of the fast electrons ejected from the front side of target was also increased by about one time. The method to enhance the surface acceleration of fast electron is effective for various targets with sub-wavelength structured surface, and can be applied widely in the cone-guided fast ignition, energetic ion acceleration, plasma device, and other high energy density physics experiments.

  19. Application of Alcohols to Dual - Fuel Feeding the Spark-Ignition and Self-Ignition Engines

    Directory of Open Access Journals (Sweden)

    Stelmasiak Zdzisław

    2014-10-01

    Full Text Available This paper concerns analysis of possible use of alcohols for the feeding of self - ignition and spark-ignition engines operating in a dual- fuel mode, i.e. simultaneously combusting alcohol and diesel oil or alcohol and petrol. Issues associated with the requirements for application of bio-fuels were presented with taking into account National Index Targets, bio-ethanol production methods and dynamics of its production worldwide and in Poland. Te considerations are illustrated by results of the tests on spark- ignition and self- ignition engines fed with two fuels: petrol and methanol or diesel oil and methanol, respectively. Te tests were carried out on a 1100 MPI Fiat four- cylinder engine with multi-point injection and a prototype collector fitted with additional injectors in each cylinder. Te other tested engine was a SW 680 six- cylinder direct- injection diesel engine. Influence of a methanol addition on basic operational parameters of the engines and exhaust gas toxicity were analyzed. Te tests showed a favourable influence of methanol on combustion process of traditional fuels and on some operational parameters of engines. An addition of methanol resulted in a distinct rise of total efficiency of both types of engines at maintained output parameters (maximum power and torque. In the same time a radical drop in content of hydrocarbons and nitrogen oxides in exhaust gas was observed at high shares of methanol in feeding dose of ZI (petrol engine, and 2-3 fold lower smokiness in case of ZS (diesel engine. Among unfavourable phenomena, a rather insignificant rise of CO and NOx content for ZI engine, and THC and NOx - for ZS engine, should be numbered. It requires to carry out further research on optimum control parameters of the engines. Conclusions drawn from this work may be used for implementation of bio-fuels to feeding the combustion engines.

  20. Modelling the ignition process on the injection jet for Diesel engine combustion; Modellierung des Zuendvorgangs am Einspritzstrahl bei dieselmotorischer Verbrennung

    Energy Technology Data Exchange (ETDEWEB)

    Pitsch, H.; Mueller, U.C.; Peters, N.

    1995-12-31

    A simplified chemical model is developed to describe Diesel engine self-ignition processes. It is assumed that the ignition of Diesel fuel can be described by the single component fuel n-heptane. Starting from a detailed reaction mechanism for n-heptane with about 1000 element reactions and 168 chemical substances, a starting mechanism with 81 element reactions and 37 chemical substances is produced by a reaction flow analysis which can describe ignition processes in conditions relevant for Diesel engines. The introduction of steady state assumptions for quickly consumed intermediate species leads to a reduced mechanism with 14 global reaction steps. In order to prove the validity of these reduced mechanisms, calculated ignition delay times are compared with surge wave tube experiments for different temperatures, pressures and fuel ratios. Finally, one dimensional calculations of ignition processes in the mixing space for pressures and temperatures relevant for engines are introduced. From these, the effect of the scalar dissipation rate which describes the extent of diffusion flames on the ignition delay times, is discussed. An approximation formula for the ignition delay times as a function of the dissipation rate is derived. (orig.) [Deutsch] Zur Beschreibung dieselmotorischer Selbstzuendprozesse wird ein vereinfachtes chemisches Modell entwickelt. Dazu wird angenommen, dass die Zuendung von Dieselkraftstoffen durch den Einkomponentenkraftstoff n-Heptan beschrieben werden kann. Ausgehend von einem detaillierten Reaktionsmechanismus fuer n-Heptan mit ungefaehr 1000 Elementarreaktionen und 168 chemischen Spezies wird mittels einer Reaktionsflussanalyse ein Startmechanismus mit 81 Elementarreaktionen und 37 chemischen Spezies erstellt, der in der Lage ist, Zuendprozesse unter dieselmotorisch relevanten Bedingungen zu beschreiben. Die Einfuehrung von Stationaritaetsannahmen fuer schnell verbrauchte Zwischenspezies fuehrt auf einen reduzierten Mechanismus mit 14

  1. Status Of The National Ignition Campaign And National Ignition Facility Integrated Computer Control System

    Energy Technology Data Exchange (ETDEWEB)

    Lagin, L; Brunton, G; Carey, R; Demaret, R; Fisher, J; Fishler, B; Ludwigsen, P; Marshall, C; Reed, R; Shelton, R; Townsend, S

    2011-03-18

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility that will contains a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn. NIF is operated by the Integrated Computer Control System (ICCS) in an object-oriented, CORBA-based system distributed among over 1800 frontend processors, embedded controllers and supervisory servers. In the fall of 2010, a set of experiments began with deuterium and tritium filled targets as part of the National Ignition Campaign (NIC). At present, all 192 laser beams routinely fire to target chamber center to conduct fusion and high energy density experiments. During the past year, the control system was expanded to include automation of cryogenic target system and over 20 diagnostic systems to support fusion experiments were deployed and utilized in experiments in the past year. This talk discusses the current status of the NIC and the plan for controls and information systems to support these experiments on the path to ignition.

  2. Auto-Ignition and Heat Release Correlations for Controlled Auto-Ignition Combustion in Gasoline Engines

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Auto-ignition and heat release correlations for controlled auto-ignition (CAI) combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode. Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range. Furthermore, a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments. The heat release correlation was described in two parts, one is for the first slower heat release process at low temperature, and the other is for the second faster heat release process at high temperature. Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program. The results show that the predicted loads and ignition timings match closely with the measurements.

  3. National Ignition Facility wet weather construction plan

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, A N

    1998-01-01

    This report presents a wet weather construction plan for the National Ignition Facility (NIF) construction project. Construction of the NIF commenced in mid- 1997, and excavation of the site was completed in the fall. Preparations for placing concrete foundations began in the fall, and above normal rainfall is expected over the tinter. Heavy rainfall in late November impacted foundation construction, and a wet weather construction plan was determined to be needed. This wet weather constiction plan recommends a strategy, techniques and management practices to prepare and protect the site corn wet weather effects and allow construction work to proceed. It is intended that information in this plan be incorporated in the Stormwater Pollution Prevention Plan (SWPPP) as warranted.

  4. Electrical Arc Ignition Testing of Spacesuit Materials

    Science.gov (United States)

    Smith, Sarah; Gallus, Tim; Tapia, Susana; Ball, Elizabeth; Beeson, Harold

    2006-01-01

    A viewgraph presentation on electrical arc ignition testing of spacesuit materials is shown. The topics include: 1) Background; 2) Test Objectives; 3) Test Sample Materials; 4) Test Methods; 5) Scratch Test Objectives; 6) Cotton Scratch Test Video; 7) Scratch Test Results; 8) Entire Date Plot; 9) Closeup Data Plot; 10) Scratch Test Problems; 11) Poke Test Objectives; 12) Poke Test Results; 13) Poke Test Problems; 14) Wire-break Test Objectives; 15) Cotton Wire-Break Test Video; 16) High Speed Cotton Wire-break Test Video; 17) Typical Data Plot; 18) Closeup Data Plot; 19) Wire-break Test Results; 20) Wire-break Tests vs. Scratch Tests; 21) Urethane-coated Nylon; and 22) Moleskin.

  5. Construction Safety for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Predmore, R

    2000-09-01

    This Construction Safety Program (CSP) for the National Ignition Facility (NIF) presents safety protocols and guidelines that management and workers shall follow to assure a safe and healthful work environment. Appendix A, a separate companion document, includes further applicable environmental, safety, and health requirements for the NIF Project. Specifically this document: {sm_bullet} Defines the fundamental site safety philosophy, {sm_bullet} Identifies management roles and responsibilities, {sm_bullet} Defines core safety management processes, {sm_bullet} Identifies LLNL institutional requirements, and {sm_bullet} Defines the functional areas and facilities accrued by the program and the process for transition of facilities, functional areas, and/or systems from construction to activation. Anyone willfully or thoughtlessly disregarding standards will be subject to immediate removal from the site. Thorough job planning will help ensure that these standards are met.

  6. The Oxidation and Ignition of Jet Fuels

    Science.gov (United States)

    2017-01-03

    12 3.2.1 Three-Arrhenius model……………………………………………………. 12 3.2.2 Global reduced model……………………………………………… …….. 13 3.3. CO...oxidation. Species time- histories , on the other hand, can indicate the extent of reaction at all DISTRIBUTION A: Distribution approved for public...ignition delay times and CO time histories during fuel oxidation. The shock tube and mixing vessel can be heated up to 200 ̊ C to allow gas-phase

  7. National Ignition Facility Target Design and Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Cook, R C; Kozioziemski, B J; Nikroo, A; Wilkens, H L; Bhandarkar, S; Forsman, A C; Haan, S W; Hoppe, M L; Huang, H; Mapoles, E; Moody, J D; Sater, J D; Seugling, R M; Stephens, R B; Takagi, M; Xu, H W

    2007-12-10

    The current capsule target design for the first ignition experiments at the NIF Facility beginning in 2009 will be a copper-doped beryllium capsule, roughly 2 mm in diameter with 160-{micro}m walls. The capsule will have a 75-{micro}m layer of solid DT on the inside surface, and the capsule will driven with x-rays generated from a gold/uranium cocktail hohlraum. The design specifications are extremely rigorous, particularly with respect to interfaces, which must be very smooth to inhibit Rayleigh-Taylor instability growth. This paper outlines the current design, and focuses on the challenges and advances in capsule fabrication and characterization; hohlraum fabrication, and D-T layering and characterization.

  8. Update on ignition studies at Cea

    Energy Technology Data Exchange (ETDEWEB)

    Holstein, P.A.; Casanova, M.; Casner, A.; Cherfils, C.; Dattolo, E.; Disdier, L.; Galmiche, D.; Giorla, J.; Houry, M.; Jadaud, J.P.; Laffite, S.; Liberatore, S.; Loiseau, P.; Lours, L.; Masse, L.; Monteil, M.C.; Morice, O.; Naudy, M.; Philippe, F.; Poggi, F.; Renaud, F.; Riazuelo, G.; Saillard, Y.; Seytor, P.; Vandenboomgaerde, M.; Wagon, F. [CEA Bruyeres-le-Chatel, 91 (France)

    2007-08-15

    This article sums up the theoretical and experimental studies about ignition. Three experiments are salient this year on the Omega laser in collaboration with DOE laboratories. First, 3 cones of beams have allowed to mimic the LMJ (laser MegaJoule) configuration and to get symmetry measurements. Secondly, we have measured perturbations due to hydro-instability in CHGe planar samples with face-on and side-on radiographs. And thirdly, we have improved our nuclear diagnostics, particularly the neutron image system tested on direct drive implosions. As far as LMJ target design is concerned, we have defined a preliminary domain corresponding to the possible operation at 2{omega}. At 3 {omega} we have studied the low mode instability effects on the DT deformation (due to the laser or to the target) and on the yield. The stability is clearly improved with graded doped CH for our nominal capsule L1215. (authors)

  9. Treatment of Gait Ignition Failure with Ropinirole

    Directory of Open Access Journals (Sweden)

    Alexis N. Cohen-Oram

    2014-10-01

    Full Text Available Gait ignition failure (GIF is a syndrome characterized by hesitation or inability to initiate gait from a static position. It may occur in a variety of conditions, including normal pressure hydrocephalus, subcortical vascular disease, parkinsonian syndromes and a variety of focal lesions. Previous information on the treatment of GIF has been primarily anecdotal, but there have been a few reports of response to dopamine agonists. We report a 63-year-old man with anoxic encephalopathy who developed GIF nine years after the initial anoxic insult. The patient’s GIF responded robustly, albeit transiently, to ropinirole. MRI was unrevealing, but a positron emission tomography scan showed hypometabolism in the deep frontal ACA/MCA watershed area; this may have disconnected the basal ganglia from the motor cortex and/or interrupted dopaminergic mesocortical transmission. Our understanding of the pathophysiology and the treatment of GIF remains limited, but there may be at least a limited therapeutic role for dopamine agonists.

  10. Development and Testing of a Green Monopropellant Ignition System

    Science.gov (United States)

    Whitmore, Stephen A.; Merkley, Daniel P.; Eilers, Shannon D.; Judson, Michael I.; Taylor, Terry L.

    2013-01-01

    This paper will detail the development and testing of a "green" monopropellant booster ignition system. The proposed booster ignition technology eliminates the need for a pre-heated catalyst bed, a high wattage power source, toxic pyrophoric ignition fluids, or a bi-propellant spark ignitor. The design offers the simplicity of a monopropellant feed system features non-hazardous gaseous oxygen (GOX) as the working fluid. The approach is fundamentally different from all other "green propellant" solutions in the aerospace in the industry. Although the proposed system is more correctly a "hybrid" rocket technology, since only a single propellant feed path is required, it retains all the simple features of a monopropellant system. The technology is based on the principle of seeding an oxidizing flow with a small amount of hydrocarbon.1 The ignition is initiated electrostatically with a low-wattage inductive spark. Combustion gas byproducts from the hydrocarbon-seeding ignition process can exceed 2400 C and the high exhaust temperature ensures reliable main propellant ignition. The system design is described in detail in the Hydrocarbon-Seeded Ignition System Design subsection.

  11. Robustness studies of NIF ignition targets in two dimensions

    Science.gov (United States)

    Clark, Daniel

    2007-11-01

    Inertial confinement fusion capsules are critically dependent on the integrity of their hot spots to ignite. At the time of ignition, only a certain fractional perturbation of the nominally spherical hot spot boundary can be tolerated and the capsule still achieve ignition. The degree to which the expected hot spot perturbation in any given capsule design is less than this maximum tolerable perturbation is a measure of the ignition margin or robustness of that design. Moreover, since there will inevitably be uncertainties in the initial character and implosion dynamics of any given capsule, all of which can contribute to the eventual hot spot perturbation, quantifying the robustness of that capsule against a range of parameter variations is an important consideration in the capsule design. Here, the robustness of the 300 eV indirect drive target design for the National Ignition Facility (NIF) [J. D. Lindl, et. al., Phys. Plasmas 11, 339 (2004)] is studied in the parameter space of inner ice roughness, implosion velocity, and capsule scale. A suite of two thousand two-dimensional simulations, run with the radiation hydrodynamics code Lasnex, is used as the data base for the study. For each scale, an ignition region in the two remaining variables is identified and the ``ignition cliff'' is mapped. In accordance with the theoretical arguments of W. K. Levedahl and J. D. Lindl [Nucl. Fusion 37, 165 (1997)] and R. Kishony and D. Shvarts [Phys. Plasmas 8, 4925 (2001)], the location of this cliff is fitted to a power law of the capsule implosion velocity and scale. It is found that the cliff can be quite well represented in this power law form, and, using this scaling law, an assessment of the overall (one- and two-dimensional) ignition margin of the design can be made. The effect on the ignition margin of an increase or decrease in the density of the target fill gas is also assessed.

  12. Why relevance theory is relevant for lexicography

    DEFF Research Database (Denmark)

    Bothma, Theo; Tarp, Sven

    2014-01-01

    , socio-cognitive and affective relevance. It then shows, at the hand of examples, why relevance is important from a user perspective in the extra-lexicographical pre- and post-consultation phases and in the intra-lexicographical consultation phase. It defines an additional type of subjective relevance...... that is very important for lexicography as well as for information science, viz. functional relevance. Since all lexicographic work is ultimately aimed at satisfying users’ information needs, the article then discusses why the lexicographer should take note of all these types of relevance when planning a new...... dictionary project, identifying new tasks and responsibilities of the modern lexicographer. The article furthermore discusses how relevance theory impacts on teaching dictionary culture and reference skills. By integrating insights from lexicography and information science, the article contributes to new...

  13. The National Ignition Facility: The Path to Ignition, High Energy Density Science and Inertial Fusion Energy

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E

    2011-03-25

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is a Nd:Glass laser facility capable of producing 1.8 MJ and 500 TW of ultraviolet light. This world's most energetic laser system is now operational with the goals of achieving thermonuclear burn in the laboratory and exploring the behavior of matter at extreme temperatures and energy densities. By concentrating the energy from its 192 extremely energetic laser beams into a mm{sup 3}-sized target, NIF can produce temperatures above 100 million K, densities of 1,000 g/cm{sup 3}, and pressures 100 billion times atmospheric pressure - conditions that have never been created in a laboratory and emulate those in the interiors of planetary and stellar environments. On September 29, 2010, NIF performed the first integrated ignition experiment which demonstrated the successful coordination of the laser, the cryogenic target system, the array of diagnostics and the infrastructure required for ignition. Many more experiments have been completed since. In light of this strong progress, the U.S. and the international communities are examining the implication of achieving ignition on NIF for inertial fusion energy (IFE). A laser-based IFE power plant will require a repetition rate of 10-20 Hz and a 10% electrical-optical efficiency laser, as well as further advances in large-scale target fabrication, target injection and tracking, and other supporting technologies. These capabilities could lead to a prototype IFE demonstration plant in 10- to 15-years. LLNL, in partnership with other institutions, is developing a Laser Inertial Fusion Energy (LIFE) baseline design and examining various technology choices for LIFE power plant This paper will describe the unprecedented experimental capabilities of the NIF, the results achieved so far on the path toward ignition, the start of fundamental science experiments and plans to transition NIF to an international user facility

  14. Shock Timing experiments on the National Ignition Facility

    Science.gov (United States)

    Celliers, P. M.; Boehly, T. R.; Robey, H. F.; Datte, P. S.; Bowers, M. W.; Krauter, K. G.; Frieders, G.; Ross, G. F.; Jackson, J. L.; Olson, R. E.; Munro, D. H.; Nikroo, A.; Kroll, J. J.; Horner, J. B.; Hamza, A. V.; Bhandarkar, S. D.; Gibson, C. R.; Eggert, J. H.; Smith, R. F.; Park, H.-S.; Young, B. K.; Hsing, W. W.; Collins, G. W.; Landen, O. L.; Meyerhofer, D. D.

    2011-06-01

    Experiments are proceeding to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility. These experiments use a modified cryogenic hohlraum geometry designed to match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with VISAR (Velocity Interferometer System for Any Reflector). The results of these measurements will be used to set the pulse shape for ignition capsule implosions to follow. Prepared by LLNL under Contract DE-AC52-07NA27344.

  15. A study on spontaneous ignition of bituminous coal

    Directory of Open Access Journals (Sweden)

    Li Xin-Rui

    2009-01-01

    Full Text Available The thermal properties of four bituminous coals were studied using isothermal and temperature-programmed calorimeters, such as a differential thermal analysis, a heat flux calorimeter C80 and an thermal activity monitor (TAM-III. The corresponding spontaneous ignition was measured in an adiabatic spontaneous ignition tester. It was found that there were weak exothermic activities in bituminous coal at 50-100°C and meanwhile carbon monoxide and carbon dioxide was generated. These thermal behaviors are responsible for the self heating from 50°C and spontaneous ignition at 80°C.

  16. A study on spontaneous ignition of bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Xin-Rui Li; Hiroshi Koseki; Yusaku Iwata [National Research Institute of Fire and Disaster, Tokyo (Japan)

    2009-07-01

    The thermal properties of four bituminous coals were studied using isothermal and temperature-programmed calorimeters, such as a differential thermal analysis, a heat flux calorimeter C80 and an thermal activity monitor (TAM-III). The corresponding spontaneous ignition was measured in an adiabatic spontaneous ignition tester. It was found that there were weak exothermic activities in bituminous coal at 50-100 {sup o}C and meanwhile carbon monoxide and carbon dioxide was generated. These thermal behaviors are responsible for the self heating from 50{sup o}C and spontaneous ignition at 80{sup o}C. 15 refs., 7 figs., 5 tabs.

  17. The characteristics of drug resistant relevant genes in multidrug-resistant and extensively drug-resistant tuberculosis by fast molecular assay%M/XDR-TB的快速分子检测和耐药特征分析

    Institute of Scientific and Technical Information of China (English)

    范齐文; 郭建; 张慧涨; 吴晓渊; 胡香南; 钱雪琴; 邓桂林; 康涵; 吴文娟

    2011-01-01

    Objective To analyze the characterstics of phenotype and genotype of multidrug resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis (XDR-TB) by molecular line probe assay and liquid culture with MGIT960.Methods GenoType MTBDR Kits were used for identifying the types of the first-line and second-line antituberculosis drug resistant genes partly and BD MGIT960 was used for detecting the chug susceptibility.Results ( 1 ) Out of 94 MDR-TB strains,the rate of drug resistant to EMB,AMK,OFX and MFX by BD MGIT960 assay were 36.2%,17.0%,54.3% and 55.3%,respectively.Among these isolates,13 were extensively drug resistant tuberculosis (XDR-TB).(2) Compared with MGIT960,the concordance rate of GenoType MTBDRplus was 86.2% and 95.7% respectively.Taking MGIT960 results as reference,the sensitivity of GenoType MTBDRsl detecting the susceptibility of EMB,AMK,OFX and MFX to 94 isolates were 47.1%,81.3%,94.1%,94.2%,respectively.The specificity were 75.0%,98.7%,90.7%,92.9%,respectively.(3) Among the rpoB mutation categories,S531L accounts for most.MTB resistant to IFN caused by the mutation of katG chiefly and the S315T1 was in the majority.The gyrA mutation sites located at the ninety-fourth codon most.Out of 94 strains,23 were mixed with 2 kindsof Mycobacterium tuberculosis at least and 7 were undetectable mutations.Conclusion Among the M/XDR-TB,the strains resistant to INH,RFP,AMK,OFX and MFX were caused most by the mutation of katG,rpoB,rrs and gyrA,respectively.The relationship between EMB and embB was not so clear relatively.As a fast detecting drug susceptibility test kit,GenoType MTBDR possess good sensitivity and specificity.So,it could be as an assistant method to guide the therapy on clinic.%目的 使用分子线性探针杂交技术结合仪器法液体快速培养分析耐多药( multidrug resistant,MDR)及广泛耐药(extensively drug resistant,XDR)结核分枝杆菌(Mycobacterium tuberculosis,MTB)的耐药基因和表型特征.方法

  18. A direct numerical simulation of cool-flame affected autoignition in diesel engine-relevant conditions

    Energy Technology Data Exchange (ETDEWEB)

    Krisman, Alexander; Hawkes, Evatt Robert.; Talei, Mohsen; Bhagatwala, Ankit; Chen, Jacqueline H.

    2016-11-11

    In diesel engines, combustion is initiated by a two-staged autoignition that includes both low- and high-temperature chemistry. The location and timing of both stages of autoignition are important parameters that influence the development and stabilisation of the flame. In this study, a two-dimensional direct numerical simulation (DNS) is conducted to provide a fully resolved description of ignition at diesel engine-relevant conditions. The DNS is performed at a pressure of 40 atmospheres and at an ambient temperature of 900 K using dimethyl ether (DME) as the fuel, with a 30 species reduced chemical mechanism. At these conditions, similar to diesel fuel, DME exhibits two-stage ignition. The focus of this study is on the behaviour of the low-temperature chemistry (LTC) and the way in which it influences the high-temperature ignition. The results show that the LTC develops as a “spotty” first-stage autoignition in lean regions which transitions to a diffusively supported cool-flame and then propagates up the local mixture fraction gradient towards richer regions. The cool-flame speed is much faster than can be attributed to spatial gradients in first-stage ignition delay time in homogeneous reactors. The cool-flame causes a shortening of the second-stage ignition delay times compared to a homogeneous reactor and the shortening becomes more pronounced at richer mixtures. Multiple high-temperature ignition kernels are observed over a range of rich mixtures that are much richer than the homogeneous most reactive mixture and most kernels form much earlier than suggested by the homogeneous ignition delay time of the corresponding local mixture. Altogether, the results suggest that LTC can strongly influence both the timing and location in composition space of the high-temperature ignition.

  19. Ignition Delay Properties of Alternative Fuels with Navy-Relevant Diesel Injectors

    Science.gov (United States)

    2014-06-01

    and palm oil, vegetable oil, and animal fats [8]. Of 5 particular interest in the field of HRD production is microalgae [9]. Algae-based fuels are...of the microalgae does not interfere, either with land or resources, with the production of food [10]. Oil from microalgae is converted to diesel...derived from microalgae . An exhaustive list of the properties of HRD can be found in Hsieh et al. [10]. b. Direct Sugar-to-Hydrocarbon Fuel As the

  20. (Re)igniting a Sociological Imagination in Adult Education: The Continuing Relevance of Classical Theory

    Science.gov (United States)

    Lange, Elizabeth

    2015-01-01

    This article argues that sociology has been a foundational discipline for the field of adult education, but it has been largely implicit, until recently. This article contextualizes classical theories of sociology within contemporary critiques, reviews the historical roots of sociology and then briefly introduces the classical theories…

  1. (Re)igniting a Sociological Imagination in Adult Education: The Continuing Relevance of Classical Theory

    Science.gov (United States)

    Lange, Elizabeth

    2015-01-01

    This article argues that sociology has been a foundational discipline for the field of adult education, but it has been largely implicit, until recently. This article contextualizes classical theories of sociology within contemporary critiques, reviews the historical roots of sociology and then briefly introduces the classical theories…

  2. Relating the octane numbers of fuels to ignition delay times measured in an ignition quality tester (IQT)

    KAUST Repository

    Naser, Nimal

    2016-09-21

    A methodology for estimating the octane index (OI), the research octane number (RON) and the motor octane number (MON) using ignition delay times from a constant volume combustion chamber with liquid fuel injection is proposed by adopting an ignition quality tester. A baseline data of ignition delay times were determined using an ignition quality tester at a charge pressure of 21.3 bar between 770 and 850 K and an equivalence ratio of 0.7 for various primary reference fuels (PRFs, mixtures of isooctane and n-heptane). Our methodology was developed using ignition delay times for toluene reference fuels (mixtures of toluene and n-heptane). A correlation between the OI and the ignition delay time at the initial charge temperature enabled the OI of non-PRFs to be predicted at specified temperatures. The methodology was validated using ignition delay times for toluene primary reference fuels (ternary mixtures of toluene, iso-octane, and n-heptane), fuels for advanced combustion engines (FACE) gasolines, and certification gasolines. Using this methodology, the RON, the MON, and the octane sensitivity were estimated in agreement with values obtained from standard test methods. A correlation between derived cetane number and RON is also provided. (C) 2016 Elsevier Ltd. All rights reserved.

  3. Ignition time of self-propagating high-temperature synthesis by laser

    Institute of Scientific and Technical Information of China (English)

    陈森昌; 迟彦惠; 史玉升; 黄树槐

    2002-01-01

    The ignition of self-propagating high-temperature synthesis (SHS) by a laser beam has very well application, but there is lack in study on the ignition process. In order to search the rule of ignition process with laser beam, ignition time of SHS was studied in detail. First one dimension ignition model was introduced: burning is the process in which one layer is ignited by next layer. Then according to Fourier conduction equation, an equation used to calculate the ignition time was deduced. Finally a series of tests were made to verify the equation. The results prove that the change of the parameters in test agrees well with the equation.

  4. Two-stage Lagrangian modeling of ignition processes in ignition quality tester and constant volume combustion chambers

    KAUST Repository

    Alfazazi, Adamu

    2016-08-10

    The ignition characteristics of isooctane and n-heptane in an ignition quality tester (IQT) were simulated using a two-stage Lagrangian (TSL) model, which is a zero-dimensional (0-D) reactor network method. The TSL model was also used to simulate the ignition delay of n-dodecane and n-heptane in a constant volume combustion chamber (CVCC), which is archived in the engine combustion network (ECN) library (http://www.ca.sandia.gov/ecn). A detailed chemical kinetic model for gasoline surrogates from the Lawrence Livermore National Laboratory (LLNL) was utilized for the simulation of n-heptane and isooctane. Additional simulations were performed using an optimized gasoline surrogate mechanism from RWTH Aachen University. Validations of the simulated data were also performed with experimental results from an IQT at KAUST. For simulation of n-dodecane in the CVCC, two n-dodecane kinetic models from the literature were utilized. The primary aim of this study is to test the ability of TSL to replicate ignition timings in the IQT and the CVCC. The agreement between the model and the experiment is acceptable except for isooctane in the IQT and n-heptane and n-dodecane in the CVCC. The ability of the simulations to replicate observable trends in ignition delay times with regard to changes in ambient temperature and pressure allows the model to provide insights into the reactions contributing towards ignition. Thus, the TSL model was further employed to investigate the physical and chemical processes responsible for controlling the overall ignition under various conditions. The effects of exothermicity, ambient pressure, and ambient oxygen concentration on first stage ignition were also studied. Increasing ambient pressure and oxygen concentration was found to shorten the overall ignition delay time, but does not affect the timing of the first stage ignition. Additionally, the temperature at the end of the first stage ignition was found to increase at higher ambient pressure

  5. FAST READ

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    POLICY Reduced Vehicle Purchase Tax urged The Ministry of Industry and Information Technology and the Ministry of Commerce have jointly issued a circular on urging relevant sides to levy 5 percent Vehicle Purchase Tax on those purchased from Jan 20 through Dec 31,2009.The circular sets up 4 principles:

  6. Ignition of Isomers of Pentane: An Experimental and Kinetic Modeling Study

    Science.gov (United States)

    2000-08-04

    diesel engines [26,27], and ignition under homogeneous charge compres- sion ignition ( HCCI ) conditions [26,28]. Kinetic modeling shows that the isomers of...Introduction Hydrocarbon ignition is important in many prac- tical combustion systems, including internal com- bustion engines , detonations, pulse combustors...tem- peratures are similar to those in automotive engines during diesel ignition and end-gas autoignition in spark-ignition engines . The RCM provides

  7. Propellant Flow Actuated Piezoelectric Rocket Engine Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spark ignition of a bi-propellant rocket engine is a classic, proven, and generally reliable process. However, timing can be critical, and the control logic,...

  8. Physical Improvements in Exciter/Igniter Units Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project consists of developing a prototype exciter/igniter unit that can operate to a subset of expected flight performance requirements. The main focus...

  9. Propellant Flow Actuated Piezoelectric Rocket Engine Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Under a Phase 1 effort, IES successfully developed and demonstrated a spark ignition concept where propellant flow drives a very simple fluid mechanical oscillator...

  10. Physical Improvements in Exciter/Igniter Units Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase 2 project consists of the physical integration of our Phase 1 small, compact exciter with a "flight like" igniter or spark plug capable of...

  11. Compact Ignition Tokamak Program: status of FEDC studies

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, C.A.

    1985-01-01

    Viewgraphs on the Compact Ignition Tokamak Program comprise the report. The technical areas discussed are the mechanical configuration status, magnet analysis, stress analysis, cooling between burns, TF coil joint, and facility/device layout options. (WRF)

  12. Frictionally induced ignition processes in drop and skid tests

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Peter [Los Alamos National Laboratory; Parker, Gary [Los Alamos National Laboratory; Novak, Alan [Los Alamos National Laboratory

    2010-01-01

    The standard LANL/Pantex drop and skid tests rely on subjective assessment of reaction violence to quantify the response of the charge, and completely miss nonpropagating hot-spot ignition sites. Additionally, large variations in test results have been observed, which we propose is due to a misunderstanding of the basic physical processes that lead to threshold ignition in these tests. The tests have been redesigned to provide control of these mechanisms and to permit direct observation of hot spots at the impact site, allowing us to follow the progression of the outcome as the drop height and ignition source density are varied. The results confirm that frictional interactions between high-melting-point solids are the dominant ignition mechanism, not just at the threshold, but in fact at all realistic drop heights.

  13. Preliminary results from recent experiments and future roadmap to Shock Ignition of Fusion Targets

    Science.gov (United States)

    Batani, D.; Malka, G.; Schurtz, G.; Ribeyre, X.; Lebel, E.; Giuffrida, L.; Tikhonchuk, V.; Volpe, L.; Patria, A.; Koester, P.; Labate, L.; Gizzi, L. A.; Antonelli, L.; Richetta, M.; Nejdl, J.; Sawicka, M.; Margarone, D.; Krus, M.; Krousky, E.; Skala, J.; Dudzak, R.; Velyhan, A.; Ullshmied, J.; Renner, O.; Smid, M.; Klimo, O.; Atzeni, S.; Marocchino, A.; Schiavi, A.; Spindloe, C.; O'Dell, T.; Vinci, T.; Wolowski, J.; Badziak, J.; Pysarcizck, T.; Rosinski, M.; Kalinowska, Z.; Chodukowski, T.

    2012-11-01

    Shock ignition (SI) is a new approach to Inertial Confinement Fusion (ICF) based on decoupling the compression and ignition phase. The last one relies on launching a strong shock through a high intensity laser spike (<= 1016 W/cm2) at the end of compression. In this paper, first we described an experiment performed using the PALS iodine laser to study laser-target coupling and laser-plasma interaction in an intensity regime relevant for SI. A first beam with wavelength λ = 1.33 μm and low intensity was used to create an extended preformed plasma, and a second one with λ = 0.44 μm to create a strong shock. Several diagnostics characterized the preformed plasma and the interaction of the main pulse. Pressure up to 90 Mbar was inferred. In the last paper of the paper, we discuss the relevant steps, which can be followed in order to approach the demonstration of SI on laser facilities like LMJ.

  14. Ignition technique for an in situ oil shale retort

    Science.gov (United States)

    Cha, Chang Y.

    1983-01-01

    A generally flat combustion zone is formed across the entire horizontal cross-section of a fragmented permeable mass of formation particles formed in an in situ oil shale retort. The flat combustion zone is formed by either sequentially igniting regions of the surface of the fragmented permeable mass at successively lower elevations or by igniting the entire surface of the fragmented permeable mass and controlling the rate of advance of various portions of the combustion zone.

  15. Ignition and burn of a small magnetized fuel target

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, Ronald C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2012-06-01

    The crucial step for inertial confinement fusion (ICF) is ignition, which leads to sufficiently high gain to enable design of a power producing system. Thus far, this step has not been demonstrated. Magnetized targets may provide an alternative path to ignition. In addition, the 1-D calculations presented here suggest that this approach may provide the gain and other characteristics needed for a practical fusion reactor.

  16. CORONA DISCHARGE IGNITION FOR ADVANCED STATIONARY NATURAL GAS ENGINES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Paul D. Ronney

    2003-09-12

    An ignition source was constructed that is capable of producing a pulsed corona discharge for the purpose of igniting mixtures in a test chamber. This corona generator is adaptable for use as the ignition source for one cylinder on a test engine. The first tests were performed in a cylindrical shaped chamber to study the characteristics of the corona and analyze various electrode geometries. Next a test chamber was constructed that closely represented the dimensions of the combustion chamber of the test engine at USC. Combustion tests were performed in this chamber and various electrode diameters and geometries were tested. The data acquisition and control system hardware for the USC engine lab was updated with new equipment. New software was also developed to perform the engine control and data acquisition functions. Work is underway to design a corona electrode that will fit in the new test engine and be capable igniting the mixture in one cylinder at first and eventually in all four cylinders. A test engine was purchased for the project that has two spark plug ports per cylinder. With this configuration it will be possible to switch between corona ignition and conventional spark plug ignition without making any mechanical modifications.

  17. Controlled auto ignition of gasoline engines; Steuerung der ottomotorischen Selbstzuendung

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, Christina

    2011-07-01

    Controlled Auto Ignition allows for significant efficiency gains in combination with extremely low NO{sub x} emissions and particulate matters when compared to conventional spark ignited combustion concepts. The limiting factors for controlled auto ignition are the temperature at very low loads and the pressure gradient at higher loads. Based on experiments on a single cylinder engine with fully variable valve actuators and gasoline direct injection, the contribution under consideration reports on main parameters to control the controlled auto ignition. Detailed analyses demonstrate the impact of each parameter on self-ignition and combustion. Additionally, different methods to expand the operating range of controlled auto ignition are discussed with regard to the achievable efficiency and the required effort. One important result of this contribution is a feed-forward control which coordinates the main actuating parameters and ensures the desired combustion phasing even in dynamic mode. A regression model is developed which uses the input variables air/fuel ratio, start of injection, engine speed and fuel mass to predict the combustion phasing and the indicated mean effective pressure. Inverting this model leads to the final feed-forward control which allows to separate the effects of start of injection and exhaust valve closing. In that case exhaust valve closing controls the air/fuel ratio, while start of injection corrects the lasting deviation in combustion phasing. Using the actual air/fuel ratio as an additional input parameter ensures the required combustion phasing even in dynamic mode.

  18. Ignition of pyrophoric powders: An entry-level model

    Science.gov (United States)

    Alymov, M. I.; Seplyarskii, B. S.; Gordopolova, I. S.

    2015-11-01

    Chemically prepared metal nanopowders are normally pyrophoric, i.e. are liable to ignite spontaneously on exposure to air because of high reactivity and developed specific surface. On the other side, reliable theoretical models for spontaneous self-ignition of fine dispersed powders at room temperature have not been suggested so far. A deeper insight into the mechanism of the phenomenon would shed new light on the critical conditions for self-inflammation and thus would provide some clues for optimization of the passivation of fine dispersed powders. In this work, we formulated and analyzed an entry-level model for ignition of pyrophoric powders. Analysis of such a model in terms of the ignition theory gave the following results. Depending on the width of the reaction zone, the ignition may get started in either one or two stages. The duration of each stage was evaluated by using the approximate methods of combustion theory. The parametric limits for the model applicability were derived and the influence of sample length on the ignition process was explored as well.

  19. Cyclopentane combustion. Part II. Ignition delay measurements and mechanism validation

    KAUST Repository

    Rachidi, Mariam El

    2017-06-12

    This study reports cyclopentane ignition delay measurements over a wide range of conditions. The measurements were obtained using two shock tubes and a rapid compression machine, and were used to test a detailed low- and high-temperature mechanism of cyclopentane oxidation that was presented in part I of this study (Al Rashidi et al., 2017). The ignition delay times of cyclopentane/air mixtures were measured over the temperature range of 650–1350K at pressures of 20 and 40atm and equivalence ratios of 0.5, 1.0 and 2.0. The ignition delay times simulated using the detailed chemical kinetic model of cyclopentane oxidation show very good agreement with the experimental measurements, as well as with the cyclopentane ignition and flame speed data available in the literature. The agreement is significantly improved compared to previous models developed and investigated at higher temperatures. Reaction path and sensitivity analyses were performed to provide insights into the ignition-controlling chemistry at low, intermediate and high temperatures. The results obtained in this study confirm that cycloalkanes are less reactive than their non-cyclic counterparts. Moreover, cyclopentane, a high octane number and high octane sensitivity fuel, exhibits minimal low-temperature chemistry and is considerably less reactive than cyclohexane. This study presents the first experimental low-temperature ignition delay data of cyclopentane, a potential fuel-blending component of particular interest due to its desirable antiknock characteristics.

  20. Mechanism of plasma ignition in electrothermal-chemical launcher

    Directory of Open Access Journals (Sweden)

    Yong Jin

    2016-04-01

    Full Text Available Plasma generator is a core component in an electrothermal-chemical (ETC launcher. Its work state directly influences the launch efficiency of a system. The interaction between plasma and propellants is a very important mechanism in ETC technology. Based on the transient radiation model and open air plasma jet experiment, the mechanism of plasma ignition process is analyzed. Results show that the surface temperature of local solid propellant grain can quickly achieve the ignition temperature under the action of early transient plasma radiation. But it needs enough time to maintain the high energy flow to make self-sustained combustion of solid propellant grains. Because of the limited space characteristics of transient radiation, the near-field propellant grains can gain enough energy by the strong transient radiation to be ignited and achieve self-sustained combustion. The far-field propellant grains mainly gain the energy by the activated particles in plasma jet to be ignited and self-sustained combustion. Experiments show that plasma jet always has a high flow velocity in the area of the cartridge. Compared with conventional ignition, the solid propellant grains can obtain more quick and uniform ignition and self-sustained combustion by this kind of ablation controlled arc (ACA plasma via energy skin effect of propellant grains, pre-heat temperature mechanism and high efficient jet diffusion.

  1. Analysis of Metallised Propellant Ignition Process under Conductive Heating

    Directory of Open Access Journals (Sweden)

    K. A. Bhaskaran

    1998-07-01

    Full Text Available Ignition of a composite aluminised propellant (AP-HTPB-Al in stagnant hot air is analysed theoretically, based on solid phase and gas phase theories. According to solid phase theory, ignition is due to reaction of the propellant in the solid phase at elevated temperatures. One-dimensional transient solid phase energy equation is solved to obtain the surface temperature profile of the propellant. By gas phase theory, an exothermic gas phase reaction, adjacent to the propellant surface, is considered responsible for the ignition. The changes in temperature and concentrations in the gas phase and the temperature profile below the propellant surface during the pre-ignition induction period are considered. Equations of energy and concentrations of reactants have been solved to obtain the species concentration and temperature profiles in the gas phase. An experimental investigation of the ignition of AP-HTPB-Al propellant is also carried out in a shock tube under end-mount conditions. Pressure and temperature ranges were 6-16 bar and 1500-3000 K, respectively. A comparison of the experimental data with predicted results shows that the ignition in an oxidizing atmosphere is by gas phase reaction, whereas in an inert atmosphere, solid phase reaction may be predominant.

  2. Mechanism of plasma ignition in electrothermal-chemical launcher

    Institute of Scientific and Technical Information of China (English)

    Yong JIN; Yan-jie NI; Hai-yuan LI; Bao-ming LI

    2016-01-01

    Plasma generator is a core component in an electrothermal-chemical (ETC) launcher. Its work state directly influences the launch efficiency of a system. The interaction between plasma and propellants is a very important mechanism in ETC technology. Based on the transient radiation model and open air plasma jet experiment, the mechanism of plasma ignition process is analyzed. Results show that the surface temperature of local solid propellant grain can quickly achieve the ignition temperature under the action of early transient plasma radiation. But it needs enough time to maintain the high energy flow to make self-sustained combustion of solid propellant grains. Because of the limited space characteristics of transient radiation, the near-field propellant grains can gain enough energy by the strong transient radiation to be ignited and achieve self-sustained combustion. The far-field propellant grains mainly gain the energy by the activated particles in plasma jet to be ignited and self-sustained combustion. Experiments show that plasma jet always has a high flow velocity in the area of the cartridge. Compared with conventional ignition, the solid propellant grains can obtain more quick and uniform ignition and self-sustained combustion by this kind of ablation controlled arc (ACA) plasma via energy skin effect of propellant grains, pre-heat temperature mechanism and high efficient jet diffusion.

  3. Fast generation of dendritic cells

    DEFF Research Database (Denmark)

    Kvistborg, P; Bøgh, Marie; Claesson, M H

    2009-01-01

    we have developed fast DC protocol by comparing two different fast DC protocols with SDDC. DC were evaluated by FACS analysis, and the optimal profile was considered: CD14(low), CD80(high), CD83(high), CD86(high), CCR7(high), HLA class I and II(high). FACS profiles were used as the selection criteria...... together with yield and morphology. Two fast DC protocols fulfilled these criteria and were selected for functional analysis. Our results demonstrate that DC generated within 5days or 48h are comparable with SDDC both phenotypically and functionally. However, we found that 48h DC were more susceptible than...... SDDC to the IL-10 inducing stimulus of TLR ligands (R848 and LPS). Thus to determine the clinical relevance of fast DC protocols in cancer settings, small phase I trials should be conducted monitoring regulatory T cells carefully....

  4. Experimental studies on the group ignition of a cloud of coal particles: Volume 2, Pyrolysis and ignition modeling

    Energy Technology Data Exchange (ETDEWEB)

    Annamalai, K.; Ryan, W.

    1992-01-01

    The primary objectives of this work are to formulate a model to simulate transient coal pyrolysis, ignition, and combustion of a cloud of coal particles and to compare results of the program with those reported in the literature elsewhere.

  5. Sensitivity and Effect of Ignition Timing on the Performance of a Spark Ignition Engine: An Experimental and Modeling Study

    Directory of Open Access Journals (Sweden)

    A. H. Kakaee

    2011-01-01

    Full Text Available The performance of a spark ignition engine is investigated under different values of ignition advance. A two-zone burnt/unburned model with the fuel burning rate described by a Wiebe function is used for modeling in-cylinder combustion, and then experiments are carried out to validate the calculated data. By varying the ignition timing, the results of some characteristics such as power, torque, thermal efficiency, pressure, and heat release are obtained and compared. The results show that optimal power and torque are achieved at 31°CA before top dead center, and performance is decreased if this ignition timing is changed. It is also shown that the maximum thermal efficiency is accomplished when peak pressure occurs between 5 and 15°CA after top dead center.

  6. Status of the National Ignition Facility Integrated Computer Control System (ICCS) on the path to ignition

    Energy Technology Data Exchange (ETDEWEB)

    Lagin, L.J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550 (United States)], E-mail: lagin1@llnl.gov; Bettenhausen, R.C.; Bowers, G.A.; Carey, R.W.; Edwards, O.D.; Estes, C.M.; Demaret, R.D.; Ferguson, S.W.; Fisher, J.M.; Ho, J.C.; Ludwigsen, A.P.; Mathisen, D.G.; Marshall, C.D.; Matone, J.T.; McGuigan, D.L.; Sanchez, R.J.; Stout, E.A.; Tekle, E.A.; Townsend, S.L.; Van Arsdall, P.J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550 (United States)] (and others)

    2008-04-15

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-MJ, 500-TW, ultraviolet laser system together with a 10-m diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is comprised of 24 independent bundles of eight beams each using laser hardware that is modularized into more than 6000 line replaceable units such as optical assemblies, laser amplifiers, and multi-function sensor packages containing 60,000 control and diagnostic points. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 800 front-end processors and 50 supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves interoperation between different languages and target architectures. A shot automation framework has been deployed during the past year to orchestrate and automate shots performed at the NIF using the ICCS. In December 2006, a full cluster of 48 beams of NIF was fired simultaneously, demonstrating that the independent bundle control system will scale to full scale of 192 beams. At present, 72 beams have been commissioned and have demonstrated 1.4-MJ capability of infrared light. During the next 2 years, the control system will be expanded in preparation for project completion in 2009 to include automation of target area systems including

  7. Magnetic Fields on the National Ignition Facility (MagNIF)

    Energy Technology Data Exchange (ETDEWEB)

    Mason, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Folta, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-12

    A magnetized target capability on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) has been investigated. Stakeholders’ needs and project feasibility analysis were considered in order to down-select from a wide variety of different potential magnetic field magnitudes and volumes. From the large range of different target platforms, laser configurations, and diagnostics configurations of interest to the stakeholders, the gas-pipe platform has been selected for the first round of magnetized target experiments. Gas pipe targets are routinely shot on the NIF and provide unique value for external collaborators. High-level project goals have been established including an experimentally relevant 20Tesla magnetic field magnitude. The field will be achieved using pulsed power-driven coils. A system architecture has been proposed. The pulsed power drive system will be located in the NIF target bay. This decision provides improved maintainability and mitigates equipment safety risks associated with explosive failure of the drive capacitor. High-level and first-level subsystem requirements have been established. Requirements have been included for two distinct coil designs – full solenoid and quasi-Helmholtz. A Failure Modes and Effects Analysis (FMEA) has been performed and documented. Additional requirements have been derived from the mitigations included in the FMEA document. A project plan is proposed. The plan includes a first phase of electromagnetic simulations to assess whether the design will meet performance requirements, then a second phase of risk mitigation projects to address the areas of highest technical risk. The duration from project kickoff to the first magnetized target shot is approximately 29 months.

  8. Development and testing of an ignition physics test facility and an oxygen/methane swirl torch igniter

    Science.gov (United States)

    Flores, Jesus Roberto

    There are many advantages to LOX/methane propulsion, such as in-situ resource utilization from Mars and the Moon, and simplicity of ground operations due to its non-toxic nature. There exists a lack of fundamental understanding of the ignition physics, and flame characteristics of these propellants when related to rocket propulsion, which has created undesirably long design cycles and flight hardware that is not optimized. Motivated by these issues, a study of the ignition physics of a shear coaxial injector is proposed, in which the flow field dynamics and ignition transients will be observed through a visually accessible combustion chamber. The main goal of this work is to study the effects of geometric differences of the injector, such as recess in the liquid oxygen post and thickness of the LOX post, on the jet breakup downstream of the injector, and the flame anchoring mechanism and location. A facility was developed to support this endeavor in a safe and efficient way, including a cryogenic delivery system, a Multipurpose Optically Accessible Combustor (MOAC) with torch igniter, and a bunker with a Data Acquisition and Remote Controls system (DARCS). A swirl coflow premixed torch igniter was designed, manufactured and developed with the intent of using it as the MOAC's main ignition source. It was designed to use oxygen and methane as the propellants in an incremental step towards the goal of a LOX/methane rocket engine. Extensive testing was done on the igniter in the development phase to prove that it will reliable ignite and sustain combustion under a variety of propellant inlet conditions of which include: warm gas, cold gas, and liquid cryogenic conditions. The testing phase also provided data for component reliability and proof of concept for the testing facilities designed, especially for the cryogenic delivery system, and methane condensing unit. Future injector testing parameters of the hardware produced is included along with recommendations to

  9. Overview of the National Ignition Facility.

    Science.gov (United States)

    Brereton, Sandra

    2013-06-01

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is the world's largest and most energetic laser system for inertial confinement fusion (ICF) and experiments studying high energy density (HED) science. The NIF is a 192-beam, Nd-glass laser facility that is capable of producing 1.8 MJ, 500 TW of ultraviolet light, and over 50 times more energetic than other existing ICF facilities. The NIF construction began in 1997, and the facility, which was completed in 2009, is now fully operational. The facility is capable of firing up to 192 laser beams onto a target placed at the center of a 10-m-diameter spherical target chamber. Experiments involving the use of tritium have been underway for some time. These experiments present radiological issues: prompt neutron/gamma radiation, neutron activation, fission product generation, and decay radiation. This paper provides an introduction to the NIF facility and its operation, describes plans for the experimental program, and discusses radiological issues associated with the NIF's operations.

  10. National Ignition Facility Project Site Safety Program

    Energy Technology Data Exchange (ETDEWEB)

    Dun, C

    2003-09-30

    This Safety Program for the National Ignition Facility (NIF) presents safety protocols and requirements that management and workers shall follow to assure a safe and healthful work environment during activities performed on the NIF Project site. The NIF Project Site Safety Program (NPSSP) requires that activities at the NIF Project site be performed in accordance with the ''LLNL ES&H Manual'' and the augmented set of controls and processes described in this NIF Project Site Safety Program. Specifically, this document: (1) Defines the fundamental NIF site safety philosophy. (2) Defines the areas covered by this safety program (see Appendix B). (3) Identifies management roles and responsibilities. (4) Defines core safety management processes. (5) Identifies NIF site-specific safety requirements. This NPSSP sets forth the responsibilities, requirements, rules, policies, and regulations for workers involved in work activities performed on the NIF Project site. Workers are required to implement measures to create a universal awareness that promotes safe practice at the work site and will achieve NIF management objectives in preventing accidents and illnesses. ES&H requirements are consistent with the ''LLNL ES&H Manual''. This NPSSP and implementing procedures (e.g., Management Walkabout, special work procedures, etc.,) are a comprehensive safety program that applies to NIF workers on the NIF Project site. The NIF Project site includes the B581/B681 site and support areas shown in Appendix B.

  11. National Ignition Facility Comes to Life

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E

    2003-09-01

    First conceived of nearly 15 years ago, the National Ignition Facility (NIF) is up and running and successful beyond almost everyone's expectations. During commissioning of the first four laser beams, the laser system met design specifications for everything from beam quality to energy output. NIF will eventually have 192 laser beams. Yet with just 2% of its final beam configuration complete, NIF has already produced the highest energy laser shots in the world. In July, laser shots in the infrared wavelength using four beams produced a total of 26.5 kilojoules of energy per beam, not only meeting NIF's design energy requirement of 20 kilojoules per beam but also exceeding the energy of any other infrared laser beamline. In another campaign, NIF produced over 11.4 kilojoules of energy when the infrared light was converted to green light. An earlier performance campaign of laser light that had been frequency converted from infrared to ultraviolet really proved NIF's mettle. Over 10.4 kilojoules of ultraviolet energy were produced in about 4 billionths of a second. If all 192 beamlines were to operate at these levels, over 2 megajoules of energy would result. That much energy for the pulse duration of several nanoseconds is about 500 trillion watts of power, more than 500 times the US peak generating power.

  12. Imploding ignition waves: I. one dimensional analysis

    CERN Document Server

    Kushnir, Doron; Waxman, Eli

    2011-01-01

    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_c. An approximate analytic expression for R_c 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_c~0.1 mm (spherical) and R_c~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_c. Our suggested mechanism differs from that proposed by Zel'dovich et al. (1970), 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...

  13. Experimental and Numerical Study of Jet Controlled Compression Ignition on Combustion Phasing Control in Diesel Premixed Compression Ignition Systems

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2014-07-01

    Full Text Available In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark timing. Detailed combustion characteristics were analyzed based on the BMEP of 2.18 bar. The simulation results showed that the high temperature jets of reacting active radical species issued from the ignition chamber played an important role on the onset of combustion in the JCCI system. The combustion of diesel pre-mixtures was initiated rapidly by the combustion products issued from the ignition chamber. Moreover, the flame propagation was not obvious, similar to that in Pre-mixed Charge Compression Ignition (PCCI. Consequently, spark timing sweep experiments were conducted. The results showed a good linear relationship between spark timing in the ignition chamber and CA10 and CA50, which indicated the ability for direct combustion phasing control in diesel PCCI. The NOx and soot emissions gradually changed with the decrease of spark advance angle. The maximum reduction of NOx and soot were both over 90%, and HC and CO emissions were increased.

  14. Theory of hydro-equivalent ignition for inertial fusion and its applications to OMEGA and the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Nora, R.; Betti, R.; Bose, A.; Woo, K. M.; Christopherson, A. R.; Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Fusion Science Center, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and/or Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Anderson, K. S.; Shvydky, A.; Marozas, J. A.; Collins, T. J. B.; Radha, P. B.; Hu, S. X.; Epstein, R.; Marshall, F. J.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); McCrory, R. L. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and/or Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

    2014-05-15

    The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements for cryogenic implosion experiments on the Omega Laser Facility. The theory of hydrodynamic similarity is developed in both one and two dimensions and tested using multimode hydrodynamic simulations with the hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] of hydro-equivalent implosions (implosions with the same implosion velocity, adiabat, and laser intensity). The theory is used to scale the performance of direct-drive OMEGA implosions to the National Ignition Facility (NIF) energy scales and determine the requirements for demonstrating hydro-equivalent ignition on OMEGA. Hydro-equivalent ignition on OMEGA is represented by a cryogenic implosion that would scale to ignition on the NIF at 1.8 MJ of laser energy symmetrically illuminating the target. It is found that a reasonable combination of neutron yield and areal density for OMEGA hydro-equivalent ignition is 3 to 6 × 10{sup 13} and ∼0.3 g/cm{sup 2}, respectively, depending on the level of laser imprinting. This performance has not yet been achieved on OMEGA.

  15. Analysis on ignition and extinction of n-heptane in homogeneous systems

    Institute of Scientific and Technical Information of China (English)

    LIU; Yongfeng; PEI; Pucheng

    2005-01-01

    To calculate ignition delay times, the governing equations about species and temperature, which are in a closed volume based on the theory of thermal explosion and in a continuously stirred flow reactor, are deducted. The method referred to steady state assumptions is based on the observation that due to very fast chemical processes in combustion problems many chemical species and reactions are in a quasi-steady state or partial equilibrium. When a species is assumed to be in the steady state, the corresponding differential equation can be replaced by an algebraic relation, which reduces the computational costs. The steady state solution of the reactor equations describes the three ignition temperature regimes and get "S-shaped curve". The reduced simplified 4-step mechanism for n-heptane from 1011 elementary reactions leads with the steady state assumptions to linear differential equations, which is solved. The simulation results of the 4-step reduced mechanism for n-heptane are fitted well with the experiment data. At last, two important parameters are discussed thoroughly and the temperature perturbation is given. It reduces the computational efforts considerably without losing too much accuracy and further supplies numerical methods for turbulent combustion in the diesel engine.

  16. Experimental Study on Igniting Self-propagating High-temperature Synthesis by Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Senchang; SHI Yusheng; HUANG Shuhuai

    2002-01-01

    An applied range of self-propagating high-temperature synthesis (SHS) is extended under igniting by laser, but there is no study in detail on its ignition process. The ignition time of SHS by laser is studied in detail in this paper for searching igniting law. A laser beam produced by CO2 laser scans back and forth along a straight line on the surface of a sample, and an ignition time is measured under different testing conditions. The results show that the ignition time is the shortest at certain mixing time, the ignition time is longer with decreasing of the density and increasing of the sample density, and the ignition time becomes shorter when pre-heat temperature rises, but the ignition time has no relation with the area and the thickness of samples when the thickness is thicker, and it has no close relation with shield gas of N2.

  17. High-temperature oxidation and ignition of metals

    Science.gov (United States)

    Hill, Paul R; Adamson, David; Foland, Douglas H; Bressette, Walter E

    1956-01-01

    A study of the high-temperature oxidation of several aircraft construction materials was undertaken to assess the possibility of ignition under high-temperature flight conditions.Tests have been made both in open and closed jets, and, in addition, the burning of metals has been observed under static conditions in a pressurized vessel containing either air, oxygen, or nitrogen. When heated in an atmosphere of oxygen or when heated and plunged into a supersonic airstream, titanium, iron, carbon steel, and common alloys such as 4130 were found to have spontaneous-ignition temperatures in the solid phase (below melting) and they melted rapidly while burning. Inconel, copper, 18-8 stainless steel, Monel, and aluminum could not be made to ignite spontaneously at temperatures up to melting with the equipment available. Magnesium ignited spontaneously in either type of test at temperatures just above the melting temperature.A theory for the spontaneous ignition of metals, based on the first law of thermodynamics, is presented. Good correlation was obtained between calculated spontaneous-ignition temperatures and values measured in supersonic jet tests. There appears at the present time to be no need for concern regarding the spontaneous ignition of Inconel, the stainless steels, copper, aluminum, or magnesium for ordinary supersonic airplane or missile applications where the material temperature is kept within ordinary structural limits or at least below melting. For hypersonic applications where the material is to be melted away to absorb the heat of convection, the results of the present tests do not apply sufficiently to allow a conclusion.

  18. Compositional effects on the ignition of FACE gasolines

    KAUST Repository

    Sarathy, Mani

    2016-05-08

    As regulatory measures for improved fuel economy and decreased emissions are pushing gasoline engine combustion technologies towards extreme conditions (i.e., boosted and intercooled intake with exhaust gas recirculation), fuel ignition characteristics become increasingly important for enabling stable operation. This study explores the effects of chemical composition on the fundamental ignition behavior of gasoline fuels. Two well-characterized, high-octane, non-oxygenated FACE (Fuels for Advanced Combustion Engines) gasolines, FACE F and FACE G, having similar antiknock indices but different octane sensitivities and chemical compositions are studied. Ignition experiments were conducted in shock tubes and a rapid compression machine (RCM) at nominal pressures of 20 and 40. atm, equivalence ratios of 0.5 and 1.0, and temperatures ranging from 650 to 1270. K. Results at temperatures above 900. K indicate that ignition delay time is similar for these fuels. However, RCM measurements below 900. K demonstrate a stronger negative temperature coefficient behavior for FACE F gasoline having lower octane sensitivity. In addition, RCM pressure profiles under two-stage ignition conditions illustrate that the magnitude of low-temperature heat release (LTHR) increases with decreasing fuel octane sensitivity. However, intermediate-temperature heat release is shown to increase as fuel octane sensitivity increases. Various surrogate fuel mixtures were formulated to conduct chemical kinetic modeling, and complex multicomponent surrogate mixtures were shown to reproduce experimentally observed trends better than simpler two- and three-component mixtures composed of n-heptane, iso-octane, and toluene. Measurements in a Cooperative Fuels Research (CFR) engine demonstrated that the multicomponent surrogates accurately captured the antiknock quality of the FACE gasolines. Simulations were performed using multicomponent surrogates for FACE F and G to reveal the underlying chemical

  19. Ignition during hydrogen release from high pressure into the atmosphere

    Science.gov (United States)

    Oleszczak, P.; Wolanski, P.

    2010-12-01

    The first investigations concerned with a problem of hydrogen jet ignition, during outflow from a high-pressure vessel were carried out nearly 40 years ago by Wolanski and Wojcicki. The research resulted from a dramatic accident in the Chorzow Chemical Plant Azoty, where the explosion of a synthesis gas made up of a mixture composed of three moles of hydrogen per mole of nitrogen, at 300°C and 30 MPa killed four people. Initial investigation had excluded potential external ignition sources and the main aim of the research was to determine the cause of ignition. Hydrogen is currently considered as a potential fuel for various vehicles such as cars, trucks, buses, etc. Crucial safety issues are of potential concern, associated with the storage of hydrogen at a very high pressure. Indeed, the evidence obtained nearly 40 years ago shows that sudden rupture of a high-pressure hydrogen storage tank or other component can result in ignition and potentially explosion. The aim of the present research is identification of the conditions under which hydrogen ignition occurs as a result of compression and heating of the air by the shock wave generated by discharge of high-pressure hydrogen. Experiments have been conducted using a facility constructed in the Combustion Laboratory of the Institute of Heat Engineering, Warsaw University of Technology. Tests under various configurations have been performed to determine critical conditions for occurrence of high-pressure hydrogen ignition. The results show that a critical pressure exists, leading to ignition, which depends mainly on the geometric configuration of the outflow system, such as tube diameter, and on the presence of obstacles.

  20. Bridge Wire Electric Ignition Drive Circuits Design%桥丝电点火器的驱动电路设计∗

    Institute of Scientific and Technical Information of China (English)

    张宪国; 曹红松; 赵捍东; 白松

    2015-01-01

    Pulse jet engines are often ignited by gunpowder wrapped bridge wire electric igniter and widely used in aircraft attitude control. The electric igniter needs short-pulse current driving for rapid initiation. In this paper,opto-isolated constant current source and capacitor discharge mode driving circuits are designed for the demand of micro-bridge wire electric igniter. Two kinds of detonating circuit designs implemente the ignition driving of brige wire e-lectric igniter wtih resistance fluctuations. The constant current source mode is capable of long storage life,compact spatial structure and high safety, and the reservoir capacitor mode demonstrates high energy efficiency and fast-acting for quick initiation. Two methods provide reference designs for the pulse jet engines of different engineering requirements.%用于飞行器姿态控制的脉喷发动机常采用火药包裹的桥丝电点火器进行点火,电点火器需要短时脉冲电流驱动。本文针对微小型桥丝电点火器驱动需求,设计了光耦隔离恒流源方式及电容储能脉冲放电驱动电路,均实现了对阻值波动桥丝电点火器的点火驱动。试验证明,光耦隔离恒流源方式可靠性高,安全稳定,电容储能放电方式效率高、作用迅速。该两种设计方法可为脉喷发动机的工程实践提供参考。

  1. EFFECT OF IGNITION TIMING ON THE PERFORMANCE OF LPG FUELLED SI ENGINE

    Directory of Open Access Journals (Sweden)

    R.M.Dabhadkar

    2013-05-01

    Full Text Available Fast depletion of fossil fuels and their detrimental effect on the environment is demanding an urgent need of alternative fuels for meeting sustainable energy demand with minimum environmental impact.A lot of research is being carried out throughout the world to evaluate the performance, exhaust emission and combustion characteristics of the existing engines using several alternative fuels such as hydrogen, compressed natural gas, alcohols, liquefied petroleum gas (LPG, biogas, producer gas, bio-diesels developed from vegetable oils, and others (Roy et. al, 2010. LPG and CNG are the alternative fuels to be widely adopted for use in the world. Gaseous fuel mix uniformly with air which burns precisely during combustion than liquid fuels. It has minimum carbon deposition & negligible physical delay. Internal combustion engines running on liquid petroleum gas (LPG are well-proven technologies and work much likegasoline-powered spark-ignition engines. They are normally used as spark-ignition engines for bi-fuelled (gasoline/CH4 cars, but have also been used, for example, in compression-ignition engines for heavy-duty vehicles. Both LPG and NG are not used alone, but always in bi-fuel vehicles, in combination with gasoline. In bi-fuel vehicles two fuels are stored in separate tanks and the engine runs on one fuel at a time. Bi-fuel vehicles have the capability to switch back and forth from gasoline to the other fuel, manually or automatically. As a fuel for spark-ignition engines LPG have some advantages over gasoline, such as a better anti-knock characteristic and reduced CO and unburned HC emissions (Hsieh et al., 2002. Environmental point of view is that there is an increasing interest among the suppliers to investigate LPG as a transportation fuel.It was found that the liquid petroleum gas, roughly a mixture of propane and butane, which gives a benefit in terms of toxic hydrocarbons emissions and ozone formation due to its composition and CO2

  2. Possible version of the compression degradation of the thermonuclear indirect-irradiation targets at the national ignition facility and a reason for the failure of ignition

    Science.gov (United States)

    Rozanov, V. B.; Vergunova, G. A.

    2017-01-01

    The main parameters of compression of a target and tendencies at change in the irradiation conditions are determined by analyzing the published results of experiments at the megajoule National Ignition Facility (NIF) on the compression of capsules in indirect-irradiation targets by means of the one-dimensional RADIAN program in the spherical geometry. A possible version of the "failure of ignition" of an indirect-irradiation target under the NIF conditions is attributed to radiation transfer. The application of onedimensional model to analyze the National Ignition Campaign (NIC) experiments allows identifying conditions corresponding to the future ignition regime and distinguishing them from conditions under which ignition does not occur.

  3. A recoverable gas-cell diagnostic for the National Ignition Facility

    Science.gov (United States)

    Ratkiewicz, A.; Berzak Hopkins, L.; Bleuel, D. L.; Bernstein, L. A.; van Bibber, K.; Cassata, W. S.; Goldblum, B. L.; Siem, S.; Velsko, C. A.; Wiedeking, M.; Yeamans, C. B.

    2016-11-01

    The high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell. We present early results from the use of this diagnostic to measure the activation of natXe and discuss future work to study the strength of interactions between plasma and nuclei.

  4. Simulation of a gamma reaction history (GRH) detector for use at the National Ignition Facility (NIF)

    Science.gov (United States)

    Grafil, Elliot; Toebbe, Jonathan

    2009-10-01

    Reaction history measurements are critical to diagnosing inertial confinement fusion (ICF) implosions. As such they will be essential components of the National Ignition Facility (NIF) diagnostics. One proposed method to record the reaction history is the construction of a gamma-sensitive gas Cerenkov detector. An array of these Cerenkov detectors can be used to discriminate between the different gamma ray energies produced during the ICF implosion. These fusion gammas are converted to optical photons for collection by fast recording systems. We have simulated the gamma reaction history (GRH) detector under development at NIF and LANL using Geant4. Our simulations have been used to determine energy cut-off ranges for photon production in various gases, optimizing converter material and thickness, and discriminating between proposed detector geometries in order to minimize the temporal spread of the signal.

  5. A recoverable gas-cell diagnostic for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Ratkiewicz, A., E-mail: ratkiewicz1@llnl.gov; Berzak Hopkins, L.; Bleuel, D. L.; Cassata, W. S.; Velsko, C. A.; Yeamans, C. B. [Lawrence Livermore National Laboratory, Livermore, California 95440 (United States); Bernstein, L. A.; Bibber, K. van; Goldblum, B. L. [University of California, Berkeley, California 94720 (United States); Siem, S. [University of Oslo, N-0316 Oslo (Norway); Wiedeking, M. [iThemba LABS, Somerset West 7129 (South Africa)

    2016-11-15

    The high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell. We present early results from the use of this diagnostic to measure the activation of {sup nat}Xe and discuss future work to study the strength of interactions between plasma and nuclei.

  6. Nonlinear effects associated with fast magnetosonic waves and turbulent magnetic amplification in laboratory and astrophysical plasmas

    Science.gov (United States)

    Tiwary, PremPyari; Sharma, Swati; Sharma, Prachi; Singh, Ram Kishor; Uma, R.; Sharma, R. P.

    2016-12-01

    This paper presents the spatio-temporal evolution of magnetic field due to the nonlinear coupling between fast magnetosonic wave (FMSW) and low frequency slow Alfvén wave (SAW). The dynamical equations of finite frequency FMSW and SAW in the presence of ponderomotive force of FMSW (pump wave) has been presented. Numerical simulation has been carried out for the nonlinear coupled equations of finite frequency FMSW and SAW. A systematic scan of the nonlinear behavior/evolution of the pump FMSW has been done for one of the set of parameters chosen in this paper, using the coupled dynamical equations. Filamentation of fast magnetosonic wave has been considered to be responsible for the magnetic turbulence during the laser plasma interaction. The results show that the formation and growth of localized structures depend on the background magnetic field but the order of amplification does not get affected by the magnitude of the background magnetic field. In this paper, we have shown the relevance of our model for two different parameters used in laboratory and astrophysical phenomenon. We have used one set of parameters pertaining to experimental observations in the study of fast ignition of laser fusion and hence studied the turbulent structures in stellar environment. The other set corresponds to the study of magnetic field amplification in the clumpy medium surrounding the supernova remnant Cassiopeia A. The results indicate considerable randomness in the spatial structure of the magnetic field profile in both the cases and gives a sufficient indication of turbulence. The turbulent spectra have been studied and the break point has been found around k which is consistent with the observations in both the cases. The nonlinear wave-wave interaction presented in this paper may be important in understanding the turbulence in the laboratory as well as the astrophysical phenomenon.

  7. A Steam-Plasma Igniter for Aluminum Powder Combustion

    Science.gov (United States)

    Sanghyup, Lee; Kwanyoung, Noh; Jihwan, Lim; Woongsup, Yoon

    2015-05-01

    High-temperature ignition is essential for the ignition and combustion of energetic metal fuels, including aluminum and magnesium particles which are protected by their high-melting-temperature oxides. A plasma torch characterized by an ultrahigh-temperature plasma plume fulfills such high-temperature ignition conditions. A new steam plasma igniter is designed and successfully validated by aluminum power ignition and combustion tests. The steam plasma rapidly stabilizes in both plasma and steam jet modes. Parametric investigation of the steam plasma jet is conducted in terms of arc strength. A high-speed camera and an oscilloscope method visualize the discharge characteristics, and optical emission spectroscopy measures the thermochemical properties of the plasma jet. The diatomic molecule OH fitting method, the Boltzmann plot method, and short exposure capturing with an intensified charge coupled device record the axial distributions of the rotational gas temperature, excitation temperature, and OH radical distribution, respectively. The excitation temperature at the nozzle tip is near 5500 K, and the gas temperature is 5400 K.

  8. Path To Ignition: US Indirect Target Physics (LIRPP Vol. 12)

    Science.gov (United States)

    Cray, M.; Campbell, E. M.

    2016-10-01

    The United States ICF Program has been pursuing an aggressive research program in preparation for an ignition demonstration on the National Ignition Facility. Los Alamos and Livermore laboratories have collaborated on resolving indirect drive target physics issues on the Nova laser at Livermore National Laboratory. This combined with detailed modeling of laser heated indirectly driven targets likely to achieve ignition, has provided the basis for planning for the NIF. A detailed understanding of target physics, laser performance, and target fabrication is required for developing robust ignition targets. We have developed large-scale computational models to simulate complex physics which occurs in an indirectly driven target. For ignition, detailed understanding of hohlraum and implosion physics is required in order to control competing processes at the few percent level. From crucial experiments performed by Los Alamos and Livermore on the Nova laser, a comprehensive indirect drive database has been assembled. Time integrated and time dependent measurements of radiation drive and symmetry coupled with a detailed set of plasma instability measurements have confirmed our ability to predict hohlraum energetics. Implosion physics campaigns are focused on underdstanding detailed capsule hydrodynamics and instability growth. Target fabrication technology is also an active area of research at Los Alamos, Livermore, and General Atomics for NIF. NIF targets require developing technology in cryogenics and manufacturing in such areas as beryllium shell manufacture. Descriptions of our NIF target designs, experimental results, and fabrication technology supporting NIF target performance predictions will be given.

  9. LES of an ignition sequence in a gas turbine engine

    Energy Technology Data Exchange (ETDEWEB)

    Boileau, M.; Staffelbach, G.; Cuenot, B. [CERFACS, Toulouse (France); Poinsot, T. [IMFT - CNRS, Toulouse (France); Berat, C. [Turbomeca (SAFRAN group), Bordes (France)

    2008-07-15

    Being able to ignite or reignite a gas turbine engine in a cold and rarefied atmosphere is a critical issue for many manufacturers. From a fundamental point of view, the ignition of the first burner and the flame propagation from one burner to another are phenomena that are usually not studied. The present work is a large eddy simulation (LES) of these phenomena. To simulate a complete ignition sequence in an annular chamber, LES has been applied to the full 360 geometry, including 18 burners. This geometry corresponds to a real gas turbine chamber. Massively parallel computing (700 processors on a Cray XT3 machine) was essential to perform such a large calculation. Results show that liquid fuel injection has a strong influence on the ignition times. Moreover, the rate of flame progress from burner to burner is much higher than the turbulent flame speed due to a major effect of thermal expansion. This flame speed is also strongly modified by the main burner aerodynamics due to the swirled injection. Finally, the variability of the combustor sectors and quadrant ignition times is highlighted. (author)

  10. Super Marx Generator for Thermonuclear Ignition

    CERN Document Server

    Winterberg, Friedwardt

    2008-01-01

    In ongoing electric pulse power driven inertial confinement fusion experiments, Marx generators are connected in parallel with the target in the center of a ring of the Marx generators. There the currents, not the voltages add up. Instead of connecting a bank of Marx generator in parallel, one may connect them in series, adding up their voltages, not the currents. If, for example, fifty 20 MV Marx generators are connected in series, they would add up to a gigavolt. But to prevent breakdown, the adding up of the voltages in such a super-Marx generator must be fast. For this reason, it is proposed that each of the Marx generators charges up a fast discharge capacitor, with the thusly charged fast capacitors becoming the elements of a second stage super Marx generator. In a super Marx generator, the Marx generators also assume the role of the resistors in the original Marx circuit. With a voltage of 10^9 Volt and a discharge current of 10^7 Ampere, the generation of a 10^16 Watt GeV proton beam becomes possible,...

  11. Deep learning relevance

    DEFF Research Database (Denmark)

    Lioma, Christina; Larsen, Birger; Petersen, Casper

    2016-01-01

    train a Recurrent Neural Network (RNN) on existing relevant information to that query. We then use the RNN to "deep learn" a single, synthetic, and we assume, relevant document for that query. We design a crowdsourcing experiment to assess how relevant the "deep learned" document is, compared......What if Information Retrieval (IR) systems did not just retrieve relevant information that is stored in their indices, but could also "understand" it and synthesise it into a single document? We present a preliminary study that makes a first step towards answering this question. Given a query, we...... to existing relevant documents. Users are shown a query and four wordclouds (of three existing relevant documents and our deep learned synthetic document). The synthetic document is ranked on average most relevant of all....

  12. Quantifying Cricket Fast Bowling Skill.

    Science.gov (United States)

    Feros, Simon A; Young, Warren B; O'Brien, Brendan J

    2017-09-27

    To evaluate the current evidence regarding the quantification of cricket fast bowling skill. Studies that assessed fast bowling skill (bowling speed and accuracy) were identified from searches in SPORTDiscus (EBSCO) in June 2017. The reference lists of identified papers were also examined for relevant investigations. Sixteen papers matched the inclusion criteria, and discrepancies in assessment procedures were evident. Differences in: test environment, pitch and cricket ball characteristics, the warm-up prior to test, test familiarisation procedures, permitted run-up lengths, bowling spell length, delivery sequence, test instructions, collection of bowling speed data, collection and reportage of bowling accuracy data were apparent throughout the literature. The reliability and sensitivity of fast bowling skill measures has rarely been reported across the literature. Only one study has attempted to assess the construct validity of their skill measures. There are several discrepancies in how fast bowling skill has been assessed and subsequently quantified in the literature to date. This is a problem, as comparisons between studies are often difficult. Therefore, a strong rationale exists for the creation of match-specific standardised fast bowling assessments that offer greater ecological validity while maintaining acceptable reliability and sensitivity of the skill measures. If prospective research can act on the proposed recommendations from this review, then coaches will be able to make more informed decisions surrounding player selection, talent identification, return to skill following injury, and the efficacy of short- and long-term training interventions for fast bowlers.

  13. Results from Direct-Drive Shock-Timing Experiments at the National Ignition Facility

    Science.gov (United States)

    Radha, P. B.; Rosenberg, M. J.; Hohenberger, M.; Boehly, T. R.; Campbell, E. M.; Froula, D. H.; Goncharov, V. N.; Hu, S. X.; Marozas, J. A.; Myatt, J. F.; Regan, S. P.; Sangster, T. C.; Dixit, S.

    2016-10-01

    The timing of multiple shocks is critical to set an inertial confinement capsule on a desired adiabat. Several factors including laser-energy deposition, heat conduction, and equation of state determine the adiabat of the compressing shell. Dual-axis cone-in-shell experiments, performed with plastic, (CH) shells and solid spheres, are used to diagnose the first shock velocity and the catch up of subsequent shocks at the National Ignition Facility. The shocks are launched with multiple pickets, expected to be used in ignition-relevant designs, at two different intensities. In separate experiments, continuous pulse shapes are also diagnosed. The measurements are compared to two-dimensional DRACO simulations that include the effects of nonlocal heat transport, cross-beam energy transfer, and the first-principles equation of state of CH. Designs that could potentially diagnose late-time energy coupling through shocks are also presented. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  14. Propellant Flow Actuated Piezoelectric Igniter for Combustion Engines

    Science.gov (United States)

    Wollen, Mark A. (Inventor)

    2015-01-01

    A propellant flow actuated piezoelectric igniter device using one or more hammer balls retained by one or more magnets, or other retaining method, until sufficient fluid pressure is achieved to release and accelerate the hammer ball, such that it impacts a piezoelectric crystal to produce an ignition spark. Certain preferred embodiments provide a means for repetitively capturing and releasing the hammer ball after it impacts one or more piezoelectric crystals, thereby oscillating and producing multiple, repetitive ignition sparks. Furthermore, an embodiment is presented for which oscillation of the hammer ball and repetitive impact to the piezoelectric crystal is maintained without the need for a magnet or other retaining mechanism to achieve this oscillating impact process.

  15. Characterizing pyrotechnic igniter output with high-speed schlieren imaging

    Science.gov (United States)

    Skaggs, M. N.; Hargather, M. J.; Cooper, M. A.

    2017-01-01

    Small-scale pyrotechnic igniter output has been characterized using a high-speed schlieren imaging system for observing critical features of the post-combustion flow. The diagnostic, with laser illumination, was successfully applied towards the quantitative characterization of the output from Ti/KClO_4 and TiH_{1.65}/KClO_4 pyrotechnic igniters. The high-speed image sequences showed shock motion, burned gas expansion, and particle motion. A statistical-based analysis methodology for tracking the full-field shock motion enabled straightforward comparisons across the experimental parameters of pyrotechnic material and initial density. This characterization of the mechanical energy of the shock front within the post-combustion environment is a necessary addition to the large body of literature focused on pyrotechnic combustion behavior within the powder bed. Ultimately, understanding the role that the combustion behavior has on the resulting multiphase environment is required for tailored igniter development and comparative performance assessments.

  16. Kinetic model for DT ignition and burn in ICF targets

    Energy Technology Data Exchange (ETDEWEB)

    Anisimov, S.I.; Oparin, A.M.; Meyer-ter-Vehn, J. [Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany)]|[L.D. Landau Institute for Theoretical Physics, 117940 Moscow (Russia)

    1996-05-01

    Ignition and burn of DT targets is studied taking into account kinetic effects. Kinetic equations describing the interaction of the high-energy reaction products with target plasma are solved using the particle-in-cell (PIC) code for collisional plasma. Volume and spark ignition configurations are simulated for initial temperatures and {l_angle}{rho}{ital R}{r_angle} values of practical interest and target masses between 0.1 and 10 mg. Optically thick configurations igniting at temperatures below 5 keV are considered. Burn of the targets with reduced tritium content is simulated. It was shown that, for 25{percent} tritium concentration, the energy output is reduced only by 15{percent}. {copyright} {ital 1996 American Institute of Physics.}

  17. Shock timing on the National Ignition Facility: First experiments

    Science.gov (United States)

    Celliers, P. M.; Robey, H. F.; Boehly, T. R.; Alger, E.; Azevedo, S.; Berzins, L. V.; Bhandarkar, S. D.; Bowers, M. W.; Brereton, S. J.; Callahan, D.; Castro, C.; Chandrasekaran, H.; Choate, C.; Clark, D. S.; Coffee, K. R.; Datte, P. S.; Dewald, E. L.; DiNicola, P.; Dixit, S.; Döppner, T.; Dzenitis, E.; Edwards, M. J.; Eggert, J. H.; Fair, J.; Farley, D. R.; Frieders, G.; Gibson, C. R.; Giraldez, E.; Haan, S.; Haid, B.; Hamza, A. V.; Haynam, C.; Hicks, D. G.; Holunga, D. M.; Horner, J. B.; Jancaitis, K.; Jones, O. S.; Kalantar, D.; Kline, J. L.; Krauter, K. G.; Kroll, J. J.; LaFortune, K. N.; Le Pape, S.; Malsbury, T.; Mapoles, E. R.; Meezan, N. B.; Milovich, J. L.; Moody, J. D.; Moreno, K.; Munro, D. H.; Nikroo, A.; Olson, R. E.; Parham, T.; Pollaine, S.; Radousky, H. B.; Ross, G. F.; Sater, J.; Schneider, M. B.; Shaw, M.; Smith, R. F.; Sterne, P. A.; Thomas, C. A.; Throop, A.; Town, R. P. J.; Trummer, D.; Van Wonterghem, B. M.; Walters, C. F.; Widmann, K.; Widmayer, C.; Young, B. K.; Atherton, L. J.; Collins, G. W.; Landen, O. L.; Lindl, J. D.; MacGowan, B. J.; Meyerhofer, D. D.; Moses, E. I.

    2013-11-01

    An experimental campaign to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility (NIF) was initiated in late 2010. The experiments use a NIF ignition-scale hohlraum and capsule that employs a re-entrant cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with velocity interferometry that provides target performance data used to set the pulse shape for ignition capsule implosions that follow. From the start, these measurements yielded significant new information on target performance, leading to improvements in the target design. We describe the results and interpretation of the initial tuning experiments.

  18. Shock timing on the National Ignition Facility: First experiments

    Directory of Open Access Journals (Sweden)

    Celliers P.M.

    2013-11-01

    Full Text Available An experimental campaign to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility (NIF was initiated in late 2010. The experiments use a NIF ignition-scale hohlraum and capsule that employs a re-entrant cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with velocity interferometry that provides target performance data used to set the pulse shape for ignition capsule implosions that follow. From the start, these measurements yielded significant new information on target performance, leading to improvements in the target design. We describe the results and interpretation of the initial tuning experiments.

  19. AN INTRODUCTION TO A HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE

    Directory of Open Access Journals (Sweden)

    A.A. Hairuddin

    2014-12-01

    Full Text Available Homogeneous charge compression ignition (HCCI engine technology is relatively new and has not matured sufficiently to be commercialised compared with conventional engines. It can use spark ignition or compression ignition engine configurations, capitalizing on the advantages of both: high engine efficiency with low emissions levels. HCCI engines can use a wide range of fuels with low emissions levels. Due to these advantages, HCCI engines are suitable for use in a hybrid engine configuration, where they can reduce the fuel consumption even further. However, HCCI engines have some disadvantages, such as knocking and a low to medium operating load range, which need to be resolved before the engine can be commercialised. Therefore, a comprehensive study has to be performed to understand the behaviour of HCCI engines.

  20. A Study on Homogeneous Charge Compression Ignition Gasoline Engines

    Science.gov (United States)

    Kaneko, Makoto; Morikawa, Koji; Itoh, Jin; Saishu, Youhei

    A new engine concept consisting of HCCI combustion for low and midrange loads and spark ignition combustion for high loads was introduced. The timing of the intake valve closing was adjusted to alter the negative valve overlap and effective compression ratio to provide suitable HCCI conditions. The effect of mixture formation on auto-ignition was also investigated using a direct injection engine. As a result, HCCI combustion was achieved with a relatively low compression ratio when the intake air was heated by internal EGR. The resulting combustion was at a high thermal efficiency, comparable to that of modern diesel engines, and produced almost no NOx emissions or smoke. The mixture stratification increased the local A/F concentration, resulting in higher reactivity. A wide range of combustible A/F ratios was used to control the compression ignition timing. Photographs showed that the flame filled the entire chamber during combustion, reducing both emissions and fuel consumption.

  1. Ignition Delay Times of Kerosene(Jet-A)/Air Mixtures

    CERN Document Server

    Zhukov, V P; Starikovskii, A Yu

    2012-01-01

    Ignition of Jet-A/air mixtures was studied behind reflected shock waves. Heating of shock tube at temperature of 150 C was used to prepare a homogeneous fuel mixture. Ignition delay times were measured from OH emission at 309 nm and from absorption of He-Ne laser radiation at 3.3922 micrometers. The conditions behind shock waves were calculated by one-dimensional shock wave theory from initial conditions T1, P1, mixture composition and incident shock wave velocity. The ignition delay times were obtained at two fixed pressures 10, 20 atm for lean, stoichiometric and rich mixtures (ER=0.5, 1, 2) at an overall temperature range of 1040-1380 K.

  2. Ignition characteristics of 2-methyltetrahydrofuran: An experimental and kinetic study

    KAUST Repository

    Tripathi, Rupali

    2016-10-15

    The present paper elucidates oxidation behavior of 2-methyltetrahydrofuran (2-MTHF), a novel second-generation biofuel. New experimental data sets for 2-MTHF including ignition delay time measurements in two different combustion reactors, i.e. rapid compression machine and high-pressure shock tube, are presented. Measurements for 2-MTHF/oxidizer/diluent mixtures were performed in the temperature range of . 639-1413 K, at pressures of 10, 20, and 40 bar, and at three different equivalence ratios of 0.5, 1.0, and 2.0. A detailed chemical kinetic model describing both low-and high-temperature chemistry of 2-MTHF was developed and validated against new ignition delay measurements and already existing flame species profiles and ignition delay measurements. The mechanism provides satisfactory agreement with the experimental data. For identifying key reactions at various combustion conditions and to attain a better understanding of the combustion behavior, reaction path and sensitivity analyses were performed.

  3. Cavitation-induced ignition of cryogenic hydrogen-oxygen fluids

    Science.gov (United States)

    Osipov, V. V.; Muratov, C. B.; Ponizovskaya-Devine, E.; Foygel, M.; Smelyanskiy, V. N.

    2011-03-01

    The Challenger disaster and purposeful experiments with liquid hydrogen (H2) and oxygen (Ox) tank breaches demonstrated that cryogenic H2/Ox fluids always self-ignite in the process of their sudden mixing. Here, we propose a cavitation-induced self-ignition mechanism that may be realized under these conditions. In one possible scenario, self-ignition is caused by the strong shock waves generated by the collapse of pure Ox vapor bubble near the surface of the Ox liquid that may initiate detonation of the gaseous H2/Ox mixture next to the gas-liquid interface. This effect is further enhanced by H2/Ox combustion inside the collapsing bubble in the presence of admixed H2 gas.

  4. Cavitation-induced ignition of cryogenic hydrogen-oxygen fluids

    CERN Document Server

    Osipov, V V; Ponizovskya-Devine, E; Foygel, M; Smelyanskiy, V N

    2011-01-01

    The Challenger disaster and purposeful experiments with liquid hydrogen (H2) and oxygen (Ox) tanks demonstrated that cryogenic H2/Ox fluids always self-ignite in the process of their mixing. Here we propose a cavitation-induced self-ignition mechanism that may be realized under these conditions. In one possible scenario, self-ignition is caused by the strong shock waves generated by the collapse of pure Ox vapor bubble near the surface of the Ox liquid that may initiate detonation of the gaseous H2/Ox mixture adjacent to the gas-liquid interface. This effect is further enhanced by H2/Ox combustion inside the collapsing bubble in the presence of admixed H2 gas.

  5. Features of Ignition and Stable Combustion in Supersonic Combustor

    Science.gov (United States)

    Goldfeld, M.; Starov, A.; Timofeev, K.

    2009-01-01

    Present paper describes the results of experimental investigations of the supersonic combustor with entrance Mach numbers from 2 to 4 at static pressure from 0.8 to 2.5 bars, total temperature from 2000K to 3000K. Hydrogen and kerosene were used as fuel. The conditions, under which the self-ignition and intensive combustion of the fuel realized were found. Position of ignition area in the channel was determined and features of flame propagation in the channel presented. A possibility to ensure an efficient combustion of hydrogen and kerosene at a high supersonic flow velocity at the combustor entrance without special throttling and/or pseudo-shock introduction was shown. Analysis of applicability of existing methods of criterion descriptions of conditions of self-ignition and extinction of combustion is executed for generalization of experimental results on the basis of results obtained.

  6. Compression ignition of hydrogen-containing mixtures in shock tubes

    Science.gov (United States)

    Medvedev, S. P.; Gelfand, B. E.; Khomik, S. V.; Agafonov, G. L.

    2010-12-01

    The state of the art of the problem of discrepancy between the values measured in shock tubes and calculated for the delay of ignition of hydrogen-containing systems has been analyzed. It is shown that in the low-temperature region the off-design appearance of reaction sites leads to the propagation of a flame in a mixture heated by a reflected shock wave. The parameter of the time of mixture combustion in a deflagration regime has been introduced and the use of it together with the calculated delay in self-ignition for delimitation and classification of thermal and gas-dynamic phenomena on compression ignition of hydrogen-containing mixtures in shock tubes has been suggested.

  7. Photothermally activated motion and ignition using aluminum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Abboud, Jacques E.; Chong Xinyuan; Zhang Mingjun; Zhang Zhili [Mechanical, Aerospace and Biomedical Engineering Department, University of Tennessee, Knoxville, Tennessee 37996 (United States); Jiang Naibo; Roy, Sukesh [Spectral Energies, LLC, 5100 Springfield Street, Suite 301, Dayton, Ohio 45431 (United States); Gord, James R. [Air Force Research Laboratory, Propulsion Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States)

    2013-01-14

    The aluminum nanoparticles (Al NPs) are demonstrated to serve as active photothermal media, to enhance and control local photothermal energy deposition via the photothermal effect activated by localized surface plasmon resonance (LSPR) and amplified by Al NPs oxidation. The activation source is a 2-AA-battery-powered xenon flash lamp. The extent of the photothermally activated movement of Al NPs can be {approx}6 mm. Ignition delay can be {approx}0.1 ms. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements of motion-only and after-ignition products confirm significant Al oxidation occurs through sintering and bursting after the flash exposure. Simulations suggest local heat generation is enhanced by LSPR. The positive-feedback effects from the local heat generation amplified by Al oxidation produce a large increase in local temperature and pressure, which enhances movement and accelerates ignition.

  8. Volume Ignition via Time-like Detonation in Pellet Fusion

    CERN Document Server

    Csernai, L P

    2015-01-01

    Relativistic fluid dynamics and the theory of relativistic detonation fronts are used to estimate the space-time dynamics of the burning of the D-T fuel in Laser driven pellet fusion experiments. The initial "High foot" heating of the fuel makes the compressed target transparent to radiation, and then a rapid ignition pulse can penetrate and heat up the whole target to supercritical temperatures in a short time, so that most of the interior of the target ignites almost simultaneously and instabilities will have no time to develop. In these relativistic, radiation dominated processes both the interior, time-like burning front and the surrounding space-like part of the front will be stable against Rayleigh-Taylor instabilities. To achieve this rapid, volume ignition the pulse heating up the target to supercritical temperature should provide the required energy in less than ~ 10 ps.

  9. The Effect of Spark Timing on the Spark Ignition

    Directory of Open Access Journals (Sweden)

    Rafeq A. Khalefa

    2013-04-01

    Full Text Available  In this work the effect of spark timing on the spark ignition engines is investigated by computer simulation and experimental test for speeds of (1500,2000,2500,3000 and 3500rpm at spark timing of (20o,30o,40o,50o and 60o before TDC for each speed. This is done in order to find a suitable  mathematical expression for spark ignition advancing with respect to the speed of the engine to predict the correct ignition advance  as in real engines .The results showed that the method of using a mathematical expression is more realistic and reasonable  comparing  with the results obtained by other workers. 

  10. Tokamak power reactor ignition and time dependent fractional power operation

    Energy Technology Data Exchange (ETDEWEB)

    Vold, E.L.; Mau, T.K.; Conn, R.W.

    1986-06-01

    A flexible time-dependent and zero-dimensional plasma burn code with radial profiles was developed and employed to study the fractional power operation and the thermal burn control options for an INTOR-sized tokamak reactor. The code includes alpha thermalization and a time-dependent transport loss which can be represented by any one of several currently popular scaling laws for energy confinement time. Ignition parameters were found to vary widely in density-temperature (n-T) space for the range of scaling laws examined. Critical ignition issues were found to include the extent of confinement time degradation by alpha heating, the ratio of ion to electron transport power loss, and effect of auxiliary heating on confinement. Feedback control of the auxiliary power and ion fuel sources are shown to provide thermal stability near the ignition curve.

  11. Recent Advances in Cigarette Ignition Propensity Research and Development.

    Science.gov (United States)

    Alpert, Hillel R; O'Connor, Richard J; Spalletta, Ron; Connolly, Gregory N

    2010-04-01

    Major U.S. cigarette companies for decades conducted research and development regarding cigarette ignition propensity which has continued beyond fire safety standards for cigarettes that have recently been legislated. This paper describes recent scientific advances and technological development based on a comprehensive review of the physical, chemical, and engineering sciences, public health, and trade literature, U.S. and international patents, and research in the tobacco industry document libraries.Advancements since the first implementation of standards have made been in: a) understanding the key parameters involved in cigarette smoldering combustion and ignition of substrates; b) developing new cigarette and paper wrapper designs to reduce ignition propensity, including banded and non-banded cigarette paper approaches, c) assessing toxicology, and d) measuring performance. While the implications of manufacturers' non-safety related aims are of concern, this research indicates possible alternative designs should experience with fire loss and existing technologies on the market suggest need for improvement.

  12. Photothermally activated motion and ignition using aluminum nanoparticles

    Science.gov (United States)

    Abboud, Jacques E.; Chong, Xinyuan; Zhang, Mingjun; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2013-01-01

    The aluminum nanoparticles (Al NPs) are demonstrated to serve as active photothermal media, to enhance and control local photothermal energy deposition via the photothermal effect activated by localized surface plasmon resonance (LSPR) and amplified by Al NPs oxidation. The activation source is a 2-AA-battery-powered xenon flash lamp. The extent of the photothermally activated movement of Al NPs can be ˜6 mm. Ignition delay can be ˜0.1 ms. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements of motion-only and after-ignition products confirm significant Al oxidation occurs through sintering and bursting after the flash exposure. Simulations suggest local heat generation is enhanced by LSPR. The positive-feedback effects from the local heat generation amplified by Al oxidation produce a large increase in local temperature and pressure, which enhances movement and accelerates ignition.

  13. WILDFIRE IGNITION RESISTANCE ESTIMATOR WIZARD SOFTWARE DEVELOPMENT REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.; Robinson, C.; Gupta, N.; Werth, D.

    2012-10-10

    This report describes the development of a software tool, entitled “WildFire Ignition Resistance Estimator Wizard” (WildFIRE Wizard, Version 2.10). This software was developed within the Wildfire Ignition Resistant Home Design (WIRHD) program, sponsored by the U. S. Department of Homeland Security, Science and Technology Directorate, Infrastructure Protection & Disaster Management Division. WildFIRE Wizard is a tool that enables homeowners to take preventive actions that will reduce their home’s vulnerability to wildfire ignition sources (i.e., embers, radiant heat, and direct flame impingement) well in advance of a wildfire event. This report describes the development of the software, its operation, its technical basis and calculations, and steps taken to verify its performance.

  14. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2014-11-15

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D{sup 3}He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D{sup 3}He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (R{sub cm}) from the downshift of the shock-produced D{sup 3}He protons. The observed ρR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time (“short-coast”), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (∼800 ps) than in the short-coast (∼400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel ρR.

  15. Shot Automation for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Lagin, L J; Bettenhausen, R C; Beeler, R G; Bowers, G A; Carey, R; Casavant, D D; Cline, B D; Demaret, R D; Domyancic, D M; Elko, S D; Fisher, J M; Hermann, M R; Krammen, J E; Kohut, T R; Marshall, C D; Mathisen, D G; Ludwigsen, A P; Patterson, Jr., R W; Sanchez, R J; Stout, E A; Van Arsdall, P J; Van Wonterghem, B M

    2005-09-21

    A shot automation framework has been developed and deployed during the past year to automate shots performed on the National Ignition Facility (NIF) using the Integrated Computer Control System This framework automates a 4-8 hour shot sequence, that includes inputting shot goals from a physics model, set up of the laser and diagnostics, automatic alignment of laser beams and verification of status. This sequence consists of set of preparatory verification shots, leading to amplified system shots using a 4-minute countdown, triggering during the last 2 seconds using a high-precision timing system, followed by post-shot analysis and archiving. The framework provides for a flexible, model-based execution driven of scriptable automation called macro steps. The framework is driven by high-level shot director software that provides a restricted set of shot life cycle state transitions to 25 collaboration supervisors that automate 8-laser beams (bundles) and a common set of shared resources. Each collaboration supervisor commands approximately 10 subsystem shot supervisors that perform automated control and status verification. Collaboration supervisors translate shot life cycle state commands from the shot director into sequences of ''macro steps'' to be distributed to each of its shot supervisors. Each Shot supervisor maintains order of macro steps for each subsystem and supports collaboration between macro steps. They also manage failure, restarts and rejoining into the shot cycle (if necessary) and manage auto/manual macro step execution and collaborations between other collaboration supervisors. Shot supervisors execute macro step shot functions commanded by collaboration supervisors. Each macro step has database-driven verification phases and a scripted perform phase. This provides for a highly flexible methodology for performing a variety of NIF shot types. Database tables define the order of work and dependencies (workflow) of macro steps to be

  16. Reactive burn models and ignition & growth concept

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph S [Los Alamos National Laboratory; Shaw, Milton S [Los Alamos National Laboratory

    2010-01-01

    Plastic-bonded explosives are heterogeneous materials. Experimentally, shock initiation is sensitive to small amounts of porosity, due to the formation of hot spots (small localized regions of high temperature). This leads to the Ignition and Growth concept, introduced by Lee and Tarver in 1980, as the basis for reactive burn models. A homogeneized burn rate needs to account for three mesoscale physical effects (i) the density of burnt hot spots, which depends on the lead shock strength; (ii) the growth of the burn fronts triggered by hot spots, which depends on the local deflagration speed; (iii) a geometric factor that accounts for the overlap of deflagration wavelets from adjacent hot spots. These effects can be combined and the burn model defined by specifying the reaction progress variable {lambda}(t) as a function of a dimensionless reaction length {tau}{sub hs}(t)/{ell}{sub hs}, rather than by xpecifying an explicit burn rate. The length scale {ell}{sub hs} is the average distance between hot spots, which is proportional to [N{sub hs}(P{sub s})]{sup -1/3}, where N{sub hs} is the number density of hot spots activated by the lead shock. The reaction length {tau}{sub hs}(t) = {line_integral}{sub 0}{sup t} D(P(t'))dt' is the distance the burn front propagates from a single hot spot, where D is the deflagration speed and t is the time since the shock arrival. A key implementation issue is how to determine the lead shock strength in conjunction with a shock capturing scheme. They have developed a robust algorithm for this purpose based on the Hugoniot jump condition for the energy. The algorithm utilizes the time dependence of density, pressure and energy within each cell. The method is independent of the numerical dissipation used for shock capturing. It is local and can be used in one or more space dimensions. The burn model has a small number of parameters which can be calibrated to fit velocity gauge data from shock initiation experiments.

  17. Reactive burn models and ignition & growth concept

    Directory of Open Access Journals (Sweden)

    Shaw M.S.

    2011-01-01

    Full Text Available Plastic-bonded explosives are heterogeneous materials. Experimentally, shock initiation is sensitive to small amounts of porosity, due to the formation of hot spots (small localized regions of high temperature. This leads to the Ignition & Growth concept, introduced by LeeTarver in 1980, as the basis for reactive burn models. A homo- genized burn rate needs to account for three meso-scale physical effects: (i the density of active hot spots or burn centers; (ii the growth of the burn fronts triggered by the burn centers; (iii a geometric factor that accounts for the overlap of deflagration wavelets from adjacent burn centers. These effects can be combined and the burn model defined by specifying the reaction progress variable λ = g(s as a function of a dimensionless reaction length s(t = rbc/ℓbc, rather than by specifying an explicit burn rate. The length scale ℓbc(Ps = [Nbc(Ps]−1/3 is the average distance between burn centers, where Nbc is the number density of burn centers activated by the lead shock. The reaction length rbc(t = ∫t0 D(P(t′dt′ is the distance the burn front propagates from a single burn center, where D(P is the deflagration speed as a function of the local pressure and t is the time since the shock arrival. A key implementation issue is how to determine the lead shock strength in conjunction with a shock capturing scheme. We have developed a robust algorithm for this purpose based on the Hugoniot jump condition for the energy. The algorithm utilizes the time dependence of density, pressure and energy within each cell. The method is independent of the numerical dissipation used for shock capturing. It is local and can be used in one or more space dimensions. The burn model has a small number of parameters which can be calibrated to fit velocity gauge data from shock initiation experiments.

  18. Development of a Novel Non-Equilibrium Pulsed Plasma Ignition Module for High Altitude Turbojets Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An experimental research program focusing on design, development, and testing of a novel nonequilibrium plasma ignition module is proposed. The ignition module will...

  19. Laser-induced multi-point ignition for enabling high-performance engines

    KAUST Repository

    Chung, Suk-Ho

    2015-01-01

    Various multi-point laser-induced ignition techniques were reviewed, which adopted conical cavity and prechamber configurations. Up to five-point ignitions have been achieved with significant reduction in combustion duration, demonstrating potential increase in combustion system efficiency.

  20. Ignition and wave processes in combustion of solids

    CERN Document Server

    Rubtsov, Nickolai M; Alymov, Michail I

    2017-01-01

    This book focuses on the application of classical combustion theory to ignition and flame propagation in solid-solid and gas-solid systems. It presents experimental investigations in the areas of local ignition, filtration combustion, self-propagating high temperature synthesis and nanopowders protection. The authors highlight analytical formulas used in different areas of combustion in solids and propose an approach based on classical combustion theory. The book attempts to analyze the basic approaches to understanding of solid-solid and solid - gas combustion presented in contemporary literature in a unified approach based on classical combustion theory. .

  1. Optical pulse generation system for the National Ignition Facility (NIF)

    Energy Technology Data Exchange (ETDEWEB)

    Penko, F; Braucht,; Browning, D; Crane, J K; Dane, B; Deadrick, F; Dreifuerst, G; Henesian, M; Jones, B A; Kot, L; Laumann, C; Martinez, M; Moran, B; Rothenberg, J E; Skulina, K; Wilcox, R B

    1998-06-18

    We describe the Optical Pulse Generation (OPG) system for the National Ignition Facility ( NIF ). The OPG system begins with the Master Oscillator Room ( MOR ) where the initial, seed pulse for the entire laser system is produced and properly formatted to enhance ignition in the target. The formatting consists of temporally shaping the pulse and adding additional bandwidth to increase the coupling of the laser generated x-rays to the high density target plasma. The pulse produced in the MOR fans out to 48 identical preamplifier modules where it is amplified by a factor of ten billion and spatially shaped for injection into the 192 main amplifier chai

  2. Ignition of Metal Powders in Combustion Products of Model Fuel

    Science.gov (United States)

    1974-11-13

    y AD/A-001 172 IGNITION OF METAL POWDERS IN COMBUSTION PRODUCTS OF MODEL FUEL A. K. Klyauzov, et al Foreign Technology...S. Air Force UNCLASSIFIED »b. s»ouc » "I»0«T TITLE IGNITION OF METAL POWDERS IN COMBUSTION PRODUCTS OF MODEL FUEL f* OCJCPIPTIVK NOTKI (Typ* o...report mnd Inclumiv «**»••) Translation S »UTMö«I|I ( Firn tSSS», rnlddl* Inltlml, faar .tarna; A. K. Klyauzov, M. M. Arsh, et al 6

  3. Exhaust gas recirculation in a homogeneous charge compression ignition engine

    Science.gov (United States)

    Duffy, Kevin P.; Kieser, Andrew J.; Rodman, Anthony; Liechty, Michael P.; Hergart, Carl-Anders; Hardy, William L.

    2008-05-27

    A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

  4. The National Ignition Facility front-end laser system

    Energy Technology Data Exchange (ETDEWEB)

    Burkhart, S.C.; Beach, R.J.; Crane, J.H.; Davin, J.M.; Perry, M.D.; Wilcox, R.B.

    1995-07-07

    The proposed National Ignition Facility is a 192 beam Nd:glass laser system capable of driving targets to fusion ignition by the year 2005. A key factor in the flexibility and performance of the laser is a front-end system which provides a precisely formatted beam to each beamline. Each of the injected beams has individually controlled energy, temporal pulseshape, and spatial shape to accommodate beamline-to-beamline variations in gain and saturation. This flexibility also gives target designers the options for precisely controlling the drive to different areas of the target. The design of the Front-End laser is described, and initial results are discussed.

  5. Ignite HD采集和制作平台

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Thomson新推出的Ignite HD解决方案,包括Ignite SDC和HDC自动控制摄像系统。Ignite系列产品为控制室和新闻编辑室提供了完备的链路.并且使广播机构和视频制作公司利用新Kayak HD紧凑视频制作切换台,高效、节约地从SD过渡到HD。其中,Ignire HDC是全合一自动控制HD广播摄像系统。

  6. Beryllium ignition target design for indirect drive NIF experiments

    Science.gov (United States)

    Simakov, A. N.; Wilson, D. C.; Yi, S. A.; Kline, J. L.; Salmonson, J. D.; Clark, D. S.; Milovich, J. L.; Marinak, M. M.

    2016-03-01

    Beryllium (Be) ablator offers multiple advantages over carbon based ablators for indirectly driven NIF ICF ignition targets. These are higher mass ablation rate, ablation pressure and ablation velocity, lower capsule albedo, and higher thermal conductivity at cryogenic temperatures. Such advantages can be used to improve the target robustness and performance. While previous NIF Be target designs exist, they were obtained a long time ago and do not incorporate the latest improved physical understanding and models based upon NIF experiments. Herein, we propose a new NIF Be ignition target design at 1.45 MJ, 430 TW that takes all this knowledge into account.

  7. Fuzziness and Relevance Theory

    Institute of Scientific and Technical Information of China (English)

    Grace Qiao Zhang

    2005-01-01

    This paper investigates how the phenomenon of fuzzy language, such as `many' in `Mary has many friends', can be explained by Relevance Theory. It is concluded that fuzzy language use conforms with optimal relevance in that it can achieve the greatest positive effect with the least processing effort. It is the communicators themselves who decide whether or not optimal relevance is achieved, rather than the language form (fuzzy or non-fuzzy) used. People can skillfully adjust the deployment of different language forms or choose appropriate interpretations to suit different situations and communication needs. However, there are two challenges to RT: a. to extend its theory from individual relevance to group relevance; b. to embrace cultural considerations (because when relevance principles and cultural protocols are in conflict, the latter tends to prevail).

  8. Perceptions of document relevance

    Directory of Open Access Journals (Sweden)

    Peter eBruza

    2014-07-01

    Full Text Available This article presents a study of how humans perceive the relevance of documents.Humans are adept at making reasonably robust and quick decisions about what information is relevant to them, despite the ever increasing complexity and volume of their surrounding information environment. The literature on document relevance has identified various dimensions of relevance (e.g., topicality, novelty, etc., however little is understood about how these dimensions may interact.We performed a crowdsourced study of how human subjects judge two relevance dimensions in relation to document snippets retrieved from an internet search engine.The order of the judgement was controlled.For those judgements exhibiting an order effect, a q-test was performed to determine whether the order effects can be explained by a quantum decision model based on incompatible decision perspectives.Some evidence of incompatibility was found which suggests incompatible decision perspectives is appropriate for explaining interacting dimensions of relevance.

  9. Relevance Theory in Translation

    Institute of Scientific and Technical Information of China (English)

    Shao Jun; Jiang Min

    2008-01-01

    In perspective of relevance theory, translation is regarded as communication. According to relevance theory, communication not only requires encoding, transfer and decoding processes, but also involves inference in addition. As communication, translation decision-making is also based on the human beings' inferential mental faculty. Concentrating on relevance theory, this paper tries to analyze and explain some translation phenomena in two English versions of Cai Gen Tan-My Crude Philosophy of Life.

  10. Plasma Assisted Ignition at High Pressures and Low Temperatures. PAI Kinetics and Fast Gas Heating

    Science.gov (United States)

    2014-05-06

    of Scientific Research European Office of Aerospace Research and Development Unit 4515, APO AE 09421-4515 Distribution Statement A: Approved for...discharge is shown in figure 5.3. For the ICCD visualisation of the discharge, both positive and negative polarity pulses were used. Electric field

  11. Photothermal Deoxygenation of Graphene Oxide for Distributed Ignition and Patterning Applications (Postprint)

    Science.gov (United States)

    2010-01-01

    and in high efficiency homogenous charge compression ignition ( HCCI ) engines , where ignition control is of paramount importance. 15. SUBJECT TERMS... HCCI ) engine that combines the high efficiency of a diesel engine with the low emissions of a spark ignition engine . In a typical HCCI engine , fuel... engine .[40] The high compression ratio of HCCI engines provides an efficiency increase of up to 15% over traditional spark ignition engines .[41,42

  12. Storage Reliability of Missile Materiel Program. Igniters and Safe and Arm Device Analysis.

    Science.gov (United States)

    1976-05-01

    currenk is applied to the squibs which ignite the pyrogen motor. Hot gases from the pyrogen motor exhaust up the blast tube to the rocket motor...acts as a back- up in case of failure of the primary ignition spark plug. The hot gas igniter has a burn-time of 80 to 100 milliseconds. It consists of...Reliability The data collected todate indicates two separate character- istics effecting the reliability of igniters and safe and arm devices. The first

  13. Ignition et oxydation des particules de combustible solide pulvérisé Ignition and Oxidation of Pulverized Solid Fuel

    Directory of Open Access Journals (Sweden)

    De Soete G. G.

    2006-11-01

    Full Text Available On présente dans cet article, en utilisant la méthode du ruban chauffé, une étude de la compétition entre (1 la dévolatilisation et l'oxydation consécutive des produits de pyrolyse et (2 l'ignition de la matrice solide et sa combustion rapide. La comparaison entre le moment de l'ignition et le début de la pyrolyse permet de déterminer en fonction de la température, de la taille des particules et de la concentration en oxygène, le domaine dans lequel l'ignition d'un combustible solide pyrolysable est du type whole coal ignition (c'est-à-dire lorsque l'ignition intervient avant que la pyrolyse devienne mesurable. Les résultats suggèrent que ce type d'ignition doit s'effectuer en règle générale dans les conditions de mise en oeuvre des combustibles solides pulvérisés dans les flammes industrielles. Dans le cas de l'ignition whole coal , la vitesse de combustion de la matrice solide est inhibée dans la période qui suit l'ignition. Cette inhibition est due d'une part à la difficulté pour l'oxygène de diffuser dans les pores pendant la sortie des produits de pyrolyse, et d'autre part à la consommation préférentielle de l'oxygène dans l'oxydation des produits de pyrolyse, principalement dans le cas où cette oxydation se développe sous forme de flamme. Ce n'est que lorsque la pyrolyse s'achève que la vitesse de combustion hétérogène peut atteindre sa valeur stationnaire normale, qui est alors pratiquement identique à celle du coke. Aux températures situées entre la température d'ignition du combustible solide et la température d'extinction du coke résiduel, la combustion est incomplète, une extinction intervenant à un degré de dévolatilisation d'autant plus grande que la température est élevée. Ce phénomène s'explique qualitativement par la théorie classique d'ignition thermique lorsqu'on l'applique au cas particulier des combustibles solides pyrolysables. Les températures d'ignition ainsi que les d

  14. Characterizing the effects of scale and heating rate on micro-scale explosive ignition criteria.

    Energy Technology Data Exchange (ETDEWEB)

    Hafenrichter, Everett Shingo; Pahl, Robert J.

    2005-01-01

    Laser diode ignition experiments were conducted in an effort to characterize the effects of scale and heating rate on micro-scale explosive ignition criteria. Over forty experiments were conducted with various laser power densities and laser spot sizes. In addition, relatively simple analytical and numerical calculations were performed to assist with interpretation of the experimental data and characterization of the explosive ignition criteria.

  15. Photothermal Deoxygenation of Graphene Oxide to Graphitic Carbon for Distributed Ignition and Patterning Applications (Preprint)

    Science.gov (United States)

    2009-04-13

    liquid fuel rocket engines and in high efficiency homogenous charge compression ignition ( HCCI ) engines , where ignition control is of paramount importance...distributed ignition” has applications in liquid fuel rocket engines and in high efficiency homogenous charge compression ignition ( HCCI ) engines , where... HCCI engine application: Over the last decade, extraordinary effort has been undertaken to both improve the fuel efficiency in

  16. Experimental Study of Ignition over Impact-Driven Supersonic Liquid Fuel Jet

    Directory of Open Access Journals (Sweden)

    Anirut Matthujak

    2013-01-01

    Full Text Available This study experimentally investigates the mechanism of the ignition of the supersonic liquid fuel jet by the visualization. N-Hexadecane having the cetane number of 100 was used as a liquid for the jet in order to enhance the ignition potential of the liquid fuel jet. Moreover, the heat column and the high intensity CO2 laser were applied to initiate the ignition. The ignition over the liquid fuel jet was visualized by a high-speed digital video camera with a shadowgraph system. From the shadowgraph images, the autoignition or ignition of the supersonic liquid fuel jet, at the velocity of 1,186 m/s which is a Mach number relative to the air of 3.41, did not take place. The ignition still did not occur, even though the heat column or the high intensity CO2 laser was alone applied. The attempt to initiate the ignition over the liquid fuel jet was achieved by applying both the heat column and the high intensity CO2 laser. Observing the signs of luminous spots or flames in the shadowgraph would readily indicate the presence of ignitions. The mechanism of the ignition and combustion over the liquid fuel jet was clearly clarified. Moreover, it was found that the ignition over the supersonic liquid fuel jet in this study was rather the force ignition than being the auto-ignition induced by shock wave heating.

  17. FAST: FAST Analysis of Sequences Toolbox.

    Science.gov (United States)

    Lawrence, Travis J; Kauffman, Kyle T; Amrine, Katherine C H; Carper, Dana L; Lee, Raymond S; Becich, Peter J; Canales, Claudia J; Ardell, David H

    2015-01-01

    FAST (FAST Analysis of Sequences Toolbox) provides simple, powerful open source command-line tools to filter, transform, annotate and analyze biological sequence data. Modeled after the GNU (GNU's Not Unix) Textutils such as grep, cut, and tr, FAST tools such as fasgrep, fascut, and fastr make it easy to rapidly prototype expressive bioinformatic workflows in a compact and generic command vocabulary. Compact combinatorial encoding of data workflows with FAST commands can simplify the documentation and reproducibility of bioinformatic protocols, supporting better transparency in biological data science. Interface self-consistency and conformity with conventions of GNU, Matlab, Perl, BioPerl, R, and GenBank help make FAST easy and rewarding to learn. FAST automates numerical, taxonomic, and text-based sorting, selection and transformation of sequence records and alignment sites based on content, index ranges, descriptive tags, annotated features, and in-line calculated analytics, including composition and codon usage. Automated content- and feature-based extraction of sites and support for molecular population genetic statistics make FAST useful for molecular evolutionary analysis. FAST is portable, easy to install and secure thanks to the relative maturity of its Perl and BioPerl foundations, with stable releases posted to CPAN. Development as well as a publicly accessible Cookbook and Wiki are available on the FAST GitHub repository at https://github.com/tlawrence3/FAST. The default data exchange format in FAST is Multi-FastA (specifically, a restriction of BioPerl FastA format). Sanger and Illumina 1.8+ FastQ formatted files are also supported. FAST makes it easier for non-programmer biologists to interactively investigate and control biological data at the speed of thought.

  18. FAST: FAST Analysis of Sequences Toolbox

    Directory of Open Access Journals (Sweden)

    Travis J. Lawrence

    2015-05-01

    Full Text Available FAST (FAST Analysis of Sequences Toolbox provides simple, powerful open source command-line tools to filter, transform, annotate and analyze biological sequence data. Modeled after the GNU (GNU’s Not Unix Textutils such as grep, cut, and tr, FAST tools such as fasgrep, fascut, and fastr make it easy to rapidly prototype expressive bioinformatic workflows in a compact and generic command vocabulary. Compact combinatorial encoding of data workflows with FAST commands can simplify the documentation and reproducibility of bioinformatic protocols, supporting better transparency in biological data science. Interface self-consistency and conformity with conventions of GNU, Matlab, Perl, BioPerl, R and GenBank help make FAST easy and rewarding to learn. FAST automates numerical, taxonomic, and text-based sorting, selection and transformation of sequence records and alignment sites based on content, index ranges, descriptive tags, annotated features, and in-line calculated analytics, including composition and codon usage. Automated content- and feature-based extraction of sites and support for molecular population genetic statistics makes FAST useful for molecular evolutionary analysis. FAST is portable, easy to install and secure thanks to the relative maturity of its Perl and BioPerl foundations, with stable releases posted to CPAN. Development as well as a publicly accessible Cookbook and Wiki are available on the FAST GitHub repository at https://github.com/tlawrence3/FAST. The default data exchange format in FAST is Multi-FastA (specifically, a restriction of BioPerl FastA format. Sanger and Illumina 1.8+ FastQ formatted files are also supported. FAST makes it easier for non-programmer biologists to interactively investigate and control biological data at the speed of thought.

  19. Making Science Relevant

    Science.gov (United States)

    Eick, Charles; Deutsch, Bill; Fuller, Jennifer; Scott, Fletcher

    2008-01-01

    Science teachers are always looking for ways to demonstrate the relevance of science to students. By connecting science learning to important societal issues, teachers can motivate students to both enjoy and engage in relevant science (Bennet, Lubben, and Hogarth 2007). To develop that connection, teachers can help students take an active role in…

  20. Polar Direct Drive--Simulations and Results from OMEGA and the National Ignition Facility

    Science.gov (United States)

    Radha, P. B.

    2015-11-01

    Polar direct drive (PDD) is a valuable platform to study implosion dynamics at the National Ignition Facility (NIF). While hydrodynamic behavior is expected to scale between OMEGA and the NIF, coronal laser-plasma interactions that influence drive and shell preheat are expected to be different because of the larger coronal density scale lengths characteristic of the NIF. The goal of NIF experiments is to validate physics models (e.g., thermal transport and laser-plasma interactions relevant to energy coupling) at these longer scale lengths to gain confidence in hydrodynamic simulations of direct-drive implosions. Models in the hydrodynamic code DRACO, validated using OMEGA implosions, are used to design and interpret NIF experiments. The physics in these models, including cross-beam energy transfer and nonlocal transport, is discussed. Comparisons with observations including shell and ablation surface trajectory, temporally resolved scattered light and spectra, bang time, shell shape, time-resolved x-ray emission, and areal density are presented from OMEGA and NIF experiments. Excellent agreement is obtained on the backlit shell trajectories and scattered light, providing confidence in the modeling of the laser drive at the longer scale. Possible reasons for the discrepancy in the predicted trajectory of the ablation surface are discussed and planned experiments to address issues such as imprint and shock timing are presented. As will be shown, high-convergence implosions should be possible with custom phase plates relevant to PDD, improved single-beam smoothing, and laser pulse shaping. Such implosions are a necessary step toward a future direct-drive -ignition campaign. A path forward for direct drive on the NIF is presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. Effects of the injected trigger pulse focusing and timing on the ignition and gain of dense static, or imploding DT fuel

    Science.gov (United States)

    Caruso, Angelo; Pais, Vicente A.

    1998-07-01

    We discuss two issues relevant for the feasibility of the scheme in which a heavy ion pulse is used to ignite a DT fuel spherically compressed, by laser induced ablation, along a low adiabat (no self-ignition). The discussed issues are (i) the degree of synchronism between the laser driven implosion and the trigger pulse; (ii) the requirements on focusing for the trigger beam. The numerical simulation have been made by using cylindrical heavy ion beams with gaussian radial distribution, truncated where the intensity is {1}/{e-4} of the maximum. The parameter ( dbeam), used to measure the focusing, is the diameter of the circle where the intensity is {1}/{e} of the maximum (energy content ≈ 64% of the total energy). Requirements on focusing have been first explored by simulating (2D) the irradiation of static DT cylinders at 200 g/cm 3 by coaxially impinging 15 GeV Bi ions. The ignition conditions have been studied for pulses having 10 ps or 50 ps duration. For both the cases, the ignition energy ( Emin) is constant for spot radii smaller than 50 μm. In the range 50-140 μm the ignition energy increases linearly (3 × Emin at 140 μm, with Emin = 40 kJ for 10 ps pulses, Emin = 100 kJ for 50 ps pulses). The study on synchronism has been performed by simulating (2D) the irradiation, by a heavy ion beam, of a laser imploded spherical DT shell (initial aspect ratio 10). The trigger beam was started at different times near the stagnation, and the initial fuel state (field of velocity, density, temperature, etc.) was that computed by a 1D simulation. It has been found that ignition, and almost constant thermonuclear energy release, can be obtained by triggering within a temporal window of the order of 1 ns, around the stagnation. The interplay between focusing and synchronization for the ignition of the spherical imploding fuel has also been studied. The heavy ion pulse duration was maintained constant at 50 ps (FWHM). Ignition conditions have been studied for trigger

  2. Ignition delay time measurements of primary reference fuel blends

    KAUST Repository

    Alabbad, Mohammed

    2017-02-07

    Ignition delay times of four different primary reference fuels (PRF), mixtures of n-heptane and iso-octane, were measured behind reflected shock waves in a high-pressure shock tube facility. The PRFs were formulated to match the RON of two high-octane gasolines (RON 95 and 91) and two prospective low-octane naphtha fuels (RON 80 and 70). Experiments were carried out over a wide range of temperatures (700–1200K), pressures (10, 20, and 40bar) and equivalence ratios (0.5 and 1). Kinetic modeling predictions from four chemical kinetic mechanisms are compared with the experimental data. Ignition delay correlations are developed to reproduce the measured ignition delay times. Brute force sensitivity analyses are carried out to identify reactions that affect ignition delay times at specific temperature, pressure and equivalence ratio. The large experimental data set provided in the current work will serve as a benchmark for the validation of chemical kinetic mechanisms of primary reference fuel blends.

  3. Electric ignition and airless kindle for underfeed stokers

    Energy Technology Data Exchange (ETDEWEB)

    Crowther, M.E. [CRE Group Ltd., Stoke Orchard (United Kingdom)

    1996-02-01

    The leaflet describes a project carried out to assess the effectiveness and reliability of two methods of reducing the amount of coal used for kindling on boilers fitted with underfeed stokers. Many coal-fired boilers use underfeed stokers to deliver their fuel. When heat is not required, the stoker is put into standby `kindle` mode, and the fire kept alight by the periodic delivery of small amounts of coal and air. CRE Group Ltd., assessed two techniques for reducing the fuel used for kindling: electric ignition and airless kindle. Electric ignition eliminates entirely the need for kindling by automatically re-igniting the coal in the stoker retort using a hot air jet. CRE Group`s development work aimed to overcome earlier design problems and improve cost-effectiveness and reliability. Airless kindle reduces the size and frequency of coal feed in kindle mode. Although it does not entirely eliminate the use of kindle, it saves almost as much fuel for a lower capital outlay and minimal maintenance costs. This option has proved so attractive to the host organisations (Derbyshire Country Council, Nottinghamshire Country Council and Haven Nurseries) that the boiler used for trials for the electric ignition system has now been converted to airless kindle. 3 figs., 4 photos.

  4. Computational Modeling in Support of the National Ignition Facilty Operations

    CERN Document Server

    Shaw, M J; Haynam, C A; Williams, W H

    2001-01-01

    Numerical simulation of the National Ignition Facility (NIF) laser performance and automated control of the laser setup process are crucial to the project's success. These functions will be performed by two closely coupled computer code: the virtual beamline (VBL) and the laser performance operations model (LPOM).

  5. Computational Modeling in Support of National Ignition Facility Operations

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M J; Sacks, R A; Haynam, C A; Williams, W H

    2001-10-23

    Numerical simulation of the National Ignition Facility (NIF) laser performance and automated control of laser setup process are crucial to the project's success. These functions will be performed by two closely coupled computer codes: the virtual beamline (VBL) and the laser operations performance model (LPOM).

  6. Knock Prediction Using a Simple Model for Ignition Delay

    KAUST Repository

    Kalghatgi, Gautam

    2016-04-05

    An earlier paper has shown the ability to predict the phasing of knock onset in a gasoline PFI engine using a simple ignition delay equation for an appropriate surrogate fuel made up of toluene and PRF (TPRF). The applicability of this approach is confirmed in this paper in a different engine using five different fuels of differing RON, sensitivity, and composition - including ethanol blends. An Arrhenius type equation with a pressure correction for ignition delay can be found from interpolation of previously published data for any gasoline if its RON and sensitivity are known. Then, if the pressure and temperature in the unburned gas can be estimated or measured, the Livengood-Wu integral can be estimated as a function of crank angle to predict the occurrence of knock. Experiments in a single cylinder DISI engine over a wide operating range confirm that this simple approach can predict knock very accurately. The data presented should enable engineers to study knock or other auto-ignition phenomena e.g. in premixed compression ignition (PCI) engines without explicit chemical kinetic calculations. © Copyright 2016 SAE International.

  7. Utilization of Alcohol Fuel in Spark Ignition and Diesel Engines.

    Science.gov (United States)

    Berndt, Don; Stengel, Ron

    These five units comprise a course intended to prepare and train students to conduct alcohol fuel utilization seminars in spark ignition and diesel engines. Introductory materials include objectives and a list of instructor requirements. The first four units cover these topics: ethanol as an alternative fuel (technical and economic advantages,…

  8. Optimization of the process of plasma ignition of coal

    Energy Technology Data Exchange (ETDEWEB)

    Peregudov, V.S. [Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2009-04-15

    Results are given of experimental and theoretical investigations of plasma ignition of coal as a result of its thermochemical preparation in application to the processes of firing up a boiler and stabilizing the flame combustion. The experimental test bed with a commercial-scale burner is used for determining the conditions of plasma ignition of low-reactivity high-ash anthracite depending on the concentration of coal in the air mixture and velocity of the latter. The calculations produce an equation (important from the standpoint of practical applications) for determining the energy expenditure for plasma ignition of coal depending on the basic process parameters. The tests reveal the difficulties arising in firing up a boiler with direct delivery of pulverized coal from the mill to furnace. A scheme is suggested, which enables one to reduce the energy expenditure for ignition of coal and improve the reliability of the process of firing up such a boiler. Results are given of calculation of plasma thermochemical preparation of coal under conditions of lower concentration of oxygen in the air mixture.

  9. Real fuel effects on flame extinction and re-ignition

    Science.gov (United States)

    Zhao, Xinyu; Wu, Bifen; Xu, Chao; Lu, Tianfeng; Chen, Jacqueline H.

    2016-11-01

    Flame-vortex interactions have significant implications in studying combustion in practical aeronautical engines, and can be used to facilitate the model development in capturing local extinction and re-ignition. To study the interactions between the complex fuel and the intense turbulence that are commonly encountered in engines, direct numerical simulations of the interactions between a flame and a vortex pair are carried out using a recently-developed 24-species reduced chemistry for n-dodecane. Both non-premixed and premixed flames with different initial and inlet thermochemical conditions are studied. Parametric studies of different vortex strengths and orientations are carried out to induce maximum local extinction and re-ignition. Chemical-explosive-mode-analysis based flame diagnostic tools are used to identify different modes of combustion, including auto-ignition and extinction. Results obtained from the reduced chemistry are compared with those obtained from one-step chemistry to quantify the effect of fuel pyrolysis on the extinction limit. Effects of flame curvature, heat loss and unsteadiness on flame extinction are also explored. Finally, the validity of current turbulent combustion models to capture the local extinction and re-ignition will be discussed.

  10. Modeling spatio-temporal wildfire ignition point patterns

    Science.gov (United States)

    Amanda S. Hering; Cynthia L. Bell; Marc G. Genton

    2009-01-01

    We analyze and model the structure of spatio-temporal wildfire ignitions in the St. Johns River Water Management District in northeastern Florida. Previous studies, based on the K-function and an assumption of homogeneity, have shown that wildfire events occur in clusters. We revisit this analysis based on an inhomogeneous K-...

  11. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Science.gov (United States)

    2010-07-01

    ...-constantan or chromelalumel—and a potentiometer shall be used for all temperature measurements. (3) Syringe...) Temperature control. Each autotransformer shall be so adjusted that the temperature at the neck, mid-section... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Autogenous-ignition temperature test....

  12. 49 CFR 192.751 - Prevention of accidental ignition.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Prevention of accidental ignition. 192.751 Section 192.751 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS... NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Maintenance § 192.751 Prevention...

  13. Laser diode ignition characteristics of Zirconium Potassium Perchlorate (ZPP)

    Science.gov (United States)

    Callaghan, Jerry D.; Tindol, Scot

    1993-01-01

    Hi-Shear Technology, Corp., (HSTC) has designed and built a Laser equivalent NASA Standard Initiator (LNSI). Langlie tests with a laser diode output initiating ZPP were conducted as a part of this effort. The test parameters include time to first pressure, laser power density requirements, and ignition time. The data from these laser tests on ZPP are presented.

  14. Railplug Ignition System for Enhanced Engine Performance and Reduced Maintenance

    Energy Technology Data Exchange (ETDEWEB)

    DK Ezekoye; Matt Hall; Ron Matthews

    2005-08-01

    This Final Technical Report discusses the progress that was made on the experimental and numerical tasks over the duration of this project. The primary objectives of the project were to (1) develop an improved understanding of the spark ignition process, and (2) develop the railplug as an improved ignitor for large bore stationary natural gas engines. We performed fundamental experiments on the physical processes occurring during spark ignition and used the results from these experiments to aid our development of the most complete model of the spark ignition process ever devised. The elements in this model include (1) the dynamic response of the ignition circuit, (2) a chemical kinetics mechanism that is suitable for the reactions that occur in the plasma, (3) conventional flame propagation kinetics, and (4) a multi-dimensional formulation so that bulk flow through the spark gap can be incorporated. This model (i.e., a Fortran code that can be used as a subroutine within an engine modeling code such as KIVA) can be obtained from Prof. Ron Matthews at rdmatt{at}mail.utexas.edu or Prof. DK Ezekoye at dezekoye{at}mail.utexas.edu. Fundamental experiments, engine experiments, and modeling tasks were used to help develop the railplug as a new ignitor for large bore natural gas engines. As the result of these studies, we developed a railplug that could extend the Lean Stability Limit (LSL) of an engine operating at full load on natural gas from {phi} = 0.59 for operation on spark plugs down to {phi} = 0.53 using railplugs with the same delivered energy (0.7 J). However, this delivered energy would rapidly wear out the spark plug. For a conventional delivered energy (<0.05 J), the LSL is {phi} = 0.63 for a spark plug. Further, using a permanent magnet to aid the plasma movement, the LSL was extended to {phi} = 0.54 for a railplug with a delivered energy of only 0.15 J/shot, a typical discharge energy for commercial capacitive discharge ignition systems. Here, it should be

  15. Measuring fast electron distribution functions at intensities up to 10{sup 21} W cm{sup -2}

    Energy Technology Data Exchange (ETDEWEB)

    Booth, N., E-mail: nicola.booth@stfc.ac.uk [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QN (United Kingdom); Clarke, R.J. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QN (United Kingdom); Doria, D. [Department of Physics and Mathematics, Queen' s University Belfast, Belfast BT1 4NN (United Kingdom); Gizzi, L.A. [ILIL-IPCF, Consiglio Nazionale delle Richerche, Pisa (Italy); Gregori, G. [Department of Physics, University of Oxford OX4 1PJ (United Kingdom); Hakel, P. [Department of Physics, College of Science, University of Nevada, Reno, NV 89557-0208 (United States); Koester, P.; Labate, L.; Levato, T. [ILIL-IPCF, Consiglio Nazionale delle Richerche, Pisa (Italy); Li, B. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QN (United Kingdom); Makita, M. [Department of Physics and Mathematics, Queen' s University Belfast, Belfast BT1 4NN (United Kingdom); Mancini, R.C. [Department of Physics, College of Science, University of Nevada, Reno, NV 89557-0208 (United States); Pasley, J. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QN (United Kingdom); Rajeev, P.P. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QN (United Kingdom); Riley, D. [Department of Physics and Mathematics, Queen' s University Belfast, Belfast BT1 4NN (United Kingdom); Robinson, A.P.L. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QN (United Kingdom); Wagenaars, E.; Waugh, J.N.; Woolsey, N.C. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)

    2011-10-11

    Here we present results from ultra-intense experiments demonstrating the viability of polarization spectroscopy as a diagnostic of the electron return current and spatial anisotropy and distribution function of the fast electron beam. The measurements extend to ultra-relativistic intensities of 10{sup 21} W cm{sup -2}, including laser-plasma interaction regimes important for fast ignition studies, for example HiPER, and the development of secondary sources from next generation ultra-short pulse, ultra-intense laser facilities such as Astra-Gemini and ELI. As an in situ diagnostic, spectroscopic measurements are vital to understanding fast electron beams, enabling extrapolation of results to define fast ignition inertial confinement fusion and secondary source facilities.

  16. Real-time study of fast-electron transport inside dense hot plasmas.

    Science.gov (United States)

    Sandhu, A S; Ravindra Kumar, G; Sengupta, S; Das, A; Kaw, P K

    2006-03-01

    We offer a method to study transport of fast electrons in dense hot media. The technique relies on temporal profiling of the laser induced magnetic fields and offers a unique capability to map the hot electron currents and their neutralization (or lack of it) by the return currents in the plasma. We report direct quantitative measurements of strong electric inhibition in insulators and turbulence induced anomalous stopping of hot electrons in conductors. The present technique can prove extremely important from the point of view of fast ignition scheme, which relies on the penetration of fast electrons into the fusion core.

  17. Kinetics of plasma-assisted combustion: effect of non-equilibrium excitation on the ignition and oxidation of combustible mixtures

    Science.gov (United States)

    Popov, N. A.

    2016-08-01

    A review of experimental and theoretical investigations of the effect of atomic particles, and electronically and vibrationally excited molecules on the induction delay time and on the shift in the ignition temperature threshold of combustible mixtures is presented. The addition of oxygen and hydrogen atoms to combustible mixtures may cause a significant reduction in the ignition delay time. However, at relatively low initial temperatures, the non-equilibrium effect of the addition of atomic particles in ground electronic states is not pronounced. At the same time, the effect of excited O(1D) atoms on the oxidation and reforming of combustible mixtures is quite significant due to the high rates of reactions of O(1D) atoms with hydrogen and hydrocarbon molecules. In fuel-air mixtures, collisions with O(1D) atoms determine, under certain conditions, the dissociation of hydrocarbon molecules. Singlet oxygen molecules, O2(a1Δ g ), participate both in chain initiation and chain branching reactions, but the effect of O2(a1Δ g ) on the ignition processes is generally less important compared to oxygen atoms. The reactions of vibrationally excited molecules and the processes of VT-relaxation in combustible mixtures are discussed. The production of vibrationally excited N 2(v) molecules in fuel-air mixtures at relatively low electric field is very important. However, at the moment, the effect of the reactions of N 2(v) molecules on the oxidation and ignition of combustible mixtures is not completely clear, and requires further investigation. Therefore, with present knowledge, to reduce the ignition delay time and decrease the temperature threshold of combustive mixtures, the use of gas discharge systems with relatively high E/N values is recommended. In this case the reactions of electronically excited {{\\text{N}}2}≤ft(\\text{A}{}3Σu+,\\text{B}{}3{{\\Pi}g},\\text{C}{}3{{\\Pi}u},\\text{a}{}\\prime 1Σu-\\right) molecules, and atomic particles in ground and

  18. Are Published Minimum Vapor Phase Spark Ignition Energy Data Valid?

    Energy Technology Data Exchange (ETDEWEB)

    Staggs, K J; Alvares, N J; Greenwood, D W

    2001-11-21

    The use of sprayed flammable fluids as solvents in dissolution and cleaning processes demand detailed understanding of ignition and fire hazards associated with these applications. When it is not feasible to inert the atmosphere in which the spraying process takes place, then elimination of all possible ignition sources must be done. If operators are involved in the process, the potential for human static build-up and ultimate discharge is finite, and it is nearly impossible to eliminate. The specific application discussed in this paper involved the use of heated Dimethyl Sulfoxide (DMSO) to dissolve high explosives (HE). Search for properties of DMSO yielded data on flammability limits and flash point, but there was no published information pertaining to the minimum energy for electrical arc ignition. Due to the sensitivity of this procedure, The Hazards Control Department of Lawrence Livermore National Laboratory (LLNL) was tasked to determine the minimum ignition energy of DMSO aerosol and vapor an experimental investigation was thus initiated. Because there were no electrical sources in spray chamber, Human Electro-Static Discharge (HESD) was the only potential ignition source. Consequently, the electrostatic generators required for this investigation were designed to produce electrostatic arcs with the defined voltage and current pulse characteristics consistent with simulated human capacitance. Diagnostic procedures required to insure these characteristics involve specific data gathering techniques where the voltage and current sensors are in close proximity to the electrodes, thus defining the arc energy directly between the electrodes. The intriguing finding derived from this procedure is how small these measured values are relative to the arc energy as defined by the capacitance and the voltage measure at the capacitor terminals. The suggested reason for this difference is that the standard procedure for determining arc energy from the relation; E = 1/2CV

  19. Safety Implementation of Hydrogen Igniters and Recombiners for Nuclear Power Plant Severe Accident Management

    Institute of Scientific and Technical Information of China (English)

    XIAO Jianjun; ZHOU Zhiwei; JING Xingqing

    2006-01-01

    Hydrogen combustion in a nuclear power plant containment building may threaten the integrity of the containment. Hydrogen recombiners and igniters are two methods to reduce hydrogen levels in containment buildings during severe accidents. The purpose of this paper is to evaluate the safety implementation of hydrogen igniters and recombiners. This paper analyzes the risk of deliberate hydrogen ignition and investigates three mitigation measures using igniters only, hydrogen recombiners only or a combination of recombiners and igniters. The results indicate that steam can effectively control the hydrogen flame acceleration and the deflagration-to-detonation transition.

  20. Possible version of the compression degradation of the thermonuclear indirect-irradiation targets at the national ignition facility and a reason for the failure of ignition

    Energy Technology Data Exchange (ETDEWEB)

    Rozanov, V. B., E-mail: rozanov@sci.lebedev.ru; Vergunova, G. A., E-mail: verg@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-01-15

    The main parameters of compression of a target and tendencies at change in the irradiation conditions are determined by analyzing the published results of experiments at the megajoule National Ignition Facility (NIF) on the compression of capsules in indirect-irradiation targets by means of the one-dimensional RADIAN program in the spherical geometry. A possible version of the “failure of ignition” of an indirect-irradiation target under the NIF conditions is attributed to radiation transfer. The application of onedimensional model to analyze the National Ignition Campaign (NIC) experiments allows identifying conditions corresponding to the future ignition regime and distinguishing them from conditions under which ignition does not occur.

  1. Comparison of Plasticity Index of Søvind Marl found by use of Casagrande Cup, Fall Cone apparatus and Loss on Ignition

    DEFF Research Database (Denmark)

    Grønbech, Gitte; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    organic materials has been suggested as a new and fast way to classify clay and determine the plasticity index up to an Ip of 60 %. A serie of tests using traditional means, the Casagrande Cup, and Loss on Ignition have been carried out, and the results are compared, to assess whether this method can...... shown in numerous papers. However the comparability is still fairly undocumented on the plastic danish tertiary clay, like the Søvind Marl. Based on a serie of tests carried out on Søvind Marl, the liquid limit from the Casagrande Cup and the Fall Cone apparatus are compared. The Loss on Ignition on non......The Casagrande Cup method has been the preferred method of finding the liquid limit in Denmark for many years. It is however stated by the Danish Standards Association, that the Fall Cone test, is to be preferred when possible. The comparability of the Casagrande and the Fall Cone method has been...

  2. Ignition models and simulation of solid propellant of thermodynamic undersea vehicle

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jin-jun; QIAN Zhi-bo; YANG Jie; YAN Ping

    2007-01-01

    The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is necessary to establish accurate burning models for solid propellants. Based on combustion models using powder tings and two different solid ignition grains, namely star-shaped ignition grains and stuffed ignition grains, a mathematic model of the ignition process of the propulsion system was built.With the help of Matlah, a series of calculations were made to determine the effects of different grains on ignition characteristics. The results show that stuffed ignition grain is best suited to be the ignition grain of a thermodynamic undersea vehicle system.

  3. Characterization of semiconductor bridges (SCB) igniters for use in thermal batteries

    Energy Technology Data Exchange (ETDEWEB)

    Bickes, R.W.; Guidotti, R.A. [Sandia National Labs., Albuquerque, NM (United States); McCampbell, C.B. [SCB Technologies, Inc., Albuquerque, NM (United States)

    1996-05-01

    Semiconductor bridges (SCB) igniters were evaluated as possible replacements for conventional hot-wire igniters for use in thermal batteries. The all-fire and no-fire characteristics were determined using an up-down scheme; the Neyer/SENSIT program was used to analyze the data. The SCB igniters functioned with a higher no-fire level, relative to a hot-wire igniter, for a given all-fire level. This makes the SCB igniter safer and more reliable than its hot-wire counterpart. The SCB is very resistant to electrostatic discharge and does not require a sensitization mixture for ignition of the primary pyrotechnic charge. These factors, along with its amenability to large-scale production, make the SCB igniter ideally suited for use in thermal batteries.

  4. Enhanced combustion by jet ignition in a turbocharged cryogenic port fuel injected hydrogen engine

    Energy Technology Data Exchange (ETDEWEB)

    Boretti, Alberto A.; Watson, Harry C. [Department of Mechanical Engineering, The University of Melbourne, 3010 Melbourne (Australia)

    2009-03-15

    The Hydrogen Assisted Jet Ignition (HAJI) is a physico-chemical combustion enhancement system developed at the University of Melbourne. Jet ignition can ignite ultra-lean air/fuel mixtures which are far beyond the stable ignition limit of a spark plug. Jet ignition may further enhance the combustion properties of hydrogen enabling the development of a diesel-like, almost throttle-less, control of load by quantity of fuel injected for higher thermal efficiencies all over the range of loads. The object of this paper is to show the benefits of jet ignition and present the latest results obtained on a four cylinder engine having the jet ignition coupled with cryogenic hydrogen injection and turbo charging. (author)

  5. Ignition characteristics of forest species in relation to thermal analysis data

    Energy Technology Data Exchange (ETDEWEB)

    Liodakis, S.; Bakirtzis, D. [Laboratory of Inorganic and Analytical Chemistry, Department of Chemical Engineering, National Technical University of Athens (NTUA), 9 Iroon Polytecniou Street, 157 73 Athens (Greece); Dimitrakopoulos, A. [Laboratory of Forest Protection, Department of Forestry and Natural Environment, Aristotle University, P.O. Box 228, 540 06 Thessaloniki (Greece)

    2002-07-15

    The ignitability of various forest species was measured with a specifically designed apparatus, under precisely controlled temperature and airflow conditions. The ignitability tests were based on ignition delay time versus temperature measurements using five different forest species: Pinus halepensis, Pistacia lentiscus, Cupressus sempervirens, Olea europaea, Cistus incanus. These species are common in the Mediterranean region and frequently devastated by forest fires. The ignition characteristics of the forest fuels examined were related to thermogravimetric analysis data. The DTG curves showed that the mass changes related to cellulose decomposition in the temperature range of 320-370C are greatly responsible for the ignition behavior of the species tested. In addition, the mass of volatiles evolving between 120-160C has a significant effect on the ignitability. On the contrary, the inorganic ash content of forest fuels, measured by atomic absorption spectroscopy, seems to play an insignificant role on the ignitability characteristics of the forest fuels examined.

  6. Cyclic Combustion Variations in Dual Fuel Partially Premixed Pilot-Ignited Natural Gas Engines

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, K. K. [Mississippi State Univ., MS (United States). Dept. of Mechanical Engineering; Krishnan, S. R. [Mississippi State Univ., MS (United States). Dept. of Mechanical Engineering; Qi, Y. [Caterpillar, Inc., Peoria, IL (United States)

    2012-05-09

    Dual fuel pilot ignited natural gas engines are identified as an efficient and viable alternative to conventional diesel engines. This paper examines cyclic combustion fluctuations in conventional dual fuel and in dual fuel partially premixed low temperature combustion (LTC). Conventional dual fueling with 95% (energy basis) natural gas (NG) substitution reduces NOx emissions by almost 90%t relative to straight diesel operation; however, this is accompanied by 98% increase in HC emissions, 10 percentage points reduction in fuel conversion efficiency (FCE) and 12 percentage points increase in COVimep. Dual fuel LTC is achieved by injection of a small amount of diesel fuel (2-3 percent on an energy basis) to ignite a premixed natural gas₋air mixture to attain very low NOx emissions (less than 0.2 g/kWh). Cyclic variations in both combustion modes were analyzed by observing the cyclic fluctuations in start of combustion (SOC), peak cylinder pressures (Pmax), combustion phasing (Ca50), and the separation between the diesel injection event and Ca50 (termed "relative combustion phasing" ). For conventional dual fueling, as % NG increases, Pmax decreases, SOC and Ca50 are delayed, and cyclic variations increase. For dual fuel LTC, as diesel injection timing is advanced from 20° to 60° BTDC, the relative combustion phasing is identified as an important combustion parameter along with SoC, Pmax, and CaPmax. For both combustion modes, cyclic variations were characterized by alternating slow and fast burn cycles, especially at high %NG and advanced injection timings. Finally, heat release return maps were analyzed to demonstrate thermal management strategies as an effective tool to mitigate cyclic combustion variations, especially in dual fuel LTC.

  7. Criticisms of Relevance Theory

    Institute of Scientific and Technical Information of China (English)

    尚静; 孟晔; 焦丽芳

    2006-01-01

    This paper briefly introduces first the notion of Sperber and Wilson's Relevance Theory. Then, the motivation of S & W putting forward their RT is also mentioned. Secondly, the paper gives some details about the methodology of RT, in which ostensive-inferential communication, context and optimal relevance are highlighted. Thirdly, the paper focuses on the criticisms of RT from different areas of research on human language and communication. Finally, the paper draws a conclusion on the great importance of RT in pragmatics.

  8. Ramadan fasting: Do we need more evidence?

    Directory of Open Access Journals (Sweden)

    Mohsen Nematy

    2015-03-01

    Full Text Available Over a billion of Muslims fast worldwide during Ramadan each year. Through this religious custom, fasting contributes to their health as well as their spiritual growth. However, available evidence regarding the health-benefits of Ramadan fasting is scarce and highly contentious. Although Islam exempts patients from fasting, many fast conceivably, and their clinical condition is prone to deteriorate due to persistent gap between current expert knowledge and conclusive strong evidence regarding the pathophysiologic and metabolic alterations of fasting and the consensus that should be taken into account to implements guided managing of various patient groups during Ramadan fasting among health care professionals. In this article, we summarized the results of initial studies regarding the effects of Ramadan fasting on some clinical conditions including alterations of body composition and clinically important outcomes of patients with a previous history of cardiovascular disease, asthma and renal colic disease. Our studies have shed light on several outcomes in favor of Ramadan fasting, and encourage those with mentioned diseases to consult their physicians and follow medical and scientific recommendations. In this review we aimed to present a piece of relevant evidence, clarify future scope and provide suggestions for future investigations.

  9. Correlation between self-ignition of a dust layer on a hot surface and in baskets in an oven

    OpenAIRE

    2008-01-01

    International audience; Evaluation of self-ignition hazard of bulk materials requires experimental determination of self-ignition temperatures as a function of volume. There are two standardised methods : determination of the self-ignition temperature of dust samples in oven and measurement of the self-ignition temperature of a dust layer deposited on a hot surface. Sometimes, the sample behaviour during these tests makes the second method difficult to apply. The self-ignition phenomena in th...

  10. The National Ignition Facility: Enabling Fusion Ignition for the 21st Century

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E I; Miller, G H; Wuest, C R

    2004-09-17

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, when completed in 2008, will contain a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter-diameter target chamber and room for 100 diagnostics. NIF is housed in a 26,000 square meter environmentally controlled building and is the world's largest and most energetic laser experimental system. NIF provides a scientific center for the study of inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} bar; conditions that exist naturally only in the interior of stars and planets. NIF is currently configured with four laser beams activated in late 2002. These beams are being regularly used for laser performance and physics experiments and to date nearly 250 system shots have been conducted. NIF's laser beams have generated 106 kilojoules in 23-ns pulses of infrared light and over 16 kJ in 3.5-ns pulses at the third harmonic (351 nm). A number of target experimental systems are being commissioned in support of experimental campaigns. This paper provides a detailed look the NIF laser systems, laser and optical performance, and results from laser commissioning shots. We also discuss NIF's high -energy density and inertial fusion experimental capabilities, the first experiments on NIF, and plans for future capabilities of this unique facility.

  11. The Limits to Relevance

    Science.gov (United States)

    Averill, M.; Briggle, A.

    2006-12-01

    Science policy and knowledge production lately have taken a pragmatic turn. Funding agencies increasingly are requiring scientists to explain the relevance of their work to society. This stems in part from mounting critiques of the "linear model" of knowledge production in which scientists operating according to their own interests or disciplinary standards are presumed to automatically produce knowledge that is of relevance outside of their narrow communities. Many contend that funded scientific research should be linked more directly to societal goals, which implies a shift in the kind of research that will be funded. While both authors support the concept of useful science, we question the exact meaning of "relevance" and the wisdom of allowing it to control research agendas. We hope to contribute to the conversation by thinking more critically about the meaning and limits of the term "relevance" and the trade-offs implicit in a narrow utilitarian approach. The paper will consider which interests tend to be privileged by an emphasis on relevance and address issues such as whose goals ought to be pursued and why, and who gets to decide. We will consider how relevance, narrowly construed, may actually limit the ultimate utility of scientific research. The paper also will reflect on the worthiness of research goals themselves and their relationship to a broader view of what it means to be human and to live in society. Just as there is more to being human than the pragmatic demands of daily life, there is more at issue with knowledge production than finding the most efficient ways to satisfy consumer preferences or fix near-term policy problems. We will conclude by calling for a balanced approach to funding research that addresses society's most pressing needs but also supports innovative research with less immediately apparent application.

  12. Inertial Confinement Fusion and the National Ignition Facility (NIF)

    Energy Technology Data Exchange (ETDEWEB)

    Ross, P.

    2012-08-29

    Inertial confinement fusion (ICF) seeks to provide sustainable fusion energy by compressing frozen deuterium and tritium fuel to extremely high densities. The advantages of fusion vs. fission are discussed, including total energy per reaction and energy per nucleon. The Lawson Criterion, defining the requirements for ignition, is derived and explained. Different confinement methods and their implications are discussed. The feasibility of creating a power plant using ICF is analyzed using realistic and feasible numbers. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is shown as a significant step forward toward making a fusion power plant based on ICF. NIF is the world’s largest laser, delivering 1.8 MJ of energy, with a peak power greater than 500 TW. NIF is actively striving toward the goal of fusion energy. Other uses for NIF are discussed.

  13. Inertial fusion target development for ignition and energy

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, K.R. [General Atomics, San Diego, CA (United States); Norimatsu, T. [Osaka Univ. (Japan). Inst. of Laser Engineering

    1994-12-01

    The target needs of the next ICF experiments that will lead toward ignition and energy are different from those of today`s experiments. The future experiments on OMEGA Upgrade, GEKKO XII Upgrade, the National Ignition Facility and Megajoule will need large, precise, cryogenic targets. Development is needed on a number of aspects of these targets, including shell fabrication, characterization, cryogenic layering and target handling. However, coordinated R and D programs are in place and work is in process to carry out the needed development. It is vital to the success of inertial fusion that this work be sustained. Coordinated effort, like the National Cryogenic Target Program in the USA, will help make the development activities as efficient and effective as possible, and should be encouraged.

  14. Application of Dimethyl Ether in Compression Ignition Engines

    DEFF Research Database (Denmark)

    Hansen, Kim Rene

    -Marathon. The diesel engine test results from 1995 showed that DME is a superb diesel fuel. DME is easy to ignite by compression ignition and it has a molecular structure that results in near-zero emission of particulates when burned. These are features of a fuel that are highly desirable in a diesel engine....... The challenges with DME as a diesel engine fuel are mainly related to poor lubricity and incompatibility with a range of elastomers commonly used for seals in fuel injection systems. This means that although DME burns well in a diesel engine designing a fuel injection system for DME is challenging. Since...... then studies have revealed that the injection pressure for DME does not have to be as high as with diesel to achieve satisfactory performance. This opens for a larger range of possibilities when designing injection systems. In the period from 2004 to 2009 the DME engine was perfected for use in the car DTU...

  15. Nanostructured energetic composites: synthesis, ignition/combustion modeling, and applications.

    Science.gov (United States)

    Zhou, Xiang; Torabi, Mohsen; Lu, Jian; Shen, Ruiqi; Zhang, Kaili

    2014-03-12

    Nanotechnology has stimulated revolutionary advances in many scientific and industrial fields, particularly in energetic materials. Powder mixing is the simplest and most traditional method to prepare nanoenergetic composites, and preliminary findings have shown that these composites perform more effectively than their micro- or macro-sized counterparts in terms of energy release, ignition, and combustion. Powder mixing technology represents only the minimum capability of nanotechnology to boost the development of energetic material research, and it has intrinsic limitations, namely, random distribution of fuel and oxidizer particles, inevitable fuel pre-oxidation, and non-intimate contact between reactants. As an alternative, nanostructured energetic composites can be prepared through a delicately designed process. These composites outperform powder-mixed nanocomposites in numerous ways; therefore, we comprehensively discuss the preparation strategies adopted for nanostructured energetic composites and the research achievements thus far in this review. The latest ignition and reaction models are briefly introduced. Finally, the broad promising applications of nanostructured energetic composites are highlighted.

  16. Controlled Emissivity Coatings to Delay Ignition of Polyethylene.

    Science.gov (United States)

    Sonnier, Rodolphe; Ferry, Laurent; Gallard, Benjamin; Boudenne, Abderrahim; Lavaud, François

    2015-10-12

    Semi-opaque to opaque films containing small amounts of various aluminium particles to decrease emissivity were easily prepared and coated onto low-density polyethylene (LDPE) sheets. The thermal-radiative properties (reflectivity, transmissivity and absorptivity) of the films were measured and related to the aluminum particles' content, size and nature. Time-to-ignition of samples was assessed using a cone calorimeter at different heat flux values (35, 50 and 75 kW/m²). The coatings allowed significant ignition delay and, in some cases, changed the material behaviour from thermally thin to thick behaviour. These effects are related both to their emissivity and transmissivity. A lower emissivity, which decreases during the degradation, and a lower transmissivity are the key points to ensure an optimal reaction-to-fire.

  17. Controlled Emissivity Coatings to Delay Ignition of Polyethylene

    Directory of Open Access Journals (Sweden)

    Rodolphe Sonnier

    2015-10-01

    Full Text Available Semi-opaque to opaque films containing small amounts of various aluminium particles to decrease emissivity were easily prepared and coated onto low-density polyethylene (LDPE sheets. The thermal-radiative properties (reflectivity, transmissivity and absorptivity of the films were measured and related to the aluminum particles’ content, size and nature. Time-to-ignition of samples was assessed using a cone calorimeter at different heat flux values (35, 50 and 75 kW/m2. The coatings allowed significant ignition delay and, in some cases, changed the material behaviour from thermally thin to thick behaviour. These effects are related both to their emissivity and transmissivity. A lower emissivity, which decreases during the degradation, and a lower transmissivity are the key points to ensure an optimal reaction-to-fire.

  18. Development of Beryllium-Copper Alloy Ignition Capsules

    Science.gov (United States)

    Cooley, Jason; Alexander, David; Thoma, Daniel; Field, Robert; Day, Robert; Cameron, Bernard; Nobile, Arthur; Rivera, Gerald; Kelly, Ann; Papin, Pallas; Schulze, Roland; Dauelsberg, Lawrence; Alexander, Neil; Galix, Remy

    2004-11-01

    Cu-doped Be capsules are being developed for ignition on the National Ignition Facility (NIF). Our fabrication approach is based on bonding of cylindrical parts containing precision machined hemispherical cavities, followed by machining an external spherical contour to produce a spherical shell. While we have demonstrated this approach, there are several key issues that need to be resolved before a shell meeting NIF specifications can be produced. These issues are synthesis of high purity small grain size Be0.9at%Cu alloy, formation of a strong hemishell bond that will allow the capsule to contain its 400 atm fill gas at room temperature, precision machining and polishing of the capsule to meet stringent specifications for surface finish and spherical quality, and filling with DT. In this paper we report on the progress that has been made in resolving these key issues.

  19. Status of the National Ignition Facility and Campaign, and Controls and Information Systems on the Path to Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Lagin, L.; Azevedo, S.; Bettenhausen, R.; Beeler, R.; Belk, L.; Bowers, G.; Brunton, G.; Carey, R.; Casey, A.; Christensen, M.; Demaret, R.; Edwards, O.; Estes, C.; Fisher, J.; Foxworthy, C.; Frazier, T.; Kegelmeyer, L.; Krammen, J.; Ludwigsen, A.; Mathisen, D.; Marshall, C.; Shelton, R.; Stout, E.; Townsend, S.; Van Arsdall, P.; Wilson, E. [Lawrence Livermore National Laboratory, Livermore (United States)

    2009-07-01

    Full text of the publication follows: The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-Mega-joule, 500-Terawatt, ultraviolet laser system together with a 10- meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 1000 front-end processors, embedded controllers and supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves inter-operation between different languages and target architectures. A shot automation framework has been used to orchestrate and automate over a thousand system shots performed at the NIF using the ICCS. An experimental database and automated shot analysis infrastructure has also been developed and is being used for conducting experiments. In March 2009, the NIF project was completed by successfully demonstrating its formal completion of performance and operational design criteria. At present, all 192 beams have been commissioned to target chamber center. During the past year, the control system was expanded to include automation of target area systems including final optics, target positioners and diagnostics, in preparation for project completion. A detailed set of experiments have begun and are being performed as part of a National

  20. The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability

    Energy Technology Data Exchange (ETDEWEB)

    Keating, Edward [General Motors LLC, Pontiac, MI (United States); Gough, Charles [General Motors LLC, Pontiac, MI (United States)

    2015-07-07

    This report summarizes activities conducted in support of the project “The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability” under COOPERATIVE AGREEMENT NUMBER DE-EE0005654, as outlined in the STATEMENT OF PROJECT OBJECTIVES (SOPO) dated May 2012.