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Sample records for intense laser plasma

  1. Plasma optical modulators for intense lasers

    NASA Astrophysics Data System (ADS)

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D. A.; Mori, W. B.; Zhang, Jie

    2016-06-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 1016 W cm-2 to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations.

  2. Plasma optical modulators for intense lasers

    PubMed Central

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D. A.; Mori, W. B.; Zhang, Jie

    2016-01-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 1016 W cm−2 to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations. PMID:27283369

  3. Plasma optical modulators for intense lasers.

    PubMed

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D A; Mori, W B; Zhang, Jie

    2016-01-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 10(16) W cm(-2) to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations. PMID:27283369

  4. Interaction of plasmas with intense lasers

    SciTech Connect

    Kruer, William L.

    2000-06-01

    The interaction of plasmas with intense lasers is an excellent example of how different fields of physics are interconnected. Invention of the laser and its ongoing development has allowed the creation and study of high temperature, dense matter in the laboratory. The results both advance the underlying plasma science and are relevant to many fields ranging from astrophysics to fusion and nonlinear physics. A brief overview of the interaction physics is given. Selected topics are discussed to illustrate the exciting progress in experimental, theoretical, and computational investigations with focused laser intensities up to 10{sup 21} W/cm{sup 2}. (c) 2000 American Institute of Physics.

  5. Relativistic plasma astrophysics with intense lasers

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Yasuhiro; Chu, Hsu-Hsin; Hau, Lin-Ni; Chen, Shih-Hung; Liu, Yao-Li; Hsieh, Chia-Ying; Sakawa, Youichi; Hideaki, Takabe; Wang, Jyhpyng

    2015-12-01

    Recent progresses of laser technologies enable us to investigate space and astrophysical phenomena in laboratories. In space plasmas the local observations by spacecrafts provide us the microscopic information of the plasma and electric/magnetic fields, however, it is difficult to obtain the global structures of the phenomena. In astrophysical plasmas, in contrast, global images provide us the macroscopic information, although there is no local observation and thus no microscopic information. Laboratory experiments on space and astrophysical phenomena provide us the local and global information simultaneously. We have investigated so far mostly non-relativistic phenomena in the universe with long laser pulses. Now we extend our research from non-relativistic to relativistic regime with an ultra intense laser, the 100 TW laser facility at National Central University. We introduce our facility and model relativistic phenomena in laboratory, focusing on the magnetic field generation and the magnetic reconnection in the universe.

  6. Aluminium plasma production at high laser intensity

    SciTech Connect

    Torrisi, L.; Cutroneo, M.

    2014-02-28

    Thick and thin films of Al targets were irradiated in vacuum with iodine laser at 1315 nm wavelength, 300 ps pulse duration at a maximum intensity of about 10{sup 16} W/cm{sup 2} by varying the pulse energy and focal position. The laser-generated plasma was monitored in forward and backward directions by using ion collectors, SiC detectors, Thomson parabola spectrometer, and X-ray streak camera. Ion emission shows maximum proton energy of about 4 MeV in self-focusing conditions and a maximum Al ion energy of about 50 MeV. An evaluation of the electric field driving ions in conditions of target normal sheath acceleration is given.

  7. Focusing of Intense Laser via Parabolic Plasma Concave Surface

    NASA Astrophysics Data System (ADS)

    Zhou, Weimin; Gu, Yuqiu; Wu, Fengjuan; Zhang, Zhimeng; Shan, Lianqiang; Cao, Leifeng; Zhang, Baohan

    2015-12-01

    Since laser intensity plays an important role in laser plasma interactions, a method of increasing laser intensity - focusing of an intense laser via a parabolic plasma concave surface - is proposed and investigated by three-dimensional particle-in-cell simulations. The geometric focusing via a parabolic concave surface and the temporal compression of high harmonics increased the peak intensity of the laser pulse by about two orders of magnitude. Compared with the improvement via laser optics approaches, this scheme is much more economic and appropriate for most femtosecond laser facilities. supported by National Natural Science Foundation of China (Nos. 11174259, 11175165), and the Dual Hundred Foundation of China Academy of Engineering Physics

  8. Ultra-high intensity laser plasma interactions

    NASA Astrophysics Data System (ADS)

    Langdon, A. Bruce; Hinkel, D. E.; Lasinski, Barbara F.; Still, C. H.

    1997-11-01

    In current studies of plasma interactions relevant to the fast ignitor concept,footnote M. Tabak, et al., Phys. Plasmas 1, 1626 (1994). an ultra-high intensity beam propagates through underdense, relativistically transparent, and then near solid density plasmas to create a channel. The ultra-high intensity beam propagates through this channel toward the compressed core where it creates hot electrons as it is absorbed. Three-dimensional fluid simulation(R. L. Berger et al), Phys. Fluids B, 2243 (1993). (with relativistic enhancements) studies of self-focusing in the underdense plasma will be reported and compared to PIC simulations in the same parameter regime. Beam structure near focus detracts from channel formation. Modeling in support of upcoming 100TW will be presented.

  9. Dynamics of intense laser propagation in underdense plasma: Polarization dependence

    SciTech Connect

    Singh, D. K.; Fiuza, F.; Silva, L. O.; Davies, J. R.; Sarri, G.

    2012-07-15

    We present a comprehensive numerical study of the dynamics of an intense laser pulse as it propagates through an underdense plasma in two and three dimensions. By varying the background plasma density and the polarization of the laser beam, significant differences are found in terms of energy transport and dissipation, in agreement with recently reported experimental results. Below the threshold for relativistic self-focusing, the plasma and laser dynamics are observed to be substantially insensitive to the initial laser polarization, since laser transport is dominated by ponderomotive effects. Above this threshold, relativistic effects become important, and laser energy is dissipated either by plasma heating (p-polarization) or by trapping of electromagnetic energy into plasma cavities (s-polarization) or by a combination of both (circular polarization). Besides the fundamental interest of this study, the results presented are relevant to applications such as plasma-based accelerators, x-ray lasers, and fast-ignition inertial confinement fusion.

  10. The interaction of intense subpicosecond laser pulses with underdense plasmas

    SciTech Connect

    Coverdale, C.A.

    1995-05-11

    Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 10{sup 16} W/cm{sup 2} laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by L{sub plasma} {ge} 2L{sub Rayleigh} > c{tau}. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (n{sub o} {le} 0.05n{sub cr}). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in {omega}-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

  11. Intense transient magnetic-field generation by laser plasma

    SciTech Connect

    Benjamin, R.F.

    1981-08-18

    In a laser system, the return current of a laser generated plasma is conducted near a target to subject that target to the magnetic field thereof. In alternate embodiments the target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet.

  12. Intensity dependence of relativistic focusing of intense laser beams propagating in plasmas

    SciTech Connect

    Liu Mingwei; Zhou Bingju; Yi Yougen; Liu Xiaojuan; Tang Liqiang

    2007-10-15

    Optical guiding of an intense laser beam propagating in uniform plasmas is analyzed by means of the variational method. The focusing properties of the beam are shown to be governed by the laser power as well as the laser intensity. An increase in the laser intensity leads to an enhancement of ponderomotive self-channeling but a stronger weakening of relativistic self-focusing. The oscillations of the beam spot size along the propagation distance come from the variability of the focusing force in terms of the laser intensity; and the dependence on the laser intensity is negligible in the weakly relativistic limit.

  13. Propagation of intense laser pulses in strongly magnetized plasmas

    SciTech Connect

    Yang, X. H. Ge, Z. Y.; Xu, B. B.; Zhuo, H. B.; Ma, Y. Y.; Shao, F. Q.; Yu, W.; Xu, H.; Yu, M. Y.; Borghesi, M.

    2015-06-01

    Propagation of intense circularly polarized laser pulses in strongly magnetized inhomogeneous plasmas is investigated. It is shown that a left-hand circularly polarized laser pulse propagating up the density gradient of the plasma along the magnetic field is reflected at the left-cutoff density. However, a right-hand circularly polarized laser can penetrate up the density gradient deep into the plasma without cutoff or resonance and turbulently heat the electrons trapped in its wake. Results from particle-in-cell simulations are in good agreement with that from the theory.

  14. Intense tera-hertz laser driven proton acceleration in plasmas

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Tibai, Z.; Hebling, J.

    2016-06-01

    We investigate the acceleration of a proton beam driven by intense tera-hertz (THz) laser field from a near critical density hydrogen plasma. Two-dimension-in-space and three-dimension-in-velocity particle-in-cell simulation results show that a relatively long wavelength and an intense THz laser can be employed for proton acceleration to high energies from near critical density plasmas. We adopt here the electromagnetic field in a long wavelength (0.33 THz) regime in contrast to the optical and/or near infrared wavelength regime, which offers distinct advantages due to their long wavelength ( λ = 350 μ m ), such as the λ 2 scaling of the electron ponderomotive energy. Simulation study delineates the evolution of THz laser field in a near critical plasma reflecting the enhancement in the electric field of laser, which can be of high relevance for staged or post ion acceleration.

  15. Relativistic intensity laser interactions with low-density plasmas

    NASA Astrophysics Data System (ADS)

    Willingale, L.; Nilson, P. M.; Zulick, C.; Chen, H.; Craxton, R. S.; Cobble, J.; Maksimchuk, A.; Norreys, P. A.; Sangster, T. C.; Scott, R. H. H.; Stoeckl, C.

    2016-03-01

    We perform relativistic-intensity laser experiments using the Omega EP laser to investigate channeling phenomena and particle acceleration in underdense plasmas. A fundamental understanding of these processes is of importance to the hole-boring fast ignition scheme for inertial confinement fusion. Proton probing was used to image the electromagnetic fields formed as the Omega EP laser pulse generated a channel through underdense plasma. Filamentation of the channel was observed, followed by self-correction into a single channel. The channel radius as a function of time was found to be in reasonable agreement with momentum- conserving snowplough models.

  16. Plasmas and Short-Pulse, High-Intensity Lasers

    NASA Astrophysics Data System (ADS)

    Clark, Thomas

    1999-11-01

    Many of the applications of short-pulse, high-intensity laser systems, including coherent UV and X-ray generation, compact particle accelerators, and non-perturbative nonlinear optics as well as the study of laser-matter interaction physics, require large intensity-interaction length products. In recent years, plasma structures resulting from the hydrodynamic evolution of laser-produced plasma filaments have proven to be attractive media for guiding pulses with peak powers approaching the terawatt level over lengths many times the vacuum Rayleigh range. The hydrodynamics of plasma waveguides have been characterized using time- and space-resolved interferometry measurements of electron density profiles. The laser-driven ionization and heating phase of the plasma filament creation is followed by hot electron driven plasma expansion. Density profiles suitable for optical guiding develop within the first few hundred picoseconds after plasma creation, during which rapid cooling occurs. At longer times the plasma expansion closely follows that of a cylindrical blast wave, with further cooling due to expansion work. The observed guided intensity profiles of end-coupled and tunnel-coupled pulses compare favorably with calculations of the quasi-bound waveguide modes based on the measured electron density profiles. Time- and space-resolved electron density measurements of a laser-driven concentric implosion were also performed. The implosion is the result of the interaction of a second laser pulse with an existing plasma waveguide. The two-pulse absorption and ionization significantly exceed that due to a single pulse of the same total energy. The author would like to acknowledge the significant contributions of Prof. Howard M. Milchberg to the work being presented.

  17. Microengineering Laser Plasma Interactions at Relativistic Intensities.

    PubMed

    Jiang, S; Ji, L L; Audesirk, H; George, K M; Snyder, J; Krygier, A; Poole, P; Willis, C; Daskalova, R; Chowdhury, E; Lewis, N S; Schumacher, D W; Pukhov, A; Freeman, R R; Akli, K U

    2016-02-26

    We report on the first successful proof-of-principle experiment to manipulate laser-matter interactions on microscales using highly ordered Si microwire arrays. The interaction of a high-contrast short-pulse laser with a flat target via periodic Si microwires yields a substantial enhancement in both the total and cutoff energies of the produced electron beam. The self-generated electric and magnetic fields behave as an electromagnetic lens that confines and guides electrons between the microwires as they acquire relativistic energies via direct laser acceleration. PMID:26967419

  18. Microengineering Laser Plasma Interactions at Relativistic Intensities

    NASA Astrophysics Data System (ADS)

    Jiang, S.; Ji, L. L.; Audesirk, H.; George, K. M.; Snyder, J.; Krygier, A.; Poole, P.; Willis, C.; Daskalova, R.; Chowdhury, E.; Lewis, N. S.; Schumacher, D. W.; Pukhov, A.; Freeman, R. R.; Akli, K. U.

    2016-02-01

    We report on the first successful proof-of-principle experiment to manipulate laser-matter interactions on microscales using highly ordered Si microwire arrays. The interaction of a high-contrast short-pulse laser with a flat target via periodic Si microwires yields a substantial enhancement in both the total and cutoff energies of the produced electron beam. The self-generated electric and magnetic fields behave as an electromagnetic lens that confines and guides electrons between the microwires as they acquire relativistic energies via direct laser acceleration.

  19. Dependence of terahertz power from laser-produced plasma on laser intensity

    SciTech Connect

    Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R.

    2012-07-11

    Power of terahertz radiation from plasma which is generated from air irradiated by coupled ({omega}, 2{omega}) femtosecond laser pulses is analyzed for high laser intensities, for which non-linear plasma effects on the pulse propagation become essential, with multidimensional particle-in-cell simulations including the self-consistent plasma kinetics. The growth rate of THz power becomes slower as the laser intensity increases. A reason of such a lowering of efficiency in THz emission is found to be ionization of air by the laser pulse, which results in poor focusing of laser pulses.

  20. Experimental results to study astrophysical plasma jets using Intense Lasers

    NASA Astrophysics Data System (ADS)

    Loupias, B.; Gregory, C. D.; Falize, E.; Waugh, J.; Seiichi, D.; Pikuz, S.; Kuramitsu, Y.; Ravasio, A.; Bouquet, S.; Michaut, C.; Barroso, P.; Rabec Le Gloahec, M.; Nazarov, W.; Takabe, H.; Sakawa, Y.; Woolsey, N.; Koenig, M.

    2009-08-01

    We present experimental results of plasma jet, interacted with an ambient medium, using intense lasers to investigate the complex features of astrophysical jets. This experiment was performed in France at the LULI facility, Ecole Polytechnique, using one long pulse laser to generate the jet and a short pulse laser to probe it by proton radiography. A foam filled cone target was used to generate high velocity plasma jet, and a gas jet nozzle produced the well known ambient medium. Using visible pyrometry and interferometry, we were able to measure the jet velocity and electronic density. We get a panel of measurements at various gas density and time delay. From these measurements, we could underline the growth of a perturbed shape of the jet interaction with the ambient medium. The reason of this last observation is still in debate and will be presented in the article.

  1. Propagation of intense laser pulse in cold underdense plasma

    SciTech Connect

    Chen, X.L.; Sudan, R.N.

    1994-10-05

    We have derived a simplified set of three dimensional equations for the propagation of an intense laser pulse in cold underdense plasma [Phys. Fluids, {bold B}5, 1336 (1993)]. A three dimensional code has recently been developed to study this set of equations. Here we report on some of the preliminary results from the 3-d code. {copyright} 1994 {ital American} {ital Institute} {ital of} {ital Physics}

  2. Nonlinear properties of relativistically intense laser in plasmas

    SciTech Connect

    Qiao Bin; Lai, C. H.; Zhou, C. T.; He, X. T.; Wang, X. G.; Yu, M. Y.

    2007-11-15

    Nonlinear characteristics including spatial chaos and patterns associated with relativistically intense laser-plasma interaction are studied theoretically and numerically using a model relativistic nonlinear Schroedinger equation. It is shown that in the phase space irregular homoclinic orbit crossings exist. The latter are verified and investigated numerically. The spatial chaos and complex patterns of the laser wave field can be attributed to the relativistic electron mass variation as well as the ponderomotive-force driven electron-density modulation. The formation of complex patterns results from stochastic partition of energy in the Fourier modes.

  3. Propagation of intense subpicosecond laser pulses through underdense plasmas

    SciTech Connect

    Coverdale, C.A.; Darrow, C.B.; Decker, C.D.; Mori, W.B.; Tzeng, K.; Marsh, K.A.; Clayton, C.E.; Joshi, C.

    1995-06-05

    The propagation of an intense, subpicosecond laser pulse through a substantial length ({ital L}/{lambda}{similar_to}10{sup 3}) of an underdense plasma ({ital n}/{ital n}{sub {ital c}}{similar_to}1%) is studied through experiments and computer simulations. For {ital I}=8{times}10{sup 17} W/cm{sup 2} only 55% of the incident laser light was transmitted through the plasma within the focal cone angle. The decrease in transmission was accompanied by Raman forward scattering as evidenced by the generation of anti-Stokes sidebands and up to 2 MeV electrons. Simulations show that the majority of the reduction in transmission could be due to Raman forward and side scattering.

  4. Ultra-Intense Laser Pulse Propagation in Gas and Plasma

    SciTech Connect

    Antonsen, T. M.

    2004-10-26

    It is proposed here to continue their program in the development of theories and models capable of describing the varied phenomena expected to influence the propagation of ultra-intense, ultra-short laser pulses with particular emphasis on guided propagation. This program builds upon expertise already developed over the years through collaborations with the NSF funded experimental effort lead by Professor Howard Milchberg here at Maryland, and in addition the research group at the Ecole Polytechnique in France. As in the past, close coupling between theory and experiment will continue. The main effort of the proposed research will center on the development of computational models and analytic theories of intense laser pulse propagation and guiding structures. In particular, they will use their simulation code WAKE to study propagation in plasma channels, in dielectric capillaries and in gases where self focusing is important. At present this code simulates the two-dimensional propagation (radial coordinate, axial coordinate and time) of short pulses in gas/plasma media. The plasma is treated either as an ensemble of particles which respond to the ponderomotive force of the laser and the self consistent electric and magnetic fields created in the wake of pulse or as a fluid. the plasma particle motion is treated kinetically and relativistically allowing for study of intense pulses that result in complete cavitation of the plasma. The gas is treated as a nonlinear medium with rate equations describing the various stages of ionization. A number of important physics issues will be addressed during the program. These include (1) studies of propagation in plasma channels, (2) investigation of plasma channel nonuniformities caused by parametric excitation of channel modes, (3) propagation in dielectric capillaries including harmonic generation and ionization scattering, (4) self guided propagation in gas, (5) studies of the ionization scattering instability recently

  5. Ptychographic measurements of ultrahigh-intensity laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Leblanc, A.; Monchocé, S.; Bourassin-Bouchet, C.; Kahaly, S.; Quéré, F.

    2016-04-01

    The extreme intensities now delivered by femtosecond lasers make it possible to drive and control relativistic motion of charged particles with light, opening a path to compact particle accelerators and coherent X-ray sources. Accurately characterizing the dynamics of ultrahigh-intensity laser-plasma interactions as well as the resulting light and particle emissions is an essential step towards such achievements. This remains a considerable challenge, as the relevant scales typically range from picoseconds to attoseconds in time, and from micrometres to nanometres in space. In these experiments, owing to the extreme prevalent physical conditions, measurements can be performed only at macroscopic distances from the targets, yielding only partial information at these microscopic scales. This letter presents a major advance by applying the concepts of ptychography to such measurements, and thus retrieving microscopic information hardly accessible until now. This paves the way to a general approach for the metrology of extreme laser-plasma interactions on very small spatial and temporal scales.

  6. Guiding of intense laser pulse in uniform plasmas and preformed plasma channels

    SciTech Connect

    Wang Jingwei; Lei, A. L.; Wang Xin; Yu Wei; Yu, M. Y.; Senecha, V. K.; Wang, X. G.; Murakami, M.; Mima, K.

    2010-10-15

    Guiding of laser pulse in uniform plasmas and preformed plasma channels is investigated. The self-guiding mechanisms for these two cases are quite different. It is found that an intense laser pulse can be steadily self-guided in underdense plasmas with nearly a constant spot size if the self-consistently generated electron cavity has a sufficiently steep density gradient at the edge. In a preformed plasma channel, however, laser guiding is maintained mainly by the balance between the light diffraction and focusing. The latter is induced by the wall plasmas which greatly reduce the local dielectric constant. It is shown that the self-guiding of a laser pulse in uniform plasmas requires tens of terawatts power, but those that are in preformed channels can be realized with only a terawatt power.

  7. Laser shaping of a relativistic intense, short Gaussian pulse by a plasma lens.

    PubMed

    Wang, H Y; Lin, C; Sheng, Z M; Liu, B; Zhao, S; Guo, Z Y; Lu, Y R; He, X T; Chen, J E; Yan, X Q

    2011-12-23

    By 3D particle-in-cell simulation and analysis, we propose a plasma lens to make high intensity, high contrast laser pulses with a steep front. When an intense, short Gaussian laser pulse of circular polarization propagates in near-critical plasma, it drives strong currents of relativistic electrons which magnetize the plasma. Three pulse shaping effects are synchronously observed when the laser passes through the plasma lens. The laser intensity is increased by more than 1 order of magnitude while the initial Gaussian profile undergoes self-modulation longitudinally and develops a steep front. Meanwhile, a nonrelativistic prepulse can be absorbed by the overcritical plasma lens, which can improve the laser contrast without affecting laser shaping of the main pulse. If the plasma skin length is properly chosen and kept fixed, the plasma lens can be used for varied laser intensity above 10(19) W/cm(2). PMID:22243161

  8. Laser Shaping of a Relativistic Intense, Short Gaussian Pulse by a Plasma Lens

    NASA Astrophysics Data System (ADS)

    Wang, H. Y.; Lin, C.; Sheng, Z. M.; Liu, B.; Zhao, S.; Guo, Z. Y.; Lu, Y. R.; He, X. T.; Chen, J. E.; Yan, X. Q.

    2011-12-01

    By 3D particle-in-cell simulation and analysis, we propose a plasma lens to make high intensity, high contrast laser pulses with a steep front. When an intense, short Gaussian laser pulse of circular polarization propagates in near-critical plasma, it drives strong currents of relativistic electrons which magnetize the plasma. Three pulse shaping effects are synchronously observed when the laser passes through the plasma lens. The laser intensity is increased by more than 1 order of magnitude while the initial Gaussian profile undergoes self-modulation longitudinally and develops a steep front. Meanwhile, a nonrelativistic prepulse can be absorbed by the overcritical plasma lens, which can improve the laser contrast without affecting laser shaping of the main pulse. If the plasma skin length is properly chosen and kept fixed, the plasma lens can be used for varied laser intensity above 1019W/cm2.

  9. Analysis of plasma channels in mm-scale plasmas formed by high intensity laser beams

    NASA Astrophysics Data System (ADS)

    Murakami, R.; Habara, H.; Ivancic, S.; Anderson, K.; Haberberger, D.; Iwawaki, T.; Sakagami, H.; Stoeckl, C.; Theobald, W.; Uematsu, Y.; Tanaka, K. A.

    2016-05-01

    A plasma channel created by a high intensity infrared laser beam was observed in a long scale-length plasma (L ∼ 240 μm) with the angular filter refractometry technique, which indicated a stable channel formation up to the critical density. We analyzed the observed plasma channel using a rigorous ray-tracing technique, which provides a deep understanding of the evolution of the channel formation.

  10. Measurements of forward scattered laser radiation from intense sub-ps laser interactions with underdense plasmas

    SciTech Connect

    Walton, B. R.; Mangles, S. P. D.; Najmudin, Z.; Tatarakis, M.; Wei, M. S.; Gopal, A.; Marle, C.; Dangor, A. E.; Krushelnick, K.; Fritzler, S.; Malka, V.; Clarke, R. J.; Hernandez-Gomez, C.

    2006-11-15

    Two experiments studying the interaction of high intensity laser pulses (1x10{sup 19}-5x10{sup 20} W/cm{sup 2}) with underdense plasma are compared. The experiments used lasers that differed in power and focused intensity but had similar pulse duration ({approx}1 ps). Spectroscopic measurements of the forward scattered light (sidebands) near the fundamental laser frequency produced by the self-modulation instability were performed and the energies of electrons accelerated in the interaction are measured and compared. It is found that at high intensities the sideband intensities and the electron energies were not directly correlated, implying that relativistic plasma wave generation is not the most important mechanism for electron acceleration in the ultrahigh intensity regime. Simulation results for the forward scattered spectrum agree well with experimental results.

  11. Plasma discreteness effects in the presence of an intense, ultrashort laser pulse

    SciTech Connect

    Savchenko, V.I.; Fisch, N.J.

    1996-03-01

    Discrete effects of the plasma irradiated by an ultrashort, intense laser pulse are investigated. Although, for most plasmas of interest, the damping of the laser pulse is due to collective plasma effects, in certain regimes the energy absorbed in the plasma microfields can be important. A scattering matrix is derived for an electron scattering off an ion in the presence of an intense laser field.

  12. Tight focusing of ultra-intense laser pulses by innovative plasma optics toward extreme intensity

    NASA Astrophysics Data System (ADS)

    Nakatsutsumi, M.; Kon, A.; Fuchs, J.; Buffechoux, S.; Audebert, P.; Kodama, R.

    2009-11-01

    With rapid advances in laser technology, laser beams are now available that can be routinely focused to intensities approaching >10^21 Wcm-2. Enhancement of laser intensity is achieved by truncating the pulse width, increasing the laser-energy, or reducing the focal spot size. Although the reduction of the spot size is the simplest among those, by using low f-number optics, this method is not frequently employed because of the difficulty in avoiding damage from target debris or complexity of alignment procedure. We developed for the first time very compact (<1 cm^3) extremely low f-number (0.4) plasma-based, confocal ellipsoid focusing systems. Direct measurement of the laser focal spot using low-energy laser indicates 1/5 reduction of spot size compared to standard focusing (using a f/3 optics). Around tenfold enhancement of laser intensity by reduction of the spot size for high power shots is clearly evidenced by remarkable enhancement of proton energy. The experiment was performed at LULI 100TW laser facility.

  13. A Plasma Lens for High Intensity Laser Focusing

    SciTech Connect

    Fang, F.; Clayton, C. E.; Marsh, K. A.; Joshi, C.; Lopes, N. C.; Ito, H.

    2006-11-27

    A plasma lens based on a short hydrogen-filled alumina capillary discharge is experimentally characterized. For a plasma length of about 5mm, the focal length, measured from the plasma entrance, was {approx} 11 to 8mm for on axis densities of {approx} 2.5 to 5 x 1018cm-3, respectively. The plasma temperature away from the walls of the 1/2mm diameter capillary was estimated to be {approx} 8eV indicating that the plasma is fully ionized. Such a lens should thus be suitable for focusing very high intensity pulses. Comparisons of the measured focusing strength to that predicted by a first-order fluid model [N. A. Bobrova, et al., Phys. Rev. E 65, 016407 (2002)] shows reasonable agreement given that some of the observed plasma parameters are not predicted by this model.

  14. Appearance of Density Cavitations in the Laser Wake in Simulations of High Intensity Laser-Plasma Interactions

    SciTech Connect

    Wang, T.-L.

    2009-01-22

    Nonlinear interactions of high intensity, ultrashort laser pulses with underdense plasmas produce many interesting features that may appear in computer simulations. One of these features commonly observed in Particle-In-Cell (PIC) simulations is the spontaneous appearance of long-lived density cavitations in the plasma wake region behind the laser pulse. To study these cavitations, several small 2D PIC simulations are run in which plasma density, density ramps, total simulation time, laser pulsewidth, laser intensity, and laser polarization parameters have been varied. Based on the simulation results, some possible aspects of an experiment designed to directly detect these structures are discussed.

  15. Resonant high-order harmonic generation from plasma ablation: Laser intensity dependence of the harmonic intensity and phase

    SciTech Connect

    Milosevic, D. B.

    2010-02-15

    Experimentally observed strong enhancement of a single high-order harmonic in harmonic generation from low-ionized laser plasma ablation is explained as resonant harmonic generation. The resonant harmonic intensity increases regularly with the increase of the laser intensity, while the phase of the resonant harmonic is almost independent of the laser intensity. This is in sharp contrast with the usual plateau and cutoff harmonics, the intensity of which exhibits wild oscillations while its phase changes rapidly with the laser intensity. The temporal profile of a group of harmonics, which includes the resonant harmonic, has the form of a broad peak in each laser-field half cycle. These characteristics of resonant harmonics can have an important application in attoscience. We illustrate our results using examples of Sn and Sb plasmas.

  16. Emittance of positron beams produced in intense laser plasma interaction

    SciTech Connect

    Chen Hui; Hazi, A.; Link, A.; Anderson, S.; Gronberg, J.; Izumi, N.; Tommasini, R.; Wilks, S.; Sheppard, J. C.; Meyerhofer, D. D.; Baldis, H. A.; Marley, E.; Park, J.; Williams, G. J.; Fedosejev, R.; Kerr, S.

    2013-01-15

    The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be useful as an alternative positron source for future accelerators.

  17. Propagation of intense short-pulse laser in homogeneous near-critical density plasmas

    NASA Astrophysics Data System (ADS)

    Habara, H.; Nakaguchi, S.; Uematsu, Y.; Baton, S. D.; Chen, S. N.; Fuchs, J.; Iwawaki, T.; MacDonald, M.; Nazarov, W.; Rousseaux, C.; Tanaka, K. A.

    2016-05-01

    Ultra intense laser light propagation in a homogeneous overdense plasma was investigated using a plastic foam target filling a polyimide tube. Laser propagation into overdense plasma was measured via Doppler red shift of the reflected laser light from the moving plasma at 0.3-0.4 of speed of light. We also observed strongly collimated electron beam possibly caused by the magnetic field surrounding the plasma channel, and high energy X-rays emitted via synchrotron radiation by the oscillating electrons inside the channel. These features imply that UIL propagates inside the overdense plasma as predicted in PIC calculation, and are very important for direct irradiation scheme of fast ignition.

  18. Ponderomotive acceleration of injected electrons in tenuous plasmas by intense laser pulses

    SciTech Connect

    Sazegari, V.; Shokri, B.

    2006-11-15

    The trapping and acceleration of an electron by forward ponderomotive force associated with intense short laser pulses, propagating in homogeneous rarefied plasmas is analyzed. This is done not by solving the motion equations but by energy conservation law and Lorentz transformation. This method is able to the treat the ponderomotive acceleration regardless of laser polarization. It is shown that the gain of acceleration increases linearly with the field strength of the laser and the relativistic factor of the group velocity of the laser in the plasma, while the minimum injection energy necessary for trapping the electron decreases with the laser field strength and increases slowly with the group velocity of the laser.

  19. Intense terahertz emission from relativistic circularly polarized laser pulses interaction with overdense plasmas

    SciTech Connect

    Chen, Zi-Yu; Li, Xiao-Ya; Yu, Wei

    2013-10-15

    During the interaction of a relativistic circularly polarized laser pulse with an overdense plasma target, the longitudinal motion of bunches of electrons under the action of light pressure and electrostatic restore force can emit intense terahertz (THz) pulses. This mechanism allows high pump laser intensity and large electron number participating in the emission. Two-dimensional particle-in-cell simulations are carried out to investigate the THz emission. The results suggest that such a source can produce remarkably intense THz pulses with energy of several mJ/sr and power of tens of gigawatts, which could find applications in nonlinear studies and relativistic laser-plasma interaction diagnostics.

  20. Magnetic field generation during intense laser channelling in underdense plasma

    NASA Astrophysics Data System (ADS)

    Smyth, A. G.; Sarri, G.; Vranic, M.; Amano, Y.; Doria, D.; Guillaume, E.; Habara, H.; Heathcote, R.; Hicks, G.; Najmudin, Z.; Nakamura, H.; Norreys, P. A.; Kar, S.; Silva, L. O.; Tanaka, K. A.; Vieira, J.; Borghesi, M.

    2016-06-01

    Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.

  1. Resonant absorption and not-so-resonant absorption in short, intense laser irradiated plasma

    SciTech Connect

    Ge, Z. Y.; Zhuo, H. B.; Ma, Y. Y.; Yang, X. H.; Yu, T. P.; Zou, D. B.; Yin, Y.; Shao, F. Q.; Yu, W.; Luan, S. X.; Zhou, C. T.; Institute of Applied Physics and Computational Mathematics, Beijing 100088 ; Peng, X. J.

    2013-07-15

    An analytical model for laser-plasma interaction during the oblique incidence by an ultrashort ultraintense p-polarized laser on a solid-density plasma is proposed. Both the resonant absorption and not-so-resonant absorption are self-consistently included. Different from the previous theoretical works, the physics of resonant absorption is found to be valid in more general conditions as the steepening of the electron density profile is considered. Even for a relativistic intensity laser, resonant absorption can still exist under certain plasma scale length. For shorter plasma scale length or higher laser intensity, the not-so-resonant absorption tends to be dominant, since the electron density is steepened to a critical level by the ponderomotive force. The laser energy absorption rates for both mechanisms are discussed in detail, and the difference and transition between these two mechanisms are presented.

  2. Monoenergetic beams of relativistic electrons from intense laser-plasma interactions.

    PubMed

    Mangles, S P D; Murphy, C D; Najmudin, Z; Thomas, A G R; Collier, J L; Dangor, A E; Divall, E J; Foster, P S; Gallacher, J G; Hooker, C J; Jaroszynski, D A; Langley, A J; Mori, W B; Norreys, P A; Tsung, F S; Viskup, R; Walton, B R; Krushelnick, K

    2004-09-30

    High-power lasers that fit into a university-scale laboratory can now reach focused intensities of more than 10(19) W cm(-2) at high repetition rates. Such lasers are capable of producing beams of energetic electrons, protons and gamma-rays. Relativistic electrons are generated through the breaking of large-amplitude relativistic plasma waves created in the wake of the laser pulse as it propagates through a plasma, or through a direct interaction between the laser field and the electrons in the plasma. However, the electron beams produced from previous laser-plasma experiments have a large energy spread, limiting their use for potential applications. Here we report high-resolution energy measurements of the electron beams produced from intense laser-plasma interactions, showing that--under particular plasma conditions--it is possible to generate beams of relativistic electrons with low divergence and a small energy spread (less than three per cent). The monoenergetic features were observed in the electron energy spectrum for plasma densities just above a threshold required for breaking of the plasma wave. These features were observed consistently in the electron spectrum, although the energy of the beam was observed to vary from shot to shot. If the issue of energy reproducibility can be addressed, it should be possible to generate ultrashort monoenergetic electron bunches of tunable energy, holding great promise for the future development of 'table-top' particle accelerators. PMID:15457251

  3. Ellipsoidal plasma mirror focusing of high power laser pulses to ultra-high intensities

    NASA Astrophysics Data System (ADS)

    Wilson, R.; King, M.; Gray, R. J.; Carroll, D. C.; Dance, R. J.; Armstrong, C.; Hawkes, S. J.; Clarke, R. J.; Robertson, D. J.; Neely, D.; McKenna, P.

    2016-03-01

    The design and development of an ellipsoidal F/1 focusing plasma mirror capable of increasing the peak intensity achievable on petawatt level laser systems to >1022 W cm-2 is presented. A factor of 2.5 reduction in the focal spot size is achieved when compared to F/3 focusing with a conventional (solid state) optic. We find a factor of 3.6 enhancement in peak intensity, taking into account changes in plasma mirror reflectivity and focal spot quality. The sensitivity of the focusing plasma optic to misalignment is also investigated. It is demonstrated that an increase in the peak laser intensity from 3 ×1020 W cm-2 to 1021 W cm-2 results in a factor of 2 increase in the maximum energy of sheath-accelerated protons from a thin foil positioned at the focus of the intense laser light.

  4. Propagation of an intense laser beam in a tapered plasma channel

    SciTech Connect

    Jha, Pallavi; Singh, Ram Gopal; Upadhyaya, Ajay K.; Mishra, Rohit K.

    2008-03-15

    Propagation characteristics and modulation instability of an intense laser beam propagating in an axially tapered plasma channel, having a parabolic radial density profile, are studied. Using the source-dependent expansion technique, the evolution equation for the laser spot is set up and conditions for propagation of the laser beam with a constant spot size (matched beam) are obtained. Further, the dispersion relation and growth rate of modulation instability of the laser pulse as it propagates through linearly and quadratically tapered plasma channels, have been obtained.

  5. Quasi-matched propagation of ultra-short, intense laser pulses in plasma channels

    SciTech Connect

    Benedetti, C.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-05-15

    The propagation of an ultrashort and relativistically intense laser pulse in a preformed plasma channel is investigated. The nonlinear paraxial wave equation describing the laser propagation in the plasma is solved both analytically and numerically. For any arbitrary temporal laser pulse profile with a given power (less then the critical power for self-focusing) and any prescribed transverse density profile in the channel, we determine the laser intensity distribution along the pulse ensuring quasi-matched propagation, neglecting non-paraxial effects. For the case of a Gaussian laser with an initially uniform spot throughout the pulse, we determine the optimal channel depth that minimizes laser evolution (e.g., minimizes spot size oscillations). The analytical and semi-analytical results obtained for both cases in the weakly relativistic regime are presented and validated through comparison with numerical simulations.

  6. Ultra-intense single attosecond pulse generated from circularly polarized laser interacting with overdense plasma

    NASA Astrophysics Data System (ADS)

    Ji, Liangliang; Shen, Baifei; Zhang, Xiaomei; Wen, Meng; Xia, Changquan; Wang, Wenpeng; Xu, Jiancai; Yu, Yahong; Yu, Mingyang; Xu, Zhizhan

    2011-08-01

    Few-cycle relativistic circularly polarized (CP) laser pulse reflected from overdense plasma is investigated by analysis and particle-in-cell simulations. It is found that through the laser-induced one-time drastic oscillation of the plasma boundary, an ultra-intense single attosecond light pulse can be generated naturally. An analytical model is proposed to describe the interaction and it agrees well with simulation results. They both indicate that peak intensity of the generated attosecond pulse is higher when the plasma density is closer to the relativistic transparency threshold and/or the pulse duration is closer to plasma oscillating period. Two dimensional simulation shows that a two-cycle 1021 W/cm2 CP laser can generate a single 230 attosecond 2 × 1021 W/cm2 pulse of light at a conversion efficiency greater than 10-2.

  7. Ultra-intense single attosecond pulse generated from circularly polarized laser interacting with overdense plasma

    SciTech Connect

    Ji Liangliang; Shen Baifei; Zhang Xiaomei; Wen Meng; Xia Changquan; Wang Wenpeng; Xu Jiancai; Yu Yahong; Xu Zhizhan; Yu Mingyang

    2011-08-15

    Few-cycle relativistic circularly polarized (CP) laser pulse reflected from overdense plasma is investigated by analysis and particle-in-cell simulations. It is found that through the laser-induced one-time drastic oscillation of the plasma boundary, an ultra-intense single attosecond light pulse can be generated naturally. An analytical model is proposed to describe the interaction and it agrees well with simulation results. They both indicate that peak intensity of the generated attosecond pulse is higher when the plasma density is closer to the relativistic transparency threshold and/or the pulse duration is closer to plasma oscillating period. Two dimensional simulation shows that a two-cycle 10{sup 21} W/cm{sup 2} CP laser can generate a single 230 attosecond 2 x 10{sup 21} W/cm{sup 2} pulse of light at a conversion efficiency greater than 10{sup -2}.

  8. On the control of filamentation of intense laser beams propagating in underdense plasma

    SciTech Connect

    Williams, E A

    2005-10-21

    In indirect drive ICF ignition designs, the laser energy is delivered into the hohlraum through the laser entrance holes (LEH), which are sized as small as practicable to minimize X-ray radiation losses. On the other hand, deleterious laser plasma processes, such as filamentation and stimulated back-scatter, typically increase with laser intensity. Ideally, therefore, the laser spot shape should be a close fit to the LEH, with uniform (envelope) intensity in the spot and minimal energy at larger radii spilling onto the LEH material. This keeps the laser intensity as low as possible consistent with the area of the LEH aperture and the power requirements of the design. This can be achieved (at least for apertures significantly larger than the laser's aberrated focal spot) by the use of custom-designed phase plates. However, outfitting the 192 beam (National Ignition facility) NIF laser with multiple sets of phase plates optimized for a variety of different LEH aperture sizes is an expensive proposition. It is thus important to assess the impact on laser-plasma interaction processes of using phase plates with a smaller than optimum focal spot (or even no phase plates at all!) and then de-focusing the beam to expand it to fill the LEH and lower its intensity. We find significant effects from the lack of uniformity of the laser envelope out of the focal plane, from changes in the characteristic sizes of the laser speckle, and on the efficacy of additional polarization and/or SSD beam smoothing. We quantify these effects with analytic estimates and simulations using our laser plasma interaction code pF3D.

  9. Reflectivity of plasmas created by high-intensity, ultra-short laser pulses

    SciTech Connect

    Gold, D.M.

    1994-06-01

    Experiments were performed to characterize the creation and evolution of high-temperature (T{sub e}{approximately}100eV), high-density (n{sub e}>10{sup 22}cm{sup {minus}3}) plasmas created with intense ({approximately}10{sup 12}-10{sup 16}W/cm{sup 2}), ultra-short (130fs) laser pulses. The principle diagnostic was plasma reflectivity at optical wavelengths (614nm). An array of target materials (Al, Au, Si, SiO{sub 2}) with widely differing electronic properties tested plasma behavior over a large set of initial states. Time-integrated plasma reflectivity was measured as a function of laser intensity. Space- and time-resolved reflectivity, transmission and scatter were measured with a spatial resolution of {approximately}3{mu}m and a temporal resolution of 130fs. An amplified, mode-locked dye laser system was designed to produce {approximately}3.5mJ, {approximately}130fs laser pulses to create and nonintrusively probe the plasmas. Laser prepulse was carefully controlled to suppress preionization and give unambiguous, high-density plasma results. In metals (Al and Au), it is shown analytically that linear and nonlinear inverse Bremsstrahlung absorption, resonance absorption, and vacuum heating explain time-integrated reflectivity at intensities near 10{sup 16}W/cm{sup 2}. In the insulator, SiO{sub 2}, a non-equilibrium plasma reflectivity model using tunneling ionization, Helmholtz equations, and Drude conductivity agrees with time-integrated reflectivity measurements. Moreover, a comparison of ionization and Saha equilibration rates shows that plasma formed by intense, ultra-short pulses can exist with a transient, non-equilibrium distribution of ionization states. All targets are shown to approach a common reflectivity at intensities {approximately}10{sup 16}W/cm{sup 2}, indicating a material-independent state insensitive to atomic or solid-state details.

  10. Stationary self-focusing of intense laser beam in cold quantum plasma using ramp density profile

    SciTech Connect

    Habibi, M.; Ghamari, F.

    2012-10-15

    By using a transient density profile, we have demonstrated stationary self-focusing of an electromagnetic Gaussian beam in cold quantum plasma. The paper is devoted to the prospects of using upward increasing ramp density profile of an inhomogeneous nonlinear medium with quantum effects in self-focusing mechanism of high intense laser beam. We have found that the upward ramp density profile in addition to quantum effects causes much higher oscillation and better focusing of laser beam in cold quantum plasma in comparison to that in the classical relativistic case. Our computational results reveal the importance and influence of formation of electron density profiles in enhancing laser self-focusing.

  11. Propagation of Super-intense and Ultra-short Laser Pulses in Plasmas

    NASA Astrophysics Data System (ADS)

    Giulietti, Danilo

    The propagation of super-intense and ultra-short laser pulses in plasmas is a main concern in several applications of the laser-plasma interactions, from Inertial Confinement Fusion (ICF) to High Energy Physics (HEP). During the propagation in the plasma the light beam deeply changes its parameters due the onset of non-linear effects, among them the relativistic regime of the electron quivering motion. These extreme conditions are suitable for the electron acceleration in high field gradient, opening the way for the realization of compact secondary sources of X-gamma rays.

  12. Hollow screw-like drill in plasma using an intense Laguerre-Gaussian laser.

    PubMed

    Wang, Wenpeng; Shen, Baifei; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

    2015-01-01

    With the development of ultra-intense laser technology, MeV ions can be obtained from laser-foil interactions in the laboratory. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction. Ion acceleration in an azimuthal orientation was scarcely studied. In this research, a doughnut Laguerre-Gaussian (LG) laser is used for the first time to examine laser-plasma interaction in the relativistic intensity regime in three-dimensional particle-in-cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw-like drill of an mode laser. The angular momentum of particles in the longitudinal direction produced by the LG laser is enhanced compared with that produced by the usual laser pulses, such as linearly and circularly polarized Gaussian pulses. Moreover, the particles (including electrons and ions) can be trapped and uniformly compressed in the dark central minimum of the doughnut LG pulse. The hollow-structured LG laser has potential applications in the generation of x-rays with orbital angular momentum, plasma accelerators, fast ignition for inertial confinement fusion, and pulsars in the astrophysical environment. PMID:25651780

  13. Hollow screw-like drill in plasma using an intense Laguerre-Gaussian laser

    NASA Astrophysics Data System (ADS)

    Wang, Wenpeng; Shen, Baifei; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

    2015-02-01

    With the development of ultra-intense laser technology, MeV ions can be obtained from laser-foil interactions in the laboratory. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction. Ion acceleration in an azimuthal orientation was scarcely studied. In this research, a doughnut Laguerre-Gaussian (LG) laser is used for the first time to examine laser-plasma interaction in the relativistic intensity regime in three-dimensional particle-in-cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw-like drill of an mode laser. The angular momentum of particles in the longitudinal direction produced by the LG laser is enhanced compared with that produced by the usual laser pulses, such as linearly and circularly polarized Gaussian pulses. Moreover, the particles (including electrons and ions) can be trapped and uniformly compressed in the dark central minimum of the doughnut LG pulse. The hollow-structured LG laser has potential applications in the generation of x-rays with orbital angular momentum, plasma accelerators, fast ignition for inertial confinement fusion, and pulsars in the astrophysical environment.

  14. Intense short-pulse lasers irradiating wire and hollow plasma fibers.

    PubMed

    Zhou, C T; He, X T; Chew, L Y

    2011-03-15

    When an intense laser pulse irradiates a solid-density foil target, electrons produced at the relativistic critical density can be accelerated to relativistic energy by the ponderomotive force. When a plasma fiber is attached to the back of the foil, the produced relativistic electrons are guided to propagate along the fiber for a long distance, because the high-current electron beam induces strong radial electric fields in the fiber. Transport and heating of intense laser-driven relativistic electrons in both wire and hollow plasma fibers are compared theoretically and numerically. We found that the coupling efficiency from the laser to the plasma fiber depends on the fiber structure. Because of the enhanced return currents in the wire fiber, the temperature in the wire fiber is higher than that in the hollow fiber. PMID:21403730

  15. Intense isolated attosecond pulse generation from relativistic laser plasmas using few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Ma, Guangjin; Dallari, William; Borot, Antonin; Krausz, Ferenc; Yu, Wei; Tsakiris, George D.; Veisz, Laszlo

    2015-03-01

    We have performed a systematic study through particle-in-cell simulations to investigate the generation of attosecond pulse from relativistic laser plasmas when laser pulse duration approaches the few-cycle regime. A significant enhancement of attosecond pulse energy has been found to depend on laser pulse duration, carrier envelope phase, and plasma scale length. Based on the results obtained in this work, the potential of attaining isolated attosecond pulses with ˜100 μJ energy for photons >16 eV using state-of-the-art laser technology appears to be within reach.

  16. Intense isolated attosecond pulse generation from relativistic laser plasmas using few-cycle laser pulses

    SciTech Connect

    Ma, Guangjin; Dallari, William; Borot, Antonin; Tsakiris, George D.; Veisz, Laszlo; Krausz, Ferenc; Yu, Wei

    2015-03-15

    We have performed a systematic study through particle-in-cell simulations to investigate the generation of attosecond pulse from relativistic laser plasmas when laser pulse duration approaches the few-cycle regime. A significant enhancement of attosecond pulse energy has been found to depend on laser pulse duration, carrier envelope phase, and plasma scale length. Based on the results obtained in this work, the potential of attaining isolated attosecond pulses with ∼100 μJ energy for photons >16 eV using state-of-the-art laser technology appears to be within reach.

  17. Ultra Intense Laser Pulse Interactions with Planer and Spherical Plasmas for Fast Ignitor

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuo A.

    1999-11-01

    The fast ignitor concept requires the guiding or penetration of an ultra-intense laser close to a highly compressed (1000 times solid density) core and the generation of energetic electrons (MeV). Ultra-intense laser plasma interactions have been intensively studied using the Peta Watt Module (PWM) laser system synchronized with the GEKKO XII laser system. The ultra-intense laser pulse of 50J energy, 0.5-1 psec pulse width and 1053 nm laser wavelength could be focused onto a preformed plasma created on a solid target at an intensity of 1e19 W/cm2. The preformed plasma had a cut-off density surface at around 100 micron from the surface. Changing the focus position of this 100 TW laser pulse relative to the preformed plasma, we found an anomalous mode. Side view of x-ray pinhole camera showed that there was a local tiny spot almost at the surface of the solid target which indicates the propagation of the pulse in the long scale-length plasma into an over-dense region for over 100 micorn distance. The erergy spectrum and angular distribution of more than MeV electrons were measured. Its energy transport was studied with K-a spectroscopy. The backscattered light of the ultra-intense laser light was spectrally and spatially resolved. The backscattered light image showed several hot spots within the focused region. The spatilally resolved spectra of the backscattered light were totally different at the hot spots and surrounding regions. The details of neutron spectra were measured using ``MANDALA" neutron spectormeters with a total of 841 channel photo-multiplier detectors. The data indicates that deuterium ions were accelerated by the hot electrons up to 100 keV and created beam fusion reactions within solid CD targets. Guiding channels were created utilizing a ponderomotive self-focusing in preformed plasmas created on a solid target. The self-focus channel was measured by both UV and x-ray laser probes. The details of the experiment as well as the theoretical

  18. Hollow screw-like drill in plasma using an intense Laguerre–Gaussian laser

    PubMed Central

    Wang, Wenpeng; Shen, Baifei; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

    2015-01-01

    With the development of ultra-intense laser technology, MeV ions can be obtained from laser–foil interactions in the laboratory. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction. Ion acceleration in an azimuthal orientation was scarcely studied. In this research, a doughnut Laguerre–Gaussian (LG) laser is used for the first time to examine laser–plasma interaction in the relativistic intensity regime in three-dimensional particle-in-cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw-like drill of an mode laser. The angular momentum of particles in the longitudinal direction produced by the LG laser is enhanced compared with that produced by the usual laser pulses, such as linearly and circularly polarized Gaussian pulses. Moreover, the particles (including electrons and ions) can be trapped and uniformly compressed in the dark central minimum of the doughnut LG pulse. The hollow-structured LG laser has potential applications in the generation of x-rays with orbital angular momentum, plasma accelerators, fast ignition for inertial confinement fusion, and pulsars in the astrophysical environment. PMID:25651780

  19. Electron acceleration in combined intense laser fields and self-consistent quasistatic fields in plasma

    SciTech Connect

    Qiao Bin; He, X.T.; Zhu Shaoping; Zheng, C.Y.

    2005-08-15

    The acceleration of plasma electron in intense laser-plasma interaction is investigated analytically and numerically, where the conjunct effect of laser fields and self-consistent spontaneous fields (including quasistatic electric field E{sub s}{sup l}, azimuthal quasistatic magnetic field B{sub s{theta}} and the axial one B{sub sz}) is completely considered for the first time. An analytical relativistic electron fluid model using test-particle method has been developed to give an explicit analysis about the effects of each quasistatic fields. The ponderomotive accelerating and scattering effects on electrons are partly offset by E{sub s}{sup l}, furthermore, B{sub s{theta}} pinches and B{sub sz} collimates electrons along the laser axis. The dependences of energy gain and scattering angle of electron on its initial radial position, plasma density, and laser intensity are, respectively, studied. The qualities of the relativistic electron beam (REB), such as energy spread, beam divergence, and emitting (scattering) angle, generated by both circularly polarized (CP) and linearly polarized (LP) lasers are studied. Results show CP laser is of clear advantage comparing to LP laser for it can generate a better REB in collimation and stabilization.

  20. Intense ion beams accelerated by relativistic laser plasmas

    NASA Astrophysics Data System (ADS)

    Roth, Markus; Cowan, Thomas E.; Gauthier, Jean-Claude J.; Allen, Matthew; Audebert, Patrick; Blazevic, Abel; Fuchs, Julien; Geissel, Matthias; Hegelich, Manuel; Karsch, S.; Meyer-ter-Vehn, Jurgen; Pukhov, Alexander; Schlegel, Theodor

    2001-12-01

    We have studied the influence of the target properties on laser-accelerated proton and ion beams generated by the LULI multi-terawatt laser. A strong dependence of the ion emission on the surface conditions, conductivity, shape and material of the thin foil targets were observed. We have performed a full characterization of the ion beam using magnetic spectrometers, Thompson parabolas, radiochromic film and nuclear activation techniques. The strong dependence of the ion beam acceleration on the conditions on the target back surface was found in agreement with theoretical predictions based on the target normal sheath acceleration (TNSA) mechanism. Proton kinetic energies up to 25 MeV have been observed.

  1. Parallel PIC Simulations of Short-Pulse High Intensity Laser Plasma Interactions.

    NASA Astrophysics Data System (ADS)

    Lasinski, B. F.; Still, C. H.; Langdon, A. B.

    2001-10-01

    We extend our previous simulations of high intensity short pulse laser plasma interactions footnote B. F. Lasinski, A. B. Langdon, S. P. Hatchett, M. H. Key, and M. Tabak, Phys. Plasmas 6, 2041 (1999); S. C. Wilks and W. L. Kruer, IEEE Journal of Quantum Electronics 11, 1954 (1997). to 3D and to much larger systems in 2D using our new, modern, 3D, electromagnetic, fully relativistic, massively parallel PIC code. We study the generation of hot electrons and energetic ions and the associated complex phenomena. Laser light filamentation and the formation of high static magnetic fields are described.

  2. Parallel PIC Simulations of Ultra-High Intensity Laser Plasma Interactions.

    NASA Astrophysics Data System (ADS)

    Lasinski, B. F.; Still, C. H.; Langdon, A. B.; Wilks, S. C.; Hatchett, S. P.; Hinkel, D. E.

    1999-11-01

    We extend our previous simulations of high intensity short pulse laser plasma interactionsfootnote B. F. Lasinski, A. B. Langdon, S. P. Hatchett, M. H. Key, and M. Tabak, Phys. Plasmas 6, 2041 (1999); S. C. Wilks and W. L. Kruer, IEEE Journal of Quantum Electronics 11, 1954 (1997). to 3D and to much larger systems in 2D using our new, modern, 3D, electromagnetic, fully relativistic, massively parallel PIC code. Our simulation parameters are guided by the recent Petawatt experiments at Livermore. We study the generation of hot electrons and energetic ions and the associated complex phenomena. Laser light filamentation and the formation of high static magnetic fields are described.

  3. Effect of Relativistic Plasma on Extreme-Ultraviolet Harmonic Emission from Intense Laser-Matter Interactions

    SciTech Connect

    Krushelnick, K.; Dangor, A. E.; Mangles, S. P. D.; Rozmus, W.; Wagner, U.; Habara, H.; Norreys, P. A.; Beg, F. N.; Wei, M. S.; Bochkarev, S. G.; Clark, E. L.; Gopal, A.; Evans, R. G.; Robinson, A. P. L.; Tatarakis, M.; Zepf, M.

    2008-03-28

    Experiments were performed in which intense laser pulses (up to 9x10{sup 19} W/cm{sup 2}) were used to irradiate very thin (submicron) mass-limited aluminum foil targets. Such interactions generated high-order harmonic radiation (greater than the 25th order) which was detected at the rear of the target and which was significantly broadened, modulated, and depolarized because of passage through the dense relativistic plasma. The spectral modifications are shown to be due to the laser absorption into hot electrons and the subsequent sharply increasing relativistic electron component within the dense plasma.

  4. Intensity Distribution of Laser Induced Plasma Generated at Different Ambient Gas Preassure

    NASA Astrophysics Data System (ADS)

    Sarmiento, Rafael; Cabanzo, Rafael; Mejia-Ospino, Enrique

    2008-04-01

    In this work, intensity distributions of laser induced plasmas have been measured by emission with two-dimensional spatial resolution and temporal resolution. The plasmas have been generated on the surfaces of steel samples at different pressures of air and argon, in the ranges from l*10-6 to 680 Torr. We compare the features of the intensity spatial and temporal distribution in the two ambient studied here. We observed that the maxima values of intensity are obtained when the pressure is maxima. The features of intensity distribution show a significant change with the ambient and gas pressure. Also, we have measured how change the size of the plasma plume with the pressure at two different ambient.

  5. Effects of relativistic electron temperature on parametric instabilities for intense laser propagation in underdense plasma

    SciTech Connect

    Zhao, Yao; Zheng, Jun; Chen, Min; Yu, Lu-Le; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming E-mail: zhengming.sheng@strath.ac.uk

    2014-11-15

    Effects of relativistic electron temperature on stimulated Raman scattering and stimulated Brillouin scattering instabilities for high intensity lasers propagating in underdense plasma are studied theoretically and numerically. The dispersion relations for these instabilities are derived from the relativistic fluid equation. For a wide range of laser intensity and electron temperature, it is found that the maximum growth rate and the instability region in k-space can be reduced at relativistic electron temperature. Particle-in-cell simulations are carried out, which confirm the theoretical analysis.

  6. Energy relaxation of intense laser pulse-produced plasmas

    NASA Astrophysics Data System (ADS)

    Shihab, M.; Abou-Koura, G. H.; El-Siragy, N. M.

    2016-05-01

    We describe a collisional radiative model (CRE) of homogeneously expanded nickel plasmas in vacuum. The CRE model is coupled with two separate electron and ion temperature magneto-hydrodynamic equations. On the output, the model provides the temporal variation of the electron temperature, ion temperature, and average charge state. We demonstrate the effect of three-body recombination ({∝}N_e T^{-9/2}_e) on plasma parameters, as it changes the time dependence of electron temperature from t^{-2} to t^{-1} and exhibits a pronounced effect leading to a freezing feature in the average charge state. In addition, the effect of the three-body recombination on the warm up of ions and delaying the equilibration is addressed.

  7. Dense Helical Electron Bunch Generation in Near-Critical Density Plasmas with Ultrarelativistic Laser Intensities

    PubMed Central

    Hu, Ronghao; Liu, Bin; Lu, Haiyang; Zhou, Meilin; Lin, Chen; Sheng, Zhengming; Chen, Chia-erh; He, Xiantu; Yan, Xueqing

    2015-01-01

    The mechanism for emergence of helical electron bunch(HEB) from an ultrarelativistic circularly polarized laser pulse propagating in near-critical density(NCD) plasma is investigated. Self-consistent three-dimensional(3D) Particle-in-Cell(PIC) simulations are performed to model all aspects of the laser plasma interaction including laser pulse evolution, electron and ion motions. At a laser intensity of 1022 W/cm2, the accelerated electrons have a broadband spectrum ranging from 300 MeV to 1.3 GeV, with the charge of 22 nano-Coulombs(nC) within a solid-angle of 0.14 Sr. Based on the simulation results, a phase-space dynamics model is developed to explain the helical density structure and the broadband energy spectrum. PMID:26503634

  8. Dense Helical Electron Bunch Generation in Near-Critical Density Plasmas with Ultrarelativistic Laser Intensities.

    PubMed

    Hu, Ronghao; Liu, Bin; Lu, Haiyang; Zhou, Meilin; Lin, Chen; Sheng, Zhengming; Chen, Chia-erh; He, Xiantu; Yan, Xueqing

    2015-01-01

    The mechanism for emergence of helical electron bunch(HEB) from an ultrarelativistic circularly polarized laser pulse propagating in near-critical density(NCD) plasma is investigated. Self-consistent three-dimensional(3D) Particle-in-Cell(PIC) simulations are performed to model all aspects of the laser plasma interaction including laser pulse evolution, electron and ion motions. At a laser intensity of 10(22) W/cm(2), the accelerated electrons have a broadband spectrum ranging from 300 MeV to 1.3 GeV, with the charge of 22 nano-Coulombs(nC) within a solid-angle of 0.14 Sr. Based on the simulation results, a phase-space dynamics model is developed to explain the helical density structure and the broadband energy spectrum. PMID:26503634

  9. Channeling of multikilojoule high-intensity laser beams in an inhomogeneous plasma

    SciTech Connect

    Ivancic, S.; Haberberger, D.; Habara, H.; Iwawaki, T.; Anderson, K. S.; Craxton, R. S.; Froula, D. H.; Meyerhofer, D. D.; Stoeckl, C.; Tanaka, K. A.; Theobald, W.

    2015-05-01

    Channeling experiments were performed that demonstrate the transport of high-intensity (>10¹⁸ W/cm²), multikilojoule laser light through a millimeter-sized, inhomogeneous (~300-μm density scale length) laser produced plasma up to overcritical density, which is an important step forward for the fast-ignition concept. The background plasma density and the density depression inside the channel were characterized with a novel optical probe system. The channel progression velocity was measured, which agrees well with theoretical predictions based on large scale particle-in-cell simulations, confirming scaling laws for the required channeling laser energy and laser pulse duration, which are important parameters for future integrated fast-ignition channeling experiments.

  10. Channeling of multikilojoule high-intensity laser beams in an inhomogeneous plasma.

    PubMed

    Ivancic, S; Haberberger, D; Habara, H; Iwawaki, T; Anderson, K S; Craxton, R S; Froula, D H; Meyerhofer, D D; Stoeckl, C; Tanaka, K A; Theobald, W

    2015-05-01

    Channeling experiments were performed that demonstrate the transport of high-intensity (>10(18)W/cm(2)), multikilojoule laser light through a millimeter-sized, inhomogeneous (∼300-μm density scale length) laser-produced plasma up to overcritical density, which is an important step forward for the fast-ignition concept. The background plasma density and the density depression inside the channel were characterized with a novel optical probe system. The channel progression velocity was measured, which agrees well with theoretical predictions based on large scale particle-in-cell simulations, confirming scaling laws for the required channeling laser energy and laser pulse duration, which are important parameters for future integrated fast-ignition channeling experiments. PMID:26066111

  11. One-dimensional intense laser pulse solitons in a plasma

    SciTech Connect

    Sudan, R.N.; Dimant, Y.S.; Shiryaev, O.B.

    1997-05-01

    A general analytical framework is developed for the nonlinear dispersion relations of a class of large amplitude one-dimensional isolated envelope solitons for modulated light pulse coupled to electron plasma waves, previously investigated numerically [Kozlov {ital et al.}, Zh. Eksp. Teor. Fiz. {bold 76}, 148 (1979); Kaw {ital et al.}, Phys. Rev. Lett. {bold 68}, 3172 (1992)]. The analytical treatment of weakly nonlinear solitons [Kuehl and Zhang, Phys. Rev. E {bold 48}, 1316 (1993)] is extended to the strongly nonlinear limit. {copyright} {ital 1997 American Institute of Physics.}

  12. Effects of the plasma profiles on photon and pair production in ultrahigh intensity laser solid interaction

    SciTech Connect

    Tian, Y. X.; Jin, X. L. Yan, W. Z.; Li, J. Q.; Li, B.; Yu, J. Q.

    2015-12-15

    The model of photon and pair production in strong field quantum electrodynamics is implemented into our 1D3V particle-in-cell code with Monte Carlo algorithm. Using this code, the evolution of the particles in ultrahigh intensity laser (∼10{sup 23} W/cm{sup 2}) interaction with aluminum foil target is observed. Four different initial plasma profiles are considered in the simulations. The effects of initial plasma profiles on photon and pair production, energy spectra, and energy evolution are analyzed. The results imply that one can set an optimal initial plasma profile to obtain the desired photon distributions.

  13. Effect of background gas pressure and laser pulse intensity on laser induced plasma radiation of copper samples

    NASA Astrophysics Data System (ADS)

    Mehrabian, S.; Aghaei, M.; Tavassoli, S. H.

    2010-04-01

    Study of laser induced plasma emission of Cu in one dimension is numerically carried out. Effects of different background gas pressure (He), 100, 500, and 760 torr, and laser pulse intensities, 0.5, 0.7, and 1 GW/cm2, on the plasma emission as well as ablation processes are investigated. Under a specified condition, heat conduction equation in the target accompanied with gas dynamic equations in the plume is solved simultaneously. The mentioned equations are coupled to each other through the Knudsen layer conditions and the energy and mass balances at the interface between the target and the vapor. The Bremsstrahlung radiation of plasma and the spectral emission of copper atoms are studied under various background gas pressure and laser pulse intensities. Furthermore, number density of He, Cu, and the electron, pressure, and temperature of the plume under various conditions are obtained. In the early time after laser pulse, plasma radiation is mainly due to the Bremsstrahlung radiation while after some 10 ns, the plasma radiation is dominated by spectral emission of Cu atoms. A similar uncoupling is observed spatially. The Bremsstrahlung emission is dominant near the sample surface while at farther points the spectral emission is the dominant one. By increase in the background pressure and also the pulse intensity, the dominancy of the spectral emission would occur later in time and farther in position.

  14. Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse

    DOE PAGESBeta

    Bang, W.

    2015-07-02

    Energetic deuterium ions from large deuterium clusters (>10 nm diameter) irradiated by an intense laser pulse (>10¹⁶ W/cm²) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We show an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the availablemore » experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10 - keV deuterium fusion plasma for 10 ns.« less

  15. Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse

    SciTech Connect

    Bang, W.

    2015-07-02

    Energetic deuterium ions from large deuterium clusters (>10 nm diameter) irradiated by an intense laser pulse (>10¹⁶ W/cm²) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We show an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the available experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10 - keV deuterium fusion plasma for 10 ns.

  16. Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse.

    PubMed

    Bang, W

    2015-07-01

    Energetic deuterium ions from large deuterium clusters (>10nm diameter) irradiated by an intense laser pulse (>10(16)W/cm(2)) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We present an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the available experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10-keV deuterium fusion plasma for 10ns. PMID:26274289

  17. Radiation emission from ultra-relativistic plasma electrons in short-intense laser light interactions

    NASA Astrophysics Data System (ADS)

    Ondarza-Rovira, R.; Boyd, TJM

    2016-05-01

    Intense femtosecond laser light incident on overcritical density plasmas has shown to emit a prolific number of high-order harmonics of the driver frequency, with spectra characterised by power-law decays. When the laser pulse is p-polarised, plasma effects do modify the harmonic spectrum, weakening the so-called universal decay index p = 8/3 to 5/3. In this work appeal is made to a single particle radiation model in support of the predictions from particle-in-cell (PIC) simulations. Using these, we further show that the emission radiated by electrons -those that are relativistically accelerated inside the plasma, after being expelled into vacuum, the so-called Brunel electrons- is characterised not only by the plasma line but also by ultraviolet harmonic orders characterised by the 5/3 decay index.

  18. Plasma channel charging by an intense short pulse laser and ion Coulomb explosion

    SciTech Connect

    Tripathi, V.K.; Taguchi, T.; Liu, C.S.

    2005-04-15

    The combined effects of relativistic self-focusing and the expulsion of electrons by the ponderomotive force of a radially focused laser create an ion channel, depleted of electrons, of radius r{sub 0}{approx}c/{omega}{sub p}, where {omega}{sub p} is the electron plasma frequency. This charging process takes place on plasma period, {omega}{sub p}{sup -1}, time scale. The Coulomb explosion of the channel accelerates ions to several hundreds of keV energy in about an ion plasma period, constituting an important ion acceleration mechanism by short pulse intense laser. In the case of a deuterium-tritium plasma, the accelerated ions can produce fusion energy with an efficiency of {approx}0.5%.

  19. Correlation of laser ablation plasma emission with ICP-AES signal intensity

    SciTech Connect

    Fernandez, A.J.; Mao, X.L.; Shannon, M.A.

    1994-12-31

    Laser ablation offers many favorable characteristics for direct solid sample chemical analysis. However, the technique usually provides poor precision in comparison to solution nebulization. The primary contributor to this imprecision is the irreproducibility of the laser material interaction. This paper describes a technique for monitoring changes in the laser material interaction directly, and using these data to improve inductively coupled atomic emission spectroscopy (ICP-AES). Simultaneous measurements of the spectral emission intensity in the laser-induced plasma (LIP) and the ICP-AES were made under different power density conditions. The LIP spatial profile and excitation temperature was measured. The data from the LIP show a strong correlation with ICP-AES signal intensity. Both emission signals increase linearly with the laser power density (log-log) and show a change in the slope for different spot sizes and laser powers. These results support the occurrence of two different ablation mechanisms, a less efficient interaction dominating at the higher power densities (> 1 GW/cm2) and a more efficient interaction in the lower power density regimes. The benefits of using simultaneous monitoring of the laser induced plasma for chemical analysis by ICP-AES will be discussed.

  20. Swarm of ultra-high intensity attosecond pulses from laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Bychenkov, V. Y. U.; Krushelnick, K.; Maksimchuk, A.; Popov, K. I.; Rozmus, W.

    2010-08-01

    We report on the realistic scheme of intense X-rays and γ-radiation generation in a laser interaction with thin foils. It is based on the relativistic mirror concept, i.e., a flying thin plasma slab interacts with a counterpropagating laser pulse, reflecting part of it in the form of an intense ultra-short electromagnetic pulse having an up-shifted frequency. A series of relativistic mirrors is generated in the interaction of the intense laser with a thin foil target as the pulse tears off and accelerates thin electron layers. A counterpropagating pulse is reflected by these flying layers in the form of a swarm of ultra-short pulses resulting in a significant energy gain of the reflected radiation due to the momentum transfer from flying layers.

  1. Experiment and simulation of novel liquid crystal plasma mirrors for high contrast, intense laser pulses

    PubMed Central

    Poole, P. L.; Krygier, A.; Cochran, G. E.; Foster, P. S.; Scott, G. G.; Wilson, L. A.; Bailey, J.; Bourgeois, N.; Hernandez-Gomez, C.; Neely, D.; Rajeev, P. P.; Freeman, R. R.; Schumacher, D. W.

    2016-01-01

    We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors. PMID:27557592

  2. Experiment and simulation of novel liquid crystal plasma mirrors for high contrast, intense laser pulses.

    PubMed

    Poole, P L; Krygier, A; Cochran, G E; Foster, P S; Scott, G G; Wilson, L A; Bailey, J; Bourgeois, N; Hernandez-Gomez, C; Neely, D; Rajeev, P P; Freeman, R R; Schumacher, D W

    2016-01-01

    We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors. PMID:27557592

  3. Controlling two plasmon decay instability in intense femtosecond laser driven plasmas

    SciTech Connect

    Singh, Prashant Kumar; Adak, Amitava; Lad, Amit D.; Chatterjee, Gourab; Ravindra Kumar, G.; Brijesh, P.

    2015-11-15

    We investigate the onset of the two-plasmon-decay (TPD) instability in intense femtosecond laser-solid interaction. In particular, this instability, originating at the quarter critical electron density surface in the inhomogeneous plasma, is explored for a wide range of laser parameters-energy, pulse duration, and intensity contrast. By varying these laser parameters, we demonstrate ways to excite and control the growth of the TPD process. The pulse duration scan carried out under a constant laser fluence reveals the pulse width dependent nature of TPD growth. The spectral splitting of the TPD induced three-halves harmonic emission is used to infer the electron temperature near the quarter critical density surface. Moreover, by varying the laser contrast over four orders of magnitude, we find that the intensity threshold of three-halves harmonic emission increases by nearly two orders of magnitude. This contrast dependent intensity threshold for the emission of three-halves harmonic can be a useful diagnostic of the laser contrast.

  4. Direct laser acceleration of electron by an ultra intense and short-pulsed laser in under-dense plasma

    SciTech Connect

    Li, Y. Y.; Gu, Y. J.; Zhu, Z.; Li, X. F.; Ban, H. Y.; Kong, Q.; Kawata, S.

    2011-05-15

    Direct laser acceleration (DLA) of electron by an ultra intense and short-pulsed laser interacting with under-dense plasma is investigated based on 2.5-dimensional particle-in-cell simulation. A high-density electron beam is generated by the laser longitudinal ponderomotive force. Although the total number of DLA electrons is significantly smaller than the number of electrons trapped in the bubble, the total charge of high-energy DLA electrons (E>800MeV) reaches 67 pC/{mu}m. It is found that the electron beam occurs in a two-stage acceleration, i.e., accelerated in vacuum by the laser directly soon after a DLA process in plasma. The beam is accelerated violently with effective acceleration gradient in 100 GeV/cm. The energy spectrum of electrons presents a Maxwellian distribution with the highest energy of about 3.1 GeV. The dependence of maximum electron energy and electric quantity with laser intensity, laser width, pulse duration, and initial plasma density are also studied.

  5. Propagation of an ultrashort, intense laser pulse in a relativistic plasma

    SciTech Connect

    Ritchie, B.; Decker, C.D.

    1997-12-31

    A Maxwell-relativistic fluid model is developed for the propagation of an ultrashort, intense laser pulse through an underdense plasma. The separability of plasma and optical frequencies ({omega}{sub p} and {omega} respectively) for small {omega}{sub p}/{omega} is not assumed; thus the validity of multiple-scales theory (MST) can be tested. The theory is valid when {omega}{sub p}/{omega} is of order unity or for cases in which {omega}{sub p}/{omega} {much_lt} 1 but strongly relativistic motion causes higher-order plasma harmonics to be generated which overlap the region of the first-order laser harmonic, such that MST would not expected to be valid although its principal validity criterion {omega}{sub p}/{omega} {much_lt} 1 holds.

  6. Effects of laser-plasma interactions on terahertz radiation from solid targets irradiated by ultrashort intense laser pulses

    SciTech Connect

    Li Chun; Zhou Mulin; Ding Wenjun; Du Fei; Liu Feng; Li Yutong; Wang Weimin; Ma Jinglong; Chen Liming; Lu Xin; Dong Quanli; Wang Zhaohua; Wei Zhiyi; Sheng Zhengming; Zhang Jie; Lou Zheng; Shi Shengcai

    2011-09-15

    Interactions of 100-fs laser pulses with solid targets at intensities of 10{sup 18} W/cm{sup 2} and resultant terahertz (THz) radiation are studied under different laser contrast ratio conditions. THz emission is measured in the specular reflection direction, which appears to decrease as the laser contrast ratio varies from 10{sup -8} to 10{sup -6}. Correspondingly, the frequency spectra of the reflected light are observed changing from second harmonic dominant, three-halves harmonic dominant, to vanishing of both harmonics. Two-dimensional particle-in-cell simulation also suggests that this observation is correlated with the plasma density scale length change. The results demonstrate that the THz emission is closely related to the laser-plasma interaction processes. The emission is strong when resonance absorption is a key feature of the interaction, and becomes much weaker when parametric instabilities dominate.

  7. Measurement of ultrafast dynamics in the interaction of intense laser pulses with gases, clusters, and plasma waveguidesa)

    NASA Astrophysics Data System (ADS)

    Kim, K. Y.; Alexeev, I.; Milchberg, H. M.

    2005-05-01

    Femtosecond time-resolved dynamics in the interaction of high intensity, ultrashort laser pulses with various targets—gases, nanometer-size clusters, and plasma waveguides—was studied using a new ultrafast optical diagnostic: Single-shot supercontinuum spectral interferometry (SSSI). The diagnostic measures ultrarapid transients induced by an intense laser pulse in the complex refractive index of the evolving target medium, providing a direct view of how the laser-produced disturbances, such as plasma densities, evolve in time and space. Using the SSSI diagnostic (i) the laser-induced double step ionization of helium, (ii) time-resolved explosion dynamics of intense-laser-heated clusters, and (iii) the coupling and guiding of intense laser pulses injected into a plasma waveguide were examined.

  8. High harmonic generation in underdense plasmas by intense laser pulses with orbital angular momentum

    SciTech Connect

    Mendonça, J. T.; Vieira, J.

    2015-12-15

    We study high harmonic generation produced by twisted laser pulses, with orbital angular momentum in the relativistic regime, for pulse propagation in underdense plasma. We consider fast time scale processes associated with an ultra-short pulse, where the ion motion can be neglected. We use both analytical models and numerical simulations using a relativistic particle-in-cell code. The present description is valid for relativistic laser intensities, when the normalized field amplitude is much larger than one, a ≫ 1. We also discuss two distinct processes associated with linear and circular polarization. Using both analytical solutions and particle-in-cell simulations, we are able to show that, for laser pulses in a well defined Laguerre-Gauss mode, angular momentum conservation is observed during the process of harmonic generation. Intensity modulation of the harmonic spectrum is also verified, as imposed by the nonlinear time-scale for energy transfer between different harmonics.

  9. High harmonic generation in underdense plasmas by intense laser pulses with orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.; Vieira, J.

    2015-12-01

    We study high harmonic generation produced by twisted laser pulses, with orbital angular momentum in the relativistic regime, for pulse propagation in underdense plasma. We consider fast time scale processes associated with an ultra-short pulse, where the ion motion can be neglected. We use both analytical models and numerical simulations using a relativistic particle-in-cell code. The present description is valid for relativistic laser intensities, when the normalized field amplitude is much larger than one, a ≫ 1. We also discuss two distinct processes associated with linear and circular polarization. Using both analytical solutions and particle-in-cell simulations, we are able to show that, for laser pulses in a well defined Laguerre-Gauss mode, angular momentum conservation is observed during the process of harmonic generation. Intensity modulation of the harmonic spectrum is also verified, as imposed by the nonlinear time-scale for energy transfer between different harmonics.

  10. Monoenergetic proton emission from nuclear reaction induced by high intensity laser-generated plasma

    SciTech Connect

    Torrisi, L.; Cavallaro, S.; Giuffrida, L.; Cutroneo, M.; Krasa, J.; Margarone, D.; Velyhan, A.; Ullschmied, J.; Kravarik, J.; Wolowski, J.; Szydlowski, A.; Rosinski, M.

    2012-02-15

    A 10{sup 16} W/cm{sup 2} Asterix laser pulse intensity, 1315 nm at the fundamental frequency, 300 ps pulse duration, was employed at PALS laboratory of Prague, to irradiate thick and thin primary CD{sub 2} targets placed inside a high vacuum chamber. The laser irradiation produces non-equilibrium plasma with deutons and carbon ions emission with energy of up to about 4 MeV per charge state, as measured by time-of-flight (TOF) techniques by using ion collectors and silicon carbide detectors. Accelerated deutons may induce high D-D cross section for fusion processes generating 3 MeV protons and 2.5 MeV neutrons, as measured by TOF analyses. In order to increase the mono-energetic proton yield, secondary CD{sub 2} targets can be employed to be irradiated by the plasma-accelerated deutons. Experiments demonstrated that high intensity laser pulses can be employed to promote nuclear reactions from which characteristic ion streams may be developed. Results open new scenario for applications of laser-generated plasma to the fields of ion sources and ion accelerators.

  11. Guiding of high intensity ultrashort laser pulses in plasma channels produced with the dual laser pulse ignitor-heater technique

    SciTech Connect

    Volfbeyn, P.; Leemans, W.P.

    1998-07-01

    The authors present results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme is proposed and experimentally tested in hydrogen and nitrogen. It makes use of two laser pulses. The Ignitor, an ultrashort (< 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used subsequently to heat the existing spark via inverse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. The channel density was diagnosed with time resolved longitudinal interferometry. From these measurements the plasma temperature was inferred. The guiding properties of the channels were tested by injecting a > 5 {times} 10{sup 17} W/cm{sup 2}, 75 fs laser pulse.

  12. Target micro-displacement measurement by a "comb" structure of intensity distribution in laser plasma propulsion

    NASA Astrophysics Data System (ADS)

    Zheng, Z. Y.; Zhang, S. Q.; Gao, L.; Gao, H.

    2015-05-01

    A "comb" structure of beam intensity distribution is designed and achieved to measure a target displacement of micrometer level in laser plasma propulsion. Base on the "comb" structure, the target displacement generated by nanosecond laser ablation solid target is measured and discussed. It is found that the "comb" structure is more suitable for a thin film target with a velocity lower than tens of millimeters per second. Combing with a light-electric monitor, the `comb' structure can be used to measure a large range velocity.

  13. Observation of plasma density dependence of electromagnetic soliton excitation by an intense laser pulse

    SciTech Connect

    Sarri, G.; Kar, S.; Kourakis, I.; Borghesi, M.; Romagnani, L.; Bulanov, S. V.; Cecchetti, C. A.; Gizzi, L. A.; Galimberti, M.; Heathcote, R.; Jung, R.; Osterholz, J.; Willi, O.; Schiavi, A.

    2011-08-15

    The experimental evidence of the correlation between the initial electron density of the plasma and electromagnetic soliton excitation at the wake of an intense (10{sup 19} W/cm{sup 2}) and short (1 ps) laser pulse is presented. The spatial distribution of the solitons, together with their late time evolution into post-solitons, is found to be dependent upon the background plasma parameters, in agreement with published analytical and numerical findings. The measured temporal evolution and electrostatic field distribution of the structures are consistent with their late time evolution and the occurrence of multiple merging of neighboring post-solitons.

  14. Ensemble of ultra-high intensity attosecond pulses from laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Maksimchuk, A.; Krushelnick, K.; Popov, K. I.; Bychenkov, V. Yu.; Rozmus, W.

    2010-01-01

    The efficient generation of intense X-rays and γ-radiation is studied. The scheme is based on the relativistic mirror concept, i.e., a flying thin plasma slab interacts with a counterpropagating laser pulse, reflecting part of it in the form of an intense ultra-short electromagnetic pulse having an up-shifted frequency. In the proposed scheme a series of relativistic mirrors is generated in the interaction of the intense laser with a thin foil target as the pulse tears off and accelerates thin electron layers. A counterpropagating pulse is reflected by these flying layers in the form of an ensemble of ultra-short pulses resulting in a significant energy gain of the reflected radiation due to the momentum transfer from flying layers.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  16. Electrons trajectories around a bubble regime in intense laser plasma interaction

    SciTech Connect

    Lu, Ding; Xie, Bai-Song; Ali Bake, Muhammad; Sang, Hai-Bo; Zhao, Xue-Yan; Wu, Hai-Cheng

    2013-06-15

    Some typical electrons trajectories around a bubble regime in intense laser plasma interaction are investigated theoretically. By considering a modification of the fields and ellipsoid bubble shape due to the presence of residual electrons in the bubble regime, we study in detail the electrons nonlinear dynamics with or without laser pulse. To examine the electron dynamical behaviors, a set of typical electrons, which locate initially at the front of the bubble, on the transverse edge and at the bottom of the bubble respectively, are chosen for study. It is found that the range of trapped electrons in the case with laser pulse is a little narrower than that without laser pulse. The partial phase portraits for electrons around the bubble are presented numerically and their characteristic behaviors are discussed theoretically. Implication of our results on the high quality electron beam generation is also discussed briefly.

  17. Second harmonic generation by self-focusing of intense hollow Gaussian laser beam in collisionless plasma

    NASA Astrophysics Data System (ADS)

    Purohit, Gunjan; Rawat, Priyanka; Gauniyal, Rakhi

    2016-01-01

    The effect of self focused hollow Gaussian laser beam (HGLB) (carrying null intensity in center) on the excitation of electron plasma wave (EPW) and second harmonic generation (SHG) has been investigated in collisionless plasma, where relativistic-ponderomotive and only relativistic nonlinearities are operative. The relativistic change of electron mass and the modification of the background electron density due to ponderomotive nonlinearity lead to self-focusing of HGLB in plasma. Paraxial ray theory has been used to derive coupled equations for the self focusing of HGLB in plasma, generation of EPW, and second harmonic. These coupled equations are solved analytically and numerically to study the laser intensity in the plasma, electric field associated with the excited EPW, and the power of SHG. Second harmonic emission is generated due to nonlinear coupling between incident HGLB and EPW satisfying the proper phase matching conditions. The results show that the effect of including the ponderomotive nonlinearity is significant on the generation of EPW and second harmonic. The electric field associated with EPW and the power of SHG are found to be highly sensitive to the order of the hollow Gaussian beam.

  18. Laser guiding at relativistic intensities and wakefield particle acceleration in plasma channels

    SciTech Connect

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

    2004-08-01

    Electron beams with hundreds of picoCoulombs of charge in percent energy spread at above 80 MeV, and with few milliradian divergence, have been produced for the first time in a high gradient laser wakefield accelerator by guiding the drive laser pulse. Channels formed by hydrodynamic shock were used to guide acceleration relevant laser intensities of at least 1E18W/cm2 at the guide output over more than 10 Rayleigh lengths at LBNL's l'OASIS facility (10TW, 2E19W/cm2). The pondermotive force of the laser pulse drove an intense plasma wave, producing acceleration gradients on the order of 100 GV/m. Electrons were trapped from the background plasma and accelerated. By extending the acceleration length using the guiding channel, the energy of the electron beam was greatly increased, and bunches of small energy spread and low emittance were formed. Experiments varying gas jet length as well assimilations indicate that the high quality beams were formed when beam loading turned off injection after an initial load, producing an isolated bunch, and when that bunch was subsequently accelerated to the dephasing length at which point it rotated in phase space to produce low energy spread.

  19. Electron Acceleration and the Propagation of Ultrashort High-Intensity Laser Pulses in Plasmas

    SciTech Connect

    Wang, Xiaofang; Krishnan, Mohan; Saleh, Ned; Wang, Haiwen; Umstadter, Donald

    2000-06-05

    Reported are interactions of high-intensity laser pulses ({lambda}=810 nm and I{<=}3x10{sup 18} W /cm{sup 2} ) with plasmas in a new parameter regime, in which the pulse duration ({tau}=29 fs ) corresponds to 0.6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degree sign is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results. (c) 2000 The American Physical Society.

  20. High-intensity laser for Ta and Ag implantation into different substrates for plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Cutroneo, M.; Mackova, A.; Malinsky, P.; Matousek, J.; Torrisi, L.; Ullschmied, J.

    2015-07-01

    High-intensity lasers generating non-equilibrium plasma, can be employed to accelerate ions in the keV-MeV region, useful for many applications. In the present work, we performed study of ion implantation into different substrates by using a high-intensity laser at the PALS laboratory in Prague. Multi-energy ions generated by plasma from Ta and Ag targets were implanted into polyethylene and metallic substrates (Al, Ti) at energies of tens of keV per charge state. The ion emission was monitored online using time-of-flight detectors and electromagnetic deflection systems. Rutherford Backscattering Spectrometry (RBS) was used to characterise the elemental composition in the implanted substrates by ion plasma emission and to provide the implanted ion depth profiling. These last measurements enable offline plasma characterisation and provide information on the useful potentiality of multi-ion species and multi-energy ion implantation into different substrates. XPS analysis gives information on the chemical bonds and their modifications in the first superficial implanted layers. The depth distributions of implanted Ta and Ag ions were compared with the theoretical ones achieved by using the SRIM-2012 simulation code.

  1. Guiding of intense femtosecond laser pulses in fully ionized plasma channels

    NASA Astrophysics Data System (ADS)

    Downer, M. C.

    2002-11-01

    Plasma waveguides capable of guiding relativistically intense fs laser pulses without optical distortion are essential to developing GeV-scale laser wakefield accelerators, coherent short-wavelength sources and lenses for fourth-generation x-ray sources. Various approaches to guiding terawatt pulses through preformed plasma fibers inside gas-filled solid capillaries [1], and in laser-generated cylindrical shock waves [2] will be compared. We report the first implementation of a laser-generated waveguide in a Helium plasma, which provides full ionization and minimization of ionization-induced distortions of the guided pulse up to relativistic guided intensity. 80 fs laser pulses were guided at near-relativistic intensity (0.2 x 10^18 W/cm^2) over 60 Rayleigh ranges (1.5 cm) with > 50% throughput, 20 Hz repetition rate and no detectable distortion of their spectrum or 16 micron-diameter TEM_00 mode structure [3]. Channels were generated by the method developed by Milchberg et al. [2], in which a filament of He gas (300-700 Torr) was ionized and heated by a powerful line-focused Nd:YAG laser pulse. To enable waveguide formation in Helium, the method was modified by slightly (0.1%) pre-ionizing the helium to seed inverse bremsstrahlung absorption, and by lengthening (100 to 400 ps) and strengthening (0.3 to 1 J) the channel-forming laser pulse. Recent femtosecond time-resolved pump-probe experiments inside the Helium channel will be reported. The issues involved, and current progress, in upgrading performance to fully relativistic guided intensity (10^18 W/cm^2) will be discussed. [1] Ehrlich et al., Phys. Rev. Lett. 77, 4186 (1996); Hosokai et al., Opt. Lett. 25, 10 (2000); Spence et al., Phys. Rev. E 63, 015401 (2001). [2] C. G. Durfee, III and H. M. Milchberg, Phys. Rev. Lett. 71, 2409 (1993); J. Fan, et al. Appl. Phys. Lett. 73, 3064 (1998). [3] E. W. Gaul et al., Appl. Phys. Lett. 77, 4112 (2000).

  2. Radiation-Hydrodynamic Simulation of Experiments With Intense Lasers Generating Collisionless Interpenetrating Plasmas

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    Collisionless shocks, shocks generated by plasma wave interactions in regions where the collisional mean-free-path for ions is long compared to the length scale for instabilities that generate magnetic fields, are found in many astrophysical systems such as supernova remnants and planetary bow shocks. Generating conditions to investigate collisionless shock physics is difficult to achieve in a laboratory setting; however, high-energy-density physics facilities have made this a possibility. Experiments whose goal is to investigate the production and growth of magnetic fields in collisionless shocks in laboratory-scale systems are being carried out on intense lasers, several of which are measuring the plasma properties and magnetic field strength in counter-streaming, collisionless flows generated by laser ablation. This poster reports radiation-hydrodynamic simulations using the CRASH code to model the ablative flow of plasma generated in order to assess potential designs, as well as infer properties of collected data from previous experiments. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52- 08NA28616, by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-FG52-09NA29548, and by the National Laser User Facility Program, grant number DE-NA0000850.

  3. Stable long range proton acceleration driven by intense laser pulse with underdense plasmas

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Zhu, Z.; Li, X. F.; Yu, Q.; Huang, S.; Zhang, F.; Kong, Q.; Kawata, S.

    2014-06-01

    Proton acceleration is investigated by 2.5-dimensional particle-in-cell simulations in an interaction of an ultra intense laser with a near-critical-density plasma. It was found that multi acceleration mechanisms contribute together to a 1.67 GeV collimated proton beam generation. The W-BOA (breakout afterburner based on electrons accelerated by a wakefield) acceleration mechanism plays an important role for the proton energy enhancement in the area far from the target. The stable and continuous acceleration maintains for a long distance and period at least several pico-seconds. Furthermore, the energy scalings are also discussed about the target density and the laser intensity.

  4. Stable long range proton acceleration driven by intense laser pulse with underdense plasmas

    SciTech Connect

    Gu, Y. J.; Zhu, Z.; Li, X. F.; Yu, Q.; Huang, S.; Zhang, F.; Kong, Q.; Kawata, S.

    2014-06-15

    Proton acceleration is investigated by 2.5-dimensional particle-in-cell simulations in an interaction of an ultra intense laser with a near-critical-density plasma. It was found that multi acceleration mechanisms contribute together to a 1.67 GeV collimated proton beam generation. The W-BOA (breakout afterburner based on electrons accelerated by a wakefield) acceleration mechanism plays an important role for the proton energy enhancement in the area far from the target. The stable and continuous acceleration maintains for a long distance and period at least several pico-seconds. Furthermore, the energy scalings are also discussed about the target density and the laser intensity.

  5. The evolution of ultra-intense, short-pulse lasers in underdense plasmas

    SciTech Connect

    Decker, C.D.; Mori, W.B.; Tzeng, K.C.

    1995-11-03

    The propagation of short-pulse lasers through underdense plasmas at ultra-high intensities (I {>=}10{sup 19}W/cm) is examined. The pulse evolution is found to be significantly different than it is for moderate intensities. Rather than beam breakup from self-modulation, Raman forward scattering and laser hose instabilities the behavior is dominated by leading edge erosion. A differential equation which describes local pump depletion is derived and used to analyze the formation and evolution of the erosion. This pulse erosion is demonstrated with one dimensional particle in cell (PIC) simulations. In addition, two dimensional simulations are presented which show pulse erosion along with other effects such as channeling and diffraction.

  6. Dependence of stimulated Brillouin scattering on laser intensity, laser {ital f} number, and ion species in hohlraum plasmas

    SciTech Connect

    Fernandez, J.C.; Cobble, J.A.; Failor, B.H.; Hsing, W.W.; Rose, H.A.; Wilde, B.H.; Bradley, K.S.; Gobby, P.L.; Kirkwood, R.; Kornblum, H.N.; Montgomery, D.S.; Wilke, M.D. ||

    1996-03-01

    Stimulated Brillouin scattering has been studied in plasma conditions approaching those expected within laser-driven cavities (hohlraums) capable of driving a fusion capsule to ignition with x rays. These conditions are achieved using a gas-filled hohlraum design that was fielded at the Nova laser. As the intensity of an interaction beam (351 nm in wavelength) is increased above an onset value {ital I}{sub {ital c}}, the measured Brillouin backscatter into the lens rises sharply and saturates. {ital I}{sub {ital c}} decreases as the optic {ital f} number increases. The saturation level depends on the gas ion species. {copyright} {ital 1996 The American Physical Society.}

  7. Two-dimensional self-focusing of short intense laser pulse in underdense plasma

    SciTech Connect

    Chen, X.L.; Sudan, R.N. )

    1993-04-01

    A simplified set of three-dimensional equations are derived for the propagation of an intense laser pulse of arbitrary strength [bold a]=[ital e][bold A]/[ital mc][sup 2] (where [bold A] is the magnetic vector potential of the laser pulse) in cold underdense plasma. In different limits, the equations can be easily reduced to those of previous one-dimensional models [Phys. Fluids [bold 30], 526 (1987); Phys. Rev. A [bold 40], 3230 (1989); [bold 41], 4463 (1990)]. For [vert bar][bold a][vert bar][le]1, an approximate set of equations from the averaged Lagrangian is obtained. The present study differs from previous work in that wave dispersion is also important for short laser pulse, and is included in the model equations. The axisymmetric two-dimensional model equations are solved numerically to show the effect of dispersion in the self-focusing process.

  8. Intense isolated few-cycle attosecond XUV pulses from overdense plasmas driven by tailored laser pulses

    NASA Astrophysics Data System (ADS)

    Chen, Zi-Yu; Li, Xiao-Ya; Chen, Li-Ming; Li, Yu-Tong; Zhu, Wen-Jun

    2014-06-01

    A method to generate an intense isolated few-cycle attosecond XUV pulse is demonstrated using particle-in-cell simulations. When a tailored laser pulse with a sharp edge irradiates a foil target, a strong transverse net current can be excited, which emits a few-cycle XUV pulse from the target rear side. The isolated pulse is ultrashort in the time domain with a duration of several hundred attoseconds. It also has a narrow bandwidth in the spectral domain compared to other XUV sources of high-order harmonics. It has most energy confined around the plasma frequency and no low-harmonic orders below the plasma frequency. It is also shown that XUV pulse of peak field strength up to $ 8\\times 10^{12} $ V$\\mathrm{m}^{-1}$ can be produced. Without the need for pulse selecting and spectral filtering, such an intense few-cycle XUV pulse is better suited to a number of applications.

  9. Plume splitting and rebounding in a high-intensity CO{sub 2} laser induced air plasma

    SciTech Connect

    Chen Anmin; Jiang Yuanfei; Liu Hang; Jin Mingxing; Ding Dajun

    2012-07-15

    The dynamics of plasma plume formed by high-intensity CO{sub 2} laser induced breakdown of air at atmospheric pressure is investigated. The laser wavelength is 10.6 {mu}m. Measurements were made using 3 ns gated fast photography as well as space and time resolved optical emission spectroscopy. The behavior of the plasma plume was studied with a laser energy of 3 J and 10 J. The results show that the evolution of the plasma plume is very complicated. The splitting and rebounding of the plasma plume is observed to occur early in the plumes history.

  10. Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

    SciTech Connect

    Arora, V.; Chakera, J. A.; Naik, P. A.; Gupta, P. D.

    2015-07-31

    X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available for time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.

  11. High intensity laser interactions with underdense plasma: a source of energetic electrons, ions, neutrons and gamma-rays

    NASA Astrophysics Data System (ADS)

    Najmudin, Zulfikar

    2002-11-01

    With the rapid advances in laser technology, laser beams are now available that can be routinely focused to intensities approaching 10^20 Wcm-2. At these intensities all matter becomes ionised on a time scale close to the period of the laser. The subsequent interaction is therefore characterised by the interaction of an intense laser beam with a highly dissociated medium (plasma). The interaction is particularly interesting since at these intensities, the normalised momentum of the electrons in the laser field is given by a_0=0.89× I(10^18 Wcm-2× λ^2(μ m)). Hence the quiver velocity of the plasma electrons in the electric field of the laser beam becomes relativistic. The interaction of the laser beam with a plasma at such elevated intensities is highly non-linear, and can lead to a whole host of interesting phenomena. These include relativistic self-focusing, harmonic generation, and Raman type parametric instabilities. These processes are of interest, not only from a scientific perspective, but also a technological one, with the prospect that such an interaction can provide useful sources of energetic particles. In this context, plasma wave generation by laser beam self-modulation, proton acceleration by Coulomb explosions and thermonuclear fusion neutron generation by extreme heating of intense laser beams will be discussed. Recent highlights of this research include the detection of protons of energies in excess of 1 MeV, the heating of an underdense deuterium plasma to temperatures in excess of 1 keV, resulting in the detection in excess of 10^6 fusion neutrons; and the detection of electrons accelerated to greater than 200 MeV due to the generation of relativistically steepened plasma waves. The latter measurement is particularly noteworthy since it is obtained with a 1 J, 10 Hz laser system, (Salle Jaune, LOA).

  12. SiC detector damage and characterization for high intensity laser-plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Cannavò, A.

    2016-05-01

    Silicon-Carbide (SiC) detectors are always more extensively employed as diagnostics in laser-generated plasma due to their remarkable properties such as their high band gap, high carrier velocity, high detection efficiency, high radiation resistance and low leakage current at room temperature. SiC detectors, in comparison with Si detectors, have the advantage of being insensitive to visible light, having low reverse current at high temperature and high radiation hardness. A similar energy resolution characterizes the two types of detectors, being 0.8% in Si and 1.0% in SiC, as measured detecting 5.8 MeV alpha particles. Generally, SiC detectors are employed as laser-plasma diagnostics in time-of-flight configuration, permitting the simultaneous detection of photons, electrons and ions based on discrimination of velocity. SiC detectors can be employed in the proportionality regime, because their response is proportional to the radiation energy deposited in the active layer. Using thin absorbers in front of the detectors makes it possible to have further information on the radiation nature, intensity and energy. Surface characterization of SiC before and after prolonged exposure to hot plasma laser generated shows the formation of bulk defects and thin film deposition on the detector surface limiting the device functionality.

  13. Development of time resolved x-ray spectroscopy in high intensity laser-plasma interactions

    SciTech Connect

    Notley, M. M.; Weber, R. L.; Fell, B.; Jeffries, J.; Freeman, R. R.; Mackinnon, A. J.; Dickson, R.; Hey, D.; Khattak, F.; Saiz, E. Garcia; Gregori, G.

    2006-10-15

    This article discusses the design of a novel time resolved von Hamos Bragg spectrometer to provide spectra in the region around the titanium K-{alpha} and He-{alpha} lines. The instrument consists of a highly oriented pyrolitic graphite mosaic crystal coupled to a picosecond x-ray streak camera. Measurements of the time dependent behavior from Ti foils illuminated with intense laser pulses can be used to improve the understanding of recombination dynamics, electron transport, and phase transitions in strongly coupled dense plasma. This is important for the modeling of the compression phase in inertial confinement fusion research and the study of astrophysical environments.

  14. Nonlinear interaction of intense hypergeometric Gaussian subfamily laser beams in plasma

    NASA Astrophysics Data System (ADS)

    Sobhani, H.; Vaziri (Khamedi), M.; Rooholamininejad, H.; Bahrampour, A. R.

    2016-07-01

    Propagation of Hypergeometric-Gaussian laser beam in a nonlinear plasma medium is investigated by considering the Source Dependent Expansion method. A subfamily of Hypergeometric-Gaussian beams with a non-negative, even and integer radial index, can be expressed as the linear superposition of finite number of Laguerre-Gaussian functions. Propagation of Hypergeometric-Gaussian beams in a nonlinear plasma medium depends on the value of radial index. The bright rings' number of these beams is changed during the propagation in plasma medium. The effect of beam vortex charge number l and initial (input) beam intensity on the self-focusing of Hypergeometric-Gaussian beams is explored. Also, by choosing the suitable initial conditions, Hypergeometric-Gaussian subfamily beams can be converted to one or more mode components that a typical of mode conversion may be occurred. The self-focusing of these winding beams can be used to control the focusing force and improve the electron bunch quality in laser plasma accelerators.

  15. Study of the plasma expansion produced on ultra-thin foil targets with a high intensity and ultrashort laser pulse

    NASA Astrophysics Data System (ADS)

    Gnedyuk, Semen; Fourmaux, Sylvain; Buffechoux, Sebastien; Albertazzi, Bruno; Martin, Francois; Kieffer, Jean Claude

    2011-10-01

    INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes J3X 1S2, Québec, Canada LULI, UMR 7605, CNRS - CEA - Université Paris 6 - Ecole Polytechnique, Palaiseau, France Abstract: A high intensity ultrashort laser pulse, with an intensity of the order of 1019 W/cm2, focused onto a thin foil target generates a plasma and highly energetic ion (including proton) beams from its front and rear sides which propagate along the target normal. Another interest of laser plasma interaction with ultra-thin foil is the possibility to deposit energy in the entire laser absorption depth before any expansion thus enabling target isochoric heating. With a target thickness of 30 or 15 nm the laser pulse should interact in volume and enable to reach very high temperature while the target is still at solid density. The resulting cooling of the target will then be ultra-fast and potential X-ray emission should be ultrashort. The 100 TW class laser system at the Advanced Laser Light Source facility enables laser plasma interaction study with femtosecond laser pulses, ultra thin foil targets and high contrast laser pulse intensity ratio. We used a shadowgraph diagnostic with a femtosecond laser probe to characterize the plasma expansion.

  16. Analytical description of attosecond pulse generation on a plasma surface irradiated by high-intense laser pulses

    NASA Astrophysics Data System (ADS)

    Cherednychek, M.; Pukhov, A.

    2016-04-01

    We study theoretically the process of turning a laser pulse into a train of attosecond or even zeptosecond pulses due to high harmonic generation (HHG) upon backreflection of intense laser radiation from a plasma surface. It is shown that under appropriate conditions these attosecond pulses may have an amplitude that is several orders of magnitude larger than that of the laser pulse. We study this process in detail, especially the nanobunching of the plasma electron density. We derive the analytical expression that describes the electron density profile and obtain a good agreement with particle-in-cell simulations. We investigate the most efficient case of HHG at a moderate laser intensity (normalised vector potential α0 = 10) on the overdense plasma slab with an exponential pre-plasma profile. Subsequently we calculate the spectra of single attosecond pulses from back radiation using our expression for density shape in combination with the equation for spectrum of nanobunch radiation.

  17. Measurement of ultrafast dynamics in the interaction of intense laser pulses with gases, atomic clusters, and plasmas

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Yong

    2003-10-01

    We have investigated the time resolved dynamics of intense, ultrashort pulse laser interactions with gases, nanometer-size clusters, and plasma waveguides. To probe the ultrafast dynamics in these interactions, we developed a new femtosecond optical diagnostic, single-shot supercontinuum spectral interferometry (SSSI), which measures ultra-rapid transients induced by an intense laser pulse in the complex index of refraction. The measurement of the transient refractive index in intense laser-heated materials provides a direct view of how the laser-produced perturbation evolves in time and space. Our SSSI diagnostic is capable of ˜10 fs temporal resolution on a temporal window ˜1.5 ps long, along with ˜7 mum one-dimensional (1D) spatial resolution. SSSI was first applied to probe the ionization dynamics of helium gas under the irradiation of high intensity (˜1017 W/cm 2) laser pulses. It revealed a characteristic stepwise transition process He → He+ → He2+, in agreement with the optical field ionization model. This measurement was used as a test case to demonstrate that finite laser-target interaction lengths can strongly affect the interpretation of all measurements involving extraction of transient phases. The time-resolved explosion dynamics of intense (˜1015 W/cm2) laser-heated clusters was also studied with SSSI and additional ultrafast optical diagnostics. Here, the ultrafast processes are ionization and rapid cluster plasma explosion. The measurement strongly supports our laser-cluster interaction scenario in which laser-heated clusters explode layer-by-layer, and the laser is strongly coupled at critical density. For the cluster sizes and laser intensities of this experiment, the measured several hundred-femtosecond evolution timescale of laser-heated clusters can be understood in terms of plasma hydrodynamics. A major implication of our understanding of microscopic cluster dynamics was the prediction and observation of self-focusing in clustered

  18. Observation of relativistic cross-phase modulation in high-intensity laser-plasma interactions.

    PubMed

    Chen, S; Rever, M; Zhang, P; Theobald, W; Umstadter, D

    2006-10-01

    A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I = 1.3 x 10(18) W cm(-2), lambda = 1.05 microm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8-100 nm when the pump laser power is increased from 0.45-2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump power of 2.4 TW. The experimental cross-phase modulated spectra compared well with theoretical calculations. Applications to generation of high-power single-cycle pulses are also discussed. PMID:17155181

  19. Spectroscopic measurements of ablation plasma generated with laser-driven intense extreme ultraviolet (EUV) light

    NASA Astrophysics Data System (ADS)

    Tanaka, N.; Hane, K.; Shikata, H.; Masuda, M.; Nagatomi, K.; Sunahara, A.; Yoshida, M.; Fujioka, S.; Nishimura, H.

    2016-03-01

    Material ablation by a focused Extreme ultraviolet (EUV) light is studied by comparing expanding ion properties and plasma parameters with laser ablation. The kinetic energy distributions of expanding ions from EUV and laser ablation showed different spectra implying different geometries of plasma expansion. The calculation results of plasma parameters showed that EUV energy is mostly deposited in high electron density region close to the solid density, while laser energy is deposited in low energy density region. Plasma parameters experimentally obtained from visible spectra did not show noticeable difference between EUV and laser ablation due to the corresponding low cut off density.

  20. Upper limit power for self-guided propagation of intense lasers in plasma

    SciTech Connect

    Wang Weimin; Hu Zhidan; Chen Liming; Li Yutong; Sheng Zhengming; Zhang Jie; Zeng Ming; Liu Yue; Kawata, Shigeo; Zheng Chunyang; Mori, Warren B.

    2012-10-29

    It is shown that there is an upper-limit laser power for self-focusing of a laser pulse in plasma in addition to the well-known lower-limit critical power set by the relativistic effect. This upper limit is caused by the transverse ponderomotive force of the laser, which tends to expel plasma electrons from the laser propagating area. Furthermore, there is a lower-limit plasma density for a given laser spot size, below which self-focusing does not occur for any laser power. Both the lower-limit density and the upper-limit power are derived theoretically and verified by two-dimensional and three-dimensional particle-in-cell simulations. It is also found that plasma channels may be unfavorable for stable guiding of lasers above the upper-limit power.

  1. Instability and dynamics of two nonlinearly coupled intense laser beams in a quantum plasma

    SciTech Connect

    Wang Yunliang; Shukla, P. K.; Eliasson, B.

    2013-01-15

    We consider nonlinear interactions between two relativistically strong laser beams and a quantum plasma composed of degenerate electron fluids and immobile ions. The collective behavior of degenerate electrons is modeled by quantum hydrodynamic equations composed of the electron continuity, quantum electron momentum (QEM) equation, as well as the Poisson and Maxwell equations. The QEM equation accounts the quantum statistical electron pressure, the quantum electron recoil due to electron tunneling through the quantum Bohm potential, electron-exchange, and electron-correlation effects caused by electron spin, and relativistic ponderomotive forces (RPFs) of two circularly polarized electromagnetic (CPEM) beams. The dynamics of the latter are governed by nonlinear wave equations that include nonlinear currents arising from the relativistic electron mass increase in the CPEM wave fields, as well as from the beating of the electron quiver velocity and electron density variations reinforced by the RPFs of the two CPEM waves. Furthermore, nonlinear electron density variations associated with the driven (by the RPFs) quantum electron plasma oscillations obey a coupled nonlinear Schroedinger and Poisson equations. The nonlinearly coupled equations for our purposes are then used to obtain a general dispersion relation (GDR) for studying the parametric instabilities and the localization of CPEM wave packets in a quantum plasma. Numerical analyses of the GDR reveal that the growth rate of a fastest growing parametrically unstable mode is in agreement with the result that has been deduced from numerical simulations of the governing nonlinear equations. Explicit numerical results for two-dimensional (2D) localized CPEM wave packets at nanoscales are also presented. Possible applications of our investigation to intense laser-solid density compressed plasma experiments are highlighted.

  2. Relativistic effects in the interaction of high intensity ultra-short laser pulse with collisional underdense plasma

    SciTech Connect

    Abedi, Samira; Dorranian, Davoud; Abari, Mehdi Etehadi; Shokri, Babak

    2011-09-15

    In this paper, the effect of weakly relativistic ponderomotive force in the interaction of intense laser pulse with nonisothermal, underdense, collisional plasma is studied. Ponderomotive force modifies the electron density and temperature distribution. By considering the weakly relativistic effect and ohmic heating of plasma electrons, the nonlinear dielectric permittivity of plasma medium is obtained and the equation of electromagnetic wave propagation in plasma is solved. It is shown that with considering the ohmic heating of electrons and collisions, the effect of ponderomotive force in weakly relativistic regime leads to steepening the electron density profile and increases the temperature of plasma electrons noticeably. Bunches of electrons in plasma become narrower. By increasing the laser pulse strength, the wavelength of density oscillations decreases. In this regime of laser-plasma interaction, electron temperature increases sharply by increasing the intensity of laser pulse. The amplitude of electric and magnetic fields increases by increasing the laser pulse energy while their wavelength decreases and they lost their sinusoidal form.

  3. Polarization effect on the relativistic nonlinear dynamics of an intense laser beam propagating in a hot magnetoactive plasma.

    PubMed

    Sepehri Javan, N; Adli, F

    2013-10-01

    Nonlinear dynamics of an intense circularly polarized laser beam interacting with a hot magnetized plasma is investigated. Using a relativistic fluid model, a modified nonlinear Schrödinger equation is derived based on a quasineutral approximation, which is valid for hot plasma. Using a three-dimensional model, spatial-temporal development of the laser pulse is investigated. The occurrence of some nonlinear phenomena such as self-focusing, self-modulation, light trapping, and filamentation of the laser pulse is discussed. Also the effect of polarization and external magnetic field on the nonlinear evolution of these phenomena is studied. PMID:24229288

  4. The effect of light-induced plasma on propagation of intense fs laser radiation in c-Si

    NASA Astrophysics Data System (ADS)

    Kononenko, V. V.; Zavedeev, E. V.; Gololobov, V. M.

    2016-04-01

    The strong two-photon absorption and induced plasma are well-known factors restricting the penetration of intense focused laser pulses in silicon crystals. In this paper, we demonstrate that the role of plasma is not exhausted by the defocusing effect in a beam waist. We investigated experimentally the propagation of an IR laser pulse focused inside a silicon target and found a complex filament-like transformation of the beam. The results of numerical simulation suggest that this behavior is the result of wavefront distortion induced by the subsurface plasma ρ s.

  5. High-order harmonic generation by nonlinear reflection of an intense high-contrast laser pulse on a plasma.

    PubMed

    Monot, Pascal; Doumy, Gilles; Dobosz, Sundrine; Perdrix, Michel; D'Oliveira, Pascal; Quéré, Fabion; Réau, Fabrice; Martin, Philippe; Audebert, Patrick; Gauthier, Jean-Claude; Geindre, Jean-Paul

    2004-04-15

    We demonstrate the use of a plasma mirror to obtain 60-fs 10-TW laser pulses with a temporal contrast of 10(8) on a nanosecond time scale and 10(6) on a picosecond time scale, and we use these high-contrast pulses to generate high harmonics by nonlinear reflection on a plasma with a steep electronic density gradient. Well-collimated harmonics up to 20th order are observed for a laser intensity of approximately equal to 3 x 10(17) W/cm2, whereas no harmonics are obtained without the plasma mirror. PMID:15119413

  6. Efficient gamma-ray generation by ultra-intense laser pulses obliquely incident on a planar plasma layer

    NASA Astrophysics Data System (ADS)

    Serebryakov, D. A.; Nerush, E. N.

    2016-04-01

    We have carried out numerical simulations of oblique incidence of a laser pulse with an intensity of I = 1.33 × 1023 W cm-2 on a planar plasma layer and found the plasma density and the angle of incidence of p-polarised laser pulses that correspond to the highest gamma-ray generation efficiency and high gamma-ray directivity. The shape of the plasma surface has been determined by simulation and conditions have been considered that lead to an increase in generation efficiency.

  7. Picosecond soft-x-ray pulses from a high-intensity laser-plasma source.

    PubMed

    Pelletier, J F; Chaker, M; Kieffer, J C

    1996-07-15

    We report time-resolved spectroscopic analysis of laser-produced plasma x-ray sources. Plasmas produced by a 400-fs 1-TW tabletop laser are characterized with a transmission grating spectrometer coupled to a soft-x-ray streak camera. Soft-x-ray radiation in the 1-6-nm range with durations of 2-7 ps is observed for copper and tantalum plasmas. The effect of incident laser energy on the x-ray pulse duration is also investigated. PMID:19876245

  8. Intense THz radiation from laser plasma with controllable waveform and polarization

    NASA Astrophysics Data System (ADS)

    Bai, Ya; Liu, Peng; Song, Liwei; Li, Ruxin; Xu, Zhizhan

    2015-03-01

    We demonstrate the generation of waveform-controlled THz radiation from air plasma that is produced when carrier envelope phase (CEP) stabilized few-cycle laser pulses undergoes filamentation in ambient air. Elliptically polarized THz waves are generated from air plasma induced by circularly polarized few-cycle laser pulses. Our results reveal that electric field asymmetry in rotating directions of the circularly polarized few-cycle laser pulses produces the enhanced broadband transient currents, and the phase difference of perpendicular laser field components is partially inherited in the generation process of THz emission.

  9. Note: Characterization of the plasma parameters of a capillary discharge-produced plasma channel waveguide to guide an intense laser pulse

    SciTech Connect

    Higashiguchi, Takeshi; Yugami, Noboru; Hikida, Masafumi; Terauchi, Hiromitsu; Bai Jinxiang; Kikuchi, Takashi; Tao Yezheng

    2010-04-15

    We demonstrated the production of an optical waveguide in a capillary discharge-produced plasma using a cylindrical capillary. Plasma parameters of its waveguide were characterized by use of both a Nomarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 10{sup 17} cm{sup -3} was observed at a discharge time of 150 ns and a maximum discharge current of 400 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.

  10. Laser prepulse induced plasma channel formation in air and relativistic self focusing of an intense short pulse

    SciTech Connect

    Kumar, Ashok; Dahiya, Deepak; Sharma, A. K.

    2011-02-15

    An analytical formalism is developed and particle-in-cell simulations are carried out to study plasma channel formation in air by a two pulse technique and subsequent relativistic self focusing of the third intense laser through it. The first prepulse causes tunnel ionization of air. The second pulse heats the plasma electrons and establishes a prolonged channel. The third pulse focuses under the combined effect of density nonuniformity of the channel and relativistic mass nonlinearity. A channel with 20% density variation over the spot size of the third pulse is seen to strongly influence relativistic self focusing at normalized laser amplitude {approx}0.4-1. In deeper plasma channels, self focusing is less sensitive to laser amplitude variation. These results are reproduced in particle-in-cell simulations. The present treatment is valid for millimeter range plasma channels.

  11. Intensity anomalies in the extreme VUV spectrum of Al/+3/ obtained in a laser-produced plasma

    NASA Technical Reports Server (NTRS)

    Valero, F. P. J.

    1974-01-01

    The results of experiments performed to check the possibility of stimulated emission in the extreme vacuum ultraviolet (VUV) by an Al(+3) laser-generated plasma are reported. It is concluded that the spectral line intensity anomalies previously observed are not due to population inversion.

  12. Temporally and spatially resolved measurements of multi-megagauss magnetic fields in high intensity laser-produced plasmas

    SciTech Connect

    Gopal, A.; Tatarakis, M.; Beg, F. N.; Wei, M. S.; Clark, E. L.; Dangor, A. E.; Evans, R. G.; Norreys, P. A.; Zepf, M.; Krushelnick, K.

    2008-12-15

    We report spatially and temporally resolved measurements of self-generated multi-megagauss magnetic fields produced during ultrahigh intensity laser plasma interactions. Spatially resolved measurements of the magnetic fields show an asymmetry in the distribution of field with respect to the angle of laser incidence. Temporally resolved measurements of the self-generated third harmonic suggest that the strength of the magnetic field is proportional to the square root of laser intensity (i.e., the laser B-field) during the rise of the laser pulse. The experimental results are compared with numerical simulations using a particle-in-cell code which also shows clear asymmetry of the field profile and similar magnetic field growth rates and scalings.

  13. Measurement of ultrafast dynamics in the interaction of intense laser pulses with gases, clusters, and plasma waveguides

    NASA Astrophysics Data System (ADS)

    Kim, K. Y.

    2004-11-01

    We have investigated the femtosecond time resolved dynamics of intense, ultrashort laser interactions with various targets-gases, nanometer-size clusters, and plasma waveguides. To probe the ultrafast dynamics in these interactions, we developed a new ultrafast optical diagnostic, single-shot supercontinuum spectral interferometry (SSSI) [1], which measures ultra-rapid transients induced by an intense laser pulse in the complex index of refraction of the evolving medium. This measurement provides a direct view on how the laser-produced perturbations evolve in time and space. To date, we have measured, using the SSSI diagnostic, (i) the laser-induced double step ionization of helium [2], (ii) time-resolved explosion dynamics of intense-laser-heated clusters [3], and (iii) the coupling and guiding of intense laser pulses injected into a plasma waveguide. [1] K. Y. Kim, I. Alexeev, and H. M. Milchberg, Appl. Phys. Lett. 81, 4124 (2002). [2] K. Y. Kim, I. Alexeev, and H. M. Milchberg, Opt. Express 10, 1563 (2002). [3] K. Y. Kim et al., Phys. Rev. Lett. 90, 023401 (2003); I. Alexeev et al., ibid. 90, 103402 (2003).

  14. Novel high-energy physics studies using intense lasers and plasmas

    SciTech Connect

    Leemans, Wim P.; Bulanov, Stepan; Esarey, Eric; Schroeder, Carl

    2015-06-29

    In the framework of the project “Novel high-energy physics studies using intense lasers and plasmas” we conducted the study of ion acceleration and “flying mirrors” with high intensity lasers in order to develop sources of ion beams and high frequency radiation for different applications. Since some schemes of laser ion acceleration are also considered a good source of “flying mirrors”, we proposed to investigate the mechanisms of “mirror” formation. As a result we were able to study the laser ion acceleration from thin foils and near critical density targets. We identified several fundamental factors limiting the acceleration in the RPA regime and proposed the target design to compensate these limitations. In the case of near critical density targets, we developed a concept for the laser driven ion source for the hadron therapy. Also we studied the mechanism of “flying mirror” generation during the intense laser interaction with thin solid density targets. As for the laser-based positron creation and capture we initially proposed to study different regimes of positron beam generation and positron beam cooling. Since the for some of these schemes a good quality electron beam is required, we studied the generation of ultra-low emittance electron beams. In order to understand the fundamental physics of high energy electron beam interaction with high intensity laser pulses, which may affect the efficient generation of positron beams, we studied the radiation reaction effects.

  15. Modification of semiconductor materials with the use of plasma produced by low intensity repetitive laser pulses

    SciTech Connect

    Wolowski, J.; Rosinski, M.; Badziak, J.; Czarnecka, A.; Parys, P.; Turan, R.; Yerci, S.

    2008-03-19

    This work reports experiments concerning specific application of laser-produced plasma at IPPLM in Warsaw. A repetitive pulse laser system of parameters: energy up to 0.8 J in a 3.5 ns-pulse, wavelength of 1.06 {mu}m, repetition rate of up to 10 Hz, has been employed in these investigations. The characterisation of laser-produced plasma was performed with the use of 'time-of-flight' ion diagnostics simultaneously with other diagnostic methods. The results of laser-matter interaction were obtained in dependence on laser pulse parameters, illumination geometry and target material. The modified SiO{sub 2} layers and sample surface properties were characterised with the use of different methods at the Middle-East Technological University in Ankara and at the Warsaw University of technology. The production of the Ge nanocrystallites has been demonstrated for annealed samples prepared in different experimental conditions.

  16. Increasing the upper-limit intensity and temperature range for thermal self-focusing of a laser beam by using plasma density ramp-up

    NASA Astrophysics Data System (ADS)

    Bokaei, B.; Niknam, A. R.

    2014-03-01

    This work is devoted to improving relativistic and ponderomotive thermal self-focusing of the intense laser beam in an underdense plasma. It is shown that the ponderomotive nonlinearity induces a saturation mechanism for thermal self-focusing. Therefore, in addition to the well-known lower-limit critical intensity, there is an upper-limit intensity for thermal self-focusing above which the laser beam starts to experience ponderomotive defocusing. It is indicated that the upper-limit intensity value is dependent on plasma and laser parameters such as the plasma electron temperature, plasma density, and laser spot size. Furthermore, the effect of the upward plasma density ramp profile on the thermal self-focusing is studied. Results show that by using the plasma density ramp-up, the upper-limit intensity increases and the self-focusing temperature range expands.

  17. Increasing the upper-limit intensity and temperature range for thermal self-focusing of a laser beam by using plasma density ramp-up

    SciTech Connect

    Bokaei, B.; Niknam, A. R.

    2014-03-15

    This work is devoted to improving relativistic and ponderomotive thermal self-focusing of the intense laser beam in an underdense plasma. It is shown that the ponderomotive nonlinearity induces a saturation mechanism for thermal self-focusing. Therefore, in addition to the well-known lower-limit critical intensity, there is an upper-limit intensity for thermal self-focusing above which the laser beam starts to experience ponderomotive defocusing. It is indicated that the upper-limit intensity value is dependent on plasma and laser parameters such as the plasma electron temperature, plasma density, and laser spot size. Furthermore, the effect of the upward plasma density ramp profile on the thermal self-focusing is studied. Results show that by using the plasma density ramp-up, the upper-limit intensity increases and the self-focusing temperature range expands.

  18. Stopping and Coulomb explosion of energetic carbon clusters in a plasma irradiated by an intense laser field

    NASA Astrophysics Data System (ADS)

    Wang, Guiqiu; Wang, Younian

    2015-09-01

    The interaction of a charged particle beam with a plasma is a very important subject of relevance for many fields of physics, such as inertial confinement fusion (ICF) driven by ion or electron beams, high energy density physics, and related astrophysical problems. Recently, a promising ICF scheme has been proposed, in which the plasma target is irradiated simultaneously by intense laser and ion beams. For molecular ion or cluster, slowing down process will company the Coulomb explosion phenomenon. In this paper, we present a study of the effects of intense radiation field (RF) on the interaction of energetic carbon clusters in a plasma. The emphasis is laid on the dynamic polarization and correlation effects of the constituent ions within the cluster in order to disclose the role of the vicinage effects on the Coulomb explosion and energy deposition of the clusters in plasma. On the other hand, affecting of a strong laser field on the cluster propagating in plasma is considered, the influence of a large range of laser parameters and plasma parameters on the Coulomb explosion and stopping power are discussed. This work is supported by the National Natural Science Foundation of China (11375034), and the Fundamental Research Funds for the Central Universities of China (3132015144, 3132014337).

  19. Characteristic x-ray emission from undermines plasmas irradiated by ultra-intense lasers

    SciTech Connect

    Niemann, Christoph

    2012-05-05

    Between FY09 and FY11 we have conducted more than a dozen three-week experimental campaigns at high-power laser facilities around the world to investigate laser-channeling through x-ray and optical imaging and the conversion from laser-energy to xrays. We have performed simultaneous two-wavelength x-ray imaging (K-alpha and He-alpha) to distinguish the hot-plasma region (hot-spot) from the laser-produced electrons (K-alpha). In addition, we have initiated a new collaboration with SNL and have performed first shots on the 100 TW beamlet chamber to commission a fast x-ray streak camera to be used to investigate the temporal evolution of our K-alpha sources. We also collaborated on campaigns at the Rutherford Appleton Laboratory (UK) and the LANL Trident laser to employ laser produced x-ray sources for Thomson scattering off dense matter.

  20. Continuous plasma laser. [method and apparatus for producing intense, coherent, monochromatic light from low temperature plasma

    NASA Technical Reports Server (NTRS)

    Libby, W. F.; Jensen, C. A.; Wood, L. L. (Inventor)

    1977-01-01

    The apparatus includes a housing for confining a gas at subatmospheric pressure and including a set of reflectors defining an optical cavity. At least one anode and cathode are positioned within the gas. First control means control the voltage applied to the anode and second control means independently control the temperature of the cathode. The pressure of the gas is controlled by a third control means. An intense monochromatic output is achieved by confining the gas in the housing at a controlled pre-determined reduced pressure, independently controlling the temperature of the electron emitting cathode and applying predetermined controlled low voltage to the anode.

  1. Coulomb-Boltzmann-Shifted distribution in laser-generated plasmas from 1010 up to 1019 W/cm2 intensities

    NASA Astrophysics Data System (ADS)

    Torrisi, L.

    2016-02-01

    The charge production from laser-generated plasmas generates not isotropically ion acceleration in vacuum and with mean kinetic energy proportional to the ion charge state. The ion velocity depends on many factors of which the most important are the plasma temperature, the adiabatic gas expansion in vacuum and the Coulomb acceleration. The ion energy distributions of the emitted ions from the plasma can be well explained by the Coulomb-Boltzmann-Shifted function, with a cut-off limitation at high energy for a wide range of laser intensities. It can be applied for intensities of 1010 W/cm2, when plasma is produced only in the backward direction from thick targets (backward plasma acceleration regime), as well as at intensities of the order of 1019 W/cm2, when plasma is produced in the forward direction from thin targets in target-normal sheath acceleration regime. It loses of validity in radiation pressure acceleration regime, at which ions are emitted near mono-energetically.

  2. Generating intense fully coherent soft x-ray radiation based on a laser-plasma accelerator.

    PubMed

    Feng, Chao; Xiang, Dao; Deng, Haixiao; Huang, Dazhang; Wang, Dong; Zhao, Zhentang

    2015-06-01

    Laser-plasma based accelerator has the potential to dramatically reduce the size and cost of future x-ray light sources to the university-laboratory scale. However, the large energy spread of the laser-plasma accelerated electron beam may hinder the way for short wavelength free-electron laser generation. In this paper, we propose a novel method for directly imprinting strong coherent micro-bunching on the electron beam with large intrinsic energy spread by using a wavefront-tilted conventional optical laser beam and a weak dipole magnet. Theoretical analysis and numerical simulations demonstrate that this technique can be used for the generation of fully coherent femtosecond soft x-ray radiation at gigawatts level with a very short undulator. PMID:26072855

  3. Deflection, spraying, and induced scattering of intense laser beams in plasmas

    SciTech Connect

    Kruer, W.L.

    1996-09-01

    Investigations into laser beam spraying, deflection, and induced scattering in plasmas are presented. Recent calculations and experiments on beam spraying due to filamentation are discussed. A simple model is presented for an enhanced beam deflection associated with nearly sonic plasma flow transverse to the beam. This model provides useful insights on the laser beam deflection, its scaling and the importance of self-consistent profile modifications. Finally, some discussion is given of recent experiments demonstrating the interplay between stimulated.Raman and Brillouin scattering.

  4. Self-compression of intense short laser pulses in relativistic magnetized plasma

    SciTech Connect

    Olumi, M.; Maraghechi, B.

    2014-11-15

    The compression of a relativistic Gaussian laser pulse in a magnetized plasma is investigated. By considering relativistic nonlinearity and using non-linear Schrödinger equation with paraxial approximation, a second-order differential equation is obtained for the pulse width parameter (in time) to demonstrate the longitudinal pulse compression. The compression of laser pulse in a magnetized plasma can be observed by the numerical solution of the equation for the pulse width parameter. The effects of magnetic field and chirping are investigated. It is shown that in the presence of magnetic field and negative initial chirp, compression of pulse is significantly enhanced.

  5. Measurements of plasma-wave generation using a short-pulse high-intensity laser beat wave

    SciTech Connect

    Walton, B.; Najmudin, Z.; Wei, M.S.; Marle, C.; Kingham, R.J.; Krushelnick, K.; Dangor, A.E.; Clarke, R.J.; Poulter, M. J.; Hernandez-Gomez, C.; Hawkes, S.; Neely, D.; Collier, J.L.; Danson, C.N.; Fritzler, S.; Malka, V.

    2006-01-15

    Experiments to examine the generation of relativistic plasma waves via a high-intensity short-pulse beat-wave scheme are described in detail. The pulse stretcher of the Vulcan chirped-pulse amplification (CPA) laser system was modified to produce two frequency, 3 ps pulses focusable to intensities up to 10{sup 18} W cm{sup -2}. Short high-intensity pulses were used to avoid limitations to the plasma-wave amplitude due to the modulational instability. Two experiments were undertaken, at 3 and 10 TW, with the generation of plasma waves diagnosed by measuring the sidebands produced in the spectrum of the forward scattered beam. A resonance in the sideband signal was observed for an initial plasma density higher than expected for the given beat frequency. This resonance shift can be attributed to transverse ponderomotive expulsion of plasma electrons from the laser focal region. A monotonically increasing background was also observed, which was due to nonresonant cross-phase modulation.

  6. Probing ultrafast dynamics in a solid-density plasma created by an intense femtosecond laser

    NASA Astrophysics Data System (ADS)

    Adak, Amitava; Blackman, Dave; Chatterjee, Gourab; Singh, Prashant Kumar; Lad, Amit D.; Brijesh, P.; Robinson, A. P. L.; Pasley, John; Kumar, G. Ravindra

    2016-03-01

    We report a study on the dynamics of a near-solid density plasma using an ultraviolet (266 nm) femtosecond probe laser pulse, which can penetrate to densities of ∼ 1022 cm-3, nearly an order of magnitude higher than the critical density of the 800 nm, femtosecond pump laser. Time-resolved probe-reflectivity from the plasma shows a rapid decay (picosecond- timescale) while the time-resolved reflected probe spectra show red shifts at early temporal delays and blue shifts at longer delays. This spectral behaviour of the reflected probe can be explained by a laser-driven shock moving inward and a subsequent hydrodynamic free expansion in the outward direction.

  7. Electron acceleration by laser wakefield and x-ray emission at moderate intensity and density in long plasmas

    SciTech Connect

    Ferrari, H. E.; Lifschitz, A. F.; Maynard, G.; Cros, B.

    2011-08-15

    The dynamics of electron acceleration by laser wakefield and the associated x-rays emission in long plasmas are numerically investigated for parameters close to the threshold of laser self-focusing. The plasma length is set by the use of dielectric capillary tubes that confine the gas and the laser energy. Electrons self-injection and acceleration to the 170 MeVs are obtained for densities as low as 5 x 10{sup 18} cm{sup -3} and a moderate input intensity (0.77 x 10{sup 18} W/cm{sup 2}). The associated x-ray emission at the exit of the capillary tube is shown to be an accurate diagnostic of the electrons self-injection and acceleration process.

  8. Impact of Pre-Plasma on Fast Electron Generation and Transport from Short Pulse High Intensity Lasers

    NASA Astrophysics Data System (ADS)

    Peebles, J.; McGuffey, C.; Krauland, C.; Jarrott, L. C.; Sorokovikova, A.; Qiao, B.; Krasheninnikov, S.; Beg, F. N.; Wei, M. S.; Park, J.; Link, A.; Chen, H.; McLean, H. S.; Wagner, C.; Minello, V.; McCary, E.; Meadows, A.; Spinks, M.; Gaul, E.; Dyer, G.; Hegelich, B. M.; Martinez, M.; Donovan, M.; Ditmire, T.

    2014-10-01

    We present the results and analysis from recent short pulse laser matter experiments using the Texas Petawatt Laser to study the impact of pre-plasma on fast electron generation and transport. The experimental setup consisted of 3 separate beam elements: a main, high intensity, short pulse beam for the interaction, a secondary pulse of equal intensity interacting with a separate thin foil target to generate protons for side-on proton imaging and a third, low intensity, wider beam to generate a varied scale length pre-plasma. The main target consisted of a multilayer planar Al foil with a buried Cu fluor layer. The electron beam was characterized with multiple diagnostics, including several bremsstrahlung spectrometers, magnetic electron spectrometers and Cu-K α imaging. The protons from the secondary target were used to image the fields on the front of the target in the region of laser plasma interaction. Features seen in the interaction region by these protons will be presented along with characteristics of the generated electron beam. This work performed under the auspices of the US DOE under Contracts DE-FOA-0000583 (FES, NNSA).

  9. Subpicosecond KrF{asterisk}-laser plasma interaction at intensities between 10{sup 14} and 10{sup 17} W/cm{sup 2}

    SciTech Connect

    Teubner, U.; Gibbon, P.; Foerster, E.; Fallies, F.; Audebert, P.; Geindre, J.P.; Gauthier, J.C.

    1996-07-01

    The interaction of high-intensity subpicosecond KrF{asterisk}-laser pulses with aluminium plasmas is investigated at intensities between 10{sup 14} and 10{sup 17} W/cm{sup 2}. Using a one-dimensional hydrocode, the laser energy absorption and time evolution of plasma parameters have been studied as a function of laser intensity, incidence angle, and polarization. Complementary particle-in-cell simulations have also been performed to check the collisionless absorption component carried by hot electrons and ions. These simulations are compared to previous experiments on laser pulse absorption and x-ray generation. {copyright} {ital 1996 American Institute of Physics.}

  10. Ion heating and thermonuclear neutron production from high-intensity subpicosecond laser pulses interacting with underdense plasmas.

    PubMed

    Fritzler, S; Najmudin, Z; Malka, V; Krushelnick, K; Marle, C; Walton, B; Wei, M S; Clarke, R J; Dangor, A E

    2002-10-14

    Thermonuclear fusion neutrons produced by D(d,n)3He reactions have been measured from the interaction of a high-intensity laser with underdense deuterium plasmas. For an input laser energy of 62 J, more than (1.0+/-0.2)x10(6) neutrons with a mean kinetic energy of (2.5+/-0.2) MeV were detected. These neutrons were observed to have an isotropic angular emission profile. By comparing these measurements with those using a secondary solid CD2 target it was determined that neutrons are produced from direct ion heating during this interaction. PMID:12398731

  11. Interaction of intense lasers and relativistic electron beams with solids, gases and plasmas. Progress report, January-30 June 1993

    SciTech Connect

    Ott, E.; Liu, C.S.; Grantstein, V.L.

    1993-06-01

    The focus of the Maryland Program is to establish strong experimental and theoretical support for ongoing programs at NRL. Areas of research which are of mutual interest are pursued by members of the University of Maryland faculty in collaboration with their counterparts at NRL. The proposal encompasses basically three broad areas of research activities. The first area deals with excimer laser technology and the interaction of high power lasers with matter (gases, solids and plasma). The second area of mutual interest involves diagnostics of intense relativistic electron beams and study of their propagation and interaction with a background gas. The nonlinear temporal dynamics in neural networks is the third area for collaboration.

  12. Ultra intense laser/plasma interaction at normal incidence: Relativistic mirrors effects, high harmonics generation and absorption

    NASA Astrophysics Data System (ADS)

    Sanz, Javier; Debayle, Arnaud; Mima, K.

    2012-11-01

    An analytical study of the relativistic interaction of a linearly-polarized laser-field of ω frequency with highly overdense plasma is presented. Very intense high harmonics are generated produced by relativistic mirrors effects due to the relativistic electron plasma oscillation. Also, in agreement with 1D Particle-In-Cell Simulations (PICS), the model self-consistently explains the transition between the sheath inverse bremsstrahlung (SIB) absorption regime and the J×B heating (responsible for the 2ω electron bunches), as well as the mean electron energy.

  13. Final report 'IONPACK: Ionization Package for Intense Lasers and Plasma Physics Codes'

    SciTech Connect

    Dimitre A Dimitorv; David L Bruhwiler

    2004-01-06

    OAK-B135 There is a need for accurate models of ionization processes in simulations on advanced concepts for next-generation high-energy accelerators. In this Phase I project, we studied the feasibility to develop of a generic, extendable, and interoperable software library for simulation of tunneling, impact, multiphoton, and barrier suppression ionization processes that can easily be used with existing Particle-In-Cell (PIC), hydrodynamic, and other plasma simulation codes. We developed a functional prototype of the package in and identified the complete library design to be implemented in the Phase II and tested on currently relevant research problems in laser and beam-plasma wakefield accelerators.

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

    SciTech Connect

    Lecz, Zs.; Andreev, A.

    2015-04-15

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

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

    SciTech Connect

    Ma, Tammy Yee Wing

    2010-01-01

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

  16. Quantitative Kα line spectroscopy for energy transport in ultra-intense laser plasma interaction

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Nishimura, H.; Fujioka, S.; Arikawa, Y.; Nakai, M.; Chen, H.; Park, J.; Williams, G. J.; Ozaki, T.; Shiraga, H.; Kojima, S.; Johzaki, T.; Sunahara, A.; Miyanaga, N.; Kawanaka, J.; Nakata, Y.; Jitsuno, T.; Azechi, H.

    2016-03-01

    Absolute Ka line spectroscopy is proposed for studying laser-plasma interactions taking place in the cone-guided fast ignition targets. X-ray spectra ranging from 20 to 100 keV were quantitatively measured with a Laue spectrometer. The absolute sensitivities of the Laue spectrometer system were calibrated using pre-characterized laser-produced x-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for x-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency, is derived as a consequence of this work. The absolute yield of Au and Ta Ka lines were measured in the fast ignition experimental campaign performed at Institute of Laser Engineering, Osaka University. Applying the hot electron spectrum information from the electron spectrometer, an energy transfer efficiency of the incident LFEX [1], a kJ-class PW laser, to hot electrons was derived for a planar and cone-guided geometry.

  17. Weakly relativistic and ponderomotive effects on the density steepening in the interaction of an intense laser pulse with an underdense plasma

    SciTech Connect

    Niknam, A. R.; Hashemzadeh, M.; Shokri, B.

    2009-03-15

    The effect of the weakly relativistic ponderomotive force in the interaction of an intense laser pulse with an underdense plasma is studied. This force modifies the electron density distribution. Furthermore, the existence of intense laser pulses in plasma causes the electron relativistic mass to appear and, consequently, the plasma frequency decreases. It is clear that the electron temperature also affects the dielectric permittivity of plasma. By considering the weakly relativistic and ponderomotive effects, the nonlinear dielectric permittivity of plasma is obtained. Taking into account the Maxwell equations and the nonlinear dielectric permittivity, the electric and magnetic field profiles in plasma are investigated. It is shown that the electromagnetic field profiles deviate from sinusoidal structure. Also, the steepening of the electron density profile decreases by increasing the electron temperature and decreasing the laser pulse intensity. The wavelength of oscillations decreases by increasing the energy flux. Finally, it is found that the electric and magnetic field profiles are lengthened by increasing the electron temperature.

  18. PIC Simulations of Ultra Intense Laser Pulses Propagating Through Overdense Plasma for Fast-Ignitor and Radiography Applications

    NASA Astrophysics Data System (ADS)

    Lasinski, Barbara F.

    1998-11-01

    Particle-in-Cell codes are uniquely suited to model the interaction of ultra intense laser beams with overdense plasmas. We describe our Zohar simulations whose parameters are guided by present high intensity experiments to explore both fast-ignitorfootnote M. Tabak, J. Hammer, M. E. Glinsky, W. L. Kruer, S. C. Wilks, J. Woodworth, E. M. Campbell, M. D Perry, and R. J. Mason, Phys. Plasmas 1, 1626 (1994). and radiographyfootnote S. P. Hatchett, S. Wilks, B. F. Lasinski, and M. Perry, presented at the 28^th Anomalous Absorption Conference, June 14-18, 1998. applications. The ρ r of the simulated plasma slabs and the time scale of the ZOHAR modeling are roughly comparable to present short pulse experiments with thin CH foils and high laser intensity. Complex low frequency magnetic field structures, narrow channel formation, beam deflection, and harmonic generation are all evident in these simulations. Absorption fractions are high and we verify the predicted scaling for T_hot.footnote S. C. Wilks, W. L. Kruer, M. Tabak, and A. B. Langdon, Phys. Rev. Lett. 69, 1383 (1992). Our recent work has emphasized our particle tracking diagnostics which allow us to explore the nature of the currents that produce and interact with these static magnetic fields which are larger than 10^9 G for simulations at 10^21 W/cm^2 in a 50nc plasma. Particle orbits at various stages of channel formation provide a more complete understanding of the hot electron generation as the short pulse, high intensity laser penetrates overdense plasma. We identify particles which constitute the current in the narrow channel. The forward going electrons are partially confined in the channel by the low frequency magnetic field. In contrast, the return current particles on the outside of the channel are defocused by the high magnetic field and move away from the channel. Electrons continuously move in toward the channel and replenish the return current. Results on the spectra and angular distribution of the

  19. The effects of transverse plasma flow on laser beam deflection and of ultra-intense laser beam filamentation on channel formation

    NASA Astrophysics Data System (ADS)

    Hinkel, D. E.

    1997-11-01

    Recent experiments conducted at Lawrence Livermore National Laboratory (LLNL) with the Nova and Janus lasers demonstrate deflection of the laser beam in plasma with flow transverse to the beam. In gas-filled hohlraum experiments(S. G. Glendinning et al.), the laser spot on the hohlraum wall is ~ 100 μm closer to the laser entrance hole (LEH) than in empty hohlraum experiments, which degrades drive symmetry. In a series of exploding foil experiments(J. D. Moody et al.), Phys. Rev. Lett. 77, 1294 (1996)., intensity dependent deflection of the transmitted beam is observed, and interferometric measurements of laser-produced channels in preformed plasma(P. E. Young et al.), to be submitted to Phys. Rev. Lett., 1997. show beam deflection in the presence of near-sonic transverse flow. Theoretical analysis(D. E. Hinkel et al.), Phys. Rev. Lett. 77, 1298 (1996). yields simple scaling laws for the formation of ponderomotively (or thermally) created density depressions downstream from the laser beam's high intensity regions, into which the light is refracted. An integrated approach that utilizes plasma parameters from the hydrocode Lasnex, detailed knowledge of the beam structure, and plasma physics analysis and modelling with F3D(R. L. Berger et al.), Phys. Fluids B 5, 2243 (1993)., has been used to develop a predictive capability that successfully quantifies the amount of beam deflection occurring in experiments. Related physics of beam self-focussing and filamentation is of relevance to the Fast Ignitor(M. Tabak et al.), Phys. Plasmas 1, 1626 (1994).. In channeling experiments performed on the 100 TW laser at LLNL, the f/3 laser beam, which has a 15 μm waist at best focus, has intensities in excess of IL = 1 × 10^17 W/cm^2. Modelling of these high intensity experiments indicates that channel formation occurs over a wide range of cone angles for an idealized (Gaussian) beam. However, when beam structure is taken into consideration, channel formation in the underdense

  20. Formation of plasma channels in the interaction of a nanosecond laser pulse at moderate intensities with helium gas jets.

    PubMed

    De Wispelaere, E; Malka, V; Hüller, S; Amiranoff, F; Baton, S; Bonadio, R; Casanova, M; Dorchies, F; Haroutunian, R; Modena, A

    1999-06-01

    We report on a detailed study of channel formation in the interaction of a nanosecond laser pulse with a He gas jet. A complete set of diagnostics is used in order to characterize the plasma precisely. The evolution of the plasma radius and of the electron density and temperature are measured by Thomson scattering, Schlieren imaging, and Mach-Zehnder interferometry. In gas jets, one observes the formation of a channel with a deep density depletion on axis. Because of ionization-induced defocusing which increases the size of the focal spot and decreases the maximum laser intensity, no channel is observed in the case of a gas-filled chamber. The results obtained in various gas-jet and laser conditions show that the channel radius, as well as the density along the propagation axis, can be adjusted by changing the laser energy and gas-jet pressure. This is a crucial issue when one wants to adapt the channel parameters in order to guide a subsequent high-intensity laser pulse. The experimental results and their comparison with one-dimensional (1D) and two-dimensional hydrodynamic simulations show that the main mechanism for channel formation is the hydrodynamic evolution behind a supersonic electron heat wave propagating radially in the plasma. It is also shown from 2D simulations that a fraction of the long pulse can be self-guided in the channel it creates. The preliminary results and analyses on this subject have been published before [V. Malka et al., Phys. Rev. Lett. 79, 2979 (1997)]. PMID:11969699

  1. Fast-electron refluxing effects on anisotropic hard-x-ray emission from intense laser-plasma interactions.

    PubMed

    McKeever, K; Makita, M; Nersisyan, G; Dzelzainis, T; White, S; Kettle, B; Dromey, B; Zepf, M; Sarri, G; Doria, D; Ahmed, H; Lewis, C L S; Riley, D; Robinson, A P L

    2015-03-01

    Fast-electron generation and dynamics, including electron refluxing, is at the core of understanding high-intensity laser-plasma interactions. This field is itself of strong relevance to fast ignition fusion and the development of new short-pulse, intense, x-ray, γ-ray, and particle sources. In this paper, we describe experiments that explicitly link fast-electron refluxing and anisotropy in hard-x-ray emission. We find the anisotropy in x-ray emission to be strongly correlated to the suppression of refluxing. In contrast to some previous work, the peak of emission is directly along the rear normal to the target rather than along either the incident laser direction or the specular reflection direction. PMID:25871224

  2. Impact of pre-plasma on fast electron generation and transport from short pulse, high intensity lasers

    NASA Astrophysics Data System (ADS)

    Peebles, J.; McGuffey, C.; Krauland, C. M.; Jarrott, L. C.; Sorokovikova, A.; Wei, M. S.; Park, J.; Chen, H.; McLean, H. S.; Wagner, C.; Spinks, M.; Gaul, E. W.; Dyer, G.; Hegelich, B. M.; Martinez, M.; Donovan, M.; Ditmire, T.; Krasheninnikov, S. I.; Beg, F. N.

    2016-01-01

    Previous experiments and modeling examining the impact of an underdense, pre-formed plasma in laser-plasma interactions have shown that the fast electrons are generated with energies higher than predicted by ponderomotive scaling [4, 3-14]. We report on experiments using the Texas Petawatt high intensity (150 fs, 1.5  ×  1020 W cm-2) laser pulse, which were conducted to examine the mechanism for accelerating these high energy electrons. These experiments gauge the impact a controlled low density pre-formed plasma has on electron generation with a shorter time scale than previous experiments, 150-180 fs. Electron temperatures measured via magnetic spectrometer on experiment were found to be independent of preformed plasma. Supplemental computational results using 1D PIC simulations predict that super-ponderomotive electrons are generated inside a potential well in the pre-plasma [1]. However, while the potential well is established around 150 fs, the electrons require at least an additional 50 fs to be trapped and heated inside it.

  3. Detailed Experimental Study of Ion Acceleration by Interaction of an Ultra-Short Intense Laser with an Underdense Plasma.

    PubMed

    Kahaly, S; Sylla, F; Lifschitz, A; Flacco, A; Veltcheva, M; Malka, V

    2016-01-01

    Ion acceleration from intense (Iλ(2) > 10(18) Wcm(-2) μm(2)) laser-plasma interaction is experimentally studied within a wide range of He gas densities. Focusing an ultrashort pulse (duration  ion plasma period) on a newly designed submillimetric gas jet system, enabled us to inhibit total evacuation of electrons from the central propagation channel reducing the radial ion acceleration associated with ponderomotive Coulomb explosion, a mechanism predominant in the long pulse scenario. New ion acceleration mechanism have been unveiled in this regime leading to non-Maxwellian quasi monoenergetic features in the ion energy spectra. The emitted nonthermal ion bunches show a new scaling of the ion peak energy with plasma density. The scaling identified in this new regime differs from previously reported studies. PMID:27531755

  4. Ion Acceleration by Ultra-intense Laser Pulse Interacting with Double-layer Near-critical Density Plasma

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Kong, Q.; Kawata, S.; Izumiyama, T.; Nagashima, T.; Takano, M.; Li, X. F.; Yu, Q.; Barada, D.; Ma, Y. Y.; Wang, P. X.

    2016-03-01

    A collimated ion beam is generated through the interaction between ultra-intense laser pulse and a double layer plasma. The maximum energy is above 1GeV and the total charge of high energy protons is about several tens of nC/μm. The double layer plasma is combined with an underdense plasma and a thin overdense one. The wakefield traps and accelerates a bunch of electrons to high energy in the first underdense slab. When the well collimated electron beam accelerated by the wakefield penetrates through the second overdense slab, it enhances target normal sheath acceleration (TNSA) and breakout after-burner (BOA) regimes. The mechanism is simulated and analyzed by 2.5 dimensional Particle-in-cell code. Compared with single target TNSA or BOA, both the acceleration gradient and energy transfer efficiency are higher in the double layer regime.

  5. Detailed Experimental Study of Ion Acceleration by Interaction of an Ultra-Short Intense Laser with an Underdense Plasma

    PubMed Central

    Kahaly, S.; Sylla, F.; Lifschitz, A.; Flacco, A.; Veltcheva, M.; Malka, V.

    2016-01-01

    Ion acceleration from intense (Iλ2 > 1018 Wcm−2 μm2) laser-plasma interaction is experimentally studied within a wide range of He gas densities. Focusing an ultrashort pulse (duration  ion plasma period) on a newly designed submillimetric gas jet system, enabled us to inhibit total evacuation of electrons from the central propagation channel reducing the radial ion acceleration associated with ponderomotive Coulomb explosion, a mechanism predominant in the long pulse scenario. New ion acceleration mechanism have been unveiled in this regime leading to non-Maxwellian quasi monoenergetic features in the ion energy spectra. The emitted nonthermal ion bunches show a new scaling of the ion peak energy with plasma density. The scaling identified in this new regime differs from previously reported studies. PMID:27531755

  6. The effect of external magnetic field on the density distributions and electromagnetic fields in the interaction of high-intensity short laser pulse with collisionless underdense plasma

    NASA Astrophysics Data System (ADS)

    Mahmoodi-Darian, Masoomeh; Ettehadi-Abari, Mehdi; Sedaghat, Mahsa

    2016-03-01

    Laser absorption in the interaction between ultra-intense femtosecond laser and solid density plasma is studied theoretically here in the intensity range I{λ^2} ˜eq 10^{14}{-}10^{16}{{W}}{{{cm}}^{-2}} \\upmu{{{m}}2} . The collisionless effect is found to be significant when the incident laser intensity is less than 10^{16}{{W}}{{{cm}}^{-2}}\\upmu{{{m}}2} . In the current work, the propagation of a high-frequency electromagnetic wave, for underdense collisionless plasma in the presence of an external magnetic field is investigated. When a constant magnetic field parallel to the laser pulse propagation direction is applied, the electrons rotate along the magnetic field lines and generate the electromagnetic part in the wake with a nonzero group velocity. Here, by considering the ponderomotive force in attendance of the external magnetic field and assuming the isothermal collisionless plasma, the nonlinear permittivity of the plasma medium is obtained and the equation of electromagnetic wave propagation in plasma is solved. Here, by considering the effect of the ponderomotive force in isothermal collisionless magnetized plasma, it is shown that by increasing the laser pulse intensity, the electrons density profile leads to steepening and the electron bunches of plasma become narrower. Moreover, it is found that the wavelength of electric and magnetic field oscillations increases by increasing the external magnetic field and the density distribution of electrons also grows in comparison to the unmagnetized collisionless plasma.

  7. Effect of reentrant cone geometry on energy transport in intense laser-plasma interactions

    SciTech Connect

    Lancaster, K. L.; Sherlock, M.; Heathcote, R.; Green, J. S.; Norreys, P. A.; Gregory, C. D.; Hakel, P.; Akli, K. U.; Hey, D. S.; Stephens, R. B.; Beg, F. N.; Chen, S. N.; Wei, M. S.; Yabuuchi, T.; Freeman, R. R.; Highbarger, K.; Van Woerkom, L.; Weber, R. L.; Habara, H.; Key, M. H.

    2009-10-15

    The energy transport in cone-guided low-Z targets has been studied for laser intensities on target of 2.5x10{sup 20} W cm{sup -2}. Extreme ultraviolet (XUV) imaging and transverse optical shadowgraphy of the rear surfaces of slab and cone-slab targets show that the cone geometry strongly influences the observed transport patterns. The XUV intensity showed an average spot size of 65{+-}10 {mu}m for slab targets. The cone slabs showed a reduced spot size of 44{+-}10 {mu}m. The shadowgraphy for the aforementioned shots demonstrate the same behavior. The transverse size of the expansion pattern was 357{+-}32 {mu}m for the slabs and reduced to 210{+-}30 {mu}m. A transport model was constructed which showed that the change in transport pattern is due to suppression of refluxing electrons in the material surrounding the cone.

  8. Experimental study of relativistic self-focusing and self-channeling of an intense laser pulse in an underdense plasma

    SciTech Connect

    Gibbon, P.; Jakober, F.; Monot, P.; Auguste, T.

    1996-04-01

    This paper reports on experimental investigations on relativistic self-focusing and self-channeling of a terawatt laser pulse (0.7 TW {le} P {le} 15 TW) in an underdense plasma. The authors present results obtained with picosecond ({tau} = 1 ps) and subpicosecond ({tau} = 0.4 ps) pulses. In the ``long pulse`` regime, modifications in the laser propagation are observed for P < P{sub c}, the critical power for self-focusing. By contrast, self-guiding of subpicosecond pulses is observed for P {approx} P{sub c}. Using a paraxial envelope model describing the laser propagation and taking into account the plasma response to the ponderomotive force, it is shown that a maximum laser intensity of 5--15 times that reached in vacuum may be achieved when P is in the (1.25--4) {times} P{sub c} range. It is also demonstrated that ion motion may significantly reduce the effective P{sub c}.

  9. Numerical modeling of radiation physics in kinetic plasmas [IV] - Isochoric heating by intense X-ray laser-produced photoelectrons

    NASA Astrophysics Data System (ADS)

    Royle, Ryan; Sentoku, Yasuhiko

    2014-10-01

    An intense, hard X-ray laser such as an XFEL is an attractive light source since it can directly heat solid matter isochorically to a temperature of millions of degrees on a time scale of a few tens of femtoseconds, which is much shorter than the plasma expansion time scale. The X-ray laser interaction with carbon, aluminum, silicon, and copper is studied with a particle-in-cell code that solves the photoionization and X-ray transport self-consistently. Photoionization is the dominant absorption mechanism and non-thermal photoelectrons are produced with energy near the X-ray photon energy. The photoelectrons' stopping range is a few microns and they are quickly thermalized in tens of femtoseconds. As a result, a hot plasma column is formed behind the laser pulse with a temperature of more than 100,000 kelvin (>10 eV) and energy density greater than 1011 J/m3. The heating depth and temperature depend on the material and are also controllable by changing the photon energy of the incident laser light.

  10. Amplification of ultra-short light pulses by ion collective modes in plasmas. The use of damage-less optics for high laser intensities

    NASA Astrophysics Data System (ADS)

    Frank, A.; Fuchs, J.; Lancia, L.; Lehmann, G.; Marquès, J.-R.; Mourou, G.; Riconda, C.; Spatschek, K. H.; Toncian, T.; Vassura, L.; Weber, S.

    2014-05-01

    The use of plasmas provides a way to overcome the damage threshold of classical solid-state based optical materials which is the main limitation encountered in producing extreme power laser pulses. In particular one can use plasmas to directly amplify ultra-short laser pulses to very high intensities. Multi-dimensional kinetic simulations and first proof-of-principle experiments show the feasibility of using plasma instabilities involving ion waves, such as stimulated Brillouin backscattering, in a controlled way to transfer energy from a long pump pulse to a short seed pulse and thereby increase the intensity of the latter. Plasma parametric amplification, and the use of plasma mirrors for focusing, is part of the newly developping domain of plasma optics, which eventually will pave the way to Exawatt lasers.

  11. Specific features of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense 500-ps-long laser pulse

    SciTech Connect

    Borisenko, N. G.; Merkul’ev, Yu. A.; Orekhov, A. S.; Chaurasia, S.; Tripathi, S.; Munda, D. S.; Dhareshwar, L. J.; Pimenov, V. G.; Sheveleva, E. E.

    2013-08-15

    The properties of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense (10{sup 14} W/cm{sup 3}) short (0.5 ps) 1.064-μm laser pulse were studied. It is found that, even at plasma densities exceeding the critical density, a small fraction of the incident laser radiation penetrates through the plasma in which the processes of density and temperature equalization still take place. The intensification (as compared to plasmas produced from denser foams and solid films) of transport processes in such plasma along and across the laser beam can be caused by the initial microheterogeneity of the solid target. The replacement of a small (10% by mass) part of the polymer with copper nanoparticles leads to a nearly twofold increase in the intensity of the plasma X-ray emission.

  12. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: High-resolution x-ray spectroscopy of a plasma produced by an intense picosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Bryunetkin, B. A.; Skobelev, I. Yu; Faenov, A. Ya; Kalashnikov, M. P.; Nickles, P. V.; Schnürer, M.; Pikuz, S. A.

    1993-04-01

    It has been shown experimentally that a source based on a plasma produced by a picosecond laser is extremely promising for systematic research on the satellite structures of multiply charged ions which have electrons in L or M shells. The combination of the unique characteristics of this source and the particular measurement apparatus used (with a spectral resolution Δλ/λ~10-4) has made it possible to refine the wavelengths of several transitions of Mg IX and X ions which had been identified previously, to identify for the first time ten spectral lines due to 1s2p4l → 1s24l and 1s2p3l → 1s23l transitions of the Mg X ion, and to measure the wavelengths of 47 spectral lines which have tentatively been attributed to the Be-like ion Mg IX.

  13. Effect of electron heating on self-induced transparency in relativistic-intensity laser-plasma interactions.

    PubMed

    Siminos, E; Grech, M; Skupin, S; Schlegel, T; Tikhonchuk, V T

    2012-11-01

    The effective increase of the critical density associated with the interaction of relativistically intense laser pulses with overcritical plasmas, known as self-induced transparency, is revisited for the case of circular polarization. A comparison of particle-in-cell simulations to the predictions of a relativistic cold-fluid model for the transparency threshold demonstrates that kinetic effects, such as electron heating, can lead to a substantial increase of the effective critical density compared to cold-fluid theory. These results are interpreted by a study of separatrices in the single-electron phase space corresponding to dynamics in the stationary fields predicted by the cold-fluid model. It is shown that perturbations due to electron heating exceeding a certain finite threshold can force electrons to escape into the vacuum, leading to laser pulse propagation. The modification of the transparency threshold is linked to the temporal pulse profile, through its effect on electron heating. PMID:23214893

  14. Responses of organic and inorganic materials to intense EUV radiation from laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Makimura, Tetsuya; Torii, Shuichi; Nakamura, Daisuke; Takahashi, Akihiko; Okada, Tatsuo; Niino, Hiroyuki; Murakami, Kouichi

    2013-05-01

    We have investigated responses of polymers to EUV radiation from laser-produced plasmas beyond ablation thresholds and micromachining. We concentrated on fabricate precise 3D micro-structures of PDMS, PMMA, acrylic block copolymers (BCP), and silica. The micromachining technique can be applied to three-dimensional micro-fluidic and bio-medical devices. The EUV processing is a promising to realize a practical micromachining technique. In the present work, we used two EUV radiation sources; (a) Wide band EUV light in a range of 10{300 eV was generated by irradiation of Ta targets with Nd:YAG laser light at 500 mJ/pulse. (b) Narrow band EUV light at 11 and 13 nm was generated by irradiation of solid Xe and Sn targets, respectively, with pulsed TEA CO2 laser light. The generated EUV light was condensed onto the materials at high power density beyond the ablation thresholds, using ellipsoidal mirrors. We found that through-holes with a diameter of one micrometer an be fabricated in PMMA and PDMS sheets with thicknesses of 4-10 micrometers, at 250 and 230 nm/shot, respectively. The effective ablation of PMMA sheets can be applied to a LIGA-like process for fabricating micro-structures of metals for micro- and nano-molds. PDMS sheets are ablated if it is irradiated with EUV light beyond a distinct threshold power density, while PDMS surfaces were modified at lower power densities. Furthermore, BCP sheets were ablated to have 1-micrometer structures. Thus, we have developed a practical technique for micromachining of PMMA, PDMS and BCP sheets in a micrometer scale.

  15. On the origin of super-hot electrons from intense laser interactions with solid targets having moderate scale length preformed plasmas

    SciTech Connect

    Krygier, A. G.; Schumacher, D. W.; Freeman, R. R.

    2014-02-15

    We use particle-in-cell modeling to identify the acceleration mechanism responsible for the observed generation of super-hot electrons in ultra-intense laser-plasma interactions with solid targets with pre-formed plasma. We identify several features of direct laser acceleration that drive the generation of super-hot electrons. We find that, in this regime, electrons that become super-hot are primarily injected by a looping mechanism that we call loop-injected direct acceleration.

  16. The effect of external magnetic field on the bremsstrahlung nonlinear absorption mechanism in the interaction of high intensity short laser pulse with collisional underdense plasma

    SciTech Connect

    Sedaghat, M.; Ettehadi-Abari, M.; Shokri, B. Ghorbanalilu, M.

    2015-03-15

    Laser absorption in the interaction between ultra-intense femtosecond laser and solid density plasma is studied theoretically here in the intensity range Iλ{sup 2}≃10{sup 14}−10{sup 16}Wcm{sup −2}μm{sup 2}. The collisional effect is found to be significant when the incident laser intensity is less than 10{sup 16}Wcm{sup −2}μm{sup 2}. In the current work, the propagation of a high frequency electromagnetic wave, for underdense collisional plasma in the presence of an external magnetic field is investigated. It is shown that, by considering the effect of the ponderomotive force in collisional magnetized plasmas, the increase of laser pulse intensity leads to steepening of the electron density profile and the electron bunches of plasma makes narrower. Moreover, it is found that the wavelength of electric and magnetic fields oscillations increases by increasing the external magnetic field and the density distribution of electrons also grows in comparison with the unmagnetized collisional plasma. Furthermore, the spatial damping rate of laser energy and the nonlinear bremsstrahlung absorption coefficient are obtained in the collisional regime of magnetized plasma. The other remarkable result is that by increasing the external magnetic field in this case, the absorption coefficient increases strongly.

  17. Gamma-ray emission in near critical density plasmas at laser intensities of 10{sup 21 }W/cm{sup 2}

    SciTech Connect

    Wang, H. Y.; Liu, B.; Yan, X. Q.; Zepf, M.

    2015-03-15

    We study synchrotron radiation emission from laser interaction with near critical density (NCD) plasmas at intensities of 10{sup 21 }W∕cm{sup 2} using three-dimensional particle-in-cell simulations. It is found that the electron dynamics depend on the laser shaping process in NCD plasmas, and thus the angular distribution of the emitted photons changes as the laser pulse evolves in space and time. The final properties of the resulting synchrotron radiation, such as its overall energy, the critical photon energy, and the radiation angular distribution, are strongly affected by the laser polarization and plasma density. By using a 420 TW∕50 fs laser pulse at the optimal plasma density (∼1n{sub c}), about 10{sup 8} photons/0.1% bandwidth are produced at multi-MeV photon energies, providing a route to ultraintense, femtosecond gamma ray pulses.

  18. Physics of the interaction of ultra intense laser pulses with cold collisional plasma using large scale kinetic simulations

    SciTech Connect

    Héron, A.; Adam, J. C.

    2015-07-15

    We present a set of 2D collisional particle-in-cell simulations of the interaction of ultra-intense laser pulses with over-dense cold collisional plasmas. The size of these simulations is about 100 times as large as those previously published. This allows studying the transport of energetic particles on time scale of the order of 400 fs without perturbations due to the influence of boundary effects and performing a very detailed analysis of the physics of the transport. We confirm the existence of a threshold in intensity close to the relativistic threshold above which the beam of energetic particles diverges when it penetrates the cold plasma. We also study the applicability of Ohm's law to compute the electric field, which is the method commonly used in hybrid codes. The heating of the cold plasma is then studied and we show that half of the heating is anomalous, i.e., not given by standard Joule effect. We discuss the previously published results in the light of these new simulations.

  19. Physics of the interaction of ultra intense laser pulses with cold collisional plasma using large scale kinetic simulations

    NASA Astrophysics Data System (ADS)

    Héron, A.; Adam, J. C.

    2015-07-01

    We present a set of 2D collisional particle-in-cell simulations of the interaction of ultra-intense laser pulses with over-dense cold collisional plasmas. The size of these simulations is about 100 times as large as those previously published. This allows studying the transport of energetic particles on time scale of the order of 400 fs without perturbations due to the influence of boundary effects and performing a very detailed analysis of the physics of the transport. We confirm the existence of a threshold in intensity close to the relativistic threshold above which the beam of energetic particles diverges when it penetrates the cold plasma. We also study the applicability of Ohm's law to compute the electric field, which is the method commonly used in hybrid codes. The heating of the cold plasma is then studied and we show that half of the heating is anomalous, i.e., not given by standard Joule effect. We discuss the previously published results in the light of these new simulations.

  20. Relative phase interactions of two copropagating laser beams in underdense plasmas at different intensities and spot sizes

    SciTech Connect

    Mahdy, A. I.

    2010-06-15

    The mutual interactions of two copropagating laser beams at a relative phase are studied using a two-dimensional fluid code. The interactions are investigated in underdense plasma at selected beam configurations and beam parameters for two separate nonlinearities, i.e., the ponderomotive and the relativistic nonlinearity. The selected beam configurations are introduced by different initial transverse spot size perturbations (finite and infinite) and different initial transversal intensity distributions (nonuniform and uniform) over those spot sizes and the selected beam parameters are given by different initial beam intensities relevant to each nonlinearity. In the ponderomotive nonlinearity, simulation results show that no mutual interactions are demonstrated between the copropagating beams regardless of the initial beam configurations and parameters. In nonlinear relativistic simulations, the mutual interactions between the beams are clearly observed, a mutual repulsion is formed in the presence of initial intensities that are nonuniformly distributed over finite spot sizes, and an effective strongly modulated mutual attraction takes places in the presence of initial intensities that are uniformly distributed over infinite spot sizes. Moreover, it is found in these simulations that increasing the initial beam intensities improves the attraction properties between the copropagationg beams.

  1. Helium and hydrogen plasma waveguides for high-intensity laser channeling

    NASA Astrophysics Data System (ADS)

    Zgadzaj, Rafal Bogumil

    The results of cross polarized pump-probe experiments in preformed He plasma waveguides are reported. Pump and probe have same wavelength and duration of 800nm and 80fs respectively. Peak pump intensity is Iguided = 0.2x1018 W/cm2 ˜1000 Iprobe. Single shot probe spectra and mode profiles at the channel exit are discriminated from the pump with a polarization analyzer and captured at various relative time delays Deltat. Frequency-domain interference (FDI) between the probe and a weak depolarized component of the pump is observed for |Deltat| ≳ 100fs. Although the depolarized component is nearly undetectable through measurement of pump leakage alone, FDI sensitively reveals its substantially non-Gaussian structure. The possible depolarization mechanisms are analyzed. When probe is positioned at the leading edge of the pump, Deltat ≲ 0, its spectrum suffers a blue shift not measurable in the transmitted pump itself. The evidence suggests the channel interior is fully ionized and the partially formed channel ends are the origin of both depolarization and blue shift. A robust, pulsed, differentially-pumped plasma channel generation cell for high intensity guiding experiments has been developed. The design includes an axicon lens, windows for transverse interferometry, and permits injection of one or two different gases (main gas plus high Z seed gas) with several millisecond injection times and simultaneous 0.1ms pressure sensing resolution. Very well formed plasma waveguides have been formed in helium as well as hydrogen, at repeatable and well controlled pressures up to 1000Torr, with very uniform interior density, rapid density drop at boundaries, and very low exterior density. The possible danger associated with the use of large amounts of hydrogen was considered and a complex safety system was designed, constructed and used. Extensive analysis of channel profile reconstruction through transverse interferometry was performed. This includes an intuitive

  2. X-ray optics for laser-plasma sources: Aplications of intense SXR and EUV radiation pulses

    SciTech Connect

    Bartnik, Andrzej; Fiedorowicz, Henryk; Jarocki, Roman; Kostecki, Jerzy; Szczurek, Anna; Szczurek, Miroslaw; Wachulak, Przemyslaw; Pina, Ladislav

    2012-05-17

    In this work we present a short review of SXR and EUV optics that have been designed and developed for experiments concerning material processing and imaging, using a laser-plasma radiation source based on a gas puff target. Three different kinds of mirrors employed as the EUV collectors are presented: the grazing incidence axisymmetrical ellipsoidal mirror, the grazing incidence multifoil mirror, and the ellipsoidal mirror with Mo/Si multilayer coating. Experiments concerning characterization of the mirrors were performed using EUV radiation from Kr or Xe plasmas produced in a double stream gas puff target irradiated with Nd:YAG laser pulses (4ns, 0.8 J, 10 Hz). Intensity of the focused radiation was sufficient for micromachining of organic polymers and surface modification of organic and inorganic solids. Different kinds of micro-and nanostructures created in near-surface layers of different kinds polymers were obtained. Significant differences were revealed in XPS spectra acquired for irradiated and not irradiated polymers.

  3. Polarized Heα Radiation by Anisotropic Fast Electron Transport in Ultra-Intense Laser Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Kawamura, T.; Kai, T.; Koike, F.; Nakazaki, S.; Nishimura, H.; Inubushi, Y.; Okano, Y.; Nagatomo, H.; Batani, D.; Morace, A.; Redaelli, R.; Fourment, C.; Santos, J.; Malka, G.; Boscheron, A.; Casner, A.; Koenig, M.; Fujioka, S.; Nakamura, T.; Johzaki, T.; Mima, K.

    2009-09-01

    In fast ignition research, the transport dynamics of fast electrons is one of the critical issues. Fast electrons generated by an intense laser pulse show a highly anisotropic velocity distribution. To gain insight into the anisotropy of the velocity distribution of fast electrons, polarized x-ray spectroscopy has been proposed. The polarization spectroscopy of Cl Heα radiation was experimentally demonstrated at 1017 W/cm2 (˜100 mJ in 130 fs), and a new time-dependent atomic population kinetics code was also developed. It predicts that the high polarization arises only in a low-density region of the target plasma. Additional x-ray polarization measurements were done at 101717-18 W/cm2 (˜10 J in ˜1 ps). Polarization was measured as a function of the overcoat thickness of a target. The polarization is negative in the shallow region near the target surface, and becomes near zero at the laser intensity of ˜1018 W/cm2. At ˜1017 W/cm2, the polarization varies from negative to positive, and finally zero along with an increase in the overcoat thickness.

  4. Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma

    SciTech Connect

    Adak, Amitava; Chatterjee, Gourab; Kumar Singh, Prashant; Lad, Amit D.; Brijesh, P.; Kumar, G. Ravindra; Blackman, David R.; Robinson, A. P. L.; Pasley, John

    2014-06-15

    We report on the picosecond dynamics of a near-solid-density plasma generated by an intense, infrared (λ = 800 nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic (λ = 266 nm) probe pulse, which gets blue-shifted at longer probe-delays. A combination of particle-in-cell and radiation-hydrodynamics modelling is performed to model the pump laser interaction with the solid target. The results are post-processed to predict the Doppler shift. An excellent agreement is found between the results of such modelling and the experiment. The modelling suggests that the initial inward motion of the critical surface observed in the experiment is due to the passage of a shock-wave-like disturbance, launched by the pump interaction, propagating into the target. Furthermore, in order to achieve the best possible fit to the experimental data, it was necessary to incorporate the effects of bulk ion-acceleration resulting from the electrostatic field set up by the expulsion of electrons from the laser envelope. We also present results of time-resolved pump-probe reflectometry, which are corroborated with the spectrometry results using a 1-D reflectivity model.

  5. Proton Radiography of Field Distributions in Ultra-Intense-Laser Plasma Interactions with Pulse of MeV Proton Beams

    NASA Astrophysics Data System (ADS)

    Nakamura, Hirotaka; Kodama, Ryosuke; Tampo, Motonobu; Borghesi, Marco; Romagnani, Lorenzo; Fuchs, Julien; Amin, Munib; Pipahl, Ariane; Willi, Oswald; Michibata, Takuya; Mima, Kunioki; Azechi, Hiroshi

    2008-11-01

    Proton radiography has been used to observe transient electric and magnetic fields in laser plasma interactions. We report an experimental investigation of a transient electric field generated around a laser-irradiated-plasma-fiber attached on a tip of a cone-geometry target. The electric field guided and collimated energetic electrons generated by the laser-plasma interactions in the fiber. The front of these fields propagated along the fiber with the energetic electrons at almost the light velocity. Simulation with the Geant4 Monte Carlo code shows the electric field above a few TV/m were excited around the fiber.

  6. Self-focusing of a high-intensity laser in a collisional plasma under weak relativistic-ponderomotive nonlinearity

    SciTech Connect

    Gupta, D. N.; Islam, M. R.; Jaroszynski, D. A.; Jang, D. G.; Suk, H.

    2013-12-15

    Self-focusing a laser beam in collisional plasma is investigated under the weak relativistic-ponderomotive nonlinearity. In this case, the plasma equilibrium density is modified and it causes generation of the nonlinearity due to the Ohmic heating of electrons, collisions, and the weak relativistic-ponderomotive force during the interaction of the laser beam with the plasma. Our theoretical and simulation results show that a significant nonlinearity in laser self-focusing can occur under the weak relativistic-ponderomotive regime for some appropriate simulation parameters.

  7. Using time-integrated K{sub {alpha}} images to study refluxing and the extent of pre-plasmas in intense laser-plasma experiment

    SciTech Connect

    Ovchinnikov, V. M.; Schumacher, D. W.; Kemp, G. E.; Krygier, A. G.; Van Woerkom, L. D.; Akli, K. U.; Freeman, R. R.; Stephens, R. B.; Link, A.

    2011-11-15

    We report the results of an experimental and numerical modeling study of the formation of time-integrated K{sub {alpha}} images by electrons excited during an intense laser-plasma interaction. We report the use of the spatial structure of time-integrated K{sub {alpha}} images to quantitatively characterize the pre-plasma profile near the critical surface and to verify the near elimination of back-surface refluxing from targets when a thick layer of a low-Z material is attached to the back. The time integrated K{sub {alpha}} images are found to be sensitive to the relative separation between the critical surface and the bulk target, permitting a single parameter exponential pre-plasma scale length to be determined by fitting to experimental results. The refluxed electrons affect different parts of the K{sub {alpha}} images in a manner that varies depending on the location of the refluxing. We use these properties to characterize refluxing also by fitting to experimental results. Experiments were performed using the Titan laser at the Lawrence Livermore National Laboratory and the simulations used a customized version of the hybrid-PIC code, LSP. We find good quantitative match between experiment and simulation.

  8. Laser Plasma Material Interactions

    NASA Astrophysics Data System (ADS)

    Schaaf, Peter; Carpene, Ettore

    2004-12-01

    Surface treatment by means of pulsed laser beams in reactive atmospheres is an attractive technique to enhance the surface features, such as corrosion and wear resistance or the hardness. Many carbides and nitrides play an important role for technological applications, requiring the mentioned property improvements. Here we present a new promising fast, flexible and clean technique for a direct laser synthesis of carbide and nitride surface films by short pulsed laser irradiation in reactive atmospheres (e.g. methane, nitrogen). The corresponding material is treated by short intense laser pulses involving plasma formation just above the irradiated surface. Gas-Plasma-Surface reactions lead to a fast incorporation of the gas species into the material and subsequently the desired coating formation if the treatment parameters are chosen properly. A number of laser types have been used for that (Excimer Laser, Nd:YAG, Ti:sapphire, Free Electron Laser) and a number of different nitride and carbide films have been successfully produced. The mechanisms and some examples will be presented for Fe treated in nitrogen and Si irradiated in methane.

  9. Laser Guiding at Relativistic Intensities and Wakefield ParticleAcceleration in Plasma Channels

    SciTech Connect

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

    2005-05-01

    High quality electron beams with hundreds of picoCoulombs ofcharge inpercent energy spread above 80 MeV were produced for the firsttime in high gradient laser wakefield accelerators by guiding the drivelaser pulse.

  10. A study of fast electron energy transport in relativistically intense laser-plasma interactions with large density scalelengths

    SciTech Connect

    Scott, R. H. H.; Norreys, P. A.; Perez, F.; Baton, S. D.; Davies, J. R.; Lancaster, K. L.; Trines, R. M. G. M.; Bell, A. R.; Tzoufras, M.; Rose, S. J.

    2012-05-15

    A systematic experimental and computational investigation of the effects of three well characterized density scalelengths on fast electron energy transport in ultra-intense laser-solid interactions has been performed. Experimental evidence is presented which shows that, when the density scalelength is sufficiently large, the fast electron beam entering the solid-density plasma is best described by two distinct populations: those accelerated within the coronal plasma (the fast electron pre-beam) and those accelerated near or at the critical density surface (the fast electron main-beam). The former has considerably lower divergence and higher temperature than that of the main-beam with a half-angle of {approx}20 Degree-Sign . It contains up to 30% of the total fast electron energy absorbed into the target. The number, kinetic energy, and total energy of the fast electrons in the pre-beam are increased by an increase in density scalelength. With larger density scalelengths, the fast electrons heat a smaller cross sectional area of the target, causing the thinnest targets to reach significantly higher rear surface temperatures. Modelling indicates that the enhanced fast electron pre-beam associated with the large density scalelength interaction generates a magnetic field within the target of sufficient magnitude to partially collimate the subsequent, more divergent, fast electron main-beam.

  11. Imaging of Plasmas using Proton Beams Generated by Ultra-Intense Laser Pulses

    SciTech Connect

    Borghesi, M,; Campbell, D.H.; Clarke, R.J.; Galimberti, M.; Gizzi, L.A.; Haines, M.G.; Mackinnon, A.J.; Schiavi, A.; Willi, O.

    2002-01-15

    Proton imaging is a diagnostic with enormous potential for the investigation of fundamental plasma physics problems which were impossible to explore up to now. By using this diagnostic, for the first time the measurement of transient electric fields in dense plasmas has been obtained, determining their evolution on a picosecond scale with micrometric spatial resolution. The data is of great relevance to Inertial Confinement Fusion both in the conventional and Fast Ignitor approach. Detailed analysis and modeling is presently undergoing.

  12. Plasma physics applications to intense radiation sources, pulsed power and space physics. Short pulse ultra intense laser-plasma interaction experiment. Final report, 1 January 1990-31 May 1993

    SciTech Connect

    Sudan, R.N.

    1993-05-31

    Intense bright x-ray sources from dense z-pinch and x-pinch plasmas are being investigated for photo-pumping x-ray laser media. Crossed Aluminum wire X-pinches with mass line density up to hundreds of micrograms per centimeter have been imploded by up to 600 kA current for 40 ns using a 0.5 TW pulsed power generator. High density bright spots are observed. Soft x-ray spectroscopy was used to infer plasma density of up to approx. 10 to the 20th power per cubic cm and temperature of 100 -300 eV. The optimum mass loading for different ionization stages of Aluminum ions was examined. Parallel wire z-pinches yielded both lower density up to approx. 10(19)cm-3, and lower temperatures (70 - 200 eV), than the X-pinch plasmas.

  13. Optimizing electron-positron pair production on kilojoule-class high-intensity lasers for the purpose of pair-plasma creation

    NASA Astrophysics Data System (ADS)

    Myatt, J.; Delettrez, J. A.; Maximov, A. V.; Meyerhofer, D. D.; Short, R. W.; Stoeckl, C.; Storm, M.

    2009-06-01

    Expressions for the yield of electron-positron pairs, their energy spectra, and production rates have been obtained in the interaction of multi-kJ pulses of high-intensity laser light interacting with solid targets. The Bethe-Heitler conversion of hard x-ray bremsstrahlung [D. A. Gryaznykh, Y. Z. Kandiev, and V. A. Lykov, JETP Lett. 67, 257 (1998); K. Nakashima and H. Takabe, Phys. Plasmas 9, 1505 (2002)] is shown to dominate over direct production (trident process) [E. P. Liang, S. C. Wilks, and M. Tabak, Phys. Rev. Lett. 81, 4887 (1998)]. The yields and production rates have been optimized as a function of incident laser intensity by the choice of target material and dimensions, indicating that up to 5×1011 pairs can be produced on the OMEGA EP laser system [L. J. Waxer , Opt. Photonics News 16, 30 (2005)]. The corresponding production rates are high enough to make possible the creation of a pair plasma.

  14. Production of dense vapor targets for laser-plasma interaction studies with intense, ultra-short pulses

    SciTech Connect

    Bolton, P.R.; Eder, D.C.; Guethlein, G.; Stewart, R.E.; Young, P.E.

    1993-03-19

    The technique of laser-induced ablation of thin films from glass slide substrates has been investigated as a candidate vapor target production method for studies of both tunneling-driven x-ray/xuv recombination lasers and relativistic propagation using intense, ultra-short laser pulses. It is shown by simultaneous two-wavelength interferometry that particle densities of order 10{sup 19}/cm{sup 3} are readily achieved and that some intrinsic ionization accompanies the plume formation. Absorption measurements with both 100 picosecond and 125 femtosecond pulses are consistent with observed edge velocities near 10{sup 6} cm/sec. The level of ionization driven by the intense 125 femtosecond laser pulse has been coarsely estimated. Averaged estimates from spectral blue shifting of spectra transmitted through the plume are consistently lower than those obtained from evaluation of saturation intensity thresholds based on the sequential nonresonant optical field ionization (OFI) process.

  15. Electron transport in the tip of cone targets in high intensity laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Le Galloudec, Nathalie; D'Humieres, Emmanuel; Cho, Byoung-Ick; Osterholz, Jens; Sentoku, Yasuhiko; Ditmire, Todd

    2008-04-01

    Cones targets of specific parameters were irradiated with the Thor laser (0.5J, 40fs, 800nm, 7micron focal spot, 3.10^19W/cm^2) at UT Austin. These targets have been diagnosed with a focus on hot electron transport especially in the tip. The results show a 5micron diameter beam exiting the outside tip after about 60 micron propagation in the bulk material of the tip itself. Key elements of the interaction will be presented along with supporting simulations.

  16. Electron transport in cone targets in high intensity laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Le Galloudec, Nathalie; D'Humieres, Emmanuel; Cho, Byoung-Ick; Osterholz, Jens; Sentoku, Yasuhiko; Ditmire, Todd

    2008-11-01

    Copper cones targets of different roughnesses were irradiated with the Thor laser (0.5J, 40fs, 800nm, 7 micron focal spot, 3.10^19W/cm^2) at UT Austin. Hot electron transport in the tip has been diagnosed with Coherent Transition of Radiation (CTR). Progress at the NTF has been made and a new diagnostic is being designed to provide a CTR at both φ and 2 φ. Results supported by simulations will present the current knowledge and trace a path to future progress.

  17. Simulations of the interaction of intense petawatt laser pulses with dense Z-pinch plasmas : final report LDRD 39670.

    SciTech Connect

    Welch, Dale Robert; MacFarlane, Joseph John; Mehlhorn, Thomas Alan; Campbell, Robert B.

    2004-11-01

    We have studied the feasibility of using the 3D fully electromagnetic implicit hybrid particle code LSP (Large Scale Plasma) to study laser plasma interactions with dense, compressed plasmas like those created with Z, and which might be created with the planned ZR. We have determined that with the proper additional physics and numerical algorithms developed during the LDRD period, LSP was transformed into a unique platform for studying such interactions. Its uniqueness stems from its ability to consider realistic compressed densities and low initial target temperatures (if required), an ability that conventional PIC codes do not possess. Through several test cases, validations, and applications to next generation machines described in this report, we have established the suitability of the code to look at fast ignition issues for ZR, as well as other high-density laser plasma interaction problems relevant to the HEDP program at Sandia (e.g. backlighting).

  18. A novel femtosecond-gated, high-resolution, frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experiments

    SciTech Connect

    Feister, S. Orban, C.; Nees, J. A.; Morrison, J. T.; Frische, K. D.; Chowdhury, E. A.; Roquemore, W. M.

    2014-11-15

    Ultra-intense laser-matter interaction experiments (>10{sup 18} W/cm{sup 2}) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the main ultra-intense pulse. These system-dependent pre-pulses in the nanosecond and/or picosecond regimes are often intense enough to modify the target significantly by ionizing and forming a plasma layer in front of the target before the arrival of the main pulse. Time resolved interferometry offers a robust way to characterize the expanding plasma during this period. We have developed a novel pump-probe interferometry system for an ultra-intense laser experiment that uses two short-pulse amplifiers synchronized by one ultra-fast seed oscillator to achieve 40-fs time resolution over hundreds of nanoseconds, using a variable delay line and other techniques. The first of these amplifiers acts as the pump and delivers maximal energy to the interaction region. The second amplifier is frequency shifted and then frequency doubled to generate the femtosecond probe pulse. After passing through the laser-target interaction region, the probe pulse is split and recombined in a laterally sheared Michelson interferometer. Importantly, the frequency shift in the probe allows strong plasma self-emission at the second harmonic of the pump to be filtered out, allowing plasma expansion near the critical surface and elsewhere to be clearly visible in the interferograms. To aid in the reconstruction of phase dependent imagery from fringe shifts, three separate 120° phase-shifted (temporally sheared) interferograms are acquired for each probe delay. Three-phase reconstructions of the electron densities are then inferred by Abel inversion. This interferometric system delivers precise measurements of pre-plasma expansion that can identify the condition of the target at the moment that the ultra-intense pulse arrives. Such measurements are indispensable for correlating laser pre-pulse measurements

  19. Effect of Cumulative Nanosecond Laser Pulses on the Plasma Emission Intensity and Surface Morphology of Pt- and Ag-Ion Deposited Silicon

    NASA Astrophysics Data System (ADS)

    Khurram, Siraj; Muhammad Zakria, Butt; Muhammad, Khaleeq-Urrahman; Muhammad Shahid, Rafique; Saima, Rafique; Fakhar-Un-Nisa

    2012-04-01

    In this work, the laser induced plasma plume characteristics and surface morphology of Pt- and Ag-ion deposited silicon were studied. The deposited silicon was exposed to cumulative laser pulses. The plasma plume images produced by each laser shot were captured through a computer controlled image capturing system and analyzed with image-J software. The integrated optical emission intensity of both samples showed an increasing trend with increasing pulses. Ag-ion deposited silicon showed higher optical emission intensity as compared to Pt-ion deposited silicon, suggesting that more damage occurred to the silicon by Ag ions, which was confirmed by SRIM/TRIM simulations. The surface morphologies of both samples were examined by optical microscope showing thermal, exfoliational and hydrodynamical sputtering processes along with the re-deposition of the material, debris and heat affected zones' formation. The crater of Pt-ion deposited silicon was deeper but had less lateral damage than Ag- ion deposited silicon. The novel results clearly indicated that the ion deposited silicon surface produced incubation centers, which led to more absorption of incident light resulting into a higher emission intensity from the plasma plume and deeper crater formation as compared to pure silicon. The approach can be effectively utilized in the laser induced breakdown spectroscopy technique, which endures poor limits of detection.

  20. Comment on 'Dynamics of an electron driven by relativistically intense laser radiation' [Phys. Plasmas 15, 023104 (2008)

    SciTech Connect

    Tian Youwei; Bao Gang; Zheng Ying; Yang Jianping; Yu Wei; Wang Xin

    2010-06-15

    Galkin et al. [Phys. Plasmas 15, 023104 (2008)] presented the comparison of the electron dynamics in the cases of the linear and circular polarizations of the optical fields. They assume that the longitudinal component of the laser field can be neglected in the case of longitudinal displacement less than the Rayleigh range. In this comment, we point out that the longitudinal component must be considered for the minimum spot size less than 10 times wavelength for linearly polarized laser pulse and for the minimum spot size less than 15 times wavelength for circularly polarized laser pulse.

  1. Two-dimensional particle-in-cell simulations of plasma cavitation and bursty Brillouin backscattering for nonrelativistic laser intensities

    SciTech Connect

    Riconda, C.; Weber, S.; Tikhonchuk, V. T.; Adam, J.-C.; Heron, A.

    2006-08-15

    Two-dimensional particle-in-cell simulations of laser-plasma interaction using a plane-wave geometry show strong bursty stimulated Brillouin backscattering, rapid filamentation, and subsequent plasma cavitation. It is shown that the cavitation is not induced by self-focusing. The electromagnetic fields below the plasma frequency that are excited are related to transient soliton-like structures. At the origin of these solitons is a three-wave decay process exciting new modes in the plasma. The cavitation is responsible for a strong local reduction of the reflectivity and goes along with an efficient but transient heating of the electrons. Once heating ceases, transmission starts to increase. Local as well as global average reflectivities attain a very low value due to strong plasma density variations brought about by the cavitation process. On the one hand, the simulations confirm the existence of a new mechanism of cavity and soliton formation in nonrelativistic laser-plasma interaction in two dimensions, which was shown to exist in one-dimensional simulations [S. Weber, C. Riconda, and V. T. Tikhonchuk, Phys. Rev. Lett. 94, 055005 (2005)]. On the other hand, new aspects are introduced inherently related to the additional degree of freedom.

  2. Operational plasma density and laser parameters for future colliders based on laser-plasma accelerators

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-12-21

    The operational plasma density and laser parameters for future colliders based on laser-plasma accelerators are discussed. Beamstrahlung limits the charge per bunch at low plasma densities. Reduced laser intensity is examined to improve accelerator efficiency in the beamstrahlung-limited regime.

  3. High-resolution measurements of the spatial and temporal evolution of megagauss magnetic fields created in intense short-pulse laser-plasma interactions

    SciTech Connect

    Chatterjee, Gourab Singh, Prashant Kumar; Adak, Amitava; Lad, Amit D.; Kumar, G. Ravindra

    2014-01-15

    A pump-probe polarimetric technique is demonstrated, which provides a complete, temporally and spatially resolved mapping of the megagauss magnetic fields generated in intense short-pulse laser-plasma interactions. A normally incident time-delayed probe pulse reflected from its critical surface undergoes a change in its ellipticity according to the magneto-optic Cotton-Mouton effect due to the azimuthal nature of the ambient self-generated megagauss magnetic fields. The temporal resolution of the magnetic field mapping is typically of the order of the pulsewidth, limited by the laser intensity contrast, whereas a spatial resolution of a few μm is achieved by this optical technique. High-harmonics of the probe can be employed to penetrate deeper into the plasma to even near-solid densities. The spatial and temporal evolution of the megagauss magnetic fields at the target front as well as at the target rear are presented. The μm-scale resolution of the magnetic field mapping provides valuable information on the filamentary instabilities at the target front, whereas probing the target rear mirrors the highly complex fast electron transport in intense laser-plasma interactions.

  4. Experimental observations and simulations on relativistic self-guiding of an ultra-intense laser pulse in underdense plasmas

    SciTech Connect

    Chiron, A.; Bonnaud, G.; Dulieu, A.; Miquel, J.L.; Malka, G.; Louis-Jacquet, M.; Mainfray, G.

    1996-04-01

    The experimental images of the sidescattered light from a plasma, created by the multiterawatt laser pulse propagating in a hydrogen gas jet, exhibit clear dependence on both gas jet pressure and laser power. Two- and three-dimensional simulations of wave propagation, in presence of the relativistic electron mass increase and the ponderomotive expel of electrons, have been performed to reproduce the Thomson radiation from the plasma electrons. They show electron cavitation induced by the beam focusing, self-focusing, self-guiding, smoothing of the beam nonuniformities and, at larger power, beam filamentation. A bremsstrahlung model with account of the ionization, heating, expansion, and recombination dynamics of the gas, provides the plasma emission background. Both Thomson emission and bremsstrahlung are required to recover the experimental emission patterns. Among the interpretations, a scenario of laser self-guiding over five Rayleigh lengths can be found for 10 TW laser power and 5{times}10{sup 18} cm{sup {minus}3} electron density, which surprisingly disappears at larger powers and densities. {copyright} {ital 1996 American Institute of Physics.}

  5. Plasma-based generation and control of a single few-cycle high-energy ultrahigh-intensity laser pulse.

    PubMed

    Tamburini, M; Di Piazza, A; Liseykina, T V; Keitel, C H

    2014-07-11

    A laser-boosted relativistic solid-density paraboloidal foil is known to efficiently reflect and focus a counterpropagating laser pulse. Here we show that in the case of an ultrarelativistic counterpropagating pulse, a high-energy and ultrahigh-intensity reflected pulse can be more effectively generated by a relatively slow and heavy foil than by a fast and light one. This counterintuitive result is explained with the larger reflectivity of a heavy foil, which compensates for its lower relativistic Doppler factor. Moreover, since the counterpropagating pulse is ultrarelativistic, the foil is abruptly dispersed and only the first few cycles of the counterpropagating pulse are reflected. Our multidimensional particle-in-cell simulations show that even few-cycle counterpropagating laser pulses can be further shortened (both temporally and in the number of laser cycles) with pulse amplification. A single few-cycle, multipetawatt laser pulse with several joules of energy and with a peak intensity exceeding 10(23)  W/cm(2) can be generated already employing next-generation high-power laser systems. In addition, the carrier-envelope phase of the generated few-cycle pulse can be tuned provided that the carrier-envelope phase of the initial counterpropagating pulse is controlled. PMID:25062199

  6. The nonlinear interplay between Raman scattering, self-focusing, and hosing of intense short-pulse lasers propagating in an underdense plasma

    NASA Astrophysics Data System (ADS)

    Tzeng, Kuo-Cheng

    1998-11-01

    Understanding the propagation of short-pulse high intensity lasers through Rayleigh lengths of underdense plasma is essential for the successful development of laser-plasma accelerator schemes and the fast ignitor fusion concept. When short-pulse lasers propagate through underdense plasmas they are susceptible to a wide range of instabilities, including Raman scattering, spot size self-modulation, relativistic self-focusing, and hosing. Furthermore, the highly nonlinear interplay between these instabilities leads to the generation of relativistic plasma waves which can wave break, generating kA's of relativistic electrons with energies up to ≈100 MeV. To unravel this complex interplay of instabilities, we use a fully relativistic parallelized particle-in-cell code. The simulations show that for parameters relevant to several ongoing laser-plasma accelerator experiments that significant laser absorption occurs within Rayleigh length distances, that Raman scattering and plasma heating can suppress self-focusing and ponderomotive blowout, and that the final nonlinear state of the pulses is dominated by a long wavelength hosing instability. The simulations also provide details of the characteristics of the accelerated electrons including, the self-trapping mechanism, their maximum energy, energy spread and emittance. The simulations show that the maximum energy can exceed simple dephasing estimates in agreement with recent experimental observations. This work was done in collaboration with R.G.Hemker, B.J.Duda, W.B.Mori and T.Katsouleas Work supported by DOE grants DE-FG-03-92-ER40727 and DE-FG-03-98-DP00211, LLNL contract W-7405-ENG-48, and NSF grant DMS-9722121. *Currently at Capital Management Sciences, Los Angeles

  7. Nonlinear laser energy depletion in laser-plasma accelerators

    SciTech Connect

    Shadwick, B.A.; Schroeder, C.B.; Esarey, E.

    2009-04-03

    Energy depletion of intense, short-pulse lasers via excitation of plasma waves is investigated numerically and analytically. The evolution of a resonant laser pulse proceeds in two phases. In the first phase, the pulse steepens, compresses, and frequency red-shifts as energy is deposited in the plasma. The second phase of evolution occurs after the pulse reaches a minimum length at which point the pulse rapidly lengthens, losing resonance with the plasma. Expressions for the rate of laser energy loss and rate of laser red-shifting are derived and are found to be in excellent agreement with the direct numerical solution of the laser field evolution coupled to the plasma response. Both processes are shown to have the same characteristic length-scale. In the high intensity limit, for nearly-resonant Gaussian laser pulses, this scale length is shown to be independent of laser intensity.

  8. Particle-in-cell simulations of ultra intense laser pulses propagating through overdense plasma for fast-ignitor and radiography applications

    NASA Astrophysics Data System (ADS)

    Lasinski, Barbara F.; Langdon, A. Bruce; Hatchett, Stephen P.; Key, Michael H.; Tabak, Max

    1999-05-01

    Zohar (two-dimensions, particle-in-cell) [C. K. Birdsall and A. B. Langdon, Plasma Physics via Computer Simulation (McGraw-Hill, New York, 1985)] simulations of ultra intense laser beams boring into overdense plasmas whose parameters are guided by the fast-ignitor concept and radiography applications are presented. Complex low frequency magnetic field structures, narrow channel formation, and beam deflection are all evident. Particle tracking diagnostics elucidate the nature of the currents that produce and interact with these static magnetic fields which are larger than 109 G for simulations at 1021W/cm2 in a 50nc plasma. Tracking electron orbits provides a more complete understanding of the hot electron generation as the short pulse, high intensity laser penetrates overdense plasma. Particles which constitute the current in the narrow channel are partially confined by the low frequency magnetic field. In contrast, the return current particles on the outside of the channel are defocused by the high magnetic field and move away from the channel.

  9. Particle-in-cell simulations of ultra intense laser pulses propagating through overdense plasma for fast-ignitor and radiography applications

    SciTech Connect

    Lasinski, B.F.; Langdon, A.B.; Hatchett, S.P.; Key, M.H.; Tabak, M.

    1999-05-01

    Zohar (two-dimensions, particle-in-cell) [C. K. Birdsall and A. B. Langdon, {ital Plasma Physics via Computer Simulation} (McGraw{endash}Hill, New York, 1985)] simulations of ultra intense laser beams boring into overdense plasmas whose parameters are guided by the fast-ignitor concept and radiography applications are presented. Complex low frequency magnetic field structures, narrow channel formation, and beam deflection are all evident. Particle tracking diagnostics elucidate the nature of the currents that produce and interact with these static magnetic fields which are larger than 10{sup 9} G for simulations at 10{sup 21} W/cm{sup 2} in a 50n{sub c} plasma. Tracking electron orbits provides a more complete understanding of the hot electron generation as the short pulse, high intensity laser penetrates overdense plasma. Particles which constitute the current in the narrow channel are partially confined by the low frequency magnetic field. In contrast, the return current particles on the outside of the channel are defocused by the high magnetic field and move away from the channel.

  10. Relativistic self-focusing of ultra-high intensity X-ray laser beams in warm quantum plasma with upward density profile

    SciTech Connect

    Habibi, M.; Ghamari, F.

    2014-05-15

    The results of a numerical study of high-intensity X-ray laser beam interaction with warm quantum plasma (WQP) are presented. By means of an upward ramp density profile combined with quantum factors specially the Fermi velocity, we have demonstrated significant relativistic self-focusing (RSF) of a Gaussian electromagnetic beam in the WQP where the Fermi temperature term in the dielectric function is important. For this purpose, we have considered the quantum hydrodynamics model that modifies refractive index of inhomogeneous WQPs with the inclusion of quantum correction through the quantum statistical and diffraction effects in the relativistic regime. Also, to better illustration of the physical difference between warm and cold quantum plasmas and their effect on the RSF, we have derived the envelope equation governing the spot size of X-ray laser beam in Q-plasmas. In addition to the upward ramp density profile, we have found that the quantum effects would be caused much higher oscillation and better focusing of X-ray laser beam in the WQP compared to that of cold quantum case. Our computational results reveal the importance of the use of electrons density profile and Fermi speed in enhancing self-focusing of laser beam.

  11. Space- and time-resolved density measurements of a high-intensity laser-produced plasma for x-ray laser studies.

    PubMed

    Dobosz, S; D'Oliveira, P; Hulin, S; Monot, P; Réau, F; Auguste, T

    2002-04-01

    We present a detailed study on the spatiotemporal density evolution of a plasma created by optical-field ionization of a high-pressure pulsed gas jet by a 10-TW, 60-fs Ti:sapphire laser. The plasma dynamics has been studied on a 17-ns time scale with a 60-fs time resolution and a 5-microm space resolution using a Mach-Zehnder interferometer. The density profile and the plasma radial expansion were accurately measured for conditions relevant to x-ray laser schemes in H-like nitrogen which were recently proposed [S. Hulin et al., Phys. Rev. E 61, 5693 (2000)]. The results were reproduced well by hydrocode simulations that allowed to infer the plasma temperature. PMID:12006081

  12. Double core-hole emissivity of transient aluminum plasmas produced in the interaction with ultra-intense x-ray laser pulse

    NASA Astrophysics Data System (ADS)

    Gao, Cheng; Zeng, Jiaolong; Yuan, Jianmin

    2015-11-01

    Emissivity of single core-hole (SCH) and double core-hole (DCH) states of aluminum plasmas produced in the interaction with ultra-intense x-ray laser pulse interaction are investigated systematically by solving the time-dependent rate equation implemented in the detailed level accounting approximation. We first demonstrated the plasma density effects on level populations and charge state distribution. Compared with recent experiments, it is shown that the plasma density effects play important roles in the evolution dynamics. Then we systematically investigated the emissivity of the transient aluminum plasmas produced by the x-ray laser pulses with a few photon energies above the threshold photon energy to create DCH states. For the laser photon energy where there are resonant absorptions (RA), 1s-np transitions with both full 1s and SCH 1s states play important roles in time evolution of the population and DCH emission spectroscopy. The significant RA effects are illustrated in detail for x-ray pulses, which creates the 1s-2p resonant absorption from the SCH states of Al VII. With the increase of the photon energy, the emissions from lower charge states become larger.

  13. Intense ion beams accelerated by ultra-intense laser pulses

    NASA Astrophysics Data System (ADS)

    Roth, Markus; Cowan, T. E.; Gauthier, J. C.; Vehn, J. Meyer-Ter; Allen, M.; Audebert, P.; Blazevic, A.; Fuchs, J.; Geissel, M.; Hegelich, M.; Karsch, S.; Pukhov, A.; Schlegel, T.

    2002-04-01

    The discovery of intense ion beams off solid targets irradiated by ultra-intense laser pulses has become the subject of extensive international interest. These highly collimated, energetic beams of protons and heavy ions are strongly depending on the laser parameters as well as on the properties of the irradiated targets. Therefore we have studied the influence of the target conditions on laser-accelerated ion beams generated by multi-terawatt lasers. The experiments were performed using the 100 TW laser facility at Laboratoire pour l'Utilisation des Laser Intense (LULI). The targets were irradiated by pulses up to 5×1019 W/cm2 (~300 fs,λ=1.05 μm) at normal incidence. A strong dependence on the surface conditions, conductivity, shape and purity was observed. The plasma density on the front and rear surface was determined by laser interferometry. We characterized the ion beam by means of magnetic spectrometers, radiochromic film, nuclear activation and Thompson parabolas. The strong dependence of the ion beam acceleration on the conditions on the target back surface was confirmed in agreement with predictions based on the target normal sheath acceleration (TNSA) mechanism. Finally shaping of the ion beam has been demonstrated by the appropriate tailoring of the target. .

  14. Generation of ultrahigh intensity laser pulses

    NASA Astrophysics Data System (ADS)

    Fisch, N. J.; Malkin, V. M.

    2003-05-01

    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 1025 W/cm2 can be contemplated using existing optical elements. These intensities are several orders of magnitude higher than what is currently available through chirped pump amplifiers.

  15. Intensity clamping in the filament of femtosecond laser radiation

    SciTech Connect

    Kandidov, V P; Fedorov, V Yu; Tverskoi, O V; Kosareva, O G; Chin, S L

    2011-04-30

    We have studied numerically the evolution of the light field intensity and induced refractive index of a medium upon filamentation of femtosecond laser radiation in air. It is shown that the intensity clamping results from the dynamic balance of optical powers of nonlinear lenses, induced by radiation due to the Kerr nonlinearity of air, and laser plasma produced during photoionisation. We have found the relation between the peak values of the light field intensity and the electron density in laser-produced plasma, as well as the transverse sizes of the filament and the plasma channel. (effects of laser radiation on matter)

  16. An unconventional ion implantation method for producing Au and Si nanostructures using intense laser-generated plasmas

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Cutroneo, M.; Mackova, A.; Lavrentiev, V.; Pfeifer, M.; Krousky, E.

    2016-02-01

    The present paper describes measurements of ion implantation by high-intensity lasers in an innovative configuration. The ion acceleration and implantation were performed using the target normal sheath acceleration regime. Highly ionized charged ions were generated and accelerated by the self-consistent electrostatic accelerating field at the rear side of a directly illuminated foil surface. A sub-nanosecond pulsed laser operating at an intensity of about 1016 W cm-2 was employed to irradiate thin foils containing Au atoms. Multi-energy and multi-species ions with energies of the order of 1 MeV per charge state were implanted on exposed substrates of monocrystalline silicon up to a concentration of about 1% Au atoms in the first superficial layers. The target, laser parameters and irradiation conditions play a decisive role in the dynamic control of the characteristics of the ion beams to be implanted. The ion penetration depth, the depth profile, the integral amount of implanted ions and the concentration-depth profiles were determined by Rutherford back-scattering analysis. Ion implantation produces Si nanocrystals and Au nanoparticles and induces physical and chemical modifications of the implanted surfaces.

  17. Describing electron motion in ultra-high intensity laser plasma interactions: the inclusion of a stochastic radiation reaction force

    NASA Astrophysics Data System (ADS)

    Ridgers, Christopher

    2014-10-01

    At intensities soon to be reached by next-generation laser facilities (exceeding 5 × 1022W/cm-2) electrons are accelerated so violently in the laser fields that they radiate energy (as gamma-ray photons) comparable to that they gain from the laser pulse. In this case the radiation reaction force becomes important in determining their motion. However, at these intensities the electric field in the electron's rest frame approaches the Schwinger field; the critical field of quantum electrodynamics where quantum effects on the radiation reaction force become crucial. In particular, the force transitions from a deterministic classical force to a stochastic force. I will compare electron motion when the radiation reaction is treated classically and stochastically, showing that the two treatments give the same result in the classical limit (correspondence) and that, surprisingly, a modified deterministic force (called the ``semi-classical'' model) can also be used when quantum effects are strong. I will also demonstrate that the semi-classical treatment fails to predict the rate of pair production by the emitted gamma-ray photons. To describe pair production one needs to adopt a new model for electron motion where the motion is described in terms of the evolution of a probability function in phase space as opposed to motion along a classical (deterministic) worldline.

  18. Filamentation of laser in an inhomogeneous plasma

    SciTech Connect

    Singh, Ranjeet; Tripathi, V. K.

    2011-02-15

    Filamentation of an intense short pulse laser in an inhomogeneous plasma is investigated when laser propagates along the direction of density gradient and nonlinearity arises due to the relativistic mass variation and ponderomotive force. The ion motion is neglected; however, the effect of dielectric swelling is included. The inhomogeneity in the density profile introduces dielectric swelling of the pump intensity enhancing the plasma permittivity and the growth rate of the instability. The perturbation in laser amplitude grows faster than exponential as the laser penetrates deeper into the denser plasma.

  19. Surface plasma wave excitation via laser irradiated overdense plasma foil

    SciTech Connect

    Kumar, Pawan; Tripathi, V. K.

    2012-04-09

    A laser irradiated overdense plasma foil is seen to be susceptible to parametric excitation of surface plasma wave (SPW) and ion acoustic wave (IAW) on the ion plasma period time scale. The SPW is localised near the front surface of the foil while IAW extends upto the rear. The evanescent laser field and the SPW exert a ponderomotive force on electrons driving the IAW. The density perturbation associated with the latter beats with the laser induced oscillatory electron velocity to drive the SPW. At relativistic laser intensity, the growth rate is of the order of ion plasma frequency.

  20. Plasma-based XUV lasers

    NASA Astrophysics Data System (ADS)

    Klisnick, A.

    2012-01-01

    This lecture is an introduction to the generation of plasma-based XUV lasers and their use as a source for scientific applications. We first discuss the main conditions required to create population inversions and amplify XUV radiation. We give an overview of the main properties of the different types of XUV lasers beams that are currently operational worldwide, while comparing them to other ultrashort, high-brightness sources existing in the same spectral range. We discuss recent demonstrations of applications of plasma-based XUV lasers to high-resolution imaging and interaction with matter at high intensity. Finally we conclude with current prospects for extending these sources to shorter wavelength and higher output intensity.

  1. Relativistic Laser-Plasma Interactions

    SciTech Connect

    Skoric, Milos M.

    2009-11-10

    Ever since the much acclaimed paper of Akhiezer and Polovin plasma theorists have been attempting to comprehend complex dynamics related to the propagation of high and ultra-high intensity electromagnetic (EM) radiation through a plasma. This topic was successfully revisited a number of years later by Kaw and Dawson whose analysis threw more light on the propagation of coupled longitudinal-transverse waves of arbitrary intensity. The high phase velocity case was soon solved exactly by Max and Perkins, (early review). The problem of relativistic laser-plasma interactions is of particular interest concerning the fast ignition concept, relevant to contemporary laser inertial confinement fusion research. Moreover, the understanding of relativistic laser pulse evolution in a plasma is basic to many new applications, including optical-field-ionized x-ray lasers, plasma-based electron accelerator schemes, as well as, interpretation of some astrophysical phenomena, and references, therein). From a text given in two tutorial lectures, in a limited space, we mainly focus on an important paradigm of stimulated Raman scattering.

  2. Pulse evolution and plasma-wave phase velocity in channel-guided laser-plasma accelerators.

    PubMed

    Benedetti, C; Rossi, F; Schroeder, C B; Esarey, E; Leemans, W P

    2015-08-01

    The self-consistent laser evolution of an intense, short-pulse laser exciting a plasma wave and propagating in a preformed plasma channel is investigated, including the effects of pulse steepening and energy depletion. In the weakly relativistic laser intensity regime, analytical expressions for the laser energy depletion, pulse self-steepening rate, laser intensity centroid velocity, and phase velocity of the plasma wave are derived and validated numerically. PMID:26382537

  3. Ta-ion implantation induced by a high-intensity laser for plasma diagnostics and target preparation

    NASA Astrophysics Data System (ADS)

    Cutroneo, M.; Malinsky, P.; Mackova, A.; Matousek, J.; Torrisi, L.; Slepicka, P.; Ullschmied, J.

    2015-12-01

    The present work is focused on the implantation of Ta ions into silicon substrates covered by a silicon dioxide layer 50-300 nm thick. The implantation is achieved using sub-nanosecond pulsed laser ablation (1015 W/cm2) with the objective of accelerating non-equilibrium plasma ions. The accelerated Ta ions are implanted into the exposed silicon substrates at energies of approximately 20 keV per charge state. By changing a few variables in the laser pulse, it is possible to control the kinetic energy, the yield and the angular distribution of the emitted ions. Rutherford Back-Scattering analysis was performed using 2.0 MeV He+ as the probe ions to determine the elemental depth profiles and the chemical composition of the laser-implanted substrates. The depth distributions of the implanted Ta ions were compared to SRIM 2012 simulations. The evaluated results of energy distribution were compared with online techniques, such as Ion Collectors (IC) and an Ion Energy Analyser (IEA), for a detailed identification of the produced ion species and their energy-to-charge ratios (M/z). Moreover, XPS (X-ray Photon Spectroscopy) and AFM (Atomic Force Microscopy) analyses were carried out to obtain information on the surface morphology and the chemical composition of the modified implanted layers, as these features are important for further application of such structures.

  4. X-ray line polarization of He-like Si satellite spectra in plasmas driven by high-intensity ultrashort pulsed lasers.

    PubMed

    Hakel, Peter; Mancini, Roberto C; Gauthier, Jean-Claude; Mínguez, Emilio; Dubau, Jacques; Cornille, Marguerite

    2004-05-01

    We present a modeling study of x-ray line polarization in plasmas driven by high-intensity, ultrashort duration pulsed lasers. Electron kinetics simulations of these transient and nonequilibrium plasmas predict non-Maxwellian and anisotropic electron distribution functions. Under these conditions, the magnetic sublevels within fine structure levels can be unequally populated which leads to the emission of polarized lines. We have developed a time-dependent, collisional-radiative atomic kinetics model of magnetic sublevels to understand the underlying processes and mechanisms leading to the formation of polarized x-ray line emission in plasmas with anisotropic electron distribution functions. The electron distribution function consists of a thermal component extracted from hydrodynamic calculations and a beam component determined by PIC simulations of the laser-plasma interaction. We focus on the polarization properties of the He-like Si satellites of the L y(alpha) line, discuss the time evolution of polarized satellite spectra, and identify suitable polarization markers that are sensitive to the anisotropy of the electron distribution function and can be used for diagnostic applications. PMID:15244949

  5. Time dependent Doppler shifts in high-order harmonic generation in intense laser interactions with solid density plasma and frequency chirped pulses

    SciTech Connect

    Welch, E. C.; Zhang, P.; He, Z.-H.; Dollar, F.; Krushelnick, K.; Thomas, A. G. R.

    2015-05-15

    High order harmonic generation from solid targets is a compelling route to generating intense attosecond or even zeptosecond pulses. However, the effects of ion motion on the generation of harmonics have only recently started to be considered. Here, we study the effects of ion motion in harmonics production at ultrahigh laser intensities interacting with solid density plasma. Using particle-in-cell simulations, we find that there is an optimum density for harmonic production that depends on laser intensity, which scales linearly with a{sub 0} with no ion motion but with a reduced scaling if ion motion is included. We derive a scaling for this optimum density with ion motion and also find that the background ion motion induces Doppler red-shifts in the harmonic structures of the reflected pulse. The temporal structure of the Doppler shifts is correlated to the envelope of the incident laser pulse. We demonstrate that by introducing a frequency chirp in the incident pulse we are able to eliminate these Doppler shifts almost completely.

  6. Resonance laser-plasma excitation of coherent terahertz phonons in the bulk of fluorine-bearing crystals under high-intensity femtosecond laser irradiation

    SciTech Connect

    Potemkin, F V; Mareev, E I; Khodakovskii, N G; Mikheev, P M

    2013-08-31

    The dynamics of coherent phonons in fluorine-containing crystals was investigated by pump-probe technique in the plasma production regime. Several phonon modes, whose frequencies are overtones of the 0.38-THz fundamental frequency, were simultaneously observed in a lithium fluoride crystal. Phonons with frequencies of 1 and 0.1 THz were discovered in a calcium fluoride crystal and coherent phonons with frequencies of 1 THz and 67 GHz were observed in a barium fluoride crystal. Furthermore, in the latter case the amplitudes of phonon mode oscillations were found to significantly increase 15 ps after laser irradiation. (interaction of laser radiation with matter)

  7. Collimated GeV proton beam generated by the interaction of ultra-intense laser with a uniform near-critical underdense plasma

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Zhu, Z.; Li, Y. Y.; Li, X. F.; Chen, C. Y.; Kong, Q.; Kawata, S.

    2011-08-01

    An ultra-intense short-pulsed laser interacting with a uniform underdense plasma with near-critical density is investigated by 2.5-dimensional particle-in-cell simulations. It is found that a collimated proton beam with maximum energy up to the GeV was generated. The corresponding proton acceleration mechanism is analyzed. The laser wakefield acceleration (LWFA) electrons play an important role as a driving beam. Due to the features of LWFA electrons, quasi-monoenergetic distribution and good collimation, the protons can be accelerated for a long distance by the charge-separated electric field. The proton beam in this regime is also well collimated and the amount can reach several nC. Moreover, it is found that the LWFA electrons can overtake the laser and stand quasi-synchronized in the center of pulse. Therefore the electrons can absorb energy from the laser and transfer it to the protons like in the break-out afterburner (BOA) scheme in laser irradiated on ultra-thin film target.

  8. Experimental evidence and theoretical analysis of photoionized plasma under x-ray radiation produced by intense laser

    NASA Astrophysics Data System (ADS)

    Wang, Feilu; Fujioka, Shinsuke; Nishimura, Hiroaki; Kato, Daiji; Li, Yutong; Zhao, Gang; Zhang, Jie; Takabe, Hideaki

    2008-04-01

    We composed a time-dependent detailed-configuration-accounting atomic model, which solves rate equations for level population distributions including collisional and radiative atomic processes based on the screened hydrogenic model (R. M. More, Handbook of Plasma Physics, vol. 3, Amsterdam: Elsevier Science Publishers, 1991). This model is used to interpret recent photoionization experiment on the large-scale laser system Gekko-XII (Yamanaka et al., 1981, IEEE, J. Quantum Electron. 17, 1639). In this experiment, the nitrogen gas was bathed in a Planckian radiation field of 80eV and was ionized beyond He-like state (open K-shell). It indicates the ionization parameter is around 10 erg cm/s under near steady-state conditions and the reasonable range of the electron temperature is 20-30eV. The comparison of synthetic and experimental spectra shows reasonable agreement and photoionization plays a significant role in this experiment.

  9. Self-focusing and stimulated Brillouin back-scattering of a long intense laser pulse in a finite temperature relativistic plasma

    SciTech Connect

    Niknam, A. R.; Barzegar, S.; Hashemzadeh, M.

    2013-12-15

    The nonlinear dynamics of electromagnetic waves propagating through a plasma considering the effects of relativistic mass and ponderomotive nonlinearities is investigated. The modified electron density distribution, the dispersion relation, and the spatial profiles of electromagnetic wave amplitude in the plasma are obtained. It is shown that the cut-off frequency decreases, and there is an intensity range in which the ponderomotive self-focusing takes place. In the upper limit of this range, the laser beam is defocused due to the relativistic ponderomotive force. In addition, the stability of electromagnetic waves to stimulated Brillouin scattering is studied, and the backscattered wave resulting from decay of high power electromagnetic beam is resolved in relativistic regime. The study of effects of electron density and temperature on the growth rate of backscattered wave has been shown that by increasing these effects, the growth rate of instability increases.

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

    SciTech Connect

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

    2006-08-07

    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{sub L}/L{sub n}, where d{sub L} is the laser beam diameter and L{sub n} is the plasma density gradient scale length. When d{sub L}>>L{sub n}, a dense highly collimated megaampere ion (proton) beam of the ion current density approaching TA/cm{sup 2} can be generated by skin-layer ponderomotive acceleration, even with a tabletop subpicosecond laser.

  11. Physics of Laser-driven plasma-based acceleration

    SciTech Connect

    Esarey, Eric; Schroeder, Carl B.

    2003-06-30

    The physics of plasma-based accelerators driven by short-pulse lasers is reviewed. This includes the laser wake-field accelerator, the plasma beat wave accelerator, the self-modulated laser wake-field accelerator, and plasma waves driven by multiple laser pulses. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse direction, electron dephasing, laser pulse energy depletion, as well as beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and plasmas with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Recent experimental results are summarized.

  12. On the possibility of the emission of attosecond pulses owing to the interaction of counterpropagating relativistically intense laser pulses with a thin layer of a diluted plasma

    NASA Astrophysics Data System (ADS)

    Platonenko, V. T.; Sterzhantov, A. F.

    2010-01-01

    A numerical experiment in which two relativistically intense laser pulses are normally incident on a layer of a diluted plasma from two opposite sides is described. The period of Langmuir plasma oscillations is much larger than the pulse duration and the product of this period by the speed of light is much larger than the thickness of the layer. A pulse propagating to the right is incident on the layer earlier than the counter pulse and carries a significant fraction of electrons or all of the electrons from the plasma. Under certain conditions, electrons form a bunch, which contains most of the electrons and has a thickness much smaller than the wavelength of light. The counter pulse perturbs the motion of the bunch and initiates the emission of a short few-cycle pulse, which propagates in the positive direction (to the right), significantly differs in structure from the counter pulse, and has a duration much smaller than the field period in laser pulses.

  13. Laser Guiding for GeV Laser-Plasma Accelerators

    SciTech Connect

    Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, C.B.; Toth, Csaba

    2005-06-06

    Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator (LWFA) at LBNL have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short term prospects for intense radiation sources based on laser-driven plasma accelerators.

  14. Laser guiding for GeV laser-plasma accelerators.

    PubMed

    Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, Carl; Tóth, Csaba

    2006-03-15

    Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator at Lawrence Berkeley National Laboratory (LBNL) have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short-term prospects for intense radiation sources based on laser-driven plasma accelerators. PMID:16483950

  15. Fundamental Physics Explored with High Intensity Laser

    NASA Astrophysics Data System (ADS)

    Tajima, T.; Homma, K.

    2012-10-01

    Over the last century the method of particle acceleration to high energies has become the prime approach to explore the fundamental nature of matter in laboratory. It appears that the latest search of the contemporary accelerator based on the colliders shows a sign of saturation (or at least a slow-down) in increasing its energy and other necessary parameters to extend this frontier. We suggest two pronged approach enabled by the recent progress in high intensity lasers. First we envision the laser-driven plasma accelerator may be able to extend the reach of the collider. For this approach to bear fruit, we need to develop the technology of high averaged power laser in addition to the high intensity. For this we mention that the latest research effort of ICAN is an encouraging sign. In addition to this, we now introduce the concept of the noncollider paradigm in exploring fundamental physics with high intensity (and large energy) lasers. One of the examples we mention is the laser wakefield acceleration (LWFA) far beyond TeV without large luminosity. If we relax or do not require the large luminosity necessary for colliders, but solely in ultrahigh energy frontier, we are still capable of exploring such a fundamental issue. Given such a high energetic particle source and high-intensity laser fields simultaneously, we expect to be able to access new aspects on the matter and the vacuum structure from fundamental physical point of views. LWFA naturally exploits the nonlinear optical effects in the plasma when it becomes of relativistic intensity. Normally nonlinear optical effects are discussed based upon polarization susceptibility of matter to external fields. We suggest application of this concept even to the vacuum structure as a new kind of order parameter to discuss vacuum-originating phenomena at semimacroscopic scales. This viewpoint unifies the following observables with the unprecedented experimental environment we envision; the dispersion relation of

  16. Progress of Laser-Driven Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuhisa

    2007-07-01

    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.

  17. Progress of Laser-Driven Plasma Accelerators

    SciTech Connect

    Nakajima, Kazuhisa

    2007-07-11

    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.

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

    NASA Astrophysics Data System (ADS)

    Tong, Huifeng; Yuan, Hong; Tang, Zhiping

    2013-01-01

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

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

    SciTech Connect

    Tong Huifeng; Yuan Hong; Tang Zhiping

    2013-01-28

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

  20. Detection of surface changes of materials caused by intense irradiation with laser-plasma EUV source utilizing scattered or luminescent radiation excited with the EUV pulses

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Rakowski, R.; Szczurek, M.

    2008-04-01

    Extreme ultraviolet (EUV) radiation is absorbed in a thin surface layer of any material. Irradiation of material samples with intense EUV pulses may cause different surface changes. Some of them, especially connected with material desorption, can be clearly visible using an optical or electron microscope. Other changes concerning crystal structure or chemical composition may not be visible under the microscope. They can however be detected using the EUV radiation itself. In this paper a new method of measurement of surface changes by irradiation with a laser-plasma EUV source is presented. The radiation was collected and focused on a material surface using a specially designed multifoil collector. Radiation scattered or excited in the material was detected with the use of a Wolter-type mirror coupled to a back-illuminated CCD camera. Depending on material samples, images with different intensity distributions were registered. For some samples, the intensity distributions of the images obtained before and after irradiation were slightly different. The intensity differences in such cases allowed us to obtain differential images. The appearance of such images was assumed to be evidence of surface changes.

  1. Study of 1–8 keV K-α x-ray emission from high intensity femtosecond laser produced plasma

    SciTech Connect

    Arora, V. Naik, P. A.; Chakera, J. A.; Bagchi, S.; Tayyab, M.; Gupta, P. D.

    2014-04-15

    We report an experimental study on the optimization of a laser plasma based x-ray source of ultra-short duration K-α line radiation. The interaction of pulses from a CPA based Ti:sapphire laser (10 TW, 45 fs, 10 Hz) system with magnesium, titanium, iron and copper solid target generates bright 1-8 keV K-α x-ray radiation. The x-ray yield was optimized with the laser pulse duration (at fixed fluence) which is varied in the range of 45 fs to 1.4 ps. It showed a maximum at laser pulse duration of ∼740 fs, 420 fs, 350 and 250 fs for Mg (1.3 keV), Ti (4.5 keV), Fe (6.4 keV) and Cu (8.05 keV) respectively. The x-ray yield is observed to be independent of the sign of the chirp. The scaling of the K-α yield (I{sub x} ∝ I{sub L}{sup β}) for 45 fs and optimized pulse duration were measured for laser intensities in the region of 3 × 10{sup 14} – 8 × 10{sup 17}. The x-ray yield shows a much faster scaling exponent β = 1.5, 2.1, 2.4 and 2.6 for Mg, Ti, Fe and Cu respectively at optimized pulse duration compared to scaling exponent of 0.65, 1.3, 1.5, and 1.7 obtained for 45 fs duration laser pulses. The laser to x-ray energy conversion efficiencies obtained for different target materials are η{sub Mg} = 1.2 × 10{sup −5}, η{sub Ti} = 3.1 × 10{sup −5}, η{sub Fe} = 2.7 × 10{sup −5}, η{sub Cu} = 1.9 × 10{sup −5}. The results have been explained from the efficient generation of optimal energy hot electrons at longer laser pulse duration. The faster scaling observed at optimal pulse duration indicates that the x-ray source is generated at the target surface and saturation of x-ray emission would appear at larger laser fluence. An example of utilization of the source for measurement of shock-wave profiles in a silicon crystal by time resolved x-ray diffraction is also presented.

  2. Laser Plasma Interactions at Intensities from 10{sup 12}W/cm{sup 2} to 10{sup 21} W/cm{sup 2}

    SciTech Connect

    Kruer, W L

    2002-11-05

    A tutorial introduction is given to some important physics and current challenges in laser plasma interactions. The topics are chosen to illustrate a few of John Dawson's many pioneering contributions to the physics and modeling of plasmas. In each case, a current frontier is also briefly discussed, including the .53{micro}m option for laser fusion, kinetic inflation of instability levels, and new regimes accessed with ultra-high power lasers.

  3. Relativistic plasma shutter for ultraintense laser pulses

    PubMed Central

    Reed, Stephen A.; Matsuoka, Takeshi; Bulanov, Stepan; Tampo, Motonobu; Chvykov, Vladimir; Kalintchenko, Galina; Rousseau, Pascal; Yanovsky, Victor; Kodama, Ryousuke; Litzenberg, Dale W.; Krushelnick, Karl; Maksimchuk, Anatoly

    2009-01-01

    A relativistic plasma shutter technique is proposed and tested to remove the sub-100 ps pedestal of a high-intensity laser pulse. The shutter is an ultrathin foil placed before the target of interest. As the leading edge of the laser ionizes the shutter material it will expand into a relativistically underdense plasma allowing for the peak pulse to propagate through while rejecting the low intensity pedestal. An increase in the laser temporal contrast is demonstrated by measuring characteristic signatures in the accelerated proton spectra and directionality from the interaction of 30 TW pulses with ultrathin foils along with supporting hydrodynamic and particle-in-cell simulations. PMID:19654882

  4. Laser Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Malka, Victor

    The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain, and to demonstrate new approaches for producing energetic particle beams. The extremely large electric fields, with amplitudes exceeding the TV/m level, that are produced in plasma medium are of relevance particle acceleration. Since the value of this longitudinal electric field, 10,000 times larger than those produced in conventional radio-frequency cavities, plasma accelerators appear to be very promising for the development of compact accelerators. The incredible progresses in the understanding of laser plasma interaction physic, allows an excellent control of electron injection and acceleration. Thanks to these recent achievements, laser plasma accelerators deliver today high quality beams of energetic radiation and particles. These beams have a number of interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine, radio-biology, chemistry, physics and material science,security (material inspection), and of course in accelerator science.

  5. Laser hosing in relativistically hot plasmas.

    PubMed

    Li, G; Mori, W B; Ren, C

    2013-04-12

    Electron response in an intense laser is studied in the regime where the electron temperature is relativistic. Equations for laser envelope and plasma density evolution, both in the electron plasma wave and ion acoustic wave regimes, are rederived from the relativistic fluid equations to include relativistic plasma temperature effect. These equations are used to study short-pulse and long-pulse laser hosing instabilities using a variational method approach. The analysis shows that relativistic electron temperatures reduce the hosing growth rates and shift the fastest-growing modes to longer wavelengths. These results resolve a long-standing discrepancy between previous nonrelativistic theory and simulations or experiments on hosing. PMID:25167277

  6. Reshaping of intense laser pulse with a capillary

    SciTech Connect

    Cao Lihua; Yu Wei; Yu, M. Y.; Wang Xin; Gu Yuqiu; He, X. T.

    2009-09-15

    The reshaping of intense laser pulse by vacuum capillary is studied by particle-in-cell simulation. It is shown that as an intense laser pulse propagates from free space into a capillary, its profile is reshaped due to laser-plasma interaction near the entrance of capillary. As a result, the free-space mode is self-consistently converted into a capillary mode. Only the relatively low-intensity periphery of the reshaped pulse interacts with the capillary-wall plasma, so that the high-intensity center of the pulse can propagate in the narrow vacuum channel over a distance much larger than the Rayleigh length. The mechanism is then applied to reshape a radially imperfect laser pulse having two wings around the center spot. Most of the output light energy is concentrated in the center spot, and the wings are almost completely removed. That is, the quality of the laser pulse can be greatly improved by a capillary.

  7. Current new applications of laser plasmas

    SciTech Connect

    Hauer, A.A.; Forslund, D.W.; McKinstrie, C.J.; Wark, J.S.; Hargis, P.J. Jr.; Hamil, R.A.; Kindel, J.M.

    1988-09-01

    This report describes several new applications of laser-produced plasmas that have arisen in the last few years. Most of the applications have been an outgrowth of the active research in laser/matter interaction inspired by the pursuit of laser fusion. Unusual characteristics of high-intensity laser/matter interaction, such as intense x-ray and particle emission, were noticed early in the field and are now being employed in a significant variety of applications outside the fusion filed. Applications range from biology to materials science to pulsed-power control and particle accelerators. 92 refs., 23 figs., 4 tabs.

  8. SPECIAL ISSUE DEVOTED TO THE 80TH ANNIVERSARY OF ACADEMICIAN N G BASOV'S BIRTH: Emission spectra of a plasma observed upon irradiation of solid targets by high-intensity ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Vergunova, G. A.; Ivanov, E. M.; Rozanov, Vladislav B.

    2003-02-01

    The spectral radiative losses are investigated in a plasma under conditions typical of a plasma produced upon irradiation of solid targets by high-intensity (up to 1017 W cm-2 ultrashort (10-13-10-9 s) laser pulses. The comparison of the calculated X-ray spectra with the experimental data for aluminum and carbon plasmas shows their satisfactory agreement. These studies made it possible to test the methods in use and to conclude that it is necessary to introduce supplements into the collision — radiation model for calculating the optical characteristics of a nonequilibrium plasma of complex chemical composition.

  9. Flash imaging of fine structures of cellular organelles by contact x-ray microscopy with a high intensity laser plasma x-ray source

    NASA Astrophysics Data System (ADS)

    Kado, Masataka; Ishino, Masahiko; Kishimoto, Maki; Tamotsu, Satoshi; Yasuda, Keiko; Kinjo, Yasuhito; Shinohara, Kunio

    2011-09-01

    X-ray flash imaging by contact microscopy with a highly intense laser-plasma x-ray source was achieved for the observation of wet biological cells. The exposure time to obtain a single x-ray image was about 600 ps as determined by the pulse duration of the driving laser pulse. The x-ray flash imaging makes it possible to capture an x-ray image of living biological cells without any artificial treatment such as staining, fixation, freezing, and so on. The biological cells were cultivated directly on the surface of the silicon nitride membranes, which are used for the x-ray microscope. Before exposing the cells to x-rays they were observed by a conventional fluorescent microscope as reference, since the fluorescent microscopes can visualize specific organelles stained with fluorescent dye. Comparing the x-ray images with the fluorescent images of the exact same cells, each cellular organelle observed in the x-ray images was identified one by one and actin filaments and mitochondria were clearly identified in the x-ray images.

  10. EDITORIAL: Laser and plasma accelerators Laser and plasma accelerators

    NASA Astrophysics Data System (ADS)

    Bingham, Robert

    2009-02-01

    This special issue on laser and plasma accelerators illustrates the rapid advancement and diverse applications of laser and plasma accelerators. Plasma is an attractive medium for particle acceleration because of the high electric field it can sustain, with studies of acceleration processes remaining one of the most important areas of research in both laboratory and astrophysical plasmas. The rapid advance in laser and accelerator technology has led to the development of terawatt and petawatt laser systems with ultra-high intensities and short sub-picosecond pulses, which are used to generate wakefields in plasma. Recent successes include the demonstration by several groups in 2004 of quasi-monoenergetic electron beams by wakefields in the bubble regime with the GeV energy barrier being reached in 2006, and the energy doubling of the SLAC high-energy electron beam from 42 to 85 GeV. The electron beams generated by the laser plasma driven wakefields have good spatial quality with energies ranging from MeV to GeV. A unique feature is that they are ultra-short bunches with simulations showing that they can be as short as a few femtoseconds with low-energy spread, making these beams ideal for a variety of applications ranging from novel high-brightness radiation sources for medicine, material science and ultrafast time-resolved radiobiology or chemistry. Laser driven ion acceleration experiments have also made significant advances over the last few years with applications in laser fusion, nuclear physics and medicine. Attention is focused on the possibility of producing quasi-mono-energetic ions with energies ranging from hundreds of MeV to GeV per nucleon. New acceleration mechanisms are being studied, including ion acceleration from ultra-thin foils and direct laser acceleration. The application of wakefields or beat waves in other areas of science such as astrophysics and particle physics is beginning to take off, such as the study of cosmic accelerators considered

  11. High-intensity laser heating in liquids: Multiphoton absorption

    SciTech Connect

    Longtin, J.P.; Tien, C.L.

    1995-12-31

    At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in absorption and heating several orders of magnitude greater than classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for strong, controlled energy deposition in liquids without bulk plasma formation, shock waves, liquid ejection, etc., which is of interest for many laser-liquid applications, including laser desorption of liquid films, laser particle removal, and laser water removal from microdevices. This work develops a microscopically based model of the heating during multiphoton absorption in liquids. The dependence on pulse duration, intensity, wavelength, repetition rate, and liquid properties is discussed. Pure water exposed to 266 nm laser radiation is investigated, and a novel heating mechanism for water is proposed that uses multiple-wavelength laser pulses.

  12. Molecules and Clusters in Intense Laser Fields

    NASA Astrophysics Data System (ADS)

    Posthumus, Jan

    2009-09-01

    Preface; 1. Ultra-high intensity based on Ti:Sapphire Philip F. Taday and Andrew J. Langley; 2. Diatomic molecules in intense laser fields Jan H. Posthumus and James F. McCann; 3. Small polyatomic molecules in intense laser fields C. Cornaggia; 4. Coherent control in intense laser fields Eric Charron and Brian Sheehy; 5. Experimental studies of laser-heated rare gas clusters M. Lezius and M. Schmidt; 6. Single cluster explosions and high harmonic generation John W. G. Tisch and Emma Springate; 7. Intense laser interaction with extended cluster media Roland A. Smith and Todd Ditmire.

  13. Molecules and Clusters in Intense Laser Fields

    NASA Astrophysics Data System (ADS)

    Posthumus, Jan

    2001-06-01

    Preface; 1. Ultra-high intensity based on Ti:Sapphire Philip F. Taday and Andrew J. Langley; 2. Diatomic molecules in intense laser fields Jan H. Posthumus and James F. McCann; 3. Small polyatomic molecules in intense laser fields C. Cornaggia; 4. Coherent control in intense laser fields Eric Charron and Brian Sheehy; 5. Experimental studies of laser-heated rare gas clusters M. Lezius and M. Schmidt; 6. Single cluster explosions and high harmonic generation John W. G. Tisch and Emma Springate; 7. Intense laser interaction with extended cluster media Roland A. Smith and Todd Ditmire.

  14. Optimum laser intensity for the production of energetic deuterium ions from laser-cluster interaction

    NASA Astrophysics Data System (ADS)

    Bang, W.; Dyer, G.; Quevedo, H. J.; Bernstein, A. C.; Gaul, E.; Rougk, J.; Aymond, F.; Donovan, M. E.; Ditmire, T.

    2013-09-01

    We measured, using Petawatt-level pulses, the average ion energy and neutron yield in high-intensity laser interactions with molecular clusters as a function of laser intensity. The interaction volume over which fusion occurred (1-10 mm3) was larger than previous investigations, owing to the high laser power. Possible effects of prepulses were examined by implementing a pair of plasma mirrors. Our results show an optimum laser intensity for the production of energetic deuterium ions both with and without the use of the plasma mirrors. We measured deuterium plasmas with 14 keV average ion energies, which produced 7.2 × 106 and 1.6 × 107 neutrons in a single shot with and without plasma mirrors, respectively. The measured neutron yields qualitatively matched the expected yields calculated using a cylindrical plasma model.

  15. Optimum laser intensity for the production of energetic deuterium ions from laser-cluster interaction

    SciTech Connect

    Bang, W.; Dyer, G.; Quevedo, H. J.; Bernstein, A. C.; Gaul, E.; Rougk, J.; Aymond, F.; Donovan, M. E.; Ditmire, T.

    2013-09-15

    We measured, using Petawatt-level pulses, the average ion energy and neutron yield in high-intensity laser interactions with molecular clusters as a function of laser intensity. The interaction volume over which fusion occurred (1–10 mm{sup 3}) was larger than previous investigations, owing to the high laser power. Possible effects of prepulses were examined by implementing a pair of plasma mirrors. Our results show an optimum laser intensity for the production of energetic deuterium ions both with and without the use of the plasma mirrors. We measured deuterium plasmas with 14 keV average ion energies, which produced 7.2 × 10{sup 6} and 1.6 × 10{sup 7} neutrons in a single shot with and without plasma mirrors, respectively. The measured neutron yields qualitatively matched the expected yields calculated using a cylindrical plasma model.

  16. Laser Plasma and Hydrodynamics Experiments with KrF Lasers

    NASA Astrophysics Data System (ADS)

    Weaver, James

    2006-10-01

    The proposed Fusion Test Facility (FTF) will exploit the unique features of Krypton Fluoride (KrF) lasers to achieve ignition and substantial gain (>20) at <500 kJ laser energies using direct drive.[1] The strategy uses highly uniform, high bandwidth, 248 nm KrF laser illumination at intensities near 2 x 10^15 W/cm^2 to accelerate low-aspect ratio pellets to implosion velocities of 400 km/s. Higher than usual implosion velocity allows ignition at substantially reduced laser energy. Amplitudes of both hydrodynamic instability during the pellet implosion and deleterious laser plasma instability (LPI) in the corona must be kept sufficiently low if one is to achieve ignition and gain. Increased laser intensity reduces hydrodynamic instability because it allows acceleration of thicker, low aspect ratio pellets, but is also more likely to produce deleterious LPI. The deep UV wavelength of KrF should allow use of these higher intensities. Studies of hydrodynamic instabilities and laser plasma instabilities (LPI) are the subject of ongoing experiments at the 2-3 kJ Nike KrF laser. The Nike laser has demonstrated highly uniform UV irradiation of planar targets at moderate laser intensities (I˜10^14 W/cm^2), including the recent addition of short duration ``spike'' prepulses for hydrodynamic stability studies. A new effort in LPI physics is underway at the Nike facility where the peak intensity is being extended above 10^15 W/cm^2 by a combination of smaller focal diameters and shorter pulse lengths. This talk will discuss progress in the ongoing experiments at Nike in support of the FTF design. [1] S. P. Obenschain, et al., Phys. Plasmas 13 056329 (2006).

  17. Progress on laser plasma accelerators

    SciTech Connect

    Chen, P.

    1986-04-01

    Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experimental results obtained on the PBWA experiment at UCLA confirms this. Parameters related to the PBWA as an accelerator system are derived, among them issues concerning the efficiency and the laser power and energy requirements are discussed.

  18. Collaborative Research: Instability and transport of laser beam in plasma

    SciTech Connect

    Rose, Harvey Arnold; Lushnikov, Pavel

    2014-11-18

    Our goal was to determine the onset of laser light scattering due to plasma wave instabilities. Such scatter is usually regarded as deleterious since laser beam strength is thereby diminished. While this kind of laser-plasma-instability (LPI) has long been understood for the case of coherent laser light, the theory of LPI onset for a laser beam with degraded coherence is recent. Such a laser beam fills plasma with a mottled intensity distribution, which has large fluctuations. The key question is: do the exceptionally large fluctuations control LPI onset or is it controlled by the relatively quiescent background laser intensity? We have answered this question. This is significant because LPI onset power in the former case is typically small compared to that of the latter. In addition, if large laser intensity fluctuations control LPI onset, then nonlinear effects become significant for less powerful laser beams than otherwise estimated.

  19. Study of Acceleration, Transport and Dephasing of Hot Electrons in Solid Density Plasmas Irradiated with Ultra Intense Laser Pulses

    NASA Astrophysics Data System (ADS)

    Cho, B. I.; Osterholz, J.; Bernstein, A. C.; Dyer, G. M.; Ditmire, T.

    2008-04-01

    We have characterized the transport of hot electrons in solid targets by coherent transition radiation (CTR). CTR was observed from the rear side of aluminum foils irradiated with the THOR laser (800 nm, 40 fs, 600 mJ, 2 x 10^19 W/cm^2) at the University of Texas at Austin. In the experiment, two distinct beams of hot electrons are emitted simultaneously from the target rear side. This observation shows that two different mechanisms, namely resonance absorption and j x B heating, accelerate the electrons at the target front side. These two distinct beams propagate through aluminum foils with different spatial and temporal characteristics and electron temperatures. The interpretation is confirmed by calculations of the electron acceleration and transport inside the target.

  20. Femtosecond laser-induced electronic plasma at metal surface

    SciTech Connect

    Chen Zhaoyang; Mao, Samuel S.

    2008-08-04

    We develop a theoretical analysis to model plasma initiation at the early stage of femtosecond laser irradiation of metal surfaces. The calculation reveals that there is a threshold intensity for the formation of a microscale electronic plasma at the laser-irradidated metal surface. As the full width at half maximum of a laser pulse increases from 15 to 200 fs, the plasma formation threshold decreases by merely about 20%. The dependence of the threshold intensity on laser pulse width can be attributed to laser-induced surface electron emission, in particular due to the effect of photoelectric effect.

  1. Plasma ignition for laser propulsion

    NASA Technical Reports Server (NTRS)

    Askew, R. F.

    1982-01-01

    For a specific optical system a pulsed carbon dioxide laser having an energy output of up to 15 joules was used to initiate a plasma in air at one atmosphere pressure. The spatial and temporal development of the plasma were measured using a multiframe image converter camera. In addition the time dependent velocity of the laser supported plasma front which moves opposite to the direction of the laser pulse was measured in order to characterize the type of wavefront developed. Reliable and reproducible spark initiation was achieved. The lifetime of the highly dense plasma at the initial focal spot was determined to be less than 100 nanoseconds. The plasma front propagates toward the laser at a variable speed ranging from zero to 1.6 x 1,000,000 m/sec. The plasma front propagates for a total distance of approximately five centimeters for the energy and laser pulse shape employed.

  2. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Generating collimated intense monochromatic beams of soft x radiation from an X-pinch in the wavelength region 0.4-1.0 nm by means of spherical crystal mirrors

    NASA Astrophysics Data System (ADS)

    Faenov, A. Ya; Mingaleev, A. R.; Pikuz, S. A.; Pikuz, T. A.; Romanova, V. M.; Skobelev, I. Yu; Shelkovenko, T. A.

    1993-05-01

    The generation of collimated intense monochromatic beams of soft x radiation in the wavelength interval 0.4-1.0 nm from an X-pinch is reported. This is the first such report. High-quality mica crystals with dimensions of 10 × (30-35) mm were used to form beams with an energy of 2-3.2 μJ, a wavelength spread Δλ/λ=4 · 10-3, and a divergence of 5 · 10-4 rad. The mica crystals were bent into spherical surfaces with a radius of curvature of 10 or 25 cm. The characteristics of the resulting beams are compared with those of the beams from Ta lasers, with a wavelength ~4.5 nm, which are the shortest-wavelength x-ray lasers which have been reported to date. This comparison shows that the beams obtained in the present study are better than those from the Ta laser in terms of several characteristics (divergence, wavelength, and efficiency), while they are worse (but not greatly so) in terms of certain other characteristics (wavelength spread and energy in the pulse. It is thus possible today to solve many practical problems involving the use of collimated intense monochromatic beams of soft x radiation in the wavelength interval 0.25-2.0 nm. These problems can be solved with the help of the x radiation from an X-pinch or from plasmas produced by picosecond or femtosecond table-top lasers and short-focal-length, large-aperture crystal mirrors.

  3. Measurements of Intense Femtosecond Laser Pulse Propagation in Air

    NASA Astrophysics Data System (ADS)

    Ting, Antonio

    2004-11-01

    Intense femtosecond pulses generated from chirped pulse amplification (CPA) lasers can deliver laser powers many times above the critical power for self-focusing in air. Catastrophic collapse of the laser pulse is usually prevented by the defocusing of the plasma column formed when the laser intensity gets above the threshold for multiphoton ionization. The resultant laser/plasma filament can extend many meters as the laser pulse propagates in the atmosphere. We have carried out a series of experiments both for understanding the formation mechanisms of the filaments and the nonlinear effects such as white light and harmonics generation associated with them. Many applications of these filaments such as remote atmospheric breakdown, laser induced electrical discharge and femtosecond laser material interactions require direct measurements of their characteristics. Direct measurements of these filaments had been difficult because the high laser intensity ( ˜10^13 W/cm^2) can damage practically any optical diagnostics. A novel technique was invented to obtain the first absolute measurements of laser energy, transverse profile, fluence and spectral content of the filaments. We are investigating a ``remote atmospheric breakdown'' concept of remotely sensing chemical and biological compounds. A short intense laser pulse can be generated at a remote position by using the group velocity dispersion (GVD) of the air to compress an initially long, frequency negatively chirped laser pulse to generate the air breakdown and filaments. We have observed that nonlinear contributions to the laser spectrum through self-phase modulation can lead to modification of the linear GVD compression. We have also observed the generation of ultraviolet (UV) radiations from these filaments in air and the induced fluorescence by the UV radiation of a surrogate biological agent. These and other results such as laser induced electrical discharges will be presented.

  4. Effect of laser intensity on radio frequency emissions from laser induced breakdown of atmospheric air

    NASA Astrophysics Data System (ADS)

    Vinoth Kumar, L.; Manikanta, E.; Leela, Ch.; Prem Kiran, P.

    2016-06-01

    The studies on the effect of input laser intensity, through the variation of laser focusing geometry, on radio frequency (RF) emissions, over 30-1000 MHz from nanosecond (ns) and picosecond (ps) laser induced breakdown (LIB) of atmospheric air are presented. The RF emissions from the ns and ps LIB were observed to be decreasing and increasing, respectively, when traversed from tight to loose focusing conditions. The angular and radial intensities of the RF emissions from the ns and ps LIB are found to be consistent with sin2θ/r2 dependence of the electric dipole radiation. The normalized RF emissions were observed to vary with incident laser intensity (Iλ2), indicating the increase in the induced dipole moment at moderate input laser intensities and the damping of radiation due to higher recombination rate of plasma at higher input laser intensities.

  5. TOPICAL REVIEW: Relativistic laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Umstadter, Donald

    2003-04-01

    By focusing petawatt peak power laser light to intensities up to 1021 W cm-2, highly relativistic plasmas can now be studied. The force exerted by light pulses with this extreme intensity has been used to accelerate beams of electrons and protons to energies of a million volts in distances of only microns. This acceleration gradient is a thousand times greater than in radio-frequency-based accelerators. Such novel compact laser-based radiation sources have been demonstrated to have parameters that are useful for research in medicine, physics and engineering. They might also someday be used to ignite controlled thermonuclear fusion. Ultrashort pulse duration particles and x-rays that are produced can resolve chemical, biological or physical reactions on ultrafast (femtosecond) timescales and on atomic spatial scales. These energetic beams have produced an array of nuclear reactions, resulting in neutrons, positrons and radioactive isotopes. As laser intensities increase further and laser-accelerated protons become relativistic, exotic plasmas, such as dense electron-positron plasmas, which are of astrophysical interest, can be created in the laboratory. This paper reviews many of the recent advances in relativistic laser-plasma interactions.

  6. Pushing the Limits of Plasma Length in Inertial-Fusion Laser-Plasma Interaction Experiments

    NASA Astrophysics Data System (ADS)

    Froula, D. H.; Divol, L.; London, R. A.; Michel, P.; Berger, R. L.; Meezan, N. B.; Neumayer, P.; Ross, J. S.; Wallace, R.; Glenzer, S. H.

    2008-01-01

    We demonstrate laser beam propagation and low backscatter in laser produced hohlraum plasmas of ignition plasma length. At intensities I<5×1014Wcm-2 greater than 80% of the energy in a blue (3ω, 351 nm) laser is transmitted through a L=5-mm long, high-temperature (Te=2.5keV), high-density (ne=5×1020cm-3) plasma. These experiments show that the backscatter scales exponentially with plasma length which is consistent with linear theory. The backscatter calculated by a new steady state 3D laser-plasma interaction code developed for large ignition plasmas is in good agreement with the measurements.

  7. Plasma mirrors for short pulse lasers

    SciTech Connect

    Yanovksy, V.P.; Perry, M.D.; Brown, C.G.; Feit, M.D.; Rubenchik, A.

    1997-06-11

    We show experimentally and theoretically that plasmas created by a sufficiently (1014 1015 2 short (<500 fs) intense W/cm ) laser pulse on the surface of dielectric material act as nearly perfect mirrors: reflecting p to 90% of the incident radiation with a wavefront quality equal to that of the initial solid surface.

  8. Wavelength scaling of laser plasma coupling

    SciTech Connect

    Kruer, W.L.

    1983-11-03

    The use of shorter wavelength laser light both enhances collisional absorption and reduces deleterious collective plasma effects. Coupling processes which can be important in reactor-size targets are briefly reviewed. Simple estimates are presented for the intensity-wavelength regime in which collisional absorption is high and collective effects are minimized.

  9. Pulse distortion and modulation instability in laser plasma interaction

    SciTech Connect

    Jha, Pallavi; Singh, Ram Gopal; Upadhyay, Ajay K.

    2009-01-15

    The present paper deals with the propagation of a short, intense, Gaussian laser pulse in plasma. Using a one dimensional model, a wave equation including finite pulse length and group velocity dispersion is set up and solved to obtain the intensity distribution across the laser pulse. It is shown that the pulse profile becomes asymmetric as it propagates through plasma. Further, the growth rate of modulation instability and range of unstable frequencies across the laser pulse have been derived and graphically analyzed.

  10. Laser welding control by monitoring of plasma

    NASA Astrophysics Data System (ADS)

    Chmelickova, Hana; Sebestova, Hana; Havelkova, Martina; Rihakova, Lenka; Nozka, Libor

    2013-04-01

    Deep penetration welding is a typical industrial application of high power lasers, where plasma can be generated above the keyhole. Thanks to the plasma plume presence welding process can be controlled on-line by means of the plasma intensity measurements. Various on-line monitoring methods have been developed in research centers all over the world. Goal of them is to enable promptly operator action to avoid enormous economical looses if un-expected defect is detected. Our laboratory was participated in project CLET - "Closed loop control of the laser welding process through the measurement of plasma" as a responsible partner for developed system testing both in the laboratory with pulsed Nd:YAG laser and in the real welding facility with high power continual CO2 laser. Control system is based on the electron temperature computation from the relative intensities of couple of emission lines belong to certain metal ion present in plasma plume. Our experiment was realized using Ocean Optics HR2000+ spectrometer within the stainless steel tube longitudinal welding. Several couples of emission lines were tested to acquire a good signal at actual welding conditions. Then power calibration was made to obtain the electron temperature dependence on increasing power. Samples were prepared for microanalysis and measured by laser confocal scanning microscope to find optimal power range for full penetrations achieving without thermal distortion of the tube or weld humping. Numerical model of the remelted area cross section was made to display temperature distribution dependence on increasing power.

  11. Relativistic laser pulse compression in magnetized plasmas

    SciTech Connect

    Liang, Yun; Sang, Hai-Bo Wan, Feng; Lv, Chong; Xie, Bai-Song

    2015-07-15

    The self-compression of a weak relativistic Gaussian laser pulse propagating in a magnetized plasma is investigated. The nonlinear Schrödinger equation, which describes the laser pulse amplitude evolution, is deduced and solved numerically. The pulse compression is observed in the cases of both left- and right-hand circular polarized lasers. It is found that the compressed velocity is increased for the left-hand circular polarized laser fields, while decreased for the right-hand ones, which is reinforced as the enhancement of the external magnetic field. We find a 100 fs left-hand circular polarized laser pulse is compressed in a magnetized (1757 T) plasma medium by more than ten times. The results in this paper indicate the possibility of generating particularly intense and short pulses.

  12. Improving sensitivity of laser-induced breakdown spectroscopy using laser plasmas interaction

    NASA Astrophysics Data System (ADS)

    Il'in, Alexey A.; Golik, Sergey S.; Nagorny, Ivan G.; Bulanov, Alexey V.

    2006-11-01

    Laser plasmas interaction and spectral characteristics of plasma were investigated at a laser breakdown in a normal atmosphere with the purpose of improving laser-induced breakdown spectroscopy sensitivity. Colliding plasmas interaction was investigated depending on mechanism of absorption wave of laser radiation and distance between foci. Laser supported detonation wave, breakdown wave and fast wave of ionization are absorption wave observed in experiment. It was shown that seed electrons for cascade breakdown in front of fast wave of ionization is occurred due to oxygen molecules photoionization. Molecular emission and collapse of intensity of plasma continuum during the initial moments of laser plasma expansion were registered. The line/continuum ratio was essentially increased in case of laser plasmas interaction. Thus laser plasmas interaction improves sensitivity of LIBS.

  13. Relativistic focusing and ponderomotive channeling of intense laser beams

    PubMed

    Hafizi; Ting; Sprangle; Hubbard

    2000-09-01

    The ponderomotive force associated with an intense laser beam expels electrons radially and can lead to cavitation in plasma. Relativistic effects as well as ponderomotive expulsion of electrons modify the refractive index. An envelope equation for the laser spot size is derived, using the source-dependent expansion method with Laguerre-Gaussian eigenfunctions, and reduced to quadrature. The envelope equation is valid for arbitrary laser intensity within the long pulse, quasistatic approximation and neglects instabilities. Solutions of the envelope equation are discussed in terms of an effective potential for the laser spot size. An analytical expression for the effective potential is given. For laser powers exceeding the critical power for relativistic self-focusing the analysis indicates that a significant contraction of the spot size and a corresponding increase in intensity is possible. PMID:11088939

  14. Relativistic focusing and ponderomotive channeling of intense laser beams

    SciTech Connect

    Hafizi, B.; Ting, A.; Sprangle, P.; Hubbard, R. F.

    2000-09-01

    The ponderomotive force associated with an intense laser beam expels electrons radially and can lead to cavitation in plasma. Relativistic effects as well as ponderomotive expulsion of electrons modify the refractive index. An envelope equation for the laser spot size is derived, using the source-dependent expansion method with Laguerre-Gaussian eigenfunctions, and reduced to quadrature. The envelope equation is valid for arbitrary laser intensity within the long pulse, quasistatic approximation and neglects instabilities. Solutions of the envelope equation are discussed in terms of an effective potential for the laser spot size. An analytical expression for the effective potential is given. For laser powers exceeding the critical power for relativistic self-focusing the analysis indicates that a significant contraction of the spot size and a corresponding increase in intensity is possible. (c) 2000 The American Physical Society.

  15. Relativistic soliton formation in laser magnetized plasma interactions

    NASA Astrophysics Data System (ADS)

    Feng, W.; Li, J. Q.; Kishimoto, Y.

    2016-05-01

    The laser plasma interactions in the presence of strong magnetic field are studied by employing particle-in-cell simulations. Simulations show that the energy absorption of strong laser pulse is mainly characterized by the electron cyclotron resonance heating (ECRH) when the magnetic field is large enough. However, it is found that for a weaker magnetic field, a standing or moving soliton can be generated in some moderate laser intensity regions, greatly enhancing the laser absorption. The laser intensity for the soliton heating decreases as the magnetic field increases. Furthermore, the soliton position moves towards the front boundary when the laser intensity or magnetic field strength increases.

  16. Terahertz radiation from a laser plasma filament.

    PubMed

    Wu, H-C; Meyer-Ter-Vehn, J; Ruhl, H; Sheng, Z-M

    2011-03-01

    By the use of two-dimensional particle-in-cell simulations, we clarify the terahertz (THz) radiation mechanism from a plasma filament formed by an intense femtosecond laser pulse. The nonuniform plasma density of the filament leads to a net radiating current for THz radiation. This current is mainly located within the pulse and the first cycle of the wakefield. As the laser pulse propagates, a single-cycle and radially polarized THz pulse is constructively built up forward. The single-cycle shape is mainly due to radiation damping effect. PMID:21517604

  17. Interpenetration and stagnation in colliding laser plasmas

    SciTech Connect

    Al-Shboul, K. F.; Harilal, S. S. Hassan, S. M.; Hassanein, A.; Costello, J. T.; Yabuuchi, T.; Tanaka, K. A.; Hirooka, Y.

    2014-01-15

    We have investigated plasma stagnation and interaction effects in colliding laser-produced plasmas. For generating colliding plasmas, two split laser beams were line-focused onto a hemi-circular target and the seed plasmas so produced were allowed to expand in mutually orthogonal directions. This experimental setup forced the expanding seed plasmas to come to a focus at the center of the chamber. The interpenetration and stagnation of plasmas of candidate fusion wall materials, viz., carbon and tungsten, and other materials, viz., aluminum, and molybdenum were investigated in this study. Fast-gated imaging, Faraday cup ion analysis, and optical emission spectroscopy were used for diagnosing seed and colliding plasma plumes. Our results show that high-Z target (W, Mo) plasma ions interpenetrate each other, while low-Z (C, Al) plasmas stagnate at the collision plane. For carbon seed plasmas, an intense stagnation was observed resulting in longer plasma lifetime; in addition, the stagnation layer was found to be rich with C{sub 2} dimers.

  18. Fast Ignition relevant study of the flux of high intensity laser generated electrons via a hollow cone into a laser-imploded plasma

    SciTech Connect

    Key, M; Adam, J; Akli, K; Borgheshi, M; Chen, M; Evans, R; Freeman, R; Hatchett, S; Hill, J; Heron, A; King, J; Lancaster, K; Mackinnon, A; Norreys, P; Phillips, T; Romagnani, L; Snavely, R; Stephens, R; Stoeckl, C

    2005-10-11

    An integrated experiment relevant to fast ignition is described. A Cu doped CD spherical shell target is imploded around an inserted hollow Au cone by a six beam 600J, 1ns laser to a peak density of 4gcm{sup -3} and a diameter of 100 {micro}m. A 10 ps, 20TW laser pulse is focused into the cone at the time of peak compression. The flux of high-energy electrons through the imploded material is determined from the yield of Cu K{alpha} fluorescence by comparison with a Monte Carlo model and is estimated to carry 15% of the laser energy. Collisional and Ohmic heating are modeled. An electron spectrometer shows significantly greater reduction of the transmitted electron flux than is due to binary collisions and Ohmic potential. Enhanced scattering by instability-induced magnetic fields is suggested.

  19. Laser propagation and channel formation in laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Young, P. E.

    1996-05-01

    The understanding of laser beam propagation through underdense plasmas is of vital importance to inertial confinement fusion schemes, as well as being a fundamental physics issue. Formation of plasma channels has numerous applications including table-top x-ray lasers and laser-plasma induced particle accelerators. The fast ignitor concept (M. Tabak et al., Phys. Plasmas 1), 1626 (1994)., for example, requires the formation of an evacuated channel through a large, underdense plasma. Scaled experiments (P.E. Young et al., Phys. Rev. Lett. 63), 2812 (1989). (S. Wilks et al., Phys. Rev. Lett. 73), 2994 (1994). (P.E. Young et al, Phys. Plasmas 2), 2825 (1995). have shown that the axial extent of a channel formed by a 100 ps pulse is limited by the onset of the filamentation instability (P.E. Young et al., Phys. Rev. Lett. 61), 2336 (1988).. We have obtained quantitative comparison between filamentation theory and experiment (P.E. Young, Phys. Plasmas 2), 2815 (1995).. More recent experiments (P.E. Young et al., Phys. Rev. Lett. 75), 1082 (1995). have shown that by increasing the length of the channel-forming pulse, the filamentation instability is overcome and the channel forms at higher densities. This result has important implications for the fast ignitor design and the understanding of time-dependent beam dynamics. In addition, we will present measurements of ion energies ejected by the ponderomotive force which is a measurement of the peak laser intensity in the plasma; the ion energies indicate filamented laser intensities above 1.5× 10^17 W/cm^2. * Work performed under the auspices of the U.S. Dept. of Energy by Lawrence Livermore National Laboratory under contract W-7405-ENG-48. ^ In collaboration with S. Wilks, J. Hammer, W. Kruer, M. Foord, G. Guethlein, and M. Tabak.

  20. Charged Particle Acceleration by Lasers in Plasmas

    SciTech Connect

    Liu, C. S.; Tripathi, V. K.

    2007-07-11

    Several physical processes of laser electron acceleration in plasmas are revisited. A laser beam can drive plasma waves which in turn can accelerate resonant electrons. If these plasma waves can reach amplitude limited only by wave breaking alone, then the corresponding accelerating gradient in the plasma wave is of the order of electron rest mass energy per plasma skin depth, typically about GEV per centimeter. This is several orders of magnitudes higher than the conventional RF field gradient, giving rise to the possibility of compact accelerators needed for high energy physics research as well as medical and other applications. The chirped short pulse laser, with intensity exceeding the threshold for relativistic self focusing, can generate ion bubble in its wake by expelling electrons. The electrons at the bubble boundary, surge toward the stagnation point and pile up there. As the pile acquires a critical size, these electrons are injected into the bubble and accelerated by the combined fields of ion space charge and the plasma wave to Gev in energy. Most remarkably these electrons are bunched in phase space while being accelerated to high energy, resulting in near mono-energetic electron beam of high beam quality, with narrow energy spread. We review also other processes related to laser electron acceleration, such as acceleration in plasma wave assisted by ponderomotive force and betatron acceleration.

  1. Measurements of laser-induced plasma temperature field in deep penetration laser welding

    NASA Astrophysics Data System (ADS)

    Chen, Genyu; Zhang, Mingjun; Zhao, Zhi; Zhang, Yi; Li, Shichun

    2013-02-01

    Laser-induced plasma in deep penetration laser welding is located inside or outside the keyhole, namely, keyhole plasma or plasma plume, respectively. The emergence of laser-induced plasma in laser welding reveals important information of the welding technological process. Generally, electron temperature and electron density are two important characteristic parameters of plasma. In this paper, spectroscopic measurements of electron temperature and electron density of the keyhole plasma and plasma plume in deep penetration laser welding conditions were carried out. To receive spectra from several points separately and simultaneously, an Optical Multi-channel Analyser (OMA) was developed. On the assumption that the plasma was in local thermal equilibrium, the temperature was calculated with the spectral relative intensity method. The spectra collected were processed with Abel inversion method to obtain the temperature fields of keyhole plasma and plasma plume.

  2. PAPERS DEVOTED TO THE MEMORY OF ACADEMICIAN A M PROKHOROV: Dynamics of plasma production and development in gases and transparent solids irradiated by high-intensity, tightly focused picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Garnov, Sergei V.; Konov, Vitalii I.; Malyutin, A. A.; Tsar'kova, O. G.; Yatskovskii, I. S.; Dausinger, F.

    2003-09-01

    The results of experimental studies of the dynamics of formation and development of a laser plasma produced in microvolumes of gases (air) and transparent solids (fused silica) by high-intensity [I⋍(1-2)×1014 W cm-2], ~22-ps, 539-nm laser pulses tightly focused in a region of diameter 4 μm are presented. The spatiotemporal distributions of the refractive index and the electron density are studied by the interferometric method with a spatial resolution of ~1.6 μm and a temporal resolution of ~3 ps directly during the action of excitation picosecond laser pulses. An almost complete ionisation of the initial gas was shown to occur even in the initial stage of air plasma formation, within a few picoseconds after plasma production. The irradiation of solid transparent dielectrics (fused silica) by picosecond laser pulses resulted in a reversible production of a plasma with an electron density above 1020 cm-3, which did not cause the damage of dielectrics.

  3. Intense excitation source of blue-green laser

    NASA Astrophysics Data System (ADS)

    Han, K. S.

    1985-10-01

    An intense and efficient excitation source for blue-green lasers useful for the space-based satellite laser applications, underwater strategic communication, and measurement of ocean bottom profile is being developed. The source in use, hypocycloidal pinch plasma (HCP), and a newly designed dense-plasma focus (DPF) can produce intense UV photons (200 to 300 nm) which match the absorption spectra of both near UV and blue green dye lasers (300 to 400 nm). During the current project period, the successful enhancement of blue-green laser output of both Coumarin 503 and LD490 dye through the spectral conversion of the HCP pumping light has been achieved with a converter dye BBQ. The factor of enhancement in the blue-green laser output energy of both Coumarin 503 and LD490 is almost 73%. This enhancement will definitely be helpful in achieving the direct high power blue-green laser (> 1 MW) with the existing blue green dye laser. On the other hand the dense-plasma focus (DPF) with new optical coupling has been designed and constructed. For the optimization of the DPF device as the UV pumping light source, the velocity of current sheath and the formation of plasma focus have been measured as function of argon or argon-deuterium fill gas pressure. Finally, the blue-green dye laser (LD490) has been pumped with the DPF device for preliminary tests. Experimental results with the DPF device show that the velocity of the current sheath follows the inverse relation of sq st. of pressure as expected. The blue-green dye (LD490) laser output exceeded 3.1 m at the best cavity tuning of laser system. This corresponds to 3J/1 cu cm laser energy extraction.

  4. Measurements of Energy Transport Patterns in Solid Density Laser Plasma Interactions at Intensities of 5x10{sup 20} W cm{sup -2}

    SciTech Connect

    Lancaster, K. L.; Clarke, R. J.; Green, J. S.; Murphy, C. D.; Norreys, P. A.; Hey, D. S.; Akli, K. U.; Davies, J. R.; Habara, H.; Nakatsutsumi, M.; Yabuuchi, T.; Key, M. H.; Kodama, R.; Krushelnick, K.; Simpson, P.; Zepf, M.; Stephens, R.; Stoeckl, C.

    2007-03-23

    K{sub {alpha}} x-ray emission, extreme ultraviolet emission, and plasma imaging techniques have been used to diagnose energy transport patterns in copper foils ranging in thickness from 5 to 75 {mu}m for intensities up to 5x10{sup 20} W cm{sup -2}. The K{sub {alpha}} emission and shadowgrams both indicate a larger divergence angle than that reported in the literature at lower intensities [R. Stephens et al., Phys. Rev. E 69, 066414 (2004)]. Foils 5 {mu}m thick show triple-humped plasma expansion patterns at the back and front surfaces. Hybrid code modeling shows that this can be attributed to an increase in the mean energy of the fast electrons emitted at large radii, which only have sufficient energy to form a plasma in such thin targets.

  5. Interaction of High Intensity Electromagnetic Waves with Plasmas

    SciTech Connect

    G. Shvets

    2008-10-03

    The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.

  6. Fast ignition relevant study of the flux of high intensity laser-generated electrons via a hollow cone into a laser-imploded plasma

    SciTech Connect

    Key, M. H.; Chen, M. H.; Hatchett, S. P.; Hill, J. M.; King, J. A.; MacKinnon, A. J.; Patel, P.; Phillips, T.; Snavely, R. A.; Town, R.; Adam, J. C.; Heron, A.; Akli, K. U.; Stephens, R.; Borghesi, M.; Romagnani, L.; Zepf, M.; Evans, R. G.; Freeman, R. R.; Habara, H.

    2008-02-15

    An integrated experiment relevant to fast ignition . A Cu-doped deuterated polymer spherical shell target with an inserted hollow Au cone is imploded by a six-beam 900-J, 1-ns laser. A 10-ps, 70-J laser pulse is focused into the cone at the time of peak compression. The flux of high-energy electrons through the imploded material is determined from the yield of Cu K{alpha} fluorescence by comparison with a Monte Carlo model. The electrons are estimated to carry about 15% of the laser energy. Collisional and Ohmic heating are modeled, and Ohmic effects are shown to be relatively unimportant. An electron spectrometer shows significantly greater reduction of the transmitted electron flux than is calculated in the model. Enhanced scattering by instability-induced magnetic fields is suggested. An extension of this fluor-based technique to measurement of coupling efficiency to the ignition hot spot in future larger-scale fast ignition experiments is outlined.

  7. Laser propagation in underdense plasmas: Scaling arguments

    SciTech Connect

    Garrison, J.C.

    1993-05-01

    The propagation of an intense laser beam in the underdense plasma is modelled by treating the plasma as a relativistic, zero temperature, charged fluid. For paraxial propagation and a sufficiently underdense plasma ({omega}p/{omega} {much_lt} 1), a multiple-scales technique is used to expand the exact equations in powers of the small parameter {theta} {equivalent_to} {omega}p/{omega}. The zeroth order equations are used in a critical examination of previous work on this problem, and to derive a scaling law for the threshold power required for cavitation.

  8. Laser pulse modulation instabilities in plasma channels

    PubMed

    Sprangle; Hafizi; Penano

    2000-04-01

    In this paper the modulational instability associated with propagation of intense laser pulses in a partially stripped, preformed plasma channel is analyzed. In general, modulation instabilities are caused by the interplay between (anomalous) group velocity dispersion and self-phase modulation. The analysis is based on a systematic approach that includes finite-perturbation-length effects, nonlinearities, group velocity dispersion, and transverse effects. To properly include the radial variation of both the laser field and plasma channel, the source-dependent expansion method for analyzing the wave equation is employed. Matched equilibria for a laser beam propagating in a plasma channel are obtained and analyzed. Modulation of a uniform (matched) laser beam equilibrium in a plasma channel leads to a coupled pair of differential equations for the perturbed spot size and laser field amplitude. A general dispersion relation is derived and solved. Surface plots of the spatial growth rate as a function of laser beam power and the modulation wave number are presented. PMID:11088236

  9. Generation of Ultra-high Intensity Laser Pulses

    SciTech Connect

    N.J. Fisch; V.M. Malkin

    2003-06-10

    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{sup 25} W/cm{sup 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.

  10. Plasma effects on harmonic spectra generated from moderately relativistic laser-plasma interactions.

    PubMed

    Ondarza-Rovira, R; Boyd, T J M

    2012-08-01

    When intense p-polarized laser light is incident on a plasma with an electron density many times the critical density, the flux of fast electrons created by Brunel absorption excites plasma oscillations. These oscillations may in turn affect the spectrum of high harmonics by modulating the spectrum at the plasma frequency, ω(p), and by coupling to the radiation field through the steep density gradient at the plasma-vacuum interface, so generating plasma line emission (PLE) at ω(p) and harmonics of ω(p). Both aspects depend sensitively on a range of plasma and laser pulse parameters, including the initial electron density, the density profile at the plasma-vacuum interface, and the intensity, pulse shape, and pulse length of the incident laser light. These various dependences have been characterised for moderately relativistic laser-plasma interactions by means of a series of particle-in-cell (PIC) simulations. PMID:23005869

  11. Density profile of a line plasma generated by laser ablation for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Kim, J.; Hwangbo, Y.; Ryu, W.-J.; Kim, K. N.; Park, S. H.

    2016-03-01

    An elongated line plasma generated by a laser ablation of an aluminum target was investigated, which can be used in the laser wakefield acceleration (LWFA) by employing ultra-intense laser pulse through the longitudinal direction of the plasma. To generate a uniform and long plasma channel along the propagation of ultra-intense laser pulse (main pulse), a cylindrical lens combined with a biprism was used to shape the intensity of a ns Nd:YAG laser (pre-pulse) on the Al target. A uniformity of laser intensity can be manipulated by changing the distance between the biprism and the target. The density profile of the plasma generated by laser ablation was measured using two interferometers, indicating that a 3-mm long uniform line plasma with a density of 6 × 1017 cm-3 could be generated. The density with main pulse was also measured and the results indicated that the density would increase further due to additional ionization of the plasma by the main ultra-intense laser pulse. The resulting plasma density, which is a crucial parameter for the LWFA, can be controlled by the intensity of the pre-pulse, the time delay between the pre- and main pulse, and the distance of the main pulse from the target surface.

  12. Plasma channel guided laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron Guy Robinson

    2005-11-01

    High quality electron beams (several 109 electrons above 80 MeV energy with percent energy spread and low divergence) have been produced for the first time in a compact, high gradient, all-optical laser accelerator by extending the interaction distance using a pre-formed plasma density channel to guide the drive laser pulse. Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (wake) driven by the radiation pressure of an intense laser, have over the past decade demonstrated accelerating fields thousands of times greater than those achievable in conventional radio-frequency accelerators. This has spurred interest in them as compact next-generation sources of energetic electrons and radiation. To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance resulted in low-energy beams with 100 percent electron energy spread, which has limited potential applications. Optical guiding of relativistically intense (>1018 W/cm 2) laser pulses over distances greater than 10 diffraction lengths is demonstrated herein using plasma channels, which have a density minimum on the axis of propagation, formed by hydrodynamic shock. Laser modes with peak powers of up to 4 TW---twice the self-guiding threshold---were guided without aberration by tuning the plasma density profile. The transmitted optical spectrum showed that the pulse remained in the channel over the entire length, and no accelerated electrons were observed at these powers. Simulations indicated that a large plasma wave was driven by the 4 TW pulse, indicating a possible dark current free structure for a laser wakefield accelerator using controlled injection. The presence of a large plasma wave was verified by increasing laser power and observing electron acceleration. At a guided drive pulse power of 9 TW (500 mJ in 50 fs

  13. PLASMA WAKE EXCITATION BY LASERS OR PARTICLE BEAMS

    SciTech Connect

    Schroeder, Carl B.; Esarey, Eric; Benedetti, Carlo; Toth, Csaba; Geddes, Cameron; Leemans, Wim

    2011-04-01

    Plasma accelerators may be driven by the ponderomotive force of an intense laser or the space-charge force of a charged particle beam. Plasma wake excitation driven by lasers or particle beams is examined, and the implications of the different physical excitation mechanisms for accelerator design are discussed. Plasma-based accelerators have attracted considerable attention owing to the ultrahigh field gradients sustainable in a plasma wave, enabling compact accelerators. These relativistic plasma waves are excited by displacing electrons in a neutral plasma. Two basic mechanisms for excitation of plasma waves are actively being researched: (i) excitation by the nonlinear ponderomotive force (radiation pressure) of an intense laser or (ii) excitation by the space-charge force of a dense charged particle beam. There has been significant recent experimental success using lasers and particle beam drivers for plasma acceleration. In particular, for laser-plasma accelerators (LPAs), the demonstration at LBNL in 2006 of high-quality, 1 GeV electron beams produced in approximately 3 cm plasma using a 40 TW laser. In 2007, for beam-driven plasma accelerators, or plasma-wakefield accelerators (PWFAs), the energy doubling over a meter to 42 GeV of a fraction of beam electrons on the tail of an electron beam by the plasma wave excited by the head was demonstrated at SLAC. These experimental successes have resulted in further interest in the development of plasma-based acceleration as a basis for a linear collider, and preliminary collider designs using laser drivers and beam drivers are being developed. The different physical mechanisms of plasma wave excitation, as well as the typical characteristics of the drivers, have implications for accelerator design. In the following, we identify the similarities and differences between wave excitation by lasers and particle beams. The field structure of the plasma wave driven by lasers or particle beams is discussed, as well as the

  14. Temperature measurement of laser-induced plasmas from the intensity ratio of two lines emitted from different elements with the same ionization degree.

    PubMed

    Hou, Huaming; Tian, Ye; Lu, Yuan; Li, Ying; Zheng, Ronger

    2014-01-01

    A new laser induced plasma temperature measuring method with two lines emitted from different elements with the same ionization degree is proposed, assuming local thermodynamic equilibrium condition of the plasma. The influence of measurement error on deduced temperature accuracy was simulated in theory. A solution containing Cu, K, and Cr elements was used as the sample. Plasma was generated at the surface of the solution, and time-resolved spectra were recorded. Two atomic lines, Cu I 324 nm and K I 766 nm, were used to determine the plasma temperature with the proposed method. Four atomic lines and two ionic lines of Cr were selected to deduce plasma temperature with the Saha-Boltzmann plot method for comparison. The temperatures deduced from the two different methods showed similar behavior as a function of time. The results suggested that this method can be useful in cases where only very few lines from a single element are available in the spectrum and Boltzmann or Saha-Boltzmann plots cannot be built. PMID:25226263

  15. Direct heating of compressed core by ultra-intense laser

    NASA Astrophysics Data System (ADS)

    Sunahara, A.; Johzaki, T.; Sakagami, H.; Nagatomo, H.; Mima, K.; Abe, Y.; Arikawa, Y.; Fujioka, S.; Shiraga, H.; Azechi, H.; Mori, Y.; Sentoku, Y.; Kitagawa, Y.

    2016-05-01

    We propose a new scheme for heating an imploded core in the fast-ignition scheme. In this method, a heating laser irradiates an imploded core plasma directly. The accelerated fast-ions as well as fast-electrons heat the core. Two-dimensional particle in cell (PIC) simulation confirmed that carbon C6+ and deuteron D+ ions were accelerated as well as fast electrons when ultra-intense laser irradiates the CD plasma. In order to estimate the temperature scaling of the heated core in this scheme, we conducted transport simulations in the one-dimensional conical geometry. Our results show that 5 keV of ignition temperature can be achieved at the intensity of 1021 W/cm2, and 1.5 ps pulse for the compressed CD plasma with 10g/cm3 density.

  16. Physics of laser-driven plasma-based electron accelerators

    SciTech Connect

    Esarey, E.; Schroeder, C. B.; Leemans, W. P.

    2009-07-15

    Laser-driven plasma-based accelerators, which are capable of supporting fields in excess of 100 GV/m, are reviewed. This includes the laser wakefield accelerator, the plasma beat wave accelerator, the self-modulated laser wakefield accelerator, plasma waves driven by multiple laser pulses, and highly nonlinear regimes. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse diffraction, electron dephasing, laser pulse energy depletion, and beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Experiments demonstrating key physics, such as the production of high-quality electron bunches at energies of 0.1-1 GeV, are summarized.

  17. Laser-PlasmaWakefield Acceleration with Higher Order Laser Modes

    SciTech Connect

    Geddes, C.G.R.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Mullowney, P.; Paul, K.; Cary, J.R.; Leemans, W.P.

    2010-06-01

    Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications.

  18. Laser-Plasma Wakefield Acceleration with Higher Order Laser Modes

    SciTech Connect

    Geddes, C. G. R.; Schroeder, C. B.; Cormier-Michel, E.; Mullowney, P.; Paul, K.; Esarey, E.; Cary, J. R.; Leemans, W. P.

    2010-11-04

    Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications.

  19. QED effects and radiation generation in relativistic laser plasma

    NASA Astrophysics Data System (ADS)

    Kostyukov, I. Yu.; Nerush, E. N.; Bashmakov, V. F.

    2011-06-01

    The radiative and quantum effects in laser plasmas are discussed. The self-consistent numerical model based on particle-in-cell and Monte-Carlo methods are developed. First we analyze the spectra of Compton backscattered photons and betatron radiation in the classical and quantum regimes. Then we address an interaction between intense laser pulse and relativistic electron beam. Finally we discuss the electron-positron pair plasma production in extremely-intense laser field. It is shown that such plasma can be an efficient source of energetic gammaquanta.

  20. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Divergence and intensity of amplified spontaneous emission coupled out of an active medium by a distributed refraction method

    NASA Astrophysics Data System (ADS)

    Ladagin, V. K.; Starikov, F. A.; Urlin, V. D.

    1993-05-01

    The dynamics of the radiation in the near and far zones has been studied analytically and numerically for the case in which nonlinearly amplified spontaneous x radiation is coupled out of a plasma active medium by a distributed refraction method. The divergence Δθ of the amplified noise falls off exponentially with increasing length of the active medium, z. When z is equal to five or six refraction lengths, Δθ is an order of magnitude smaller than the geometric divergence. The maximum radiation flux qm is at the refraction angle and increases exponentially with increasing z. The rate of increase of qm and the rate of decrease of Δθ may be lowered by diffraction. In the case of a linear amplification of the noise, qm also corresponds to the refraction angle and may be much greater than the paraxial flux density. However, the advantage over coupling out the end in the case of a homogeneous active medium is achieved at a substantial cost in power.

  1. Laser Assisted Plasma Arc Welding

    SciTech Connect

    FUERSCHBACH,PHILLIP W.

    1999-10-05

    Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  2. Effects of laser polarization in the expansion of plasma waveguides

    NASA Astrophysics Data System (ADS)

    Lemos, N.; Grismayer, T.; Cardoso, L.; Geada, J.; Figueira, G.; Dias, J. M.

    2013-10-01

    We experimentally demonstrate that a column of hydrogen plasma generated by an ultra-short (sub-picosecond), moderate intensity (˜1015-16 W.cm-2) laser, radially expands at a higher velocity when using a circularly polarized laser beam instead of a linearly polarized beam. Interferometry shows that after 1 ns there is a clear shock structure formed, that can be approximated to a cylindrical blast wave. The shock velocity was measured for plasmas created with linearly and circularly polarized laser beams, indicating an approximately 20% higher velocity for plasmas generated with a circularly polarized laser beam, thus implying a higher plasma electron temperature. The heating mechanism was determined to be the Above Threshold Ionization effect. The calculated electrum energy spectrum for a circularly polarized laser beam was broader when compared to the one generated by a linearly polarized laser beam, leading to a higher plasma temperature.

  3. Effects of laser polarization in the expansion of plasma waveguides

    SciTech Connect

    Lemos, N.; Grismayer, T.; Cardoso, L.; Geada, J.; Figueira, G.; Dias, J. M.

    2013-10-15

    We experimentally demonstrate that a column of hydrogen plasma generated by an ultra-short (sub-picosecond), moderate intensity (∼10{sup 15–16} W.cm{sup –2}) laser, radially expands at a higher velocity when using a circularly polarized laser beam instead of a linearly polarized beam. Interferometry shows that after 1 ns there is a clear shock structure formed, that can be approximated to a cylindrical blast wave. The shock velocity was measured for plasmas created with linearly and circularly polarized laser beams, indicating an approximately 20% higher velocity for plasmas generated with a circularly polarized laser beam, thus implying a higher plasma electron temperature. The heating mechanism was determined to be the Above Threshold Ionization effect. The calculated electrum energy spectrum for a circularly polarized laser beam was broader when compared to the one generated by a linearly polarized laser beam, leading to a higher plasma temperature.

  4. Plasma detector for TEA CO2 laser pulse measurement

    NASA Astrophysics Data System (ADS)

    Ichikawa, Y.; Yamanaka, M.; Mitsuishi, A.; Fujita, S.; Yamanaka, T.; Yamanaka, C.; Tsunawaki, Y.; Iwasaki, T.; Takai, M.

    1983-10-01

    Laser-pulse evolution can be detected by measuring the emf generated by fast electrons in a laser-produced plasma when the laser radiation is focused onto a solid metal target in a vacuum. Using this phenomenon a 'plasma detector' is constructed, and its characteristics for the TEA CO2 laser radiation of intensity 10 to the 9th to 10 to the 10th W/sq cm are investigated experimentally. The plasma detector operates at room temperature and is strong against laser damages. For the evacuated plasma detector down to 0.1 torr, a maximum output voltage of 90 V and a rise time shorter than 1 ns are observed. The plasma detector, therefore, can be used as a power monitor for laser pulses and as a trigger voltage source.

  5. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Boundary instability of an erosion laser plasma expanding into a background gas

    NASA Astrophysics Data System (ADS)

    Anisimov, V. N.; Grishina, V. G.; Derkach, O. N.; Kanevskiĭ, M. F.; Sebrant, A. Yu

    1993-12-01

    The stability of the contact region in the system consisting of an erosion plasma and a gas has been determined experimentally under conditions such that the length of the applied laser pulse is longer than the rise time of the instability, and the expansion of the erosion plume is accompanied by breakdown of the background gas. The evolution of perturbations of the plasma front following the introduction of initial perturbations with a fixed spatial period has been studied. It is possible to model the injection of plasma bunches into a low-pressure gas by studying the dynamics of the vaporization at moderate laser-light intensities, characteristic of technological applications.

  6. Intense laser ionization of transiently aligned CO

    SciTech Connect

    Pinkham, D.; Jones, R.R.

    2005-08-15

    We have measured the ionization rate for CO molecules exposed to intense 30 fsec 780 nm laser pulses as a function of the angle between the molecular and laser polarization axes. Nonionizing, 70 fsec laser pulses are used to coherently prepare the molecules, preferentially aligning them for the strong-field ionization experiments. We find a 2:1 ionization-rate ratio for molecules aligned parallel or perpendicular to the ionizing field.

  7. Prepulse effect on intense femtosecond laser pulse propagation in gas

    SciTech Connect

    Giulietti, Antonio; Tomassini, Paolo; Galimberti, Marco; Giulietti, Danilo; Gizzi, Leonida A.; Koester, Petra; Labate, Luca; Ceccotti, Tiberio; D'Oliveira, Pascal; Auguste, Thierry; Monot, Pascal; Martin, Philippe

    2006-09-15

    The propagation of an ultrashort laser pulse can be affected by the light reaching the medium before the pulse. This can cause a serious drawback to possible applications. The propagation in He of an intense 60-fs pulse delivered by a Ti:sapphire laser in the chirped pulse amplification (CPA) mode has been investigated in conditions of interest for laser-plasma acceleration of electrons. The effects of both nanosecond amplified spontaneous emission and picosecond pedestals have been clearly identified. There is evidence that such effects are basically of refractive nature and that they are not detrimental for the propagation of a CPA pulse focused to moderately relativistic intensity. The observations are fully consistent with numerical simulations and can contribute to the search of a stable regime for laser acceleration.

  8. Ion beam control in laser plasma interaction

    NASA Astrophysics Data System (ADS)

    Kawata, S.; Izumiyama, T.; Sato, D.; Nagashima, T.; Takano, M.; Barada, D.; Gu, Y. J.; Ma, Y. Y.; Kong, Q.; Wang, P. X.; Wang, W. M.

    2016-03-01

    By a two-stage successive acceleration in laser ion acceleration, our 2.5-dimensional particle-in-cell simulations demonstrate a remarkable increase in ion energy by a few hundreds of MeV; the maximum proton energy reaches about 250MeV. The ions are accelerated by the inductive continuous post-acceleration in a laser plasma interaction together with the target normal sheath acceleration and the breakout afterburner mechanism. An intense short-pulse laser generates a strong current by high-energy electrons accelerated, when an intense short- pulse laser illuminates a plasma target. The strong electric current creates a strong magnetic field along the high-energy electron current in the plasma. During the increase phase in the magnetic field strength, the moving longitudinal inductive electric field is induced by the Faraday law, and accelerates the forward-moving ions continously. The multi-stage acceleration provides a unique controllability in the ion energy and its quality.

  9. Kinetic Approach for Laser-Induced Plasmas

    SciTech Connect

    Omar, Banaz; Rethfeld, Baerbel

    2008-10-22

    Non-equilibrium distribution functions of electron gas and phonon gas excited with ultrashort intense laser pulses are calculated for laser-induced plasmas occurring in solids. The excitation during femtosecond irradiation and the subsequent thermalization of the free electrons, as well as the dynamics of phonons are described by kinetic equations. The microscopic collision processes, such as absorption by inverse bremsstrahlung, electron-electron collisions, and electron-phonon interactions are considered by complete Boltzmann collision integrals. We apply our kinetic approach for gold by taking s-band electron into account and compare it with the case of excitation of d-band electrons.

  10. Intense excitation source of blue-green laser

    NASA Astrophysics Data System (ADS)

    Han, Kwang S.

    1986-10-01

    An intense and efficient source for blue green laser useful for the space-based satellite laser applications, underwater strategic communication, and measurement of ocean bottom profile is being developed. The source in use, the hypocycloidal pinch plasma (HCP), and the dense plasma focus (DPF) can produce intense uv photons (200 to 400nm) which match the absorption spectra of both near UV and blue green dye lasers (300 to 400nm). As a result of optimization of the DPF light at 355nm, the blue green dye (LD490) laser output exceeding 4mJ was obtained at the best cavity tunning of the laser system. With the HCP pumped system a significant enhancement of the blue green laser outputs with dye LD490 and coumarin 503 has been achieved through the spectrum conversion of the pumping light by mixing a converter dye BBQ. The maximum increase of laser output with the dye mixture of LD490+BBQ and coumarin 503+BBQ was greater than 80%. In addition, the untunned near UV lasers were also obtained. The near UV laser output energy of P-terphenyl dye was 0.5mJ at lambda sub C=337nm with the bandwidth of 3n m for the pulse duration of 0.2us. Another near UV laser output energy obtained with BBQ dye was 25 mJ at lambda sub C=383nm with the bandwidth of 3nm for the pulse duration of 0.2us. Another near UV laser output energy obtained with BBQ dye was 25 mJ at lambda sub C=383nm with the bandwidth of 3nm for the pulse duration of 0.2microsec.

  11. Energy distribution of fast electrons accelerated by high intensity laser pulse depending on laser pulse duration

    NASA Astrophysics Data System (ADS)

    Kojima, Sadaoki; Arikawa, Yasunobu; Morace, Alessio; Hata, Masayasu; Nagatomo, Hideo; Ozaki, Tetsuo; Sakata, Shohei; Lee, Seung Ho; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Johzaki, Tomoyuki; Sunahara, Atsushi; Sakagami, Hitoshi; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke; Azechi, Hiroshi

    2016-05-01

    The dependence of high-energy electron generation on the pulse duration of a high intensity LFEX laser was experimentally investigated. The LFEX laser (λ = 1.054 and intensity = 2.5 – 3 x 1018 W/cm2) pulses were focused on a 1 mm3 gold cubic block after reducing the intensities of the foot pulse and pedestal by using a plasma mirror. The full width at half maximum (FWHM) duration of the intense laser pulse could be set to either 1.2 ps or 4 ps by temporally stacking four beams of the LFEX laser, for which the slope temperature of the high-energy electron distribution was 0.7 MeV and 1.4 MeV, respectively. The slope temperature increment cannot be explained without considering pulse duration effects on fast electron generation.

  12. Laser-plasma interactions for fast ignition

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. Laser Plasma instability reduction by coherence disruption

    SciTech Connect

    Kruer, W l; Amendt, P A; Meezan, N; Suter, L J

    2006-04-19

    The saturation levels of stimulated scattering of intense laser light in plasmas and techniques to reduce these levels are of great interest. A simple model is used to highlight the dependence of the reflectivity on the coherence length for the density fluctuations producing the scattering. Sometimes the coherence lengths can be determined nonlinearly. For NIF hohlraum plasmas, a reduction in the coherence lengths might be engineered in several ways. Finally, electron trapping in ion sound waves is briefly examined as a potentially important effect for the saturation of stimulated Brillouin scattering.

  14. Investigation of Nd:YAG laser produced tin droplet plasma expansion

    NASA Astrophysics Data System (ADS)

    Chen, Ziqi; Wang, Xinbing; Zuo, Duluo; Lu, Peixiang; Wang, Junwu

    2016-05-01

    The present work reports an investigation of plasma expansion produced by Nd:YAG laser irradiating tin droplets. An intensified charged coupled device camera was used to record the plasma plume images, and the temporal evolution of the plasma plume was studied at various laser intensities. Our results demonstrate that the shape of the plasma plume develops from an approximate circle to an ellipse. The temporal evolutions of plasma boundary and plasma centroid were calculated by the secondary moment of plasma image intensity. The angle distributions of the plasma expanding velocity were obtained; the results show that the plasma expanding velocity decreases with increase of the angle to the incoming laser axis. In addition, the eccentricity of the plasma ellipse decreases with time. Meanwhile, we found that the centroid of plasma clusters moves toward the laser incoming direction during the expansion stage and the velocity of this motion is independent of laser intensity.

  15. High-order harmonics from laser-irradiated plasma surfaces

    SciTech Connect

    Teubner, U.; Gibbon, P.

    2009-04-15

    The investigation of high-order harmonic generation (HHG) of femtosecond laser pulses by means of laser-produced plasmas is surveyed. This kind of harmonic generation is an alternative to the HHG in gases and shows significantly higher conversion efficiency. Furthermore, with plasma targets there is no limitation on applicable laser intensity and thus the generated harmonics can be much more intense. In principle, harmonic light may also be generated at relativistic laser intensity, in which case their harmonic intensities may even exceed that of the focused laser pulse by many orders of magnitude. This phenomenon presents new opportunities for applications such as nonlinear optics in the extreme ultraviolet region, photoelectron spectroscopy, and opacity measurements of high-density matter with high temporal and spatial resolution. On the other hand, HHG is strongly influenced by the laser-plasma interaction itself. In particular, recent results show a strong correlation with high-energy electrons generated during the interaction process. The harmonics are a promising tool for obtaining information not only on plasma parameters such as the local electron density, but also on the presence of large electric and magnetic fields, plasma waves, and the (electron) transport inside the target. This paper reviews the theoretical and experimental progress on HHG via laser-plasma interactions and discusses the prospects for applying HHG as a short-wavelength, coherent optical tool.

  16. Laser Initiated, RF Sustained Air Plasmas

    NASA Astrophysics Data System (ADS)

    Scharer, John; Giar, Ryan; Hummelt, Jason; Way, Jesse

    2009-11-01

    Measurements and analysis of air breakdown processes by focusing 193 nm, 260 mJ, 10 MW high power UV laser radiation to 18 cm and 1.3 cm zones are examined. Quantum resonant multi-photon (REMPI) and collisional cascade ionization processes affect the breakdown and plasma formation. Our spectroscopic measurements show that REMPI (2+1) processes on nitrogen play a substantial role at lower pressures due to the high photon energy (6.4 eV). The REMPI process yields high density air plasmas (5 x 10^16/cc) for the 18 cm focus with the laser flux three orders of magnitude below the classical breakdown threshold intensity. Measurements of the f = 1.3 cm core laser plasma density (8x10^17/cc) and electron temperature decay via two color laser interferometry are made. The 18 cm focal length lens and its ionizing shock wave front are utilized to produce air seed plasma to initiate a large volume (500 cc) RF sustainment discharge coupled by means of a 6 cm diameter helical coil at up to 10 kW power levels.

  17. Suppression of parasitic noise by strong Langmuir wave damping in quasitransient regimes of backward Raman amplification of intense laser pulses in plasmas.

    NASA Astrophysics Data System (ADS)

    Malkin, Vladimir; Fisch, Nathaniel

    2009-11-01

    Currently built powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulsed, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can suppress deleterious instabilities of BRA seeded by the thermal noise. This shows that it may be feasible to observe x-ray BRA for the first time soon.

  18. Enhanced energy localization and heating in high contrast ultra-intense laser produced plasmas via novel conical micro-target design

    NASA Astrophysics Data System (ADS)

    Rassuchine, J.; d'Humières, E.; Baton, S.; Fuchs, J.; Guillou, P.; Koenig, M.; Kodama, R.; Nakatsutsumi, M.; Norimatsu, T.; Batani, D.; Morace, A.; Redaelli, R.; Gremillet, L.; Rousseaux, C.; Dorchies, F.; Fourment, C.; Santos, J. J.; Adams, J.; Korgan, G.; Malekos, S.; Sentoku, Y.; Cowan, T. E.

    2008-05-01

    We report new experiments showing enhanced laser-target coupling and energy localization using nano-fabricated micro-conical Cu targets performed at the 100 TW CPA laser at LULI. A comparison was made between 1ω (λ = 1.057 μm, I = 1019 W/cm2) and 2ω (λ = 0.53 μm, I = 4-8 × 1018 W/cm2) irradiation to determine the effect of ASE induced preformed plasma filling the cone, using as principal diagnostics 2D Cu Kα imaging (transverse and rear-side), and high-resolution conical crystal spectroscopy of the Cu Kα bands. The 2ω irradiation exhibits laser absorption up to 50 μm deeper into the cone tip (versus at 1 ω), with a commensurately smaller Kα emission zone. Spectroscopy indicates a higher average charge state for the Cu emission at 2ω, with some shots exhibiting up to at least O-like emission. We deduce that micro-cone targets have similar performance in terms of material heating as a 50 μm diameter reduced mass target, despite a 900-fold larger mass. The observed enhancement in energy localization and heating in the cone geometry is supported by 2D collisional PIC simulations which indicate the presence of self-generated resistive magnetic field structures (>= 10 MG) which confine the energetic electrons to the tip region

  19. Thomson scattering from laser plasmas

    SciTech Connect

    Moody, J D; Alley, W E; De Groot, J S; Estabrook, K G; Glenzer, S H; Hammer, J H; Jadaud, J P; MacGowan, B J; Rozmus, W; Suter, L J; Williams, E A

    1999-01-12

    Thomson scattering has recently been introduced as a fundamental diagnostic of plasma conditions and basic physical processes in dense, inertial confinement fusion plasmas. Experiments at the Nova laser facility [E. M. Campbell et al., Laser Part. Beams 9, 209 (1991)] have demonstrated accurate temporally and spatially resolved characterization of densities, electron temperatures, and average ionization levels by simultaneously observing Thomson scattered light from ion acoustic and electron plasma (Langmuir) fluctuations. In addition, observations of fast and slow ion acous- tic waves in two-ion species plasmas have also allowed an independent measurement of the ion temperature. These results have motivated the application of Thomson scattering in closed-geometry inertial confinement fusion hohlraums to benchmark integrated radiation-hydrodynamic modeling of fusion plasmas. For this purpose a high energy 4{omega} probe laser was implemented recently allowing ultraviolet Thomson scattering at various locations in high-density gas-filled hohlraum plasmas. In partic- ular, the observation of steep electron temperature gradients indicates that electron thermal transport is inhibited in these gas-filled hohlraums. Hydrodynamic calcula- tions which include an exact treatment of large-scale magnetic fields are in agreement with these findings. Moreover, the Thomson scattering data clearly indicate axial stagnation in these hohlraums by showing a fast rise of the ion temperature. Its timing is in good agreement with calculations indicating that the stagnating plasma will not deteriorate the implosion of the fusion capsules in ignition experiments.

  20. Laser-plasma-based linear collider using hollow plasma channels

    NASA Astrophysics Data System (ADS)

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2016-09-01

    A linear electron-positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

  1. Analytical model for interaction of short intense laser pulse with solid target

    SciTech Connect

    Luan, S. X.; Ma, G. J.; Yu, Wei; Yu, M. Y.; Zhang, Q. J.; Sheng, Z. M.; Murakami, M.

    2011-04-15

    A simple but comprehensive two-dimensional analytical model for the interaction of a normally incident short intense laser pulse with a solid-density plasma is proposed. Electron cavitation near the target surface by the laser ponderomotive force induces a strong local electrostatic charge-separation field. The cavitation makes possible mode conversion of the laser light into longitudinal electron oscillation at laser frequency, even for initial normal incidence of laser pulse. The intense charge-separation field in the cavity can significantly enhance the laser induced uxB electron oscillation at twice laser frequency to density levels even higher than that of the initial target.

  2. Laser-plasma ion beams-experiments towards charge transfer x-ray laser

    SciTech Connect

    Crespo Lopez-Urrutia, J.R.; Fill, E.E. ); Bruch, R. ); Schneider, D. )

    1993-06-05

    Laser plasmas produced at intensities of up to 10[sup 14] W/cm[sup 2] expand towards a secondary target a few millimeters away. The intense x-ray emission during the interaction plasma-target was recorded spectrally, spatially and time-resolved. A number of processes, like recombination and charge transfer may account for this strong radiation. The implications of these experiments to the design of a charge transfer x-ray laser are discussed.

  3. Laser frequency modulation with electron plasma

    NASA Technical Reports Server (NTRS)

    Burgess, T. J.; Latorre, V. R.

    1972-01-01

    When laser beam passes through electron plasma its frequency shifts by amount proportional to plasma density. This density varies with modulating signal resulting in corresponding modulation of laser beam frequency. Necessary apparatus is relatively inexpensive since crystals are not required.

  4. Plasma Channel Diagnostic Based on Laser Centroid Oscillations

    SciTech Connect

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Osterhoff, Jens; Shiraishi, Satomi; Schroeder, Carl; Geddes, Cameron; Toth, Csaba; Esarey, Eric; Leemans, Wim

    2010-09-09

    A technique has been developed for measuring the properties of discharge-based plasma channels by monitoring the centroid location of a laser beam exiting the channel as a function of input alignment offset between the laser and the channel. The centroid position of low-intensity (<10{sup 14}Wcm{sup -2}) laser pulses focused at the input of a hydrogen-filled capillary discharge waveguide was scanned and the exit positions recorded to determine the channel shape and depth with an accuracy of a few %. In addition, accurate alignment of the laser beam through the plasma channel can be provided by minimizing laser centroid motion at the channel exit as the channel depth is scanned either by scanning the plasma density or the discharge timing. The improvement in alignment accuracy provided by this technique will be crucial for minimizing electron beam pointing errors in laser plasma accelerators.

  5. Revealing discriminating power of the elements in edible sea salts: Line-intensity correlation analysis from laser-induced plasma emission spectra

    NASA Astrophysics Data System (ADS)

    Lee, Yonghoon; Ham, Kyung-Sik; Han, Song-Hee; Yoo, Jonghyun; Jeong, Sungho

    2014-11-01

    We have investigated the discriminating power of the elements in edible sea salts using Laser-Induced Breakdown Spectroscopy (LIBS). For the ten different sea salts from South Korea, China, Japan, France, Mexico and New Zealand, LIBS spectra were recorded in the spectral range between 190 and 1040 nm, identifying the presence of Na, Cl, K, Ca, Mg, Li, Sr, Al, Si, Ti, Fe, C, O, N, and H. Intensity correlation analysis of the observed emission lines provided a valuable insight into the discriminating power of the different elements in the sea salts. The correlation analysis suggests that the elements with independent discrimination power can be categorized into three groups; those that represent dissolved ions in seawater (K, Li, and Mg), those that are associated with calcified particles (Ca and Sr), and those that are present in soils contained in the sea salts (Al, Si, Ti, and Fe). Classification models using a few emission lines selected based on the results from intensity correlation analysis and full broadband LIBS spectra were developed based on Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) and their performances were compared. Our results indicate that effective combination of a few emission lines can provide a dependable model for discriminating the edible sea salts and the performance is not much degraded from that based on the full broadband spectra. This can be rationalized by the intensity correlation results.

  6. Measurement of the relaxation time of hot electrons in laser-solid interaction at relativistic laser intensities

    SciTech Connect

    Chen, H; Shepherd, R; Chung, H K; Dyer, G; Faenov, A; Fournier, K B; Hansen, S B; Hunter, J; Kemp, A; Pikuz, T; Ping, Y; Widmann, K; Wilks, S C; Beiersdorfer, P

    2006-08-22

    The authors have measured the relaxation time of hot electrons in short pulse laser-solid interactions using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. Employing laser intensities of 10{sup 17}, 10{sup 18}, and 10{sup 19} W/cm{sup 2}, they find increased laser coupling to hot electrons as the laser intensity becomes relativistic and thermalization of hot electrons at timescales on the order of 10 ps at all laser intensities. They propose a simple model based on collisional coupling and plasma expansion to describe the rapid relaxation of hot electrons. The agreement between the resulting K{sub {alpha}} time-history from this model with the experiments is best at highest laser intensity and less satisfactory at the two lower laser intensities.

  7. Interaction physics of multipicosecond Petawatt laser pulses with overdense plasma.

    PubMed

    Kemp, A J; Divol, L

    2012-11-01

    We study the interaction of intense petawatt laser pulses with overdense plasma over several picoseconds, using two- and three-dimensional kinetic particle simulations. Sustained irradiation with non-diffraction-limited pulses at relativistic intensities yields conditions that differ qualitatively from what is experimentally available today. Nonlinear saturation of laser-driven density perturbations at the target surface causes recurrent emissions of plasma, which stabilize the surface and keep absorption continuously high. This dynamics leads to the acceleration of three distinct groups of electrons up to energies many times the laser ponderomotive potential. We discuss their energy distribution for applications like the fast-ignition approach to inertial confinement fusion. PMID:23215393

  8. Zeeman effect induced by intense laser light.

    PubMed

    Stambulchik, E; Maron, Y

    2014-08-22

    We analyze spectral line shapes of hydrogenlike species subjected to fields of electromagnetic waves. It is shown that the magnetic component of an electromagnetic wave may significantly influence the spectra. In particular, the Zeeman effect induced by a visible or infrared light can be experimentally observed using present-day powerful lasers. In addition, the effect may be used for diagnostics of focused beam intensities achieved at existing and newly built laser facilities. PMID:25192094

  9. Detecting radiation reaction at moderate laser intensities.

    PubMed

    Heinzl, Thomas; Harvey, Chris; Ilderton, Anton; Marklund, Mattias; Bulanov, Stepan S; Rykovanov, Sergey; Schroeder, Carl B; Esarey, Eric; Leemans, Wim P

    2015-02-01

    We propose a new method of detecting radiation reaction effects in the motion of particles subjected to laser pulses of moderate intensity and long duration. The effect becomes sizable for particles that gain almost no energy through the interaction with the laser pulse. Hence, there are regions of parameter space in which radiation reaction is actually the dominant influence on charged particle motion. PMID:25768626

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

    DOEpatents

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

    1989-09-26

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

  11. Nuclear Powered Laser Driven Plasma Propulsion System

    NASA Astrophysics Data System (ADS)

    Kammash, T.

    A relativistic plasma thruster that could open up the solar system to near-term human exploration is presented. It is based on recent experimental and theoretical research, which show that ultrafast (very short pulse length) lasers can accelerate charged particles to relativistic speeds. In table top-type experiments charge-neutral proton beams containing more than 1014 particles with mean energies of tens of MeV's have been produced when high intensity lasers with femtosecond (10-15 s) pulse lengths are made to strike thin solid targets. When viewed from a propulsion standpoint such systems can produce specific impulses of several million seconds albeit at modest thrusts and require nuclear power systems to drive them. Several schemes are proposed to enhance the thrust and make these systems suitable for manned interplanetary missions. In this paper we set forth the physics principles that make relativistic plasma driven by ultrafast lasers particularly attractive for propulsion applications. We introduce the “Laser Accelerated Plasma Propulsion System” LAPPS, and demonstrate its potential propulsive capability by addressing an interstellar mission to the Oort Cloud, and a planetary mission to Mars. We show that the first can be carried out in a human's lifetime and the second in a matter of months. In both instances we identify the major technological problems that must be addressed if this system is to evolve into a leading contender among the advance propulsion concepts currently under consideration.

  12. Atoms, molecules and clusters in intense laser fields

    NASA Astrophysics Data System (ADS)

    Walters, Zachary B.

    Recent advances in the technology of intense, short laser pulses have opened the possibility of investigating processes in atoms, molecules and clusters in which the normal intramolecular forces between electrons and nuclei, and between different electrons, are rivaled in strength by interactions with the driving laser, or with a cluster plasma. Experiments using rescattered electrons offer a means of probing atomic and molecular processes on ultrafast timescales. This thesis extends techniques and concepts of atomic and molecular physics to describe physics in the strong field regime. This involves investigating how electron scattering from atoms and molecules is affected by the intense and time-varying electric field of the laser, the effect of such scattering on experimental observables, and the role of intramolecular structure on strong field processes. Also investigated is the evolution of van derWaals atomic clusters when subject to intense laser pulses in the VUV regime. Here processes such as photoionization, inverse bremsstrahlung heating, and collisional ionization and recombination are affected both by the non-hydrogenic nature of the relevant atomic potentials but also by the screening of these potentials by the cluster plasma.

  13. Lasers and Intense Pulsed Light Hidradenitis Suppurativa.

    PubMed

    Saunte, Ditte M; Lapins, Jan

    2016-01-01

    Lasers and intense pulsed light (IPL) treatment are useful for the treatment of hidradenitis suppurativa (HS). Carbon dioxide lasers are used for cutting or vaporization of the affected area. It is a effective therapy for the management of severe and recalcitrant HS with persistent sinus tract and scarring, and can be performed under local anesthesia. HS has a follicular pathogenesis. Lasers and IPL targeting the hair have been found useful in treating HS by reducing the numbers of hairs in areas with HS. The methods have few side effects, but the studies are preliminary and need to be repeated. PMID:26617364

  14. Microwave interferometry of laser induced air plasmas formed by short laser pulses

    SciTech Connect

    Jungwirth, P.W.

    1993-08-01

    Applications for the interaction of laser induced plasmas with electromagnetic probes requires time varying complex conductivity data for specific laser/electromagnetic probe geometries. Applications for this data include plasma switching (Q switching) and the study of ionization fronts. The plasmas were created in laboratory air by 100 ps laser pulses at a wavelength of 1 {mu}m. A long focal length lens focused the laser pulse into WR90 (X band) rectangular waveguide. Two different laser beam/electromagnetic probe geometries were investigated. For the longitudinal geometry, the laser pulse and the microwave counterpropagated inside the waveguide. For the transverse geometry, the laser created a plasma ``post`` inside the waveguide. The effects of the laser beam deliberately hitting the waveguide were also investigated. Each geometry exhibits its own characteristics. This research project focused on the longitudinal geometry. Since the laser beam intensity varies inside the waveguide, the charge distribution inside the waveguide also varies. A 10 GHz CW microwave probe traveled through the laser induced plasma. From the magnitude and phase of the microwave probe, a spatially integrated complex conductivity was calculated. No measurements of the temporal or spatial variation of the laser induced plasma were made. For the ``plasma post,`` the electron density is more uniform.

  15. Laser-plasma interactions relevant to Inertial Confinement Fusion

    SciTech Connect

    Wharton, K.B.

    1998-11-02

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

  16. An experimental study of laser supported hydrogen plasmas

    NASA Technical Reports Server (NTRS)

    Vanzandt, D. M.; Mccay, T. D.; Eskridge, R. H.

    1984-01-01

    The rudiments of a rocket thruster which receives its enthalpy from an energy source which is remotely beamed from a laser is described. An experimental study now partially complete is discussed which will eventually provide a detailed understanding of the physics for assessing the feasibility of using hydrogen plasmas for accepting and converting this energy to enthalpy. A plasma ignition scheme which uses a pulsed CO2 laser has been developed and the properties of the ignition spark documented, including breakdown intensities in hydrogen. A complete diagnostic system capable of determining plasma temperature and the plasma absorptivity for subsequent steady state absorption of a high power CO2 laser beam are developed and demonstrative use is discussed for the preliminary case study, a two atmosphere laser supported argon plasma.

  17. Radiative trapping in intense laser beams

    NASA Astrophysics Data System (ADS)

    Kirk, J. G.

    2016-08-01

    The dynamics of electrons in counter-propagating, circularly polarized laser beams are shown to exhibit attractors whose ability to trap particles depends on the ratio of the beam intensities and a single parameter describing radiation reaction. Analytical expressions are found for the underlying limit cycles and the parameter range in which they are stable. In high-intensity optical pulses, where radiation reaction strongly modifies the trajectories, the production of collimated gamma-rays and the initiation of non-linear cascades of electron–positron pairs can be optimized by a suitable choice of the intensity ratio.

  18. Protons acceleration in thin CH foils by ultra-intense femtosecond laser pulses

    SciTech Connect

    Kosarev, I. N.

    2015-03-15

    Interaction of femtosecond laser pulses with the intensities 10{sup 21}, 10{sup 22 }W/cm{sup 2} with CH plastic foils is studied in the framework of kinetic theory of laser plasma based on the construction of propagators (in classical limit) for electron and ion distribution functions in plasmas. The calculations have been performed for real densities and charges of plasma ions. Protons are accelerated both in the direction of laser pulse (up to 1 GeV) and in the opposite direction (more than 5 GeV). The mechanisms of forward acceleration are different for various intensities.

  19. Laser production and heating of plasma for MHD application

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1988-01-01

    Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO2 laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO2 laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO2 laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.

  20. Pushing the limits of plasma length in inertial-fusion laser-plasma interaction experiments.

    PubMed

    Froula, D H; Divol, L; London, R A; Michel, P; Berger, R L; Meezan, N B; Neumayer, P; Ross, J S; Wallace, R; Glenzer, S H

    2008-01-11

    We demonstrate laser beam propagation and low backscatter in laser produced hohlraum plasmas of ignition plasma length. At intensities I < 5 x 10(14) W cm(-2) greater than 80% of the energy in a blue (3 omega, 351 nm) laser is transmitted through a L=5-mm long, high-temperature (Te = 2.5 keV), high-density (ne = 5 x 10(20) cm(-3)) plasma. These experiments show that the backscatter scales exponentially with plasma length which is consistent with linear theory. The backscatter calculated by a new steady state 3D laser-plasma interaction code developed for large ignition plasmas is in good agreement with the measurements. PMID:18232778

  1. Pushing the limits of plasma length in inertial fusion laser-plasma interaction experiments

    SciTech Connect

    Froula, D; Divol, L; London, R; Michel, P; Berger, R L; Meezan, N; Neumayer, P; Ross, J; Wallace, R; Glenzer, S H

    2007-08-02

    We demonstrate laser beam propagation and low backscatter in laser produced hohlraum plasmas of ignition plasma length. At intensities I < 5 x 10{sup 14} W cm{sup -2} greater than 80% of the energy in a blue (3{omega}, 351 nm) laser is transmitted through a L=5-mm long, high-temperature (T{sub e} = 2.5 keV), high-density (n{sub e} = 5 x 10{sup 20} cm{sup -3}) plasma. These experiments show that the backscatter scales exponentially with plasma length which is consistent with linear theory. The backscatter calculated by a new steady state 3D laser-plasma interaction code developed for large ignition plasmas is in good agreement with the measurements.

  2. Spatiotemporal dynamics of Gaussian laser pulse in a multi ions plasma

    NASA Astrophysics Data System (ADS)

    Jafari Milani, M. R.

    2016-08-01

    Spatiotemporal evolutions of Gaussian laser pulse propagating through a plasma with multiple charged ions are studied, taking into account the ponderomotive nonlinearity. Coupled differential equations for beam width and pulse length parameters are established and numerically solved using paraxial ray approximation. In one-dimensional geometry, effects of laser and plasma parameters such as laser intensity, plasma density, and temperature on the longitudinal pulse compression and the laser intensity distribution are analyzed for plasmas with singly and doubly charged ions. The results demonstrate that self-compression occurs in a laser intensity range with a turning point intensity in which the self-compression process has its strongest extent. The results also show that the multiply ionized ions have different effect on the pulse compression above and below turning point intensity. Finally, three-dimensional geometry is used to analyze the simultaneous evolution of both self-focusing and self-compression of Gaussian laser pulse in such plasmas.

  3. Plasma neutralization models for intense ion beam transport in plasma

    SciTech Connect

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.; O'Rourke, Sean; Lee, Edward P.

    2003-05-01

    Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed based on the assumption of long charge bunches (l{sub b} >> r{sub b}). Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The analytical predictions for the degree of ion beam charge and current neutralization also agree well with the results of the numerical simulations. The model predicts very good charge neutralization (>99%) during quasi-steady-state propagation, provided the beam pulse duration {tau}{sub b} is much longer than the electron plasma period 2{pi}/{omega}{sub p}, where {omega}{sub p} = (4{pi}e{sup 2}n{sub p}/m){sup 1/2} is the electron plasma frequency, and n{sub p} is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. The analytical formulas derived in this paper can provide an important benchmark for numerical codes, and provide scaling relations for different beam and plasma parameters.

  4. Propagation of an ultra-short, intense laser in a relativistic fluid

    SciTech Connect

    Ritchie, A.B.; Decker, C.D.

    1997-12-31

    A Maxwell-relativistic fluid model is developed to describe the propagation of an ultrashort, intense laser pulse through an underdense plasma. The model makes use of numerically stabilizing fast Fourier transform (FFT) computational methods for both the Maxwell and fluid equations, and it is benchmarked against particle-in-cell (PIC) simulations. Strong fields generated in the wake of the laser are calculated, and the authors observe coherent wake-field radiation generated at harmonics of the plasma frequency due to nonlinearities in the laser-plasma interaction. For a plasma whose density is 10% of critical, the highest members of the plasma harmonic series begin to overlap with the first laser harmonic, suggesting that widely used multiple-scales-theory, by which the laser and plasma frequencies are assumed to be separable, ceases to be a useful approximation.

  5. Efficient energy absorption of intense ps-laser pulse into nanowire target

    NASA Astrophysics Data System (ADS)

    Habara, H.; Honda, S.; Katayama, M.; Sakagami, H.; Nagai, K.; Tanaka, K. A.

    2016-06-01

    The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. These features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.

  6. Modelling of relativistic laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Berwick, Stuart James

    In order to characterise the propagation and stability of linearly polarised laser pulses of arbitrary intensity interacting with underdense plasma, a one-dimensional, fully relativistic, covariant electron fluid model is derived. As a first step, the model is Lorentz transformed into a frame moving with the group velocity of the laser pulse. A linear instability analysis is undertaken which generates an infinite hierarchy of homogeneous mode-coupling equations describing the decay of the laser pump via stimulated Raman forward scattering (SRFS), stimulated Raman back scattering (SRBS) and the relativistic modulational instability (RMI). SRFS and RMI are seen to merge into a hybrid instability at high intensities (1>1018Wcm-2) and a 6-wave analysis (rather than the conventional 3 or 4-wave) is required to accurately predict growth. Next, an Eulerian fluid code is developed in order to evolve the full non- linear equations. The method of characteristics is used to integrate the electromagnetic wave equation and a predictor-corrector algorithm is used to integrate the equations of continuity and momentum. After testing, this code is used to simulate the propagation and stability of ultra-short (<200fs), 'table-top' and cos2 modulated laser pulses of relativistic intensities in underdense plasma. Comparison is made to the predictions of the dispersion relation and growth rates obtained in each case are reconciled. The spatiotemporal behaviour is discussed with reference to the results of a 3-wave WKB model of the interaction. The importance of seeding mechanisms, pulse shape and relativity on the evolution of the instabilities is also discussed.

  7. Nonlinear propagation of broadband intense electromagnetic waves in an electron-positron plasma

    SciTech Connect

    Marklund, M.; Eliasson, B.; Shukla, P. K.

    2006-08-15

    A kinetic equation describing the nonlinear evolution of intense electromagnetic pulses in electron-positron (e-p) plasmas is presented. The modulational instability is analyzed for a relativistically intense partially coherent pulse, and it is found that the modulational instability is inhibited by the spectral pulse broadening. A numerical study for the one-dimensional kinetic photon equation is presented. Computer simulations reveal a Fermi-Pasta-Ulam-type recurrence phenomenon for localized broadband pulses. The results should be of importance in understanding the nonlinear propagation of broadband intense electromagnetic pulses in e-p plasmas in laser-plasma systems as well as in astrophysical plasma settings.

  8. Laser ablated zirconium plasma: A source of neutral zirconium

    SciTech Connect

    Yadav, Dheerendra; Thareja, Raj K.

    2010-10-15

    The authors report spectroscopic investigations of laser produced zirconium (Zr) plasma at moderate laser fluence. At low laser fluence the neutral zirconium species are observed to dominate over the higher species of zirconium. Laser induced fluorescence technique is used to study the velocity distribution of ground state neutral zirconium species. Two-dimensional time-resolved density distributions of ground state zirconium is mapped using planner laser induced fluorescence imaging and total ablated mass of neutral zirconium atoms is estimated. Temporal and spatial evolutions of electron density and temperature are discussed by measuring Stark broadened profile and ratio of intensity of emission lines, respectively.

  9. EFFECT OF LASER LIGHT ON LASER PLASMAS: Laser plasma at low air pressure

    NASA Astrophysics Data System (ADS)

    Vas'kovskiĭ, Yu M.; Moiseev, V. N.; Rovinskiĭ, R. E.; Tsenina, I. S.

    1993-01-01

    The dynamic and optical characteristics of the laser plasma produced during the application of a CO2 laser pulse to a target have been studied as a function of the ambient air pressure. The changes in the surface roughness of the sample after bombardment were studied as a function of the air pressure. It is concluded from the results that a transition from an air plasma to an erosion plasma occurs at a residual air pressure on the order of 1 torr. The experiment data support the existing picture of the process by which a plasma is produced near the surface of a target in air by laser pulses.

  10. Self-mode-transition from laser wakefield accelerator to plasma wakefield accelerator of laser-driven plasma-based electron acceleration

    SciTech Connect

    Pae, K. H.; Choi, I. W.; Lee, J.

    2010-12-15

    Via three-dimensional particle-in-cell simulations, the self-mode-transition of a laser-driven electron acceleration from laser wakefield to plasma-wakefield acceleration is studied. In laser wakefield accelerator (LWFA) mode, an intense laser pulse creates a large amplitude wakefield resulting in high-energy electrons. Along with the laser pulse depletion, the electron bunch accelerated in the LWFA mode drives a plasma wakefield. Then, after the plasma wakefield accelerator mode is established, electrons are trapped and accelerated in the plasma wakefield. The mode transition process and the characteristics of the accelerated electron beam are presented.

  11. Transverse intensity transformation by laser amplifiers

    NASA Astrophysics Data System (ADS)

    Litvin, Igor A.; King, Gary; Collett, Oliver J. P.; Strauss, Hencharl J.

    2015-03-01

    Lasers beams with a specific intensity profile such as super-Gaussian, Airy or Dougnut-like are desirable in many applications such as laser materials processing, medicine and communications. We propose a new technique for laser beam shaping by amplifying a beam in an end-pumped bulk amplifier that is pumped with a beam that has a modified intensity profile. Advantages of this method are that it is relatively easy to implement, has the ability to reshape multimode beams and is naturally suited to high power/energy beams. Both three and four level gain materials can be used as amplifier media. However, a big advantage of using three level materials is their ability to attenuate of the seed beam, which enhances the contrast of the shaping. We first developed a numerical method to obtain the required pump intensity for an arbitrary beam transformation. This method was subsequently experimentally verified using a three level system. The output of a 2.07 μm seed laser was amplified in a Ho:YLF bulk amplifier which was being pumped by a 1.89 μm Tm:YLF laser which had roughly a TEM10 Hermit Gaussian intensity profile. The seed beam was amplified from 0.3 W to 0.55 W at the full pump power of 35 W. More importantly, the beam profile in one transverse direction was significantly shaped from Gaussian to roughly flat-top, as the model predicted. The concept has therefore been shown to be viable and can be used to optimise the beam profile for a wide range of applications.

  12. Characteristics of microwave plasma induced by lasers and sparks.

    PubMed

    Ikeda, Yuji; Tsuruoka, Ryoji

    2012-03-01

    Characteristics of the plasma light source of microwave (MW) plus laser-induced breakdown spectroscopy (LIBS) or spark-induced breakdown spectroscopy (SIBS) were studied. The plasma was initially generated by laser- or spark-induced breakdown as a plasma seed. A plasma volume was then grown and sustained by MWs in air. This MW plasma had a long lifetime, large volume, strong emission intensity, and high stability with time. These characteristics are suitable for applications in the molecular analysis of gases such as OH or N(2). Because the plasma properties did not depend on laser or spark plasma seeds, the resulting plasma was easily controllable by the input power and duration of the MWs. Therefore, a significant improvement was achieved in the spectral intensity and signal-to-noise ratio. For example, the peak intensity of the Pb spectra of LIBS increased 15 times, and that of SIBS increased 880 times without increases in their background noise. A MW-enhanced plasma light source could be used to make the total system smaller and cheaper than a conventional LIBS system, which would be useful for real-time and in situ analysis of gas molecules in, for example, food processing, medical applications, chemical exposure, and gas turbine or automobile air-to-fuel ratio and exhaust gas measurement. PMID:22410918

  13. Laser red shifting based characterization of wakefield excitation in a laser-plasma accelerator

    SciTech Connect

    Shiraishi, S.; Benedetti, C.; Gonsalves, A. J.; Nakamura, K.; Shaw, B. H.; Sokollik, T.; Tilborg, J. van; Geddes, C. G. R.; Schroeder, C. B.; Tóth, Cs.; Esarey, E.; Leemans, W. P.

    2013-06-15

    Optical spectra of a drive laser exiting a channel guided laser-plasma accelerator (LPA) are analyzed through experiments and simulations to infer the magnitude of the excited wakefields. The experiments are performed at sufficiently low intensity levels and plasma densities to avoid electron beam generation via self-trapping. Spectral redshifting of the laser light is studied as an indicator of the efficiency of laser energy transfer into the plasma through the generation of coherent plasma wakefields. Influences of input laser energy, plasma density, temporal and spatial laser profiles, and laser focal location in a plasma channel are analyzed. Energy transfer is found to be sensitive to details of laser pulse shape and focal location. The experimental conditions for these critical parameters are modeled and included in particle-in-cell simulations. Simulations reproduce the redshift of the laser within uncertainties of the experiments and produce an estimate of the wake amplitudes in the experiments as a function of amount of redshift. The results support the practical use of laser redshifting to quantify the longitudinally averaged accelerating field that a particle would experience in an LPA powered below the self-trapping limit.

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

    PubMed

    Lehmann, G; Spatschek, K H

    2016-06-01

    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. PMID:27314721

  15. Transient Plasma Photonic Crystals for High-Power Lasers

    NASA Astrophysics Data System (ADS)

    Lehmann, G.; Spatschek, K. H.

    2016-06-01

    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.

  16. Ion acceleration using high-contrast ultra-intense lasers

    NASA Astrophysics Data System (ADS)

    Fuchs, J.; Antici, P.; D'Humières, E.; Lefebvre, E.; Borghesi, M.; Brambrink, E.; Cecchetti, C.; Toncian, T.; Pépin, H.; Audebert, P.

    2006-06-01

    We have compared the acceleration of high-energy ions from the rear-surface of thin foils for various contrast conditions of the ultra-intense laser pulse irradiating the targets. The experiments were performed using the LULI 100 TW facility. We used Al targets of variable thicknesses and the laser pulse contrast ratio ahead of the main pulse was varied using either a fast Pockels cell or a single or double plasma mirror. The latter was installed at an intermediate field position, in between the focusing optics and the target, so that its effect was optimized. By improving with these two methods the laser pulse contrast, we have observed that we could significantly reduce the thickness of the target used for proton acceleration and at the same time increase both the cut-off energy of the accelerated protons and the energy conversion efficiency of the process.

  17. Kr photoionized plasma induced by intense extreme ultraviolet pulses

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.

    2016-04-01

    Irradiation of any gas with an intense EUV (extreme ultraviolet) radiation beam can result in creation of photoionized plasmas. The parameters of such plasmas can be significantly different when compared with those of the laser produced plasmas (LPP) or discharge plasmas. In this work, the photoionized plasmas were created in a krypton gas irradiated using an LPP EUV source operating at a 10 Hz repetition rate. The Kr gas was injected into the vacuum chamber synchronously with the EUV radiation pulses. The EUV beam was focused onto a Kr gas stream using an axisymmetrical ellipsoidal collector. The resulting low temperature Kr plasmas emitted electromagnetic radiation in the wide spectral range. The emission spectra were measured either in the EUV or an optical range. The EUV spectrum was dominated by emission lines originating from Kr III and Kr IV ions, and the UV/VIS spectra were composed from Kr II and Kr I lines. The spectral lines recorded in EUV, UV, and VIS ranges were used for the construction of Boltzmann plots to be used for the estimation of the electron temperature. It was shown that for the lowest Kr III and Kr IV levels, the local thermodynamic equilibrium (LTE) conditions were not fulfilled. The electron temperature was thus estimated based on Kr II and Kr I species where the partial LTE conditions could be expected.

  18. Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves

    SciTech Connect

    Schroeder, Carl B.; Esarey, Eric

    2010-06-30

    A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically-intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a non-relativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined, and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for non-relativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.

  19. Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves.

    PubMed

    Schroeder, C B; Esarey, E

    2010-05-01

    A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a nonrelativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for Langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three-velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for nonrelativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances. PMID:20866340

  20. Challenges of PIC Simulations at High Laser Intensity

    NASA Astrophysics Data System (ADS)

    Luedtke, Scott V.; Arefiev, Alexey V.; Toncian, Toma; Hegelich, Bjorn Manuel

    2015-11-01

    New lasers with very high intensity pulses (I >1022 W/cm2) are being commissioned to explore new regimes of laser-matter interactions. These lasers require accurate particle-in-cell (PIC) simulations, which may require new computational approaches to efficiently produce physically accurate results. We examine the constraints on PIC simulations at high field intensity imposed by both the particle pusher and field solver. As proposed by Arefiev, et al. (Physics of Plasmas 22, 013103 (2015)), we implement adaptive sub-cycling in the Boris pusher of the EPOCH code and demonstrate its effectiveness in efficiently reducing errors from the pusher. It is well know that the use of a finite-difference scheme also modifies the electromagnetic wave dispersion relation. We examine the effect of the resulting discrepancy in the phase velocity on electron acceleration, and demonstrate that relatively small errors in the phase velocity lead to substantial changes in the electron energy gain from the laser pulse. We discuss the corresponding conditions for the field solver. These results are relevant to direct laser acceleration and underdense ionization experiments. This work was supported by NNSA cooperative agreement DE-NA0002008, the Defense Advanced Research Projects Agency's PULSE program (12-63-PULSE-FP014) and the Air Force Office of Scientific Research (FA9550-14-1-0045).

  1. Nonlinear pulse propagation and phase velocity of laser-driven plasma waves

    SciTech Connect

    Schroeder, Carl B.; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2011-03-25

    Laser evolution and plasma wave excitation by a relativistically-intense short-pulse laser in underdense plasma are investigated in the broad pulse limit, including the effects of pulse steepening, frequency red-shifting, and energy depletion. The nonlinear plasma wave phase velocity is shown to be significantly lower than the laser group velocity and further decreases as the pulse propagates owing to laser evolution. This lowers the thresholds for trapping and wavebreaking, and reduces the energy gain and efficiency of laser-plasma accelerators that use a uniform plasma profile.

  2. Plasma temperature clamping in filamentation laser induced breakdown spectroscopy

    SciTech Connect

    Harilal, Sivanandan S.; Yeak, J.; Phillips, Mark C.

    2015-10-19

    Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filamentation channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also partly explains the reason for the occurrence of atomic plume during fs LIBS in air compared to long-pulse ns LIBS.

  3. Plasma temperature clamping in filamentation laser induced breakdown spectroscopy.

    PubMed

    Harilal, S S; Yeak, J; Phillips, M C

    2015-10-19

    Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filament channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also explain the near absence of ion emission but strong atomic neutral emission from plumes produced during fs LIBS in air. PMID:26480372

  4. Measurement of acceleration in femtosecond laser-plasmas

    SciTech Connect

    Haessner, R.; Theobald, W.; Niedermeier, S.; Michelmann, K.; Feurer, T.; Schillinger, H.; Sauerbrey, R.

    1998-02-20

    Accelerations up to 4x10{sup 19} m/s{sup 2} are measured in femtosecond laser-produced plasmas at intensities of 10{sup 18} W/cm{sup 2} using the Frequency Resolved Optical Gating (FROG) technique. A high density plasma is formed by focusing an ultrashort unchirped laser pulse on a plane carbon target and part of the reflected pulse is eventually detected by a FROG autocorrelator. Radiation pressure and thermal pressure accelerate the plasma which causes a chirp in the reflected laser pulse. The retrieved phase and amplitude information reveal that the plasma motion is dominated by the large light pressure which pushes the plasma into the target. This is supported by theoretical estimates and by the results of independently measured time integrated spectra of the reflected pulse.

  5. Laser propagation and soliton generation in strongly magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Feng, W.; Li, J. Q.; Kishimoto, Y.

    2016-03-01

    The propagation characteristics of various laser modes with different polarization, as well as the soliton generation in strongly magnetized plasmas are studied numerically through one-dimensional (1D) particle-in-cell (PIC) simulations and analytically by solving the laser wave equation. PIC simulations show that the laser heating efficiency substantially depends on the magnetic field strength, the propagation modes of the laser pulse and their intensities. Generally, large amplitude laser can efficiently heat the plasma with strong magnetic field. Theoretical analyses on the linear propagation of the laser pulse in both under-dense and over-dense magnetized plasmas are well confirmed by the numerical observations. Most interestingly, it is found that a standing or moving soliton with frequency lower than the laser frequency is generated in certain magnetic field strength and laser intensity range, which can greatly enhance the laser heating efficiency. The range of magnetic field strength for the right-hand circularly polarized (RCP) soliton formation with high and low frequencies is identified by solving the soliton equations including the contribution of ion's motion and the finite temperature effects under the quasi-neutral approximation. In the limit of immobile ions, the RCP soliton tends to be peaked and stronger as the magnetic field increases, while the enhanced soliton becomes broader as the temperature increases. These findings in 1D model are well validated by 2D simulations.

  6. Laser Channeling in an Inhomogeneous Plasma for Fast-Ignition Laser Fusion

    NASA Astrophysics Data System (ADS)

    Ivancic, S.; Haberberger, D.; Theobald, W.; Anderson, K. S.; Froula, D. H.; Meyerhofer, D. D.; Tanaka, K.; Habara, H.; Iwawaki, T.

    2014-10-01

    The evacuation of a plasma cavity by a high-intensity laser beam is of practical importance to the channeling fast-ignition concept. The channel in the plasma corona of an imploded inertial confinement fusion capsule provides a clear path through the plasma so that the energy from a second high-intensity laser can be deposited close to the dense core of the assembled fuel to achieve ignition. This study reports on experiments that demonstrate the transport of high-intensity (>1017 W/cm2) laser light through an inhomogeneous kilojoule-laser-produced plasma up to overcritical density. The multikilojoule high-intensity light evacuates a cavity inside the focal spot, leaving a parabolic trough that is observed using a novel optical probing technique--angular filter refractometery. The cavity forms in less than 100 ps using a 20-TW laser pulse and bores at a velocity of ~ 2 μm/ps. The experimentally measured depths of the cavity are consistent with a ponderomotive hole-boring model. The experiments show that 100-ps IR pulses with an intensity of ~ 5 ×1017 W/cm2 produced a channel up to the critical density, while 10-ps pulses with the same energy but higher intensity did not propagate as far. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  7. Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

    NASA Astrophysics Data System (ADS)

    Thévenet, M.; Leblanc, A.; Kahaly, S.; Vincenti, H.; Vernier, A.; Quéré, F.; Faure, J.

    2016-04-01

    Accelerating particles to relativistic energies over very short distances using lasers has been a long-standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration. With the advent of petawatt lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams.

  8. Large-amplitude plasma wave generation with a high-intensity short-pulse beat wave.

    PubMed

    Walton, B; Najmudin, Z; Wei, M S; Marle, C; Kingham, R J; Krushelnick, K; Dangor, A E; Clarke, R J; Poulter, M J; Hernandez-Gomez, C; Hawkes, S; Neely, D; Collier, J L; Danson, C N; Fritzler, S; Malka, V

    2002-12-15

    A short-pulse laser beat wave scheme for advanced particle accelerator applications is examined. A short, intense (3-ps, >10(18)-W cm(-2)) two-frequency laser pulse is produced by use of a modified chirped-pulse amplification scheme and is shown to produce relativistic plasma waves during interactions with low-density plasmas. The generation of plasma waves was observed by measurement of forward Raman scattering. Resonance was found to occur at an electron density many times that expected, owing to ponderomotive displacement of plasma within the focal region. PMID:18033483

  9. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Thresholds of surface plasma formation by the interaction of laser pulses with a metal

    NASA Astrophysics Data System (ADS)

    Borets-Pervak, I. Yu; Vorob'ev, V. S.

    1995-04-01

    An analysis is made of a model of the formation of a surface laser plasma which takes account of the heating and vaporisation of thermally insulated surface microdefects. This model is used in an interpretation of experiments in which such a plasma has been formed by irradiation of a titanium target with microsecond CO2 laser pulses. A comparison with the experimental breakdown intensities is used to calculate the average sizes of microdefects and their concentration: the results are in agreement with the published data. The dependence of the delay time of plasma formation on the total energy in a laser pulse is calculated.

  10. Short-pulse high intensity laser thin foil interaction

    NASA Astrophysics Data System (ADS)

    Audebert, Patrick

    2003-10-01

    The technology of ultrashort pulse laser generation has progressed to the point that optical pulses larger than 10 J, 300 fs duration or shorter are routinely produced. Such pulses can be focused to intensities exceeding 10^18 W/cm^2. With high contrast pulses, these focused intensities can be used to heat solid matter to high temperatures with minimal hydrodynamic expansion, producing an extremely high energy-density state of matter for a short period of time. This high density, high temperature plasma can be studied by x-ray spectroscopy. We have performed experiments on thin foils of different elements under well controlled conditions at the 100 Terawatt laser at LULI to study the characteristics X-ray emission of laser heated solids. To suppress the ASE effect, the laser was frequency doubled. S-polarized light with a peak intensity of 10^19W/cm^2 was used to minimize resonance absorption. To decrease the effect of longitudinal temperature gradients very thin (800 μ) aluminum foil targets were used. We have also studied the effect of radial gradient by limiting the measured x-ray emission zone using 50μ or 100μ pinhole on target. The spectra, in the range 7-8Å, were recorded using a conical crystal spectrometer coupled to a 800 fs resolution streak camera. A Fourier Domain Interferometry (FDI) of the back of the foil was also performed providing a measurement of the hydrodynamic expansion as function of time for each shot. To simulate the experiment, we used the 1D hydrodynamic code FILM with a given set of plasma parameter (ρ, Te) as initial conditions. The X-ray emission was calculated by post processing hydrodynamic results with a collisional-radiative model which uses super-configuration average atomic data. The simulation reproduces the main features of the experimental time resolved spectrum.

  11. Generation of strongly coupled plasmas by high power excimer laser

    NASA Astrophysics Data System (ADS)

    Zhu, Yongxiang; Liu, Jingru; Zhang, Yongsheng; Hu, Yun; Zhang, Jiyan; Zheng, Zhijian; Ye, Xisheng

    2013-05-01

    (ultraviolet). To generate strongly coupled plasmas (SCP) by high power excimer laser, an Au-CH-Al-CH target is used to make the Al sample reach the state of SCP, in which the Au layer transforms laser energy to X-ray that heating the sample by volume and the CH layers provides necessary constraints. With aid of the MULTI-1D code, we calculate the state of the Al sample and its relationship with peak intensity, width and wavelength of laser pulses. The calculated results suggest that an excimer laser with peak intensity of the magnitude of 1013W/cm2 and pulse width being 5ns - 10ns is suitable to generate SCP with the temperature being tens of eV and the density of electron being of the order of 1022/cm-3. Lasers with shorter wavelength, such as KrF laser, are preferable.

  12. Amplification and generation of ultra-intense twisted laser pulses via stimulated Raman scattering.

    PubMed

    Vieira, J; Trines, R M G M; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O

    2016-01-01

    Twisted Laguerre-Gaussian lasers, with orbital angular momentum and characterized by doughnut-shaped intensity profiles, provide a transformative set of tools and research directions in a growing range of fields and applications, from super-resolution microcopy and ultra-fast optical communications to quantum computing and astrophysics. The impact of twisted light is widening as recent numerical calculations provided solutions to long-standing challenges in plasma-based acceleration by allowing for high-gradient positron acceleration. The production of ultra-high-intensity twisted laser pulses could then also have a broad influence on relativistic laser-matter interactions. Here we show theoretically and with ab initio three-dimensional particle-in-cell simulations that stimulated Raman backscattering can generate and amplify twisted lasers to petawatt intensities in plasmas. This work may open new research directions in nonlinear optics and high-energy-density science, compact plasma-based accelerators and light sources. PMID:26817620

  13. Amplification and generation of ultra-intense twisted laser pulses via stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Vieira, J.; Trines, R. M. G. M.; Alves, E. P.; Fonseca, R. A.; Mendonça, J. T.; Bingham, R.; Norreys, P.; Silva, L. O.

    2016-01-01

    Twisted Laguerre-Gaussian lasers, with orbital angular momentum and characterized by doughnut-shaped intensity profiles, provide a transformative set of tools and research directions in a growing range of fields and applications, from super-resolution microcopy and ultra-fast optical communications to quantum computing and astrophysics. The impact of twisted light is widening as recent numerical calculations provided solutions to long-standing challenges in plasma-based acceleration by allowing for high-gradient positron acceleration. The production of ultra-high-intensity twisted laser pulses could then also have a broad influence on relativistic laser-matter interactions. Here we show theoretically and with ab initio three-dimensional particle-in-cell simulations that stimulated Raman backscattering can generate and amplify twisted lasers to petawatt intensities in plasmas. This work may open new research directions in nonlinear optics and high-energy-density science, compact plasma-based accelerators and light sources.

  14. Plasma heating and current drive using intense, pulsed microwaves

    SciTech Connect

    Cohen, B.I.; Cohen, R.H.; Nevins, W.M.; Rognlien, T.D.; Bonoli, P.T.; Porkolab, M.

    1988-01-01

    The use of powerful new microwave sources, e.g., free-electron lasers and relativistic gyrotrons, provide unique opportunities for novel heating and current-drive schemes in the electron-cyclotron and lower-hybrid ranges of frequencies. These high-power, pulsed sources have a number of technical advantages over conventional, low-intensity sources; and their use can lead to improved current-drive efficiencies and better penetration into a reactor-grade plasma in specific cases. The Microwave Tokamak Experiment at Lawrence Livermore National Laboratory will provide a test for some of these new heating and current-drive schemes. This paper reports theoretical progress both in modeling absorption and current drive for intense pulses and in analyzing some of the possible complications that may arise, e.g., parametric instabilities and nonlinear self-focusing. 22 refs., 9 figs., 1 tab.

  15. Ablation of carbon-doped liquid propellant in laser plasma propulsion

    NASA Astrophysics Data System (ADS)

    Zheng, Z. Y.; Liang, T.; Zhang, S. Q.; Gao, L.; Gao, H.; Zhang, Z. L.

    2016-04-01

    Carbon-doped liquid glycerol ablated by nanosecond pulse laser is investigated in laser plasma propulsion. It is found that the propulsion is much more correlated with the carbon content. The doped carbon can change the laser intensity and laser focal position so as to reduce the splashing quantity of the glycerol. Less consumption of the liquid volume results in a high specific impulse.

  16. Photoionized argon plasmas induced with intense soft x-ray and extreme ultraviolet pulses

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Wachulak, P.; Fok, T.; Węgrzyński, Ł.; Fiedorowicz, H.; Skrzeczanowski, W.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Dudzak, R.; Dostal, J.; Krousky, E.; Skala, J.; Ullschmied, J.; Hrebicek, J.; Medrik, T.

    2016-01-01

    In this work, photoionized plasmas were created by irradiation of gaseous argon with soft x-ray (SXR) and extreme ultraviolet (EUV) intense radiation pulses. Two different laser-produced plasma sources, employing a low energy Nd:YAG laser and a high energy iodine laser system (PALS), were used for creation of photoionized plasmas. In both cases the EUV or SXR beam irradiated the Ar stream, injected into a vacuum chamber synchronously with the radiation pulse. Emission spectra, measured for the Ar photoionized plasmas indicated strong differences in ionization degree for plasmas produced using low and high energy systems. In case of the the EUV driving pulses, emission lines corresponding to neutral atoms and singly charged ions were observed. In case of the SXR pulses utilized for the photoionized plasma creation, only Ar V–VIII emission lines were recorded. Additionally, electron density measurements were performed by laser interferometry employing a femtosecond laser system synchronized with the irradiating system. Maximum electron density for the Ar photoionized plasma, induced using the high energy system, reached 1.9 · 1018 cm‑3. Interferometric measurements performed for the moment of maximum intensity of the main laser pulse (t  =  0) revealed no fringe shift. Detection limit for the interferometric measurements was estimated. It allowed to estimate the upper limit for electron density at t  =  0 as 5 · 1016 cm‑3.

  17. Investigation on the Influence of Different Laser Beam Intensity Distributions on Keyhole Geometry During Laser Welding

    NASA Astrophysics Data System (ADS)

    Volpp, J.

    An analytical quasi-static model of the keyhole during laser deep penetration welding is introduced. This model is used to calculate the keyhole geometry depending on spatial laser beam intensity. Keyhole shapes can be found solving the energy and pressure equations. All necessary physical effects like Fresnel and plasma absorption, heat conduction and vaporization are implemented in the model. For evaluation a Gaussian and a top hat beam profile were used. Experimental measurements of the keyhole shape using copper inlays in aluminum base material show good agreement with the results of the modeling.

  18. Multistage coupling of independent laser-plasma accelerators.

    PubMed

    Steinke, S; van Tilborg, J; Benedetti, C; Geddes, C G R; Schroeder, C B; Daniels, J; Swanson, K K; Gonsalves, A J; Nakamura, K; Matlis, N H; Shaw, B H; Esarey, E; Leemans, W P

    2016-02-11

    Laser-plasma accelerators (LPAs) are capable of accelerating charged particles to very high energies in very compact structures. In theory, therefore, they offer advantages over conventional, large-scale particle accelerators. However, the energy gain in a single-stage LPA can be limited by laser diffraction, dephasing, electron-beam loading and laser-energy depletion. The problem of laser diffraction can be addressed by using laser-pulse guiding and preformed plasma waveguides to maintain the required laser intensity over distances of many Rayleigh lengths; dephasing can be mitigated by longitudinal tailoring of the plasma density; and beam loading can be controlled by proper shaping of the electron beam. To increase the beam energy further, it is necessary to tackle the problem of the depletion of laser energy, by sequencing the accelerator into stages, each powered by a separate laser pulse. Here, we present results from an experiment that demonstrates such staging. Two LPA stages were coupled over a short distance (as is needed to preserve the average acceleration gradient) by a plasma mirror. Stable electron beams from a first LPA were focused to a twenty-micrometre radius--by a discharge capillary-based active plasma lens--into a second LPA, such that the beams interacted with the wakefield excited by a separate laser. Staged acceleration by the wakefield of the second stage is detected via an energy gain of 100 megaelectronvolts for a subset of the electron beam. Changing the arrival time of the electron beam with respect to the second-stage laser pulse allowed us to reconstruct the temporal wakefield structure and to determine the plasma density. Our results indicate that the fundamental limitation to energy gain presented by laser depletion can be overcome by using staged acceleration, suggesting a way of reaching the electron energies required for collider applications. PMID:26829223

  19. Laser beat wave resonant terahertz generation in a magnetized plasma channel

    NASA Astrophysics Data System (ADS)

    Bhasin, Lalita; Tripathi, V. K.; Kumar, Pawan

    2016-02-01

    Resonant excitation of terahertz (THz) radiation by nonlinear mixing of two lasers in a ripple-free self created plasma channel is investigated. The channel has a transverse static magnetic field and supports a THz X-mode with phase velocity close to the speed of light in vacuum when the frequency of the mode is close to plasma frequency on the channel axis and its value decreases with the intensity of lasers. The THz is resonantly driven by the laser beat wave ponderomotive force. The THz amplitude scales almost three half power of the intensity of lasers as the width of the THz eigen mode shrinks with laser intensity.

  20. Laser plasma acceleration of electrons: Towards the production of monoenergetic beams

    SciTech Connect

    Krushelnick, K.; Najmudin, Z.; Mangles, S.P.D.; Thomas, A.G.R.; Wei, M.S.; Walton, B.; Gopal, A.; Clark, E.L.; Dangor, A.E.; Fritzler, S.; Murphy, C.D.; Norreys, P.A.; Mori, W.B.; Gallacher, J.; Jaroszynski, D.; Viskup, R.

    2005-05-15

    The interaction of high intensity laser pulses with underdense plasma is investigated experimentally using a range of laser parameters and energetic electron production mechanisms are compared. It is clear that the physics of these interactions changes significantly depending not only on the interaction intensity but also on the laser pulse length. For high intensity laser interactions in the picosecond pulse duration regime the production of energetic electrons is highly correlated with the production of plasma waves. However as intensities are increased the peak electron acceleration increases beyond that which can be produced from single stage plasma wave acceleration and direct laser acceleration mechanisms must be invoked. If, alternatively, the pulse length is reduced such that it approaches the plasma period of a relativistic electron plasma wave, high power interactions can be shown to enable the generation of quasimonoenergetic beams of relativistic electrons.

  1. Review of Astrophysics Experiments on Intense Lasers

    SciTech Connect

    Remington, B A; Drake, R P; Takabe, H; Arnett, D

    2000-01-19

    Astrophysics has traditionally been pursued at astronomical observatories and on theorists' computers. Observations record images from space, and theoretical models are developed to explain the observations. A component often missing has been the ability to test theories and models in an experimental setting where the initial and final states are well characterized. Intense lasers are now being used to recreate aspects of astrophysical phenomena in the laboratory, allowing the creation of experimental testbeds where theory and modeling can be quantitatively tested against data. We describe here several areas of astrophysics--supernovae, supernova remnants, gamma-ray bursts, and giant planets--where laser experiments are under development to test our understanding of these phenomena.

  2. Low intensity laser treatment of nerve injuries

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Guang; Liu, Timon Cheng-Yi; Luo, Qing-Ming

    2007-05-01

    The neural regeneration and functional recovery after nerve injuries has long been an important field in neuroscience. Low intensity laser (LIL) irradiation is a novel and useful tool for the treatment of many injuries and disorders. The aim of this study was to assess the role of LIL irradiation in the treatment of peripheral and central nerve injuries. Some animal experiments and clinical investigations have shown beneficial effects of LIL irradiation on neural tissues, but its therapeutic value and efficacy are controversial. Reviewing the data of experimental and clinical studies by using the biological information model of photobiomodulation, we conclude that LIL irradiation in specific parameters can promote the regeneration of injured peripheral and central nerves and LIL therapy is a safe and valuable treatment for superficial peripheral nerve injuries and spinal cord injury. The biological effects of LIL treatment depend largely on laser wavelength, power and dose per site and effective irradiation doses are location-specific.

  3. Mestastable State Population in Laser Induced Plasmas

    NASA Technical Reports Server (NTRS)

    Kwong, V. H. S.; Kyriakides, C.; Ward, W. K.

    2006-01-01

    Laser induced plasma has been used as a source of neutrals and ions in the study of astrophysical plasmas. The purity of state of this source is essential in the determination of collision parameters such as the charge transfer rate coefficients between ions and neutrals. We will show that the temperature of the laser induced plasma is a rapidly decreasing function of time. The temperature is initially high but cools off rapidly through collisions with the expanding plasma electrons as the plasma recombines and streams into the vacuum. This rapid expansion of the plasma, similar to a supersonic jet, drastically lowers the internal energy of the neutrals and ions.

  4. Relativistic second-harmonic generation of a laser from underdense plasmas

    SciTech Connect

    Singh, K.P.; Gupta, D.N.; Yadav, Sushila; Tripathi, V.K.

    2005-01-01

    A high intensity laser obliquely incident on a vacuum-plasma interface produces second-harmonic radiation in the reflected component. The efficiency of second-harmonic generation increases with the angle of incidence, up to critical angle of incidence (our model is not valid beyond critical angle of incidence). The efficiency also depends on electron density, showing a maximum at {omega}{sub p}{sup 2}/{omega}{sup 2} congruent with 0.7, where {omega}{sub p} and {omega} are relativistic plasma frequency and laser frequency, respectively. The efficiency of second-harmonic generation increases sharply with laser intensity in the nonrelativistic regime and saturates at higher intensities. The intensity of the second harmonic is proportional to square of the laser intensity at low pump laser intensities and tends to proportional to laser intensity in the strong relativistic regime.

  5. Laser plasma interaction physics in the context of fusion

    NASA Astrophysics Data System (ADS)

    Labaune, C.; Fuchs, J.; Depierreux, S.; Baldis, H. A.; Pesme, D.; Myatt, J.; Hüller, S.; Tikhonchuk, V. T.; Laval, G.

    2000-08-01

    Of vital importance for Inertial Confinement Fusion (ICF) are the understanding and control of the nonlinear processes which can occur during the propagation of the laser pulses through the underdense plasma surrounding the fusion capsule. The control of parametric instabilities has been studied experimentally, using the LULI six-beam laser facility, and also theoretically and numerically. New results based on the direct observation of plasma waves with Thomson scattering of a short wavelength probe beam have revealed the occurence of the Langmuir decay instability. This secondary instability may play an imporant role in the saturation of stimulated Raman scattering. Another mechanism for reducing the growth of the scattering instabilities is the so-called `plasma-induced incoherence'. Namely, recent theoretical studies have shown that the propagation of laser beams through the underdense plasma can increase their spatial and temporal incoherence. This plasma-induced beam smoothing can reduce the levels of parametric instabilities. One signature of this process is a large increase of the spectral width of the laser light after propagation through the plasma. Comparison of the experimental results with numerical simulations shows an excellent agreement between the observed and calculated time-resolved spectra of the transmitted laser light at various laser intensities.

  6. Polyatomic molecules under intense femtosecond laser irradiation.

    PubMed

    Konar, Arkaprabha; Shu, Yinan; Lozovoy, Vadim V; Jackson, James E; Levine, Benjamin G; Dantus, Marcos

    2014-12-11

    Interaction of intense laser pulses with atoms and molecules is at the forefront of atomic, molecular, and optical physics. It is the gateway to powerful new tools that include above threshold ionization, high harmonic generation, electron diffraction, molecular tomography, and attosecond pulse generation. Intense laser pulses are ideal for probing and manipulating chemical bonding. Though the behavior of atoms in strong fields has been well studied, molecules under intense fields are not as well understood and current models have failed in certain important aspects. Molecules, as opposed to atoms, present confounding possibilities of nuclear and electronic motion upon excitation. The dynamics and fragmentation patterns in response to the laser field are structure sensitive; therefore, a molecule cannot simply be treated as a "bag of atoms" during field induced ionization. In this article we present a set of experiments and theoretical calculations exploring the behavior of a large collection of aryl alkyl ketones when irradiated with intense femtosecond pulses. Specifically, we consider to what extent molecules retain their molecular identity and properties under strong laser fields. Using time-of-flight mass spectrometry in conjunction with pump-probe techniques we study the dynamical behavior of these molecules, monitoring ion yield modulation caused by intramolecular motions post ionization. The set of molecules studied is further divided into smaller sets, sorted by type and position of functional groups. The pump-probe time-delay scans show that among positional isomers the variations in relative energies, which amount to only a few hundred millielectronvolts, influence the dynamical behavior of the molecules despite their having experienced such high fields (V/Å). High level ab initio quantum chemical calculations were performed to predict molecular dynamics along with single and multiphoton resonances in the neutral and ionic states. We propose the

  7. Improving the intensity of the HELEN Laser at AWE

    NASA Astrophysics Data System (ADS)

    Hopps, Nicholas; Nolan, Jonathan; Girling, Mark; Kopec, Maria; Harvey, Ewan

    2005-04-01

    The HELEN laser is a three-beam, large aperture Nd:glass laser, used for plasma physics studies at the Atomic Weapons Establishment in the UK. Two of the beams nominally deliver 500 J each in 1 ns at the second harmonic (527 nm). The third beam, the "backlighter", has recently been upgraded to operate as a chirped pulse amplification system and it now routinely delivers 70 J to target in 500 fs. Optimal focal spot performance is achieved using a closed-loop adaptive optics system, which ensures good wavefront characteristics, irrespective of whether previous firing of the amplifiers has induced refractive index variations in the laser glass. The system uses a 32 element bimorph mirror with 98 mm aperture, roughly half way through the laser chain. A Shack-Hartman wavefront sensor, positioned at the output of the laser is the diagnostic used to provide feedback to the deformable mirror. Correction of the static and slowly varying aberrations on the beam has been demonstrated. The fast aberrations induced during the flashlamp discharge have been evaluated. The improved focal spot characteristics result in an intensity on target of significantly greater than 1019 Wcm-2.

  8. Thomson parabola spectrometry for gold laser-generated plasmas

    SciTech Connect

    Torrisi, L.; Cutroneo, M.; Ando, L.; Ullschmied, J.

    2013-02-15

    The plasma generated from thin gold films irradiated in high vacuum at high intensity ({approx}10{sup 15} W/cm{sup 2}) laser shot is characterized in terms of ion generation through time-of-flight techniques and Thomson parabola spectrometry. Gold ions and protons, accelerated in forward direction by the electric field developed in non-equilibrium plasma, have been investigated. Measurements, performed at PALS laboratory, give information about the gold charge states distributions, the ion energy distributions and the proton acceleration driven as a function of film thickness, laser parameters, and angular emission. The ion diagnostics of produced plasma in forward direction permits to understand some mechanisms developed during its expansion kinetics. The role of the focal position of a laser beam with respect to the target surface, plasma properties, and the possibility to accelerate protons up to energies above 3 MeV has been presented and discussed.

  9. Control of laser plasma instabilities in hohlraums

    SciTech Connect

    Kruer, W.L.

    1996-12-01

    Laser plasma instabilities are an important constraint on the operating regime for inertial fusion. Many techniques have been developed to control the various laser-driven instabilities. Experiments with long scale length plasmas are testing these instability levels, the nonlinear regimes, and the control mechanisms.

  10. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    NASA Astrophysics Data System (ADS)

    Kalmykov, Serguei; Shvets, Gennady

    2006-11-01

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters.

  11. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    SciTech Connect

    Kalmykov, Serguei; Shvets, Gennady

    2006-11-27

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters.

  12. High-energy 4{omega} probe laser for laser-plasma experiments at nova

    SciTech Connect

    Glenzer, S. H., LLNL

    1998-06-02

    For the characterization of inertial confinement fusion plasmas we implemented a high-energy 4{omega} probe laser at the Nova laser facility. A total energy of > 50 Joules at 4{omega}, a focal spot size of order 100 {micro}m, and a pointing accuracy of 100 {micro}m was demonstrated for target shots. This laser provides intensities of up to 3 x 10{sup 14}W cm{sup -2} and therefore fulfills high-power requirements for laser-plasma interaction experiments. The 4{omega} probe laser is now routinely used for Thomson scattering. Successful experiments were performed in gas-filled hohlraums at electron densities of n{sub e} > 2 X 10{sup 21}cm{sup -3} which represents the highest density plasma so far being diagnosed with Thomson scattering.

  13. Laser plasma at low air pressure

    NASA Astrophysics Data System (ADS)

    Vas'kovskii, Iu. M.; Moiseev, V. N.; Rovinskii, R. E.; Tsenina, I. S.

    1993-01-01

    The ambient-pressure dependences of the dynamic and optical characteristics of a laser plasma generated by CO2-laser irradiation of an obstacle are investigated experimentally. The change of the sample's surface roughness after irradiation is investigated as a function of air pressure. It is concluded that the transition from the air plasma to the erosion plasma takes place at an air pressure of about 1 mm Hg. The results confirm the existing theory of plasma formation near the surface of an obstacle under the CO2-laser pulse effect in air.

  14. Plasma laser accelerator: longitudinal dynamics, the plasma/laser interaction, and a qualitative design

    SciTech Connect

    Ruth, R.D.; Chao, A.W.

    1982-04-01

    In this paper we present our studies on a plasma laser accelerator. First we look at the longitudinal dynamics and the trapping of particles in the potential well due to the longitudinal electric field in a plasma density wave. Next we study the plasma/laser interaction to obtain power requirements. Lastly, we qualitatively design a plasma/laser accelerator with parameters somewhat more modest than existing suggestions.

  15. Absolute intensity of radiation emitted by uranium plasmas

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.; Lee, J. H.; Mcfarland, D. R.

    1975-01-01

    The absolute intensity of radiation emitted by fissioning and nonfissioning uranium plasmas in the spectral range from 350 nm to 1000 nm was measured. The plasma was produced in a plasma-focus apparatus and the plasma properties are simular to those anticipated for plasma-core nuclear reactors. The results are expected to contribute to the establishment of design criteria for the development of plasma-core reactors.

  16. Light-curing polymers for laser plasma generation

    NASA Astrophysics Data System (ADS)

    Loktionov, E. Y.; Protasov, Y. S.; Protasov, Y. Y.; Telekh, V. D.

    2015-07-01

    Solid rather than liquid media are used in pulsed laser plasma generators despite sophisticated transportation and dosing system need for a long-term operation. Liquid media could be more preferable due to transfer and dosing (down to 10-14 L) being well developed, but plasma generation of those results in intense droplet formation and kinetic energy losses. Combination of liquids transportation advantages and solids plasma generation efficiency might resolve this trade-off. Liquid-to-solid transition can be induced by cooling down to sublimation temperature, thermo-, photo- or electron induced polymerization (curing). Light cured polymers seem to be very useful as active media for plasma generators, since they can be solidified very fast (ca. 30 ms) just before impact. We considered experimentally several UV- curing polymer and mixtures ablation regimes and supply schemes for laser plasma generation. The best results were obtained for liquid polymer at high-power pulsed irradiation matching curing optimum wavelength.

  17. Laser-plasma instability in hohlraums

    SciTech Connect

    Fernandez, J.C.; Cobble, J.A.; Hsing, W.W.

    1994-10-01

    A gas-filled hohlraum designed so as to approach plasma conditions expected in future ignition hohlraums has been fielded at the Nova laser. Radiation hydrodynamics modeling of these Nova hohlraums predicts reasonably well the measured plasma parameters. The measured reflectivity of a probe beam by Stimulated Brillouin scattering is modest. Some observed dependencies of reflectivity on laser and plasma parameters are understood theoretically, while others are not.

  18. A side-injected-laser plasma accelerator

    SciTech Connect

    Katsouleas, T.; Dawson, J.M.; Sultana, D.; Yun, Y.T.

    1985-10-01

    A new method for driving relativistic plasma waves capable of ultra-high acceleration gradients (order 1GeV/cm) is presented. By injecting a single laser frequency from the side, rather than colinearly with the accelerated particles, both pump depletion and particle dephasing may be avoidable. The coupling of the side injected laser to the relativistic plasma wave via a pre-formed density ripple in the plasma is modelled analytically and with computer simulation.

  19. Beat wave excitation of electron plasma wave by relativistic cross focusing of cosh-Gaussian laser beams in plasma

    NASA Astrophysics Data System (ADS)

    Singh, Arvinder; Gupta, Naveen

    2015-06-01

    A scheme for beat wave excitation of electron plasma wave (EPW) is proposed by relativistic cross-focusing of two coaxial Cosh-Gaussian (ChG) laser beams in an under dense plasma. The plasma wave is generated on account of beating of two coaxial laser beams of frequencies ω1 and ω2 . The mechanism for laser produced nonlinearity is assumed to be relativistic nonlinearity in electron mass. Following moment theory approach in Wentzel Kramers Brillouin (W.K.B) approximation, the coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived. The relativistic nonlinearity depends not only on the intensity of first laser beam but also on the intensity of second laser beam. Therefore, propagation dynamics of one laser beam affect that of second beam and hence cross-focusing of the two laser beams takes place. Due to non uniform intensity distribution of pump laser beams, the background electron concentration gets modified. The amplitude of EPW, which depends on the background electron concentration, thus gets nonlinearly coupled with the laser beams. The effects of relativistic electron mass nonlinearity and the cross-focusing of pump beams on excitation of EPW have been incorporated. Numerical simulations have been carried out to investigate the effect of laser as well as plasma parameters on cross-focusing of laser beams and further its effect on power of excited EPW.

  20. Plasma channel diagnostic based on laser centroid oscillations

    SciTech Connect

    Gonsalves, A. J.; Nakamura, K.; Lin, C.; Osterhoff, J.; Shiraishi, S.; Schroeder, C. B.; Geddes, C. G. R.; Tóth, Cs.; Esarey, E.; Leemans, W. P.

    2010-05-01

    A technique has been developed for measuring the properties of discharge-based plasma channels by monitoring the centroid location of a laser beam exiting the channel as a function of input alignment offset between the laser and the channel. Experiments were performed using low-intensity (<1014 Wcm-2) laser pulses focused onto the entrance of a hydrogen-filled capillary discharge waveguide. Scanning the laser centroid position at the input of the channel and recording the exit position allows determination of the channel depth with an accuracy of a few percent, measurement of the transverse channel shape, and inference of the matched spot size. In addition, accurate alignment of the laser beam through the plasma channel is provided by minimizing laser centroid motion at the channel exit as the channel depth is scanned either by scanning the plasma density or the discharge timing. The improvement in alignment accuracy provided by this technique will be crucial for minimizing electron beam pointing errors in laser plasma accelerators.

  1. Amplification and generation of ultra-intense twisted laser pulses via stimulated Raman scattering

    PubMed Central

    Vieira, J.; Trines, R. M. G. M.; Alves, E. P.; Fonseca, R. A.; Mendonça, J. T.; Bingham, R.; Norreys, P.; Silva, L. O.

    2016-01-01

    Twisted Laguerre–Gaussian lasers, with orbital angular momentum and characterized by doughnut-shaped intensity profiles, provide a transformative set of tools and research directions in a growing range of fields and applications, from super-resolution microcopy and ultra-fast optical communications to quantum computing and astrophysics. The impact of twisted light is widening as recent numerical calculations provided solutions to long-standing challenges in plasma-based acceleration by allowing for high-gradient positron acceleration. The production of ultra-high-intensity twisted laser pulses could then also have a broad influence on relativistic laser–matter interactions. Here we show theoretically and with ab initio three-dimensional particle-in-cell simulations that stimulated Raman backscattering can generate and amplify twisted lasers to petawatt intensities in plasmas. This work may open new research directions in nonlinear optics and high–energy-density science, compact plasma-based accelerators and light sources. PMID:26817620

  2. [The Spectral Analysis of Laser-Induced Plasma in Laser Welding with Various Protecting Conditions].

    PubMed

    Du, Xiao; Yang, Li-jun; Liu, Tong; Jiao, Jiao; Wang, Hui-chao

    2016-01-01

    The shielding gas plays an important role in the laser welding process and the variation of the protecting conditions has an obvious effect on the welding quality. This paper studied the influence of the change of protecting conditions on the parameters of laser-induced plasma such as electron temperature and electron density during the laser welding process by designing some experiments of reducing the shielding gas flow rate step by step and simulating the adverse conditions possibly occurring in the actual Nd : YAG laser welding process. The laser-induced plasma was detected by a fiber spectrometer to get the spectral data. So the electron temperature of laser-induced plasma was calculated by using the method of relative spectral intensity and the electron density by the Stark Broadening. The results indicated that the variation of protecting conditions had an important effect on the electron temperature and the electron density in the laser welding. When the protecting conditions were changed, the average electron temperature and the average electron density of the laser-induced plasma would change, so did their fluctuation range. When the weld was in a good protecting condition, the electron temperature, the electron density and their fluctuation were all low. Otherwise, the values would be high. These characteristics would have contribution to monitoring the process of laser welding. PMID:27228732

  3. Characterization of material ablation driven by laser generated intense extreme ultraviolet light

    NASA Astrophysics Data System (ADS)

    Tanaka, Nozomi; Masuda, Masaya; Deguchi, Ryo; Murakami, Masakatsu; Sunahara, Atsushi; Fujioka, Shinsuke; Yogo, Akifumi; Nishimura, Hiroaki

    2015-09-01

    We present a comparative study on the hydrodynamic behaviour of plasmas generated by material ablation by the irradiation of nanosecond extreme ultraviolet (EUV or XUV) or infrared laser pulses on solid samples. It was clarified that the difference in the photon energy deposition and following material heating mechanism between these two lights result in the difference in the plasma parameters and plasma expansion characteristics. Silicon plate was ablated by either focused intense EUV pulse (λ = 9-25 nm, 10 ns) or laser pulse (λ = 1064 nm, 10 ns), both with an intensity of ˜109 W/cm2. Both the angular distributions and energy spectra of the expanding ions revealed that the photoionized plasma generated by the EUV light differs significantly from that produced by the laser. The laser-generated plasma undergoes spherical expansion, whereas the EUV-generated plasma undergoes planar expansion in a comparatively narrow angular range. It is presumed that the EUV radiation is transmitted through the expanding plasma and directly photoionizes the samples in the solid phase, consequently forming a high-density and high-pressure plasma. Due to a steep pressure gradient along the direction of the target normal, the EUV plasma expands straightforward resulting in the narrower angular distribution observed.

  4. Characterization of material ablation driven by laser generated intense extreme ultraviolet light

    SciTech Connect

    Tanaka, Nozomi Masuda, Masaya; Deguchi, Ryo; Murakami, Masakatsu; Fujioka, Shinsuke; Yogo, Akifumi; Nishimura, Hiroaki; Sunahara, Atsushi

    2015-09-14

    We present a comparative study on the hydrodynamic behaviour of plasmas generated by material ablation by the irradiation of nanosecond extreme ultraviolet (EUV or XUV) or infrared laser pulses on solid samples. It was clarified that the difference in the photon energy deposition and following material heating mechanism between these two lights result in the difference in the plasma parameters and plasma expansion characteristics. Silicon plate was ablated by either focused intense EUV pulse (λ = 9–25 nm, 10 ns) or laser pulse (λ = 1064 nm, 10 ns), both with an intensity of ∼10{sup 9 }W/cm{sup 2}. Both the angular distributions and energy spectra of the expanding ions revealed that the photoionized plasma generated by the EUV light differs significantly from that produced by the laser. The laser-generated plasma undergoes spherical expansion, whereas the EUV-generated plasma undergoes planar expansion in a comparatively narrow angular range. It is presumed that the EUV radiation is transmitted through the expanding plasma and directly photoionizes the samples in the solid phase, consequently forming a high-density and high-pressure plasma. Due to a steep pressure gradient along the direction of the target normal, the EUV plasma expands straightforward resulting in the narrower angular distribution observed.

  5. Relativistic laser piston model: Ponderomotive ion acceleration in dense plasmas using ultraintense laser pulses

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    Laser ponderomotive force at superhigh intensities provides an efficient ion acceleration in bulk dense targets and evacuates a channel enabling further laser beam propagation. The developed quasistationary model of a laser piston—a double layer structure supported by the radiation pressure—predicts the general parameters of the acceleration process in homogeneous and inhomogeneous overdense plasmas. Particle-in-cell simulations confirm the estimated characteristics in a wide range of laser intensities and ion densities and show advantages of circularly polarized laser pulses. Two nonstationary effects are identified in the simulations. First, oscillations of the piston velocity and of the thickness of the ion charge separation layer broaden the energy spectrum of accelerated ions. Second, the electrons accelerated toward the incoming laser wave emit strong high-frequency radiation, enabling a cooling effect, which helps to sustain high charge neutrality in the piston and to maintain an efficient ion acceleration.

  6. Plasma dynamics near critical density inferred from direct measurements of laser hole boring

    NASA Astrophysics Data System (ADS)

    Gong, Chao; Tochitsky, Sergei Ya.; Fiuza, Frederico; Pigeon, Jeremy J.; Joshi, Chan

    2016-06-01

    We have used multiframe picosecond optical interferometry to make direct measurements of the hole boring velocity, vHB, of the density cavity pushed forward by a train of C O2 laser pulses in a near critical density helium plasma. As the pulse train intensity rises, the increasing radiation pressure of each pulse pushes the density cavity forward and the plasma electrons are strongly heated. After the peak laser intensity, the plasma pressure exerted by the heated electrons strongly impedes the hole boring process and the vHB falls rapidly as the laser pulse intensity falls at the back of the laser pulse train. A heuristic theory is presented that allows the estimation of the plasma electron temperature from the measurements of the hole boring velocity. The measured values of vHB, and the estimated values of the heated electron temperature as a function of laser intensity are in reasonable agreement with those obtained from two-dimensional numerical simulations.

  7. Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Benedetti, C.; Toth, Cs.; Geddes, C. G. R.; Leemans, W. P.

    2010-11-04

    Plasma accelerators may be driven by the ponderomotive force of an intense laser or the space-charge force of a charged particle beam. The implications for accelerator design and the different physical mechanisms of laser-driven and beam-driven plasma acceleration are discussed. Driver propagation is examined, as well as the effects of the excited plasma wave phase velocity. The driver coupling to subsequent plasma accelerator stages for high-energy physics applications is addressed.

  8. Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Benedetti, C.; Toth, Cs.; Geddes, C. G. R.; Leemans, W.P.

    2010-06-01

    Plasma accelerators may be driven by the ponderomotive force of an intense laser or the space-charge force of a charged particle beam. The implications for accelerator design and the different physical mechanisms of laser-driven and beam-driven plasma acceleration are discussed. Driver propagation is examined, as well as the effects of the excited plasma wave phase velocity. The driver coupling to subsequent plasma accelerator stages for high-energy physics applications is addressed.

  9. Charge Diagnostics for Laser Plasma Accelerators

    SciTech Connect

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W. P.

    2010-06-01

    The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1percent per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm2 and 0.4 pC/ps/mm2, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within +/-10 percent.

  10. Charge Diagnostics for Laser Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W. P.

    2010-11-01

    The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1% per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm2 and 0.4 pC/ps/mm2, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within ±10%.

  11. Charge Diagnostics for Laser Plasma Accelerators

    SciTech Connect

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W. P.

    2010-11-04

    The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1% per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm{sup 2} and 0.4 pC/ps/mm{sup 2}, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within {+-}10%.

  12. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    NASA Astrophysics Data System (ADS)

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing; Ding, Dajun

    2013-10-01

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  13. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    SciTech Connect

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  14. High-power, high-intensity laser propagation and interactions

    SciTech Connect

    Sprangle, Phillip; Hafizi, Bahman

    2014-05-15

    This paper presents overviews of a number of processes and applications associated with high-power, high-intensity lasers, and their interactions. These processes and applications include: free electron lasers, backward Raman amplification, atmospheric propagation of laser pulses, laser driven acceleration, atmospheric lasing, and remote detection of radioactivity. The interrelated physical mechanisms in the various processes are discussed.

  15. Magneto-optical imaging of magnetic domain pattern produced by intense femtosecond laser pulse irradiation

    NASA Astrophysics Data System (ADS)

    Sinha, Jaivarhan; Mohan, Shyam; Banerjee, S. S.; Kahaly, S.; Kumar, G. Ravindra

    2009-03-01

    An important and intriguing area of research is laser plasma generated giant magnetic field pulses. Interaction of ultrashort high intensity laser pulses with matter involves several mechanisms for generating ultrastrong magnetic fields. By irradiating a magnetic recordable tape constituting of γ-Fe2O3 particles with an intense p-polarized femtosecond laser pulses (˜ 10^16 W cm-2, 100fs), we have found complex magnetic field patterns stored in the tape. We image the local magnetic field distribution around the irradiated region [1] using the high sensitivity magneto-optical imaging technique. We understand the complex magnetic domains patterns recoded on the tape in terms of interesting instabilities [1] generated in the plasma produced during the irradiation of the tape with intense laser pulses. [0pt] [1] Jaivardhan Sinha, Shyam Mohan, S. S Banerjee, S. Kahaly, G. Ravindra Kumar, Phys. Rev. E 77, 046118(2008). *satyajit@iitk.ac.in

  16. Laser Diagnostics for Plasma Processes

    NASA Astrophysics Data System (ADS)

    Filimonov, Serguei Victor

    The time transients of vibrational/rotational excitation up to v = 7 vibrational level of the ground electronic state of nitrogen were measured in a positive column during the 1-10 mus pulsed electric discharges, and in the afterglow. Current densities were up to 25 A/cm^2, and pressures up to 6 Torr. It is shown that initially energy is being transferred, primarily into vibrational levels above v = 1, resulting in a highly non Boltzmann distribution. The redistribution between vibrational levels takes place within 100 mus after the discharge pulse. Beyond 100 mus the vibrational populations resemble closely Boltzmann distribution. Significant rotational heating was observed in the afterglow and is attributed to energy transfer from vibration to rotation via collisions with electrons. The rotational temperature was as high as 3500 K and reached maximum values between 80 and 100 mus after the discharge pulse. Standard, Coherent Anti-Stokes Raman Spectroscopy (CARS) was employed in all measurements. A novel laser interferometric system has been developed for real time in situ monitoring of the etch rate during the plasma etching. The two-beam-two-path optical set-up provides continuous etch rate measurements while plasma parameters are changing.

  17. Guiding of laser beams in plasmas by electromagnetic cascade compression

    NASA Astrophysics Data System (ADS)

    Kalmykov, S.; Shvets, G.

    2006-10-01

    The near-resonant beatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few- femtosecond electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red- and blue-shifted by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser phase, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. Thus, a train of high intensity radiation spikes with continually evolving longitudinal profile can be self- guided over several Rayleigh lengths in homogeneous plasma. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW show that achieving GeV energy is possible under realistic experimental conditions.

  18. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Coulomb explosion of a laser plasma

    NASA Astrophysics Data System (ADS)

    Tkachev, Aleksei N.; Yakovlenko, Sergei I.

    1993-11-01

    The behavior of a plasma produced by multistep selective ionization of a vapor and subjected to an intense pulsed electric field has been studied. Electrons are quickly "sucked" out of such a plasma, and then there is a Coulomb explosion of the net charge.

  19. Evolution of chirped laser pulses in a magnetized plasma channel

    SciTech Connect

    Jha, Pallavi; Hemlata,; Mishra, Rohit Kumar

    2014-12-15

    The propagation of intense, short, sinusoidal laser pulses in a magnetized plasma channel has been studied. The wave equation governing the evolution of the radiation field is set up and a variational technique is used to obtain the equations describing the evolution of the laser spot size, pulse length and chirp parameter. Numerical methods are used to analyze the simultaneous evolution of these parameters. The effect of the external magnetic field on initially chirped as well as unchirped laser pulses on the spot size, pulse length and chirping has been analyzed.

  20. Ultlra-intense laser-matter interactions at extreme parameters

    SciTech Connect

    Hegellich, Bjorn M

    2010-11-24

    thinnest of these at less than 3nm, i.e. 1/300 of the laser wavelength, are even thinner than the plasma skin depth. This drastically changes the laser-matter interaction physics leading to the emergence of new particle acceleration mechanisms, like Break-Out Afterburner (BOA) Acceleration, driven by a relativistic, kinetic plasma instability or Radiation Pressure Acceleration (RPA), driven by stabilized charge separation. Furthermore, these interactions also produce relativistic high harmonics in forward direction as well as mono-en,ergetic electron pulses which might lend itself as a source for fully coherent Thomson scattering in the mulit-keV regime. In this talk I will present an overview over the laser developments leading to this paradigm change as well as over the theoretical and experimental results following from it. Specifically we were able for the first time to demonstrate BOA acceleration of Carbon ions to up to 0.5 GeV using a laser pulse with {approx}10{sup 20} W/cm{sup 2} intensity and showing the scalability of this mechanism into regimes relevant for Hadron Therapy. We were further able to demonstrate mono-energetic electron break-out from ultrathin targets, as a first step towards a flying mirror.

  1. Proton shock acceleration in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Marti, M.; Davies, J.; Fonseca, R. A.; Silva, L. O.; Fahlen, J.; Ren, C.; Tsung, F.; Mori, W. B.

    2003-10-01

    The formation of strong, high Mach number (2--3), electrostatic shocks by laser pulses incident on overdense plasma slabs is observed in 1 and 2-dimensional particle-in-cell simulations, for a wide range of intensities, pulse durations, target thicknesses and densities. The shocks propagate undisturbed across the plasma, accelerating the ions (protons). For dimensionless field strength parameter a_0=16 (Iλ^2 ≈ 3 × 10^20 W cm-2 μm^2, where I is intensity and λ wavelength) the highest energy protons are accelerated by the shock. A plateau in the ion spectrum provides a direct signature for shock acceleration.

  2. Nonstationary stimulated Brillouin scattering in a laser plasma

    SciTech Connect

    Chirokikh, A.V.; Kozochkin, S.M.; Streltsov, A.P. ); Ochirov, B.D.; Rubenchik, A.M. )

    1993-08-02

    The stimulated Brillouin scattering (SBS) of intense laser light is considered. We present experimental data demonstrating SBS nonstationarity of radiation directed at thick targets. The results are explained in terms of the interaction of light scattered and reflected from the critical surface. Numerical simulations supporting this interpretation are presented. It is demonstrated that the SBS evolution is neither sensitive to plasma density, size of plasma slab, or beam intensity variations. But it is sensitive enough to changes in the reflection coefficient and variations of the critical surface velocity.

  3. Metal surface nitriding by laser induced plasma

    NASA Astrophysics Data System (ADS)

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

    1996-10-01

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

  4. Laser plasma instability experiments with KrF lasersa)

    NASA Astrophysics Data System (ADS)

    Weaver, J. L.; Oh, J.; Afeyan, B.; Phillips, L.; Seely, J.; Feldman, U.; Brown, C.; Karasik, M.; Serlin, V.; Aglitskiy, Y.; Mostovych, A. N.; Holland, G.; Obenschain, S.; Chan, L.-Y.; Kehne, D.; Lehmberg, R. H.; Schmitt, A. J.; Colombant, D.; Velikovich, A.

    2007-05-01

    Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase the maximum usable intensity by suppressing LPI. The concomitant increase in ablation pressure would allow implosion of low-aspect-ratio pellets to ignition with substantial gain (>20) at much reduced laser energy. The proposed KrF-laser-based Fusion Test Facility (FTF) would exploit this strategy to achieve significant fusion power (150MW) with a rep-rate system that has a per pulse laser energy well below 1 MJ. Measurements of LPI using the Nike KrF laser are presented at and above intensities needed for the FTF (I˜2×1015W/cm2). The results to date indicate that LPI is indeed suppressed. With overlapped beam intensity above the planar, single beam intensity threshold for the two-plasmon decay instability, no evidence of instability was observed via measurements of 3/2ωo and 1/2ωo harmonic emissions.

  5. Laser-generated plasma by carbon nanoparticles embedded into polyethylene

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Ceccio, G.; Cutroneo, M.

    2016-05-01

    Carbon nanoparticles have been embedded into polyethylene at different concentrations by using chemical-physical processes. The synthesized material was characterized in terms of physical modifications concerning the mechanical, compositional and optical properties. Obtained flat targets have been irradiated by Nd:YAG laser at intensities of the order of 1010 W/cm2 in order to generate non-equilibrium plasma in vacuum. The laser-matter interaction produces charge separation effects with consequent acceleration of protons and carbon ions. Plasma was characterized using time-of-flight measurements of the accelerated ions. Applications of the produced targets in order to generate carbon ion beams from laser-generated plasma are presented and discussed.

  6. Laser intensity modulation by nonabsorbing defects

    SciTech Connect

    Feit, M.D.; Rubenchik, A.M.

    1997-01-01

    Nonabsorbing bulk defects can initiate laser damage in transparent materials. Defects such as voids, microcracks and localized stress concentrations can serve as positive or negative lenses for the incident laser light. The resulting interference pattern between refracted and diffracted light can result in intensity increases on the order of a factor of 2 some distance away from a typical negative microlens, and even larger for a positive microlens. Thus, the initial damage site can be physically removed from the defect which initiates damage. The parameter that determines the strength of such lensing is (Ka){sup 2}{Delta}{epsilon}, where the wavenumber K is 2{pi}/{lambda} linear size of the defect and AF, is the difference in dielectric coefficient between matrix and scatterer. Thus, even a small change in refractive index results in a significant effect for a defect large compared to a wavelength. Geometry is also important. Three dimensional (eg. voids) as well as linear and planar (eg. cracks) microlenses can all have strong effects. The present paper evaluates the intensification due to spherical voids and high refractive index inclusions. We wish to particularly draw attention to the very large intensification that can occur at inclusions.

  7. Laser intensity modulation by nonabsorbing defects

    SciTech Connect

    Feit, M.D., Rubenchik, A.M.

    1996-11-20

    Nonabsorbing defects can lead to laser damage. Defects such as voids, microcracks, and localized stressed concentrations, even if they differ from the surrounding medium only by refractive index, can serve as positive or negative lenses for the incident laser light. The resulting interference pattern between refracted and diffracted light can result in intensity increases on the order of a factor of 2 some distance away from a typical negative microlens, and even larger for a positive microlens. Thus, the initial damage site can be physically removed from the defect which initiates damage. The parameter that determines the strength of such lensing is (Ka){sup 2}{Delta}{epsilon}, where the wavenumber K is 2{pi}/{lambda}, 2a is the linear size of the defect, and {Delta}{epsilon} is the difference in dielectric coefficient between matrix and scatterer. Thus, even a small change in refractive index results in a significant effect for a defect large compared to a wavelength. Geometry is also important. Three dimensional (e.g. voids) as well as linear and planar (e.g. cracks) microlenses can all have strong effects. This paper evaluates intensification due to spherical voids and high refractive index inclusions.

  8. Low intensity laser therapy: the clinical approach

    NASA Astrophysics Data System (ADS)

    Kahn, Fred

    2006-02-01

    Recently, there has been significant improvement in the process of research and application of Low Intensity Laser Therapy (LILT). Despite this positive direction, a wide discrepancy between the research component and clinical understanding of the technology remains. In our efforts to achieve better clinical results and more fully comprehend the mechanisms of interaction between light and cells, further studies are required. The clinical results presented in this paper are extrapolated from a wide range of musculoskeletal problems including degenerative osteoarthritis, repetitive motion injuries, sports injuries, etc. The paper includes three separate clinical studies comprising 151, 286 and 576 consecutive patient discharges at our clinic. Each patient studied received a specific course of treatment that was designed for that individual and was modified on a continuing basis as the healing process advanced. On each visit, clinical status correlation with the duration, dosage and other parameters was carried out. The essentials of the treatment consisted of a three stage approach. This involved a photon stream emanating from a number of specified gallium-aluminum-arsenide diodes; stage one, red light array, stage two consisting of an array of infrared diodes and stage three consisting of the application of an infrared laser diode probe. On average, each of these groups required less than 10 treatments per patient and resulted in a significant improvement / cure rate greater than 90% in all conditions treated. This report clearly demonstrates the benefits of LILT, indicating that it should be more widely adapted in all medical therapeutic settings.

  9. Terahertz generation in plasmas using two-color laser pulses.

    PubMed

    Peñano, Joseph; Sprangle, Phillip; Hafizi, Bahman; Gordon, Daniel; Serafim, Philip

    2010-02-01

    We analyze the generation of terahertz radiation when an intense, short laser pulse is mixed with its frequency-doubled counterpart in plasma. The nonlinear coupling of the fundamental and the frequency-doubled laser pulses in plasma is shown to be characterized by a third order susceptibility which has a time dependence characteristic of the laser pulse durations. The terahertz generation process depends on the relative polarizations of the lasers and the terahertz frequency is omega approximately 1/tau(L), where tau(L) is the laser pulse duration. Since the laser pulse duration is typically in the picosecond or subpicosecond regime the resulting radiation is in the terahertz or multiterahertz regime. To obtain the third order susceptibility we solve the plasma fluid equations correct to third order in the laser fields, including both the relativistic and ponderomotive force terms. The relativistic and ponderomotive contributions to the susceptibility nearly cancel in the absence of electron collisions. Therefore, in this terahertz generation mechanism collisional effects play a critical role. Consistent with recent experimental observations, our model shows that (1) the terahertz field amplitude is proportional to I(1) square root I(2), where I(1) and I(2) are the intensities of the fundamental and second harmonic laser pulses, respectively, (2) the terahertz emission is maximized when the polarization of the laser beams and the terahertz are aligned, (3) for typical experimental parameters, the emitted terahertz field amplitude is on the order of tens of kilovolts/cm with duration comparable to that of the drive laser pulses, and (4) the direction of terahertz emission depends sensitively on experimental parameters. PMID:20365665

  10. Terahertz generation in plasmas using two-color laser pulses

    SciTech Connect

    Penano, Joseph; Sprangle, Phillip; Gordon, Daniel; Hafizi, Bahman; Serafim, Philip

    2010-02-15

    We analyze the generation of terahertz radiation when an intense, short laser pulse is mixed with its frequency-doubled counterpart in plasma. The nonlinear coupling of the fundamental and the frequency-doubled laser pulses in plasma is shown to be characterized by a third order susceptibility which has a time dependence characteristic of the laser pulse durations. The terahertz generation process depends on the relative polarizations of the lasers and the terahertz frequency is omegaapprox1/tau{sub L}, where tau{sub L} is the laser pulse duration. Since the laser pulse duration is typically in the picosecond or subpicosecond regime the resulting radiation is in the terahertz or multiterahertz regime. To obtain the third order susceptibility we solve the plasma fluid equations correct to third order in the laser fields, including both the relativistic and ponderomotive force terms. The relativistic and ponderomotive contributions to the susceptibility nearly cancel in the absence of electron collisions. Therefore, in this terahertz generation mechanism collisional effects play a critical role. Consistent with recent experimental observations, our model shows that (1) the terahertz field amplitude is proportional to I{sub 1}sq root(I{sub 2}), where I{sub 1} and I{sub 2} are the intensities of the fundamental and second harmonic laser pulses, respectively, (2) the terahertz emission is maximized when the polarization of the laser beams and the terahertz are aligned, (3) for typical experimental parameters, the emitted terahertz field amplitude is on the order of tens of kilovolts/cm with duration comparable to that of the drive laser pulses, and (4) the direction of terahertz emission depends sensitively on experimental parameters.

  11. Effects of laser plasma on damage in optical glass induced by pulsed lasers

    NASA Astrophysics Data System (ADS)

    Han, Jinghua; Li, Yaguo; He, Changtao; Zhang, Qiuhui; Niu, Ruihua; Yang, Liming; Feng, Guoying

    2012-12-01

    Laser-induced plasma can expedite the deposition of incident laser energy and the laser-induced damage in optical glass is considerably affected by the magnitude and distribution of the plasma shock wave. The spatial distribution of energy deposition and expansion pressure of the laser plasma shock wave is analyzed based on the moving breakdown model. Furthermore, damage morphologies are discussed in light of the spatial distribution of pressure and glass properties. It was found that with the increase of laser pulse energy, the shock wave expands rapidly in the direction opposite to the incident laser, resulting in that the damage morphologies transform from sphere to spindle gradually. The laser energy deposits mostly in a narrow plasma channel. The diffusion of the plasma with high temperature and pressure leads to the shock wave; the intensity of which decreases sharply with the axial distance from the centerline. As a consequence, the glass near the centerline fractures and melts, and the refractive index also changes near the end of cracks.

  12. Laser-plasma-interaction experiments using multikilojoule lasers

    SciTech Connect

    Drake, R.P.

    1987-07-01

    This paper summarizes the results of several laser-plasma-interaction experiments using multikilojoule lasers, and considers their implications for laser fusion. The experiments used 1.06, 0.53, 0.35, and 0.26 ..mu..m light to produce relatively large, warm, planar plasmas and to study the effect of laser wavelength and density-gradient scale length on the Stimulated Raman Scattering and on the scattering of light at frequencies near the incident laser frequency by Stimulated Brillouin Scattering or other processes. The results of these experiments suggest that some laser wavelength between 0.2 and 0.6 ..mu..m will be required for high-gain laser fusion.

  13. Influence of Ambient Plasmas to the Field Dynamics of Laser Driven Mass-Limited Targets

    SciTech Connect

    Schnuerer, M.; Sokollik, T.; Steinke, S.; Nickles, P. V.; Sandner, W.; Toncian, T.; Amin, M.; Willi, O.; Andreev, A. A.

    2010-02-02

    Dilute plasmas surrounding mass-limited targets provide sufficient current for influencing strong fields, which are built up due to the interaction of an intense and ultrafast laser pulse. Such situation occurs, where evaporation of the target surface is present. The high-intensity laser pulse interacts with the quasi-isolated mass-limited target and the spatial wings of the intensity distribution account for ionization of the ambient plasma. A fast change of strong electrical fields following intense laser irradiation of water droplets (16 micron diameter) has been measured with proton imaging. An analytical model explains charge transport accounting for the observation.

  14. Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

    PubMed Central

    Hu, Wenqian; Shin, Yung C.; King, Galen B.

    2012-01-01

    Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11. Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps). Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators. PMID:22806170

  15. Multiple pulse resonantly enhanced laser plasma wakefield acceleration

    SciTech Connect

    Corner, L.; Walczak, R.; Nevay, L. J.; Dann, S.; Hooker, S. M.; Bourgeois, N.; Cowley, J.

    2012-12-21

    We present an outline of experiments being conducted at Oxford University on multiple-pulse, resonantly-enhanced laser plasma wakefield acceleration. This method of laser plasma acceleration uses trains of optimally spaced low energy short pulses to drive plasma oscillations and may enable laser plasma accelerators to be driven by compact and efficient fibre laser sources operating at high repetition rates.

  16. Quasitransient backward Raman amplification of powerful laser pulses in dense plasmas with multicharged ions

    NASA Astrophysics Data System (ADS)

    Malkin, V. M.; Fisch, N. J.

    2010-07-01

    The range of plasma parameters, where the efficient quasitransient backward Raman amplification (QBRA) of powerful laser pulses is possible, is determined for dense plasmas with multicharged ions. Approximate scalings that portray in a simple way the efficient QBRA range in multidimensional parameter space are found. The calculation, applicable to infrared, ultraviolet, soft x-ray, and x-ray laser pulses, takes into account plasma heating by the lasers. It is shown that efficient QBRA can survive even the nonsaturated linear Landau damping of the Langmuir wave mediating the energy transfer from the pump to the seed laser pulse; moreover, this survival does not require very intense seed laser pulses.

  17. Experimental studies of laser guiding in plasma channels

    SciTech Connect

    Volfbeyn, P.; Leemans, W.P.

    1998-07-01

    The authors present results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme is proposed and experimentally tested in hydrogen and nitrogen. It makes use of two laser pulses. The Ignitor, an ultrashort (< 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used subsequently to heat the existing spark via inverse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows, creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. The channel density was diagnosed with time resolved longitudinal interferometry. From these measurements the plasma temperature was inferred. The guiding properties of the channels were tested by injecting a > 5 {times} 10{sup 17} W/cm{sup 2}, 75 fs laser pulse.

  18. Towards manipulating relativistic laser pulses with micro-tube plasma lenses

    NASA Astrophysics Data System (ADS)

    Ji, L. L.; Snyder, J.; Pukhov, A.; Freeman, R. R.; Akli, K. U.

    2016-03-01

    Efficient coupling of intense laser pulses to solid-density matter is critical to many applications including ion acceleration for cancer therapy. At relativistic intensities, the focus has been mainly on investigating various laser beams irradiating initially overdense flat interfaces with little or no control over the interaction. Here, we propose a novel approach that leverages recent advancements in 3D direct laser writing (DLW) of materials and high contrast lasers to manipulate the laser-matter interactions on the micro-scales. We demonstrate, via simulations, that usable intensities ≥1023 Wcm‑2 could be achieved with current tabletop lasers coupled to micro-engineered plasma lenses. We show that these plasma optical elements act as a lens to focus laser light. These results open new paths to engineering light-matter interactions at ultra-relativistic intensities.

  19. Towards manipulating relativistic laser pulses with micro-tube plasma lenses.

    PubMed

    Ji, L L; Snyder, J; Pukhov, A; Freeman, R R; Akli, K U

    2016-01-01

    Efficient coupling of intense laser pulses to solid-density matter is critical to many applications including ion acceleration for cancer therapy. At relativistic intensities, the focus has been mainly on investigating various laser beams irradiating initially overdense flat interfaces with little or no control over the interaction. Here, we propose a novel approach that leverages recent advancements in 3D direct laser writing (DLW) of materials and high contrast lasers to manipulate the laser-matter interactions on the micro-scales. We demonstrate, via simulations, that usable intensities ≥10(23) Wcm(-2) could be achieved with current tabletop lasers coupled to micro-engineered plasma lenses. We show that these plasma optical elements act as a lens to focus laser light. These results open new paths to engineering light-matter interactions at ultra-relativistic intensities. PMID:26979657

  20. Towards manipulating relativistic laser pulses with micro-tube plasma lenses

    PubMed Central

    Ji, L. L.; Snyder, J.; Pukhov, A.; Freeman, R. R.; Akli, K. U.

    2016-01-01

    Efficient coupling of intense laser pulses to solid-density matter is critical to many applications including ion acceleration for cancer therapy. At relativistic intensities, the focus has been mainly on investigating various laser beams irradiating initially overdense flat interfaces with little or no control over the interaction. Here, we propose a novel approach that leverages recent advancements in 3D direct laser writing (DLW) of materials and high contrast lasers to manipulate the laser-matter interactions on the micro-scales. We demonstrate, via simulations, that usable intensities ≥1023 Wcm−2 could be achieved with current tabletop lasers coupled to micro-engineered plasma lenses. We show that these plasma optical elements act as a lens to focus laser light. These results open new paths to engineering light-matter interactions at ultra-relativistic intensities. PMID:26979657

  1. Mechanism of generating fast electrons by an intense laser at a steep overdense interface.

    PubMed

    May, J; Tonge, J; Fiuza, F; Fonseca, R A; Silva, L O; Ren, C; Mori, W B

    2011-08-01

    The acceleration and heating of electrons by an intense laser normally incident on a steep overdense plasma interface is investigated using the particle-in-cell code osiris. Energetic electrons are generated by the laser's electric field in the vacuum region within λ/4 of the surface. Only those electrons which originate within the plasma with a sufficiently large transverse momentum can escape the plasma. This mechanism relies on the standing wave structure created by the incoming and reflected wave and is therefore very different for linear and circularly polarized light. PMID:21929052

  2. Numerical simulation study of positron production by intense laser-accelerated electrons

    SciTech Connect

    Yan, Yonghong; Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 ; Dong, Kegong; Wu, Yuchi; Zhang, Bo; Gu, Yuqiu; Yao, Zeen

    2013-10-15

    Positron production by ultra-intense laser-accelerated electrons has been studied with two-dimensional particle-in-cell and Monte Carlo simulations. The dependence of the positron yield on plasma density, plasma length, and converter thickness was investigated in detail with fixed parameters of a typical 100 TW laser system. The results show that with the optimal plasma and converter parameters a positron beam containing up to 1.9 × 10{sup 10} positrons can be generated, which has a small divergence angle (10°), a high temperature (67.2 MeV), and a short pulse duration (1.7 ps)

  3. Observations of the filamentation of high-intensity laser-produced electron beams

    SciTech Connect

    Wei, M.S.; Beg, F.N.; Dangor, A.E.; Gopal, A.; Tatarakis, M.; Krushelnick, K.; Clark, E.L.; Evans, R.G.; Ledingham, K.W.D.; McKenna, P.; Norreys, P.A.; Zepf, M.

    2004-11-01

    Filamented electron beams have been observed to be emitted from the rear of thin solid targets irradiated by a high-intensity short-pulse laser when there is low-density plasma present at the back of the target. These observations are consistent with a laser-generated beam of relativistic electrons propagating through the target, which is subsequently fragmented by a Weibel-like instability in the low-density plasma at the rear. These measurements are in agreement with particle-in-cell simulations and theory, since the filamentation instability is predicted to be dramatically enhanced when the electron beam density approaches that of the background plasma.

  4. Mechanism of generating fast electrons by an intense laser at a steep overdense interface

    SciTech Connect

    May, J.; Tonge, J.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

    2011-08-15

    The acceleration and heating of electrons by an intense laser normally incident on a steep overdense plasma interface is investigated using the particle-in-cell code osiris. Energetic electrons are generated by the laser's electric field in the vacuum region within {lambda}/4 of the surface. Only those electrons which originate within the plasma with a sufficiently large transverse momentum can escape the plasma. This mechanism relies on the standing wave structure created by the incoming and reflected wave and is therefore very different for linear and circularly polarized light.

  5. Ponderomotive self-focusing of Gaussian laser beam in warm collisional plasma

    SciTech Connect

    Jafari Milani, M. R.; Niknam, A. R.; Farahbod, A. H.

    2014-06-15

    The propagation characteristics of a Gaussian laser beam through warm collisional plasma are investigated by considering the ponderomotive force nonlinearity and the complex eikonal function. By introducing the dielectric permittivity of warm unmagnetized plasma and using the WKB and paraxial ray approximations, the coupled differential equations defining the variations of laser beam parameters are obtained and solved numerically. Effects of laser and plasma parameters such as the collision frequency, the initial laser intensity and its spot size on the beam width parameter and the axis laser intensity distribution are analyzed. It is shown that, self-focusing of the laser beam takes place faster by increasing the collision frequency and initial laser spot size and then after some distance propagation the laser beam abruptly loses its initial diameter and vastly diverges. Furthermore, the modified electron density distribution is obtained and the collision frequency effect on this distribution is studied.

  6. Study of laser plasma interactions in the relativistic regime

    SciTech Connect

    Umstadter, D.

    1997-08-13

    We discuss the first experimental demonstration of electron acceleration by a laser wakefield over instances greater than a Rayleigh range (or the distance a laser normally propagates in vacuum). A self-modulated laser wakefield plasma wave is shown to have a field gradient that exceeds that of an RF linac by four orders of magnitude (E => 200 GV/m) and accelerates electrons with over 1-nC of charge per bunch in a beam with space-charge-limited emittance (1 mm-mrad). Above a laser power threshold, a plasma channel, created by the intense ultrashort laser pulse (I approx. 4 x1018 W/CM2, gamma = 1 micron, r = 400 fs), was found to increase the laser propagation distance, decrease the electron beam divergence, and increase the electron energy. The plasma wave, directly measured with coherent Thomson scattering is shown to damp-due to beam loading-in a duration of 1.5 ps or approx. 100 plasma periods. These results may have important implications for the proposed fast ignitor concept.

  7. Plasma lenses for ultrashort multi-petawatt laser pulses

    SciTech Connect

    Palastro, J. P.; Gordon, D.; Hafizi, B.; Johnson, L. A.; Peñano, J.; Hubbard, R. F.; Helle, M.; Kaganovich, D.

    2015-12-15

    An ideal plasma lens can provide the focusing power of a small f-number, solid-state focusing optic at a fraction of the diameter. An ideal plasma lens, however, relies on a steady-state, linear laser pulse-plasma interaction. Ultrashort multi-petawatt (MPW) pulses possess broad bandwidths and extreme intensities, and, as a result, their interaction with the plasma lens is neither steady state nor linear. Here, we examine nonlinear and time-dependent modifications to plasma lens focusing, and show that these result in chromatic and phase aberrations and amplitude distortion. We find that a plasma lens can provide enhanced focusing for 30 fs pulses with peak power up to ∼1 PW. The performance degrades through the MPW regime, until finally a focusing penalty is incurred at ∼10 PW.

  8. Plasma lenses for ultrashort multi-petawatt laser pulses

    NASA Astrophysics Data System (ADS)

    Palastro, J. P.; Gordon, D.; Hafizi, B.; Johnson, L. A.; Peñano, J.; Hubbard, R. F.; Helle, M.; Kaganovich, D.

    2015-12-01

    An ideal plasma lens can provide the focusing power of a small f-number, solid-state focusing optic at a fraction of the diameter. An ideal plasma lens, however, relies on a steady-state, linear laser pulse-plasma interaction. Ultrashort multi-petawatt (MPW) pulses possess broad bandwidths and extreme intensities, and, as a result, their interaction with the plasma lens is neither steady state nor linear. Here, we examine nonlinear and time-dependent modifications to plasma lens focusing, and show that these result in chromatic and phase aberrations and amplitude distortion. We find that a plasma lens can provide enhanced focusing for 30 fs pulses with peak power up to ˜1 PW. The performance degrades through the MPW regime, until finally a focusing penalty is incurred at ˜10 PW.

  9. Persistence of uranium emission in laser-produced plasmas

    SciTech Connect

    LaHaye, N. L.; Harilal, S. S. Diwakar, P. K.; Hassanein, A.

    2014-04-28

    Detection of uranium and other nuclear materials is of the utmost importance for nuclear safeguards and security. Optical emission spectroscopy of laser-ablated U plasmas has been presented as a stand-off, portable analytical method that can yield accurate qualitative and quantitative elemental analysis of a variety of samples. In this study, optimal laser ablation and ambient conditions are explored, as well as the spatio-temporal evolution of the plasma for spectral analysis of excited U species in a glass matrix. Various Ar pressures were explored to investigate the role that plasma collisional effects and confinement have on spectral line emission enhancement and persistence. The plasma-ambient gas interaction was also investigated using spatially resolved spectra and optical time-of-flight measurements. The results indicate that ambient conditions play a very important role in spectral emission intensity as well as the persistence of excited neutral U emission lines, influencing the appropriate spectral acquisition conditions.

  10. Intense terahertz-pulse generation by four-wave mixing process in induced gas plasma

    NASA Astrophysics Data System (ADS)

    Wicharn, S.; Buranasiri, P.

    2015-08-01

    In this article, we have numerically investigated an intense terahertz (THz) pulses generation in gaseous plasma based on the third-order nonlinear effect, four-wave mixing rectification (FWMR). We have proposed that the fundamental fields and second-harmonic field of ultra-short pulse lasers are combined and focused into a very small gas chamber to induce a gaseous plasma, which intense THz pulse is produced. To understand the THz generation process, the first-order multiple-scale perturbation method (MSPM) has been utilized to derive a set of nonlinear coupled-mode equations for interacting fields such as two fundamental fields, a second-harmonic field, and a THz field. Then, we have simulate the intense THz-pulse generation by using split step-beam propagation method (SS-BPM) and calculated output THz intensities. Finally, the output THz intensities generated from induced air, nitrogen, and argon plasma have been compared.

  11. Resonant self-trapping of high intensity Bessel beams in underdense plasmas.

    PubMed

    Fan, J; Parra, E; Kim, K Y; Alexeev, I; Milchberg, H M; Cooley, J; Antonsen, T M

    2002-05-01

    We present a comprehensive report based on recent work [Phys. Rev. Lett. 84, 3085 (2000)] on resonant self-trapping and enhanced absorption of high power Bessel beams in underdense plasmas. The trapping resonance is strongly dependent on initial gas pressure, Bessel-beam geometry, and laser wavelength. Analytic estimates, and simulations using a one-dimensional Bessel-beam-plasma interaction code consistently explain the experimental observations. These results are for longer, moderate intensity pulses where the self-trapping channel is induced by laser-heated plasma thermal pressure. To explore the extension of this effect to ultrashort, intense pulsed Bessel beams, we perform propagation simulations using the code WAKE [Phys. Rev. E 53, R2068 (1996)]. We find that self-trapping can occur as a result of a plasma refractive index channel induced by the combined effects of relativistic motion of electrons and their ponderomotive expulsion. PMID:12059716

  12. Reinjection of transmitted laser light into laser-produced plasma for efficient laser ignition.

    PubMed

    Endo, Takuma; Takenaka, Yuhei; Sako, Yoshiyuki; Honda, Tomohisa; Johzaki, Tomoyuki; Namba, Shinichi

    2016-02-10

    For improving the laser absorption efficiency in laser ignition, the transmitted laser light was returned to the laser-produced plasma by using a corner cube. In the experiments, the transmitted light was reinjected into the plasma at different times. The laser absorption efficiency was found to be substantially improved when the transmitted light was reinjected into the plasma after adequate plasma expansion. Furthermore, through visualization experiments on gas-dynamics phenomena, it was found that the reinjection of the transmitted light affected not only the laser absorption efficiency but also the gas dynamics after breakdown, and thereby the initial flame kernel development. PMID:26906388

  13. Characteristics of optical emission intensities and bubblelike phenomena induced by laser ablation in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Takada, Noriharu; Machmudah, Siti; Goto, Hiroshi; Wahyudiono; Goto, Motonobu; Sasaki, Koichi

    2014-01-01

    We investigated the characteristics of laser ablation phenomena in supercritical fluids by optical emission and shadowgraph imaging. In comparison with laser ablation in liquid H2O, the optical emission of a laser ablation plasma produced in supercritical H2O had a longer lifetime and a larger transport length. It was found in supercritical CO2 that laser ablation plasmas with bright optical emissions were produced at a mass density of approximately 300 kg/m3. A clear correlation between the optical emission intensity and the density fluctuation was not observed in our experimental results, which were obtained in a regime deviated from the critical point. Bubblelike hollows were observed by shadowgraph imaging in both supercritical H2O and CO2. The dynamics of the bubblelike hollows were different from the dynamics of a cavitation bubble induced by laser ablation in a liquid medium but relatively similar to the dynamics of ambient gas in gas-phase laser ablation.

  14. Laser ablation inductively coupled plasma mass spectrometry

    SciTech Connect

    Durrant, S.F.

    1996-07-01

    Laser ablation for solid sample introduction to inductively coupled plasma mass spectrometry for bulk and spatially-resolved elemental analysis is briefly reviewed. {copyright} {ital 1996 American Institute of Physics.}

  15. Two-dimensional fluorescence spectroscopy of laser-produced plasmas.

    PubMed

    Harilal, S S; LaHaye, N L; Phillips, M C

    2016-08-01

    We use a two-dimensional laser-induced fluorescence spectroscopy technique to measure the coupled absorption and emission properties of atomic species in plasmas produced via laser ablation of a solid aluminum target at atmospheric pressure. Emission spectra from the Al I 394.4 nm and Al I 396.15 nm transitions are measured while a frequency-doubled, continuous wave (cw) Ti:sapphire laser is tuned across the Al I 396.15 nm transition. The resulting two-dimensional spectra show the energy coupling between the two transitions via increased emission intensity for both transitions during resonant absorption of the cw laser at one transition. Time-delayed, gated detection of the emission spectrum is used to isolate resonantly excited fluorescence emission from thermally excited emission from the plasma. In addition, the tunable cw laser measures the absorption spectrum of the Al transition with ultrahigh resolution after the plasma has cooled, resulting in narrower spectral linewidths than observed in emission spectra. Our results highlight that fluorescence spectroscopy employing cw laser re-excitation after pulsed laser ablation combines benefits of both traditional emission and absorption spectroscopic methods. PMID:27472615

  16. Scaling of Ion Acceleration in Super Intense Laser Matter Interaction in Radiative Damping Regime

    NASA Astrophysics Data System (ADS)

    Pandit, Rishi; Sentoku, Yasuhiko; Ackad, Edward

    2015-11-01

    We had derived the radiation reaction terms including the higher orders and implemented in PICLS codes [R. Pandit and Y. Sentoku, Phys. Plasmas 19, 073304 (2012)]. It was found that higher order terms of radiation reaction reduce the ponderomotive force as well as the photon pressure. The ponderomotive scaling, in super intense laser matter interactions, changes due to the decrease of the ponderomotive force on the electron and ion's accelerations. A new scaling of ion acceleration has been derived which depends on the laser intensity and oscillatory energy of electron. At 1023 W/cm2 almost half of the ponderomotive force is damped due to higher order terms. We will show how the theoretical result compares with PICLS simulations by varying laser intensities to understand the effect of the reduced ponderomotive force in super intense laser matter interaction.

  17. Spectroscopic Analysis of High Intensity Laser Beam Jets Interaction Experiments on the Leopard Laser at UNR

    NASA Astrophysics Data System (ADS)

    Petkov, E. E.; Weller, M. E.; Kantsyrev, V. L.; Safronova, A. S.; Moschella, J. J.; Shrestha, I.; Shlyapsteva, V. V.; Stafford, A.; Keim, S. F.; University of Nevada Reno Team

    2013-10-01

    Results of Ar gas-puff experiments performed on the high power Leopard laser at UNR are presented. Flux density of laser radiation in focal spot was up to 2 × 1016 W/cm2 (pulse duration was 0.8 ns and laser wavelength was 1.057 μm). Specifically, spectroscopic analysis of K-shell Ar spectra are investigated and compared as functions of the orientation of the laser beam to linear gas jet. The laser beam axis was positioned either along the jet plane or orthogonal to it at a distance of 1 mm from the nozzle output. The diagnostics used included a time-integrated x-ray spectrometer along with a set of filtered Si diodes with various cutoff energies. In order to identify lines, a non-local thermodynamic equilibrium (non-LTE) kinetic model was utilized and was also used to determine plasma parameters such as electron temperature and density. The importance of the spectroscopic study of high intensity laser beam-jets interaction experiments is discussed. This work was supported by the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-13-1-0033, to University of Nevada, Reno, and in part by the DOE/NNSA Cooperative agreements DE-NA0001984 and DE-FC52-06NA27616.

  18. LASER-ELECTRON COMPTON INTERACTION IN PLASMA CHANNELS

    SciTech Connect

    POGORELSKY,I.V.

    1998-10-01

    A concept of high intensity femtosecond laser synchrotron source (LSS) is based on Compton backscattering of focused electron and laser beams. The short Rayleigh length of the focused laser beam limits the length of interaction to a few picoseconds. However, the technology of the high repetition rate high-average power picosecond lasers required for high put through LSS applications is not developed yet. Another problem associated with the picosecond laser pulses is undesirable nonlinear effects occurring when the laser photons are concentrated in a short time interval. To avoid the nonlinear Compton scattering, the laser beam has to be split, and the required hard radiation flux is accumulated over a number of consecutive interactions that complicates the LSS design. In order to relieve the technological constraints and achieve a practically feasible high-power laser synchrotron source, we propose to confine the laser-electron interaction region in the extended plasma channel. This approach permits to use nanosecond laser pulses instead of the picosecond pulses. That helps to avoid the nonlinear Compton scattering regime and allows to utilize already existing technology of the high-repetition rate TEA CO{sub 2} lasers operating at the atmospheric pressure. We demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider.

  19. Plasma effects in high harmonic spectra from ultrarelativistic laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Boyd, T. J. M.; Ondarza-Rovira, R.

    2016-03-01

    A single particle model has been applied to examine the competition between radiation from a strong Langmuir source and coherent bremsstrahlung in ultra-relativistic laser-plasma interactions. Output from this model shows generally satisfactory agreement with that from particle-in-cell (PIC) simulations, in particular reproducing spectra characterised by a decay index p = 5 / 3. At the highest intensities considered, both model and PIC spectra show the competing contribution from relativistic electron bremsstrahlung, characterised by a further relaxation in the decay index to p = 2 / 3. Combinations of laser and plasma parameters have been identified that define regions of parameter space where one or other emission is dominant.

  20. Probing Ultrafast Processes in Intense Laser--Matter Interactions

    NASA Astrophysics Data System (ADS)

    Hu, S. X.

    2012-06-01

    This talk reports on computational studies of using sub-femtosecond/attosecond extreme ultraviolet and soft-x-ray pulses to probe ultrafast processes in intense laser interactions with atoms, molecules, and plasmas. By developing and optimizing the finite-element discrete-variable-representation (FEDVR) combined with the real-space product (RSP) algorithm, a powerful computational method is generated, enabling one to explore transient processes in quantum, few-body systems non-perturbatively driven by strong electromagnetic fields. These studies include attosecond photoelectron microscopy of molecular structures, ultrafast probing ion--atom collisions, as well as exploring electron correlations in single-/double-ionization of helium in intense laser fields. Detailed discussions on what has been learned and what can be done in experiments will be presented. This work was partially supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302, the University of Rochester, and the New York State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this article. Computations have been conducted utilizing the Kraken Supercomputer of the National Institute of Computational Sciences (NICS) at Oak Ridge National Laboratory.

  1. An ultracompact X-ray source based on a laser-plasma undulator.

    PubMed

    Andriyash, I A; Lehe, R; Lifschitz, A; Thaury, C; Rax, J-M; Krushelnick, K; Malka, V

    2014-01-01

    The capability of plasmas to sustain ultrahigh electric fields has attracted considerable interest over the last decades and has given rise to laser-plasma engineering. Today, plasmas are commonly used for accelerating and collimating relativistic electrons, or to manipulate intense laser pulses. Here we propose an ultracompact plasma undulator that combines plasma technology and nanoengineering. When coupled with a laser-plasma accelerator, this undulator constitutes a millimetre-sized synchrotron radiation source of X-rays. The undulator consists of an array of nanowires, which are ionized by the laser pulse exiting from the accelerator. The strong charge-separation field, arising around the wires, efficiently wiggles the laser-accelerated electrons. We demonstrate that this system can produce bright, collimated and tunable beams of photons with 10-100 keV energies. This concept opens a path towards a new generation of compact synchrotron sources based on nanostructured plasmas. PMID:25145401

  2. An ultracompact X-ray source based on a laser-plasma undulator

    NASA Astrophysics Data System (ADS)

    Andriyash, I. A.; Lehe, R.; Lifschitz, A.; Thaury, C.; Rax, J.-M.; Krushelnick, K.; Malka, V.

    2014-08-01

    The capability of plasmas to sustain ultrahigh electric fields has attracted considerable interest over the last decades and has given rise to laser-plasma engineering. Today, plasmas are commonly used for accelerating and collimating relativistic electrons, or to manipulate intense laser pulses. Here we propose an ultracompact plasma undulator that combines plasma technology and nanoengineering. When coupled with a laser-plasma accelerator, this undulator constitutes a millimetre-sized synchrotron radiation source of X-rays. The undulator consists of an array of nanowires, which are ionized by the laser pulse exiting from the accelerator. The strong charge-separation field, arising around the wires, efficiently wiggles the laser-accelerated electrons. We demonstrate that this system can produce bright, collimated and tunable beams of photons with 10-100 keV energies. This concept opens a path towards a new generation of compact synchrotron sources based on nanostructured plasmas.

  3. Terahertz generation in multiple laser-induced air plasmas

    SciTech Connect

    Chen, M.-K.; Kim, Jae Hun; Yang, C.-E.; Yin, Stuart Shizhuo; Hui Rongqing; Ruffin, Paul

    2008-12-08

    An investigation of the terahertz wave generation in multiple laser-induced air plasmas is presented. First, it is demonstrated that the intensity of the terahertz wave increases as the number of air plasmas increases. Second, the physical mechanism of this enhancement effect of the terahertz generation is studied by quantitatively measuring the intensity of the generated terahertz wave as a function of phase difference between adjacent air plasmas. It is found out that the superposition is the main mechanism to cause this enhancement. Thus, the results obtained in this paper not only provide a technique to generate stronger terahertz wave but also enable a better understanding of the mechanism of the terahertz generation in air plasma.

  4. Laser channeling in mm-scale underdense plasmas of fast ignition targets

    NASA Astrophysics Data System (ADS)

    Ren, C.; Li, G.; Yan, R.; Wang, T.-L.; Tonge, J.; Mori, W. B.

    2008-04-01

    In the fast ignition approach to laser fusion, non-linear laser-plasma interactions could cause significant energy loss for an ignition laser in an underdense plasma. One way to avoid this is to use a channeling pulse to create a low-density channel for the ignition pulse. Two dimensional Particle-in-cell simulations show that laser channeling in mm-scale underdense plasmas has many new phenomena that are not present in previous short-scale experiments and simulations, including plasma buildup to nc in front of the laser, laser hosing/refraction, channel bifurcation, and self-correction and electron heating to relativistic temperatures. The channeling speed is much less than the linear group velocity of the laser. The simulations find that low- intensity channeling pulses are preferred to minimize the required laser energy. The channel is also shown to significantly increase the transmission of an ignition pulse.

  5. Subsurface plasma in beam of continuous CO2-laser

    NASA Astrophysics Data System (ADS)

    Danytsikov, Y. V.; Dymshakov, V. A.; Lebedev, F. V.; Pismennyy, V. D.; Ryazanov, A. V.

    1986-03-01

    Experiments performed at the Institute of Atomic Energy established the conditions for formation of subsurface plasma in substances by laser radiation and its characteristics. A quasi-continuous CO2 laser emitting square pulses of 0.1 to 1.0 ms duration and 1 to 10 kW power as well as a continuous CO2 laser served as radiation sources. Radiation was focused on spots 0.1 to 0.5 mm in diameter and maintained at levels ensuring constant power density during the interaction time, while the temperature of the target surface was measured continuously. Metals, graphite and dielectric materials were tested with laser action taking place in air N2 + O2 mixtures, Ar or He atmosphere under pressures of 0.01 to 1.0 atm. Data on radiation intensity thresholds for evaporation and plasma formation were obtained. On the basis of these thresholds, combined with data on energy balance and the temperature profile in plasma layers, a universal state diagram was constructed for subsurface plasma with nonquantified surface temperature and radiation intensity coordinates.

  6. Propagation of ultraintense laser pulses through overdense plasma layers

    NASA Astrophysics Data System (ADS)

    Guérin, S.; Mora, P.; Adam, J. C.; Héron, A.; Laval, G.

    1996-07-01

    Due to relativistic effects, a large amplitude electromagnetic wave can propagate in a classically overdense plasma with ω2p≳ω2≳ω2p/γ, where ωp is the plasma frequency, ω the laser frequency, and γ the relativistic factor of an electron in the laser field. Particle-in-cell simulations are used to study the interaction of an ultrahigh intensity laser pulse in normal incidence on a one-dimensional preformed plasma layer. Both electrons and ions dynamics are included. The width of the layer is 10 to 30 μm and the plasma is characterized by (ωp/ω)2=1.5. During the penetration of the electromagnetic wave a large longitudinal electric field is generated. It results in a strong longitudinal heating of electrons which reach relativistic temperatures. This heating further lowers the effective plasma frequency ωp/γ so the layer becomes almost transparent after the plasma crossing by the wave front. Velocity of the wave front, reflection and transmission rates are studied as functions of the incident energy flux, the plasma thickness, and the pulse duration.

  7. Bulk resonance absorption induced by relativistic effects in laser-plasma interaction

    SciTech Connect

    Ding Wenjun; Sheng, Z.-M.; Zhang, J.; Yu, M. Y.

    2009-04-15

    Resonance absorption in relativistic laser-plasma interaction is studied via two-dimensional particle-in-cell simulation. As the laser intensity increases from the linear regime, the absorption rate first decreases due to relativistic modulation of the electron plasma oscillations excited at the mode conversion layer. However, the trend reverses after a critical intensity. The reversal can be attributed to the fact that the relativistic critical layer depends on the local intensity of the laser pulse, so that instead of occurring in a thin layer, resonance absorption occurs in a plasma bulk region, leading absorption rate increase. The reflected-light spectrum also shows broadening and splitting of the harmonics at high laser intensities, which can be attributed to critical-surface oscillations driven by the laser ponderomotive force.

  8. LASER PLASMA AND LASER APPLICATIONS: Plasma transparency in laser absorption waves in metal capillaries

    NASA Astrophysics Data System (ADS)

    Anisimov, V. N.; Kozolupenko, A. P.; Sebrant, A. Yu

    1988-12-01

    An experimental investigation was made of the plasma transparency to heating radiation in capillaries when absorption waves propagated in these capillaries as a result of interaction with a CO2 laser pulse of 5-μs duration. When the length of the capillary was in excess of 20 mm, total absorption of the radiation by the plasma was observed at air pressures of 1-100 kPa. When the capillary length was 12 mm, a partial recovery of the transparency took place. A comparison was made with the dynamics and recovery of the plasma transparency when breakdown of air took place near the free surface.

  9. Higher-order paraxial theory of the propagation of ring rippled laser beam in plasma: Relativistic ponderomotive regime

    SciTech Connect

    Purohit, Gunjan Rawat, Priyanka; Chauhan, Prashant; Mahmoud, Saleh T.

    2015-05-15

    This article presents higher-order paraxial theory (non-paraxial theory) for the ring ripple formation on an intense Gaussian laser beam and its propagation in plasma, taking into account the relativistic-ponderomotive nonlinearity. The intensity dependent dielectric constant of the plasma has been determined for the main laser beam and ring ripple superimposed on the main laser beam. The dielectric constant of the plasma is modified due to the contribution of the electric field vector of ring ripple. Nonlinear differential equations have been formulated to examine the growth of ring ripple in plasma, self focusing of main laser beam, and ring rippled laser beam in plasma using higher-order paraxial theory. These equations have been solved numerically for different laser intensities and plasma frequencies. The well established experimental laser and plasma parameters are used in numerical calculation. It is observed that the focusing of the laser beams (main and ring rippled) becomes fast in the nonparaxial region by expanding the eikonal and other relevant quantities up to the fourth power of r. The splitted profile of laser beam in the plasma is observed due to uneven focusing/defocusing of the axial and off-axial rays. The growths of ring ripple increase when the laser beam intensity increases. Furthermore, the intensity profile of ring rippled laser beam gets modified due to the contribution of growth rate.

  10. Validating Laser-Induced Birefringence Theory with Plasma Interferometry

    SciTech Connect

    Chen, Cecilia

    2015-09-02

    Intense laser beams crossing paths in plasma is theorized to induce birefringence in the medium, resulting from density and refractive index modulations that affect the polarization of incoming light. The goal of the associated experiment, conducted on Janus at Lawrence Livermore’s Jupiter Laser Facility, was to create a tunable laser-plasma waveplate to verify the relationship between dephasing angle and beam intensity, plasma density, plasma temperature, and interaction length. Interferometry analysis of the plasma channel was performed to obtain a density map and to constrain temperature measured from Thomson scattering. Various analysis techniques, including Fast Fourier transform (FFT) and two variations of fringe-counting, were tried because interferograms captured in this experiment contained unusual features such as fringe discontinuity at channel edges, saddle points, and islands. The chosen method is flexible, semi-automated, and uses a fringe tracking algorithm on a reduced image of pre-traced synthetic fringes. Ultimately, a maximum dephasing angle of 49.6° was achieved using a 1200 μm interaction length, and the experimental results appear to agree with predictions.

  11. Plasma Parameter of a Capillary Discharge-Produced Plasma Channel to Guide an Ultrashort Laser Pulse

    SciTech Connect

    Higashiguchi, Takeshi; Terauchi, Hiromitsu; Bai, Jin-xiang; Yugami, Noboru

    2009-01-22

    We have observed the optical guiding of a 100-fs laser pulse with the laser intensity in the range of 10{sup 16} W/cm{sup 2} using a 1.5-cm long capillary discharge-produced plasma channel for compact electron acceleration applications. The optical pulse propagation using the plasma channel is achieved with the electron densities of 10{sup 17}-10{sup 18} cm{sup -3} and the electron temperatures of 0.5-4 eV at a discharge time delay of around 150 ns and a discharge current of 500 A with a pulse duration of 100-150 ns. An energy spectrum of the accelerated electrons from a laser-plasma acceleration scheme showed a peak at 1.3 MeV with a maximum energy tail of 1.6 MeV.

  12. Large aperture adaptive optics for intense lasers

    NASA Astrophysics Data System (ADS)

    Deneuville, François; Ropert, Laurent; Sauvageot, Paul; Theis, Sébastien

    2015-05-01

    ISP SYSTEM has developed a range of large aperture electro-mechanical deformable mirrors (DM) suitable for ultra short pulsed intense lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations thanks to electromechanical actuators driven by stepper motors. DM design and assembly method have been adapted to large aperture beams and the performances were evaluated on a first application for a beam with a diameter of 250mm at 45° angle of incidence. A Strehl ratio above 0.9 was reached for this application. Simulations were correlated with measurements on optical bench and the design has been validated by calculation for very large aperture (up to Ø550mm). Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for actual MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The MD-AME mirrors can be adapted to circular, square or elliptical beams and they are compatible with all dielectric or metallic coatings.

  13. Self-regulated propagation of intense infrared pulses in elongated soft-x-ray plasma amplifiers

    NASA Astrophysics Data System (ADS)

    Oliva, Eduardo; Depresseux, Adrien; Tissandier, Fabien; Gautier, Julien; Sebban, Stéphane; Maynard, Gilles

    2015-08-01

    Increasing the electron density of collisionally pumped plasma-based soft-x-ray lasers offers promising opportunities to deliver ultrashort pulses. However, strong nonlinear effects, such as overionization-induced refraction and self-focusing, hinder the propagation of the laser beam and thus the generation of elongated volume of lasing ions to be pumped. Using a particle-in-cell code and a ray-tracing model we demonstrate that optically preformed waveguides allow for addressing those issues through a self-regulation regime between self-focusing and overionization processes. As a result, guiding intense pulses over several millimeters leads to the implementation of saturated plasma amplifiers.

  14. Laser-produced plasmas in medicine

    NASA Astrophysics Data System (ADS)

    Gitomer, Steven J.; Jones, Roger D.

    1990-06-01

    The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g. lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g. kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g. laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

  15. Laser-produced plasmas in medicine

    NASA Astrophysics Data System (ADS)

    Gitomer, S. J.; Jones, R. D.

    The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. Those areas of laser medicine are examined in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. Examples are examined for the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

  16. Laser-produced plasmas in medicine

    SciTech Connect

    Gitomer, S.J. ); Jones, R.D. . Applied Theoretical Physics Div.)

    1991-12-01

    The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photodynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper the authors examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation), and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented, along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

  17. Laser-produced plasmas in medicine

    SciTech Connect

    Gitomer, S.J.; Jones, R.D.

    1990-01-01

    The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included. 63 refs.

  18. COUNTER PROPAGATION OF ELECTRON AND CO2 LASER BEAMS IN A PLASMA CHANNEL.

    SciTech Connect

    HIROSE,T.; POGORELSKY,I.V.; BEN ZVI,I.; YAKIMENKO,V.; KUSCHE,K.; SIDDONS,P.; KUMITA,T.; KAMIYA,Y.; ZIGLER,A.; GREENBERG,B.; ET AL

    2002-11-12

    A high-energy CO{sub 2} laser is channeled in a capillary discharge. Occurrence of guiding conditions at a relatively low plasma density (<10{sup 18} cm{sup -3}) is confirmed by MHD simulations. Divergence of relativistic electron beam changes depending on the plasma density. Counter-propagation of the electron and laser beams inside the plasma channel results in intense x-ray generation.

  19. Enhanced laser beam coupling to a plasma

    DOEpatents

    Steiger, Arno D.; Woods, Cornelius H.

    1976-01-01

    Density perturbations are induced in a heated plasma by means of a pair of oppositely directed, polarized laser beams of the same frequency. The wavelength of the density perturbations is equal to one half the wavelength of the laser beams. A third laser beam is linearly polarized and directed at the perturbed plasma along a line that is perpendicular to the direction of the two opposed beams. The electric field of the third beam is oriented to lie in the plane containing the three beams. The frequency of the third beam is chosen to cause it to interact resonantly with the plasma density perturbations, thereby efficiently coupling the energy of the third beam to the plasma.

  20. Staging of laser-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Steinke, S.; van Tilborg, J.; Benedetti, C.; Geddes, C. G. R.; Daniels, J.; Swanson, K. K.; Gonsalves, A. J.; Nakamura, K.; Shaw, B. H.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2016-05-01

    We present results of an experiment where two laser-plasma-accelerator stages are coupled at a short distance by a plasma mirror. Stable electron beams from the first stage were used to longitudinally probe the dark-current-free, quasi-linear wakefield excited by the laser of the second stage. Changing the arrival time of the electron beam with respect to the second stage laser pulse allowed reconstruction of the temporal wakefield structure, determination of the plasma density, and inference of the length of the electron beam. The first stage electron beam could be focused by an active plasma lens to a spot size smaller than the transverse wake size at the entrance of the second stage. This permitted electron beam trapping, verified by a 100 MeV energy gain.

  1. Laser-Hole Boring into Overdense Plasmas Measured with Soft X-Ray Laser Probing

    SciTech Connect

    Takahashi, K.; Kodama, R.; Tanaka, K. A.; Hashimoto, H.; Kato, Y.; Mima, K.; Weber, F. A.; Barbee, T. W. Jr.; Da Silva, L. B.

    2000-03-13

    A laser self-focused channel formation into overdense plasmas was observed using a soft x-ray laser probe system with a grid image refractometry (GIR) technique. 1.053 {mu}m laser light with a 100 ps pulse duration was focused onto a preformed plasma at an intensity of 2x10{sup 17} W /cm{sup 2} . Cross sections of the channel were obtained which show a 30 {mu}m diameter in overdense plasmas. The channel width in the overdense region was kept narrow as a result of self-focusing. Conically diverging density ridges were also observed along the channel, indicating a Mach cone created by a shock wave due to the supersonic propagation of the channel front. (c) 2000 The American Physical Society.

  2. Laser-Hole Boring into Overdense Plasmas Measured with Soft X-Ray Laser Probing

    NASA Astrophysics Data System (ADS)

    Takahashi, K.; Kodama, R.; Tanaka, K. A.; Hashimoto, H.; Kato, Y.; Mima, K.; Weber, F. A.; Barbee, T. W., Jr.; da Silva, L. B.

    2000-03-01

    A laser self-focused channel formation into overdense plasmas was observed using a soft x-ray laser probe system with a grid image refractometry (GIR) technique. 1.053 μm laser light with a 100 ps pulse duration was focused onto a preformed plasma at an intensity of 2×1017 W/cm 2. Cross sections of the channel were obtained which show a 30 μm diameter in overdense plasmas. The channel width in the overdense region was kept narrow as a result of self-focusing. Conically diverging density ridges were also observed along the channel, indicating a Mach cone created by a shock wave due to the supersonic propagation of the channel front.

  3. Laser plasma interaction experiments in the context of inertial fusion

    NASA Astrophysics Data System (ADS)

    Labaune, C.; Bandulet, H.; Depierreux, S.; Lewis, K.; Michel, P.; Michard, A.; Baldis, H. A.; Hulin, S.; Pesme, D.; Hüller, S.; Tikhonchuk, V.; Riconda, C.; Weber, S.

    2004-12-01

    In laser fusion, the coupling and the propagation of the laser beams in the plasma surrounding the pellet must be well controlled for to succeed in producing a high energy level. To achieve thermonuclear ignition and high gain, the coupling efficiency must be as high as possible, the uniformity of the energy deposition must be very good and the fast electron generation must be minimized. This implies a deep understanding of the laser plasma interaction mechanisms to keep the nonlinear processes at a low level. Important advances in laser plasma interaction physics have been achieved thanks to the converging efforts of the experimental and theoretical approaches. Among the different studies of the last few years, we will report results on three themes which are important for future fusion experiments. The first concerns the ability of plasmas to induce temporal and spatial incoherence to the laser beams during their propagation. Beam smoothing, beam spraying and increased incoherence may in turn reduce the level of backscattering instabilities. In laser fusion, multiple beams are used to irradiate the target. The effect of the overlap of the laser beams on parametric instabilities may complicate the problem. Not only is there the interplay between instabilities driven by one beam, but also the interplay between instabilities driven by different beams. In the Laboratoire pour l'Utilisation des Lasers Intenses (LULI) experiment, although the overall stimulated Brillouin scattering (SBS) reflectivity was reduced, a well-defined resonance of the amplitude of ion acoustic waves (IAWs) associated with SBS has been observed for waves propagating along the bisecting direction between two laser beams. Energy transfer between two identical laser beams has been observed and correlated with plasma induced incoherence. The nonlinear saturation of stimulated scattering instabilities is a fundamental ingredient of the understanding of the observed and future reflectivity levels

  4. Nonlinear heating of underdense collisional plasma by a laser pulse

    SciTech Connect

    Abari, M. Etehadi; Shokri, B.

    2011-05-15

    The nonlinear interaction of a laser pulse with a homogenous unmagnetized underdense plasma, taking ohmic heating and the effects of ponderomotive force into account, is theoretically studied. Since the ponderomotive force modifies the electrons density and temperature distribution, the nonlinear dielectric permittivity of plasma is obtained in non-relativistic regime. Furthermore, electric and magnetic fields, electron density, temperature distribution, and the effective permittivity variations are obtained in terms of plasma length by making use the steady state solutions of the Maxwell and hydrodynamic equations. It is shown that the oscillations wave length of electric and magnetic fields decreases when the laser intensity increases. At the same time, in this case, electron density oscillations become highly peaked. Also, the amplitude of the electron temperature oscillations increase and their wavelength decreases.

  5. Review of upconverted Nd-glass laser plasma experiments at the Lawrence Livermore National Laboratory

    SciTech Connect

    Manes, K.R.

    1982-05-01

    Systematic scaling experiments aimed at deducing the dependence of laser-plasma interaction phenomena on target plasma material and target irradiation history have been underway in laboratories all over the world in recent years. During 1980 and 1981 the Livermore program undertook to measure the laser light absorption of high and low Z plasmas and the partition of the absorbed energy amongst the thermal and suprathermal electron populations as a function of both laser intensity and wavelength. Simulations suggested that short wavelength laser light would couple more efficiently than longer wavelengths to target plasmas. Shorter wavelength heating of higher electron plasma densities would, it was felt, lead to laser-plasma interactions freer of anomalous absorption processes. The following sections review LLNL experiments designed to test these hypotheses.

  6. Experimental evidence of plasma-induced incoherence of a laser beam after propagation through an underdense plasma

    NASA Astrophysics Data System (ADS)

    Labaune, Christine; Fuchs, Julien; Depierreux, Sylvie; Baldis, Hector; Pesme, Denis; Myatt, Jason; Hüller, Stefan; Laval, Guy; Tikhonchuk, Vladimir

    2000-10-01

    Experiments with the six-beam laser facility at Laboratoire pour l'Utilisation des lasers Intenses (LULI) have demonstrated simultaneous and correlated large angular beam spreading and spectral broadening, on the red side of the spectra, of a RPP laser beam after its propagation through an underdense plasma.. At the highest intensities, the beam initial aperture is widely broadened (the F.W.H.M. aperture is increased by a factor 2) and its bandwidth increases from <0.1 A to more than 10 A. Results showing the effect of the plasma electron density, laser intensity and polarization smoothing will be presented. The increase of spatial and temporal incoherence of the laser beam is discussed following recent numerical simulations.

  7. Developments in Laser and Plasma-Based Accelerators

    NASA Astrophysics Data System (ADS)

    Downer, Michael

    2001-04-01

    The explosive growth of multiterawatt laser technology combined with the increasing size and cost of conventional RF particle accelerators has driven intense research into more compact laser-driven and/or plasma based acceleration concepts. Although schemes for direct laser acceleration without plasmas or, conversely, plasma acceleration without lasers have been studied, the greatest recent progress has been made with concepts that combine lasers and plasmas [1]. Tajima and Dawson [2] proposed in 1979 that a sufficiently intense single laser pulse of duration t ω_p-1, or a pair of laser pulses with Δω ω_p, could be efficiently drive a longitudinal electron plasma wave with phase velocity approaching c via the ponderomotive force. Charged particles that "surf" such waves experience accelerating gradients (E 10^9 V/cm) as much as a thousand times greater than conventional RF accelerators. Numerous experiments have now demonstrated acceleration of up to 10^9 electrons per laser pulse to energies exceeding 100 MeV, with wide energy spread, but competitive beam emittance. Such sources have proven useful for nuclear activation analysis in their current form. However for such accelerators to be useful to a wider community, including high energy physics, key challenges must be addressed. These include: 1) Guiding terawatt laser pulses. Achieving useful laser intensities requires focusing, thus limiting interaction length to < 1 mm, whereas interaction lengths of several cm are needed to use laser energy efficiently and reach GeV acceleration in a single stage. Several groups are now developing high-throughput plasma "fibers" that have supported peak powers near a terawatt over > 1 cm without distortion [3]. 2) Phased injection. Since plasma waves with useful gradients have wavelengths of micron dimensions, charged particles must be injected with unprecedented spatial and temporal precision to achieve a monochromatic output beam. Several groups are developing new laser

  8. Near-diffraction-limited laser focusing with a near-critical density plasma lens.

    PubMed

    Shou, Yinren; Lu, Haiyang; Hu, Ronghao; Lin, Chen; Wang, Hongyong; Zhou, Meilin; He, Xiantu; Chen, Jia Erh; Yan, Xueqing

    2016-01-01

    In this Letter, we investigate the feasibility of focusing relativistic laser pulses toward diffraction limit by near-critical density plasma lenses. A theoretical model is developed to estimate the focal length of the plasma lens. Particle-in-cell simulations with various pulse parameters, such as pulse duration, beam waist, and intensity, are performed to show the robustness of plasma lenses. The results prove that the near-critical density plasma lenses can be deployed to obtain higher laser peak intensities with sub-wavelength focal spots in experiments. PMID:26696178

  9. The phase-lock dynamics of the laser wakefield acceleration with an intensity-decaying laser pulse

    SciTech Connect

    Li, Wentao; Liu, Jiansheng Wang, Wentao; Zhang, Zhijun; Chen, Qiang; Tian, Ye; Qi, Rong; Yu, Changhai; Wang, Cheng; Li, Ruxin Xu, Zhizhan; Tajima, T.

    2014-03-03

    An electron beam with the maximum energy extending up to 1.8 GeV, much higher than the dephasing limit, is experimentally obtained in the laser wakefield acceleration with the plasma density of 3.5 × 10{sup 18} cm{sup −3}. With particle in cell simulations and theoretical analysis, we find that the laser intensity evolution plays a major role in the enhancement of the electron energy gain. While the bubble length decreases due to the intensity-decay of the laser pulse, the phase of the electron beam in the wakefield can be locked, which contributes to the overcoming of the dephasing. Moreover, the laser intensity evolution is described for the phase-lock acceleration of electrons in the uniform plasma, confirmed with our own simulation. Since the decaying of the intensity is unavoidable in the long distance propagation due to the pump depletion, the energy gain of the high energy laser wakefield accelerator can be greatly enhanced if the current process is exploited.

  10. Hybrid Laser-Plasma Wakefield Acceleration

    SciTech Connect

    Hidding, B.; Koenigstein, T.; Willi, O.; Pretzler, G.; Karsch, S.; Rosenzweig, J. B.

    2010-11-04

    The concept of driving a driver/witness-type plasma wakefield accelerator (PWFA) with quasimonoenergetic double electron bunches from a laser wakefield accelerator (LWFA) is studied. In the quasimonoenergetic LWFA/SMLWFA (self-modulated LWFA) regime, it is possible to generate multiple quasimonoenergetic electron bunches with durations of only a few fs and distances of only a few tens of fs with a comparably simple experimental setup. In a subsequent high-density plasma afterburner stage the witness bunch energy can be boosted in the plasma wakefield generated by the driver. Such a hybrid system can increase the maximum energy output of a laser wakefield accelerator and is well suited to study driver/witness plasma accelerator phenomena and can be used as a cost-effective test-bed for future high-energy plasma-based accelerators.

  11. Hybrid Laser-Plasma Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Hidding, B.; Königstein, T.; Karsch, S.; Willi, O.; Pretzler, G.; Rosenzweig, J. B.

    2010-11-01

    The concept of driving a driver/witness-type plasma wakefield accelerator (PWFA) with quasimonoenergetic double electron bunches from a laser wakefield accelerator (LWFA) is studied. In the quasimonoenergetic LWFA/SMLWFA (self-modulated LWFA) regime, it is possible to generate multiple quasimonoenergetic electron bunches with durations of only a few fs and distances of only a few tens of fs with a comparably simple experimental setup. In a subsequent high-density plasma afterburner stage the witness bunch energy can be boosted in the plasma wakefield generated by the driver. Such a hybrid system can increase the maximum energy output of a laser wakefield accelerator and is well suited to study driver/witness plasma accelerator phenomena and can be used as a cost-effective test-bed for future high-energy plasma-based accelerators.

  12. Improved ion acceleration via laser surface plasma waves excitation

    SciTech Connect

    Bigongiari, A.

    2013-05-15

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

  13. Scattering of intense femtosecond laser radiation at water aerosol in backward direction

    NASA Astrophysics Data System (ADS)

    Efimenko, E. S.; Malkov, Yu. A.; Murzanev, A. A.; Stepanov, A. N.

    2015-12-01

    We investigated the scattering of femtosecond laser pulses with intensities within the 1012-1013W/cm2 range at a water aerosol jet at 20° to backward direction. The scattered energy and spectra transformation as a function of incident intensity obtained in experiment show good agreement with the results of extensive numerical modeling based on self-consistent solution of Maxwell equations using a nonlinear 3D FDTD code and balance equation for plasma density.

  14. Laser-induced breakdown spectroscopy of tantalum plasma

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ ˜ 1064 nm, τ ˜ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO2: N2: He), O2, N2, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  15. Laser-induced breakdown spectroscopy of tantalum plasma

    SciTech Connect

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

    2013-07-15

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

  16. Stable laser-pulse propagation in plasma channels for GeV electron acceleration

    PubMed

    Sprangle; Hafizi; Penano; Hubbard; Ting; Zigler; Antonsen

    2000-12-11

    To achieve multi-GeV electron energies in the laser wakefield accelerator (LWFA) it is necessary to propagate an intense laser pulse long distances in plasma without disruption. A 3D envelope equation for a laser pulse in a tapered plasma channel is derived, which includes wakefields and relativistic and nonparaxial effects, such as finite pulse length and group velocity dispersion. It is shown that electron energies of approximately GeV in a plasma-channel LWFA can be achieved by using short pulses where the forward Raman and modulation nonlinearities tend to cancel. Further energy gain can be achieved by tapering the plasma density to reduce electron dephasing. PMID:11102198

  17. Radiation sources based on laser-plasma interactions.

    PubMed

    Jaroszynski, D A; Bingham, R; Brunetti, E; Ersfeld, B; Gallacher, J; van der Geer, B; Issac, R; Jamison, S P; Jones, D; de Loos, M; Lyachev, A; Pavlov, V; Reitsma, A; Saveliev, Y; Vieux, G; Wiggins, S M

    2006-03-15

    Plasma waves excited by intense laser beams can be harnessed to produce femtosecond duration bunches of electrons with relativistic energies. The very large electrostatic forces of plasma density wakes trailing behind an intense laser pulse provide field potentials capable of accelerating charged particles to high energies over very short distances, as high as 1GeV in a few millimetres. The short length scale of plasma waves provides a means of developing very compact high-energy accelerators, which could form the basis of compact next-generation light sources with unique properties. Tuneable X-ray radiation and particle pulses with durations of the order of or less than 5fs should be possible and would be useful for probing matter on unprecedented time and spatial scales. If developed to fruition this revolutionary technology could reduce the size and cost of light sources by three orders of magnitude and, therefore, provide powerful new tools to a large scientific community. We will discuss how a laser-driven plasma wakefield accelerator can be used to produce radiation with unique characteristics over a very large spectral range. PMID:16483958

  18. A "slingshot" laser-driven acceleration mechanism of plasma electrons

    NASA Astrophysics Data System (ADS)

    Fiore, Gaetano; De Nicola, Sergio

    2016-09-01

    We briefly report on the recently proposed Fiore et al. [1] and Fiore and De Nicola [2] electron acceleration mechanism named "slingshot effect": under suitable conditions the impact of an ultra-short and ultra-intense laser pulse against the surface of a low-density plasma is expected to cause the expulsion of a bunch of superficial electrons with high energy in the direction opposite to that of the pulse propagation; this is due to the interplay of the huge ponderomotive force, huge longitudinal field arising from charge separation, and the finite size of the laser spot.

  19. Propagation and absorption of high-intensity femtosecond laser radiation in diamond

    SciTech Connect

    Kononenko, V V; Konov, V I; Gololobov, V M; Zavedeev, E V

    2014-12-31

    Femtosecond interferometry has been used to experimentally study the photoexcitation of the electron subsystem of diamond exposed to femtosecond laser pulses of intensity 10{sup 11} to 10{sup 14} W cm{sup -2}. The carrier concentration has been determined as a function of incident intensity for three harmonics of a Ti : sapphire laser (800, 400 and 266 nm). The results demonstrate that, in a wide range of laser fluences (up to those resulting in surface and bulk graphitisation), a well-defined multiphoton absorption prevails. We have estimated nonlinear absorption coefficients for pulsed radiation at λ = 800 nm (four-photon transition) and at 400 and 266 nm (indirect and direct two-photon transitions, respectively). It has also been shown that, at any considerable path length of a femtosecond pulse in diamond (tens of microns or longer), the laser beam experiences a severe nonlinear transformation, determining the amount of energy absorbed by the lattice, which is important for the development of technology for diamond photostructuring by ultrashort pulses. The competition between wave packet self-focusing and the plasma defocusing effect is examined as a major mechanism governing the propagation of intense laser pulses in diamond. (interaction of laser radiation with matter. laser plasma)

  20. Plasma expansion into a waveguide created by a linearly polarized femtosecond laser pulse

    SciTech Connect

    Lemos, N.; Grismayer, T.; Cardoso, L.; Figueira, G.; Dias, J. M.

    2013-06-15

    We demonstrate the efficient generation of 4 mm and 8 mm long plasma waveguides in hydrogen and helium. These waveguides have matching spots sizes for 13 to 34 μm laser beams. The plasma waveguides are created by ultra-short laser pulses (sub-picosecond) of moderate intensities, ∼10{sup 15}–10{sup 16} W cm{sup −2}, that heat the plasma to initial temperatures of tens of eV in order to create a hot plasma column that will expand into a plasma waveguide. We have determined that the main heating mechanism when using fs laser pulses and plasma densities ∼10{sup 18–19} cm{sup −3} is Above Threshold Ionization. Detailed time and space electron density measurements are presented for the laser produced plasma waveguides.