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Sample records for laser induced nuclear

  1. Laser induced nuclear reactions

    International Nuclear Information System (INIS)

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

    1998-01-01

    Dramatic improvements in laser technology since 1984 have revolutionised high power laser technology. Application of chirped-pulse amplification techniques has resulted in laser intensities in excess of 10 19 W/cm 2 . In the mid to late eighties, C. K. Rhodes and K. Boyer discussed the possibility of shining laser light of this intensity onto solid surfaces and to cause nuclear transitions. In particular, irradiation of a uranium target could induce electro- and photofission in the focal region of the laser. In this paper it is shown that μCi of 62 Cu can be generated via the (γ,n) reaction by a laser with an intensity of about 10 19 Wcm -2

  2. Laser-induced nuclear physics and applications

    International Nuclear Information System (INIS)

    Ledingham, K.W.D.; Singhal, R.P.; McKenna, P.; Spencer, I.

    2002-01-01

    With a 1 ps pulse laser at 1 μm wavelength, He gas is ionised at about 3.10 14 W.cm -2 . As the intensity increases, the inert gases become multiple ionised and between 10 18 and 10 19 W.cm -2 photon induced nuclear reactions are energetically possible. Close to 10 21 W.cm -2 pion production can take place. At the very high intensities of 10 28 W.cm -2 , it can be shown that electron-positron pairs can be created from the vacuum. The authors review the applications of high intensity focused laser beams in particle acceleration, laser-induced fission and laser production of protons and neutrons. Exciting new phenomena are expected at intensities higher than 10 22 W.cm -2 , -) the oscillating electric field can affect directly the protons in exactly the same way as the electrons in the plasma, -) fusion reactions by direct laser acceleration of ions. (A.C.)

  3. Laser-induced nuclear fusion

    International Nuclear Information System (INIS)

    Jablon, Claude

    1977-01-01

    Research programs on laser-induced thermonuclear fusion in the United States, in Europe and in USSR are reviewed. The principle of the fusion reactions induced is explained, together with the theoretical effects of the following phenomena: power and type of laser beams, shape and size of the solid target, shock waves, and laser-hydrodynamics coupling problems [fr

  4. Laser induced nuclear orientation: intersection of laser and nuclear spectroscopy

    International Nuclear Information System (INIS)

    Burns, M.; Pappas, P.; Field, M.S.

    1978-01-01

    The application of lasers to the study of hyperfine structure is reviewed with emphasis placed on the ability of the laser beam to align the nuclei in a sample. This aligning effect is especially useful if the nuclei are unstable as then the angular distribution of the subsequent nuclear radiation may be effected and information will by given about the nuclear parameters. (B.R.H.)

  5. Laser-induced nuclear orientation and gamma anisotropy in sodium

    International Nuclear Information System (INIS)

    Pappas, P.G.

    1980-12-01

    The use of laser optical pumping to induce nuclear orientation in several isotopes and one isomer of atomic sodium vapor is described. Essentially complete nuclear polarization, P > 90%, has been achieved in stable 23 Na when pumping with modest laser intensities (I approx. = 10 mW/cm 2 ). The volume of the sample cell was approximately 10 cc, and was filled with a sodium density of about 10'' atoms/cc. Complete coverage of the Doppler distribution was accomplished with the use of trace amounts (less than or equal to 1 torr) of argon buffer gas to induce velocity changing collisions. A theoretical model which accurately predicts the amount of polarization is developed. The orientation of nuclei which are unstable to gamma decay can manifest itself in anisotropic gamma ray emission. This anisotropy can be used to measure isotope and isomer shifts, from which nuclear properties can be derived. Gamma anisotropy was observed in two systems, 22 Na and /sup 24m/Na. From the observed anisotropy in /sup 24m/Na, a negative sign for the g factor is determined. Values are derived for the magnetic moment, μ = 2.56 +- 0.64 nm, and the isomer shift, deltaν/sub 24m/ = 288 +- 191 MHz (D1 line). A model is described which relates various laser and fubber gas parameters to the observed gamma anisotropy lineshape. This model facilitates the extraction of physical parameters from knowledge of the laser frequency at which the anisotropy is a maximum

  6. Laser induced breakdown spectroscopy for applications in nuclear industry

    International Nuclear Information System (INIS)

    Suri, B.M.

    2010-01-01

    There are several analytical techniques employing laser spectroscopy - each with its own distinctive potential. Laser Induced Breakdown Spectroscopy (LIBS) is one such technique which is attractive in view of its relative compactness and simplicity (in configuration), remote and online analysis (with no sample handling requirement) and high spatial resolution allowing compositional map or homogeneity analysis. In this technique, a high power pulsed (mostly nanosecond) laser is employed to irradiate the sample causing spark emission, characteristics of the sample composition, which is collected using suitable optics and analysed spectroscopically. Remote and online capability is derived from long distance delivery of laser beams and collection of emitted light by fibres or conventional optics. Since laser can be focused sharply on the target, it can facilitate compositional mapping. Beam Technology Development Group at BARC had initiated work on LIBS of nuclear materials several years ago. Recently the challenge of online monitoring of radioactive waste vitrification plant in a hot cell has been taken up. The theoretical and experimental work done by the group related to instrument development, plasma characterization, quantitative compositional analysis of ternary alloys and uranium vitrified glass samples (comprising more than dozen elements) are described. The future plans for setting up online glass homogeneity monitoring facility are also described. This should fulfill an important demand for optimization of vitrification process. Various other demands of nuclear industry are also reviewed

  7. Laser induced nuclear orientation effects

    International Nuclear Information System (INIS)

    Burns, M.; Pappas, P.; Feld, M.S.; Murnick, D.E.

    1977-01-01

    Resonant laser radiation can orient metastable nuclei, resulting in spatially anisotropic emission of β or γ radiation. This technique can be used to obtain isomer shifts and nuclear moments and can lead to isomer separation. (Auth.)

  8. Time-resolved laser-induced fluorescence in the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Moulin, C.; Decambox, P.; Mauchien, P.; Petit, A.

    1995-01-01

    Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented. (author)

  9. Nuclear Fusion Effects Induced in Intense Laser-Generated Plasmas

    Directory of Open Access Journals (Sweden)

    Lorenzo Torrisi

    2013-01-01

    Full Text Available Deutered polyethylene (CD2n thin and thick targets were irradiated in high vacuum by infrared laser pulses at 1015W/cm2 intensity. The high laser energy transferred to the polymer generates plasma, expanding in vacuum at supersonic velocity, accelerating hydrogen and carbon ions. Deuterium ions at kinetic energies above 4 MeV have been measured by using ion collectors and SiC detectors in time-of-flight configuration. At these energies the deuterium–deuterium collisions may induce over threshold fusion effects, in agreement with the high D-D cross-section valuesaround 3 MeV energy. At the first instants of the plasma generation, during which high temperature, density and ionacceleration occur, the D-D fusions occur as confirmed by the detection of mono-energetic protonsand neutrons with a kinetic energy of 3.0 MeV and 2.5 MeV, respectively, produced by the nuclear reaction. The number of fusion events depends strongly on the experimental set-up, i.e. on the laser parameters (intensity, wavelength, focal spot dimension, target conditions (thickness, chemical composition, absorption coefficient, presence of secondary targets and used geometry (incidence angle, laser spot, secondary target positions.A number of D-D fusion events of the order of 106÷7 per laser shot has been measured.

  10. On the use of time resolved laser-induced spectrofluorometry in the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Moulin, C.; Decambox, P.; Mauchien, P.; Davin, T.; Pradel, B.

    1991-01-01

    Time Resolved Laser-Induced Spectrofluorometry (TRLIS) has been used for actinides trace analysis and complexation analysis in the nuclear fuel cycle. Results obtained in the different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment are presented. 4 figs., 6 refs

  11. Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator

    Science.gov (United States)

    Wang, X. L.; Xu, Z. Y.; Luo, W.; Lu, H. Y.; Zhu, Z. C.; Yan, X. Q.

    2017-09-01

    Photo-transmutation of long-lived nuclear waste induced by a high-charge relativistic electron beam (e-beam) from a laser plasma accelerator is demonstrated. A collimated relativistic e-beam with a high charge of approximately 100 nC is produced from high-intensity laser interaction with near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor and then radiates energetic bremsstrahlung photons with flux approaching 1011 per laser shot. Taking a long-lived radionuclide 126Sn as an example, the resulting transmutation reaction yield is the order of 109 per laser shot, which is two orders of magnitude higher than obtained from previous studies. It is found that at lower densities, a tightly focused laser irradiating relatively longer NCD plasmas can effectively enhance the transmutation efficiency. Furthermore, the photo-transmutation is generalized by considering mixed-nuclide waste samples, which suggests that the laser-accelerated high-charge e-beam could be an efficient tool to transmute long-lived nuclear waste.

  12. Nuclear-driven flashlamp pumping of the atomic iodine laser

    International Nuclear Information System (INIS)

    Miley, G.H.

    1992-03-01

    This report is a study of the atomic iodine laser pumped with nuclear- excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor investigated the fluorescence of the excimer XeBr under nuclear pumping with 10 B and 3 He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C 3 F 7 I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation

  13. Nuclear-pumped lasers

    CERN Document Server

    Prelas, Mark

    2016-01-01

    This book focuses on Nuclear-Pumped Laser (NPL) technology and provides the reader with a fundamental understanding of NPLs, a review of research in the field, and exploration of large scale NPL system design and applications. Early chapters look at the fundamental properties of lasers, nuclear-pumping and nuclear reactions that may be used as drivers for nuclear-pumped lasers. The book goes on to explore the efficient transport of energy from the ionizing radiation to the laser medium and then the operational characteristics of existing nuclear-pumped lasers. Models based on Mathematica, explanations and a tutorial all assist the reader’s understanding of this technology. Later chapters consider the integration of the various systems involved in NPLs and the ways in which they can be used, including beyond the military agenda. As readers will discover, there are significant humanitarian applications for high energy/power lasers, such as deflecting asteroids, space propulsion, power transmission and mining....

  14. Development of Laser-Induced Breakdown Spectroscopy Technologies for Nuclear Safeguards and Forensic Applications

    International Nuclear Information System (INIS)

    Chen, S.; El-Jaby, A.; Doucet, F.; Bouchard, P.; Sabsabi, M.

    2015-01-01

    Under the IAEA Task A1855, the Canadian Safeguards Support Program (CSSP) undertook the development of laser-induced breakdown spectroscopy (LIBS) technologies for safeguards applications. Collaboration between the Canadian Nuclear Safety Commission (CNSC), the National Research Council Canada, and the IAEA has demonstrated that the LIBS technique combined with chemometrics can determine the origins of yellowcake, identify maraging steels, aluminium alloys, and magnesium alloys, among other materials involved in the nuclear industry; and determine heavy water content as well as the isotope ratios of other actinides. As part of the task, the CSSP has developed a portable LIBS system to enable inspectors to characterize specific nuclear and non-nuclear material during complementary access and inspections. This device was recently tested by the IAEA in both Vienna and Siebersdorf for various metals and uranium bearing materials. The laser source proved to be stable and the chemometrics software was able to identify various materials. The device is ready for further in-depth testing. The chemometrics algorithm that has been developed for LIBS can also be adapted to nuclear forensics for the querying database. Multi-stage pattern recognition algorithms can reliably identify unknown materials among database populations (e.g., identify origins of yellowcake). Further work in this field is being undertaken as part of the CNSC's National Nuclear Forensics Library (NNFL) development activities for the Canadian National Nuclear Forensics Capability Project (CNNFCP). The paper will provide an overview of the LIBS techniques being developed for safeguards and forensic applications, and of progress in integrating all components into a compact unit. (author)

  15. Temporal follow-up of plasma parameter in an nuclear grade aluminum laser induced plasma at different laser energies by laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Karki, Vijay; Singh, Manjeet; Sarkar, Arnab

    2015-07-01

    We report spectroscopic studies of laser induced plasma (LIP) produced by ns – 532 nm - Nd:YAG laser light pulses for different laser energies (35, 45 and 60 mJ) on an nuclear grade aluminum sample in air at atmospheric pressure. The temporal history of the plasma is obtained by recording the emission features at predetermined delays and at a fixed gate width (2.5 ì s). The temporal profiles of excitation temperature (T e ), ionization temperature (T ion ) and electron number density (N e ) were determined from Boltzmann plot, Saha-Boltzmann equation and Stark broadening method, respectively. T e , T ion and N e , shows a power law decay pattern with increasing acquisition time delay. T e has a positive correlation with laser energy, but the T ion and N e differ negligibly from one laser energy to another. Again the rate of decay of T e increases with increasing laser energy but that of T ion is much slower and independent of laser energy. The follow up of the local thermodynamic equilibrium (LTE) conditions were evaluated using both McWhirter criterion and T e /T ion ratio for different delays and different energies to determine the temporal range in which LTE is satisfied. Both the methods concluded very similar results except for very high energy and small delay conditions, where T e /T ion ratio deviates from unity indicating non-LTE condition. The relative transition probabilities of Al transition (3sp4s: 4 P 2/5 →3sp 2 : 4P 3/2,5/2 ) and (4s: 2 S 1/2 → 3p: 2 P 1/2,3/2 ) were estimated and are in excellent agreement with the Kurucz database. These investigations provide an insight to optimize various parameters during LIBS analysis of aluminum based matrices. (author)

  16. Determination of nuclear spins of short-lived isotopes by laser induced fluorescence

    International Nuclear Information System (INIS)

    Buchinger, F.; Dabkiewicz, P.; Kremmling, H.; Kuehl, T.; Mueller, A.C.; Schuessler, H.A.

    1980-01-01

    The spins of several nuclear ground and isomeric states have been measured for a number of mercury isotopes. The fluorescent light from the 6s6p 3 P 1 state is observed at 2537 Angstroem after excitation with the frequency doubled output of a pulsed dye laser. Four different laser induced fluorescence techniques were tested for their applicability: double resonance, Hanle effect, time delayed integral Hanle beats, and time resolved quantum beats. The sensitivity and selectivity of these models are compared with emphasis on the determination of spins of nuclei far from beta-stability, where short half lives and low production yields restrict the number of available atoms. The experiments were carried out on-line with the ISOLDE isotope separator at CERN at densities as low as 10 6 atoms/cm 3 . Results for the very neutron deficient high spin mercury isomers with half lives of several seconds, but also for the ground states of the abundant low spin stable mercury isotopes, are given as examples. The test measurements determined the nuclear spins of the odd sup(185m-191m)Hg isomers to be I = 13/2. (orig.)

  17. Measurement of changes in nuclear charge radii of 2r by laser-induced resonance fluorescence

    International Nuclear Information System (INIS)

    Gangrskij, Yu.P.; Zemlyanoj, S.G.; Marinova, K.P.; Markov, B.N.; Khoang Tkhi Kim Khueh; Chan Kong Tam; Kul'dzhanov, B.K.

    1987-01-01

    The optical isotopic shifts of Zr stable isotopes have been measured in three atomic transitions of type 4d 2 5s 2 → 4d 2 5s5p using the technique of laser-induced resonance fluorescence. The changes of nuclear mean-square charge radius Δ 2 > have been determined. The extracted values of Δ 2 > are compared to predictions of the droplet model. It is shown that the droplet model calculations can be made to agree with the experimental results, if changes of nuclear dynamical octupole deformation and of surface diffuseness parameter are taken into account

  18. Exploring laser-induced breakdown spectroscopy for nuclear materials analysis and in-situ applications

    Science.gov (United States)

    Martin, Madhavi Z.; Allman, Steve; Brice, Deanne J.; Martin, Rodger C.; Andre, Nicolas O.

    2012-08-01

    Laser-induced breakdown spectroscopy (LIBS) has been used to determine the limits of detection of strontium (Sr) and cesium (Cs), common nuclear fission products. Additionally, detection limits were determined for cerium (Ce), often used as a surrogate for radioactive plutonium in laboratory studies. Results were obtained using a laboratory instrument with a Nd:YAG laser at fundamental wavelength of 1064 nm, frequency doubled to 532 nm with energy of 50 mJ/pulse. The data was compared for different concentrations of Sr and Ce dispersed in a CaCO3 (white) and carbon (black) matrix. We have addressed the sampling errors, limits of detection, reproducibility, and accuracy of measurements as they relate to multivariate analysis in pellets that were doped with the different elements at various concentrations. These results demonstrate that LIBS technique is inherently well suited for in situ analysis of nuclear materials in hot cells. Three key advantages are evident: (1) small samples (mg) can be evaluated; (2) nuclear materials can be analyzed with minimal sample preparation; and (3) samples can be remotely analyzed very rapidly (ms-seconds). Our studies also show that the methods can be made quantitative. Very robust multivariate models have been used to provide quantitative measurement and statistical evaluation of complex materials derived from our previous research on wood and soil samples.

  19. Nuclear based diagnostics in high-power laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Marc; Sonnabend, Kerstin; Harres, Knut; Otten, Anke; Roth, Markus [TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Vogt, Karsten; Bagnoud, Vincent [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)

    2010-07-01

    High-power lasers allow focused intensities of >10{sup 18} W/cm{sup 2}. During the laser-solid interaction, an intense relativistic electron current is injected from the plasma into the target. One challenge is to characterize the electron dynamic close to the interaction region. Moreover, next generation high-power laser proton acceleration leads to high proton fluxes, which require novel, nuclear diagnostic techniques. We present an activation-based nuclear pyrometry for the investigation of electrons generated in relativistic laser-solid interactions. We use novel activation targets consisting of several isotopes with different photo-neutron disintegration thresholds. The electrons are decelerated inside the target via bremsstrahlung processes. The high-energy bremsstrahlung induces photo-nuclear reactions. In this energy range no disturbing low energy effects are important. Via the pyrometry the Reconstruction of the absolute yield, spectral and spatial distribution of the electrons is possible. For the characterization of proton beams we present a nuclear activation imaging spectroscopy (NAIS). The diagnostic is based on proton-neutron disintegration reactions of copper stacked in consecutive layers. An autoradiography of copper layers leads to spectrally and spatially reconstruction of the beam profile.

  20. Status of Nuclear-Pumped Laser research

    International Nuclear Information System (INIS)

    Prelas, M.A.

    1984-01-01

    The field of Nuclear-Pumped lasers (NPLs) has progressed in many directions since the discovery of the first NPL in 1974. This paper discusses developments in the area of coupling nuclear energy to a laser media, kinetics, and the integration of nuclear reactors to a laser (or other types of energy conversion medium). Many questions about the process of nuclear-pumping have been examined since the discovery of the first NPL in 1974. During a period of time between 1974 and 1981, several types of lasers have been driven by nuclear reactions (ie rare gas lasers, impurity type lasers, molecular lasers, and an ion laser). Three of the lasers discovered, had demonstrated efficiencies of >1%. In addition, volume scaling of NPLs was demonstrated

  1. Lasers in nuclear physics

    International Nuclear Information System (INIS)

    Inamura, T.T.

    1988-01-01

    The hyperfine interaction has been reviewed from a point of view of nuclear physics. Recent progress of nuclear spectroscopy with lasers is presented as one of laser studies of fundamental physics currently pursued in Japan. Especially, the hyperfine anomaly is discussed in connection with the origin of nuclear magnetism. (author)

  2. Boron-Proton Nuclear-Fusion Enhancement Induced in Boron-Doped Silicon Targets by Low-Contrast Pulsed Laser

    Directory of Open Access Journals (Sweden)

    A. Picciotto

    2014-08-01

    Full Text Available We show that a spatially well-defined layer of boron dopants in a hydrogen-enriched silicon target allows the production of a high yield of alpha particles of around 10^{9} per steradian using a nanosecond, low-contrast laser pulse with a nominal intensity of approximately 3×10^{16}  W cm^{−2}. This result can be ascribed to the nature of the long laser-pulse interaction with the target and with the expanding plasma, as well as to the optimal target geometry and composition. The possibility of an impact on future applications such as nuclear fusion without production of neutron-induced radioactivity and compact ion accelerators is anticipated.

  3. Laser-induced interactions

    International Nuclear Information System (INIS)

    Green, W.R.

    1979-01-01

    This dissertation discusses some of the new ways that lasers can be used to control the energy flow in a medium. Experimental and theoretical considerations of the laser-induced collision are discussed. The laser-induced collision is a process in which a laser is used to selectively transfer energy from a state in one atomic or molecular species to another state in a different species. The first experimental demonstration of this process is described, along with later experiments in which lasers were used to create collisional cross sections as large as 10 - 13 cm 2 . Laser-induced collisions utilizing both a dipole-dipole interaction and dipole-quadrupole interaction have been experimentally demonstrated. The theoretical aspects of other related processes such as laser-induced spin-exchange, collision induced Raman emission, and laser-induced charge transfer are discussed. Experimental systems that could be used to demonstrate these various processes are presented. An experiment which produced an inversion of the resonance line of an ion by optical pumping of the neutral atom is described. This type of scheme has been proposed as a possible method for constructing VUV and x-ray lasers

  4. Nuclear-pumped lasers for large-scale applications

    International Nuclear Information System (INIS)

    Anderson, R.E.; Leonard, E.M.; Shea, R.F.; Berggren, R.R.

    1989-05-01

    Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficiently short initiation pulse may be possible. Proof-of-principle experiments are planned to demonstrate lasing in a direct nuclear-pumped large-volume system; to study the effects of various neutron absorbing materials on laser performance; to study the effects of long initiation pulse lengths; to demonstrate the performance of large-scale optics and the beam quality that may be obtained; and to assess the performance of alternative designs of burst systems that increase the neutron output and burst repetition rate. 21 refs., 8 figs., 5 tabs

  5. Laser induced photochemical and photophysical processes in fuel reprocessing: present scenario and future prospects

    International Nuclear Information System (INIS)

    Bhowmick, G.K.; Sarkar, S.K.; Ramanujam, A.

    2001-01-01

    State-of-art lasers can meet the very stringent requirements of nuclear technology and hence find application in varied areas of nuclear fuel cycle. Here, we discuss two specific applications in nuclear fuel reprocessing namely (a) add-on photochemical modifications of PUREX process where photochemical reactors replace the chemical reactors, and (b) fast, matrix independent sensitive laser analytical techniques. The photochemical modifications based on laser induced valency adjustment offers efficient separation, easy maintenance and over all reduction in the volume of radioactive waste. The analytical technique of time resolved laser induced fluorescence (TRLIF) has several attractive features like excellent sensitivity, element selective, and capability of on line remote process monitoring. For optically opaque solutions, optical excitation is detected by its conversion into thermal energy by non-radiative relaxation processes using the photo-thermal spectroscopic techniques. (author)

  6. Laser applications in nuclear power plants

    Indian Academy of Sciences (India)

    2014-01-09

    Jan 9, 2014 ... Keywords. Nd:YAG laser; fibre-optic beam delivery; laser cutting; laser welding; nuclear reactor. ... Author Affiliations. D N Sanyal1. Remote Tooling Section, Technology Development Group, Nuclear Power Corporation of India Ltd., Mumbai 400 094, India ...

  7. Laser robot in the nuclear industry

    International Nuclear Information System (INIS)

    Contre, M.

    1987-05-01

    Possibilities of power lasers for welding, cutting, drilling, plugging surface treatment and hard-facing are reviewed. CO 2 and Nd:YAG lasers only have adequate power for nuclear applications. Radiation effects on lasers and contamination problems are examined. Then examples of applications to nuclear industry are given: PWR fuel fabrication, oxide thickness measurement in Magnox reactors, laser cutting of a cylindrical piece of steel on the bottom of a fuel channel in a gas graphite reactor, nuclear plant dismantling and fuel reprocessing. 51 refs [fr

  8. Laser-induced time-resolved spectrofluorometry and thermal lensing: applications in the nuclear industry

    International Nuclear Information System (INIS)

    Decambox, P.; Delorme, N.; Mauchien, P.; Moulin, C.

    1989-01-01

    Sensitive spectroscopic methods for the determination of actinides and lanthanides in various media are required in the nuclear industry. Laser-Induced Time-Resolved Spectrofluorometry (LITRS) for several actinides and lanthanides at very low levels and thermal lensing (TL) for oxidation state characterization allow these determinations. The set-up of LITRS is presented. Spectra, limit of detections and lifetimes obtained for U, Cm, Am, Eu, Gd, Tb, Dy, Ce, Sm, Tm are shown. Detection limit as low as 5.10 -12 M can be achieved. Examples of matrices encountered for the determination of uranium are given as well as comparison with mass spectrometry and alpha counting. The set-up of TL and performances obtained on plutonium as well as future developments are presented

  9. Exploring laser-induced breakdown spectroscopy for nuclear materials analysis and in-situ applications

    International Nuclear Information System (INIS)

    Martin, Madhavi Z.; Allman, Steve; Brice, Deanne J.; Martin, Rodger C.; Andre, Nicolas O.

    2012-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been used to determine the limits of detection of strontium (Sr) and cesium (Cs), common nuclear fission products. Additionally, detection limits were determined for cerium (Ce), often used as a surrogate for radioactive plutonium in laboratory studies. Results were obtained using a laboratory instrument with a Nd:YAG laser at fundamental wavelength of 1064 nm, frequency doubled to 532 nm with energy of 50 mJ/pulse. The data was compared for different concentrations of Sr and Ce dispersed in a CaCO 3 (white) and carbon (black) matrix. We have addressed the sampling errors, limits of detection, reproducibility, and accuracy of measurements as they relate to multivariate analysis in pellets that were doped with the different elements at various concentrations. These results demonstrate that LIBS technique is inherently well suited for in situ analysis of nuclear materials in hot cells. Three key advantages are evident: (1) small samples (mg) can be evaluated; (2) nuclear materials can be analyzed with minimal sample preparation; and (3) samples can be remotely analyzed very rapidly (ms-seconds). Our studies also show that the methods can be made quantitative. Very robust multivariate models have been used to provide quantitative measurement and statistical evaluation of complex materials derived from our previous research on wood and soil samples. - Highlights: ► Did the detection of strontium, cerium, and cesium in CaCO 3 and graphite matrices. ► The detection of these elements was performed in a systematic manner. ► Univariate calibration curves were used to determine strontium detection. ► Univariate and multivariate statistical analysis built improved statistical models. ► Limits of detection are comparable or better in case of cerium and cesium.

  10. Study on two-color planar laser induced fluorescence thermometry

    International Nuclear Information System (INIS)

    Li Shaodan; Tan Sichao; Gao Puzhen; Lin Yuansheng

    2014-01-01

    Many of the convection heat transfer process are involved in the research of nuclear reactor thermal hydraulics. To experimentally determine the variation of the temperature field in those processes is important for the design and safety operation of the nuclear reactor. The application of the two-color planar laser induced fluorescence (PLIF) in the measurements of fluid temperature distribution is discussed in the paper. The laser dyes used here is rhodamine B (RhB) with negative temperature coefficient and fluorescein 27 (F127) with positive temperature coefficient. The beam of the laser light is adjusted to laser sheet by using the lens group. The fluid with dyes is excited by this laser sheet in a specific plane and temperature dependent fluorescence is released. The temperature field of the plane can be determined through the intensity information. Some technical aspects encountered in the application of the two-laser PLIF are discussed in the paper, such as the spectra characteristic of the dyes and the separation of the spectra. The calibration temperature is higher than the water saturation temperature (at atmosphere pressure). (authors)

  11. Role of aromatic amino acids in carbohydrate binding of plant lectins : Laser photo chemically induced dynamic nuclear polarization study of hevein domain-containing lectins

    NARCIS (Netherlands)

    Siebert, HC; vonderLieth, CW; Kaptein, R; Beintema, JJ; Dijkstra, K; vanNuland, N; Soedjanaatmadja, UMS; Rice, A; Vliegenthart, JFG; Wright, CS; Gabius, HJ

    Carbohydrate recognition by lectins often involves the side chains of tyrosine, tryptophan, and histidine residues. These moieties are able to produce chemically induced dynamic nuclear polarization (CIDNP) signals after laser irradiation in the presence of a suitable radical pair-generating dye.

  12. DNA fragmentation and nuclear phenotype in tendons exposed to low-intensity infrared laser

    Science.gov (United States)

    de Paoli, Flavia; Ramos Cerqueira, Larissa; Martins Ramos, Mayara; Campos, Vera M.; Ferreira-Machado, Samara C.; Geller, Mauro; de Souza da Fonseca, Adenilson

    2015-03-01

    Clinical protocols are recommended in device guidelines outlined for treating many diseases on empirical basis. However, effects of low-intensity infrared lasers at fluences used in clinical protocols on DNA are controversial. Excitation of endogenous chromophores in tissues and free radicals generation could be described as a consequence of laser used. DNA lesions induced by free radicals cause changes in DNA structure, chromatin organization, ploidy degrees and cell death. In this work, we investigated whether low-intensity infrared laser therapy could alter the fibroblasts nuclei characteristics and induce DNA fragmentation. Tendons of Wistar rats were exposed to low-intensity infrared laser (830 nm), at different fluences (1, 5 and 10 J/cm2), in continuous wave (power output of 10mW, power density of 79.6 mW/cm2). Different frequencies were analyzed for the higher fluence (10 J/cm2), at pulsed emission mode (2.5, 250 and 2500 Hz), with the laser source at surface of skin. Geometric, densitometric and textural parameters obtained for Feulgen-stained nuclei by image analysis were used to define nuclear phenotypes. Significant differences were observed on the nuclear phenotype of tendons after exposure to laser, as well as, high cell death percentages was observed for all fluences and frequencies analyzed here, exception 1 J/cm2 fluence. Our results indicate that low-intensity infrared laser can alter geometric, densitometric and textural parameters in tendon fibroblasts nuclei. Laser can also induce DNA fragmentation, chromatin lost and consequently cell death, using fluences, frequencies and emission modes took out from clinical protocols.

  13. Measurement of fuel corrosion products using planar laser-induced fluorescence

    International Nuclear Information System (INIS)

    Wantuck, P.J.; Sappey, A.D.; Butt, D.P.

    1993-01-01

    Characterizing the corrosion behavior of nuclear fuel material in a high-temperature hydrogen environment is critical for ascertaining the operational performance of proposed nuclear thermal propulsion (NTP) concepts. In this paper, we describe an experimental study undertaken to develop and test non-intrusive, laser-based diagnostics for ultimately measuring the distribution of key gas-phase corrosion products expected to evolve during the exposure of NTP fuel to hydrogen. A laser ablation technique is used to produce high temperature, vapor plumes from uranium-free zirconium carbide (ZrC) and niobium carbide (NbC) forms for probing by various optical diagnostics including planar laser-induced fluorescence (PLIF). We discuss the laser ablation technique, results of plume emission measurements, and we describe both the actual and proposed planar LIF schemes for imaging constituents of the ablated ZrC and NbC plumes. Envisioned testing of the laser technique in rf-heated, high temperature gas streams is also discussed

  14. Applications of laser produced ion beams to nuclear analysis of materials

    International Nuclear Information System (INIS)

    Mima, K.; Azuma, H.; Fujita, K.; Yamazaki, A.; Okuda, C.; Ukyo, Y.; Kato, Y.; Arrabal, R. Gonzalez; Soldo, F.; Perlado, J. M.; Nishimura, H.; Nakai, S.

    2012-01-01

    Laser produced ion beams have unique characteristics which are ultra-short pulse, very low emittance, and variety of nuclear species. These characteristics could be used for analyzing various materials like low Z ion doped heavy metals or ceramics. Energies of laser produced ion beam extend from 0.1MeV to 100MeV. Therefore, various nuclear processes can be induced in the interactions of ion beams with samples. The ion beam driven nuclear analysis has been developed for many years by using various electrostatic accelerators. To explore the applicability of laser ion beam to the analysis of the Li ion battery, a proton beam with the diameter of ∼ 1.0 μm at Takasaki Ion Acceleration for Advanced Radiation Application (TIARA), JAEA was used. For the analysis, the PIGE (Particle-Induced Gamma Ray Emission) is used. The proton beam scans over Li battery electrode samples to diagnose Li density in the LiNi 0.85 Co 0.15 O 2 anode. As the results, PIGE images for Li area density distributions are obtained with the spatial resolution of better than 1.5μm FWHM. By the Li PIGE images, the depth dependence of de-intercalation levels of Li in the anode is obtained. By the POP experiments at TIARA, it is clarified that laser produced ion beam is appropriate for the Li ion battery analysis. 41.85.Lc, 41.75.Jv, 42.62.cf.

  15. Fiber-optic laser-induced breakdown spectroscopy of zirconium metal in air: Special features of the plasma produced by a long-pulse laser

    Science.gov (United States)

    Matsumoto, Ayumu; Ohba, Hironori; Toshimitsu, Masaaki; Akaoka, Katsuaki; Ruas, Alexandre; Sakka, Tetsuo; Wakaida, Ikuo

    2018-04-01

    The decommissioning of the Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Plant is an essential issue in nuclear R&D. Fiber-optic laser-induced breakdown spectroscopy (Fiber-optic LIBS) could be used for in-situ elemental analysis of the inside of the damaged reactors. To improve the performances under difficult conditions, using a long-pulse laser can be an efficient alternative. In this work, the emission spectra of zirconium metal in air obtained for a normal-pulse laser (6 ns) and a long-pulse laser (100 ns) (wavelength: 1064 nm, pulse energy: 12.5 mJ, spot diameter: 0.35 mm) are compared to investigate the fundamental aspects of fiber-optic LIBS with the long-pulse laser. The spectral features are considerably different: when the long-pulse laser is used, the atomic and molecular emission is remarkably enhanced. The enhancement of the atomic emission at the near infrared (NIR) region would lead to the observation of emission lines with minimum overlapping. To understand the differences in the spectra induced respectively from the normal-pulse laser and the long-pulse laser, photodiode signals, time-resolved spectra, plasma parameters, emission from the ambient air, and emission regions are investigated, showing the particular characteristics of the plasma produced by the long-pulse laser.

  16. Induced Current Characteristics Due to Laser Induced Plasma and Its Application to Laser Processing Monitoring

    International Nuclear Information System (INIS)

    Madjid, Syahrun Nur; Idris, Nasrullah; Kurniawan, Koo Hendrik; Kagawa, Kiichiro

    2011-01-01

    In laser processing, suitable conditions for laser and gas play important role in ensuring a high quality of processing. To determine suitable conditions, we employed the electromagnetic phenomena associated with laser plasma generation. An electrode circuit was utilised to detect induced current due to the fast electrons propelled from the material during laser material processing. The characteristics of induced current were examined by changing parameters such as supplied voltage, laser pulse energy, number of laser shots, and type of ambient gas. These characteristics were compared with the optical emission characteristics. It was shown that the induced current technique proposed in this study is much more sensitive than the optical method in monitoring laser processing, that is to determine the precise focusing condition, and to accurately determine the moment of completion of laser beam penetration. In this study it was also shown that the induced current technique induced by CW CO 2 laser can be applied in industrial material processing for monitoring the penetration completion in a stainless steel plate drilling process.

  17. Laser enhanced radioactive decay and selective transmutation of nuclear waste

    International Nuclear Information System (INIS)

    Saloman, R.; Aarnio, P.; Ala-Heikkila, J.; Hakola, A.; Santala, M.

    2007-01-01

    We have investigated narrow-band coherent laser radiation - ranging from visible to X- and to gamma-ray wave length region - and their interactions both directly with photon-nuclear couplings and indirectly through the photon-electron and electron-nucleus interactions. In particular we discuss various means of selective excitation of nuclear resonance states by narrowband lasers. During the relaxation process the active nucleus may return to its initial ground-state or find another final state. In the latter case the nucleus is transmuted into a state which may have beneficial properties for instance concerning radioactivity. One ideal case would be the destruction of long-lived nuclear waste isotopes into faster decaying ones. The essential presumption is that the excitation process is selective and efficient as regards background processes due to unwanted excitation channels of the primary isotope and due to other surrounding nuclides. The paper consists of 1) a short review of generating short-wave length coherent light sources, 2) a survey of potential photon-induced nuclear states and their decay channels, and 3) a determination of the selectivity of the transmutation process

  18. Study on laser beam welding technology for nuclear power plants

    International Nuclear Information System (INIS)

    Chida, Itaru; Shiihara, Katsunori; Fukuda, Takeshi; Kono, Wataru; Obata, Minoru; Morishima, Yasuo

    2012-01-01

    Laser beam welding is one of the jointing processes by irradiating laser beam on the material surface locally and widely used at various industrial fields. Toshiba has developed various laser-based maintenance and repair technologies and already applied them to several existing nuclear power plants. Laser cladding is a technique to weld the corrosion resistant metal onto a substrate surface by feeding filler wire to improve the corrosion resistance. Temper-bead welding is the heat input process to provide the desired microstructure properties of welded low alloy steels without post weld heat treatment, by inducing proper heat cycle during laser welding. Both laser welding technologies would be performed underwater by blowing the shielding gas for creating the local dry area. In this report, some evaluation results of material characteristics by temper-bead welding to target at Reactor Coolant System nozzle of PWR are presented. (author)

  19. Lasers in atomic, molecular and nuclear physics

    International Nuclear Information System (INIS)

    Letokhov, V.S.

    1986-01-01

    This book presents papers on laser applications in atomic, molecular and nuclear physics. Specifically discussed are: laser isotope separation; laser spectroscopy of chlorophyll; laser spectroscopy of molecules and cell membranes; laser detection of atom-molecule collisions and lasers in astrophysics

  20. Laser peening applications for next generation of nuclear power facilities

    International Nuclear Information System (INIS)

    Rankin, J.; Truong, C.; Walter, M.; Chen, H.-L.; Hackel, L.

    2008-01-01

    Generation of electricity by nuclear power can assist in achieving goals of reduced greenhouse gas emissions. Increased safety and reliability are necessary attributes of any new nuclear power plants. High pressure, hot water and radiation contribute to operating environments where Stress Corrosion Cracking (SCC) and hydrogen embrittlement can lead to potential component failures. Desire for improved steam conversion efficiency pushes the fatigue stress limits of turbine blades and other rotating equipment. For nuclear reactor facilities now being designed and built and for the next generations of designs, laser peening could be incorporated to provide significant performance life to critical subsystems and components making them less susceptible to fatigue, SCC and radiation induced embrittlement. These types of components include steam turbine blades, hubs and bearings as well as reactor components including cladding material, housings, welded assemblies, fittings, pipes, flanges, vessel penetrations, nuclear waste storage canisters. Laser peening has proven to be a commercial success in aerospace applications and has recently been put into use for gas and steam turbine generators and light water reactors. An expanded role for this technology for the broader nuclear power industry would be a beneficial extension. (author)

  1. Investigation of relativistic laser-plasmas using nuclear diagnostics

    International Nuclear Information System (INIS)

    Guenther, Marc M.

    2011-01-01

    The present work explores with the development of a novel nuclear diagnostic method for the investigation of the electron dynamics in relativistic laser-plasma interactions. An additional aim of this work was the determination of the real laser peak intensity via the interaction of an intense laser short-pulse with a solid target. The nuclear diagnostics is based on a photo-neutron disintegration nuclear activation method. The main constituent of the nuclear diagnostic are novel pseudoalloic activation targets as a kind of calorimeter to measure the high-energy bremsstrahlung produced by relativistic electrons. The targets are composed of several stable isotopes with different (γ,xn)-reaction thresholds. The activated nuclides were identified via the characteristic gamma-ray decay spectrum by using high-resolution gamma spectroscopy after the laser irradiation. Via the gamma spectroscopy the (γ,xn)-reaction yields were determined. The high-energy bremsstrahlung spectrum has been deconvolved using a novel analysis method based on a modified Penfold-Leiss method. This facilitates the reconstruction of the spectrum of bremsstrahlung photons without any anticipated fit procedures. Furthermore, the characterization of the corresponding bremsstrahlung electrons in the interaction zone is accessible immediately. The consolidated findings about the properties of the relativistic electrons were used to determine the real peak intensity at the laser-plasma interaction zone. In the context of this work, experiments were performed at three different laser facilities. First Experiments were carried out at the 100 TW laser facility at Laboratoire pour l'Utilisation des Lasers Intense (LULI) in France and supplementary at the Vulcan laser facility at Rutherford Appleton Laboratory (RAL) in United Kingdom. The main part of the activation experiments were performed at the PHELIX laser facility (Petawatt High Energy Laser for heavy Ion EXperiments) at GSI-Helmholtzzentrum fuer

  2. Study of laser cladding nuclear valve parts

    International Nuclear Information System (INIS)

    Shi Shihong; Wang Xinlin; Huang Guodong

    1998-12-01

    The mechanism of laser cladding is discussed by using heat transfer model of laser cladding, heat conduction model of laser cladding and convective transfer mass model of laser melt-pool. Subsequently the laser cladding speed limit and the influence of laser cladding parameters on cladding layer structure is analyzed. A 5 kW with CO 2 transverse flow is used in the research for cladding treatment of sealing surface of stop valve parts of nuclear power stations. The laser cladding layer is found to be 3.0 mm thick. The cladding surface is smooth and has no such defects as crack, gas pore, etc. A series of comparisons with plasma spurt welding and arc bead welding has been performed. The results show that there are higher grain grade and hardness, lower dilution and better performances of resistance to abrasion, wear and of anti-erosion in the laser cladding layer. The new technology of laser cladding can obviously improve the quality of nuclear valve parts. Consequently it is possible to lengthen the service life of nuclear valve and to raise the safety and reliability of the production system

  3. Laser applications in nuclear physics

    International Nuclear Information System (INIS)

    Murnick, D.E.

    1985-01-01

    A large fraction of the International Workshop on Hyperfine Interactions was devoted to various aspects of 'laser applications in nuclear physics'. This panel discussion took place before all of the relevant formal presentations on the subject were complete. Nevertheless, there had been sufficient discussions for the significance of this emerging area of hyperfine interaction research to be made clear. An attempt was made to identify critical and controversial aspects of the subject in order to critically evaluate past successes and indicate important future directions of research. Each of the panelists made a short statement on one phase of laser-nuclear physics research, which was followed by general discussions with the other panelists and the audience. In this report, a few areas which were not covered in the formal presentations are summarized: extensions of laser spectroscopy to shorter lifetimes; extension of laser techniques to nuclei far off stability; interpretation of laser spectroscopic data; sensitivity and spectral resolution; polarized beams and targets. (Auth.)

  4. Advanced Laser-Compton Gamma-Ray Sources for Nuclear Materials Detection, Assay and Imaging

    Science.gov (United States)

    Barty, C. P. J.

    2015-10-01

    Highly-collimated, polarized, mono-energetic beams of tunable gamma-rays may be created via the optimized Compton scattering of pulsed lasers off of ultra-bright, relativistic electron beams. Above 2 MeV, the peak brilliance of such sources can exceed that of the world's largest synchrotrons by more than 15 orders of magnitude and can enable for the first time the efficient pursuit of nuclear science and applications with photon beams, i.e. Nuclear Photonics. Potential applications are numerous and include isotope-specific nuclear materials management, element-specific medical radiography and radiology, non-destructive, isotope-specific, material assay and imaging, precision spectroscopy of nuclear resonances and photon-induced fission. This review covers activities at the Lawrence Livermore National Laboratory related to the design and optimization of mono-energetic, laser-Compton gamma-ray systems and introduces isotope-specific nuclear materials detection and assay applications enabled by them.

  5. Physico-chemical studies of laser-induced plasmas for quantitative analysis of materials in nuclear systems

    International Nuclear Information System (INIS)

    Saad, Rawad

    2014-01-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a multi-elemental analysis technique very well suited for analysis in hostile environments particularly in the nuclear industry. Quantitative measurements are frequently performed on liquid or solid samples but in some cases, atypical signal behaviors were observed in the LIBS experiment. To avoid or minimize any impact on measurement accuracy, it is necessary to improve the understanding of these phenomena. In the framework of a three-year PhD thesis, the objective was to study the chemical reactions occurring within laser-generated plasma in a LIBS analysis. Experiments on a model material (pure aluminum sample) highlighted the dynamics of molecular recombination according to different ambient gas. The temporal evolution of Al I atomic emission lines and molecular bands of AlO and AlN were studied. A collisional excitation effect was identified for a peculiar electronic energy level of aluminum in the case of a nitrogen atmosphere. This effect disappeared in air. The aluminum plasma was also imaged during its expansion under the different atmospheres in order to localize the areas in which the molecular recombination process takes place. Spectacular particle projections have been highlighted. (author) [fr

  6. Generation of laser-induced fast neutron and its application

    International Nuclear Information System (INIS)

    Cha, Hyung Ki; Kwon, D. H.; Nam, S. M.

    2010-04-01

    The supply of high-efficiency neutron source is still problematic even though a fast neutron source is being accepted increasingly for industrial applications. Radioisotopes and a neutron tube are typically being used, but their neutron flux, lifetime, and price are the limiting factors for more diverse applications. As ultra high power, short pulse laser technologies have been developed, a neutron source generated via laser induced nuclear reaction comes to the fore. The laser induced neutron source has a high peak flux in comparison to the traditional neutron source and is like a point source with its diameter less than 1 mm. These properties can be utilized effectively for the analysis of pulsed fast neutron activation or the studies of a fast neutron material damage and/or recover. The purpose of R and D here is to develop a robust neutron source with a yield of 10 7 neutrons/s, and to carry out a preliminary research for application study in the next research stage

  7. Infrared laser-induced chemical reactions

    International Nuclear Information System (INIS)

    Katayama, Mikio

    1978-01-01

    The experimental means which clearly distinguishes between infrared ray-induced reactions and thermal reactions has been furnished for the first time when an intense monochromatic light source has been obtained by the development of infrared laser. Consequently, infrared laser-induced chemical reactions have started to develop as one field of chemical reaction researches. Researches of laser-induced chemical reactions have become new means for the researches of chemical reactions since they were highlighted as a new promising technique for isotope separation. Specifically, since the success has been reported in 235 U separation using laser in 1974, comparison of this method with conventional separation techniques from the economic point of view has been conducted, and it was estimated by some people that the laser isotope separation is cheaper. This report briefly describes on the excitation of oscillation and reaction rate, and introduces the chemical reactions induced by CW laser and TEA CO 2 laser. Dependence of reaction yield on laser power, measurement of the absorbed quantity of infrared ray and excitation mechanism are explained. Next, isomerizing reactions are reported, and finally, isotope separation is explained. It was found that infrared laser-induced chemical reactions have the selectivity for isotopes. Since it is evident that there are many examples different from thermal and photo-chemical reactions, future collection of the data is expected. (Wakatsuki, Y.)

  8. Progress of laser nuclear fusion research

    International Nuclear Information System (INIS)

    Shiraga, Hiroyuki

    2017-01-01

    This paper describes the principle and features of nuclear fusion using laser, as well as its basic concepts such as high-temperature / high-density implosion system and fast ignition of fuel. At present, researches aiming at nuclear fusion ignition have been developing. As the current state of researches, this paper reviews the situations of FIREX (Fast Ignition Realization Experiment) project of Japan focusing on direct irradiation implosion and fast ignition system, as well as NIF (National Ignition Facility) project of the U.S. aiming at ignition combustion based on indirect irradiation implosion and central ignition system. In collaboration with the National Institute for Fusion Science, Osaka University started FIREX-1 project in 2003. It built a heating laser LFEX of 10 kJ/1 to 10ps, and started an implosion/heating integration experiment in 2009. Currently, it is developing experiment to achieve heating to 5 keV. At NIF, the self-heating of central sparks via energy of α particles generated in the nuclear fusion reaction has been realized. This paper also overviews R and D issues surrounding the lasers for reactors for use in laser nuclear fusion power generators. (A.O.)

  9. Some actinide speciation using laser induced photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    Pollard, P.M.; McMillan, J.W.; Phillips, G.; Thomason, H.P.; Ewart, F.T.

    1988-01-01

    Laser induced photoacoustic spectroscopy is an attractive method for the speciation of actinides in solutions from nuclear disposal studies because it is essentially non-invasive and has a reasonably high sensitivity, down to ca 10 -8 M. A novel true dual beam system has been constructed and commissioned at Harwell with a performance at least equal to any others in existence. It is based on a XeCl excimer laser and a dye laser, beam splitter, two laser power monitors and photoacoustic cells. The wavelength scanning, data collection, and spectra processing and display are controlled by an Apricot computer. The sample and reference cells are housed in an inert atmosphere glove box. Early applications of the equipment described include measurements of Am and Np species under varying conditions of pH, Eh and carbonate concentration. The observations show some correlation with predictions made using the geochemical modelling code PHREEQE. (orig.)

  10. Laser induced energy transfer

    International Nuclear Information System (INIS)

    Falcone, R.W.

    1979-01-01

    Two related methods of rapidly transferring stored energy from one excited chemical species to another are described. The first of these, called a laser induced collision, involves a reaction in which the energy balance is met by photons from an intense laser beam. A collision cross section of ca 10 - 17 cm 2 was induced in an experiment which demonstrated the predicted dependence of the cross section on wavelength and power density of the applied laser. A second type of laser induced energy transfer involves the inelastic scattering of laser radiation from energetically excited atoms, and subsequent absorption of the scattered light by a second species. The technique of producing the light, ''anti-Stokes Raman'' scattering of visible and infrared wavelength laser photons, is shown to be an efficient source of narrow bandwidth, high brightness, tunable radiation at vacuum ultraviolet wavelengths by using it to excite a rare gas transition at 583.7 A. In addition, this light source was used to make the first measurement of the isotopic shift of the helium metastable level at 601 A. Applications in laser controlled chemistry and spectroscopy, and proposals for new types of lasers using these two energy transfer methods are discussed

  11. Study on laser beam welding technology for nuclear power plants title

    International Nuclear Information System (INIS)

    Chida, Itaru; Shiihara, Katsunori; Fukuda, Takeshi; Kono, Wataru; Obata, Minoru; Morishima, Yasuo

    2011-01-01

    Laser beam welding is one of the jointing processes by irradiating laser beam on the material surface locally and widely used at various industrial fields. Toshiba has developed various laser-based maintenance and repair technologies and already applied them to several existing nuclear power plants. Laser cladding is a technique to weld the corrosion resistant metal onto a substrate surface by feeding filler wire to improve the corrosion resistance. Temper-bead welding is the heat input process to provide the desired microstructure properties of welded low alloy steels without post weld heat treatment, by inducing proper heat cycle during laser welding. Both laser welding technologies would be performed underwater by blowing the shielding gas for creating the local dry area. In this report, some evaluation results of material characteristics by temper-bead welding to target at Reactor Coolant System nozzle of PWR are presented. (author)

  12. Generation of laser-induced fast neutron and its application

    International Nuclear Information System (INIS)

    Cha, Hyung Ki; Lee, S.; Kwon, D.; Nam, S.; Park, S.; Rhee, Y.; Jung, Y.; Lee, K.; Cha, Y.; Kwon, S.; Lim, C.; Han, J.; Park, S.; Chung, C.

    2012-04-01

    The supply of high-efficiency neutron source is still problematic even though a fast neutron source is being accepted increasingly for industrial applications. Radioisotopes and a neutron tube are typically being used, but their neutron flux, lifetime, and price are the limiting factors for more diverse applications. As ultra high power, short pulse laser technologies have been developed, a neutron source generated via laser induced nuclear reaction comes to the fore. The laser induced neutron source has a high peak flux in comparison to the traditional neutron source and is like a point source with its diameter less than 1 mm. These properties can be utilized effectively for the analysis of pulsed fast neutron activation or the studies of a fast neutron material damage and/or recover. The purpose of R and D here is to develop a robust neutron source with a yield of 107 neutrons/s during 1st R and D stage ('07 ∼ '09) and to construct a stable laser neutron source in longer operation and to demonstrate its usefulness for a neutron activation analysis of explosive materials and a neutron impact analysis of crystalline in the second R and D stage ('10 ∼ '11)

  13. Advanced methods for nuclear reactor gas laser coupling

    International Nuclear Information System (INIS)

    Miley, G.H.; Verdeyen, J.T.

    1978-06-01

    Research is described that led to the discovery of three nuclear-pumped lasers (NPLs) using mixtures of Ne--N 2 , He--Hg, and He or Ne with CO or CO 2 . The Ne--N 2 NPL was the first laser obtained with modest neutron fluxes from a TRIGA reactor (vs fast burst reactors used elsewhere in such work), the He--Hg NPL was the first visible nuclear-pumped laser, while the Ne--CO and He--CO 2 lasers are the first to provide energy storage on a millisecond time scale. Important potential applications of NPLs include coupling and power transmission from remote power stations such as nuclear plants in satellites and neutron-feedback operation of inertial confinement fusion plants

  14. Application of the nuclear microprobe to the study of organic and inorganic composition of teeth irradiated by a laser beam

    International Nuclear Information System (INIS)

    Sommer, F.; Engelmann, Ch.; Couble, Ml.; Magloire, H.; Bonnin, P.

    1986-01-01

    The nuclear microprobe uses both direct observation of nuclear reactions induced by deuterons and X ray emission induced by protons or deuterons. Thanks to these techniques, concentration profiles of the main elements (C, N, P, Ca...) contained in different parts of healthy teeth (enamel, dentine and cementum) are drawn in control zones and laser irradiated zones. The results obtained show that important perturbations appear during the irradiation by the laser beam; we observe successively, depleted zones in carbon and nitrogen which contain calcium and phosphorus and hypomineralized zones which contain organic material. 10 refs [fr

  15. Laser-induced damage in optical materials

    CERN Document Server

    Ristau, Detlev

    2014-01-01

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

  16. Self-sustaining nuclear pumped laser-fusion reactor experiment

    International Nuclear Information System (INIS)

    Boody, F.P.; Choi, C.K.; Miley, G.H.

    1977-01-01

    The features of a neutron feedback nuclear pumped (NFNP) laser-fusion reactor equipment were studied with the intention of establishing the feasibility of the concept. The NFNP laser-fusion concept is compared schematically to electrically pumped laser fusion. The study showed that, once a method of energy storage has been demonstrated, a self-sustaining fusion-fission hybrid reactor with a ''blanket multiplication'' of two would be feasible using nuclear pumped Xe F* excimer lasers having efficiencies of 1 to 2 percent and D-D-T pellets with gains of 50 to 100

  17. Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

    International Nuclear Information System (INIS)

    Babushok, V.I.; DeLucia, F.C.; Gottfried, J.L.; Munson, C.A.; Miziolek, A.W.

    2006-01-01

    A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of the double pulse laser induced breakdown spectroscopy technique: collinear, orthogonal pre-spark, orthogonal pre-heating and dual pulse crossed beam modes. In addition, combinations of laser pulses with different wavelengths, different energies and durations were studied, thus providing flexibility in the choice of wavelength, pulse width, energy and pulse sequence. The double pulse laser induced breakdown spectroscopy approach provides a significant enhancement in the intensity of laser induced breakdown spectroscopy emission lines up to two orders of magnitude greater than a conventional single pulse laser induced breakdown spectroscopy. The double pulse technique leads to a better coupling of the laser beam with the plasma plume and target material, thus providing a more temporally effective energy delivery to the plasma and target. The experimental results demonstrate that the maximum effect is obtained at some optimum separation delay time between pulses. The optimum value of the interpulse delay depends on several factors, such as the target material, the energy level of excited states responsible for the emission, and the type of enhancement process considered. Depending on the specified parameter, the enhancement effects were observed on different time scales ranging from the picosecond time level (e.g., ion yield, ablation mass) up to the hundred microsecond level (e.g., increased emission intensity for laser induced breakdown spectroscopy of submerged metal target in water). Several suggestions have been proposed to explain

  18. Development of a fiber-coupled laser-induced breakdown spectroscopy instrument for analysis of underwater debris in a nuclear reactor core

    International Nuclear Information System (INIS)

    Saeki, Morihisa; Iwanade, Akio; Ohba, Hironori; Ito, Chikara; Wakaida, Ikuo; Thornton, Blair; Sakka, Tetsuo

    2014-01-01

    To inspect the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi nuclear power plant (F1-NPP), a transportable fiber-coupled laser-induced breakdown spectroscopy (LIBS) instrument has been developed. The developed LIBS instrument was designed to analyze underwater samples in a high-radiation field by single-pulse breakdown with gas flow or double-pulse breakdown. To check the feasibility of the assembled fiber-coupled LIBS instrument for the analysis of debris material (mixture of the fuel core, fuel cladding, construction material and so on) in the F1-NPP, we investigated the influence of the radiation dose on the optical transmittance of the laser delivery fiber, compared data quality among various LIBS techniques for an underwater sample and studied the feasibility of the fiber-coupled LIBS system in an analysis of the underwater sample of the simulated debris in F1-NPP. In a feasible study conducted by using simulated debris, which was a mixture of CeO 2 (surrogate of UO 2 ), ZrO 2 and Fe, we selected atomic lines suitable for the analysis of materials, and prepared calibration curves for the component elements. The feasible study has guaranteed that the developed fiber-coupled LIBS system is applicable for analyzing the debris materials in the F1-NPP. (author)

  19. Femtosecond laser-induced herringbone patterns

    Science.gov (United States)

    Garcell, Erik M.; Lam, Billy; Guo, Chunlei

    2018-06-01

    Femtosecond laser-induced herringbone patterns are formed on copper (Cu). These novel periodic structures are created following s-polarized, large incident angle, femtosecond laser pulses. Forming as slanted and axially symmetric laser-induced periodic surface structures along the side walls of ablated channels, the result is a series of v-shaped structures that resemble a herringbone pattern. Fluence mapping, incident angle studies, as well as polarization studies have been conducted and provide a clear understanding of this new structure.

  20. Laser-spectroscopic nuclear-structure studies on radioactive silver and indium isotopes

    International Nuclear Information System (INIS)

    Dinger, U.

    1988-05-01

    Neutron-deficient silver and neutron-rich indium isotopes were studied by collinear laser spectroscopy. The neutron-deficient nuclei 101 , 103 , 104 , 105 , 105m , 106m Ag were produced as evaporation-residual nuclei in heavy-ion fusion reactions at the mass separator of the GSI in Darmstadt. The fourteen studied indium isotopes and isomers with even mass number in the range 112-126 In were produced by 600-MeV-proton induced fission of a uranium carbide target at the ISOLDE separator in Geneva. The mass-separated ion beam was subsequently deviated electrostatically, neutralized in a sodium vapor and superposed with a c w dye laser. A photon counting system detected the resonance fluorescence of the induced transitions. The hyperfine structure and the isotope shift of the 4d 9 5s 2 2 D 5/2 → 4d 10 6p 2 P 3/2 transition (λ=547.7 nm) in silver and the 5p 2 P 1/2,3/2 → 6s 2 s 1/2 transition (λ=410 respectively 451 nm) in indium were measured. While in indium for the analysis of the data earlier work could be referred to, in silver a detailed analysis of the isotope shift and hyperfine structure was performed by means of ab initio calculations and semi-empirical procedures. Thereby the configuration interactions were especially considered. The nuclear moments were discussed in the framework of existing nuclear models regarding nuclear-spectroscopic informations. (orig./HSI) [de

  1. D-D nuclear fusion processes induced in polyethylene foams by TW Laser-generated plasma

    Directory of Open Access Journals (Sweden)

    Torrisi L.

    2015-01-01

    Full Text Available Deuterium-Deuterium fusion processes were generated by focusing the 3 TW PALS Laser on solid deuterated polyethylene targets placed in vacuum. Deuterium ion acceleration of the order of 4 MeV was obtained using laser irradiance Iλ2 ∼ 5 × 1016 W μm2/cm2 on the target. Thin and thick targets, at low and high density, were irradiated and plasma properties were monitored “on line” and “off line”. The ion emission from plasma was monitored with Thomson Parabola Spectrometer, track detectors and ion collectors. Fast semiconductor detectors based on SiC and fast plastic scintillators, both employed in time-of-flight configuration, have permitted to detect the characteristic 3.0 MeV protons and 2.45 MeV neutrons emission from the nuclear fusion reactions. From massive absorbent targets we have evaluated the neutron flux by varying from negligible values up to about 5 × 107 neutrons per laser shot in the case of foams targets, indicating a reaction rate of the order of 108 fusion events per laser shot using “advanced targets”.

  2. Laser pulse heating of nuclear fuels for simulation of reactor power

    Indian Academy of Sciences (India)

    Laser applications; nuclear fuel elements; nuclear safety. ... accident (LOCA) and reactivity initiated accident (RIA), a laser pulse heating system is under ... As a prelude to work on irradiated nuclear fuel specimens, pilot studies on unirradiated ...

  3. Nuclear transitions induced by atomic excitations

    International Nuclear Information System (INIS)

    Dyer, P.; Bounds, J.A.; Haight, R.C.; Luk, T.S.

    1988-01-01

    In the two-step pumping scheme for a gamma-ray laser, an essential step is that of exciting the nucleus from a long-lived storage isomer to a nearby short- lived state that then decays to the upper lasing level. An experiment is in progress to induce this transfer by first exciting the atomic electrons with UV photons. The incident photons couple well to the electrons, which then couple via a virtual photon to the nucleus. As a test case, excitation of the 235 U nucleus is being sought, using a high- brightness UV laser. The excited nuclear state, having a 26- minute half-life, decays by internal conversion, resulting in emission of an atomic electron. A pulsed infrared laser produces an atomic beam of 235 U which is then bombarded by the UV laser beam. Ions are collected, and conversion electrons are detected by a channel electron multiplier. In preliminary experiments, an upper limit of 7 x 10 -5 has been obtained for the probability of exciting a 235 U atom in the UV beam for one picosecond at an intensity of about 10 15 W/cm 2 . Experiments with higher sensitivities and at higher UV beam intensities are underway

  4. Measurement of Irradiated Pyroprocessing Samples via Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Phongikaroon, Supathorn [Virginia Commonwealth Univ., Richmond, VA (United States)

    2016-10-31

    The primary objective of this research is to develop an applied technology and provide an assessment to remotely measure and analyze the real time or near real time concentrations of used nuclear fuel (UNF) dissolute in electrorefiners. Here, Laser-Induced Breakdown Spectroscopy (LIBS), in UNF pyroprocessing facilities will be investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in the media of solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis|one measurement/laser pulse, or average spectra from multiple laser pulses for greater accuracy in < 2 minutes; (ii) Direct detection of elements and impurities in the system with low detection limits|element specific, ranging from 2-1000 ppm for most elements; and (iii) Near non-destructive elemental analysis method (about 1 g material). One important challenge to overcome is achieving high-resolution spectral analysis to quantitatively analyze all important fission products and actinides. Another important challenge is related to accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment with an argon atmosphere.

  5. Laser cutting of thick steel plates with 30 kW fiber laser for nuclear decommissioning

    International Nuclear Information System (INIS)

    Tamura, Koji

    2015-01-01

    Laser cutting technologies of the thick steel plates for the nuclear decommissioning were developed with a 30 kW fiber laser. Plates of stainless steel and carbon steel more than 100 mm thick were successfully cut, indicating that this technology is promising for the application to the nuclear decommissioning. (author)

  6. Study on process of laser cladded nuclear valve parts

    International Nuclear Information System (INIS)

    Zhang Chunliang

    2000-01-01

    The microstructure and performances of the Co-base alloy coatings that are formed by laser cladding, plasma spurt welding and arc surfacing on the nuclear valve-sealing surface have been studied and compared. The combination costs of laser cladding, plasma spurt welding and arc, surfacing have been analyzed and compared. The results showed that the laser cladding processing has the advantages of high efficiency, low energy cost, a little machining allowance, high rate of finished products and low combination cost, compared with plasma spurt welding processing and arc surfacing processing. The laser cladding technology can improve the qualities of nuclear valve parts and increase their service life. Therefore, the laser cladding processing is a new technology with developing potential

  7. Laser-Ultrasonic Testing and its Applications to Nuclear Reactor Internals

    Science.gov (United States)

    Ochiai, M.; Miura, T.; Yamamoto, S.

    2008-02-01

    A new nondestructive testing technique for surface-breaking microcracks in nuclear reactor components based on laser-ultrasonics is developed. Surface acoustic wave generated by Q-switched Nd:YAG laser and detected by frequency-stabilized long pulse laser coupled with confocal Fabry-Perot interferometer is used to detect and size the cracks. A frequency-domain signal processing is developed to realize accurate sizing capability. The laser-ultrasonic testing allows the detection of surface-breaking microcrack having a depth of less than 0.1 mm, and the measurement of their depth with an accuracy of 0.2 mm when the depth exceeds 0.5 mm including stress corrosion cracking. The laser-ultrasonic testing system combined with laser peening system, which is another laser-based maintenance technology to improve surface stress, for inner surface of small diameter tube is developed. The generation laser in the laser-ultrasonic testing system can be identical to the laser source of the laser peening. As an example operation of the system, the system firstly works as the laser-ultrasonic testing mode and tests the inner surface of the tube. If no cracks are detected, the system then changes its work mode to the laser peening and improves surface stress to prevent crack initiation. The first nuclear industrial application of the laser-ultrasonic testing system combined with the laser peening was completed in Japanese nuclear power plant in December 2004.

  8. Development of YAG laser cutting system for decommissioning nuclear equipments

    International Nuclear Information System (INIS)

    Kasai, Takeshi; Nitta, Kazuhiko; Hosoda, Hiroshi.

    1995-01-01

    Technology of remote controlled cutting and reduction of generative secondary products have been required to the cutting system for decommissioning nuclear equipments. At a point of view that laser cutting technology by use of a Nd:YAG laser is effective, we have developed the laser cutting machine and carried out cutting tests for several stainless steel plates. As a result, the stainless steel plate with a thickness of 22mm could be cut by using an optical fiber which can flexibly propagate laser power, and possibility of application of this laser cutting system to decommissioning nuclear equipments was verified. (author)

  9. Development of YAG laser cutting system for decommissioning nuclear equipments

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, Takeshi [Fuji Electric Co. Research and Development Ltd., Yokosuka, Kanagawa (Japan); Nitta, Kazuhiko; Hosoda, Hiroshi

    1995-07-01

    Technology of remote controlled cutting and reduction of generative secondary products have been required to the cutting system for decommissioning nuclear equipments. At a point of view that laser cutting technology by use of a Nd:YAG laser is effective, we have developed the laser cutting machine and carried out cutting tests for several stainless steel plates. As a result, the stainless steel plate with a thickness of 22mm could be cut by using an optical fiber which can flexibly propagate laser power, and possibility of application of this laser cutting system to decommissioning nuclear equipments was verified. (author).

  10. On-line determination of iodine in nuclear fuel reprocessing off-gas streams by a combination of laser-induced fluorimetry and laser photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    Kuno, Yusuke; Sato, Souichi; Masui, Jinichi

    1992-01-01

    The on-line determination of molecular iodine and organic iodides in nuclear fuel reprocessing off-gas streams containing high concentrations of NO x gas was studied. Ultraviolet radiation is used to convert organic iodides into molecular iodine. The approximate concentration of iodine before and after the photochemical conversion in the presence of NO x gas was first determined by laser-induced fluorimetry. NO 2 was determined by photoacoustic spectroscopy, correcting the acoustic signal due to iodine by using the approximate iodine concentration. NO was determined from the concentrations of NO 2 before and after the photoirradiation based on the photochemical fraction changes of NO and NO 2 . The quenching of the fluorimetry due to NO and NO 2 was finally corrected with the NO and NO 2 concentrations obtained. The detection limit of the proposed method is 10 nl 1 -1 . 7 figs., 2 tabs., 11 refs

  11. Effect of laser pulse energies in laser induced breakdown spectroscopy in double-pulse configuration

    International Nuclear Information System (INIS)

    Benedetti, P.A.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

    2005-01-01

    In this paper, the effect of laser pulse energy on double-pulse laser induced breakdown spectroscopy signal is studied. In particular, the energy of the first pulse has been changed, while the second pulse energy is held fixed. A systematic study of the laser induced breakdown spectroscopy signal dependence on the interpulse delay is performed, and the results are compared with the ones obtained with a single laser pulse of energy corresponding to the sum of the two pulses. At the same time, the crater formed at the target surface is studied by video-confocal microscopy, and the variation in crater dimensions is correlated to the enhancement of the laser induced breakdown spectroscopy signal. The results obtained are consistent with the interpretation of the double-pulse laser induced breakdown spectroscopy signal enhancement in terms of the changes in ambient gas pressure produced by the shock wave induced by the first laser pulse

  12. Numerical simulation for nuclear pumped laser

    Energy Technology Data Exchange (ETDEWEB)

    Sakasai, Kaoru [Japan Atomic Energy Research Inst., Tokyo (Japan)

    1998-07-01

    To apply nuclear pumped laser of {sup 3}He-Ne-Ar gas to detect neutron, the optimum gas mixture was investigated by numerical simulation. When {sup 3}He-Ne-Ar mixture gas are irradiated by neutron, proton and triton with high velocity are produced by {sup 3}He(np)T and two charge particles ionized {sup 3}He, Ne and Ar which reacted each other and attained to 3p`(1/2){sub 0}-3S`(1/2). The calculation method is constructed by defining the rate equations of each ion and exited atom and the electron energy balance equation and by time integrating the simultaneous differential equations of the above two equations and the law of conservation of charge. Penning ionization and energy transport by elastic collision of neutral atom were considered in the transport process of electron energy direct ionization by secondary charge particle. Calculation time was 1 msec. The optimum component was shown 3 atm He, 24 Torr He and 8 Torr Ar by simulation. Laser oscilation was generated under the conditions 3.3 x 10{sup 14} (N/cm{sup 2}/5) thermal neutron flux at 50 cm laser cell length and 99% coefficient of reflection of mirror. After laser oscilation, laser output was proportional to neutron flux. These results showed nuclear pumped laser of {sup 3}He-Ne-Ar was able to detect optically neutron. (S.Y)

  13. Filament-induced remote surface ablation for long range laser-induced breakdown spectroscopy operation

    International Nuclear Information System (INIS)

    Rohwetter, Ph.; Stelmaszczyk, K.; Woeste, L.; Ackermann, R.; Mejean, G.; Salmon, E.; Kasparian, J.; Yu, J.; Wolf, J.-P.

    2005-01-01

    We demonstrate laser induced ablation and plasma line emission from a metallic target at distances up to 180 m from the laser, using filaments (self-guided propagation structures ∼ 100 μm in diameter and ∼ 5 x 10 13 W/cm 2 in intensity) appearing as femtosecond and terawatt laser pulses propagating in air. The remarkable property of filaments to propagate over a long distance independently of the diffraction limit opens the frontier to long range operation of the laser-induced breakdown spectroscopy technique. We call this special configuration of remote laser-induced breakdown spectroscopy 'remote filament-induced breakdown spectroscopy'. Our results show main features of filament-induced ablation on the surface of a metallic sample and associated plasma emission. Our experimental data allow us to estimate requirements for the detection system needed for kilometer-range remote filament-induced breakdown spectroscopy experiment

  14. Temporal Evolution Study of the Plasma Induced by CO2 Pulsed Laser on Targets of Titanium Oxides

    Czech Academy of Sciences Publication Activity Database

    Diaz, L.; Camacho, J.J.; Sanz, M.; Hernández, M.; Jandová, Věra; Castillejo, M.

    2013-01-01

    Roč. 86, AUG 1 (2013), s. 88-93 ISSN 0584-8547 Grant - others:DGICYT(ES) CTQ2008-05393/BQU; DGICYT(ES) CTQ2010-15680/BQU; CAM(ES) Geomateriales S2009/ Institutional support: RVO:67985858 Keywords : laser induced breakdown spectroscopy * time-resolved optical emission spectroscopy * high-power IR CO2 pulsed laser Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 3.150, year: 2013

  15. Metastability exchange optical pumping in 3He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation

    International Nuclear Information System (INIS)

    Batz, Marion

    2011-01-01

    Advances in metastability exchange optical pumping (MEOP) of 3 He at high laser powers, with its various applications, but also at high gas pressures p 3 and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B≤30 mT and p 3 =0.63-2.45 mbar. 3 He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.

  16. Risks induced by laser radiation; Risques induits par le rayonnement laser

    Energy Technology Data Exchange (ETDEWEB)

    Courant, D [CEA Fontenay-aux-Roses, 92 (France). Dept. de Radiobiologie et de Radiopathologie

    2001-07-01

    The use of lasers is often dangerous because of the emitted power, the wave length, the conduction system(optical fiber, wave guide, mirrors) and the use conditions. The safety notion involves the precise knowledge of materials, the biological effects in function of laser emission parameters, the knowledge of protection standards, the observance of use rules and the personnel training. This chapter treats the risks induced by the beam. It gives the different biological effects induced by the laser beam, at the eye and skin levels that are at the origin of exposure limits and the lasers classification recommended by the protection standards. (N.C.)

  17. Laser measurements and nuclear structure

    International Nuclear Information System (INIS)

    Leander, G.A.

    1982-01-01

    The nuclear states amenable to laser studies are reviewed with respect to their structure. Systematic predictions are made, e.g., for magnetic moments of parity-mixed intrinsic orbitals in the Ac isotopes and for the shape of the known high-spin isomers in the Pb region

  18. Nuclear fuel safety studies by laser pulse heating

    International Nuclear Information System (INIS)

    Viswanadham, C.S.; Kumar, Santosh; Dey, G.K.; Kutty, T.R.G.; Khan, K.B.; Kumar, Arun; Jathar, V.P.; Sahoo, K.C.

    2009-01-01

    The behaviour of nuclear fuels under transient heating conditions is vital to nuclear safety. A laser pulse based heating system to simulate the transient heating conditions experienced by the fuel during reactor accidents like LOCA and RIA is under development at BARC, Mumbai. Some of the concepts used in this system are under testing in pilot studies. This paper describes the results of some pilot studies carried out on unirradiated UO 2 specimens by laser pulse heating, followed by metallography and X-ray diffraction measurements. (author)

  19. Effect of laser spot size on energy balance in laser induced plasmas

    International Nuclear Information System (INIS)

    Pant, H.C.; Sharma, S.; Bhawalkar, D.D.

    1980-01-01

    The effect of the laser spot size on laser light absorption in laser induced plasmas from solid targets was studied. It was found that at a constant laser intensity on the target, reduction in the laser spot size enhances the net laser energy absorption. It was also observed that the laser light reflection from the target becomes more diffused when the focal spot size is reduced

  20. Laser-induced breakdown spectroscopy analysis of asbestos

    International Nuclear Information System (INIS)

    Caneve, L.; Colao, F.; Fabbri, F.; Fantoni, R.; Spizzichino, V.; Striber, J.

    2005-01-01

    Laser-induced breakdown spectroscopy was applied to test the possibility of detecting and identifying asbestos in different samples in view of the perspective at field operation without sample preparation which is peculiar to this technique. Several like-resin materials were first investigated by laser-induced breakdown spectroscopy, in order to find an asbestos container assuring safe laboratory operation during the material characterization aimed to identify indicators suitable for a quick identification on field. Successively, spectra of asbestos samples of both in serpentine and amphibole forms were measured and the variability in elemental composition was calculated from the emission spectra. Ratios of intensities of characteristic elements were tested as indicators for asbestos recognition. Laser-induced breakdown spectroscopy results were compared with those obtained by analyzing the same asbestos samples with a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, a good correlation was found for Mg/Si and Fe/Si, thus showing the capability of laser-induced breakdown spectroscopy as a diagnostic tool for this category of materials. In particular, it was demonstrated that the method based on two indicators derived from laser-induced breakdown spectroscopy intensity ratios allows to discriminate between asbestos and cements in single shot measurements suitable to field operation

  1. Detection of boron in simulated corrosion products by using a laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Song, K.; Yeon, J-W.; Jung, S-H.; Hwang, J.; Jung, E-C.

    2010-01-01

    In nuclear power plants, many methods for detection of coolant leakage have been developed and employed for the safe operation. However, these methods have many limitations for analyzing and dealing with the corrosion products due to the high radioactivity. LIBS (Laser-induced breakdown spectroscopy) offer a remote and on-site elemental analysis including the boron in the corrosion products with no sample preparation. In this study, we investigated the feasibility of detecting boron and analyzing an elemental composition of boron-containing iron oxides with the LIBS, in order to develop a coolant leakage detection system. First, we prepared five different boron-containing iron oxides and the element ratios were determined by using ICP-AES (inductive coupled plasma-atomic emission spectrometer). After this, the laser induced emission spectra of these iron oxides were obtained by using a 266 nm Nd:YAG laser. The B/Fe ratios of the oxides were determined by comparing the intensities of the B emission peak at 249.844 nm with those of the Fe peak at 250.217 nm as an internal reference. It was confirmed that the B contents in the oxides could be analyzed over 0.1 wt% by the laser induced breakdown spectroscopic technique. (author)

  2. Laser-Induced Breakdown Spectroscopy (LIBS) in a Novel Molten Salt Aerosol System.

    Science.gov (United States)

    Williams, Ammon N; Phongikaroon, Supathorn

    2017-04-01

    In the pyrochemical separation of used nuclear fuel (UNF), fission product, rare earth, and actinide chlorides accumulate in the molten salt electrolyte over time. Measuring this salt composition in near real-time is advantageous for operational efficiency, material accountability, and nuclear safeguards. Laser-induced breakdown spectroscopy (LIBS) has been proposed and demonstrated as a potential analytical approach for molten LiCl-KCl salts. However, all the studies conducted to date have used a static surface approach which can lead to issues with splashing, low repeatability, and poor sample homogeneity. In this initial study, a novel molten salt aerosol approach has been developed and explored to measure the composition of the salt via LIBS. The functionality of the system has been demonstrated as well as a basic optimization of the laser energy and nebulizer gas pressure used. Initial results have shown that this molten salt aerosol-LIBS system has a great potential as an analytical technique for measuring the molten salt electrolyte used in this UNF reprocessing technology.

  3. Laser-induced stresses versus mechanical stress power measurements during laser ablation of solids

    International Nuclear Information System (INIS)

    Shannon, M.A.; Russo, R.E.

    1995-01-01

    Laser-induced stresses resulting from high-power laser-material interactions have been studied extensively. However, the rate of change in mechanical energy, or stress power, due to laser-induced stresses has only recently been investigated. An unanswered question for monitoring laser-material interactions in the far-field is whether stress power differs from stresses measured, particularly with respect to laser-energy coupling to a solid target. This letter shows experimental acoustic data which demonstrate that stress power measured in the far field of the target shows changes in laser-energy coupling, whereas the stresses measured do not. For the ambient medium above the target, stress power and stress together reflect changes in laser-energy coupling. copyright 1995 American Institute of Physics

  4. Metastability exchange optical pumping in {sup 3}He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Batz, Marion

    2011-07-08

    Advances in metastability exchange optical pumping (MEOP) of {sup 3}He at high laser powers, with its various applications, but also at high gas pressures p{sub 3} and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B{<=}30 mT and p{sub 3}=0.63-2.45 mbar. {sup 3}He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.

  5. A Comparison of Laser-induced Bremsstrahlung and Laser Compton Scattering for (γ, n) Photo-transmutation of Hazardous Nuclear Waste

    International Nuclear Information System (INIS)

    Rehman, Haseeb ur; Lee, Jiyoung; Kim, Yonghee

    2015-01-01

    This paper also presents sensitivity analysis to yield the maximum possible photo-transmutation rates. In general the possibility of radionuclide transmutation using photo-neutron reaction is evaluated in this work. In this paper a detailed methodology to calculate transmutation reaction rates using Laser Induced Bremsstrahlung (LIB) and Laser Compton Scattering (LCS) has been discussed. The methodology was validated by comparing the calculated reaction rates against published data in publically accessed literatures. In the second half of the paper, the authors present a novel concept to narrow down the LCS photon spectrum to an energy range that matches with the resonance region of a particular radionuclide. This is particularly useful considering hazardous waste is usually a mix of different isotopes. As such, being able to tune the LCS photon into any narrow energy range so as to selectively transmute any particular isotope of interest in the hazardous waste mixture would be very desirable. LCS spectrum is highly sensitive to the electron beam energy, laser power, laser luminosity and Compton backscattering angle. From the results it is quite evident that LCS is much better option for the radionuclide transmutation as reaction rates for the LCS is much higher than LIB method even for very small laser power. It can be seen even for the optimistic reaction rate calculations with Bremsstrahlung method reaction rate is much lower than LCS case for 10 Hz repetition rate. If repetition rate of laser 100 Hz then LIB reaction rate has the same order of the magnitude as the reaction rate via LCS. Higher Laser Powers can yield very high transmutation rates

  6. Laser-induced breakdown spectroscopy measurements of uranium and thorium powders and uranium ore

    Energy Technology Data Exchange (ETDEWEB)

    Judge, Elizabeth J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, James E., E-mail: jbarefield@lanl.gov [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Berg, John M. [Manufacturing Engineering and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, Samuel M.; Havrilla, George J.; Montoya, Velma M.; Le, Loan A.; Lopez, Leon N. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-05-01

    Laser-induced breakdown spectroscopy (LIBS) was used to analyze depleted uranium and thorium oxide powders and uranium ore as a potential rapid in situ analysis technique in nuclear production facilities, environmental sampling, and in-field forensic applications. Material such as pressed pellets and metals, has been extensively studied using LIBS due to the high density of the material and more stable laser-induced plasma formation. Powders, on the other hand, are difficult to analyze using LIBS since ejection and removal of the powder occur in the laser interaction region. The capability of analyzing powders is important in allowing for rapid analysis of suspicious materials, environmental samples, or trace contamination on surfaces since it most closely represents field samples (soil, small particles, debris etc.). The rapid, in situ analysis of samples, including nuclear materials, also reduces costs in sample collection, transportation, sample preparation, and analysis time. Here we demonstrate the detection of actinides in oxide powders and within a uranium ore sample as both pressed pellets and powders on carbon adhesive discs for spectral comparison. The acquired LIBS spectra for both forms of the samples differ in overall intensity but yield a similar distribution of atomic emission spectral lines. - Highlights: • LIBS analysis of mixed actinide samples: depleted uranium oxide and thorium oxide • LIBS analysis of actinide samples in powder form on carbon adhesive discs • Detection of uranium in a complex matrix (uranium ore) as a precursor to analyzing uranium in environmental samples.

  7. Faraday cup measurements of a laser-induced plasma for a laser-proton acceleration

    International Nuclear Information System (INIS)

    Park, Seong Hee; Jeong, Young Uk; Lee, Ki Tae

    2006-01-01

    Experiments for the generation of laser-induced protons were performed in collaboration with Advanced Photonics Research Institute (APRI). An intensity of 3 X 10 18 W/cm 2 was delivered to a 17-μm Al target, and the Faraday Cup signals of the charged particles generated by the laser-plasma interaction were measured. In this paper, we discuss the first experimental results of laser-induced proton generation using the APRI laser and report on the feasibility of current measurement for charged-particles when using a Faraday cup.

  8. Investigation on laser welding characteristics for appendage of bearing pads of nuclear fuel element

    International Nuclear Information System (INIS)

    Kim, S. S.; Kim, W. K.; Park, C. H.; Ko, J. H.; Lee, J. W.; Yang, M. S.

    2001-01-01

    In CANDU nuclear fuel manufacturing the brazing technology has been adopted conventionally to attach the bearing pads of nuclear fuel elements. However, in order to meet good performance of nuclear fuel and improved working efficiency, we started developing the laser welding technology for attachments of the bearing pads. Since the YAG laser can be suitable for small parts and transmit the beam through the optical fiber, the process is corresponding to mass-production with working shops. Making the most of this feature, we have developed the laser welding for appendage of the bearing pads of nuclear fuel elements, and has studied on the laser welding characterisitcs of appendages for nuclear fuel element

  9. Development of portable laser peening systems for nuclear power reactors

    International Nuclear Information System (INIS)

    Chida, Itaru; Uehara, Takuya; Yoda, Masaki; Miyasaka, Hiroyuki; Kato, Hiromi

    2009-01-01

    Stress corrosion cracking (SCC) is the major factor to reduce the reliability of aged reactor components. Toshiba has developed various laser-based maintenance and repair technologies and applied them to existing nuclear power plants. Laser-based technology is considered to be the best tool for remote processing in nuclear power plants, and particularly so for the maintenance and repair of reactor core components. Accessibility could be drastically improved by a simple handling system owing to the absence of reactive force against laser irradiation and the flexible optical fiber. For the preventive maintenance, laser peening technology was developed and applied to reactor components in operating BWRs and PWRs. Laser peening is a novel process to improve residual stress from tensile to compressive on material surface layer by irradiating focused high-power laser pulses in water without any surface preparations. Laser peening systems, which deliver laser pulses with mirrors or through an optical fiber, were developed and have been applied to preventive maintenance against SCC in nuclear power reactors since 1999. Each system was composed of laser oscillators, a beam delivery system, a laser irradiation head, remote handling equipment and a monitor/control system. Beam delivery with mirrors was accomplished through alignment/tracking functions with sufficient accuracy. Reliable fiber-delivery was attained by the development of a novel input coupling optics and an irradiation head with auto-focusing. Recently, we have developed portable laser peening (PLP) system which could employ both mirror- and fiber- delivery technologies. Size and weight of the PLP system for BWR bottom was almost 1/25 compared to the previous system. PLP system would be the applicable to both BWRs and PWRs as one of the maintenance technologies. (author)

  10. Laser induced damage threshold on metallic surfaces during laser cleaning

    CSIR Research Space (South Africa)

    Labuschagne, K

    2005-07-01

    Full Text Available laser paint removal. Laser induced damage on 316L stainless steel was studied, with the target subjected to single and multiple pulse irradiations using a Q-switched Nd:YAG, with fluences between 0.15 and 11.8 J/cm2. Several different damage morphologies...

  11. Nuclear structure considerations for gamma-ray lasers

    International Nuclear Information System (INIS)

    Strottman, D.; Arthur, E.D.; Madland, D.G.

    1985-01-01

    Presented are initial results in our investigation of the nuclear physics issues of gamma-ray lasers. These include the questions of what is known from existing experimental data, where does one optimally search for nuclei displaying simultaneously both closely lying levels and nuclear isomerism, and which theoretical models does one employ for systematic searches for candidate nuclei and for calculation of detailed candidate level properties

  12. Investigation of relativistic laser-plasmas using nuclear diagnostics; Untersuchung relativistischer Laserplasmen mittels nukleardiagnostischer Verfahren

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Marc M.

    2011-01-19

    The present work explores with the development of a novel nuclear diagnostic method for the investigation of the electron dynamics in relativistic laser-plasma interactions. An additional aim of this work was the determination of the real laser peak intensity via the interaction of an intense laser short-pulse with a solid target. The nuclear diagnostics is based on a photo-neutron disintegration nuclear activation method. The main constituent of the nuclear diagnostic are novel pseudoalloic activation targets as a kind of calorimeter to measure the high-energy bremsstrahlung produced by relativistic electrons. The targets are composed of several stable isotopes with different ({gamma},xn)-reaction thresholds. The activated nuclides were identified via the characteristic gamma-ray decay spectrum by using high-resolution gamma spectroscopy after the laser irradiation. Via the gamma spectroscopy the ({gamma},xn)-reaction yields were determined. The high-energy bremsstrahlung spectrum has been deconvolved using a novel analysis method based on a modified Penfold-Leiss method. This facilitates the reconstruction of the spectrum of bremsstrahlung photons without any anticipated fit procedures. Furthermore, the characterization of the corresponding bremsstrahlung electrons in the interaction zone is accessible immediately. The consolidated findings about the properties of the relativistic electrons were used to determine the real peak intensity at the laser-plasma interaction zone. In the context of this work, experiments were performed at three different laser facilities. First Experiments were carried out at the 100 TW laser facility at Laboratoire pour l'Utilisation des Lasers Intense (LULI) in France and supplementary at the Vulcan laser facility at Rutherford Appleton Laboratory (RAL) in United Kingdom. The main part of the activation experiments were performed at the PHELIX laser facility (Petawatt High Energy Laser for heavy Ion EXperiments) at GSI

  13. Laser Compton Scattering Gamma Ray Induced Photo-Trasmutation

    CERN Document Server

    Li, Dazhi

    2004-01-01

    High brightness beams of gamma rays produced with laser Compton scattering have the potential to realize photo-transmutation through (γ,n) reaction, implying an efficient method to dispose long-lived fission products. Preliminary investigations have been carried out in understanding the feasibility of development of a transmutation facility to repose nuclear waste. A laser Compton scattering experimental setup based on a storage ring started to generate gamma-ray beams for studying the coupling of gamma photons and nuclear giant resonance. This paper demonstrates the dependency of nuclear transmutation efficiency on target dimensions and gamma ray features. 197Au sample was adopted in our experiment, and experimental results correspond to the theoretical estimations.

  14. The Dawn of Nuclear Photonics with Laser-based Gamma-rays

    International Nuclear Information System (INIS)

    Barty, C.J.

    2011-01-01

    A renaissance in nuclear physics is occurring around the world because of a new kind of incredibly bright, gamma-ray light source that can be created with short pulse lasers and energetic electron beams. These highly Mono-Energetic Gamma-ray (MEGa-ray) sources produce narrow, laser-like beams of incoherent, tunable gamma-rays and are enabling access and manipulation of the nucleus of the atom with photons or so called 'Nuclear Photonics'. Just as in the early days of the laser when photon manipulation of the valence electron structure of the atom became possible and enabling to new applications and science, nuclear photonics with laser-based gamma-ray sources promises both to open up wide areas of practical isotope-related, materials applications and to enable new discovery-class nuclear science. In the United States, the development of high brightness and high flux MEGa-ray sources is being actively pursued at the Lawrence Livermore National Laboratory in Livermore (LLNL), California near San Francisco. The LLNL work aims to create by 2013 a machine that will advance the state of the art with respect to source the peak brightness by 6 orders of magnitude. This machine will create beams of 1 to 2.3 MeV photons with color purity matching that of common lasers. In Europe a similar but higher photon energy gamma source has been included as part of the core capability that will be established at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility in Magurele, Romania outside of Bucharest. This machine is expected to have an end point gamma energy in the range of 13 MeV. The machine will be co-located with two world-class, 10 Petawatt laser systems thus allowing combined intense-laser and gamma-ray interaction experiments. Such capability will be unique in the world. In this talk, Dr. Chris Barty from LLNL will review the state of the art with respect to MEGa-ray source design, construction and experiments and will describe both the ongoing projects

  15. Railgun system using a laser-induced plasma armature

    International Nuclear Information System (INIS)

    Onozuka, M.; Oda, Y.; Azuma, K.

    1996-01-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun. copyright 1996 American Institute of Physics

  16. Railgun system using a laser-induced plasma armature

    Science.gov (United States)

    Onozuka, Masanori; Oda, Yasushi; Azuma, Kingo

    1996-05-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun.

  17. Nuclear excitation via the motion of electrons in a strong laser field

    International Nuclear Information System (INIS)

    Berger, J.F.; Gogny, D.; Weiss, M.S.

    1987-12-01

    A method of switching from a nuclear isomeric state to a lasing state is examined. A semi-classical model of laser-electron-nuclear coupling is developed. In it the electrons are treated as free in the external field of the laser, but with initial conditions corresponding to their atomic orbits. Application is made to testing this model in 235 U and to the design criteria of a gamma-ray laser. 14 refs., 2 tabs

  18. Ablative fractional laser enhances MAL-induced PpIX accumulation

    DEFF Research Database (Denmark)

    Haak, C S; Christiansen, K; Erlendsson, Andrés M

    2016-01-01

    BACKGROUND AND OBJECTIVES: Pretreatment of skin with ablative fractional laser enhances accumulation of topical provided photosensitizer, but essential information is lacking on the interaction between laser channel densities and pharmacokinetics. Hence our objectives were to investigate how...... (range 46-133min) induced fluorescence levels similar to curettage and 180min incubation. Furthermore, MAL 80 and 160mg/g induced similar fluorescence intensities in skin exposed to laser densities of 1, 2 and 5% (p>0.0537, 30-180min). CONCLUSION: MAL-induced protoporphyrin accumulation is augmented...... protoporphyrin accumulation was affected by laser densities, incubation time and drug concentration. METHODS: We conducted the study on the back of healthy male volunteers (n=11). Test areas were pretreated with 2940nm ablative fractional Er:YAG laser, 11.2mJ per laser channel using densities of 1, 2, 5, 10...

  19. Emission Characteristics of Laser-Induced Plasma Using Collinear Long and Short Dual-Pulse Laser-Induced Breakdown Spectroscopy (LIBS).

    Science.gov (United States)

    Wang, Zhenzhen; Deguchi, Yoshihiro; Liu, Renwei; Ikutomo, Akihiro; Zhang, Zhenzhen; Chong, Daotong; Yan, Junjie; Liu, Jiping; Shiou, Fang-Jung

    2017-09-01

    Collinear long and short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulse-width laser with the pulse width of 60 μs under free running (FR) conditions as an external energy source. Comparing the measurement results of stainless steel in air using single-pulse LIBS (SP-LIBS) and DP-LIBS, the emission intensity was markedly enhanced using DP-LIBS. The temperature of plasma induced by DP-LIBS was maintained at a higher temperature under different gate delay time and short pulse-width laser power conditions compared with those measured using short SP-LIBS. Moreover, the variation rates of plasma temperatures measured using DP-LIBS were also lower. The superior detection ability was verified by the measurement of aluminum sample in water. The spectra were clearly detected using DP-LIBS, whereas it cannot be identified using SP-LIBS of short and long pulse widths. The effects of gate delay time and short pulse-width laser power were also discussed. These results demonstrate the feasibility and enhanced detection ability of the proposed collinear long and short DP-LIBS method.

  20. Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

    Directory of Open Access Journals (Sweden)

    Christian G. Parigger

    2010-01-01

    Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

  1. Towards abundant and pollution-free energy. Laser nuclear fusion

    International Nuclear Information System (INIS)

    Robieux, J.

    2008-01-01

    This book shows that it is now practically certain that by the year 2080 laser nuclear fusion will allow to produce an abundant and relatively cheap energy. Thanks to this energy, it will be possible to convert a mixture of CO 2 , H 2 and water into an automotive fuel or a food product. Laser nuclear fusion will use deuterium as fuel and thus oil and gas will become useless. Also, thanks to this new energy source, global warming and starvation will be overcome. The laser fusion concept was introduced by J. Robieux in 1962 just after the discovery of the laser. This idea was immediately accepted and sustained by the French President De Gaulle. The research on laser fusion was initially undertaken at the Marcoussis research centre from the Compagnie Generale d'Electricite (General Electricity Company - CGE). In 1967, the lasers built at Marcoussis were 30 times more powerful than any other laser in the rest of world. A cooperation with the USA started at that time and is still going on today. In 1969, the CEA centre of Limeil realized the world premiere experiments of laser fusion. This book presents the historical aspects and the state-of-the-art of this technology today. It is written in two parts, the first part does not require any scientific knowledge and is accessible to everybody, while the second part can be understood only by readers having a basic scientific background. (J.S.)

  2. Laser applications in nuclear power plants

    Indian Academy of Sciences (India)

    2014-01-09

    Jan 9, 2014 ... we have used laser techniques to cut stainless steel sheets up to 14 mm thickness and stainless steel weld up to ... radioactive environment, reasons being easiness in tool handling, flexibility, non-contact nature ... in nuclear power plants of NPCIL, India, by invoking different innovative techniques. Figure 1.

  3. Laser-induced incandescence applied to dusty plasmas

    NARCIS (Netherlands)

    van de Wetering, F.M.J.H.; Oosterbeek, W.; Beckers, J.; Nijdam, S.; Kovacevic, E.; Berndt, J.

    2016-01-01

    This paper reports on the laser heating of nanoparticles (diameters ≤1 μm) confined in a reactive plasma by short (150 ps) and intense (~63 mJ) UV (355 nm) laser pulses (laser-induced incandescence, LII). Important parameters such as the particle temperature and radius follow from analysis of the

  4. Railgun system using a laser-induced plasma armature

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, M.; Oda, Y.; Azuma, K. [Mitsubishi Heavy Industries, Ltd., 3-3-1, Minatomirai, Nishi-ku, Yokohama 220-84 (Japan)

    1996-05-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun. {copyright} {ital 1996 American Institute of Physics.}

  5. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

    A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self-diffracti......A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self...

  6. Laser spectroscopy used in nuclear physics; La spectroscopie laser appliquee a la physique nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Le Blanc, F

    2001-04-05

    The study of nuclear shapes is a basic topic since it constitutes an excellent ground for testing and validating nuclear models. Measurements of the electron quadrupolar moment, of the nuclear charge radius and of the magnetic dipolar moment shed light on the nuclear deformation. Laser spectroscopy is a specific tool for such measurements, it is based on the interaction of the nucleus with the surrounding electron cloud (hyperfine structure), it is then an external approach of the shape of the nucleus whereas the classical nuclear spectroscopy ({alpha}, {beta} or {gamma}) gives information on the deformation from the inside of the nucleus. The author describes 2 techniques of laser spectroscopy: the colinear spectroscopy directly applied to a beam issued from an isotope separator and the resonant ionization spectroscopy linked with atom desorption that allows the study of particular nuclei. In order to illustrate both methods some effective measurements are presented: - the colinear spectroscopy has allowed the achievement of the complete description of the isomeric state (T = 31 years) of hafnium-178; - The experiment Complis has revealed an unexpected even-odd zigzag effect on very neutron-deficient platinum isotopes; and - the comparison of 2 isotopes of gold and platinum with their isomers has shown that the inversion of 2 levels of neutron, that was found out by nuclear spectroscopy, is in fact a consequence of a change in the nuclear shape. (A.C.)

  7. Detection and evaluation of uranium in different minerals by gamma spectrometry and laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Sergani, F.M.; Khedr, M.A.; Harith, M.A.; El Mongy, S.A.

    2004-01-01

    Analysis, detection and evaluation of source nuclear materials (e.g. uranium) in different minerals by sensitive techniques are a vital objective for uranium exploration, nuclear materials extraction, processing and verification. In this work, uranium in different geological formations was determined using gamma spectrometry and laser induced breakdown spectroscopy (LIBS). The investigated samples were collected from different regions distributed all over Egypt. The samples were then prepared for non-destructive analysis. A hyper pure germanium detector was used to measure the emitted gamma rays of uranium and its daughters in the samples. The concentrations of uranium in ppm (μg/g) in the investigated samples are given and discussed in this work. The highest uranium concentration (4354.9 ppm) was found in uranophane samples of Gattar rocks. In Laser induced breakdown spectroscopy (LIBS) technique, plasma was formed by irradiating the rock surface with focused Q-switched Nd:Yag laser pulses of 7 ns pulse duration at the fundamental wavelength (1064 nm). Atoms and ions originating from the rock surface are excited and ionized in the laser produced hot plasma (∝10 000 K). The plasma emission spectral line is characteristic of the elements present in the plasma and allows identification of the uranium in the uranophane mineral. The strong atomic line at 424.2 nm is used for the qualitative identification of uranium. It can be mentioned that the elevated levels of uranium in some of the investigated uranophane samples are of great economic feasibility to be extracted. (orig.)

  8. Laser-induced cracks in ice due to temperature gradient and thermal stress

    Science.gov (United States)

    Yang, Song; Yang, Ying-Ying; Zhang, Jing-Yuan; Zhang, Zhi-Yan; Zhang, Ling; Lin, Xue-Chun

    2018-06-01

    This work presents the experimental and theoretical investigations on the mechanism of laser-induce cracks in ice. The laser-induced thermal gradient would generate significant thermal stress and lead to the cracking without thermal melting in the ice. The crack density induced by a pulsed laser in the ice critically depends on the laser scanning speed and the size of the laser spot on the surface, which determines the laser power density on the surface. A maximum of 16 cracks within an area of 17 cm × 10 cm can be generated when the laser scanning speed is at 10 mm/s and the focal point of the laser is right on the surface of the ice with a laser intensity of ∼4.6 × 107 W/cm2. By comparing the infrared images of the ice generated at various experimental conditions, it was found that a larger temperature gradient would result in more laser-induced cracks, while there is no visible melting of the ice by the laser beam. The data confirm that the laser-induced thermal stress is the main cause of the cracks created in the ice.

  9. Laser-based analytical monitoring in nuclear-fuel processing plants

    International Nuclear Information System (INIS)

    Hohimer, J.P.

    1978-09-01

    The use of laser-based analytical methods in nuclear-fuel processing plants is considered. The species and locations for accountability, process control, and effluent control measurements in the Coprocessing, Thorex, and reference Purex fuel processing operations are identified and the conventional analytical methods used for these measurements are summarized. The laser analytical methods based upon Raman, absorption, fluorescence, and nonlinear spectroscopy are reviewed and evaluated for their use in fuel processing plants. After a comparison of the capabilities of the laser-based and conventional analytical methods, the promising areas of application of the laser-based methods in fuel processing plants are identified

  10. Heparanase-1 activities in the development of laser induced choroidal neovascularization

    Directory of Open Access Journals (Sweden)

    Bao-Ke Hou

    2013-04-01

    Full Text Available AIM:To investigate the role of heparanase-1 in laser-induced choroidal neovascularization (CNV.METHODS:Experimental CNV was induced by krypton laser photocoagulation in 15 male Brown Norway rats. Fundus fluorescein angiography and histopathological examination were performed in observing the CNV development. The expression and distribution of heparanase-1 protein in the laser lesions were determined by immunohistochemistry and western blotting analysis.RESULTS:The success rate of laser induced CNV was approximately 75% on 3-4 weeks after laser photocoagulation. The protein levels of heparanase-1 increased significantly in the retina-choroidal complex of CNV models when compared to normal rat eyes (P<0.01. Immunostaining confirmed strong heparanase-1 expressions in all laser lesions, and it displayed to be highest at the newly formed blood vessels within the fibrovascular complex in the subretinal space.CONCLUSION:Heparanase-1 is closely involved in the development of laser induced CNV.

  11. Physical aspects of laser applications to modern nuclear technologies

    International Nuclear Information System (INIS)

    Semerok, A.

    2001-11-01

    This report has been presented by the author to obtain his HDR (accreditation to supervise research). After a brief presentation of his domain of skills, of his education, of his professional experience, and his awards, the author gives an overview of his work performed in the field of laser applications to modern nuclear technologies. Notably, he reports experimental studies dealing with the following topics: radiation source for uranium isotope separation by MLIS method, laser isotope separation in atom vapour, laser plasma diagnostics in strong magnetic field, laser ablation-time of flight mass spectrometry for low uranium isotope ratio measurements, laser ablation-optical emission spectroscopy for surface analysis. The report is completed by many published scientific articles

  12. The use of laser-induced breakdown spectroscopy for the determination of fluorine concentration in glass ionomer cement

    Czech Academy of Sciences Publication Activity Database

    Kratochvíl, T.; Pouzar, M.; Novotný, K.; Havránek, Vladimír; Černohorský, T.; Zvolská, M.

    2013-01-01

    Roč. 88, OCT (2013), s. 26-31 ISSN 0584-8547 Grant - others:GA ČR(CZ) GAP207/11/0555 Institutional support: RVO:61389005 Keywords : Fluorine * GIC * Laser-induced breakdown spectroscopy * Quantitative analysis Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.150, year: 2013 http://www.sciencedirect.com/science/article/pii/S0584854713002243#

  13. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create

  14. Optimization of an Image-Guided Laser-Induced Choroidal Neovascularization Model in Mice.

    Directory of Open Access Journals (Sweden)

    Yan Gong

    Full Text Available The mouse model of laser-induced choroidal neovascularization (CNV has been used in studies of the exudative form of age-related macular degeneration using both the conventional slit lamp and a new image-guided laser system. A standardized protocol is needed for consistent results using this model, which has been lacking. We optimized details of laser-induced CNV using the image-guided laser photocoagulation system. Four lesions with similar size were consistently applied per eye at approximately double the disc diameter away from the optic nerve, using different laser power levels, and mice of various ages and genders. After 7 days, the mice were sacrificed and retinal pigment epithelium/choroid/sclera was flat-mounted, stained with Isolectin B4, and imaged. Quantification of the area of the laser-induced lesions was performed using an established and constant threshold. Exclusion criteria are described that were necessary for reliable data analysis of the laser-induced CNV lesions. The CNV lesion area was proportional to the laser power levels. Mice at 12-16 weeks of age developed more severe CNV than those at 6-8 weeks of age, and the gender difference was only significant in mice at 12-16 weeks of age, but not in those at 6-8 weeks of age. Dietary intake of omega-3 long-chain polyunsaturated fatty acid reduced laser-induced CNV in mice. Taken together, laser-induced CNV lesions can be easily and consistently applied using the image-guided laser platform. Mice at 6-8 weeks of age are ideal for the laser-induced CNV model.

  15. Surface modifications induced by pulsed-laser texturing—Influence of laser impact on the surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Costil, S., E-mail: sophie.costil@utbm.fr [IRTES-LERMPS, Université de Technologie de Belfort - Montbéliard, site de Sévenans, 90010 Belfort Cedex (France); Lamraoui, A.; Langlade, C. [IRTES-LERMPS, Université de Technologie de Belfort - Montbéliard, site de Sévenans, 90010 Belfort Cedex (France); Heintz, O.; Oltra, R. [ICB, Université de Bourgogne, 21078 Dijon Cedex (France)

    2014-01-01

    Laser cleaning technology provides a safe, environmentally friendly and very cost effective way to improve cleaning and surface preparation of metallic materials. Compared with efficient cleaning processes, it can avoid the disadvantages of ductile materials prepared by conventional technologies (cracks induced by sand-blasting for example) and treat only some selected areas (due to the optical fibers). By this way, laser technology could have several advantages and expand the range of thermal spraying. Moreover, new generations of lasers (fiber laser, disc laser) allow the development of new methods. Besides a significant bulk reduction, no maintenance, low operating cost, laser fibers can introduce alternative treatments. Combining a short-pulse laser with a scanner allows new applications in terms of surface preparation. By multiplying impacts using scanning laser, it is possible to shape the substrate surface to improve the coating adhesion as well as the mechanical behaviour. In addition, during the interactions of the laser beam with metallic surfaces, several modifications can be induced and particularly thermal effects. Indeed, under ambient conditions, a limited oxidation of the clean surface can occur. This phenomenon has been investigated in detail for silicon but few works have been reported concerning metallic materials. This paper aims at studying the surface modifications induced on aluminium alloy substrates after laser texturing. After morphological observations (SEM), a deeper surface analysis will be performed using XPS (X-ray photoelectron spectroscopy) measures and microhardness testing.

  16. Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

    Science.gov (United States)

    Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

    2006-08-01

    A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.

  17. Use of laser cutting techniques for dismantling tasks in nuclear facilities

    International Nuclear Information System (INIS)

    Haferkamp, H.; Drygalla, M.; Goede, M.

    2001-01-01

    A handguided laser processing system developed by laser zentrum Hannover e.V. (LZH) allows impressive cutting, notching, and material removal applications for the dismantling of nuclear power plants. The handguided unit is equipped with a motor drive for consistent processing results and flexible processing for as long as desired. It offers the possibility to adjust the nozzle as well as focal position in order that various materials with different material thicknesses may be processed. The set process parameters may be viewed on a display which also indicates the laser processing programme selected. An integrated exhaust system guarantees a shielded process. The operator is not only protected against process emissions but also against laser beam reflexions. The handguided unit is connected to the laser beam source via an optical fibre and can be used for laser output powers of up to 1500 W with a high beam quality. For handguided laser material processing low emissions at high feed rates as well as cutting kerf widths between 0.5 and 0.3 mm for special applications such as the dismantling of large facilities or units, etc. are decisive, especially when cutting metal sheets for the dismantling of nuclear power plants. (orig.)

  18. Use of laser cutting techniques for dismantling tasks in nuclear facilities

    Energy Technology Data Exchange (ETDEWEB)

    Haferkamp, H.; Drygalla, M.; Goede, M. [Laser Zentrum Hannover e.V. (Germany)

    2001-07-01

    A handguided laser processing system developed by laser zentrum Hannover e.V. (LZH) allows impressive cutting, notching, and material removal applications for the dismantling of nuclear power plants. The handguided unit is equipped with a motor drive for consistent processing results and flexible processing for as long as desired. It offers the possibility to adjust the nozzle as well as focal position in order that various materials with different material thicknesses may be processed. The set process parameters may be viewed on a display which also indicates the laser processing programme selected. An integrated exhaust system guarantees a shielded process. The operator is not only protected against process emissions but also against laser beam reflexions. The handguided unit is connected to the laser beam source via an optical fibre and can be used for laser output powers of up to 1500 W with a high beam quality. For handguided laser material processing low emissions at high feed rates as well as cutting kerf widths between 0.5 and 0.3 mm for special applications such as the dismantling of large facilities or units, etc. are decisive, especially when cutting metal sheets for the dismantling of nuclear power plants. (orig.)

  19. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    Directory of Open Access Journals (Sweden)

    Leif Holmlid

    2015-08-01

    Full Text Available Previous results from laser-induced processes in ultra-dense deuterium D(0 give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0 of ultra-dense hydrogen (size of a few pm escape with a substantial fraction of the energy. Heat loss to the D2 gas (at <1 mbar pressure is measured and compensated for under various conditions. Heat release of a few W is observed, at up to 50% higher energy than the total laser input thus a gain of 1.5. This is uniquely high for the use of deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.

  20. Advanced scheme for high-yield laser driven nuclear reactions

    Czech Academy of Sciences Publication Activity Database

    Margarone, Daniele; Picciotto, A.; Velyhan, Andriy; Krása, Josef; Kucharik, M.; Mangione, A.; Szydlowsky, A.; Malinowska, A.; Bertuccio, G.; Shi, Y.; Crivellari, M.; Ullschmied, Jiří; Bellutti, P.; Korn, Georg

    2015-01-01

    Roč. 57, č. 1 (2015), s. 014030 ISSN 0741-3335 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional research plan: CEZ:AV0Z2043910 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : laser plasma * nuclear reaction * laser fusion Subject RIV: BL - Plasma and Gas Discharge Physics; BH - Optics, Masers, Lasers (UFP-V) Impact factor: 2.404, year: 2015

  1. Inhomogeneous nuclear spin polarization induced by helicity-modulated optical excitation of fluorine-bound electron spins in ZnSe

    Science.gov (United States)

    Heisterkamp, F.; Greilich, A.; Zhukov, E. A.; Kirstein, E.; Kazimierczuk, T.; Korenev, V. L.; Yugova, I. A.; Yakovlev, D. R.; Pawlis, A.; Bayer, M.

    2015-12-01

    Optically induced nuclear spin polarization in a fluorine-doped ZnSe epilayer is studied by time-resolved Kerr rotation using resonant excitation of donor-bound excitons. Excitation with helicity-modulated laser pulses results in a transverse nuclear spin polarization, which is detected as a change of the Larmor precession frequency of the donor-bound electron spins. The frequency shift in dependence on the transverse magnetic field exhibits a pronounced dispersion-like shape with resonances at the fields of nuclear magnetic resonance of the constituent zinc and selenium isotopes. It is studied as a function of external parameters, particularly of constant and radio frequency external magnetic fields. The width of the resonance and its shape indicate a strong spatial inhomogeneity of the nuclear spin polarization in the vicinity of a fluorine donor. A mechanism of optically induced nuclear spin polarization is suggested based on the concept of resonant nuclear spin cooling driven by the inhomogeneous Knight field of the donor-bound electron.

  2. Nuclear microprobe characterization of surface hardening by precipitation of chromium carbides after laser beam treatment of a Ni-Cr substrate

    International Nuclear Information System (INIS)

    Mosbah, M.; Gosset, J.; Trocellier, P.; Puig, T.; Cantarel, M.; Condat, M.

    1989-01-01

    Surface treatment by laser provides interesting solutions to the problem of accelerated wear of materials. The aim of the present study is the characterization of chromium carbides rich surface alloys after laser beam melting of a Ni 70 Cr 30 carbon precoated substrate. The carbon profiling of the lasered surface was performed by nuclear microprobe using the 12 C(d,p 0 ) 13 C reaction, Ni and Cr were evaluated by means of PIXE (Particle Induced X Ray Emission). The specificity of the method and the experimental conditions are explained. Wear results are very satisfactory and close to those obtained by injection of chromium carbide powders into the laser beam in the case of a Nimonic alloy: wear rates are divided by two orders of magnitude

  3. Robust optimization of the laser induced damage threshold of dielectric mirrors for high power lasers.

    Science.gov (United States)

    Chorel, Marine; Lanternier, Thomas; Lavastre, Éric; Bonod, Nicolas; Bousquet, Bruno; Néauport, Jérôme

    2018-04-30

    We report on a numerical optimization of the laser induced damage threshold of multi-dielectric high reflection mirrors in the sub-picosecond regime. We highlight the interplay between the electric field distribution, refractive index and intrinsic laser induced damage threshold of the materials on the overall laser induced damage threshold (LIDT) of the multilayer. We describe an optimization method of the multilayer that minimizes the field enhancement in high refractive index materials while preserving a near perfect reflectivity. This method yields a significant improvement of the damage resistance since a maximum increase of 40% can be achieved on the overall LIDT of the multilayer.

  4. Ultrafast molecular imaging by laser-induced electron diffraction

    International Nuclear Information System (INIS)

    Peters, M.; Nguyen-Dang, T. T.; Cornaggia, C.; Saugout, S.; Charron, E.; Keller, A.; Atabek, O.

    2011-01-01

    We address the feasibility of imaging geometric and orbital structures of a polyatomic molecule on an attosecond time scale using the laser-induced electron diffraction (LIED) technique. We present numerical results for the highest molecular orbitals of the CO 2 molecule excited by a near-infrared few-cycle laser pulse. The molecular geometry (bond lengths) is determined within 3% of accuracy from a diffraction pattern which also reflects the nodal properties of the initial molecular orbital. Robustness of the structure determination is discussed with respect to vibrational and rotational motions with a complete interpretation of the laser-induced mechanisms.

  5. Laser-induced shockwave propagation from ablation in a cavity

    International Nuclear Information System (INIS)

    Zeng Xianzhong; Mao Xianglei; Mao, Samuel S.; Wen, S.-B.; Greif, Ralph; Russo, Richard E.

    2006-01-01

    The propagation of laser-induced shockwaves from ablation inside of cavities was determined from time-resolved shadowgraph images. The temperature and electron number density of the laser-induced plasma was determined from spectroscopic measurements. These properties were compared to those for laser ablation on the flat surface under the same energy and background gas condition. A theoretical model was proposed to determine the amount of energy and vaporized mass stored in the vapor plume based on these measurements

  6. Ultrasound imaging of Nd:YAG laser-induced tissue coagulation in porcine livers.

    Science.gov (United States)

    Ritzel, U; Wietzke-Braun, P; Brinck, U; Leonhardt, U; Ramadori, G

    2001-12-01

    Absorption of laser light energy induces denaturation of proteins and thermocoagulation of irradiated tissue. Recently, MRI-guided laser coagulation in combination with MR thermometry was reported as a treatment of liver tumours. In the present study ultrasonographic imaging was evaluated for its suitability in laser induced tissue thermocoagulation. Fresh porcine livers were used for ex vivo examinations. Placement of the laser catheter and tissue coagulation during laser light emission were online monitored by ultrasonography. Nd:YAG laser-induced tissue damage was evaluated by macroscopical and microscopical examinations of histological sections. During laser light emission a marked hyperdense signal enhancement was observed by ultrasonography which strongly correlated with the extent of macroscopic tissue damage. The size of laser-induced coagulation zone depended on both the power setting and total energy delivered. Carbonization of the tissue surrounding the laser tip is a limiting factor because of laser light absorption. However our data indicate that using appropriate laser energy and exposure time prevent carbonization although carbonization can not be visualized by ultrasonography. It is concluded from the present ex vivo studies that laser coagulation can be effectively performed under ultrasonographic guidance.

  7. Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule

    International Nuclear Information System (INIS)

    Bien-Aime, K.

    2009-11-01

    Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm 2 , a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

  8. Electromagnetically induced transparency with broadband laser pulses

    International Nuclear Information System (INIS)

    Yavuz, D. D.

    2007-01-01

    We suggest a scheme to slow and stop broadband laser pulses inside an atomic medium using electromagnetically induced transparency. Extending the suggestion of Harris et al. [Phys. Rev. Lett. 70, 552 (1993)], the key idea is to use matched Fourier components for the probe and coupling laser beams

  9. Time differentiated nuclear resonance spectroscopy coupled with pulsed laser heating in diamond anvil cells

    Energy Technology Data Exchange (ETDEWEB)

    Kupenko, I., E-mail: kupenko@esrf.fr; Strohm, C. [Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth (Germany); ESRF-The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9 (France); McCammon, C.; Cerantola, V.; Petitgirard, S.; Dubrovinsky, L. [Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth (Germany); Glazyrin, K. [Photon Science, DESY, D-22607 Hamburg (Germany); Vasiukov, D.; Aprilis, G. [Laboratory of Crystallography, Material Physics and Technology at Extreme Conditions, Universität Bayreuth, D-95440 Bayreuth (Germany); Chumakov, A. I.; Rüffer, R. [ESRF-The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9 (France)

    2015-11-15

    Developments in pulsed laser heating applied to nuclear resonance techniques are presented together with their applications to studies of geophysically relevant materials. Continuous laser heating in diamond anvil cells is a widely used method to generate extreme temperatures at static high pressure conditions in order to study the structure and properties of materials found in deep planetary interiors. The pulsed laser heating technique has advantages over continuous heating, including prevention of the spreading of heated sample and/or the pressure medium and, thus, a better stability of the heating process. Time differentiated data acquisition coupled with pulsed laser heating in diamond anvil cells was successfully tested at the Nuclear Resonance beamline (ID18) of the European Synchrotron Radiation Facility. We show examples applying the method to investigation of an assemblage containing ε-Fe, FeO, and Fe{sub 3}C using synchrotron Mössbauer source spectroscopy, FeCO{sub 3} using nuclear inelastic scattering, and Fe{sub 2}O{sub 3} using nuclear forward scattering. These examples demonstrate the applicability of pulsed laser heating in diamond anvil cells to spectroscopic techniques with long data acquisition times, because it enables stable pulsed heating with data collection at specific time intervals that are synchronized with laser pulses.

  10. Nuclear Material Detection by One-Short-Pulse-Laser-Driven Neutron Source

    International Nuclear Information System (INIS)

    Favalli, Andrea; Aymond, F.; Bridgewater, Jon S.; Croft, Stephen; Deppert, O.; Devlin, Matthew James; Falk, Katerina; Fernandez, Juan Carlos; Gautier, Donald Cort; Gonzales, Manuel A.; Goodsell, Alison Victoria; Guler, Nevzat; Hamilton, Christopher Eric; Hegelich, Bjorn Manuel; Henzlova, Daniela; Ianakiev, Kiril Dimitrov; Iliev, Metodi; Johnson, Randall Philip; Jung, Daniel; Kleinschmidt, Annika; Koehler, Katrina Elizabeth; Pomerantz, Ishay; Roth, Markus; Santi, Peter Angelo; Shimada, Tsutomu; Swinhoe, Martyn Thomas; Taddeucci, Terry Nicholas; Wurden, Glen Anthony; Palaniyappan, Sasikumar; McCary, E.

    2015-01-01

    Covered in the PowerPoint presentation are the following areas: Motivation and requirements for active interrogation of nuclear material; laser-driven neutron source; neutron diagnostics; active interrogation of nuclear material; and, conclusions, remarks, and future works.

  11. Laser induced fusion - theoretical aspects

    International Nuclear Information System (INIS)

    Lawande, S.V.; Gunye, M.R.

    1979-01-01

    The theoretical aspects of thermonuclear fusion induced by laser are discussed. After outlining the basic features and the energetics of laser fusion in the chapter 1, various non-linear mechanisms responsible for an enhanced absorption of laser energy into the plasma and the stimulated scattering processes which hinder the absorption are discussed in the second chapter on laser plasma interactions. The third chapter on gas dynamics and the shock phenomena presents the mathematical formulation of the compression to high densities of the core of the pellet for its implosion. A hydrodynamic model developed to stimulate the evolution of laser heated symmetric plasma is outlined in the chapter four on numerichigly relativistic noninteracting particles, regular bouncing states may occur at high densities, or at high temperatures. The latter case is considered in details for the collapse phase of a hot universe; lepton pair creation may completely decelerate the collapse of a hot hadronic plasma, provided the observational parameters, the Hubble constant Hsub(deg), the matter parameter Ωsub(deg) and the deceleration parameter qsub(deg) satisfy certain constraint conditions

  12. Sputtering of amorphous carbon layers studied by laser induced fluorescence

    International Nuclear Information System (INIS)

    Pasch, E.

    1992-07-01

    In order to minimize the radiation losses, it is desirable to keep the plasmas in nuclear fusion devices free of high-Z-impurities. Therefore, the walls of TEXTOR and other tokamaks are covered with thin layers of amorphous carbon layers (a-C:H) or amorphous carbon/boron layers (a-C/B:H). The sputtering behaviour of these layers has been studied under bombardment by Ar + ions with energies of 1.5 keV and current densities of a few mA/cm 2 . Investigations of these coatings were carried out with the object to measure the velocity distribution of the sputtered atoms and the sputtered yields by laser induced fluorescence in the vacuum ultraviolet. (orig.)

  13. The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

    International Nuclear Information System (INIS)

    Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

    2011-01-01

    Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

  14. The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

    Science.gov (United States)

    Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

    2011-02-01

    Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

  15. Study of a plasma created by an accelerated proton beam for the characterization of a nuclear pumped laser medium

    International Nuclear Information System (INIS)

    Vialle, M.

    1985-04-01

    Processes leading to laser effect in nuclear induced plasmas can be studied with simulation experiments using charged particles beams. Such an experiment has been performed with a proton beam (2 MeV, 2 μA/cm 2 ) produced by a Van de Graaff accelerator. This beam is an excitation and ionisation source quite comparable to the laser medium source of a reactor experiment. The plasma created in a Ne target (about 100 torrs) containing N 2 impurities has been studied: - experimentally using R.F. diagnostics and spectroscopy; - theoretically by calculating the electronic distribution function in the low and medium energy region [fr

  16. Visualization of cavitation bubbles induced by a laser pulse

    International Nuclear Information System (INIS)

    Testud-Giovanneschi, P.; Dufresne, D.; Inglesakis, G.

    1987-01-01

    The I.M.F.M. researchers working on Laser-Matter Interaction are studying the effects induced on matter by a pulsed radiation energy deposit. In this research, the emphasis is on the laser liquids interaction field and more particularly the cavitation induced by a laser pulse or ''optical-cavitation'' as termed by W. Lauterborn (1). For bubbles investigations, the visualizations form a basic diagnostic. This paper presents the experimental apparatus of formation of bubbles, the visualization apparatus and different typical examples of photographic recordings

  17. High power CO2 lasers and their applications in nuclear industry

    International Nuclear Information System (INIS)

    Nath, A.K.

    2002-01-01

    Carbon dioxide laser is one of the most popular lasers in industry for material processing applications. It has very high power capability and high efficiency, can be operated in continuous wave (CW), modulated and pulsed modes, and has relatively low cost. Due to these characteristics high power CO 2 lasers are being used worldwide in different industries for a wide variety of materials processing operations. In nuclear industry, CO 2 laser has made its way in many applications. Some of the tasks performed by multikilowatt CO 2 laser are cutting operations necessary to remove unprocessible hardware from reactor fuel assemblies, sealing/fixing/removing radioactive contaminations onto/from concrete surfaces and surface modification of engineering components for improved surface mechanical and metallurgical characteristics. We have developed various models of CW CO 2 lasers of power up to 12 kW and a high repetitive rate TEA (Transversely Excited Atmospheric pressure) CO 2 laser of 500 W average power operating at 500 Hz repetition rates. We have carried many materials processing applications of direct relevance to DAE. Recent work includes laser welding of end plug PFBR fuel tubes, martensitic stainless steel and titanium alloy, surface cladding of turbine blades made of Ni-super alloy with stellite 694, fabrication on graded material of stainless steel and stellite, and laser scabbling, drilling and cutting of concrete which have potential application in decontamination and decommissioning of nuclear facilities. A brief overview of these indigenous developments will be presented. (author)

  18. Self-Induced Faraday Instability Laser

    Science.gov (United States)

    Perego, A. M.; Smirnov, S. V.; Staliunas, K.; Churkin, D. V.; Wabnitz, S.

    2018-05-01

    We predict the onset of self-induced parametric or Faraday instabilities in a laser, spontaneously caused by the presence of pump depletion, which leads to a periodic gain landscape for light propagating in the cavity. As a result of the instability, continuous wave oscillation becomes unstable even in the normal dispersion regime of the cavity, and a periodic train of pulses with ultrahigh repetition rate is generated. Application to the case of Raman fiber lasers is described, in good quantitative agreement between our conceptual analysis and numerical modeling.

  19. Chromatin influence on the function and formation of the nuclear envelope shown by laser-induced psoralen photoreaction

    International Nuclear Information System (INIS)

    Peterson, S.P.; Berns, M.W.

    1978-01-01

    Potorous tridactylis (PTK 2 ) cells growing in culture were treated with psoralen derivatives and dividing cells were located by phase-contrast microscopy. Psoralens, light-sensitive DNA-photoadducting drugs, were reacted with mitotic chromosomes through exposure to 365-nm light from an argon laser micro-beam system. It was shown that following mitosis and photoreaction, cells without nuclear envelopes were produced when psoralen-treated cells received 60 light pulses over their entire chromosome complement. These 'non-nuclear membrane' cells were found to incorporate [ 3 H]uridine, and to a lesser extent, [ 3 H]thymidine by autoradiography. Reduction of the light exposure by half (30 near-u.v. pulses) over the entire chromosome complement in the presence of psoralen also produced non-nuclear-membrane cells as seen by light microscopy. Further examination of these cells (30 light pulses) by single-cell electron microscopy revealed that unlike the high light exposure (60 near-u.v. pulses), the low light dosage resulted in cells with membrane patches associated with their chromatin. Since neither actinomycin D nor cycloheximide impeded nuclear envelope reformation, the psoralen-DNA reaction is concluded to produce non-nuclear membrane by a mechanism other than transcription or translation inhibition. The association of Golgi with areas of nuclear membrane patches gives indirect evidence of a possible Golgi contribution to the reformation of the nuclear envelope after mitosis. It is concluded that DNA plays a role in envelope reformation. (author)

  20. Para-hydrogen raman laser and its application to laser induced chemistry

    International Nuclear Information System (INIS)

    Tashiro, Hideo

    1988-01-01

    The report outlines the mechanism of the para-hydrogen Raman laser as a infrared light source, and its application to laser induced chemistry. The Stoke's wave number after a Raman shift is equal to the difference between the wave number of the CO 2 laser used for excitation and the rotation Raman wave number of the hydrogen molecule. A Raman laser can serve as an infrared source. CO 2 laser oscillation beam in the range of 9∼11 micrometers is selected and the frequency of infrared beam is varied by changing the wave number of the CO 2 laser beam. A problem with the Raman laser is that the Raman scatterring gain is small due to a large wavelength. In developing equipment, a special mechanism is required to solve this problem. A Raman laser comprises a CO 2 laser for excitation and multi-pulse Raman cells. The combination of a TEA oscillator and amplifiers gives CO 2 pulses with a peak power of about several tens of MW. Many heavy metal compounds including fluorides, carbonyl compounds and other organic compounds, absorb light with wavelengths in the same range as those of the Raman laser. Such compounds can be dissociated directly by applying Raman laser beams. The laser will be helpful for separation of isotopes, etc. (Nogami, K.)

  1. Contributions to process monitoring by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rusak, David Alexander

    1998-12-01

    When a pulsed laser of sufficient energy and pulse duration is brought to a focus, multi-photon ionization creates free electrons in the focal volume. These electrons are accelerated in a process known as inverse Bremsstrahlung and cause collisional ionization of species in the focal volume. More charge carriers are produced and the process continues for the duration of the laser pulse. The manifestation of this process is a visible spark or plasma which typically lasts for tens of microseconds. This laser-induced plasma can serve as a source in an atomic emission experiment. Because the composition of the plasma is determined in large part by the environment in which it forms, elements in the laser target can be determined spectroscopically. The goal of a laser-induced breakdown spectroscopy (LIBS) experiment is to establish a relationship between the concentration of an element of interest in the target and the intensity of light emitted from the laser-induced plasma at a wavelength characteristic of that element. Because LIBS requires only optical access to the sample and can perform elemental determinations in solids, liquids, or gases with little sample preparation, there is interest in using it as an on-line technique for process monitoring in a number of industrial applications. However, before the technique becomes useful in industrial applications, many issues regarding instrumentation and data analysis need to be addressed in the lab. The first two chapters of this dissertation provide, respectively, the basics of the atomic emission experiment and a background of laser-induced breakdown spectroscopy. The next two chapters examine the effect of target water content on the laser-induced plasma and the use of LIBS for analysis of aqueous samples. Chapter 5 describes construction of a fiber optic LIBS probe and its use to study temporal electron number density evolution in plasmas formed on different metals. Chapter 6 is a study of excitation, vibrational

  2. Remote metal analysis by laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Duckworth, A.

    1996-01-01

    This paper describes a new technique by which the composition of irradiated or inaccessible reactor components can be determined remotely. The technique uses very short duration, high energy laser pulses at a wavelength which can be transmitted down an optical fibre to ablate a tiny plasma from the surface of a metal component. Light from the plasma is collected by a second fibre and returned to a spectrometer where it is split into the characteristic emission wavelengths of the elements in the sample. Comparison of the emission line amplitude for a particular element with that of a chosen calibration line can be used to deduce the concentration of the element in the sample. The technique has been used successfully to differentiate between different highly radioactive control rod batches at Sizewell ''A'' and Hinkley Point ''A'' Power Stations. The material analysis accuracy is comparable with that obtained from electron microphobe analysis and other direct spectroscopic methods. However, by analysing the mild steel control rod casing material remotely, difficult sample removal becomes unneccessary and the integrity of the component remains essentially unaltered. In addition, removal of deposits or surface corrosion is incorporated very neatly into the process. These factors make remote laser induced breakdown spectroscopy an ideal tool for material analysis in the nuclear environment. (UK)

  3. Remote metal analysis by laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Duckworth, A.

    1996-01-01

    This paper describes a new technique by which the composition of irradiated or inaccessible reactor components can be determined remotely. The technique uses very short duration, high energy laser pulses at a wavelength which can be transmitted down an optical fibre to ablate a tiny plasma from the surface of a metal component. Light from the plasma is collected by a second fibre and returned to a spectrometer where it is split into the characteristic emission wavelengths of the elements in the sample. Comparison of the emission line amplitude for a particular element with that of a chosen calibrationline can be used to deduce the concentration of the element in the sample. The technique has been used successfully to differentiate between highly radioactive control rod batches at Sizewell 'A' and Hinkley Point 'A Power Stations. The material analysis accuracy is comparable with that obtained from electron microprobe analysis and other direct spectroscopic methods. However, by analysing the mild steel control rod casing material remotely, difficult sample removal becomes unnecessary and the integrity of the component remains essentially unaltered. In addition, removal of deposits or surface corrosion is incorporated very neatly into the process. These factors make remote laser induced breakdown spectroscopy an ideal tool for material analysis in the nuclear environment. (Author)

  4. Ultrasensitive detection of target analyte-induced aggregation of gold nanoparticles using laser-induced nanoparticle Rayleigh scattering.

    Science.gov (United States)

    Lin, Jia-Hui; Tseng, Wei-Lung

    2015-01-01

    Detection of salt- and analyte-induced aggregation of gold nanoparticles (AuNPs) mostly relies on costly and bulky analytical instruments. To response this drawback, a portable, miniaturized, sensitive, and cost-effective detection technique is urgently required for rapid field detection and monitoring of target analyte via the use of AuNP-based sensor. This study combined a miniaturized spectrometer with a 532-nm laser to develop a laser-induced Rayleigh scattering technique, allowing the sensitive and selective detection of Rayleigh scattering from the aggregated AuNPs. Three AuNP-based sensing systems, including salt-, thiol- and metal ion-induced aggregation of the AuNPs, were performed to examine the sensitivity of laser-induced Rayleigh scattering technique. Salt-, thiol-, and metal ion-promoted NP aggregation were exemplified by the use of aptamer-adsorbed, fluorosurfactant-stabilized, and gallic acid-capped AuNPs for probing K(+), S-adenosylhomocysteine hydrolase-induced hydrolysis of S-adenosylhomocysteine, and Pb(2+), in sequence. Compared to the reported methods for monitoring the aggregated AuNPs, the proposed system provided distinct advantages of sensitivity. Laser-induced Rayleigh scattering technique was improved to be convenient, cheap, and portable by replacing a diode laser and a miniaturized spectrometer with a laser pointer and a smart-phone. Using this smart-phone-based detection platform, we can determine whether or not the Pb(2+) concentration exceed the maximum allowable level of Pb(2+) in drinking water. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Deuterium–deuterium nuclear reaction induced by high intensity laser pulses

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Cavallaro, S.; Cutroneo, M.; Giuffrida, L.; Krása, Josef; Margarone, Daniele; Velyhan, Andriy; Kravarik, J.; Ullschmied, Jiří; Wolowski, J.; Szydlowski, A.; Rosinski, M.

    2013-01-01

    Roč. 272, May (2013), s. 42-45 ISSN 0169-4332 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279; GA MŠk EE.2.3.20.0087; GA MŠk(CZ) LC528 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OPVK 3 Laser Zdroj(XE) CZ.1.07/2.3.00/20.0279; OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087; 7FP LASERLAB-EUROPE(XE) 228334 Program:EE; FP7 Keywords : D–D fusion * cross-section * laser-plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.538, year: 2013

  6. Characterization Of High Explosives Detonations Via Laser-Induced Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Aleman, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    One objective of the Department of Energy’s National Security Administration is to develop technologies that can help the United States government to detect foreign nuclear weapons development activities. The realm of high explosive (HE) experiments is one of the key areas to assess the nuclear ambitions of a country. SRNL has participated in the collection of particulates from HE experiments and characterized the material with the purpose to correlate particulate matter with HE. Since these field campaigns are expensive, on-demand simulated laboratory-scale explosion experiments are needed to further our knowledge of the chemistry and particle formation in the process. Our goal is to develop an experimental test bed in the laboratory to test measurement concepts and correlate particle formation processes with the observables from the detonation fireball. The final objective is to use this knowledge to tailor our experimental setups in future field campaigns. The test bed uses pulsed laser-induced plasmas to simulate micro-explosions, with the intent to study the temporal behavior of the fireball observed in field tests. During FY15, a plan was prepared and executed which assembled two laser ablation systems, procured materials for study, and tested a Step-Scan Fourier Transform Infrared Spectrometer (SS-FTIR). Designs for a shadowgraph system for shock wave analysis, design for a micro-particulate collector from ablated pulse were accomplished. A novel spectroscopic system was conceived and a prototype system built for acquisition of spectral/temporal characterization of a high speed event such as from a high explosive detonation. Experiments and analyses will continue into FY16.

  7. IR Laser-Induced Thermolysis and UV Laser-Induced Photolysis of 1,3-Diethyldisiloxane: Chemical Vapour Deposition of Nanotextured Hydridoalkylsilicones

    Czech Academy of Sciences Publication Activity Database

    Urbanová, Markéta; Bastl, Zdeněk; Šubrt, Jan; Pola, Josef

    2001-01-01

    Roč. 11, č. 6 (2001), s. 1557-1562 ISSN 0959-9428 R&D Projects: GA AV ČR IAA4072806 Keywords : thermolysis * UV laser photolysis * composition Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.736, year: 2001

  8. Spectroscopy of beryllium-like nitrogen ions by laser-induced recombination

    International Nuclear Information System (INIS)

    Uhlenberg, G.

    1996-04-01

    The following topics were dealt with: Rydberg spectroscopy of beryllium-like nitrogen (N 3+ ) by laser-induced recombination, transition enrgies, Rydberg level shift, configuration interaction, laser intensity effect, laser band width

  9. Precision linac and laser technologies for nuclear photonics gamma-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F.; Hartemann, F. V.; Anderson, S. G.; Cross, R. R.; Gibson, D. J.; Hall, J.; Marsh, R. A.; Messerly, M.; Wu, S. S.; Siders, C. W.; Barty, C. P. J. [Lawrence Livermore National Laboratory, NIF and Photon Science, 7000 East Avenue, Livermore, California 94550 (United States)

    2012-05-15

    Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scattered and Doppler upshifted by a high brightness electron beam to generate tunable and highly collimated gamma-ray pulses. The electron and laser beam parameters can be optimized to achieve the spectral brightness and narrow bandwidth required by nuclear photonics applications. A description of the design of the next generation precision gamma-ray source currently under construction at Lawrence Livermore National Laboratory is presented, along with the underlying motivations. Within this context, high-gradient X-band technology, used in conjunction with fiber-based photocathode drive laser and diode pumped solid-state interaction laser technologies, will be shown to offer optimal performance for high gamma-ray spectral flux, narrow bandwidth applications.

  10. Beam diagnostics for Laser-induced proton generation at KAERI

    International Nuclear Information System (INIS)

    Kim, Dong Heun; Park, Seong Hee; Jeong, Young Uk; Lee, Ki Tae; Chan, Young Ho; Lee, Byung Cheol; Yoo, Byeong Duk

    2005-01-01

    With an advent of femto-second lasers, a laseraccelerated ion generation has been world-widely studied for medical and nuclear applications. It is known that protons with the energy from several tens MeV to a few hundreds MeV require for a cancer therapy and nuclear reaction. Even though, up to present, the maximum energy of laser-accelerated proton is about 60 MeV, it is expected that the energy of protons generated can be obtained at least up to 150 MeV. According to theoretical and experimental works, it turns out the energy distribution and the flux of ions strongly depends on the intensity of a fs laser at a target. However, physics on laser-plasma interaction is still not clear. The precise measurements of parameters of a fs laser and ions are important to figure out the physics and develop the theoretical interpretation. Typically, beam diagnostic system includes measurements and/or monitoring of the temporal and spatial profiles of lasers at the target as well as the energy spectrum and density profile of protons, which are critical for the analysis of mechanism and the characterization of protons generated. We fabricated and installed the target chamber for laser-accelerated proton generation and are now integrating beam diagnostic system. For laser diagnostics, beam monitoring and alignment system has been installed. For a charged particle, CR-39 detectors, Thomson parabola spectrometer, and Si charged particle detectors are installed for density profile and energy spectrum. In this paper, we discuss the laser beam monitoring and alignment system. We also estimates expected spectrum of protons from Thomson parabola spectrometer, depending on the parameters of protons

  11. Laser-induced diffusion decomposition in Fe–V thin-film alloys

    Energy Technology Data Exchange (ETDEWEB)

    Polushkin, N.I., E-mail: nipolushkin@fc.ul.pt [Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Duarte, A.C.; Conde, O. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Alves, E. [Associação Euratom/IST e Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Barradas, N.P. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS (Portugal); García-García, A.; Kakazei, G.N.; Ventura, J.O.; Araujo, J.P. [Departamento de Física, Universidade do Porto e IFIMUP, 4169-007 Porto (Portugal); Oliveira, V. [Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Instituto Superior de Engenharia de Lisboa, 1959-007 Lisboa (Portugal); Vilar, R. [Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal)

    2015-05-01

    Highlights: • Irradiation of an Fe–V alloy by femtosecond laser triggers diffusion decomposition. • The decomposition occurs with strongly enhanced (∼4 orders) atomic diffusivity. • This anomaly is associated with the metallic glassy state achievable under laser quenching. • The ultrafast diffusion decomposition is responsible for laser-induced ferromagnetism. - Abstract: We investigate the origin of ferromagnetism induced in thin-film (∼20 nm) Fe–V alloys by their irradiation with subpicosecond laser pulses. We find with Rutherford backscattering that the magnetic modifications follow a thermally stimulated process of diffusion decomposition, with formation of a-few-nm-thick Fe enriched layer inside the film. Surprisingly, similar transformations in the samples were also found after their long-time (∼10{sup 3} s) thermal annealing. However, the laser action provides much higher diffusion coefficients (∼4 orders of magnitude) than those obtained under standard heat treatments. We get a hint that this ultrafast diffusion decomposition occurs in the metallic glassy state achievable in laser-quenched samples. This vitrification is thought to be a prerequisite for the laser-induced onset of ferromagnetism that we observe.

  12. Laser application for nuclear reaction product detecting system alignment

    International Nuclear Information System (INIS)

    Grantsev, V.I.; Dryapachenko, I.P.; Kornilov, V.A.; Nemets, O.F.; Rudenko, B.A.; Sokolov, M.V.; Struzhko, B.G.; Gnatovskij, A.V.; Bojchuk, V.N.

    1982-01-01

    A method for optical alignment of nuclear particle detector system using a laser beam and hologram is described. The method permits to arrange detectors very precisely in accordance with any chosen space coordinate values. The results of modelling the geometry of an experiment based on using the suggested method on cyclotron beams are described. A gas helium-neon laser with wavelength of 0.63 μm radiation power of an order of 2 MW and angular beam divergence less than 10 angular minutes is used for modelling. It is concluded that the laser and hologram application provides large possibilities for the modelling the geometry of experiments on nuclear reaction investigation. When necessary it is possible to obtain small nonius scale of reference beams by means of multiplicating properties of the wave front modulator-hologram system. It is also possible to record holograms shaping the reference beams in two or several planes crossing along the central beam direction. Such holograms can be used for modelling the noncoplanar geometry of correlation experiments [ru

  13. UV laser-induced cross-linking in peptides

    Science.gov (United States)

    Leo, Gabriella; Altucci, Carlo; Bourgoin-Voillard, Sandrine; Gravagnuolo, Alfredo M.; Esposito, Rosario; Marino, Gennaro; Costello, Catherine E.; Velotta, Raffaele; Birolo, Leila

    2013-01-01

    RATIONALE The aim of this study was to demonstrate, and to characterize by high resolution mass spectrometry, that it is possible to preferentially induce covalent cross-links in peptides by using high energy femtosecond UV laser pulses. The cross-link is readily formed only when aromatic amino acids are present in the peptide sequence. METHODS Three peptides, xenopsin, angiotensin I, interleukin, individually or in combination, were exposed to high energy femtosecond UV laser pulses, either alone or in the presence of spin trapping molecules, the reaction products being characterized by high resolution mass spectrometry. RESULTS High resolution mass spectrometry and spin trapping strategies showed that cross-linking occurs readily, proceeds via a radical mechanism, and is the highly dominant reaction, proceeding without causing significant photo-damage in the investigated range of experimental parameters. CONCLUSIONS High energy femtosecond UV laser pulses can be used to induce covalent cross-links between aromatic amino acids in peptides, overcoming photo-oxidation processes, that predominate as the mean laser pulse intensity approaches illumination conditions achievable with conventional UV light sources. PMID:23754800

  14. Laser-induced damage study of polymer PMMA

    International Nuclear Information System (INIS)

    Mansour, N.

    2001-01-01

    This article presents the results of bulk laser-induced damage measurements in polymer PMMA at 532 nm and 1064 nm for nanosecond laser pulses. The damage thresholds were measured for focused spot sizes ranging over two orders of magnitude. In this work, self-focusing effects were verified to be absent by measurements of breakdown thresholds using both linearly and circularly polarized light. At both 1064 nm and 532 nm, the dependence of the breakdown field, E B , on the spot size, ω, was empirically determined to be E B = C/√ω, where C depends on the wavelength. The extracted value for C(λ) at 1064 nm is larger by a factor of 5 than at 532 nm. Possible reasons for this strong dispersion and mechanism for laser-induced damage in polymer materials will be discussed

  15. Laser induced white lighting of tungsten filament

    Science.gov (United States)

    Strek, W.; Tomala, R.; Lukaszewicz, M.

    2018-04-01

    The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

  16. Laser Induced Selective Activation For Subsequent Autocatalytic Electroless Plating

    DEFF Research Database (Denmark)

    Zhang, Yang

    . The third hypothesis is that the activation and rinsing process can be described by diffusion. This hypothesis is proved using Fick’s diffusion laws combined with the short-time-plating experiment. The influence of laser parameters on the surface structure is investigated for Nd:YAG, UV, and fiber lasers......The subject of this PhD thesis is “Laser induced selective activation for subsequent autocatalytic electroless plating.” The objective of the project is to investigate the process chains for micro structuring of polymer surfaces for selective micro metallization. Laser induced selective activation...... (LISA) is introduced and studied as a new technique for producing 3D moulded interconnect devices (3D-MIDs). This technique enables the metallization of polymer surface modified by laser and subsequently activated by a PdCl2/SnCl2 system. Various technologies exist on an industrial level...

  17. Infrared laser induced organic reactions. 2. Laser vs. thermal inducment of unimolecular and hydrogen bromide catalyzed bimolecular dehydration of alcohols

    International Nuclear Information System (INIS)

    Danen, W.C.

    1979-01-01

    It has been demonstrated that a mixture of reactant molecules can be induced by pulsed infrared laser radiation to react via a route which is totally different from the pathway resulting from heating the mixture at 300 0 C. The high-energy unimolecular elimination of H 2 O from ethanol in the presence of 2-propanol and HBr can be selectively induced with a pulsed CO 2 laser in preference to either a lower energy bimolecular HBr-catalyzed dehydration or the more facile dehydration of 2-propanol. Heating the mixture resulted in the almost exclusive reaction of 2-propanol to produce propylene. It was demonstrated that the bimolecular ethanol + HBr reaction cannot be effectively induced by the infrared laser radiation as evidenced by the detrimental effect on the yield of ethylene as the HBr pressure was increased. The selective, nonthermal inducement of H 2 O elimination from vibrationally excited ethanol in the presence of 2-propanol required relatively low reactant pressures. At higher pressures intermolecular V--V energy transfer allowed the thermally more facile dehydration from 2-propanol to become the predominant reaction channel

  18. Krypton laser photocoagulation induces retinal vascular remodeling rather than choroidal neovascularization.

    Science.gov (United States)

    Behar-Cohen, F; Benezra, D; Soubrane, G; Jonet, L; Jeanny, J C

    2006-08-01

    The purpose of this study is to analyze the retina and choroid response following krypton laser photocoagulation. Ninety-two C57BL6/Sev129 and 32 C57BL/6J, 5-6-week-old mice received one single krypton (630 nm) laser lesion: 50 microm, 0.05 s, 400 mW. On the following day, every day thereafter for 1 week and every 2-3 days for the following 3 weeks, serial sections throughout the lesion were systematically collected and studied. Immunohistology using specific markers or antibodies for glial fibrillary acidic protein (GFAP) (astrocytes, glia and Muller's cells), von Willebrand (vW) (vascular endothelial cells), TUNEL (cells undergoing caspase dependent apoptosis), PCNA (proliferating cell nuclear antigen) p36, CD4 and F4/80 (infiltrating inflammatory and T cells), DAPI (cell nuclei) and routine histology were carried out. Laser confocal microscopy was also performed on flat mounts. Temporal and spatial observations of the created photocoagulation lesions demonstrate that, after a few hours, activated glial cells within the retinal path of the laser beam express GFAP. After 48 h, GFAP-positive staining was also detected within the choroid lesion center. "Movement" of this GFAP-positive expression towards the lasered choroid was preceded by a well-demarcated and localized apoptosis of the retina outer nuclear layer cells within the laser beam path. Later, death of retinal outer nuclear cells and layer thinning at this site was followed by evagination of the inner nuclear retinal layer. Funneling of the entire inner nuclear and the thinned outer nuclear layers into the choroid lesion center was accompanied by "dragging" of the retinal capillaries. Thus, from days 10 to 14 after krypton laser photocoagulation onward, well-formed blood capillaries (of retinal origin) were observed within the lesion. Only a few of the vW-positive capillary endothelial cells stained also for PCNA p36. In the choroid, dilatation of the vascular bed occurred at the vicinity of the

  19. Effect of the R dependence of laser-induced polarizability on molecular dynamic alignment in an intense femtosecond laser field

    International Nuclear Information System (INIS)

    Chen Jianxin; Cui Xiaomei; Huang Bomin; Wu Hongchun; Zhuo Shuangmu

    2006-01-01

    In the rotation equation of the angle θ between the molecular axis and the laser polarization direction, the dependence of laser-induced polarizability on the molecular internuclear distance R is considered. The effect of the R dependence of laser-induced polarizability on molecular dynamic alignment in an intense femtosecond laser field is investigated with 20 and 100 fs laser pulses for N 2 molecules and with 60 and 100 fs laser pulses for Br 2 molecules at intensities of 5x10 14 W cm -2 and 5x10 15 W cm -2 . This effect exists and only occurs during the dissociative process after the molecule is ionized. It enhances the degrees of molecular dynamic alignment and is more significant in reorienting the angular distributions of molecules towards the laser polarization direction in the conditions of high laser intensity and short pulse length. Compared with the N 2 molecule, the effect of the R dependence of laser-induced polarizability on molecular dynamic alignment for Br 2 is stronger. The reasons are presented and discussed

  20. Remote quantitative analysis of cerium through a shielding window by stand-off laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Gong, Yongdeuk; Choi, Daewoong; Han, Bo-Young; Yoo, Jonghyun; Han, Song-Hee; Lee, Yonghoon

    2014-01-01

    Highlights: • Remote LIBS analysis of cerium in the samples located behind a shielding window. • Effects of a shielding window on the remote LIBS analysis were investigated. • Multivariate analysis improves the calibration quality. - Abstract: Laser-Induced Breakdown Spectroscopy (LIBS) has been considered in many applications in nuclear industry. LIBS can be an ideal technique for analyzing the inaccessible nuclear materials typically located behind a shielding window. We report the effect of optical transmittance of the shielding window on the analytical performances of stand-off LIBS for the preliminary surrogate sample of demonstration pyrochemical process, a mixture of cerium oxide (CeO 2 ) and potassium chloride (KCl). A pulsed laser beam was focused on the surface of the sample located 1.45 m away from the stand-off LIBS device. The laser-induced plasma emission was collected through a Schmidt–Cassegrain telescope. LIBS spectra were obtained in an open path and through the shielding window. Univariate calibration curves were obtained using the integrated area of partially resolved Ce I and II lines. The limits of detection (LOD) for Ce were estimated to be 0.046 and 0.061 wt.% for the open-path and through-window analysis, respectively. We found that the through-window LOD is mainly influenced by the optical transmittance of the shielding window and therefore, the through-window LOD can be predicted from the open-path LOD and the optical transmittance of the shielding window. Also, multivariate calibration using partial least squares regression was successfully applied. The quality of calibration could be improved by the multivariate analysis

  1. Remote quantitative analysis of cerium through a shielding window by stand-off laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yongdeuk [Department of Chemistry, Mokpo National University, Jeonnam 534-729 (Korea, Republic of); Choi, Daewoong [Department of Chemistry, Mokpo National University, Jeonnam 534-729 (Korea, Republic of); Korea Atomic Energy Research Institute, P.O. Box 255, Yuseong, Daejeon 305-353 (Korea, Republic of); Han, Bo-Young, E-mail: byhan@kaeri.re.kr [Korea Atomic Energy Research Institute, P.O. Box 255, Yuseong, Daejeon 305-353 (Korea, Republic of); Yoo, Jonghyun [Applied Spectra, 46665 Fremont Boulevard, Fremont, CA 94538 (United States); Han, Song-Hee [Division of Maritime Transportation System, Mokpo National Maritime University, Jeonnam 530-729 (Korea, Republic of); Lee, Yonghoon, E-mail: yhlee@mokpo.ac.kr [Department of Chemistry, Mokpo National University, Jeonnam 534-729 (Korea, Republic of)

    2014-10-15

    Highlights: • Remote LIBS analysis of cerium in the samples located behind a shielding window. • Effects of a shielding window on the remote LIBS analysis were investigated. • Multivariate analysis improves the calibration quality. - Abstract: Laser-Induced Breakdown Spectroscopy (LIBS) has been considered in many applications in nuclear industry. LIBS can be an ideal technique for analyzing the inaccessible nuclear materials typically located behind a shielding window. We report the effect of optical transmittance of the shielding window on the analytical performances of stand-off LIBS for the preliminary surrogate sample of demonstration pyrochemical process, a mixture of cerium oxide (CeO{sub 2}) and potassium chloride (KCl). A pulsed laser beam was focused on the surface of the sample located 1.45 m away from the stand-off LIBS device. The laser-induced plasma emission was collected through a Schmidt–Cassegrain telescope. LIBS spectra were obtained in an open path and through the shielding window. Univariate calibration curves were obtained using the integrated area of partially resolved Ce I and II lines. The limits of detection (LOD) for Ce were estimated to be 0.046 and 0.061 wt.% for the open-path and through-window analysis, respectively. We found that the through-window LOD is mainly influenced by the optical transmittance of the shielding window and therefore, the through-window LOD can be predicted from the open-path LOD and the optical transmittance of the shielding window. Also, multivariate calibration using partial least squares regression was successfully applied. The quality of calibration could be improved by the multivariate analysis.

  2. High-power fiber laser cutting parameter optimization for nuclear Decommissioning

    Directory of Open Access Journals (Sweden)

    Ana Beatriz Lopez

    2017-06-01

    Full Text Available For more than 10 years, the laser process has been studied for dismantling work; however, relatively few research works have addressed the effect of high-power fiber laser cutting for thick sections. Since in the nuclear sector, a significant quantity of thick material is required to be cut, this study aims to improve the reliability of laser cutting for such work and indicates guidelines to optimize the cutting procedure, in particular, nozzle combinations (standoff distance and focus position, to minimize waste material. The results obtained show the performance levels that can be reached with 10 kW fiber lasers, using which it is possible to obtain narrower kerfs than those found in published results obtained with other lasers. Nonetheless, fiber lasers appear to show the same effects as those of CO2 and ND:YAG lasers. Thus, the main factor that affects the kerf width is the focal position, which means that minimum laser spot diameters are advised for smaller kerf widths.

  3. High-power fiber laser cutting parameter optimization for nuclear decommissioning

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Ana Beatriz; Assuncao, Eurico; Quintino, Luisa [IDMEC, Instituto Superior Tecnico, Universidade de Lisboa, Lisboa (Portugal); Khan, Ali; Blackbun, Jonathan [TWI Ltd., Cambridge (United States)

    2017-06-15

    For more than 10 years, the laser process has been studied for dismantling work; however, relatively few research works have addressed the effect of high-power fiber laser cutting for thick sections. Since in the nuclear sector, a significant quantity of thick material is required to be cut, this study aims to improve the reliability of laser cutting for such work and indicates guidelines to optimize the cutting procedure, in particular, nozzle combinations (standoff distance and focus position), to minimize waste material. The results obtained show the performance levels that can be reached with 10 kW fiber lasers, using which it is possible to obtain narrower kerfs than those found in published results obtained with other lasers. Nonetheless, fiber lasers appear to show the same effects as those of CO{sub 2} and ND:YAG lasers. Thus, the main factor that affects the kerf width is the focal position, which means that minimum laser spot diameters are advised for smaller kerf widths.

  4. Interference of laser-induced resonances in the continuous structures of a helium atom

    International Nuclear Information System (INIS)

    Magunov, A I; Strakhova, S I

    2003-01-01

    Coherent effects in the interference of overlapping laser-induced resonances in helium atoms are considered. The simultaneous action of single-mode radiation of the 294-nm second harmonic of a cw dye laser and a 1064-nm Nd:YAG laser on helium atoms provides the overlap of two resonances induced by transitions from the 1s2s 1 S and 1s4s 1 S helium levels. The shape of the overlapping laser-induced resonances in the rotating-wave approximation is described by analytic expressions, which depend on the laser radiation intensities and the ratio of laser frequencies. (nonlinear optical phenomena)

  5. Characterization of nuclear graphite elastic properties using laser ultrasonic methods

    Science.gov (United States)

    Zeng, Fan W.; Han, Karen; Olasov, Lauren R.; Gallego, Nidia C.; Contescu, Cristian I.; Spicer, James B.

    2015-05-01

    Laser ultrasonic methods have been used to characterize the elastic behaviors of commercially-available and legacy nuclear graphites. Since ultrasonic techniques are sensitive to various aspects of graphite microstructure including preferred grain orientation, microcrack orientation and porosity, laser ultrasonics is a candidate technique for monitoring graphite degradation and structural integrity in environments expected in high-temperature, gas-cooled nuclear reactors. Aspects of materials texture can be assessed by studying ultrasonic wavespeeds as a function of propagation direction and polarization. Shear wave birefringence measurements, in particular, can be used to evaluate elastic anisotropy. In this work, laser ultrasonic measurements of graphite moduli have been made to provide insight into the relationship between the microstructures and the macroscopic stiffnesses of these materials. In particular, laser ultrasonic measurements have been made using laser line sources to produce shear waves with specific polarizations. By varying the line orientation relative to the sample, shear wave birefringence measurements have been recorded. Results from shear wave birefringence measurements show that an isostatically molded graphite, such as PCIB, behaves isotropically, while an extruded graphite, such as H-451, displays significant ultrasonic texture. Graphites have complicated microstructures that depend on the manufacturing processes used, and ultrasonic texture in these materials could originate from grain orientation and preferred microcrack alignment. Effects on material isotropy due to service related microstructural changes are possible and the ultimate aim of this work is to determine the degree to which these changes can be assessed nondestructively using laser ultrasonics measurements.

  6. Impact of mechanical stress induced in silica vacuum windows on laser-induced damage.

    Science.gov (United States)

    Gingreau, Clémence; Lanternier, Thomas; Lamaignère, Laurent; Donval, Thierry; Courchinoux, Roger; Leymarie, Christophe; Néauport, Jérôme

    2018-04-15

    At the interface between vacuum and air, optical windows must keep their optical properties, despite being subjected to mechanical stress. In this Letter, we investigate the impact of such stress on the laser-induced damage of fused silica windows at the wavelength of 351 nm in the nanosecond regime. Different stress values, from 1 to 30 MPa, both tensile and compressive, were applied. No effect of the stress on the laser-induced damage was evidenced.

  7. Sources of high energy particles obtained with intense lasers for applications in nuclear physics; Sources de particules de hautes energies obtenues avec des lasers intenses pour applications a la physique nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Gerbaux, M

    2007-12-15

    This experimental study concerns the characterization of the beams of electrons and protons with energies above a few MeV produced in the interaction of an ultra-intense (10{sup 19} W/cm{sup 2}) laser beam with a 10 {mu}m thick solid target. This work was issued in the framework to use these beams in nuclear physics experiments. It was hence necessary to know quantitatively the characteristics of these particle beams. Laser accelerated particle beams have very different characteristics from conventional ones produced in accelerators, especially on account of their transience and intensity as well as their continuous energy distribution. These properties make their characterization complex and led us to develop methods combining measurements with diodes spectrometers, radiochromic films, nuclear activation of chosen materials and Monte-Carlo simulations. These methods have been employed on 2 different facilities but with similar characteristics for the study of the electron beams as a function of the target material. The angular aperture of the electron beam appears to be strongly dependent on the atomic number of the target. An experiment was also carried out to characterize at each shot the proton beam produced with the LULI 100 TW laser facility. This experiment also proved the possibility to induce nuclear reactions in plasma and to measure quantitatively the reaction rate in order to scale an experiment on the perturbation of the nucleus electronic-shells coupling via a strong electromagnetic field due to the laser. (author)

  8. Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

    International Nuclear Information System (INIS)

    Barboza, Carlos Augusto Galvão; Ginani, Fernanda; Soares, Diego Moura; Henriques, Águida Cristina Gomes; Freitas, Roseana de Almeida

    2014-01-01

    To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm"2). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4'-6-diamidino-2-phenylindole) at 72 hours. Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm"2, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm"2, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering

  9. Applications of super - high intensity lasers in nuclear engineering

    International Nuclear Information System (INIS)

    Salomaa, R.; Hakola, A.; Santala, M.

    2007-01-01

    Laser-plasma interactions arising when a super intense ultrashort laser pulse impinges a solid target creates intense partly collimated and energy resolved photons, high energy electron and protons and neutrons. In addition the plasma plume can generate huge magnetic and electric fields. Also ultra short X-ray pulses are created. We have participated in some of such experiments at Rutherford and Max-Planck Institute and assessed the applications of such kind as laser-driven accelerators. This paper discusses applications in nuclear engineering (neutron sources, isotope separation, fast ignition and transmutation, etc). In particular the potential for extreme time resolution and to partial energy resolution are assessed

  10. Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J.A.; Amado, J.M.; Tobar, M.J.; Mateo, M.P.; Yañez, A.; Nicolas, G., E-mail: gines@udc.es

    2015-05-01

    Highlights: • Chemical mapping and profiling by laser-induced breakdown spectroscopy (LIBS) of coatings produced by laser cladding. • Production of laser clads using tungsten carbide (WC) and nickel based matrix (NiCrBSi) powders. • Calibration by LIBS of hardfacing alloys with different WC concentrations. - Abstract: Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

  11. Laser-based sensor for a coolant leak detection in a nuclear reactor

    Science.gov (United States)

    Kim, T.-S.; Park, H.; Ko, K.; Lim, G.; Cha, Y.-H.; Han, J.; Jeong, D.-Y.

    2010-08-01

    Currently, the nuclear industry needs strongly a reliable detection system to continuously monitor a coolant leak during a normal operation of reactors for the ensurance of nuclear safety. In this work, we propose a new device for the coolant leak detection based on tunable diode laser spectroscopy (TDLS) by using a compact diode laser. For the feasibility experiment, we established an experimental setup consisted of a near-IR diode laser with a wavelength of about 1392 nm, a home-made multi-pass cell and a sample injection system. The feasibility test was performed for the detection of the heavy water (D2O) leaks which can happen in a pressurized heavy water reactor (PWHR). As a result, the device based on the TDLS is shown to be operated successfully in detecting a HDO molecule, which is generated from the leaked heavy water by an isotope exchange reaction between D2O and H2O. Additionally, it is suggested that the performance of the new device, such as sensitivity and stability, can be improved by adapting a cavity enhanced absorption spectroscopy and a compact DFB diode laser. We presume that this laser-based leak detector has several advantages over the conventional techniques currently employed in the nuclear power plant, such as radiation monitoring, humidity monitoring and FT-IR spectroscopy.

  12. Remote triggering of high voltage systems by laser-induced plasmas

    CSIR Research Space (South Africa)

    West, NJ

    2008-08-01

    Full Text Available -induced plasma was found to play a significant role in the breakdown process – best results being obtained when the laser was focused in the centre of the gap. Finally, the shape of the laser-induced arc is dependant on the applied electric field. When the field...

  13. Vibrationally induced nuclear quadrupole coupling in the v3 = 1 state of 189OsO4

    International Nuclear Information System (INIS)

    Scappini, F.; Kreiner, W.A.; Frye, J.M.; Oka, T.

    1987-01-01

    Electric nuclear quadrupole hyperfine structure arising from a quadrupolar nucleus at the center of tetrahedral molecules, such as 189 OsO 4 , is symmetry forbidden. However, through vibration--rotation distortion a small nuclear quadrupole coupling is induced. The hyperfine structure due to the vibrationally induced eqQ has been measured for a number of P- and R-branch transitions in the ν 3 fundamental of 189 OsO 4 , by using inverse Lamb dip spectroscopy. Microwave modulation sidebands of CO 2 laser lines have been used as the tunable infrared radiation. From the analysis of the observed hyperfine structure patterns, the values of the scalar and tensor coupling constants have been determined to be chi/sup V//sub s/ = -4.103 +- 0.048 MHz and chi/sup V//sub t/ = -3.090 +- 0.059 MHz

  14. Supersonic laser-induced jetting of aluminum micro-droplets

    International Nuclear Information System (INIS)

    Zenou, M.; Sa'ar, A.; Kotler, Z.

    2015-01-01

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets

  15. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  16. Nuclear Excitation by a Zeptosecond Multi-MeV Laser Pulse

    International Nuclear Information System (INIS)

    Weidenmueller, Hans A.

    2011-01-01

    A zeptosecond multi-MeV laser pulse may either excite a ''plasma'' of strongly interacting nucleons or a collective mode. We derive the conditions on laser energy and photon number such that either of these scenarios is realized. We use the nuclear giant dipole resonance as a representative example, and a random-matrix description of the fine-structure states and perturbation theory as tools.

  17. Laser resonant ionization spectroscopy and laser-induced resonant fluorescence spectra of samarium atom

    International Nuclear Information System (INIS)

    Jin, Changtai

    1995-01-01

    We have measured new high-lying levels of Sm atom by two-colour resonant photoionisation spectroscopy; we have observed the isotope shifts of Sm atom by laser-induced resonant fluorescence spectroscopy; the lifetime of eight low-lying levels of Sm atom were measured by using pulsed laser-Boxcar technique in atomic beam.

  18. Q-switched Nd:YAG/V:YAG microchip 1338 nm laser for laser-induced breakdown spectroscopy

    Science.gov (United States)

    Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2017-12-01

    Q-switched microchip laser emitting radiation at wavelength 1338nm was tested as a radiation source for laser induced breakdown spectroscopy (LIBS). This laser used sandwich crystal which combined in one piece the cooling part (undoped YAG crystal 4mm long), the active laser part (Nd:YAG crystal 12mm long), and the saturable absorber (V:YAG crystal 0.7mm long). The diameter of this crystal was 5 mm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith crystal surfaces. The pump mirror (HT @ 808 nm, HR @ 1.3 ¹m) was placed on the undoped YAG part. The output coupler (R = 90% @ 1338 nm) was placed on the V:YAG part. The fibre-coupled 808nm pumping laser diode was operating in pulsed regime (rep. rate 250 Hz, pulse width 300 ¹s, pulse energy 6 mJ). Using this pumping, stable and high reproducible Q-switched pulses were generated at wavelength 1338 nm. Pulse length was 6.2 ns (FWHM) and the mean output power was 33mW. The single pulse energy and peak power was 0.13mJ and 21kW, respectively. Laser was operating in fundamental TEM00 mode. The laser radiation was focused on a tested sample using single plano-convex lens (focal length 75 mm). The focal spot radius was 40 ¹m. The corresponding peak-power density was 0.83GW/cm2. The laser induced break-down was successfully reached and corresponding laser-induced plasma spectra were recorded for set of metallic elements (Cu, Ag, Au, In, Zn, Al, Fe, Ni, Cr) and alloys (Sn-Pb solder, duralumin, stainless-steel, brass). To record the spectra, StellarNet BLACK-Comet concave grating CCD-based spectrometer was used without any special collimation optics. Thanks to used laser wavelength far from the detector sensitivity, no special filtering was needed to overcome the CCD dazzling. The constructed laser could significantly improve repletion-rate of up-to-date LIBS devices.

  19. Impurity monitoring by laser-induced fluorescence techniques

    International Nuclear Information System (INIS)

    Gelbwachs, J.A.

    1984-01-01

    Laser-induced fluorescence spectroscopy can provide a highly sensitive and selective means of detecting atomic and ionic impurities. Because the photodetector can be physically isolated from the laser-excited region, these techniques can be applied to monitoring in hostile environments. The basic concepts behind fluorescence detection are reviewed. Saturated optical excitation is shown to maximize impurity atom emission yield while mitigating effects of laser intensity fluctuations upon absolute density calibration. Monitoring in high- and low-pressure monitoring environments is compared. Methods to improve detection sensitivity by luminescence background suppression are presented

  20. Imaging femtosecond laser-induced electronic excitation in glass

    International Nuclear Information System (INIS)

    Mao Xianglei; Mao, Samuel S.; Russo, Richard E.

    2003-01-01

    While substantial progress has been achieved in understanding laser ablation on the nanosecond and picosecond time scales, it remains a considerable challenge to elucidate the underlying mechanisms during femtosecond laser material interactions. We present experimental observations of electronic excitation inside a wide band gap glass during single femtosecond laser pulse (100 fs, 800 nm) irradiation. Using a femtosecond time-resolved imaging technique, we measured the evolution of a laser-induced electronic plasma inside the glass and calculated the electron number density to be on the order of 10 19 cm -3

  1. Femtosecond versus nanosecond laser machining: comparison of induced stresses and structural changes in silicon wafers

    International Nuclear Information System (INIS)

    Amer, M.S.; El-Ashry, M.A.; Dosser, L.R.; Hix, K.E.; Maguire, J.F.; Irwin, Bryan

    2005-01-01

    Laser micromachining has proven to be a very successful tool for precision machining and microfabrication with applications in microelectronics, MEMS, medical device, aerospace, biomedical, and defense applications. Femtosecond (FS) laser micromachining is usually thought to be of minimal heat-affected zone (HAZ) local to the micromachined feature. The assumption of reduced HAZ is attributed to the absence of direct coupling of the laser energy into the thermal modes of the material during irradiation. However, a substantial HAZ is thought to exist when machining with lasers having pulse durations in the nanosecond (NS) regime. In this paper, we compare the results of micromachining a single crystal silicon wafer using a 150-femtosecond and a 30-nanosecond lasers. Induced stress and amorphization of the silicon single crystal were monitored using micro-Raman spectroscopy as a function of the fluence and pulse duration of the incident laser. The onset of average induced stress occurs at lower fluence when machining with the femtosecond pulse laser. Induced stresses were found to maximize at fluence of 44 J cm -2 and 8 J cm -2 for nanosecond and femtosecond pulsed lasers, respectively. In both laser pulse regimes, a maximum induced stress is observed at which point the induced stress begins to decrease as the fluence is increased. The maximum induced stress was comparable at 2.0 GPa and 1.5 GPa for the two lasers. For the nanosecond pulse laser, the induced amorphization reached a plateau of approximately 20% for fluence exceeding 22 J cm -2 . For the femtosecond pulse laser, however, induced amorphization was approximately 17% independent of the laser fluence within the experimental range. These two values can be considered nominally the same within experimental error. For femtosecond laser machining, some effect of the laser polarization on the amount of induced stress and amorphization was also observed

  2. Depth-resolved sample composition analysis using laser-induced ablation-quadrupole mass spectrometry and laser-induced breakdown spectroscopy

    Science.gov (United States)

    Oelmann, J.; Gierse, N.; Li, C.; Brezinsek, S.; Zlobinski, M.; Turan, B.; Haas, S.; Linsmeier, Ch.

    2018-06-01

    Monitoring a sample's material composition became more and more important over the last years for both - industrial process control as well as for post mortem analysis in research and industrial development. Although material composition identification as well as a comparison with standard samples works fine, there is a lack of diagnostics which can provide quantitative information with depth resolution without any standard samples. We present a novel method utilizing a residual gas analysis with quadrupole mass spectrometry after picosecond laser-induced ablation and release of volatile species. In the present experiment, well characterized multilayer thin film solar cells (μc-Si:H and a-Si:D as p-i-n-junctions on ZnO:Al electrodes) are used as a set of well characterized material samples to demonstrate the capabilities of the new method. The linearity of the spectrometer signal to gas pressure simplifies its calibration and reduces its uncertainties in comparison with other analysis techniques, although high vacuum conditions (10-6 hPa to 10-7 hPa) are required to reach high sensitivity better than the percent-range. Moreover, the laser-ablation based sample analysis requires no preparation of the sample and is flexible regarding ablation rates. The application of a picosecond laser pulse ensures that the thermal penetration depth of the laser is in the same order of magnitude as the ablation rate, which enables to achieve depth resolutions in the order of 100 nm and avoids matrix mixing effects at the edge of the laser-induced crater in the sample.

  3. Robust nanopatterning by laser-induced dewetting of metal nanofilms

    International Nuclear Information System (INIS)

    Favazza, Christopher; Kalyanaraman, Ramki; Sureshkumar, Radhakrishna

    2006-01-01

    We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1≤h≤8 nm on SiO 2 was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with unimodal size distribution and short range ordering in nearest neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting

  4. Robust nanopatterning by laser-induced dewetting of metal nanofilms

    Energy Technology Data Exchange (ETDEWEB)

    Favazza, Christopher [Department of Physics, Washington University in St Louis, MO 63130 (United States); Kalyanaraman, Ramki [Department of Physics, Washington University in St Louis, MO 63130 (United States); Sureshkumar, Radhakrishna [Center for Materials Innovation, Washington University in St Louis, MO 63130 (United States)

    2006-08-28

    We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1{<=}h{<=}8 nm on SiO{sub 2} was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with unimodal size distribution and short range ordering in nearest neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting.

  5. Robust nanopatterning by laser-induced dewetting of metal nanofilms.

    Science.gov (United States)

    Favazza, Christopher; Kalyanaraman, Ramki; Sureshkumar, Radhakrishna

    2006-08-28

    We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1≤h≤8 nm on SiO(2) was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with unimodal size distribution and short range ordering in nearest neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting.

  6. Laser-enhanced chemical reactions and the liquid state. II. Possible applications to nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    DePoorter, G.L.; Rofer-DePoorter, C.K.

    1976-01-01

    Laser photochemistry is surveyed as a possible improvement upon the Purex process for reprocessing spent nuclear fuel. Most of the components of spent nuclear fuel are photochemically active, and lasers can be used to selectively excite individual chemical species. The great variety of chemical species present and the degree of separation that must be achieved present difficulties in reprocessing. Lasers may be able to improve the necessary separations by photochemical reaction or effects on rates and equilibria of reactions

  7. Isotopic imaging via nuclear resonance fluorescence with laser-based Thomson radiation

    Science.gov (United States)

    Barty, Christopher P. J. [Hayward, CA; Hartemann, Frederic V [San Ramon, CA; McNabb, Dennis P [Alameda, CA; Pruet, Jason A [Brentwood, CA

    2009-07-21

    The present invention utilizes novel laser-based, high-brightness, high-spatial-resolution, pencil-beam sources of spectrally pure hard x-ray and gamma-ray radiation to induce resonant scattering in specific nuclei, i.e., nuclear resonance fluorescence. By monitoring such fluorescence as a function of beam position, it is possible to image in either two dimensions or three dimensions, the position and concentration of individual isotopes in a specific material configuration. Such methods of the present invention material identification, spatial resolution of material location and ability to locate and identify materials shielded by other materials, such as, for example, behind a lead wall. The foundation of the present invention is the generation of quasimonochromatic high-energy x-ray (100's of keV) and gamma-ray (greater than about 1 MeV) radiation via the collision of intense laser pulses from relativistic electrons. Such a process as utilized herein, i.e., Thomson scattering or inverse-Compton scattering, produces beams having diameters from about 1 micron to about 100 microns of high-energy photons with a bandwidth of .DELTA.E/E of approximately 10E.sup.-3.

  8. Erratum to: Measurement of copper vapour laser-induced ...

    Indian Academy of Sciences (India)

    Erratum to: Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by. Michelson interferometer. A WAHID. ∗. , S KUNDU, J S B SINGH, A K SINGH, A KHATTAR,. S K MAURYA, J S DHUMAL and K DASGUPTA. Laser & Plasma Technology Division, Beam Technology Development ...

  9. Laser-Induced, Local Oxidation of Copper Nanoparticle Films During Raman Measurements

    Science.gov (United States)

    Hight Walker, Angela R.; Cheng, Guangjun; Calizo, Irene

    2011-03-01

    The optical properties of gold and silver nanoparticles and their films have been thoroughly investigated as surface enhanced Raman scattering (SERS) substrates and chemical reaction promoters. Similar to gold and silver nanoparticles, copper nanoparticles exhibit distinct plasmon absorptions in the visible region. The work on copper nanoparticles and their films is limited due to their oxidization in air. However, their high reactivity actually provides an opportunity to exploit the laser-induced thermal effect and chemical reactions of these nanoparticles. Here, we present our investigation of the local oxidation of a copper nanoparticle film induced by a visible laser source during Raman spectroscopic measurements. The copper nanoparticle film is prepared by drop-casting chemically synthesized copper colloid onto silicon oxide/silicon substrate. The local oxidation induced by visible lasers in Raman spectroscopy is monitored with the distinct scattering peaks for copper oxides. Optical microscopy and scanning electron microscopy have been used to characterize the laser-induced morphological changes in the film. The results of this oxidation process with different excitation wavelengths and different laser powers will be presented.

  10. [Study of enhancement effect of laser-induced crater on plasma radiation].

    Science.gov (United States)

    Chen, Jin-Zhong; Zhang, Xiao-Ping; Guo, Qing-Lin; Su, Hong-Xin; Li, Guang

    2009-02-01

    Single pulses exported from high-energy neodymium glass laser were used to act on the same position of soil sample surface repeatedly, and the plasma emission spectra generated from sequential laser pulse action were collected by spectral recording system. The experimental results show that the laser-induced soil plasma radiation was enhanced continuously under the confinement effect of the crater walls, and the line intensities and signal-to-background ratios both had different improvements along with increasing the number of acting pulses. The photographs of the plasma image and crater appearance were taken to study the plasma shape, laser-induced crater appearance, and the mass of the ablated sample. The internal mechanism behind that laser-induced crater enhanced plasma radiation was researched. Under the sequential laser pulse action, the forming plasma as a result enlarges gradually first, leading to distortion at the trail of plasma plume, and then, its volume diminishes slowly. And also, the color of the plasma changes from buff to white gradually, which implies that the temperature increases constantly. The laser-induced crater had a regular shape, that is, the diameter increased from its bottom to top gradually, thus forming a taper. The mass of the laser-ablated substance descends along with increasing the amount of action pulse. Atomization degree of vaporized substance was improved in virtue of the crater confinement effect, Fresnel absorption produced from the crater walls reflection, and the inverse bremsstrahlung, and the plasma radiation intensity was enhanced as a result.

  11. Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas.

    Science.gov (United States)

    Liu, Lei; Deng, Leimin; Fan, Lisha; Huang, Xi; Lu, Yao; Shen, Xiaokang; Jiang, Lan; Silvain, Jean-François; Lu, Yongfeng

    2017-10-30

    Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al 2 O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al 2 O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O 2 chemistry in air.

  12. Laser-induced filaments in the mid-infrared

    International Nuclear Information System (INIS)

    Zheltikov, A M

    2017-01-01

    Laser-induced filamentation in the mid-infrared gives rise to unique regimes of nonlinear wave dynamics and reveals in many ways unusual nonlinear-optical properties of materials in this frequency range. The λ 2 scaling of the self-focusing threshold P cr , with radiation wavelength λ , allows the laser powers transmitted by single mid-IR filaments to be drastically increased without the loss of beam continuity and spatial coherence. When extended to the mid-infrared, laser filamentation enables new methods of pulse compression. Often working around the universal physical limitations, it helps generate few-cycle and subcycle field waveforms within an extraordinarily broad range of peak powers, from just a few up to hundreds of P cr . As a part of a bigger picture, laser-induced filamentation in the mid-infrared offers important physical insights into the general properties of the nonlinear-optical response of matter as a function of the wavelength. Unlike their near-infrared counterparts, which can be accurately described within the framework of perturbative nonlinear optics, mid-infrared filaments often entangle perturbative and nonperturbative nonlinear-optical effects, showing clear signatures of strong-field optical physics. With the role of nonperturbative nonlinear-optical phenomena growing, as a general tendency, with the field intensity and the driver wavelength, extension of laser filamentation to even longer driver wavelengths, toward the long-wavelength infrared, promises a hic sunt dracones land. (topical review)

  13. Confinement inertial fusion. Power reactors of nuclear fusion by lasers

    International Nuclear Information System (INIS)

    Velarde, G.; Ahnert, C.; Aragones, J.M.; Leira, G; Martinez-Val, J.M.

    1980-01-01

    The energy crisis and the need of the nuclear fusion energy are analized. The nuclear processes in the laser interation with the ablator material are studied, as well as the thermohydrodinamic processes in the implossion, and the neutronics of the fusion. The fusion reactor components are described and the economic and social impact of its introduction in the future energetic strategies.(author)

  14. Nuclear diagnostics of high intensity laser plasma interactions

    International Nuclear Information System (INIS)

    Krushelnick, K.; Santala, M.I.K.; Beg, F.N.; Clark, E.L.; Dangor, A.E.; Tatarakis, M.; Watts, I.; Wei, M.S.; Zepf, M.; Ledingham, K.W.D.; McCanny, T.; Spencer, I.; Clarke, R.J.; Norreys, P.A.

    2002-01-01

    Nuclear activation has been observed in materials exposed to energetic protons and heavy ions generated from high intensity laser-solid interactions (at focused intensities up to 5x10 19 W/cm 2 ). The energy spectrum of the protons is determined through the use of these nuclear activation techniques and is found to be consistent with other ion diagnostics. Heavy ion fusion reactions and large neutron fluxes from the (p, n) reactions were also observed. The reduction of proton emission and increase in heavy ion energy using heated targets was also observed

  15. Heat pump processes induced by laser radiation

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.

    1980-01-01

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

  16. CW-laser induced microchannels in dye-polymethacrylic acid films

    OpenAIRE

    M.A. Camacho-López

    2007-01-01

    In this work we report on the formation of microchannels on dye-polymethacrylic acid films using a cw-laser. A focalized beam of a He-Ne laser (632.8 nm emission line) was used to form microchannels on the films. It was found that there exists a laser power density threshold for a pit formation that depends on the dye concentration. The dimensions of the laser-induced channels are dependent on the laser power density. Microchannel formation in the transparent polymethacrylic acid films was no...

  17. Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Barboza, Carlos Augusto Galvão; Ginani, Fernanda [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil); Soares, Diego Moura [Universidade Federal de Pernambuco, Recife, PE (Brazil); Henriques, Águida Cristina Gomes; Freitas, Roseana de Almeida [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil)

    2014-07-01

    To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm{sup 2}). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4'-6-diamidino-2-phenylindole) at 72 hours. Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm{sup 2}, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm{sup 2}, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering.

  18. Laser-Induced Formation and Disintegration of Gold Nanopeanuts and Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Shin; Yoon, Jun Hee; Kim, Hyung Jun; Huh, Young Duk; Yoon, Sang Woon [Dankook University, Yongin (Korea, Republic of)

    2010-04-15

    We report the laser-induced formation of peanut-shaped gold nanoparticles (Au nanopeanuts) and gold nanowires (AuNWs), and their morphological properties. Pulsed laser irradiation of citrate-capped gold nanoparticles at 532 nm induces fragmentation, spherical growth, the formation of Au nanopeanuts, and the formation of AuNWs, sequentially. High-resolution transmission electron microscopy images reveal that the Au nanopeanuts are formed by instantaneous fusion of spherical nanoparticles in random orientation by laser heating. Furthermore, Au nanopeanuts are bridged in a linear direction to form AuNWs by an amorphous accumulation of gold atoms in the junction. The laser-produced Au nanopeanuts and AuNWs slowly disintegrate, restoring the spherical shape of the original Au nanoparticles when the laser irradiation is stopped. The addition of citrate effectively prevents them from transforming back to the nanospheres.

  19. Laser-induced ionization of Na vapor

    International Nuclear Information System (INIS)

    Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

    1982-01-01

    The production of Na 2 + ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na 2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na 2 D 1 PIμ Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na 2 + ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na 2 + through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na 2 molecules

  20. Laser-induced breakdown spectroscopy with laser irradiation resonant with vibrational transitions

    International Nuclear Information System (INIS)

    Khachatrian, Ani; Dagdigian, Paul J.

    2010-01-01

    An investigation of laser-induced breakdown spectroscopy (LIBS) of polymers, both in bulk form and spin coated on Si wafers, with laser irradiation in the mid-infrared spectral region is presented. Of particular interest is whether the LIBS signals are enhanced when the laser wavelength is resonant with a fundamental vibrational transition of the polymer. Significant increases in the LIBS signals were observed for irradiation on hydride stretch fundamental transitions, and the magnitude of the enhancement showed a strong dependence on the mode excited. The role of the substrate was investigated by comparison of results for bulk and spin-coated samples. The polymers investigated were Nylon 12 and poly(vinyl alcohol-co-ethylene).

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser......-machined surfaces, normalized bearing area curves and parameters are used to characterize the surface quantitatively. The range of normalized bearing area curve parameters for plate-able surface is suggested. PBT/PET with 40 % glass fiber was used as the substrate material. For all of the studied lasers......, the parameters were varied in a relatively large range, and matrixes of the laser-machined surface were obtained. The topography of those laser-machined surfaces was examined by scanning electronic microscope (SEM). For each sample examined by SEM, there was an identical workpiece plated by for 90 min...

  2. Aerosol core nuclear reactor for space-based high energy/power nuclear-pumped lasers

    International Nuclear Information System (INIS)

    Prelas, M.A.; Boody, F.P.; Zediker, M.S.

    1987-01-01

    An aerosol core reactor concept can overcome the efficiency and/or chemical activity problems of other fuel-reactant interface concepts. In the design of a laser using the nuclear energy for a photon-intermediate pumping scheme, several features of the aerosol core reactor concept are attractive. First, the photon-intermediate pumping concept coupled with photon concentration methods and the aerosol fuel can provide the high power densities required to drive high energy/power lasers efficiently (about 25 to 100 kW/cu cm). Secondly, the intermediate photons should have relatively large mean free paths in the aerosol fuel which will allow the concept to scale more favorably. Finally, the aerosol core reactor concept can use materials which should allow the system to operate at high temperatures. An excimer laser pumped by the photons created in the fluorescer driven by a self-critical aerosol core reactor would have reasonable dimensions (finite cylinder of height 245 cm and radius of 245 cm), reasonable laser energy (1 MJ in approximately a 1 millisecond pulse), and reasonable mass (21 kg uranium, 8280 kg moderator, 460 kg fluorescer, 450 kg laser medium, and 3233 kg reflector). 12 references

  3. Nuclear reactivity control using laser induced polarization

    International Nuclear Information System (INIS)

    Bowman, C.D.

    1990-01-01

    This patent describes a control element for reactivity control of a fission source provides an atomic density of 3 He in a control volume which is effective to control criticality as the 3 He is spin-polarized. Spin-polarization of the 3 He affects the cross section of the control volume for fission neutrons and hence, the reactivity. An irradiation source is directed within the 3 He for spin-polarizing the 3 He. An alkali-metal vapor may be included with the 3 He where a laser spin-polarizes the alkali-metal atoms which in turn, spin-couple with 3 He to spin-polarize the 3 He atoms

  4. Study on the high-precision laser welding technology of nuclear fuel elements processing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soo Sung; Yang, M. S.; Kim, W. K.; Lee, D. Y

    2001-01-01

    The proper welding method for appendage of bearing pads and spacers of PHWR nuclear fuel elements is considered important in respect to the soundness of weldments and the improvement of the performance of nuclear fuels during the operation in reactor. The probability of welding defects of the appendage parts is mostly apt to occur and it is connected directly with the safty and life prediction of the nuclear reactor in operation. Recently there has been studied all over the world to develope welding technology by laser in nuclear fuel processing, and the appendage of bearing pads and spacers of PHWR nuclear fuel elements. Therefore, the purpose of this study is to investigate the characteristics of the laser welded specimens and make some samples for the appendage of bearing pads of PHWR nuclear fuel elements. This study will be also provide the basic data for the fabrications of the appendage of bearing pads and spacers. Especially the laser welding is supposed to be used in the practical application such as precise materials manufacturing fields. In this respect this technology is not only a basic advanced technology with wide applications but also likely to be used for the development of directly applicable technologies for industries, with high potential benefits derived in the view point of economy and industry.

  5. Study on the high-precision laser welding technology of nuclear fuel elements processing

    International Nuclear Information System (INIS)

    Kim, Soo Sung; Yang, M. S.; Kim, W. K.; Lee, D. Y.

    2001-01-01

    The proper welding method for appendage of bearing pads and spacers of PHWR nuclear fuel elements is considered important in respect to the soundness of weldments and the improvement of the performance of nuclear fuels during the operation in reactor. The probability of welding defects of the appendage parts is mostly apt to occur and it is connected directly with the safty and life prediction of the nuclear reactor in operation. Recently there has been studied all over the world to develope welding technology by laser in nuclear fuel processing, and the appendage of bearing pads and spacers of PHWR nuclear fuel elements. Therefore, the purpose of this study is to investigate the characteristics of the laser welded specimens and make some samples for the appendage of bearing pads of PHWR nuclear fuel elements. This study will be also provide the basic data for the fabrications of the appendage of bearing pads and spacers. Especially the laser welding is supposed to be used in the practical application such as precise materials manufacturing fields. In this respect this technology is not only a basic advanced technology with wide applications but also likely to be used for the development of directly applicable technologies for industries, with high potential benefits derived in the view point of economy and industry

  6. Sensitive elemental detection using microwave-assisted laser-induced breakdown imaging

    Science.gov (United States)

    Iqbal, Adeel; Sun, Zhiwei; Wall, Matthew; Alwahabi, Zeyad T.

    2017-10-01

    This study reports a sensitive spectroscopic method for quantitative elemental detection by manipulating the temporal and spatial parameters of laser-induced plasma. The method was tested for indium detection in solid samples, in which laser ablation was used to generate a tiny plasma. The lifetime of the laser-induced plasma can be extended to hundreds of microseconds using microwave injection to remobilize the electrons. In this novel method, temporal integrated signal of indium emission was significantly enhanced. Meanwhile, the projected detectable area of the excited indium atoms was also significantly improved using an interference-, instead of diffraction-, based technique, achieved by directly imaging microwave-enhanced plasma through a novel narrow-bandpass filter, exactly centered at the indium emission line. Quantitative laser-induce breakdown spectroscopy was also recorded simultaneously with the new imaging method. The intensities recorded from both methods exhibit very good mutual linear relationship. The detection intensity was improved to 14-folds because of the combined improvements in the plasma lifetime and the area of detection.

  7. Influence of external magnetic field on laser-induced gold nanoparticles fragmentation

    International Nuclear Information System (INIS)

    Serkov, A. A.; Rakov, I. I.; Simakin, A. V.; Kuzmin, P. G.; Shafeev, G. A.; Mikhailova, G. N.; Antonova, L. Kh.; Troitskii, A. V.; Kuzmin, G. P.

    2016-01-01

    Laser-assisted fragmentation is an efficient method of the nanoparticles size and morphology control. However, its exact mechanisms are still under consideration. One of the remaining problems is the plasma formation, inevitably occurring upon the high intensity laser irradiation. In this Letter, the role of the laser-induced plasma is studied via introduction of high-intensity external magnetic field (up to 7.5 T). Its presence is found to cause the plasma emission to start earlier regarding to a laser pulse, also increasing the plume luminosity. Under these conditions, the acceleration of nanoparticles fragmentation down to a few nanometers is observed. Laser-induced plasma interaction with magnetic field and consequent energy transfer from plasma to nanoparticles are discussed.

  8. Effects of ionizing radiation on laser-induced damage in SiO/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Soileau, M J; Mansour, N; Canto, E; Griscom, D L

    1988-05-01

    The effects of radiation damage on bulk laser-induced damage in SiO/sub 2/ were investigated. Samples studied included Spectrasil A, B, and WF (water free). Measurements of laser-induced breakdown were conducted with 532 and 1064 nm laser pulses of approximately 20 ns duration. Reductions of up to 40% in the laser-induced breakdown threshold were observed at 532 nm for samples exposed to 10/sup 8/ rad of ..gamma..-radiation. The decrease in breakdown threshold for irradiated SiO/sub 2/ samples at 532 nm was found to be proportional to the linear absorption of the specimen at 266 nm. These results are in good agreement with a proposed model which suggests that two-photon absorption initiated avalanche process is responsible for laser-induced breakdown for these materials.

  9. Lasers '89

    International Nuclear Information System (INIS)

    Harris, D.G.; Shay, T.M.

    1990-01-01

    This book covers the following topics: XUV, X-Ray and Gamma-Ray Lasers, excimer lasers, chemical lasers, nuclear pumped lasers, high power gas lasers, solid state lasers, laser spectroscopy. The paper presented include: Development of KrF lasers for fusion and Nuclear driven solid-state lasers

  10. Flexible temperature and flow sensor from laser-induced graphene

    KAUST Repository

    Marengo, Marco

    2017-12-25

    Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced graphene. The main benefits arise from peculiar electrical, thermal and mechanical performances of the material thus obtained, along with a cheap and simple fabrication process. The temperature sensor is a negative temperature coefficient thermistor with non-linear response typical of semi-metals. The thermistor shows a 4% decrease of the resistance in a temperature range of 20–60 °C. The flow sensor exploits the piezoresistive properties of laser-induced graphene and can be used both in gaseous and liquid media thanks to a protective polydimethylsiloxane coating. Main characteristics are ultra-fast response and versatility in design offered by the laser technology.

  11. Laser-induced breakdown spectroscopy of tantalum plasma

    International Nuclear Information System (INIS)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq

    2013-01-01

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO 2 : N 2 : He), O 2 , N 2 , and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis

  12. Laser-induced photochemical enrichment of boron isotopes

    International Nuclear Information System (INIS)

    Freund, S.M.; Ritter, J.J.

    1976-01-01

    A boron trichloride starting material containing both boron-10 isotopes and boron-11 isotopes is selectively enriched in one or the other of these isotopes by a laser-induced photochemical method involving the reaction of laser-excited boron trichloride with either H 2 S or D 2 S. The method is carried out by subjecting a low pressure gaseous mixture of boron trichloride starting material and the sulfide to infrared radiation from a carbon dioxide TE laser. The wave length of the radiation is selected so as to selectively excite one or the other of boron-10 BCl 3 molecules or boron-11 BCl 3 molecules, thereby making them preferentially more reactive with the sulfide. The laser-induced reaction produces both a boron-containing solid phase reaction product and a gaseous phase containing mostly unreacted BCl 3 and small amounts of sulfhydroboranes. Pure boron trichloride selectively enriched in one of the isotopes is recovered as the primary product of the method from the gaseous phase by a multi-step recovery procedure. Pure boron trichloride enriched in the other isotope is recovered as a secondary product of the method by the subsequent chlorination of the solid phase reaction product followed by separation of BCl 3 from the mixture of gaseous products resulting from the chlorination

  13. Laser-induced breakdown spectroscopy of tantalum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

    2013-07-15

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  14. Laser induced magnetization switching in a TbFeCo ferrimagnetic thin film: discerning the impact of dipolar fields, laser heating and laser helicity by XPEEM

    International Nuclear Information System (INIS)

    Gierster, L.; Ünal, A.A.; Pape, L.; Radu, F.; Kronast, F.

    2015-01-01

    We investigate laser induced magnetic switching in a ferrimagnetic thin film of Tb_2_2Fe_6_9Co_9 by PEEM. Using a small laser beam with a spot size of 3–5 µm in diameter in combination with high resolution magnetic soft X-ray microscopy we are able to discriminate between different effects that govern the microscopic switching process, namely the influence of the laser heating, of the helicity dependent momentum transfer, and of the dipolar coupling. Applying a sequence of femtosecond laser pulses to a previously saturated TbFeCo film leads to the formation of ring shaped magnetic structures in which all three effects can be observed. Laser helicity assisted switching is only observed in a narrow region within the Gaussian profile of the laser spot. Whereas in the center of the laser spot we find clear evidence for thermal demagnetization and in the outermost areas magnetic switching is determined by dipolar coupling with the surrounding film. Our findings demonstrate that by reducing the laser spot size the influence of dipolar coupling on laser induced switching is becoming increasingly important. - Highlights: • With a new PEEM sample holder a laser spot size of 3–5 µm in diameter is reached. • Spatial resolved imaging of laser induced magnetization reversal. • A single femtosecond laser pulse leads to a multi-domain state in TbFeCo. • A pulse sequence results in a ring-shaped magnetic pattern caused by dipolar fields. • Laser helicity dependent effects appear only in a narrow fluence region.

  15. The development of fieldable laser-induced breakdown spectrometer: No limits on the horizon

    International Nuclear Information System (INIS)

    Fortes, F.J.; Laserna, J.J.

    2010-01-01

    In this review, new trends in the development of fieldable instrumentation based on laser-induced breakdown spectroscopy (LIBS) and its recent applications is presented. Depending on the LIBS configuration we will distinguish between portable, remote and stand-off instruments. Moreover, the development of portable systems gives greater flexibility and also increases the range of LIBS applications. In general, portable instruments are employed in close-contact applications like immovable artworks, contaminated soils and environmental diagnostic, while remote and stand-off instruments are normally used in analytical applications at distances where access to the sample is difficult or hazardous. Although remote and stand-off instruments are both used for chemical analysis at distances, the instrumental configurations are completely different. In remote analysis, an optical fiber is employed to deliver the laser energy a certain distance. This approach has been usually restricted to industrial applications, bulk analysis in water, geological measurements and chemical analysis on nuclear stations. In the case of stand-off applications, the laser beam and the returning plasma light are transmitted in an open-path configuration. In this article we also discuss the instrumental requirements in the design of remote and stand-off instruments.

  16. A comparative study of the laser induce breakdown spectroscopy in single- and double-pulse laser geometry

    International Nuclear Information System (INIS)

    Sun Duixiong; Su Maogen; Dong Chenzhong; Wen Guanhong; Cao Xiangnian

    2013-01-01

    A time resolved laser induced breakdown spectroscopy technique (LIBS) was used for the investigation of emission signal enhancement on double-pulse LIBS. Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to generate laser-induced plasma on aluminium-based alloys. The plasma emission signals were recorded by spectrometer with ICCD detector. Spectral response calibration was performed by using deuterium and tungsten halogen lamps. Time evolution of the plasma temperature and electron density was investigated in SP and DP experiments. Based on the investigation of plasma parameters, the enhancements of emission line intensities were investigated, and the mechanisms of it were discussed. (author)

  17. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    Science.gov (United States)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  18. New pulsed YAG laser performances in cutting thick metallic materials for nuclear applications

    International Nuclear Information System (INIS)

    Alfille, J.P.; Prunele, D. de; Pilot, G.

    1996-01-01

    The purpose of this study was to evaluate the capacities of the pulsed YAG laser thick cutting on metallic material and to compare with the CO 2 laser capacities. Stainless steel (304L) cutting tests were made in air and underwater using CO 2 and YAG lasers. A performance assessment was made for each laser and the wastes produced in the cutting operation were measured and the gases and the aerosols analyzed. The results show that the pulsed YAG laser is high performance tool for thick cutting and particularly attractive for nuclear applications

  19. Study of xenon binding in cryptophane-A using laser-induced NMR polarization enhancement

    International Nuclear Information System (INIS)

    Luhmer, M.; Goodson, B.M.; Song, Y.Q.; Laws, D.D.; Kaiser, L.; Pines, A.; Lawrence Berkeley National Lab., CA

    1999-01-01

    Xenon is chemically inert, yet exhibits NMR parameters that are highly sensitive to its chemical environment. Considerable work has therefore capitalized on the utility of 129 Xe (I = 1/2) as a magnetic resonance probe of molecules, materials, and biological systems. In solution, spin-polarization transfer between laser-polarized xenon and the hydrogen nuclei of nearby molecules leads to signal enhancements in the resolved 1 H NMR spectrum, offering new opportunities for probing the chemical environment of xenon atoms. Following binding of laser-polarized xenon to molecules of cryptophane-A, selective enhancements of the 1 H NMR signals were observed. A theoretical framework for the interpretation of such experimental results is provided, and the spin polarization-induced nuclear Overhauser effects are shown to yield information about the molecular environment of xenon. The observed selective 1 H enhancements allowed xenon-proton internuclear distances to be estimated. These distances reveal structural characteristics of the complex, including the preferred molecular conformations adopted by cryptophane-A upon binding of xenon

  20. Laser-induced breakdown spectroscopy analysis of the copper added to gadolinium (Contract research)

    International Nuclear Information System (INIS)

    Akaoka, Katsuaki; Maruyama, Youichiro; Oba, Masaki; Miyabe, Masabumi; Wakaida, Ikuo

    2008-11-01

    For applying Laser-induced breakdown Spectroscopy (LIBS) to the analysis of nuclear fuel materials, it is very important to investigate the analytical method to identify the emission spectrum and its intensity on impurities intermingled within complex emission spectra of matrix elements such as uranium (U) and plutonium (Pu). Experiments using gadolinium (Gd) as simulated sample, in which several 100 ppm of copper (Cu) was contained, were performed and the analytical performance was estimated. The spectrum was decomposed into each peak of some spectra component on Gd and Cu. And the result, intensity of Cu component intermingled in Gd was determined quantitatively. In order to evaluate the linearity in the impurity analysis, the experiments with various concentration of Cu were carried out. The detection limit was determined to be about 70 ppm from the equivalent noise level which was estimated from the standard deviation in wavelength. The results curried out under the other laser conditions (intensity and wavelength) ware also evaluated. (author)

  1. Characterization of laser-induced ignition of biogas-air mixtures

    International Nuclear Information System (INIS)

    Forsich, Christian; Lackner, Maximilian; Winter, Franz; Kopecek, Herbert; Wintner, Ernst

    2004-01-01

    Fuel-rich to fuel-lean biogas-air mixtures were ignited by a Nd:YAG laser at initial pressures of up to 3 MPa and compared to the ignition of methane-air mixtures. The investigations were performed in a constant volume vessel heatable up to 473 K. An InGaAsSb/AlGaAsSb quantum well ridge diode laser operating at 2.55 μm was used to track the generation of water in the vicinity of the laser spark in a semi-quantitative manner. Additionally, the flame emissions during the ignition process were recorded and a gas inhomogeneity index was deduced. Laser-induced ignition and its accompanying effects could be characterized on a time scale spanning four orders of magnitude. The presence of CO 2 in the biogas reduces the burning velocity. The flame emissions result in a much higher intensity for methane than it was the case during biogas ignition. This knowledge concludes that engines fuelled with biogas ultimately affect the performance of the process in a different way than with methane. Methane-air mixtures can be utilized in internal combustion engines with a higher air-fuel ratio than biogas. Comparing failed laser-induced ignition of methane-air and biogas-air mixtures similar results were obtained. The three parameters water absorbance, flame emission and the gas inhomogeneity index constitute a suitable tool for judging the quality of laser-induced ignition of hydrocarbon-air mixtures at elevated pressures and temperatures as encountered in internal combustion engines

  2. Influence of nuclear radiation and laser beams on optical fibers and components

    Directory of Open Access Journals (Sweden)

    Pantelić Slađana N.

    2011-01-01

    Full Text Available The influence of nuclear radiation and particles has been the object of investigation for a long time. For new materials and systems the research should be continued. Human activities in various environments, including space, call for more detailed research. The role of fibers in contemporary communications, medicine, and industry increases. Fibers, their connections and fused optics components have one type of tasks - the transmission of information and power. The other type of tasks is reserved for fiber lasers: quantum generators and amplifiers. The third type of tasks is for fiber sensors, including high energy nuclear physics. In this paper we present some chosen topics in the mentioned areas as well as our experiments with nuclear radiation and laser beams to fiber and bulk materials of various nature (glass, polymer, metallic, etc..

  3. Reactor operations for nuclear pumping of lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beck, G; Cooper, G [University of Illinois (United States)

    1974-07-01

    Experiments involving the measurement of gas parameters that are related to lasing, and lasing of various gas mixtures have comprised a major part of the utilization of the University of Illinois Advanced TRIGA Reactor since the upgrading of the facility was completed in 1969. A thru beam port, which was added during upgrading, has been the facility used for these measurements. The laser cell is placed in the port adjacent to the core. Alignment is then accomplished by using both ends of the port or by a mirror placed at the back side of the apparatus. The reactor has been operated in all modes (pulsing, square wave, and steady state) for the experiments although pulsing is the primary mode that is used. Laser enhancement has been obtained in several cases, but efforts toward direct pumping from the radiation alone have not as yet succeeded. Improved laser operation from direct pumping has been suggested with an emphasis on high-powered systems where the basic input energy is to be derived from a nuclear reactor.

  4. Visualization of femtosecond laser pulse-induced microincisions inside crystalline lens tissue.

    Science.gov (United States)

    Stachs, Oliver; Schumacher, Silvia; Hovakimyan, Marine; Fromm, Michael; Heisterkamp, Alexander; Lubatschowski, Holger; Guthoff, Rudolf

    2009-11-01

    To evaluate a new method for visualizing femtosecond laser pulse-induced microincisions inside crystalline lens tissue. Laser Zentrum Hannover e.V., Hannover, Germany. Lenses removed from porcine eyes were modified ex vivo by femtosecond laser pulses (wavelength 1040 nm, pulse duration 306 femtoseconds, pulse energy 1.0 to 2.5 microJ, repetition rate 100 kHz) to create defined planes at which lens fibers separate. The femtosecond laser pulses were delivered by a 3-dimension (3-D) scanning unit and transmitted by focusing optics (numerical aperture 0.18) into the lens tissue. Lens fiber orientation and femtosecond laser-induced microincisions were examined using a confocal laser scanning microscope (CLSM) based on a Rostock Cornea Module attached to a Heidelberg Retina Tomograph II. Optical sections were analyzed in 3-D using Amira software (version 4.1.1). Normal lens fibers showed a parallel pattern with diameters between 3 microm and 9 microm, depending on scanning location. Microincision visualization showed different cutting effects depending on pulse energy of the femtosecond laser. The effects ranged from altered tissue-scattering properties with all fibers intact to definite fiber separation by a wide gap. Pulse energies that were too high or overlapped too tightly produced an incomplete cutting plane due to extensive microbubble generation. The 3-D CLSM method permitted visualization and analysis of femtosecond laser pulse-induced microincisions inside crystalline lens tissue. Thus, 3-D CLSM may help optimize femtosecond laser-based procedures in the treatment of presbyopia.

  5. Towards friction control using laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Römer, Gerardus Richardus, Bernardus, Engelina; Huis in 't Veld, Bert; Schmidt, M.; Zaeh, M.

    2011-01-01

    This paper aims at contributing to the study of laser-induced periodic surface structures (LIPSS) and the description of their tribological properties in order to facilitate the knowledge for contact mechanical applications. To obtain laser parameters for LIPSS formation, we propose to execute two

  6. Laser-induced photo-thermal strain imaging

    Science.gov (United States)

    Choi, Changhoon; Ahn, Joongho; Jeon, Seungwan; Kim, Chulhong

    2018-02-01

    Vulnerable plaque is the one of the leading causes of cardiovascular disease occurrence. However, conventional intravascular imaging techniques suffer from difficulty in finding vulnerable plaque due to limitation such as lack of physiological information, imaging depth, and depth sensitivity. Therefore, new techniques are needed to help determine the vulnerability of plaque, Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed that varies with temperature of medium. During temperature increase, strain occurs in the medium and its variation tendency is depending on the type of tissue, which makes it possible to use for tissue differentiation. Here, we demonstrate laser-induced photo-thermal strain imaging (pTSI) to differentiate tissue using an intravascular ultrasound (IVUS) catheter and a 1210-nm continuous-wave laser for heating lipids intensively. During heating, consecutive US images were obtained from a custom-made phantom made of porcine fat and gelatin. A cross correlation-based speckle-tracking algorithm was then applied to calculate the strain of US images. In the strain images, the positive strain produced in lipids (porcine fat) was clearly differentiated from water-bearing tissue (gelatin). This result shows that laser-induced pTSI could be a new method to distinguish lipids in the plaque and can help to differentiate vulnerability of plaque.

  7. Low-intensity infrared laser effects on zymosan-induced articular inflammatory response

    Science.gov (United States)

    Januária dos Anjos, Lúcia Mara; da Fonseca, Adenilson d. S.; Gameiro, Jacy; de Paoli, Flávia

    2015-03-01

    Low-level therapy laser is a phototherapy treatment that involves the application of low power light in the red or infrared wavelengths in various diseases such as arthritis. In this work, we investigated whether low-intensity infrared laser therapy could cause death by caspase-6 apoptosis or DNA damage pathways in cartilage cells after zymosaninduced articular inflammatory process. Inflammatory process was induced in C57BL/6 mouse by intra-articular injection of zymosan into rear tibio-tarsal joints. Thirty animals were divided in five groups: (I) control, (II) laser, (III) zymosan-induced, (IV) zymosan-induced + laser and (V). Laser exposure was performed after zymosan administration with low-intensity infrared laser (830 nm), power 10 mW, fluence 3.0 J/cm2 at continuous mode emission, in five doses. Twenty-four hours after last irradiation, the animals were sacrificed and the right joints fixed and demineralized. Morphological analysis was observed by hematoxylin and eosin stain, pro-apoptotic (caspase-6) was analyzed by immunocytochemistry and DNA fragmentation was performed by TUNEL assay in articular cartilage cells. Inflammatory process was observed in connective tissue near to articular cartilage, in IV and V groups, indicating zymosan effect. This process was decreased in both groups after laser treatment and dexamethasone. Although groups III and IV presented higher caspase-6 and DNA fragmentation percentages, statistical differences were not observed when compared to groups I and II. Our results suggest that therapies based on low-intensity infrared lasers could reduce inflammatory process and could not cause death by caspase-6 apoptosis or DNA damage pathways in cartilage cells after zymosan-induced articular inflammatory process.

  8. Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

    Science.gov (United States)

    Weber, Stefan; Kothe, Gerd; Norris, James R.

    1997-04-01

    The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave

  9. Applications of lasers in nuclear power plants

    International Nuclear Information System (INIS)

    Raj, Rupam; Sanyal, D.N.; Sil, Jaydeb

    2013-01-01

    Applications of lasers in nuclear power plants: Bellow lip cutting and high pressure feeder coupling stud (HPFC) cutting during en-masse coolant channel replacement (EMCCR) campaign at Narora Atomic Power Station Reactor 1 in May 2006; cutting of pressure tubes from Madras Atomic Power Station 1 (MAPS-1) for easy storage in April 2005; In-situ cutting of selected coolant channel S-7 at Kakrapar Atomic Power Station (KAPS-2) (cutting of 12 mm thick end fitting and 4 mm thick liner tube of stainless steel from inside) in January 2005; Development of a miniature cutting mechanism for steam generator tubes (14 mm i.d.) from inside, In-situ bellow repair for secondary shutdown system; LASER welding may be deployed for End shield of MAPS-1 leak repair

  10. Nuclear fission fragment excitation of electronic transition laser media

    International Nuclear Information System (INIS)

    Lorents, D.C.; McCusker, M.V.; Rhodes, C.K.

    1976-01-01

    The properties of high energy electronic transition lasers excited by fission fragments are expanded. Specific characteristics of the media including density, excitation rates, wavelength, kinetics, fissile material, scale size, and medium uniformity are assessed. The use of epithermal neutrons, homogeneously mixed fissile material, and special high cross section nuclear isotopes to optimize coupling of the energy to the medium are shown to be important considerations maximizing the scale size, energy deposition, and medium uniformity. A performance limit point of approximately 1000 J/l in approximately 100 μs pulses is established for a large class of systems operating in the near ultraviolet and visible spectral regions. It is demonstrated that e-beam excitation can be used to simulate nuclear pumping conditions to facilitate the search for candidate media. Experimental data for the kinetics of a XeF* laser operating in Ar/Xe/F 2 /UF 6 mixtures are given. These reactor-pumped systems are suitable for scaling to volumes on the order of (meters) 3

  11. Laser induced forward transfer of graphene

    NARCIS (Netherlands)

    Smits, E.C.P.; Walter, A.; Leeuw, D.M. de; Asadi, K.

    2017-01-01

    Transfer of graphene and other two-dimensional materials is still a technical challenge. The 2D-materials are typically patterned after transfer, which leads to a major loss of material. Here, we present laser induced forward transfer of chemical vapor deposition grown graphene layers with

  12. Laser induced fluorescence spectroscopy for FTU

    International Nuclear Information System (INIS)

    Hughes, T.P.

    1995-07-01

    Laser induced fluorescence spectroscopy (LIFS) is based on the absorption of a short pulse of tuned laser light by a group of atoms and the observation of the resulting fluorescence radiation from the excited state. Because the excitation is resonant it is very efficient, and the fluorescence can be many times brighter than the normal spontaneous emission, so low number densities of the selected atoms can be detected and measured. Good spatial resolution can be achieved by using a narrow laser beam. If the laser is sufficiently monochromatic, and it can be tuned over the absorption line profile of the selected atoms, information can also be obtained about the velocities of the atoms from the Doppler effect which can broaden and shift the line. In this report two topics are examined in detail. The first is the effect of high laser irradiance, which can cause 'power broadening' of the apparent absorption line profile. The second is the effect of the high magnetic field in FTU. Detailed calculations are given for LIFS of neutral iron and molybdenum atoms, including the Zeeman effect, and the implementation of LIFS for these atoms on FTU is discussed

  13. Nonequilibrium photochemical reactions induced by lasers. Technical progress report

    International Nuclear Information System (INIS)

    Steinfeld, J.I.

    1978-04-01

    Research has progressed in six principal subject areas of interest to DOE advanced (laser) isotope separation efforts. These are (1) Infrared double resonance spectroscopy of molecules excited by multiple infrared photon absorption, particularly SF 6 and vinyl chloride. (2) Infrared multiphoton excitation of metastable triplet-state molecules, e.g., biacetyl. (3) An Information Theory analysis of multiphoton excitation and collisional deactivation has been carried out. (4) The mechanism of infrared energy deposition and multiphoton-induced reactions in chlorinated ethylene derivatives; and RRKM (statistical) model accounts for all observed behavior of the system, and a deuterium-specific reaction pathway has been identified. (5) Diffusion-enhanced laser isotope separation in N 16 O/N 18 O. (6) A technical evaluation of laser-induced chemistry and isotope separation

  14. Analysis of organic vapors with laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nozari, Hadi; Tavassoli, Seyed Hassan [Laser and Plasma Research Institute, Shahid Beheshti University, G. C, 1983963113 Evin, Tehran (Iran, Islamic Republic of); Rezaei, Fatemeh, E-mail: fatemehrezaei@kntu.ac.ir [Department of Physics, K. N. Toosi University of Technology, 15875-4416 Shariati, Tehran (Iran, Islamic Republic of)

    2015-09-15

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  15. Analysis of organic vapors with laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Nozari, Hadi; Tavassoli, Seyed Hassan; Rezaei, Fatemeh

    2015-01-01

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor

  16. LASER INDUCED SELECTIVE ACTIVATION UTILIZING AUTO-CATALYTIC ELECTROLESS PLATING ON POLYMER SURFACE

    DEFF Research Database (Denmark)

    Zhang, Yang; Nielsen, Jakob Skov; Tang, Peter Torben

    2009-01-01

    . Characterization of the deposited copper layer was used to select and improve laser parameters. Several types of polymers with different melting points were used as substrate. Using the above mentioned laser treatment, standard grades of thermoplastic materials such as ABS, SAN, PE, PC and others have been......This paper presents a new method for selective micro metallization of polymers induced by laser. An Nd: YAG laser was employed to draw patterns on polymer surfaces using a special set-up. After subsequent activation and auto-catalytic electroless plating, copper only deposited on the laser tracks....... Induced by the laser, porous and rough structures are formed on the surface, which favours the palladium attachment during the activation step prior to the metallization. Laser focus detection, scanning electron microscopy (SEM) and other instruments were used to analyze the topography of the laser track...

  17. DNA damages induced by Ar F laser

    Energy Technology Data Exchange (ETDEWEB)

    Chapel, C.; Rose, S.; Chevrier, L.; Cordier, E.; Courant, D. [CEA Fontenay-aux-Roses, 92 (France). Dept. de Radiobiologie et de Radiopathologie

    2006-07-01

    The photo ablation process used in corneal refractive surgery by the Argon Fluoride (Ar F) laser emitting in ultraviolet C at 193 nm, exposes viable cells round the irradiated zone to sub ablative doses (< 400 joules.m -2). Despite that DNA absorption is higher at 193 nm than 254 nm, cytotoxicity of 193 nm laser radiation is lower than radiation emitted by 254 nm UV-C lamps. In situ, DNA could be protected of laser radiation by cellular components. Consequently, some authors consider that this radiation does not induce genotoxic effect whereas others suspect it to be mutagenic. These lasers are used for fifteen years but many questions remain concerning the long term effects on adjacent cells to irradiated area. The purpose of this study is to describe the effect of 193 nm laser radiation on DNA of stromal keratocytes which are responsible of the corneal structure. The 193 nm laser irradiation induces directly DNA breakage in keratocytes as it has been shown by the comet assay under alkaline conditions. Two hours post irradiation, damages caused by the highest exposure (150 J.m-2) are not repaired as it has been measured with the Olive Tail Moment (product of tail length and tail DNA content). They give partly evidence of induction of an apoptotic process in cells where DNA could be too damaged. In order to characterize specifically double strand breaks, a comparative analysis by immunofluorescence of the H2 Ax histone phosphorylation (H2 Ax) has been performed on irradiated keratocytes and unirradiated keratocytes. Results show a dose dependent increase of the number of H2 Ax positive cells. Consequences of unrepaired DNA lesions could be observed by the generation of micronuclei in cells. Results show again an increase of micronuclei in laser irradiated cells. Chromosomal aberrations have been pointed out by cytogenetic methods 30 mn after irradiation. These aberrations are dose dependent (from 10 to 150 J.m-2). The number of breakage decreases in the long run

  18. Experimental tests of induced spatial incoherence using short laser wavelength

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Grun, J.; Herbst, M.J.

    1986-01-01

    The authors have developed a laser beam smoothing technique called induced spatial incoherence (ISI), which can produce the highly uniform focal profiles required for direct-drive laser fusion. Uniform well-controlled focal profiles are required to obtain the highly symmetric pellet implosions needed for high-energy gain. In recent experiments, the authors' tested the effects of ISI on high-power laser-target interaction. With short laser wavelength, the coupling physics dramatically improved over that obtained with an ordinary laser beam

  19. UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

    Science.gov (United States)

    Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

    2016-04-01

    Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

  20. IR Laser-Induced Co-decomposition of Dimethyl Selenide and Trisilane: Gas-Phase Formation of SiSe and Chemical Vapor Deposition of Nanostructured H/Si/Se/C Polymers.

    Czech Academy of Sciences Publication Activity Database

    Santos, M.; Díaz, L.; Urbanová, Markéta; Bastl, Zdeněk; Šubrt, Jan; Pola, Josef

    2007-01-01

    Roč. 188, 2-3 (2007) , s. 399-408 ISSN 1010-6030 R&D Projects: GA MŠk(CZ) ME 846 Grant - others:MCyT(ES) BQU2003/08531/C02/02 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : laser deposition * laser-induced polymers * silicon selenide Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.911, year: 2007

  1. Collinear Laser Spectroscopy of Potassium Nuclear Charge Radii beyond N = 28

    CERN Document Server

    AUTHOR|(CDS)2078903; Jochim, Selim

    Nuclear ground-state properties, such as spin, charge radius, and magnetic dipole and electric quadrupole moments are important quantities to describe the nucleus. The comparison of experimental data to shell-model calculations gives insight in the underlying nuclear structure and composition of ground-state wave functions. Spins and charge radii can also be used to test the predictions of state-of-the-art microscopic models. This work contributes to these studies providing new measurements in the region of the nuclear chart around the magic proton number Z = 20. The data have been obtained at the collinear laser spectroscopy setup COLLAPS located at the radioactive-ion-beam facility ISOLDE at CERN. Using bunched-beam laser spectroscopy hyperne structure spectra of the potassium isotopes with mass number A = 48 51 could be recorded for the first time. Ground-state spins and isotope shifts could be deduced for 4851K contributing to the evolution of the d3=2 orbital beyond the shell closure at the magi...

  2. Enhancement of molecular NMR signal induced by polarization transfer from laser-polarized 129Xe

    International Nuclear Information System (INIS)

    Sun Xianping

    2001-01-01

    There is a large non-equilibrium nuclear polarization and a longer relaxation time in the laser-polarized 129 Xe produced by means of optical pumping and spin exchange. The characteristics of the laser-polarized 129 Xe permit the transfer of the polarization to enhance the atomic nuclear spin in liquid, solid and surface of solid molecules. Therefore, the sensitivity in nuclear magnetic resonance measurements for the molecules is enhanced and applications in the investigations of materials and surface sciences are expanded. The progress in the investigations of materials and surface sciences are expanded. The progress in the investigations of the polarization transfer between laser-polarized 129 Xe and the atomic nuclei in the molecules, the relative physics and the measurement of some parameters are introduced

  3. Development of a compact vertical-cavity surface-emitting laser end-pumped actively Q-switched laser for laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo; Chen, Rongzhang; Nelsen, Bryan; Chen, Kevin, E-mail: pec9@pitt.edu [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Liu, Lei; Huang, Xi; Lu, Yongfeng [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

    2016-03-15

    This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications.

  4. Optofluidic lens actuated by laser-induced solutocapillary forces

    Science.gov (United States)

    Malyuk, A. Yu.; Ivanova, N. A.

    2017-06-01

    We demonstrate an adaptive liquid lens controlled by laser-induced solutocapillary forces. The liquid droplet serving as a lens is formed in a thin layer of binary liquid mixture by surface tension driven flows caused by the thermal action of laser irradiation. The shape of droplet, its aperture and the focal length are reversibly changed without hysteresis by varying the intensity of the laser beam. The focal length variation range of the droplet-lens lies in between infinity (a flat layer) to 15 mm (a curved interface). The droplet-lens is capable to adjust the in-plane lateral position in response to a displacement of the laser beam. The proposed laser controlled droplet-lens will enable to develop smart liquid optical devices, which can imitate the accommodation reflex and pupillary light reflex of the eye.

  5. Experimental studies of particle acceleration with ultra-intense lasers - Applications to nuclear physics experiments involving laser-produced plasmas

    International Nuclear Information System (INIS)

    Plaisir, C.

    2010-11-01

    For the last ten years, the Ultra High Intensity Lasers offer the opportunity to produce accelerated particle beams which contain more than 10 12 electrons, protons accelerated into a few ps. We have simulated and developed some diagnostics based on nuclear activation to characterize both the angular and the energy distributions of the particle beams produced with intense lasers. The characterization methods which are presented are illustrated by means of results obtained in different experiments. We would use the particle beams produced to excite nuclear state in a plasma environment. It can modify intrinsic characteristics of the nuclei such as the half-life of some isomeric states. To prepare this kind of experiments, we have measured the nuclear reaction cross section (gamma,n) to produce the isomeric state of the 84 Rb, which has an excitation energy of 463 keV, with the electron accelerator ELSA of CEA/DIF in Bruyeres-le-Chatel (France). (author)

  6. Remote quantitative analysis of minerals based on multispectral line-calibrated laser-induced breakdown spectroscopy (LIBS).

    Science.gov (United States)

    Wan, Xiong; Wang, Peng

    2014-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a feasible remote sensing technique used for mineral analysis in some unapproachable places where in situ probing is needed, such as analysis of radioactive elements in a nuclear leak or the detection of elemental compositions and contents of minerals on planetary and lunar surfaces. Here a compact custom 15 m focus optical component, combining a six times beam expander with a telescope, has been built, with which the laser beam of a 1064 nm Nd ; YAG laser is focused on remote minerals. The excited LIBS signals that reveal the elemental compositions of minerals are collected by another compact single lens-based signal acquisition system. In our remote LIBS investigations, the LIBS spectra of an unknown ore have been detected, from which the metal compositions are obtained. In addition, a multi-spectral line calibration (MSLC) method is proposed for the quantitative analysis of elements. The feasibility of the MSLC and its superiority over a single-wavelength determination have been confirmed by comparison with traditional chemical analysis of the copper content in the ore.

  7. Flow measurement by Laser Doppler Anemometry in a nuclear fuel assembly

    International Nuclear Information System (INIS)

    Kehoe, A.

    1984-12-01

    Development of a Laser Doppler Anemometer measurement system and its operation are examined in this research. The system is designed for flow measurement in laboratory models of nuclear fuel assemblies. Use of the system is demonstrated by measuring turbulent velocity profiles in the laboratory model at full scale reactor flow rates. The reactors at the Savanah River Plant (SRP) are heavy water moderated and operate at low temperatures and pressures. Reactor power is currently limited by the temperature of the water in the nuclear fuel assembly. These temperature limits are conservatively calculated without allowing for any turbulent mixing. This research incorporates the design, fabriction and operation of a plexiglas model fuel assembly for the purpose of making turbulent velocity measurement via a Laser Doppler Anemometer System

  8. Laser-induced multiphoton transitions

    International Nuclear Information System (INIS)

    Stenholm, S.

    1978-06-01

    Laser induced multiphoton processes are reviewed. The effects of strong fields on atoms are discussed. The perturbation treatment is presented and also its generalization to treat intermediate resonances. The influence of atomic coherence is discussed heuristically and the relation between quantal and classical descriptions of the field is elucidated by reference to the dressed atom description. Atomic ionization experiments are reviewed and the present understanding of multiphoton dissociation of molecules is explained. Finally some prospects for the future are discussed. (author)

  9. Laser-filamentation-induced condensation and snow formation in a cloud chamber.

    Science.gov (United States)

    Ju, Jingjing; Liu, Jiansheng; Wang, Cheng; Sun, Haiyi; Wang, Wentao; Ge, Xiaochun; Li, Chuang; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2012-04-01

    Using 1 kHz, 9 mJ femtosecond laser pulses, we demonstrate laser-filamentation-induced spectacular snow formation in a cloud chamber. An intense updraft of warm moist air is generated owing to the continuous heating by the high-repetition filamentation. As it encounters the cold air above, water condensation and large-sized particles spread unevenly across the whole cloud chamber via convection and cyclone like action on a macroscopic scale. This indicates that high-repetition filamentation plays a significant role in macroscopic laser-induced water condensation and snow formation.

  10. Laser-Induced Fluorescence diagnostic of barium ion plasmas in the Paul Trap Simulator Experiment

    International Nuclear Information System (INIS)

    Chung, Moses; Gilson, Erik P.; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.

    2005-01-01

    The Paul Trap Simulator Experiment (PTSX) is a cylindrical Paul trap whose purpose is to simulate the nonlinear dynamics of intense charged particle beam propagation in alternating-gradient magnetic transport systems. To investigate the ion plasma microstate in PTSX, including the ion density profile and the ion velocity distribution function, a laser-induced fluorescence diagnostic system is being developed as a nondestructive diagnostic. Instead of cesium, which has been used in the initial phase of the PTSX experiment, barium has been selected as the preferred ion for the laser-induced fluorescence diagnostic. A feasibility study of the laser-induced fluorescence diagnostic using barium ions is presented with the characterization of a tunable dye laser. The installation of the barium ion source and the development of the laser-induced fluorescence diagnostic system are also discussed

  11. Towards a safety case for the use of laser cutting in nuclear decommissioning

    International Nuclear Information System (INIS)

    Hilton, P.A.

    2014-01-01

    Some of the requirements in nuclear decommissioning include size reduction of contaminated containers, pipework and other structures manufactured from stainless and other steels. Size reduction is generally performed using mechanical saws or shears, with drawbacks of quick wear, significant applied force, difficult remote operation and addition to contaminated waste mass. The use of lasers for cutting within the context of nuclear decommissioning has been recently demonstrated by TWI and others. In this paper, aspects of drawing together a safety case for using laser beams for cutting in a nuclear decommissioning cell are discussed, via analysis of relevant purpose designed experimental data. Data presented includes assessment of the use of different focal length lenses and the power densities anticipated at distances of up to 3 m from the focal point, as well as beam effects on material behind the cutting zone. An assessment of anticipated material damage from stray beams or unintended exposure to laser light of surrounding items is also presented. Finally materials for effective screening against stray beams during the cutting process have been tested for effectiveness. (authors)

  12. Non-destructive visualization of linear explosive-induced Pyroshock using phase arrayed laser-induced shock in a space launcher composite

    International Nuclear Information System (INIS)

    Jang, Jae Kyeong; Lee, Jung Ryul

    2015-01-01

    Separation mechanism of Space launch vehicles are used in various separation systems and pyrotechnic devices. The operation of these pyrotechnic devices generates Pyroshock that can cause failures in electronic components. The prediction of high frequency structural response, especially the shock response spectrum (SRS), is important. This paper presents a non-destructive visualization and simulation of linear explosive-induced Pyroshock using phase arrayed Laser-induced shock. The proposed method includes a laser shock test based on laser beam and filtering zone conditioning to predict the SRS of Pyroshock. A ballistic test based on linear explosive and non-contact Laser Doppler Vibrometers and a nondestructive Laser shock measurement using laser excitation and several PZT sensors, are performed using a carbon composite sandwich panel. The similarity of the SRS of the conditioned laser shock to that of the real explosive Pyroshock is evaluated with the Mean Acceleration Difference. The average of MADs over the two training points was 33.64%. And, MAD at verification point was improved to 31.99%. After that, experimentally found optimal conditions are applied to any arbitrary points in laser scanning area. Finally, it is shown that linear explosive-induced real Pyroshock wave propagation can be visualized with high similarity based on the proposed laser technology. (paper)

  13. Real-time control of ultrafast laser micromachining by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Tong Tao; Li Jinggao; Longtin, Jon P.

    2004-01-01

    Ultrafast laser micromachining provides many advantages for precision micromachining. One challenging problem, however, particularly for multilayer and heterogeneous materials, is how to prevent a given material from being ablated, as ultrafast laser micromachining is generally material insensitive. We present a real-time feedback control system for an ultrafast laser micromachining system based on laser-induced breakdown spectroscopy (LIBS). The characteristics of ultrafast LIBS are reviewed and discussed so as to demonstrate the feasibility of the technique. Comparison methods to identify the material emission patterns are developed, and several of the resulting algorithms were implemented into a real-time computer control system. LIBS-controlled micromachining is demonstrated for the fabrication of microheater structures on thermal sprayed materials. Compared with a strictly passive machining process without any such feedback control, the LIBS-based system provides several advantages including less damage to the substrate layer, reduced machining time, and more-uniform machining features

  14. Laser-Induced Damage with Femtosecond Pulses

    Science.gov (United States)

    Kafka, Kyle R. P.

    The strong electric fields of focused femtosecond laser pulses lead to non-equilibrium dynamics in materials, which, beyond a threshold intensity, causes laser-induced damage (LID). Such a strongly non-linear and non-perturbative process renders important LID observables like fluence and intensity thresholds and damage morphology (crater) extremely difficult to predict quantitatively. However, femtosecond LID carries a high degree of precision, which has been exploited in various micro/nano-machining and surface engineering applications, such as human eye surgery and super-hydrophobic surfaces. This dissertation presents an array of experimental studies which have measured the damage behavior of various materials under femtosecond irradiation. Precision experiments were performed to produce extreme spatio-temporal confinement of the femtosecond laser-solid damage interaction on monocrystalline Cu, which made possible the first successful direct-benchmarking of LID simulation with realistic damage craters. A technique was developed to produce laser-induced periodic surface structures (LIPSS) in a single pulse (typically a multi-pulse phenomenon), and was used to perform a pump-probe study which revealed asynchronous LIPSS formation on copper. Combined with 1-D calculations, this new experimental result suggests more drastic electron heating than expected. Few-cycle pulses were used to study the LID performance and morphology of commercial ultra-broadband optics, which had not been systematically studied before. With extensive surface analysis, various morphologies were observed, including LIPSS, swelling (blisters), simple craters, and even ring-shaped structures, which varied depending on the coating design, number of pulses, and air/vacuum test environment. Mechanisms leading to these morphologies are discussed, many of which are ultrafast in nature. The applied damage behavior of multi-layer dielectric mirrors was measured and compared between long pulse (150 ps

  15. Biological effects of laser-induced stress waves

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  16. Chemical consequences of laser-induced breakdown in molecular gases

    Czech Academy of Sciences Publication Activity Database

    Babánková, Dagmar; Civiš, Svatopluk; Juha, Libor

    2006-01-01

    Roč. 30, č. 2-3 (2006), s. 75-88 ISSN 0079-6727 R&D Projects: GA ČR GA203/06/1278; GA MŠk LC510; GA MŠk LC528; GA MŠk 1P04LA235 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100523 Keywords : laser spark * laser-induced dielectric breakdown * laser-plasma chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.500, year: 2006

  17. Neuroprotective Treatment of Laser-Induced Retinal Injuries

    National Research Council Canada - National Science Library

    Rosner, Mordechai

    2001-01-01

    .... It is not possible to prevent all these injuries and there is no treatment. This study was designed to evaluate the neuroprotective effect of dextromethorphan, memantine and brimonidine in our rat model of laser- induced retinal-lesions Methods...

  18. Study on microstructure and high temperature wear resistance of laser cladded nuclear valve clack

    International Nuclear Information System (INIS)

    Zhang Chunliang; Chen Zichen

    2002-01-01

    Laser cladding of Co-base alloy on the nuclear valve-sealing surface are performed with a 5 kW CO 2 transverse flowing laser. The microstructure and the high temperature impact-slide wear resistance of the laser cladded coating and the plasma cladded coating are studied. The results show that the microstructure, the dilution rate and the high temperature impact-slide wear resistance of the laser cladded coating have obvious advantages over the spurt cladding processing

  19. Nuclear moments and isotopic variation of the mean square charge radii of strontium nuclei by atomic beam laser spectroscopy

    International Nuclear Information System (INIS)

    Chongkum, S.

    1987-10-01

    Hyperfine structure and optical isotope shift measurements have been performed on a series of stable and radioactive strontium isotopes (A = 80 to 90), including two isomers 85m and 87m. The spectroscopy applied continuous wave dye laser induced fluorescence of free atoms at λ=293.2 nm in a well collimated atomic beam. The 293.2 nm ultraviolet light was generated by frequency doubling the output of a dye laser in either a temperature tuned Ammonium Dihydrogen Arsenate (ADA) crystal or an angle tuned Lithium Iodate crystal. A special radio frequency (rf) technique was used to tune the dye laser frequency with long term stability. Radioactive Sr isotopes were produced either by neutron capture of stable strontium or by (α,xn) reactions from krypton gas. The samples were purified by an electromagnetic mass separator and their sizes were of order 100 pg, which corresponds to 10 11 atoms. The observed results of the hyperfine structure components are evaluated in terms of nuclear magnetic dipole moments and electric quadrupole moments. Changes in mean square charge radii of strontium nuclei which were extracted from the isotope shift measurements, exhibit a distinct shell effect at the neutron magic number N=50. The experimental data are analysed and compared with some theoretical nuclear model predictions. The strong increase of the nuclear charge radii with decreasing neutron number of isotopes below N=50 is in agreement with the variation of the mean square deformation extracted from measured B(E2) values. (orig.) [de

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  1. Doping of silicon by laser-induced diffusion

    International Nuclear Information System (INIS)

    Pretorius, R.; Allie, M.S.

    1986-01-01

    This report gives information on the doping of silicon by laser-induced diffusion, modelling and heat-flow calculation, doping from evaporated layers and silicon self-diffusion during pulsed laser irradiation. In order to tailor dopant profiles accurately a knowledge of the heat flow and the melt depths attained as a function of laser energy and material type is crucial. The heat flow calculations described can be used in conjuntion with most diffusion equations in order to predict the redistribution of the deposited dopant which occurs as a result of liquid phase diffusion during the melting period. Doping of Si was carried out by evaporating this films of Sb, In and Bi 10 to 300 A thick, onto the substrates. During pulsed laser irradiation the dopant film and underlying silicon substrate is melted and the dopant incorporated into the crystal lattice during recrystallization. Radioactive 31 Si(T1/2=2,62h) was used as a tracer to measure the self-diffusion of silicon in silicon during pulsed laser (pulsewidth = 30ns, wavelength = 694nm) irradiation

  2. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Winn, J.S.

    1980-10-01

    Laser induced fluoresence (LIF) spectra (laser excitation spectra) are conceptually among the most simple spectra to obtain. One need only confine a gaseous sample in a suitable container, direct a laser along one axis of the container, and monitor the sample's fluorescence at a right angle to the laser beam. As the laser wavelength is changed, the changes in fluorescence intensity map the absorption spectrum of the sample. (More precisely, only absorption to states which have a significant radiative decay component are monitored.) For ion spectroscopy, one could benefit in many ways by such an experiment. Most optical ion spectra have been observed by emission techniques, and, aside from the problems of spectral analysis, discharge emission methods often produce the spectra of many species, some of which may be unknown or uncertain. Implicit in the description of LIF given above is certainty as to the chemical identity of the carrier of the spectrum. This article describes a method by which the simplifying aspects of LIF can be extended to molecular ions

  3. Laser-induced agglomeration of gold nanoparticles dispersed in a liquid

    Energy Technology Data Exchange (ETDEWEB)

    Serkov, A.A.; Shcherbina, M.E. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, Moscow Institute of Physics and Technology (State University), Moscow (Russian Federation); Kuzmin, P.G., E-mail: qzzzma@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Kirichenko, N.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, Moscow Institute of Physics and Technology (State University), Moscow (Russian Federation)

    2015-05-01

    Highlights: • Pulsed laser irradiation of dense gold nanoparticles colloidal solution can result in their agglomeration. • Gas bubbles in-phase pulsation induced by laser radiation accounts for nanoparticles agglomeration. • Time evolution of the size distribution function proceeds in activation mode. • The electrostatic-like model of nanoparticles agglomeration is in good correspondence with the experimental data. - Abstract: Dynamics of gold nanoparticles (NPs) ensemble in dense aqueous solution under exposure to picosecond laser radiation is studied both experimentally and theoretically. Properties of NPs are examined by means of transmission electron microscopy, optical spectroscopy, and size-measuring disk centrifuge. Theoretical investigation of NPs ensemble behavior is based on the analytical model taking into account collisions and agglomeration of particles. It is shown that in case of dense NPs colloidal solutions (above 10{sup 14} particles per milliliter) the process of laser fragmentation typical for nanosecond laser exposure turns into laser-induced agglomeration which leads to formation of the particles with larger sizes. It is shown that there is a critical concentration of NPs: at higher concentrations agglomeration rate increases tremendously. The results of mathematical simulation are in compliance with experimental data.

  4. Analysis of moving surface structures at a laser-induced boiling front

    Energy Technology Data Exchange (ETDEWEB)

    Matti, R.S., E-mail: ramiz.matti@ltu.se [Luleå University of Technology, Department of Engineering Sciences and Mathematics, S-971 87 Luleå (Sweden); University of Mosul, College of Engineering, Department of Mechanical Engineering, Mosul (Iraq); Kaplan, A.F.H. [Luleå University of Technology, Department of Engineering Sciences and Mathematics, S-971 87 Luleå (Sweden)

    2014-10-30

    Highlights: • For laser-induced boiling, molten metal surfaces show a moving wave pattern. • Categorization of seven kinds of shapes enabled systematic pattern analysis. • Bright shapes changed or disappeared, giving evidence for pulsating waves. • Interpretation on the topology and on the basic laser–melt interaction was made. - Abstract: Recently ultra-high speed imaging enabled to observe moving wave patterns on metal melts that experience laser-induced boiling. In laser materials processing a vertical laser-induced boiling front governs processes like keyhole laser welding, laser remote fusion cutting, laser drilling or laser ablation. The observed waves originate from temperature variations that are closely related to the melt topology. For improved understanding of the essential front mechanisms and of the front topology, for the first time a deeper systematic analysis of the wave patterns was carried out. Seven geometrical shapes of bright or dark domains were distinguished and categorized, in particular bright peaks of three kinds and dark valleys, often inclined. Two categories describe special flow patterns at the top and bottom of the front. Dynamic and statistical analysis has revealed that the shapes often combine or separate from one category to another when streaming down the front. The brightness of wave peaks typically fluctuates during 20–50 μs. This variety of thermal wave observations is interpreted with respect to the accompanying surface topology of the melt and in turn for governing local mechanisms like absorption, shadowing, boiling, ablation pressure and melt acceleration. The findings can be of importance for understanding the key process mechanisms and for optimizing laser materials processing.

  5. Analysis of moving surface structures at a laser-induced boiling front

    International Nuclear Information System (INIS)

    Matti, R.S.; Kaplan, A.F.H.

    2014-01-01

    Highlights: • For laser-induced boiling, molten metal surfaces show a moving wave pattern. • Categorization of seven kinds of shapes enabled systematic pattern analysis. • Bright shapes changed or disappeared, giving evidence for pulsating waves. • Interpretation on the topology and on the basic laser–melt interaction was made. - Abstract: Recently ultra-high speed imaging enabled to observe moving wave patterns on metal melts that experience laser-induced boiling. In laser materials processing a vertical laser-induced boiling front governs processes like keyhole laser welding, laser remote fusion cutting, laser drilling or laser ablation. The observed waves originate from temperature variations that are closely related to the melt topology. For improved understanding of the essential front mechanisms and of the front topology, for the first time a deeper systematic analysis of the wave patterns was carried out. Seven geometrical shapes of bright or dark domains were distinguished and categorized, in particular bright peaks of three kinds and dark valleys, often inclined. Two categories describe special flow patterns at the top and bottom of the front. Dynamic and statistical analysis has revealed that the shapes often combine or separate from one category to another when streaming down the front. The brightness of wave peaks typically fluctuates during 20–50 μs. This variety of thermal wave observations is interpreted with respect to the accompanying surface topology of the melt and in turn for governing local mechanisms like absorption, shadowing, boiling, ablation pressure and melt acceleration. The findings can be of importance for understanding the key process mechanisms and for optimizing laser materials processing

  6. Femtosecond laser induced phenomena in transparent solid materials

    DEFF Research Database (Denmark)

    Tan, D.Z.; Sharafudeen, K.N.; Yue, Yuanzheng

    2016-01-01

    solved, especially concerning the interaction of strong, ultra-short electromagnetic pulses with matter, and also because potential advanced technologies will emerge due to the impressive capability of the intense femtosecond laser to create new material structures and hence functionalities. When......The interaction of intense femtosecond laser pulses with transparent materials is a topic that has caused great interest of scientists over the past two decades. It will continue to be a fascinating field in the coming years. This is because many challenging fundamental problems have not been......–matter interaction, and fabricate various integrated micro-devices. In recent years we have witnessed exciting development in understanding and applying femtosecond laser induced phenomena in transparent materials. The interaction of femtosecond laser pulses with transparent materials relies on non...

  7. Correlation between grade of pearlite spheroidization and laser induced spectra

    Science.gov (United States)

    Yao, Shunchun; Dong, Meirong; Lu, Jidong; Li, Jun; Dong, Xuan

    2013-12-01

    Laser induced breakdown spectroscopy (LIBS) which is used traditionally as a spectrochemical analytical technique was employed to analyze the grade of pearlite spheroidization. Three 12Cr1MoV steel specimens with different grades of pearlite spheroidization were ablated to produce plasma by pulse laser at 266 nm. In order to determine the optimal temporal condition and plasma parameters for correlating the grade of pearlite spheroidization and laser induced spectra, a set of spectra at different delays were analyzed by the principal component analysis method. Then, the relationship between plasma temperature, intensity ratios of ionic to atomic lines and grade of pearlite spheroidization was studied. The analysis results show that the laser induced spectra of different grades of pearlite spheroidization can be readily identifiable by principal component analysis in the range of 271.941-289.672 nm with 1000 ns delay time. It is also found that a good agreement exists between the Fe ionic to atomic line ratios and the tensile strength, whereas there is no obvious difference in the plasma temperature. Therefore, LIBS may be applied not only as a spectrochemical analytical technique but also as a new way to estimate the grade of pearlite spheroidization.

  8. Production of photofission fragments and study of their nuclear structure by laser spectroscopy

    International Nuclear Information System (INIS)

    Gangrskij, Yu.P.; Zemlyanoj, S.G.; Karaivanov, D.V.; Marinova, K.P.; Markov, B.N.; Mel'nikova, L.M.; Myshinskij, G.V.; Penionzhkevich, Yu.Eh.; Zhemenik, V.I.

    2005-01-01

    The prospective nuclear structure investigations of the fission fragments by resonance laser spectroscopy methods are discussed. Research in this field is currently being carried out as part of the DRIBs project, which is under development at the Laboratory of Nuclear Reactions, JINR. The fission fragments under study are mainly very neutron-rich nuclei near the proton (Z=50) and neutron (N=50 and 82) closed shells, nuclei in the region of strong deformation (N>60 and N>90) and nuclei with high-spin isomeric states. Resonance laser spectroscopy is used successfully in the study of the structure of such nuclei. It allows one to determine a number of nuclear parameters (mean-square charge radius, magnetic dipole and electric quadrupole moments) and to make conclusions about the collective and single particle properties of the nuclei

  9. Boron- and iron-bearing molecules in laser-induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gaft, M.; Nagli, L.; Eliezer, N.; Groisman, Y.

    2015-08-01

    Boron combines with alkali-earth elements, such as Ca, Mg, and Sr and with oxygen to form molecules in LIP of boron-bearing minerals with strong and characteristic band emission. It may be supposed that those bands are of CaBO{sub 2}, MgBO{sub 2} and SrBO{sub 2} type. Besides, emission of BO, BO{sub 2} and FeO is also detected. - Highlights: • We studied laser-induced breakdown spectra of B with Ca, Mg and Sr in air. • Emission of polyatomic molecules was found. • Molecules of FeO were found in laser-induced plasma in air.

  10. Development of Laser-Induced Fluorescence Diagnostic for the Paul Trap Simulator Experiment

    CERN Document Server

    Chung, Moses; Efthimion, Philip; Gilson, Erik P; Majeski, Richard; Startsev, Edward

    2005-01-01

    The Paul Trap Simulator Experiment (PTSX) is a cylindrical Paul trap whose purpose is to simulate the nonlinear dynamics of intense charged particle beam propagation in alternating-gradient magnetic transport systems. For the in-situ measurement of the transverse ion density profile in the PTSX device, which is essential for the study of beam mismatch and halo particle production, a laser-induced fluorescence diagnostic system is being developed. Instead of cesium, which has been used in the initial phase of the PTSX experiment, barium has been selected as the preferred ion for the laser-induced fluorescence diagnostic. The installation of the barium ion source and the characterization of the tunable dye laser system are discussed. The design of the collection optics with an intensified CCD camera system is also discussed. Finally, initial test results using the laser-induced fluorescence diagnostic will be presented.

  11. Calibration-free laser-induced breakdown spectroscopy for ...

    Indian Academy of Sciences (India)

    journal of. August 2012 physics pp. 299–310. Calibration-free laser-induced ... for quantitative analysis of materials, illustrated by CF-LIBS applied to a ..... The authors are thankful to BRNS, DAE, Govt. of India for the financial support provided.

  12. Laser-induced stabilisation of the tympanic membrane

    Science.gov (United States)

    Schacht, Sophie A. L.; Stahn, Patricia; Hinsberger, Marius; Hoetzer, Benjamin; Schick, Bernhard; Wenzel, Gentiana I.

    2017-07-01

    Repeated pathologies of the tympanic membrane (TM) decrease its tension inducing conductive hearing loss and adhesive processes up to cholesteatoma. Our results regarding the development of a laser based noninvasive procedure to strengthen the structure of the TM are herein presented.

  13. Laser induced fluorescence of trapped molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references.

  14. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references

  15. Laser induced forward transfer of soft materials

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  16. Narrow titanium oxide nanowires induced by femtosecond laser pulses on a titanium surface

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui; Li, Xian-Feng [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Zhang, Cheng-Yun [School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006 (China); Tie, Shao-Long [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Lan, Sheng, E-mail: slan@scnu.edu.cn [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)

    2017-02-28

    Highlights: • Titanium oxide nanowires with a feature width as narrow as ∼20 nm were induced on a titanium surface by using femtosecond laser pulses at 400 nm. • An evolution of the surface structure from a high spatial frequency laser-induced periodic structure parallel to the laser polarization to a low spatial frequency one perpendicular to the laser polarization was observed with increasing irradiation pulse number. • The formation of the titanium oxide nanowires was confirmed by the energy dispersive spectroscopy measurements and the evolution of the surface structure was successfully interpreted by using the efficacy factor theory. - Abstract: The evolution of the nanostructure induced on a titanium (Ti) surface with increasing irradiation pulse number by using a 400-nm femtosecond laser was examined by using scanning electron microscopy. High spatial frequency periodic structures of TiO{sub 2} parallel to the laser polarization were initially observed because of the laser-induced oxidation of the Ti surface and the larger efficacy factor of TiO{sub 2} in this direction. Periodically aligned TiO{sub 2} nanowires with featured width as small as 20 nm were obtained. With increasing pulse number, however, low spatial frequency periodic structures of Ti perpendicular to the laser polarization became dominant because Ti possesses a larger efficacy factor in this direction. The competition between the high- and low-spatial frequency periodic structures is in good agreement with the prediction of the efficacy factor theory and it should also be observed in the femtosecond laser ablation of other metals which are easily oxidized in air.

  17. Local thermodynamic equilibrium considerations in powerchip laser-induced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Merten, Jonathan A., E-mail: jmerten@astate.edu; Smith, Benjamin W., E-mail: bwsmith@chem.ufl.edu; Omenetto, Nicoló, E-mail: omenetto@chem.ufl.edu

    2013-05-01

    Time-resolved emission experiments are reported in the fast-decaying transient plasma induced by a microchip laser on an aluminum target in three different cover gases, i.e., air, argon and helium. The laser operates at 532 nm, with a repetition frequency of 1 kHz and a pulse width of less than 0.5 ns. The overall persistence of plasma emission is of the order of 100 ns. We examine the existence of local thermodynamic equilibrium (LTE) by evaluating the temporal criteria required (in addition to the McWhirter criterion), as recommended by Cristoforetti et al. (Spectrochim. Acta Part B 65, 2010, 86–95). The temporal criteria examine the evolution of temperature and electron number density and compare their rate of change to the rate at which electron collisions can thermalize the change. These considerations are used to determine time windows in which LTE may be present. Our results suggest that calibration-free LIBS measurements with these lasers may be possible for some elements at early times, especially under argon. - Highlights: ► Powerchip laser-induced plasma evolution is affected by cover gas. ► Plasma often out of LTE, despite fulfilling the McWhirter criterion ► Calibration-free LIBS may be possible with powerchip laser plasmas.

  18. Local thermodynamic equilibrium considerations in powerchip laser-induced plasmas

    International Nuclear Information System (INIS)

    Merten, Jonathan A.; Smith, Benjamin W.; Omenetto, Nicoló

    2013-01-01

    Time-resolved emission experiments are reported in the fast-decaying transient plasma induced by a microchip laser on an aluminum target in three different cover gases, i.e., air, argon and helium. The laser operates at 532 nm, with a repetition frequency of 1 kHz and a pulse width of less than 0.5 ns. The overall persistence of plasma emission is of the order of 100 ns. We examine the existence of local thermodynamic equilibrium (LTE) by evaluating the temporal criteria required (in addition to the McWhirter criterion), as recommended by Cristoforetti et al. (Spectrochim. Acta Part B 65, 2010, 86–95). The temporal criteria examine the evolution of temperature and electron number density and compare their rate of change to the rate at which electron collisions can thermalize the change. These considerations are used to determine time windows in which LTE may be present. Our results suggest that calibration-free LIBS measurements with these lasers may be possible for some elements at early times, especially under argon. - Highlights: ► Powerchip laser-induced plasma evolution is affected by cover gas. ► Plasma often out of LTE, despite fulfilling the McWhirter criterion ► Calibration-free LIBS may be possible with powerchip laser plasmas

  19. Enhancement of laser-induced breakdown spectroscopy (LIBS) Detection limit using a low-pressure and short-pulse laser-induced plasma process.

    Science.gov (United States)

    Wang, Zhen Zhen; Deguchi, Yoshihiro; Kuwahara, Masakazu; Yan, Jun Jie; Liu, Ji Ping

    2013-11-01

    Laser-induced breakdown spectroscopy (LIBS) technology is an appealing technique compared with many other types of elemental analysis because of the fast response, high sensitivity, real-time, and noncontact features. One of the challenging targets of LIBS is the enhancement of the detection limit. In this study, the detection limit of gas-phase LIBS analysis has been improved by controlling the pressure and laser pulse width. In order to verify this method, low-pressure gas plasma was induced using nanosecond and picosecond lasers. The method was applied to the detection of Hg. The emission intensity ratio of the Hg atom to NO (IHg/INO) was analyzed to evaluate the LIBS detection limit because the NO emission (interference signal) was formed during the plasma generation and cooling process of N2 and O2 in the air. It was demonstrated that the enhancement of IHg/INO arose by decreasing the pressure to a few kilopascals, and the IHg/INO of the picosecond breakdown was always much higher than that of the nanosecond breakdown at low buffer gas pressure. Enhancement of IHg/INO increased more than 10 times at 700 Pa using picosecond laser with 35 ps pulse width. The detection limit was enhanced to 0.03 ppm (parts per million). We also saw that the spectra from the center and edge parts of plasma showed different features. Comparing the central spectra with the edge spectra, IHg/INO of the edge spectra was higher than that of the central spectra using the picosecond laser breakdown process.

  20. Initiation of nuclear reactions under laser irradiation of Au nanoparticles in the aqueous solution of Uranium salt

    Energy Technology Data Exchange (ETDEWEB)

    Simakin, A.V.; Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow (Russian Federation)

    2010-10-15

    Laser exposure of a suspension of either gold or palladium nanoparticles in aqueous solutions of UO{sub 2}Cl{sub 2} of natural isotope abundance was experimentally studied. Picosecond Nd:YAG lasers at peak power of 10{sup 11}-10{sup 13} W/cm{sup 2} at the wavelength of 1.06-0.355 {mu}m were used as well as a visible-range Cu vapor laser at a peak power of 10{sup 10} W/cm{sup 2}. The composition of colloidal solutions before and after laser exposure was analyzed using atomic absorption and gamma spectroscopy in the 0.06-1 MeV range of photon energy. Real-time gamma spectroscopy was used to characterize the kinetics of nuclear reactions during laser exposure. It was found that laser exposure initiated nuclear reactions involving both {sup 238}U and {sup 235}U nuclei via different channels in H{sub 2}O and D{sub 2}O. The influence of saturation of both the liquid and nanoparticles by gaseous H{sub 2} and D{sub 2} on the kinetics of nuclear transformations was found. Possible mechanisms of observed processes are discussed. (orig.)

  1. Laser-Induced Breakdown Spectroscopy Infrared Emission From Inorganic and Organic Substances

    National Research Council Canada - National Science Library

    Yang, C.S; Brown, E; Hommerich, U; Trivedi, S. B; Snyder, A. P; Samuels, A. C

    2006-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been established as a powerful method for identifying trace elemental contaminants by analyzing the atomic spectral emission lines that result subsequent to plasmas generated by laser power...

  2. Laser induced structural transformation in chalcogenide based superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Zallo, Eugenio, E-mail: zallo@pdi-berlin.de; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2016-05-30

    Superlattices made of alternating layers of nominal GeTe and Sb{sub 2}Te{sub 3} have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  3. Laser induced structural transformation in chalcogenide based superlattices

    International Nuclear Information System (INIS)

    Zallo, Eugenio; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella

    2016-01-01

    Superlattices made of alternating layers of nominal GeTe and Sb 2 Te 3 have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  4. Laser-induced mobilization of dust produced during fusion reactors operation

    International Nuclear Information System (INIS)

    Vatry, A.

    2010-01-01

    During tokamak operation, plasma-wall interactions lead to material erosion process and dusts production. These dusts are mainly composed by carbon and tungsten, with sizes ranging from 10 nm to 100 μm. For safety reasons and to guarantee an optimum reactor functioning, the dusts have to be kept in reasonable quantity. The dusts mobilization is a first step to collect them, and the laser is a promising technique for this application. To optimize the cleaning, physical mechanisms responsible for dust ejection induced by laser have been identified. Some particles, such as aggregates, are directly ablated by the laser. The metal droplets are ejected intact by an electrostatic force, induced by the photoelectrons. We also characterized the particles ejection to choose an appropriate collection device. (author) [fr

  5. Induced nuclear beta decay

    International Nuclear Information System (INIS)

    Reiss, H.R.

    1986-01-01

    Certain nuclear beta decay transitions normally inhibited by angular momentum or parity considerations can be induced to occur by the application of an electromagnetic field. Such decays can be useful in the controlled production of power, and in fission waste disposal

  6. Cascade generation in Al laser induced plasma

    Science.gov (United States)

    Nagli, Lev; Gaft, Michael; Raichlin, Yosef; Gornushkin, Igor

    2018-05-01

    We found cascade IR generation in Al laser induced plasma. This generation includes doublet transitions 3s 25s 2S1/2 → 3s24p 2P1/2,3/2 → 3s24s 2S1/2; corresponding to strong lines at 2110 and 2117 nm, and much weaker lines at 1312-1315 nm. The 3s25s2S 1/2 starting IR generation level is directly pumped from the 3s23p 2P3/2 ground level. The starting level for UV generation at 396.2 nm (transitions 3s24s 2S1/2 → 4p 2P3/2) is populated due to the fast collisional processes in the plasma plume. These differences led to different time and special dependences on the lasing in the IR and UV spectral range within the aluminum laser induced plasma.

  7. Laser ablation of liquid surface in air induced by laser irradiation through liquid medium

    Science.gov (United States)

    Utsunomiya, Yuji; Kajiwara, Takashi; Nishiyama, Takashi; Nagayama, Kunihito; Kubota, Shiro; Nakahara, Motonao

    2010-10-01

    The pulse laser ablation of a liquid surface in air when induced by laser irradiation through a liquid medium has been experimentally investigated. A supersonic liquid jet is observed at the liquid-air interface. The liquid surface layer is driven by a plasma plume that is produced by laser ablation at the layer, resulting in a liquid jet. This phenomenon occurs only when an Nd:YAG laser pulse (wavelength: 1064 nm) is focused from the liquid onto air at a low fluence of 20 J/cm2. In this case, as Fresnel’s law shows, the incident and reflected electric fields near the liquid surface layer are superposed constructively. In contrast, when the incident laser is focused from air onto the liquid, a liquid jet is produced only at an extremely high fluence, several times larger than that in the former case. The similarities and differences in the liquid jets and atomization processes are studied for several liquid samples, including water, ethanol, and vacuum oil. The laser ablation of the liquid surface is found to depend on the incident laser energy and laser fluence. A pulse laser light source and high-resolution film are required to observe the detailed structure of a liquid jet.

  8. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  9. Packaging-induced failure of semiconductor lasers and optical telecommunications components

    Energy Technology Data Exchange (ETDEWEB)

    Sharps, J.A. [Corning Inc., NY (United States)

    1996-12-31

    Telecommunications equipment for field deployment generally have specified lifetimes of > 100,000 hr. To achieve this high reliability, it is common practice to package sensitive components in hermetic, inert gas environments. The intent is to protect components from particulate and organic contamination, oxidation, and moisture. However, for high power density 980 nm diode lasers used in optical amplifiers, the authors found that hermetic, inert gas packaging induced a failure mode not observed in similar, unpackaged lasers. They refer to this failure mode as packaging-induced failure, or PIF. PIF is caused by nanomole amounts of organic contamination which interact with high intensity 980 nm light to form solid deposits over the emitting regions of the lasers. These deposits absorb 980 nm light, causing heating of the laser, narrowing of the band gap, and eventual thermal runaway. The authors have found PIF is averted by packaging with free O{sub 2} and/or a getter material that sequesters organics.

  10. CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification.

    Science.gov (United States)

    Baccou, C; Yahia, V; Depierreux, S; Neuville, C; Goyon, C; Consoli, F; De Angelis, R; Ducret, J E; Boutoux, G; Rafelski, J; Labaune, C

    2015-08-01

    Laser-accelerated ion beams can be used in many applications and, especially, to initiate nuclear reactions out of thermal equilibrium. We have experimentally studied aneutronic fusion reactions induced by protons accelerated by the Target Normal Sheath Acceleration mechanism, colliding with a boron target. Such experiments require a rigorous method to identify the reaction products (alpha particles) collected in detectors among a few other ion species such as protons or carbon ions, for example. CR-39 track detectors are widely used because they are mostly sensitive to ions and their efficiency is near 100%. We present a complete calibration of CR-39 track detector for protons, alpha particles, and carbon ions. We give measurements of their track diameters for energy ranging from hundreds of keV to a few MeV and for etching times between 1 and 8 h. We used these results to identify alpha particles in our experiments on proton-boron fusion reactions initiated by laser-accelerated protons. We show that their number clearly increases when the boron fuel is preformed in a plasma state.

  11. Overview of applications of Laser-Induced Breakdown Spectroscopy (LIBS)

    International Nuclear Information System (INIS)

    Cremers, D.A.

    1987-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a method of performing elemental analyses of solids, liquids, and gases using the microplasma produced by a focused laser pulse. Because the microplasma is formed by optical radiation, LIBS has some important advantages compared to conventional laboratory based analytical methods. Three applications are discussed which use the LIBS method. 6 refs., 8 figs., 2 tabs

  12. Laser-induced field-free alignment of the OCS molecule

    International Nuclear Information System (INIS)

    Loriot, V; Tzallas, P; Benis, E P; Hertz, E; Lavorel, B; Charalambidis, D; Faucher, O

    2007-01-01

    We investigate the dynamical alignment of jet-cooled OCS molecules induced by a short laser pulse. The alignment is measured through the orientational contribution of the optical Kerr effect using a second weak laser pulse as a probe. Maximum alignment is observed at conditions close to saturation of ionization. The results are analysed with a quantum mechanical model solving for the rotational dynamics

  13. Laser induced florescence: application to spectroscopy and new microscopy imaging methods

    International Nuclear Information System (INIS)

    Galaup, L. P.

    2012-01-01

    Laser induced fluorescence is one of the light using techniques which allows the highest sensitivity for atoms and molecules detection, up to the single atom or single molecule level. This field is much too large for an extensive review; therefor we have chosen to focus on two main points: 1- the observation of laser stimulated fluorescence in phthalocyanine and porphyrin like molecules in rare gas and nitrogen matrices at low temperatures. 2- the presentation of laser induced fluorescence techniques suitable for achieving ultra-high spatial resolution imaging, below the diffraction limit of conventional microscopy, thanks to highly fluorescent molecules to be used as biological markers. (Author)

  14. In-source laser spectroscopy of polonium isotopes: From atomic physics to nuclear structure

    CERN Multimedia

    Rothe, S

    2014-01-01

    The Resonance Ionization Laser Ion Source RILIS [1] at the CERN-ISOLDE on-line radioactive ion beam facility is essential for ion beam production for the majority of experiments, but it is also powerful tool for laser spectroscopy of rare isotopes. A series of experiments on in-source laser spectroscopy of polonium isotopes [2, 3] revealed the nuclear ground state properties of 191;211;216;218Po. However, limitations caused by the isobaric background of surface-ionized francium isotopes hindered the study of several neutron rich polonium isotopes. The development of the Laser Ion Source and Trap (LIST) [4] and finally its integration at ISOLDE has led to a dramatic suppression of surface ions. Meanwhile, the RILIS laser spectroscopy capabilities have advanced tremendously. Widely tunable titanium:sapphire (Ti:Sa) lasers were installed to complement the established dye laser system. Along with a new data acquisition system [5], this more versatile laser setup enabled rst ever laser spectroscopy of the radioact...

  15. Induced-Fission Imaging of Nuclear Material

    International Nuclear Information System (INIS)

    Hausladen, Paul; Blackston, Matthew A.; Mullens, James Allen; McConchie, Seth M.; Mihalczo, John T.; Bingham, Philip R.; Ericson, Milton Nance; Fabris, Lorenzo

    2010-01-01

    This paper presents initial results from development of the induced-fission imaging technique, which can be used for the purpose of measuring or verifying the distribution of fissionable material in an unopened container. The technique is based on stimulating fissions in nuclear material with 14 MeV neutrons from an associated-particle deuterium-tritium (D-T) generator and counting the subsequent induced fast fission neutrons with an array of fast organic scintillation detectors. For each source neutron incident on the container, the neutron creation time and initial trajectory are known from detection of the associated alpha particle of the d + t → α + n reaction. Many induced fissions will lie along (or near) the interrogating neutron path, allowing an image of the spatial distribution of prompt induced fissions, and thereby fissionable material, to be constructed. A variety of induced-fission imaging measurements have been performed at Oak Ridge National Laboratory with a portable, low-dose D-T generator, including single-view radiographic measurements and three-dimensional tomographic measurements. Results from these measurements will be presented along with the neutron transmission images that have been performed simultaneously. This new capability may have applications to a number of areas in which there may be a need to confirm the presence or configuration of nuclear materials, such as nuclear material control and accountability, quality assurance, treaty confirmation, or homeland security applications.

  16. Remote sensing vegetation status by laser-induced fluorescence

    International Nuclear Information System (INIS)

    Günther, K.P.; Dahn, H.G.; Lüdeker, W.

    1994-01-01

    In November 1989 the EUREKA project LASFLEUR (EU 380) started as an European research effort to investigate the future application of far-field laser-induced plant fluorescence for synoptic, airborne environmental monitoring of vegetation. This report includes a brief introduction in a theoretically approach for the laser-induced fluorescence signals of leaves and their spectral and radiometric behaviour. In addition, a detailed description of the design and realization of the second generation of the far-field fluorescence lidar (DLidaR-2) is given with special regard to the optical and electronical setup, followed by a short explanation of the data processing. The main objectives of the far field measurements are to demonstrate the link between laser-induced fluorescence data and plant physiology and to show the reliability of remote single shot lidar measurements. The data sets include the typical daily cycles of the fluorescence for different global irradiation. As expected from biophysical models, the remotely sensed chlorophyll fluorescence is highly correlated with the carbon fixation rate, while the fluorescence ratio F685 / F730 is only dependent on the chlorophyll concentration. Drought stress measurement of evergreen oaks Quercus pubescens confirm the findings of healthy plants with regard to the fluorescence ratio F685 / F730 while the fluorescence signals of stressed plants show a different behavior than nonstressed plants. Additionally, the corresponding physiological data (porometer and PAM data) are presented. (author)

  17. Analysis of laser-induced heating in optical neuronal guidance

    DEFF Research Database (Denmark)

    Ebbesen, Christian L.; Bruus, Henrik

    2012-01-01

    Recently, it has been shown that it is possible to control the growth direction of neuronal growth cones by stimulation with weak laser light; an effect dubbed optical neuronal guidance. The effect exists for a broad range of laser wavelengths, spot sizes, spot intensities, optical intensity...... profiles and beam modulations, but it is unknown which biophysical mechanisms govern it. Based on thermodynamic modeling and simulation using published experimental parameters as input, we argue that the guidance is linked to heating. Until now, temperature effects due to laser-induced heating...

  18. Correlation between grade of pearlite spheroidization and laser induced spectra

    International Nuclear Information System (INIS)

    Yao, Shunchun; Dong, Meirong; Lu, Jidong; Li, Jun; Dong, Xuan

    2013-01-01

    Laser induced breakdown spectroscopy (LIBS) which is used traditionally as a spectrochemical analytical technique was employed to analyze the grade of pearlite spheroidization. Three 12Cr1MoV steel specimens with different grades of pearlite spheroidization were ablated to produce plasma by pulse laser at 266 nm. In order to determine the optimal temporal condition and plasma parameters for correlating the grade of pearlite spheroidization and laser induced spectra, a set of spectra at different delays were analyzed by the principal component analysis method. Then, the relationship between plasma temperature, intensity ratios of ionic to atomic lines and grade of pearlite spheroidization was studied. The analysis results show that the laser induced spectra of different grades of pearlite spheroidization can be readily identifiable by principal component analysis in the range of 271.941–289.672 nm with 1000 ns delay time. It is also found that a good agreement exists between the Fe ionic to atomic line ratios and the tensile strength, whereas there is no obvious difference in the plasma temperature. Therefore, LIBS may be applied not only as a spectrochemical analytical technique but also as a new way to estimate the grade of pearlite spheroidization. (paper)

  19. Morphological changes in skin tumors caused by pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Moskalik, K G; Lipova, V A; Neyshtadt, E L

    1979-01-01

    Morphological changes induced by treating melanomas, basaloma and flatcell skin cancers with a pulsed neodymium laser at 1060 nm, pulse length 1 msec and energy 250 to 500 J/cm/sup 2/, were studied using impressions and scrapings from the affected area. Nuclear pyknosis, nuclear and cellular elongation, vacuolization, frequent complete loss of cytoplasm, particulaly in the zone of direct irradiation, and loss of cellular structure were seen. These dystrophic changes increased with closeness to the zone of direct irradiation, culminating in necrosis. Formed and decomposed blood elements and melanin accumulated in the intracellular spaces, due to disruption of capillaries and small arteries and veins. Fewer and more aggregated melanoblasts were found after melanoma irradiation. Nuclear chromatin fusion, cytoplasmic changes and altered cell shape were observed. Basaloma cells were clustered and elongated after irradiation, with many fibrous structures and loss of cellular elements. Cytoplasmic vacuolization and lysis, bare nuclei, karyolysis, karyorrhexis and karyopyknosis were seen in corneous flat-cell cancer. In the few cases in which malignant cells were found under the scab from the first treatment the procedure was repeated. The morphological changes induced by pulsed laser irradiation are very similar to electrocoagulation necrosis, but are more localized. The ability of low and middle energy lasers to induce thrombosis and coagulation in vascular walls reduced the probability of hematogenic tumor cell dissemination. Cytological examination is highly effective in determining the degree of radical skin cancer healing due to laser treatment. 12 references, 2 figures.

  20. Use of laser ablation in nuclear decontamination

    International Nuclear Information System (INIS)

    Moggia, Fabrice; Lecardonnel, Xavier; Damerval, Frederique

    2012-09-01

    The development and the use of clean decontamination process appear to be one of the main priorities for industries especially for nuclear industries. This is especially due to the fact of wastes minimization which is one of the principal commitments. One answer would be to use a photonic process such as the LASER process. The principle of this process is based on the absorption, by the contaminant, of the photon's energy. This energy then will propagate into the material and create some mechanical waves responsible of the interfaces embrittlement and de-cohesion. As we can see, this process so called LASER ablation does not use any chemicals and allows us to avoid any production of liquid waste. Since now a couple of years, the Clean-Up Business Unit of AREVA group (BE/CL) investigates this new decontamination technology. Many tests have been done in inactive conditions on various simulants such as paints, inks, resins, metallic oxides firstly in order to estimate its efficiency but also to fully qualify it. After that, we decided to move on hot tests to fully validate this new process and to show its interest for the nuclear industry. Those hot tests have been done on two kinds of contaminated material (on tank pieces covered with a thick metallic oxide layer and on metallic pieces covered with grease). Some information such as Scanning Electron Microscopy (SEM), X-Ray scattering spectroscopy and decontamination factors (DF) will be provided in this paper. (authors)

  1. Formation of laser-induced periodic surface structures on niobium by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Pan, A.; Dias, A.; Gomez-Aranzadi, M.; Olaizola, S. M.; Rodriguez, A.

    2014-01-01

    The surface morphology of a Niobium sample, irradiated in air by a femtosecond laser with a wavelength of 800 nm and pulse duration of 100 fs, was examined. The period of the micro/nanostructures, parallel and perpendicularly oriented to the linearly polarized fs-laser beam, was studied by means of 2D Fast Fourier Transform analysis. The observed Laser-Induced Periodic Surface Structures (LIPSS) were classified as Low Spatial Frequency LIPSS (periods about 600 nm) and High Spatial Frequency LIPSS, showing a periodicity around 300 nm, both of them perpendicularly oriented to the polarization of the incident laser wave. Moreover, parallel high spatial frequency LIPSS were observed with periods around 100 nm located at the peripheral areas of the laser fingerprint and overwritten on the perpendicular periodic gratings. The results indicate that this method of micro/nanostructuring allows controlling the Niobium grating period by the number of pulses applied, so the scan speed and not the fluence is the key parameter of control. A discussion on the mechanism of the surface topology evolution was also introduced

  2. Formation of laser-induced periodic surface structures on niobium by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pan, A.; Dias, A.; Gomez-Aranzadi, M.; Olaizola, S. M. [CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón (Spain); CEIT-IK4 and Tecnun, University of Navarra, Manuel Lardizábal 15, 20018 San Sebastián (Spain); Rodriguez, A. [CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón (Spain)

    2014-05-07

    The surface morphology of a Niobium sample, irradiated in air by a femtosecond laser with a wavelength of 800 nm and pulse duration of 100 fs, was examined. The period of the micro/nanostructures, parallel and perpendicularly oriented to the linearly polarized fs-laser beam, was studied by means of 2D Fast Fourier Transform analysis. The observed Laser-Induced Periodic Surface Structures (LIPSS) were classified as Low Spatial Frequency LIPSS (periods about 600 nm) and High Spatial Frequency LIPSS, showing a periodicity around 300 nm, both of them perpendicularly oriented to the polarization of the incident laser wave. Moreover, parallel high spatial frequency LIPSS were observed with periods around 100 nm located at the peripheral areas of the laser fingerprint and overwritten on the perpendicular periodic gratings. The results indicate that this method of micro/nanostructuring allows controlling the Niobium grating period by the number of pulses applied, so the scan speed and not the fluence is the key parameter of control. A discussion on the mechanism of the surface topology evolution was also introduced.

  3. Development of a Laser Induced Fluorescence (LIF) System with a Tunable Diode Laser

    International Nuclear Information System (INIS)

    Woo, Hyun Jong; Do, Jeong Jun; You, Hyun Jong; Choi, Geun Sik; Lee, Myoung Jae; Chung, Kyu Sun

    2005-01-01

    The Laser Induced Fluorescence (LIF) is known as one of the most powerful techniques for measurements of ion velocity distribution function (IVDF) and ion temperature by means of Doppler broadening and Doppler shift. The dye lasers are generally used for LIF system with 611.66 nm (in vac.) for Ar ion, the low power diode laser was also proposed by Severn et al with the wavelength of 664.55 nm and 668.61 nm (in vac.) for Ar ion. Although the diode laser has the disadvantages of low power and small tuning range, it can be used for LIF system at the low temperature plasmas. A tunable diode laser with 668.614 nm of center wavelength and 10 GHz mode hop free tuning region has been used for our LIF system and it can be measured the ion temperature is up to 1 eV. The ion temperature and velocity distribution function have been measured with LaB6 plasma source, which is about 0.23 eV with Ar gas and 2.2 mTorr working pressure

  4. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  5. Structure changes in steels and hard metal induced by nanosecond and femtosecond laser processing

    Science.gov (United States)

    Dumitru, Gabriel; Romano, Valerio; Weber, Heinz P.; Haefke, Henry; Gerbig, Yvonne; Sentis, Marc L.; Hermann, Joerg; Bruneau, Sebastien

    2003-11-01

    Investigations on the occurrence of structure and hardness changes (for two sorts of steel and for a hard metal substrate) in the immediate vicinity of laser induced craters are presented in this work. Experiments with femtosecond pulses were performed in air with a Ti:sapphire laser (800 nm, 100 fs) at mean fluences of 2, 5 and 10 J/cm2. Series of microcraters were induced with 100 to 5,000 laser pulses per hole. Experiments with similar fluences, but 10 to 40 pules per hole, were performed on the same materials using a Nd:YAG delivering 100 ns pulese. After laser irradiation, cuts were made through the processed samples and the changes occurred in the crystalline structure of the target materials were evidenced by metallographical analysis of the resulting cross-sections. Hardness measurements were performed in points situated in the immediate vicinity of the laser-induced pores. Affected zones in the material surrounding laser induced pores were always found in the ns-regime, however with different properties for various laser parameters. In the fs-regime, zones of modified materials were also found and in such zones a significant hardness increasing was evidenced; the limit of the low fluences regime, where no structure changes occurred, was found to be slightly above 2 J/cm2.

  6. Amorphous-polycrystal transition induced by laser pulse in self-ion implanted silicon

    International Nuclear Information System (INIS)

    Foti, G.; Rimini, E.; Vitali, G.; Bertolotti, M.

    1977-01-01

    Reflection high energy electron diffraction has been used to investigate the amorphous to polycrystalline structure transition in silicon induced by laser pulse. The power density of the ruby laser pulse, in the free generation mode, has been maintained below the threshold to induce surface damage. Depth analysis has been carried out in silicon crystal using the channeling effect technique. (orig.) [de

  7. Novel nuclear laser spectroscopy method using superfluid helium for measurement of spins and moments of exotic nuclei

    International Nuclear Information System (INIS)

    Furukawa, Takeshi; Wakui, Takashi; Yang, Xiaofei; Fujita, Tomomi; Imamura, Kei; Yamaguchi, Yasuhiro; Tetsuka, Hiroki; Tsutsui, Yoshiki; Mitsuya, Yosuke; Ichikawa, Yuichi; Ishibashi, Yoko; Yoshida, Naoki; Shirai, Hazuki; Ebara, Yuta; Hayasaka, Miki; Arai, Shino; Muramoto, Sosuke

    2013-01-01

    Highlights: • Development of a novel nuclear laser spectroscopy method using superfluid helium. • Observation of the Zeeman resonance with the 85 Rb beam introduced into helium. • Demonstration of deducing the nuclear spins from the observed resonance spectrum. -- Abstract: We have been developing a novel nuclear laser spectroscopy method “OROCHI” for determining spins and moments of exotic radioisotopes. In this method, we use superfluid helium as a stopping material of energetic radioisotope beams and then stopped radioisotope atoms are subjected to in situ laser spectroscopy in superfluid helium. To confirm the feasibility of this method for rare radioisotopes, we carried out a test experiment using a 85 Rb beam. In this experiment, we have successfully measured the Zeeman resonance signals from the 85 Rb atoms stopped in superfluid helium by laser-RF double resonance spectroscopy. This method is efficient for the measurement of spins and moments of more exotic nuclei

  8. Applications of ultra-short pulsed laser ablation: thin films deposition and fs/ns dual-pulse laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Teghil, R; De Bonis, A; Galasso, A; Santagata, A; Albano, G; Villani, P; Spera, D; Parisi, G P

    2008-01-01

    In this paper, we report a survey of two of the large number of possible practical applications of the laser ablation performed by an ultra-short pulse laser, namely pulsed laser deposition (PLD) and fs/ns dual-pulse laser-induced breakdown spectroscopy (DP-LIBS). These applications differ from those using just longer pulsed lasers as a consequence of the distinctive characteristics of the plasma produced by ultra-short laser beams. The most important feature of this plasma is the large presence of particles with nanometric size which plays a fundamental role in both applications.

  9. Activation cross-section data for -particle-induced nuclear reactions ...

    Indian Academy of Sciences (India)

    B M ALI

    2018-02-20

    particle-induced nuclear reactions on natural vanadium up to 20 MeV. It should be mentioned that this study represents a part of (a supplement) systematical study of charged particles-induced nuclear reactions. Earlier studies were.

  10. Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule; Impact de l'environnement sur l'endommagement laser des optiques de silice du Laser MegaJoule

    Energy Technology Data Exchange (ETDEWEB)

    Bien-Aime, K.

    2009-11-15

    Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm{sup 2}, a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

  11. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

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

    1996-10-01

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

  12. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    International Nuclear Information System (INIS)

    Camacho-Lopez, Santiago; Evans, Rodger; Escobar-Alarcon, Luis; Camacho-Lopez, Miguel A.; Camacho-Lopez, Marco A.

    2008-01-01

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO 2 in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance

  13. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, Santiago [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico)], E-mail: camachol@cicese.mx; Evans, Rodger [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico); Escobar-Alarcon, Luis [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Miguel A. [Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n, esq. Jesus Carranza, Toluca, Estado de Mexico 50120 (Mexico); Camacho-Lopez, Marco A. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Tollocan s/n, esq. Paseo Colon, Toluca, Estado de Mexico, 50110 (Mexico)

    2008-12-30

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO{sub 2} in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance.

  14. Dynamics of laser-induced magnetization in Ce-doped yttrium aluminum garnet

    International Nuclear Information System (INIS)

    Kolesov, Roman

    2007-01-01

    Circularly polarized short laser pulse induces nonequilibrium population of spin levels in the excited state of Ce 3+ -ion embedded in yttrium aluminium garnet crystal and, consequently, the magnetization of the crystal associated with spin polarization. Dynamic behavior of laser-induced magnetization is studied as a function of the external magnetic field. It reveals spin oscillations attributed to the effect of hyperfine magnetic field produced by 27 Al nuclei on the Ce 3+ spin. A simple theoretical model explaining spin oscillations is presented. It shows that circularly polarized light induces spin coherence at the transition between Zeeman sublevels of Ce 3+ ion in the lowest 5d state. Temporal shape of laser-induced magnetization signal reveals the following parameters of this state: (1) the spin-lattice relaxation constant is ≅2x10 7 s -1 , (2) inhomogeneous spin dephasing time is ≅4 ns, and (3) the g tensor of the state seems to be isotropic with the g factor being in the range 0.7-0.9. In addition, the width of the local hyperfine field distribution is ≅40 G

  15. [Study on physical deviation factors on laser induced breakdown spectroscopy measurement].

    Science.gov (United States)

    Wan, Xiong; Wang, Peng; Wang, Qi; Zhang, Qing; Zhang, Zhi-Min; Zhang, Hua-Ming

    2013-10-01

    In order to eliminate the deviation between the measured LIBS spectral line and the standard LIBS spectral line, and improve the accuracy of elements measurement, a research of physical deviation factors in laser induced breakdown spectroscopy technology was proposed. Under the same experimental conditions, the relationship of ablated hole effect and spectral wavelength was tested, the Stark broadening data of Mg plasma laser induced breakdown spectroscopy with sampling time-delay from 1.00 to 3.00 micros was also studied, thus the physical deviation influences such as ablated hole effect and Stark broadening could be obtained while collecting the spectrum. The results and the method of the research and analysis can also be applied to other laser induced breakdown spectroscopy experiment system, which is of great significance to improve the accuracy of LIBS elements measuring and is also important to the research on the optimum sampling time-delay of LIBS.

  16. Laser-Induced Breakdown Spectroscopy for Qualitative Analysis of Metals in Simulated Martian Soils

    Science.gov (United States)

    Mowry, Curtis; Milofsky, Rob; Collins, William; Pimentel, Adam S.

    2017-01-01

    This laboratory introduces students to laser-induced breakdown spectroscopy (LIBS) for the analysis of metals in soil and rock samples. LIBS employs a laser-initiated spark to induce electronic excitation of metal atoms. Ensuing atomic emission allows for qualitative and semiquantitative analysis. The students use LIBS to analyze a series of…

  17. CO2 laser photo-induced decomposition of ammoniated ammonium ions

    International Nuclear Information System (INIS)

    Ikezoe, Yasumasa; Soga, Takesi; Suzuki, Kazuya; Moriyama, Noboru; Ohno, Shin-ichi

    1995-01-01

    Photo-induced decomposition of ammoniated (clustered) ammonium ions was studied using a CO 2 laser to excite vibrational levels of the cluster ion. A tandem mass spectrometer (TMS) was installed with two quadrupole mass filters, a corona discharge ionization chamber, and a series of einzel lenses. Cluster ions of NH 4 + ·nNH 3 with n=1-7 were formed in TMS, and found to decompose at the frequency of 1077 cm -1 to an extent in proportional to laser intensity. CO 2 laser between 925 and 1055 do not decompose the cluster ions with laser intensities examined. (author)

  18. Laser-induced fluorescence imaging of bacteria

    Science.gov (United States)

    Hilton, Peter J.

    1998-12-01

    This paper outlines a method for optically detecting bacteria on various backgrounds, such as meat, by imaging their laser induced auto-fluorescence response. This method can potentially operate in real-time, which is many times faster than current bacterial detection methods, which require culturing of bacterial samples. This paper describes the imaging technique employed whereby a laser spot is scanned across an object while capturing, filtering, and digitizing the returned light. Preliminary results of the bacterial auto-fluorescence are reported and plans for future research are discussed. The results to date are encouraging with six of the eight bacterial strains investigated exhibiting auto-fluorescence when excited at 488 nm. Discrimination of these bacterial strains against red meat is shown and techniques for reducing background fluorescence discussed.

  19. Single-Shot, Volumetrically Illuminated, Three-Dimensional, Tomographic Laser-Induced-Fluorescence Imaging in a Gaseous Free Jet

    Science.gov (United States)

    2016-04-28

    Single-shot, volumetrically illuminated, three- dimensional, tomographic laser-induced- fluorescence imaging in a gaseous free jet Benjamin R. Halls...acquisition; (110.6955) Tomographic imaging ; (110.6960) Tomography; (280.2490) Flow diagnostics; (300.2530) Fluorescence , laser-induced...84 (1983). 2. I. van Cruyningen, A. Lozano, and R. K. Hanson, “Quantitative imaging of concentration by planar laser-induced fluorescence ,” Exp

  20. Laser-induced fluorescence of oral mucosa cancer

    Science.gov (United States)

    Jaliashvili, Z. V.; Medoidze, T. D.; Melikishvili, Z. G.; Gogilashvili, K. T.

    2017-10-01

    The laser-induced fluorescence (LIF) spectra have been measured for cancer-infused and control mice mucosa tissues. It was established that there is quite a difference between their LIF spectral shapes. These spectral shapes are used to express the diagnostic of different states of tissues: from normal to cancer.

  1. Laser-induced breakdown ignition in a gas fed two-stroke engine

    Science.gov (United States)

    Loktionov, E. Y.; Pasechnikov, N. A.; Telekh, V. D.

    2018-01-01

    Laser-induced ignition for internal combustion engines is investigated intensively after demonstration of a compact ‘laser plug’ possibility. Laser spark benefits as compared to traditional spark plugs are higher compression rate, and possibility of almost any fuel ignition, so lean mixtures burning with lower temperatures could reduce harmful exhausts (NO x , CH, etc). No need in electrode and possibility for multi-point, linear or circular ignition can make combustion even more effective. Laser induced combustion wave appears faster and is more stable in time, than electric one, so can be used for ramjets, chemical thrusters, and gas turbines. To the best of our knowledge, we have performed laser spark ignition of a gas fed two-stroke engine for the first time. Combustion temperature and pressure, exhaust composition, ignition timing were investigated at laser and compared to a regular electric spark ignition in a two-stroke model engine. Presented results show possibility for improvement of two-stroke engines performance, in terms of rotation rate increase and NO x emission reduction. Such compact engines using locally mined fuel could be highly demanded in remote Arctic areas.

  2. Charge radii and moments of tin nuclei by laser spectroscopy

    International Nuclear Information System (INIS)

    Anselment, M.; Bekk, K.; Hanser, A.; Hoeffgen, H.; Meisel, G.; Goering, S.; Rebel, H.; Schatz, G.

    1986-04-01

    The isotope shift and hyperfine structure of the optical Sn I resonance transition 5p 2 3 P 0 ->5p6s 3 P 1 at lambda=286.3 nm have been studied for 18 Sn nuclei including 2 isomers. Laser induced resonance fluorescence from a collimated atomic beam of tin was observed using a tunable cw dye laser with frequency doubler. The electromagnetic nuclear moments and changes of the mean square charge radii of the nuclear charge distributions were determined. The results are discussed with respect to the information they provide on the nuclear structure of the nuclei investigated; they are compared with various theoretical models. (orig.) [de

  3. Spectroscopic analysis of femtosecond laser-induced gas breakdown

    International Nuclear Information System (INIS)

    Hermann, J.; Bruneau, S.; Sentis, M.

    2004-01-01

    The plasma generated by the interaction of a femtosecond laser pulse with gas has been analyzed using time- and space-resolved emission spectroscopy. The laser beam has been focused with a microscope objective into different gases (air, Ar, He) at pressures ranging from 10 2 to 10 5 Pa. From the analysis of spectral line emission from ions and neutral atoms, the plasma parameters and the plasma composition have been determined as a function of time and space. Furthermore, the generation of fast electrons and/or VUV radiation by the femtosecond laser interaction with the gas was brought to the fore. From the time- and space-evolution of the plasma parameters, a rough estimation of initial values of electron density and refraction index in the focal volume has been performed. These results are compared to analysis of the laser beam transmitted by the plasma. The latter show that only a small fraction of the laser energy is absorbed by the plasma while the spatial distribution of the transmitted laser beam is strongly perturbed by the plasma, which acts like a defocusing lens. However, in ambient helium, the plasma defocusing is weak due to the high ionization potential of helium. The understanding of femtosecond laser-induced gas breakdown is useful for process optimization in femtosecond laser applications like micromachining or surface microanalysis, etc

  4. Roll-to-Roll Nanoforming of Metals Using Laser-Induced Superplasticity.

    Science.gov (United States)

    Goswami, Debkalpa; Munera, Juan C; Pal, Aniket; Sadri, Behnam; Scarpetti, Caio Lui P G; Martinez, Ramses V

    2018-05-24

    This Letter describes a low-cost, scalable nanomanufacturing process that enables the continuous forming of thin metallic layers with nanoscale accuracy using roll-to-roll, laser-induced superplasticity (R2RLIS). R2RLIS uses a laser shock to induce the ultrahigh-strain-rate deformation of metallic films at room temperature into low-cost polymeric nanomolds, independently of the original grain size of the metal. This simple and inexpensive nanoforming method does not require access to cleanrooms and associated facilities, and can be easily implemented on conventional CO 2 lasers, enabling laser systems commonly used for rapid prototyping or industrial cutting and engraving to fabricate uniform and three-dimensional crystalline metallic nanostructures over large areas. Tuning the laser power during the R2RLIS process enables the control of the aspect ratio and the mechanical and optical properties of the fabricated nanostructures. This roll-to-roll technique successfully fabricates mechanically strengthened gold plasmonic nanostructures with aspect ratios as high as 5 that exhibit high oxidation resistance and strong optical field enhancements. The CO 2 laser used in R2RLIS can also integrate the fabricated nanostructures on transparent flexible substrates with robust interfacial contact. The ability to fabricate ultrasmooth metallic nanostructures using roll-to-roll manufacturing enables the large scale production, at a relatively low-cost, of flexible plasmonic devices toward emerging applications.

  5. UV laser induced photochemistry of nitrobenzene and nitrotoluene isomers

    International Nuclear Information System (INIS)

    Kosmidis, C.; Clark, A.; Deas, R.M.; Ledingham, K.W.D.; Marshall, A.; Singhal, R.P.

    1995-01-01

    The photofragmentation of nitrobenzene and the isomers of nitrotoluene in the gas phase are studied in the wavelength region 210-270 nm using a pulsed UV laser in conjunction with a time of flight mass spectrometer. Laser induced mass spectra are analysed and compared with those produced by the electron impact (EI) technique. The generation of the observed fragment ions is explained by invoking different fragmentation pathways followed by these molecules. Observed differences in the mass spectra of the o-, m-, and p-nitrotoluene isomers are discussed as a possible way for a laser based method for their identification. (author)

  6. Instantaneous temperature field measurements using planar laser-induced fluorescence.

    Science.gov (United States)

    Seitzman, J M; Kychakoff, G; Hanson, R K

    1985-09-01

    A single-pulse, laser-induced-fluorescence diagnostic for the measurement of two-dimensional temperature fields in combustion flows is described. The method uses sheet illumination from a tunable laser to excite planar laserinduced fluorescence in a stable tracer molecule, seeded at constant mole fraction into the flow field. The temporal resolution of this technique is determined by the laser pulse length. Experimental results are presented for a rodstabilized, premixed methane-air flame, using the Q(1) (22) line of the nitric oxide A(2) Sigma(+) (v = 0) ? X(2)II((1/2))(v = 0) transition (lambda approximately 225.6 nm).

  7. Strengthening of the nuclear valve sealing surface by laser cladding technology

    International Nuclear Information System (INIS)

    Shi Shihong; Huang Guodong

    1998-07-01

    A 5 kW laser with CO 2 flow transverse for cladding Co-base alloy or Ni-base alloy coat on the austenite matrix of the nuclear valve sealing surface is introduced. The results show that, after the sealing surface of valve is processed by the laser cladding, the coat of 3.0 mm thick can be made with smooth surface. The test and comparison analysis indicate that the structure and all performance have obvious advantages over that of the plasma spurt welding, bead welding and flame welding processing

  8. Time-resolved laser-induced fluorescence system

    Science.gov (United States)

    Bautista, F. J.; De la Rosa, J.; Gallegos, F. J.

    2006-02-01

    Fluorescence methods are being used increasingly in the measurement of species concentrations in gases, liquids and solids. Laser induced fluorescence is spontaneous emission from atoms or molecules that have been excited by laser radiation. Here we present a time resolved fluorescence instrument that consists of a 5 μJ Nitrogen laser (337.1 nm), a sample holder, a quartz optical fiber, a spectrometer, a PMT and a PC that allows the measurement of visible fluorescence spectra (350-750 nm). Time response of the system is approximately 5 ns. The instrument has been used in the measurement of colored bond paper, antifreeze, diesel, cochineal pigment and malignant tissues. The data acquisition was achieved through computer control of a digital oscilloscope (using General Purpose Interface Bus GPIB) and the spectrometer via serial (RS232). The instrument software provides a graphic interface that lets make some data acquisition tasks like finding fluorescence spectra, and fluorescence lifetimes. The software was developed using the Lab-View 6i graphic programming package and can be easily managed in order to add more functions to it.

  9. Standoff laser-induced thermal emission of explosives

    Science.gov (United States)

    Galán-Freyle, Nataly Y.; Pacheco-Londoño, Leonardo C.; Figueroa-Navedo, Amanda; Hernandez-Rivera, Samuel P.

    2013-05-01

    A laser mediated methodology for remote thermal excitation of analytes followed by standoff IR detection is proposed. The goal of this study was to determine the feasibility of using laser induced thermal emission (LITE) from vibrationally excited explosives residues deposited on surfaces to detect explosives remotely. Telescope based FT-IR spectral measurements were carried out to examine substrates containing trace amounts of threat compounds used in explosive devices. The highly energetic materials (HEM) used were PETN, TATP, RDX, TNT, DNT and ammonium nitrate with concentrations from 5 to 200 μg/cm2. Target substrates of various thicknesses were remotely heated using a high power CO2 laser, and their mid-infrared (MIR) thermally stimulated emission spectra were recorded. The telescope was configured from reflective optical elements in order to minimize emission losses in the MIR frequencies and to provide optimum overall performance. Spectral replicas were acquired at a distance of 4 m with an FT-IR interferometer at 4 cm- 1 resolution and 10 scans. Laser power was varied from 4-36 W at radiation exposure times of 10, 20, 30 and 60 s. CO2 laser powers were adjusted to improve the detection and identification of the HEM samples. The advantages of increasing the thermal emission were easily observed in the results. Signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration), as well as the laser power and laser exposure time. For samples of RDX and PETN, varying the power and time of induction of the laser, the calculated low limit of detections were 2 and 1 μg/cm2, respectively.

  10. Laser-induced selective copper plating of polypropylene surface

    Science.gov (United States)

    Ratautas, K.; Gedvilas, M.; Stankevičiene, I.; JagminienÄ--, A.; Norkus, E.; Li Pira, N.; Sinopoli, S.; Emanuele, U.; Račiukaitis, G.

    2016-03-01

    Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

  11. New power lasers

    International Nuclear Information System (INIS)

    Yamanaka, Masanobu; Daido, Hiroyuki; Imasaki, Kazuo.

    1989-01-01

    As the new power lasers which are expected to exert large extending effect to the fields of advanced science and technology including precision engineering as well as laser nuclear fusion, LD-excited solid laser, X-ray laser and free electron laser are taken up and outlined. Recently, the solid laser using high power output, high efficiency semiconductor laser as the exciting beam source has been developed. This is called laser diode (LD)-excited solid laser, and the heightening of power output and efficiency and the extension of life are planned. Its present status and application to medical use, laser machining, laser soldering and so on are described. In 1960, the laser in visible region appeared, however in 1985, the result of observing induced emission beam by electron collision exciting method was reported in USA. In the wavelength range of 200 A, holography and contact X-ray microscope applications were verified. The various types of soft X-ray laser and the perspective hereafter are shown. The principle of free electron laser is explained. In the free electron laser, wavelength can be changed by varying electron beam energy, the period of wiggler magnetic field and the intensity of magnetic field. Further, high efficiency and large power output are possible. Its present status, application and the perspective hereafter are reported. (K.I.)

  12. Application of CO2 laser beam weld for repair of fuel element of nuclear reactor 'YAYOI'

    International Nuclear Information System (INIS)

    Hashimoto, Mitsuo; Yanagi, Hideharu; Sukegawa, Toshio; Saito, Isao; Sasuga, Norihiko; Aizawa, Nagaaki; Miya, Kenzo

    1986-01-01

    The present studies are to develop CO 2 laser beam welding techniques in order to apply for repoint of nuclear reactor fuel of Fast Neutron Source Reactor YAYOI. For that purpos, many experiments were conduted to obtain various effects of laser welding variables with use of SUS 304 plates, pipes and simulated dumy fuels. These experiments provided us an optimal welding condition through metallurgical observations, non-destructive and mechanical tests. It was found that the laser welds exhibited properties equivalent to those of the base metal, in addition they provided us a favorable system than that of electron beam welds against a cladding of radioactive nuclear fuel in a hot cell. The present paper reports on the characteristics of laser welds, structural analysis of fuel element and a system design of remotely operated devices setting in a hot cell. (author)

  13. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    International Nuclear Information System (INIS)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-01-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  14. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haisu [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Heraklion 71110 (Greece); Tzortzakis, Stelios, E-mail: stzortz@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Heraklion 71110 (Greece); Materials Science and Technology Department, University of Crete, 71003 Heraklion (Greece); Science Program, Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar)

    2016-05-23

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  15. Laser induced fluorescence of some plant leaves

    International Nuclear Information System (INIS)

    Helmi, M.S.; Mohamed, M.M.; Amer, R.; Elshazly, O.; Elraey, M.

    1992-01-01

    Laser induced fluorescence (LIF) is successfully used as a technique for remote detection of spectral characteristics of some plants. A pulsed nitrogen laser at 337.1 nm is used to excite cotton, corn and rice leaves. The fluorescence spectrum is detected in the range from 340 nm to 820 nm. It is found that, these plant leaves have common fluorescence maxima at 440 nm, 685 nm and 740 nm. plant leaves are also found to be identifiable by the ratio of the fluorescence intensity at 440 nm to that at 685 nm. The present technique can be further used as a means of assessing, remotely, plant stresses. 5 fig

  16. Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

    Science.gov (United States)

    Varela, J. A.; Amado, J. M.; Tobar, M. J.; Mateo, M. P.; Yañez, A.; Nicolas, G.

    2015-05-01

    Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

  17. Method and apparatus for induced nuclear beta decay

    International Nuclear Information System (INIS)

    Reiss, H.

    1986-01-01

    This invention relates to a method and apparatus for inducing beta decay transition that are normally inhibited by angular momentum or parity considerations. According to one aspect of this invention a method of inducing nuclear beta decay transition comprises providing a medium which includes atomic nuclei that have forbidden beta decay transition in which the initial and final nuclear states do not have the same intrinsic parity or have total angular momenta which differ by more than one quantum unit of angular momentum, and applying to the medium an electromagnetic field which has an intensity sufficient to provide the angular momentum or intrinsic parity necessary to overcome the forbiddenness of the beta decay transition of the atomic nuclei, thereby to induce the beta decay transitions. According to another aspect of this invention an apparatus for inducing beta decay transition comprises a medium which includes atomic nuclei that have forbidden beta decay transitions in which the initial and final nuclear states do not have the same intrinsic parity or have total angular momenta which differ by more than one quantum unit of angular momentum, field producing means for producing an electromagnetic field in the medium and means for energising the field producing means to establish the field at an intensity sufficient to provide the angular momentum or intrinsic parity necessary to overcome the forbiddenness of the beta decay transitions of the atomic nuclei. The energy released in these induced nuclear transition is useful for the controlled production of power. The induced beta dacay transitions are also useful to reduce the halflives of long-lived fission product wastes from conventional nuclear fission power plants

  18. Laser-induced forward transfer of hybrid carbon nanostructures

    International Nuclear Information System (INIS)

    Palla-Papavlu, A.; Filipescu, M.; Vizireanu, S.; Vogt, L.; Antohe, S.; Dinescu, M.; Wokaun, A.; Lippert, T.

    2016-01-01

    Highlights: • Rapid prototyping of carbon nanowalls (CNW) and functionalized CNWs is described. • CNW and CNW:SnO_2 pixels are successfully printed by laser-induced forward transfer. • Flexible (polyimide) and rigid (glass) supports are used as substrates. • 4 μm thick CNW and CNW:SnO_2 pixels maintain their morphology and structure after LIFT. - Abstract: Chemically functionalized carbon nanowalls (CNWs) are promising materials for a wide range of applications, i.e. gas sensors, membranes for fuel cells, or as supports for catalysts. However, the difficulty of manipulation of these materials hinders their integration into devices. In this manuscript a procedure for rapid prototyping of CNWs and functionalized CNWs (i.e. decorated with SnO_2 nanoparticles) is described. This procedure enables the use of laser-induced forward transfer (LIFT) as a powerful technique for printing CNWs and CNW:SnO_2 pixels onto rigid and flexible substrates. A morphological study shows that for a large range of laser fluences i.e. 500–700 mJ/cm"2 it is possible to transfer thick (4 μm) CNW and CNW:SnO_2 pixels. Micro-Raman investigation of the transferred pixels reveals that the chemical composition of the CNWs and functionalized CNWs does not change as a result of the laser transfer. Following these results one can envision that CNWs and CNW:SnO_2 pixels obtained by LIFT can be ultimately applied in technological applications.

  19. A versatile interaction chamber for laser-based spectroscopic applications, with the emphasis on Laser-Induced Breakdown Spectroscopy

    International Nuclear Information System (INIS)

    Novotný, J.; Brada, M.; Petrilak, M.; Prochazka, D.; Novotný, K.; Hrdička, A.; Kaiser, J.

    2014-01-01

    The technical note describes the interaction chamber developed particularly for the laser spectroscopy technique applications, such as Laser-Induced Breakdown Spectroscopy (LIBS), Raman Spectroscopy and Laser-Induced Fluorescence. The chamber was designed in order to provide advanced possibilities for the research in mentioned fields and to facilitate routine research procedures. Parameters and the main benefits of the chamber are described, such as the built-in module for automatic 2D chemical mapping and the possibility to set different ambient gas conditions (pressure value and gas type). Together with the chamber description, selected LIBS application examples benefiting from chamber properties are described. - Highlights: • Development of the interaction chamber for LIBS applications • Example of automated chemical mapping of lead in a chalcopyrite sample • Example of LIBS measurement of fluorine in underpressure • Overview of chamber benefits

  20. Study on the ablation threshold induced by pulsed lasers at different wavelengths

    International Nuclear Information System (INIS)

    Torrisi, L.; Borrielli, A.; Margarone, D.

    2007-01-01

    A study of the effects induced by pulsed laser ablation on different materials as a function of the laser wavelength is presented. In particular the ablation at low laser fluence, of the order of 10 8 -10 10 W/cm 2 with ns pulse width, is investigated experimentally on different metals, semiconductors and polymers. Two theoretical models, explain the experimental results about the fluence threshold value measurements, as depending on the laser wavelength are discussed. The photothermal process is valid for the estimation of the threshold fluence for IR and visible radiation, both inducing thermal heating in metals and semiconductors through the photon-free electron energy transfer. This model is not valid for polymers. The photochemical process is valid for the estimation of the threshold fluence for UV radiation, which photon energy is higher with respect to the chemical binding energy. This radiation induces chemical bond breaking in insulators and scission and cross linking effects can be produced. This last model is not valid for metals and semiconductors

  1. Implementing New Methods of Laser Marking of Items in the Nuclear Material Control and Accountability System at SSC RF-IPPE: An Automated Laser Marking System

    International Nuclear Information System (INIS)

    Regoushevsky, V.I.; Tambovtsev, S.D.; Dvukhsherstnov, V.G.; Efimenko, V.F.; Ilyantsev, A.I.; Russ, G.P. III

    2009-01-01

    For over ten years SSC RF-IPPE, together with the US DOE National Laboratories, has been working on implementing automated control and accountability methods for nuclear materials and other items. Initial efforts to use adhesive bar codes or ones printed (painted) onto metal revealed that these methods were inconvenient and lacked durability under operational conditions. For NM disk applications in critical stands, there is the additional requirement that labels not affect the neutron characteristics of the critical assembly. This is particularly true for the many stainless-steel clad disks containing highly enriched uranium (HEU) and plutonium that are used at SSC RF-IPPE for modeling nuclear power reactors. In search of an alternate method for labeling these disks, we tested several technological options, including laser marking and two-dimensional codes. As a result, the method of laser coloring was chosen in combination with Data Matrix ECC200 symbology. To implement laser marking procedures for the HEU disks and meet all the nuclear material (NM) handling standards and rules, IPPE staff, with U.S. technical and financial support, implemented an automated laser marking system; there are also specially developed procedures for NM movements during laser marking. For the laser marking station, a Zenith 10F system by Telesis Technologies (10 watt Ytterbium Fiber Laser and Merlin software) is used. The presentation includes a flowchart for the automated system and a list of specially developed procedures with comments. Among other things, approaches are discussed for human-factor considerations. To date, markings have been applied to numerous steel-clad HEU disks, and the work continues. In the future this method is expected to be applied to other MC and A items.

  2. Nanosecond laser-induced back side wet etching of fused silica with a copper-based absorber liquid

    Science.gov (United States)

    Lorenz, Pierre; Zehnder, Sarah; Ehrhardt, Martin; Frost, Frank; Zimmer, Klaus; Schwaller, Patrick

    2014-03-01

    Cost-efficient machining of dielectric surfaces with high-precision and low-roughness for industrial applications is still challenging if using laser-patterning processes. Laser induced back side wet etching (LIBWE) using UV laser pulses with liquid heavy metals or aromatic hydrocarbons as absorber allows the fabrication of well-defined, nm precise, free-form surfaces with low surface roughness, e.g., needed for optical applications. The copper-sulphatebased absorber CuSO4/K-Na-Tartrate/NaOH/formaldehyde in water is used for laser-induced deposition of copper. If this absorber can also be used as precursor for laser-induced ablation, promising industrial applications combining surface structuring and deposition within the same setup could be possible. The etching results applying a KrF excimer (248 nm, 25 ns) and a Nd:YAG (1064 nm, 20 ns) laser are compared. The topography of the etched surfaces were analyzed by scanning electron microscopy (SEM), white light interferometry (WLI) as well as laser scanning microscopy (LSM). The chemical composition of the irradiated surface was studied by energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). For the discussion of the etching mechanism the laser-induced heating was simulated with finite element method (FEM). The results indicate that the UV and IR radiation allows micro structuring of fused silica with the copper-based absorber where the etching process can be explained by the laser-induced formation of a copper-based absorber layer.

  3. Instantaneous nonvertical electronic transitions with shaped femtosecond laser pulses: Is it possible?

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Møller, Klaus Braagaard

    2003-01-01

    In molecular electronic transitions, a vertical transition can be induced by an ultrashort laser pulse. That is, a replica of the initial nuclear state-times the transition dipole moment of the electronic transition-can be created instantaneously (on the time scale of nuclear motion) in the excited...

  4. Study on the effects of ion motion on laser-induced plasma wakes

    International Nuclear Information System (INIS)

    Zhou Suyun; Yu Wei; Yuan Xiao; Xu Han; Cao, L. H.; Cai, H. B.; Zhou, C. T.

    2012-01-01

    A 2D analytical model is presented for the generation of plasma wakes (or bubbles) with an ultra-intense laser pulse by taking into account the response of plasma ions. It is shown that the effect of ion motion becomes significant at the laser intensity exceeding 10 21 W/cm 2 and plasma background density below 10 19 cm −3 . In this regime, ion motion tends to suppress the electrostatic field induced by charge separation and makes the electron acceleration less effective. As a result, the assumption of immobile ions overestimates the efficiency of laser wake-field acceleration of electrons. Based on the analytical model, the dynamics of plasma ions in laser-induced wake field is investigated. It is found that only one bubble appears as the plasmas background density exceeds the resonant density and the deposited laser energy is concentrated into the bubble, resulting in the generation of an ion bunch with extremely high energy density.

  5. Laser-induced thermoelectric voltage in normal state MgB2 thin films

    International Nuclear Information System (INIS)

    Zhao Songqing; Zhou Yueliang; Zhao Kun; Wang Shufang; Chen Zhenghao; Jin Kuijuan; Lue Huibin; Cheng Bolin; Yang Guozhen

    2006-01-01

    Laser-induced voltage has been observed in c-axis oriented MgB 2 thin film at room temperature. The amplitude of the signal is approximately proportional to the film thickness. For the film with the thickness of 150 nm, a very fast response has been detected when the film was irradiated by a 308 nm pulsed laser of 20 ns duration. The rise time and full width at half-maximum of the signal are about 3 and 25 ns, respectively. The physical origin of the laser-induced voltage can be attributed to a transverse thermoelectricity due to the anisotropic thermopower in MgB 2

  6. Laser induced focusing for over-dense plasma beams

    International Nuclear Information System (INIS)

    Schmidt, Peter; Boine-Frankenheim, Oliver; Mulser, Peter

    2015-01-01

    The capability of ion acceleration with high power, pulsed lasers has become an active field of research in the past years. In this context, the radiation pressure acceleration (RPA) mechanism has been the topic of numerous theoretical and experimental publications. Within that mechanism, a high power, pulsed laser beam hits a thin film target. In contrast to the target normal sheath acceleration, the entire film target is accelerated as a bulk by the radiation pressure of the laser. Simulations predict heavy ion beams with kinetic energy up to GeV, as well as solid body densities. However, there are several effects which limit the efficiency of the RPA: On the one hand, the Rayleigh-Taylor-instability limits the predicted density. On the other hand, conventional accelerator elements, such as magnetic focusing devices are too bulky to be installed right after the target. Therefore, we present a new beam transport method, suitable for RPA-like/over-dense plasma beams: laser induced focusing

  7. Laser induced uranium fluorescence as an analytical method

    International Nuclear Information System (INIS)

    Krutman, I.

    1985-01-01

    A laser induced fluorescence system was developed to measure uranium trace level amounts in aqueous solution with reliable and simple materials and electronics. A nitrogen pulsed laser was built with the storage energy capacitor directly coupled to laser tube electrodes as a transmission line device. This laser operated at 3Hz repetition rate with peak intensity around 21 Kw and temporal width of 4.5 x 10 -9 s. A sample compartment made of rigid PVC and a photomultiplier housing of aluminium were constructed and assembled forming a single integrated device. As a result of this prototype system we made several analytical measurements with U dissolved in nitric acid to obtain a calibration curve. We obtained a straight line from a plot of U concentration versus fluorescence intensity fitted by a least square method that produced a regression coefficient of 0.994. The lower limit of U determination was 30 ppb -+ 3.5%. (Author) [pt

  8. Determination of uranium concentration in an ore sample using laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Kim, Y.-S.; Han, B.-Y.; Shin, H.S.; Kim, H.D.; Jung, E.C.; Jung, J.H.; Na, S.H.

    2012-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been recognized as a promising technique for analyzing sensitive nuclear materials such as uranium, plutonium, and curium in a high-radiation environment, especially since the implementation of IAEA (International Atomic Energy Agency) safeguards. The uranium spectra of ore samples were quantitatively analyzed prior to analyzing sensitive materials in the nuclear industry. The purpose of this experiment is to extract quantitative information about the uranium in a uranium ore using a standard addition approach. The uranium ore samples containing different concentrations of U were prepared by mixing raw ore powder with natural uranium oxide powders. Calibration sets of 0.2, 0.4, 0.6, 0.8 and 1.0 wt.% uranium concentrations within the uranium ore sample were achieved. A pulsed and Q-switched Nd:YAG laser at a wavelength of 532 nm was used as a light source. An echelle spectrometer that covers a 190–420 nm wavelength range is used to generate a calibration curve and determine the detection limit of uranium in the ore matrix. The neutral atomic-emission peak at a wavelength of 356.659 nm indicated a detection limit of ∼ 158 ppm for uranium, and the uranium concentration was determined in a raw ore sample that has an unknown quantity of uranium. - Highlights: ► The feasibility of LIBS application to monitor uranium element was carried out. ► The detection limit of U in ore was determined by a standard additional approach. ► Quantitative analyses of U concentration in a natural uranium ore were performed.

  9. Laser-induced breakdown spectroscopy measurement of a small fraction of rhenium in bulk tungsten

    Science.gov (United States)

    Nishijima, D.; Ueda, Y.; Doerner, R. P.; Baldwin, M. J.; Ibano, K.

    2018-03-01

    Laser-induced breakdown spectroscopy (LIBS) of bulk rhenium (Re) and tungsten (W)-Re alloy has been performed using a Q-switched Nd:YAG laser (wavelength = 1064 nm, pulse width ∼4-6 ns, laser energy = 115 mJ). It is found that the electron temperature, Te, of laser-induced Re plasma is lower than that of W plasma, and that Te of W-Re plasma is in between Re and W plasmas. This indicates that material properties affect Te in a laser-induced plasma. For analysis of W-3.3%Re alloy, only the strongest visible Re I 488.9 nm line is found to be used because of the strong enough intensity without contamination with W lines. Using the calibration-free LIBS method, the atomic fraction of Re, cRe, is evaluated as a function of the ambient Ar gas pressure, PAr. At PAr 10 Torr due to spectral overlapping of the Re I 488.9 nm line by an Ar II 488.9 nm line.

  10. Osteoid Osteoma: Experience with Laser- and Radiofrequency-Induced Ablation

    International Nuclear Information System (INIS)

    Gebauer, Bernhard; Tunn, Per-Ulf; Gaffke, Gunnar; Melcher, Ingo; Felix, Roland; Stroszczynski, Christian

    2006-01-01

    The purpose of this study was to analyze the clinical outcome of osteoid osteoma treated by thermal ablation after drill opening. A total of 17 patients and 20 procedures were included. All patients had typical clinical features (age, pain) and a typical radiograph showing a nidus. In 5 cases, additional histological specimens were acquired. After drill opening of the osteoid osteoma nidus, 12 thermal ablations were induced by laser interstitial thermal therapy (LITT) (9F Power-Laser-Set; Somatex, Germany) and 8 ablations by radiofrequency ablation (RFA) (RITA; StarBurst, USA). Initial clinical success with pain relief has been achieved in all patients after the first ablation. Three patients had an osteoid osteoma recurrence after 3, 9, and 10 months and were successfully re-treated by thermal ablation. No major complication and one minor complication (sensible defect) were recorded. Thermal ablation is a safe and minimally invasive therapy option for osteoid osteoma. Although the groups are too small for a comparative analysis, we determined no difference between laser- and radiofrequency-induced ablation in clinical outcome after ablation

  11. Laser-induced plasma spectrometry: truly a surface analytical tool

    International Nuclear Information System (INIS)

    Vadillo, Jose M.; Laserna, J.

    2004-01-01

    For a long period, analytical applications of laser induced plasma spectrometry (LIPS) have been mainly restricted to overall and quantitative determination of elemental composition in bulk, solid samples. However, introduction of new compact and reliable solid state lasers and technological development in multidimensional intensified detectors have made possible the seeking of new analytical niches for LIPS where its analytical advantages (direct sampling from any material irrespective of its conductive status without sample preparation and with sensitivity adequate for many elements in different matrices) could be fully exploited. In this sense, the field of surface analysis could take advantage from the cited advantages taking into account in addition, the capability of LIPS for spot analysis, line scan, depth-profiling, area analysis and compositional mapping with a single instrument in air at atmospheric pressure. This review paper outlines the fundamental principles of laser-induced plasma emission relevant to sample surface studies, discusses the experimental parameters governing the spatial (lateral and in-depth) resolution in LIPS analysis and presents the applications concerning surface examination

  12. Gas laser spectrometer for nuclear investigation at nucleonic stability limit. (project)

    International Nuclear Information System (INIS)

    Myshinskij, G.V.

    1989-01-01

    It is proposed to obtain the atomic beam of the proton-rich and neutron-rich nuclides with half-lives of up to 1 ms, by using the gas-jet technique. Subsequently their properties are investigated using the methods of laser resonance ionization and nuclear spectroscopy. 8 refs.; 4 figs

  13. Diode-Laser Induced Fluorescence Spectroscopy of an Optically Thick Plasma in Combination with Laser Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    S. Nomura

    2013-01-01

    Full Text Available Distortion of laser-induced fluorescence profiles attributable to optical absorption and saturation broadening was corrected in combination with laser absorption spectroscopy in argon plasma flow. At high probe-laser intensity, saturated absorption profiles were measured to correct probe-laser absorption. At low laser intensity, nonsaturated absorption profiles were measured to correct fluorescence reabsorption. Saturation broadening at the measurement point was corrected using a ratio of saturated to non-saturated broadening. Observed LIF broadening and corresponding translational temperature without correction were, respectively, 2.20±0.05 GHz and 2510±100 K and corrected broadening and temperature were, respectively, 1.96±0.07 GHz and 1990±150 K. Although this correction is applicable only at the center of symmetry, the deduced temperature agreed well with that obtained by LAS with Abel inversion.

  14. High spatial resolution in laser-induced breakdown spectroscopy of expanding plasmas

    International Nuclear Information System (INIS)

    Siegel, J.; Epurescu, G.; Perea, A.; Gordillo-Vazquez, F.J.; Gonzalo, J.; Afonso, C.N.

    2005-01-01

    We report a technique that is able to achieve high spatial resolution in the measurement of the temporal and spectral emission characteristics of laser-induced expanding plasmas. The plasma is imaged directly onto the slit of an imaging spectrograph coupled to a time-gated intensified camera, with the plasma expansion direction being parallel to the slit extension. In this way, a single hybrid detection system is used to acquire the spatial, spectral and temporal characteristics of the laser induced plasma. The parallel acquisition approach of this technique ensures a much better spatial resolution in the expansion direction, reproducibility and data acquisition speed than commonly obtained by sequential measurements at different distances from the target. We have applied this technique to study the laser-induced plasma in LiNbO 3 and Bi 12 Ge 1 O 20 , revealing phenomena not seen in such detail with standard instruments. These include extreme line broadening up to a few nanometers accompanied by self-absorption near the target surface, as well as different ablation and expansion dynamics for the different species ejected. Overall, the high precision and wealth of quantitative information accessible with this technique open up new possibilities for the study of fundamental plasma expansion processes during pulsed laser ablation

  15. Laser optical pumping of sodium and lithium atom beams

    International Nuclear Information System (INIS)

    Cusma, J.T.

    1983-01-01

    The method of optical pumping with a continuous wave dye laser has been used to produce beams of polarized 23 Na atoms and polarized 6 Li atoms. Optical pumping of a 23 Na atom beam using either a multimode dye laser or a single frequency dye laser with a double passed acousto-optic modulator results in electron spin polarizations of 0.70-0.90 and nuclear spin polarizations of 0.75-0.90. Optical pumping of a 6 Li atom beam using a single frequency dye laser either with an acousto-optic modulator or with Doppler shift pumping results in electron spin polarizations of 0.77-0.95 and nuclear spin polarizations greater than 0.90. The polarization of the atom beam is measured using either the laser induced fluorescence in an intermediate magnetic field or a 6-pole magnet to determine the occupation probabilities of the ground hyperfine sublevels following optical pumping. The results of the laser optical pumping experiments agree with the results of a rate equation analysis of the optical pumping process which predicts that nearly all atoms are transferred into a single sublevel for our values of laser intensity and interaction time. The use of laser optical pumping in a polarized ion source for nuclear scattering experiments is discussed. The laser optical pumping method provides a means of constructing an intense source of polarized Li and Na ions

  16. Laser-induced forward transfer (LIFT) of congruent voxels

    Energy Technology Data Exchange (ETDEWEB)

    Piqué, Alberto, E-mail: pique@nrl.navy.mil [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Breckenfeld, Eric [National Research Council Fellow at the Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-06-30

    Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D

  17. Laser-induced forward transfer (LIFT) of congruent voxels

    International Nuclear Information System (INIS)

    Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel; Breckenfeld, Eric

    2016-01-01

    Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D

  18. Laser-Induced Motion of a Nanofluid in a Micro-Channel

    Directory of Open Access Journals (Sweden)

    Tran X. Phuoc

    2016-10-01

    Full Text Available Since a photon carries both energy and momentum, when it interacts with a particle, photon-particle energy and momentum transfer occur, resulting in mechanical forces acting on the particle. In this paper we report our theoretical study on the use of a laser beam to manipulate and control the flow of nanofluids in a micro-channel. We calculate the velocity induced by a laser beam for TiO2, Fe2O3, Al2O3 MgO, and SiO2 nanoparticles with water as the base fluid. The particle diameter is 50 nm and the laser beam is a 4 W continuous beam of 6 mm diameter and 532 nm wavelength. The results indicate that, as the particle moves, a significant volume of the surrounding water (up to about 8 particle diameters away from the particle surface is disturbed and dragged along with the moving particle. The results also show the effect of the particle refractive index on the particle velocity and the induced volume flow rate. The velocity and the volume flowrate induced by the TiO2 nanoparticle (refractive index n = 2.82 are about 0.552 mm/s and 9.86 fL, respectively, while those induced by SiO2 (n = 1.46 are only about 7.569 μm/s and 0.135, respectively.

  19. Wafer-scale laser pantography: Fabrication of n-metal-oxide-semiconductor transistors and small-scale integrated circuits by direct-write laser-induced pyrolytic reactions

    International Nuclear Information System (INIS)

    McWilliams, B.M.; Herman, I.P.; Mitlitsky, F.; Hyde, R.A.; Wood, L.L.

    1983-01-01

    A complete set of processes sufficient for manufacture of n-metal-oxide-semiconductor (n-MOS) transistors by a laser-induced direct-write process has been demonstrated separately, and integrated to yield functional transistors. Gates and interconnects were fabricated of various combinations of n-doped and intrinsic polysilicon, tungsten, and tungsten silicide compounds. Both 0.1-μm and 1-μm-thick gate oxides were micromachined with and without etchant gas, and the exposed p-Si [100] substrate was cleaned and, at times, etched. Diffusion regions were doped by laser-induced pyrolytic decomposition of phosphine followed by laser annealing. Along with the successful manufacture of working n-MOS transistors and a set of elementary digital logic gates, this letter reports the successful use of several laser-induced surface reactions that have not been reported previously

  20. Computational fluid-dynamic model of laser-induced breakdown in air

    International Nuclear Information System (INIS)

    Dors, Ivan G.; Parigger, Christian G.

    2003-01-01

    Temperature and pressure profiles are computed by the use of a two-dimensional, axially symmetric, time-accurate computational fluid-dynamic model for nominal 10-ns optical breakdown laser pulses. The computational model includes a kinetics mechanism that implements plasma equilibrium kinetics in ionized regions and nonequilibrium, multistep, finite-rate reactions in nonionized regions. Fluid-physics phenomena following laser-induced breakdown are recorded with high-speed shadowgraph techniques. The predicted fluid phenomena are shown by direct comparison with experimental records to agree with the flow patterns that are characteristic of laser spark decay

  1. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  2. Laser induced single spot oxidation of titanium

    International Nuclear Information System (INIS)

    Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-01-01

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  3. Detection of early caries by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-07-01

    To improve sensitivity of dental caries detection by laser-induced breakdown spectroscopy (LIBS) analysis, it is proposed to utilize emission peaks in the ultraviolet. We newly focused on zinc whose emission peaks exist in ultraviolet because zinc exists at high concentration in the outer layer of enamel. It was shown that by using ratios between heights of an emission peak of Zn and that of Ca, the detection sensitivity and stability are largely improved. It was also shown that early caries are differentiated from healthy part by properly setting a threshold in the detected ratios. The proposed caries detection system can be applied to dental laser systems such as ones based on Er:YAG-lasers. When ablating early caries part by laser light, the system notices the dentist that the ablation of caries part is finished. We also show the intensity of emission peaks of zinc decreased with ablation with Er:YAG laser light.

  4. Enhancement of laser induced damage threshold of fused silica by acid etching combined with UV laser conditioning

    International Nuclear Information System (INIS)

    Chen Meng; Xiang Xia; Jiang Yong; Zu Xiaotao; Yuan Xiaodong; Zheng Wanguo; Wang Haijun; Li Xibin; Lu Haibing; Jiang Xiaodong; Wang Chengcheng

    2010-01-01

    Acid etching combined with UV laser conditioning is developed to enhance the laser induced damage threshold (LIDT) of fused silica. Firstly, the fused silica is etched for 1 ∼ 100 min with a buffered 1% HF solution. After acid etching, its transmittance, surface roughness and LIDT are measured. The results reveal that the fused silica has the highest LIDT and transmittance after etching for 10 min. Then UV laser (355 nm) conditioning is adopted to process the 10-min-etched fused silica. When the laser fluence is below 60% of fused silica's zero probability damage threshold, the LIDT increases gradually with the increase of laser conditioning fluence. However, the LIDT rapidly decreases to be lower than the threshold of the 10-min-etched fused silica when the conditioning fluence is up to 80% of the threshold. Proper acid etching and laser conditioning parameters will effectively enhance the laser damage resistance of fused silica. (authors)

  5. Study of the laser-induced damage of reflective components in the sub-picosecond regime

    International Nuclear Information System (INIS)

    Sozet, Martin

    2016-01-01

    In this thesis, laser-induced damage phenomenon of reflective components is investigated in the sub-picosecond regime. These components, made of stacks of dielectric materials, are widely used in powerful laser facilities such as PETAL laser. PETAL laser has been built at the CEA-CESTA in France to deliver multi-kJ/500 fs pulses at 1053 nm and reach a power higher than 6 PW. For this kind of laser systems, reflective components are commonly used instead of optics operating in transmission to limit the accumulation of non-linear phase along the beam propagation due to the high intensities. Optical components irradiated by the highest power densities are the pulse compression gratings, transport mirrors and the focusing parabola, located at the end of the laser chain. Nowadays, laser-induced damage is the main factor that limits the overall performances of powerful laser systems. This manuscript presents three study axes to better understand and control damage phenomenon. The first one concerns the conception of reflective optics for the peta-watt applications. The design of new structures has been investigated to reach high diffraction efficiencies in the case of pulse compression gratings and a high reflectivity in the case of mirrors, while reducing the Electric-field enhancement which is one of the causes of the laser-induced damage. The second axis deals with the development of a precise damage metrology with new testing tools which brings new perspectives and a new viewpoint for the assessment of the laser resistance of optical components. Finally, the third axis concerns the study the damage growth after several irradiations in the sub-picosecond regime. The evolution of the damage area during growth sequences is observed and compared to numerical simulations. It enables to improve the understanding in the growth phenomenon. In the end, these studies will allow to develop predictive models of the laser-induced damage and new tools for the conception of

  6. Evidence of liquid phase during laser-induced periodic surface structures formation induced by accumulative ultraviolet picosecond laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, T. T. D.; Petit, A.; Semmar, N., E-mail: nadjib.semmar@univ-orleans.fr [GREMI, UMR7344, CNRS/University of Orleans, 14 rue d' Issoudun, BP6744, 45067 Orleans Cedex 2 (France); Vayer, M. [ICMN, UMR 7374, CNRS/University of Orleans, 1b rue de la Ferollerie, CS 40059, 45071 Orleans Cedex (France); Sauldubois, A. [CME, UFR Sciences, University of Orleans, 1 Rue de Chartres, BP 6759, 45067 Orleans Cedex 2 (France)

    2015-11-09

    Laser-induced periodic surface structures (LIPSS) were formed on Cu/Si or Cu/glass thin films using Nd:YAG laser beam (40 ps, 10 Hz, and 30 mJ/cm{sup 2}). The study of ablation threshold is always achieved over melting when the variation of the number of pulses increases from 1 to 1000. But the incubation effect is leading to reduce the threshold of melting as increasing the number of laser pulse. Also, real time reflectivity signals exhibit typical behavior to stress the formation of a liquid phase during the laser-processing regime and helps to determine the threshold of soft ablation. Atomic Force Microscopy (AFM) analyses have shown the topology of the micro-crater containing regular spikes with different height. Transmission Electron Microscopy (TEM) allows finally to show three distinguished zones in the close region of isolated protrusions. The central zone is a typical crystallized area of few nanometers surrounded by a mixed poly-crystalline and amorphous area. Finally, in the region far from the protrusion zone, Cu film shows an amorphous structure. The real time reflectivity, AFM, and HR-TEM analyses evidence the formation of a liquid phase during the LIPSS formation in the picosecond regime.

  7. Laser-induced micro-jetting from armored droplets

    KAUST Repository

    Marston, J. O.

    2015-06-23

    We present findings from an experimental study of laser-induced cavitation within a liquid drop coated with a granular material, commonly referred to as “armored droplets” or “liquid marbles.” The cavitation event follows the formation of plasma after a nanosecond laser pulse. Using ultra-high-speed imaging up to 320,610 fps, we investigate the extremely rapid dynamics following the cavitation, which manifests itself in the form of a plethora of micro-jets emanating simultaneously from the spaces between particles on the surface of the drop. These fine jets break up into droplets with a relatively narrow diameter range, on the order of 10 μm. © 2015, Springer-Verlag Berlin Heidelberg.

  8. Fast switching of alkali atom dispensers using laser-induced heating

    International Nuclear Information System (INIS)

    Griffin, P.F.; Weatherill, K.J.; Adams, C.S.

    2005-01-01

    We show that by using an intense laser source to locally heat an alkali atom dispenser, one can generate a high flux of atoms followed by fast recovery (<100 ms) of the background pressure when the laser is extinguished. For repeated heating pulses a switch-on time for the atomic flux of 200 ms is readily attainable. This technique is suited to ultracold atom experiments using simple ultrahigh vacuum (UHV) chambers. Laser-induced heating provides a fast repetition of the experimental cycle, which, combined with low atom loss due to background gas collisions, is particularly useful for experiments involving far-off resonance optical traps, where sufficient laser power (0.5-4 W) is readily available

  9. Classification of Explosive Residues on Organic Substrates Using Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    2013-04-01

    Army Research Laboratory (ARL), we have been using laser induced breakdown spectro - scopy (LIBS), an optical spectroscopic technique that determines the...LX200GPS) was fitted with UV -coated optics to provide full broadband ( UV - VIS-NIR) capability. A custom-made three-channel gated CCD spectrometer (Ocean...Chem. 82, 1389–1400 (2010). 8. F. C. De Lucia, Jr., R. S. Harmon, K. L. McNesby, R. J. Winkel, Jr., and A. W. Miziolek, “Laser-induced breakdown spectro

  10. Scattering properties of ultrafast laser-induced refractive index shaping lenticular structures in hydrogels

    Science.gov (United States)

    Wozniak, Kaitlin T.; Germer, Thomas A.; Butler, Sam C.; Brooks, Daniel R.; Huxlin, Krystel R.; Ellis, Jonathan D.

    2018-02-01

    We present measurements of light scatter induced by a new ultrafast laser technique being developed for laser refractive correction in transparent ophthalmic materials such as cornea, contact lenses, and/or intraocular lenses. In this new technique, called intra-tissue refractive index shaping (IRIS), a 405 nm femtosecond laser is focused and scanned below the corneal surface, inducing a spatially-varying refractive index change that corrects vision errors. In contrast with traditional laser correction techniques, such as laser in-situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), IRIS does not operate via photoablation, but rather changes the refractive index of transparent materials such as cornea and hydrogels. A concern with any laser eye correction technique is additional scatter induced by the process, which can adversely affect vision, especially at night. The goal of this investigation is to identify sources of scatter induced by IRIS and to mitigate possible effects on visual performance in ophthalmic applications. Preliminary light scattering measurements on patterns written into hydrogel showed four sources of scatter, differentiated by distinct behaviors: (1) scattering from scanned lines; (2) scattering from stitching errors, resulting from adjacent scanning fields not being aligned to one another; (3) diffraction from Fresnel zone discontinuities; and (4) long-period variations in the scans that created distinct diffraction peaks, likely due to inconsistent line spacing in the writing instrument. By knowing the nature of these different scattering errors, it will now be possible to modify and optimize the design of IRIS structures to mitigate potential deficits in visual performance in human clinical trials.

  11. Molecular signatures in femtosecond laser-induced organic plasmas: comparison with nanosecond laser ablation.

    Science.gov (United States)

    Serrano, Jorge; Moros, Javier; Laserna, J Javier

    2016-01-28

    During the last few years, laser-induced breakdown spectroscopy (LIBS) has evolved significantly in the molecular sensing area through the optical monitoring of emissions from organic plasmas. Large efforts have been made to study the formation pathways of diatomic radicals as well as their connections with the bonding framework of molecular solids. Together with the structural and chemical-physical properties of molecules, laser ablation parameters seem to be closely tied to the observed spectral signatures. This research focuses on evaluating the impact of laser pulse duration on the production of diatomic species that populate plasmas of organic materials. Differences in relative intensities of spectral signatures from the plasmas of several organic molecules induced in femtosecond (fs) and nanosecond (ns) ablation regimes have been studied. Beyond the abundance and origin of diatomic radicals that seed the plasma, findings reveal the crucial role of the ablation regime in the breakage pattern of the molecule. The laser pulse duration dictates the fragments and atoms resulting from the vaporized molecules, promoting some formation routes at the expense of other paths. The larger amount of fragments formed by fs pulses advocates a direct release of native bonds and a subsequent seeding of the plasma with diatomic species. In contrast, in the ns ablation regime, the atomic recombinations and single displacement processes dominate the contribution to diatomic radicals, as long as atomization of molecules prevails over their progressive decomposition. Consequently, fs-LIBS better reflects correlations between strengths of emissions from diatomic species and molecular structure as compared to ns-LIBS. These new results entail a further step towards the specificity in the analysis of molecular solids by fs-LIBS.

  12. Liquid steel analysis by laser-induced plasma spectroscopy

    International Nuclear Information System (INIS)

    Gruber, J.

    2002-11-01

    When a nanosecond pulsed laser is focused onto a sample and the intensity exceeds a certain threshold, material is vaporized and a plasma is formed above the sample surface. The laser-light becomes increasingly absorbed by inverse bremsstrahlung and by photo-excitation and photo-ionization of atoms and molecules. The positive feedback, by which the number of energetic electrons for ionization is increased in an avalanche-like manner under the influence of laser-light, is the so-called optical breakdown. Radiating excited atoms and ions within the expanding plasma plume produce a characteristic optical emission spectrum. A spectroscopic analysis of this optical emission of the laser-induced plasma permits a qualitative and quantitative chemical analysis of the investigated sample. This technique is therefore often called laser-induced plasma spectroscopy (LIPS) or laser-induced breakdown spectroscopy (LIBS). LIPS is a fast non-contact technique, by which solid, liquid or gaseous samples can be analyzed with respect to their chemical composition. Hence, it is an appropriate tool for the rapid in-situ analysis of not easily accessible surfaces for process control in industrial environments. In this work, LIPS was studied as a technique to determine the chemical composition of solid and liquid steel. A LIPS set-up was designed and built for the remote and continuous in-situ analysis of the steel melt. Calibration curves were prepared for the LIPS analysis of Cr, Mn, Ni and Cu in solid steel using reference samples with known composition. In laboratory experiments an induction furnace was used to melt steel samples in crucibles, which were placed at a working distance of 1.5 m away from the LIPS apparatus. The response of the LIPS system was monitored on-line during the addition of pure elements to the liquid steel bath within certain concentration ranges (Cr: 0.11 - 13.8 wt%, Cu: 0.044 - 0.54 wt%, Mn: 1.38 - 2.5 wt%, Ni: 0.049 - 5.92 wt%). The analysis of an element

  13. Growth behavior of laser-induced damage on fused silica optics under UV, ns laser irradiation.

    Science.gov (United States)

    Negres, Raluca A; Norton, Mary A; Cross, David A; Carr, Christopher W

    2010-09-13

    The growth behavior of laser-induced damage sites is affected by a large number of laser parameters as well as site morphology. Here we investigate the effects of pulse duration on the growth rate of damage sites located on the exit surface of fused silica optics. Results demonstrate a significant dependence of the growth parameters on laser pulse duration at 351 nm from 1 ns to 15 ns, including the observation of a dominant exponential versus linear, multiple-shot growth behavior for long and short pulses, respectively. These salient behaviors are tied to the damage morphology and suggest a shift in the fundamental growth mechanisms for pulses in the 1-5 ns range.

  14. Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

    Science.gov (United States)

    Lednev, Vasily N; Pershin, Sergey M; Sdvizhenskii, Pavel A; Grishin, Mikhail Ya; Fedorov, Alexander N; Bukin, Vladimir V; Oshurko, Vadim B; Shchegolikhin, Alexander N

    2018-01-01

    A new approach combining Raman spectrometry and laser induced breakdown spectrometry (LIBS) within a single laser event was suggested. A pulsed solid state Nd:YAG laser running in double pulse mode (two frequency-doubled sequential nanosecond laser pulses with dozens microseconds delay) was used to combine two spectrometry methods within a single instrument (Raman/LIBS spectrometer). First, a low-energy laser pulse (power density far below ablation threshold) was used for Raman measurements while a second powerful laser pulse created the plasma suitable for LIBS analysis. A short time delay between two successive pulses allows measuring LIBS and Raman spectra at different moments but within a single laser flash-lamp pumping. Principal advantages of the developed instrument include high quality Raman/LIBS spectra acquisition (due to optimal gating for Raman/LIBS independently) and absence of target thermal alteration during Raman measurements. A series of high quality Raman and LIBS spectra were acquired for inorganic salts (gypsum, anhydrite) as well as for pharmaceutical samples (acetylsalicylic acid). To the best of our knowledge, the quantitative analysis feasibility by combined Raman/LIBS instrument was demonstrated for the first time by calibration curves construction for acetylsalicylic acid (Raman) and copper (LIBS) in gypsum matrix. Combining ablation pulses and Raman measurements (LIBS/Raman measurements) within a single instrument makes it an efficient tool for identification of samples hidden by non-transparent covering or performing depth profiling analysis including remote sensing. Graphical abstract Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

  15. Laser-induced forward transfer of hybrid carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Palla-Papavlu, A. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); University of Bucharest, Faculty of Physics, 405 Atomistilor Street, 077125 Magurele (Romania); Filipescu, M., E-mail: mihaela.filipescu@inflpr.ro [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); Vizireanu, S. [National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); Vogt, L. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Antohe, S. [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, 077125 Magurele (Romania); Academy of Romanian Scientists, Splaiul Independentei 54, 050094 Bucharest (Romania); Dinescu, M. [National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); Wokaun, A.; Lippert, T. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland)

    2016-06-30

    Highlights: • Rapid prototyping of carbon nanowalls (CNW) and functionalized CNWs is described. • CNW and CNW:SnO{sub 2} pixels are successfully printed by laser-induced forward transfer. • Flexible (polyimide) and rigid (glass) supports are used as substrates. • 4 μm thick CNW and CNW:SnO{sub 2} pixels maintain their morphology and structure after LIFT. - Abstract: Chemically functionalized carbon nanowalls (CNWs) are promising materials for a wide range of applications, i.e. gas sensors, membranes for fuel cells, or as supports for catalysts. However, the difficulty of manipulation of these materials hinders their integration into devices. In this manuscript a procedure for rapid prototyping of CNWs and functionalized CNWs (i.e. decorated with SnO{sub 2} nanoparticles) is described. This procedure enables the use of laser-induced forward transfer (LIFT) as a powerful technique for printing CNWs and CNW:SnO{sub 2} pixels onto rigid and flexible substrates. A morphological study shows that for a large range of laser fluences i.e. 500–700 mJ/cm{sup 2} it is possible to transfer thick (4 μm) CNW and CNW:SnO{sub 2} pixels. Micro-Raman investigation of the transferred pixels reveals that the chemical composition of the CNWs and functionalized CNWs does not change as a result of the laser transfer. Following these results one can envision that CNWs and CNW:SnO{sub 2} pixels obtained by LIFT can be ultimately applied in technological applications.

  16. Time-Resolved Emission Spectroscopic Study of Laser-Induced Steel Plasmas

    International Nuclear Information System (INIS)

    Shah, M. L.; Pulhani, A. K.; Suri, B. M.; Gupta, G. P.

    2013-01-01

    Laser-induced steel plasma is generated by focusing a Q-switched Nd:YAG visible laser (532 nm wavelength) with an irradiance of ∼ 1 × 10 9 W/cm 2 on a steel sample in air at atmospheric pressure. An Echelle spectrograph coupled with a gateable intensified charge-coupled detector is used to record the plasma emissions. Using time-resolved spectroscopic measurements of the plasma emissions, the temperature and electron number density of the steel plasma are determined for many times of the detector delay. The validity of the assumption by the spectroscopic methods that the laser-induced plasma (LIP) is optically thin and is also in local thermodynamic equilibrium (LTE) has been evaluated for many delay times. From the temporal evolution of the intensity ratio of two Fe I lines and matching it with its theoretical value, the delay times where the plasma is optically thin and is also in LTE are found to be 800 ns, 900 ns and 1000 ns.

  17. Laser-induced immune modulation inhibits tumor growth in vivo (Conference Presentation)

    Science.gov (United States)

    Ottaviani, Giulia; Martinelli, Valentina; Rupel, Katia; Caronni, Nicoletta; Naseem, Asma; Zandonà, Lorenzo; Perinetti, Giuseppe; Gobbo, Margherita; Di Lenarda, Roberto; Bussani, Rossana; Benvenuti, Federica; Giacca, Mauro; Biasotto, Matteo; Zacchigna, Serena

    2017-02-01

    Photobiomodulation stands as a recommended therapy for oral mucositis induced by oncological therapies. However, its mechanisms of action and, more importantly, its safety in cancer patients, are still unclear. We assessed cancer cell metabolism and proliferation in vitro and in vivo after exposure to different laser protocols. We exploited both ectopic melanoma and a more physiological oral carcinogenesis mouse model, followed by molecular, histological and immunohistochemical characterization. Laser irradiation resulted in a slightly increase in cell metabolism and proliferation in vitro, albeit each protocol exerted a difference response. Of notice, in vivo laser light reduced tumour growth and invasiveness, indicating e beneficial effect on tumor microenvironment. Laser-treated tumors were surrounded and infiltrated by immune cells, mainly lymphocytes and dendritic cells, paralleled by an enhanced secretion of type I interferons. In contrast, the number of pro-angiogenic macrophages was reduced in response to laser irradiation, with consequent normalization of the tumor vasculature. Based on these finding we have also started exploring the effect of photobiomodulation on lymphocyte response in an experimental model of vaccination. Preliminary data indicate that laser light induced antigen-specific CD8+ and CD4+ T cell responses. In conclusion, our data point toward photobiomodulation as an effective strategy to boost the immune response in vivo, with relevant, therapeutic activities in both cancer and vaccination experimental models. These results support the safe use of laser light on cancer patients and open the way to innovative therapeutic opportunities.

  18. Effects of ginkgo biloba extract on laser-induced choroidal neovascularization in rats

    Directory of Open Access Journals (Sweden)

    Chao Chen

    2013-11-01

    Full Text Available AIM: To investigate the effects of ginkgo biloba extract(EGb 761on laser-induced choroidal neovascularization(CNVin rats.METHODS: Totally 60 BN rats were randomly divided into 4 groups: normal control group, model group, experimental group, physiological saline group with 15 in each group. All CNV models were made by krypton laser. Rats in experimental group were intraperitoneally injected with 0.35% EGb761(100mg/kgevery day after laser exposure until they were sacrificed. Rats in physiological saline group were intraperitoneally injected physiological saline every day after laser exposure until they were sacrificed. Fundus fluorescein angiography(FFAwas performed on every rat on the 7th day, 14th day and the 21st day after laser exposure, then the rats were sacrificed immediately. The eyes were enucleated and processed for histopathologic examination.RESULTS: There was no choroidal fluorescein leakage staining in normal rats. There were obviously less choroidal fluorescein leakage points in experimental groups than that in the corresponding model groups(PCONCLUSION: EGb761 len inhibit the formation of laser-induced CNV in rats. The longer the time, the better curative effect.

  19. Observation of laser-induced elastic waves in agar skin phantoms using a high-speed camera and a laser-beam-deflection probe.

    Science.gov (United States)

    Laloš, Jernej; Gregorčič, Peter; Jezeršek, Matija

    2018-04-01

    We present an optical study of elastic wave propagation inside skin phantoms consisting of agar gel as induced by an Er:YAG (wavelength of 2.94 μm) laser pulse. A laser-beam-deflection probe is used to measure ultrasonic propagation and a high-speed camera is used to record displacements in ablation-induced elastic transients. These measurements are further analyzed with a custom developed image recognition algorithm utilizing the methods of particle image velocimetry and spline interpolation to determine point trajectories, material displacement and strain during the passing of the transients. The results indicate that the ablation-induced elastic waves propagate with a velocity of 1 m/s and amplitudes of 0.1 mm. Compared to them, the measured velocities of ultrasonic waves are much higher, within the range of 1.42-1.51 km/s, while their amplitudes are three orders of magnitude smaller. This proves that the agar gel may be used as a rudimental skin and soft tissue substitute in biomedical research, since its polymeric structure reproduces adequate soft-solid properties and its transparency for visible light makes it convenient to study with optical instruments. The results presented provide an insight into the distribution of laser-induced elastic transients in soft tissue phantoms, while the experimental approach serves as a foundation for further research of laser-induced mechanical effects deeper in the tissue.

  20. Fs-laser-induced Ca2+ concentration change during membrane perforation for cell transfection.

    Science.gov (United States)

    Baumgart, J; Bintig, W; Ngezahayo, A; Lubatschowski, H; Heisterkamp, A

    2010-02-01

    Fs-laser based opto-perforation is a gentle method for gene transfer into sensitive cells such as stem cells or primary cells. The high selectivity and the low damage to the cell lead to a high efficiency of transfection. However, there are side effects which induce stress to the cell due to the exchange of intra- and extracellular media as well as the disintegration of the structure of biomolecules resulting from the laser exposure. Moreover, the mechanisms of the optical transfection are still unclear. In this paper, we present our study on calcium (Ca(2+)) homeostasis during cell surgery, especially during laser induced membrane perforation. We show that the manipulation of cells can induce an increase in the cytosolic Ca(2+) concentration. This increase was not observed if the manipulation of the cells was performed in absence of the extracellular calcium indicating the importance of the Ca(2+) uptake. We found, that the uptake of extracellular Ca(2+) strongly depends on the repetition rate and the irradiation time of the laser pulses. The exposure for several seconds to kHz pulses even induces Ca(2+) induced Ca(2+) release. Dependent on the location of perforation, probably in the vicinity of an intracellular Ca(2+) stock, an instantaneous intracellular Ca(2+) release can be induced. Since Ca(2+) could be involved in negative side effect by cell surgery, we propose an application of the optoperforation technique in nominal Ca(2+)-free external solution.

  1. Manipulating the mitochondria activity in human hepatic cell line Huh7 by low-power laser irradiation

    Science.gov (United States)

    Lynnyk, Anna; Lunova, Mariia; Jirsa, Milan; Egorova, Daria; Kulikov, Andrei; Kubinová, Šárka; Lunov, Oleg; Dejneka, Alexandr

    2018-01-01

    Low-power laser irradiation of red light has been recognized as a promising tool across a vast variety of biomedical applications. However, deep understanding of the molecular mechanisms behind laser-induced cellular effects remains a significant challenge. Here, we investigated mechanisms involved in the death process in human hepatic cell line Huh7 at a laser irradiation. We decoupled distinct cell death pathways targeted by laser irradiations of different powers. Our data demonstrate that high dose laser irradiation exhibited the highest levels of total reactive oxygen species production, leading to cyclophilin D-related necrosis via the mitochondrial permeability transition. On the contrary, low dose laser irradiation resulted in the nuclear accumulation of superoxide and apoptosis execution. Our findings offer a novel insight into laser-induced cellular responses, and reveal distinct cell death pathways triggered by laser irradiation. The observed link between mitochondria depolarization and triggering ROS could be a fundamental phenomenon in laser-induced cellular responses. PMID:29541521

  2. Innovative applications of femtosecond laser induced self-organized nanostructure

    International Nuclear Information System (INIS)

    Shimotsuma, Yasuhiko; Miura, Kiyotaka; Sakakura, Masaaki

    2015-01-01

    The nanostructure induced by the direct-writing of femtosecond-laser pulses can open a new opportunity to develop avant-garde devices such as a 5D optical storage, polarization imaging sensor, thermoelectric conversion elements. (author)

  3. Laser-induced partial oxidation of cyclohexane in liquid phase

    International Nuclear Information System (INIS)

    Oshima, Y.; Wu, X.W.; Koda, S.

    1995-01-01

    A laser-induced partial oxidation of cyclohexane was studied in the liquid phase. With KrF excimer laser (248 nm) irradiation to neat liquid cyclohexane in which O 2 was dissolved, cyclohexanol and cyclohexanone were obtained with very high selectivities, together with cyclohexane as a minor product. Radical recombination reactions to produce dicyclohexyl ether and bicyclohexyl also took place, while these products were not observed in the gas phase reaction. These experimental results were considered to be due not only to higher concentration of cyclohexane but to the cage effect in the liquid phase oxidation. To clarify the reaction progress including the photoabsorption process, the effects of laser intensity and O 2 pressure on product distribution were studied. (author)

  4. Magnetic field generation by circularly polarized laser light and inertial plasma confinement in a miniature 'Magnetic Bottle' induced by circularly polarized laser light

    International Nuclear Information System (INIS)

    Kolka, E.

    1993-07-01

    A new concept of hot plasma confinement in a miniature magnetic bottle induced by circularly polarized laser light is suggested in this work. Magnetic fields generated by circularly polarized laser light may be of the order of megagauss. In this configuration the circularly polarized laser light is used to get confinement of a plasma contained in a good conductor vessel. The poloidal magnetic field induced by the circularly polarized laser and the efficiency of laser absorption by the plasma are calculated in this work. The confinement in this scheme is supported by the magnetic forces and the Lawson criterion for a DT plasma might be achieved for number density n=5*10 21 cm -3 and confinement time τ= 20 nsec. The laser and the plasma parameters required to get an energetic gain are calculated. (authors)

  5. Fusion--fission hybrid concepts for laser-induced fusion

    International Nuclear Information System (INIS)

    Maniscalco, J.

    1976-01-01

    Fusion-fission hybrid concepts are viewed as subcritical fission reactors driven and controlled by high-energy neutrons from a laser-induced fusion reactor. Blanket designs encompassing a substantial portion of the spectrum of different fission reactor technologies are analyzed and compared by calculating their fissile-breeding and fusion-energy-multiplying characteristics. With a large number of different fission technologies to choose from, it is essential to identify more promising hybrid concepts that can then be subjected to in-depth studies that treat the engineering safety, and economic requirements as well as the neutronic aspects. In the course of neutronically analyzing and comparing several fission blanket concepts, this work has demonstrated that fusion-fission hybrids can be designed to meet a broad spectrum of fissile-breeding and fusion-energy-multiplying requirements. The neutronic results should prove to be extremely useful in formulating the technical scope of future studies concerned with evaluating the technical and economic feasibility of hybrid concepts for laser-induced fusion

  6. Probing the onset of laser-induced relativistic transparency in massive targets

    Science.gov (United States)

    Wang, Tao; Wagner, Craig; Toncian, Toma; Dyer, Gilliss; Arefiev, Alexey; Ditmire, Todd

    2017-10-01

    We have investigated a novel approach of using harmonics of the laser frequency generated in the plasma to detect the onset of relativistic transparency induced by an intense laser pulse. The onset of the transparency is directly associated with a forward motion of a relativistically adjusted critical surface. The corresponding velocity is relativistic, so the harmonics generated at this critical surface are noticeably shifted. Using particle-in-cell simulations, we have confirmed that the resulting shift greatly exceeds the shift produced during a hole-boring process when the relativistic transparency plays no role, which allows us to clearly identify the onset of the relativistic transparency. Experiments that we have carried out at the Texas Petawatt laser showcase this approach. The 3rd harmonic signal detected in experiments with massive targets irradiated at laser intensities around 1020 W/cm2 has a pronounced shift associated with the relativistic transparency. The shift represents a recession of the relativistically adjusted critical surface with a velocity close to 0.2 c. This approach opens a new possibility of detecting changes in the optical properties of matter induced by intense laser pulses even when no transmission of the laser pulse takes place. This research was supported part by NSF (Grant No. 1632777) and NNSA (Cont. No. DE-NA0002008). Simulations were performed using HPC resources at TACC at the University of Texas.

  7. Dual-wavelength differential spectroscopic imaging for diagnostics of laser-induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Motto-Ros, V., E-mail: vincent.motto-ros@univ-lyon1.fr [Universite de Lyon, F-69622, Lyon, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Ma, Q.L. [Universite de Lyon, F-69622, Lyon, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Gregoire, S. [CRITT Matriaux Alsace, 19 rue de St Junien, 67300 Schiltigheim (France); Lei, W.Q.; Wang, X.C. [Universite de Lyon, F-69622, Lyon, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Pelascini, F.; Surma, F. [CRITT Matriaux Alsace, 19 rue de St Junien, 67300 Schiltigheim (France); Detalle, V. [Laboratoire de Recherche des Monuments Historiques, 29 rue de Paris, 77420 Champs-sur-Marne (France); Yu, J. [Universite de Lyon, F-69622, Lyon, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France)

    2012-08-15

    A specific configuration for plasma fast spectroscopic imaging was developed, where a pair of narrowband filters, one fitting an emission line of a species to be studied and the other out of its emission line, allowed double images to be taken for a laser-induced plasma. A dedicated software was developed for the subtraction between the double images. The result represents therefore the monochromatic emission image of the species in the plasma. We have shown in this work that such configuration is especially efficient for the monitoring of a plasma generated under the atmospheric pressure at very short delays after the impact of the laser pulse on the target, when a strong continuum emission is observed. The efficiency of the technique has been particularly demonstrated in the study of laser-induced plasma on a polymer target. Molecular species, such as C{sub 2} and CN, as well as atomic species, such as C and N, were imaged starting from 50 ns after the laser impact. Moreover space segregation of different species, atomic or molecular, inside of the plasma was clearly observed. - Highlights: Black-Right-Pointing-Pointer Imaging to study species with time and space resolution in laser induced plasma. Black-Right-Pointing-Pointer Image display of multiple species is proposed based on RGB color model. Black-Right-Pointing-Pointer Molecular emission (CN and C{sub 2}) is observed at very short delays (50 ns). Black-Right-Pointing-Pointer Segregation of different species inside the plasma is clearly established.

  8. Visible laser induced positive ion emissions from NaCl nanoparticles prepared by droplet rapid drying

    International Nuclear Information System (INIS)

    Sun, Mao-Xu; Guo, Deng-Zhu; Xing, Ying-Jie; Zhang, Geng-Min

    2012-01-01

    Highlights: ► NaCl nanoparticles were firstly prepared by heat induced explosion on silicon wafer. ► We found that laser induced ion emissions from NaCl nanoparticles are more prominent. ► We found that water adsorption can efficiently enhance laser induced ion emissions. ► The ultra-photothermal effect in NaCl nanoparticles was observed and explained. - Abstract: A novel convenient way for the formation of sodium chloride (NaCl) nanoparticles on silicon wafer is proposed by using a droplet rapid drying method. The laser induced positive ion emissions from NaCl nanoparticles with and without water treatment is demonstrated by using a laser desorption/ionization time-of-flight mass spectrometer, with laser intensity well below the plasma formation threshold. It is found that the positive ion emissions from NaCl nanoparticles are obviously higher than that from microsize NaCl particles under soft 532 nm laser irradiations, and water adsorption can efficiently enhance the ion emissions from NaCl nanoparticles. The initial kinetic energies of the emitted ions are estimated as 16–17 eV. The synergy of the ultra-thermal effect in nanomaterials, the defect-mediated multiphoton processes, and the existence of intermediate states in NaCl-water interfaces are suggested as the mechanisms.

  9. Capillary electrophoresis hyphenated with UV-native-laser induced fluorescence detection (CE/UV-native-LIF).

    Science.gov (United States)

    Couderc, François; Ong-Meang, Varravaddheay; Poinsot, Véréna

    2017-01-01

    Native laser-induced fluorescence using UV lasers associated to CE offers now a large related literature, for now 30 years. The main works have been performed using very expensive Ar-ion lasers emitting at 257 and 275 nm. They are not affordable for routine analyses, but have numerous applications such as protein, catecholamine, and indolamine analysis. Some other lasers such as HeCd 325 nm have been used but only for few applications. Diode lasers, emitting at 266 nm, cheaper, are extensively used for the same topics, even if the obtained sensitivity is lower than the one observed using the costly UV-Ar-ion lasers. This review presents various CE or microchips applications and different UV lasers used for the excitation of native fluorescence. We showed that CE/Native UV laser induced fluorescence detection is very sensitive for detection as well as small aromatic biomolecules than proteins containing Trp and Tyr amino acids. Moreover, it is a simple way to analyze biomolecules without derivatization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Development of laser materials processing and laser metrology techniques

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Chung, Chin Man; Kim, Jeong Mook; Kim, Min Suk; Kim, Kwang Suk; Baik, Sung Hoon; Kim, Seong Ouk; Park, Seung Kyu

    1997-09-01

    The applications of remote laser materials processing and metrology have been investigated in nuclear industry from the beginning of laser invention because they can reduce the risks of workers in the hostile environment by remote operation. The objective of this project is the development of laser material processing and metrology techniques for repairing and inspection to improve the safety of nuclear power plants. As to repairing, we developed our own laser sleeve welding head and innovative optical laser weld monitoring techniques to control the sleeve welding process. Furthermore, we designed and fabricated a 800 W Nd:YAG and a 150 W Excimer laser systems for high power laser materials processing in nuclear industry such as cladding and decontamination. As to inspection, we developed an ESPI and a laser triangulation 3-D profile measurement system for defect detection which can complement ECT and UT inspections. We also developed a scanning laser vibrometer for remote vibration measurement of large structures and tested its performance. (author). 58 refs., 16 tabs., 137 figs

  11. Prospects for laser-induced breakdown spectroscopy for biomedical applications: a review.

    Science.gov (United States)

    Singh, Vivek Kumar; Rai, Awadhesh Kumar

    2011-09-01

    We review the different spectroscopic techniques including the most recent laser-induced breakdown spectroscopy (LIBS) for the characterization of materials in any phase (solid, liquid or gas) including biological materials. A brief history of the laser and its application in bioscience is presented. The development of LIBS, its working principle and its instrumentation (different parts of the experimental set up) are briefly summarized. The generation of laser-induced plasma and detection of light emitted from this plasma are also discussed. The merit and demerits of LIBS are discussed in comparison with other conventional analytical techniques. The work done using the laser in the biomedical field is also summarized. The analysis of different tissues, mineral analysis in different organs of the human body, characterization of different types of stone formed in the human body, analysis of biological aerosols using the LIBS technique are also summarized. The unique abilities of LIBS including detection of molecular species and calibration-free LIBS are compared with those of other conventional techniques including atomic absorption spectroscopy, inductively coupled plasma atomic emission spectroscopy and mass spectroscopy, and X-ray fluorescence.

  12. Time-resolved ultraviolet laser-induced breakdown spectroscopy for organic material analysis

    Energy Technology Data Exchange (ETDEWEB)

    Baudelet, Matthieu; Boueri, Myriam [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1, UMR CNRS 5579, 43, Bd. du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Yu Jin [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1, UMR CNRS 5579, 43, Bd. du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)], E-mail: jin.yu@lasim.univ-lyon1.fr; Mao, Samuel S; Piscitelli, Vincent; Xianglei, Mao; Russo, Richard E [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2007-12-15

    Ultraviolet pulses (266 nm) delivered by a quadrupled Nd:YAG laser were used to analyze organic samples with laser-induced breakdown spectroscopy (LIBS). We present characteristics of the spectra obtained from organic samples with special attentions on the emissions of organic elements, O and N, and molecular bonds CN. The choice of these atomic or molecular species is justified on one hand, by the importance of these species to specify organic or biological materials; and on the other hand by the possible interferences with ambient air when laser ablation takes place in the atmosphere. Time-resolved LIBS was used to determine the time-evolution of line intensity emitted from these species. We demonstrate different kinetic behaviors corresponding to different origins of emitters: native atomic or molecular species directly vaporized from the sample or those generated through dissociation or recombination due to interaction between laser-induced plasma and air molecules. Our results show the ability of time-resolved UV-LIBS for detection and identification of native atomic or molecular species from an organic sample.

  13. Laser filament-induced aerosol formation

    Directory of Open Access Journals (Sweden)

    H. Saathoff

    2013-05-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  14. Disorder-induced localization of excitability in an array of coupled lasers

    Science.gov (United States)

    Lamperti, M.; Perego, A. M.

    2017-10-01

    We report on the localization of excitability induced by disorder in an array of coupled semiconductor lasers with a saturable absorber. Through numerical simulations we show that the exponential localization of excitable waves occurs if a certain critical amount of randomness is present in the coupling coefficients among the lasers. The results presented in this Rapid Communication demonstrate that disorder can induce localization in lattices of excitable nonlinear oscillators, and can be of interest in the study of photonics-based random networks, neuromorphic systems, and, by analogy, in biology, in particular, in the investigation of the collective dynamics of neuronal cell populations.

  15. Laser-induced damage to thin film dielectric coatings

    International Nuclear Information System (INIS)

    Walker, T.W.

    1980-01-01

    The laser-induced damage thresholds of dielectric thin film coatings have been found to be more than an order of magnitude lower than the bulk material damage thresholds. Prior damage studies have been inconclusive in determining the damage mechanism which is operative in thin films. A program was conducted in which thin film damage thresholds were measured as a function of laser wavelength (1.06 μm, 0.53 μm, 0.35 μm and 0.26 μm), laser pulse length (5 and 15 nanoseconds), film materials and film thickness. The large matrix of data was compared to predictions given by avalanche ionization, multiphoton ionization and impurity theories of laser damage. When Mie absorption cross-sections and the exact thermal equations were included into the impurity theory excellent agreement with the data was found. The avalanche and multiphoton damage theories could not account for most parametric variations in the data. For example, the damage thresholds for most films increased as the film thickness decreased and only the impurity theory could account for this behavior. Other observed changes in damage threshold with changes in laser wavelength, pulse length and film material could only be adequately explained by the impurity theory. The conclusion which results from this study is that laser damage in thin film coatings results from absorbing impurities included during the deposition process

  16. Quantitative analysis of chromium concentration in nickel based alloys by laser induced breakdown spectroscopy at atmospheric pressure using a nanosecond ultraviolet Nd:YAG laser

    International Nuclear Information System (INIS)

    Gupta, G.P.; Suri, B.M.; Verma, A.; Sundararaman, M.; Unnikrishnan, V.K.; Alti, K.; Kartha, V.B.; Santhosh, C.

    2010-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been well recognized as a simple, fast and direct analytical technique of elemental analysis of multi-element materials by a number of research groups all over the world. It is based on the focusing of a high-power pulsed laser beam with a power density > 100 MW/cm 2 onto a sample surface followed by optical emission spectroscopy of the plasma produced over the surface. In the present work, they have carried out the quantitative analysis of chromium in nickel-based-alloys using laser-induced breakdown spectroscopy (LIBS) in air at atmospheric pressure. In the present work the quantitative analysis of chromium in nickel-based-alloys using laser-induced break-down spectroscopy (LIBS) in air at atmospheric pressure has been carried out

  17. Development of Mechanical Sealing and Laser Welding Technology to Instrument Thermocouple for Nuclear Fuel Test Rod

    Energy Technology Data Exchange (ETDEWEB)

    Joung, Chang-Young; Ahn, Sung-Ho; Hong, Jin-Tae; Kim, Ka-Hye; Huh, Sung-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Zircaloy-4 of the nuclear fuel test rod, AISI 316L of the mechanical sealing parts, and the MI (mineral insulated) cable at a thermocouple instrumentation are hetero-metals, and are difficult to weld to dissimilar materials. Therefore, a mechanical sealing method to instrument the thermocouple should be conducted using two kinds of sealing process as follows: One is a mechanical sealing process using Swagelok, which is composed of sealing components that consists of an end-cap, a seal tube, a compression ring and a Swagelok nut. The other is a laser welding process used to join a seal tube, and an MI cable, which are made of the same material. The mechanical sealing process should be sealed up with the mechanical contact compressed by the strength forced between a seal tube and an end-cap, and the laser welding process should be conducted to have no defects on the sealing area between a seal tube and an MI cable. Therefore, the mechanical sealing and laser welding techniques need to be developed to accurately measure the centerline temperature of the nuclear fuel test rod in an experimental reactor. The mechanical sealing and laser welding tests were conducted to develop the thermocouple instrumentation techniques for the nuclear fuel test rod. The optimum torque value of a Swagelok nut to seal the mechanical sealing part between the end-cap and seal tube was established through various torque tests using a torque wrench. The optimum laser welding conditions to seal the welding part between a seal tube and an MI cable were obtained through various welding tests using a laser welding system.

  18. Development of Mechanical Sealing and Laser Welding Technology to Instrument Thermocouple for Nuclear Fuel Test Rod

    International Nuclear Information System (INIS)

    Joung, Chang-Young; Ahn, Sung-Ho; Hong, Jin-Tae; Kim, Ka-Hye; Huh, Sung-Ho

    2015-01-01

    Zircaloy-4 of the nuclear fuel test rod, AISI 316L of the mechanical sealing parts, and the MI (mineral insulated) cable at a thermocouple instrumentation are hetero-metals, and are difficult to weld to dissimilar materials. Therefore, a mechanical sealing method to instrument the thermocouple should be conducted using two kinds of sealing process as follows: One is a mechanical sealing process using Swagelok, which is composed of sealing components that consists of an end-cap, a seal tube, a compression ring and a Swagelok nut. The other is a laser welding process used to join a seal tube, and an MI cable, which are made of the same material. The mechanical sealing process should be sealed up with the mechanical contact compressed by the strength forced between a seal tube and an end-cap, and the laser welding process should be conducted to have no defects on the sealing area between a seal tube and an MI cable. Therefore, the mechanical sealing and laser welding techniques need to be developed to accurately measure the centerline temperature of the nuclear fuel test rod in an experimental reactor. The mechanical sealing and laser welding tests were conducted to develop the thermocouple instrumentation techniques for the nuclear fuel test rod. The optimum torque value of a Swagelok nut to seal the mechanical sealing part between the end-cap and seal tube was established through various torque tests using a torque wrench. The optimum laser welding conditions to seal the welding part between a seal tube and an MI cable were obtained through various welding tests using a laser welding system

  19. Influence of laser beam profile on electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Cuk, S. M.; Radonjic, M.; Krmpot, A. J.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M.

    2010-01-01

    We compared, experimentally and theoretically, Hanle electromagnetically induced absorption (EIA) obtained using Gaussian and Π-shaped laser beams 3 mm in diameter. The study was done by measuring the transmission of a laser locked to the F g =2→F e =3 transition at the D 2 line of 87 Rb in a vacuum cell. EIA linewidths obtained for the two laser profiles were significantly different in the range of laser intensities 1-4 mW/cm 2 . EIA with the Π-shaped laser beam has a broad intensity maximum and linewidths larger than those obtained with the Gaussian beam profile. We also studied Hanle EIA by measuring the transmission of selected segments of the entire laser beam by placing a small movable aperture in front of the detector. Waveforms so obtained in Hanle EIA resonances were strongly influenced both by the radial distance of the transmitted segment from the beam center and by the radial profile of the laser beam. We show that outer regions of Gaussian beam, and central regions of the Π-shaped beam generate the narrowest lines. The different behaviors of EIA owing to different beam profiles revealed by both theory and experiment indicate the importance of the radial profile of the laser beam for proper modeling of coherent effects in alkali metal vapors.

  20. Studies of the confinement at laser-induced backside dry etching using infrared nanosecond laser pulses

    Science.gov (United States)

    Ehrhardt, M.; Lorenz, P.; Bayer, L.; Han, B.; Zimmer, K.

    2018-01-01

    In the present study, laser-induced backside etching of SiO2 at an interface to an organic material using laser pulses with a wavelength of λ = 1064 nm and a pulse length of τ = 7 ns have been performed in order to investigate selected processes involved in etching of the SiO2 at confined ablation conditions with wavelengths well below the band gap of SiO2. Therefore, in between the utilized metallic absorber layer and the SiO2 surface, a polymer interlayer with a thickness between 20 nm to 150 nm was placed with the aim, to separate the laser absorption process in the metallic absorber layer from the etching process of the SiO2 surface due to the provided organic interlayer. The influence of the confinement of the backside etching process was analyzed by the deposition of different thick polymer layers on top of the metallic absorber layer. In particular, it was found that the SiO2 etching depth decreases with higher polymer interlayer thickness. However, the etching depth increases with increasing the confinement layer thickness. SEM images of the laser processed areas show that the absorber and confinement layers are ruptured from the sample surface without showing melting, and suggesting a lift off process of these films. The driving force for the layers lift off and the etching of the SiO2 is probably the generated laser-induce plasma from the confined ablation that provides the pressure for lift off, the high temperatures and reactive organic species that can chemically attack the SiO2 surface at these conditions.

  1. Flexible temperature and flow sensor from laser-induced graphene

    KAUST Repository

    Marengo, Marco; Marinaro, Giovanni; Kosel, Jü rgen

    2017-01-01

    Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced graphene. The main benefits arise from peculiar electrical, thermal and mechanical performances of the material thus obtained, along with a cheap

  2. An experimental study on choroidal neovascularization induced by Krypton laser in rat model.

    Science.gov (United States)

    Cui, Jing; Liu, Yuanyuan; Zhang, Jingkai; Yan, Hua

    2014-01-01

    The purpose of this work was to study the efficacy and safety of choroidal neovascularization (CNV) formation induced by Krypton laser in Brown Norway (BN) rats, and observe the trend of the change of CNV after laser photocoagulation. Twenty-five male BN rats were involved in this study. Two eyes of one rat without any laser photocoagulation were randomly selected as the control group, and the other 48 eyes of 24 rats were selected as the experimental group. Eight eyes of four rats were randomly selected to receive the examinations of fundus fluorescein angiography (FFA), histopathology, and transmission electron microscopy 3, 7, 14, 21, 28, and 56 days after laser photocoagulation. After laser photocoagulation, the leakage appeared in burns on day 7 (59%), reached the peak on day 21 (84%), (p0.05). The thickness of CNV increased from day 7 to day 21 (p0.05). The experimental model of CNV can be successfully induced by Krypton laser in rats with a stable, long-lasting, and high success rate. After laser photocoagulation, the leakages appear on day 7, reach the peak on day 21, and remain stable after day 21.

  3. Laser-induced transfer of gel microdroplets for cell printing

    Science.gov (United States)

    Yusupov, V. I.; Zhigar'kov, V. S.; Churbanova, E. S.; Chutko, E. A.; Evlashin, S. A.; Gorlenko, M. V.; Cheptsov, V. S.; Minaev, N. V.; Bagratashvili, V. N.

    2017-12-01

    We study thermal and transport processes involved in the transfer of gel microdroplets under the conditions of laser cell microprinting. The specific features of the interaction of pulsed laser radiation ( λ = 1.064 µm, pulse duration 4 - 200 ns, energy 2 µJ - 1 mJ) with the absorbing gold film deposited on the glass donor substrate are determined. The investigation of the dynamics of transport processes by means of fast optical video recording and optoacoustic methods makes it possible to determine the characteristics of the produced gel jets as functions of the laser operation regimes. The hydrodynamic process of interaction between the laser radiation and the gold coating with the hydrogel layer on it is considered and the temperature in the region of the laser pulse action is estimated. It is shown that in the mechanism of laser-induced transfer a significant role is played by the processes of explosive boiling of water (in gel) and gold. The amount of gold nanoparticles arriving at the acceptor plate in the process of the laser transfer is determined. For the laser pulse duration 8 ns and small energies (less than 10 µJ), the fraction of gold nanoparticles in the gel microdroplets is negligibly small, and their quantity linearly grows with increasing pulse energy. The performed studies offer a base for optimising the processes of laser transfer of gel microdroplets in the rapidly developing technologies of cell microprinting.

  4. Nuclear fission and neutron-induced fission cross-sections

    CERN Document Server

    James, G D; Michaudon, A; Michaudon, A; Cierjacks, S W; Chrien, R E

    2013-01-01

    Nuclear Fission and Neutron-Induced Fission Cross-Sections is the first volume in a series on Neutron Physics and Nuclear Data in Science and Technology. This volume serves the purpose of providing a thorough description of the many facets of neutron physics in different fields of nuclear applications. This book also attempts to bridge the communication gap between experts involved in the experimental and theoretical studies of nuclear properties and those involved in the technological applications of nuclear data. This publication will be invaluable to those interested in studying nuclear fis

  5. Nuclear physics with laser-electron-photons. Developments and perspectives at SPring-8

    International Nuclear Information System (INIS)

    Fujiwara, Mamoru

    1998-01-01

    By the Compton scattering with ultraviolet laser beam using the 8 GeV electron beam of the SPring-8, the photon beam which is polarized by nearly 100% is obtained in 1-3.5 GeV region. The quark nuclear physics research at this facility is unique in the world, and it is expected that in the experiment at the SPring-8, the collision phenomena of polarized, high energy gamma-ray and the quarks in nucleons and the knockout phenomena of quarks are observed. Also the polarization experiment for clarifying ''the origin of nucleon spin'' has been proposed. Japan can stand at the top in the world in the research of quark nuclear physics with leptons. In the inverse Compton scattering using far infrared laser, the gamma-ray with good directionality of MeV range is obtained, and it will be applied widely to the research on E1 resonance and M1 excitation of atomic nuclei. In this report, the medium energy quark nuclear physics developed at the SPring-8 is outlined, and the nuclear physics which is expected to be developed when the high intensity, high polarization gamma-ray of about 10 MeV is generated is discussed. The detection of s, anti-s components in nucleons, research on baryon deformation and baryon spectra, verification of the Gerasimov, Drell-Hearn law of sum, meson structure, test of quark model by the photolysis of deuterons, dual Ginzburg Landau theory exploration, research on the mass and behavior of mesons in nuclear media are discussed. (K.I.)

  6. Nuclear physics with laser-electron-photons. Developments and perspectives at SPring-8

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Mamoru [Osaka Univ., Ibaraki (Japan). Research Center for Nuclear Physics

    1998-03-01

    By the Compton scattering with ultraviolet laser beam using the 8 GeV electron beam of the SPring-8, the photon beam which is polarized by nearly 100% is obtained in 1-3.5 GeV region. The quark nuclear physics research at this facility is unique in the world, and it is expected that in the experiment at the SPring-8, the collision phenomena of polarized, high energy gamma-ray and the quarks in nucleons and the knockout phenomena of quarks are observed. Also the polarization experiment for clarifying ``the origin of nucleon spin`` has been proposed. Japan can stand at the top in the world in the research of quark nuclear physics with leptons. In the inverse Compton scattering using far infrared laser, the gamma-ray with good directionality of MeV range is obtained, and it will be applied widely to the research on E1 resonance and M1 excitation of atomic nuclei. In this report, the medium energy quark nuclear physics developed at the SPring-8 is outlined, and the nuclear physics which is expected to be developed when the high intensity, high polarization gamma-ray of about 10 MeV is generated is discussed. The detection of s, anti-s components in nucleons, research on baryon deformation and baryon spectra, verification of the Gerasimov, Drell-Hearn law of sum, meson structure, test of quark model by the photolysis of deuterons, dual Ginzburg Landau theory exploration, research on the mass and behavior of mesons in nuclear media are discussed. (K.I.)

  7. Value added cleaning and disinfection of the root canal: laser-activated irrigation and laser-induced photoporation

    Science.gov (United States)

    De Moor, Roeland J. G.; Meire, Maarten A.

    2016-03-01

    Among present-day marketed systems ultrasonic activation appears to be the best way to activate and potentiate endodontic irrigants. An alternative for ultrasonic activation of irrigants is laser activated irrigation (LAI) or photoninitiated acoustic streaming. Based on present-day research it appears that LAI (especially with Erbium lasers) can be more efficient for debris removal out of root canals and interaction with the endodontic biofilms thanks to the induction of specific cavitation phenomena and acoustic streaming. Other wavelengths are now explored to be used for LAI. Another way to interact with biofilms is to rely on laser-induced photoporation in combination with gold nanoparticles ( AuNPs). The latter is an alternative physical method for delivering macromolecules in cells. Nanosized membrane pores can be created upon pulsed laser illumination. Depending on the laser energy, pores are created through either direct heating of the AuNPs or by vapour nanobubbles that can emerge around the AuNPs.

  8. Apparatus, system, and method for laser-induced breakdown spectroscopy

    Science.gov (United States)

    Effenberger, Jr., Andrew J; Scott, Jill R; McJunkin, Timothy R

    2014-11-18

    In laser-induced breakdown spectroscopy (LIBS), an apparatus includes a pulsed laser configured to generate a pulsed laser signal toward a sample, a constructive interference object and an optical element, each located in a path of light from the sample. The constructive interference object is configured to generate constructive interference patterns of the light. The optical element is configured to disperse the light. A LIBS system includes a first and a second optical element, and a data acquisition module. The data acquisition module is configured to determine an isotope measurement based, at least in part, on light received by an image sensor from the first and second optical elements. A method for performing LIBS includes generating a pulsed laser on a sample to generate light from a plasma, generating constructive interference patterns of the light, and dispersing the light into a plurality of wavelengths.

  9. Nonlinear propagation of a spatially incoherent laser beam: self-induced smoothing and reduction of scattering instabilities

    International Nuclear Information System (INIS)

    Maximov, A.V.; Ourdev, I.G.; Rozmus, W.; Capjack, C.E.; Mounaix, Ph.; Huller, S.; Pesme, D.; Tikhonchuk, V.T.; Divol, L.

    2000-01-01

    It is shown that plasma-induced angular spreading and spectral broadening of a spatially incoherent laser beam correspond to increased spatial and temporal incoherence of the laser light. The spatial incoherence is characterized by an effective beam f-number, decreasing in space along the direction of light propagation. Plasma-induced beam smoothing can influence laser-plasma interaction physics. In particular, decreasing the correlation time of the propagating laser light may dramatically reduce the levels of backward stimulated Brillouin and Raman scattering inside the plasma. Also, the decrease of the laser beam effective f-number reduces the reflectivity of backward stimulated Brillouin scattering. (authors)

  10. Desorption/ablation of lithium fluoride induced by extreme ultraviolet laser radiation

    Directory of Open Access Journals (Sweden)

    Blejchař Tomáš

    2016-06-01

    Full Text Available The availability of reliable modeling tools and input data required for the prediction of surface removal rate from the lithium fluoride targets irradiated by the intense photon beams is essential for many practical aspects. This study is motivated by the practical implementation of soft X-ray (SXR or extreme ultraviolet (XUV lasers for the pulsed ablation and thin film deposition. Specifically, it is focused on quantitative description of XUV laser-induced desorption/ablation from lithium fluoride, which is a reference large band-gap dielectric material with ionic crystalline structure. Computational framework was proposed and employed here for the reconstruction of plume expansion dynamics induced by the irradiation of lithium fluoride targets. The morphology of experimentally observed desorption/ablation craters were reproduced using idealized representation (two-zone approximation of the laser fluence profile. The calculation of desorption/ablation rate was performed using one-dimensional thermomechanic model (XUV-ABLATOR code taking into account laser heating and surface evaporation of the lithium fluoride target occurring on a nanosecond timescale. This step was followed by the application of two-dimensional hydrodynamic solver for description of laser-produced plasma plume expansion dynamics. The calculated plume lengths determined by numerical simulations were compared with a simple adiabatic expansion (blast-wave model.

  11. Production and Characterization of Femtosecond-Laser-Induced Air Plasma

    National Research Council Canada - National Science Library

    Armbruster, David R

    2008-01-01

    .... A beam expander was used to expand the beam to a diameter of approximately 6.5 mm, and the beam was focused through a 25 mm focal length achromatic lens to produce laser-induced plasma in ambient air...

  12. MR imaging and histopathologic correlations of thermal injuries induced by interstitial laser applications

    International Nuclear Information System (INIS)

    Anzai, Y.; Lufkin, R.B.; Castro, D.J.; Farahani, K.; Chen, H.W.; Hirchowiz, S.

    1991-01-01

    Interstitial laser phototherapy for deep-seated tumors may become an attractive therapeutic modality when a noninvasive, accurate monitoring system is developed. In this paper, to devaluate the ability of MR imaging to differentiate reversible and irreversible thermal injuries induced by laser therapy, the precise correlation of MR and histopathologic findings are investigated in the in vivo model. Nd:YAG lasers were applied to normal musculature of rabbits, and MR examinations were performed immediately after laser exposure and followed up for up to 10 weeks. The sequential MR images were correlated with histopathologic findings. T2-weighted MR imaging clearly showed laser-induced thermal injuries on any postoperative day. MR imaging of acute thermal injuries showed a central cavity, low-signal zone of coagulative necrosis and a peripheral high-signal layer of interstitial edema. The infiltration of neutrophils followed by fibrovascular response was identified on the marginal edema layer after 6 postoperative days

  13. About a fuel for burnup reactor of periodical pulsed nuclear pumped laser

    International Nuclear Information System (INIS)

    Volkov, A.I.; Lukin, A.V.; Magda, L.E.; Magda, E.P.; Pogrebov, I.S.; Putnikov, I.S.; Khmelnitsky, D.V.; Scherbakov, A.P.

    1998-01-01

    A physical scheme of burnup reactor for a Periodic Pulsed Nuclear Pumped Laser was supposed. Calculations of its neutron physical parameters were made. The general layout and construction of basic elements of the reactor are discussed. The requirements for the fuel and fuel elements are established. (author)

  14. Application of a compact diode pumped solid-state laser source for quantitative laser-induced breakdown spectroscopy analysis of steel

    Science.gov (United States)

    Tortschanoff, Andreas; Baumgart, Marcus; Kroupa, Gerhard

    2017-12-01

    Laser-induced breakdown spectroscopy (LIBS) technology holds the potential for onsite real-time measurements of steel products. However, for a mobile and robust LIBS measurement system, an adequate small and ruggedized laser source is a key requirement. In this contribution, we present tests with our compact high-power laser source, which, initially, was developed for ignition applications. The CTR HiPoLas® laser is a robust diode pumped solid-state laser with a passive Q-switch with dimensions of less than 10 cm3. The laser generates 2.5-ns pulses with 30 mJ at a maximum continuous repetition rate of about 30 Hz. Feasibility of LIBS experiments with the laser source was experimentally verified with steel samples. The results show that the laser with its current optical output parameters is very well-suited for LIBS measurements. We believe that the miniaturized laser presented here will enable very compact and robust portable high-performance LIBS systems.

  15. Applications of laser-induced gratings to spectroscopy and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, E.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program has traditionally emphasized two principal areas of research. The first is the spectroscopic characterization of large-amplitude motion on the ground-state potential surface of small, transient molecules. The second is the reactivity of carbonaceous clusters and its relevance to soot and fullerene formation in combustion. Motivated initially by the desire to find improved methods of obtaining stimulated emission pumping (SEP) spectra of transients, most of our recent work has centered on the use of laser-induced gratings or resonant four-wave mixing in free-jet expansions. These techniques show great promise for several chemical applications, including molecular spectroscopy and photodissociation dynamics. The author describes recent applications of two-color laser-induced grating spectroscopy (LIGS) to obtain background-free SEP spectra of transients and double resonance spectra of nonfluorescing species, and the use of photofragment transient gratings to probe photodissociation dynamics.

  16. Laser-induced reaction alumina coating on ceramic composite

    Science.gov (United States)

    Xiao, Chenghe

    Silicon carbide ceramics are susceptible to corrosion by certain industrial furnace environments. It is also true for a new class of silicon carbide-particulate reinforced alumina-matrix composite (SiCsb(P)Alsb2Osb3) since it contains more than 55% of SiC particulate within the composite. This behavior would limit the use of SiCsb(P)Alsb2Osb3 composites in ceramic heat exchangers. Because oxide ceramics corrode substantially less in the same environments, a laser-induced reaction alumina coating technique has been developed for improving corrosion resistance of the SiCsb(P)Alsb2Osb3 composite. Specimens with and without the laser-induced reaction alumina coating were subjected to corrosion testing at 1200sp°C in an air atmosphere containing Nasb2COsb3 for 50 ˜ 200 hours. Corroded specimens were characterized via x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The uncoated SiCsbP/Alsb2Osb3 composite samples experienced an initial increase in weight during the exposure to Nasb2COsb3 at 1200sp°C due to the oxidation of residual aluminum metal in the composite. There was no significant weight change difference experienced during exposure times between 50 and 200 hours. The oxidation layer formed on the as-received composite surface consisted of Si and Alsb2Osb3 (after washing with a HF solution). The oxidation layer grew outward and inward from the original surface of the composite. The growth rate in the outward direction was faster than in the inward direction. The formation of the Si/Alsb2Osb3 oxidation layer on the as-received composite was nonuniform, and localized corrosion was observed. The coated samples experienced very little mass increase. The laser-induced reaction alumina coating effectively provided protection for the SiCsbP/Alsb2Osb3 composite by keeping the corrodents from contacting the composite and by the formation of some refractory compounds such as Nasb2OAlsb2Osb3SiOsb2 and Nasb2Alsb{22}Osb

  17. Microstructure and mechanical characteristics of a laser welded joint in SA508 nuclear pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wei, E-mail: wei.guo-2@manchester.ac.uk [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom); Dong, Shiyun [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom); Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Guo, Wei; Francis, John A.; Li, Lin [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom)

    2015-02-11

    SA508 steels are typically used in civil nuclear reactors for critical components such as the reactor pressure vessel. Nuclear components are commonly joined using arc welding processes, but with design lives for prospective new build projects exceeding 60 years, new welding technologies are being sought. In this exploratory study, for the first time, autogenous laser welding was carried out on 6 mm thick SA508 Cl.3 steel sheets using a 16 kW fiber laser system operating at a power of 4 kW. The microstructure and mechanical properties (including microhardness, tensile strength, elongation, and Charpy impact toughness) were characterized and the microstructures were compared with those produced through arc welding. A three-dimensional transient model based on a moving volumetric heat source model was also developed to simulate the laser welding thermal cycles in order to estimate the cooling rates included by the process. Preliminary results suggest that the laser welding process can produce welds that are free of macroscopic defects, while the strength and toughness of the laser welded joint in this study matched the values that were obtained for the parent material in the as-welded condition.

  18. Femtosecond self-reconfiguration of laser-induced plasma patterns in dielectrics

    Science.gov (United States)

    Déziel, Jean-Luc; Dubé, Louis J.; Messaddeq, Sandra H.; Messaddeq, Younès; Varin, Charles

    2018-05-01

    Laser-induced modification of transparent solids by intense femtosecond laser pulses allows fast integration of nanophotonic and nanofluidic devices with controlled optical properties. Experimental observations suggest that the local and dynamic nature of the interactions between light and the transient plasma plays an important role during fabrication. Current analytical models neglect these aspects and offer limited coverage of nanograting formation on dielectric surfaces. In this paper, we present a self-consistent dynamic treatment of the plasma buildup and its interaction with light within a three-dimensional electromagnetic framework. The main finding of this work is that local light-plasma interactions are responsible for the reorientation of laser-induced periodic plasma patterns with respect to the incident light polarization, when a certain energy density threshold is reached. Plasma reconfiguration occurs within a single laser pulse, on a femtosecond time scale. Moreover, we show that the reconfigured subwavelength plasma structures actually grow into the bulk of the sample, which agrees with the experimental observations of self-organized volume nanogratings. We find that mode coupling of the incident and transversely scattered light with the periodic plasma structures is sufficient to initiate the growth and self-organization of the pattern inside the medium with a characteristic half-wavelength periodicity.

  19. Nanosecond-laser induced crosstalk of CMOS image sensor

    Science.gov (United States)

    Zhu, Rongzhen; Wang, Yanbin; Chen, Qianrong; Zhou, Xuanfeng; Ren, Guangsen; Cui, Longfei; Li, Hua; Hao, Daoliang

    2018-02-01

    The CMOS Image Sensor (CIS) is photoelectricity image device which focused the photosensitive array, amplifier, A/D transfer, storage, DSP, computer interface circuit on the same silicon substrate[1]. It has low power consumption, high integration,low cost etc. With large scale integrated circuit technology progress, the noise suppression level of CIS is enhanced unceasingly, and its image quality is getting better and better. It has been in the security monitoring, biometrice, detection and imaging and even military reconnaissance and other field is widely used. CIS is easily disturbed and damaged while it is irradiated by laser. It is of great significance to study the effect of laser irradiation on optoelectronic countermeasure and device for the laser strengthening resistance is of great significance. There are some researchers have studied the laser induced disturbed and damaged of CIS. They focused on the saturation, supersaturated effects, and they observed different effects as for unsaturation, saturation, supersaturated, allsaturated and pixel flip etc. This paper research 1064nm laser interference effect in a typical before type CMOS, and observring the saturated crosstalk and half the crosstalk line. This paper extracted from cmos devices working principle and signal detection methods such as the Angle of the formation mechanism of the crosstalk line phenomenon are analyzed.

  20. Two methods for nuclear spin determination in collinear laser spectroscopy: classical r.f. magnetic resonance and observation of the Larmor precession

    International Nuclear Information System (INIS)

    Bendali, N.; Duong, H.T.; Saint-Jalm, J.M.; Vialle, J.L.

    1984-01-01

    Measurement of nuclear spin in the collinear laser spectroscopy method has been investigated using a fast sodium atomic beam excited collinearly by a C.W. single mode dye laser beam. The atomic magnetic moments are first aligned by optical pumping process, then they interact with a static magnetic field H 0 . The magnetic alignment of the atomic system just at the exit of the magnetic field is monitored by the laser induced fluorescence. Upon varying the amplitude of H 0 , the fluorescence signal presents a fringed structure. This structure is due to the Larmor precession of the aligned magnetic moments around H 0 , and therefore it is a signature of the spin involved. The modulation patterns corresponding to different relative orientations of H 0 and light polarization direction, are fitted by an analytical formula. In a second step, a classical magnetic resonance experiment with a static magnetic field and a radiofrequency field has been performed. The monocinetic character of our fast atomic beam allowed us to observe, even at high r.f. power, resonances line shapes in agreement with the Majorana formula

  1. Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages.

    Science.gov (United States)

    Jones, Christopher P; Brenner, Ceri M; Stitt, Camilla A; Armstrong, Chris; Rusby, Dean R; Mirfayzi, Seyed R; Wilson, Lucy A; Alejo, Aarón; Ahmed, Hamad; Allott, Ric; Butler, Nicholas M H; Clarke, Robert J; Haddock, David; Hernandez-Gomez, Cristina; Higginson, Adam; Murphy, Christopher; Notley, Margaret; Paraskevoulakos, Charilaos; Jowsey, John; McKenna, Paul; Neely, David; Kar, Satya; Scott, Thomas B

    2016-11-15

    A small scale sample nuclear waste package, consisting of a 28mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500keV), with a source size of <0.5mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30cm(2) scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned. Copyright © 2016. Published by Elsevier B.V.

  2. Femtosecond laser-induced decomposition in triazenepolymer thin films

    International Nuclear Information System (INIS)

    Bonse, J.; Wiggins, S.M.; Solis, J.; Lippert, T.; Sturm, H.

    2005-01-01

    The damage induced by ultrashort, 130 fs, near-infrared, 800 nm, Ti:sapphire laser pulses in 1 μm thick triazenepolymer films on glass substrates has been investigated. Real-time reflectivity measurements with a ps-resolution streak camera and a ns-resolution photodiode set-up have been performed to study in situ the structural transformation dynamics upon single-pulse excitation with laser fluences above the threshold of permanent damage. Scanning force microscopy has been used to probe ex situ the corresponding surface topography of the ablated spots. Modulated lateral force microscopy (M-LFM) has been applied to observe alterations of the local friction properties within and around the irradiated areas

  3. Preliminary studies of laser-induced breakdown spectrometry for the determination of Ba, Cd, Cr and Pb in toys

    International Nuclear Information System (INIS)

    Godoi, Quienly; Santos, Dario; Nunes, Lidiane C.; Leme, Flavio O.; Rufini, Iolanda A.; Agnelli, Jose A.M.; Trevizan, Lilian C.; Krug, Francisco J.

    2009-01-01

    The performance of laser-induced breakdown spectrometry (LIBS) for the determination of Ba, Cd, Cr and Pb in toys has been evaluated by using a Nd:YAG laser operating at 1064 nm and an Echelle spectrometer with intensified charge-coupled device detector. Samples were purchased in different cities of Sao Paulo State market and analyzed directly without sample preparation. Laser-induced breakdown spectrometry experimental conditions (number of pulses, delay time, integration time gate and pulse energy) were optimized by using a Doehlert design. Laser-induced breakdown spectrometry signals correlated reasonably well with inductively coupled plasma optical emission spectrometry (ICP OES) concentrations after microwave-assisted acid digestion of selected samples. Thermal analysis was used for polymer identification and scanning electron microscopy to visualize differences in crater geometry of different polymers employed for toy fabrication. Results indicate that laser-induced breakdown spectrometry can be proposed as a rapid screening method for investigation of potentially toxic elements in toys. The unique application of laser-induced breakdown spectrometry for identification of contaminants in successive layers of ink and polymer is also demonstrated.

  4. Edaravone is a free radical scavenger that protects against laser-induced choroidal neovascularization in mice and common marmosets.

    Science.gov (United States)

    Masuda, Tomomi; Shimazawa, Masamitsu; Takata, Shinsuke; Nakamura, Shinsuke; Tsuruma, Kazuhiro; Hara, Hideaki

    2016-05-01

    Choroidal neovascularization (CNV) is a main characteristic in exudative type of age-related macular degeneration (AMD). Our study aimed to evaluate the effects of edaravone, a free radical scavenger on laser-induced CNV. CNV was induced by laser photocoagulation to the subretinal choroidal area of mice and common marmosets. Edaravone was administered either intraperitoneally twice a day for 2 weeks or intravenously just once after laser photocoagulation. The effects of edaravone on laser-induced CNV were evaluated by fundus fluorescein angiography, CNV area measurements, and the expression of 4-hydroxy-2-nonenal (4-HNE) modified proteins, a marker of oxidative stress. Furthermore, the effects of edaravone on the production of H2O2-induced reactive oxygen species (ROS) and vascular endothelial growth factor (VEGF)-induced cell proliferation were evaluated using human retinal pigment epithelium cells (ARPE-19) and human retinal microvascular endothelial cells, respectively. CNV areas in the edaravone-treated group were significantly smaller in mice and common marmosets. The expression of 4-HNE modified proteins was upregulated 3 h after laser photocoagulation, and intravenously administered edaravone decreased it. In in vitro studies, edaravone inhibited H2O2-induced ROS production and VEGF-induced cell proliferation. These findings suggest that edaravone may protect against laser-induced CNV by inhibiting oxidative stress and endothelial cell proliferation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Deuteron-induced reactions generated by intense lasers for PET isotope production

    Science.gov (United States)

    Kimura, Sachie; Bonasera, Aldo

    2011-05-01

    We investigate the feasibility of using laser accelerated protons/deuterons for positron emission tomography (PET) isotope production by means of the nuclear reactions 11B(p, n) 11C and 10B(d, n) 11C. The second reaction has a positive Q-value and no energy threshold. One can, therefore, make use of the lower energy part of the laser-generated deuterons, which includes the majority of the accelerated deuterons. By assuming that the deuteron spectra are similar to the proton spectra, the 11C produced from the reaction 10B(d, n) 11C is estimated to be 7.4×10 9 per laser-shot at the Titan laser at Lawrence Livermore National Laboratory. Meanwhile a high-repetition table-top laser irradiation is estimated to generate 3.5×10 711C per shot from the same reaction. In terms of the 11C activity, it is about 2×10 4 Bq per shot. If this laser delivers kHz, the activity is integrated to 1 GBq after 3 min. The number is sufficient for the practical application in medical imaging for PET.

  6. Laser induced fluorescence of biochemical for UV LIDAR application.

    Science.gov (United States)

    Gupta, L; Sharma, R C; Razdan, A K; Maini, A K

    2014-05-01

    Laser induced fluorescence spectroscopy in the ultraviolet regime has been used for the detection of biochemical through a fiber coupled CCD detector from a distance of 2 m. The effect of concentration and laser excitation energy on the fluorescence spectra of nicotinamide adenine dinucleotide (NADH) has been investigated. The signature fluorescence peak of NADH was centred about 460 nm. At lower concentration Raman peak centred at 405 nm was also observed. The origin of this peak has been discussed. Detection limit with the proposed set up is found to be 1 ppm.

  7. Fs–ns double-pulse Laser Induced Breakdown Spectroscopy of copper-based-alloys: Generation and elemental analysis of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Guarnaccio, A.; Parisi, G.P.; Mollica, D. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); De Bonis, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Teghil, R. [Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Santagata, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy)

    2014-11-01

    Evolution of nanoparticles ejected during ultra-short (250 fs) laser ablation of certified copper alloys and relative calibration plots of a fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration is presented. All work was performed in air at atmospheric pressure using certified copper-based-alloy samples irradiated by a fs laser beam and followed by a delayed perpendicular ns laser pulse. In order to evaluate possible compositional changes of the fs induced nanoparticles, it was necessary to consider, for all samples used, comparable features of the detected species. With this purpose the induced nanoparticles black-body-like emission evolution and their relative temperature decay have been studied. These data were exploited for defining the distance between the target surface and the successive ns laser beam to be used. The consequent calibration plots of minor constituents (i.e. Sn, Pb and Zn) of the certified copper-based-alloy samples have been reported by taking into account self-absorption effects. The resulting linear regression coefficients suggest that the method used, for monitoring and ruling the fs laser induced nanoparticles, could provide a valuable approach for establishing the occurrence of potential compositional changes of the detected species. All experimental data reveal that the fs laser induced nanoparticles can be used for providing a coherent composition of the starting target. In the meantime, the fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration here used can be considered as an efficient technique for compositional determination of the nanoparticles ejected during ultra-short laser ablation processes. - Highlights: • Laser induced NP continuum black-body-like emission was used for T determination. • Invariable composition of generated NPs was assumed in the range of 20 μs. • Fs-ns DP-LIBS was employed for the compositional characterization of NPs. • NPs obtained by fs

  8. Laser-induced agglomeration of gold nanoparticles dispersed in a liquid

    Science.gov (United States)

    Serkov, A. A.; Shcherbina, M. E.; Kuzmin, P. G.; Kirichenko, N. A.

    2015-05-01

    Dynamics of gold nanoparticles (NPs) ensemble in dense aqueous solution under exposure to picosecond laser radiation is studied both experimentally and theoretically. Properties of NPs are examined by means of transmission electron microscopy, optical spectroscopy, and size-measuring disk centrifuge. Theoretical investigation of NPs ensemble behavior is based on the analytical model taking into account collisions and agglomeration of particles. It is shown that in case of dense NPs colloidal solutions (above 1014 particles per milliliter) the process of laser fragmentation typical for nanosecond laser exposure turns into laser-induced agglomeration which leads to formation of the particles with larger sizes. It is shown that there is a critical concentration of NPs: at higher concentrations agglomeration rate increases tremendously. The results of mathematical simulation are in compliance with experimental data.

  9. Raman microspectrometry of laser-reshaped rabbit auricular cartilage: preliminary study on laser-induced cartilage mineralization

    Science.gov (United States)

    Heger, Michal; Mordon, Serge R.; Leroy, Gérard; Fleurisse, Laurence; Creusy, Collette

    2006-03-01

    Laser-assisted cartilage reshaping (LACR) is a relatively novel technique designed to noninvasively and permanently restructure cartilaginous tissue. It is believed that heat-induced stress relaxation, in which a temperature-mediated disruption of H2O binding is associated with conformational alterations in the proteoglycan and collagen-rich matrix, constitutes the underlying mechanism of LACR. Several reports have suggested that laser-mediated cartilage mineralization may contribute to the permanent shape change of laser-reshaped cartilage. In an effort to validate these results in the context of Er:glass LACR, we performed a preliminary Raman microspectrometric study to characterize the crystal deposits in laser-irradiated chondrocytes and extracellular matrix. For the first time, we identified intracellular calcium sulfate deposits and extracellular calcium phosphate (apatite) crystals in laser-reshaped rabbit auricular cartilage. Calcium carbonate deposits are localized in both irradiated and nonirradiated samples, suggesting that this mineral plays no role in conformational retention. In our discussion, we elaborate on the possible molecular and cellular mechanisms responsible for intra- and extracellular crystallization, and propose a novel hypothesis on the formation of apatite, inasmuch as the biological function of this mineral (providing structure and rigidity in bones and dental enamel) may be extrapolated to the permanent shape change of laser-irradiated cartilage.

  10. Review of the utilization of laser and electron beam methods in the nuclear domain

    International Nuclear Information System (INIS)

    Charissoux, C.; Bonnin, P.; Calvet, J.N.; Contre, M.

    1987-01-01

    The use of laser and electron beams by the nuclear industry for making components, fabricating fuels, waste processing, maintenance, and dismantling installations is reviewed. The advantages in welding include very rapid thermal cycles, deep weld zones with a restricted effect on surrounding material, and reduced residual stress. Surface treatments can also take advantage of these benefits. In cutting, the intrinsic advantages of the laser are completed by its high potential for robotization [fr

  11. Laser generation of proton beams for the production of short-lived positron emitting radioisotopes

    International Nuclear Information System (INIS)

    Spencer, I.; Ledingham, K.W.D.; Singhal, R.P.; McCanny, T.; McKenna, P.; Clark, E.L.; Krushelnick, K.; Zepf, M.; Beg, F.N.; Tatarakis, M.; Dangor, A.E.; Norreys, P.A.; Clarke, R.J.; Allott, R.M.; Ross, I.N.

    2001-01-01

    Protons of energies up to 37 MeV have been generated when ultra-intense lasers (up to 10 20 W cm -2 ) interact with hydrogen containing solid targets. These protons can be used to induce nuclear reactions in secondary targets to produce β + -emitting nuclei of relevance to the nuclear medicine community, namely 11 C and 13 N via (p, n) and (p,α) reactions. Activities of the order of 200 kBq have been measured from a single laser pulse interacting with a thin solid target. The possibility of using ultra-intense lasers to produce commercial amounts of short-lived positron emitting sources for positron emission tomography (PET) is discussed

  12. Laser-induced fusion of human embryonic stem cells with optical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shuxun; Wang Xiaolin; Sun Dong [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Cheng Jinping; Han Cheng, Shuk [Department of Biology and Chemistry, City University of Hong Kong (Hong Kong); Kong, Chi-Wing [Stem Cell and Regenerative Medicine Consortium, and Departments of Medicine and Physiology, LKS Faculty of Medicine, University of Hong Kong (Hong Kong); Li, Ronald A. [Stem Cell and Regenerative Medicine Consortium, and Departments of Medicine and Physiology, LKS Faculty of Medicine, University of Hong Kong (Hong Kong); Center of Cardiovascular Research, Mount Sinai School of Medicine, New York, New York 10029 (United States)

    2013-07-15

    We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

  13. Detection and Implications of Laser-Induced Raman Scattering at Astronomical Observatories

    Directory of Open Access Journals (Sweden)

    Frédéric P. A. Vogt

    2017-06-01

    Full Text Available Laser guide stars employed at astronomical observatories provide artificial wavefront reference sources to help correct (in part the impact of atmospheric turbulence on astrophysical observations. Following the recent commissioning of the 4 Laser Guide Star Facility (4LGSF on Unit Telescope 4 (UT4 of the Very Large Telescope (VLT, we characterize the spectral signature of the uplink beams from the 22-W lasers to assess the impact of laser scattering from the 4LGSF on science observations. We use the Multi-Unit Spectroscopic Explorer (MUSE optical integral field spectrograph mounted on the Nasmyth B focus of UT4 to acquire spectra at a resolution of R≅3000 of the uplink laser beams over the wavelength range of 4750 Å–9350 Å. We report the first detection of laser-induced Raman scattering by N_{2}, O_{2}, CO_{2}, H_{2}O, and (tentatively CH_{4} molecules in the atmosphere above the astronomical observatory of Cerro Paranal. In particular, our observations reveal the characteristic spectral signature of laser photons—but 480 Å to 2210 Å redder than the original laser wavelength of 5889.959 Å—landing on the 8.2-m primary mirror of UT4 after being Raman-scattered on their way up to the sodium layer. Laser-induced Raman scattering, a phenomenon not usually discussed in the astronomical context, is not unique to the observatory of Cerro Paranal, but it is common to any astronomical telescope employing a laser guide star (LGS system. It is thus essential for any optical spectrograph coupled to a LGS system to thoroughly handle the possibility of a Raman spectral contamination via a proper baffling of the instrument and suitable calibrations procedures. These considerations are particularly applicable for the HARMONI optical spectrograph on the upcoming Extremely Large Telescope (ELT. At sites hosting multiple telescopes, laser-collision-prediction tools should also account for the presence of Raman emission from the uplink laser beam

  14. Secondary emissions during fiber laser cutting of nuclear material

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, A., E-mail: beatriz.mendes.lopez@gmail.com [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Assunção, E. [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); European Federation for Welding, Joining and Cutting, Porto Salvo 2740-120 (Portugal); Pires, I. [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Quintino, L. [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); European Federation for Welding, Joining and Cutting, Porto Salvo 2740-120 (Portugal)

    2017-04-15

    The laser process has been studied for dismantling work for more than 10 years, however there is almost no data available concerning secondary emissions generated during the process. These emissions are inevitable during the laser cutting process and can have detrimental effects in human health and in the equipment. In terms of safety, for nuclear decommissioning, is crucial to point out ways of controlling the emissions of the process. This paper gives indications about the parameters to be used in order to reduce these secondary emissions and about the influence of these parameters on the particles size distribution. In general, for producing minimal dross and fume emissions the beam focus should be placed on the surface of the material. The higher percentage of secondary emissions which present higher diameter, increases approximately linearly with the stand-off distance and with the use of low air pressure.

  15. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge.

    Science.gov (United States)

    MacDonald, N A; Cappelli, M A; Hargus, W A

    2012-11-01

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s(')[1/2](1)(0)-6p(')[3/2](2) xenon atomic transition at λ = 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  16. Measurements of energetic ions produced by high-energy laser pulses by means of solid-state nuclear track detectors

    Czech Academy of Sciences Publication Activity Database

    Szydlowski, A.; Badziak, A.; Parys, P.; Wolowski, J.; Woryna, E.; Jungwirth, Karel; Králiková, Božena; Krása, Josef; Láska, Leoš; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří; Ullschmied, Jiří; Boody, F. D.; Gammino, S.; Torrisi, L.

    2004-01-01

    Roč. 7, č. 3 (2004), s. 327-332 ISSN 1093-3611 Institutional research plan: CEZ:AV0Z1010921 Keywords : iodine laser * nuclear track detectors * ions Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.194, year: 2004

  17. Laser-Induced Fluorescence Measurements within a Laboratory Hall Thruster (Postprint)

    National Research Council Canada - National Science Library

    Hargus, Jr., W. A; Cappelli, M. A

    1999-01-01

    In this paper, we describe the results of a study of laser induced fluorescence velocimetry of ionic xenon in the plume and interior acceleration channel of a laboratory Hall type thruster operating...

  18. Ultraviolet laser-induced voltage in anisotropic shale

    Science.gov (United States)

    Miao, Xinyang; Zhu, Jing; Li, Yizhang; Zhao, Kun; Zhan, Honglei; Yue, Wenzheng

    2018-01-01

    The anisotropy of shales plays a significant role in oil and gas exploration and engineering. Owing to various problems and limitations, anisotropic properties were seldom investigated by direct current resistivity methods. Here in this work, a 248 nm ultraviolet laser was employed to assess the anisotropic electrical response of a dielectric shale. Angular dependence of laser-induced voltages (V p) were obtained, with a data symmetry at the location of 180° and a ~62.2% V p anisotropy of the sample. The double-exponential functions have provided an explanation for the electrical field controlled carrier transportation process in horizontal and vertical directions. The results demonstrate that the combination of optics and electrical logging analysis (Opti-electrical Logging) is a promising technology for the investigation of unconventional reservoirs.

  19. Excimer-laser-induced activation of Mg-doped GaN layers

    International Nuclear Information System (INIS)

    Lin, Y.-J.; Liu, W.-F.; Lee, C.-T.

    2004-01-01

    In this study, we investigated the 248 nm excimer-laser-induced activation of the Mg-doped GaN layers. According to the observed photoluminescence results and the x-ray photoelectron spectroscopy measurements, we found that the dissociation of the Mg-H complexes and the formation of hydrogenated Ga vacancies (i.e., V Ga H 2 ) and/or the Ga vacancies occupied by interstitial Mg during the laser irradiation process, led to an increase in the hole concentration

  20. The influence of the laser spot size and the pulse number on laser-induced backside wet etching

    International Nuclear Information System (INIS)

    Boehme, R.; Zimmer, K.

    2005-01-01

    The laser-induced backside wet etching (LIBWE) of transparent solids at the interface to absorbing liquid is a new promising method for laser microstructuring. The influence of the laser spot size and the applied pulse number to the etch rate were investigated in detail for fused silica and two different liquids. Additional to the significant rise of the etch rate with increasing spot size considerable incubation effects have been observed at low laser fluences and pulse numbers. Based on the bubble formation during LIBWE processing, a relation between the bubble collapse time and the etch rate was ascertained. This relation fits the etch rate dependence on the spot size well. It is assumed that the deposition of decomposition products from the bubble accounts for the spot size influence the etch rate

  1. Development of pulse laser processing for mounting fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Aikihko; Shimada, Yukihiro; Yonemoto, Yukihiro; Suzuki, Hirokazu; Ishibashi, Hisayoshi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umebidai Kidugawa Kyoto 619-0215 (Japan); Applied Laser Technology Institute, Tsuruga Head Office, Japan Atomic Energy Agency, 65-20 Kizaki Tsuruga Fukui 914-8585 (Japan); Technical Research and Development Institute, Kumagai Gumi Co., Ltd., 2-1 Tsukudo, Shinjuku Tokyo 162-8557 (Japan)

    2012-07-11

    Pulse laser processing has been developed for the application of industrial plants in monitoring and maintenance. Surface cleaning by nano-second laser ablation was demonstrated for decontamination of oxide layers of Cr contained steel. Direct writing by femtosecond processing induced a Bragg grating in optical fiber to make it a seismic sensor for structural health monitoring. Adhesive cement was used to fix the seismic sensor on the surface of reactor coolant pipe material. Pulse laser processing and its related technologies were presented to overcome the severe accidents of nuclear power plants.

  2. Analysis of relaxing laser-induced plasmas by absorption spectroscopy: Toward a new quantitative diagnostic technique

    International Nuclear Information System (INIS)

    Ribiere, M.; Cheron, B.G.

    2010-01-01

    Broad-band near UV absorption spectroscopy was used to analyze atmospheric laser-induced plasmas formed on metallic and refractory targets. When the common emission spectroscopy only provides the density of the radiating atomic excited states, the technique reported in this paper is able to achieve high spatial resolution in the measurement of absolute number densities in expanding laser-induced plasmas. The reliability and the versatility of this technique, which is based on the comparison between results of the numerical integration of the radiative transfer equation and experimental spectra, were tested on different targets. The evolutions in time and space of the absolute population of the plasma species originating from metallic alloys (Al-Mg and Cu-Ni) and refractory materials (C/SiC) were achieved over large time scales. Owing to its accuracy, this absorption technique (that we call 'LIPAS' for Laser Induced Plasma Absorption Spectroscopy) should bring a new and enhanced support to the validation of collisional-radiative models attempting to provide reliable evolutions of laser-induced plasmas.

  3. Laser induced local modification of magnetic domain in Co/Pt multilayer

    International Nuclear Information System (INIS)

    Talapatra, A.; Mohanty, J.

    2016-01-01

    Manipulation of magnetic system by the use of laser has drawn the attention of contemporary research. We demonstrate here the modification of magnetic domain in perpendicularly magnetized Co/Pt multilayer by using ultrashort laser pulse. The as-prepared sample shows an out-of-plane saturation magnetic field of 803.4 mT and almost zero remanence with a labyrinth-like domain pattern at room temperature. Atomistic simulation showed that interaction with femto-second laser results in demagnetization of the material in 200 fs followed by a slower recovery. As it indicates a net loss in magnetization, so magnetic force microscopy is carried out to investigate the equilibrium state after the system is relaxed. Demagnetized random domains appeared at the centre of the laser spot with having a rim at the boundary which signifies a deterministic switching with respect to the neighbouring area. Rotation of domains at the central area with the application of small transverse field (100 mT) proves the region to be magnetically weaker. Systematic 3D micromagnetic simulation has been performed to model the laser induced change by selective reduction of anisotropy which is discussed in detail. This shows shrinking of domains to a near circular pattern to minimize the magnetostatic energy. 50% reduction in anisotropy energy is observed with increasing the total energy of the system and a sharp increase in demagnetization energy also takes place simultaneously. This also satisfies the anisotropy in domain rotation with the application of transverse field. - Highlights: • Laser induced magnetization dynamics. • Local manipulation of magnetic domains. • Deterministic switching of domains with laser. • Modeling magnetic domain structure with local anisotropy distribution.

  4. Laser induced local modification of magnetic domain in Co/Pt multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Talapatra, A., E-mail: ph13p1001@iith.ac.in; Mohanty, J., E-mail: jmohanty@iith.ac.in

    2016-11-15

    Manipulation of magnetic system by the use of laser has drawn the attention of contemporary research. We demonstrate here the modification of magnetic domain in perpendicularly magnetized Co/Pt multilayer by using ultrashort laser pulse. The as-prepared sample shows an out-of-plane saturation magnetic field of 803.4 mT and almost zero remanence with a labyrinth-like domain pattern at room temperature. Atomistic simulation showed that interaction with femto-second laser results in demagnetization of the material in 200 fs followed by a slower recovery. As it indicates a net loss in magnetization, so magnetic force microscopy is carried out to investigate the equilibrium state after the system is relaxed. Demagnetized random domains appeared at the centre of the laser spot with having a rim at the boundary which signifies a deterministic switching with respect to the neighbouring area. Rotation of domains at the central area with the application of small transverse field (100 mT) proves the region to be magnetically weaker. Systematic 3D micromagnetic simulation has been performed to model the laser induced change by selective reduction of anisotropy which is discussed in detail. This shows shrinking of domains to a near circular pattern to minimize the magnetostatic energy. 50% reduction in anisotropy energy is observed with increasing the total energy of the system and a sharp increase in demagnetization energy also takes place simultaneously. This also satisfies the anisotropy in domain rotation with the application of transverse field. - Highlights: • Laser induced magnetization dynamics. • Local manipulation of magnetic domains. • Deterministic switching of domains with laser. • Modeling magnetic domain structure with local anisotropy distribution.

  5. Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Christopher P., E-mail: cj0810@bristol.ac.uk [Interface Analysis Centre, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Brenner, Ceri M. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Stitt, Camilla A. [Interface Analysis Centre, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Armstrong, Chris; Rusby, Dean R. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Mirfayzi, Seyed R. [Centre for Plasma Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Wilson, Lucy A. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Alejo, Aarón; Ahmed, Hamad [Centre for Plasma Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Allott, Ric [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Butler, Nicholas M.H. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Clarke, Robert J.; Haddock, David; Hernandez-Gomez, Cristina [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Higginson, Adam [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Murphy, Christopher [Department of Physics, University of York, York YO10 5DD (United Kingdom); Notley, Margaret [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Paraskevoulakos, Charilaos [Interface Analysis Centre, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Jowsey, John [Ground Floor North B582, Sellafield Ltd, Seascale, Cumbria CA20 1PG (United Kingdom); and others

    2016-11-15

    Highlights: • X-ray generation was achieved via laser interaction with a tantalum thin foil target. • Picosecond X-ray pulse from a sub-mm spot generated high resolution images. • MeV X-ray emission is possible, permitting analysis of full scale waste containers. • In parallel neutron emission of 10{sup 7}–10{sup 9} neutrons per steradian per pulse was attained. • Development of a 10 Hz diode pumped laser system for waste monitoring is envisioned. - Abstract: A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm{sup 2} scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned.

  6. Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

    International Nuclear Information System (INIS)

    Jones, Christopher P.; Brenner, Ceri M.; Stitt, Camilla A.; Armstrong, Chris; Rusby, Dean R.; Mirfayzi, Seyed R.; Wilson, Lucy A.; Alejo, Aarón; Ahmed, Hamad; Allott, Ric; Butler, Nicholas M.H.; Clarke, Robert J.; Haddock, David; Hernandez-Gomez, Cristina; Higginson, Adam; Murphy, Christopher; Notley, Margaret; Paraskevoulakos, Charilaos; Jowsey, John

    2016-01-01

    Highlights: • X-ray generation was achieved via laser interaction with a tantalum thin foil target. • Picosecond X-ray pulse from a sub-mm spot generated high resolution images. • MeV X-ray emission is possible, permitting analysis of full scale waste containers. • In parallel neutron emission of 10"7–10"9 neutrons per steradian per pulse was attained. • Development of a 10 Hz diode pumped laser system for waste monitoring is envisioned. - Abstract: A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm"2 scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned.

  7. Study on VCSEL laser heating chip in nuclear magnetic resonance gyroscope

    Science.gov (United States)

    Liang, Xiaoyang; Zhou, Binquan; Wu, Wenfeng; Jia, Yuchen; Wang, Jing

    2017-10-01

    In recent years, atomic gyroscope has become an important direction of inertial navigation. Nuclear magnetic resonance gyroscope has a stronger advantage in the miniaturization of the size. In atomic gyroscope, the lasers are indispensable devices which has an important effect on the improvement of the gyroscope performance. The frequency stability of the VCSEL lasers requires high precision control of temperature. However, the heating current of the laser will definitely bring in the magnetic field, and the sensitive device, alkali vapor cell, is very sensitive to the magnetic field, so that the metal pattern of the heating chip should be designed ingeniously to eliminate the magnetic field introduced by the heating current. In this paper, a heating chip was fabricated by MEMS process, i.e. depositing platinum on semiconductor substrates. Platinum has long been considered as a good resistance material used for measuring temperature The VCSEL laser chip is fixed in the center of the heating chip. The thermometer resistor measures the temperature of the heating chip, which can be considered as the same temperature of the VCSEL laser chip, by turning the temperature signal into voltage signal. The FPGA chip is used as a micro controller, and combined with PID control algorithm constitute a closed loop control circuit. The voltage applied to the heating resistor wire is modified to achieve the temperature control of the VCSEL laser. In this way, the laser frequency can be controlled stably and easily. Ultimately, the temperature stability can be achieved better than 100mK.

  8. The significant role of plasmonic effects in femtosecond laser-induced grating fabrication on the nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Min; Zhao, Fuli [State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, 510275 (China); Cheng, Ya; Xu, Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, 201800 (China)

    2013-02-15

    Nowadays, plasmonics aiming at manipulating light beyond the diffraction limit has aroused great interest on account of the promise of nanoscale optical devices. Generally, the ability to break diffraction barrier is achieved via controlling surface plasmons (SPs) on artificial structures as products of human ingenuity. Here, nevertheless, it is demonstrated that in short-pulse laser ablation ultrafast active plasmonic structures spontaneously generate by virtue of plasmonic effects rather than human will. First, with the experimental results on ZnO, Si, and GaAs, explicit evidence is provided for the grating-splitting phenomenon that acts as a direct route for the formation of laser-induced deep-subwavelength gratings. The splitting mechanism can break through the diffraction limit and push laser-induced structures towards the nanoscale. Then, through comprehensive numerical studies based on the viewpoint of plasmonics, it can be confirmed that the grating-splitting phenomenon originates in the conversion of SP modes from the resonant to the nonresonant mode and further to the inphase or antiphase asymmetric mode. In short, plasmonic effects play an important role in ultrafast laser-induced grating splitting towards the nanoscale, which will provide new insights into the mechanisms of ultrafast laser-induced nanostructures. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. The significant role of plasmonic effects in femtosecond laser-induced grating fabrication on the nanoscale

    International Nuclear Information System (INIS)

    Huang, Min; Zhao, Fuli; Cheng, Ya; Xu, Zhizhan

    2013-01-01

    Nowadays, plasmonics aiming at manipulating light beyond the diffraction limit has aroused great interest on account of the promise of nanoscale optical devices. Generally, the ability to break diffraction barrier is achieved via controlling surface plasmons (SPs) on artificial structures as products of human ingenuity. Here, nevertheless, it is demonstrated that in short-pulse laser ablation ultrafast active plasmonic structures spontaneously generate by virtue of plasmonic effects rather than human will. First, with the experimental results on ZnO, Si, and GaAs, explicit evidence is provided for the grating-splitting phenomenon that acts as a direct route for the formation of laser-induced deep-subwavelength gratings. The splitting mechanism can break through the diffraction limit and push laser-induced structures towards the nanoscale. Then, through comprehensive numerical studies based on the viewpoint of plasmonics, it can be confirmed that the grating-splitting phenomenon originates in the conversion of SP modes from the resonant to the nonresonant mode and further to the inphase or antiphase asymmetric mode. In short, plasmonic effects play an important role in ultrafast laser-induced grating splitting towards the nanoscale, which will provide new insights into the mechanisms of ultrafast laser-induced nanostructures. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Laser induced breakdown detection for the assessment of colloid mediated radionuclide migration

    CERN Document Server

    Walther, C; Hauser, W; Kim, J I; Scherbaum, F J

    2002-01-01

    Colloids play an important role in the transport of pollutants in the environment. Harmful substances can undergo transport over large distances if bound to colloids in aqueous surrounding. One important example is the migration of Pu(IV) at unexpectedly high rates over several miles at a Nevada nuclear detonation test site. For long term safety assessments of radioactive waste repositories, it is hence crucial to know about the amount, size distribution and chemical composition of colloids in the ground water. Standard methods (e.g. light scattering) can be applied for high concentrations and large sizes of particles. Colloids smaller than 50 nm, however, are detected with very low efficiency. Laser induced breakdown detection (LIBD) can fill this gap. A new instrumentation is presented, which as compared to previous instruments, opens up a much wider operational dynamic range, now covering three orders of magnitude in size (5-1000 nm) and seven orders of magnitude in particle concentration (1 ppt - several ...

  11. The Spectral Emission Characteristics of Laser Induced Plasma on Tea Samples

    International Nuclear Information System (INIS)

    Zheng Peichao; Shi Minjie; Wang Jinmei; Liu Hongdi

    2015-01-01

    Laser induced breakdown spectroscopy (LIBS) provides a useful technique for food security as well as determining nutrition contents. In this paper, optical emission studies of laser induced plasma on commercial tea samples were carried out. The spectral intensities of Mg, Mn, Ca, Al, C and CN vibration bands varying with laser energy and the detection delay time of an intensified charge coupled device were studied. In addition, the relative concentrations of six microelements, i.e., Mg, Mn, Ca, Al, Na and K, were analyzed semi-quantitatively as well as H, for four kinds of tea samples. Moreover, the plasma parameters were explored, including electron temperature and electron number density. The electron temperature and electron number density were around 11000 K and 10 17 cm −3 , respectively. The results show that it is reasonable to consider the LIBS technique as a new method for analyzing the compositions of tea leaf samples. (paper)

  12. Nuclear Reactions Studies in Laser-Plasmas at the forthcoming ELI-NP facilities

    Science.gov (United States)

    Lanzalone, G.; Muoio, A.; Altana, C.; Frassetto, M.; Malferrari, L.; Mascali, D.; Odorici, F.; Tudisco, S.; Gizzi, L. A.; Labate, L.; Puglia, S. M. R.; Trifirò, A.

    2018-05-01

    This work aim to prepare a program of studies on nuclear physics and astrophysics, which will be conducted at the new ELI-NP Laser facility, which actually is under construction in Bucharest, Romania. For the arguments treated, such activity has required also a multidisciplinary approach and knowledge in the fields of nuclear physics, astrophysics, laser and plasma physics join with also some competences on solid state physics related to the radiation detection. A part of this work has concerned to the experimental test, which have been performed in several laboratories and in order to study and increase the level of knowledge on the different parts of the project. In particular have been performed studies on the laser matter interaction at the ILIL laboratory of Pisa Italy and at the LENS laboratory in Catania, where (by using different experimental set-ups) has been investigated some key points concerning the production of the plasma stream. Test has been performed on several target configurations in terms of: composition, structure and size. All the work has been devoted to optimize the conditions of target in order to have the best performance on the production yields and on energies distribution of the inner plasma ions. A parallel activity has been performed in order to study the two main detectors, which will constitute the full detections system, which will be installed at the ELI-NP facility.

  13. Role of Laser Power, Wavelength, and Pulse Duration in Laser Assisted Tin-Induced Crystallization of Amorphous Silicon

    Directory of Open Access Journals (Sweden)

    V. B. Neimash

    2018-01-01

    Full Text Available This work describes tin-induced crystallization of amorphous silicon studied with Raman spectroscopy in thin-film structures Si-Sn-Si irradiated with pulsed laser light. We have found and analyzed dependencies of the nanocrystals’ size and concentration on the laser pulse intensity for 10 ns and 150 μm duration laser pulses at the wavelengths of 535 nm and 1070 nm. Efficient transformation of the amorphous silicon into a crystalline phase during the 10 ns time interval of the acting laser pulse in the 200 nm thickness films of the amorphous silicon was demonstrated. The results were analyzed theoretically by modeling the spatial and temporal distribution of temperature in the amorphous silicon sample within the laser spot location. Simulations confirmed importance of light absorption depth (irradiation wavelength in formation and evolution of the temperature profile that affects the crystallization processes in irradiated structures.

  14. Titanium monoxide spectroscopy following laser-induced optical breakdown

    International Nuclear Information System (INIS)

    Parigger, Christian G.; Woods, Alexander C.; Keszler, Anna; Nemes, László; Hornkohl, James O.

    2012-01-01

    This work investigates Titanium Monoxide (TiO) in ablation-plasma by employing laser-induced breakdown spectroscopy (LIBS) with 1 to 10 TW/cm 2 irradiance, pulsed, 13 nanosecond, Q-switched Nd:YAG laser radiation at the fundamental wavelength of 1064 nm. The analysis of TiO is based on our first accurate determination of transition line strengths for selected TiO A-X, B-X, and E-X transitions, particularly TiO A-X γ and B-X γ′ bands. Electric dipole line strengths for the A 3 Φ-X 3 δ and B 3 Π-X 3 δ bands of TiO are computed. The molecular TiO spectra are observed subsequent to laser-induced breakdown (LIB). We discuss analysis of diatomic molecular spectra that may occur simultaneously with spectra originating from atomic species. Gated detection is applied to investigate the development in time of the emission spectra following LIB. Collected emission spectra allow one to infer micro-plasma parameters such as temperature and electron density. Insight into the state of the micro-plasma is gained by comparing measurements with predictions of atomic and molecular spectra. Nonlinear fitting of recorded and computed diatomic spectra provides the basis for molecular diagnostics, while atomic species may overlap and are simultaneously identified. Molecular diagnostic approaches similar to TiO have been performed for diatomic molecules such as AlO, C 2 , CN, CH, N 2 , NH, NO and OH.

  15. Mechanisms of two-color laser-induced field-free molecular orientation.

    Science.gov (United States)

    Spanner, Michael; Patchkovskii, Serguei; Frumker, Eugene; Corkum, Paul

    2012-09-14

    Two mechanisms of two-color (ω+2ω) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g., on the order of ≳0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanisms lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally.

  16. Measurement of nuclear moments and radii by collinear laser spectroscopy

    CERN Multimedia

    Geithner, W R; Lievens, P; Kotrotsios, G; Silverans, R; Kappertz, S

    2002-01-01

    %IS304 %title\\\\ \\\\Collinear laser spectroscopy on a fast beam has proven to be a widely applicable and very efficient tool for measurements of changes in mean square nuclear charge radii, nuclear spins, magnetic dipole and electric quadrupole moments. Recent developments of extremely sensitive non-optical detection schemes enabled for some elements the extension of the measurements towards the very short-lived isotopes in the far wings of the ISOLDE production curves. The gain in sensitivity opens up new perspectives, particularly for measurements on lighter nuclei whose ground-state properties can be interpreted by large scale microscopic calculations instead of the more phenomenologic models used for heavier nuclei.\\\\ \\\\ For the sequence of argon isotopes $^{32-40}$Ar and $^{46}$Ar isotope shifts and nuclear moments were measured by optical pumping followed by state selective collisional ionization and detection of the $\\beta$-decay. Similarly, the low-background $\\alpha$-detection was used to extend earlie...

  17. Ion and laser beam induced metastable alloy formation

    International Nuclear Information System (INIS)

    Westendorp, J.F.M.

    1986-01-01

    This thesis deals with ion and laser beam induced thin film mixing. It describes the development of an Ultra High Vacuum apparatus for deposition, ion irradiation and in situ analysis of thin film sandwiches. This chamber has been developed in close collaboration with High Voltage Engineering Europa. Thin films can be deposited by an e-gun evaporator. The atom flux is monitored by a quadrupole mass spectrometer. A comparison is made between ion beam and laser mixing of Cu with Au and Cu with W. The comparison provides a better understanding of the relative importance of purely collisional mixing, the role of thermodynamic effects and the contribution of diffusion due to defect generation and migration. (Auth.)

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  19. Study of early laser-induced plasma dynamics: Transient electron density gradients via Thomson scattering and Stark Broadening, and the implications on laser-induced breakdown spectroscopy measurements

    International Nuclear Information System (INIS)

    Diwakar, P.K.; Hahn, D.W.

    2008-01-01

    To further develop laser-induced breakdown spectroscopy (LIBS) as an analytical technique, it is necessary to better understand the fundamental processes and mechanisms taking place during the plasma evolution. This paper addresses the very early plasma dynamics (first 100 ns) using direct plasma imaging, light scattering, and transmission measurements from a synchronized 532-nm probe laser pulse. During the first 50 ns following breakdown, significant Thomson scattering was observed while the probe laser interacted with the laser-induced plasma. The Thomson scattering was observed to peak 15-25 ns following plasma initiation and then decay rapidly, thereby revealing the highly transient nature of the free electron density and plasma equilibrium immediately following breakdown. Such an intense free electron density gradient is suggestive of a non-equilibrium, free electron wave generated by the initial breakdown and growth processes. Additional probe beam transmission measurements and electron density measurements via Stark broadening of the 500.1-nm nitrogen ion line corroborate the Thomson scattering observations. In concert, the data support the finding of a highly transient plasma that deviates from local thermodynamic equilibrium (LTE) conditions during the first tens of nanoseconds of plasma lifetime. The implications of this early plasma transient behavior are discussed in the context of plasma-analyte interactions and the role on LIBS measurements

  20. Dynamical chaos and induced nuclear fission

    Energy Technology Data Exchange (ETDEWEB)

    Bolotin, Yu L; Krivoshej, I V

    1985-01-01

    It is shown that the exponential instability of trajectories, which arises at negative curvature of the potential energy surface, leads to diffusion of the image point through the barrier and determines real time delays in induced nuclear fission.

  1. Formation of organic layer on femtosecond laser-induced periodic surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Yasumaru, Naoki, E-mail: yasuma@fukui-nct.ac.jp [National Institute of Technology, Fukui College, Sabae, Fukui 916-8507 (Japan); Sentoku, Eisuke [National Institute of Technology, Fukui College, Sabae, Fukui 916-8507 (Japan); Kiuchi, Junsuke [Eyetec Co., Ltd., Sabae, Fukui 916-0016 (Japan)

    2017-05-31

    Highlights: • Surface analyses of two types of femtosecond laser-induced periodic surface structures (LIPSS) on titanium were conducted. • The parallel-oriented ultrafine LIPSS showed the almost same roughness and chemical states as the non-irradiated Ti surface. • The well-known perpendicular-oriented LIPSS were typically covered with an organic layer similar to a cellulose derivative. - Abstract: Two types of laser-induced periodic surface structures (LIPSS) formed on titanium by femtosecond (fs) laser pulses (λ = 800 nm, τ = 180 fs, ν = 1 kHz) in air were investigated experimentally. At a laser fluence F above the ablation threshold, LIPSS with a minimum mean spacing of D < λ⁄2 were observed perpendicular to the laser polarization direction. In contrast, for F slightly below than the ablation threshold, ultrafine LIPSS with a minimum value of D < λ/10 were formed parallel to the polarization direction. The surface roughness of the parallel-oriented LIPSS was almost the same as that of the non-irradiated surface, unlike the high roughness of the perpendicular-oriented LIPSS. In addition, although the surface state of the parallel-oriented LIPSS was the same as that of the non-irradiated surface, the perpendicular-oriented LIPSS were covered with an organic thin film similar to a cellulose derivative that cannot be easily formed by conventional chemical synthesis. The results of these surface analyses indicate that these two types of LIPSS are formed through different mechanisms. This fs-laser processing technique may become a new technology for the artificial synthesis of cellulose derivatives.

  2. Pico- and femtosecond laser-induced crosslinking of protein microstructures: evaluation of processability and bioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Turunen, S; Kaepylae, E; Kellomaeki, M [Tampere University of Technology, Department of Biomedical Engineering, PO Box 692, 33101 Tampere (Finland); Terzaki, K; Fotakis, C; Farsari, M [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology Hellas (FORTH), N. Plastira 100, 70013, Heraklion, Crete (Greece); Viitanen, J, E-mail: elli.kapyla@tut.fi [VTT Technical Research Centre of Finland, PO Box 1300, 33101 Tampere (Finland)

    2011-12-15

    This study reports the pico- and femtosecond laser-induced photocrosslinking of protein microstructures. The capabilities of a picosecond Nd:YAG laser to promote multiphoton excited crosslinking of proteins were evaluated by fabricating 2D and 3D microstructures of avidin, bovine serum albumin (BSA) and biotinylated bovine serum albumin (bBSA). The multiphoton absorption-induced photocrosslinking of proteins was demonstrated here for the first time with a non-toxic biomolecule flavin mononucleotide (FMN) as the photosensitizer. Sub-micrometer and micrometer scale structures were fabricated from several different compositions of protein and photosensitizer by varying the average laser power and scanning speed in order to determine the optimal process parameters for efficient photocrosslinking. In addition, the retention of ligand-binding ability of the crosslinked protein structures was shown by fluorescence imaging of immobilized biotin or streptavidin conjugated fluorescence labels. The surface topography and the resolution of the protein patterns fabricated with the Nd:YAG laser were compared to the results obtained with a femtosecond Ti:Sapphire laser. Quite similar grain characteristics and comparable feature sizes were achieved with both laser sources, which demonstrates the utility of the low-cost Nd:YAG microlaser for direct laser writing of protein microstructures.

  3. Pico- and femtosecond laser-induced crosslinking of protein microstructures: evaluation of processability and bioactivity

    International Nuclear Information System (INIS)

    Turunen, S; Kaepylae, E; Kellomaeki, M; Terzaki, K; Fotakis, C; Farsari, M; Viitanen, J

    2011-01-01

    This study reports the pico- and femtosecond laser-induced photocrosslinking of protein microstructures. The capabilities of a picosecond Nd:YAG laser to promote multiphoton excited crosslinking of proteins were evaluated by fabricating 2D and 3D microstructures of avidin, bovine serum albumin (BSA) and biotinylated bovine serum albumin (bBSA). The multiphoton absorption-induced photocrosslinking of proteins was demonstrated here for the first time with a non-toxic biomolecule flavin mononucleotide (FMN) as the photosensitizer. Sub-micrometer and micrometer scale structures were fabricated from several different compositions of protein and photosensitizer by varying the average laser power and scanning speed in order to determine the optimal process parameters for efficient photocrosslinking. In addition, the retention of ligand-binding ability of the crosslinked protein structures was shown by fluorescence imaging of immobilized biotin or streptavidin conjugated fluorescence labels. The surface topography and the resolution of the protein patterns fabricated with the Nd:YAG laser were compared to the results obtained with a femtosecond Ti:Sapphire laser. Quite similar grain characteristics and comparable feature sizes were achieved with both laser sources, which demonstrates the utility of the low-cost Nd:YAG microlaser for direct laser writing of protein microstructures.

  4. Non-destructive evaluation of UV pulse laser-induced damage performance of fused silica optics.

    Science.gov (United States)

    Huang, Jin; Wang, Fengrui; Liu, Hongjie; Geng, Feng; Jiang, Xiaodong; Sun, Laixi; Ye, Xin; Li, Qingzhi; Wu, Weidong; Zheng, Wanguo; Sun, Dunlu

    2017-11-24

    The surface laser damage performance of fused silica optics is related to the distribution of surface defects. In this study, we used chemical etching assisted by ultrasound and magnetorheological finishing to modify defect distribution in a fused silica surface, resulting in fused silica samples with different laser damage performance. Non-destructive test methods such as UV laser-induced fluorescence imaging and photo-thermal deflection were used to characterize the surface defects that contribute to the absorption of UV laser radiation. Our results indicate that the two methods can quantitatively distinguish differences in the distribution of absorptive defects in fused silica samples subjected to different post-processing steps. The percentage of fluorescence defects and the weak absorption coefficient were strongly related to the damage threshold and damage density of fused silica optics, as confirmed by the correlation curves built from statistical analysis of experimental data. The results show that non-destructive evaluation methods such as laser-induced fluorescence and photo-thermal absorption can be effectively applied to estimate the damage performance of fused silica optics at 351 nm pulse laser radiation. This indirect evaluation method is effective for laser damage performance assessment of fused silica optics prior to utilization.

  5. Nuclear dynamics in heavy ion induced fusion-fission reactions

    International Nuclear Information System (INIS)

    Kapoor, S.S.

    1992-01-01

    Heavy ion induced fission and fission-like reactions evolve through a complex nuclear dynamics encountered in the medium energy nucleus-nucleus collisions. In the recent years, measurements of the fragment-neutron and fragment-charged particle angular correlations in heavy ion induced fusion-fission reactions, have provided new information on the dynamical times of nuclear deformations of the initial dinuclear complex to the fission saddle point and the scission point. From the studies of fragment angular distributions in heavy ion induced fission it has been possible to infer the relaxation times of the dinuclear complex in the K-degree of freedom and our recent measurements on the entrance channel dependence of fragment anisotropies have provided an experimental signature of the presence of fissions before K-equilibration. This paper reviews recent experimental and theoretical status of the above studies with particular regard to the questions relating to dynamical times, nuclear dissipation and the effect of nuclear dissipation on the K-distributions at the fission saddle in completely equilibrated compound nucleus. (author). 19 refs., 9 figs

  6. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, N. A.; Cappelli, M. A. [Stanford Plasma Physics Laboratory, Stanford University, Stanford, California 94305 (United States); Hargus, W. A. Jr. [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)

    2012-11-15

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s{sup Prime }[1/2]{sub 1}{sup 0}-6p{sup Prime }[3/2]{sub 2} xenon atomic transition at {lambda}= 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  7. Application of laser-induced autofluorescence spectra detection in human colorectal cancer screening

    Science.gov (United States)

    Fu, Sheng; Chia, Teck-Chee; Kwek, Leong Chuan; Diong, Cheong Hoong; Tang, Choong Leong; Choen, Francis S.; Krishnan, S. M.

    2003-10-01

    We investigated 48 normal patients and 25 diseased patients using our laser-induced autofluorescence spectra detection system during their regular colonoscopy. The colon and rectum mucosa autofluorescence were excited by 405 nm continue wavelength laser. We observed that cancer or diseased colorectal mucosa, their autofluorescence spectra are significantly different from normal area. The autofluorescence spectra intensity at about 500 nm was been used for our intensity ratio characteristics intensity for our diagnostic algorithm. The intensity ratios of RI-680/I-500 and RI-630/I-500 were performed to identify the detection area. From experimental result we concluded that both intensity ratios of RI-680/I-500 and RI-630/I-500 as guidelines can detect cancerous and polyps disease completely. Our investigation provided some useful insight for laser induced autofluorescence spectra as a diagnosis technique for clinical application.

  8. Saturation of the laser-induced narrowband coherent synchrotron radiation process: Experimental observation at a storage ring

    Science.gov (United States)

    Hosaka, M.; Yamamoto, N.; Takashima, Y.; Szwaj, C.; Le Parquier, M.; Evain, C.; Bielawski, S.; Adachi, M.; Zen, H.; Tanikawa, T.; Kimura, S.; Katoh, M.; Shimada, M.; Takahashi, T.

    2013-02-01

    We study the efficiency limitation affecting laser-induced coherent synchrotron radiation (CSR) at high laser power. Experiments are made on the UVSOR-II storage ring in conditions of narrowband terahertz CSR emission. While, at moderate power, CSR power increases quadratically with laser power, a noticeable decrease in efficiency and eventually a decrease in CSR power is observed experimentally at high power. Details of the underlying process are analyzed numerically. As the saturation effect depends almost instantaneously on the laser intensity, the saturation occurs locally in longitudinal space. This has important consequences on the modulation pattern induced on the electron bunch.

  9. Evolution of Technology Laser Scanner. Implications for use in Nuclear Power and Radioactive Facilities; Evolucion de la Tecnologia Laser Escaner. Implicaciones en uso en Centrales Nucleares e Instalaciones Radioactivas

    Energy Technology Data Exchange (ETDEWEB)

    Sarti Fernandez, F.; Bonet, J.

    2012-07-01

    The main technical factors affecting these teams their actual implementation in nuclear power plants will be analyzed: data acquisition speed, sensitivity, laser power, autonomy, contamination of equipment, radiation effect, etc. In conclusion, the real difference is displayed in the data collection in function of various technologies, embodied in field time, and costs.

  10. Quantitative Classification of Quartz by Laser Induced Breakdown Spectroscopy in Conjunction with Discriminant Function Analysis

    Directory of Open Access Journals (Sweden)

    A. Ali

    2016-01-01

    Full Text Available A responsive laser induced breakdown spectroscopic system was developed and improved for utilizing it as a sensor for the classification of quartz samples on the basis of trace elements present in the acquired samples. Laser induced breakdown spectroscopy (LIBS in conjunction with discriminant function analysis (DFA was applied for the classification of five different types of quartz samples. The quartz plasmas were produced at ambient pressure using Nd:YAG laser at fundamental harmonic mode (1064 nm. We optimized the detection system by finding the suitable delay time of the laser excitation. This is the first study, where the developed technique (LIBS+DFA was successfully employed to probe and confirm the elemental composition of quartz samples.

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

  13. Search for nuclear excitation by laser-driven electron motion

    International Nuclear Information System (INIS)

    Bounds, J.A.; Dyer, P.

    1992-01-01

    It has been proposed that a nucleus may be excited by first exciting the atom's electrons with UV photons. The incident photons couple to the electrons, which would then couple via a virtual photon to the nucleus. As a test case, experiments with 235 U have been performed. A pulsed infrared laser produces an atomic vapor of 235 U which is then bombarded by a high-brightness UV laser beam. The resulting ions are collected. The first excited nuclear state of 235 U has a 26-min half-life and decays by internal conversion, resulting in emission of an atomic electron. These conversion electrons are detected by a channel electron multiplier. An upper limit of 4.0x10 -5 has been obtained for the probability of exciting the nucleus of a 235 U atom that is in the 248-nm UV beam for 700 fs at an irradiance in the range of 1.0x10 15 to 2.5x10 15 W/cm 2

  14. Physical analysis on laser-induced cerebral damage

    Science.gov (United States)

    Luo, Xiaosen; Liu, Jiangang; Tao, Chunkan; Lan, Xiufeng; Cao, Lingyan; Pan, Weimin; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2005-01-01

    Experimental investigation on cerebral damage of adult SD rats induced by 532nm CW laser was performed. Tissue heat conductive equation was set up based on two-layered structure model. Finite difference algorithm was utilized to numerically simulate the temperature distribution in the brain tissue. Allowing for tissue response to temperature variation, free boundary model was used to discuss tissue thermal coagulation formation in brain. Experimental observations show that thermal coagulation and necrosis can be caused due to laser light absorption. The result of the calculation shows that the process of the thermal coagulation of the given mode comprises two stages: fast and slow. At the first stage, necrosis domain grows fast. Then necrosis domain growth becomes slower because of the competition between the heat diffusion into the surrounding undamaged tissue and the heat dissipation caused by blood perfusion. At the center of coagulation area no neuron was observed and at the transitional zone few nervous cells were seen by microscope. The research can provide reference data for developing clinical therapy of some kind of encephalic diseases by using 532nm laser, and for making cerebral infarction models in animal experiment.

  15. Protective effect of basic fibroblast growth factor on retinal injury induced by argon laser photocoagulation

    International Nuclear Information System (INIS)

    Chen, P; San, Q; Wang, C Z; Yang, Z F; Kang, H X; Qian, H W; Zhang, C P

    2010-01-01

    Laser photocoagulation treatment is often complicated by a side effect of visual impairment, which is caused by the unavoidable laser-induced retinal destruction. At present no specific is found to cure this retinopathy. The aim of this study was to observe the neuroprotective effect of bFGF on laser-induced retinal injury. Chinchilla rabbits were divided into three groups and argon laser lesions were created in the retinas. Then bFGF or dexamethasone, a widely used ophthalmic preparation, or saline was given severally by retrobulbar injection. The retinal lesions were evaluated histologically and morphometrically, and visual function was examined by ERG. The results showed that bFGF administration better preserved morphology of retinal photoreceptors and significantly diminished the area of the lesions. Furthermore, bFGF promoted the restoration of the ERG b-wave amplitude. In rabbits treated with dexamethasone, however, the lesions showed almost no ameliorative changes. This is the first study to investigate the potential role of bFGF as a remedial agent in laser photocoagulation treatment. These findings suggest that bFGF has significant neuroprotective properties in the retina and this type of neuroprotection may be of clinical significance in reducing iatrogenic laser-induced retinal injuries in humans

  16. Progress of laser fusion research

    International Nuclear Information System (INIS)

    Yamanaka, Chiyoe

    1988-01-01

    The history of the research on nuclear fusion utilizing laser is described. It started in USSR in 1968, but the full scale start of laser implosion nuclear fusion was in 1972. In Osaka University, nuclear fusion neutrons were detected with a solid deuterium target and the phenomenon of parametric abnormal absorption in laser plasma was found in 1971. The new type target for implosion nuclear fusion ''Canon ball'' was devised in 1975. The phenomenon of the abnormal transmission of laser beam through a thin metal film in a multiple film target was found in 1976, and named ''Osaka effect''. Also the development of lasers has been advanced, and in 1983, a largest glass laser in the world, Gekko 12, with 12 beams, 30 kJ output, 55 TW, was completed. The new target LHART was devised, which enabled the generation of 10 trillion D-T reaction neutrons. Due to the development of high power laser technology, the realization of the new design of fuel pellets, the evaluation of the data by computer simulation, and the realization of new plasma diagnostic method, the research on laser nuclear fusion has developed rapidly, and the attainment of break-even is expected in 1990s. The features of inertial nuclear fusion are enumerated. (Kako, I.)

  17. Monitoring of pipelines in nuclear power plants by measuring laser-based mechanical impedance

    International Nuclear Information System (INIS)

    Lee, Hyeonseok; Sohn, Hoon; Yang, Suyoung; Yang, Jinyeol

    2014-01-01

    Using laser-based mechanical impedance (LMI) measurement, this study proposes a damage detection technique that enables structural health monitoring of pipelines under the high temperature and radioactive environments of nuclear power plants (NPPs). The applications of conventional electromechanical impedance (EMI) based techniques to NPPs have been limited, mainly due to the contact nature of piezoelectric transducers, which cannot survive under the high temperature and high radiation environments of NPPs. The proposed LMI measurement technique aims to tackle the limitations of the EMI techniques by utilizing noncontact laser beams for both ultrasound generation and sensing. An Nd:Yag pulse laser is used for ultrasound generation, and a laser Doppler vibrometer is employed for the measurement of the corresponding ultrasound responses. For the monitoring of pipes covered by insulation layers, this study utilizes optical fibers to guide the laser beams to specific target locations. Then, an outlier analysis is adopted for autonomous damage diagnosis. Validation of the proposed LMI technique is carried out on a carbon steel pipe elbow under varying temperatures. A corrosion defect chemically engraved in the specimen is successfully detected. (papers)

  18. Monitoring of pipelines in nuclear power plants by measuring laser-based mechanical impedance

    Science.gov (United States)

    Lee, Hyeonseok; Sohn, Hoon; Yang, Suyoung; Yang, Jinyeol

    2014-06-01

    Using laser-based mechanical impedance (LMI) measurement, this study proposes a damage detection technique that enables structural health monitoring of pipelines under the high temperature and radioactive environments of nuclear power plants (NPPs). The applications of conventional electromechanical impedance (EMI) based techniques to NPPs have been limited, mainly due to the contact nature of piezoelectric transducers, which cannot survive under the high temperature and high radiation environments of NPPs. The proposed LMI measurement technique aims to tackle the limitations of the EMI techniques by utilizing noncontact laser beams for both ultrasound generation and sensing. An Nd:Yag pulse laser is used for ultrasound generation, and a laser Doppler vibrometer is employed for the measurement of the corresponding ultrasound responses. For the monitoring of pipes covered by insulation layers, this study utilizes optical fibers to guide the laser beams to specific target locations. Then, an outlier analysis is adopted for autonomous damage diagnosis. Validation of the proposed LMI technique is carried out on a carbon steel pipe elbow under varying temperatures. A corrosion defect chemically engraved in the specimen is successfully detected.

  19. Annual report of the nuclear physics section of the institute of applied nuclear physics (July 1, 1976 - June 30, 1977)

    International Nuclear Information System (INIS)

    Bechtold, V.; Ottmar, H.

    1977-10-01

    The activities of the Nuclear Physics Section of the Institute of Applied Nuclear Physics from mid 1976 to mid 1977 are surveyed. The research program comprises both contributions to fundamental and applied nuclear research. The activities on the application of nuclear methods mainly concentrate on the measurements of cross sections of neutron-induced nuclear reactions for the fast breeder project, the application of gamma-ray spectrometry to nuclear fuel assay problems, the development of a proton microbeam for elemental analysis, and the production of 123 J for medical application. The study of nuclear reactions induced by α particles, 6 Li ions and fast neutrons, and the measurement of optical hyperfine structure using high-resolution laser spectroscopy form the major part of the fundamental research work. In addition, the operation of the two accelerators of the institute, an isochronous cyclotron and a 3 MV Van de Graaff accelerator, are briefly reviewed. (orig.) [de

  20. Polarisation Control of DFB Fibre Laser Using UV-Induced Birefringent Phase-Shift

    DEFF Research Database (Denmark)

    Philipsen, Jacob Lundgreen; Lauridsen, Vibeke Claudia; Berendt, Martin Ole

    1998-01-01

    The polarisation properties of a distributed feedback (DFB) fibre laser are investigated experimentally. A birefringent phase-shift is induced by side illumination of the centre part of the lasing structure with ultraviolet (UV) light and it is experimentally shown that the birefringence...... of the phase-shift is the dominating effect controlling the polarisation properties of the laser....

  1. Excimer-laser-induced permanent electrical conductivity in solid C60 films

    International Nuclear Information System (INIS)

    Ning, D.; Lou, Q.H.; Dong, J.X.; Wei, Y.R.

    1996-01-01

    After being irradiated in air by a XeCl (308 nm) excimer laser, the electrical conductivity of solid thin-film C 60 has been improved by more than six orders of magnitudes. The products resulting from laser irradiation of C 60 films have been investigated by Raman scattering and the onset of conductivity can be attributed to laser-induced oxygenation and disintegration of the fullerene. Irradiated by ∼40 ns laser pulses with different fluence, products with different microstructure were observed. At lower fluence, the Raman features of microcrystalline graphite and fullerene polymer were observed. At a fluence just below the ablation threshold (36 mJ/cm 2 ), the fullerene molecules in the film were disintegrated completely and transformed to amorphous graphite. (orig.). With 5 figs

  2. The potential of laser cutting and snake arm robots in aspects of nuclear decommissioning

    International Nuclear Information System (INIS)

    Hilton, Paul; Khan, Ali

    2013-01-01

    This paper will describe recent work conducted in the UK to highlight the potential of applying high power laser cutting to aspects of decommissioning and dismantling in the nuclear sector. A major driver for this activity is size reduction of metallic structures, vessels and tubing, with the objective of efficient stacking of the cut parts for future long term storage. TWI have used a standard 5 kW multi-mode laser with fibre optic delivery of the beam, to demonstrate techniques for cutting stainless steel tubing, at diameters up to 150 mm and wall thicknesses up to 7 mm, and various thicknesses of plate materials. Using specially developed cutting heads, employing long focal length lenses to form the beam, techniques were developed to allow the cutting of tubes from one side only and without changing the focal position of the laser beam with respect to the diameter of the tube perpendicular to the incident beam. The latter means that remote programming of the cutting path becomes much simpler. For cutting plate materials, special gas nozzle dynamics have produced great tolerance of the cutting process to stand-off distance (the distance between the surface of the material being cut and the exit of the cutting nozzle). One particularly interesting method of remote deployment of these cutting techniques is to use 'snake arm' robots. These robots, by nature of their construction, can access areas un-accessible using other techniques. This of course makes them particularly suited to aspects of nuclear decommissioning, particularly in what are termed 'un-structured environments', where the exact disposition of items encountered is not known. The paper will also describe the first time a laser cutting head has been installed on the end of a snake arm robot and the combination used in a simulated nuclear cutting application. (author)

  3. Carbohydrate-protein interaction studies by laser photo CIDNP NMR methods

    NARCIS (Netherlands)

    Siebert, HC; Kaptein, R; Beintema, JJ; Soedjanaatmadja, UM; Wright, CS; Rice, A; Kleineidam, RG; Kruse, S; Schauer, R; Pouwels, PJW; Kamerling, JP; Gabius, HJ; Vliegenthart, JFG

    The side chains of tyrosine, tryptophan and histidine are able to produce CIDNP (Chemically Induced Dynamic Nuclear Polarization) signals after laser irradiation in the presence of a suitable radical pair-generating dye. Elicitation of such a response in proteins implies surface accessibility of the

  4. Quantitative pump-induced wavefront distortions in laser-diode- and flash-lamp-pumped Nd:YLF laser rods

    International Nuclear Information System (INIS)

    Skeldon, M.D.; Saager, R.B.; Seka, W.

    1999-01-01

    Detailed interferometric measurements of the induced thermal distortions due to laser-diode and xenon flashlamp pumping of Nd:YLF are presented. The thermal distortions are quantified in terms of the primary aberrations of defocus, astigmatism, coma, and spherical. Defocus and astigmatism are shown to dominate the thermal aberrations. The measured defocus and astigmatism are converted to the conventional thermal-focal lengths in two perpendicular directions with respect to the Nd:YLF crystalline c axis for each of the two polarization states σ and π. A comparison of the thermal-focal lengths measured with the xenon flashlamp- and laser-diode-pumped rods is given when the rods are pumped to the same small-signal gain. The authors calculate effective dioptric-power coefficients from the data for comparison to those reported in the literature for krypton-flashlamp pumping. A thermal-time constant of 1.5 s is measured for the laser-diode-pumped Nd:YLF laser rod

  5. 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.

  6. Resonance-enhanced laser-induced plasma spectroscopy: ambient gas effects

    International Nuclear Information System (INIS)

    Lui, S.L.; Cheung, N.H.

    2003-01-01

    When performing laser-induced plasma spectroscopy for elemental analysis, the sensitivity could be significantly enhanced if the plume was resonantly rekindled by a dye laser pulse. The extent of the enhancement was found to depend on the ambient gas. Air, nitrogen, helium, argon and xenon at pressures ranging from vacuum to 1 bar were investigated. In vacuum, the analyte signal was boosted because of reduced cooling, but it soon decayed as the plume freely expanded. By choosing the right ambient gas at the right pressure, the expanding plume could be confined as well as thermally insulated to maximize the analyte signal. For instance, an ambient of 13 mbar xenon yielded a signal-to-noise ratio of 110. That ratio was 53 when the pellet was ablated in air, and decreased further to 5 if the dye laser was tuned off resonance

  7. Comparison of the Detection Characteristics of Trace Species Using Laser-Induced Breakdown Spectroscopy and Laser Breakdown Time-of-Flight Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Zhenzhen Wang

    2015-03-01

    Full Text Available The rapid and precise element measurement of trace species, such as mercury, iodine, strontium, cesium, etc. is imperative for various applications, especially for industrial needs. The elements mercury and iodine were measured by two detection methods for comparison of the corresponding detection features. A laser beam was focused to induce plasma. Emission and ion signals were detected using laser-induced breakdown spectroscopy (LIBS and laser breakdown time-of-flight mass spectrometry (LB-TOFMS. Multi-photon ionization and electron impact ionization in the plasma generation process can be controlled by the pressure and pulse width. The effect of electron impact ionization on continuum emission, coexisting molecular and atomic emissions became weakened in low pressure condition. When the pressure was less than 1 Pa, the plasma was induced by laser dissociation and multi-photon ionization in LB-TOFMS. According to the experimental results, the detection limits of mercury and iodine in N2 were 3.5 ppb and 60 ppb using low pressure LIBS. The mercury and iodine detection limits using LB-TOFMS were 1.2 ppb and 9.0 ppb, which were enhanced due to different detection features. The detection systems of LIBS and LB-TOFMS can be selected depending on the condition of each application.

  8. Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-06-01

    A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

  9. Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

    International Nuclear Information System (INIS)

    Thiyagarajan, Magesh; Thompson, Shane

    2012-01-01

    We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 μm radius spot size that produces laser intensities up to 3 - 6 TW/cm 2 , sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10 8 nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then scaled to

  10. Laser-induced microstructural development and phase evolution in magnesium alloy

    International Nuclear Information System (INIS)

    Guan, Y.C.; Zhou, W.; Li, Z.L.; Zheng, H.Y.

    2014-01-01

    Highlights: • Secondary phase evolution caused by laser processing was firstly reported. • Microstructure development was controlled by heat flow thermodynamics and kinetics. • Solid-state transformation resulted in submicron and nano-scale precipitates. • Cluster-shaped particles in overlapped region were due to precipitation coarsening. • Properties of materials can be tailored selectively by laser processing. -- Abstract: Secondary phase plays an important role in determining microstructures and properties of magnesium alloys. This paper focuses on laser-induced microstructure development and secondary phase evolution in AZ91D Mg alloy studied by SEM, TEM and EDS analyses. Compared to bulk shape and lamellar structure of the secondary phase in as-received cast material, rapid-solidified microstructures with various morphologies including nano-precipitates were observed in laser melt zone. Formation mechanisms of microstructural evolution and effect of phase development on surface properties were further discussed

  11. Structural features of silver-doped phosphate glasses in zone of femtosecond laser-induced modification

    International Nuclear Information System (INIS)

    Vasileva, A.A.; Nazarov, I.A.; Olshin, P.K.; Povolotskiy, A.V.; Sokolov, I.A.; Manshina, A.A.

    2015-01-01

    Femtosecond (fs) laser writing of two-dimensional microstructures (waveguides) is demonstrated in bulk phosphate glasses doped with silver ions. Silver-content phosphate and silver-content niobium–phosphate glasses with high concentration of silver oxide 55 mol% were used as samples for fs laser writing. The chemical network structure of the synthesized samples is analyzed through Raman spectroscopy and was found to be strongly sensitive to Nb incorporation. It was found that the direct laser writing process enables not only reorganization of glass network, but also formation of color centers and silver nanoparticles that are revealed in appearance of luminescence signal and plasmon absorption. The process of NPs' formation is more efficient for Nb-phosphate glass, while color centers are preferably formed in phosphate glass. - Graphical abstract: Formation of silver NPs on the surface of 0.5Ag 2 O–0.4P 2 O 5 –0,1Nb 2 O 5 glass induced by CW laser irradiation. - Highlights: • The structure of 0.5Ag 2 O–0.1Nb 2 O 5 –0.4P 2 O 5 and 0.55Ag 2 O–0.45P 2 O 5 glasses was investigated by Raman spectroscopy. • Fs laser writing induces formation of silver NPs in investigated glasses. • Surface plasmon resonance in the absorption spectra confirms the formation of NP. • The possibility of CW laser induced formation of silver NPs on the surface of sample with niobium is shown

  12. CO2 laser-induced bump formation and growth on polystyrene for multi-depth soft lithography molds

    International Nuclear Information System (INIS)

    Li, Huawei; Fan, Yiqiang; Conchouso, David; Foulds, Ian G

    2012-01-01

    This paper reports the process of creating bumps on the surface of polystyrene (PS) induced by a CO 2 laser at low powers. The paper also outlines the procedure for growing bumps induced by multiple laser scans on the aforementioned bumps. These bumps result from the net volume gain of the laser heat-affected zone on the PS rather than from a deposition process, and the expansion of the heat-affected zone on PS was verified by measuring the hardness change using nanoindentation. The bumps have a much smoother surface than microchannels fabricated with laser cutting; depending on the laser power, they have heights ranging from hundreds of nanometers to 42 µm. The laser scanning speed and scan times along with this technique offer a fast and low-cost alternative for fabricating molds for multi-depth PDMS microfluidic devices. (paper)

  13. Refining femtosecond laser induced periodical surface structures with liquid assist

    International Nuclear Information System (INIS)

    Jiao, L.S.; Ng, E.Y.K.; Zheng, H.Y.

    2013-01-01

    Highlights: ► LIPSS on silicon wafer was made in air and in ethanol environment. ► Ethanol environment produce cleaner surface ripples. ► Ethanol environment decrease spatial wavelength of the LIPSS by 30%. ► More number of pulses produce smaller spatial wavelength in air. ► Number of pulses do not influence spatial wavelength in ethanol environment. - Abstract: Laser induced periodic surface structures were generated on silicon wafer using femtosecond laser. The medium used in this study is both air and ethanol. The laser process parameters such as wavelength, number of pulse, laser fluence were kept constant for both the mediums. The focus of the study is to analyze spatial wavelength. When generating surface structures with air as a medium and same process parameter of the laser, spatial wavelength results showed a 30% increase compared to ethanol. The cleanliness of the surface generated using ethanol showed considerably less debris than in air. The results observed from the above investigation showed that the medium plays a predominant role in the generation of surface structures.

  14. Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

    Directory of Open Access Journals (Sweden)

    Hery Suyanto

    2016-08-01

    Full Text Available A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns and picosecond (ps lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS using He ambient gas.

  15. Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

    Energy Technology Data Exchange (ETDEWEB)

    Suyanto, Hery [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Hedwig, Rinda [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Marpaung, Alion Mangasi [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, Rawamangun, Jakarta 12440 (Indonesia); Ramli, Muliadi [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Lie, Tjung Jie; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Abdulmadjid, Syahrun Nur [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha,Bandung 40132 (Indonesia); Kagawa, Kiichiro [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Fukui Science Education Academy, Takagi Chuo 2 chome, Fukui 910-0804 (Japan)

    2016-08-15

    A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns) and picosecond (ps) lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE) mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS) using He ambient gas.

  16. Railgun pellet injection system using a laser-induced plasma armature

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, M.; Oda, Y.; Azuma, K. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Advanced Technology Development Dept.; Kasai, S.; Hasegawa, K. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan)

    1996-06-01

    An electromagnetic railgun pellet injection system that utilizes a laser-induced plasma armature formation has been developed for fusion experimental devices. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. A small amount of hydrogen gas increased the breakdown voltage of helium gas. This effect is considered to be one of the reasons for lowering the energy conversion coefficient for hydrogen pellet acceleration. To compensate for the low pellet acceleration efficiency, a railgun with ceramic insulators and an augmented rail structure has been tested. The energy conversion coefficient using the augmented railgun was further increased from that using a single-rail structure with the plastic insulators. The average acceleration rate was almost doubled. The highest hydrogen pellet velocity was about 2.3 km s{sup -1}. (Author).

  17. Railgun pellet injection system using a laser-induced plasma armature

    International Nuclear Information System (INIS)

    Onozuka, M.; Oda, Y.; Azuma, K.

    1996-01-01

    An electromagnetic railgun pellet injection system that utilizes a laser-induced plasma armature formation has been developed for fusion experimental devices. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. A small amount of hydrogen gas increased the breakdown voltage of helium gas. This effect is considered to be one of the reasons for lowering the energy conversion coefficient for hydrogen pellet acceleration. To compensate for the low pellet acceleration efficiency, a railgun with ceramic insulators and an augmented rail structure has been tested. The energy conversion coefficient using the augmented railgun was further increased from that using a single-rail structure with the plastic insulators. The average acceleration rate was almost doubled. The highest hydrogen pellet velocity was about 2.3 km s -1 . (Author)

  18. Laser-Induced Changes to L-adrenaline-D-hydrogentartrate Incorporated in KBr Matrices

    International Nuclear Information System (INIS)

    Jovanovic, T.S.; Bogavac, M.R.; Radak, B.B.; Trtica, M.S.

    2002-01-01

    Changes in the pharmaceutical L-adrenaline-D-hydrogentartrate, incorporated in KBr matrices, induced by a pulsed carbon-dioxide Transversely Excited Atmospheric (TEA) laser, were observed. Modifications of the sample were monitored via infrared spectra. Special attention was devoted to the dependence of the sample changes on the laser energy density used. The irradiation of the pharmaceutical has been performed with two laser lines at wavelengths of about 10.6 μm. The laser lines coincide well with the absorption band of the pharmaceutical, which is assigned to the ring vibrations/out-of-plane OH deformation vibrations, within the carboxyl (COOH) group of L-adrenaline-D-hydrogentartrate. Laser energy densities of 1.20 and 1.70 J/cm2 modified the pharmaceutical/compound. It was found that this modification is in essence a thermal effect. The level of change showed a dependence on the laser energy density, number of accumulated laser pulses and temporal shape of the pulse.

  19. Reduction of Friction of Metals Using Laser-Induced Periodic Surface Nanostructures

    OpenAIRE

    Zhuo Wang; Quanzhong Zhao; Chengwei Wang

    2015-01-01

    We report on the effect of femtosecond-laser-induced periodic surface structures (LIPSS) on the tribological properties of stainless steel. Uniform periodic nanostructures were produced on AISI 304L (American Iron and Steel Institute steel grade) steel surfaces using an 800-nm femtosecond laser. The spatial periods of LIPSS measured by field emission scanning electron microscopy ranged from 530 to 570 nm. The tribological properties of smooth and textured surfaces with periodic nanostructures...

  20. Compact Birefringent Waveplates Photo-Induced in Silica by Femtosecond Laser

    Directory of Open Access Journals (Sweden)

    Matthieu Lancry

    2014-09-01

    Full Text Available Recently, we showed that femtosecond laser induced “nanogratings” consist of thin regions with a low refractive index (Δn = −0.15, due to the formation of nanoporous silica surrounded by regions with a positive index change. In this paper, we investigate a wide range of laser parameters to achieve very high retardance within a single layer; as much as 350 nm at λ = 546 nm but also to minimize the competing losses. We show that the total retardance depends on the number of layers present and can be accumulated in the direction of laser propagation to values higher than 1600 nm. This opens the door to using these nanostructures as refined building blocks for novel optical elements based on strong retardance.