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Sample records for high gradient laser

  1. The chirped-pulse inverse free-electron laser: A high-gradient vacuum laser accelerator

    International Nuclear Information System (INIS)

    Hartemann, F.V.; Landahl, E.C.; Troha, A.L.; Van Meter, J.R.; Baldis, H.A.; Freeman, R.R.; Luhmann, N.C. Jr.; Song, L.; Kerman, A.K.; Yu, D.U.

    1999-01-01

    The inverse free-electron laser (IFEL) interaction is studied theoretically and computationally in the case where the drive laser intensity approaches the relativistic regime, and the pulse duration is only a few optical cycles long. The IFEL concept has been demonstrated as a viable vacuum laser acceleration process; it is shown here that by using an ultrashort, ultrahigh-intensity drive laser pulse, the IFEL interaction bandwidth and accelerating gradient are increased considerably, thus yielding large energy gains. Using a chirped pulse and negative dispersion focusing optics allows one to take further advantage of the laser optical bandwidth and produce a chromatic line focus maximizing the gradient. The combination of these novel ideas results in a compact vacuum laser accelerator capable of accelerating picosecond electron bunches with a high gradient (GeV/m) and very low energy spread. copyright 1999 American Institute of Physics

  2. Optical design for increased interaction length in a high gradient dielectric laser accelerator

    OpenAIRE

    Cesar, D.; Maxson, J.; Musumeci, P.; Shen, X.; England, R. J.; Wootton, K. P.

    2018-01-01

    We present a methodology for designing and measuring pulse front tilt in an ultrafast laser for use in dielectric laser acceleration. Previous research into dielectric laser accelerating modules has focused on measuring high accelerating gradients in novel structures, but has done so only for short electron-laser coupling lengths. Here we demonstrate an optical design to extend the laser-electron interaction to 1mm.

  3. Development of High-Gradient Dielectric Laser-Driven Particle Accelerator Structures

    Energy Technology Data Exchange (ETDEWEB)

    Byer, Robert L. [Stanford Univ., CA (United States). Edward L. Ginzton Lab.

    2013-11-07

    The thrust of Stanford's program is to conduct research on high-gradient dielectric accelerator structures driven with high repetition-rate, tabletop infrared lasers. The close collaboration between Stanford and SLAC (Stanford Linear Accelerator Center) is critical to the success of this project, because it provides a unique environment where prototype dielectric accelerator structures can be rapidly fabricated and tested with a relativistic electron beam.

  4. Lateral Temperature-Gradient Method for High-Throughput Characterization of Material Processing by Millisecond Laser Annealing.

    Science.gov (United States)

    Bell, Robert T; Jacobs, Alan G; Sorg, Victoria C; Jung, Byungki; Hill, Megan O; Treml, Benjamin E; Thompson, Michael O

    2016-09-12

    A high-throughput method for characterizing the temperature dependence of material properties following microsecond to millisecond thermal annealing, exploiting the temperature gradients created by a lateral gradient laser spike anneal (lgLSA), is presented. Laser scans generate spatial thermal gradients of up to 5 °C/μm with peak temperatures ranging from ambient to in excess of 1400 °C, limited only by laser power and materials thermal limits. Discrete spatial property measurements across the temperature gradient are then equivalent to independent measurements after varying temperature anneals. Accurate temperature calibrations, essential to quantitative analysis, are critical and methods for both peak temperature and spatial/temporal temperature profile characterization are presented. These include absolute temperature calibrations based on melting and thermal decomposition, and time-resolved profiles measured using platinum thermistors. A variety of spatially resolved measurement probes, ranging from point-like continuous profiling to large area sampling, are discussed. Examples from annealing of III-V semiconductors, CdSe quantum dots, low-κ dielectrics, and block copolymers are included to demonstrate the flexibility, high throughput, and precision of this technique.

  5. The LLNL/UCLA high gradient inverse free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Moody, J. T.; Musumeci, P.; Anderson, G.; Anderson, S.; Betts, S.; Fisher, S.; Gibson, D.; Tremaine, A.; Wu, S. [Department of Physics and Astronomy, UCLA, Los Angeles California, 90095 (United States); Lawrence Livermore National Laboratory (United States)

    2012-12-21

    We describe the Inverse Free Electron Accelerator currently under construction at Lawrence Livermore National Lab. Upon completion of this accelerator, high brightness electrons generated in the photoinjector blowout regime and accelerated to 50 MeV by S-band accelerating sections will interact with > 4 TW peak power Ti:Sapphire laser in a highly tapered 50 cm undulator and experience an acceleration gradient of > 200 MeV/m. We present the final design of the accelerator as well as the results of start-to-end simulations investigating preservation of beam quality and tolerances involved with this accelerator.

  6. Variable high gradient permanent magnet quadrupole (QUAPEVA)

    Science.gov (United States)

    Marteau, F.; Ghaith, A.; N'Gotta, P.; Benabderrahmane, C.; Valléau, M.; Kitegi, C.; Loulergue, A.; Vétéran, J.; Sebdaoui, M.; André, T.; Le Bec, G.; Chavanne, J.; Vallerand, C.; Oumbarek, D.; Cosson, O.; Forest, F.; Jivkov, P.; Lancelot, J. L.; Couprie, M. E.

    2017-12-01

    Different applications such as laser plasma acceleration, colliders, and diffraction limited light sources require high gradient quadrupoles, with strength that can reach up to 200 T/m for a typical 10 mm bore diameter. We present here a permanent magnet based quadrupole (so-called QUAPEVA) composed of a Halbach ring and surrounded by four permanent magnet cylinders. Its design including magnetic simulation modeling enabling us to reach 201 T/m with a gradient variability of 45% and mechanical issues are reported. Magnetic measurements of seven systems of different lengths are presented and confirmed the theoretical expectations. The variation of the magnetic center while changing the gradient strength is ±10 μm. A triplet of QUAPEVA magnets is used to efficiently focus a beam with large energy spread and high divergence that is generated by a Laser Plasma Acceleration source for a free electron laser demonstration and has enabled us to perform beam based alignment and control the dispersion of the beam.

  7. Microstructure and high temperature oxidation resistance of Ti-Ni gradient coating on TA2 titanium alloy fabricated by laser cladding

    Science.gov (United States)

    Liu, Fencheng; Mao, Yuqing; Lin, Xin; Zhou, Baosheng; Qian, Tao

    2016-09-01

    To improve the high temperature oxidation resistance of TA2 titanium alloy, a gradient Ni-Ti coating was laser cladded on the surface of the TA2 titanium alloy substrate, and the microstructure and oxidation behavior of the laser cladded coating were investigated experimentally. The gradient coating with a thickness of about 420-490 μm contains two different layers, e.g. a bright layer with coarse equiaxed grain and a dark layer with fine and columnar dendrites, and a transition layer with a thickness of about 10 μm exists between the substrate and the cladded coating. NiTi, NiTi2 and Ni3Ti intermetallic compounds are the main constructive phases of the laser cladded coating. The appearance of these phases enhances the microhardness, and the dense structure of the coating improves its oxidation resistance. The solidification procedure of the gradient coating is analyzed and different kinds of solidification processes occur due to the heat dissipation during the laser cladding process.

  8. Study of ultra-high gradient wakefield excitation by intense ultrashort laser pulses in plasma

    International Nuclear Information System (INIS)

    Kotaki, Hideyuki

    2002-12-01

    We investigate a mechanism of nonlinear phenomena in laser-plasma interaction, a laser wakefield excited by intense laser pulses, and the possibility of generating an intense bright electron source by an intense laser pulse. We need to understand and further employ some of these phenomena for our purposes. We measure self-focusing, filamentation, and the anomalous blueshift of the laser pulse. The ionization of gas with the self-focusing causes a broad continuous spectrum with blueshift. The normal blueshift depends on the laser intensity and the plasma density. We, however, have found different phenomenon. The laser spectrum shifts to fixed wavelength independent of the laser power and gas pressure above some critical power. We call the phenomenon 'anomalous blueshift'. The results are explained by the formation of filaments. An intense laser pulse can excite a laser wakefield in plasma. The coherent wakefield excited by 2 TW, 50 fs laser pulses in a gas-jet plasma around 10 18 cm -3 is measured with a time-resolved frequency domain interferometer (FDI). The density distribution of the helium gas is measured with a time-resolved Mach-Zehnder interferometer to search for the optimum laser focus position and timing in the gas-jet. The results show an accelerating wakefield excitation of 20 GeV/m with good coherency, which is useful for ultrahigh gradient particle acceleration in a compact system. This is the first time-resolved measurement of laser wakefield excitation in a gas-jet plasma. The experimental results are compared with a Particle-in-Cell (PIC) simulation. The pump-probe interferometer system of FDI and the anomalous blueshift will be modified to the optical injection system as a relativistic electron beam injector. In 1D PIC simulation we obtain the results of high quality intense electron beam acceleration. These results illuminate the possibility of a high energy and a high quality electron beam acceleration. (author)

  9. Ultra-high gradient compact accelerator developments

    NARCIS (Netherlands)

    Brussaard, G.J.H.; Wiel, van der M.J.

    2004-01-01

    Continued development of relatively compact, although not quite 'table-top', lasers with peak powers in the range up to 100 TW has enabled laser-plasma-based acceleration experiments with amazing gradients of up to 1 TV/m. In order to usefully apply such gradients to 'controlled' acceleration,

  10. Observation of 690 MV m-1 Electron Accelerating Gradient with a Laser-Driven Dielectric Microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, K.P.; Wu, Z.; /SLAC; Cowan, B.M.; /Tech-X, Boulder; Hanuka, A.; /SLAC /Technion; Makasyuk, I.V.; /SLAC; Peralta, E.A.; Soong, K.; Byer, R.L.; /Stanford U.; England, R.J.; /SLAC

    2016-06-27

    Acceleration of electrons using laser-driven dielectric microstructures is a promising technology for the miniaturization of particle accelerators. In this work, experimental results are presented of relativistic electron acceleration with 690±100 MVm-1 gradient. This is a record-high accelerating gradient for a dielectric microstructure accelerator, nearly doubling the previous record gradient. To reach higher acceleration gradients the present experiment employs 90 fs duration laser pulses.

  11. High power ultrashort pulse lasers

    International Nuclear Information System (INIS)

    Perry, M.D.

    1994-01-01

    Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced

  12. Effects of bunch density gradient in high-gain free-electron lasers

    International Nuclear Information System (INIS)

    Huang, Z.; Kim, K.-J.

    1999-01-01

    The authors investigate effects of the bunch density gradient in self-amplified spontaneous emission (SASE), including the role of coherent spontaneous emission (CSE) in the evolution of the free-electron laser (FEL) process. In the exponential gain regime, the authors solve the coupled Maxwell-Vlasov equations and extend the linear theory to a bunched beam with energy spread. A time-dependent, nonlinear simulation algorithm is used to study the CSE effect and the nonlinear evolution of the radiation pulse

  13. Free-electron laser as a power source for a high-gradient accelerating structure

    International Nuclear Information System (INIS)

    Sessler, A.M.

    1982-02-01

    A two beam colliding linac accelerator is proposed in which one beam is intense (approx. = 1KA), of low energy (approx. = MeV), and long (approx. = 100 ns) and provides power at 1 cm wavelength through a free-electron-laser-mechanism to the second beam of a few electrons (approx. = 10 11 ), which gain energy at the rate of 250 MeV/m in a high-gradient accelerating structure and hence reach 375 GeV in 1.5 km. The intense beam is given energy by induction units and gains, and losses by radiation, 250 keV/m thus supplying 25 J/m to the accelerating structure. The luminosity, L, of two such linacs would be, at a repetition rate of 1 kHz, L = 4. x 10 32 cm -2 s -1

  14. 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.

  15. Laser pulse propagation and enhanced energy coupling to fast electrons in dense plasma gradients

    International Nuclear Information System (INIS)

    Gray, R J; Carroll, D C; Yuan, X H; Brenner, C M; Coury, M; Quinn, M N; Tresca, O; McKenna, P; Burza, M; Wahlström, C-G; Lancaster, K L; Neely, D; Lin, X X; Li, Y T

    2014-01-01

    Laser energy absorption to fast electrons during the interaction of an ultra-intense (10 20 W cm −2 ), picosecond laser pulse with a solid is investigated, experimentally and numerically, as a function of the plasma density scale length at the irradiated surface. It is shown that there is an optimum density gradient for efficient energy coupling to electrons and that this arises due to strong self-focusing and channeling driving energy absorption over an extended length in the preformed plasma. At longer density gradients the laser filaments, resulting in significantly lower overall energy coupling. As the scale length is further increased, a transition to a second laser energy absorption process is observed experimentally via multiple diagnostics. The results demonstrate that it is possible to significantly enhance laser energy absorption and coupling to fast electrons by dynamically controlling the plasma density gradient. (paper)

  16. Plasma membrane temperature gradients and multiple cell permeabilization induced by low peak power density femtosecond lasers

    Directory of Open Access Journals (Sweden)

    Allen L. Garner

    2016-03-01

    Full Text Available Calculations indicate that selectively heating the extracellular media induces membrane temperature gradients that combine with electric fields and a temperature-induced reduction in the electropermeabilization threshold to potentially facilitate exogenous molecular delivery. Experiments by a wide-field, pulsed femtosecond laser with peak power density far below typical single cell optical delivery systems confirmed this hypothesis. Operating this laser in continuous wave mode at the same average power permeabilized many fewer cells, suggesting that bulk heating alone is insufficient and temperature gradients are crucial for permeabilization. This work suggests promising opportunities for a high throughput, low cost, contactless method for laser mediated exogenous molecule delivery without the complex optics of typical single cell optoinjection, for potential integration into microscope imaging and microfluidic systems.

  17. Role of resistivity gradient in laser-driven ion acceleration

    Directory of Open Access Journals (Sweden)

    L. A. Gizzi

    2011-01-01

    Full Text Available It was predicted that, when a fast electron beam with some angular spread is normally incident on a resistivity gradient, magnetic field generation can occur that can inhibit beam propagation [A. R. Bell et al., Phys. Rev. E 58, 2471 (1998PLEEE81063-651X10.1103/PhysRevE.58.2471]. This effect can have consequences on the laser-driven ion acceleration. In the experiment reported here, we compare ion emission from laser irradiated coated and uncoated metal foils and we show that the ion beam from the coated target has a much smaller angular spread. Detailed hybrid numerical simulations confirm that the inhibition of fast electron transport through the resistivity gradient may explain the observed effect.

  18. Gradient heating protocol for a diode-pumped alkali laser

    Science.gov (United States)

    Cai, He; Wang, You; Han, Juhong; Yu, Hang; Rong, Kepeng; Wang, Shunyan; An, Guofei; Wang, Hongyuan; Zhang, Wei; Wu, Peng; Yu, Qiang

    2018-06-01

    A diode-pumped alkali laser (DPAL) has gained rapid development in the recent years. Until now, the structure with single heater has been widely utilized to adjust the temperature of an alkali vapor cell in most of the literatures about DPALs. However, for an end-pumped DPAL using single heater, most pump energy is absorbed by the gain media near the entrance cell window because of the large absorption cross section of atomic alkali. As a result, the temperature in the pumping area around the entrance window will go up rapidly, especially in a case of high pumping density. The temperature rise would bring about some negative influences such as thermal effects and variations in population density. In addition, light scattering and window contamination aroused by the chemical reaction between the alkali vapor and the buffer gas will also affect the output performance of a DPAL system. To find a solution to these problems, we propose a gradient heating approach in which several heaters are tandem-set along the optical axis to anneal an alkali vapor cell. The temperature at the entrance window is adjusted to be lower than that of the other side. By using this novel scheme, one can not only achieve a homogeneous absorption of the pump energy along the cell axis, but also decrease the possibility of the window damage in a DPAL configuration. The theoretical simulation of the laser output features has been carried out for a configuration of multiple heaters. Additionally, the DPAL output performance under different gradient temperatures is also discussed in this paper. The conclusions might be helpful for development of a high-powered and high-beam-quality DPAL.

  19. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    Science.gov (United States)

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  20. [The effect of technological parameters of wide-band laser cladding on microstructure and sinterability of gradient bioceramics composite coating].

    Science.gov (United States)

    Liu, Qibin; Zhu, Weidong; Zou, Longjiang; Zheng, Min; Dong, Chuang

    2005-12-01

    The gradient bioceramics coating was prepared on the surface of Ti-6Al-4V alloy by using wide-band laser cladding. And the effect of technological parameters of wide-band laser cladding on microstructure and sinterability of gradient bioceramics composite coating was studied. The experimental results indicated that in the circumstances of size of laser doze D and scanning velocity V being fixed, with the increasement of power P, the density of microstructure in bioceramics coating gradually degraded; with the increasement of power P, the pore rate of bioceramics gradually became high. While P = 2.3 KW, the bioceramics coating with dense structure and lower pore rate (5.11%) was obtained; while P = 2.9 KW, the bioceramics coating with disappointing density was formed and its pore rate was up to 21.32%. The microhardness of bioceramics coating demonstrated that while P = 2.3 KW, the largest value of microhardness of bioceramics coating was 1100 HV. Under the condition of our research work, the optimum technological parameters for preparing gradient bioceramics coating by wide-band laser cladding are: P = 2.3 KW, V = 145 mm/min, D = 16 mm x 2 mm.

  1. Spectroscopic analysis of the density and temperature gradients in the laser-heated gas jet

    International Nuclear Information System (INIS)

    Matthews, D.L.; Lee, R.W.; Auerbach, J.M.

    1981-01-01

    We have performed an analysis of the x-ray spectra produced by a 1.0TW, lambda/sub L/-0.53μm laser-irradiated gas jet. Plasmas produced by ionization of neon, argon and N 2 + SF 6 gases were included in those measurements. Plasma electron density and temperature gradients were obtained by comparison of measured spectra with those produced by computer modeling. Density gradients were also obtained using laser interferometry. The limitations of this technique for plasma diagnosis will be discussed

  2. Generation of highly collimated high-current ion beams by skin-layer laser-plasma interaction at relativistic laser intensities

    International Nuclear Information System (INIS)

    Badziak, J.; Jablonski, S.; Glowacz, S.

    2006-01-01

    Generation of fast ion beams by laser-induced skin-layer ponderomotive acceleration has been studied using a two-dimensional (2D) two-fluid relativistic computer code. It is shown that the key parameter determining the spatial structure and angular divergence of the ion beam is the ratio d L /L n , where d L is the laser beam diameter and L n is the plasma density gradient scale length. When d L >>L n , a dense highly collimated megaampere ion (proton) beam of the ion current density approaching TA/cm 2 can be generated by skin-layer ponderomotive acceleration, even with a tabletop subpicosecond laser

  3. High voltage switch triggered by a laser-photocathode subsystem

    Science.gov (United States)

    Chen, Ping; Lundquist, Martin L.; Yu, David U. L.

    2013-01-08

    A spark gap switch for controlling the output of a high voltage pulse from a high voltage source, for example, a capacitor bank or a pulse forming network, to an external load such as a high gradient electron gun, laser, pulsed power accelerator or wide band radar. The combination of a UV laser and a high vacuum quartz cell, in which a photocathode and an anode are installed, is utilized as triggering devices to switch the spark gap from a non-conducting state to a conducting state with low delay and low jitter.

  4. Compensating the electron beam energy spread by the natural transverse gradient of laser undulator in all-optical x-ray light sources.

    Science.gov (United States)

    Zhang, Tong; Feng, Chao; Deng, Haixiao; Wang, Dong; Dai, Zhimin; Zhao, Zhentang

    2014-06-02

    All-optical ideas provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this paper, the beam energy spread effect is proposed to be significantly compensated by the natural transverse gradient of a laser undulator when properly transverse-dispersing the electron beam. Theoretical analysis and numerical simulations on conventional laser-Compton scattering sources and high-gain all-optical x-ray free-electron lasers with the electron beams from laser-plasma accelerators are presented.

  5. Emission characteristics of laser and superluminescent diodes with a gradient-index waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Bazarov, A.E.; Garmash, I.A.; Goldobin, I.S.; Eliukhin, V.A.; Pak, G.T.

    1987-05-01

    A study is made of the emission characteristics of laser and superluminescent diodes with gradient-index waveguides based on Al(x)Ga(1-x)As solid solutions, operating in the CW mode at room temperature. The coupling coefficients for a single-mode fiber are 25 and 18 percent for laser and superluminescent diodes, respectively, when an interface device consisting of three microlenses is used. 6 references.

  6. Study of laser driven plasma based electron acceleration and Bremsstrahlung radiation emission using ultra-high intensity laser pulses

    International Nuclear Information System (INIS)

    Rao, B.S.

    2013-01-01

    High energy particle accelerators are one of the most important inventions of the twentieth century which have led to enormous advances in basic scientific understanding of world around us. Despite their grand success, the present day high energy accelerators are hitting practical limits due to their large size and cost. This is because the accelerating gradients in conventional radio-frequency (RF) accelerators are typically limited to < 50 MV/m by the field breakdown of the accelerating structure. To address this major issue, many advanced accelerator techniques have been proposed and some of them are being actively pursued. Laser wakefield acceleration (LWFA) in plasma medium is one of the techniques being most actively pursued world over due to extremely large acceleration gradients of the order of 100 GV/m possible in this scheme which promises significant reduction of the size and cost of the future high energy accelerators. The present thesis work mainly deals with laser wakefield acceleration (LWFA) of self-injected electrons to 10s of MeV energy in plasma medium of length of the order of 500 μm using the table-top 10 TW laser at Laser Plasma Division, Raja Ramanna Centre for Advanced Technology

  7. High Gradient Accelerator Research

    International Nuclear Information System (INIS)

    Temkin, Richard

    2016-01-01

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  8. A compact high-gradient 25 MeV 17 GHz RF linac for free-electron laser research

    International Nuclear Information System (INIS)

    Danly, B.G.; Chen, S.C.; Kreischer, K.E.

    1995-01-01

    A new compact high-gradient (60 MeV/m) high-frequency (17.136 GHz) RF linac is presently under construction by Haimson Research Corp. (HRC) for installation at the MIT Plasma Fusion Center in the High-Gradient Accelerator and High Power Microwave Laboratory. This accelerator will utilize an existing traveling-wave relativistic klystron (TWRK) which is now operation at MIT with 25 MW power, 67 dB gain, and 52% efficiency at 17.136 GHz

  9. Spinodal decomposition in AISI 316L stainless steel via high-speed laser remelting

    Energy Technology Data Exchange (ETDEWEB)

    Chikarakara, Evans, E-mail: evans.chikarakara2@mail.dcu.ie [Advanced Processing Technology Research Centre, Dublin City University, Dublin (Ireland); Naher, Sumsun, E-mail: sumsun.naher@city.ac.uk [School of Engineering and Mathematical Sciences, City University London (United Kingdom); Brabazon, Dermot, E-mail: dermot.brabazon@dcu.ie [Advanced Processing Technology Research Centre, Dublin City University, Dublin (Ireland)

    2014-05-01

    A 1.5 kW CO{sub 2} pulsed laser was used to melt the surface of AISI 316L stainless steel with a view to enhancing the surface properties for engineering applications. A 90 μm laser beam spot size focused onto the surface was used to provide high irradiances (up to 23.56 MW/cm{sup 2}) with low residence times (as low as 50 μs) in order to induce rapid surface melting and solidification. Variations in microstructure at different points within the laser treated region were investigated. From this processing refined lamellar and nodular microstructures were produced. These sets of unique microstructures were produced within the remelted region when the highest energy densities were selected in conjunction with the lowest residence times. The transformation from the typical austenitic structure to much finer unique lamellar and nodular structures was attributed to the high thermal gradients achieved using these selected laser processing parameters. These structures resulted in unique characteristics including elimination of cracks and a reduction of inclusions within the treated region. Grain structure reorientation between the bulk alloy and laser-treated region occurred due to the induced thermal gradients. This present article reports on microstructure forms resulting from the high-speed laser surface remelting and corresponding underlying kinetics.

  10. Laser focusing of high-energy charged-particle beams

    International Nuclear Information System (INIS)

    Channell, P.J.

    1986-01-01

    It is shown that laser focusing of high-energy charged-particle beams using the inverse Cherenkov effect is well suited for applications with large linear colliders. Very high gradient (>0.5 MG/cm) lenses result that can be added sequentially without AG cancellation. These lenses are swell understood, have small geometric aberrations, and offer the possibility of correlating phase and energy aberrations to produce an achromatic final focus

  11. Polarization-gradient laser cooling as a way to create strongly localized structures for atom lithography

    International Nuclear Information System (INIS)

    Prudnikov, O. N.; Taichenachev, A. V.; Tumaikin, A. M.; Yudin, V. I.

    2007-01-01

    Generally, conditions for deep sub-Doppler laser cooling do not match conditions for strong atomic localization, that takes place in a deeper optical potential and leads to higher temperature. Moreover, for a given detuning in a deep optical potential the secular approximation, which is frequently used for a quantum description of laser cooling, fails. Here we investigate the atomic localization in optical potential, using a full quantum approach for atomic density matrix beyond the secular approximation. It is shown that laser cooling in a deep optical potential, created by a light field with polarization gradients, can be used as an alternative method for the formation of high contrast spatially localized structures of atoms for the purposes of atom lithography and atomic nanofabrication. Finally, we analyze possible limits for the width and contrast of localized atomic structures that can be reached in this type of light mask

  12. Microstructure and osteoblast response of gradient bioceramic coating on titanium alloy fabricated by laser cladding

    International Nuclear Information System (INIS)

    Zheng Min; Fan Ding; Li Xiukun; Li Wenfei; Liu Qibin; Zhang Jianbin

    2008-01-01

    To construct a bioactive interface between metal implant and the surrounding bone tissue, the gradient calcium phosphate bioceramic coating on titanium alloy (Ti-6Al-4V) was designed and fabricated by laser cladding. The results demonstrated that the gradient bioceramic coating was metallurgically bonded to the titanium alloy substrate. The appearance of hydroxyapatite and β-tricalcium phosphate indicated that the bioactive phases were synthesized on the surface of coating. The microhardness gradually decreased from the coating to substrate, which could help stress relaxation between coating and bone tissue. Furthermore, the methyl thiazolyl tetrazolium (MTT) assay of cell proliferation revealed that the laser-cladded bioceramic coating had more favorable osteoblast response compared with the surface of untreated titanium alloy substrate

  13. Microstructure and osteoblast response of gradient bioceramic coating on titanium alloy fabricated by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Min [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China)], E-mail: zhminmin@sina.com; Fan Ding; Li Xiukun [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Li Wenfei; Liu Qibin [College of Materials Science and Engineering, Guizhou University, Guiyang 550003 (China); Zhang Jianbin [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China)

    2008-11-15

    To construct a bioactive interface between metal implant and the surrounding bone tissue, the gradient calcium phosphate bioceramic coating on titanium alloy (Ti-6Al-4V) was designed and fabricated by laser cladding. The results demonstrated that the gradient bioceramic coating was metallurgically bonded to the titanium alloy substrate. The appearance of hydroxyapatite and {beta}-tricalcium phosphate indicated that the bioactive phases were synthesized on the surface of coating. The microhardness gradually decreased from the coating to substrate, which could help stress relaxation between coating and bone tissue. Furthermore, the methyl thiazolyl tetrazolium (MTT) assay of cell proliferation revealed that the laser-cladded bioceramic coating had more favorable osteoblast response compared with the surface of untreated titanium alloy substrate.

  14. Dynamics of Gradient Bioceramic Composite Coating on Surface of Titanium Alloy by Wide-Band Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    LIU Qi-bin; ZOU Long-jiang; ZHU Wei-dong; LI Hai-tao; DONG Chuang

    2004-01-01

    The gradient bioceramic coating was prepared on the surface of titanium alloy using wide-band laser cladding. The dynamics of gradient bioceramic composite coating containing hydroxyapatite (HA) prepared with mixture of CaHPO4*2H2O and CaCO3 under the condition of wide-band laser was studied theoretically. The corresponding mathematical model and its numerical solution were presented. The examination experiment showed that HA bioceramic composite coatings can be obtained by appropriately choosing wide-band laser cladding parameters. The microstructure and surface morphology of HA bioceramic coating were observed by SEM and X-ray diffraction. The experimental results showed that the bioceramic coating is composed of HA, β-TCP, CaO, CaTiO3 and TiO2. The surface of bioceramic coating takes coral-shaped structure or short-rod piled structure, which helps osteoblast grow into bioceramic and improves the biocompatibility.

  15. A study of TiB2/TiB gradient coating by laser cladding on titanium alloy

    Science.gov (United States)

    Lin, Yinghua; Lei, Yongping; Li, Xueqiao; Zhi, Xiaohui; Fu, Hanguang

    2016-07-01

    TiB2/TiB gradient coating has been fabricated by a laser cladding technique on the surface of a Ti-6Al-4V substrate using TiB2 powder as the cladding material. The microstructure and mechanical properties of the gradient coating were analyzed by SEM, EPMA, XRD, TEM and an instrument to measure hardness. With the increasing distance from the coating surface, the content of TiB2 particles gradually decreased, but the content of TiB short fibers gradually increased. Meanwhile, the micro-hardness and the elastic modulus of the TiB2/TiB coating showed a gradient decreasing trend, but the fracture toughness showed a gradient increasing trend. The fracture toughness of the TiB2/TiB coating between the center and the bottom was improved, primarily due to the debonding of TiB2 particles and the high fracture of TiB short fibers, and the fracture position of TiB short fiber can be moved to an adjacent position. However, the debonding of TiB2 particles was difficult to achieve at the surface of the TiB2/TiB coating.

  16. Development of longer Nd:LGGG crystal for high power laser application

    Science.gov (United States)

    Yin, Yanru; Tian, Hanlin; Zhang, Jian; Mu, Wenxiang; Zhang, Baitao; Jia, Zhitai; He, Jingliang; Tao, Xutang

    2017-11-01

    In order to further improve the Nd3+:(LuxGd1-x)3Ga5O12 (Nd:LGGG) crystal performance in high power laser field, a long Nd:LGGG crystal with dimensions of Φ 23 × 112 mm3 has been grown successfully by the Czochralski (Cz) method for laser rod fabrication. Compared with the normal size LGGG crystals (like 30-50 mm in length), we overcame several difficulties in the growth of longer ones, including crystal cracking by a large longitudinal temperature gradient, spiral growth by a small radial temperature gradient, and growth instability and even constitutional super cooling by Ga2O3 volatilizing continuously. The doping concentrations of Nd3+ and Lu3+ in the as-grown crystal and the crystal optical quality have been measured. The performance of diode-side-pumped Nd:LGGG rod laser has been preliminarily tested for the first time, simply by replacing the Nd:YAG crystal rod inside a commercial laser module. Under an incident pump power of 160 W, the maximum continuous wave output power of 38 W has been obtained, corresponding to an optical-optical conversion efficiency of 23.8% and a slope efficiency of 40.8%, respectively.

  17. Magnetoelectric Transverse Gradient Sensor with High Detection Sensitivity and Low Gradient Noise.

    Science.gov (United States)

    Zhang, Mingji; Or, Siu Wing

    2017-10-25

    We report, theoretically and experimentally, the realization of a high detection performance in a novel magnetoelectric (ME) transverse gradient sensor based on the large ME effect and the magnetic field gradient (MFG) technique in a pair of magnetically-biased, electrically-shielded, and mechanically-enclosed ME composites having a transverse orientation and an axial separation. The output voltage of the gradient sensor is directly obtained from the transverse MFG-induced difference in ME voltage between the two ME composites and is calibrated against transverse MFGs to give a high detection sensitivity of 0.4-30.6 V/(T/m), a strong common-mode magnetic field noise rejection rate of gradient noise of 0.16-620 nT/m/ Hz in a broad frequency range of 1 Hz-170 kHz under a small baseline of 35 mm. An analysis of experimental gradient noise spectra obtained in a magnetically-unshielded laboratory environment reveals the domination of the pink (1/ f ) noise, dielectric loss noise, and power-frequency noise below 3 kHz, in addition to the circuit noise above 3 kHz, in the gradient sensor. The high detection performance, together with the added merit of passive and direct ME conversion by the large ME effect in the ME composites, makes the gradient sensor suitable for the passive, direct, and broadband detection of transverse MFGs.

  18. High Resolution Studies Of Lensed z ∼ 2 Galaxies: Kinematics And Metal Gradients

    Science.gov (United States)

    Leethochawalit, Nicha

    2016-09-01

    We use the OSIRIS integral field unit (IFU) spectograph to secure spatially-resolved strong emission lines of 15 gravitationally-lensed star-forming galaxies at redshift z ∼ 2. With the aid of gravitational lensing and Keck laser-assisted adaptive optics, the spatial resolution of these sub-luminous galaxies is at a few hundred parsecs. First, we demonstrate that high spatial resolution is crucial in diagnosing the kinematic properties and dynamical maturity of z ∼ 2 galaxies. We observe a significantly lower fraction of rotationally-supported systems than what has been claimed in lower spatial resolution surveys. Second, we find a much larger fraction of z ∼ 2 galaxies with weak metallicity gradients, contrary to the simple picture suggested by earlier studies that well-ordered rotation develops concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydronamical simulations, strong feedback is likely to play a key role in flattening metal gradients in early star-forming galaxies.

  19. Coreless Concept for High Gradient Induction Cell

    International Nuclear Information System (INIS)

    Krasnykh, Anatoly

    2008-01-01

    An induction linac cell for a high gradient is discussed. The proposed solid state coreless approach for the induction linac topology (SLIM(reg s ign)) is based on nanosecond mode operation. This mode may have an acceleration gradient comparable with gradients of rf- accelerator structures. The discussed induction system has the high electric efficiency. The key elements are a solid state semiconductor switch and a high electric density dielectric with a thin section length. The energy in the induction system is storied in the magnetic field. The nanosecond current break-up produces the high voltage. The induced voltage is used for acceleration. This manner of an operation allows the use of low voltage elements in the booster part and achieves a high accelerating gradient. The proposed topology was tested in POP (proof of principle) experiments

  20. Relativistic klystrons for high-gradient accelerators

    International Nuclear Information System (INIS)

    Westenskow, G.A.; Aalberts, D.P.; Boyd, J.K.; Deis, G.A.; Houck, T.L.; Orzechowski, T.J.; Ryne, R.D.; Yu, S.S.; Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W.; Hopkins, D.B.; Sessler, A.M.; Haimson, J.; Mecklenburg, B.

    1991-01-01

    Experimental work is being performed by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. The authors have learned how to overcome their previously reported problem of high power rf pulse shortening and have achieved peak rf power levels of 330 MW using an 11.4-GHz high-gain tube with multiple output structures. In these experiments the rf pulse is of the same duration as the beam current pulse. In addition, experiments have been performed on two short sections of a high-gradient accelerator using the rf power from a relativistic klystron. An average accelerating gradient of 84 MV/m has been achieved with 80-MW of rf power

  1. High gradient superconducting quadrupoles

    International Nuclear Information System (INIS)

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

  2. Laser-plasma harmonics with high-contrast pulses and designed prepulses

    International Nuclear Information System (INIS)

    Marjoribanks, R. S.; Zhao, L.; Budnik, F. W.; Kulcsar, G.; Vitcu, A.; Higaki, H.; Wagner, R.; Maksimchuk, A.; Umstadter, D.; Le Blanc, S. P.; Downer, M. C.

    1998-01-01

    One aspect of the complexity of mid- and high-harmonic generation in high-intensity laser-plasma interactions is that nonlinear hydrodynamics is virtually always folded together with the nonlinear optical conversion process. We have partly dissected this issue in picosecond and subpicosecond interactions with preformed plasma gradients, imaging and spectrally resolving low- and mid-order harmonics. We describe spatial breakup of the picosecond beam in preformed plasmas, concomitant broadening and breakup of the harmonic spectrum, presumably through self-phase modulation, together with data on the sensitivity of harmonics production efficiency to the gradient or extent of preformed plasma. Lastly, we show preliminary data of regular Stokes-like and anti-Stokes-like satellites to the harmonics, accompanied by modification of the forward-scattered beam

  3. Design study of high gradient, low impedance accelerating structures for the FERMI free electron laser linac upgrade

    Science.gov (United States)

    Shafqat, N.; Di Mitri, S.; Serpico, C.; Nicastro, S.

    2017-09-01

    The FERMI free-electron laser (FEL) of Elettra Sincrotrone Trieste, Italy, is a user facility driven by a 1.5 GeV 10-50 Hz S-band radiofrequency linear accelerator (linac), and it is based on an external laser seeding scheme that allows lasing at the shortest fundamental wavelength of 4 nm. An increase of the beam energy to 1.8 GeV at a tolerable breakdown rate, and an improvement of the final beam quality is desired in order to allow either lasing at 4 nm with a higher flux, or lasing at shorter wavelengths. This article presents the impedance analysis of newly designed S-band accelerating structures, for replacement of the existing backward travelling wave structures (BTWS) in the last portion of the FERMI linac. The new structure design promises higher accelerating gradient and lower impedance than those of the existing BTWS. Particle tracking simulations show that, with the linac upgrade, the beam relative energy spread, its linear and nonlinear z-correlation internal to the bunch, and the beam transverse emittances can be made smaller than the ones in the present configuration, with expected advantage to the FEL performance. The repercussion of the upgrade on the linac quadrupole magnets setting, for a pre-determined electron beam optics, is also considered.

  4. 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

  5. HG2006 Workshop on High-Gradient Radio Frequency

    CERN Multimedia

    2006-01-01

    Meeting to be held at CERN on 25-27 September 2006 in Room 40/S2-B01 (Building 40). The objective of the workshop is to bring the high-gradient RF community together to present and discuss recent theoretical and experimental developments. Significant progress has recently been made in understanding the basic physics of rf breakdown and developing techniques for achieving higher gradients. This workshop should contribute to maintaining these efforts and to promoting contacts and collaboration. The scientific programme will be organized in half day sessions dedicated to: High-gradient rf experimental results Theory and computation High-gradient technology, materials and processing Specialized experiments on related high-gradient or high-power phenomenon like dc discharge and pulsed surface heating Reports from collaborations and projects. Each session will consist of selected presentations followed by a dedicated discussion. Information about the meeting and participant registration is available at http...

  6. Magnetoelectric Transverse Gradient Sensor with High Detection Sensitivity and Low Gradient Noise

    OpenAIRE

    Zhang, Mingji; Or, Siu Wing

    2017-01-01

    We report, theoretically and experimentally, the realization of a high detection performance in a novel magnetoelectric (ME) transverse gradient sensor based on the large ME effect and the magnetic field gradient (MFG) technique in a pair of magnetically-biased, electrically-shielded, and mechanically-enclosed ME composites having a transverse orientation and an axial separation. The output voltage of the gradient sensor is directly obtained from the transverse MFG-induced difference in ME vo...

  7. A model to describe the surface gradient-nanograin formation and property of friction stir processed laser Co-Cr-Ni-Mo alloy

    Science.gov (United States)

    Li, Ruidi; Yuan, Tiechui; Qiu, Zili

    2014-07-01

    A gradient-nanograin surface layer of Co-base alloy was prepared by friction stir processing (FSP) of laser-clad coating in this work. However, it is lack of a quantitatively function relationship between grain refinement and FSP conditions. Based on this, an analytic model is derived for the correlations between carbide size, hardness and rotary speed, layer depth during in-situ FSP of laser-clad Co-Cr-Ni-Mo alloy. The model is based on the principle of typical plastic flow in friction welding and dynamic recrystallization. The FSP experiment for modification of laser-clad Co-based alloy was conducted and its gradient nanograin and hardness were characterized. It shows that the model is consistent with experimental results.

  8. Characteristics of single-atom trapping in a magneto-optical trap with a high magnetic-field gradient

    International Nuclear Information System (INIS)

    Yoon, Seokchan; Choi, Youngwoon; Park, Sangbum; Ji, Wangxi; Lee, Jai-Hyung; An, Kyungwon

    2007-01-01

    A quantitative study on characteristics of a magneto-optical trap with a single or a few atoms is presented. A very small number of 85 Rb atoms were trapped in a micron-size magneto-optical trap with a high magnetic-field gradient. In order to find the optimum condition for a single-atom trap, we have investigated how the number of atoms and the size of atomic cloud change as various experimental parameters, such as a magnetic-field gradient and the trapping laser intensity and detuning. The averaged number of atoms was measured very accurately with a calibration procedure based on the single-atom saturation curve of resonance fluorescence. In addition, the number of atoms in a trap could be controlled by suppressing stochastic loading events by means of a real-time active feedback on the magnetic-field gradient

  9. Vacuum laser acceleration using a radially polarized CO sub 2 laser beam

    CERN Document Server

    Liu, Y; He, P

    1999-01-01

    Utilizing the high-power, radially polarized CO sub 2 laser and high-quality electron beam at the Brookhaven Accelerator Test Facility, a vacuum laser acceleration scheme is proposed. In this scheme, optics configuration is simple, a small focused beam spot size can be easily maintained, and optical damage becomes less important. At least 0.5 GeV/m acceleration gradient is achievable by 1 TW laser power.

  10. High Ra, high Pr convection with viscosity gradients

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. High Ra, high Pr convection with viscosity gradients. Weak upward flow through mesh. Top fluid more viscous. Unstable layer Instability Convection.

  11. Gradient Alloy for Optical Packaging

    Data.gov (United States)

    National Aeronautics and Space Administration — Advances in additive manufacturing, such as Laser Engineered Net Shaping (LENS), enables the fabrication of compositionally gradient microstructures, i.e. gradient...

  12. Dynamic phasing of multichannel cw laser radiation by means of a stochastic gradient algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V A; Volkov, M V; Garanin, S G; Dolgopolov, Yu V; Kopalkin, A V; Kulikov, S M; Starikov, F A; Sukharev, S A; Tyutin, S V; Khokhlov, S V; Chaparin, D A [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation)

    2013-09-30

    The phasing of a multichannel laser beam by means of an iterative stochastic parallel gradient (SPG) algorithm has been numerically and experimentally investigated. The operation of the SPG algorithm is simulated, the acceptable range of amplitudes of probe phase shifts is found, and the algorithm parameters at which the desired Strehl number can be obtained with a minimum number of iterations are determined. An experimental bench with phase modulators based on lithium niobate, which are controlled by a multichannel electronic unit with a real-time microcontroller, has been designed. Phasing of 16 cw laser beams at a system response bandwidth of 3.7 kHz and phase thermal distortions in a frequency band of about 10 Hz is experimentally demonstrated. The experimental data are in complete agreement with the calculation results. (control of laser radiation parameters)

  13. Dependence of high order harmonics intensity on laser focal spot position in preformed plasma plumes

    International Nuclear Information System (INIS)

    Singhal, H.; Ganeev, R.; Naik, P. A.; Arora, V.; Chakravarty, U.; Gupta, P. D.

    2008-01-01

    The dependence of the high-order harmonic intensity on the laser focal spot position in laser produced plasma plumes is experimentally studied. High order harmonics up to the 59th order (λ∼13.5 nm) were generated by focusing 48 fs laser pulses from a Ti:sapphire laser system in silver plasma plume produced using 300 ps uncompressed laser radiation as the prepulse. The intensity of harmonics nearly vanished when the best focus was located in the plume center, whereas it peaked on either side with unequal intensity. The focal spot position corresponding to the peak harmonic intensity moved away from the plume center for higher order harmonics. The results are explained in terms of the variation of phase mismatch between the driving laser beam and harmonics radiation produced, relativistic drift of electrons, and defocusing effect due to radial ionization gradient in the plasma for different focal spot positions

  14. On the physics of electron ejection from laser-irradiated overdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Thévenet, M.; Vincenti, H.; Faure, J. [Laboratoire d' Optique Appliquée, ENSTA ParisTech, CNRS, Ecole Polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau Cedex (France)

    2016-06-15

    Using 1D and 2D PIC simulations, we describe and model the backward ejection of electron bunches when a laser pulse reflects off an overdense plasma with a short density gradient on its front side. The dependence on the laser intensity and gradient scale length is studied. It is found that during each laser period, the incident laser pulse generates a large charge-separation field, or plasma capacitor, which accelerates an attosecond bunch of electrons toward vacuum. This process is maximized for short gradient scale lengths and collapses when the gradient scale length is comparable to the laser wavelength. We develop a model that reproduces the electron dynamics and the dependence on laser intensity and gradient scale length. This process is shown to be strongly linked with high harmonic generation via the Relativistic Oscillating Mirror mechanism.

  15. High quality electron beams from a plasma channel guided laser wakefield accelerator

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, Cs.; Tilborg, J. van; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2004-01-01

    Laser driven accelerators, in which particles are accelerated by the electric field of a plasma wave driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV/m. These fields are thousands of times those achievable in conventional radiofrequency (RF) accelerators, spurring interest in laser accelerators as compact next generation sources of energetic electrons and radiation. To date however, acceleration distances have been severely limited by lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low energy beams with 100% electron energy spread, limiting applications. Here we demonstrate that a relativistically intense laser can be guided by a preformed plasma density channel and that the longer propagation distance can result in electron beams of percent energy spread with low emittance and increased energy, containing >10 9 electrons above 80 MeV. The preformed plasma channel technique forms the basis of a new class of accelerators, combining beam quality comparable to RF accelerators with the high gradients of laser accelerators to produce compact tunable high brightness electron and radiation sources

  16. Berkeley Lab Laser Accelerator (BELLA) facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Berkeley Lab Laser Accelerator (BELLA) facility (formerly LOASIS) develops advanced accelerators and radiation sources. High gradient (1-100 GV/m) laser-plasma...

  17. Phase locking of a seven-channel continuous wave fibre laser system by a stochastic parallel gradient algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, M V; Garanin, S G; Dolgopolov, Yu V; Kopalkin, A V; Kulikov, S M; Sinyavin, D N; Starikov, F A; Sukharev, S A; Tyutin, S V; Khokhlov, S V; Chaparin, D A [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation)

    2014-11-30

    A seven-channel fibre laser system operated by the master oscillator – multichannel power amplifier scheme is the phase locked using a stochastic parallel gradient algorithm. The phase modulators on lithium niobate crystals are controlled by a multichannel electronic unit with the microcontroller processing signals in real time. The dynamic phase locking of the laser system with the bandwidth of 14 kHz is demonstrated, the time of phasing is 3 – 4 ms. (fibre and integrated-optical structures)

  18. Prospects for compact high-intensity laser synchrotron x-ray and gamma sources

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.

    1996-11-01

    A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high-brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power CO 2 laser may be used as prototype LSS brick stones. In a feasible demonstration experiment, 10-GW, 100-ps CO 2 laser beam will be brought to a head-on collision with a 10-ps, 0.5-nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 angstrom) x-rays of 10-ps pulse duration, with a flux of ∼ 10 19 photons/sec, will be produced via linear Compton backscattering. The x-ray spectrum is tunable proportionally to the e-beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 10 22 photons/sec level, after the ongoing ATF CO 2 laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact ''table-top'' LSS of monochromatic gamma radiation may become feasible

  19. Prospects for compact high-intensity laser synchrotron x-ray and gamma sources

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.

    1997-01-01

    A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high- brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high- brightness electron beam and the high-power C0 2 laser may be used as prototype LSS brick stones. In a feasible demonstration experiment, 10 GW, 100 ps C0 2 laser beam will be brought to a head-on collision with a 10 ps, 0.5 nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 A) x-rays of 10-ps pulse duration, with a flux of ∼10 19 photons/sec, will be produced via linear Compton backscattering. The x-ray spectra is tunable proportionally to the e- beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 10 22 photon/sec level, after the ongoing ATF C0 2 laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact ''table- top'' LSS of monochromatic gamma radiation may become feasible

  20. Measurements of the temporal and spatial phase variations of a 33 GHz pulsed free electron laser amplifier and application to high gradient RF acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Volfbeyn, P.; Bekefi, G. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-12-31

    We report the results of temporal and spatial measurements of phase of a pulsed free electron laser amplifier (FEL) operating in combined wiggler and axial guide magnetic fields. The 33 GHz FEL is driven by a mildly relativistic electron beam (750 kV, 90-300 A, 30 ns) and generates 61 MW of radiation with a high power magnetron as the input source. The phase is measured by an interferometric technique from which frequency shifting is determined. The results are simulated with a computer code. Experimental studies on a CERN-CLIC 32.98 GHz 26-cell high gradient accelerating section (HGA) were carried out for input powers from 0.1 MW to 35 MW. The FEL served as the r.f. power source for the HGA. The maximum power in the transmitted pulse was measured to be 15 MW for an input pulse of 35 MW. The theoretically calculated shunt impedance of 116 M{Omega}/m predicts a field gradient of 65 MeV/m inside the HGA. For power levels >3MW the pulse transmitted through the HGA was observed to be shorter than the input pulse and pulse shortening became more serious with increasing power input. At the highest power levels the output pulse length (about 5 nsec) was about one quarter of the input pulse length. Various tests suggest that these undesirable effects occur in the input coupler to the HGA. Light and X-ray production inside the HGA have been observed.

  1. Thermal Conductivity and Thermal Gradient Cyclic Behavior of Refractory Silicate Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2001-01-01

    Plasma-sprayed mullite and BSAS coatings have been developed to protect SiC/SiC ceramic matrix composites from high temperature environmental attack. In this study, thermal conductivity and thermal barrier functions of these coating systems are evaluated using a laser high-heat-flux test rig. The effects of water vapor on coating thermal conductivity and durability are studied by using alternating furnace and laser thermal gradient cyclic tests. The influence of laser high thermal-gradient cycling on coating failure modes is also investigated.

  2. Longitudinal wake field for an electron beam accelerated through a ultra-high field gradient

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

    2006-12-15

    Electron accelerators with higher and higher longitudinal field gradients are desirable, as they allow for the production of high energy beams by means of compact and cheap setups. The new laser-plasma acceleration technique appears to constitute the more promising breakthrough in this direction, delivering unprecedent field gradients up to TV/m. In this article we give a quantitative description of the impact of longitudinal wake fields on the electron beam. Our paper is based on the solution of Maxwell's equations for the longitudinal field. Our conclusions are valid when the acceleration distance is much smaller than the the overtaking length, that is the length that electrons travel as a light signal from the tail of the bunch overtakes the head of the bunch. This condition is well verified for laser-plasma devices. We calculate a closed expression for the impedance and the wake function that may be evaluated numerically. It is shown that the rate of energy loss in the bunch due to radiative interaction is equal to the energy emitted through coherent radiation in the far-zone. Furthermore, an expression is found for the asymptotic limit of a large distance of the electron beam from the accelerator compared with the overtaking length. Such expression allows us to calculate analytical solutions for a Gaussian transverse and longitudinal bunch shape. Finally, we study the feasibility of Table-Top Free-Electron Lasers in the Vacuum Ultra-Violet (TT-VUV FEL) and X-ray range (TT-XFEL), respectively based on 100 MeV and 1 GeV laser-plasma accelerator drivers. Numerical estimations presented in this paper indicate that the effects of the time-dependent energy change induced by the longitudinal wake pose a serious threat to the operation of these devices. (orig.)

  3. Thermally Induced Ultra High Cycle Fatigue of Copper Alloys of the High Gradient Accelerating Structures

    CERN Document Server

    Heikkinen, Samuli; Wuensch, Walter

    2010-01-01

    In order to keep the overall length of the compact linear collider (CLIC), currently being studied at the European Organization for Nuclear Research (CERN), within reasonable limits, i.e. less than 50 km, an accelerating gradient above 100 MV/m is required. This imposes considerable demands on the materials of the accelerating structures. The internal surfaces of these core components of a linear accelerator are exposed to pulsed radio frequency (RF) currents resulting in cyclic thermal stresses expected to cause surface damage by fatigue. The designed lifetime of CLIC is 20 years, which results in a number of thermal stress cycles of the order of 2.33•1010. Since no fatigue data existed in the literature for CLIC parameter space, a set of three complementary experiments were initiated: ultra high cycle mechanical fatigue by ultrasound, low cycle fatigue by pulsed laser irradiation and low cycle thermal fatigue by high power microwaves, each test representing a subset of the original problem. High conductiv...

  4. Gradient twinned 304 stainless steels for high strength and high ductility

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Aiying [School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai (China); Liu, Jiabin; Wang, Hongtao [Institute of Applied Mechanics, Zhejiang University, Hangzhou (China); Lu, Jian, E-mail: jianlu@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Wang, Y. Morris, E-mail: ymwang@llnl.gov [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA (United States)

    2016-06-14

    Gradient materials often have attractive mechanical properties that outperform uniform microstructure counterparts. It remains a difficult task to investigate and compare the performance of various gradient microstructures due to the difficulty of fabrication, the wide range of length scales involved, and their respective volume percentage variations. We have investigated four types of gradient microstructures in 304 stainless steels that utilize submicrotwins, nanotwins, nanocrystalline-, ultrafine- and coarse-grains as building blocks. Tensile tests reveal that the gradient microstructure consisting of submicrotwins and nanotwins has a persistent and stable work hardening rate and yields an impressive combination of high strength and high ductility, leading to a toughness that is nearly 50% higher than that of the coarse-grained counterpart. Ex- and in-situ transmission electron microscopy indicates that nanoscale and submicroscale twins help to suppress and limit martensitic phase transformation via the confinement of martensite within the twin lamellar. Twinning and detwinning remain active during tensile deformation and contribute to the work hardening behavior. We discuss the advantageous properties of using submicrotwins as the main load carrier and nanotwins as the strengthening layers over those coarse and nanocrystalline grains. Our work uncovers a new gradient design strategy to help metals and alloys achieve high strength and high ductility.

  5. High-temperature stability of laser-joined silicon carbide components

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Marion, E-mail: marion.herrmann@tu-dresden.de; Lippmann, Wolfgang; Hurtado, Antonio

    2013-11-15

    Silicon carbide is recommended for applications in energy technology due to its good high-temperature corrosion resistance, mechanical durability, and abrasion resistance. The prerequisite for use is often the availability of suitable technologies for joining or sealing the components. A laser-induced process using fillers and local heating of the components represents a possible low-cost option. Investigations in which yttrium aluminosilicate glass was used for laser-induced brazing of SiC components of varying geometry are presented. A four-point bending strength of 112 MPa was found for these joints. In burst tests, laser-joined components were found to withstand internal pressures of up to 54 MPa. Helium leak tests yielded leak rates of less than 10{sup –8} mbar l s{sup −1}, even after 300 h at 900 °C. In contrast, the assemblies showed an increased leak rate after annealing at 1050 °C. The short process time of the laser technique – in the range of a few seconds to a few minutes – results in high temperature gradients and transients. SEM analysis showed that the filler in the seam predominantly solidifies in a glassy state. Crystallization occurred during later thermal loading of the joined components, with chemical equilibrium being established. Differences in seam structures yielded from different cooling rates in the laser process could not be equalized by annealing. The results demonstrated the long-term stability of laser-brazed SiC assemblies to temperatures in the range of glass transformation (900 °C) of the yttrium aluminosilicate filler. In technological investigations, the suitability of the laser joining technique for sealing of SiC components with a geometry approximating that of a fuel element sleeve pin (pin) in a gas-cooled fast reactor was proven.

  6. High resolution temperature mapping of gas turbine combustor simulator exhaust with femtosecond laser induced fiber Bragg gratings

    Science.gov (United States)

    Walker, Robert B.; Yun, Sangsig; Ding, Huimin; Charbonneau, Michel; Coulas, David; Lu, Ping; Mihailov, Stephen J.; Ramachandran, Nanthan

    2017-04-01

    Femtosecond infrared (fs-IR) laser written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent in advanced gas turbine engines under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring exhaust temperature gradients of a gas turbine combustor simulator. Results include: contour plots of measured temperature gradients, contrast with thermocouple data.

  7. New solid laser: Ceramic laser. From ultra stable laser to ultra high output laser

    International Nuclear Information System (INIS)

    Ueda, Kenichi

    2006-01-01

    An epoch-making solid laser is developed. It is ceramic laser, polycrystal, which is produced as same as glass and shows ultra high output. Ti 3+ :Al 2 O 3 laser crystal and the CPA (chirped pulse amplification) technique realized new ultra high output lasers. Japan has developed various kinds of ceramic lasers, from 10 -2 to 67 x 10 3 w average output, since 1995. These ceramic lasers were studied by gravitational radiation astronomy. The scattering coefficient of ceramic laser is smaller than single crystals. The new fast ignition method is proposed by Institute of Laser Engineering of Osaka University, Japan. Ultra-intense short pulse laser can inject the required energy to the high-density imploded core plasma within the core disassembling time. Ti 3+ :Al 2 O 3 crystal for laser, ceramic YAG of large caliber for 100 kW, transparent laser ceramic from nano-crystals, crystal grain and boundary layer between grains, the scattering coefficient of single crystal and ceramic, and the derived release cross section of Yb:YAG ceramic are described. (S.Y.)

  8. High temperature semiconductor diode laser pumps for high energy laser applications

    Science.gov (United States)

    Campbell, Jenna; Semenic, Tadej; Guinn, Keith; Leisher, Paul O.; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

    2018-02-01

    Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. To mitigate this thermal management burden, it is desirable for diode pumps to operate efficiently at high heat sink temperatures. In this work, we have developed a scalable cooling architecture, based on jet-impingement technology with industrial coolant, for efficient cooling of diode laser bars. We have demonstrated 60% electrical-to-optical efficiency from a 9xx nm two-bar laser stack operating with propylene-glycolwater coolant, at 50 °C coolant temperature. To our knowledge, this is the highest efficiency achieved from a diode stack using 50 °C industrial fluid coolant. The output power is greater than 100 W per bar. Stacks with additional laser bars are currently in development, as this cooler architecture is scalable to a 1 kW system. This work will enable compact and robust fiber-coupled diode pump modules for high energy laser applications.

  9. Investigation on the parameter optimization and performance of laser cladding a gradient composite coating by a mixed powder of Co50 and Ni/WC on 20CrMnTi low carbon alloy steel

    Science.gov (United States)

    Shi, Yan; Li, Yunfeng; Liu, Jia; Yuan, Zhenyu

    2018-02-01

    In this study, a gradient composite coating was manufactured on 20CrMnTi alloy steel by laser cladding. The laser power, cladding scan velocity and powder flow rate were selected as influencing factors of the orthogonal cladding experiments. The influencing factors were optimized by the comprehensive analysis of Taguchi OA and TOPSIS method. The high significant parameters and the predicted results were confirmed by the ANOVA method. The macromorphology and microstructures are characterized by using laser microscope, SEM, XRD and microhardness tester. Comparison tests of wear resistance of gradient composite coating, 20CrMnTi cemented quenching sample and the 20CrMnTi sample were conducted on the friction-wear tester. The results show that the phases are γ-Co solid solution, Co3B, M23C6 and etc. The interlayers and wear-resisting layer also contain new hard phases as WC, W2C. The microhardness of the gradient coating was increased to 3 times as compared with that of the 20CrMnTi substrate. The wear resistance of the gradient composite coating and 20CrMnTi cemented quenching sample was enhanced to 36.4 and 15.9 times as compared with that of the 20CrMnTi.

  10. A high-gradient high-duty-factor Rf photo-cathode electron gun

    International Nuclear Information System (INIS)

    Rimmer, Robert A.; Hartman, Neal; Lidia, Steven M.; Wang, Shaoheng

    2002-01-01

    We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

  11. A high-gradient high-duty-factor RF photo-cathode electron gun

    International Nuclear Information System (INIS)

    Rimmer, Robert; Hartman, N.; Lidia, S.; Wang, S.H.

    2002-01-01

    We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

  12. Research on a wavefront aberration calculation method for a laser energy gradient attenuator

    International Nuclear Information System (INIS)

    Dong, Tingting; Han, Xu; Chen, Chi; Fu, Yuegang; Li, Ming

    2013-01-01

    When a laser energy gradient attenuator is working, there is an inhomogeneous temperature distribution in the whole of the glass because of the non-uniform light energy absorption. This will lead to optical performance reduction. An integrated opto-thermal–mechanical method is proposed to calculate the wavefront aberration for analysis of the thermal effect of the system. Non-sequential optical analysis is used for computing the absorbed energy distribution. The finite element analysis program solves the temperature distribution and the deformations of nodes on the surfaces. An interface routine is created to fit the surface shape and the index field, and extended Zernike polynomials are introduced to get a higher fitting precision. Finally, the parameters are imported to the CodeV optical design program automatically, and the user defined gradient index material is ray traced to obtain the wavefront aberration. The method can also be used in other optical systems for thermal effect analysis. (letter)

  13. Engineering design of the interaction waveguide for high-power accelerator-driven microwave free-electron lasers

    International Nuclear Information System (INIS)

    Hopkins, D.B.; Clay, H.W.; Stallard, B.W.; Throop, A.L.; Listvinsky, G.; Makowski, M.A.

    1989-01-01

    Linear induction accelerators (LIAs) operating at beam energies of a few million electron volts and currents of a few thousand amperes are suitable drivers for free-electron lasers (FELs). Such lasers are capable of producing gigawatts of peak power and megawatts of average power at microwave frequencies. Such devices are being studied as possible power sources for future high-gradient accelerators and are being constructed for plasma heating applications. At high power levels, the engineering design of the interaction waveguide presents a challenge. This paper discusses several concerns, including electrical breakdown and metal fatigue limits, choice of material, and choice of operating propagation mode. 13 refs., 3 figs

  14. Teradiode's high brightness semiconductor lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

    2016-03-01

    TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

  15. CERN/KEK: Very high accelerating gradients

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1993-01-15

    Full text: A world-wide effort is under way to develop linear electron-positron colliders so that physics experiments can be extended into a range of energies where circular machines (necessarily much larger than CERN's 27-kilometre LEP machine) would be crippled by synchrotron radiation. CERN is studying the feasibility of building a 2 TeV machine called CLIC powered not by individual klystrons, but by a high intensity electron 'drive' linac running parallel to the main linac (November 1990, page 7). This drive linac will itself be powered by similar superconducting cavities to those developed for LEP. A high gradient is an obvious design aim for any future high energy linear collider because it makes it shorter and therefore cheaper - the design figure for the CLIC machine is 80 MV/m. The CLIC study group has taken a significant step forward in demonstrating the technical feasibility of their machine by achieving peak and average accelerating gradients of 137 MV/m and 84 MV/m respectively in a short section of accelerating structure during high gradient tests at the Japanese KEK Laboratory last year. This result obtained within the framework of a CERN/KEK collaboration on linear colliders was obtained using a 20-cell accelerating section built at CERN using state-of the- art technology which served both as a model for CLIC studies as well as a prototype for the Japanese Linear Collider studies. The operating frequency of the model accelerating section is 2.6 times lower than the CLIC frequency but was chosen because a high power r.f. source and pulse compression scheme has been developed for this frequency at KEK. Testing CLIC models at 11.4 GHz is however more stringent than at 30 GHz because the chance of electrical breakdown increases as the frequency is lowered. This recent result clearly demonstrates that a gradient of 80 MV/m is feasible.

  16. CERN/KEK: Very high accelerating gradients

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    Full text: A world-wide effort is under way to develop linear electron-positron colliders so that physics experiments can be extended into a range of energies where circular machines (necessarily much larger than CERN's 27-kilometre LEP machine) would be crippled by synchrotron radiation. CERN is studying the feasibility of building a 2 TeV machine called CLIC powered not by individual klystrons, but by a high intensity electron 'drive' linac running parallel to the main linac (November 1990, page 7). This drive linac will itself be powered by similar superconducting cavities to those developed for LEP. A high gradient is an obvious design aim for any future high energy linear collider because it makes it shorter and therefore cheaper - the design figure for the CLIC machine is 80 MV/m. The CLIC study group has taken a significant step forward in demonstrating the technical feasibility of their machine by achieving peak and average accelerating gradients of 137 MV/m and 84 MV/m respectively in a short section of accelerating structure during high gradient tests at the Japanese KEK Laboratory last year. This result obtained within the framework of a CERN/KEK collaboration on linear colliders was obtained using a 20-cell accelerating section built at CERN using state-of the- art technology which served both as a model for CLIC studies as well as a prototype for the Japanese Linear Collider studies. The operating frequency of the model accelerating section is 2.6 times lower than the CLIC frequency but was chosen because a high power r.f. source and pulse compression scheme has been developed for this frequency at KEK. Testing CLIC models at 11.4 GHz is however more stringent than at 30 GHz because the chance of electrical breakdown increases as the frequency is lowered. This recent result clearly demonstrates that a gradient of 80 MV/m is feasible

  17. Evolution of a Planar Wake in Adverse Pressure Gradient

    Science.gov (United States)

    Driver, David M.; Mateer, George G.

    2016-01-01

    In the interest of improving the predictability of high-lift systems at maximum lift conditions, a series of fundamental experiments were conducted to study the effects of adverse pressure gradient on a wake flow. Mean and fluctuating velocities were measured with a two-component laser-Doppler velocimeter. Data were obtained for several cases of adverse pressure gradient, producing flows ranging from no reversed flow to massively reversed flow. While the turbulent Reynolds stresses increase with increasing size of the reversed flow region, the gradient of Reynolds stress does not. Computations using various turbulence models were unable to reproduce the reversed flow.

  18. Laser hybrid brazing of oxide ceramics for high temperature gas sensing applications in (V)HTRS

    Energy Technology Data Exchange (ETDEWEB)

    Heilmann, F. [Robert Bosch GmbH, Stuttgart (Germany). Corporate Research and Advance Engineering; Technische Univ. Dresden (Germany). Chair of Hydrogen- and Nuclear Engineering; Rixecker, G. [Robert Bosch GmbH, Stuttgart (Germany). Corporate Research and Advance Engineering; Boerner, F.D.; Lippmann, W.; Hurtado, A. [Technische Univ. Dresden (Germany). Chair of Hydrogen- and Nuclear Engineering

    2009-07-01

    It has been shown that the use of halogen lamps to assist laser brazing reduces total energy and joining time. For parts with specific geometries not suitable for a rotation process, an assistive heating with halogen lamps might be even more beneficial, to alleviate temperature gradients and transients. Forsterite-based ceramics are highly suitable as a joining partner for ZrO{sub 2}, especially in a laser brazing process based on volume heating. By adding Fe{sub 2}O{sub 3} to the raw powder mixture, the absorptivity of the forsterite ceramic can be tuned with an optimum at 0.1 wt.% Fe, reducing the necessary laser energy input even more. (orig.)

  19. Advances in high-gradient magnetic fishing for bioprocessing

    DEFF Research Database (Denmark)

    Goncalves Gomes, Claudia Sofia

    2006-01-01

    High-gradient magnetic fishing” (HGMF) er en metode til processering af fødestrømme med biologiske molekyler. HGMF integrerer brugen af superparamagnetiske adsorbenter med separation og processering med høj-gradient magnetisk separation (HGMS) i et magnetisk filter. Adsorbenterne er uporøse og...

  20. High energy HF pulsed lasers

    International Nuclear Information System (INIS)

    Patterson, E.L.; Gerber, R.A.

    1976-01-01

    Recent experiments show that pulsed HF lasers are capable of producing high energy with good efficiency. Preliminary experiments show that the laser radiation from the high-gain medium can be controlled with a low-power probe laser beam or with low-level feedback. These results indicate that the HF laser may have potential for second-generation laser fusion experiments

  1. The quest for high-gradient superconducting cavities

    International Nuclear Information System (INIS)

    Padamsee, H.

    1999-01-01

    Superconducting RF cavities excel in applications requiring continuous waves or long pulse voltages. Since power losses in the walls of the cavity increase as the square of the accelerating voltage, copper cavities become uneconomical as demand for high continuous wave voltage grows with particle energy. For these reasons, RF superconductivity has become an important technology for high energy and high luminosity accelerators. The state of art in performance of sheet metal niobium cavities is best represented by the statistics of more than 300 5-cell, 1.5-GHz cavities built for CEBAF. Key aspects responsible for the outstanding performance of the CEBAF cavities set are the anti-multipactor, elliptical cell shape, good fabrication and welding techniques, high thermal conductivity niobium, and clean surface preparation. On average, field emission starts at the electric field of 8.7 MV/m, but there is a large spread, even though the cavities received nominally the same surface treatment and assembly procedures. In some cavities, field emission was detected as low as 3 MV/m. In others, it was found to be as high as 19 MV/m. As we will discuss, the reason for the large spread in the gradients is the large spread in emitter characteristics and the random occurrence of emitters on the surface. One important phenomenon that limits the achievable RF magnetic field is thermal breakdown of superconductivity, originating at sub-millimeter-size regions of high RF loss, called defects. Simulation reveal that if the defect is a normal conducting region of 200 mm radius, it will break down at 5 MV/m. Producing high gradients and high Q in superconducting cavities demands excellent control of material properties and surface cleanliness. The spread in gradients that arises from the random occurrence of defects and emitters must be reduced. It will be important to improve installation procedures to preserve the excellent gradients now obtained in laboratory test in vertical cryostats

  2. Gradient High Performance Liquid Chromatography Method ...

    African Journals Online (AJOL)

    Purpose: To develop a gradient high performance liquid chromatography (HPLC) method for the simultaneous determination of phenylephrine (PHE) and ibuprofen (IBU) in solid ..... nimesulide, phenylephrine. Hydrochloride, chlorpheniramine maleate and caffeine anhydrous in pharmaceutical dosage form. Acta Pol.

  3. Avoiding vacuum arcs in high gradient normal conducting RF structures

    CERN Document Server

    Sjøbæk, Kyrre Ness; Adli, Erik; Grudiev, Alexej; Wuensch, Walter

    In order to build the Compact LInear Collider (CLIC), accelerating structures reaching extremely high accelerating gradients are needed. Such structures have been built and tested using normal-conducting copper, powered by X-band RF power and reaching gradients of 100 MV/m and above. One phenomenon that must be avoided in order to reliably reach such gradients, is vacuum arcs or “breakdowns”. This can be accomplished by carefully designing the structure geometry such that high surface fields and large local power flows are avoided. The research presented in this thesis presents a method for optimizing the geometry of accelerating structures so that these breakdowns are made less likely, allowing the structure to operate reliably at high gradients. This was done primarily based on a phenomenological scaling model, which predicted the maximum gradient as a function of the break down rate, pulse length, and field distribution in the structure. The model is written in such a way that it allows direct comparis...

  4. HIGH-GRADIENT, HIGH-TRANSFORMER-RATIO, DIELECTRIC WAKE FIELD ACCELERATOR

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L

    2012-04-12

    The Phase I work reported here responds to DoE'ss stated need "...to develop improved accelerator designs that can provide very high gradient (>200 MV/m for electrons...) acceleration of intense bunches of particles." Omega-P's approach to this goal is through use of a ramped train of annular electron bunches to drive a coaxial dielectric wakefield accelerator (CDWA) structure. This approach is a direct extension of the CDWA concept from acceleration in wake fields caused by a single drive bunch, to the more efficient acceleration that we predict can be realized from a tailored (or ramped) train of several drive bunches. This is possible because of a much higher transformer ratio for the latter. The CDWA structure itself has a number of unique features, including: a high accelerating gradient G, potentially with G > 1 GeV/m; continuous energy coupling from drive to test bunches without transfer structures; inherent transverse focusing forces for particles in the accelerated bunch; highly stable motion of high charge annular drive bunches; acceptable alignment tolerances for a multi-section system. What is new in the present approach is that the coaxial dielectric structure is now to be energized by-not one-but by a short train of ramped annular-shaped drive bunches moving in the outer coaxial channel of the structure. We have shown that this allows acceleration of an electron bunch traveling along the axis in the inner channel with a markedly higher transformer ratio T than for a single drive bunch. As described in this report, the structure will be a GHz-scale prototype with cm-scale transverse dimensions that is expected to confirm principles that can be applied to the design of a future THz-scale high gradient (> 500 MV/m) accelerator with mm-scale transverse dimensions. We show here a new means to significantly increase the transformer ratio T of the device, and thereby to significantly improve its suitability as a flexible and effective component in

  5. Progress in high-energy laser technology

    International Nuclear Information System (INIS)

    Miyanaga, Noriaki; Kitagawa, Yoneyoshi; Nakatsuka, Masahiro; Kanabe, Tadashi; Okuda, Isao

    2005-01-01

    The technological development of high-energy lasers is one of the key issues in laser fusion research. This paper reviews several technologies on the Nd:glass laser and KrF excimer laser that are being used in the current laser fusion experiments and related plasma experiments. Based on the GEKKO laser technology, a new high-energy Nd: glass laser system, which can deliver energy from 10 kJ (boad-band operation) to 20 kJ (narrow-band operation), is under construction. The key topics in KrF laser development are improved efficiency and repetitive operation, which aim at the development of a laser driven for fusion reactor. Ultra-intense-laser technology is also very important for fast ignition research. The key technology for obtaining the petawatt output with high beam quality is reviewed. Regarding the uniform laser irradiation required for high-density compression, the beam-smoothing methods on the GEKKO XII laser are reviewed. Finally, we discuss the present status of MJ-class lasers throughout the world, and summarize by presenting the feasibility of various applications of the high-energy lasers to a wide range of scientific and technological fields. (author)

  6. Dielectric-Lined High-Gradient Accelerator Structure

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2012-04-24

    Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS

  7. Dielectric-Lined High-Gradient Accelerator Structure

    International Nuclear Information System (INIS)

    Hirshfield, Jay L.

    2012-01-01

    Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field (∼2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 (micro)s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10 5 RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30

  8. New technology based on clamping for high gradient radio frequency photogun

    Science.gov (United States)

    Alesini, David; Battisti, Antonio; Ferrario, Massimo; Foggetta, Luca; Lollo, Valerio; Ficcadenti, Luca; Pettinacci, Valerio; Custodio, Sean; Pirez, Eylene; Musumeci, Pietro; Palumbo, Luigi

    2015-09-01

    High gradient rf photoguns have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the present paper we present the design of a new rf photogun recently developed in the framework of the SPARC_LAB photoinjector activities at the laboratories of the National Institute of Nuclear Physics in Frascati (LNF-INFN, Italy). This design implements several new features from the electromagnetic point of view and, more important, a novel technology for its realization that does not involve any brazing process. From the electromagnetic point of view the gun presents high mode separation, low peak surface electric field at the iris and minimized pulsed heating on the coupler. For the realization, we have implemented a novel fabrication design that, avoiding brazing, strongly reduces the cost, the realization time and the risk of failure. Details on the electromagnetic design, low power rf measurements and high power radiofrequency and beam tests performed at the University of California in Los Angeles (UCLA) are discussed in the paper.

  9. High gradient RF breakdown study

    International Nuclear Information System (INIS)

    Laurent, L.; Luhmann, N.C. Jr.; Scheitrum, G.; Hanna, S.; Pearson, C.; Phillips, R.

    1998-01-01

    Stanford Linear Accelerator Center and UC Davis have been investigating high gradient RF breakdown and its effects on pulse shortening in high energy microwave devices. RF breakdown is a critical issue in the development of high power microwave sources and next generation linear accelerators since it limits the output power of microwave sources and the accelerating gradient of linacs. The motivation of this research is to find methods to increase the breakdown threshold level in X-band structures by reducing dark current. Emphasis is focused on improved materials, surface finish, and cleanliness. The test platform for this research is a traveling wave resonant ring. A 30 MW klystron is employed to provide up to 300 MW of traveling wave power in the ring to trigger breakdown in the cavity. Five TM 01 cavities have previously been tested, each with a different combination of surface polish and/or coating. The onset of breakdown was extended up to 250 MV/m with a TiN surface finish, as compared to 210 MV/m for uncoated OFE copper. Although the TiN coating was helpful in depressing the field emission, the lowest dark current was obtained with a 1 microinch surface finish, single-point diamond-turned cavity

  10. Laser - driven high - energy ions and their application to inertial confinement fusion

    International Nuclear Information System (INIS)

    Borghesi, M.

    2007-01-01

    The acceleration of high-energy ion beams (up to several tens of MeV per nucleon) following the interaction of short and intense laser pulses with solid targets has been one of the most important results of recent laser-plasma research [1]. The acceleration is driven by relativistic electrons, which acquire energy directly from the laser pulse and set up extremely large (∼TV/m) space charge fields at the target interfaces. The properties of laser-driven ion beams (high brightness and laminarity, high-energy cut-off, ultrashort burst duration) distinguish them from lower energy ions accelerated in earlier experiments at moderate laser intensities, and compare favourably with those of 'conventional' accelerator beams. In view of these properties, laser-driven ion beams can be employed in a number of innovative applications in the scientific, technological and medical areas. We will discuss in particular aspects of interest to their application in an Inertial Confinement Fusion context. Laser-driven protons are indeed being considered as a possible trigger for Fast Ignition of a precompressed fuel.[2] Recent results relating to the optimization of beam energy and focusing will be presented. These include the use of laser-driven impulsive fields for proton beam collimation and focusing [3], and the investigation of acceleration in presence of finite-scale plasma gradient. Proposed target developments enabling proton production at high repetition rate will also be discussed. Another important area of application of proton beams is diagnostic use in a particle probing arrangement for detection of density non-homogeneities [4] and electric/magnetic fields [5]. We will discuss the use of laser-driven proton beams for the diagnosis of magnetic and electric fields in planar and hohlraum targets and for the detection of fields associated to relativistic electron propagation through dense matter, an issue of high relevance for electron driven Fast Ignition. [1] M

  11. Dynamics and structure of self-generated magnetics fields on solids following high contrast, high intensity laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Albertazzi, B. [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); INRS-EMT, 1650 bd L. Boulet, J3X1S2, Varennes, Québec (Canada); Graduate School of Engineering, University of Osaka, Suita, Osaka 565-087 (Japan); Chen, S. N.; Fuchs, J., E-mail: julien.fuchs@polytechnique.fr [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation); Antici, P. [INRS-EMT, 1650 bd L. Boulet, J3X1S2, Varennes, Québec (Canada); Dept. SBAI, Universita di Roma “La Sapienza,” Via A. Scarpa 14, 00161 Rome (Italy); Böker, J.; Swantusch, M.; Willi, O. [Institut für Laser-und Plasmaphysik, Heinrich-Heine-Universität, Düsseldorf (Germany); Borghesi, M. [School of Mathematics and Physics, The Queen' s University, Belfast (United Kingdom); Breil, J.; Feugeas, J. L.; Nicolaï, Ph.; Tikhonchuk, V. T.; D' Humières, E. [CELIA, University of Bordeaux - CNRS - CEA, 33405 Talence (France); Dervieux, V.; Nakatsutsumi, M.; Romagnagni, L. [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Lancia, L. [Dept. SBAI, Universita di Roma “La Sapienza,” Via A. Scarpa 14, 00161 Rome (Italy); Shepherd, R. [LLNL, East Av., Livermore, California 94550 (United States); Sentoku, Y. [Department of Physics, University of Nevada, Reno, Nevada 89557-0058 (United States); Starodubtsev, M. [Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation); and others

    2015-12-15

    The dynamics of self-generated magnetic B-fields produced following the interaction of a high contrast, high intensity (I > 10{sup 19 }W cm{sup −2}) laser beam with thin (3 μm thick) solid (Al or Au) targets is investigated experimentally and numerically. Two main sources drive the growth of B-fields on the target surfaces. B-fields are first driven by laser-generated hot electron currents that relax over ∼10–20 ps. Over longer timescales, the hydrodynamic expansion of the bulk of the target into vacuum also generates B-field induced by non-collinear gradients of density and temperature. The laser irradiation of the target front side strongly localizes the energy deposition at the target front, in contrast to the target rear side, which is heated by fast electrons over a much larger area. This induces an asymmetry in the hydrodynamic expansion between the front and rear target surfaces, and consequently the associated B-fields are found strongly asymmetric. The sole long-lasting (>30 ps) B-fields are the ones growing on the target front surface, where they remain of extremely high strength (∼8–10 MG). These B-fields have been recently put by us in practical use for focusing laser-accelerated protons [B. Albertazzi et al., Rev. Sci. Instrum. 86, 043502 (2015)]; here we analyze in detail their dynamics and structure.

  12. Prototyping high-gradient mm-wave accelerating structures

    International Nuclear Information System (INIS)

    Nanni, Emilio A.; Dolgashev, Valery A.; Haase, Andrew; Neilson, Jeffrey; Tantawi, Sami

    2017-01-01

    We present single-cell accelerating structures designed for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics of ultrahigh vacuum RF breakdown in high-gradient RF accelerators. The accelerating structures are π-mode standing-wave cavities fed with a TM 01 circular waveguide. The structures are fabricated using precision milling out of two metal blocks, and the blocks are joined with diffusion bonding and brazing. The impact of fabrication and joining techniques on the cell geometry and RF performance will be discussed. First prototypes had a measured Q 0 of 2800, approaching the theoretical design value of 3300. The geometry of these accelerating structures are as close as practical to singlecell standing-wave X-band accelerating structures more than 40 of which were tested at SLAC. This wealth of X-band data will serve as a baseline for these 110 GHz tests. Furthermore, the structures will be powered with short pulses from a MW gyrotron oscillator. RF power of 1 MW may allow an accelerating gradient of 400 MeV/m to be reached.

  13. Heavy Metal Diffusion through Soft Clay under High Hydraulic Gradients

    Directory of Open Access Journals (Sweden)

    Zaheer Ahmed Almani

    2013-04-01

    Full Text Available This study was focused on the determination of contaminant transport parameters of heavy metal Zinc moving through saturated soft Bangkok undisturbed clay under high hydraulic gradients. These parameters were compared with contaminant transport determined under concentration gradient alone (pure diffusion. In total fifteen column tests were conducted and a mathematical model was applied to determine the coefficients. Two different source concentrations conditions, constant and decreasing, were applied. Testing periods were ranged from 15-60 days while hydraulic gradients were ranged from 0-500. The curves between relative concentration and time and pore volume were developed for the constant source condition whereas curves between source reservoirs concentrations and time were developed for decreasing source condition. The effective diffusion and distribution coefficients, De and Kd, were determined by curve fitting using the computer code POLLUTE v 6.3. The results showed that diffusion coefficient increases and distribution coefficient decreases as hydraulic gradient increases from 0 to high value of 500 due to contribution of dispersion and additional molecular diffusion at high advective velocity. Thus, testing at high gradients ensures the safe performance of earthen barriers under worse conditions.

  14. Cemented carbide cutting tool: Laser processing and thermal stress analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S. [Mechanical Engineering Department, KFUPM, Box 1913, Dhahran 31261 (Saudi Arabia)]. E-mail: bsyilbas@kfupm.edu.sa; Arif, A.F.M. [Mechanical Engineering Department, KFUPM, Box 1913, Dhahran 31261 (Saudi Arabia); Karatas, C. [Engineering Faculty, Hacettepe University, Ankara (Turkey); Ahsan, M. [Mechanical Engineering Department, KFUPM, Box 1913, Dhahran 31261 (Saudi Arabia)

    2007-04-15

    Laser treatment of cemented carbide tool surface consisting of W, C, TiC, TaC is examined and thermal stress developed due to temperature gradients in the laser treated region is predicted numerically. Temperature rise in the substrate material is computed numerically using the Fourier heating model. Experiment is carried out to treat the tool surfaces using a CO{sub 2} laser while SEM, XRD and EDS are carried out for morphological and structural characterization of the treated surface. Laser parameters were selected include the laser output power, duty cycle, assisting gas pressure, scanning speed, and nominal focus setting of the focusing lens. It is found that temperature gradient attains significantly high values below the surface particularly for titanium and tantalum carbides, which in turn, results in high thermal stress generation in this region. SEM examination of laser treated surface and its cross section reveals that crack initiation below the surface occurs and crack extends over the depth of the laser treated region.

  15. High-power pulsed lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.

    1980-01-01

    The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization

  16. High speed micromachining with high power UV laser

    Science.gov (United States)

    Patel, Rajesh S.; Bovatsek, James M.

    2013-03-01

    Increasing demand for creating fine features with high accuracy in manufacturing of electronic mobile devices has fueled growth for lasers in manufacturing. High power, high repetition rate ultraviolet (UV) lasers provide an opportunity to implement a cost effective high quality, high throughput micromachining process in a 24/7 manufacturing environment. The energy available per pulse and the pulse repetition frequency (PRF) of diode pumped solid state (DPSS) nanosecond UV lasers have increased steadily over the years. Efficient use of the available energy from a laser is important to generate accurate fine features at a high speed with high quality. To achieve maximum material removal and minimal thermal damage for any laser micromachining application, use of the optimal process parameters including energy density or fluence (J/cm2), pulse width, and repetition rate is important. In this study we present a new high power, high PRF QuasarR 355-40 laser from Spectra-Physics with TimeShiftTM technology for unique software adjustable pulse width, pulse splitting, and pulse shaping capabilities. The benefits of these features for micromachining include improved throughput and quality. Specific example and results of silicon scribing are described to demonstrate the processing benefits of the Quasar's available power, PRF, and TimeShift technology.

  17. Laser technologies for laser accelerators. Annual report

    International Nuclear Information System (INIS)

    1985-01-01

    The primary result of the work reported is the determination of laser system architectures that satsify the requirements of high luminosity, high energy (about 1 TeV), electron accelerators. It has been found that high laser efficiency is a very hard driver for these accelerators as the total average laser output optical power is likely to fall above 10 MW. The luminosity requires rep rates in the kHz range, and individual pulse lengths in the 1-10 psec range are required to satisfy acceleration gradient goals. CO 2 and KrF lasers were chosen for study because of their potential to simultaneously satisfy the given requirements. Accelerator luminosity is reviewed, and requirements on laser system average power and rep rate are determined as a function of electron beam bunch parameters. Laser technologies are reviewed, including CO 2 , excimers, solid state, and free electron lasers. The proposed accelerator mechanisms are summarized briefly. Work on optical transport geometries for near and far field accelerators are presented. Possible exploitation of the CO 2 and DrF laser technology to generate the required pulse lengths, rep rates, and projected efficiencies is illustrated and needed development work is suggested. Initial efforts at developing a 50 GeV benchmark conceptual design and a 100 MeV demonstration experiment conceptual design are presented

  18. Effect of Y2O3 Content on Microstructure of Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    Liu Qibin; Zou Jianglong; Zheng Min; Dong Chuang

    2005-01-01

    To eliminate thermal stress and cracks in the process of laser cladding, a kind of bioceramic coating with gradient compositional design was prepared on the surface of Ti alloy by using wide-band laser cladding. And effect of Y2O3 content on gradient bioceramic composite coating was studied. The experimental results indicate that adding rare earth can refine grain. Different rare earth contents affect formation of HA and β-TCP in bioceramic coating. When the content of rare earth ranges from 0.4% to 0.6%, the active extent of rare earth in synthesizing HA and β-TCP is the best, which indicates that "monosodium glutamate" effect of rare earth plays a dominant role. However, when rare earth content is up to 0.8%, the amount of synthesizing HA and β-TCP in coating conversely goes down, which demonstrates that rare earth gradually losts its catalysis in manufacturing HA and β-TCP.

  19. Relativistic klystron research for high gradient accelerators

    International Nuclear Information System (INIS)

    Allen, M.A.; Callin, R.S.; Deruyter, H.

    1988-06-01

    Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron--positron colliders, compact accelerators, and FEL sources. We have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 7 figs

  20. Highly-efficient mid-infrared CW laser operation in a lightly-doped 3 at.% Er:SrF2 single crystal.

    Science.gov (United States)

    Su, Liangbi; Guo, Xinsheng; Jiang, Dapeng; Wu, Qinghui; Qin, Zhipeng; Xie, Guoqiang

    2018-03-05

    3 at.% Er:SrF 2 laser crystals with high optical quality were successfully grown using the temperature gradient technique (TGT). The intense mid-infrared emission was observed around 2.7 μm with excitation by a 970 nm LD. Based on the Judd-Ofelt theory, the emission cross-sections of the 4 I 13/2 - 4 I 11/2 transition were calculated by using the Fuchtbauer-Ladenburg (FL) method. Efficient continuous-wave laser operation at 2.8 µm was achieved with the lightly-doped 3 at.% Er:SrF 2 crystal pumped by a 970 nm laser diode. The laser output power reached up to 1.06 W with a maximum slope efficiency of 26%.

  1. Laser-Doppler acoustic probing of granular media with in-depth property gradient and varying pore pressures

    International Nuclear Information System (INIS)

    Bodet, L.; Dhemaied, A.; Mourgues, R.; Tournat, V.; Rejiba, F.

    2012-01-01

    Non-contacting ultrasonic techniques recently proved to be efficient in the physical modeling of seismic-wave propagation at various application scales, as for instance in the context of geological analogue and seismic modeling. An innovative experimental set-up is proposed here to perform laser-Doppler acoustic probing of unconsolidated granular media with varying pore pressures. The preliminary experiments presented here provide reproducible results and exploitable data, thus validating both the proposed medium preparation and pressure gradient generation procedure.

  2. High resolution laser micro sintering / melting using q-switched and high brilliant laser radiation

    Science.gov (United States)

    Exner, H.; Streek, A.

    2015-03-01

    Since the discovery of selective laser sintering/melting, numerous modifications have been made to upgrade or customize this technology for industrial purposes. Laser micro sintering (LMS) is one of those modifications: Powders with particles in the range of a few micrometers are used to obtain products with highly resolved structures. Pulses of a q-switched laser had been considered necessary in order to generate sinter layers from the micrometer scaled metal powders. LMS has been applied with powders from metals as well as from ceramic and cermet feedstock's to generate micro parts. Recent technological progress and the application of high brilliant continuous laser radiation have now allowed an efficient laser sintering/melting of micrometer scaled metal powders. Thereby it is remarkable that thin sinter layers are generated using high continuous laser power. The principles of the process, the state of the art in LMS concerning its advantages and limitations and furthermore the latest results of the recent development of this technology will be presented. Laser Micro Sintering / Laser Micro Melting (LMM) offer a vision for a new dimension of additive fabrication of miniature and precise parts also with application potential in all engineering fields.

  3. Design features of a seven-cell high-gradient superconducting cavity

    International Nuclear Information System (INIS)

    Liska, D.J.; Ledford, J.; Black, S.; Spalek, G.; DiMarco, J.N.

    1992-01-01

    A cavity development program is in place at Los Alamos National Laboratory to evaluate structures that could be used to accelerate pions. The work is being guided by the conceptual design of PILAC, a high-gradient superconducting linac for raising the energy of rapidly decaying intense pion beams generated by Los Alamos Meson Physics Facility (LAMPF) to 1 GeV. The specification requires a cavity gradient of 12.5 MV/m at 805 MHz. The design of a seven-cell prototype cavity to achieve these high gradients has been completed by the Accelerator Technology division. The cavity is presently under procurement for high power testing a 2.0 K in 1993

  4. CO2 laser technology for advanced particle accelerators

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.

    1996-06-01

    Short-pulse, high-power CO 2 lasers open new prospects for development of ultra-high gradient laser-driven electron accelerators. The advantages of λ=10 μm CO 2 laser radiation over the more widely exploited solid state lasers with λ∼1 μm are based on a λ 2 -proportional ponderomotive potential, λ-proportional phase slippage, and λ-proportional scaling of the laser accelerator structures. We show how a picosecond terawatt CO 2 laser that is under construction at the Brookhaven Accelerator Test Facility may benefit the ATF's experimental program of testing far-field, near-field, and plasma accelerator schemes

  5. High-intensity laser physics

    International Nuclear Information System (INIS)

    Mohideen, U.

    1993-01-01

    This thesis is a study of the effect of high intensity lasers on atoms, free electrons and the generation of X-rays from solid density plasmas. The laser produced 50 milli Joule 180 femto sec pulses at 5 Hz. This translates to a maximum intensity of 5 x 10 18 W/cm 2 . At such high fields the AC stark shifts of atoms placed at the focus is much greater than the ionization energy. The characteristics of multiphoton ionization of atoms in intense laser fields was studied by angle resolved photoelectron spectroscopy. Free electrons placed in high intensity laser fields lead to harmonic generation. This phenomenon of Nonlinear Compton Scattering was theoretically investigated. Also, when these high intensity pulses are focused on solids a hot plasma is created. This plasma is a bright source of a short X-ray pulse. The pulse-width of X-rays from these solid density plasmas was measured by time-resolved X-ray spectroscopy

  6. Methods for slow axis beam quality improvement of high power broad area diode lasers

    Science.gov (United States)

    An, Haiyan; Xiong, Yihan; Jiang, Ching-Long J.; Schmidt, Berthold; Treusch, Georg

    2014-03-01

    For high brightness direct diode laser systems, it is of fundamental importance to improve the slow axis beam quality of the incorporated laser diodes regardless what beam combining technology is applied. To further advance our products in terms of increased brightness at a high power level, we must optimize the slow axis beam quality despite the far field blooming at high current levels. The later is caused predominantly by the built-in index step in combination with the thermal lens effect. Most of the methods for beam quality improvements reported in publications sacrifice the device efficiency and reliable output power. In order to improve the beam quality as well as maintain the efficiency and reliable output power, we investigated methods of influencing local heat generation to reduce the thermal gradient across the slow axis direction, optimizing the built-in index step and discriminating high order modes. Based on our findings, we have combined different methods in our new device design. Subsequently, the beam parameter product (BPP) of a 10% fill factor bar has improved by approximately 30% at 7 W/emitter without efficiency penalty. This technology has enabled fiber coupled high brightness multi-kilowatt direct diode laser systems. In this paper, we will elaborate on the methods used as well as the results achieved.

  7. The high-power iodine laser

    Science.gov (United States)

    Brederlow, G.; Fill, E.; Witte, K. J.

    The book provides a description of the present state of the art concerning the iodine laser, giving particular attention to the design and operation of pulsed high-power iodine lasers. The basic features of the laser are examined, taking into account aspects of spontaneous emission lifetime, hyperfine structure, line broadening and line shifts, stimulated emission cross sections, the influence of magnetic fields, sublevel relaxation, the photodissociation of alkyl iodides, flashlamp technology, excitation in a direct discharge, chemical excitation, and questions regarding the chemical kinetics of the photodissociation iodine laser. The principles of high-power operation are considered along with aspects of beam quality and losses, the design and layout of an iodine laser system, the scalability and prospects of the iodine laser, and the design of the single-beam Asterix III laser.

  8. Laser wakefield electron acceleration. A novel approach employing supersonic microjets and few-cycle laser pulses

    International Nuclear Information System (INIS)

    Schmid, Karl

    2011-01-01

    This thesis covers the few-cycle laser-driven acceleration of electrons in a laser-generated plasma. This process, known as laser wakefield acceleration (LWFA), relies on strongly driven plasma waves for the generation of accelerating gradients in the vicinity of several 100 GV/m, a value four orders of magnitude larger than that attainable by conventional accelerators. This thesis demonstrates that laser pulses with an ultrashort duration of 8 fs and a peak power of 6 TW allow the production of electron energies up to 50 MeV via LWFA. The special properties of laser accelerated electron pulses, namely the ultrashort pulse duration, the high brilliance, and the high charge density, open up new possibilities in many applications of these electron beams. (orig.)

  9. Laser safety at high profile laser facilities

    International Nuclear Information System (INIS)

    Barat, K.

    2010-01-01

    Complete text of publication follows. Laser safety has been an active concern of laser users since the invention of the laser. Formal standards were developed in the early 1970's and still continue to be developed and refined. The goal of these standards is to give users guidance on the use of laser and consistent safety guidance and requirements for laser manufacturers. Laser safety in the typical research setting (government laboratory or university) is the greatest challenge to the laser user and laser safety officer. This is due to two factors. First, the very nature of research can put the user at risk; consider active manipulation of laser optics and beam paths, and user work with energized systems. Second, a laser safety culture that seems to accept laser injuries as part of the graduate student educational process. The fact is, laser safety at research settings, laboratories and universities still has long way to go. Major laser facilities have taken a more rigid and serious view of laser safety, its controls and procedures. Part of the rationale for this is that these facilities draw users from all around the world presenting the facility with a work force of users coming from a wide mix of laser safety cultures. Another factor is funding sources do not like bad publicity which can come from laser accidents and a poor safety record. The fact is that injuries, equipment damage and lost staff time slow down progress. Hence high profile/large laser projects need to adapt a higher safety regimen both from an engineering and administrative point of view. This presentation will discuss all these points and present examples. Acknowledgement. This work has been supported by the University of California, Director, Office of Science.

  10. X-ray spectroscopy of a thin foil plasma produced by a short-pulse high-intensity laser

    International Nuclear Information System (INIS)

    Audebert, P.; Nagels, V.; Geindre, J.P.; Dorchies, F.; Peyrusse, O.; Gary, S.; Girard, F.; Shepherd, R.; Gauthier, J.C.; Chenais-Popovics, C.

    2003-01-01

    High density and temperature plasmas have been generated by irradiating thin foils of various elements with a high-energy subpicosecond laser pulse. The X-ray emission duration was studied by time-resolved X-ray spectroscopy. Frequency domain interferometry provided a measurement of the hydrodynamic expansion of the back of the foil as a function of time. The effect of longitudinal temperature gradients, i.e., gradients perpendicular to the surface, were decreased using very thin foil targets. Additionally, radial gradients effects, i.e., gradients parallel to the surface, were limited by using a 50 μm pinhole on target. The Al, Se and Sm spectra, recorded in the range 7.7-8 Angst. using a conical crystal spectrometer coupled to an 800 fs resolution streak camera, lasted a few picoseconds. Sm spectra showed no spectral features in this wavelength range, providing a spectrally homogeneous backlighter for future experiments. The main features of the experimental time-resolved spectra have been well reproduced with one-dimensional hydrodynamic simulations of the free expansion of a plasma heated at a given initial temperature obtained from the expansion velocity of the rear critical surface of the plasma

  11. Orsay: High-gradient experiment

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    Maintaining the tradition of its contribution to the LEP Injector Linac (LIL), Orsay's Linear Accelerator Laboratory (LAL) is carrying out an R&D programme entitled 'New accelerator physics experiments at LAL' (NEPAL). The aim is to contribute to the long-term development of high energy electron-positron linear colliders, where progress can be of short-term benefit both to conventional accelerators and to injectors in rings or free-electron lasers

  12. Experimental and theoretical investigation of high gradient acceleration

    International Nuclear Information System (INIS)

    Wurtele, J.S.; Bekefi, G.; Chen, C.; Chen, S.C.; Temkin, R.J.

    1993-01-01

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, ''Experimental and Theoretical Investigations of High Gradient Acceleration''. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders

  13. CO2 laser technology for advanced particle accelerators. Revision

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.

    1996-06-01

    Short-pulse, high-power CO 2 lasers open new prospects for development of ultra-high gradient laser-driven electron accelerators. The advantages of λ=10 μm CO 2 laser radiation over the more widely exploited solid state lasers with λ∼1 μm are based on a λ 2 -proportional ponderomotive potential, λ-proportional phase slippage distance, and λ-proportional scaling of the laser accelerator structures. We show how a picosecond terawatt CO 2 laser that is under construction at the Brookhaven Accelerator Test Facility may benefit the ATF's experimental program of testing far-field, near-field, and plasma accelerator schemes

  14. Optics assembly for high power laser tools

    Science.gov (United States)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  15. High-energy molecular lasers self-controlled volume-discharge lasers and applications

    CERN Document Server

    Apollonov, V V

    2016-01-01

    This book displays the physics and design of high-power molecular lasers. The lasers described are self-controlled volume-discharge lasers. The book explains self-sustained discharge lasers, self-initiated discharge lasers and technical approaches to laser design. Important topics discussed are laser efficiency, laser beam quality and electric field homogeneity. The book contains many new innovative applications.

  16. Prospects of target nanostructuring for laser proton acceleration

    Science.gov (United States)

    Lübcke, Andrea; Andreev, Alexander A.; Höhm, Sandra; Grunwald, Ruediger; Ehrentraut, Lutz; Schnürer, Matthias

    2017-03-01

    In laser-based proton acceleration, nanostructured targets hold the promise to allow for significantly boosted proton energies due to strong increase of laser absorption. We used laser-induced periodic surface structures generated in-situ as a very fast and economic way to produce nanostructured targets capable of high-repetition rate applications. Both in experiment and theory, we investigate the impact of nanostructuring on the proton spectrum for different laser-plasma conditions. Our experimental data show that the nanostructures lead to a significant enhancement of absorption over the entire range of laser plasma conditions investigated. At conditions that do not allow for efficient laser absorption by plane targets, i.e. too steep plasma gradients, nanostructuring is found to significantly enhance the proton cutoff energy and conversion efficiency. In contrast, if the plasma gradient is optimized for laser absorption of the plane target, the nanostructure-induced absorption increase is not reflected in higher cutoff energies. Both, simulation and experiment point towards the energy transfer from the laser to the hot electrons as bottleneck.

  17. Preprocessing of gravity gradients at the GOCE high-level processing facility

    Science.gov (United States)

    Bouman, Johannes; Rispens, Sietse; Gruber, Thomas; Koop, Radboud; Schrama, Ernst; Visser, Pieter; Tscherning, Carl Christian; Veicherts, Martin

    2009-07-01

    One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in Earth scienes and gravity field analysis, additional preprocessing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and nontidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/ f behaviour for low frequencies. In the outlier detection, the 1/ f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/ f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low-degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10-3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10-2 level with this

  18. The utilization of high-intensity lasers

    International Nuclear Information System (INIS)

    Fabre, E.

    1988-01-01

    The 1988 progress report of the laboratory for the Utilization of High-Intensity Lasers (Polytechnic School, France), is presented. The research program is focused on the laser-plasma physics, on the generation of high pressures by means of laser shock heating, on the laser spectroscopy and on the laser implosions. Numerical simulation codes are developed. Concerning the atomic physics, the investigations on dense plasmas and the x-laser research developments are carried out. The research activities of the laboratory teams, the published papers, the national and international cooperations, are given [fr

  19. High Power High Efficiency Diode Laser Stack for Processing

    Science.gov (United States)

    Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan

    2018-03-01

    High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.

  20. High Power Vanadate lasers

    CSIR Research Space (South Africa)

    Strauss

    2006-07-01

    Full Text Available stream_source_info Strauss1_2006.pdf.txt stream_content_type text/plain stream_size 3151 Content-Encoding UTF-8 stream_name Strauss1_2006.pdf.txt Content-Type text/plain; charset=UTF-8 Laser Research Institute... University of Stellenbosch www.laser-research.co.za High Power Vanadate lasers H.J.Strauss, Dr. C. Bollig, R.C. Botha, Prof. H.M. von Bergmann, Dr. J.P. Burger Aims 1) To develop new techniques to mount laser crystals, 2) compare the lasing properties...

  1. Theoretical interpretation of high-Z discs irradiated with 1.06 μ laser light

    International Nuclear Information System (INIS)

    Rosen, M.D.; Mead, W.C.; Thomson, J.J.; Kruer, W.L.

    1978-01-01

    High Z discs have been irradiated with 1.06 μ laser light at intensities between 7 x 10 13 and 3 x 10 15 W/cm, and pulse lengths between 200 and 1000 ps. Due to the high Z, inverse bremsstrahlung becomes an important absorption effect and competes strongly with resonance absorption and stimulated scattering. We find that inhibited electron thermal conduction and non-LTE ionization physics are important. Their inclusion in the LASNEX modeling results in steepened temperature and density profiles near critical, thus producing a several keV underdense corona. These conditions bring what would otherwise be 100% inverse bremsstrahlung absorption down to the experimentally observed values (50% at 10 14 W/cm). The non-LTE physics is essential to correctly compute the level populations of the high Z atoms moving rapidly through a steep density gradient into the corona. This modeling also shows that x-rays are emitted in a thin overdense region, and on a time scale 50% longer than the laser pulse. Both of these effects are seen in the experiments

  2. The disparate impact of the ion temperature gradient and the density gradient on edge transport and the low-high transition in tokamaks

    International Nuclear Information System (INIS)

    Kleva, Robert G.; Guzdar, Parvez N.

    2009-01-01

    Steepening of the ion temperature gradient in nonlinear fluid simulations of the edge region of a tokamak plasma causes a rapid degradation in confinement. As the density gradient steepens, there is a continuous improvement in confinement analogous to the low (L) to high (H) transition observed in tokamaks. In contrast, as the ion temperature gradient steepens, there is a rapid increase in the particle and energy fluxes and no L-H transition. For a given pressure gradient, confinement always improves when more of the pressure gradient arises from the density gradient, and less of the pressure gradient arises from the ion temperature gradient.

  3. Physics of laser fusion. Volume III. High-power pulsed lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Eimerl, D.; George, E.V.; Trenholme, J.B.; Simmons, W.W.; Hunt, J.T.

    1982-09-01

    High-power pulsed lasers can deliver sufficient energy on inertial-confinement fusion (ICF) time scales (0.1 to 10 ns) to heat and compress deuterium-tritium fuel to fusion-reaction conditions. Several laser systems have been examined, including Nd:glass, CO 2 , KrF, and I 2 , for their ICF applicability. A great deal of developmental effort has been applied to the Nd:glass laser and the CO 2 gas laser systems; these systems now deliver > 10 4 J and 20 x 10 12 W to ICF targets. We are constructing the Nova Nd:glass laser at LLNL to provide > 100 kJ and > 100 x 10 12 W of 1-μm radiation for fusion experimentation in the mid-1980s. For ICF target gain > 100 times the laser input, we expect that the laser driver must deliver approx. 3 to 5 MJ of energy on a time scale of 10 to 20 ns. In this paper we review the technological status of fusion-laser systems and outline approaches to constructing high-power pulsed laser drivers

  4. Ultra-High Gradient S-band Linac for Laboratory and Industrial Applications

    Science.gov (United States)

    Faillace, L.; Agustsson, R.; Dolgashev, V.; Frigola, P.; Murokh, A.; Rosenzweig, J.; Yakimenko, V.

    2010-11-01

    A strong demand for high gradient structures arises from the limited real estate available for linear accelerators. RadiaBeam Technologies is developing a Doubled Energy Compact Accelerator (DECA) structure: an S-band standing wave electron linac designed to operate at accelerating gradients of up to 50 MV/m. In this paper, we present the radio-frequency design of the DECA S-band accelerating structure, operating at 2.856 GHz in the π-mode. The structure design is heavily influenced by NLC collaboration experience with ultra high gradient X-band structures; S-band, however, is chosen to take advantage of commonly available high power S-band klystrons.

  5. Studies of high repetition rate laser-produced plasma soft-X-ray amplifiers

    International Nuclear Information System (INIS)

    Cassou, K.

    2006-12-01

    The progress made as well on the Ti:Sa laser system, as in the control and the knowledge of laser produced X-UV sources allowed the construction of a X-UV laser station dedicated to the applications. My thesis work falls under the development of this station and more particularly on the characterization of a X-UV laser plasma amplifier. The experimental study relates to the coupling improvement of the pump infra-red laser with plasma within the framework of the transient collisional X-UV laser generation. These X-UV lasers are generated in a plasma formed by the interaction of a solid target and a laser pulse of approximately 500 ps duration, followed by a second infra-red laser pulse known as of pump (about 5 ps) impinging on the target in grazing incidence. For the first time, a complete parametric study was undertaken on the influence of the grazing angle on the pumping of the amplifying medium. One of the results was to reach very high peak brightness about 10 28 ph/s/mm 2 /mrad 2 /(0.1%bandwidth), which compares well with the free-electron laser brightness. Moreover, we modified then used a new two-dimensional hydrodynamic code with adaptive mesh refinement in order to understand the influence of the space-time properties of the infra-red laser on the formation and the evolution of the amplifying plasma. Our modeling highlighted the interest to use a super Gaussian transverse profile for the line focus leading to an increase in a factor two of the gain region size and a reduction of the electron density gradient by three orders of magnitude. These improvements should strongly increase the energy contained in X-UV laser beam. We thus used X-UV laser to study the appearance of transient defects produced by a laser IR on a beam-splitter rear side. We also began research on the mechanisms of DNA damage induced by a very intense X-UV radiation. (author)

  6. High Average Power, High Energy Short Pulse Fiber Laser System

    Energy Technology Data Exchange (ETDEWEB)

    Messerly, M J

    2007-11-13

    Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

  7. Potential uses of high gradient magnetic filtration for high-temperature water purification in boiling water reactors

    International Nuclear Information System (INIS)

    Elliott, H.H.; Holloway, J.H.; Abbott, D.G.

    1979-01-01

    Studies of various high-temperature filter devices indicate a potentially positive impact for high gradient magnetic filtration on boiling water reactor radiation level reduction. Test results on in-plant water composition and impurity crystallography are presented for several typical boiling water reactors (BWRs) on plant streams where high-temperature filtration may be particularly beneficial. An experimental model on the removal of red iron oxide (hematite) from simulated reactor water with a high gradient magnetic filter is presented, as well as the scale-up parameters used to predict the filtration efficiency on various high temperature, in-plant streams. Numerical examples are given to illustrate the crud removal potential of high gradient magnetic filters installed at alternative stream locations under typical, steady-state, plant operating conditions

  8. High power all solid state VUV lasers

    International Nuclear Information System (INIS)

    Zhang, Shen-jin; Cui, Da-fu; Zhang, Feng-feng; Xu, Zhi; Wang, Zhi-min; Yang, Feng; Zong, Nan; Tu, Wei; Chen, Ying; Xu, Hong-yan; Xu, Feng-liang; Peng, Qin-jun; Wang, Xiao-yang; Chen, Chuang-tian; Xu, Zu-yan

    2014-01-01

    Highlights: • Polarization and pulse repetition rate adjustable ps 177.3 nm laser was developed. • Wavelength tunable ns, ps and fs VUV lasers were developed. • High power ns 177.3 nm laser with narrow linewidth was investigated. - Abstract: We report the investigation on the high power all solid state vacuum ultra-violet (VUV) lasers by means of nonlinear frequency conversion with KBe 2 BO 3 F 2 (KBBF) nonlinear crystal. Several all solid state VUV lasers have developed in our group, including polarization and pulse repetition rate adjustable picosecond 177.3 nm VUV laser, wavelength tunable nanosecond, picosecond and femtosecond VUV lasers, high power ns 177.3 nm laser with narrow linewidth. The VUV lasers have impact, accurate and precise advantage

  9. High-resolution wavefront control of high-power laser systems

    International Nuclear Information System (INIS)

    Brase, J.; Brown, C.; Carrano, C.; Kartz, M.; Olivier, S.; Pennington, D.; Silva, D.

    1999-01-01

    Nearly every new large-scale laser system application at LLNL has requirements for beam control which exceed the current level of available technology. For applications such as inertial confinement fusion, laser isotope separation, laser machining, and laser the ability to transport significant power to a target while maintaining good beam quality is critical. There are many ways that laser wavefront quality can be degraded. Thermal effects due to the interaction of high-power laser or pump light with the internal optical components or with the ambient gas are common causes of wavefront degradation. For many years, adaptive optics based on thing deformable glass mirrors with piezoelectric or electrostrictive actuators have be used to remove the low-order wavefront errors from high-power laser systems. These adaptive optics systems have successfully improved laser beam quality, but have also generally revealed additional high-spatial-frequency errors, both because the low-order errors have been reduced and because deformable mirrors have often introduced some high-spatial-frequency components due to manufacturing errors. Many current and emerging laser applications fall into the high-resolution category where there is an increased need for the correction of high spatial frequency aberrations which requires correctors with thousands of degrees of freedom. The largest Deformable Mirrors currently available have less than one thousand degrees of freedom at a cost of approximately $1M. A deformable mirror capable of meeting these high spatial resolution requirements would be cost prohibitive. Therefore a new approach using a different wavefront control technology is needed. One new wavefront control approach is the use of liquid-crystal (LC) spatial light modulator (SLM) technology for the controlling the phase of linearly polarized light. Current LC SLM technology provides high-spatial-resolution wavefront control, with hundreds of thousands of degrees of freedom, more

  10. High power laser research and development at the Laboratory for Laser Energetics

    International Nuclear Information System (INIS)

    Soures, J.M.; McCrory, R.L.; Cerqua, K.A.

    1986-01-01

    As part of its research mission - to investigate the interaction of intense radiation with matter - the Laboratory for Laser Energetics (LLE) of the University of Rochester is developing a number of high-peak power and high-average-power laser systems. In this paper we highlight some of the LLE work on solid-state laser research, development and applications. Specifically, we discuss the performance and operating characteristics of Omega, a twenty-four beam, 4000 Joule, Nd:glass laser system which is frequently tripled using the polarization mismatch scheme. We also discuss progress in efforts to develop high-average-power solid-state laser systems with active-mirror and slab geometries and to implement liquid-crystal devices in high-power Nd:glass lasers. Finally we present results from a program to develop a compact, ultrahigh-peak-power solid-state laser using the concept of frequency chirped pulse amplification

  11. Development of high-power CO2 lasers and laser material processing

    Science.gov (United States)

    Nath, Ashish K.; Choudhary, Praveen; Kumar, Manoj; Kaul, R.

    2000-02-01

    Scaling laws to determine the physical dimensions of the active medium and optical resonator parameters for designing convective cooled CO2 lasers have been established. High power CW CO2 lasers upto 5 kW output power and a high repetition rate TEA CO2 laser of 500 Hz and 500 W average power incorporated with a novel scheme for uniform UV pre- ionization have been developed for material processing applications. Technical viability of laser processing of several engineering components, for example laser surface hardening of fine teeth of files, laser welding of martensitic steel shroud and titanium alloy under-strap of turbine, laser cladding of Ni super-alloy with stellite for refurbishing turbine blades were established using these lasers. Laser alloying of pre-placed SiC coating on different types of aluminum alloy, commercially pure titanium and Ti-6Al-4V alloy, and laser curing of thermosetting powder coating have been also studied. Development of these lasers and results of some of the processing studies are briefly presented here.

  12. High-gradient electron accelerator powered by a relativisitic klystron

    International Nuclear Information System (INIS)

    Allen, M.A.; Boyd, J.K.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Haimson, J.; Hoag, H.A.; Hopkins, D.B.; Houck, T.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Mecklenburg, B.; Miller, R.H.; Ruth, R.D.; Ryne, R.D.; Sessler, A.M.; Vlieks, A.E.; Wang, J.W.; Westenskow, G.A.; Yu, S.S.

    1989-01-01

    We have used relativistic klystron technology to extract 290 MW of peak power at 11.4 GHz from an induction linac beam, and to power a short 11.4-GHz high-gradient accelerator. We have measured rf phase stability, field emission, and the momentum spectrum of an accelerated electron beam. An average accelerating gradient of 84 MV/m has been achieved with 80 MW of relativistic klystron power

  13. Effect of diffraction and film-thickness gradients on wafer-curvature measurements of thin-film stress

    International Nuclear Information System (INIS)

    Breiland, W.G.; Lee, S.R.; Koleske, D.D.

    2004-01-01

    When optical measurements of wafer curvature are used to determine thin-film stress, the laser beams that probe the sample are usually assumed to reflect specularly from the curved surface of the film and substrate. Yet, real films are not uniformly thick, and unintended thickness gradients produce optical diffraction effects that steer the laser away from the ideal specular condition. As a result, the deflection of the laser in wafer-curvature measurements is actually sensitive to both the film stress and the film-thickness gradient. We present a Fresnel-Kirchhoff optical diffraction model of wafer-curvature measurements that provides a unified description of these combined effects. The model accurately simulates real-time wafer-curvature measurements of nonuniform GaN films grown on sapphire substrates by vapor-phase epitaxy. During thin-film growth, thickness gradients cause the reflected beam to oscillate asymmetrically about the ideal position defined by the stress-induced wafer curvature. This oscillating deflection has the same periodicity as the reflectance of the growing film, and the deflection amplitude is a function of the film-thickness gradient, the mean film thickness, the wavelength distribution of the light source, the illuminated spot size, and the refractive indices of the film and substrate. For typical GaN films grown on sapphire, misinterpretation of these gradient-induced oscillations can cause stress-measurement errors that approach 10% of the stress-thickness product; much greater errors occur in highly nonuniform films. Only transparent films can exhibit substantial gradient-induced deflections; strongly absorbing films are immune

  14. High-field electron-photon interactions

    International Nuclear Information System (INIS)

    Hartemann, F V.

    1999-01-01

    Recent advances in novel technologies (including chirped-pulse amplification, femtosecond laser systems operating in the TW-PW range, high-gradient rf photoinjectors, and synchronized relativistic electron bunches with subpicosecond durations and THz bandwidths) allow experimentalists to study the interaction of relativistic electrons with ultrahigh-intensity photon fields. Ponderomotive scattering can accelerate these electrons with extremely high gradients in a three-dimensional vacuum laser focus. The nonlinear Doppler shift induced by relativistic radiation pressure in Compton backscattering is shown to yield complex nonlinear spectra which can be modified by using temporal laser pulse shaping techniques. Colliding laser pulses, where ponderomotive acceleration and Compton backscattering are combined, could also yield extremely short wavelength photons. Finally, one expects strong radiative corrections when the Doppler-upshifted laser wavelength approaches the Compton scale. These are discussed within the context of high-field classical electrodynamics, a new discipline borne out of the aforementioned innovations

  15. Vacuum ultraviolet Ar2*laser pumped by a high-intensity laser

    International Nuclear Information System (INIS)

    Kubodera, Shoichi; Kaku, Masanori; Higashiguchi, Takeshi

    2004-01-01

    We observed a small-signal gain of Ar 2 * emission at 126 nm by use of an Ar-filled hollow fiber to guide the ultrashort-pulse high-intensity laser propagation. The small signal gain coefficient was measured to be 0.05 cm -1 at 126 nm. Kinetic analysis revealed that the electrons produced by the high-intensity laser through an optical-field ionization process initiated the Ar 2 * production process. This laser scheme could be combined with high harmonic radiation of the pump laser in the vacuum ultraviolet (VUV), leading to the production of amplified ultrashort VUV pulses. (author)

  16. Physical grounds for biological effect of laser radiation

    International Nuclear Information System (INIS)

    Rubinov, A N

    2003-01-01

    A new approach to the understanding of biological activity caused by low-intensity laser radiation, in which coherence is a factor of paramount importance, has been developed. It is based on the dipole interaction of gradient laser fields with cells, organelles and membranes. The laser intensity gradients in an object arise due to the interference of the light scattered by the tissue with the incident light beam (speckle formation). Apart from speckles, different types of light spatial modulation can be created deliberately using different schemes for beam interference. It is shown that gradient laser fields may cause spatial modulation of the concentration of particles and increase their 'partial temperature'. This paper presents the results of experimental observation of trapping of different types of particles, including human lymphocytes, in the interference fields of the He-Ne laser. The sweep-net effect on particles of different sizes on moving the laser field is demonstrated and crystal-like self-organization of particles in the laser gradient field is observed. The influence of gradient laser fields on erythrocyte rouleaus, on the apoptosis of human lymphocytes as well as on their chromosome aberrations is demonstrated. It may be concluded from the experimental studies that the influence of an interference laser field with a rightly chosen period can stimulate the repair system of a cell, increasing its viability

  17. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

    2017-01-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses

  18. Design of a high-power, high-brightness Nd:YAG solar laser.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana; Garcia, Dário

    2014-03-20

    A simple high-power, high-brightness Nd:YAG solar laser pumping approach is presented in this paper. The incoming solar radiation is both collected and concentrated by four Fresnel lenses and redirected toward a Nd:YAG laser head by four plane-folding mirrors. A fused-silica secondary concentrator is used to compress the highly concentrated solar radiation to a laser rod. Optimum pumping conditions and laser resonator parameters are found through ZEMAX and LASCAD numerical analysis. Solar laser power of 96 W is numerically calculated, corresponding to the collection efficiency of 24  W/m². A record-high solar laser beam brightness figure of merit of 9.6 W is numerically achieved.

  19. 8. High power laser and ignition facilities

    International Nuclear Information System (INIS)

    Bayramian, A.J.; Beach, R.J.; Bibeau, C.

    2002-01-01

    This document gives a review of the various high power laser projects and ignition facilities in the world: the Mercury laser system and Electra (Usa), the krypton fluoride (KrF) laser and the HALNA (high average power laser for nuclear-fusion application) project (Japan), the Shenguang series, the Xingguang facility and the TIL (technical integration line) facility (China), the Vulcan peta-watt interaction facility (UK), the Megajoule project and its feasibility phase: the LIL (laser integration line) facility (France), the Asterix IV/PALS high power laser facility (Czech Republic), and the Phelix project (Germany). In Japan the 100 TW Petawatt Module Laser, constructed in 1997, is being upgraded to the world biggest peta-watt laser. Experiments have been performed with single-pulse large aperture e-beam-pumped Garpun (Russia) and with high-current-density El-1 KrF laser installation (Russia) to investigate Al-Be foil transmittance and stability to multiple e-beam irradiations. An article is dedicated to a comparison of debris shield impacts for 2 experiments at NIF (national ignition facility). (A.C.)

  20. Ablation Behavior of Plasma-Sprayed La1-xSrxTiO3+δ Coating Irradiated by High-Intensity Continuous Laser.

    Science.gov (United States)

    Zhu, Jinpeng; Ma, Zhuang; Gao, Yinjun; Gao, Lihong; Pervak, Vladimir; Wang, Lijun; Wei, Chenghua; Wang, Fuchi

    2017-10-11

    Laser protection for optical components, particularly those in high-power laser systems, has been a major concern. La 1-x Sr x TiO 3+δ with its good optical and thermal properties can be potentially applied as a high-temperature optical protective coating or high-reflectivity material for optical components. However, the high-power laser ablation behavior of plasma-sprayed La 1-x Sr x TiO 3+δ (x = 0.1) coatings has rarely been investigated. Thus, in this study, laser irradiation experiments were performed to study the effect of high-intensity continuous laser on the ablation behavior of the La 1-x Sr x TiO 3+δ coating. The results show that the La 1-x Sr x TiO 3+δ coating undergoes three ablation stages during laser irradiation: coating oxidation, formation and growth of new structures (columnar and dendritic crystals), and mechanical failure. A finite-element simulation was also conducted to explore the mechanism of the ablation damage to the La 1-x Sr x TiO 3+δ coating and provided a good understanding of the ablation behavior. The apparent ablation characteristics are attributed to the different temperature gradients determined by the reflectivity and thermal diffusivity of the La 1-x Sr x TiO 3+δ coating material, which are critical factors for improving the antilaser ablation property. Now, the stainless steel substrate deposited by it can effectively work as a protective shield layer against ablation by laser irradiation.

  1. Laser safety at high profile projects

    Science.gov (United States)

    Barat, K.

    2011-03-01

    Laser Safety at high profile laser facilities tends to be more controlled than in the standard laser lab found at a research institution. The reason for this is the potential consequences for such facilities from incidents. This ranges from construction accidents, to equipment damage to personnel injuries. No laser user wants to sustain a laser eye injury. Unfortunately, many laser users, most commonly experienced researchers and inexperienced graduate students, do receive laser eye injuries during their careers. . More unforgiveable is the general acceptance of this scenario, as part of the research & development experience. How do senior researchers, safety personnel and management stop this trend? The answer lies in a cultural change that involves institutional training, user mentoring, hazard awareness by users and administrative controls. None of these would inhibit research activities. As a matter of fact, proper implementation of these controls would increase research productivity. This presentation will review and explain the steps needed to steer an institution, research division, group or individual lab towards a culture that should nearly eliminate laser accidents. As well as how high profile facilities try to avoid laser injuries. Using the definition of high profile facility as one who's funding in the million to billions of dollars or Euros and derives form government funding.

  2. Laser fusion and high energy density science

    International Nuclear Information System (INIS)

    Kodama, Ryosuke

    2005-01-01

    High-power laser technology is now opening a variety of new fields of science and technology using laser-produced plasmas. The laser plasma is now recognized as one of the important tools for the investigation and application of matter under extreme conditions, which is called high energy density science. This chapter shows a variety of applications of laser-produced plasmas as high energy density science. One of the more attractive industrial and science applications is the generation of intense pulse-radiation sources, such as the generation of electro-magnetic waves in the ranges of EUV (Extreme Ultra Violet) to gamma rays and laser acceleration of charged particles. The laser plasma is used as an energy converter in this regime. The fundamental science applications of high energy density physics are shown by introducing laboratory astrophysics, the equation of state of high pressure matter, including warm dense matter and nuclear science. Other applications are also presented, such as femto-second laser propulsion and light guiding. Finally, a new systematization is proposed to explore the possibility of the high energy density plasma application, which is called high energy plasma photonics''. This is also exploration of the boundary regions between laser technology and beam optics based on plasma physics. (author)

  3. Laser wakefield acceleration with high-power, few-cycle mid-IR lasers

    OpenAIRE

    Papp, Daniel; Wood, Jonathan C.; Gruson, Vincent; Bionta, Mina; Gruse, Jan-Niclas; Cormier, Eric; Najmudin, Zulfikar; Légaré, François; Kamperidis, Christos

    2018-01-01

    The study of laser wakefield electron acceleration (LWFA) using mid-IR laser drivers is a promising path for future laser driven electronaccelerators, when compared to traditional near-IR laser drivers uperating at 0.8-1 {\\mu}m central wavelength ({\\lambda}laser), as the necessary vector potential a_0 for electron injection can be achieved with smaller laser powers due to the linear dependence on {\\lambda}laser. In this work, we perform 2D PIC simulations on LWFA using few-cycle high power (5...

  4. Comparative Studies of High-Gradient Rf and Dc Breakdowns

    CERN Document Server

    Kovermann, Jan Wilhelm; Wuensch, Walter

    2010-01-01

    The CLIC project is based on normal-conducting high-gradient accelerating structures with an average accelerating gradient of 100 MV/m. The maximum achievable gradient in these structures is limited by the breakdown phenomenon. The physics of breakdowns is not yet fully understood quantitatively. A full knowledge could have strong impact on the design, material choice and construction of rf structures. Therefore, understanding breakdowns has great importance to reaching a gradient of 100MV/m with an acceptable breakdown probability. This thesis addresses the physics underlying the breakdown effect, focusing on a comparison of breakdowns in rf structures and in a dc spark setup. The dc system is simpler, easier to benchmark against simulations, with a faster turnaround time, but the relationship to rf breakdown must be established. To do so, an experimental approach based on optical diagnostics and electrical measurements methods was made. Following an introduction into the CLIC project, a general theoretical ...

  5. Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Fang, Yurui; Zhang, Zhenglong; Chen, Li; Sun, Mengtao

    2015-01-14

    Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

  6. High gradient RF test results of S-band and C-band cavities for medical linear accelerators

    Science.gov (United States)

    Degiovanni, A.; Bonomi, R.; Garlasché, M.; Verdú-Andrés, S.; Wegner, R.; Amaldi, U.

    2018-05-01

    TERA Foundation has proposed and designed hadrontherapy facilities based on novel linacs, i.e. high gradient linacs which accelerate either protons or light ions. The overall length of the linac, and therefore its cost, is almost inversely proportional to the average accelerating gradient. With the scope of studying the limiting factors for high gradient operation and to optimize the linac design, TERA, in collaboration with the CLIC Structure Development Group, has conducted a series of high gradient experiments. The main goals were to study the high gradient behavior and to evaluate the maximum gradient reached in 3 and 5.7 GHz structures to direct the design of medical accelerators based on high gradient linacs. This paper summarizes the results of the high power tests of 3.0 and 5.7 GHz single-cell cavities.

  7. Superconducting niobium cavities with high gradients

    International Nuclear Information System (INIS)

    Kneisel, P.; Saito, K.

    1992-01-01

    Present accelerator projects making use of superconducting cavity technology are constructed with design accelerating gradients E acc ranging between 5 MV/m and 8 MV/m and Q-values of several 10 9 . Future plans for upgrades of existing accelerators or for linear colliders call for gradients greater than 15 MV/m corresponding to peak surface electric fields above 30 MV/m. These demands challenge state-of-the-art production technology and require improvements in processing and handling of these cavities to overcome the major performance limitation of field emission loading. This paper reports on efforts to improve the performance of cavities made from niobium from different suppliers by using improved cleaning techniques after processing and ultrahigh vacuum annealing at temperatures of 1400 C. In single cell L-band cavities peak surface electric fields as high as 50 MV/m have been measured without significant field emission loading. (Author) 8 refs., fig

  8. High precision, rapid laser hole drilling

    Science.gov (United States)

    Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.

    2013-04-02

    A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.

  9. Determination of boundaries between ranges of high and low gradient of beam profile.

    Science.gov (United States)

    Wendykier, Jacek; Bieniasiewicz, Marcin; Grządziel, Aleksandra; Jedynak, Tadeusz; Kośniewski, Wiktor; Reudelsdorf, Marta; Wendykier, Piotr

    2016-01-01

    This work addresses the problem of treatment planning system commissioning by introducing a new method of determination of boundaries between high and low gradient in beam profile. The commissioning of a treatment planning system is a very important task in the radiation therapy. One of the main goals of this task is to compare two field profiles: measured and calculated. Applying points of 80% and 120% of nominal field size can lead to the incorrect determination of boundaries, especially for small field sizes. The method that is based on the beam profile gradient allows for proper assignment of boundaries between high and low gradient regions even for small fields. TRS 430 recommendations for commissioning were used. The described method allows a separation between high and low gradient, because it directly uses the value of the gradient of a profile. For small fields, the boundaries determined by the new method allow a commissioning of a treatment planning system according to the TRS 430, while the point of 80% of nominal field size is already in the high gradient region. The method of determining the boundaries by using the beam profile gradient can be extremely helpful during the commissioning of the treatment planning system for Intensity Modulated Radiation Therapy or for other techniques which require very small field sizes.

  10. Progress of Laser-Driven Plasma Accelerators

    International Nuclear Information System (INIS)

    Nakajima, Kazuhisa

    2007-01-01

    There is a great interest worldwide in plasma accelerators driven by ultra-intense lasers which make it possible to generate ultra-high gradient acceleration and high quality particle beams in a much more compact size compared with conventional accelerators. A frontier research on laser and plasma accelerators is focused on high energy electron acceleration and ultra-short X-ray and Tera Hertz radiations as their applications. These achievements will provide not only a wide range of sciences with benefits of a table-top accelerator but also a basic science with a tool of ultrahigh energy accelerators probing an unknown extremely microscopic world.Harnessing the recent advance of ultra-intense ultra-short pulse lasers, the worldwide research has made a tremendous breakthrough in demonstrating high-energy high-quality particle beams in a compact scale, so called ''dream beams on a table top'', which represents monoenergetic electron beams from laser wakefield accelerators and GeV acceleration by capillary plasma-channel laser wakefield accelerators. This lecture reviews recent progress of results on laser-driven plasma based accelerator experiments to quest for particle acceleration physics in intense laser-plasma interactions and to present new outlook for the GeV-range high-energy laser plasma accelerators

  11. Novel hollow fiber compressor for high power, multi-mJ ultrafast lasers

    International Nuclear Information System (INIS)

    Nagy, T.; Simon, P.; Schweinberger, W.; Sommer, A.; Schultze, M.; Kienberger, R.; Krausz, F.

    2010-01-01

    Complete text of publication follows. The current trends in ultrafast laser development include, besides the reduction of the pulse duration, also the up-scaling of the pulse energy and the increase of the repetition rate. Recently, multi-mJ, multi-kHz lasers delivering sub-30 fs pulses have become available. The compression of the output pulses of such lasers to sub-5 fs duration is a challenging task. In order to maintain good temporal contrast and beam profile, the preferred way for spectral broadening is to use noble-gas-filled hollow fibers. For launching multi-mJ pulses in the waveguide, its inner diameter has to be large in order to keep the intensity at low levels so that the ionization losses are still tolerable. For optimal in-coupling the differential pressure scheme is very favourable, which, however requires longer waveguide lengths to compensate for the reduced effective interaction length caused by the pressure gradient. Recently, a novel hollow fiber construction has been developed comprising a waveguide formed by a stretched flexible capillary tube. This special construction resolves the usual strong limitation of the length of the waveguide, provides excellent straightness, and inherently supports the differential pressure scheme. The only drawback of the flexible fiber unit to date was its susceptibility to thermal damage in case of high average power input beams. To solve this problem we present a novel composite fiber unit, which consists of a thick-walled taper followed by a long flexible fiber. This construction combines the advantages of both types: the high resistibility of the taper and the free length-scalability of a flexible fiber. In order to demonstrate the potential of the new fiber design, a 2 m long composite fiber with an inner diameter of 320 μm was placed at the output of a CPA Ti:Sa laser system comprising an oscillator, a grating-prism (grism) stretcher, two multi-pass amplifier stages and a compressor combining bulk glass

  12. Material Processing with High Power CO2-Lasers

    Science.gov (United States)

    Bakowsky, Lothar

    1986-10-01

    After a period of research and development lasertechnique now is regarded as an important instrument for flexible, economic and fully automatic manufacturing. Especially cutting of flat metal sheets with high power C02-lasers and CNC controlled two or three axes handling systems is a wide spread. application. Three dimensional laser cutting, laser-welding and -heat treatment are just at the be ginning of industrial use in production lines. The main. advantages of laser technology. are - high. accuracy - high, processing velocity - law thermal distortion. - no tool abrasion. The market for laser material processing systems had 1985 a volume of 300 Mio S with growth rates between, 20 % and 30 %. The topic of this lecture are hiTrh. power CO2-lasers. Besides this systems two others are used as machining tools, Nd-YAG- and Eximer lasers. All applications of high. power CO2-lasers to industrial material processing show that high processing velocity and quality are only guaranteed in case of a stable intensity. profile on the workpiece. This is only achieved by laser systems without any power and mode fluctuations and by handling systems of high accuracy. Two applications in the automotive industry are described, below as examples for laser cutting and laser welding of special cylindrical motor parts.

  13. High gradient test of the C-band choke-mode type accelerating structure

    International Nuclear Information System (INIS)

    Inagaki, T.; Shintake, T.; Baba, H.; Togawa, K.; Onoe, K.; Marechal, X.; Takashima, T.; Takahashi, S.; Matsumoto, H.

    2004-01-01

    The C-band (5712 MHz) choke-mode type accelerating structure will be used for SPring-8 Compact SASE-FEL Source (SCSS). To make the accelerator length short, we designed the field gradient as high as 40 MV/m. Since it is higher gradient than other traditional electron accelerators, we have to carefully check its performance (RF breakdown, dark current emission, etc.) in the high gradient test stand. The first experiment will be scheduled in this summer. In this paper, we will describe the preparation progress for the test. (author)

  14. Quality and performance of laser cutting with a high power SM fiber laser

    DEFF Research Database (Denmark)

    Kristiansen, Morten; Selchau, Jacob; Olsen, F. O.

    2013-01-01

    The introduction of high power single mode fiber lasers allows for a beam of high power and a good beam quality factor (M2 ” 1.2), compared to the multimode fiber lasers often utilised in macro laser metal cutting. This paper describes fundamental studies of macro laser metal cutting with a singl...

  15. Development of high power pulsed CO2 laser

    International Nuclear Information System (INIS)

    Nakai, Sadao; Matoba, Masafumi; Fujita, Hisanori; Daido, Hiroyuki; Inoue, Mitsuo

    1982-01-01

    The inertial nuclear fusion research using pellet implosion has rapidly progressed accompanying laser technique improvement and output increase. As the high output lasers for this purpose, Nd glass lasers or CO 2 lasers are used. The CO 2 lasers possess the characteristics required as reactor lasers, i.e., high efficiency, high frequency repetition, possibility of scale-up and economy. So, the technical development of high power CO 2 lasers assuming also as reactor drivers has been performed at a quick pace together with the research on the improvement of efficiency of pellet implosion by 10 μm laser beam. The Institute of Laser Engineering, Osaka University, stated to build a laser system LEKKO No. 8 of 8 beams and 10 kJ based on the experiences in laser systems LEKKO No. 1 and LEKKO No. 2, and the system LEKKO No. 8 was completed in March, 1981. The operation tests for one year since then has indicated as the laser characteristics that the system performance was as designed initially. This paper reviews the structure, problems and present status of the large scale CO 2 lasers. In other words, the construction of laser system, CO 2 laser proper, oscillator, booster amplifier, prevention of parasitic oscillation, non-linear pulse propagation and fairing of output pulse form, system control and beam alignment, and high power problems are described. The results obtained are to be reported in subsequent issues. (Wakatsuki, Y.)

  16. Particle capture efficiency in a multi-wire model for high gradient magnetic separation

    KAUST Repository

    Eisenträ ger, Almut; Vella, Dominic; Griffiths, Ian M.

    2014-01-01

    High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires

  17. Sideband instability analysis based on a one-dimensional high-gain free electron laser model

    Science.gov (United States)

    Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan; Yoon, Moohyun; Zhou, Guanqun

    2017-12-01

    When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulator tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (˜10 %) provides effective suppression of the sideband instability in the postsaturation regime.

  18. Laser-driven acceleration with Bessel and Gaussian beams

    International Nuclear Information System (INIS)

    Hafizi, B.; Esarey, E.; Sprangle, P.

    1997-01-01

    The possibility of enhancing the energy gain in laser-driven accelerators by using Bessel laser beams is examined. Scaling laws are derived for the propagation length, acceleration gradient, and energy gain in various accelerators for both Gaussian and Bessel beam drivers. For equal beam powers, the energy gain can be increased by a factor of N 1/2 by utilizing a Bessel beam with N lobes, provided that the acceleration gradient is linearly proportional to the laser field. This is the case in the inverse free electron laser and the inverse Cherenkov accelerators. If the acceleration gradient is proportional to the square of the laser field (e.g., the laser wakefield, plasma beat wave, and vacuum beat wave accelerators), the energy gain is comparable with either beam profile. copyright 1997 American Institute of Physics

  19. Laser ablation of UHMWPE-polyethylene by 438 nm high energy pulsed laser

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, L.; Gammino, S.; Mezzasalma, A.M.; Visco, A.M.; Badziak, J.; Parys, P.; Wolowski, J.; Woryna, E.; Krasa, J.; Laska, L.; Pfeifer, M.; Rohlena, K.; Boody, F.P

    2004-04-15

    Pulsed laser ablation of ultra-high-molecular-weight-polyethylene (UHMWPE) is investigated at Prague Asterix Laser System (PALS) Laboratory. The high ablation yield as a function of laser energy is presented at 438 nm laser wavelength. The mechanisms of the polymer ablation are studied on the base of ''in situ'' analysis, such as mass quadrupole spectrometry and time-of-flight measurements, and ''ex situ'' analysis, such as SEM investigations and Raman spectroscopy. Results show that the laser irradiation induces a strong polymer dehydrogenation and molecular emission due to different C{sub x}H{sub y} groups having high kinetic energy and high charge state. At a laser pulse energy of 150 J the H{sup +}, C{sup n+} ions (n=1 to 6) are emitted from the plasma with velocities of the order of 10{sup 8} cm/s, while the C{sub x}H{sub y} groups and the carbon clusters, detected up to C{sub 16}, have a velocity about one or two order magnitude lower. The laser ablation process produces a deep crater in the polymer, which depth depends on the laser pulse energy and it is of the order of 500 {mu}m. The crater volume increases with the laser pulse energy. Results demonstrated that the laser radiation modifies the polymer chains because dehydrogenated material and carbon-like structures are detected in the crater walls and in the bottom of the crater, respectively. A comparison of the experimental results with the data available in literature is presented and discussed.

  20. Self-guiding of high-intensity laser pulses for laser wake field acceleration

    International Nuclear Information System (INIS)

    Umstader, D.; Liu, X.

    1992-01-01

    A means of self-guiding an ultrashort and high-intensity laser pulse is demonstrated both experimentally and numerically. Its relevance to the laser wake field accelerator concept is discussed. Self-focusing and multiple foci formation are observed when a high peak power (P>100 GW), 1 μm, subpicosecond laser is focused onto various gases (air or hydrogen). It appears to result from the combined effects of self-focusing by the gas, and de-focusing both by diffraction and the plasma formed in the central high-intensity region. Quasi-stationary computer simulations show the same multiple foci behavior as the experiments. The results suggest much larger nonlinear electronic susceptibilities of a gas near or undergoing ionization in the high field of the laser pulse. Although self-guiding of a laser beam by this mechanism appears to significantly extend its high-intensity focal region, small-scale self-focusing due to beam non-uniformity is currently a limitation

  1. Exploiting the natural doping gradient of Nd:YLF crystals for high-power end pumped lasers

    CSIR Research Space (South Africa)

    Bollig, C

    2008-01-01

    Full Text Available decided to use crystals of a doping concentration below the 0.5% previously used. In addition, researchers decided to exploit the natural doping gradient along the length of the boule, which is especially pronounced at low concentrations but commonly...

  2. High-power planar dielectric waveguide lasers

    International Nuclear Information System (INIS)

    Shepherd, D.P.; Hettrick, S.J.; Li, C.; Mackenzie, J.I.; Beach, R.J.; Mitchell, S.C.; Meissner, H.E.

    2001-01-01

    The advantages and potential hazards of using a planar waveguide as the host in a high-power diode-pumped laser system are described. The techniques discussed include the use of proximity-coupled diodes, double-clad waveguides, unstable resonators, tapers, and integrated passive Q switches. Laser devices are described based on Yb 3+ -, Nd 3+ -, and Tm 3+ -doped YAG, and monolithic and highly compact waveguide lasers with outputs greater than 10 W are demonstrated. The prospects for scaling to the 100 W level and for further integration of devices for added functionality in a monolithic laser system are discussed. (author)

  3. Development of a high gradient quadrupole for the LHC Interaction Regions

    International Nuclear Information System (INIS)

    Bossert, R.; Feher, S.; Gourlay, S.A.

    1997-04-01

    A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-layer, cos(2θ) coil geometry with a 70 mm aperture operating in superfluid helium. This paper summarizes the progress on a magnetic, mechanical and thermal design that meets the requirements of maximum gradient above 250 T/m, high field quality and provision for adequate cooling in a high radiation environment

  4. Design of a High Gradient Quadrupole for the LHC Interaction Regions

    International Nuclear Information System (INIS)

    Bossert, R.; Gourlay, S.A.; Heger, T.; Huang, Y.; Kerby, J.; Lamm, M.J.; Limon, P.J.; Mazur, P.O.; Nobrega, F.; Ozelis, J.P.; Sabbi, G.; Strait, J.; Zlobin, A.V.; Caspi, S.; Dell'orco, D.; McInturff, A.D.; Scanlan, R.M.; Van Oort, J.M.; Gupta, R.C.

    1997-03-01

    A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is currently engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-shell, cos2θ coil geometry with a 70 mm aperture. This paper summarizes the progress on a magnetic and mechanical design that meets the requirements of maximum gradient ≥250 T/m, operation at 1.8K, high field quality and provision for adequate cooling in a high radiation environment

  5. High Gradient Accelerating Structures for Carbon Therapy Linac

    Energy Technology Data Exchange (ETDEWEB)

    Kutsaev, Sergey; Agustsson, R.; Faillace, L.; Goel, A.; Mustapha, B.; Nassiri, A.; Ostroumov, P.; Plastun, A.; Savin, E.

    2016-05-01

    Carbon therapy is the most promising among techniques for cancer treatment, as it has demonstrated significant improvements in clinical efficiency and reduced toxicity profiles in multiple types of cancer through much better localization of dose to the tumor volume. RadiaBeam, in collaboration with Argonne National Laboratory, are developing an ultra-high gradient linear accelerator, Advanced Compact Carbon Ion Linac (ACCIL), for the delivery of ion-beams with end-energies up to 450 MeV/u for 12C6+ ions and 250 MeV for protons. In this paper, we present a thorough comparison of standing and travelling wave designs for high gradient S-Band accelerating structures operating with ions at varying velocities, relative to the speed of light, in the range 0.3-0.7. In this paper we will compare these types of accelerating structures in terms of RF, beam dynamics and thermo-mechanical performance.

  6. Solid state pump lasers with high power and high repetition rate

    International Nuclear Information System (INIS)

    Oba, Masaki; Kato, Masaaki; Arisawa, Takashi

    1995-01-01

    We built a laser diode pumped solid state green laser (LDPSSGL) rated at high repetition rate. Two laser heads are placed in one cavity with a rotator in between to design to avoid thermal lensing and thermal birefringence effect. Although average green laser power higher than 10 W was obtained at 1 kHz repetition rate with pulse width of 20-30 nsec, the beam quality was so much deteriorated that energy efficiency was as low as 2 %. Learning from this experience that high power oscillator causes a lot of thermal distortion not only in the laser rod but also in the Q-switch device, we proceeded to built a oscillator/amplifier system. A low power oscillator has a slab type crystal in the cavity. As a result spatial distribution of laser power was extremely improved. As we expect that the high repetition rate solid state laser should be CW operated Q-switch type laser from the view point of lifetime of diode lasers, a conventional arc lamp pumped CW Q-switch green YAG laser of which the repetition rate is changeable from 1 kHz to 5 kHz and the pulse width is 250-570 nsec was also tested to obtain pumping characteristics of a dye laser as a function of power, pulse width etc., and dye laser pulse width of 100-130 nsec were obtained. (author)

  7. High-efficiency cavity-dumped micro-chip Yb:YAG laser

    Science.gov (United States)

    Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

    2014-09-01

    High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

  8. Techniques for Ultra-high Magnetic Field Gradient NMR Diffusion Measurements

    Science.gov (United States)

    Sigmund, Eric E.; Mitrovic, Vesna F.; Calder, Edward S.; Will Thomas, G.; Halperin, William P.; Reyes, Arneil P.; Kuhns, Philip L.; Moulton, William G.

    2001-03-01

    We report on development and application of techniques for ultraslow diffusion coefficient measurements through nuclear magnetic resonance (NMR) in high magnetic field gradients. We have performed NMR experiments in a steady fringe field gradient of 175 T/m from a 23 T resistive Bitter magnet, as well as in a gradient of 42 T/m from an 8 T superconducting magnet. New techniques to provide optimum sensitivity in these experiments are described. To eliminate parasitic effects of the temporal instability of the resistive magnet, we have introduced a passive filter: a highly conductive cryogen-cooled inductive shield. We show experimental demonstration of such a shield’s effect on NMR performed in the Bitter magnet. For enhanced efficiency, we have employed “frequency jumping” in our spectrometer system. Application of these methods has made possible measurements of diffusion coefficients as low as 10-10 cm^2/s, probing motion on a 250 nm length scale.

  9. High contrast laser marking of alumina

    International Nuclear Information System (INIS)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; Val, J. del; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-01-01

    Highlights: • Laser marking of alumina using near infrared (NIR) lasers was experimentally analyzed. • Color change produced by NIR lasers is due to thermally induced oxygen vacancies. • Laser marking results obtained using NIR lasers and green laser are compared. • High contrast marks on alumina were achieved. - Abstract: Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks

  10. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting

    Science.gov (United States)

    Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan

    2016-04-01

    The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.

  11. High-power fiber-coupled pump lasers for fiber lasers

    Science.gov (United States)

    Kasai, Yohei; Aizawa, Takuya; Tanaka, Daiichiro

    2018-02-01

    We present high-power fiber-coupled pump modules utilized effectively for ultra-high power single-mode (SM) fiber lasers. Maximum output power of 392 W was achieved at 23 A for 915 nm pump, and 394 W for 976 nm pump. Fiber core diameter is 118 μm and case temperature is 25deg. C. Polarization multiplexing technique was newly applied to our optical system. High-reliability of the laser diodes (LD) at high-power operation has been demonstrated by aging tests. Advanced package structure was developed that manages uncoupled light around input end of the fiber. 800 hours continuous drive with uncoupled light power of 100 W has been achieved.

  12. Development of a high power femtosecond laser

    CSIR Research Space (South Africa)

    Neethling, PH

    2010-10-01

    Full Text Available The Laser Research Institute and the CSIR National Laser Centre are developing a high power femtosecond laser system in a joint project with a phased approach. The laser system consists of an fs oscillator and a regenerative amplifier. An OPCPA...

  13. High-gradient operators in the psl(2|2 Gross–Neveu model

    Directory of Open Access Journals (Sweden)

    Alessandra Cagnazzo

    2015-03-01

    Full Text Available It has been observed more than 25 years ago that sigma model perturbation theory suffers from strongly RG-relevant high-gradient operators. The phenomenon was first seen in 1-loop calculations for the O(N vector model and it is known to persist at least to two loops. More recently, Ryu et al. suggested that a certain deformation of the psl(N|N WZNW-model at level k=1, or equivalently the psl(N|N  Gross–Neveu model, could be free of RG-relevant high-gradient operators and they tested their suggestion to leading order in perturbation theory. In this note we establish the absence of strongly RG-relevant high-gradient operators in the psl(2|2 Gross–Neveu model to all loops. In addition, we determine the spectrum for a large subsector of the model at infinite coupling and observe that all scaling weights become half-integer. Evidence for a conjectured relation with the CP1|2 sigma model is not found.

  14. High-energy krypton fluoride lasers for inertial fusion.

    Science.gov (United States)

    Obenschain, Stephen; Lehmberg, Robert; Kehne, David; Hegeler, Frank; Wolford, Matthew; Sethian, John; Weaver, James; Karasik, Max

    2015-11-01

    Laser fusion researchers have realized since the 1970s that the deep UV light from excimer lasers would be an advantage as a driver for robust high-performance capsule implosions for inertial confinement fusion (ICF). Most of this research has centered on the krypton-fluoride (KrF) laser. In this article we review the advantages of the KrF laser for direct-drive ICF, the history of high-energy KrF laser development, and the present state of the art and describe a development path to the performance needed for laser fusion and its energy application. We include descriptions of the architecture and performance of the multi-kilojoule Nike KrF laser-target facility and the 700 J Electra high-repetition-rate KrF laser that were developed at the U.S. Naval Research Laboratory. Nike and Electra are the most advanced KrF lasers for inertial fusion research and energy applications.

  15. Research with high-power short-wavelength lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Campbell, E.M.; Lindl, J.D.; Storm, E.

    1985-01-01

    Three important high-temperature, high-density experiments were conducted recently using the 10-TW, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. These experiments demonstrated successful solutions to problems that arose during previous experiments with long wavelength lasers (lambda greater than or equal to 1μm) in which inertial confinement fusion (ICF), x-ray laser, and other high-temperature physics concepts were being tested. The demonstrations were: (1) large-scale plasmas (typical dimensions of up to 1000 laser wavelengths) were produced in which potentially deleterious laser-plasma instabilities were collisionally damped. (2) Deuterium-tritium fuel was imploded to a density of 20 g/cm 3 and a pressure of 10 10 atm. (3) A 700-fold amplification of soft x rays by stimulated emission at 206 and 209 A (62 eV) from Se +24 ions was observed in a laser-generated plasma. Isoelectronic scaling to 155 A (87 eV) in Y +29 was also demonstrated

  16. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  17. High gradient experiment by accelerator test facility for Japan Linear Collider

    International Nuclear Information System (INIS)

    Takeda, Seishi; Akemoto, Mitsuo; Hayano, Hitoshi; Naito, Takashi; Matsumoto, Hiroshi

    1991-01-01

    For the e + e - linear colliders in TeV energy region such as the Japan Linear Collider (JLC), the accelerating gradient will be one of the important parameters affecting the over all design of main linacs. The gradient determines the accelerating structures, RF frequencies, peak power, AC power, total length and cost. High gradient experiment by using a traveling wave structure in S-band frequencies is presented. Discussions are given about the dependence of dark current and structure length. As one of the parameters indicating the quality of the structure, the multiplication factor η has been proposed

  18. Development of high power chemical oxygen lodine laser

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Choi, Y. D.; Chung, C. M.; Kim, M. S.; Baik, S. H.; Kwon, S. O.; Park, S. K.; Kim, T. S

    2001-10-01

    This project is directed to construct 10kW Chemical Oxygen Iodine Laser (COIL) for decommissioning of old nuclear facilities, and to get the key technology that can be used for the development of high energy laser weapon. COIL is possible up to MW class in proportion to the amount of chemical reaction. For this reason, high energy laser weapon including Airborne Laser (ABL) and Airborne Tactical Laser (ATL) has been developed as a military use in USA. Recently, many research group have been doing a development study of COIL for nuclear and industrial use in material processing such as cutting and decommissioning by combining laser beam delivery through optical fiber. The Chemical Oxygen Iodine Laser of 6 kW output power has been developed in this project. The main technologies of chemical reaction and supersonic fluid control were developed. This technology can be applied for construction of 10 kW laser system. This laser can be used for old nuclear facilities and heavy industry by combining laser beam delivery through optical fiber. The development of High Energy Laser (HEL) weapon is necessary as a military use, and we conclude that Airborne Tactical Laser should be developed in our country.

  19. Tunable high-gradient permanent magnet quadrupoles

    CERN Document Server

    Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

    2014-01-01

    A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

  20. High gradient accelerators for linear light sources

    International Nuclear Information System (INIS)

    Barletta, W.A.

    1988-01-01

    Ultra-high gradient radio frequency linacs powered by relativistic klystrons appear to be able to provide compact sources of radiation at XUV and soft x-ray wavelengths with a duration of 1 picosecond or less. This paper provides a tutorial review of the physics applicable to scaling the present experience of the accelerator community to the regime applicable to compact linear light sources. 22 refs., 11 figs., 21 tabs

  1. Overview on the high power excimer laser technology

    Science.gov (United States)

    Liu, Jingru

    2013-05-01

    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  2. High-powered CO2 -lasers and noise control

    Science.gov (United States)

    Honkasalo, Antero; Kuronen, Juhani

    High-power CO2 -lasers are being more and more widely used for welding, drilling and cutting in machine shops. In the near future, different kinds of surface treatments will also become routine practice with laser units. The industries benefitting most from high power lasers will be: the automotive industry, shipbuilding, the offshore industry, the aerospace industry, the nuclear and the chemical processing industries. Metal processing lasers are interesting from the point of view of noise control because the working tool is a laser beam. It is reasonable to suppose that the use of such laser beams will lead to lower noise levels than those connected with traditional metal processing methods and equipment. In the following presentation, the noise levels and possible noise-control problems attached to the use of high-powered CO2 -lasers are studied.

  3. Prospects of the high power iodine laser

    International Nuclear Information System (INIS)

    Hohla, K.; Brederlow, G.; Fill, E.; Volk, R.; Witte, K.J.

    1976-09-01

    The characteristic properties of the iodine laser (gaseous laser substance, photolytic pump mechanism, variable stimulated emission cross-section) made it possible in a relatively short time to generate ns pulses in the kJ range. The Asterix II and III iodine laser systems at IPP are working successfully, and the question arises what prospects are afforded for further iodine laser development. What are the problems that have to be clarified in order to build 10 or 100 kJ systems for laser fusion experiments. According to our experience these can be classified as follows: 1) Short pulse generation and contrast ratio, 2) pulse shaping in a high-gain laser and amplification in the coherent time range, 3) non-linear properties at high intensities, 4) scalable pumping schemes and chemical processes. (orig./WL) [de

  4. A plasma microlens for ultrashort high power lasers

    Science.gov (United States)

    Katzir, Yiftach; Eisenmann, Shmuel; Ferber, Yair; Zigler, Arie; Hubbard, Richard F.

    2009-07-01

    We present a technique for generation of miniature plasma lens system that can be used for focusing and collimating a high intensity femtosecond laser pulse. The plasma lens was created by a nanosecond laser, which ablated a capillary entrance. The spatial configuration of the ablated plasma focused a high intensity femtosecond laser pulse. This configuration offers versatility in the plasma lens small f-number for extremely tight focusing of high power lasers with no damage threshold restrictions of regular optical components.

  5. A plasma microlens for ultrashort high power lasers

    International Nuclear Information System (INIS)

    Katzir, Yiftach; Eisenmann, Shmuel; Ferber, Yair; Zigler, Arie; Hubbard, Richard F.

    2009-01-01

    We present a technique for generation of miniature plasma lens system that can be used for focusing and collimating a high intensity femtosecond laser pulse. The plasma lens was created by a nanosecond laser, which ablated a capillary entrance. The spatial configuration of the ablated plasma focused a high intensity femtosecond laser pulse. This configuration offers versatility in the plasma lens small f-number for extremely tight focusing of high power lasers with no damage threshold restrictions of regular optical components.

  6. High-power laser diodes with high polarization purity

    Science.gov (United States)

    Rosenkrantz, Etai; Yanson, Dan; Peleg, Ophir; Blonder, Moshe; Rappaport, Noam; Klumel, Genady

    2017-02-01

    Fiber-coupled laser diode modules employ power scaling of single emitters for fiber laser pumping. To this end, techniques such as geometrical, spectral and polarization beam combining (PBC) are used. For PBC, linear polarization with high degree of purity is important, as any non-perfectly polarized light leads to losses and heating. Furthermore, PBC is typically performed in a collimated portion of the beams, which also cancels the angular dependence of the PBC element, e.g., beam-splitter. However, we discovered that single emitters have variable degrees of polarization, which depends both on the operating current and far-field divergence. We present data to show angle-resolved polarization measurements that correlate with the ignition of high-order modes in the slow-axis emission of the emitter. We demonstrate that the ultimate laser brightness includes not only the standard parameters such as power, emitting area and beam divergence, but also the degree of polarization (DoP), which is a strong function of the latter. Improved slow-axis divergence, therefore, contributes not only to high brightness but also high beam combining efficiency through polarization.

  7. High-energy 4ω probe laser for laser-plasma experiments at Nova

    International Nuclear Information System (INIS)

    Glenzer, S.H.; Weiland, T.L.; Bower, J.; MacKinnon, A.J.; MacGowan, B.J.

    1999-01-01

    For the characterization of inertial confinement fusion plasmas, we implemented a high-energy 4ω probe laser at the Nova laser facility. A total energy of >50 J at 4ω, a focal spot size of order 100 μm, and a pointing accuracy of 100 μm was demonstrated for target shots. This laser provides intensities of up to 3x10 14 Wcm -2 and therefore fulfills high-power requirements for laser-plasma interaction experiments. The 4ω probe laser is now routinely used for Thomson scattering. Successful experiments were performed in gas-filled hohlraums at electron densities of n e >2x10 21 cm -3 which represents the highest density plasma so far being diagnosed with Thomson scattering. copyright 1999 American Institute of Physics

  8. Metallicity gradient of the thick disc progenitor at high redshift

    Science.gov (United States)

    Kawata, Daisuke; Allende Prieto, Carlos; Brook, Chris B.; Casagrande, Luca; Ciucă, Ioana; Gibson, Brad K.; Grand, Robert J. J.; Hayden, Michael R.; Hunt, Jason A. S.

    2018-01-01

    We have developed a novel Markov Chain Monte Carlo chemical 'painting' technique to explore possible radial and vertical metallicity gradients for the thick disc progenitor. In our analysis, we match an N-body simulation to the data from the Apache Point Observatory Galactic Evolution Experiment survey. We assume that the thick disc has a constant scaleheight and has completed its formation at an early epoch, after which time radial mixing of its stars has taken place. Under these assumptions, we find that the initial radial metallicity gradient of the thick disc progenitor should not be negative, but either flat or even positive, to explain the current negative vertical metallicity gradient of the thick disc. Our study suggests that the thick disc was built-up in an inside-out and upside-down fashion, and older, smaller and thicker populations are more metal poor. In this case, star-forming discs at different epochs of the thick disc formation are allowed to have different radial metallicity gradients, including a negative one, which helps to explain a variety of slopes observed in high-redshift disc galaxies. This scenario helps to explain the positive slope of the metallicity-rotation velocity relation observed for the Galactic thick disc. On the other hand, radial mixing flattens the slope of an existing gradient.

  9. High-gradient normal-conducting RF structures for muon cooling channels

    International Nuclear Information System (INIS)

    Corlett, J.N.; Green, M.A.; Hartman, N.; Ladran, A.; Li, D.; MacGill, R.; Rimmer, R.; Moretti, A.; Jurgens, T.; Holtkamp, N.; Black, E.; Summers, D.; Booke, M.

    2001-01-01

    We present a status report on the research and development of high-gradient normal-conducting RF structures for the ionization cooling of muons in a neutrino factory or muon collider. High-gradient RF structures are required in regions enclosed in strong focusing solenoidal magnets, precluding the application of superconducting RF technology [1]. We propose using linear accelerating structures, with individual cells electromagnetically isolated, to achieve the required gradients of over 15 MV/m at 201 MHz and 30 MV/m at 805 MHz. Each cell will be powered independently, and cell length and drive phase adjusted to optimize shunt impedance of the assembled structure. This efficient design allows for relatively small field enhancement on the structure walls, and an accelerating field approximately 1.7 times greater than the peak surface field. The electromagnetic boundary of each cell may be provided by a thin Be sheet, or an assembly of thin-walled metal tubes. Use of thin, low-Z materials will allow passage of the muon beams without significant deterioration in beam quality due to scattering. R and D in design and analysis of robust structures that will operate under large electric and magnetic fields and RF current heating are discussed, including the experimental program based in a high-power test laboratory developed for this purpose

  10. Staging laser plasma accelerators for increased beam energy

    International Nuclear Information System (INIS)

    Panasenko, Dmitriy; Shu, Anthony; Schroeder, Carl; Gonsalves, Anthony; Nakamura, Kei; Matlis, Nicholas; Cormier-Michel, Estelle; Plateau, Guillaume; Lin, Chen; Toth, Csaba; Geddes, Cameron; Esarey, Eric; Leemans, Wim

    2008-01-01

    Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10m, resulting in decreased average accelerating gradient and complicated e-beam transport. In this paper we use basic scaling laws to show that the total length of future laser plasma accelerators will be determined by staging technology. We also propose using a liquid jet plasma mirror for in-coupling the laser beam and show that it has the potential to reduce distance between stages to the cm-scale.

  11. High gradient magnetic separation applied to environmental remediation

    International Nuclear Information System (INIS)

    Prenger, F.C.; Stewart, W.F.; Hill, D.D.; Avens, L.R.; Worl, L.A.; Schake, A.; de Aguero, K.J.; Padilla, D.D.; Tolt, T.L.

    1993-01-01

    High Gradient Magnetic Separation (HGMS) is an application of superconducting magnet technology to the separation of magnetic solids from other solids, liquids, or gases. The production of both high magnetic fields (>4 T) and large field gradients using superconducting magnet technology has made it possible to separate a previously unreachable but large family of paramagnetic materials. This is a powerful technique that can be used to separate widely dispersed contaminants from a host material and may be the only technique available for separating material in the colloidal state. Because it is a physical separation process, no additional waste is generated. We are applying this technology to the treatment of radioactive wastes for environmental remediation. We have conducted tests examining slurries containing nonradioactive, magnetic surrogates. Results from these studies were used to verify our analytical model of the separation process. The model describes the rate process for magnetic separation and is based on a force balance on the paramagnetic species. This model was used to support bench scale experiments and prototype separator design

  12. A proof of principle experiment of laser wakefield accelerator

    International Nuclear Information System (INIS)

    Nakajima, K.; Enomoto, A.; Nakanishi, H.; Ogata, A.; Kato, Y.; Kitagawa, Y.; Mima, K.; Shiraga, H.; Yamakawa, K.; Downer, M.; Horton, W.; Newberger, B.; Tajima, T.

    1992-01-01

    Ultrashort super-intense lasers allow us to test a principle of the laser wakefield particle acceleration. The peak power of 30 TW and the pulse width of 1 ps produced by the Nd:glass laser system is capable of creating a highly-ionized plasma of a moderate density gas in an ultrafast time scale and generating a large amplitude plasma wave with the accelerating gradient of 2.5 GeV/m. Particle acceleration can be demonstrated by injecting a few MeV electrons emitted from a solid target by intense laser irradiation. (Author) 2 figs., 5 refs

  13. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.

    2005-01-01

    Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

  14. Design Studies of Nb3Sn High-Gradient Quadrupole Models for LARP

    International Nuclear Information System (INIS)

    Andreev, Nikolai; Caspi, Shlomo; Dietderich, Daniel; Ferracin, Paolo; Ghosh, Arup; Kashikhin, Vadim; Lietzke, Al; Novitski, Igor; Zlobin, Alexander; McInturff, Alfred; Sabbi, GianLuca

    2007-01-01

    Insertion quadrupoles with large aperture and high gradient are required to achieve the luminosity upgrade goal of 10 35 cm -2 s -1 at the Large Hadron Collider (LHC). In 2004, the US Department of Energy established the LHC Accelerator Research Program (LARP) to develop a technology base for the upgrade. Nb 3 Sn conductor is required in order to operate at high field and with sufficient temperature margin. We report here on the conceptual design studies of a series of 1 m long 'High-gradient Quadrupoles' (HQ) that will explore the magnet performance limits in terms of peak fields, forces and stresses. The HQ design is expected to provide coil peak fields of more than 15 T, corresponding to gradients above 300 T/m in a 90 mm bore. Conductor requirements, magnetic, mechanical and quench protection issues for candidate HQ designs will be presented and discussed

  15. Extremely-high vacuum pressure measurement by laser ionization

    International Nuclear Information System (INIS)

    Kokubun, Kiyohide

    1991-01-01

    Laser ionization method has the very high sensitivity for detecting atoms and molecules. Hurst et al. successfully detected a single Cs atom by means of resonance ionization spectroscopy developed by them. Noting this high sensitivity, the authors have attempted to apply the laser ionization method to measure gas pressure, particularly in the range down to extremely high vacuum. At present, hot cathode ionization gauges are used for measuring gas pressure down to ultrahigh vacuum, however, those have a number of disadvantages. The pressure measurement using lasers does not have such disadvantages. The pressure measurement utilizing the laser ionization method is based on the principle that when laser beam is focused through a lens, the amount of atom or molecule ions generated in the focused space region is proportional to gas pressure. In this paper, the experimental results are presented on the nonresonant multiphoton ionization characteristics of various kinds of gases, the ion detection system with high sensitivity and an extremely high vacuum system prepared for the laser ionization experiment. (K.I.)

  16. New generation of compact high power disk lasers

    Science.gov (United States)

    Feuchtenbeiner, Stefanie; Zaske, Sebastian; Schad, Sven-Silvius; Gottwald, Tina; Kuhn, Vincent; Kumkar, Sören; Metzger, Bernd; Killi, Alexander; Haug, Patrick; Speker, Nicolai

    2018-02-01

    New technological developments in high power disk lasers emitting at 1030 nm are presented. These include the latest generation of TRUMPF's TruDisk product line offering high power disk lasers with up to 6 kW output power and beam qualities of up to 4 mm*mrad. With these compact devices a footprint reduction of 50% compared to the previous model could be achieved while at the same time improving robustness and increasing system efficiency. In the context of Industry 4.0, the new generation of TruDisk lasers features a synchronized data recording of all sensors, offering high-quality data for virtual analyses. The lasers therefore provide optimal hardware requirements for services like Condition Monitoring and Predictive Maintenance. We will also discuss its innovative and space-saving cooling architecture. It allows operation of the laser under very critical ambient conditions. Furthermore, an outlook on extending the new disk laser platform to higher power levels will be given. We will present a disk laser with 8 kW laser power out of a single disk with a beam quality of 5 mm*mrad using a 125 μm fiber, which makes it ideally suited for cutting and welding applications. The flexibility of the disk laser platform also enables the realization of a wide variety of beam guiding setups. As an example a new scheme called BrightLine Weld will be discussed. This technology allows for an almost spatter free laser welding process, even at high feed rates.

  17. Laser additive manufacturing of high-performance materials

    CERN Document Server

    Gu, Dongdong

    2015-01-01

    This book entitled “Laser Additive Manufacturing of High-Performance Materials” covers the specific aspects of laser additive manufacturing of high-performance new materials components based on an unconventional materials incremental manufacturing philosophy, in terms of materials design and preparation, process control and optimization, and theories of physical and chemical metallurgy. This book describes the capabilities and characteristics of the development of new metallic materials components by laser additive manufacturing process, including nanostructured materials, in situ composite materials, particle reinforced metal matrix composites, etc. The topics presented in this book, similar as laser additive manufacturing technology itself, show a significant interdisciplinary feature, integrating laser technology, materials science, metallurgical engineering, and mechanical engineering. This is a book for researchers, students, practicing engineers, and manufacturing industry professionals interested i...

  18. High-performance OPCPA laser system

    International Nuclear Information System (INIS)

    Zuegel, J.D.; Bagnoud, V.; Bromage, J.; Begishev, I.A.; Puth, J.

    2006-01-01

    Optical parametric chirped-pulse amplification (OPCPA) is ideally suited for amplifying ultra-fast laser pulses since it provides broadband gain across a wide range of wavelengths without many of the disadvantages of regenerative amplification. A high-performance OPCPA system has been demonstrated as a prototype for the front end of the OMEGA Extended Performance (EP) Laser System. (authors)

  19. High-performance OPCPA laser system

    Energy Technology Data Exchange (ETDEWEB)

    Zuegel, J.D.; Bagnoud, V.; Bromage, J.; Begishev, I.A.; Puth, J. [Rochester Univ., Lab. for Laser Energetics, NY (United States)

    2006-06-15

    Optical parametric chirped-pulse amplification (OPCPA) is ideally suited for amplifying ultra-fast laser pulses since it provides broadband gain across a wide range of wavelengths without many of the disadvantages of regenerative amplification. A high-performance OPCPA system has been demonstrated as a prototype for the front end of the OMEGA Extended Performance (EP) Laser System. (authors)

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  1. High power diode lasers converted to the visible

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Andersen, Peter E.

    2017-01-01

    High power diode lasers have in recent years become available in many wavelength regions. However, some spectral regions are not well covered. In particular, the visible spectral range is lacking high power diode lasers with good spatial quality. In this paper, we highlight some of our recent...... results in nonlinear frequency conversion of high power near infrared diode lasers to the visible spectral region....

  2. Atmospheric Propagation and Combining of High-Power Lasers

    Science.gov (United States)

    2015-09-08

    Brightness-scaling potential of actively phase- locked solid state laser arrays,” IEEE J. Sel. Topics Quantum Electron., vol. 13, no. 3, pp. 460–472, May...attempting to phase- lock high-power lasers, which is not encountered when phase- locking low-power lasers, for example mW power levels. Regardless, we...technology does not currently exist. This presents a challenging problem when attempting to phase- lock high-power lasers, which is not encountered when

  3. Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

    2004-01-01

    Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

  4. Characterization of High-power Quasi-cw Laser Diode Arrays

    Science.gov (United States)

    Stephen, Mark A.; Vasilyev, Aleksey; Troupaki, Elisavet; Allan, Graham R.; Kashem, Nasir B.

    2005-01-01

    NASA s requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

  5. Department of Defense high power laser program guidance

    Science.gov (United States)

    Muller, Clifford H.

    1994-06-01

    The DoD investment of nominally $200 million per year is focused on four high power laser (HPL) concepts: Space-Based Laser (SBL), a Ballistic Missile Defense Organization effort that addresses boost-phase intercept for Theater Missile Defense and National Missile Defense; Airborne Laser (ABL), an Air Force effort that addresses boost-phase intercept for Theater Missile Defense; Ground-Based Laser (GBL), an Air Force effort addressing space control; and Anti-Ship Missile Defense (ASMD), a Navy effort addressing ship-based defense. Each organization is also supporting technology development with the goal of achieving less expensive, brighter, and lighter high power laser systems. These activities represent the building blocks of the DoD program to exploit the compelling characteristics of the high power laser. Even though DoD's HPL program are focused and moderately strong, additional emphasis in a few technical areas could help reduce risk in these programs. In addition, a number of options are available for continuing to use the High-Energy Laser System Test Facility (HELSTF) at White Sands Missile Range. This report provides a brief overview and guidance for the five efforts which comprise the DoD HPL program (SBL, ABL, GBL, ASMD, HELSTF).

  6. Sandia high-power atomic iodine photodissociation laser

    International Nuclear Information System (INIS)

    Palmer, R.E.; Padrick, T.D.

    1975-01-01

    One of the more promising candidates for a laser to demonstrate the feasibility of laser fusion is the 1.315 μ atomic iodine laser. In a relatively short time it has been developed into a viable subnanosecond, high energy laser. Although at present the iodine laser cannot equal the output capabilities of a large Nd:glass laser system, there are no foreseeable obstacles in the construction of a 100 psec, 10 KJ or greater atomic iodine laser system. A 100 joule system being constructed at Sandia to investigate many of the scaling parameters essential to the design of a 10 KJ or greater system is described. (U.S.)

  7. Stimulated Raman backscattering at high laser intensities

    Energy Technology Data Exchange (ETDEWEB)

    Skoric, M M [Vinca Inst. of Nuclear Sciences, Belgrade (Yugoslavia); Tajima, Toshiki; Sasaki, Akira; Maluckov, A; Jovanovic, M

    1998-03-01

    Signatures of Stimulated Raman backscattering of a short-pulse high-intensity laser interacting with an underdense plasma are discussed. We introduce a nonlinear three-wave interaction model that accounts for laser pump depletion and relativistic detuning. A mechanism is revealed based on a generic route to chaos, that predicts a progressive increase of the backscatter complexity with a growing laser intensity. Importance of kinetic effects is outlined and demonstrated in fluid-hybrid and particle simulations. As an application, we show that spectral anomalies of the backscatter, predicted by the above model, are consistent with recent sub-picosecond, high-intensity laser gas-target measurements at Livermore and elsewhere. Finally, a recently proposed scheme for generation of ultra-short, low-prepulse laser pulses by Raman backscattering in a thin foil target, is shown. (author)

  8. High-average-power solid state lasers

    International Nuclear Information System (INIS)

    Summers, M.A.

    1989-01-01

    In 1987, a broad-based, aggressive R ampersand D program aimed at developing the technologies necessary to make possible the use of solid state lasers that are capable of delivering medium- to high-average power in new and demanding applications. Efforts were focused along the following major lines: development of laser and nonlinear optical materials, and of coatings for parasitic suppression and evanescent wave control; development of computational design tools; verification of computational models on thoroughly instrumented test beds; and applications of selected aspects of this technology to specific missions. In the laser materials areas, efforts were directed towards producing strong, low-loss laser glasses and large, high quality garnet crystals. The crystal program consisted of computational and experimental efforts aimed at understanding the physics, thermodynamics, and chemistry of large garnet crystal growth. The laser experimental efforts were directed at understanding thermally induced wave front aberrations in zig-zag slabs, understanding fluid mechanics, heat transfer, and optical interactions in gas-cooled slabs, and conducting critical test-bed experiments with various electro-optic switch geometries. 113 refs., 99 figs., 18 tabs

  9. Laser-driven acceleration with Bessel beam

    International Nuclear Information System (INIS)

    Imasaki, Kazuo; Li, Dazhi

    2005-01-01

    A new approach of laser-driven acceleration with Bessel beam is described. Bessel beam, in contrast to the Gaussian beam, shows diffraction-free'' characteristics in its propagation, which implies potential in laser-driven acceleration. But a normal laser, even if the Bessel beam, laser can not accelerate charged particle efficiently because the difference of velocity between the particle and photon makes cyclic acceleration and deceleration phase. We proposed a Bessel beam truncated by a set of annular slits those makes several special regions in its travelling path, where the laser field becomes very weak and the accelerated particles are possible to receive no deceleration as they undergo decelerating phase. Thus, multistage acceleration is realizable with high gradient. In a numerical computation, we have shown the potential of multistage acceleration based on a three-stage model. (author)

  10. High-gradient compact linear accelerator

    Science.gov (United States)

    Carder, Bruce M.

    1998-01-01

    A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

  11. Transient Plasma Photonic Crystals for High-Power Lasers.

    Science.gov (United States)

    Lehmann, G; Spatschek, K H

    2016-06-03

    A new type of transient photonic crystals for high-power lasers is presented. The crystal is produced by counterpropagating laser beams in plasma. Trapped electrons and electrically forced ions generate a strong density grating. The lifetime of the transient photonic crystal is determined by the ballistic motion of ions. The robustness of the photonic crystal allows one to manipulate high-intensity laser pulses. The scheme of the crystal is analyzed here by 1D Vlasov simulations. Reflection or transmission of high-power laser pulses are predicted by particle-in-cell simulations. It is shown that a transient plasma photonic crystal may act as a tunable mirror for intense laser pulses. Generalizations to 2D and 3D configurations are possible.

  12. Laser-powered dielectric-structures for the production of high-brightness electron and x-ray beams

    Science.gov (United States)

    Travish, Gil; Yoder, Rodney B.

    2011-05-01

    Laser powered accelerators have been under intensive study for the past decade due to their promise of high gradients and leveraging of rapid technological progress in photonics. Of the various acceleration schemes under examination, those based on dielectric structures may enable the production of relativistic electron beams in breadbox sized systems. When combined with undulators having optical-wavelength periods, these systems could produce high brilliance x-rays which find application in, for instance, medical and industrial imaging. These beams also may open the way for table-top atto-second sciences. Development and testing of these dielectric structures faces a number of challenges including complex beam dynamics, new demands on lasers and optical coupling, beam injection schemes, and fabrication. We describe one approach being pursued at UCLA-the Micro Accelerator Platform (MAP). A structure similar to the MAP has also been designed which produces periodic deflections and acts as an undulator for radiation production, and the prospects for this device will be considered. The lessons learned from the multi-year effort to realize these devices will be presented. Challenges remain with acceleration of sub-relativistic beams, focusing, beam phase stability and extension of these devices to higher beam energies. Our progress in addressing these hurdles will be summarized. Finally, the demands on laser technology and optical coupling will be detailed.

  13. Analysis of the electrolyte convection inside the concentration boundary layer during structured electrodeposition of copper in high magnetic gradient fields.

    Science.gov (United States)

    König, Jörg; Tschulik, Kristina; Büttner, Lars; Uhlemann, Margitta; Czarske, Jürgen

    2013-03-19

    To experimentally reveal the correlation between electrodeposited structure and electrolyte convection induced inside the concentration boundary layer, a highly inhomogeneous magnetic field, generated by a magnetized Fe-wire, has been applied to an electrochemical system. The influence of Lorentz and magnetic field gradient force to the local transport phenomena of copper ions has been studied using a novel two-component laser Doppler velocity profile sensor. With this sensor, the electrolyte convection within 500 μm of a horizontally aligned cathode is presented. The electrode-normal two-component velocity profiles below the electrodeposited structure show that electrolyte convection is induced and directed toward the rim of the Fe-wire. The measured deposited structure directly correlates to the observed boundary layer flow. As the local concentration of Cu(2+) ions is enhanced due to the induced convection, maximum deposit thicknesses can be found at the rim of the Fe-wire. Furthermore, a complex boundary layer flow structure was determined, indicating that electrolyte convection of second order is induced. Moreover, the Lorentz force-driven convection rapidly vanishes, while the electrolyte convection induced by the magnetic field gradient force is preserved much longer. The progress for research is the first direct experimental proof of the electrolyte convection inside the concentration boundary layer that correlates to the deposited structure and reveals that the magnetic field gradient force is responsible for the observed structuring effect.

  14. Laser cutting: industrial relevance, process optimization, and laser safety

    Science.gov (United States)

    Haferkamp, Heinz; Goede, Martin; von Busse, Alexander; Thuerk, Oliver

    1998-09-01

    Compared to other technological relevant laser machining processes, up to now laser cutting is the application most frequently used. With respect to the large amount of possible fields of application and the variety of different materials that can be machined, this technology has reached a stable position within the world market of material processing. Reachable machining quality for laser beam cutting is influenced by various laser and process parameters. Process integrated quality techniques have to be applied to ensure high-quality products and a cost effective use of the laser manufacturing plant. Therefore, rugged and versatile online process monitoring techniques at an affordable price would be desirable. Methods for the characterization of single plant components (e.g. laser source and optical path) have to be substituted by an omnivalent control system, capable of process data acquisition and analysis as well as the automatic adaptation of machining and laser parameters to changes in process and ambient conditions. At the Laser Zentrum Hannover eV, locally highly resolved thermographic measurements of the temperature distribution within the processing zone using cost effective measuring devices are performed. Characteristic values for cutting quality and plunge control as well as for the optimization of the surface roughness at the cutting edges can be deducted from the spatial distribution of the temperature field and the measured temperature gradients. Main influencing parameters on the temperature characteristic within the cutting zone are the laser beam intensity and pulse duration in pulse operation mode. For continuous operation mode, the temperature distribution is mainly determined by the laser output power related to the cutting velocity. With higher cutting velocities temperatures at the cutting front increase, reaching their maximum at the optimum cutting velocity. Here absorption of the incident laser radiation is drastically increased due to

  15. Optical engineering for high power laser applications

    International Nuclear Information System (INIS)

    Novaro, M.

    1993-01-01

    Laser facilities for Inertial Confinement Fusion (I.C.F.) experiments require laser and X ray optics able to withstand short pulse conditions. After a brief recall of high power laser system arrangements and of the characteristics of their optics, the authors will present some X ray optical developments

  16. SLAC High Gradient Testing of a KEK X-Band Accelerator Structure

    International Nuclear Information System (INIS)

    Loewen, Rod

    2000-01-01

    The high accelerating gradients required for future linear colliders demands a better study of field emission and RF breakdown in accelerator structures. Changes in structure geometry, vacuum pumping, fabrication methods, and surface finish can all potentially impact the conditioning process, dark current emission, and peak RF power handling capability. Recent tests at SLAC of KEK's ''M2'' travelling wave x-band accelerator section provides an opportunity to investigate some of these effects by comparing its performance to previously high power tested structures at SLAC. In addition to studying ultimate power limitations, this test also demonstrates the use of computer automated conditioning to reach practical, achievable gradients

  17. Latest advances in high brightness disk lasers

    Science.gov (United States)

    Kuhn, Vincent; Gottwald, Tina; Stolzenburg, Christian; Schad, Sven-Silvius; Killi, Alexander; Ryba, Tracey

    2015-02-01

    In the last decade diode pumped solid state lasers have become an important tool for many industrial materials processing applications. They combine ease of operation with efficiency, robustness and low cost. This paper will give insight in latest progress in disk laser technology ranging from kW-class CW-Lasers over frequency converted lasers to ultra-short pulsed lasers. The disk laser enables high beam quality at high average power and at high peak power at the same time. The power from a single disk was scaled from 1 kW around the year 2000 up to more than 10 kW nowadays. Recently was demonstrated more than 4 kW of average power from a single disk close to fundamental mode beam quality (M²=1.38). Coupling of multiple disks in a common resonator results in even higher power. As an example we show 20 kW extracted from two disks of a common resonator. The disk also reduces optical nonlinearities making it ideally suited for short and ultrashort pulsed lasers. In a joint project between TRUMPF and IFSW Stuttgart more than 1.3 kW of average power at ps pulse duration and exceptionally good beam quality was recently demonstrated. The extremely low saturated gain makes the disk laser ideal for internal frequency conversion. We show >1 kW average power and >6 kW peak power in multi ms pulsed regime from an internally frequency doubled disk laser emitting at 515 nm (green). Also external frequency conversion can be done efficiently with ns pulses. >500 W of average UV power was demonstrated.

  18. Laser acceleration in vacuum with an open iris-loaded waveguide

    International Nuclear Information System (INIS)

    Xie, Ming

    1997-05-01

    An open iris-loaded waveguide structure is considered for laser acceleration of highly relativistic particle in vacuum. Complete characterization of all eigenmodes are given in analytical form for the structure. In particular the dominant radially polarized TM mode is evaluated in detail for laser acceleration. The entire parameter space is searched and it is found that below the laser damage threshold of the structure an acceleration gradient around 1 GV/m can be obtained over a phase slippage length of 10s of cm with TWs laser in the wavelength range from 1 to 10 μm

  19. High repetition rate, high energy, actively Q-switched all-in-fiber laser

    Science.gov (United States)

    Lecourt, J. B.; Bertrand, A.; Guillemet, S.; Hernandez, Y.; Giannone, D.

    2010-05-01

    We report an actively Q-switched Ytterbium-doped all-in-fibre laser delivering 10ns pulses with high repetition rate (from 100kHz to 1MHz). The laser operation has been validated at three different wavelengths (1040, 1050 and 1064nm). The laser can deliver up to 20Watts average power with an high beam quality (M2 = 1).

  20. High-power fiber lasers for photocathode electron injectors

    Directory of Open Access Journals (Sweden)

    Zhi Zhao

    2014-05-01

    Full Text Available Many new applications for electron accelerators require high-brightness, high-average power beams, and most rely on photocathode-based electron injectors as a source of electrons. To achieve such a photoinjector, one requires both a high-power laser system to produce the high average current beam, and also a system at reduced repetition rate for electron beam diagnostics to verify high beam brightness. Here we report on two fiber laser systems designed to meet these specific needs, at 50 MHz and 1.3 GHz repetition rate, together with pulse pickers, second harmonic generation, spatiotemporal beam shaping, intensity feedback, and laser beam transport. The performance and flexibility of these laser systems have allowed us to demonstrate electron beam with both low emittance and high average current for the Cornell energy recovery linac.

  1. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

    2018-02-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  2. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

    2018-01-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  3. High-throughput machining using a high-average power ultrashort pulse laser and high-speed polygon scanner

    Science.gov (United States)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

    2016-09-01

    High-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (aluminum, copper, and stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high-average power picosecond laser in conjunction with a unique, in-house developed polygon mirror-based biaxial scanning system. Therefore, different concepts of polygon scanners are engineered and tested to find the best architecture for high-speed and precision laser beam scanning. In order to identify the optimum conditions for efficient processing when using high-average laser powers, the depths of cavities made in the samples by varying the processing parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. For overlapping pulses of optimum fluence, the removal rate is as high as 27.8 mm3/min for aluminum, 21.4 mm3/min for copper, 15.3 mm3/min for stainless steel, and 129.1 mm3/min for Al2O3, when a laser beam of 187 W average laser powers irradiates. On stainless steel, it is demonstrated that the removal rate increases to 23.3 mm3/min when the laser beam is very fast moving. This is thanks to the low pulse overlap as achieved with 800 m/s beam deflection speed; thus, laser beam shielding can be avoided even when irradiating high-repetitive 20-MHz pulses.

  4. High Energy Density Sciences with High Power Lasers at SACLA

    Science.gov (United States)

    Kodama, Ryosuke

    2013-10-01

    One of the interesting topics on high energy density sciences with high power lasers is creation of extremely high pressures in material. The pressures of more than 0.1 TPa are the energy density corresponding to the chemical bonding energy, resulting in expectation of dramatic changes in the chemical reactions. At pressures of more than TPa, most of material would be melted on the shock Hugoniot curve. However, if the temperature is less than 1eV or lower than a melting point at pressures of more than TPa, novel solid states of matter must be created through a pressured phase transition. One of the interesting materials must be carbon. At pressures of more than TPa, the diamond structure changes to BC and cubic at more than 3TPa. To create such novel states of matter, several kinds of isentropic-like compression techniques are being developed with high power lasers. To explore the ``Tera-Pascal Science,'' now we have a new tool which is an x-ray free electron laser as well as high power lasers. The XFEL will clear the details of the HED states and also efficiently create hot dense matter. We have started a new project on high energy density sciences using an XFEL (SACLA) in Japan, which is a HERMES (High Energy density Revolution of Matter in Extreme States) project.

  5. High-Power Lasers for Science and Society

    Energy Technology Data Exchange (ETDEWEB)

    Siders, C. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Haefner, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-05

    Since the first demonstration of the laser in 1960 by Theodore Maiman at Hughes Research Laboratories, the principal defining characteristic of lasers has been their ability to focus unprecedented powers of light in space, time, and frequency. High-power lasers have, over the ensuing five and a half decades, illuminated entirely new fields of scientific endeavor as well as made a profound impact on society. While the United States pioneered lasers and their early applications, we have been eclipsed in the past decade by highly effective national and international networks in both Europe and Asia, which have effectively focused their energies, efforts, and resources to achieve greater scientific and societal impact. This white paper calls for strategic investment which, by striking an appropriate balance between distributing our precious national funds and establishing centers of excellence, will ensure a broad pipeline of people and transformative ideas connecting our world-leading universities, defining flagship facilities stewarded by our national laboratories, and driving innovation across industry, to fully exploit the potential of high-power lasers.

  6. Stimulated Brillouin backscattering and magnetic field generation in laser-produced plasmas

    International Nuclear Information System (INIS)

    Bawa'aneh, M.S.

    1999-01-01

    This thesis is concerned with aspects of laser-plasma interactions related to fusion reactions; in particular thermoelectric magnetic field generation around a hole dug in plasma by intense laser beams, and stimulated Brillouin back scattering (SBBS) from plasmas containing hot spots. A hole, of the size of the laser focal spot, is dug in the plasma when illuminated by intense laser if the laser pressure exceeds the plasma thermal pressure. This hole is found to have steep, radial density gradients. My first concern arose from the prediction that magnetic fields might be generated around the hole-plasma interface in places where the steep density gradients overlap with the non-aligned temperature gradients. When a high-power laser beam is focused on a solid pellet, plasma is formed at the surface. In order to create conditions for thermonuclear reactions in the interior of the pellet, an effective deposition of the laser energy to thermal energy of the pellet via laser-plasma coupling is necessary. When light irradiates a plasma collective processes occur, which can either enhance or reduce the light absorption. For a better understanding of the fusion problem a knowledge of the nature of these collective processes and of the fraction of light reflected from the plasma modes is required. Local hot spots seen experimentally lead to higher gain levels of scattered light. These local temperature inhomogeneities could lead to non-equilibrium distributions, which result in a free energy leading to some interesting phenomena in plasma. In the second part of the thesis stimulated Brillouin back scattering from an ion acoustic mode in a hot spot is studied. Temperature inhomogeneities lead to an ion acoustic instability, and to higher levels of SBBS gain, which leads to lower thresholds for the same electron to ion temperature ratios. This could be the answer for the observed high levels of scattering from hot spots. (author)

  7. Compact and highly efficient laser pump cavity

    Science.gov (United States)

    Chang, Jim J.; Bass, Isaac L.; Zapata, Luis E.

    1999-01-01

    A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

  8. High Energy Solid State Laser Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — A suite of laboratories with advanced spectroscopic and laser equipment, this facility develops materials and techniques for advanced solid state high energy lasers....

  9. High power laser exciter accelerators

    International Nuclear Information System (INIS)

    Martin, T.H.

    1975-01-01

    Recent developments in untriggered oil and water switching now permit the construction of compact, high energy density pulsed power sources for laser excitation. These accelerators, developed principally for electron beam fusion studies, appear adaptable to laser excitation and will provide electron beams of 10 13 to 10 14 W in the next several years. The accelerators proposed for e-beam fusion essentially concentrate the available power from the outside edge of a disk into the central region where the electron beam is formed. One of the main problem areas, that of power flow at the vacuum diode insulator, is greatly alleviated by the multiplicity of electron beams that are allowable for laser excitation. A proposal is made whereby the disk-shaped pulsed power sections are stacked vertically to form a series of radially flowing electron beams to excite the laser gas volume. (auth)

  10. Laser carved micro-crack channels in paper-based dilution devices.

    Science.gov (United States)

    Liu, Qian; Xu, Chaoping; Liang, Heng

    2017-12-01

    We developed novel laser carved micro-crack (LCC) paper-based channels to significantly accelerate the liquid flow without an external pump. For the aqueous solutions they increased the flow velocity 59 times in 16% laser power-8 micro-cracks-LCC channel compared with it in solely-printed channels. All experimental data from both LCC and solely-printed channels were well-fitted by the time-distance quadratic trinomial that we developed on laser power and micro-crack number. We designed and fabricated T-junction microstructures of LCCs. Further, the microfluidic paper-based analytical device (μPAD) of LCC on dye mixing gradient and pH gradient were developed with the characteristics, fast self-acting transportation and high-performance mixing of liquid flows. In the dye mixing gradient the time cost was reduced from 2355s in the solely-printed one to only 123s in the five-stage of this LCC-μPAD. It was useful for quick and long-distance transferences through the multiple units of μPADs. Certainly, this LCC-μPAD was inexpensive, disposable, portable and applicable to resource-limited environments. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Fabrication of high gradient insulators by stack compression

    Science.gov (United States)

    Harris, John Richardson; Sanders, Dave; Hawkins, Steven Anthony; Norona, Marcelo

    2014-04-29

    Individual layers of a high gradient insulator (HGI) are first pre-cut to their final dimensions. The pre-cut layers are then stacked to form an assembly that is subsequently pressed into an HGI unit with the desired dimension. The individual layers are stacked, and alignment is maintained, using a sacrificial alignment tube that is removed after the stack is hot pressed. The HGI's are used as high voltage vacuum insulators in energy storage and transmission structures or devices, e.g. in particle accelerators and pulsed power systems.

  12. Survey on modern pulsed high power lasers

    International Nuclear Information System (INIS)

    Witte, K.J.

    1985-01-01

    The requirements to be met by lasers for particle acceleration are partially similar to those already known for fusion lasers. The power level wanted in both caes is up to 100 TW or even more. The pulse durations favourable for laser accelerators are in the range from 1 ps to 1000 ps whereas fusion lasers require several ns. The energy range for laser accelerators is thus correspondingly smaller than that for fusion lasers: 1-100 kJ versus several 100 kJ. The design criteria of lasers meeting the requirements are discussed in the following. The CO 2 , iodine, Nd:glass and excimer lasers are treated in detail. The high repetition rate aspect will not be particularly addressed since for the present generation of lasers the wanted rates of far above 1 Hz are completely out of scope. Moreover, for the demonstration of principle these rates are not needed. (orig./HSI)

  13. Water Vapour Propulsion Powered by a High-Power Laser-Diode

    Science.gov (United States)

    Minami, Y.; Uchida, S.

    Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

  14. A high gradient test of a single-cell superconducting radio frequency cavity with a feedback waveguide

    Science.gov (United States)

    Kostin, Roman; Avrakhov, Pavel; Kanareykin, Alexei; Solyak, Nikolay; Yakovlev, Vyacheslav; Kazakov, Sergey; Wu, Genfa; Khabiboulline, Timergali; Rowe, Allan; Rathke, John

    2015-09-01

    The most severe problem of the international linear collider (ILC-type) is its high cost, resulting in part from the enormous length of the collider. This length is determined mainly by the achievable accelerating gradient in the RF system of the collider. In current technology, the maximum acceleration gradient in superconducting (SC) structures is determined mainly by the value of the surface RF magnetic field. In order to increase the gradient, a superconducting traveling wave accelerating (STWA) structure is suggested. Utilization of STWA structure with small phase advance per cell for future high energy linear colliders such as ILCs may provide an accelerating gradient 1.2-1.4 times larger [1] than a standing wave structure. However, STWA structure requires a feedback waveguide for power redirecting from the end of the structure back to the front end of accelerating structure. Recent tests of a 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient of a single-cell ILC-type cavity from the same manufacturer [2]. In the present paper, high gradient test results are presented.

  15. Inverse free electron laser accelerator for advanced light sources

    Directory of Open Access Journals (Sweden)

    J. P. Duris

    2012-06-01

    Full Text Available We discuss the inverse free electron laser (IFEL scheme as a compact high gradient accelerator solution for driving advanced light sources such as a soft x-ray free electron laser amplifier or an inverse Compton scattering based gamma-ray source. In particular, we present a series of new developments aimed at improving the design of future IFEL accelerators. These include a new procedure to optimize the choice of the undulator tapering, a new concept for prebunching which greatly improves the fraction of trapped particles and the final energy spread, and a self-consistent study of beam loading effects which leads to an energy-efficient high laser-to-beam power conversion.

  16. Feasibility of High Energy Lasers for Interdiction Activities

    Science.gov (United States)

    2017-12-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS FEASIBILITY OF HIGH ENERGY LASERS FOR INTERDICTION ACTIVITIES by Carlos Abel Javier Romero... ENERGY LASERS FOR INTERDICTION ACTIVITIES 5. FUNDING NUMBERS 6. AUTHOR(S) Carlos Abel Javier Romero Chero 7. PERFORMING ORGANIZATION NAME(S) AND...the people or cargo. High Energy Laser (HEL) weapons are an effective way to deliver energy precisely from a relative long range. This thesis studies

  17. High-Speed Operation of Interband Cascade Lasers

    Science.gov (United States)

    Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Wright, Malcom W.; Farr, William H.; Yang, Rui Q.; Liu, H. C.

    2010-01-01

    Optical sources operating in the atmospheric window of 3-5 microns are of particular interest for the development of free-space optical communication link. It is more advantageous to operate the free-space optical communication link in 3-5-microns atmospheric transmission window than at the telecom wavelength of 1.5 m due to lower optical scattering, scintillation, and background radiation. However, the realization of optical communications at the longer wavelength has encountered significant difficulties due to lack of adequate optical sources and detectors operating in the desirable wavelength regions. Interband Cascade (IC) lasers are novel semiconductor lasers that have a great potential for the realization of high-power, room-temperature optical sources in the 3-5-microns wavelength region, yet no experimental work, until this one, was done on high-speed direct modulation of IC lasers. Here, highspeed interband cascade laser, operating at wavelength 3.0 m, has been developed and the first direct measurement of the laser modulation bandwidth has been performed using a unique, highspeed quantum well infrared photodetector (QWIP). The developed laser has modulation bandwidth exceeding 3 GHz. This constitutes a significant increase of the IC laser modulation bandwidth over currently existing devices. This result has demonstrated suitability of IC lasers as a mid-IR light source for multi-GHz free-space optical communications links

  18. High power lasers & systems

    OpenAIRE

    Chatwin, Chris; Young, Rupert; Birch, Philip

    2015-01-01

    Some laser history;\\ud Airborne Laser Testbed & Chemical Oxygen Iodine Laser (COIL);\\ud Laser modes and beam propagation;\\ud Fibre lasers and applications;\\ud US Navy Laser system – NRL 33kW fibre laser;\\ud Lockheed Martin 30kW fibre laser;\\ud Conclusions

  19. Studies of high repetition rate laser-produced plasma soft-X-ray amplifiers; Etudes d'amplificateurs plasma laser a haute cadence dans le domaine X-UV et applications

    Energy Technology Data Exchange (ETDEWEB)

    Cassou, K

    2006-12-15

    The progress made as well on the Ti:Sa laser system, as in the control and the knowledge of laser produced X-UV sources allowed the construction of a X-UV laser station dedicated to the applications. My thesis work falls under the development of this station and more particularly on the characterization of a X-UV laser plasma amplifier. The experimental study relates to the coupling improvement of the pump infra-red laser with plasma within the framework of the transient collisional X-UV laser generation. These X-UV lasers are generated in a plasma formed by the interaction of a solid target and a laser pulse of approximately 500 ps duration, followed by a second infra-red laser pulse known as of pump (about 5 ps) impinging on the target in grazing incidence. For the first time, a complete parametric study was undertaken on the influence of the grazing angle on the pumping of the amplifying medium. One of the results was to reach very high peak brightness about 10{sup 28} ph/s/mm{sup 2}/mrad{sup 2}/(0.1%bandwidth), which compares well with the free-electron laser brightness. Moreover, we modified then used a new two-dimensional hydrodynamic code with adaptive mesh refinement in order to understand the influence of the space-time properties of the infra-red laser on the formation and the evolution of the amplifying plasma. Our modeling highlighted the interest to use a super Gaussian transverse profile for the line focus leading to an increase in a factor two of the gain region size and a reduction of the electron density gradient by three orders of magnitude. These improvements should strongly increase the energy contained in X-UV laser beam. We thus used X-UV laser to study the appearance of transient defects produced by a laser IR on a beam-splitter rear side. We also began research on the mechanisms of DNA damage induced by a very intense X-UV radiation. (author)

  20. Industrial application of high power disk lasers

    Science.gov (United States)

    Brockmann, Rüdiger; Havrilla, David

    2008-02-01

    Laser welding has become one of the fastest growing areas for industrial laser applications. The increasing cost effectiveness of the laser process is enabled by the development of new highly efficient laser sources, such as the Disk laser, coupled with decreasing cost per Watt. TRUMPF introduced the Disk laser several years ago, and today it has become the most reliable laser tool on the market. The excellent beam quality and output powers of up to 10 kW enable its application in the automotive industry as well as in the range of thick plate welding, such as heavy construction and ship building. This serves as an overview of the most recent developments on the TRUMPF Disk laser and its industrial applications like cutting, welding, remote welding and hybrid welding, too. The future prospects regarding increased power and even further improved productivity and economics are presented.

  1. High power laser downhole cutting tools and systems

    Science.gov (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

    2015-01-20

    Downhole cutting systems, devices and methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena. Systems and devices for the laser cutting operations within a borehole in the earth. These systems and devices can deliver high power laser energy down a deep borehole, while maintaining the high power to perform cutting operations in such boreholes deep within the earth.

  2. Next-generation fiber lasers enabled by high-performance components

    Science.gov (United States)

    Kliner, D. A. V.; Victor, B.; Rivera, C.; Fanning, G.; Balsley, D.; Farrow, R. L.; Kennedy, K.; Hampton, S.; Hawke, R.; Soukup, E.; Reynolds, M.; Hodges, A.; Emery, J.; Brown, A.; Almonte, K.; Nelson, M.; Foley, B.; Dawson, D.; Hemenway, D. M.; Urbanek, W.; DeVito, M.; Bao, L.; Koponen, J.; Gross, K.

    2018-02-01

    Next-generation industrial fiber lasers enable challenging applications that cannot be addressed with legacy fiber lasers. Key features of next-generation fiber lasers include robust back-reflection protection, high power stability, wide power tunability, high-speed modulation and waveform generation, and facile field serviceability. These capabilities are enabled by high-performance components, particularly pump diodes and optical fibers, and by advanced fiber laser designs. We summarize the performance and reliability of nLIGHT diodes, fibers, and next-generation industrial fiber lasers at power levels of 500 W - 8 kW. We show back-reflection studies with up to 1 kW of back-reflected power, power-stability measurements in cw and modulated operation exhibiting sub-1% stability over a 5 - 100% power range, and high-speed modulation (100 kHz) and waveform generation with a bandwidth 20x higher than standard fiber lasers. We show results from representative applications, including cutting and welding of highly reflective metals (Cu and Al) for production of Li-ion battery modules and processing of carbon fiber reinforced polymers.

  3. Modeling of high energy laser ignition of energetic materials

    International Nuclear Information System (INIS)

    Lee, Kyung-cheol; Kim, Ki-hong; Yoh, Jack J.

    2008-01-01

    We present a model for simulating high energy laser heating and ignition of confined energetic materials. The model considers the effect of irradiating a steel plate with long laser pulses and continuous lasers of several kilowatts and the thermal response of well-characterized high explosives for ignition. Since there is enough time for the thermal wave to propagate into the target and to create a region of hot spot in the high explosives, electron thermal diffusion of ultrashort (femto- and picosecond) lasing is ignored; instead, heat diffusion of absorbed laser energy in the solid target is modeled with thermal decomposition kinetic models of high explosives. Numerically simulated pulsed-laser heating of solid target and thermal explosion of cyclotrimethylenetrinitramine, triaminotrinitrobenzene, and octahydrotetranitrotetrazine are compared to experimental results. The experimental and numerical results are in good agreement

  4. High energy XeBr electric discharge laser

    Science.gov (United States)

    Sze, Robert C.; Scott, Peter B.

    1981-01-01

    A high energy XeBr laser for producing coherent radiation at 282 nm. The XeBr laser utilizes an electric discharge as the excitation source to minimize formation of molecular ions thereby minimizing absorption of laser radiation by the active medium. Additionally, HBr is used as the halogen donor which undergoes harpooning reactions with Xe.sub.M * to form XeBr*.

  5. Technology of discharge and laser resonators for high power CO2 lasers. Koshutsuryoku CO2 laser ni tsukawareru hoden reiki laser kyoshinki gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Y.; Kuzumoto, M. (Mitsubishi Electric Corp., Tokyo (Japan))

    1994-03-20

    This paper describes discharge excitation technology and resonator technology as basic technologies for high power CO2 lasers. As a result of progress in high-frequency power element techniques, the discharge excitation technology now generally uses laser excitation using AC discharge of capacity coupling type. Its representative example is silent discharge (SD) excitation. This is a system to excite laser by applying high voltages with as high frequency as 100 kHz to 1 MHz across a pair of electrodes covered with a dielectric material. The system maintains stability in discharge even if power supply voltage amplitude is modulated, and easily provides pulse outputs. Discharge excitation for diffusion cooled type CO2 laser generates a discharge in a gap with a gap length of about 2 mm, and can perform gas cooling by means of thermal conduction of gas, whereas a compact resonator can be fabricated. A resonator for the diffusion cooled type CO2 laser eliminates gas circulation and cooling systems, hence the device can be made more compact. A report has been given that several of these compact resonators were combined, from which a laser output of 85W was obtained by using RF discharge of 2kW. 43 refs., 21 figs.

  6. QED studies using high-power lasers

    International Nuclear Information System (INIS)

    Mattias Marklund

    2010-01-01

    Complete text of publication follows. The event of extreme lasers, which intensities above 10 22 W/cm 2 will be reached on a routine basis, will give us opportunities to probe new aspects of quantum electrodynamics. In particular, the non-trivial properties of the quantum vacuum can be investigated as we reach previously unattainable laser intensities. Effects such as vacuum birefringence and pair production in strong fields could thus be probed. The prospects of obtaining new insights regarding the non-perturbative structure of quantum field theories shows that the next generation laser facilities can be important tool for fundamental physical studies. Here we aim at giving a brief overview of such aspects of high-power laser physics.

  7. Analysis and comparison between electric and magnetic power couplers for accelerators in Free Electron Lasers (FEL)

    Science.gov (United States)

    Serpico, C.; Grudiev, A.; Vescovo, R.

    2016-10-01

    Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.

  8. Analysis and comparison between electric and magnetic power couplers for accelerators in Free Electron Lasers (FEL)

    Energy Technology Data Exchange (ETDEWEB)

    Serpico, C., E-mail: claudio.serpico@elettra.eu [Elettra - Sincrotrone Trieste, Trieste (Italy); Grudiev, A. [CERN, Geneva (Switzerland); Vescovo, R. [University of Trieste, Trieste (Italy)

    2016-10-11

    Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.

  9. The Application of Cryogenic Laser Physics to the Development of High Average Power Ultra-Short Pulse Lasers

    Directory of Open Access Journals (Sweden)

    David C. Brown

    2016-01-01

    Full Text Available Ultrafast laser physics continues to advance at a rapid pace, driven primarily by the development of more powerful and sophisticated diode-pumping sources, the development of new laser materials, and new laser and amplification approaches such as optical parametric chirped-pulse amplification. The rapid development of high average power cryogenic laser sources seems likely to play a crucial role in realizing the long-sought goal of powerful ultrafast sources that offer concomitant high peak and average powers. In this paper, we review the optical, thermal, thermo-optic and laser parameters important to cryogenic laser technology, recently achieved laser and laser materials progress, the progression of cryogenic laser technology, discuss the importance of cryogenic laser technology in ultrafast laser science, and what advances are likely to be achieved in the near-future.

  10. High-precision laser microcutting and laser microdrilling using diffractive beam-splitting and high-precision flexible beam alignment

    Science.gov (United States)

    Zibner, F.; Fornaroli, C.; Holtkamp, J.; Shachaf, Lior; Kaplan, Natan; Gillner, A.

    2017-08-01

    High-precision laser micro machining gains more importance in industrial applications every month. Optical systems like the helical optics offer highest quality together with controllable and adjustable drilling geometry, thus as taper angle, aspect ratio and heat effected zone. The helical optics is based on a rotating Dove-prism which is mounted in a hollow shaft engine together with other optical elements like wedge prisms and plane plates. Although the achieved quality can be interpreted as extremely high the low process efficiency is a main reason that this manufacturing technology has only limited demand within the industrial market. The objective of the research studies presented in this paper is to dramatically increase process efficiency as well as process flexibility. During the last years, the average power of commercial ultra-short pulsed laser sources has increased significantly. The efficient utilization of the high average laser power in the field of material processing requires an effective distribution of the laser power onto the work piece. One approach to increase the efficiency is the application of beam splitting devices to enable parallel processing. Multi beam processing is used to parallelize the fabrication of periodic structures as most application only require a partial amount of the emitted ultra-short pulsed laser power. In order to achieve highest flexibility while using multi beam processing the single beams are diverted and re-guided in a way that enables the opportunity to process with each partial beam on locally apart probes or semimanufactures.

  11. The study towards high intensity high charge state laser ion sources.

    Science.gov (United States)

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible.

  12. Advances in high field laser physics

    CERN Document Server

    Sheng, Zhengming; Chen, Liming; Lu, Wei; Shen, Baifei

    2019-01-01

    High field laser physics emerged with the advent of ultrashort intense lasers about 25 years ago. It has developed into a frontier of cross-disciplinary studies, covering attosecond X-ray physics, particle accelerator physics, and physics of inertial confined fusion, etc., with prospects of wide applications. Because this is a new and rapidly developing field, so far there are only 2-3 related books available. There are a few review articles in some journals, which are limited to specific topics in high field physics. There are quite a few conference proceedings in this field, which are the collections of papers presented at conferences. In this book, a few leading experts working on different subjects in this field are invited to introduce the key topics in high field laser physics, which cover the involved fundamental physics, the recent advances, as well as the prospects of future applications. It shall be very useful to graduate students, young researchers, and people who want to have an overview of thi...

  13. High-gradient breakdown studies of an X-band Compact Linear Collider prototype structure

    Directory of Open Access Journals (Sweden)

    Xiaowei Wu

    2017-05-01

    Full Text Available A Compact Linear Collider prototype traveling-wave accelerator structure fabricated at Tsinghua University was recently high-gradient tested at the High Energy Accelerator Research Organization (KEK. This X-band structure showed good high-gradient performance of up to 100  MV/m and obtained a breakdown rate of 1.27×10^{−8} per pulse per meter at a pulse length of 250 ns. This performance was similar to that of previous structures tested at KEK and the test facility at the European Organization for Nuclear Research (CERN, thereby validating the assembly and bonding of the fabricated structure. Phenomena related to vacuum breakdown were investigated and are discussed in the present study. Evaluation of the breakdown timing revealed a special type of breakdown occurring in the immediately succeeding pulse after a usual breakdown. These breakdowns tended to occur at the beginning of the rf pulse, whereas usual breakdowns were uniformly distributed in the rf pulse. The high-gradient test was conducted under the international collaboration research program among Tsinghua University, CERN, and KEK.

  14. The Multidisk Diode-Pumped High Power Yb:YAG Laser Amplifier of High-Intensity Laser System with 1 kHz Repetition Rate

    Science.gov (United States)

    Kuptsov, G. V.; Petrov, V. V.; Petrov, V. A.; Laptev, A. V.; Kirpichnikov, A. V.; Pestryakov, E. V.

    2018-04-01

    The source of instabilities in the multidisk diode-pumped high power Yb:YAG laser amplifier with cryogenic closed-loop cooling in the laser amplification channel of the high-intensity laser system with 1 kHz repetition rate was determined. Dissected copper mounts were designed and used to suppress instabilities and to achieve repeatability of the system. The equilibrium temperature dependency of the active elements on average power was measured. The seed laser for the multidisk amplifier was numerically simulated and designed to allow one to increase pulses output energy after the amplifier up to 500 mJ.

  15. Laser application in high temperature materials

    International Nuclear Information System (INIS)

    Ohse, R.W.

    1988-01-01

    The scope and priorities of laser application in materials science and technology are attracting widespread interest. After a brief discussion of the unique capabilities of laser application in the various fields of materials science, main emphasis is given on the three areas of materials processing, surface modification and alloying, and property measurements at high temperatures. In materials processing the operational regimes for surface hardening, drilling, welding and laser glazing are discussed. Surface modifications by laser melting, quenching and surface alloying, the formation of solid solutions, metastable phases and amorphous solids on the basis of rapid solidification, ion implantation and ion beam mixing are considered. The influence of solidification rates and interface velocities on the surface properties are given. The extension of property measurements up to and beyond the melting point of refractory materials into their critical region by a transient-type dynamic laser pulse heating technique is given for the three examples of vapour pressure measurement, density and heat capacity determination in the solid and liquid phases. A new approach, the laser autoclave technique, applying laser heating and x-ray shadow technique under autoclave conditions to acoustically levitated spheres will be presented. (author)

  16. In-plane laser forming for high precision alignment

    NARCIS (Netherlands)

    Folkersma, Ger; Römer, Gerardus Richardus, Bernardus, Engelina; Brouwer, Dannis Michel; Huis in 't Veld, Bert

    2014-01-01

    Laser microforming is extensively used to align components with submicrometer accuracy, often after assembly. While laser-bending sheet metal is the most common laser-forming mechanism, the in-plane upsetting mechanism is preferred when a high actuator stiffness is required. A three-bridge planar

  17. High resolution UV spectroscopy and laser-focused nanofabrication

    NARCIS (Netherlands)

    Myszkiewicz, G.

    2005-01-01

    This thesis combines two at first glance different techniques: High Resolution Laser Induced Fluorescence Spectroscopy (LIF) of small aromatic molecules and Laser Focusing of atoms for Nanofabrication. The thesis starts with the introduction to the high resolution LIF technique of small aromatic

  18. Improved cutting performance in high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove

    2003-01-01

    Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described.......Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described....

  19. Study on the high-frequency laser measurement of slot surface difference

    Science.gov (United States)

    Bing, Jia; Lv, Qiongying; Cao, Guohua

    2017-10-01

    In view of the measurement of the slot surface difference in the large-scale mechanical assembly process, Based on high frequency laser scanning technology and laser detection imaging principle, This paragraph designs a double galvanometer pulse laser scanning system. Laser probe scanning system architecture consists of three parts: laser ranging part, mechanical scanning part, data acquisition and processing part. The part of laser range uses high-frequency laser range finder to measure the distance information of the target shape and get a lot of point cloud data. Mechanical scanning part includes high-speed rotary table, high-speed transit and related structure design, in order to realize the whole system should be carried out in accordance with the design of scanning path on the target three-dimensional laser scanning. Data processing part mainly by FPGA hardware with LAbVIEW software to design a core, to process the point cloud data collected by the laser range finder at the high-speed and fitting calculation of point cloud data, to establish a three-dimensional model of the target, so laser scanning imaging is realized.

  20. Cryogenic cooling for high power laser amplifiers

    Directory of Open Access Journals (Sweden)

    Perin J.P.

    2013-11-01

    Full Text Available Using DPSSL (Diode Pumped Solid State Lasers as pumping technology, PW-class lasers with enhanced repetition rates are developed. Each of the Yb YAG amplifiers will be diode-pumped at a wavelength of 940 nm. This is a prerequisite for achieving high repetition rates (light amplification duration 1 millisecond and repetition rate 10 Hz. The efficiency of DPSSL is inversely proportional to the temperature, for this reason the slab amplifier have to be cooled at a temperature in the range of 100 K–170 K with a heat flux of 1 MW*m−2. This paper describes the thermo-mechanical analysis for the design of the amplification laser head, presents a preliminary proposal for the required cryogenic cooling system and finally outlines the gain of cryogenic operation for the efficiency of high pulsed laser.

  1. Recent progress in high-power slab lasers in Japan

    International Nuclear Information System (INIS)

    Fujii, Y.

    1988-01-01

    Recently, many solid-state lasers have been widely employed in Japanese industries, especially in the electronics industries for precise and reliable processing. To expand the use of solid-state lasers and to achieve higher processing speed, the authors are developing slab lasers of high power, high repetition rate, and high beam quality. Metal processing systems with optical fibers for large and complex 3-D work, multiwork station systems linked to only one laser with optical fibers, and compact x-ray sources for lithography are promising areas for such lasers. Surnitomo Metal Mining is growing Nd:GGG and Nd:YAG crystals 60 mm in diameter and 200 mm long. From 2 at.% Nd-doped GGG crystals without central core regions. The authors obtained two slab materials with dimensions of 35 X 9 X 192 and 55 X 15 X 213 mm/sup 3/. By using the smaller slab, they constructed a slab laser and obtained 370-W laser output power at 24-kW lamp input power and 10-pps repetition rate. Now they are constructing a 1-kW slab laser using the other larger size slab

  2. Wavelength dependency in high power laser cutting and welding

    Science.gov (United States)

    Havrilla, David; Ziermann, Stephan; Holzer, Marco

    2012-03-01

    Laser cutting and welding have been around for more than 30 years. Within those three decades there has never been a greater variety of high power laser types and wavelengths to choose from than there is today. There are many considerations when choosing the right laser for any given application - capital investment, cost of ownership, footprint, serviceability, along with a myriad of other commercial & economic considerations. However, one of the most fundamental questions that must be asked and answered is this - "what type of laser is best suited for the application?". Manufacturers and users alike are realizing what, in retrospect, may seem obvious - there is no such thing as a universal laser. In many cases there is one laser type and wavelength that clearly provides the highest quality application results. This paper will examine the application fields of high power, high brightness 10.6 & 1 micron laser welding & cutting and will provide guidelines for selecting the laser that is best suited for the application. Processing speed & edge quality serve as key criteria for cutting. Whereas speed, seam quality & spatter ejection provide the paradigm for welding.

  3. Using Spherical-Harmonics Expansions for Optics Surface Reconstruction from Gradients.

    Science.gov (United States)

    Solano-Altamirano, Juan Manuel; Vázquez-Otero, Alejandro; Khikhlukha, Danila; Dormido, Raquel; Duro, Natividad

    2017-11-30

    In this paper, we propose a new algorithm to reconstruct optics surfaces (aka wavefronts) from gradients, defined on a circular domain, by means of the Spherical Harmonics. The experimental results indicate that this algorithm renders the same accuracy, compared to the reconstruction based on classical Zernike polynomials, using a smaller number of polynomial terms, which potentially speeds up the wavefront reconstruction. Additionally, we provide an open-source C++ library, released under the terms of the GNU General Public License version 2 (GPLv2), wherein several polynomial sets are coded. Therefore, this library constitutes a robust software alternative for wavefront reconstruction in a high energy laser field, optical surface reconstruction, and, more generally, in surface reconstruction from gradients. The library is a candidate for being integrated in control systems for optical devices, or similarly to be used in ad hoc simulations. Moreover, it has been developed with flexibility in mind, and, as such, the implementation includes the following features: (i) a mock-up generator of various incident wavefronts, intended to simulate the wavefronts commonly encountered in the field of high-energy lasers production; (ii) runtime selection of the library in charge of performing the algebraic computations; (iii) a profiling mechanism to measure and compare the performance of different steps of the algorithms and/or third-party linear algebra libraries. Finally, the library can be easily extended to include additional dependencies, such as porting the algebraic operations to specific architectures, in order to exploit hardware acceleration features.

  4. Welding with high power fiber lasers - A preliminary study

    International Nuclear Information System (INIS)

    Quintino, L.; Costa, A.; Miranda, R.; Yapp, D.; Kumar, V.; Kong, C.J.

    2007-01-01

    The new generation of high power fiber lasers presents several benefits for industrial purposes, namely high power with low beam divergence, flexible beam delivery, low maintenance costs, high efficiency and compact size. This paper presents a brief review of the development of high power lasers, and presents initial data on welding of API 5L: X100 pipeline steel with an 8 kW fiber laser. Weld bead geometry was evaluated and transition between conduction and deep penetration welding modes was investigated

  5. A compact x-ray free electron laser

    International Nuclear Information System (INIS)

    Barletta, W.; Attac, M.; Cline, D.B.

    1988-01-01

    We present a design concept and simulation of the performance of a compact x-ray, free electron laser driven by ultra-high gradient rf-linacs. The accelerator design is based on recent advances in high gradient technology by a LLNL/SLAC/LBL collaboration and on the development of bright, high current electron sources by BNL and LANL. The GeV electron beams generated with such accelerators can be concerted to soft x-rays in the range from 2--10 nm by passage through short period, high fields strength wigglers as are being designed at Rocketdyne. Linear light sources of this type can produce trains of picosecond (or shorter) pulses of extremely high spectral brilliance suitable for flash holography of biological specimens in vivo and for studies of fast chemical reactions. 12 refs., 8 figs., 4 tabs

  6. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  7. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide

    CERN Document Server

    Yi, Longqing; Shen, Baifei

    2016-01-01

    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO 2 laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread (~1%) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO2 laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications.

  8. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the ...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser....

  9. Effects of high-gradient magnetic fields on living cell machinery

    International Nuclear Information System (INIS)

    Zablotskii, V; Lunov, O; Kubinova, S; Polyakova, T; Dejneka, A; Sykova, E

    2016-01-01

    A general interest in biomagnetic effects is related to fundamental studies of the influence of magnetic fields on living objects on the cellular and whole organism levels. Emerging technologies offer new directions for the use of high-gradient magnetic fields to control cell machinery and to understand the intracellular biological processes of the emerging field of nanomedicine. In this review we aim at highlighting recent advances made in identifying fundamental mechanisms by which magnetic gradient forces act on cell fate specification and cell differentiation. The review also provides an analysis of the currently available magnetic systems capable of generating magnetic fields with spatial gradients of up to 10 MT m −1 , with the focus on their suitability for use in cell therapy. Relationships between experimental factors and underlying biophysical mechanisms and assumptions that would ultimately lead to a deeper understanding of cell machinery and the development of more predictive models for the evaluation of the effects of magnetic fields on cells, tissue and organisms are comprehensively discussed. (topical review)

  10. Laser apparatus for surgery and force therapy based on high-power semiconductor and fibre lasers

    International Nuclear Information System (INIS)

    Minaev, V P

    2005-01-01

    High-power semiconductor lasers and diode-pumped lasers are considered whose development qualitatively improved the characteristics of laser apparatus for surgery and force therapy, extended the scope of their applications in clinical practice, and enhanced the efficiency of medical treatment based on the use of these lasers. The characteristics of domestic apparatus are presented and their properties related to the laser emission wavelength used in them are discussed. Examples of modern medical technologies based on these lasers are considered. (invited paper)

  11. Absorption of CO2 laser light by a dense, high temperature plasma

    International Nuclear Information System (INIS)

    Peacock, N.J.; Forrest, M.J.; Morgan, P.D.; Offenberger, A.A.

    1977-01-01

    The interaction between a pulsed, CO 2 laser beam and the plasma produced in a plasma focus device is investigated theoretically and experimentally. The CO 2 laser radiation, directed orthogonal to the pinch axis and along the density gradient only weakly perturbs the focus since the radiation density of 30 J cm -3 (allowing for the Airy enhancement factor near the critical layer), is still less than the plasma thermal energy >=1 kJ cm -3 . On the contrary, the CO 2 laser beam is grossly affected by the plasma and absorption during the compressed pinch phase when the plasma frequency is much more complete than can be predicted by classical resistivity. Density fluctuations at the Langmuir frequency are measured directly for forward scattering from a probe, ruby laser beam. Since the wave numbers correspond to approximately 0.1 the Langmuir waves should appear as electron 'lines' in the scattered spectrum shifted by 427 A from the ruby laser wavelength. At low CO 2 laser pump intensity the electron wave intensity is close to the thermal level. As the pump is increased beyond a threshold of approximately 3x10 9 W/cm -2 (in vacuo) enhanced scattering is observed, reaching a factor of 30 above thermal. A WKB treatment of the electron-ion decay instability which takes into account the linear growth of waves at equal electron and ion temperatures and their convection in an inhomogeneous plasma is reasonably consistent with the observations

  12. PHELIX - Petawatt high-energy laser for heavy ion experiments

    International Nuclear Information System (INIS)

    Backe, H.; Bock, R.; Caird, J.

    1998-12-01

    A high-power laser facility will be installed at the GSI heavy-ion accelerator. It will deliver laser pulses up to one kilojoule (with an option of a later upgrade to several kJ) at a pulse length of 1 - 10 nanoseconds (high-energy mode). In a high-intensity mode, laser pulses with a power of one petawatt (10 15 Watt) will be generated by chirped pulse amplification at a pulse length of typically 500 femtoseconds. Details of the laser system as well as time schedule and costs are given in Section B. In combination with the heavy-ion beams available at GSI - which will be further improved in intensity by the presently on-going upgrade program - a large number of unique experiments will become possible by the high-power laser facility described in this report. As outlined in Section A, novel research opportunities are expected in a wide range of basic-research topics spanning from the study of ion-matter interaction, through challenging new experiments in atomic, nuclear, and astrophysics, into the virgin field of relativistic plasma physics. Foreseeable topics in applied science are the development of new sources for highly charged ions and of X-ray lasers, new concepts for laser-based particle acceleration and the research in the field of inertial confinement fusion. (orig.)

  13. Spatiotemporal polarization gradients in phase-bearing light

    International Nuclear Information System (INIS)

    Lembessis, V. E.; Babiker, M.

    2010-01-01

    It is shown how the interference of two circularly polarized laser beams endowed with orbital angular momentum can give rise to spatial and temporal polarization gradients, displaying axial as well as angular symmetry properties. Illustrations are given with reference to circularly polarized Laguerre-Gaussian beams as typical light beams carrying orbital angular momentum.

  14. Potential of high-average-power solid state lasers

    International Nuclear Information System (INIS)

    Emmett, J.L.; Krupke, W.F.; Sooy, W.R.

    1984-01-01

    We discuss the possibility of extending solid state laser technology to high average power and of improving the efficiency of such lasers sufficiently to make them reasonable candidates for a number of demanding applications. A variety of new design concepts, materials, and techniques have emerged over the past decade that, collectively, suggest that the traditional technical limitations on power (a few hundred watts or less) and efficiency (less than 1%) can be removed. The core idea is configuring the laser medium in relatively thin, large-area plates, rather than using the traditional low-aspect-ratio rods or blocks. This presents a large surface area for cooling, and assures that deposited heat is relatively close to a cooled surface. It also minimizes the laser volume distorted by edge effects. The feasibility of such configurations is supported by recent developments in materials, fabrication processes, and optical pumps. Two types of lasers can, in principle, utilize this sheet-like gain configuration in such a way that phase and gain profiles are uniformly sampled and, to first order, yield high-quality (undistorted) beams. The zig-zag laser does this with a single plate, and should be capable of power levels up to several kilowatts. The disk laser is designed around a large number of plates, and should be capable of scaling to arbitrarily high power levels

  15. Reduced filamentation in high power semiconductor lasers

    DEFF Research Database (Denmark)

    Skovgaard, Peter M. W.; McInerney, John; O'Brien, Peter

    1999-01-01

    High brightness semiconductor lasers have applications in fields ranging from material processing to medicine. The main difficulty associated with high brightness is that high optical power densities cause damage to the laser facet and thus require large apertures. This, in turn, results in spatio......-temporal instabilities such as filamentation which degrades spatial coherence and brightness. We first evaluate performance of existing designs with a “top-hat” shaped transverse current density profile. The unstable nature of highly excited semiconductor material results in a run-away process where small modulations...

  16. A linear accelerator power amplification system for high gradient structure research

    International Nuclear Information System (INIS)

    Haimson, J.; Mecklenburg, B.

    1999-01-01

    The ongoing development of linear collider high power RF sources and pulse compression systems has resulted in substantial progress towards a goal of providing a peak RF power level of approximately 250 MW at the input of the accelerator structure. While the immediate development and the high power testing of specialized waveguide components required for power transmission at these high levels have proceeded expeditiously due to the availability of resonant ring systems, the testing of high gradient accelerator structures at very high power levels, and the investigation of coupler cavity RF breakdown problems have, typically, been curtailed due to the unavailability of suitable 200 to 300 MW RF test facilities. We describe herein a compact, high peak power amplification system based on a dual hybrid bridge configuration that avoids the need for power splitters at the accelerator dual feed couplers, and also provides a convenient interface for installing high gradient accelerator test structures. Design parameters are presented for a proposed power amplification system that makes use of a 75 MW, 1/2 μs flat-top RF source to produce 280 MW, 1/4 μs flat-top power for testing dual feed TW experimental accelerator sections

  17. High power visible diode laser for the treatment of eye diseases by laser coagulation

    Science.gov (United States)

    Heinrich, Arne; Hagen, Clemens; Harlander, Maximilian; Nussbaumer, Bernhard

    2015-03-01

    We present a high power visible diode laser enabling a low-cost treatment of eye diseases by laser coagulation, including the two leading causes of blindness worldwide (diabetic retinopathy, age-related macular degeneration) as well as retinopathy of prematurely born children, intraocular tumors and retinal detachment. Laser coagulation requires the exposure of the eye to visible laser light and relies on the high absorption of the retina. The need for treatment is constantly increasing, due to the demographic trend, the increasing average life expectancy and medical care demand in developing countries. The World Health Organization reacts to this demand with global programs like the VISION 2020 "The right to sight" and the following Universal Eye Health within their Global Action Plan (2014-2019). One major point is to motivate companies and research institutes to make eye treatment cheaper and easily accessible. Therefore it becomes capital providing the ophthalmology market with cost competitive, simple and reliable technologies. Our laser is based on the direct second harmonic generation of the light emitted from a tapered laser diode and has already shown reliable optical performance. All components are produced in wafer scale processes and the resulting strong economy of scale results in a price competitive laser. In a broader perspective the technology behind our laser has a huge potential in non-medical applications like welding, cutting, marking and finally laser-illuminated projection.

  18. High current, high bandwidth laser diode current driver

    Science.gov (United States)

    Copeland, David J.; Zimmerman, Robert K., Jr.

    1991-01-01

    A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

  19. How a high-gradient magnetic field could affect cell life

    Czech Academy of Sciences Publication Activity Database

    Zablotskyy, Vitaliy A.; Polyakova, Tetyana; Lunov, Oleg; Dejneka, Alexandr

    2016-01-01

    Roč. 6, Nov (2016), 1-12, č. článku 37407. ISSN 2045-2322 Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : high-gradient magnetic field * cell Subject RIV: BO - Biophysics Impact factor: 4.259, year: 2016

  20. High accuracy 3-D laser radar

    DEFF Research Database (Denmark)

    Busck, Jens; Heiselberg, Henning

    2004-01-01

    We have developed a mono-static staring 3-D laser radar based on gated viewing with range accuracy below 1 m at 10 m and 1 cm at 100. We use a high sensitivity, fast, intensified CCD camera, and a Nd:Yag passively Q-switched 32.4 kHz pulsed green laser at 532 nm. The CCD has 752x582 pixels. Camera...

  1. The UCLA/SLAC Ultra-High Gradient Cerenkov Wakefield Accelerator Experiment

    CERN Document Server

    Thompson, Matthew C; Hogan, Mark; Ischebeck, Rasmus; Muggli, Patric; Rosenzweig, James E; Scott, A; Siemann, Robert; Travish, Gil; Walz, Dieter; Yoder, Rodney

    2005-01-01

    An experiment is planned to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range. This new UCLA/SLAC collaboration will take advantage of the unique SLAC FFTB electron beam and its demonstrated ultra-short pulse lengths and high currents (e.g., sz = 20 μm at Q = 3 nC). The electron beam will be focused down and sent through varying lengths of fused silica capillary tubing with two different sizes: ID = 200 μm / OD = 325 μm and ID = 100 μm / OD = 325 μm. The pulse length of the electron beam will be varied in order to alter the accelerating gradient and probe the breakdown threshold of the dielectric structures. In addition to breakdown studies, we plan to collect and measure coherent Cerenkov radiation emitted from the capillary tube to gain information about the strength of the accelerating fields. Status and progress on the experiment are reported.

  2. Asymmetric Uncertainty Expression for High Gradient Aerodynamics

    Science.gov (United States)

    Pinier, Jeremy T

    2012-01-01

    When the physics of the flow around an aircraft changes very abruptly either in time or space (e.g., flow separation/reattachment, boundary layer transition, unsteadiness, shocks, etc), the measurements that are performed in a simulated environment like a wind tunnel test or a computational simulation will most likely incorrectly predict the exact location of where (or when) the change in physics happens. There are many reasons for this, includ- ing the error introduced by simulating a real system at a smaller scale and at non-ideal conditions, or the error due to turbulence models in a computational simulation. The un- certainty analysis principles that have been developed and are being implemented today do not fully account for uncertainty in the knowledge of the location of abrupt physics changes or sharp gradients, leading to a potentially underestimated uncertainty in those areas. To address this problem, a new asymmetric aerodynamic uncertainty expression containing an extra term to account for a phase-uncertainty, the magnitude of which is emphasized in the high-gradient aerodynamic regions is proposed in this paper. Additionally, based on previous work, a method for dispersing aerodynamic data within asymmetric uncer- tainty bounds in a more realistic way has been developed for use within Monte Carlo-type analyses.

  3. Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers

    International Nuclear Information System (INIS)

    Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

    1993-01-01

    Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented

  4. Inverse free-electron laser accelerator development

    International Nuclear Information System (INIS)

    Fisher, A.; Gallardo, J.; Steenbergen, A. van; Sandweiss, J.; Fang, J.M.

    1994-06-01

    The study of the Inverse Free-Electron Laser, as a potential mode of electron acceleration, has been pursued at Brookhaven National Laboratory for a number of years. More recent studies focused on the development of a low energy (few GeV), high gradient, multistage linear accelerator. The authors are presently designing a short accelerator module which will make use of the 50 MeV linac beam and high power (2 x 10 11 W) CO 2 laser beam of the Accelerator Test Facility (ATF) at the Center for Accelerator Physics (CAP), Brookhaven National Laboratory. These elements will be used in conjunction with a fast excitation (300 μsec pulse duration) variable period wiggler, to carry out an accelerator demonstration stage experiment

  5. Mode profiling of optical fibers at high laser powers

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Pedersen, David Bue; Simonsen, R.B.

    2008-01-01

    of the focused spot can be determined. The analyser is based on the principle of a rotating wire being swept though the laser beam, while the reflected signal is recorded [1]. By changing the incident angle of the rotating rod from 0° to 360° in relation to the fiber, the full profile of the laser beam...... is obtained. Choosing a highly reflective rod material and a sufficiently high rotation speed, these measurements can be done with high laser powers, without any additional optical elements between the fiber and analyzer. The performance of the analyzer was evaluated by coupling laser light into different...

  6. Ultra-High Gradient Channeling Acceleration in Nanostructures: Design/Progress of Proof-of-Concept (POC) Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Min [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Northern Illinois Univ., DeKalb, IL (United States). Northern Illinois Center for Accelerator & Detector Development; Green, A. [Northern Illinois Univ., DeKalb, IL (United States). Northern Illinois Center for Accelerator & Detector Development; Lumpkin, A. H. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Thurman-Keup, R. M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Shiltsev, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zhang, X. [Shanhai Inst. of Optics and Fine Mechanics, Shanghai (China); Farinella, D. M. [Univ. of California, Irvine, CA (United States); Taborek, P. [Univ. of California, Irvine, CA (United States); Tajima, T. [Univ. of California, Irvine, CA (United States); Wheeler, J. A. [Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science and FOCUS Center; Ecole Polytechnique, CNRS, Palaiseau (France). Lab. d' Optique Appliquee; Mourou, G. [Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science and FOCUS Center; Ecole Polytechnique, CNRS, Palaiseau (France). Lab. d' Optique Appliquee

    2016-09-16

    A short bunch of relativistic particles or a short-pulse laser perturbs the density state of conduction electrons in a solid crystal and excites wakefields along atomic lattices in a crystal. Under a coupling condition the wakes, if excited, can accelerate channeling particles with TeV/m acceleration gradients in principle since the density of charge carriers (conduction electrons) in solids n0 = ~ 1020 – 1023 cm-3 is significantly higher than what can be obtained in gaseous plasma. Nanostructures have some advantages over crystals for channeling applications of high power beams. The dechanneling rate can be reduced and the beam acceptance increased by the large size of the channels. For beam-driven acceleration, a bunch length with a sufficient charge density would need to be in the range of the plasma wavelength to properly excite plasma wakefields, and channeled particle acceleration with the wakefields must occur before the ions in the lattices move beyond the restoring threshold. In the case of the excitation by short laser pulses, the dephasing length is appreciably increased with the larger channel, which enables channeled particles to gain sufficient amounts of energy. This paper describes simulation analyses on beam- and laser (X-ray)-driven accelerations in effective nanotube models obtained from Vsim and EPOCH codes. Experimental setups to detect wakefields are also outlined with accelerator facilities at Fermilab and NIU. In the FAST facility, the electron beamline was successfully commissioned at 50 MeV and it is being upgraded toward higher energies for electron accelerator R&D. The 50 MeV injector beamline of the facility is used for X-ray crystal-channeling radiation with a diamond target. It has been proposed to utilize the same diamond crystal for a channeling acceleration POC test. Another POC experiment is also designed for the NIU accelerator lab with time-resolved electron diffraction. Recently, a

  7. High-gradient magnetic separation for the treatment of high-level radioactive wastes

    International Nuclear Information System (INIS)

    Ebner, A.D.; Ritter, J.A.; Nunez, L.

    1999-01-01

    Argonne National Laboratory is developing an open-gradient magnetic separation (OGMS) system to fractionate and remove nonglass-forming species from high-level radioactive wastes (HLW); however, to avoid clogging, OGMS may require high-gradient magnetic separation (HGMS) as a pretreatment to remove the most magnetic species from the HLW. In this study, the feasibility of using HGMS in the pretreatment of HLW was demonstrated. A HLW simulant of hanford's C-103 tank waste, which contained precipitate hydroxides and oxides of Fe, Al, Si, and Ca, was used. Preliminary fractionation results from a 0.3-T bench-scale HGMS unit showed that a significant amount of Fe could be removed from the HLW simulant. Between 1 and 2% of the total Fe in the sludge was removed during each stage, with over 18.5% removed in the 13 stages that were carried out. Also, in each stage, the magnetically retained fraction contained about 20% more Fe than the untreated HLW; however, it also contained a significant amount of SiO 2 in relatively large particles. This indicated that SiO 2 was acting possibly as a nucleation agent for Fe (i.e., an Fe adsorbent) and that the fractionation was based more on size than on magnetic susceptibility

  8. Magnetic matrices used in high gradient magnetic separation (HGMS: A review

    Directory of Open Access Journals (Sweden)

    Wei Ge

    Full Text Available HGMS is effective in separating or filtering fine and weakly magnetic particles and widely applied in mineral processing, water treatment, cell and protein purification. The magnetic matrix is a crucial device used in magnetic separator to generate high magnetic field gradient and provide surface sites for capturing magnetic particles. The material, geometry, size and arrangement of the matrix elements can significantly affect the gradient and distribution of the magnetic field, and the separating or filtrating performance. In this paper, the researches and developments of magnetic matrices used in HGMS are reviewed. Keywords: Magnetic matrix, HGMS, Review

  9. High-energy, short-pulse, carbon-dioxide lasers

    International Nuclear Information System (INIS)

    Fenstermacher, C.A.

    1979-01-01

    Lasers for fusion application represent a special class of short-pulse generators; not only must they generate extremely short temporal pulses of high quality, but they must do this at ultra-high powers and satisfy other stringent requirements by this application. This paper presents the status of the research and development of carbon-dioxide laser systems at the Los Alamos Scientific Laboratory, vis-a-vis the fusion requirements

  10. Laser guidance of mesoscale particles

    Science.gov (United States)

    Underdown, Frank Hartman, Jr.

    Mesoscale particles are guided and trapped in hollow optical fibers using radiation pressure forces. Laser light from a 0.4W, 780nm diode laser is guided in a low- loss fiber mode and used to generate the guidance forces. Laser scattering and absorption forces propels particles along the fiber and polarization gradient forces attract them to the fiber's axial center. Using two counter propagating laser beams, inside the fiber, particles can be trapped in three dimensions. Measuring the spring constant of the trap gives the gradient force. This dissertation describes Rayleigh and Mie scattering models for calculating guidance forces. Calculated forces as a function of particle size and composition (i.e. dielectric, semiconductor, and metals) will be presented. For example, under typical experimental conditions 100nm Au particles are guided by a 2 × 10-14 N propulsive force in a water filled fiber. In comparison, the measured force, obtained from the particle's velocity and Stokes' law, is 7.98 × 10-14 N.

  11. 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.

  12. High-intensity laser synchrotron x-ray source

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.

    1995-10-01

    A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high-brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the Laser Synchrotron Light Source (LSLS) concept is still waiting for a convincing demonstration. Available at the BNL's Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power C0 2 laser may be used as prototype LSLS brick stones. In a feasible demonstration experiment, 10-GW, 100-ps C0 2 laser beam will be brought to a head-on collision with a 10-ps, 0.5-nC, 70 MeV electron bunch. Flashes of well-collimated, up to 9.36-keV (∼ Angstrom) x-rays of 10-ps pulse duration, with a flux of ∼10 19 photons/sec will be produced via linear Compton backscattering. The x-ray spectrum is tunable proportionally to a variable e-beam energy. A natural short-term extension of the proposed experiment would be further enhancement of the x-ray flux to a 10 21 -10 22 photons/sec level, after the ongoing ATF CO 2 laser upgrade to 1 TW peak power and electron bunch shortening to 3 ps. The ATF LSLS x-ray beamline, exceeding by orders of magnitude the peak fluxes attained at the National Synchrotron Light Source (NSLS) x-ray storage ring, may become attractive for certain users, e.g., for biological x-ray microscopy. In addition, a terawatt CO 2 laser will enable harmonic multiplication of the x-ray spectrum via nonlinear Compton scattering

  13. High-power CO laser and its potential applications

    International Nuclear Information System (INIS)

    Sato, Shunichi; Takahashi, Kunimitsu; Shimamoto, Kojiro; Takashima, Yoichi; Matsuda, Keiichi; Kuribayashi, Shizuma; Noda, Osamu; Imatake, Shigenori; Kondo, Motoe.

    1995-01-01

    The R and D program for the development of a high-power CO laser and its application technologies is described. Based on a self-sustained discharge excitation scheme, the available laser output has been successfully scaled to over 20 kW. The CO laser cutting experiments for thick metals have been performed in association with the decommissioning technologies development. Other potential applications, which include those based on photo chemical process, are reviewed. Recently demonstrated high-power tunable operation and room-temperature operation are also reported. (author)

  14. High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

    Science.gov (United States)

    Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

    2016-03-01

    Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

  15. High-performance ionic diode membrane for salinity gradient power generation.

    Science.gov (United States)

    Gao, Jun; Guo, Wei; Feng, Dan; Wang, Huanting; Zhao, Dongyuan; Jiang, Lei

    2014-09-03

    Salinity difference between seawater and river water is a sustainable energy resource that catches eyes of the public and the investors in the background of energy crisis. To capture this energy, interdisciplinary efforts from chemistry, materials science, environmental science, and nanotechnology have been made to create efficient and economically viable energy conversion methods and materials. Beyond conventional membrane-based processes, technological breakthroughs in harvesting salinity gradient power from natural waters are expected to emerge from the novel fluidic transport phenomena on the nanoscale. A major challenge toward real-world applications is to extrapolate existing single-channel devices to macroscopic materials. Here, we report a membrane-scale nanofluidic device with asymmetric structure, chemical composition, and surface charge polarity, termed ionic diode membrane (IDM), for harvesting electric power from salinity gradient. The IDM comprises heterojunctions between mesoporous carbon (pore size ∼7 nm, negatively charged) and macroporous alumina (pore size ∼80 nm, positively charged). The meso-/macroporous membrane rectifies the ionic current with distinctly high ratio of ca. 450 and keeps on rectifying in high-concentration electrolytes, even in saturated solution. The selective and rectified ion transport furthermore sheds light on salinity-gradient power generation. By mixing artificial seawater and river water through the IDM, substantially high power density of up to 3.46 W/m(2) is discovered, which largely outperforms some commercial ion-exchange membranes. A theoretical model based on coupled Poisson and Nernst-Planck equations is established to quantitatively explain the experimental observations and get insights into the underlying mechanism. The macroscopic and asymmetric nanofluidic structure anticipates wide potentials for sustainable power generation, water purification, and desalination.

  16. High-resolution in-source laser spectroscopy in perpendicular geometry

    Energy Technology Data Exchange (ETDEWEB)

    Heinke, R., E-mail: reinhard.heinke@uni-mainz.de; Kron, T. [Universität Mainz, Institut für Physik (Germany); Raeder, S. [Helmholtz-Institut Mainz (Germany); Reich, T.; Schönberg, P. [Universität Mainz, Institut für Kernchemie (Germany); Trümper, M.; Weichhold, C.; Wendt, K. [Universität Mainz, Institut für Physik (Germany)

    2017-11-15

    Operation of the novel laser ion source unit LIST (Laser Ion Source and Trap), operating at the on-line radioactive ion beam facility ISOLDE at CERN allowed for the production of ultra-pure beams of exotic isotopes far-off stability as well as direct isobar-free laser spectroscopy, giving access to the study of atomic and nuclear properties of so far inaccessible nuclides. We present a specific upgrade and adaption of the LIST targeted for high resolution spectroscopy with a Doppler-reduced perpendicular atom - laser beam geometry. With this PI-LIST (Perpendicularly Illuminated Laser Ion Source and Trap) setup, experimental linewidths below 100 MHz could be demonstrated in optical laser spectroscopy off-line, applying a pulsed injection-locked high repetition rate Ti:sapphire laser. A dual repeller configuration ensured highest suppression of isobaric interferences and almost background-free measurements on small samples in the order of 10{sup 11} atoms.

  17. Picosecond high power laser systems and picosecond diagnostic technique in laser produced plasma

    International Nuclear Information System (INIS)

    Kuroda, Hiroto; Masuko, H.; Maekawa, Shigeru; Suzuki, Yoshiji; Sugiyama, Masaru.

    1979-01-01

    Highly repetitive, high power YAG and Glass laser systems have been developed and been successfully used for the studies of laser-plasma interactions. Various picosecond diagnostic techniques have been developed for such purposes in the regions from optical to X-ray frequency. Recently highly sensitive X-ray (1 - 10 KeV) streak camera for highly repetitive operations have been developed. Preliminary experiment shows the achievement of 28ps temporal resolution (100μm slit) and good sensitivity with detectable minimum number of 10E3-1KeV photons/shot/slit area. (author)

  18. High-gradient operators in the psl(2 vertical stroke 2) Gross-Neveu model

    International Nuclear Information System (INIS)

    Cagnazzo, Alessandra; Schomerus, Volker; Tlapak, Vaclav

    2014-10-01

    It has been observed more than 25 years ago that sigma model perturbation theory suffers from strongly RG-relevant high-gradient operators. The phenomenon was first seen in 1-loop calculations for the O(N) vector model and it is known to persist at least to two loops. More recently, Ryu et al. suggested that a certain deformation of the psl(N vertical stroke N) WZNW-model at level k=1, or equivalently the psl(N vertical stroke N) Gross-Neveu model, could be free of RG-relevant high-gradient operators and they tested their suggestion to leading order in perturbation theory. In this note we establish the absence of strongly RG-relevant high-gradient operators in the psl(2 vertical stroke 2) Gross-Neveu model to all loops. In addition, we determine the spectrum for a large subsector of the model at infinite coupling and observe that all scaling weights become half-integer. Evidence for a conjectured relation with the CP 1 vertical stroke 2 sigma model is not found.

  19. High-Intensity Laser Diagnostics for OMEGA EP

    International Nuclear Information System (INIS)

    Bromage, J.; Zuegel, J.D.; Bahk, S.-W.; Vickery, D.S.; Waxer, L.J.; Irwin, D.; Bagnoud, V.; Boni, R.; Moore, M.D.; Junquist, R.; Stoeckl, C.

    2006-01-01

    OMEGA EP is a new high-energy petawatt laser system under construction at the University of Rochester's Laboratory for Laser Energetics. This paper describes our designs for two diagnostics critical to OMEGA EP's mission. The focal-spot diagnostic (FSD) is responsible for characterizing the focal spot of OMEGA EP's off-axis parabolic mirror at full energy. The ultrafast temporal diagnostic (UTD) is responsible for characterizing pulse shapes of full-energy target shots ranging in width from <1 to 100 ps as well as setting the desired pulse width before the shot. These diagnostics will enable, for the first time, complete spatial and temporal characterization of the focus of a high-energy petawatt laser at full energy

  20. High-power green diode laser systems for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André

    propagation parameters and therefore efficiently increases the brightness of compact and cost-effective diode laser systems. The condition of overlapping beams is an ideal scenario for subsequent frequency conversion. Based on sum-frequency generation of two beam combined diode lasers a 3.2 fold increase...... output power of frequency doubled single emitters is limited by thermal effects potentially resulting in laser degradation and failure. In this work new concepts for power scaling of visible diode laser systems are introduced that help to overcome current limitations and enhance the application potential....... Implementing the developed concept of frequency converted, beam combined diode laser systems will help to overcome the high pump thresholds for ultrabroad bandwidth titanium sapphire lasers, leading towards diode based high-resolution optical coherence tomography with enhanced image quality. In their entirety...

  1. Coaxial monitoring of temperature field in selective pulsed laser melting

    Science.gov (United States)

    Liu, Che; Chen, Zhongyun; Cao, Hongzhong; Zhou, Jianhong

    2017-10-01

    Selective Laser Melting is a rapid manufacturing technology which produces complex parts layer by layer. The presence of thermal stress and thermal strain in the forming process often leads to defects in the formed parts. In order to detect fabricate errors and avoid failure which caused by thermal gradient in time. An infrared thermal imager and a high speed CCD camera were applied to build a coaxial optical system for real-time monitoring the temperature distribution and changing trend of laser affected zone in SLM forming process. Molten tracks were fabricated by SLM under different laser parameters such as frequency, pulse width. And the relationship between the laser parameters and the temperature distribution were all obtained and analyzed.

  2. Photo-preionization stabilized high-pressure glow-discharge lasers

    International Nuclear Information System (INIS)

    Von Bergmann, H.M.

    1980-07-01

    Simple nanosecond stabilization and pulsing techniques were developed to excite high-pressure gas-discharge lasers at high overvoltages and high specific power loadings. The techniques were applied to a variety of ultraviolet and visible laser systems employing fast transmission line pulsers and conventional LC generators. The stabilization procedures are evaluated and the parameters which control the geometry and uniformity of the high-pressure glow discharges are investigated. A detailed study of the formation, distribution and spectral characteristics of the fast surface corona discharges is provided. The stabilization and pulsing techniques were used for the corona and glow discharge excitation of high-pressure ultraviolet N 2 lasers. A detailed spectrally- and temporally-resolved study of the gain, fluorescence and energy extraction characteristics of the atmospheric pressure N 2 plasmas is provided

  3. Data-driven gradient algorithm for high-precision quantum control

    Science.gov (United States)

    Wu, Re-Bing; Chu, Bing; Owens, David H.; Rabitz, Herschel

    2018-04-01

    In the quest to achieve scalable quantum information processing technologies, gradient-based optimal control algorithms (e.g., grape) are broadly used for implementing high-precision quantum gates, but their performance is often hindered by deterministic or random errors in the system model and the control electronics. In this paper, we show that grape can be taught to be more effective by jointly learning from the design model and the experimental data obtained from process tomography. The resulting data-driven gradient optimization algorithm (d-grape) can in principle correct all deterministic gate errors, with a mild efficiency loss. The d-grape algorithm may become more powerful with broadband controls that involve a large number of control parameters, while other algorithms usually slow down due to the increased size of the search space. These advantages are demonstrated by simulating the implementation of a two-qubit controlled-not gate.

  4. End design of the SSC 58 mm High Gradient Quadrupole

    International Nuclear Information System (INIS)

    Caspi, S.

    1992-01-01

    The ''end'' design of the High Gradient Quad. was done with consideration to the integrated field harmonics, the iron contribution, and the maximum field at the conductor. Magnetic analysis was done on the return end only, however the physical dimension of the lead end were determined as well. Using the cross-section of the windings and Cook's program BEND, we generated the physical end windings around the return end. Placing a single wire at the center of each turn the integrated gradient was computed and iterating on the end block spacers the integrated harmonics minimized. The final geometry was then used for more, extensive calculations, such as the field at the conductor and the 3D field harmonics. For this detailed calculation we have placed a single line current at the center of each strand and included the iron contribution (μ = ∞), see Appendix C. With the termination of the iron serving as a reference, the maximum length of the inner and outer layers are 182 mm and 215 mm respectively. The magnetic length of the end was computed from the gradient function A 2 and was found to be 142 mm. In reality we expect the physical length of the end to be somewhat larger, however this should have little or no effect on the magnetic length. The gradient in the straight section is 212.44 T/m at 7000 A and the integrated value of the gradient is -3.01665 E5 (G) in the end region marked by the magnetic length of the end. The respective integrated harmonics for the end 12 pole and 20 pole are -10.6658 (G/CM 4 ) and 0.7279 (G/cm 8 ) corresponding to b 6 = 0.351 , b 10 = -0.024 units. The above was computed from the values of A 2 , A 6 , and A 10

  5. Laser prostatectomy in high-risk patients

    International Nuclear Information System (INIS)

    Tayib, Abdulmalik M.

    2008-01-01

    Objective was to evaluate the short-term tolerability and outcome of high power green light potassium titanyl phosphate laser prostatectomy in high-risk patients with symptomatic benign prostatic hyperplasia. Eleven high risk operative patients were included in this study at the International Medical Center, Jeddah, Kingdom of Saudi Arabia, between January and September 2007. Patients enrolled in this study underwent preoperative and postoperative, cardiac and anesthesia evaluation. Clinical presentations, ultrasound of urinary tract and preoperative laboratory investigation were recorded. All patients underwent high power green light laser prostatectomy using the green light photo vaporization system with setting of 120 watts. The intraoperative and postoperative complications and follow-up were recorded. The patient's age varied between 65-82 years with a mean age of 75.3+-8.6 years old. Seven patients presented with refractory acute urinary retention and 4 patients presented with severe lower urinary tract symptoms. The average prostate volume was 61.22 cc. All patients had uneventful intra- and postoperative course, without the intensive care. The average blood loss was insignificant and only one of the patients required blood transfusion. Foley catheters were removed one day after the procedure. All patients voided satisfactorily after removal of catheter and 8 patients complained of urgency. High power green light laser prostatectomy is a safe and effective method of treating symptomatic benign prostatic hyperplasia in patients with high operative risk. (author)

  6. Design of single-layer high-efficiency transmitting phase-gradient metasurface and high gain antenna

    Science.gov (United States)

    Zhang, Di; Yang, Xiaoqing; Su, Piqiang; Luo, Jiefang; Chen, Huijie; Yuan, Jianping; Li, Lixin

    2017-12-01

    In this paper, based on rotation phase-gradient principle, a single-layer, high-efficiency transmitting metasurface is designed and applied to high-gain antenna. In the case of circularly polarized incident wave, the PCR (polarization conversions ratio) of the metasurface element is greater than 90% in the band of 9.11-10.48 GHz. The transmitting wave emerges an anomalous refraction when left-handed circularly polarized wave are incident perpendicularly to the 1D phase-gradient metasurface, which is composed of cycle arrangement of 6 units with step value of 30°. The simulated anomalous refraction angle is 40.1°, coincided with the theoretical design value (40.6°). For further application, the 2D focused metasurface is designed to enhance the antenna performance while the left-handed circularly polarized antenna is placed at the focus. The simulated max gain is increased by 12 dB (182%) and the half-power beamwidth is reduced by 74.6°. The measured results are coincided with the simulations, which indicates the antenna has high directivity. The designed single-layer transmission metasurface has advantages of thin thickness (only 1.5 mm), high efficiency and light weight, and will have important application prospects in polarization conversion and beam control.

  7. High-order harmonic generation in laser plasma plumes

    CERN Document Server

    Ganeev, Rashid A

    2013-01-01

    This book represents the first comprehensive treatment of high-order harmonic generation in laser-produced plumes, covering the principles, past and present experimental status and important applications. It shows how this method of frequency conversion of laser radiation towards the extreme ultraviolet range matured over the course of multiple studies and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications. Significant discoveries and pioneering contributions of researchers in this field carried out in various laser scientific centers worldwide are included in this first attempt to describe the important findings in this area of nonlinear spectroscopy. "High-Order Harmonic Generation in Laser Plasma Plumes" is a self-contained and unified review of the most recent achievements in the field, such as the application of clusters (fullerenes, nanoparticles, nanotubes) for efficient harmonic generation of ultrashort laser pulses in cluster-containin...

  8. Modulating laser intensity profile ellipticity for microstructural control during metal additive manufacturing

    International Nuclear Information System (INIS)

    Roehling, Tien T.; Wu, Sheldon S.Q.; Khairallah, Saad A.; Roehling, John D.; Soezeri, S. Stefan; Crumb, Michael F.; Matthews, Manyalibo J.

    2017-01-01

    Additively manufactured (AM) metals are often highly textured, containing large columnar grains that initiate epitaxially under steep temperature gradients and rapid solidification conditions. These unique microstructures partially account for the massive property disparity existing between AM and conventionally processed alloys. Although equiaxed grains are desirable for isotropic mechanical behavior, the columnar-to-equiaxed transition remains difficult to predict for conventional solidification processes, and much more so for AM. In this study, the effects of laser intensity profile ellipticity on melt track macrostructures and microstructures were studied in 316L stainless steel. Experimental results were supported by temperature gradients and melt velocities simulated using the ALE3D multi-physics code. As a general trend, columnar grains preferentially formed with increasing laser power and scan speed for all beam profiles. However, when conduction mode laser heating occurs, scan parameters that result in coarse columnar microstructures using Gaussian profiles produce equiaxed or mixed equiaxed-columnar microstructures using elliptical profiles. By modulating spatial laser intensity profiles on the fly, site-specific microstructures and properties can be directly engineered into additively manufactured parts.

  9. ion in crossed gradient electric and magnetic fields

    Indian Academy of Sciences (India)

    Photodetachment cross-section for variousexternal fields and the laser polarization are calculated and displayed. A comparison with the photodetachment cross-section in crossed uniform electric and magnetic fields or in a single gradient electric field has been made.The agreement of our results with the above two special ...

  10. Modulation of monocytic leukemia cell function and survival by high gradient magnetic fields and mathematical modeling studies.

    Science.gov (United States)

    Zablotskii, Vitalii; Syrovets, Tatiana; Schmidt, Zoe W; Dejneka, Alexandr; Simmet, Thomas

    2014-03-01

    The influence of spatially modulated high gradient magnetic fields on cellular functions of human THP-1 leukemia cells is studied. We demonstrate that arrays of high-gradient micrometer-sized magnets induce i) cell swelling, ii) prolonged increased ROS production, and iii) inhibit cell proliferation, and iv) elicit apoptosis of THP-1 monocytic leukemia cells in the absence of chemical or biological agents. Mathematical modeling indicates that mechanical stress exerted on the cells by high magnetic gradient forces is responsible for triggering cell swelling and formation of reactive oxygen species followed by apoptosis. We discuss physical aspects of controlling cell functions by focused magnetic gradient forces, i.e. by a noninvasive and nondestructive physical approach. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Characterization of diode-laser stacks for high-energy-class solid state lasers

    Science.gov (United States)

    Pilar, Jan; Sikocinski, Pawel; Pranowicz, Alina; Divoky, Martin; Crump, P.; Staske, R.; Lucianetti, Antonio; Mocek, Tomas

    2014-03-01

    In this work, we present a comparative study of high power diode stacks produced by world's leading manufacturers such as DILAS, Jenoptik, and Quantel. The diode-laser stacks are characterized by central wavelength around 939 nm, duty cycle of 1 %, and maximum repetition rate of 10 Hz. The characterization includes peak power, electrical-to-optical efficiency, central wavelength and full width at half maximum (FWHM) as a function of diode current and cooling temperature. A cross-check of measurements performed at HiLASE-IoP and Ferdinand-Braun-Institut (FBH) shows very good agreement between the results. Our study reveals also the presence of discontinuities in the spectra of two diode stacks. We consider the results presented here a valuable tool to optimize pump sources for ultra-high average power lasers, including laser fusion facilities.

  12. A Helical Undulator Wave-guide Inverse Free-Electron Laser

    International Nuclear Information System (INIS)

    Rosenzweig, J.; Bodzin, N.; Frigola, P.; Musumeci, P.; Pellegrini, C.; Travish, G.; Joshi, C.; Tochitsky, S.

    2004-01-01

    With recent success in high gradient, high-energy gain IFEL experiments at the UCLA Neptune Laboratory, future experiments are now being contemplated. The Neptune IFEL was designed to use a tightly focused, highly diffracting, near-TW peak power 10 micron laser. This choice of laser focusing, driven by power-handling limitations of the optics near the interaction region, led to design and use of a very complex undulator, and to sensitivity to both laser misalignment and focusing errors. As these effects limited the performance of the IFEL experiment, a next generation experiment at Neptune has been studied which avoids the use of a highly diffractive laser beam through use of a waveguide. We discuss here the choice of low-loss waveguide, guided mode characteristics and likely power limitations. We also examine a preferred undulator design, which is chosen to be helical in order to maximize the acceleration achieved for a given power. With the limitations of these laser and undulator choices in mind, we show the expected performance of the IFEL using 1D simulations. Three-dimensional effects are examined, in the context of use of a solenoid for focusing and acceleration enhancement

  13. Towards shorter wavelength x-ray lasers using a high power, short pulse pump laser

    International Nuclear Information System (INIS)

    Tighe, W.; Krushelnick, K.; Valeo, E.; Suckewer, S.

    1991-05-01

    A near-terawatt, KrF* laser system, focussable to power densities >10 18 W/cm 2 has been constructed for use as a pump laser in various schemes aimed at the development of x-ray lasing below 5nm. The laser system along with output characteristics such as the pulse duration, the focal spot size, and the percentage of amplified spontaneous emission (ASE) emitted along with the laser pulse will be presented. Schemes intended to lead to shorter wavelength x-ray emission will be described. The resultant requirements on the pump laser characteristics and the target design will be outlined. Results from recent solid target experiments and two-laser experiments, showing the interaction of a high-power, short pulse laser with a preformed plasma, will be presented. 13 refs., 5 figs

  14. An All-Solid-State High Repetiton Rate Titanium:Sapphire Laser System For Resonance Ionization Laser Ion Sources

    Science.gov (United States)

    Mattolat, C.; Rothe, S.; Schwellnus, F.; Gottwald, T.; Raeder, S.; Wendt, K.

    2009-03-01

    On-line production facilities for radioactive isotopes nowadays heavily rely on resonance ionization laser ion sources due to their demonstrated unsurpassed efficiency and elemental selectivity. Powerful high repetition rate tunable pulsed dye or Ti:sapphire lasers can be used for this purpose. To counteract limitations of short pulse pump lasers, as needed for dye laser pumping, i.e. copper vapor lasers, which include high maintenance and nevertheless often only imperfect reliability, an all-solid-state Nd:YAG pumped Ti:sapphire laser system has been constructed. This could complement or even replace dye laser systems, eliminating their disadvantages but on the other hand introduce shortcomings on the side of the available wavelength range. Pros and cons of these developments will be discussed.

  15. High power lasers

    CERN Document Server

    Niku-Lari, A

    1989-01-01

    The use of lasers for the working and treatment of materials is becoming increasingly common in industry. However, certain laser applications, for example, in welding, cutting and drilling, are more widely exploited than others. Whilst the potential of lasers for the surface treatment of metals is well recognised, in practice, this particular application is a relative newcomer. The 24 papers in this volume present the latest research and engineering developments in the use of lasers for processes such as surface melting, surface alloying and cladding, and machining, as well as discussing th

  16. Control system for high power laser drilling workover and completion unit

    Science.gov (United States)

    Zediker, Mark S; Makki, Siamak; Faircloth, Brian O; DeWitt, Ronald A; Allen, Erik C; Underwood, Lance D

    2015-05-12

    A control and monitoring system controls and monitors a high power laser system for performing high power laser operations. The control and monitoring system is configured to perform high power laser operation on, and in, remote and difficult to access locations.

  17. High-power single-mode cw dye ring laser

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, H W; Stein, L; Froelich, D; Fugger, B; Welling, H [Technische Univ. Hannover (Germany, F.R.). Inst. fuer Angewandte Physik

    1977-12-01

    Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.

  18. Quantum energy duplication using super high output pulse laser

    International Nuclear Information System (INIS)

    Sugisaki, Kiwamu; Koyama, Kazuyoshi; Tanimoto, Mitsumori; Saito, Naoaki

    2000-01-01

    This study aims at elucidation on phenomena induced by strong electric field of super high output ultra short laser pulse to carry out development of basic technology required for promotion of a study on generation of high energy particle and photon using them, in order to contribute to application of super high output ultra short laser pulse and high energy plasma formed by it. In 1998 fiscal year of the last fiscal year in this study, by intending to increase the output by narrowing pulse width of the super high output laser, some basic experiments such as verification due to experiment on relativity theoretical self-convergence, generation of high energy particles, and so forth were carried out to establish a forecasting on future application. And, by conducting plasma generation experiment, self-guide and high energy particle formation experiment in plasma of super high intensity laser pulse important for its applications, and so forth, various technologies constituting foundation of future developments were developed, and more results could be obtained than those at proposal of this study. (G.K.)

  19. High power CO2 laser development with AOM integration for ultra high-speed pulses

    Science.gov (United States)

    Bohrer, Markus; Vaupel, Matthias; Nirnberger, Robert; Weinberger, Bernhard; Jamalieh, Murad

    2017-01-01

    There is a 500 billion USD world market for packaging expected to grow to a trillion in 2030. Austria plays an important role world wide for high speed laser engraving applications — especially when it comes to high end solutions. Such high end solutions are fundamental for the production of print forms for the packaging and decorating industry (e. g. cans). They are additionally used for security applications (e. g. for printing banknotes), for the textile printing industry and for creating embossing forms (e. g. for the production of dashboards in the automotive industry). High speed, high precision laser engraving needs laser resonators with very stable laser beams (400 - 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure - stable within the sub-micrometer range - a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench using hexapods, allowing to optimize the complete beam path with collimators and AOM. The major steps related to laser engraving of dry offset printing plates during the full workflow from the artists design to the printed result on an aluminum can is presented in this paper as well as laser characteristics, AOM integration and correlative CLSM and SEM investigation of the results.

  20. High-power random distributed feedback fiber laser: From science to application

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xueyuan [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Naval Academy of Armament, Beijing 100161 (China); Zhang, Hanwei; Xiao, Hu; Ma, Pengfei; Wang, Xiaolin; Zhou, Pu; Liu, Zejin [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2016-10-15

    A fiber laser based on random distributed feedback has attracted increasing attention in recent years, as it has become an important photonic device and has found wide applications in fiber communications or sensing. In this article, recent advances in high-power random distributed feedback fiber laser are reviewed, including the theoretical analyses, experimental approaches, discussion on the practical applications and outlook. It is found that a random distributed feedback fiber laser can not only act as an information photonics device, but also has the feasibility for high-efficiency/high-power generation, which makes it competitive with conventional high-power laser sources. In addition, high-power random distributed feedback fiber laser has been successfully applied for midinfrared lasing, frequency doubling to the visible and high-quality imaging. It is believed that the high-power random distributed feedback fiber laser could become a promising light source with simple and economic configurations. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Preliminary investigation into laser high voltage interaction in the case of streamer-to-leader process using a high power CO2 laser

    CSIR Research Space (South Africa)

    West, NJ

    2006-01-01

    Full Text Available This paper describes the preliminary small-scale experiments conducted in order to investigate the influence of intensely focused laser light produced by a CO2 laser on high voltage fields. The laser used operated at a maximum energy of 430 mJ per...

  2. Efficient inclusion body processing using chemical extraction and high gradient magnetic fishing

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Choe, W.S.; Middelberg, A.P.J.

    2003-01-01

    of the product-loaded supports with the aid of high gradient magnetic fields. The manufacture and testing of two types of micron-sized nonporous superparamagnetic metal chelator particles derivatized with iminodiacetic acid is described. In small-scale adsorption studies conducted with a hexahistidine tagged...... at a 60-fold increased scale using the high gradient magnetic fishing (HGMF) system to collect loaded Cu2+-chelator particles following batch adsorption of L1. Over 70% of the initial Ll present was recovered within the HGMF rig in a highly clarified form in two batch elution cycles with an overall......In this study we introduce a radical new approach for the recovery of proteins expressed in the form of inclusion bodies, involving W chemical extraction from the host cells, (ii) adsorptive capture of the target protein onto small magnetic adsorbents, and (iii) subsequent rapid collection...

  3. High gradient magnetic filters for boiler water treatment

    International Nuclear Information System (INIS)

    Harland, J.R.; Nichols, R.M.

    1977-01-01

    Heavy metal oxide suspended solids in those steam condensates recycled to the boilers produce buildup within the boiler tubes which can lead to unequal and reduced heat transfer efficiency, and indirectly, to boiler tube failures. Recommended reductions in such suspended solids in feedwater to the economizers of modern high pressure boilers to levels of under 10 ppb have been published. The industrially-available SALA-HGMF magnetic filter has achieved these desired suspended solids levels in treating steam condensates. The high gradient magnetic filter has been shown in pilot tests to achieve and even exceed the recommended low level suspended solids in a practical and efficient industrial system. Such electromagnetic filters, when combined with good system chemistry, have achieved low single number parts per billion levels of several heavy metals with very high single-pass efficiencies

  4. High-intensity laser diagnostics for OMEGA EP

    Energy Technology Data Exchange (ETDEWEB)

    Bromage, J.; Zuegel, J.D.; Bahk, S.W.; Vickery, D.S.; Waxer, L.J.; Irwin, D.; Bagnoud, V.; Boni, R.; Moore, M.D.; Jungquist, R.; Stoeckl, C. [Rochester Univ., Lab. for Laser Energetics, NY (United States)

    2006-06-15

    OMEGA EP (Extended Performance) is a new high-energy peta-watt laser system under construction at the University of Rochester's Laboratory for Laser Energetics. This paper describes our designs for two diagnostics critical to OMEGA EP's mission. The focal-spot diagnostic (FSD) is responsible for characterizing the focal spot of OMEGA EP's off-axis parabolic mirror at full energy. The ultrafast temporal diagnostic (UTD) is responsible for characterizing pulse shapes of full-energy target shots ranging in width from < 1 to 100 ps as well as setting the desired pulse width before the shot. These diagnostics will enable, for the first time, complete spatial and temporal characterization of the focus of a high-energy peta-watt laser at full energy. (authors)

  5. High-intensity laser diagnostics for OMEGA EP

    International Nuclear Information System (INIS)

    Bromage, J.; Zuegel, J.D.; Bahk, S.W.; Vickery, D.S.; Waxer, L.J.; Irwin, D.; Bagnoud, V.; Boni, R.; Moore, M.D.; Jungquist, R.; Stoeckl, C.

    2006-01-01

    OMEGA EP (Extended Performance) is a new high-energy peta-watt laser system under construction at the University of Rochester's Laboratory for Laser Energetics. This paper describes our designs for two diagnostics critical to OMEGA EP's mission. The focal-spot diagnostic (FSD) is responsible for characterizing the focal spot of OMEGA EP's off-axis parabolic mirror at full energy. The ultrafast temporal diagnostic (UTD) is responsible for characterizing pulse shapes of full-energy target shots ranging in width from < 1 to 100 ps as well as setting the desired pulse width before the shot. These diagnostics will enable, for the first time, complete spatial and temporal characterization of the focus of a high-energy peta-watt laser at full energy. (authors)

  6. Trends in high power laser applications in civil engineering

    Science.gov (United States)

    Wignarajah, Sivakumaran; Sugimoto, Kenji; Nagai, Kaori

    2005-03-01

    This paper reviews the research and development efforts made on the use of lasers for material processing in the civil engineering industry. Initial investigations regarding the possibility of using lasers in civil engineering were made in the 1960s and '70s, the target being rock excavation. At that time however, the laser powers available were too small for any practical application utilization. In the 1980's, the technology of laser surface cleaning of historically important structures was developed in Europe. In the early 1990s, techniques of laser surface modification, including glazing and coloring of concrete, roughening of granite stones, carbonization of wood were pursued, mainly in Japan. In the latter part of the decade, techniques of laser decontamination of concrete surfaces in nuclear facilities were developed in many countries, and field tests were caried out in Japan. The rapid advances in development of diode lasers and YAG lasers with high power outputs and efficiencies since the late 1990's have led to a revival of worldwide interest in the use of lasers for material processing in civil engineering. The authors believe that, in the next 10 years or so, the advent of compact high power lasers is likely to lead to increased use of lasers of material processing in the field of civil engineering.

  7. Soft apertures to shape high-power laser beams

    International Nuclear Information System (INIS)

    Lukishova, S.G.; Pashinin, P.P.; Batygov, S.K.; Terentiev, B.M.

    1989-01-01

    Soft or apodized apertures with smooth decreasing from center to edges transmission profiles are used in laser physics for beam shaping. This paper gives the results of the studies of four types of these units for UV, visible and IR lasers. They are made of glasses or crystals with the use of one of the following technologies: absorption induced by ionizing radiation; photodestruction of color centers or photooxidation of impurities ions; additive coloration; frustrated total internal reflection. The special feature of such apertures is their high optical damage resistance under the irradiation of single-pulse laser radiation. They are approximately 3-50 mm in diameter by the methods of making them give the possibility to create near-Gaussian and flat-top beams with dimensions less than 1 mm and larger than 200 mm. The results of using them in high-power single-pulse lasers are presented. Damage thresholds of these apertures in such types of lasers have been defined

  8. Achieving sensitive, high-resolution laser spectroscopy at CRIS

    Energy Technology Data Exchange (ETDEWEB)

    Groote, R. P. de [Instituut voor Kern- en Stralingsfysica, KU Leuven (Belgium); Lynch, K. M., E-mail: kara.marie.lynch@cern.ch [EP Department, CERN, ISOLDE (Switzerland); Wilkins, S. G. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Collaboration: the CRIS collaboration

    2017-11-15

    The Collinear Resonance Ionization Spectroscopy (CRIS) experiment, located at the ISOLDE facility, has recently performed high-resolution laser spectroscopy, with linewidths down to 20 MHz. In this article, we present the modifications to the beam line and the newly-installed laser systems that have made sensitive, high-resolution measurements possible. Highlights of recent experimental campaigns are presented.

  9. Target isolation system, high power laser and laser peening method and system using same

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd A.; Harris, Fritz

    2007-11-06

    A system for applying a laser beam to work pieces, includes a laser system producing a high power output beam. Target delivery optics are arranged to deliver the output beam to a target work piece. A relay telescope having a telescope focal point is placed in the beam path between the laser system and the target delivery optics. The relay telescope relays an image between an image location near the output of the laser system and an image location near the target delivery optics. A baffle is placed at the telescope focal point between the target delivery optics and the laser system to block reflections from the target in the target delivery optics from returning to the laser system and causing damage.

  10. Lasers and future high energy colliders

    International Nuclear Information System (INIS)

    Parsa, Z.

    1998-02-01

    Future high energy colliders, directions for particle physics and relationship to new technology such as lasers are discussed. Experimental approaches to explore New Physics with emphasis on the utility of high energy colliders are also discussed

  11. Stretchers and compressors for ultra-high power laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Yakovlev, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2014-05-30

    This review is concerned with pulse stretchers and compressors as key components of ultra-high power laser facilities that take advantage of chirped-pulse amplification. The potentialities, characteristics, configurations and methods for the matching and alignment of these devices are examined, with particular attention to the history of the optics of ultra-short, ultra-intense pulses before and after 1985, when the chirped-pulse amplification method was proposed, which drastically changed the view of the feasibility of creating ultra-high power laser sources. The review is intended primarily for young scientists and experts who begin to address the amplification and compression of chirped pulses, experts in laser optics and all who are interested in scientific achievements in the field of ultra-high power laser systems. (review)

  12. Large-area high-power VCSEL pump arrays optimized for high-energy lasers

    Science.gov (United States)

    Wang, Chad; Geske, Jonathan; Garrett, Henry; Cardellino, Terri; Talantov, Fedor; Berdin, Glen; Millenheft, David; Renner, Daniel; Klemer, Daniel

    2012-06-01

    Practical, large-area, high-power diode pumps for one micron (Nd, Yb) as well as eye-safer wavelengths (Er, Tm, Ho) are critical to the success of any high energy diode pumped solid state laser. Diode efficiency, brightness, availability and cost will determine how realizable a fielded high energy diode pumped solid state laser will be. 2-D Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays are uniquely positioned to meet these requirements because of their unique properties, such as low divergence circular output beams, reduced wavelength drift with temperature, scalability to large 2-D arrays through low-cost and high-volume semiconductor photolithographic processes, high reliability, no catastrophic optical damage failure, and radiation and vacuum operation tolerance. Data will be presented on the status of FLIR-EOC's VCSEL pump arrays. Analysis of the key aspects of electrical, thermal and mechanical design that are critical to the design of a VCSEL pump array to achieve high power efficient array performance will be presented.

  13. High-intensity fibre laser design for micro-machining applications

    Science.gov (United States)

    Ortiz-Neria, D. I.; Martinez-Piñón, F.; Hernandez-Escamilla, H.; Alvarez-Chavez, J. A.

    2010-11-01

    This work is focused on the design of a 250W high-intensity continuous-wave fibre optic laser with a 15μm spot size beam and a beam parameter product (BPP) of 1.8 for its use on Laser-assisted Cold Spray process (LCS) in the micro-machining areas. The metal-powder deposition process LCS, is a novel method based on Cold Spray technique (CS) assisted by laser technology. The LCS accelerates metal powders by the use of a high-pressure gas in order to achieve flash welding of particles over substrate. In LCS, the critical velocity of impact is lower with respect with CS while the powder particle is heated before the deposition by a laser beam. Furthermore, LCS does not heat the powder to achieve high temperatures as it happens in plasma processes. This property puts aside cooling problems which normally happen in sintered processes with high oxygen/nitrogen concentration levels. LCS will be used not only in deposition of thin layers. After careful design, proof of concept, experimental data, and prototype development, it should be feasible to perform micro-machining precise work with the use of the highintensity fibre laser presented in this work, and selective deposition of particles, in a similar way to the well-known Direct Metal Laser Sintering process (DMLS). The fibre laser consists on a large-mode area, Yb3+-doped, semi-diffraction limited, 25-m fibre laser cavity, operating in continuous wave regime. The fibre shows an arguably high slope-efficiency with no signs of roll-over. The measured M2 value is 1.8 and doping concentration of 15000ppm. It was made with a slight modification of the traditional MCVD technique. A full optical characterization will be presented.

  14. Current state of X-band accelerating structure high gradient test. Be held at high energy accelerator organization on April 15, 2005

    International Nuclear Information System (INIS)

    Watanabe, Ken; Higo, Toshiyasu

    2005-01-01

    XTF (X-band Test Facility, Old name is GLCTA) is the high gradient test facility for X-band acceleration. We have installed an X-band 60cm structure (KX01) in the April 2004 and have been processing it for more than 10 months. Now it is under test on long-term operation. We report here the high gradient test result to date. (author)

  15. High contrast laser marking of alumina

    Science.gov (United States)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-05-01

    Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks.

  16. Coaxial two-channel high-gradient dielectric wakefield accelerator

    Directory of Open Access Journals (Sweden)

    G. V. Sotnikov

    2009-06-01

    Full Text Available A new scheme for a dielectric wakefield accelerator is proposed that employs a cylindrical multizone dielectric structure configured as two concentric dielectric tubes with outer and inner vacuum channels for drive and accelerated bunches. Analytical and numerical studies have been carried out for such coaxial dielectric-loaded structures (CDS for high-gradient acceleration. An analytical theory of wakefield excitation by particle bunches in a multizone CDS has been formulated. Numerical calculations are presented for an example of a CDS using dielectric tubes with dielectric permittivity 5.7, having external diameters of 2.121 and 0.179 mm with inner diameters of 2.095 and 0.1 mm. An annular 5 GeV, 6 nC electron bunch with rms length of 0.035 mm energizes a wakefield on the structure axis having an accelerating gradient of ∼600  MeV/m with a transformer ratio ∼8∶1. The period of the accelerating field is ∼0.33  mm. If the width of the drive bunch channel is decreased, it is possible to obtain an accelerating gradient of >1  GeV/m while keeping the transformer ratio approximately the same. Full numerical simulations using a particle-in-cell code have confirmed results of the linear theory and furthermore have shown the important influence of the quenching wave that restricts the region of the wakefield to within several periods following the drive bunch. Numerical simulations for another example have shown nearly stable transport of drive and accelerated bunches through the CDS, using a short train of drive bunches.

  17. Fluoride materials for high peak power lasers, 17 May 1976--31 January 1977

    International Nuclear Information System (INIS)

    Folweiler, R.C.

    1977-02-01

    Single crystal fluoride optical materials were grown for potential application to laser fusion. Fluoride materials are of interest for this application, in general, because their low non-linear indices of refraction permit their use in optical components which can sustain very high peak powers without causing beam distortion. Emphasis was placed on Nd:YLF because its emission wave-lengths match the gain curve of promising amplifier materials. In addition to material growth, new feed preparation techniques were investigated and developed and certain material properties measured. The laser material, Nd:YLF, (Nd 3+ in LiYF 4 ) was grown and fabricated into laser rods. This material has laser emission at 1.047 μm and 1.053 μm, depending on the polarization selected. The former wavelength matches the peak emission wavelength of developmental Nd fluoroberyllate glasses, the latter matches Nd phosphate and fluorophosphate glasses that have low values of n 2 . The non-linear index of pure LiYF 4 was measured by Milam and Weber as 0.59 x 10 -13 esu. The concentration of Nd 3+ was varied from 1% to 4%. At higher concentrations and larger diameters a radial strain was found, sufficient to cause spiral cracking. This strain was apparently generated by a radial gradient of Nd 3+ ions. The distribution coefficient observed in one sample was 0.38. The stimulation emission coefficients were determined. Boules of KY 3 F 10 and KTb 3 F 10 were grown, with the latter suitable as a Faraday rotator material with projected low n 2 and larger Verdet constant. Experiments were performed on the systemKF-CeF 3 as a potential Faraday rotator material, and a cubic phase observed. The Ce 3+ ion has slightly lower rotary power/ion, but significantly lower cost

  18. Quantification of susceptibility change at high-concentrated SPIO-labeled target by characteristic phase gradient recognition.

    Science.gov (United States)

    Zhu, Haitao; Nie, Binbin; Liu, Hua; Guo, Hua; Demachi, Kazuyuki; Sekino, Masaki; Shan, Baoci

    2016-05-01

    Phase map cross-correlation detection and quantification may produce highlighted signal at superparamagnetic iron oxide nanoparticles, and distinguish them from other hypointensities. The method may quantify susceptibility change by performing least squares analysis between a theoretically generated magnetic field template and an experimentally scanned phase image. Because characteristic phase recognition requires the removal of phase wrap and phase background, additional steps of phase unwrapping and filtering may increase the chance of computing error and enlarge the inconsistence among algorithms. To solve problem, phase gradient cross-correlation and quantification method is developed by recognizing characteristic phase gradient pattern instead of phase image because phase gradient operation inherently includes unwrapping and filtering functions. However, few studies have mentioned the detectable limit of currently used phase gradient calculation algorithms. The limit may lead to an underestimation of large magnetic susceptibility change caused by high-concentrated iron accumulation. In this study, mathematical derivation points out the value of maximum detectable phase gradient calculated by differential chain algorithm in both spatial and Fourier domain. To break through the limit, a modified quantification method is proposed by using unwrapped forward differentiation for phase gradient generation. The method enlarges the detectable range of phase gradient measurement and avoids the underestimation of magnetic susceptibility. Simulation and phantom experiments were used to quantitatively compare different methods. In vivo application performs MRI scanning on nude mice implanted by iron-labeled human cancer cells. Results validate the limit of detectable phase gradient and the consequent susceptibility underestimation. Results also demonstrate the advantage of unwrapped forward differentiation compared with differential chain algorithms for susceptibility

  19. Proteomic investigations of the ventriculo-lumbar gradient in human CSF

    DEFF Research Database (Denmark)

    Simonsen, Anja Hviid; Bech, Sara Brynhild Winther; Laursen, Inga

    2010-01-01

    Cerebrospinal fluid (CSF) is an ideal biological material in which to search for new biomarkers for improved diagnosis of neurological diseases. During a lumbar puncture between 5 and 15 mL of CSF are obtained. Previous studies have assessed the ventriculo-lumbar concentration gradient of a number...... of specific proteins. In the present study we took a proteomics approach to investigate the possible concentration gradient of a panel of proteins and peptides in the CSF of 16 patients with neurodegenerative diseases. Using two different mass spectrometry techniques, matrix assisted laser desorption...... ionization time of flight (MALDI-TOF) and surface enhanced laser desorption ionization time of flight (SELDI-TOF), we found that only one of the investigated proteins, apolipoprotein CI, was significantly decreased between the 1st and the 10th mL of CSF. Furthermore, we confirmed previous results showing...

  20. Industrial applications of high-average power high-peak power nanosecond pulse duration Nd:YAG lasers

    Science.gov (United States)

    Harrison, Paul M.; Ellwi, Samir

    2009-02-01

    Within the vast range of laser materials processing applications, every type of successful commercial laser has been driven by a major industrial process. For high average power, high peak power, nanosecond pulse duration Nd:YAG DPSS lasers, the enabling process is high speed surface engineering. This includes applications such as thin film patterning and selective coating removal in markets such as the flat panel displays (FPD), solar and automotive industries. Applications such as these tend to require working spots that have uniform intensity distribution using specific shapes and dimensions, so a range of innovative beam delivery systems have been developed that convert the gaussian beam shape produced by the laser into a range of rectangular and/or shaped spots, as required by demands of each project. In this paper the authors will discuss the key parameters of this type of laser and examine why they are important for high speed surface engineering projects, and how they affect the underlying laser-material interaction and the removal mechanism. Several case studies will be considered in the FPD and solar markets, exploring the close link between the application, the key laser characteristics and the beam delivery system that link these together.

  1. High power YAG laser cutting; Koshutsuryoku YAG laser ni yoru setsudan gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Owaki, K. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1998-08-01

    This paper describes features of high power YAG cutting. The optical fiber transmission YAG laser machining system has some advantages in which optical path length compensation unit is not required and measures for low power loss and dust are not required, when compared with the CO2 laser system. Its application to the cutting of stainless steel plates has attracted attention. Cutting tests of SUS304 were conducted using high power YAG laser. Cutting of SUS304 plate with a thickness of 40 mm could be successfully done at the power of 3.5 kW. Cutting tests of SUS304 pipes with a thickness of 8 mm in water under the depth of 20 m were also conducted using air as assist gas at the power of 2.5 kW. Excellent results were obtained without scale deposition. For the tests by the composite beam using 3 kW and 4 kW systems, SUS304 plate with a thickness of 50 mm could be cut at the cutting speed of 0.1 m/min. Laser cutting of pipes from the internal surface was conducted using a newly developed small machining head which can rotate in the peripheral direction. Excellent quality for welding was confirmed. Cutting speed and plate thickness were improved by combining water jet cutter and YAG laser unit. 6 refs., 10 figs.

  2. High power, short pulses ultraviolet laser for the development of a new x-ray laser

    International Nuclear Information System (INIS)

    Meixler, L.; Nam, C.H.; Robinson, J.; Tighe, W.; Krushelnick, K.; Suckewer, S.; Goldhar, J.; Seely, J.; Feldman, U.

    1989-04-01

    A high power, short pulse ultraviolet laser system (Powerful Picosecond-Laser) has been developed at the Princeton Plasma Physics Laboratory (PPPL) as part of experiments designed to generate shorter wavelength x-ray lasers. With the addition of pulse compression and a final KrF amplifier the laser output is expected to have reached 1/3-1/2 TW (10 12 watts) levels. The laser system, particularly the final amplifier, is described along with some initial soft x-ray spectra from laser-target experiments. The front end of the PP-Laser provides an output of 20--30 GW (10 9 watts) and can be focussed to intensities of /approximately/10 16 W/cm 2 . Experiments using this output to examine the effects of a prepulse on laser-target interaction are described. 19 refs., 14 figs

  3. Using Spherical-Harmonics Expansions for Optics Surface Reconstruction from Gradients

    Directory of Open Access Journals (Sweden)

    Juan Manuel Solano-Altamirano

    2017-11-01

    Full Text Available In this paper, we propose a new algorithm to reconstruct optics surfaces (aka wavefronts from gradients, defined on a circular domain, by means of the Spherical Harmonics. The experimental results indicate that this algorithm renders the same accuracy, compared to the reconstruction based on classical Zernike polynomials, using a smaller number of polynomial terms, which potentially speeds up the wavefront reconstruction. Additionally, we provide an open-source C++ library, released under the terms of the GNU General Public License version 2 (GPLv2, wherein several polynomial sets are coded. Therefore, this library constitutes a robust software alternative for wavefront reconstruction in a high energy laser field, optical surface reconstruction, and, more generally, in surface reconstruction from gradients. The library is a candidate for being integrated in control systems for optical devices, or similarly to be used in ad hoc simulations. Moreover, it has been developed with flexibility in mind, and, as such, the implementation includes the following features: (i a mock-up generator of various incident wavefronts, intended to simulate the wavefronts commonly encountered in the field of high-energy lasers production; (ii runtime selection of the library in charge of performing the algebraic computations; (iii a profiling mechanism to measure and compare the performance of different steps of the algorithms and/or third-party linear algebra libraries. Finally, the library can be easily extended to include additional dependencies, such as porting the algebraic operations to specific architectures, in order to exploit hardware acceleration features.

  4. High Pressure, High Gradient RF Cavities for Muon Beam Cooling

    CERN Document Server

    Johnson, R P

    2004-01-01

    High intensity, low emittance muon beams are needed for new applications such as muon colliders and neutrino factories based on muon storage rings. Ionization cooling, where muon energy is lost in a low-Z absorber and only the longitudinal component is regenerated using RF cavities, is presently the only known cooling technique that is fast enough to be effective in the short muon lifetime. RF cavities filled with high-pressure hydrogen gas bring two advantages to the ionization technique: the energy absorption and energy regeneration happen simultaneously rather than sequentially, and higher RF gradients and better cavity breakdown behavior are possible than in vacuum due to the Paschen effect. These advantages and some disadvantages and risks will be discussed along with a description of the present and desired RF R&D efforts needed to make accelerators and colliders based on muon beams less futuristic.

  5. Uv laser triggering of high-voltage gas switches

    International Nuclear Information System (INIS)

    Woodworth, J.R.; Frost, C.A.; Green, T.A.

    1982-01-01

    Two different techniques are discussed for uv laser triggering of high-voltage gas switches using a KrF laser (248 nm) to create an ionized channel through the dielectric gas in a spark gap. One technique uses an uv laser to induce breakdown in SF 6 . For this technique, we present data that demonstrate a 1-sigma jitter of +- 150 ps for a 0.5-MV switch at 80% of its self-breakdown voltage using a low-divergence KrF laser. The other scheme uses additives to the normal dielectric gas, such as tripropylamine, which are selected to undergo resonant two-step ionization in the uv laser field

  6. Monitoring gradient profile on-line in micro- and nano-high performance liquid chromatography using conductivity detection.

    Science.gov (United States)

    Zhang, Min; Chen, Apeng; Lu, Joann J; Cao, Chengxi; Liu, Shaorong

    2016-08-19

    In micro- or nano-flow high performance liquid chromatography (HPLC), flow-splitters and gradient elutions are commonly used for reverse phase HPLC separations. When a flow splitter was used at a high split-ratio (e.g., 1000:1 or higher), the actual gradient may deviate away from the programmed gradient. Sometimes, mobile phase concentrations can deviate by as much as 5%. In this work, we noticed that the conductivity (σ) of a gradient decreased with the increasing organic-solvent fraction (φ). Based on the relationship between σ and φ, a method was developed for monitoring gradient profile on-line to record any deviations in these HPLC systems. The conductivity could be measured by a traditional conductivity detector or a capacitively coupled contactless conductivity detector (C(4)D). The method was applied for assessing the performance of an electroosmotic pump (EOP) based nano-HPLC. We also observed that σ value of the gradient changed with system pressure; a=0.0175ΔP (R(2)=0.964), where a is the percentage of the conductivity increase and ΔP is the system pressure in bar. This effect was also investigated. Copyright © 2016. Published by Elsevier B.V.

  7. Advances in high power linearly polarized fiber laser and its application

    Science.gov (United States)

    Zhou, Pu; Huang, Long; Ma, Pengfei; Xu, Jiangming; Su, Rongtao; Wang, Xiaolin

    2017-10-01

    Fiber lasers are now attracting more and more research interest due to their advantages in efficiency, beam quality and flexible operation. Up to now, most of the high power fiber lasers have random distributed polarization state. Linearlypolarized (LP) fiber lasers, which could find wide application potential in coherent detection, coherent/spectral beam combining, nonlinear frequency conversion, have been a research focus in recent years. In this paper, we will present a general review on the achievements of various kinds of high power linear-polarized fiber laser and its application. The recent progress in our group, including power scaling by using power amplifier with different mechanism, high power linearly polarized fiber laser with diversified properties, and various applications of high power linear-polarized fiber laser, are summarized. We have achieved 100 Watt level random distributed feedback fiber laser, kilowatt level continuous-wave (CW) all-fiber polarization-maintained fiber amplifier, 600 watt level average power picosecond polarization-maintained fiber amplifier and 300 watt level average power femtosecond polarization-maintained fiber amplifier. In addition, high power linearly polarized fiber lasers have been successfully applied in 5 kilowatt level coherent beam combining, structured light field and ultrasonic generation.

  8. Spectrally high performing quantum cascade lasers

    Science.gov (United States)

    Toor, Fatima

    emits at lambda = 10.8 mum for positive and lambda = 8.6 mum for negative polarity current with microsecond time delay is presented. Such a system is the first demonstration of a time and wavelength multiplexed system that uses a single QC laser. Fourth, work on the design and fabrication of a single-mode distributed feedback (DFB) QC laser emitting at lambda ≈ 7.7 mum to be used in a QC laser based photoacoustic sensor is presented. The DFB QC laser had a temperature tuning co-efficient of 0.45 nm/K for a temperature range of 80 K to 320 K, and a side mode suppression ratio of greater than 30 dB. Finally, study on the lateral mode patterns of wide ridge QC lasers is presented. The results include the observation of degenerate and non-degenerate lateral modes in wide ridge QC lasers emitting at lambda ≈ 5.0 mum. This study was conducted with the end goal of using wide ridge QC lasers in a novel technique to spatiospectrally combine multiple transverse modes to obtain an ultra high power single spot QC laser beam.

  9. Laser beams in high energy physics

    International Nuclear Information System (INIS)

    Milburn, R.H.

    1976-01-01

    Back-scattered ruby laser light from energetic electrons has facilitated a family of bubble chamber experiments in the interactions of highly polarized and quasi-monochromatic photons up to 10 GeV with 4π acceptance at the 100 to 200 event/μb level. Further studies of this sort demand the use of high-repetition-rate track chambers. To exploit the polarization and energetic purity intrinsic to the back-scattered beam one must achieve nearly two orders of magnitude increase in the average input optical power, and preferably also higher quantum energies. Prospects for this technique and its applications given modern laser capabilities and new accelerator developments are discussed

  10. A homogeneous cooling scheme investigation for high power slab laser

    Science.gov (United States)

    He, Jianguo; Lin, Weiran; Fan, Zhongwei; Chen, Yanzhong; Ge, Wenqi; Yu, Jin; Liu, Hao; Mo, Zeqiang; Fan, Lianwen; Jia, Dan

    2017-10-01

    The forced convective heat transfer with the advantages of reliability and durability is widely used in cooling the laser gain medium. However, a flow direction induced temperature gradient always appears. In this paper, a novel cooling configuration based on longitudinal forced convective heat transfer is presented. In comparison with two different types of configurations, it shows a more efficient heat transfer and more homogeneous temperature distribution. The investigation of the flow rate reveals that the higher flow rate the better cooling performance. Furthermore, the simulation results with 20 L/min flow rate shows an adequate temperature level and temperature homogeneity which keeps a lower hydrostatic pressure in the flow path.

  11. Electromagnetic design, implementation and test of a superconducting undulator with a transverse gradient field amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Afonso Rodriguez, Veronica

    2015-11-25

    This thesis describes the development of a novel superconducting transversal gradient undulator (TGU) designed to form a compact, highly brilliant laser-wakefield accelerator (LWFA) driven radiation source. A TGU in combination with a dispersive beam transport line can be employed to produce undulator radiation with natural bandwidth despite the large energy spread of the LWFA. This thesis documents the construction, first tests and characterization of the full-scale TGU.

  12. High pressure gas laser technology for atmospheric remote sensing

    Science.gov (United States)

    Javan, A.

    1980-01-01

    The development of a fixed frequency chirp-free and highly stable intense pulsed laser made for Doppler wind velocity measurements with accurate ranging is described. Energy extraction from a high pressure CO2 laser at a tunable single mode frequency is also examined.

  13. R and D toward highly repetitive laser fusion demonstration

    International Nuclear Information System (INIS)

    Satoh, Nakahiro; Matsukado, Koji; Watari, Takeshi; Sekine, Takashi; Takeuchi, Yasuki; Kawashima, Toshiyuki

    2017-01-01

    Hamamatsu Photonics conducts research on a unique continuous neutron generation method by integrating and utilizing elemental technologies such as laser, target, and measurement for laser nuclear fusion research. In addition, in collaboration with the Graduate School for the Creation of New Photonics Industries, Toyota Motor Corporation, and others, it is conducting research on laser fusion. As a high power laser of element technology, it constructed an ultrahigh intensity laser system by combining glass slab laser KURE-I and ultrahigh intensity femtosecond laser MATSU-I equipped with titanium sapphire transmitter, and achieved a peak output of 20 TW, It plans to further increase this to 100 TW. As other element technologies, it is also considering nuclear fusion fuel - target technology and light - high energy particle measurement technology. Regarding the demonstration of continuous generation of laser fusion neutrons, it performed 100 times of continuous laser beam irradiation at 1 Hz, and actually measured the number of neutrons generated. It measured 4.5x10 4 pieces of neutrons on average (maximum 10 5 ) with a frequency of 98%. Since 100% of neutron generation should occur in principle, in the future it will be necessary to enhancing laser collecting intensity and to improve solid particle number density in order to put this process into practical use as a neutron source. (A.O.)

  14. Optimized operation of dielectric laser accelerators: Single bunch

    Directory of Open Access Journals (Sweden)

    Adi Hanuka

    2018-05-01

    Full Text Available We introduce a general approach to determine the optimal charge, efficiency and gradient for laser driven accelerators in a self-consistent way. We propose a way to enhance the operational gradient of dielectric laser accelerators by leverage of beam-loading effect. While the latter may be detrimental from the perspective of the effective gradient experienced by the particles, it can be beneficial as the effective field experienced by the accelerating structure, is weaker. As a result, the constraint imposed by the damage threshold fluence is accordingly weakened and our self-consistent approach predicts permissible gradients of ∼10  GV/m, one order of magnitude higher than previously reported experimental results—with unbunched pulse of electrons. Our approach leads to maximum efficiency to occur for higher gradients as compared with a scenario in which the beam-loading effect on the material is ignored. In any case, maximum gradient does not occur for the same conditions that maximum efficiency does—a trade-off set of parameters is suggested.

  15. High-brightness fiber-coupled pump laser development

    Science.gov (United States)

    Price, Kirk; Karlsen, Scott; Leisher, Paul; Martinsen, Robert

    2010-02-01

    We report on the continued development of high brightness laser diode modules at nLIGHT Photonics. These modules, based on nLIGHT's PearlTM product platform, demonstrate excellence in output power, brightness, wavelength stabilization, and long wavelength performance. This system, based on 14 single emitters, is designed to couple diode laser light into a 105 μm fiber at an excitation NA of under 0.14. We demonstrate over 100W of optical power at 9xx nm with a diode brightness exceeding 20 MW/cm2-str with an operating efficiency of approximately 50%. Additional results show over 70W of optical coupled at 8xx nm. Record brilliance at wavelengths 14xx nm and longer will also be demonstrated, with over 15 W of optical power with a beam quality of 7.5 mm-mrad. These results of high brightness, high efficiency, and wavelength stabilization demonstrate the pump technology required for next generation solid state and fiber lasers.

  16. Ultra-short pulse, ultra-high intensity laser improvement techniques for laser-driven quantum beam science

    International Nuclear Information System (INIS)

    Kiriyama, Hiromitsu; Kando, Masaki

    2014-01-01

    Recent development activities of the Quantum Beam Research Team in JAEA are reported. The downsized, petawatt and femtosecond pulse laser is described at first. The process of the system development and utilization effort of so-called J-KAREN is explained with its time and space control system. For high contrast, OPCPA (Optical Parametric Chirped Pulse Amplification) preamplifier is adopted by using the titanium-sapphire laser system in which only the seed light pulses can be amplified. In addition, high contrast is obtained by adopting the high energy seed light to the amplifier. The system configuration of J-KAREN laser is illustrated. Typical spectra with and without OPCPA, as well as the spectra with OPCPA adjustment and without one are shown. The result of the recompressed pulses is shown in which the pulse width of 29.5 femtoseconds is close to the theoretical limit. Considering the throughput of the pulse compressor is 64 percent it is possible to generate high power laser beam of about 600 terawatts. In the supplementary budget of 2012, it has been approved to cope with the aging or obsoleteness of the system and at the same time to further sophisticate the laser using system. The upgraded laser system is named as J-KAREN-P in which the repetition rate is improved and another booster amplifier is added to increase the power. The system configuration of J-KAREN-P after the upgrading is illustrated. (S. Funahashi)

  17. Parametric Study and Multi-Criteria Optimization in Laser Cladding by a High Power Direct Diode Laser

    Science.gov (United States)

    Farahmand, Parisa; Kovacevic, Radovan

    2014-12-01

    In laser cladding, the performance of the deposited layers subjected to severe working conditions (e.g., wear and high temperature conditions) depends on the mechanical properties, the metallurgical bond to the substrate, and the percentage of dilution. The clad geometry and mechanical characteristics of the deposited layer are influenced greatly by the type of laser used as a heat source and process parameters used. Nowadays, the quality of fabricated coating by laser cladding and the efficiency of this process has improved thanks to the development of high-power diode lasers, with power up to 10 kW. In this study, the laser cladding by a high power direct diode laser (HPDDL) as a new heat source in laser cladding was investigated in detail. The high alloy tool steel material (AISI H13) as feedstock was deposited on mild steel (ASTM A36) by a HPDDL up to 8kW laser and with new design lateral feeding nozzle. The influences of the main process parameters (laser power, powder flow rate, and scanning speed) on the clad-bead geometry (specifically layer height and depth of the heat affected zone), and clad microhardness were studied. Multiple regression analysis was used to develop the analytical models for desired output properties according to input process parameters. The Analysis of Variance was applied to check the accuracy of the developed models. The response surface methodology (RSM) and desirability function were used for multi-criteria optimization of the cladding process. In order to investigate the effect of process parameters on the molten pool evolution, in-situ monitoring was utilized. Finally, the validation results for optimized process conditions show the predicted results were in a good agreement with measured values. The multi-criteria optimization makes it possible to acquire an efficient process for a combination of clad geometrical and mechanical characteristics control.

  18. Recent results in mirror based high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Nielsen, Jakob Skov; Elvang, Mads

    2004-01-01

    In this paper, recent results in high power laser cutting, obtained in reseach and development projects are presented. Two types of mirror based focussing systems for laser cutting have been developed and applied in laser cutting studies on CO2-lasers up to 12 kW. In shipyard environment cutting...... speed increase relative to state-of-the-art cutting of over 100 % has been achieved....

  19. High-efficient Nd:YAG microchip laser for optical surface scanning

    Science.gov (United States)

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

    2017-12-01

    A CW operating, compact, high-power, high-efficient diode pumped 1064nm laser, based on Nd:YAG active medium, was developed for optical surface scanning and mapping applications. To enhance the output beam quality, laser stability, and compactness, a microchip configuration was used. In this arrangement the resonator mirrors were deposited directly on to the laser crystal faces. The Nd-doping concentration was 1 at.% Nd/Y. The Nd:YAG crystal was 5mm long. The laser resonator without pumping radiation recuperation was investigated {the output coupler was transparent for pumping radiation. For the generated laser radiation the output coupler reflectivity was 95%@1064 nm. The diameter of the samples was 5 mm. For the laser pumping two arrangements were investigated. Firstly, a fibre coupled laser diode operating at wavelength 808nm was used in CW mode. The 400 ¹m fiber was delivering up to 14W of pump power amplitude to the microchip laser. The maximum CW output power of 7.2W @ 1064nm in close to TEM00 beam was obtained for incident pumping power 13.7W @ 808 nm. The differential efficiency in respect to the incident pump power reached 56 %. Secondly, a single-emitter, 1W laser diode operating at 808nm was used for Nd:YAG microchip pumping. The laser pumping was directly coupled into the microchip laser using free-space lens optics. Slope efficiency up to 70% was obtained in stable, high-quality, 1064nm laser beam with CW power up to 350mW. The system was successfully used for scanning of super-Gaussian laser mirrors reflectivity profile.

  20. Development in high speed and high quality laser cutting process in fiber reinforced plastics; FRP no laser ni yoru kosoku, kohinshitsu setsudan gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ishide, T.; Shirota, H.; Matsumoto, O. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1996-06-01

    Trimming was performed and studied by cutting KFRP, an epoxy matrix with Kevlar fiber woven thereinto, using various laser beams. The CO2 laser is capable of high-speed cutting but the product is low in quality. The surface of a cut by the YAG laser is not high in quality even with its peak output elevated. The thermally affected area is smaller under the excimer laser but it is low in cutting speed. The ablation properties of the excimer laser were investigated and the beam was shaped into a linear beam for another experiment, but it failed to attain the target speed of cutting. Next, a combination of excimer laser and CO2 laser was used for cutting. It was so designed that the preceding CO2 laser cuts the KFRP at a high speed to leave behind a carbonized layer, which is followed by a linear beam which vaporizes the carbonized layer for removal. An optical system is adopted for reshaping the excimer oscillated beam into a tube-like beam. Optical conditions were determined for a fluence value required for the removal of the carbonized layer. When the CO2 laser was set at 160W and the excimer laser at 20W, a 1mm-thick sheet was successfully cut at a speed of 16.7mm/sec. 3 refs., 7 figs.

  1. 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.

  2. High-intensity laser application in Orthodontics

    Directory of Open Access Journals (Sweden)

    Eduardo Franzotti Sant’Anna

    Full Text Available ABSTRACT Introduction: In dental practice, low-level laser therapy (LLLT and high-intensity laser therapy (HILT are mainly used for dental surgery and biostimulation therapy. Within the Orthodontic specialty, while LLLT has been widely used to treat pain associated with orthodontic movement, accelerate bone regeneration after rapid maxillary expansion, and enhance orthodontic tooth movement, HILT, in turn, has been seen as an alternative for addressing soft tissue complications associated to orthodontic treatment. Objective: The aim of this study is to discuss HILT applications in orthodontic treatment. Methods: This study describes the use of HILT in surgical treatments such as gingivectomy, ulotomy, ulectomy, fiberotomy, labial and lingual frenectomies, as well as hard tissue and other dental restorative materials applications. Conclusion: Despite the many applications for lasers in Orthodontics, they are still underused by Brazilian practitioners. However, it is quite likely that this demand will increase over the next years - following the trend in the USA, where laser therapies are more widely used.

  3. Photoemission using femtosecond laser pulses

    International Nuclear Information System (INIS)

    Srinivasan-Rao, T.; Tsang, T.; Fischer, J.

    1991-10-01

    Successful operation of short wavelength FEL requires an electron bunch of current >100 A and normalized emittance < 1 mm-mrad. Recent experiments show that RF guns with photocathodes as the electron source may be the ideal candidate for achieving these parameters. To reduce the emittance growth due to space charge and RF dynamics effects, the gun may have to operate at high field gradient (hence at high RF frequency) and a spot size small compared to the aperture. This may necessitate the laser pulse duration to be in the subpicosecond regime to reduce the energy spread. We will present the behavior of metal photocathodes upon irradiation with femtosecond laser beams, comparison of linear and nonlinear photoemission, and scalability to high currents. Theoretical estimate of the intrinsic emittance at the photocathode in the presence of the anomalous heating of the electrons, and the tolerance on the surface roughness of the cathode material will be discussed

  4. Impedance-match experiments using high intensity lasers

    International Nuclear Information System (INIS)

    Holmes, N.C.; Trainor, R.J.; Anderson, R.A.; Veeser, L.R.; Reeves, G.A.

    1981-01-01

    The results of a series of impedance-match experiments using copper-aluminum targets irradiated using the Janus Laser Facility are discussed. The results are compared to extrapolations of data obtained at lower pressures using impact techniques. The sources of errors are described and evaluated. The potential of lasers for high accuracy equation of state investigations are discussed

  5. High-energy Nd:glass laser facility for collisionless laboratory astrophysics

    International Nuclear Information System (INIS)

    Niemann, C; Constantin, C G; Schaeffer, D B; Lucky, Z; Gekelman, W; Everson, E T; Tauschwitz, A; Weiland, T; Winske, D

    2012-01-01

    A kilojoule-class laser (Raptor) has recently been activated at the Phoenix-laser-facility at the University of California Los Angeles (UCLA) for an experimental program on laboratory astrophysics in conjunction with the Large Plasma Device (LAPD). The unique combination of a high-energy laser system and the 18 meter long, highly-magnetized but current-free plasma will support a new class of plasma physics experiments, including the first laboratory simulations of quasi-parallel collisionless shocks, experiments on magnetic reconnection, or advanced laser-based diagnostics of basic plasmas. Here we present the parameter space accessible with this new instrument, results from a laser-driven magnetic piston experiment at reduced power, and a detailed description of the laser system and its performance.

  6. High beam quality and high energy short-pulse laser with MOPA

    Science.gov (United States)

    Jin, Quanwei; Pang, Yu; Jiang, JianFeng; Tan, Liang; Cui, Lingling; Wei, Bin; Sun, Yinhong; Tang, Chun

    2018-03-01

    A high energy, high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with two amplifier stages is demonstrated. The two-rod birefringence compensation was used as beam quality controlling methods, which presents a short-pulse energy of 40 mJ with a beam quality value of M2 = 1.2 at a repetition rate of 400Hz. The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns.The method of spherical aberration compensation is improved the beam quality, a M2 factor of 2.3 and an optical-to-optical efficiency of 27.7% is obtained at the maximum laser out power.The laser obtained 1.4J out energy with polarization integration.

  7. Focusing of relativistic electrons in dense plasma using a resistivity-gradient-generated magnetic switchyard.

    Science.gov (United States)

    Robinson, A P L; Key, M H; Tabak, M

    2012-03-23

    A method for producing a self-generated magnetic focussing structure for a beam of laser-generated relativistic electrons using a complex array of resistivity gradients is proposed and demonstrated using numerical simulations. The array of resistivity gradients is created by using a target consisting of alternating layers of different Z material. This new scheme is capable of effectively focussing the fast electrons even when the source is highly divergent. The application of this technique to cone-guided fast ignition inertial confinement fusion is considered, and it is shown that it may be possible to deposit over 25% of the fast electron energy into a hot spot even when the fast electron divergence angle is very large (e.g., 70° half-angle).

  8. Optical design of high power excimer laser system

    International Nuclear Information System (INIS)

    Zhang Yongsheng; Zhao Jun; Ma Lianying; Yi Aiping; Liu Jingru

    2011-01-01

    Image relay and angular multiplexing,which should be considered together in the design of high power excimer laser system, is reviewed. It's important to select proper illumination setup and laser beam shaping techniques. Given the complex and special angular multiplexing scheme in high power excimer laser systems, some detailed conceptual layout schemes are given in the paper. After a brief description of lens array and reflective telescope objective, which combine the incoming beams to a common focus, a new schematic layout which uses the final targeting optics and one optical delay line array, to realize multiplexing and de-multiplexing simultaneously is first proposed in the paper. (authors)

  9. Additive Manufacturing of High-Entropy Alloys by Laser Processing

    NARCIS (Netherlands)

    Ocelik, V.; Janssen, Niels; Smith, Stefan; De Hosson, J. Th M.

    This contribution concentrates on the possibilities of additive manufacturing of high-entropy clad layers by laser processing. In particular, the effects of the laser surface processing parameters on the microstructure and hardness of high-entropy alloys (HEAs) were examined. AlCoCrFeNi alloys with

  10. Performance of a high repetition pulse rate laser system for in-gas-jet laser ionization studies with the Leuven laser ion source LISOL

    International Nuclear Information System (INIS)

    Ferrer, R.; Sonnenschein, V.T.; Bastin, B.; Franchoo, S.; Huyse, M.; Kudryavtsev, Yu.; Kron, T.; Lecesne, N.; Moore, I.D.; Osmond, B.; Pauwels, D.; Radulov, D.; Raeder, S.; Rens, L.

    2012-01-01

    The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse energy was performed in off-line tests using stable cobalt and copper isotopes. These studies also included in-gas-jet laser spectroscopy measurements on the hyperfine structure of 63 Cu. A final run under on-line conditions in which the radioactive isotope 59 Cu (T 1/2 = 81.5 s) was produced, showed a comparable yield of the two laser systems for in-gas-cell ionization. However, a significantly improved time overlap by using the high-repetition rate laser system for in-gas-jet ionization was demonstrated by an increase of the overall duty cycle, and at the same time, pointed to the need for a better shaped atomic jet to reach higher ionization efficiencies.

  11. Large area crystallization of amorphous Si with overlapping high repetition rate laser pulses

    KAUST Repository

    Ryu, Sang-Gil

    2012-09-01

    This paper presents a pulsed laser crystallization technique, enabling large area crystallization of amorphous Si to produce grains having well-defined size and orientation. The method is developed by first determining the parameters influencing crystallization induced by single laser pulses of circular cross-sectional profile. In a second step, crystallization by overlapping round spots is examined. The experiments reveal three zones characterized by distinctly different crystallized morphologies following the laser irradiation. One of these zones corresponds to the regime of lateral crystal growth, wherein grains are driven towards the center of the spot by the radial temperature gradient. These findings are then applied to processing via line beam profiles that facilitate large area crystallization upon rapid translation of the specimen. Crystallization of extended areas hinges on the determination of the crystal growth length for a single spot. The pitch between successive pulses is then set on the basis of this information. It is shown that the pulse energy has only a weak effect on the crystal growth length. © 2012 Elsevier B.V.

  12. Static high-gradient magnetic fields affect the functionality of monocytic cells

    Czech Academy of Sciences Publication Activity Database

    Syrovets, T.; Schmidt, Z.; Buechele, B.; Zablotskyy, Vitaliy A.; Dejneka, Alexandr; Dempsey, N.; Simmet, T.

    2014-01-01

    Roč. 28, č. 1 (2014), s. 1-2 ISSN 0892-6638 Institutional support: RVO:68378271 Keywords : static high-gradient * magnet ic fields * affect the functionality * monocytic cells Subject RIV: BM - Solid Matter Physics ; Magnet ism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

  13. High-Resolution Spectroscopy of Laser Ablation Plumes Using Laser-Induced Fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark C.

    2017-02-06

    We used a CW laser as a narrow-band (~50kHz) tunable LIF excitation source to probe absorption from selected atomic transitions (Al, U etc. ) in a ns laser ablation plume. A comparison of fluorescence signal with respect to emission spectroscopy show significant increase in the magnitude and persistence from selected Al and U transitions in a LIBS plume. The high spectral resolution provided by the LIF measurement allows peaks to be easily separated even if they overlap in the emission spectra.

  14. Detailed characterization of electron sources yielding first demonstration of European X-ray Free-Electron Laser beam quality

    Directory of Open Access Journals (Sweden)

    F. Stephan

    2010-02-01

    Full Text Available The photoinjector test facility at DESY, Zeuthen site (PITZ, was built to develop and optimize photoelectron sources for superconducting linacs for high-brilliance, short-wavelength free-electron laser (FEL applications like the free-electron laser in Hamburg (FLASH and the European x-ray free-electron laser (XFEL. In this paper, the detailed characterization of two laser-driven rf guns with different operating conditions is described. One experimental optimization of the beam parameters was performed at an accelerating gradient of about 43  MV/m at the photocathode and the other at about 60  MV/m. In both cases, electron beams with very high phase-space density have been demonstrated at a bunch charge of 1 nC and are compared with corresponding simulations. The rf gun optimized for the lower gradient has surpassed all the FLASH requirements on beam quality and rf parameters (gradient, rf pulse length, repetition rate and serves as a spare gun for this facility. The rf gun studied with increased accelerating gradient at the cathode produced beams with even higher brightness, yielding the first demonstration of the beam quality required for driving the European XFEL: The geometric mean of the normalized projected rms emittance in the two transverse directions was measured to be 1.26±0.13  mm mrad for a 1-nC electron bunch. When a 10% charge cut is applied excluding electrons from those phase-space regions where the measured phase-space density is below a certain level and which are not expected to contribute to the lasing process, the normalized projected rms emittance is about 0.9 mm mrad.

  15. Modematic: a fast laser beam analyzing system for high power CO2-laser beams

    Science.gov (United States)

    Olsen, Flemming O.; Ulrich, Dan

    2003-03-01

    The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 describing test methods for laser beam parameters have been approved. To implement these methods in industry is difficult and especially for the infrared laser sources, such as the CO2-laser, the availabl analyzing systems are slow, difficult to apply and having limited reliability due to the nature of the detection methods. In an EUREKA-project the goal was defined to develop a laser beam analyzing system dedicated to high power CO2-lasers, which could fulfill the demands for an entire analyzing system, automating the time consuming pre-alignment and beam conditioning work required before a beam mode analyses, automating the analyzing sequences and data analysis required to determine the laser beam caustics and last but not least to deliver reliable close to real time data to the operator. The results of this project work will be described in this paper. The research project has led to the development of the Modematic laser beam analyzer, which is ready for the market.

  16. 2nd Topical Workshop on Laser Technology and Optics Design

    CERN Document Server

    2013-01-01

    Lasers have a variety of applications in particle accelerator operation and will play a key role in the development of future particle accelerators by improving the generation of high brightness electron and exotic ion beams and through increasing the acceleration gradient. Lasers will also make an increasingly important contribution to the characterization of many complex particle beams by means of laser-based beam diagnostics methods. The second LANET topical workshop will address the key aspects of laser technology and optics design relevant to laser application to accelerators. The workshop will cover general optics design, provide an overview of different laser sources and discuss methods to characterize beams in details. Participants will be able to choose from a range of topical areas that go deeper in more specific aspects including tuneable lasers, design of transfer lines, noise sources and their elimination and non-linear optics effects. The format of the workshop will be mainly training-based wit...

  17. High-gradient near-quench-limit operation of superconducting Tesla-type cavities in scope of the International Linear Collider

    Directory of Open Access Journals (Sweden)

    Mathieu Omet

    2014-07-01

    Full Text Available We report the successful demonstration of an ILC-like high-gradient near-quench-limit operation at the Superconducting RF Test Facility at the High Energy Accelerator Research Organization (KEK in Japan. Preparation procedures necessary for the accelerator operation were conducted, such as rf phase calibration, beam-based gradient calibration, and automated beam compensation. Test runs were performed successfully for nominal operation, high-loaded Q (Q_{L} operation, and automated P_{k}Q_{L} operation. The results are described in terms of the achieved precision and stabilities of gradients and phases.

  18. Superparamagnetic adsorbents for high-gradient magnetic fishing of lectins out of legume extracts

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Dalkiær, M.; Hubbuch, Jürgen

    2004-01-01

    This work presents the development, testing, and application in high-gradient magnetic fishing of superparamagnetic supports for adsorption of lectins. Various approaches were examined to produce affinity, mixed mode, and hydrophobic charge induction type adsorbents. In clean monocomponent systems...... affinity supports created by direct attachment of glucose or maltose to amine-terminated iron oxide particles could bind concanavalin A at levels of up to approximate to 280 mg g(-1) support with high affinity (approximate to 1 muM dissociation constants). However, the best performance was delivered......-linked adsorbents supplied sufficient competition to dissolved sugars to selectively bind concanavalin A in an extract of jack beans. The dextran-linked supports were employed in a high-gradient magnetic fishing experiment, in which concanavalin A was purified to near homogeneity from a crude, unclarified extract...

  19. New horizons for high-power lasers: applications in civil engineering

    Science.gov (United States)

    Wignarajah, Sivakumaran

    2000-01-01

    Although material processing with high power lasers has found widespread use in a variety of industries such as the automotive industry, electrical and electronics industries, aerospace industry etc., civil engineering construction is one field that has lagged behind in the use of lasers for material processing. This is in spite of the fact that a large variety of materials including ceramics, metals and plastics are used in very large quantities for civil engineering construction. The main reasons for the delay in the adopting of laser for processing construction material seem to be the high costs involved and the lack of sufficient power for processing heavy and thick materials. However, with the advent of more compact lasers with higher powers, higher efficiencies and lower photon costs, greater interest has been shown in recent years in the possible uses of high power lasers for material processing in the construction industry. The author traces some of the past work carried out both in Japan and abroad on the use of lasers in civil engineering, specially with respect to the processing of inorganic material such as concrete, natural stones, tiles and rocks. Recent developments regarding laser decontamination and laser assisted rock excavation are also introduced.

  20. The Beam Characteristics of High Power Diode Laser Stack

    Science.gov (United States)

    Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

    2018-03-01

    Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

  1. Highly efficient solar-pumped Nd:YAG laser.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana

    2011-12-19

    The recent progress in solar-pumped laser with Fresnel lens and Cr:Nd:YAG ceramic medium has revitalized solar laser researches, revealing a promising future for renewable reduction of magnesium from magnesium oxide. Here we show a big advance in solar laser collection efficiency by utilizing an economical Fresnel lens and a most widely used Nd:YAG single-crystal rod. The incoming solar radiation from the sun is focused by a 0.9 m diameter Fresnel lens. A dielectric totally internally reflecting secondary concentrator is employed to couple the concentrated solar radiation from the focal zone to a 4 mm diameter Nd:YAG rod within a conical pumping cavity. 12.3 W cw laser power is produced, corresponding to 19.3 W/m(2) collection efficiency, which is 2.9 times larger than the previous results with Nd:YAG single-crystal medium. Record-high slope efficiency of 3.9% is also registered. Laser beam quality is considerably improved by pumping a 3 mm diameter Nd:YAG rod.

  2. Fabrication Technologies of the High Gradient Accelerator Structures at 100MV/m Range

    CERN Document Server

    Wang, Juwen; Van Pelt, John; Yoneda, Charles; Gudkov, D; Riddone, Germana; Higo, Toshiyasu; Takatomi, Toshikazu

    2010-01-01

    A CERN-SLAC-KEK collaboration on high gradient X-band structure research has been established in order to demonstrate the feasibility of the CLIC baseline design for the main linac stably operating at more than 100 MV/m loaded accelerating gradient. Several prototype CLIC structures were successfully fabricated and high power tested. They operated at 105 MV/m with a breakdown rate that meets the CLIC linear collider specifications of <5×10-7/pulse/m. This paper summarizes the fabrication technologies including the mechanical design, precision machining, chemical cleaning, diffusion bonding as well as vacuum baking and all related assembly technologies. Also, the tolerances control, tuning and RF characterization will be discussed

  3. Photographic guidance for selecting flow resistance coefficients in high-gradient channels

    Science.gov (United States)

    Steven E. Yochum; Francesco Comiti; Ellen Wohl; Gabrielle C. L. David; Luca Mao

    2014-01-01

    Photographic guidance is presented to assist with the estimation of Manning’s n and Darcy-Weisbach f in high-gradient plane-bed, step-pool, and cascade channels. Reaches both with and without instream wood are included. These coefficients are necessary for the estimation of reachaverage velocity, energy loss, and...

  4. Analytic solutions for Rayleigh-Taylor growth rates in smooth density gradients

    International Nuclear Information System (INIS)

    Munro, D.H.

    1988-01-01

    The growth rate of perturbations on the shell of a laser fusion target can be estimated as √gk , where g is the shell acceleration and k is the transverse wave number of the perturbation. This formula overestimates the growth rate, and should be modified for the effects of density gradients and/or ablation of the unstable interface. The density-gradient effect is explored here analytically. With the use of variational calculus to explore all possible density profiles, the growth rate is shown to exceed √gk/(1+kL) , where L is a typical density-gradient scale length. Density profiles actually exhibiting this minimum growth rate are found

  5. THE ORIGIN OF COLOR GRADIENTS IN EARLY-TYPE SYSTEMS AND THEIR COMPACTNESS AT HIGH-z

    International Nuclear Information System (INIS)

    La Barbera, F.; De Carvalho, R. R.

    2009-01-01

    In this Letter, we present mean optical+NIR color gradient estimates for 5080 early-type galaxies (ETGs) in the grizY JHK wavebands of the Sloan Digital Sky Survey plus the UKIRT Infrared Deep Sky Survey. The color gradient is estimated as the logarithmic slope of the radial color profile in ETGs. With such a large sample size, we study the variation of the mean color gradient as a function of waveband with unprecedented accuracy. We find that (1) color gradients are mainly due, on average, to a metallicity variation of about -0.4 dex per decade in galaxy radius; and (2) a small, but significant, positive age gradient is present, on average, in ETGs, with the inner stellar population being slightly younger, by ∼0.1 dex per radial decade, than the outer one. Also, we show that the presence of a positive mean age gradient in ETGs, as found in the present study, implies their effective radius to be smaller at high-z, consistent with observations.

  6. Separation of actinides by high-gradient magnetic filtration

    International Nuclear Information System (INIS)

    Bruns, L.E.; Schliebe, M.J.

    1986-01-01

    High-gradient magnetic filtration has been identified as a candidate solid/liquid separation technique for removing actinide particulate from waste streams. Although HGMS is not intended to reduce the activity in the waste stream to below 100 nCi/g, it does offer two significant advantages: (a) selective removal of TRU solids for subsequent secondary processing and (b) reduced operating complications during solvent extraction due to solids accumulation in the interfacial region. Removal of > 95 wt% of the plutonium and americium solids is expected regardless of the solids present and their properties. Verification tests will be performed to validate this assumption

  7. An x-ray backlit Talbot-Lau deflectometer for high-energy-density electron density diagnostics

    Science.gov (United States)

    Valdivia, M. P.; Stutman, D.; Stoeckl, C.; Theobald, W.; Mileham, C.; Begishev, I. A.; Bromage, J.; Regan, S. P.

    2016-02-01

    X-ray phase-contrast techniques can measure electron density gradients in high-energy-density plasmas through refraction induced phase shifts. An 8 keV Talbot-Lau interferometer consisting of free standing ultrathin gratings was deployed at an ultra-short, high-intensity laser system using K-shell emission from a 1-30 J, 8 ps laser pulse focused on thin Cu foil targets. Grating survival was demonstrated for 30 J, 8 ps laser pulses. The first x-ray deflectometry images obtained under laser backlighting showed up to 25% image contrast and thus enabled detection of electron areal density gradients with a maximum value of 8.1 ± 0.5 × 1023 cm-3 in a low-Z millimeter sized sample. An electron density profile was obtained from refraction measurements with an error of x-ray source-size, similar to conventional radiography.

  8. Highly-reliable laser diodes and modules for spaceborne applications

    Science.gov (United States)

    Deichsel, E.

    2017-11-01

    Laser applications become more and more interesting in contemporary missions such as earth observations or optical communication in space. One of these applications is light detection and ranging (LIDAR), which comprises huge scientific potential in future missions. The Nd:YAG solid-state laser of such a LIDAR system is optically pumped using 808nm emitting pump sources based on semiconductor laser-diodes in quasi-continuous wave (qcw) operation. Therefore reliable and efficient laser diodes with increased output powers are an important requirement for a spaceborne LIDAR-system. In the past, many tests were performed regarding the performance and life-time of such laser-diodes. There were also studies for spaceborne applications, but a test with long operation times at high powers and statistical relevance is pending. Other applications, such as science packages (e.g. Raman-spectroscopy) on planetary rovers require also reliable high-power light sources. Typically fiber-coupled laser diode modules are used for such applications. Besides high reliability and life-time, designs compatible to the harsh environmental conditions must be taken in account. Mechanical loads, such as shock or strong vibration are expected due to take-off or landing procedures. Many temperature cycles with high change rates and differences must be taken in account due to sun-shadow effects in planetary orbits. Cosmic radiation has strong impact on optical components and must also be taken in account. Last, a hermetic sealing must be considered, since vacuum can have disadvantageous effects on optoelectronics components.

  9. High-current electron accelerator for gas-laser pumping

    Energy Technology Data Exchange (ETDEWEB)

    Badaliants, G R; Mamikonian, V A; Nersisian, G Ts; Papanian, V O

    1978-11-26

    A high-current source of pulsed electron beams has been developed for the pumping of UV gas lasers. The parameters of the device are: energy of 0.3-0.7 MeV pulse duration of 30 ns and current density (in a high-pressure laser chamber) of 40-100 A/sq cm. The principal feature of the device is the use of a rectangular cold cathode with incomplete discharge along the surface of the high-permittivity dielectric. Cathodes made of stainless steel, copper, and graphite were investigated.

  10. High-gradient experiment on X-band disk-loaded structures

    International Nuclear Information System (INIS)

    Higo, T.; Taniuchi, T.; Yamamoto, M.; Odagiri, J.; Tokumoto, S.; Mizuno, H.; Takata, K.; Wilson, I.; Wuensch, W.

    1993-09-01

    The high-gradient performance of two travelling-wave X-band accelerating structures 20 cm long has been studied. One of the structures, KEK, was conditioned up to an average accelerating gradient (Eav) of 68 MV/m in 600 hours, while the other, CERN, reached 85 MV/m in 50 hours. In the latter case the maximum output power was fed from the SLED system and the maximum field inside the structure was 138 MV/m. This maximum level was limited by the available power from the klystron. Operation at the Eav=50 MV/m level was found to be stable for both structures. The associated dark current at this level was less than a few μA for CERN but 20 to 30 μA for KEK. Since the two electrical designs are almost the same the difference in dark current must be attributed to the difference in the two fabrication techniques. Modified Fowler-Northeim plots of downstream dark current showed a change of slope, a kink, around 50 to 60 MV/m above which the field enhancement factor was substantially increased. (author)

  11. Experimental issues in in-situ synchrotron x-ray diffraction at high pressure and temperature by using a laser-heated diamond-anvil cell

    International Nuclear Information System (INIS)

    Yoo, C.S.

    1997-01-01

    An integrated technique of diamond-anvil cell, laser-heating and synchrotron x-ray diffraction technologies is capable of structural investigation of condensed matter in an extended region of high pressures and temperatures above 100 GPa and 3000 K. The feasibility of this technique to obtain reliable data, however, strongly depends on several experimental issues, including optical and x-ray setups, thermal gradients, pressure homogeneity, preferred orientation, and chemical reaction. In this paper, we discuss about these experimental issues together with future perspectives of this technique for obtaining accurate data

  12. Quantum Entanglement and High Brightness Laser Source

    Data.gov (United States)

    National Aeronautics and Space Administration — Our focus is on demonstrating high precision (sub-micron) laser ranging for Navigation using a unique high-sensitivity optical correlation receiver with both...

  13. High speed photography diagnostics in laser-plasma interaction experiments

    International Nuclear Information System (INIS)

    Andre, M.L.

    1988-01-01

    The authors report on their effort in the development of techniques involved in laser-plasma experiments. This includes not only laser technology but also diagnostics studies and targets design and fabrication. Among the different kind of diagnostics currently used are high speed streak cameras, fast oscilloscopes and detectors sensitive in the i.r., visible, the u.v. region and the x-rays. In this presentation the authors describe the three high power lasers which are still in operation (P 102, OctAL and PHEBUS) and the main diagnostics used to characterize the plasma

  14. Thermal Response to High-Power Holmium Laser Lithotripsy.

    Science.gov (United States)

    Aldoukhi, Ali H; Ghani, Khurshid R; Hall, Timothy L; Roberts, William W

    2017-12-01

    The aim of this study was to investigate "caliceal" fluid temperature changes during holmium laser activation/lithotripsy using settings up to 40 W power output with different irrigation flow rates. The experimental system consisted of a glass test tube (diameter 10 mm/length 75 mm) filled with deionized water, to mimic a calix. Real-time temperature was recorded using a thermocouple (Physitemp, NJ) positioned 5 mm from the bottom of the tube. A 200 μm laser fiber (Flexiva; Boston Scientific, MA) was introduced through the working channel of a disposable ureteroscope (LithoVue; Boston Scientific) and the laser fiber tip was positioned 15 mm above the bottom of the test tube. Deionized water irrigation (room temperature) through the working channel of the ureteroscope was delivered at flow rates of 0, 7-8, 14-15, and 38-40 mL/minute. A 120-W holmium laser (pulse 120; Lumenis, CA) was used. The following settings were explored: 0.5 J × 10 Hz, 1.0 J × 10 Hz, 0.5 J × 20 Hz, 1.0 J × 20 Hz, 0.5 J × 40 Hz, 1.0 J × 40 Hz, and 0.5 J × 80 Hz. During each experiment, the laser was activated continuously for 60 seconds. Temperature increased with increasing laser power output and decreasing irrigation flow rate. The highest temperature, 70.3°C (standard deviation 2.7), occurred with laser setting of 1.0 J × 40 Hz and no irrigation after 60 seconds of continuous laser firing. None of the tested laser settings and irrigation parameters produced temperature exceeding 51°C when activated for only 10 seconds of continuous laser firing. High-power holmium settings fired in long bursts with low irrigation flow rates can generate high fluid temperatures in a laboratory "caliceal" model. Awareness of this risk allows urologist to implement a variety of techniques (higher irrigation flow rates, intermittent laser activation, and potentially cooled irrigation fluid) to control and mitigate thermal

  15. Interaction of intense femtosecond laser pulses with high-Z solids

    International Nuclear Information System (INIS)

    Zhidkov, A.; Sasaki, Akira; Utsumi, Takayuki; Fukumoto, Ichirou; Tajima, Toshiki; Yoshida, Masatake; Kondo, Kenichi

    2000-01-01

    A plasma irradiated by an intense very short pulse laser can be an ultimate high brightness source of incoherent inner-shell X-ray emission of 1-30 keV. The recently developed 100 TW, 20 fs laser facility in JAERI can make considerable enhancement here. To show this a hybrid model combining hydrodynamics and collisional particle-in-cell simulations is applied. Effect of laser prepulse on the interaction of an intense s-polarized femtosecond, ∼20/40 fs, laser pulse with high-Z solid targets is studied. A new absorption mechanism originating from the interaction of the laser pulse with plasma waves excited by the relativistic component of the Lorentz force is found to increase the absorption rate over 30% even for a very short laser pulse. The obtained hot electron temperature exceeds 0.5-1 MeV at optimal conditions for absorption. Results of the simulation for lower laser pulse intensities are in good agreement with the experimental measurements of the hot electron energy distribution. (author)

  16. High energy gain electron beam acceleration by 100TW laser

    International Nuclear Information System (INIS)

    Kotaki, Hideyuki; Kando, Masaki; Kondo, Shuji; Hosokai, Tomonao; Kanazawa, Shuhei; Yokoyama, Takashi; Matoba, Toru; Nakajima, Kazuhisa

    2001-01-01

    A laser wakefield acceleration experiment using a 100TW laser is planed at JAERI-Kansai. High quality and short pulse electron beams are necessary to accelerate the electron beam by the laser. Electron beam - laser synchronization is also necessary. A microtron with a photocathode rf-gun was prepared as a high quality electron injector. The quantum efficiency (QE) of the photocathode of 2x10 -5 was obtained. A charge of 100pC from the microtron was measured. The emittance and pulse width of the electron beam was 6π mm-mrad and 10ps, respectively. In order to produce a short pulse electron beam, and to synchronize between the electron beam and the laser pulse, an inverse free electron laser (IFEL) is planned. One of problems of LWFA is the short acceleration length. In order to overcome the problem, a Z-pinch plasma waveguide will be prepared as a laser wakefield acceleration tube for 1 GeV acceleration. (author)

  17. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    R. Brian Jenkins

    2017-01-01

    Full Text Available Fiber Bragg grating (FBG temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

  18. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

    2017-01-27

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

  19. Coherent nonlinear backscattering by laser-plasma interactions

    International Nuclear Information System (INIS)

    Anderson, D.; Wilhelmsson, H.

    1974-01-01

    A theoretical analysis is carried out for the problem of coherent nonlinear backscattering of laser radiation by a high density plasma. A number of effects of direct interest to the DT-pellet fusion research is investigated. A simple physical description is introduced, which relies on a nonlinear potential formulation of the scattering equations. The simplicity and the unified nature of the approach enables one to evaluate and compare the influence on the radiation reflectivity of different effects, such as e.g. inhomogeneities, blow-off velocities, temperature gradients, laser band width and relativistic oscillatory velocities. The understanding of the role played by the various phenomena has consequently improved and it is thought that this approach should be useful for the interpretation of laser-plasma data obtained by computer simulation or laboratory experiments. The results may also be utilized to estimate how and to what extent one may avoid undesired anomalous reflection when planning new laser-plasma devices. (Auth.)

  20. Microstructure and wear resistance of laser cladded Ni-Cr-Co-Ti-V high-entropy alloy coating after laser remelting processing

    Science.gov (United States)

    Cai, Zhaobing; Cui, Xiufang; Liu, Zhe; Li, Yang; Dong, Meiling; Jin, Guo

    2018-02-01

    An attempt, combined with the technologies of laser cladding and laser remelting, has been made to develop a Ni-Cr-Co-Ti-V high entropy alloy coating. The phase composition, microstructure, micro-hardness and wear resistance (rolling friction) were studied in detail. The results show that after laser remelting, the phase composition remains unchanged, that is, as-cladded coating and as-remelted coatings are all composed of (Ni, Co)Ti2 intermetallic compound, Ti-rich phase and BCC solid solution phase. However, after laser remelting, the volume fraction of Ti-rich phase increases significantly. Moreover, the micro-hardness is increased, up to ∼900 HV at the laser remelting parameters: laser power of 1 kW, laser spot diameter of 3 mm, and laser speed of 10 mm/s. Compared to the as-cladded high-entropy alloy coating, the as-remelted high-entropy alloy coatings have high friction coefficient and low wear mass loss, indicating that the wear resistance of as-remelted coatings is improved and suggesting practical applications, like coatings on brake pads for wear protection. The worn surface morphologies show that the worn mechanism of as-cladded and as-remelted high-entropy alloy coatings are adhesive wear.

  1. High power diode laser remelting of metals

    International Nuclear Information System (INIS)

    Chmelickova, H; Tomastik, J; Ctvrtlik, R; Supik, J; Nemecek, S; Misek, M

    2014-01-01

    This article is focused on the laser surface remelting of the steel samples with predefined overlapping of the laser spots. The goal of our experimental work was to evaluate microstructure and hardness both in overlapped zone and single pass ones for three kinds of ferrous metals with different content of carbon, cast iron, non-alloy structural steel and tool steel. High power fibre coupled diode laser Laserline LDF 3600-100 was used with robotic guided processing head equipped by the laser beam homogenizer that creates rectangular beam shape with uniform intensity distribution. Each sample was treated with identical process parameters - laser power, beam diameter, focus position, speed of motion and 40% spot overlap. Dimensions and structures of the remelted zone, zone of the partial melting, heat affected zone and base material were detected and measured by means of laser scanning and optical microscopes. Hardness progress in the vertical axis of the overlapped zone from remelted surface layer to base material was measured and compared with the hardness of the single spots. The most hardness growth was found for cast iron, the least for structural steel. Experiment results will be used to processing parameters optimization for each tested material separately.

  2. Residual stress in TI6AL4V objects produced by direct metal laser sintering

    Directory of Open Access Journals (Sweden)

    Van Zyl, Ian

    2016-12-01

    Full Text Available Direct Metal Laser Sintering produces 3D objects using a layer-by- layer method in which powder is deposited in thin layers. Laser beam scans over the powder fusing powder particles as well as the previous layer. High-concentration of laser energy input leads to high thermal gradients which induce residual stress within the as- built parts. Ti6Al4V (ELI samples have been manufactured by EOSINT M280 system at prescribed by EOS process-parameters. Residual stresses were measured by XRD method. Microstructure, values and directions of principal stresses inTi6Al4V DMLS samples were analysed.

  3. Fourier domain preconditioned conjugate gradient algorithm for atmospheric tomography.

    Science.gov (United States)

    Yang, Qiang; Vogel, Curtis R; Ellerbroek, Brent L

    2006-07-20

    By 'atmospheric tomography' we mean the estimation of a layered atmospheric turbulence profile from measurements of the pupil-plane phase (or phase gradients) corresponding to several different guide star directions. We introduce what we believe to be a new Fourier domain preconditioned conjugate gradient (FD-PCG) algorithm for atmospheric tomography, and we compare its performance against an existing multigrid preconditioned conjugate gradient (MG-PCG) approach. Numerical results indicate that on conventional serial computers, FD-PCG is as accurate and robust as MG-PCG, but it is from one to two orders of magnitude faster for atmospheric tomography on 30 m class telescopes. Simulations are carried out for both natural guide stars and for a combination of finite-altitude laser guide stars and natural guide stars to resolve tip-tilt uncertainty.

  4. Thermal Gradient Cyclic Behavior of a Thermal/Environmental Barrier Coating System on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2002-01-01

    Thermal barrier and environmental barrier coatings (TBCs and EBCs) will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability of the ceramic matrix composite (CMC) engine components in harsh combustion environments. In order to develop high performance, robust coating systems for effective thermal and environmental protection of the engine components, appropriate test approaches for evaluating the critical coating properties must be established. In this paper, a laser high-heat-flux, thermal gradient approach for testing the coatings will be described. Thermal cyclic behavior of plasma-sprayed coating systems, consisting of ZrO2-8wt%Y2O3 thermal barrier and NASA Enabling Propulsion Materials (EPM) Program developed mullite+BSAS/Si type environmental barrier coatings on SiC/SiC ceramic matrix composites, was investigated under thermal gradients using the laser heat-flux rig in conjunction with the furnace thermal cyclic tests in water-vapor environments. The coating sintering and interface damage were assessed by monitoring the real-time thermal conductivity changes during the laser heat-flux tests and by examining the microstructural changes after the tests. The coating failure mechanisms are discussed based on the cyclic test results and are correlated to the sintering, creep, and thermal stress behavior under simulated engine temperature and heat flux conditions.

  5. High Power Fiber Laser Test Bed

    Data.gov (United States)

    Federal Laboratory Consortium — This facility, unique within DoD, power-combines numerous cutting-edge fiber-coupled laser diode modules (FCLDM) to integrate pumping of high power rare earth-doped...

  6. Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility

    International Nuclear Information System (INIS)

    Wu, X.L.; Yang, M.X.; Yuan, F.P.; Chen, L.; Zhu, Y.T.

    2016-01-01

    We report a design strategy to combine the benefits from both gradient structure and transformation-induced plasticity (TRIP). The resultant TRIP-gradient steel takes advantage of both mechanisms, allowing strain hardening to last to a larger plastic strain. 304 stainless steel sheets were treated by surface mechanical attrition to synthesize gradient structure with a central coarse-grained layer sandwiched between two grain-size gradient layers. The gradient layer is composed of submicron-sized parallelepiped austenite domains separated by intersecting ε-martensite plates, with increasing domain size along the depth. Significant microhardness heterogeneity exists not only macroscopically between the soft coarse-grained core and the hard gradient layers, but also microscopically between the austenite domain and ε-martensite walls. During tensile testing, the gradient structure causes strain partitioning, which evolves with applied strain, and lasts to large strains. The γ → α′ martensitic transformation is triggered successively with an increase of the applied strain and flow stress. Importantly, the gradient structure prolongs the TRIP effect to large plastic strains. As a result, the gradient structure in the 304 stainless steel provides a new route towards a good combination of high strength and ductility, via the co-operation of both the dynamic strain partitioning and TRIP effect.

  7. Diagnosing high density, fast-evolving plasmas using x-ray lasers

    International Nuclear Information System (INIS)

    Cauble, R.; Da Silva, L.B.; Barbee, T.W. Jr.

    1994-09-01

    As x-ray laser (XRL) research has matured, it has become possible to reliably utilize XRLs for applications in the laboratory. Laser coherence, high brightness and short pulse duration all make the XRL a unique tool for the diagnosis of laboratory plasmas. The high brightness of XRLs makes them well-suited for imaging and for interferometry when used in conjunction with multilayer mirrors and beamsplitters. We have utilized a soft x-ray laser in such an imaging system to examine laser-produced plasmas using radiography, moire deflectometry, and interferometry. Radiography experiments yield 100-200 ps snapshots of laser driven foils at a resolution of 1-2 μm. Moire deflectometry with an XRL has been used to probe plasmas at higher density than by optical means. Interferograms, which allow direct measurement of electron density in laser plasmas, have been obtained with this system

  8. GENERATION OF HIGH SHOCK PRESSURES BY LASER PULSES

    OpenAIRE

    Romain , J.

    1984-01-01

    Aspects of laser generated high shock pressures and results obtained over the last years are reviewed. Shock pressures up to 5 TPa inferred from shock velocity measurements are reported. Effects of laser wavelength, intensity and 2-D plasma expansion on the generated shock pressure are discussed. The hydrodynamic efficiency determined from various data including new results at 0,26 µm wavelength outlines the advantage of short wavelengths for producing very high pressures. The possibility of ...

  9. On-Chip Laser-Power Delivery System for Dielectric Laser Accelerators

    Science.gov (United States)

    Hughes, Tyler W.; Tan, Si; Zhao, Zhexin; Sapra, Neil V.; Leedle, Kenneth J.; Deng, Huiyang; Miao, Yu; Black, Dylan S.; Solgaard, Olav; Harris, James S.; Vuckovic, Jelena; Byer, Robert L.; Fan, Shanhui; England, R. Joel; Lee, Yun Jo; Qi, Minghao

    2018-05-01

    We propose an on-chip optical-power delivery system for dielectric laser accelerators based on a fractal "tree-network" dielectric waveguide geometry. This system replaces experimentally demanding free-space manipulations of the driving laser beam with chip-integrated techniques based on precise nanofabrication, enabling access to orders-of-magnitude increases in the interaction length and total energy gain for these miniature accelerators. Based on computational modeling, in the relativistic regime, our laser delivery system is estimated to provide 21 keV of energy gain over an acceleration length of 192 μ m with a single laser input, corresponding to a 108-MV/m acceleration gradient. The system may achieve 1 MeV of energy gain over a distance of less than 1 cm by sequentially illuminating 49 identical structures. These findings are verified by detailed numerical simulation and modeling of the subcomponents, and we provide a discussion of the main constraints, challenges, and relevant parameters with regard to on-chip laser coupling for dielectric laser accelerators.

  10. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical ... Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013, India ...

  11. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

    OpenAIRE

    R. Brian Jenkins; Peter Joyce; Deborah Mechtel

    2017-01-01

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initia...

  12. Numerical simulations of novel high-power high-brightness diode laser structures

    Science.gov (United States)

    Boucke, Konstantin; Rogg, Joseph; Kelemen, Marc T.; Poprawe, Reinhart; Weimann, Guenter

    2001-07-01

    One of the key topics in today's semiconductor laser development activities is to increase the brightness of high-power diode lasers. Although structures showing an increased brightness have been developed specific draw-backs of these structures lead to a still strong demand for investigation of alternative concepts. Especially for the investigation of basically novel structures easy-to-use and fast simulation tools are essential to avoid unnecessary, cost and time consuming experiments. A diode laser simulation tool based on finite difference representations of the Helmholtz equation in 'wide-angle' approximation and the carrier diffusion equation has been developed. An optimized numerical algorithm leads to short execution times of a few seconds per resonator round-trip on a standard PC. After each round-trip characteristics like optical output power, beam profile and beam parameters are calculated. A graphical user interface allows online monitoring of the simulation results. The simulation tool is used to investigate a novel high-power, high-brightness diode laser structure, the so-called 'Z-Structure'. In this structure an increased brightness is achieved by reducing the divergency angle of the beam by angular filtering: The round trip path of the beam is two times folded using internal total reflection at surfaces defined by a small index step in the semiconductor material, forming a stretched 'Z'. The sharp decrease of the reflectivity for angles of incidence above the angle of total reflection leads to a narrowing of the angular spectrum of the beam. The simulations of the 'Z-Structure' indicate an increase of the beam quality by a factor of five to ten compared to standard broad-area lasers.

  13. Purification of power plant waters with high gradient magnetic filters

    International Nuclear Information System (INIS)

    Rosenberg, R.

    1993-04-01

    This is a report of a literature survey. Magnetic high gradient filtration is suitable for separations in difficult surroundings because it can be used in high pressure and temperature, the filtration can be automated and the filter does not contain components which have to be replaced. Magnetic separators for purification of power plant waters have been manufactured commercially for a long time, but they have not always worked satisfactorily especially when separating small particles. The corrosion products in power plant waters are usually ferrimagnetic or paramagnetic and are well suited for magnetic separation. The particle sizes varies considerable but at least in nuclear power plants they are mostly in the range 0.1-30 μ, some even smaller. According to different publications most 60 Co is in particles, while other publications indicate that more than 70 % is in solution. Similarly the data on the purification efficiency of 60 Co varies significantly. Even small magnetic fields are sufficient to separate large ferrimagnetic particles, but the separation of small and paramagnetic particles requires a field more than 20 kT and the high gradient. Presently available commercial separators are so efficient that its seems not to be economically worthwhile to develop them further to improve the filtration efficiency for small particles. Instead it might be worthwhile to investigate methods to increase the particle size by water chemistry methods. (Au). (25 refs., 2 figs.)

  14. Strengthened glass for high average power laser applications

    International Nuclear Information System (INIS)

    Cerqua, K.A.; Lindquist, A.; Jacobs, S.D.; Lambropoulos, J.

    1987-01-01

    Recent advancements in high repetition rate and high average power laser systems have put increasing demands on the development of improved solid state laser materials with high thermal loading capabilities. The authors have developed a process for strengthening a commercially available Nd doped phosphate glass utilizing an ion-exchange process. Results of thermal loading fracture tests on moderate size (160 x 15 x 8 mm) glass slabs have shown a 6-fold improvement in power loading capabilities for strengthened samples over unstrengthened slabs. Fractographic analysis of post-fracture samples has given insight into the mechanism of fracture in both unstrengthened and strengthened samples. Additional stress analysis calculations have supported these findings. In addition to processing the glass' surface during strengthening in a manner which preserves its post-treatment optical quality, the authors have developed an in-house optical fabrication technique utilizing acid polishing to minimize subsurface damage in samples prior to exchange treatment. Finally, extension of the strengthening process to alternate geometries of laser glass has produced encouraging results, which may expand the potential or strengthened glass in laser systems, making it an exciting prospect for many applications

  15. High volume fabrication of laser targets using MEMS techniques

    International Nuclear Information System (INIS)

    Spindloe, C; Tomlinson, S; Green, J; Booth, N.; Tolley, M K; Arthur, G; Hall, F; Potter, R; Kar, S; Higginbotham, A

    2016-01-01

    The latest techniques for the fabrication of high power laser targets, using processes developed for the manufacture of Micro-Electro-Mechanical System (MEMS) devices are discussed. These laser targets are designed to meet the needs of the increased shot numbers that are available in the latest design of laser facilities. Traditionally laser targets have been fabricated using conventional machining or coarse etching processes and have been produced in quantities of 10s to low 100s. Such targets can be used for high complexity experiments such as Inertial Fusion Energy (IFE) studies and can have many complex components that need assembling and characterisation with high precision. Using the techniques that are common to MEMS devices and integrating these with an existing target fabrication capability we are able to manufacture and deliver targets to these systems. It also enables us to manufacture novel targets that have not been possible using other techniques. In addition, developments in the positioning systems that are required to deliver these targets to the laser focus are also required and a system to deliver the target to a focus of an F2 beam at 0.1Hz is discussed. (paper)

  16. Cutting and drilling studies using high power visible lasers

    International Nuclear Information System (INIS)

    Kautz, D.D.; Dragon, E.P.; Werve, M.E.; Hargrove, R.S.; Warner, B.E.

    1993-01-01

    High power and radiance laser technologies developed at Lawrence Livermore National Laboratory such as copper-vapor and dye lasers show great promise for material processing tasks. Evaluation of models suggests significant increases in welding, cutting, and drilling capabilities, as well as applications in emerging technologies such as micromachining, surface treatment, and stereolithography. Copper lasers currently operate at 1.8 kW output at approximately three times the diffraction limit and achieve mean time between failures of more than 1,000 hours. Dye lasers have near diffraction limited beam quality at greater than 1.0 kW. Results from cutting and drilling studies in titanium and stainless steel alloys show that cuts and holes with extremely fine features can be made with dye and copper-vapor lasers. High radiance beams produce low distortion and small heat-affected zones. The authors have accomplished very high aspect ratios (> 60:1) and features with micron scale (5-50 μm) sizes. The paper gives a description of the equipment; discusses cutting theory; and gives experimental results of cutting and drilling studies on Ti-6Al-4V and 304 stainless steel

  17. High-speed high-efficiency 500-W cw CO2 laser hermetization of metal frames of microelectronics devices

    Science.gov (United States)

    Levin, Andrey V.

    1996-04-01

    High-speed, efficient method of laser surface treatment has been developed using (500 W) cw CO2 laser. The principal advantages of CO2 laser surface treatment in comparison with solid state lasers are the basis of the method. It has been affirmed that high efficiency of welding was a consequence of the fundamental properties of metal-IR-radiation (10,6 mkm) interaction. CO2 laser hermetization of metal frames of microelectronic devices is described as an example of the proposed method application.

  18. High Power Diode Lasers with External Feedback: Overview and Prospects

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2012-01-01

    In summary, different external-cavity feedback techniques to improve the spatial beam quality and narrow the linewidth of the output beam from both BALs and TDLs are presented. Broad-area diode laser system with external-cavity feedback around 800 nm can produce several Watts of output power...... with a good beam quality. Tapered diode laser systems with external-cavity feedback around 800 and 1060 nm can deliver more than 2 W output power with diffraction-limited beam quality and can be operated in single-longitudinal mode. These high-brightness, narrow linewidth, and tunable external-cavity diode...... lasers emerge as the next generation of compact lasers that have the potential of replacing conventional high power laser systems in many existing applications....

  19. 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.

  20. High-power ultralong-wavelength Tm-doped silica fiber laser cladding-pumped with a random distributed feedback fiber laser.

    Science.gov (United States)

    Jin, Xiaoxi; Du, Xueyuan; Wang, Xiong; Zhou, Pu; Zhang, Hanwei; Wang, Xiaolin; Liu, Zejin

    2016-07-15

    We demonstrated a high-power ultralong-wavelength Tm-doped silica fiber laser operating at 2153 nm with the output power exceeding 18 W and the slope efficiency of 25.5%. A random distributed feedback fiber laser with the center wavelength of 1173 nm was employed as pump source of Tm-doped fiber laser for the first time. No amplified spontaneous emissions or parasitic oscillations were observed when the maximum output power reached, which indicates that employing 1173 nm random distributed feedback fiber laser as pump laser is a feasible and promising scheme to achieve high-power emission of long-wavelength Tm-doped fiber laser. The output power of this Tm-doped fiber laser could be further improved by optimizing the length of active fiber, reflectivity of FBGs, increasing optical efficiency of pump laser and using better temperature management. We also compared the operation of 2153 nm Tm-doped fiber lasers pumped with 793 nm laser diodes, and the maximum output powers were limited to ~2 W by strong amplified spontaneous emission and parasitic oscillation in the range of 1900-2000 nm.

  1. Development of high-power dye laser chain

    Science.gov (United States)

    Konagai, Chikara; Kimura, Hironobu; Fukasawa, Teruichiro; Seki, Eiji; Abe, Motohisa; Mori, Hideo

    2000-01-01

    Copper vapor laser (CVL) pumped dye laser (DL) system, both in a master oscillator power amplifier (MOPA) configuration, has been developed for Atomic Vapor Isotope Separation program in Japan. Dye laser output power of about 500 W has been proved in long-term operations over 200 hours. High power fiber optic delivery system is utilized in order to efficiently transport kilowatt level CVL beams to the DL MOPA. Single model CVL pumped DL oscillator has been developed and worked for 200 hours within +/- 0.1 pm wavelength stability. Phase modulator for spreading spectrum to the linewidth of hyperfine structure has been developed and demonstrated.

  2. Radio-isotope production using laser Wakefield accelerators

    International Nuclear Information System (INIS)

    Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Toth, C.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.; Reitsma, A.

    2001-01-01

    A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu 61 was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator

  3. The 1989 progress report: Laboratory for the Utilization of High-Intensity Laser

    International Nuclear Information System (INIS)

    Fabre, E.

    1989-01-01

    The 1989 progress report of the laboratory for the Utilization of High-Intensity Lasers of the Polytechnic School (France) is presented. The investigations reported were performed in the following fields: laser-matter interactions in fusion experiments, particles' laser acceleration, picoseconds and femtoseconds interactions, low-flux interactions, development of hydrodynamic codes, laser chocks simulation codes, x-ray lasers, generation of high pressures, implosion physics at 0.26 microns, dense plasmas, material's hardening by laser radiation. The published papers, the conferences and the Laboratory staff are listed [fr

  4. Beam propagation considerations in the Aurora laser system

    International Nuclear Information System (INIS)

    Rosoche, L.A.; Mc Leod, J.; Hanlon, J.A.

    1987-01-01

    Aurora is a high-power KrF laser system now being constructed for inertial confinement fusion (ICF) studies. It will use optical angular multiplexing and serial amplification by electron-beam-driven KrF amplifiers to deliver a stacked, multikilojoule 5-ns-duration laser pulse to ICF targets. The requirements of angular multiplexing KrF lasers at the multikilojoule level dictate path lengths on the order of 1 km. The inherent complicated path crossings produced by angular multiplexing and pulse stacking do not allow isolation of individual beam lines, so the optical quality of the long beam paths must be controlled. Propagation of the 248-nm light beams over long paths in air is affected by scattering, absorption thermal gradients and turbulence, beam alignment, and control and optical component figure errors

  5. High-throughput machining using high average power ultrashort pulse lasers and ultrafast polygon scanner

    Science.gov (United States)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

    2016-03-01

    In this paper, high-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (Aluminium, Copper, Stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high pulse repetition frequency picosecond laser with maximum average output power of 270 W in conjunction with a unique, in-house developed two-axis polygon scanner. Initially, different concepts of polygon scanners are engineered and tested to find out the optimal architecture for ultrafast and precision laser beam scanning. Remarkable 1,000 m/s scan speed is achieved on the substrate, and thanks to the resulting low pulse overlap, thermal accumulation and plasma absorption effects are avoided at up to 20 MHz pulse repetition frequencies. In order to identify optimum processing conditions for efficient high-average power laser machining, the depths of cavities produced under varied parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. The maximum removal rate is achieved as high as 27.8 mm3/min for Aluminium, 21.4 mm3/min for Copper, 15.3 mm3/min for Stainless steel and 129.1 mm3/min for Al2O3 when full available laser power is irradiated at optimum pulse repetition frequency.

  6. High energy KrCl electric discharge laser

    Science.gov (United States)

    Sze, Robert C.; Scott, Peter B.

    1981-01-01

    A high energy KrCl laser for producing coherent radiation at 222 nm. Output energies on the order of 100 mJ per pulse are produced utilizing a discharge excitation source to minimize formation of molecular ions, thereby minimizing absorption of laser radiation by the active medium. Additionally, HCl is used as a halogen donor which undergoes a harpooning reaction with metastable Kr.sub.M * to form KrCl.

  7. 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)

  8. High-power frequency-stabilized laser for laser cooling of metastable helium at 389 nm

    NARCIS (Netherlands)

    Koelemeij, J.C.J.; Hogervorst, W.; Vassen, W.

    2005-01-01

    A high-power, frequency-stabilized laser for cooling of metastable helium atoms using the 2 S13 →3 P23 transition at 389 nm has been developed. The 389 nm light is generated by frequency doubling of a titanium:sapphire laser in an external enhancement cavity containing a lithium-triborate nonlinear

  9. Interaction of high power ultrashort laser pulses with plasmas

    International Nuclear Information System (INIS)

    Geissler, M.

    2000-12-01

    The invention of short laser-pulses has opened a vast application range from testing ultra high-speed semiconductor devices to precision material processing, from triggering and tracing chemical reactions to sophisticated surgical applications in opthalmology and neurosurgery. In physical science, ultrashort light pulses enable researchers to follow ultrafast relaxation processes in the microcosm on time scale never before accessible and study light-matter-interactions at unprecedented intensity levels. The aim of this thesis is to investigate the interaction of ultrashort high power laser pulses with plasmas for a broad intensity range. First the ionization of atoms with intense laser fields is investigated. For sufficient strong and low frequent laser pulses, electrons can be removed from the core by a tunnel process through a potential barrier formed by the electric field of the laser. This mechanism is described by a well-established theory, but the interaction of few-cycle laser pulses with atoms can lead to regimes where the tunnel theory loses its validity. This regime is investigated and a new description of the ionization is found. Although the ionization plays a major role in many high-energy laser processes, there exist no simple and complete model for the evolution of laser pulses in field-ionizing media. A new propagation equation and the polarization response for field-ionizing media are presented and the results are compared with experimental data. Further the interaction of high power laser radiation with atoms result in nonlinear response of the electrons. The spectrum of this induced nonlinear dipole moment reaches beyond visible wavelengths into the x-ray regime. This effect is known as high harmonic generation (HHG) and is a promising tool for the generation of coherent shot wavelength radiation, but the conversions are still not efficient enough for most practical applications. Phase matching schemes to overcome the limitation are discussed

  10. Stabilized High Power Laser for Advanced Gravitational Wave Detectors

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  11. Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmas

    International Nuclear Information System (INIS)

    Li, C. K.; Seguin, F. H.; Frenje, J. A.; Manuel, M.; Casey, D.; Sinenian, N.; Petrasso, R. D.; Amendt, P. A.; Landen, O. L.; Rygg, J. R.; Town, R. P. J.; Betti, R.; Meyerhofer, D. D.; Delettrez, J.; Knauer, J. P.; Marshall, F.; Sangster, T. C.; Smalyuk, V. A.; Soures, J. M.; Shvarts, D.

    2009-01-01

    Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields produced in laser-foil interactions and during the implosion of inertial-confinement-fusion capsules. These experiments resulted in the first observations of several new and important features: (1) observations of the generation, decay dynamics, and instabilities of megagauss B fields in laser-driven planar plastic foils, (2) the observation of radial E fields inside an imploding capsule, which are initially directed inward, reverse direction during deceleration, and are likely related to the evolution of the electron pressure gradient, and (3) the observation of many radial filaments with complex electromagnetic field striations in the expanding coronal plasmas surrounding the capsule. The physics behind and implications of such observed fields are discussed.

  12. Bright ultrashort x-rays from intense subpicosecond laser-plasma interactions

    International Nuclear Information System (INIS)

    Umstadter, D.

    1995-01-01

    Short-pulse, high-intensity lasers interacting with solid targets make possible the study of a new class of laser-plasma interactions. They are unique because during the ultrashort laser pulse relatively little expansion occurs, and the density scale length remains much less than the laser wavelength. This makes possible the direct deposition of a significant amount of the laser energy at close to solid density. Steep plasma temperature and density gradients subsequently cause rapid cooling, resulting in highly non-equilibrium conditions and the concurrent emission of extremely bright ultrashort x-ray pulses. In this study, the latter are investigated experimentally with temporally and spectrally resolved soft x-ray diagnostics. The emitted x-ray spectra from solid targets with various atomic numbers are characterized for a laser pulse width τ l ∼ 400 fs. These ultrashort x rays may be used as (1) a diagnostic of solid-density plasma conditions, (2) a tool for the study of radiation hydrodynamics in a parameter regime that is otherwise inaccessible, and (3) a source for time-resolved diffraction, spectroscopy, or microscopy studies of transient chemical, biological or physical phenomena

  13. Combined resistive and laser heating technique for in situ radial X-ray diffraction in the diamond anvil cell at high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Miyagi, Lowell [Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 (United States); Department of Earth Sciences, Montana State University, Bozeman, Montana 59717 (United States); Kanitpanyacharoen, Waruntorn; Kaercher, Pamela; Wenk, Hans-Rudolf; Alarcon, Eloisa Zepeda [Department of Earth and Planetary Science, University of California, Berkeley, California 94720 (United States); Raju, Selva Vennila [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); HiPSEC, Department of Physics, University of Nevada, Las Vegas, Nevada 89154 (United States); Knight, Jason; MacDowell, Alastair [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); Williams, Quentin [Department of Earth and Planetary Science, University of California, Santa Cruz, California 95064 (United States)

    2013-02-15

    To extend the range of high-temperature, high-pressure studies within the diamond anvil cell, a Liermann-type diamond anvil cell with radial diffraction geometry (rDAC) was redesigned and developed for synchrotron X-ray diffraction experiments at beamline 12.2.2 of the Advanced Light Source. The rDAC, equipped with graphite heating arrays, allows simultaneous resistive and laser heating while the material is subjected to high pressure. The goals are both to extend the temperature range of external (resistive) heating and to produce environments with lower temperature gradients in a simultaneously resistive- and laser-heated rDAC. Three different geomaterials were used as pilot samples to calibrate and optimize conditions for combined resistive and laser heating. For example, in Run1, FeO was loaded in a boron-mica gasket and compressed to 11 GPa then gradually resistively heated to 1007 K (1073 K at the diamond side). The laser heating was further applied to FeO to raise temperature to 2273 K. In Run2, Fe-Ni alloy was compressed to 18 GPa and resistively heated to 1785 K (1973 K at the diamond side). The combined resistive and laser heating was successfully performed again on (Mg{sub 0.9}Fe{sub 0.1})O in Run3. In this instance, the sample was loaded in a boron-kapton gasket, compressed to 29 GPa, resistive-heated up to 1007 K (1073 K at the diamond side), and further simultaneously laser-heated to achieve a temperature in excess of 2273 K at the sample position. Diffraction patterns obtained from the experiments were deconvoluted using the Rietveld method and quantified for lattice preferred orientation of each material under extreme conditions and during phase transformation.

  14. Conjugate-Gradient Neural Networks in Classification of Multisource and Very-High-Dimensional Remote Sensing Data

    Science.gov (United States)

    Benediktsson, J. A.; Swain, P. H.; Ersoy, O. K.

    1993-01-01

    Application of neural networks to classification of remote sensing data is discussed. Conventional two-layer backpropagation is found to give good results in classification of remote sensing data but is not efficient in training. A more efficient variant, based on conjugate-gradient optimization, is used for classification of multisource remote sensing and geographic data and very-high-dimensional data. The conjugate-gradient neural networks give excellent performance in classification of multisource data, but do not compare as well with statistical methods in classification of very-high-dimentional data.

  15. Theoretical interpretations of enhanced laser light absorption

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1975-01-01

    Intense laser light is not efficiently absorbed classically but can be absorbed by its conversion to electron plasma waves near the critical density. The physical mechanisms for this conversion are discussed, and some simple estimates for heating by plasma waves are applied to some recent experiments. Several effects which strongly influence the absorption of high intensity light are emphasized, including a nonlinear steepening of the plasma density profile which is demonstrated in computer simulations. Finally the possibility of an induced reflection of laser light due to instabilities in the underdense plasma before the critical density is also discussed. Such stimulated reflection can be particularly important in plasmas with very long density gradients. (U.S.)

  16. High energy X-ray diffraction study of a dental ceramics–titanium functional gradient material prepared by field assisted sintering technique

    International Nuclear Information System (INIS)

    Witte, K.; Bodnar, W.; Schell, N.; Lang, H.; Burkel, E.

    2014-01-01

    A functional gradient material with eleven layers composed of a dental ceramics and titanium was successfully consolidated using field assisted sintering technique in a two-step sintering process. High energy X-ray diffraction studies on the gradient were performed at High Energy Material Science beamline at Desy in Hamburg. Phase composition, crystal unit edges and lattice mismatch along the gradient were determined applying Rietveld refinement procedure. Phase analysis revealed that the main crystalline phase present in the gradient is α-Ti. Crystallinity increases stepwisely along the gradient with a decreasing increment between every next layer, following rather the weight fraction of titanium. The crystal unit edge a of titanium remains approximately constant with a value of 2.9686(1) Å, while c is reduced with increasing amount of titanium. In the layer with pure titanium the crystal unit edge c is constant with a value of 4.7174(2) Å. The lattice mismatch leading to an internal stress was calculated over the whole gradient. It was found that the maximal internal stress in titanium embedded in the studied gradient is significantly smaller than its yield strength, which implies that the structure of titanium along the whole gradient is mechanically stable. - Highlights: • High energy XRD studies of dental ceramics–Ti gradient material consolidated by FAST. • Phase composition, crystallinity and lattice parameters are determined. • Crystallinity increases stepwisely along the gradient following weight fraction of Ti. • Lattice mismatch leading to internal stress is calculated over the whole gradient. • Internal stress in α-Ti embedded in the gradient is smaller than its yield strength

  17. Research of narrow pulse width, high repetition rate, high output power fiber lasers for deep space exploration

    Science.gov (United States)

    Tang, Yan-feng; Li, Hong-zuo; Wang, Yan; Hao, Zi-qiang; Xiao, Dong-Ya

    2013-08-01

    As human beings expand the research in unknown areas constantly, the deep space exploration has become a hot research topic all over the world. According to the long distance and large amount of information transmission characteristics of deep space exploration, the space laser communication is the preferred mode because it has the advantages of concentrated energy, good security, and large information capacity and interference immunity. In a variety of laser source, fibre-optical pulse laser has become an important communication source in deep space laser communication system because of its small size, light weight and large power. For fiber lasers, to solve the contradiction between the high repetition rate and the peak value power is an important scientific problem. General Q technology is difficult to obtain a shorter pulse widths, This paper presents a DFB semiconductor laser integrated with Electro-absorption modulator to realize the narrow pulse width, high repetition rate of the seed source, and then using a two-cascaded high gain fiber amplifier as amplification mean, to realize the fibre-optical pulse laser with pulse width 3ns, pulse frequency 200kHz and peak power 1kW. According to the space laser atmospheric transmission window, the wavelength selects for 1.06um. It is adopted that full fibre technology to make seed source and amplification, pumping source and amplification of free-space coupled into fiber-coupled way. It can overcome that fibre lasers are vulnerable to changes in external conditions such as vibration, temperature drift and other factors affect, improving long-term stability. The fiber lasers can be modulated by PPM mode, to realize high rate modulation, because of its peak power, high transmission rate, narrow pulse width, high frequency stability, all technical indexes meet the requirements of the exploration of deep space communication technology.

  18. Generation of Ultra-high Intensity Laser Pulses

    International Nuclear Information System (INIS)

    Fisch, N.J.; Malkin, V.M.

    2003-01-01

    Mainly due to the method of chirped pulse amplification, laser intensities have grown remarkably during recent years. However, the attaining of very much higher powers is limited by the material properties of gratings. These limitations might be overcome through the use of plasma, which is an ideal medium for processing very high power and very high total energy. A plasma can be irradiated by a long pump laser pulse, carrying significant energy, which is then quickly depleted in the plasma by a short counterpropagating pulse. This counterpropagating wave effect has already been employed in Raman amplifiers using gases or plasmas at low laser power. Of particular interest here are the new effects which enter in high power regimes. These new effects can be employed so that one high-energy optical system can be used like a flashlamp in what amounts to pumping the plasma, and a second low-power optical system can be used to extract quickly the energy from the plasma and focus it precisely. The combined system can be very compact. Thus, focused intensities more than 10 25 W/cm 2 can be contemplated using existing optical elements. These intensities are several orders of magnitude higher than what is currently available through chirped pump amplifiers

  19. How a High-Gradient Magnetic Field Could Affect Cell Life

    Science.gov (United States)

    Zablotskii, Vitalii; Polyakova, Tatyana; Lunov, Oleg; Dejneka, Alexandr

    2016-01-01

    The biological effects of high-gradient magnetic fields (HGMFs) have steadily gained the increased attention of researchers from different disciplines, such as cell biology, cell therapy, targeted stem cell delivery and nanomedicine. We present a theoretical framework towards a fundamental understanding of the effects of HGMFs on intracellular processes, highlighting new directions for the study of living cell machinery: changing the probability of ion-channel on/off switching events by membrane magneto-mechanical stress, suppression of cell growth by magnetic pressure, magnetically induced cell division and cell reprograming, and forced migration of membrane receptor proteins. By deriving a generalized form for the Nernst equation, we find that a relatively small magnetic field (approximately 1 T) with a large gradient (up to 1 GT/m) can significantly change the membrane potential of the cell and thus have a significant impact on not only the properties and biological functionality of cells but also cell fate. PMID:27857227

  20. How a High-Gradient Magnetic Field Could Affect Cell Life

    Science.gov (United States)

    Zablotskii, Vitalii; Polyakova, Tatyana; Lunov, Oleg; Dejneka, Alexandr

    2016-11-01

    The biological effects of high-gradient magnetic fields (HGMFs) have steadily gained the increased attention of researchers from different disciplines, such as cell biology, cell therapy, targeted stem cell delivery and nanomedicine. We present a theoretical framework towards a fundamental understanding of the effects of HGMFs on intracellular processes, highlighting new directions for the study of living cell machinery: changing the probability of ion-channel on/off switching events by membrane magneto-mechanical stress, suppression of cell growth by magnetic pressure, magnetically induced cell division and cell reprograming, and forced migration of membrane receptor proteins. By deriving a generalized form for the Nernst equation, we find that a relatively small magnetic field (approximately 1 T) with a large gradient (up to 1 GT/m) can significantly change the membrane potential of the cell and thus have a significant impact on not only the properties and biological functionality of cells but also cell fate.

  1. Full magnetic gradient tensor from triaxial aeromagnetic gradient measurements: Calculation and application

    Science.gov (United States)

    Luo, Yao; Wu, Mei-Ping; Wang, Ping; Duan, Shu-Ling; Liu, Hao-Jun; Wang, Jin-Long; An, Zhan-Feng

    2015-09-01

    The full magnetic gradient tensor (MGT) refers to the spatial change rate of the three field components of the geomagnetic field vector along three mutually orthogonal axes. The tensor is of use to geological mapping, resources exploration, magnetic navigation, and others. However, it is very difficult to measure the full magnetic tensor gradient using existing engineering technology. We present a method to use triaxial aeromagnetic gradient measurements for deriving the full MGT. The method uses the triaxial gradient data and makes full use of the variation of the magnetic anomaly modulus in three dimensions to obtain a self-consistent magnetic tensor gradient. Numerical simulations show that the full MGT data obtained with the proposed method are of high precision and satisfy the requirements of data processing. We selected triaxial aeromagnetic gradient data from the Hebei Province for calculating the full MGT. Data processing shows that using triaxial tensor gradient data allows to take advantage of the spatial rate of change of the total field in three dimensions and suppresses part of the independent noise in the aeromagnetic gradient. The calculated tensor components have improved resolution, and the transformed full tensor gradient satisfies the requirement of geological mapping and interpretation.

  2. Development of laser diode-pumped high average power solid-state laser for the pumping of Ti:sapphire CPA system

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yoichiro; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Harayama, Sayaka; Oba, Masaki; Matoba, Tohru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Laser diode pumped all solid state, high repetition frequency (PRF) and high energy Nd:YAG laser using zigzag slab crystals has been developed for the pumping source of Ti:sapphire CPA system. The pumping laser installs two main amplifiers which compose ring type amplifier configuration. The maximum amplification gain of the amplifier system is 140 and the condition of saturated amplification is achieved with this high gain. The average power of fundamental laser radiation is 250 W at the PRF of 200 Hz and the pulse duration is around 20 ns. The average power of second harmonic is 105 W at the PRF of 170 Hz and the pulse duration is about 16 ns. The beam profile of the second harmonic is near top hat and will be suitable for the pumping of Ti:sapphire laser crystal. The wall plug efficiency of the laser is 2.0 %. (author)

  3. High brightness diode-pumped organic solid-state laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien, E-mail: sebastien.forget@univ-paris13.fr [Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430, Villetaneuse (France); CNRS, UMR 7538, LPL, F-93430, Villetaneuse (France)

    2015-02-02

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  4. Visible high power fiber coupled diode lasers

    Science.gov (United States)

    Köhler, Bernd; Drovs, Simon; Stoiber, Michael; Dürsch, Sascha; Kissel, Heiko; Könning, Tobias; Biesenbach, Jens; König, Harald; Lell, Alfred; Stojetz, Bernhard; Löffler, Andreas; Strauß, Uwe

    2018-02-01

    In this paper we report on further development of fiber coupled high-power diode lasers in the visible spectral range. New visible laser modules presented in this paper include the use of multi single emitter arrays @ 450 nm leading to a 120 W fiber coupled unit with a beam quality of 44 mm x mrad, as well as very compact modules with multi-W output power from 405 nm to 640 nm. However, as these lasers are based on single emitters, power scaling quickly leads to bulky laser units with a lot of optical components to be aligned. We also report on a new approach based on 450 nm diode laser bars, which dramatically reduces size and alignment effort. These activities were performed within the German government-funded project "BlauLas": a maximum output power of 80 W per bar has been demonstrated @ 450 nm. We show results of a 200 μm NA0.22 fiber coupled 35 W source @ 450 nm, which has been reduced in size by a factor of 25 compared to standard single emitter approach. In addition, we will present a 200 μm NA0.22 fiber coupled laser unit with an output power of 135 W.

  5. High pressure X-ray preionized TEMA-CO2 laser

    Science.gov (United States)

    Bonnie, R. J. M.; Witteman, W. J.

    1987-09-01

    The construction of a high-pressure (up to 20 atm) transversely excited CO2 laser using transverse X-ray preionization is described. High pressure operation was found to be greatly improved in comparison to UV-preionized systems. Homogeneous discharges have been achieved in the pressure range 5-20 atm, yielding a specific laser output in the order of 35 J/l.

  6. Characterization of a plasma produced using a high power laser with a gas puff target for x-ray laser experiments

    International Nuclear Information System (INIS)

    Fiedorowicz, H.; Bartnik, A.; Gac, K.; Parys, P.; Szczurek, M.; Tyl, J.

    1995-01-01

    A high temperature, high density plasma can be produced by using a nanosecond, high-power laser with a gas puff target. The gas puff target is formed by puffing a small amount of gas from a high-pressure reservoir through a nozzle into a vacuum chamber. In this paper we present the gas puff target specially designed for x-ray laser experiments. The solenoid valve with the nozzle in the form of a slit 0.3-mm wide and up to 40-mm long, allows to form an elongated gas puff suitable for the creation of an x-ray laser active medium by its perpendicular irradiation with the use of a laser beam focused to a line. Preliminary results of the experiments on the laser irradiation of the gas puff targets, produced by the new valve, show that hot plasma suitable for x-ray lasers is created

  7. Characteristics of high gradient insulators for accelerator and high power flow applications

    International Nuclear Information System (INIS)

    Elizondo, J.M.; Krogh, M.L.; Smith, D.

    1997-07-01

    The high gradient insulator has been demonstrated to operate at levels comparable or better than special geometry or coated insulators. Some patented insulator configurations allow for sophisticated accelerator structures, high power flow interfaces, and microwave applications not previously possible. Sophisticated manufacturing techniques available at AlliedSignal FM and T made this development possible. Bipolar and high power flow applications are specially suited for present insulator designs. The insulator shows a beneficial effect when used under RF fields or RF structures. These insulators can be designed, to a first approximation, from simple electron flight path equations. With a recently developed model of surface flashover physics the authors completed a set of design calculations that include effects such as layer density and dielectric/metal thickness. Experimental data, obtained in the last few years of development, is presented and reviewed. Several insulator fabrication characteristics, indicating critical design parameters, are also presented

  8. High and ulta-high gradient quadrupole magnets

    International Nuclear Information System (INIS)

    Brunk, W.O.; Walz, D.R.

    1985-05-01

    Small bore conventional dc quadrupoles with apertures from 1 to 2.578cm were designed and prototypes built and measured. New fabrication techniques including the use of wire electric discharge milling (EDM) to economically generate the pole tip contours and aperture tolerances are described. Magnetic measurement data from a prototype of a 1cm aperture quadrupole with possible use in future e + /e - super colliders are presented. At a current of 400A, the lens achieved a gradient of 2.475 T/cm, and had an efficiency of 76.6%

  9. Photodetachment of H ion in crossed gradient electric and magnetic ...

    Indian Academy of Sciences (India)

    2016-10-13

    Oct 13, 2016 ... ion in a gradient electric field, the Hamiltonian of the detached electron has three degrees of freedom, which makes the dynamical behaviour of the detached electron complex. Photodetachment cross-section for vari- ous external fields and the laser polarization are calculated and displayed. A comparison ...

  10. Quantitative and Qualitative Aspects of Gas-Metal-Oxide Mass Transfer in High-Temperature Confocal Scanning Laser Microscopy

    Science.gov (United States)

    Piva, Stephano P. T.; Pistorius, P. Chris; Webler, Bryan A.

    2018-05-01

    During high-temperature confocal scanning laser microscopy (HT-CSLM) of liquid steel samples, thermal Marangoni flow and rapid mass transfer between the sample and its surroundings occur due to the relatively small sample size (diameter around 5 mm) and large temperature gradients. The resulting evaporation and steel-slag reactions tend to change the chemical composition in the metal. Such mass transfer effects can change observed nonmetallic inclusions. This work quantifies oxide-metal-gas mass transfer of solutes during HT-CSLM experiments using computational simulations and experimental data for (1) dissolution of MgO inclusions in the presence and absence of slag and (2) Ca, Mg-silicate inclusion changes upon exposure of a Si-Mn-killed steel to an oxidizing gas atmosphere.

  11. High Power Laser Laboratory at the Institute of Plasma Physics and Laser Microfusion: equipment and preliminary research

    Directory of Open Access Journals (Sweden)

    Zaraś-Szydłowska Agnieszka

    2015-06-01

    Full Text Available The purpose of this paper is to present the newly-opened High Power Laser Laboratory (HPLL at the Institute of Plasma Physics and Laser Microfusion (IPPLM. This article describes the laser, the main laboratory accessories and the diagnostic instruments. We also present preliminary results of the first experiment on ion and X-ray generation from laser-produced plasma that has been already performed at the HPLL.

  12. A possibility of local measurements of ion temperature in a high-temperature plasma by laser induced ionization

    International Nuclear Information System (INIS)

    Kantor, M

    2012-01-01

    A new diagnostic for local measurements of ion temperature and drift velocity in fusion plasmas is proposed in the paper. The diagnostic is based on laser induced ionization of excited hydrogen and deuterium atoms from the levels which ionization energy less than the laser photon energy. A high intensive laser beam ionizes nearly all the excited atoms in the beam region resulting in a quench of spontaneous line emission of the appropriate optical transitions. The measurements of the quenching emission have been used in the past for local measurements of hydrogen atom density in tokamak plasma. The idea of the new diagnostic is spectral resolution of the quenching emission. The measured spectrum relates directly to the velocity distribution of the excited atoms. This distribution is strongly coupled to the distribution of the hydrogen atoms at the ground state. So, the spectral resolution of quenching emission is a way of local measurements of the temperature and drift velocity of hydrogen atoms in plasma. The temperature of hydrogen atoms is well coupled to the local ion temperature as long as the mean free path of the atoms is shorter than the ion gradient length in plasma. In this case the new diagnostic can provide local measurements of ion temperature in plasma. The paper considers technical capabilities of the diagnostic, physical restrictions of its application and interpretation of the measurements.

  13. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode

    DEFF Research Database (Denmark)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus

    2012-01-01

    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solu...

  14. Fiber fuse behavior in kW-level continuous-wave double-clad field laser

    International Nuclear Information System (INIS)

    Sun Jun-Yi; Xiao Qi-Rong; Li Dan; Wang Xue-Jiao; Zhang Hai-Tao; Gong Ma-Li; Yan Ping

    2016-01-01

    In this study, original experimental data for fiber fuse in kW-level continuous-wave (CW) high power double-clad fiber (DCF) laser are reported. The propagating velocity of the fuse is 9.68 m/s in a 3.1-kW Yb-doped DCF laser. Three other cases in Yb-doped DCF are also observed. We think that the ignition of fiber fuse is caused by thermal mechanism, and the formation of bullet-shaped tracks is attributed to the optical discharge and temperature gradient. The inducements of initial fuse and formation of bullet-shaped voids are analyzed. This investigation of fiber fuse helps better understand the fiber fuse behavior, in order to avoid the catastrophic destruction caused by fiber fuse in high power fiber laser. (paper)

  15. Enhanced high harmonic generation driven by high-intensity laser in argon gas-filled hollow core waveguide

    International Nuclear Information System (INIS)

    Cassou, Kevin; Daboussi, Sameh; Hort, Ondrej; Descamps, Dominique; Petit, Stephane; Mevel, Eric; Constant, Eric; Guilbaud, Oilvier; Kazamias, Sophie

    2014-01-01

    We show that a significant enhancement of the photon flux produced by high harmonic generation can be obtained through guided configuration at high laser intensity largely above the saturation intensity. We identify two regimes. At low pressure, we observe an intense second plateau in the high harmonic spectrum in argon. At relatively high pressure, complex interplay between strongly time-dependent ionization processes and propagation effects leads to important spectral broadening without loss of spectral brightness. We show that the relevant parameter for this physical process is the product of laser peak power by gas pressure. We compare source performances with high harmonic generation using a gas jet in loose focusing geometry and conclude that the source developed is a good candidate for injection devices such as seeded soft x-ray lasers or free electron lasers in the soft x-ray range. (authors)

  16. Combinatorial MAPLE gradient thin film assemblies signalling to human osteoblasts

    International Nuclear Information System (INIS)

    Axente, Emanuel; Sima, Felix; Elena Sima, Livia; Serban, Natalia; Ristoscu, Carmen; Mihailescu, Ion N; Erginer, Merve; Toksoy Oner, Ebru; Eroglu, Mehmet S; Petrescu, Stefana M

    2014-01-01

    There is increased interest in smart bioactive materials to control tissue regeneration for the engineering of cell instructive scaffolds. We introduced combinatorial matrix-assisted pulsed laser evaporation (C-MAPLE) as a new method for the fabrication of organic thin films with a compositional gradient. Synchronized C-MAPLE of levan and oxidized levan was employed to assemble a two-compound biopolymer film structure. The gradient of the film composition was validated by fluorescence microscopy. In this study, we investigated the cell response induced by the compositional gradient using imaging of early osteoblast attachment and analysis of signalling phosphoprotein expression. Cells attached along the gradient in direct proportion to oxidized levan concentration. During this process distinct areas of the binary gradient have been shown to modulate the osteoblasts’ extracellular signal-regulated kinase signalling with different propensity. The proposed fabrication method results in the preparation of a new bioactive material, which could control the cell signalling response. This approach can be extended to screen new bioactive interfaces for tissue regeneration. (papers)

  17. High speed laser tomography system

    Science.gov (United States)

    Samsonov, D.; Elsaesser, A.; Edwards, A.; Thomas, H. M.; Morfill, G. E.

    2008-03-01

    A high speed laser tomography system was developed capable of acquiring three-dimensional (3D) images of optically thin clouds of moving micron-sized particles. It operates by parallel-shifting an illuminating laser sheet with a pair of galvanometer-driven mirrors and synchronously recording two-dimensional (2D) images of thin slices of the imaged volume. The maximum scanning speed achieved was 120000slices/s, sequences of 24 volume scans (up to 256 slices each) have been obtained. The 2D slices were stacked to form 3D images of the volume, then the positions of the particles were identified and followed in the consecutive scans. The system was used to image a complex plasma with particles moving at speeds up to cm/s.

  18. High-frequency strontium vapor laser for biomedical applications

    Science.gov (United States)

    Hvorostovsky, A.; Kolmakov, E.; Kudashev, I.; Redka, D.; Kancer, A.; Kustikova, M.; Bykovskaya, E.; Mayurova, A.; Stupnikov, A.; Ruzankina, J.; Tsvetkov, K.; Lukyanov, N.; Paklinov, N.

    2018-02-01

    Sr-laser with high pulse repetition rate and high peak radiation power is a unique tool for studying rapidly occurring processes in time (plasma diagnostics, photoablation, etc.). In addition, the study of the frequency characteristics of the active medium of the laser helps to reveal the physics of the formation of an inverse medium in metal vapor lasers. In this paper, an experimental study of an Sr-laser with an active volume of 5.8 cm3 in the pulse repetition frequency range from 25 to 200 kHz is carried out, and a comparison with the frequency characteristics of media with large active volumes is given. We considered the frequency characteristics of the active medium in two modes: at a constant energy in the excitation pulse CU2 / 2 and at a constant average power consumed by the rectifier. In the presented work with a small-volume GRT using the TASITR-5/12 TASITRON switch, a laser was generated for Pairs of strontium at a CSF of 200 kHz. The behavior of the characteristics of the generation lines of 6.456 μm, 1 μm, and 3 μm at increased repetition frequencies is considered. Using the example of large-volume GRT, it is shown that tubes with a large active volume increase their energy characteristics with the growth of the CSF. The possibility of laser operation at pulse repetition rates above 200 kHz is shown.

  19. Regular self-microstructuring on CR39 using high UV laser dose

    International Nuclear Information System (INIS)

    Parvin, P.; Refahizadeh, M.; Mortazavi, S.Z.; Silakhori, K.; Mahdiloo, A.; Aghaii, P.

    2014-01-01

    The UV laser induced replicas in the form of self-lining microstructures are created by high dose (with high fluence) ArF laser irradiation on CR39. Microstructures as the self-induced contours, in the form of concentric circles, appear when the laser fluence is well above the ablation threshold. It leads to the regular periodic parallel lines, i.e. circles with large radii having spatial separation 100–200 nm and line width 300–600 nm, where the number of shots increases to achieve higher UV doses. The surface wettability is also investigated after laser texturing to exhibit that a notable hydrophilicity takes place at high doses.

  20. A NASA high-power space-based laser research and applications program

    Science.gov (United States)

    Deyoung, R. J.; Walberg, G. D.; Conway, E. J.; Jones, L. W.

    1983-01-01

    Applications of high power lasers are discussed which might fulfill the needs of NASA missions, and the technology characteristics of laser research programs are outlined. The status of the NASA programs or lasers, laser receivers, and laser propulsion is discussed, and recommendations are presented for a proposed expanded NASA program in these areas. Program elements that are critical are discussed in detail.

  1. High intensive short laser pulse interaction with submicron clusters media

    International Nuclear Information System (INIS)

    Faenov, A. Ya

    2008-01-01

    The interaction of short intense laser pulses with structured targets, such as clusters, exhibits unique features, stemming from the enhanced absorption of the incident laser light compared to solid targets. Due to the increased absorption, these targets are heated significantly, leading to enhanced emission of x rays in the keV range and generation of electrons and multiple charged ions with kinetic energies from tens of keV to tens of MeV. Possible applications of these targets can be an electron/ion source for a table top accelerator, a neutron source for a material damage study, or an x ray source for microscopy or lithography. The overview of recent results, obtained by the high intensive short laser pulse interaction with different submicron clusters media will be presented. High resolution K and L shell spectra of plasma generated by superintense laser irradiation of micron sized Ar, Kr and Xe clusters have been measured with intensity 10"17"-10"19"W/cm"2"and a pulse duration of 30-1000fs. It is found that hot electrons produced by high contrast laser pulses allow the isochoric heating of clusters and shift the ion balance toward the higher charge states, which enhances both the X ray line yield and the ion kinetic energy. Irradiation of clusters, produced from such gas mixture, by a fs Ti:Sa laser pulses allows to enhance the soft X ray radiation of Heβ(665.7eV)and Lyα(653.7eV)of Oxygen in 2-8 times compare with the case of using as targets pure CO"2"or N"2"O clusters and reach values 2.8x10"10"(∼3μJ)and 2.7x10"10"(∼2.9μJ)ph/(sr·pulse), respectively. Nanostructure conventional soft X ray images of 100nm thick Mo and Zr foils in a wide field of view (cm"2"scale)with high spatial resolution (700nm)are obtained using the LiF crystals as soft X ray imaging detectors. When the target used for the ion acceleration studies consists of solid density clusters embedded into the background gas, its irradiation by high intensity laser light makes the target

  2. Incorporating high-pressure electroosmotic pump and a nano-flow gradient generator into a miniaturized liquid chromatographic system for peptide analysis.

    Science.gov (United States)

    Chen, Apeng; Lynch, Kyle B; Wang, Xiaochun; Lu, Joann J; Gu, Congying; Liu, Shaorong

    2014-09-24

    We integrate a high-pressure electroosmotic pump (EOP), a nanoflow gradient generator, and a capillary column into a miniaturized liquid chromatographic system that can be directly coupled with a mass spectrometer for proteomic analysis. We have recently developed a low-cost high-pressure EOP capable of generating pressure of tens of thousands psi, ideal for uses in miniaturized HPLC. The pump worked smoothly when it was used for isocratic elutions. When it was used for gradient elutions, generating reproducible gradient profiles was challenging; because the pump rate fluctuated when the pump was used to pump high-content organic solvents. This presents an issue for separating proteins/peptides since high-content organic solvents are often utilized. In this work, we solve this problem by incorporating our high-pressure EOP with a nano-flow gradient generator so that the EOP needs only to pump an aqueous solution. With this combination, we develop a capillary-based nano-HPLC system capable of performing nano-flow gradient elution; the pump rate is stable, and the gradient profiles are reproducible and can be conveniently tuned. To demonstrate its utility, we couple it with either a UV absorbance detector or a mass spectrometer for peptide separations. Copyright © 2014. Published by Elsevier B.V.

  3. High power multiple wavelength diode laser stack for DPSSL application without temperature control

    Science.gov (United States)

    Hou, Dong; Yin, Xia; Wang, Jingwei; Chen, Shi; Zhan, Yun; Li, Xiaoning; Fan, Yingmin; Liu, Xingsheng

    2018-02-01

    High power diode laser stack is widely used in pumping solid-state laser for years. Normally an integrated temperature control module is required for stabilizing the output power of solid-state laser, as the output power of the solid-state laser highly depends on the emission wavelength and the wavelength shift of diode lasers according to the temperature changes. However the temperature control module is inconvenient for this application, due to its large dimension, high electric power consumption and extra adding a complicated controlling system. Furthermore, it takes dozens of seconds to stabilize the output power when the laser system is turned on. In this work, a compact hard soldered high power conduction cooled diode laser stack with multiple wavelengths is developed for stabilizing the output power of solid-state laser in a certain temperature range. The stack consists of 5 laser bars with the pitch of 0.43mm. The peak output power of each bar in the diode laser stack reaches as much as 557W and the combined lasing wavelength spectrum profile spans 15nm. The solidstate laser, structured with multiple wavelength diode laser stacks, allows the ambient temperature change of 65°C without suddenly degrading the optical performance.

  4. Development of high repetition rate ultra-short pulse solid state lasers pumped by laser diodes

    International Nuclear Information System (INIS)

    Ueda, Ken-ichi; Lu, Jianren; Takaichi, Kazunori; Yagi, Hideki; Yanagitani, Takakimi; Kaminskii, Alexander; Kawanaka, Junji

    2004-01-01

    A novel technique for ceramic lasers has been developed recently. Self-energy-driven sintering of nano-and micro particles created the fully transparent Nd:YAG ceramics. The ceramic YAG demonstrated high efficiency operation (optical-to-optical conversion of 60% in end pumping) and solid-phase crystals growth and the possible scaling were investigated principally. Typical performance of ceramic YAG laser has been reviewed. The present status and future prospect of the ceramic lasers technologies were discussed. (author)

  5. Calculation of high-pressure argon plasma parameters produced by excimer laser

    International Nuclear Information System (INIS)

    Tsuda, Norio; Yamada, Jun

    2000-01-01

    When a XeCl excimer laser light was focused in a high-pressure argon gas up to 150 atm, a dense plasma developed not only backward but also forward. It is important to study on the electron density and temperature of the laser-induced plasma in the high-pressure gas. The electron density and temperature in high-pressure argon plasma produced by XeCl excimer laser has been calculated and compared with the experimental data. (author)

  6. Gradient Self-Doped CuBi2O4 with Highly Improved Charge Separation Efficiency.

    Science.gov (United States)

    Wang, Fuxian; Septina, Wilman; Chemseddine, Abdelkrim; Abdi, Fatwa F; Friedrich, Dennis; Bogdanoff, Peter; van de Krol, Roel; Tilley, S David; Berglund, Sean P

    2017-10-25

    A new strategy of using forward gradient self-doping to improve the charge separation efficiency in metal oxide photoelectrodes is proposed. Gradient self-doped CuBi 2 O 4 photocathodes are prepared with forward and reverse gradients in copper vacancies using a two-step, diffusion-assisted spray pyrolysis process. Decreasing the Cu/Bi ratio of the CuBi 2 O 4 photocathodes introduces Cu vacancies that increase the carrier (hole) concentration and lowers the Fermi level, as evidenced by a shift in the flat band toward more positive potentials. Thus, a gradient in Cu vacancies leads to an internal electric field within CuBi 2 O 4 , which can facilitate charge separation. Compared to homogeneous CuBi 2 O 4 photocathodes, CuBi 2 O 4 photocathodes with a forward gradient show highly improved charge separation efficiency and enhanced photoelectrochemical performance for reduction reactions, while CuBi 2 O 4 photocathodes with a reverse gradient show significantly reduced charge separation efficiency and photoelectrochemical performance. The CuBi 2 O 4 photocathodes with a forward gradient produce record AM 1.5 photocurrent densities for CuBi 2 O 4 up to -2.5 mA/cm 2 at 0.6 V vs RHE with H 2 O 2 as an electron scavenger, and they show a charge separation efficiency of 34% for 550 nm light. The gradient self-doping accomplishes this without the introduction of external dopants, and therefore the tetragonal crystal structure and carrier mobility of CuBi 2 O 4 are maintained. Lastly, forward gradient self-doped CuBi 2 O 4 photocathodes are protected with a CdS/TiO 2 heterojunction and coated with Pt as an electrocatalyst. These photocathodes demonstrate photocurrent densities on the order of -1.0 mA/cm 2 at 0.0 V vs RHE and evolve hydrogen with a faradaic efficiency of ∼91%.

  7. Amplified spontaneous emission and thermal management on a high average-power diode-pumped solid-state laser - the Lucia laser system

    International Nuclear Information System (INIS)

    Albach, D.

    2010-01-01

    The development of the laser triggered the birth of numerous fields in both scientific and industrial domains. High intensity laser pulses are a unique tool for light/matter interaction studies and applications. However, current flash-pumped glass-based systems are inherently limited in repetition-rate and efficiency. Development within recent years in the field of semiconductor lasers and gain media drew special attention to a new class of lasers, the so-called Diode Pumped Solid State Laser (DPSSL). DPSSLs are highly efficient lasers and are candidates of choice for compact, high average-power systems required for industrial applications but also as high-power pump sources for ultra-high intense lasers. The work described in this thesis takes place in the context of the 1 kilowatt average-power DPSSL program Lucia, currently under construction at the 'Laboratoire d'Utilisation des Laser Intenses' (LULI) at the Ecole Polytechnique, France. Generation of sub-10 nanosecond long pulses with energies of up to 100 joules at repetition rates of 10 hertz are mainly limited by Amplified Spontaneous Emission (ASE) and thermal effects. These limitations are the central themes of this work. Their impact is discussed within the context of a first Lucia milestone, set around 10 joules. The developed laser system is shown in detail from the oscillator level to the end of the amplification line. A comprehensive discussion of the impact of ASE and thermal effects is completed by related experimental benchmarks. The validated models are used to predict the performances of the laser system, finally resulting in a first activation of the laser system at an energy level of 7 joules in a single-shot regime and 6.6 joules at repetition rates up to 2 hertz. Limitations and further scaling approaches are discussed, followed by an outlook for the further development. (author) [fr

  8. Use of high-gradient magnetic fishing for reducing proteolysis during fermentation

    DEFF Research Database (Denmark)

    Maury, Trine Lütken; Ottow, Kim Ekelund; Brask, Jesper

    2012-01-01

    Proteolysis during fermentation may have a severe impact on the yield and quality of a secreted product. In the current study, we demonstrate the use of high-gradient magnetic fishing (HGMF) as an efficient alternative to the more conventional methods of preventing proteolytic degradation....... Bacitracin-linked magnetic affinity adsorbents were employed directly in a fermenter during Bacillus licheniformis cultivation to remove trace amounts of unwanted proteases. The constructed magnetic adsorbents had excellent, highly specific binding characteristics in the fermentation broth (K(d) = 1...

  9. Functionally graded materials produced with high power lasers

    NARCIS (Netherlands)

    De Hosson, J. T. M.; Ocelik, V.; Chandra, T; Torralba, JM; Sakai, T

    2003-01-01

    In this keynote paper two examples will be present of functionally graded materials produced with high power Nd:YAG lasers. In particular the conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of A18Si and Ti6Al4V alloys are presented. The formation of

  10. Capitalizing Resolving Power of Density Gradient Ultracentrifugation by Freezing and Precisely Slicing Centrifuged Solution: Enabling Identification of Complex Proteins from Mitochondria by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Haiqing Yu

    2016-01-01

    Full Text Available Density gradient centrifugation is widely utilized for various high purity sample preparations, and density gradient ultracentrifugation (DGU is often used for more resolution-demanding purification of organelles and protein complexes. Accurately locating different isopycnic layers and precisely extracting solutions from these layers play a critical role in achieving high-resolution DGU separations. In this technique note, we develop a DGU procedure by freezing the solution rapidly (but gently after centrifugation to fix the resolved layers and by slicing the frozen solution to fractionate the sample. Because the thickness of each slice can be controlled to be as thin as 10 micrometers, we retain virtually all the resolution produced by DGU. To demonstrate the effectiveness of this method, we fractionate complex V from HeLa mitochondria using a conventional technique and this freezing-slicing (F-S method. The comparison indicates that our F-S method can reduce complex V layer thicknesses by ~40%. After fractionation, we analyze complex V proteins directly on a matrix assisted laser desorption/ionization, time-of-flight mass spectrometer. Twelve out of fifteen subunits of complex V are positively identified. Our method provides a practical protocol to identify proteins from complexes, which is useful to investigate biomolecular complexes and pathways in various conditions and cell types.

  11. High energy laser facilities at Lawrence Livermore National Laboratory

    International Nuclear Information System (INIS)

    Holmes, N.C.

    1981-06-01

    High energy laser facilities at Lawrence Livermore National Laboratory are described, with special emphasis on their use for equation of state investigations using laser-generated shockwaves. Shock wave diagnostics now in use are described. Future Laboratory facilities are also discussed

  12. Laser cutting of high manganese cast steel; Komangan chuko no laser setsudan

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Y.; Tokunaga, T. [University of Industrial Technology, Kanagawa (Japan); Miyazaki, T. [Chiba Institute of Technology, Chiba (Japan)

    1994-08-25

    This paper discusses applicability of CO2 laser to cut high manganese cast steel, and investigates the cutting conditions and characteristics. The tested material is made of steel scrap, ferro Mn and ferro Cr of 50 kg in total, which was deoxidized by using pure aluminum and injected into CO2 die by means of the ordinary casting method to make a circular rod with a diameter of 28 mm. The rod was given a heating and water toughening treatment in a muffle furnace maintaining N2 atmosphere. The base structure is an austenite system of Mn 12.4% by mass with hardness of MHV 220 to 230. The paper describes discussions on test pieces (with a thickness of 2 mm) fabricated under a laser beam frequency of 150 Hz, power outputs of 250, 350 and 500 W, and cutting speeds of 100, 300 and 500 mm/min. The cutting width increases as the laser power is increased, but is not governed by the cutting speed. Increased cutting speed roughens the surface of a cut face. The laser cutting has caused no change in hardness of the base material, and no processing deterioration has been recognized. As described, the laser cutting can be applied to finish-cutting if the cutting condition is selected properly. Simplification of the cutting process and improvement of working environment can be expected from the laser cutting. 14 refs., 12 figs., 2 tabs.

  13. High repetition rate driver circuit for modulation of injection lasers

    International Nuclear Information System (INIS)

    Dornan, B.R.; Goel, J.; Wolkstein, H.J.

    1981-01-01

    An injection laser modulator comprises a self-biased field effect transistor (FET) and an injection laser to provide a quiescent state during which lasing of the injection laser occurs in response to a high repetition rate signal of pulse coded modulation (pcm). The modulator is d.c. coupled to an input pulse source of pcm rendering it compatible with an input pulse referenced to ground and not being subject to voltage level shifting of the input pulse. The modulator circuit in its preferred and alternate embodiments provides various arrangements for high impedance input and low impedance output matching. In addition, means are provided for adjusting the bias of the FET as well as the bias of the injection laser

  14. Risks and injuries in laser and high-frequency applications

    Science.gov (United States)

    Giering, K.; Philipp, Carsten M.; Berlien, Hans-Peter

    1995-01-01

    An analysis of injuries and risks using high frequency (HF) and lasers in medicine based on a literature search with MEDLINE was performed. The cases reported in the literature were classified according to the following criteria: (1) Avoidable in an optimal operational procedure. These kind of injuries are caused by a chain of unfortunate incidents. They are in principle avoidable by the 'right action at the right time' which presupposes an appropriate training of the operating team, selection of the optimal parameters for procedure and consideration of all safety instructions. (2) Avoidable, caused by malfunction of the equipment and/or accessories. The injuries classified into this group are avoidable if all safety regulations were fulfilled. This includes a pre-operational check-up and the use of medical lasers and high frequency devices only which meet the international safety standards. (3) Avoidable, caused by misuse/mistake. Injuries of this group were caused by an inappropriate selection of the procedure, wrong medical indication or mistakes during application. (4) Unavoidable, fateful. These injuries can be caused by risks inherent to the type of energy used, malfunction of the equipment and/or accessories though a pre-operational check-up was done. Some risks and complications are common to high frequency and laser application. But whereas these risks can be excluded easily in laser surgery there is often a great expenditure necessary or they are not avoidable if high frequency if used. No unavoidable risks due to laser energy occur.

  15. 2 W high efficiency PbS mid-infrared surface emitting laser

    Science.gov (United States)

    Ishida, A.; Sugiyama, Y.; Isaji, Y.; Kodama, K.; Takano, Y.; Sakata, H.; Rahim, M.; Khiar, A.; Fill, M.; Felder, F.; Zogg, H.

    2011-09-01

    High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The laser showed external quantum efficiency as high as 16%. Generally, mid-infrared III-V or II-VI semiconductor laser operation utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. Auger recombination is much lower in the IV-VI semiconductors, and the free-carrier absorption is significantly reduced by an optically pumped laser structure including multi-step optical excitation layers.

  16. Control over phase separation and nucleation using a laser-tweezing potential

    Science.gov (United States)

    Walton, Finlay; Wynne, Klaas

    2018-05-01

    Control over the nucleation of new phases is highly desirable but elusive. Even though there is a long history of crystallization engineering by varying physicochemical parameters, controlling which polymorph crystallizes or whether a molecule crystallizes or forms an amorphous precipitate is still a poorly understood practice. Although there are now numerous examples of control using laser-induced nucleation, the absence of physical understanding is preventing progress. Here we show that the proximity of a liquid-liquid critical point or the corresponding binodal line can be used by a laser-tweezing potential to induce concentration gradients. A simple theoretical model shows that the stored electromagnetic energy of the laser beam produces a free-energy potential that forces phase separation or triggers the nucleation of a new phase. Experiments in a liquid mixture using a low-power laser diode confirm the effect. Phase separation and nucleation using a laser-tweezing potential explains the physics behind non-photochemical laser-induced nucleation and suggests new ways of manipulating matter.

  17. High average power solid state laser power conditioning system

    International Nuclear Information System (INIS)

    Steinkraus, R.F.

    1987-01-01

    The power conditioning system for the High Average Power Laser program at Lawrence Livermore National Laboratory (LLNL) is described. The system has been operational for two years. It is high voltage, high power, fault protected, and solid state. The power conditioning system drives flashlamps that pump solid state lasers. Flashlamps are driven by silicon control rectifier (SCR) switched, resonant charged, (LC) discharge pulse forming networks (PFNs). The system uses fiber optics for control and diagnostics. Energy and thermal diagnostics are monitored by computers

  18. Application of laser cutting technology to high radiation environments

    International Nuclear Information System (INIS)

    Pauley, K.A.; Mitchell, M.R.; Saget, S.N.

    1996-01-01

    A 2 kW Nd:YAG laser system manufactured by the Lumonics Corporation will be used to cut various metals during the fall of 1996 as part of a United States Department of Energy (DOE)-funded technology demonstration at the Hanford Site. The laser cutting demonstration will focus on an evaluation of two issues as the technology applies to the decontamination and decommissioning (D ampersand D) of aging nuclear facilities. An assessment will be made as to the ability of laser end effectors to be operated using electromechanical remote manipulators and the ability of both end effector and fiber optics to withstand the damage created by a high radiation field. The laser cutting demonstration will be conducted in two phases. The first phase will be a non-radioactive test to ensure the ability of hot cell remote manipulators to use the laser end effector to successfully cut the types of materials and geometries found in the hot cell. The second phase will introduce the laser end effector and the associated fiber optic cable into the hot cell radiation environment. The testing in the hot cell will investigate the degradation of the optical portions of the end effector and transmission cable in the high radiation field. The objective of the demonstration is to assess the cutting efficiency and life limitations of a laser cutting system for radioactive D ampersand D operations. A successful demonstration will, therefore, allow the laser cutting technology to be integrated into the baseline planning for the D ampersand D of DOE facilities throughout the nation

  19. Generating a high brightness multi-kilowatt laser by dense spectral combination of VBG stabilized single emitter laser diodes

    Science.gov (United States)

    Fritsche, H.; Koch, Ralf; Krusche, B.; Ferrario, F.; Grohe, Andreas; Pflueger, S.; Gries, W.

    2014-05-01

    Generating high power laser radiation with diode lasers is commonly realized by geometrical stacking of diode bars, which results in high output power but poor beam parameter product (BPP). The accessible brightness in this approach is limited by the fill factor, both in slow and fast axis. By using a geometry that accesses the BPP of the individual diodes, generating a multi kilowatt diode laser with a BPP comparable to fiber lasers is possible. We will demonstrate such a modular approach for generating multi kilowatt lasers by combining single emitter diode lasers. Single emitter diodes have advantages over bars, mainly a simplified cooling, better reliability and a higher brightness per emitter. Additionally, because single emitters can be arranged in many different geometries, they allow building laser modules where the brightness of the single emitters is preserved. In order to maintain the high brightness of the single emitter we developed a modular laser design which uses single emitters in a staircase arrangement, then coupling two of those bases with polarization combination which is our basic module. Those modules generate up to 160 W with a BPP better than 7.5 mm*mrad. For further power scaling wavelength stabilization is crucial. The wavelength is stabilized with only one Volume Bragg Grating (VBG) in front of a base providing the very same feedback to all of the laser diodes. This results in a bandwidth of BPP better than 7.5 mm*mrad, which can easily coupled into a 100 μm fiber and 0.15 NA.

  20. Advancements in high-power high-brightness laser bars and single emitters for pumping and direct diode application

    Science.gov (United States)

    An, Haiyan; Jiang, Ching-Long J.; Xiong, Yihan; Zhang, Qiang; Inyang, Aloysius; Felder, Jason; Lewin, Alexander; Roff, Robert; Heinemann, Stefan; Schmidt, Berthold; Treusch, Georg

    2015-03-01

    We have continuously optimized high fill factor bar and packaging design to increase power and efficiency for thin disc laser system pump application. On the other hand, low fill factor bars packaged on the same direct copper bonded (DCB) cooling platform are used to build multi-kilowatt direct diode laser systems. We have also optimized the single emitter designs for fiber laser pump applications. In this paper, we will give an overview of our recent advances in high power high brightness laser bars and single emitters for pumping and direct diode application. We will present 300W bar development results for our next generation thin disk laser pump source. We will also show recent improvements on slow axis beam quality of low fill factor bar and its application on performance improvement of 4-5 kW TruDiode laser system with BPP of 30 mm*mrad from a 600 μm fiber. Performance and reliability results of single emitter for multiemitter fiber laser pump source will be presented as well.

  1. Absorption homogenization at wavy melt films by CO{sub 2}-lasers in contrast to 1 μm-wavelength lasers

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, Alexander F.H., E-mail: alexander.kaplan@ltu.se

    2015-02-15

    Highlights: • The absorption distribution of 1 μm wavelength lasers compared to 10 μm CO{sub 2}-lasers across a wavy molten steel surface is calculated, at grazing angle of incidence. • For a wide range of surface waviness parameters the CO{sub 2}-laser shows a much more homogenizing absorption behaviour than 1 μm-lasers. • Although the interaction is very complex and non-linear, it is fundamental and very distinct between CO{sub 2}-lasers and 1 μm-lasers, due to their very different Fresnel-absorption characteristics. • The strong local absorption peaks for 1 μm-lasers can cause very strong local boiling and amplification of surface waves, in good correlation to empirical experimental trends. • Such differences can in turn have strong consequences during laser materials processing like laser keyhole welding, laser drilling or laser remote fusion cutting. - Abstract: For wavy metal melts, across a wide range of their topology parameters, lasers with about 1 μm wavelength experience the highest Fresnel absorption around the shoulders of the waves. Calculations show that this induces a strong peak of the absorbed power density of the laser beam. The high temperature gradients have the potential to cause very local boiling and growth of the valleys. In contrast, for a certain parameter category the small Brewster angle for the CO{sub 2}-laser partially homogenizes the temperatures by elevated absorption at domains of grazing incidence. This has the potential to cause opposite consequences on the process, like wave smoothing.

  2. Relativistically Induced Transparency Acceleration (RITA) - laser-plasma accelerated quasi-monoenergetic GeV ion-beams with existing lasers?

    Science.gov (United States)

    Sahai, Aakash A.

    2013-10-01

    Laser-plasma ion accelerators have the potential to produce beams with unprecedented characteristics of ultra-short bunch lengths (100s of fs) and high bunch-charge (1010 particles) over acceleration length of about 100 microns. However, creating and controlling mono-energetic bunches while accelerating to high-energies has been a challenge. If high-energy mono-energetic beams can be demonstrated with minimal post-processing, laser (ω0)-plasma (ωpe) ion accelerators may be used in a wide-range of applications such as cancer hadron-therapy, medical isotope production, neutron generation, radiography and high-energy density science. Here we demonstrate using analysis and simulations that using relativistic intensity laser-pulses and heavy-ion (Mi ×me) targets doped with a proton (or light-ion) species (mp ×me) of trace density (at least an order of magnitude below the cold critical density) we can scale up the energy of quasi-mono-energetically accelerated proton (or light-ion) beams while controlling their energy, charge and energy spectrum. This is achieved by controlling the laser propagation into an overdense (ω0 RITA). Desired proton or light-ion energies can be achieved by controlling the velocity of the snowplow, which is shown to scale inversely with the rise-time of the laser (higher energies for shorter pulses) and directly with the scale-length of the plasma density gradient. Similar acceleration can be produced by controlling the increase of the laser frequency (Chirp Induced Transparency Acceleration, ChITA). Work supported by the National Science Foundation under NSF- PHY-0936278. Also, NSF-PHY-0936266 and NSF-PHY-0903039; the US Department of Energy under DEFC02-07ER41500, DE- FG02-92ER40727 and DE-FG52-09NA29552.

  3. High-Power ZBLAN Glass Fiber Lasers: Review and Prospect

    Directory of Open Access Journals (Sweden)

    Xiushan Zhu

    2010-01-01

    Full Text Available ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF, considered as the most stable heavy metal fluoride glass and the excellent host for rare-earth ions, has been extensively used for efficient and compact ultraviolet, visible, and infrared fiber lasers due to its low intrinsic loss, wide transparency window, and small phonon energy. In this paper, the historical progress and the properties of fluoride glasses and the fabrication of ZBLAN fibers are briefly described. Advances of infrared, upconversion, and supercontinuum ZBLAN fiber lasers are addressed in detail. Finally, constraints on the power scaling of ZBLAN fiber lasers are analyzed and discussed. ZBLAN fiber lasers are showing promise of generating high-power emissions covering from ultraviolet to mid-infrared considering the recent advances in newly designed optical fibers, beam-shaped high-power pump diodes, beam combining techniques, and heat-dissipating technology.

  4. Propagation Characteristics of High-Power Vortex Laguerre-Gaussian Laser Beams in Plasma

    Directory of Open Access Journals (Sweden)

    Zhili Lin

    2018-04-01

    Full Text Available The propagation characteristics of high-power laser beams in plasma is an important research topic and has many potential applications in fields such as laser machining, laser-driven accelerators and laser-driven inertial confined fusion. The dynamic evolution of high-power Laguerre-Gaussian (LG beams in plasma is numerically investigated by using the finite-difference time-domain (FDTD method based on the nonlinear Drude model, with both plasma frequency and collision frequency modulated by the light intensity of laser beam. The numerical algorithms and implementation techniques of FDTD method are presented for numerically simulating the nonlinear permittivity model of plasma and generating the LG beams with predefined parameters. The simulation results show that the plasma has different field modulation effects on the two exemplified LG beams with different cross-sectional patterns. The self-focusing and stochastic absorption phenomena of high-power laser beam in plasma are also demonstrated. This research also provides a new means for the field modulation of laser beams by plasma.

  5. Proton radiography of magnetic field in laser produced plasma

    International Nuclear Information System (INIS)

    Le Pape, S.; Patel, P.; Chen, S.; Town, R.; Mackinnon, A.

    2009-01-01

    Electromagnetic fields generated by the interaction with plasmas of long-pulse laser beams relevant to inertial confinement fusion have been measure. A proton beam generated by the interaction of an ultra intense laser with a thin metallic foil is used to probe the B-fields. The proton beam then generated is temporally short (of the order of a ps), highly laminar and hence equivalent to a virtual point which makes it an ideal source for radiography. We have investigated, using face-on radiography, B fields at intensity around 10 14 W/cm 2 due to the non co-linearity of temperature and density gradients. (authors)

  6. Generation of high shock pressures by laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Romain, J.P. (GRECO ILM, Laboratoire d' Energetique et Detonique, E.N.S.M.A., 86 - Poitiers (France))

    1984-11-01

    Aspects of laser generated high shock pressures and results obtained over the last years are reviewed. Shock pressures up to 5 TPa inferred from shock velocity measurements are reported. Effects of laser wavelength, intensity and 2-D plasma expansion on the generated shock pressure are discussed. The hydrodynamic efficiency determined from various data including new results at 0,26 ..mu..m wavelength outlines the advantage of short wavelengths for producing very high pressures. The possibility of achieving shock pressures in the 10 TPa range with the use of the impedance match technique is examined.

  7. Generation of high shock pressures by laser pulses

    International Nuclear Information System (INIS)

    Romain, J.P.

    1984-01-01

    Aspects of laser generated high shock pressures and results obtained over the last years are reviewed. Shock pressures up to 5 TPa inferred from shock velocity measurements are reported. Effects of laser wavelength, intensity and 2-D plasma expansion on the generated shock pressure are discussed. The hydrodynamic efficiency determined from various data including new results at 0,26 μm wavelength outlines the advantage of short wavelengths for producing very high pressures. The possibility of achieving shock pressures in the 10 TPa range with the use of the impedance match technique is examined

  8. Effects of thin high-Z layers on the hydrodynamics of laser-accelerated plastic targets

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Colombant, D.G.; Karasik, M.; Pawley, C.J.; Serlin, V.; Schmitt, A.J.; Weaver, J.L.; Gardner, J.H.; Phillips, L.; Aglitskiy, Y.; Chan, Y.; Dahlburg, J.P.; Klapisch, M.

    2002-01-01

    Experimental results and simulations that study the effects of thin metallic layers with high atomic number (high-Z) on the hydrodynamics of laser accelerated plastic targets are presented. These experiments employ a laser pulse with a low-intensity foot that rises into a high-intensity main pulse. This pulse shape simulates the generic shape needed for high-gain fusion implosions. Imprint of laser nonuniformity during start up of the low intensity foot is a well-known seed for hydrodynamic instability. Large reductions are observed in hydrodynamic instability seeded by laser imprint when certain minimum thickness gold or palladium layers are applied to the laser-illuminated surface of the targets. The experiment indicates that the reduction in imprint is at least as large as that obtained by a 6 times improvement in the laser uniformity. Simulations supported by experiments are presented showing that during the low intensity foot the laser light can be nearly completely absorbed by the high-Z layer. X rays originating from the high-Z layer heat the underlying lower-Z plastic target material and cause large buffering plasma to form between the layer and the accelerated target. This long-scale plasma apparently isolates the target from laser nonuniformity and accounts for the observed large reduction in laser imprint. With onset of the higher intensity main pulse, the high-Z layer expands and the laser light is transmitted. This technique will be useful in reducing laser imprint in pellet implosions and thereby allow the design of more robust targets for high-gain laser fusion

  9. High brightness diode lasers controlled by volume Bragg gratings

    Science.gov (United States)

    Glebov, Leonid

    2017-02-01

    Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.

  10. Lasers and new methods of particle acceleration

    International Nuclear Information System (INIS)

    Parsa, Z.

    1998-02-01

    There has been a great progress in development of high power laser technology. Harnessing their potential for particle accelerators is a challenge and of great interest for development of future high energy colliders. The author discusses some of the advances and new methods of acceleration including plasma-based accelerators. The exponential increase in sophistication and power of all aspects of accelerator development and operation that has been demonstrated has been remarkable. This success has been driven by the inherent interest to gain new and deeper understanding of the universe around us. With the limitations of the conventional technology it may not be possible to meet the requirements of the future accelerators with demands for higher and higher energies and luminosities. It is believed that using the existing technology one can build a linear collider with about 1 TeV center of mass energy. However, it would be very difficult (or impossible) to build linear colliders with energies much above one or two TeV without a new method of acceleration. Laser driven high gradient accelerators are becoming more realistic and is expected to provide an alternative, (more compact, and more economical), to conventional accelerators in the future. The author discusses some of the new methods of particle acceleration, including laser and particle beam driven plasma based accelerators, near and far field accelerators. He also discusses the enhanced IFEL (Inverse Free Electron Laser) and NAIBEA (Nonlinear Amplification of Inverse-Beamstrahlung Electron Acceleration) schemes, laser driven photo-injector and the high energy physics requirements

  11. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  12. Atomic motion in a high-intensity standing wave laser field

    International Nuclear Information System (INIS)

    Saez Ramdohr, L.F.

    1987-01-01

    This work discusses the effect of a high-intensity standing wave laser field on the motion of neutral atoms moving with a relatively high velocity. The analysis involves a detailed calculation of the force acting on the atoms and the calculation of the diffusion tensor associated with the fluctuations of the quantum force operator. The high-intensity laser field limit corresponds to a Rabi frequency much greater than the natural rate of the atom. The general results are valid for any atomic velocity. Results are then specialized to the case of slow and fast atoms where the Doppler shift of the laser frequency due to the atomic motion is either smaller or larger than the natural decay rate of the atom. The results obtained for the force and diffusion tensor are applied to a particular ideal experiment that studies the evolution of a fast atomic beam crossing a high-intensity laser beam. The theories developed previously, for a similar laser configuration, discuss only the low atomic velocities case and not the more realistic case of fast atoms. Here, an approximate solution of the equation for the distribution is obtained. Starting from the approximate distribution function, the deflection angle and dispersion angle for the atomic beam with respect to the free motion are calculated

  13. Development of the Laser Retroreflector Array (LRA) for SARAL

    Science.gov (United States)

    Costes, Vincent; Gasc, Karine; Sengenes, Pierre; Salcedo, Corinne; Imperiali, Stéphan; du Jeu, Christian

    2017-11-01

    CNES (French spatial agency) will provide the AltiKa high resolution altimeter, Doris instrument and the LRA (Laser Retroreflector Array) for SARAL (Satellite with Argos and AltiKa) in cooperation with ISRO (Indian space agency). The LRA is a passive equipment reflecting the laser beams coming from the Earth ground stations. Computing the send-return time travel of the laser beams allows the determination of the satellite altitude within an accuracy of a few millimeters. The reflective function is done by a set of 9 corner cube reflectors, with a conical arrangement providing a 150 degrees wide field of view over the full 360 degrees azimuth angle. According to CNES optomechanical specifications, the LRA has been developed by SESO (French optical firm). SESO has succeeded in providing the corner cube reflectors with a very stringent dihedral angle error of 1.6 arcsec and an accuracy within +/-0.5 arcsec. During this development, SESO has performed mechanical, thermal and thermo-optical analyses. The optical gradient of each corner cube, as well as angular deviations and PSF (Point Spread Function) in each laser range finding direction, have been computed. Mechanical and thermal tests have been successfully performed. A thermo-optical test has successfully confirmed the optical effect of the predicted in-flight thermal gradients. Each reflector is characterized in order to find its best location in the LRA housing and give the maximum optimization to the space telemetering mission.

  14. Solidification and microstructural aspects of laser-deposited Ni–Mo ...

    Indian Academy of Sciences (India)

    15Cr–3Si (wt%) alloy powder. Laser cladding parameters ... Laser cladding; microstructure; Ni–Mo–Cr–Si alloy. PACS Nos 42.62.-b; 81.65. ... [1–3]. Large temperature gradient across the interface of the melted region and the underlying solid ...

  15. Evaluation between residual stresses obtained by neutron diffraction and simulation for dual phase steel welded by laser process

    Science.gov (United States)

    Kouadri-Henni, Afia; Malard, Benoit

    2018-05-01

    This study aimed at characterizing the residual stresses (RS) distribution of a Dual Phase Steel (DP600) undergoing a Laser Beam Welding (LBW) with two different laser parameters. The RS in the ferritic phase have been experimentally determined by the use of the neutrons diffraction technique. The results confirmed a gradient of RS among different zones both on the top and below surfaces but also through the thickness of the fusion zone. Low compressive stresses were observed in the Base Metal (BM) close to the Heat Affected Zone (HAZ) whereas high tensile stresses were observed in the Fusion Zone (FZ). Numerical results showed a difference in the RS distribution depending on the model used. In the end, it appears that the high temperature gradient, specific to the laser beam, is the main factor governing the RS. Our results suggest as well that the approach regarding the RS should consider not only the temperature but also process parameters. When comparing simulation results with experimental data, the values converge well in some zones, in particular the FZ and the others less.

  16. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince–Gaussian modes for optical trapping

    Energy Technology Data Exchange (ETDEWEB)

    Jun Dong; Yu He; Xiao Zhou; Shengchuang Bai [Department of Electronics Engineering, School of Information Science and Engineering, Xiamen, 361005 (China)

    2016-03-31

    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping. (control of laser radiation parameters)

  17. An Evaluation of the Cutting Potential of Different Types of High Power Lasers

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove

    2006-01-01

    Laser cutting is a widespread industrial process. The boundaries for the performance of the lasers in terms of cutting capabilities is steadily moving towards higher cutting rates and thicker section cutting. In this paper the potential of different high power laser sources in cutting is evaluated...... based upon the historical development, the available cutting mechanisms understanding and the critical parameters involved in high power laser cutting. From the theoretical point of view, the new laser sources, the Disc-laser and the Fibre laser possess a potential of changing dramatically the limits...... for cutting performance. These theoretical considerations are evaluated against available cutting data....

  18. High-power diode laser bars as pump sources for fiber lasers and amplifiers (Invited Paper)

    Science.gov (United States)

    Bonati, G.; Hennig, P.; Wolff, D.; Voelckel, H.; Gabler, T.; Krause, U.; T'nnermann, A.; Reich, M.; Limpert, J.; Werner, E.; Liem, A.

    2005-04-01

    Fiber lasers are pumped by fibercoupled, multimode single chip devices at 915nm. That"s what everybody assumes when asked for the type of fiber laser pumps and it was like this for many years. Coming up as an amplifier for telecom applications, the amount of pump power needed was in the range of several watts. Highest pump powers for a limited market entered the ten watts range. This is a range of power that can be covered by highly reliable multimode chips, that have to survive up to 25 years, e.g. in submarine applications. With fiber lasers entering the power range and the application fields of rod and thin disc lasers, the amount of pump power needed raised into the area of several hundred watts. In this area of pump power, usually bar based pumps are used. This is due to the much higher cost pressure of the industrial customers compared to telecom customers. We expect more then 70% of all industrial systems to be pumped by diode laser bars. Predictions that bar based pumps survive for just a thousand hours in cw-operation and fractions of this if pulsed are wrong. Bar based pumps have to perform on full power for 10.000h on Micro channel heat sinks and 20.000h on passive heatsinks in industrial applications, and they do. We will show a variety of data, "real" long time tests and statistics from the JENOPTIK Laserdiode as well as data of thousands of bars in the field, showing that bar based pumps are not just well suitable for industrial applications on high power levels, but even showing benefits compared to chip based pumps. And it"s reasonable, that the same objectives of cost effectiveness, power and lifetime apply as well to thin disc, rod and slab lasers as to fiber lasers. Due to the pumping of fiber lasers, examples will be shown, how to utilize bars for high brightness fiber coupling. In this area, the automation is on its way to reduce the costs on the fibercoupling, similar to what had been done in the single chip business. All these efforts are

  19. Statistics of vacuum breakdown in the high-gradient and low-rate regime

    Science.gov (United States)

    Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio; Korsbäck, Anders; Djurabekova, Flyura; Rajamäki, Robin; Giner-Navarro, Jorge

    2017-01-01

    In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

  20. Toward high brightness, multi-kilowatt solid state lasers

    International Nuclear Information System (INIS)

    Zapata, L.E.; Manes, K.R.

    1990-11-01

    High average power (HAP) solid state laser output with improved beam quality has introduced new capabilities in materials processing. At the 500 W level and with a beam quality of a ''few'' times the diffraction limit, the General Electric NY slab is able to drill 5 cm of stainless steel in a few seconds. We expect that 2--3 kW of near infrared laser output in a low order spatial mode would enable metal working now unknown to industry. The HAP output of slab lasers is limited by the size of the available laser crystals and the pump power. Core free, six cm diameter NY boules have been grown on an experimental basis. High optical quality NG can be obtained up to 10 cm in diameter. We present the results of our modeling based on these crystals pumped by advanced arc-lamps or laser diode arrays. We project HAP laser outputs of 1.6 kW from an existing Vortek pumped NG oscillator and about 2 kW from diode pumped NY device. Several kW of laser output can be expected from two such slabs in a MOPA configuration before optical damage limits are reached. The three dimensional stress-optic code which we used to optimize our designs, was normalized to available experimental data obtained with the above NG slab at the 500 W level and a 40 W diode pumped NY test bed. Our calculations indicate the essential parameters for attainment of high beam quality. Cooling uniformity across the pumped faces of the slab is critical and the location of the transition between pumped and un-pumped regions towards the slab tips is very important. A flat pumping profile was found to be desirable and predicted one wave of distortion which should be correctable over about 75% of the aperture however, an even better wavefront was predicted over 90% of the aperture when the regions near the edges of the slab were slightly over-pumped relative to the central regions and the regions near to the ends were tapered to compensate for transition effects