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Sample records for intense laser plasma

  1. 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

  2. Studies of intense-laser plasma instabilities

    NASA Astrophysics Data System (ADS)

    Láska, L.; Krása, J.; Badziak, J.; Jungwirth, K.; Krouský, E.; Margarone, D.; Parys, P.; Pfeifer, M.; Rohlena, K.; Rosiński, M.; Ryć, L.; Skála, J.; Torrisi, L.; Ullschmied, J.; Velyhan, A.; Wołowski, J.

    2013-05-01

    The PALS high power iodine laser system in Prague (λ = 1.315 μm) was used to study non-linear processes in a laser-produced plasma at intense laser beam interactions with planar targets. The focus setting allows to alter the non-linear interaction of the main laser pulse with the ablated plasma produced by the front edge of a nanosecond laser pulse (300 ps FWHM). The arisen non-linear effects significantly influence the behavior of electrons, which accelerate fully striped or highly charged fast ions. Variations in time of the expanding plasma, recorded at the target surface by the use of Kentech low-magnification soft X-ray streak camera on ˜2 ns time scale, are presented and discussed. Narrowing, arching and even splitting of expansion paths in the target-normal space-time diagram are shown. These phenomena are ascribed to the magnetic field, self-generated at high laser intensities, which may become strong enough to cause pinching of the expanding plasma.

  3. Laboratory Plasma Astrophysics Research with Intense Lasers

    NASA Astrophysics Data System (ADS)

    Takabe, Hideaki; Kato, Tsunehiko; Kuramitsu, Yasuhiro; Sakawa, Yuichi

    2008-12-01

    Large scale laser facilities mainly constructed for fusion research can be used to produce high-energy-density plasmas like the interior of stars and planets. They can be also used to reproduce the extreme phenomena of explosion and high Mach number flow in mimic scale in laboratory. With advanced diagnostic technique, we can study the physics of plasma phenomena expected to control a variety of phenomena in Universe. The subjects studied so far are reviewed, for example, in [1], [2]. The project to promote the laboratory astrophysics with Gekko XII laser facility has been initiated from April 1st this year as a project of our institute. It consists of four sub-projects. They are 1. Physics of collisionless shock and particle acceleration, 2. Physics of Non LTE (local thermodynamic equilibrium) photo-ionized plasma, 3. Physics of planets and meteor impact, 4. Development of superconducting Terahertz device. I will briefly explain what the laser astrophysics means and introduce what are the targets of our project. Regarding the first sub-project, we have carried out hydrodynamic and PIC simulation to design the experiments with intense laser. We clarified the physical mechanism of generation of the magnetic field in non-magnetized plasma and the collsionless shock formation caused by the ion orbit modifications by the magnetic fields generated as the result of plasma instability. Note from Publisher: This article contains the abstract only.

  4. Intense terahertz radiation from relativistic laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Liao, G. Q.; Li, Y. T.; Li, C.; Liu, H.; Zhang, Y. H.; Jiang, W. M.; Yuan, X. H.; Nilsen, J.; Ozaki, T.; Wang, W. M.; Sheng, Z. M.; Neely, D.; McKenna, P.; Zhang, J.

    2017-01-01

    The development of tabletop intense terahertz (THz) radiation sources is extremely important for THz science and applications. This paper presents our measurements of intense THz radiation from relativistic laser-plasma interactions under different experimental conditions. Several THz generation mechanisms have been proposed and investigated, including coherent transition radiation (CTR) emitted by fast electrons from the target rear surface, transient current radiation at the front of the target, and mode conversion from electron plasma waves (EPWs) to THz waves. The results indicate that relativistic laser plasma is a promising driver of intense THz radiation sources.

  5. Multifocal terahertz radiation by intense lasers in rippled plasma

    NASA Astrophysics Data System (ADS)

    Gill, Reenu; Singh, Divya; Malik, Hitendra K.

    2017-06-01

    This paper presents a theoretical model for the generation of terahertz radiation by cosh-Gaussian laser beams of high intensity, which are capable of creating relativistic-ponderomotive nonlinearity. We find the components of the terahertz radiation for the relativistic laser plasma interaction, i.e. beating of the two lasers of same amplitude and different frequency in under dense plasma. We plot the electric field profile of the emitted radiation under the effect of lasers index. By creating a dip in peak of the incident lasers' fields, we can achieve multifocal terahertz radiation.

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

    SciTech Connect

    Coverdale, Christine Ann

    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), 1016 W/cm2 laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by Lplasma ≥ 2LRayleigh > cτ. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (no ≤ 0.05ncr). 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 ω-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

  7. Plasma-based polarization modulator for high-intensity lasers

    NASA Astrophysics Data System (ADS)

    Chen, Zi-Yu; Pukhov, Alexander

    2016-12-01

    Manipulation of laser pulses at high intensities is an important yet challenging issue. New types of plasma-based optical devices are promising alternatives to achieve this goal. Here we propose to modulate the polarization state of intense lasers based on oblique reflection from solid-plasma surfaces. A new analytical description is presented considering the plasma as an uniaxial medium that causes birefringence effect. Particle-in-cell simulation results numerically demonstrate that such a scheme can provide a tunable polarization control of the laser pulses even in the relativistic regime. The results are thus relevant for the design of compact, easy to use, and versatile polarization modulators for high-intensity laser pulses.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Intense Laser Plasma Interactions on the Road to Fast Ignition

    NASA Astrophysics Data System (ADS)

    van Woerkom, Linn

    2007-11-01

    Successful Fast Ignition (FI) offers the prospect of reduced laser driver energy and greater energy gain, which enhances the possibilities for realistic Inertial Confinement Fusion (ICF) energy power plants. The interaction of high intensity laser pulses with hot dense plasma lies at the core of the FI concept. At the most basic level FI relies on converting high energy, high intensity laser light into a beam of electrons which must propagate for 10's to ˜100 microns and deposit their energy in the compressed fuel. Thus, the process may be divided into two critical processes: 1) the generation of energetic electrons from the laser-matter interaction, and 2) the transport of energetic electrons through hot dense plasma. Experiments to date have only explored part of the FI relevant parameter space concerning laser energy, intensity, pulse duration, and transport of MeV particles. With the approach of first light on OMEGA EP and then NIF ARC, the field is poised to make crucial measurements that will determine the requirements for full scale FI. This talk will present recent results from high intensity laser-cone interactions that help pave the way to the next generation of experiments.

  13. 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}

  14. 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

  15. Modelling of intense line radiation from laser-produced plasmas

    SciTech Connect

    Lee, Yim T.; Gee, M.

    1990-04-01

    In this paper, we discuss modelling of Lyman-{alpha} (i.e. Ly-{alpha}) radiation emitted from laser-produced plasmas. We are interested in the application of one of these line radiations to pump a transition of an ion in a different plasma spatially separated from the emitting source. The interest is in perturbing the plasma rather than just probing it as in some backlighting experiments. As a result of pumping, the populations of certain excited levels are inverted. The resulting gain coefficients depend strongly on the population inversion density which in turn depends on the brightness of the pump radiation. As a result, we must produce an intense bright radiation source. In addition, to pump a transition effectively, we also need a pump line with a width larger than the mismatch of the resonance since the widths of the pumped transitions are rather narrow

  16. Relativistic magnetic reconnection driven by intense lasers in preformed plasma

    NASA Astrophysics Data System (ADS)

    Campbell, Paul; Raymond, A.; McKelvey, A.; Maksimchuk, A.; Nees, J.; Yanovsky, V.; Krushelnick, K.; Dong, C. F.; Fox, W.; Zulick, C.; Wei, M. S.; Chen, H.; Chvykov, V.; Mileham, C.; Nilson, P. M.; Stoeckl, C.; Thomas, A. G. R.; Willingale, L.

    2016-10-01

    Experiments were performed with the OMEGA EP laser system focusing the two short pulse beams to high intensities on foil targets. Relativistic electrons drive fast reconnection self-generated magnetic fields. To investigate the effects of a preformed plasma on this relativistic magnetic reconnection, a long pulse UV beam was used to ablate the front surface of layered targets. The density and reconnection dynamics in the preformed copper or CH plasma were diagnosed with a 4 ω optical probe. A spherically bent crystal imaged characteristic copper Kα emission induced by fast electrons accelerated into the target in the reconnection diffusion region. This work was supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0002727.

  17. A Warm Fluid Model of Intense Laser-Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Tarkenton, G. M.; Shadwick, B. A.; Esarey, E. H.; Leemans, W. P.

    2001-10-01

    Following up on our previous work on modeling intense laser-plasma interactions with cold fluids,(B.A.Shadwick, G. M. Tarkenton, E.H. Esarey, and W.P. Leemans, ``Fluid Modeling of Intense Laser-Plasma Interactions'', in Advanced Accelerator Concepts), P. Colestock and S. Kelley editors, AIP Conf. Proc. 569 (AIP, NY 2001), pg. 154. we are exploring warm fluid models. These models represent the next level in a hierarchy of complexity beyond the cold fluid approximation. With only a modest increase in computation effort, warm fluids incorporate effects that are relevant to a variety of technologically interesting cases. We present a derivation of the warm fluid from a kinetic (i.e. Vlasov) perspective and make a connection with the usual relativistic thermodynamic approach.(S. R. de Groot, W. A. van Leeuwen and Ch. G. van Weert, Relativistic Kinetic Theory: Principles and Applications), North-Holland (1980). We will provide examples where the warm fluids yield physics results not contained in the cold model and discuss experimental parameters where these effects are believed to be important.

  18. Absorption of ultra-intense intense laser pulse in self-generated pair plasma

    NASA Astrophysics Data System (ADS)

    Grismayer, Thomas; Vranic, Marija; Fonseca, Ricardo; Silva, Luis

    2014-10-01

    Plasma physics in extreme fields requires taking into account Quantum Electrodynamics effects such as non-linear Compton scattering and Breit-Wheeler pair production. Such effects intervene in laser-plasma interactions at ultra high intensities (I >1023 W/cm2). The self-consistent modeling of these scenarios is challenging since some localized regions of ultra-intense field will produce a vast number of pairs that may cause memory overflow during the simulation. To overcome this issue, we have developed a merging algorithm that allows merging a large number of particles into fewer particles with higher particle weights while conserving local particle distributions. This algorithm is crucial to investigate the laser absorption in self-generated pair plasmas. During the interaction, the laser energy is converted into pairs and photons and the absorption become significant when the plasma density reaches the critical density. We present the results of 3D PIC-QED simulations (Osiris 2.0) showing the respective fraction of laser energy transferred into pairs and photons. The dependence of the laser absorption on the laser parameters for various configurations is also discussed.

  19. Self-Steepening of intense laser pulses in plasmas

    NASA Astrophysics Data System (ADS)

    Vieira, Jorge; Fiúza, Frederico; Silva, Luis

    2007-11-01

    In state-of-the-art Laser Wake Field Acceleration (LWFA) experiments [1], the self-modulations of the laser pulse (both transverse and longitudinal) play an important role in the enhancement of the plasma wave, which can trap, accelerate and lead to quasi-mono-energetic electron beams. In this work, the self-steepening of intense laser pulses is studied analytically resorting to the photon-kinetic theory [2]. Rates for the growth of self-steepening in the early laser propagation are provided in the long and short pulse limits, and in the weakly and ultra relativistic regimes. Thresholds for the on-set, maximum and minimum growth of self-steepening are determined. We find very good agreement between the analytical model and one-dimensional PIC simulations with OSIRIS [3]. Implications of our results to state-of-the-art LWFA experiments are discussed. [1] W.P. Leemans et al Nat. Phys., 2 (10), 696-699 (2006) [2] L.O. Silva et al, IEEE TPS 28 (4) 1128-1134 (2000) [3] R. A. Fonseca et al, LNCS 2331, 342-351, (Springer, Heidelberg, 2002).

  20. 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.

  1. Analysis of processes participating during intense iodine-laser-beam interactions with laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Láska, L.; Badziak, J.; Jungwirth, K.; Kálal, M.; Krása, J.; Krouský, E.; Kubeš, P.; Margarone, D.; Parys, P.; Pfeifer, M.; Rohlena, K.; Rosiński, M.; Ryć, L.; Skála, J.; Torrisi, L.; Ullschmied, J.; Velyhan, A.; Wolowski, J.

    2010-10-01

    The high-power iodine laser PALS was used to generate highly charged Ta ions and to study non-linear processes in laser-produced plasma. Longitudinal structures of the expanding plasma, obtained by using an X-ray streak camera on a time scale ∼ 2 ns, are presented. Various bright spots (moon-like, half-moon-like), expansion-path curvature and even their splitting were recorded. These phenomena are ascribed to the effect of the magnetic field that is self-generated at high laser intensities.

  2. Short intense laser pulse collapse in near-critical plasma.

    PubMed

    Sylla, F; Flacco, A; Kahaly, S; Veltcheva, M; Lifschitz, A; Malka, V; d'Humières, E; Andriyash, I; Tikhonchuk, V

    2013-02-22

    It is observed that the interaction of an intense ultrashort laser pulse with a near-critical gas jet results in the pulse collapse and the deposition of a significant fraction of the energy. This deposition happens in a small and well-localized volume in the rising part of the gas jet, where the electrons are efficiently accelerated and heated. A collisionless plasma expansion over ~ 150 μm at a subrelativistic velocity (~ c/3) has been optically monitored in time and space, and attributed to the quasistatic field ionization of the gas associated with the hot electron current. Numerical simulations in good agreement with the observations suggest the acceleration in the collapse region of relativistic electrons, along with the excitation of a sizable magnetic dipole that sustains the electron current over several picoseconds.

  3. Nonlinear absorption of short intense laser pulse in multispecies plasma

    SciTech Connect

    Kargarian, A.; Hajisharifi, K.; Mehdian, H.

    2016-08-15

    In the present paper, the detailed investigation concerning the effect of inclusion of heavy negative ions into the finite background plasma on the laser absorption has been carried out by employing particle-in-cell simulation method. For this purpose, in this configuration, the laser energy absorption relying on the nonlinear phenomena such as phase-mixing, wave-breaking, and scattering has been studied in the Raman-Brillouin regime. It is shown that the inclusion of heavy negative ions suppresses the scattering while increases the phase-mixing time. Moreover, it is illustrated that this inclusion can increase the laser absorption in finite plasma environment, after saturation. The obtained results are expected to be relevant to the experiments on the mass spectrometry with laser desorption techniques as well as on the laser-plasma interaction with application to particles acceleration.

  4. Ultrahigh intensities and contrast using an ellipsoidal plasma mirror with the Z-Backlighter Laser

    NASA Astrophysics Data System (ADS)

    Hurd, Lucas; Nakatsutsumi, Motoaki; Audebert, Patrick; Buffechoux, Sebastien; Kon, Akira; Kodama, Ryosuke; Fuchs, Julien

    2010-11-01

    Plasma-based focusing optics have been proven to increase the peak intensity of ultrahigh intensity lasers without significantly distorting the beam spatial profile or modifying the laser system itself [1]. In this experiment we will make use of an ellipsoidal plasma mirror (EPM) to increase the contrast and decrease the focal size of the ultrashort pulses provided by the Z-Backlighter Laser at Sandia National Laboratories. We predict the EPM setup to reduce the effective numerical aperture from f/3 to f/0.6, which could lead to a 25-fold intensity enhancement compared to flat plasma mirrors. These increased intensities will be demonstrated by observing protons accelerated from laser-plasma interactions via the target normal sheath acceleration mechanism. We expect protons with energies of more than 50 MeV to be generated. [4pt] [1] Nakatsutsumi et al. Fast focusing of short-pulse lasers by innovative plasma optics toward extreme intensity. Optics Lett. 35, 2314 (2010).

  5. 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.

  6. Understanding Intense Laser Interactions with Solid Density Plasma

    DTIC Science & Technology

    2017-01-04

    structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. We have demonstrated for the first time the use of laser...the positions of atoms in the unit cell. Indeed, it is readily seen that the structure factor for the (220) silicon peaks is maximum, i.e., each... atom in the unit cell contributes to the maximum constructive interference. Reference 35 suggests that the increase of the Bragg peak intensity might

  7. Comoving acceleration of overdense electron-positron plasma by colliding ultra-intense laser pulses

    SciTech Connect

    Liang, Edison

    2006-06-15

    Particle-in-cell (PIC) simulation results of sustained acceleration of electron-positron (e+e-) plasmas by comoving electromagnetic (EM) pulses are presented. When a thin slab of overdense e+e- plasma is irradiated with linear-polarized ultra-intense short laser pulses from both sides, the pulses are transmitted when the plasma is compressed to thinner than {approx}2 relativistic skin depths. A fraction of the plasma is then captured and efficiently accelerated by self-induced JxB forces. For 1 {mu}m laser and 10{sup 21} W cm{sup -2} intensity, the maximum energy exceeds GeV in a picosecond.

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

    SciTech Connect

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

    2016-06-15

    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.

  9. Nonparaxial Propagation of Intense Laser Pulses in Plasma Channels

    NASA Astrophysics Data System (ADS)

    Esarey, E.; Schroeder, C. B.; Shadwick, B. A.; Wurtele, J. S.; Leemans, W. P.

    1999-11-01

    The nonparaxial propagation(E. Esarey and W.P. Leemans, Phys. Rev. E 59), 1082 (1999). of ultrashort, high power (near the critical power for relativistic self-focusing) laser pulses in plasmas, with or without a density channel, is examined.(E. Esarey et al., Phys. Rev. Lett., submitted.) In the adiabatic limit, in which the wave equation contains a cubic nonlinearity and coupling to the plasma wave is neglected, several phenomena are analyzed: pulse energy conservation, nonlinear group velocity, damped betatron oscillations, self-steepening, self-phase modulation, and shock formation. In the general non-adiabatic case, the coupling of forward Raman scattering (FRS) and the self-modulation instability (SMI) is analyzed. Asymptotic expressions for growth rates are derived, including regimes of reduced growth. The SMI is found to dominate FRS in most regimes of interest.

  10. 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.; 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.

  11. Shaped Plasma Lenses for Optical Beam Control at High Laser Intensities

    NASA Astrophysics Data System (ADS)

    Hubbard, R. F.; Palastro, J. P.; Johnson, L. A.; Hafizi, B.; Gordon, D. F.; Penano, J. R.; Helle, M. H.; Kaganovich, D.

    2016-10-01

    A plasma channel is a cylindrical plasma column with an on-axis density minimum. A short plasma channel can focus a laser pulse in much the same manner as a conventional lens or off-axis parabola. If the plasma has an off-axis density maximum (``inverse channel''), it behaves like a negative lens and acts to defocus the pulse. In either case, a shaped plasma lens (SPL) may be placed in the beamline at locations where the laser intensity or fluence is orders of magnitude above the damage threshold for conventional solid optics. When placed after an off-axis parabola, SPLs may provide additional flexibility and spot size control and may also be useful in suppressing laser prepulse. For high power, ultrashort laser pulses, the broad laser bandwidth and extreme intensities produce chromatic and phase aberrations and amplitude distortions that degrade the lens focusing or defocusing performance. Although there have been a few experiments that demonstrate laser pulse focusing by a shaped plasma lens, generation and control of the plasma present significant challenges. Potential applications of SPLs to laser-plasma accelerators will be discussed. Supported by the Naval Research Laboratory Base Program.

  12. Electromagnetic Confined Plasma Target for Interaction Studies with Intense Laser Fields

    SciTech Connect

    Zielbauer, B; Ursescu, U; Trotsenko, S; Spillmann, U; Schuch, R; Stohlker, T; Kuhl, T; Borneis, S; Schenkel, T; McDonald, J; Schneider, D

    2006-08-09

    The paper describes a novel application of an electron beam ion trap as a plasma target facility for intense laser-plasma interaction studies. The low density plasma target ({approx}10{sup 13}/cm{sup 3}) is confined in a mobile cryogenic electromagnetic charged particle trap, with the magnetic confinement field of 1-3T maintained by a superconducting magnet. Ion plasmas for a large variety of ion species and charge states are produced and maintained within the magnetic field and the space charge of an energetic electron beam in the ''Electron Beam Ion Trap'' (EBIT) geometry. Intense laser beams (optical lasers, x-ray lasers and upcoming ''X-Ray Free Electron Lasers'' (XFEL)) provide strong time varying electromagnetic fields (>10{sup 12} V/cm in femto- to nano-sec pulses) for interactions with electromagnetically confined neutral/non-neutral plasmas. The experiments are aimed to gain understanding of the effects of intense photon fields on ionization/excitation processes, the ionization balance, as well as photon polarization effects. First experimental scenarios and tests with an intense laser that utilize the ion plasma target are outlined.

  13. Dynamic high pressure generation through plasma implosion driven by an intense laser pulse

    NASA Astrophysics Data System (ADS)

    Li, M.; Wang, J. X.; Yuan, T.; Xu, Y. X.; Zhu, W. J.

    2017-03-01

    When an intense laser pulse is loaded upon solids, very high impact pressure can be generated on the surface. In this letter, we simulate this process through one-dimensional particle-in-cell simulation and find that the pressure as high as 0.13 TPa can be generated after the laser pulse with intensity 1015 W/cm2 and 5 picosecond duration is injected upon a nanometer solid-density plasma. The peak pressure is shown to be resulted from an energetic high-density plasma bunch, produced through plasma implosion under extremely high light pressure.

  14. Efficient propagation of ultra-intense laser beam in dense plasma

    SciTech Connect

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

    2015-04-29

    Ultra intense laser propagation in extended, dense plasma is investigated through optical and proton probing. When a >1 kJ, 10 ps laser propagates into a long-density scale length plasma, channel formation was observed up to 0.6 nc from the analysis of optical probe images. The proton track analysis shows the formation of strong electric and magnetic fields along the plasma channel, which may lead to the observed collimated electron beam on the laser axis. These results are promising for the feasibility of the direct irradiation scheme of fast ignition.

  15. 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.

  16. Wakefield effects and solitary waves of an intense short laser pulse propagation in a plasma channel

    SciTech Connect

    Hong Xueren; Xie Baisong; Zhao Xueyan; Zhang Shan; Wu Haicheng

    2011-10-15

    In the presence of relativistic and channel-coupling nonlinearity and wakefield effects, the propagation characteristics and solitary waves of an intense short laser pulse in a preformed plasma channel are investigated. The evolution equation of the laser spot size is derived by using variational technique, the initial laser and plasma parameters for propagation with constant spot size, periodic defocusing and focusing oscillations, and solitary waves are identified. For illustration, some numerical results are also presented. It is found that the laser focusing is enhanced by the wakefield effects that result in a significant reduced focusing power.

  17. 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.

  18. Pair plasma formation in the interaction of a thin plasma with ultra-intense counter-propagating lasers

    NASA Astrophysics Data System (ADS)

    Slade-Lowther, Cody

    2016-10-01

    Next-generation lasers (e.g. ELI) expect to reach peak intensities of 1023 Wcm-2. At such intensities, the electromagnetic field strength is sufficient for non-linear Quantum Electrodynamics effects to become important. The processes of non-linear Compton scattering and Breit-Wheeler Pair production become likely at intensities >=1023 Wcm-2, and have been predicted to lead to prolific pair and γ-ray production via electromagnetic cascades. We present results for the case of two counter-propagating circularly- polarized lasers of intensity I ∈ [1023 ,1025 ] Wcm24 interacting with a plasma of initial density n0 ∈ [1025 ,1035 ] via the Monte-Carlo- particle-in-cell code EPOCH. We show the maximum pair plasma density in I vs n0 space. We further discuss the variation within this space on the plasma characteristics, including laser absorption and field-particle energy distribution.

  19. Nonlinear interaction of intense left- and right-hand polarized laser pulse with hot magnetized plasma

    NASA Astrophysics Data System (ADS)

    Abedi-Varaki, M.; Jafari, S.

    2017-08-01

    In this article, self-focusing of an intense circularly polarized laser pulse in the presence of an external oblique magnetic field in hot magnetized plasma, using Maxwell's equations and the relativistic fluid momentum equation, is studied. An envelope equation governing the spot size of the laser beam for both of left- and right-hand polarizations has been derived and the effects of the plasma temperature and oblique magnetic field on the electron density distribution of hot plasma with respect to variation of the normalized laser spot size has been investigated. Numerical results depict that in right-hand polarization, self-focusing of the laser pulse along the propagation direction in hot magnetized plasma becomes better and more compressed with increasing . Inversely, in left-hand polarization, increase of in an oblique magnetic field leads to enhancement of the spot size and reduction self-focusing. Besides, in the plasma density profile, self-focusing of the laser pulse improves in comparison with no oblique magnetic field. Also it is shown that plasma temperature has a key role in the laser spot size, normalized laser output power and the variation of plasma density.

  20. High intensity laser-plasma sources of ions—physics and future applications

    NASA Astrophysics Data System (ADS)

    Krushelnick, K.; Clark, E. L.; Beg, F. N.; Dangor, A. E.; Najmudin, Z.; Norreys, P. A.; Wei, M.; Zepf, M.

    2005-12-01

    The interaction of high intensity laser pulses with plasmas is an efficient source of megaelectronvolt ions. Recent observations of the production of directional energetic ion 'beams' from the front and rear surfaces of thin foil targets upon irradiation by intense laser pulses have prompted a renewed interest into research in this area. In addition, other recent observations have shown that high energy ions can be observed from intense laser interaction with low density plasma as a result of ponderomotive shock acceleration. The source characteristics and acceleration mechanisms for these ions have been extensively investigated, and there have also been a number of proposed applications for these ion beams, such as for injectors into subsequent conventional acceleration stages, for medicine, for probing of dense plasmas and for inertial confinement fusion experiments.

  1. Ultra-intense laser-plasma interaction toward Weibel-mediated collisionless shocks formation

    NASA Astrophysics Data System (ADS)

    Grassi, Anna; Grech, M.; Amiranoff, F.; Macchi, A.; Riconda, C.

    2016-10-01

    The rapid developments in laser technology will soon offer the opportunity to study in the laboratory the processes driving Weibel-mediated collisionless shocks, typical of various astrophysical scenarii. The interaction of an ultra-intense laser with an overdense plasma has been identified as the preferential configuration. Yet, the experimental requirements still need to be properly investigated. High performance computing simulations are a necessary tool for this study. In this work, we present a series of kinetic simulations performed with the PIC code SMILEI, varying the laser and plasma parameters. In particular, we will study the effect of the laser polarisation and plasma density to obtain the best conditions for the creation of a collisionless shock. The role of the electrons heated at the interaction surface and of particles accelerated via the Hole Boring (laser-piston) mechanism on the generation of the current filamentation instability and the subsequent shock front formation will be highlighted.

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

    SciTech Connect

    Gold, David Michael

    1994-06-01

    Experiments were performed to characterize the creation and evolution of high-temperature (T e~100eV), high-density (ne>1022cm-3) plasmas created with intense (~1012-1016W/cm2), ultra-short (130fs) laser pulses. The principle diagnostic was plasma reflectivity at optical wavelengths (614nm). An array of target materials (Al, Au, Si, SiO2) 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 ~3μm and a temporal resolution of 130fs. An amplified, mode-locked dye laser system was designed to produce ~3.5mJ, ~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 1016W/cm2. In the insulator, SiO2, 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 ~1016W/cm2, indicating a material-independent state insensitive to atomic or solid-state details.

  3. [Method to measure spectrum intensity from laser plasma soft X-ray source].

    PubMed

    Ni, Qi-liang; Gong, Yan; Chen, Bo; Cao, Jian-lin

    2004-01-01

    This paper presents a method to detect and measure spectrum intensity from a laser plasma soft X-ray source. A Channel Electron Multiplier (CEM) and a calibrated silicon photodiode were used as detectors in this method, the former is a nonstandard detector and the latter is a standard one. Charge-sensitive preamplifiers were used for measuring total charges generated by detectors, and a monochromator with high resolution was employed as the spectrometer. The formulae to calculate spectrum intensity from laser plasma soft X-ray source was given, based on the known grating efficiency of the monochromator, CEM's gain and responsivity of the silicon photodiode to photons.

  4. Scientific Researches on High Intensity Laser Plasma in Asia-Pacific Region

    NASA Astrophysics Data System (ADS)

    Takabe, Hideaki

    The important topics of the presentations in the titled session are briefly summarized with author's comments for the further maturity and more challenge as plasma science. The topics of the session has been classified to three; fundamental plasma science, particle and photon sources, and quantum polarization of vacuum and non-linear QED plasma. In order not to make the paper only for a memorandum of the titled session, very important and related topics were also picked up from the other sessions. It is concluded that we have to go forward to more challenging plasma physics, not staying at almost the same place where many people are sitting for a long time compared to the time scale of the rapid progress of intense and ultra-intense laser technology and related laser plasma diagnostics.

  5. 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.

  6. 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

    2015-02-05

    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.

  7. Generation of Low-Frequency Electromagnetic Waves by Spectrally Broad Intense Laser Pulses in a Plasma

    NASA Astrophysics Data System (ADS)

    Tsintsadze, L. N.; Tajima, T.; Nishikawa, K.; Koga, J. K.; Nakagawa, K.; Kishimoto, Y.

    A new mechanism for the emission of low-frequency electromagnetic (EM) waves, including the generation of a quasistatic magnetic field, by a relativistically intense laser pulse with a wide spectrum is presented. The emission is due to modulational and filamentational instabilities of the photon gas in a plasma. The generation of the magnetic field is associated with a significant change in the laser pulse shape during the propagation. This process is identified in our 2D particle-in-cell (PIC) simulations with a high intensity (1019laser pulse.

  8. 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.

  9. The characteristics of an intense laser beam propagating in a corrugated plasma channel

    NASA Astrophysics Data System (ADS)

    Tian, Jian-Min; Tang, Rong-An; Hong, Xue-Ren; Yang, Yang; Wang, Li; Zhou, Wei-Jun; Xue, Ju-Kui

    2016-12-01

    The propagation of an intense laser beam in a corrugated plasma channel is investigated. By using the source-dependent expansion technique, an evolution equation of the laser spot size is derived. The behaviors including aperiodic oscillation, resonance, beat-like wave, and periodic oscillation with multipeak are found and analyzed. The formula for the instantaneous wave numbers of these oscillations is obtained. These theoretical findings are confirmed by the final numerical simulation.

  10. Postionisation of a spatially nonuniform plasma plume under high-intensity femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Krestovskikh, D. A.; Ivanov, K. A.; Tsymbalov, I. N.; Shulyapov, S. A.; Bukin, V. V.; Volkov, R. V.; Rupasov, A. A.; Savel’ev, A. B.

    2017-02-01

    The plasma plume formed by a high-power nanosecond laser pulse on the surface of solid targets as well as the plume parameters after its irradiation by a high-intensity femtosecond laser pulse are investigated by optical diagnostic techniques. Two-dimensional patterns of the electron plasma density are reconstructed from experimentally recorded interferograms at different stages of plasma evolution. It is shown that the interaction of the high-intensity femtosecond radiation with the plasma cloud is accompanied by the field ionisation of atoms and ions as well as by a significant increase in the electron density throughout the interaction volume. Presented at ECLIM2016 (Moscow, 18–23 September 2016).

  11. Anisotropic filamentation instability of intense laser beams in plasmas near the critical density.

    PubMed

    Sheng, Z M; Nishihara, K; Honda, T; Sentoku, Y; Mima, K; Bulanov, S V

    2001-12-01

    The relativistic filamentation instability (RFI) of linearly polarized intense laser beams in plasmas near the critical density is investigated. It is found that the RFI is anisotropic to transverse perturbations in this case; a homogeneous laser beam evolves to a stratified structure parallel to the laser polarization direction, as demonstrated recently with three-dimensional particle-in-cell simulations by Nishihara et al. [Proc. SPIE 3886, 90 (2000)]. A weakly relativistic theory is developed for plasmas near the critical density. It shows that the anisotropy of the RFI results from a suppression of the instability in the laser polarization direction due to the electrostatic response. The anisotropic RFI is also analyzed based on an envelope equation for the laser beam. Finally, the envelope equation is solved numerically, and anisotropic filamentation and self-focusing are illustrated.

  12. 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

  13. Intense Plasma Waveguide Terahertz Sources for High-Field THz Probe Science with Ultrafast Lasers for Solid State Physics

    DTIC Science & Technology

    2016-08-25

    AFRL-AFOSR-UK-TR-2016-0029 Intense Plasma-Waveguide Terahertz Sources for High - Field THz probe science with ultrafast lasers for Solid State Physics...SUPPLEMENTARY NOTES 14.  ABSTRACT Project finished successfully 15.  SUBJECT TERMS High - Field THz probe, INTENSE PLASMA-WAVEGUIDE TERAHERTZ SOURCES, Solid State...an existing high energy laser system, has been applied to the study of intense terahertz radiation generated in gaseous plasmas in purpose

  14. Correlated-intensity velocimeter for arbitrary reflector for laser-produced plasma experiments

    SciTech Connect

    Wang Zhehui; Luo Shengnian; Barnes, Cris W.; Briggs, Matthew E.; Paisley, Dennis L.; Paul, Stephen F.

    2006-10-15

    A laser-based technique, called correlated-intensity velocimeter for arbitrary reflector (CIVAR), is described for velocity measurement of reflecting surfaces in real time. Velocity versus time is an important measurement in laser-produced high-energy density plasma experiments because the motion of the surface depends on both the equation of the state of the surface material and laser-produced plasma. The physics and working principle of CIVAR are the same as those of a previous concept that resolves Doppler shift of plasma light emission using a pair of narrow passband interference filters. One unique feature of CIVAR is that a reflected laser beam is used instead of plasma emission. Therefore, CIVAR is applicable to both emitting and nonemitting reflecting surfaces. Other advantages of CIVAR include its simplicity, lower cost, and unambiguous data analysis that can be fully automated. The design of a single-point CIVAR is described in detail with emphasis on laser wavelength selection and signal-to-noise ratio. The single-point CIVAR system can be expanded into a multiple-point system straightforwardly. It is possible to use CIVAR concept to construct a two-dimensional imaging system for a nonuniform velocity field of a large reflecting surface; such a velocity imaging system may have applications beyond laser-produced plasma experiments, for example, in shock compression of condensed matter.

  15. Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

    SciTech Connect

    Wilks, S.C.; Kruer, W.L.; Young, P.E.; Hammer, J.; Tabak, M.

    1995-04-01

    Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5{times}10{sup 17} W/cm{sup 2}) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime.

  16. 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.

  17. 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.

  18. 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

    2015-10-27

    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.

  19. 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.

  20. Diagnostics of recombining laser plasma parameters based on He-like ion resonance lines intensity ratios

    NASA Astrophysics Data System (ADS)

    Ryazantsev, S. N.; Skobelev, I. Yu; Faenov, A. Ya; Pikuz, T. A.; Grum-Grzhimailo, A. N.; Pikuz, S. A.

    2016-11-01

    While the plasma created by powerful laser expands from the target surface it becomes overcooled, i.e. recombining one. Improving of diagnostic methods applicable for such plasma is rather important problem in laboratory astrophysics nowadays because laser produced jets are fully scalable to young stellar objects. Such scaling is possible because of the plasma hydrodynamic equations invariance under some transformations. In this paper it is shown that relative intensities of the resonance transitions in He-like ions can be used to measure the parameters of recombining plasma. Intensity of the spectral lines corresponding to these transitions is sensitive to the density in the range of 1016-1020 cm-3 while the temperature ranges from 10 to 100 eV for ions with nuclear charge Zn ∼ 10. Calculations were carried out for F VIII ion and allowed to determine parameters of plasma jets created by nanosecond laser system ELFIE (Ecole Polytechnique, France) for astrophysical phenomenon modelling. Obtained dependencies are quite universal and can be used for any recombining plasma containing He-like fluorine ions.

  1. Neutron Generation through Ultra-Intense Laser Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Zulick, C.; Dollar, F.; Willingale, L.; Chvykov, V.; Kalintchenko, G.; Maksimchuk, A.; Thomas, A. G. R.; Yanovsky, V.; Krushelnick, K.; Davis, J.; Petrov, G. M.; Glebov, V.; Nilson, P. M.; Sangster, T. C.; Stoeckl, C.; Craxton, R. S.; Norreys, P. A.; Cobble, J.; Chen, H.

    2012-10-01

    Fast neutrons ( 1 MeV) have important applications in biological imaging, materials testing, and active interrogation for homeland security. Experiments at the HERUCLES laser facility produced neutrons with energies up to 12 MeV in directional beams utilizing ^73Li(p,n)^74Be, and ^73Li(d,n)^84Be reactions. The neutrons were produced in a two-stage pitcher-catcher configuration by accelerating protons and deuterons from micron scale solid targets into bulk LiF. The neutron yield was measured to be up to 2.3 (±1.4) x10^7 neutrons/sr with a flux 6 times higher in the forward direction than at 90^o. Additionally, the kilojoule short-pulse OMEGA EP laser was used to investigate ^21D(d,n)^32He reactions from an underdense deuterated plastic plume. Fast neutron spectra were observed via time-of-flight measurements as a result of deuteron acceleration during the channel formation.

  2. 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.}

  3. Thermal effects in intense laser-plasma interactions

    SciTech Connect

    Shadwick, B.A.; Tarkenton, G.M.; Esarey, E.H.

    2004-10-22

    We present an overview of a new warm fluid model that incorporates leading-order kinetic corrections to the cold fluid model without making any near-equilibrium assumptions. In the quasi-static limit we obtain analytical expressions for the momentum spread and show excellent agreement with solutions of the full time-dependant equations. It is shown that over a large range of initial plasma temperatures, the fields are relatively insensitive to the pressure force. We discuss implications of this work for model validation.

  4. 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.

  5. Megagauss magnetic fields in ultra-intense laser generated dense plasmas

    NASA Astrophysics Data System (ADS)

    Shaikh, Moniruzzaman; Lad, Amit D.; Jana, Kamalesh; Sarkar, Deep; Dey, Indranuj; Kumar, G. Ravindra

    2017-01-01

    Table-top terawatt lasers can create relativistic light intensities and launch megaampere electron pulses in a solid. These pulses induce megagauss (MG) magnetic pulses, which in turn strongly affect the hot electron transport via electromagnetic instabilities. It is therefore crucial to characterize the MG magnetic fields in great detail. Here, we present measurements of the spatio-temporal evolution of MG magnetic fields produced by a high contrast (picosecond intensity contrast 10-9) laser in a dense plasma on a solid target. The MG magnetic field is measured using the magneto-optic Cotton-Mouton effect, with a time delayed second harmonic (400 nm) probe. The magnetic pulse created by the high contrast laser in a glass target peaks much faster and has a more rapid fall than that induced by a low contrast (10-6) laser.

  6. Characterization of preformed plasmas with an interferometer for ultra-short high-intensity laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Sagisaka, A.; Daido, H.; Ogura, K.; Orimo, S.; Hayashi, Y.; Nishiuchi, M.; Mori, M.; Matsukado, K.; Fukumi, A.; Li, Z.; Nakamura, S.; Takagaki, K.; Hazama, H.; Suzuki, M.; Utsumi, T.; Bulanov, S. V.; Esirkepov, T.

    The evolution of an Al preformed plasma produced by a prepulse was observed before and after the arrival of the main pulse by an interferometer using a femtosecond probe pulse. A central density depression due to the ponderomotive force of the main laser pulse in the preformed plasma with a 100 μm scale length was clearly visible after the main pulse irradiation at an intensity of 5×1016 W/cm2. The temporal profiles of the prepulse, characterized by a cross-correlation in conjunction with a precise density profile measurement by an interferometer, contribute to the better understanding of femtosecond laser-matter interactions.

  7. 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.

  8. 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.

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

    DOE PAGES

    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

  10. Structured plasma waveguides and deep EUV generation enabled by intense laser-cluster interactions

    NASA Astrophysics Data System (ADS)

    Layer, Brian David

    Using the unique properties of the interaction between intense, short-pulse lasers and nanometer scale van-der-Waals bonded aggregates (or 'clusters'), modulated waveguides in hydrogen, argon and nitrogen plasmas were produced and extreme ultraviolet (EUV) light was generated in deeply ionized nitrogen plasmas. A jet of clusters behaves as an array of mass-limited, solid-density targets with the average density of a gas. Two highly versatile experimental techniques are demonstrated for making preformed plasma waveguides with periodic structure within a laser-ionized cluster jet. The propagation of ultra-intense femtosecond laser pulses with intensities up to 2 x1017 W/cm2 has been experimentally demonstrated in waveguides generated using both methods, limited by available laser energy. The first uses a 'ring grating' to impose radial intensity modulations on the channel-generating laser pulse, which leads to axial intensity modulations at the laser focus within the cluster jet target. This creates a waveguide with axial modulations in diameter with a period between 35 mum and 2 mm, determined by the choice of ring grating. The second method creates modulated waveguides by focusing a uniform laser pulse within a jet of clusters with ow that has been modulated by periodically spaced wire obstructions. These wires make sharp, stable voids as short as 50 mum with a period as small as 200 mum within waveguides of hydrogen, nitrogen, and argon plasma. The gaps persist as the plasma expands for the full lifetime of the waveguide. This technique is useful for quasi-phase matching applications where index-modulated guides are superior to diameter modulated guides. Simulations show that these 'slow wave' guiding structures could allow direct laser acceleration of electrons, achieving gradients of 80 MV/cm and 10 MV/cm for laser pulse powers of 1.9 TW and 30 GW, respectively. Results are also presented from experiments in which a nitrogen cluster jet from a cryogenically

  11. 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.

  12. 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

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

    SciTech Connect

    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.

    2016-08-25

    Here, 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.

  14. 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

    2016-08-25

    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.

  15. Quasi-matched propagation of an ultrashort and intense laser pulse in a plasma channel

    NASA Astrophysics Data System (ADS)

    Benedetti, Carlo; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2011-10-01

    The propagation of an ultrashort and relativistically-intense laser pulse in a preformed parabolic plasma channel is investigated. The nonlinear paraxial wave equation is solved both analytically and numerically. Numerical solutions are obtained using the 2D cylindrical, envelope, ponderomotive, hybrid PIC/fluid code INF&RNO, recently developed at LBNL. For an arbitrary laser pulse profile with a given power for each longitudinal slice (less then the critical power for self-focusing), we determine the laser intensity distribution ensuring matched propagation in the channel, neglecting non-paraxial effects (self-steepening, red-shifting, etc.). Similarly, in the case of a Gaussian pulse profile, we determine the optimal channel depth yielding a quasi-matched laser propagation, including the plasma density modification induced by the laser-pulse. The analytical results obtained for both cases in the weakly-relativistic intensity regime are presented and validated through comparison with numerical simulations. Work supported by the Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  16. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Intense charge exchange of laser-plasma ions with the atoms of a pulsed gas jet

    NASA Astrophysics Data System (ADS)

    Antonov, V. M.; Boyarintsev, Y. L.; Melekhov, A. V.; Posukh, V. G.; Ponomarenko, A. G.; Shaikhislamov, I. F.

    2007-09-01

    The results of experiments on the interaction of a laser plasma with a pulsed gas jet are presented. The charge exchange of ions with neutral particles was realised for the first time under controllable conditions for a density of the reagents of no less than 1016 cm-3. The resonance pumping of the C3+ ion level with n=3 was observed by spectral methods. The structure of the region of intense charge exchange was determined from plasma photographs. The data obtained suggest that experiments on soft X-ray lasing at a C5+ ion transition are promising.

  17. 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.

  18. 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.

  19. 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.

  20. Weibel instability mediated collisionless shocks using intense laser-driven plasmas

    NASA Astrophysics Data System (ADS)

    Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald; Fernandez, Juan; Ma, Wenjun; Schreiber, Jorg; LANL Collaboration; LMU Team

    2016-10-01

    The origin of cosmic rays remains a long-standing challenge in astrophysics and continues to fascinate physicists. It is believed that ``collisionless shocks'' - where the particle Coulomb mean free path is much larger that the shock transition - are a dominant source of energetic cosmic rays. These shocks are ubiquitous in astrophysical environments such as gamma-ray bursts, supernova remnants, pulsar wind nebula and coronal mass ejections from the sun. Several spacecraft observations have revealed acceleration of charged particles, mostly electrons, to very high energies with in the shock front. There is now also clear observational evidence that supernova remnant shocks accelerate both protons and electrons. The understanding of the microphysics behind collisionless shocks and their particle acceleration is tightly related with nonlinear basic plasma processes and remains a grand challenge. In this poster, we will present results from recent experiments at the LANL Trident laser facility studying collisionless shocks using intense ps laser (80J, 650 fs - peak intensity of 1020 W/cm2) driven near-critical plasmas using carbon nanotube foam targets. A second short pulse laser driven protons from few microns thick aluminum foil is used to image the laser-driven plasma.

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

    PubMed

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

    2012-02-01

    A 10(16) W∕cm(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(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(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.

  2. 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.

  3. Simulation of Ultrafast High-Intensity Laser-Plasma Interaction and X-Ray Production

    NASA Astrophysics Data System (ADS)

    Ma, Guobin; Nantel, Marc; Gu, Shaoting; Umstadter, Donald

    1997-11-01

    We use a 1D Lagrangian hydrodynamic code to simulate the interaction of an ultrashort (100 fs) high intensity ( ~ 10^17 W/cm^2) laser pulse with a dense plasma. The laser energy deposition is calculated self-consistently by solving the time-independent Helmholtz wave equation coupled with plasma temperature and density. The ponderomotive force is included during the calculation. The ionization is calculated with an average atomic model and a detailed atomic code FLY, respectively. We compare the average ionization difference obtained with the two methods under the very same input parameters, such as laser intensity, pulse width, etc. Then, we use FLY to calculate the population density and synthesize the plasma spectra. Detailed energy levels up to n=25 of H-, He-, Li-like ions are considered. The continuum lowering, a very important effect in high-density plasma, is taken into account with three distinct models. We compare the difference due to the models. The space-integrated and time-resolved synthetic spectra using Stewart-Pyatt continuum lowering model are comparable to experiments.

  4. 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.

  5. 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.

  6. Superhot-X-ray and -electron transport in high-intensity CO2-laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Enright, G. D.; Burnett, N. H.

    1985-12-01

    A comprehensive investigation of the high-energy (70-400-keV) X-ray emission from CO2 laser-produced plasmas at intensities up to 3 x 10 to the 14th W/sq cm has revealed the presence of a 'superhot' component. The intensity of this component scales very strongly with incident laser intensity. It is expected that for intensities greater than about 5 x 10 to the 15th W/sq cm energy balance in CO2-laser-produced plasmas would be dominated by the energetic electrons responsible for this high-energy X-ray emission.

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

    SciTech Connect

    Purohit, Gunjan Rawat, Priyanka; Gauniyal, Rakhi

    2016-01-15

    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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Comparing Particle-in-Cell QED Models for High-Intensity Laser-Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Luedtke, Scott V.; Labun, Lance A.; Hegelich, Björn Manuel

    2016-10-01

    High-intensity lasers, such as the Texas Petawatt, are pushing into new regimes of laser-matter interaction, requiring continuing improvement and inclusion of new physics effects in computer simulations. Experiments at the Texas Petawatt are reaching intensity regimes where new physics-quantum electrodynamics (QED) corrections to otherwise classical plasma dynamics-becomes important. We have two particle-in-cell (PIC) codes with different QED implementations. We review the theory of photon emission in QED-strong fields, and cover the differing PIC implementations. We show predictions from the two codes and compare with ongoing 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). HPC resources provided by TACC.

  14. Collimated multi-MeV ion beams from high-intensity laser interactions with underdense plasma.

    PubMed

    Willingale, L; Mangles, S P D; Nilson, P M; Clarke, R J; Dangor, A E; Kaluza, M C; Karsch, S; Lancaster, K L; Mori, W B; Najmudin, Z; Schreiber, J; Thomas, A G R; Wei, M S; Krushelnick, K

    2006-06-23

    A beam of multi-MeV helium ions has been observed from the interaction of a short-pulse high-intensity laser pulse with underdense helium plasma. The ion beam was found to have a maximum energy for He2+ of (40(+3)(-8)) MeV and was directional along the laser propagation path, with the highest energy ions being collimated to a cone of less than 10 degrees. 2D particle-in-cell simulations show that the ions are accelerated by a sheath electric field that is produced at the back of the gas target. This electric field is generated by transfer of laser energy to a hot electron beam, which exits the target generating large space-charge fields normal to its boundary.

  15. Efficient plasma production by intense laser irradiation of low density foam targets

    SciTech Connect

    Tripathi, S.; Chaurasia, S.; Munda, D. S.; Gupta, N. K.; Dhareshwar, L. J.; Nataliya, B.

    2010-12-01

    Experimental investigations conducted on low density structured materials, such as foams have been presented in this paper. These low density foam targets having a density greater than the critical density of the laser produced plasma ({rho}{sub cr{approx_equal}}3 mg{center_dot}cm{sup -3} at laser wavelength 1.06 {mu}m) have been envisaged to have enhanced laser absorption. Experiments were done with an indigenously developed, focused 15 Joule/500 ps Nd: Glass laser at {lambda} = 1064 nm. The focused laser intensity on the target was in the range of I{approx_equal}10{sup 13}-2x10{sup 14} W/cm{sup 2}. Laser absorption was determined by energy balance experiments. Laser energy absorption was observed to be higher than 85%. In another set of experiments, low density carbon foam targets of density 150 mg/cc were compared with the solid carbon targets. The x-ray emission in the soft x-ray region was observed to increase in foam target by about 1.8 times and 2.3 times in carbon foam and Pt doped foam as compared to solid carbon. Further, investigations were also carried out to measure the energy transmitted through the sub-critical density TAC foam targets having a density less than 3 mg/cc. Such targets have been proposed to be used for smoothening of intensity ripples in a high power laser beam profile. Transmission exceeding 1.87% has been observed and consistent with results from other laboratories.

  16. Enhanced laser absorption from radiation pressure in intense laser plasma interactions

    DOE PAGES

    Dollar, F.; Zulick, C.; Raymond, A.; ...

    2017-06-06

    The reflectivity of a short-pulse laser at intensities of 2 x 1021Wcm-2 with ultra-high contrast (10-15) on sub-micrometer silicon nitride foilswas studied experimentally using varying polarizations and target thicknesses. Furthermore, the reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. The experimental results and trends we observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure on the absorption process.more » Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.« less

  17. Enhanced laser absorption from radiation pressure in intense laser plasma interactions

    NASA Astrophysics Data System (ADS)

    Dollar, F.; Zulick, C.; Raymond, A.; Chvykov, V.; Willingale, L.; Yanovsky, V.; Maksimchuk, A.; Thomas, A. G. R.; Krushelnick, K.

    2017-06-01

    The reflectivity of a short-pulse laser at intensities of 2× {10}21 {{Wcm}}-2 with ultra-high contrast ({10}-15) on sub-micrometer silicon nitride foils was studied experimentally using varying polarizations and target thicknesses. The reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. Experimental results and trends observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure on the absorption process. Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.

  18. 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.

  19. Radiation from high-intensity ultrashort-laser-pulse and gas-jet magnetized plasma interaction.

    PubMed

    Dorranian, Davoud; Starodubtsev, Mikhail; Kawakami, Hiromichi; Ito, Hiroaki; Yugami, Noboru; Nishida, Yasushi

    2003-08-01

    Using a gas-jet flow, via the interaction between an ultrashort high-intensity laser pulse and plasma in the presence of a perpendicular external dc magnetic field, the short pulse radiation from a magnetized plasma wakefield has been observed. Different nozzles are used in order to generate different densities and gas profiles. The neutral density of the gas-jet flow measured with a Mach-Zehnder interferometer is found to be proportional to back pressure of the gas jet in the range of 1 to 8 atm. Strength of the applied dc magnetic field varies from 0 to 8 kG at the interaction region. The frequency of the emitted radiation with the pulse width of 200 ps (detection limit) is in the millimeter wave range. Polarization and spatial distributions of the experimental data are measured to be in good agreement with the theory based on the V(p)xB radiation scheme, where V(p) is the phase velocity of the electron plasma wave and B is the steady magnetic field intensity. Characteristics of the radiation are extensively studied as a function of plasma density and magnetic field strength. These experiments should contribute to the development of a new kind of millimeter wavelength radiation source that is tunable in frequency, pulse duration, and intensity.

  20. 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.

  1. 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).

  2. 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.

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

    DOE PAGES

    Poole, P. L.; Krygier, A.; Cochran, G. E.; ...

    2016-08-25

    Here, 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.more » 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.« less

  4. Fast ion acceleration in a foil plasma heated by a multi-picosecond high intensity laser

    NASA Astrophysics Data System (ADS)

    Iwata, Natsumi; Mima, Kunioki; Sentoku, Yasuhiko; Yogo, Akifumi; Nagatomo, Hideo; Nishimura, Hiroaki; Azechi, Hiroshi

    2017-07-01

    We study the one-dimensional expansion of a thin foil plasma irradiated by a high intensity laser with multi-picosecond (ps) pulse durations by using particle-in-cell simulation. Electrons are found to recirculate around the expanding plasma for many times, which results in stochastic heating leading to increase of the electron temperature in the multi-ps time scale beyond the ponderomotive scaling. The conventional isothermal model cannot describe such an expansion of plasmas in the long time scale. We here developed a non-isothermal plasma expansion theory that takes the time dependence of electron temperature into account for describing the multi-ps interactions in one-dimensional geometry. By assuming that the time scale of electron temperature evolution is slow compared with the plasma expansion time scale, we derived a non-self-similar solution. The time evolution of ion maximum energy obtained by the non-isothermal theory explains the details of that observed in the simulation.

  5. Study of plasma produced from deuterized-titanium irradiated by intense laser pulses

    NASA Astrophysics Data System (ADS)

    Skladnik-Sadowska, E.; Malinowski, K.; Sadowski, M. J.; Wolowski, J.; Kubkowska, M.; Gasior, P.; Rosinski, M.; Ladygina, M.

    2010-10-01

    The paper reports on experimental studies of plasma generated by the irradiation of pure titanium (Ti) and deuterium-saturated (Ti+D 2) targets with intense laser beams from a Nd:YAG system operated at 1063 nm (0.5 J) or at 355 nm (0.1 J). The FWHM of laser pulses was 3 ns and the laser power density on the target surface amounted to (0.7- 3)×1010 W/cm2. Spectroscopic studies of plasma plumes were performed with a Mechelle®900 spectrometer in the wavelength range of 300-1100 nm, at a variable exposition time. The recorded spectra showed numerous lines originating from different Ti-ions and D+ desorbed from the (Ti+D 2) target. Estimates of electron temperatures during the plasma expansion gave T e=1.4-2 eV for 0.1 J pulses and 2.3-3 eV for 0.5 J ones. In the Ti+D 2 experiment, the electron density, as estimated from the Dα line, was N e=(1.8- 4.6)×1016 cm-3 and (1.9- 2.1)×1017 cm-3 for 0.1 and 0.5 J pulses, respectively. For the given T e, it was estimated that the Ti-I component density was about one order lower. The emission of D+ and various Ti-ions (ranging from Ti+ to Ti+14) was confirmed by corpuscular measurements, which gave higher values of energy ⟨ E Ti⟩=420-1200 eV and electron temperature T e=12-34 eV for the initial hot-plasma phase.

  6. f Number Increase of a High-Intensity Green Laser Beam in a Plasma

    NASA Astrophysics Data System (ADS)

    Cobble, J. A.; Johnson, R. P.; Mason, R. J.

    1997-11-01

    Earlier(J. A. Cobble, R. P. Johnson, R. J. Mason, Phys. Plasmas 6, 3006 (1997).), we studied the increase in f number of a high-intensity, 1054-nm laser beam passing through a low density, preformed plasma, i. e., an exploding foil. We have extended this work to 527-nm light. Again we find an increase in the f number of the probe beam. Near field imaging of the transmitted green beam shows a factor of four reduction in beam divergence at 8 percent of the critical density. The change is less for lower densities, and the beam compression corresponds to the critical power dropping below the laser power (0.6 TW) as the density increases. The density is estimated from the spectra of stimulated Raman back scatter and from modeling of the target plasma with LASNEX. A CCD camera and a spectrometer with a 200-nm bandwidth were used to record the backscattered spectra. *Work performed under the auspices of the U. S. Department of Energy.

  7. 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.

  8. Bremsstrahlung Temperature Scaling in Ultra-Intense Laser-Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Zulick, C.; Hou, B.; Nees, J.; Thomas, A. G. R.; Krushelnick, K.

    2011-10-01

    The absorption of laser energy during ultra-intense (I > 1018 W/cm2) laser-plasma interactions results in the production of a hot electron current, which can subsequently generate energetic protons, ions, and photons. The energetic photons are of particular interest in isomer excitation, positron production, and homeland security applications. Experiments were performed on the high repetition rate (500 Hz) Lambda Cubed laser (I ~ 5 .1018 , duration 30 fs) allowing high resolution (λ/ Δλ = 300) spectroscopy of X-ray and γ-ray bremsstrahlung photons in the 20 keV to 3 MeV energy range. The effective bremsstrahlung temperature was measured over a range of laser energies, target materials, and detection angles. Additionally, simulations (MCNPX and GEANT4) were used to correlate experimental bremsstrahlung temperatures with hot electron temperatures, which were compared to existing electron temperature scaling laws. This work was supported by the National Science Foundation (NSF) through the FOCUS Physics Frontier Center PHY-0114336, and by the Department of Homeland Security and NSF through grant EECS-0833499.

  9. Peculiarities of the angular distribution of laser radiation intensity scattered by laser-spark plasma in air

    SciTech Connect

    Malyutin, A A; Podvyaznikov, V A; Chevokin, V K

    2010-02-28

    The spatiotemporal study of the diagram of laser radiation scattering by the laser-spark plasma produced by 3-ns and 50-ns pulses is performed. It is shown that radiation appearing outside the laser beam cone is scattered during the first one - two nanoseconds after the air breakdown, when the spark plasma is located in the vicinity of the laser beam waist and has a shape close to spherical.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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 Schrödinger 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.

  11. Observation of a Long-Wavelength Hosing Modulation of a High-Intensity Laser Pulse in Underdense Plasma

    NASA Astrophysics Data System (ADS)

    Kaluza, M. C.; Mangles, S. P. D.; Thomas, A. G. R.; Najmudin, Z.; Dangor, A. E.; Murphy, C. D.; Collier, J. L.; Divall, E. J.; Foster, P. S.; Hooker, C. J.; Langley, A. J.; Smith, J.; Krushelnick, K.

    2010-08-01

    We report the first experimental observation of a long-wavelength hosing modulation of a high-intensity laser pulse. Side-view images of the scattered optical radiation at the fundamental wavelength of the laser reveal a transverse oscillation of the laser pulse during its propagation through underdense plasma. The wavelength of the oscillation λhosing depends on the background plasma density ne and scales as λhosing˜ne-3/2. Comparisons with an analytical model and two-dimensional particle-in-cell simulations reveal that this laser hosing can be induced by a spatiotemporal asymmetry of the intensity distribution in the laser focus which can be caused by a misalignment of the parabolic focusing mirror or of the diffraction gratings in the pulse compressor.

  12. Monoenergetic ion beam acceleration from transversely confined near-critical plasmas by intense laser pulses

    NASA Astrophysics Data System (ADS)

    Zhang, W. L.; Qiao, B.; Shen, X. F.; Chang, H. X.; Zhang, H.; Zhou, C. T.; He, X. T.

    2017-09-01

    An advanced target for production of high-energy monoenergetic ion beams by intense laser pulses is proposed, in which the near-critical plasma is transversely confined between the high-Z dense wires. It is found that the ion acceleration is significantly enhanced due to the strong magnetic dipole vortex formed at the rear of the target, where large electron current density gradients from the wires to the vacuum exist. The magnetic dipole vortex helps to realize the contraction of ion momentum phase spaces and reduction of the beam divergence so that monenergetic, highly directed, and collimated ion beams can be obtained. Two-dimensional particle-in-cell simulations have shown that monoenergetic proton beams with a peak energy of 105 MeV and particle number about 2.2 × 1011 are produced by using the advanced target at a laser intensity of 2.7 × 1020 W/cm2 and a pulse duration of 0.65 ps.

  13. Generation of terahertz radiation by intense hollow Gaussian laser beam in magnetised plasma under relativistic-ponderomotive regime

    NASA Astrophysics Data System (ADS)

    Rawat, Priyanka; Rawat, Vinod; Gaur, Bineet; Purohit, Gunjan

    2017-07-01

    This paper explores the self-focusing of hollow Gaussian laser beam (HGLB) in collisionless magnetized plasma and its effect on the generation of THz radiation in the presence of relativistic-ponderomotive nonlinearity. The relativistic change of electron mass and electron density perturbation due to the ponderomotive force leads to self-focusing of the laser beam in plasma. Nonlinear coupling between the intense HGLB and electron plasma wave leads to generation of THz radiation in plasma. Resonant excitation of THz radiation at different frequencies of laser and electron plasma wave satisfies proper phase matching conditions. Appropriate expressions for the beam width parameter of the laser beam and the electric vector of the THz wave have been evaluated under the paraxial-ray and Wentzel-Kramers Brillouin approximations. It is found that the yield of THz amplitude depends on the focusing behaviour of laser beam, magnetic field, and background electron density. Numerical simulations have been carried out to investigate the effect of laser and plasma parameters on self-focusing of the laser beam and further its effect on the efficiency of the generated THz radiation.

  14. 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.

  15. Anomalies in universal intensity scaling in ultrarelativistic laser-plasma interactions.

    PubMed

    Boyd, T J M; Ondarza-Rovira, R

    2008-09-19

    Laser light incident on targets at intensities such that the electron dynamics is ultrarelativistic gives rise to a harmonic power spectrum extending to high orders and characterized by a relatively slow decay with the harmonic number m that follows a power law dependence, m(-p). Relativistic similarity theory predicts a universal value for p=8/3 up to some cutoff m=m*. The results presented in this Letter suggest that under conditions in which plasma effects contribute to the emission spectrum, the extent of this contribution may invalidate the concept of universal decay. We report a decay with the harmonic number in the ultrarelativistic range characterized by an index 5/3 < or approximately p < or approximately 7/3, significantly weaker than that predicted by the similarity model.

  16. 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.

  17. Experimental study of fast electrons from the interaction of ultra intense laser and solid density plasmas

    NASA Astrophysics Data System (ADS)

    Cho, Byoung-Ick

    A series of experiments have been performed to understand fast electron generation from ultra intense laser-solid interaction, and their transports through a cold material. Using Micro-Electro-Mechanical Systems (MEMS), we contrived various shape of cone and wedge targets. The first set of experiment was for investigating hot electron generations by measuring x-ray production in different energy ranges. Kalpha and hard x-ray yields were compared when the laser was focused into pyramidal shaped cone targets and wedge shaped targets. Hot electron production is highest in the wedge targets irradiated with transverse polarization, though Kalpha is maximized with wedge targets and parallel polarization. These results are explained with particle-in-cell (PIC) simulations utilizing PICLS and OOPIC codes. We also investigate hot electron transport in foil, wedge, and cone targets by observing the transition radiation emitted from the targets rear side along with bremsstrahlung x-ray measurement. Two-dimensional images and spectra of 800 nm coherent transition radiation (CTR) along with ballistic electron transport analysis have revealed the spatial, temporal, and temperature characteristics of hot electron micro-pulses. Various patterns from different target-laser configurations suggest that hot electrons were guided by the strong static electromagnetic fields at the target boundary. Evidence about fast electron guiding in the cone is also observed. CTR at 400 nm showed that two distinct beams of MeV electrons are emitted from the target rear side at the same time. This measurement indicates that two different mechanisms, namely resonance absorption and j x B heating, create two populations of electrons at the targets front side and drive them to different directions, with distinct temperatures and temporal characteristics. This interpretation is consistent with the results from 3D-PIC code Virtual Laser Plasma Laboratory (VLPL).

  18. 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.

  19. Target Surface Area Effects on Hot Electron Dynamics from High Intensity Laser-Plasma Interactions

    DTIC Science & Technology

    2016-08-19

    field Abstract Reduced surface area targets were studied using an ultra- high intensity femtosecond laser in order to determine the effect of electron...New J. Phys. 18 (2016) 063020 doi:10.1088/1367-2630/18/6/063020 PAPER Target surface area effects on hot electron dynamics from high intensity laser...the higher intensity interaction, asymmetric electron current around the hexagonal loop (b)was attributed to field induced current along parallel wire

  20. 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.

  1. Investigation of non-stationary self-focusing of intense laser pulse in cold quantum plasma using ramp density profile

    SciTech Connect

    Habibi, M.; Ghamari, F.

    2012-11-15

    The authors have investigated the non-stationary self-focusing of Gaussian laser pulse in cold quantum plasma. In case of high dense plasma, the nonlinearity in the dielectric constant is mainly due to relativistic high intense interactions and quantum effects. In this paper, we have introduced a ramp density profile for plasma and presented graphically the behavior of spot size oscillations of pulse at rear and front portions of the pulse. It is observed that the ramp density profile and quantum effects play a vital role in stronger and better focusing at the rear of the pulse than at the front in cold quantum plasmas.

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

    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 μm, 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 SiO2 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.

  3. 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.

  4. Order statistics of high-intensity speckles in stimulated Brillouin scattering and plasma-induced laser beam smoothing

    NASA Astrophysics Data System (ADS)

    Hüller, S.; Porzio, A.; Robiche, J.

    2013-02-01

    We have studied plasma-induced smoothing due to stimulated Brillouin scattering (SBS) under the aspect of the extremal statistics of smoothed laser beams. As pointed out in the work by Rose and DuBois (1994 Phys. Rev. Lett. 72 2883), scattered light can be subject to uncontrolled (or even ‘explosive’) behaviour, associated with a critical gain value for SBS. In this work we show how this critical behaviour can be predicted on the basis of the order statistics of laser speckle fields, and we analyse the transition to uncontrolled behaviour of the laser beam due to the dominance of high intensity speckles.

  5. Theoretical investigation of the ultra-intense laser interaction with plasma mirrors in radiation pressure dominant regime

    NASA Astrophysics Data System (ADS)

    Sonia, Krishna Kumar; Maheshwari, K. P.; Jaiman, N. K.

    2017-05-01

    At laser intensity in the range ~ 1022 -1023W/cm2, the radiation pressure starts to play a key role in the interaction of an intense electromagnetic wave with a dense plasma foil. Depending upon the incident laser intensity, polarization of the incident beam and also on the density of the thin plasma layer the mirror motion may be assumed to be uniform, accelerated, or oscillatory. A solid dense plasma slab, accelerated in the radiation pressure dominant (RPD) regime, can efficiently reflect a counter-propagating relativistically strong source pulse consisting of up-shifted frequency and high harmonics. In this RPD regime we present our numerical results for the frequency and brightness of the reflected radiation from a uniformly moving plasma mirror. Our numerical results show that for the appropriate laser and plasma parameters in the case 2γ < {({n}e{λ }s3)}1/6 there are approximately 8.03 × 1042 photons / (mm2 - mrad2 - sec.-0.1% bandwidth) in the energy range ~ 10keV. In the case when 2γ > {({n}e{λ }s3)}1/6 for the same parameters and ad = 300, λd = 0.8 μm, the brightness is found to be 3.27 × 1034 photons / (mm2 - mrad2 - sec. - 0.1% bandwidth) in the energy range ~100 keV.

  6. 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.

  7. 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.

  8. A gated Thomson parabola spectrometer for improved ion and neutral atom measurements in intense laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Tata, Sheroy; Mondal, Angana; Sarkar, Soubhik; Lad, Amit D.; Krishnamurthy, M.

    2017-08-01

    Ions of high energy and high charge are accelerated from compact intense laser produced plasmas and are routinely analysed either by time of flight or Thomson parabola spectrometry. At the highest intensities where ion energies can be substantially large, both these techniques have limitations. Strong electromagnetic pulse noise jeopardises the arrival time measurement, and a bright central spot in the Thomson parabola spectrometer affects the signal to noise ratio of ion traces that approach close to the central spot. We present a gated Thomson parabola spectrometer that addresses these issues and provides an elegant method to improvise ion spectrometry. In addition, we demonstrate that this method provides the ability to detect and measure high energy neutral atoms that are invariably present in most intense laser plasma acceleration experiments.

  9. A gated Thomson parabola spectrometer for improved ion and neutral atom measurements in intense laser produced plasmas.

    PubMed

    Tata, Sheroy; Mondal, Angana; Sarkar, Soubhik; Lad, Amit D; Krishnamurthy, M

    2017-08-01

    Ions of high energy and high charge are accelerated from compact intense laser produced plasmas and are routinely analysed either by time of flight or Thomson parabola spectrometry. At the highest intensities where ion energies can be substantially large, both these techniques have limitations. Strong electromagnetic pulse noise jeopardises the arrival time measurement, and a bright central spot in the Thomson parabola spectrometer affects the signal to noise ratio of ion traces that approach close to the central spot. We present a gated Thomson parabola spectrometer that addresses these issues and provides an elegant method to improvise ion spectrometry. In addition, we demonstrate that this method provides the ability to detect and measure high energy neutral atoms that are invariably present in most intense laser plasma acceleration experiments.

  10. 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.

  11. Backreflection diagnostics for ultra-intense laser plasma experiments based on frequency resolved optical gating

    NASA Astrophysics Data System (ADS)

    Wagner, F.; Hornung, J.; Schmidt, C.; Eckhardt, M.; Roth, M.; Stöhlker, T.; Bagnoud, V.

    2017-02-01

    We report on the development and implementation of a time resolved backscatter diagnostics for high power laser plasma experiments at the petawatt-class laser facility PHELIX. Pulses that are backscattered or reflected from overcritical plasmas are characterized spectrally and temporally resolved using a specially designed second harmonic generation frequency resolved optical gating system. The diagnostics meets the requirements made by typical experiments, i.e., a spectral bandwidth of more than 30 nm with sub-nanometer resolution and a temporal window of 10 ps with 50 fs temporal resolution. The diagnostics is permanently installed at the PHELIX target area and can be used to study effects such as laser-hole boring or relativistic self-phase-modulation which are important features of laser-driven particle acceleration experiments.

  12. Collisionless electrostatic shock formation and ion acceleration in intense laser interactions with near critical density plasmas

    NASA Astrophysics Data System (ADS)

    Liu, M.; Weng, S. M.; Li, Y. T.; Yuan, D. W.; Chen, M.; Mulser, P.; Sheng, Z. M.; Murakami, M.; Yu, L. L.; Zheng, X. L.; Zhang, J.

    2016-11-01

    Laser-driven collisionless electrostatic shock formation and the subsequent ion acceleration have been studied in near critical density plasmas. Particle-in-cell simulations show that both the speed of laser-driven collisionless electrostatic shock and the energies of shock-accelerated ions can be greatly enhanced due to fast laser propagation in near critical density plasmas. However, a response time longer than tens of laser wave cycles is required before the shock formation in a near critical density plasma, in contrast to the quick shock formation in a highly overdense target. More important, we find that some ions can be reflected by the collisionless shock even if the electrostatic potential jump across the shock is smaller than the ion kinetic energy in the shock frame, which seems against the conventional ion-reflection condition. These anomalous ion reflections are attributed to the strong time-oscillating electric field accompanying the laser-driven collisionless shock in a near critical density plasma.

  13. Nonlinear collisional absorption and induced anisotropy in plasmas heated by an intense laser field

    NASA Astrophysics Data System (ADS)

    Bendib, A.

    2017-07-01

    The inverse bremsstrahlung absorption of a laser wave by electrons in homogeneous plasmas is investigated in the range α=v02/vt2≤2 , where v0 is the electron quiver velocity and vt is the thermal velocity. For α≪1 , previous results are recovered. In the range α≥1 , the interplay of collisional absorption and induced plasma anisotropy led to significant new results regarding the electron distribution function and the laser wave damping rate. By increasing α, the low-energy electron population increases, while the collisional absorption rate is still reduced. The temperature anisotropy induced by electron heating is also estimated.

  14. 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.

  15. 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.

  16. Nonlinear theory of intense laser-plasma interactions modified by vacuum polarization effects

    SciTech Connect

    Chen, Wenbo; Bu, Zhigang; Li, Hehe; Luo, Yuee; Ji, Peiyong

    2013-07-15

    The classical nonlinear theory of laser-plasma interactions is corrected by taking account of the vacuum polarization effects. A set of wave equations are obtained by using the Heisenberg-Euler Lagrangian density and the derivative correction with the first-order quantum electrodynamic effects. A model more suitable to formulate the interactions of ultra-strong lasers and high-energy-density plasmas is developed. In the result, some environments in which the effects of vacuum polarization will be enhanced are discussed.

  17. Energetic ion bunches produced in under-dense plasmas by an intense laser pulse (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Moreau, Julien Guillaume; d'Humières, Emmanuel; Nuter, Rachel; Tikhonchuk, Vladimir T.

    2017-05-01

    The mechanisms of the laser acceleration of ions in under-dense or near-critical plasmas (gas, foams) are at their early stage of development [1, 2, 3]. They offer a better laser/electron coupling than in solid targets resulting in a more efficient ion acceleration. They also enable a high repetition rate operation and reduce the formation of debris which could damage the interaction chamber. Our work deals with this interaction regime and focuses on understanding how electrons and ions absorb energy from the laser pulse in low density plasmas. This interaction regime involves various non linear processes that strongly modify the particle distribution functions and induce strong non-local effects. The numerical simulations were performed with the Particle-In-Cell (PIC) code OCEAN [4]. By one dimensional PIC simulations, we have shown [5] that the interaction of a 1 ps long relativistic laser pulse with a under-critical homogeneous (0.5 n_c) plasma leads to a very high plasma absorption reaching 68 % of the laser pulse energy. By a very detailed analysis of the electrostatic and electromagnetic wave spectra in the plasma and a confrontation with the theory [6], we have demonstrated that this energy transfer originates from the process of stimulated Raman scattering in the relativistic regime. Due to the increase of the effective mass of the electrons oscillating in the relativistic laser wave, this instability occurs in plasmas with a density significantly larger than the quarter of critical density and permits a homogeneous electron heating all along the plasma followed by an efficient ion acceleration at the plasma edges. We also have observed the formation of cavities [7], which lead to the formation of quasi-monoenergetic bunches of ions inside the plasma. References [1] A. Macchi, M. Borghesi and M. Passoni, Rev. Mod. Phys. 85 (2013), p. 751. [2] L. Willingale et al, Phys. Rev. Lett. 96 (2006), p. 245002. [3] E d'Humières et al, Journal of Physics : Conference

  18. High-Mach number collisionless shock and photo-ionized non-LTE plasma for laboratory astrophysics with intense lasers

    NASA Astrophysics Data System (ADS)

    Takabe, H.; Kato, T. N.; Sakawa, Y.; Kuramitsu, Y.; Morita, T.; Kadono, T.; Shigemori, K.; Otani, K.; Nagatomo, H.; Norimatsu, T.; Dono, S.; Endo, T.; Miyanishi, K.; Kimura, T.; Shiroshita, A.; Ozaki, N.; Kodama, R.; Fujioka, S.; Nishimura, H.; Salzman, D.; Loupias, B.; Gregory, C.; Koenig, M.; Waugh, J. N.; Woolsey, N. C.; Kato, D.; Li, Y.-T.; Dong, Q.-L.; Wang, S.-J.; Zhang, Y.; Zhao, J.; Wang, F.-L.; Wei, H.-G.; Shi, J.-R.; Zhao, G.; Zhang, J.-Y.; Wen, T.-S.; Zhang, W.-H.; Hu, X.; Liu, S.-Y.; Ding, Y. K.; Zhang, L.; Tang, Y.-J.; Zhang, B.-H.; Zheng, Z.-J.; Sheng, Z.-M.; Zhang, J.

    2008-12-01

    We propose that most of the collisionless shocks in the Universe, for example, supernova remnant shocks, are produced because of the magnetic field generated by Weibel instability and its nonlinear process. In order to verify and validate the computational result confirming this theory, we are carrying out model experiments with intense lasers. We are going to make a collisionless counter-streaming plasma with intense laser ablation based on the scaling law to laser plasma with the particle-in-cell simulation resulting in Weibel-mediated shock formation. Preliminary experimental data are shown. The photo-ionization and resultant non-LTE plasma physics are also very important subjects in astrophysics related to mainly compact objects, for example, black hole, neutron star and white dwarf. Planckian radiation with its temperature 80 100 eV has been produced in gold cavity with irradiation of intense lasers inside the cavity. The sample materials are irradiated by the radiation inside the cavity and absorption and self-emission spectra are observed and analyzed theoretically. It is demonstrated how the effect of non-LTE is essential to reproduce the experimental spectra with the use of a precision computational code.

  19. Low temperature plasmas created by photoionization of gases with intense radiation pulses from laser-produced plasma sources

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Pisarczyk, T.; Wachulak, P.; Chodukowski, T.; Fok, T.; Wegrzyński, Ł.; Kalinowska, Z.; Fiedorowicz, H.

    2016-12-01

    A comparative study of photoionized plasmas created by soft X-ray (SXR) and extreme ultraviolet (EUV) laser plasma sources was performed. The sources, employing high or low energy laser systems, utilized double-stream Xe/He gas-puff targets irradiated with laser pulses of different parameters. The SXR/EUV beams were used for irradiation of a gas stream, injected into a vacuum chamber synchronously with the radiation pulse. Photoionized plasmas produced this way in Ne gas emitted radiation in the SXR/EUV range. The corresponding spectra were dominated by emission lines originating from singly charged ions. Significant differences between spectra obtained in different experimental conditions concern specific transitions in Ne II ions. Creation of photoionized plasmas by SXR or EUV irradiation resulted in K-shell or L-shell emissions respectively. In case of the low energy system absorption spectra were measured additionally. In case of the high energy system, the electron density measurements were performed by laser interferometry, employing a femtosecond laser system. A maximum electron density reached the value of 2·1018cm-3. For the low energy system, a detection limit was too high for the interferometric measurements, thus only an upper estimation for electron density could be made.

  20. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Channeling of microwave radiation in a double line containing a plasma filament produced by intense femtosecond laser pulses in air

    NASA Astrophysics Data System (ADS)

    Bogatov, N. A.; Kuznetsov, A. I.; Smirnov, A. I.; Stepanov, A. N.

    2009-10-01

    The channeling of microwave radiation is demonstrated experimentally in a double line in which a plasma filament produced in air by intense femtosecond laser pulses serves as one of the conductors. It is shown that during the propagation of microwave radiation in this line, ultrashort pulses are formed, their duration monotonically decreasing with increasing the propagation length (down to the value comparable with the microwave field period). These effects can be used for diagnostics of plasma in a filament.

  1. Anti-Stokes scattering and Stokes scattering of stimulated Brillouin scattering cascade in high-intensity laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Feng, Q. S.; Liu, Z. J.; Zheng, C. Y.; Xiao, C. Z.; Wang, Q.; Zhang, H. C.; Cao, L. H.; He, X. T.

    2017-07-01

    Anti-Stokes scattering and Stokes scattering in stimulated Brillouin scattering (SBS) cascades have been researched using the Vlasov-Maxwell simulation. In high-intensity laser-plasma interactions, stimulated anti-Stokes Brillouin scattering (SABS) will occur after second stage SBS rescattering. The mechanism of SABS has been put forward to explain this phenomenon. In the early phase of SBS evolution, only first stage SBS appears and total SBS reflectivity comes from first stage SBS. However, when high-stage SBS and SABS occur, SBS reflectivity will display burst behavior and the total reflectivity comes from the SBS cascade and SABS superimposition. The SABS will compete with the SBS rescattering to determine the total SBS reflectivity. Thus, SBS rescattering including SABS is an important saturation mechanism of SBS and should be taken into account in high-intensity laser-plasma interaction.

  2. On-line depth measurement for laser-drilled holes based on the intensity of plasma emission

    NASA Astrophysics Data System (ADS)

    Ho, Chao-Ching; Chiu, Chih-Mu; Chang, Yuan-Jen; Hsu, Jin-Chen; Kuo, Chia-Lung

    2014-09-01

    The direct time-resolved depth measurement of blind holes is extremely difficult due to the short time interval and the limited space inside the hole. This work presents a method that involves on-line plasma emission acquisition and analysis to obtain correlations between the machining processes and the optical signal output. Given that the depths of laser-machined holes can be estimated on-line using a coaxial photodiode, this was employed in our inspection system. Our experiments were conducted in air under normal atmospheric conditions without gas assist. The intensity of radiation emitted from the vaporized material was found to correlate with the depth of the hole. The results indicate that the estimated depths of the laser-drilled holes were inversely proportional to the maximum plasma light emission measured for a given laser pulse number.

  3. 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.}

  4. 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).

  5. 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.

  6. 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.

  7. 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.

  8. Beat-wave excitation of electron plasma wave by cross-focusing of two intense laser beams

    NASA Astrophysics Data System (ADS)

    Mahmoud, Saleh T.; Pandey, H. D.; Sharma, R. P.

    2003-01-01

    This paper presents the cross-focusing of two intense laser beams in a collisionless plasma, taking into account the relativistic non-linearity. The non-linearity is not bound to large irradiances and this non-linearity is only a perturbation. It should be noted here that while considering the self-focusing due to relativistic electron mass variation, the electron ponderomotive density depression in the channel may also be important. Therefore, these two non-linearities may simultaneously affect the self-focusing process. In the present paper we have considered the situation when only relativistic non-linearity is important. The non-linearity due to relativistic mass variation depends not only on the intensity of one laser but also on the second laser. Therefore, one laser beam affects the dynamics of the second beam and hence a cross-focusing process takes place. The electric field amplitude of the excited electron plasma wave (EPW) has been calculated and its effect on the cross-focusing process has also been discussed. It is observed that the inclusion of a resonantly excited EPW on cross-focusing is significant and the accelerating electric field of the generated EPW becomes affected. A comparison of the theory with the recent experimental observations has also been presented.

  9. 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

  10. High-energy-density electron beam generation in ultra intense laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Liu, Jianxun; Ma, Yanyun; Yang, Xiaohu; Zhao, Jun; Yu, Tongpu; Shao, Fuqiu; Zhuo, Hongbin; Gan, Longfei; Zhang, Guobo; Zhao, Yuan; Yang, Jingkang

    2017-01-01

    By using a two-dimensional particle-in-cell simulation, we demonstrate a scheme for high-energy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum (Al) target. With the laser having a peak intensity of 4 × 1023 W cm‑2, a high quality electron beam with a maximum density of 117nc and a kinetic energy density up to 8.79 × 1018 J m‑3 is generated. The temperature of the electron beam can be 416 MeV, and the beam divergence is only 7.25°. As the laser peak intensity increases (e.g., 1024 W cm‑2), both the beam energy density (3.56 × 1019 J m‑3) and the temperature (545 MeV) are increased, and the beam collimation is well controlled. The maximum density of the electron beam can even reach 180nc. Such beams should have potential applications in the areas of antiparticle generation, laboratory astrophysics, etc. This work is financially supported by the National Natural Science Foundation of China (Nos. 11475260, 11305264, 11622547, 91230205, and 11474360), the National Basic Research Program of China (No. 2013CBA01504), and the Research Project of NUDT (No. JC14-02-02).

  11. On the Acceleration and Transport of Electrons Generated by Intense Laser-Plasma Interactions at Sharp Interfaces

    NASA Astrophysics Data System (ADS)

    May, Joshua Joseph

    The continued development of the chirped pulse amplification technique has allowed for the development of lasers with powers of in excess of 10 15W, for pulse lengths with durations of between .01 and 10 picoseconds, and which can be focused to energy densities greater than 100 giga-atmospheres. When such lasers are focused onto material targets, the possibility of creating particle beams with energy fluxes of comparable parameters arises. Such interactions have a number of theorized applications. For instance, in the Fast Ignition concept for Inertial Confinement Fusion [1], a high-intensity laser efficiently transfers its energy into an electron beam with an appropriate spectra which is then transported into a compressed target and initiate a fusion reaction. Another possible use is the so called Radiation Pressure Acceleration mechanism, in which a high-intensity, circularly polarized laser is used to create a mono-energetic ion beam which could then be used for medical imaging and treatment, among other applications. For this latter application, it is important that the laser energy is transferred to the ions and not to the electrons. However the physics of such high energy-density laser-matter interactions is highly kinetic and non-linear, and presently not fully understood. In this dissertation, we use the Particle-in-Cell code OSIRIS [2, 3] to explore the generation and transport of relativistic particle beams created by high intensity lasers focused onto solid density matter at normal incidence. To explore the generation of relativistic electrons by such interactions, we use primarily one-dimensional (1D) and two-dimensional (2D), and a few three-dimensional simulations (3D). We initially examine the idealized case of normal incidence of relatively short, plane-wave lasers on flat, sharp interfaces. We find that in 1D the results are highly dependent on the initial temperature of the plasma, with significant absorption into relativistic electrons only

  12. Optical guiding of high intensity laser pulses in plasma channel: Interferometrical investigations

    SciTech Connect

    Vogel, N.

    1997-03-01

    The excitation of the electric and self-generated magnetic field by pondermotive force during propagation of 100 ps laser pulse in air are investigated experimentally. Measurements of electron density distribution with high temporal (100 ps) and spatial resolution ({lt}1{mu}m) by interferometry and absorption photography are presented. It is shown that under certain conditions a hollow current channel can be generated. The azimuthal magnetic field in the micro-channel was determined by Faraday rotation of a probing laser beam to 7.6 MG. The charged partical densities in channel exceed 6{center_dot}10{sup 20}cm{sup {minus}3}. Ion acceleration in a pinched annular current channel up to 6 MeV analogous to a micro-{open_quotes}plasma focus{close_quotes} conditions may be realized just at length of 100 {mu}m. {copyright} {ital 1997 American Institute of Physics.}

  13. 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.

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  16. Anomalous He-like ion resonance-to-intercombination line intensity ratios in discharge and laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Shlyaptsev, Vyacheslav; Avaria, G.; Li, J.; Tomasel, F. G.; Busquet, M.; Klapish, M.; Faenov, A. Ya.; Rocca, J. J.; Csu Team; Artep Team; Osaka University Team

    2016-10-01

    Highly anomalous resonance-to-intercombination line intensity ratios were observed in He-like ions spectra from plasmas created in high current density microcapillary channels by ultrafast current pulses (<= 4ns risetime). The emission from discharges containing Si or Al impurities show intercombination line intensities to exceed the resonance line intensities by nearly an order of magnitude. The analysis and detailed hydrodynamic/atomic physics model simulations suggest that the effect responsible for the spectral anomaly reported here is different from those observed to cause similar abnormalities in other plasmas, and is related instead to a new phenomenon in which the very different optical depths in the transverse and axial directions generate triplet level populations greatly exceeding the singlet state populations. The modeling suggests that for different experimental conditions there could be even much larger line ratios observed. The model predictions were tested in wide range parameters and methods of plasma creation including laser produced plasma. This work was supported by NSF Physics Award PHY-1004295.

  17. Laser-induced plasma as a source for an intensive current to produce electromagnetic forces in the weld pool

    NASA Astrophysics Data System (ADS)

    Ambrosy, Günter; Avilov, Vjaceslav; Berger, Peter; Hügel, Helmuth

    2007-05-01

    Laser beam welding performed with a CO II laser by applying a magnetic field perpendicular to the welding direction influences the weld pool dynamics, which changes the seam properties significantly. From these results it was concluded that an intensive current density must exist in the melt. In repeating those welding experiments with a Nd:YAG laser, however, no significant effects could be observed. To explain this discrepancy, detailed trials with both CO II and Nd:YAG lasers were carried out and led to an explanation which is presented in this paper. Looking at the welding process with radiation of 10.6 μm and 1.06 μm, the only significant difference is the presence of a laser-induced plasma plume above the workpiece in the case of the longer wavelength. Therefore, the investigations were concentrated on its possible role in establishing a current flow through the weld pool. This current was directly measured during the welding process (bead on plate): Two aluminum plates separated by an insulated gap of 0.85 mm were moved under the focused beam (3 kW; 5 m/min) and the signal was recorded as function of the gap's position. From these measurements were deduced values of current that amounted to approximately 0.3 A with CO II and more then one order of magnitude less with Nd:YAG lasers.

  18. Quantitative measurement of hard x-ray spectra for high intensity laser produced plasma

    SciTech Connect

    Zhang, Z.; Nishimura, H.; Namimoto, T.; Fujioka, S.; Arikawa, Y.; Hosoda, H.; Azechi, H.; Nishikino, M.; Kawachi, T.; Sagisaka, A.; Orimo, S.; Ogura, K.; Pirozhkov, A.; Yogo, A.; Kiriyama, H.; Kondo, K.; Okano, Y.; Ohshima, S.

    2012-05-15

    X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was 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 for specific x-ray line emissions, is derived as a consequence of this work.

  19. 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.

  20. 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.

  1. Generation of fast protons in moderate-intensity laser-plasma interaction from rear sheath

    NASA Astrophysics Data System (ADS)

    Tan, Zhi-Xin; Huang, Yong-Sheng; Lan, Xiao-Fei; Lu, Jian-Xin; Duan, Xiao-Jiao; Wang, Lei-Jian; Yang, Da-Wei; Guo, Shi-Lun; Wang, Nai-Yan

    2010-05-01

    Forward fast protons are generated by the moderate-intensity laser-foil interaction. Protons with maximum energy 190 keV are measured by using magnetic spectrometer and CR-39 solid state track detectors along the direction normal to the rear surface. The experimental results are also modeled by the particle-in-cell method, investigating the time-varying electron temperature and the rear sheath field. The temporal and spatial structure of the sheath electrical field, revealed in the simulation, suggests that these protons are accelerated by target normal sheath acceleration (TNSA) mechanism.

  2. 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}.

  3. Relativistic self-focusing of intense laser beam in thermal collisionless quantum plasma with ramped density profile

    NASA Astrophysics Data System (ADS)

    Zare, S.; Yazdani, E.; Rezaee, S.; Anvari, A.; Sadighi-Bonabi, R.

    2015-04-01

    Propagation of a Gaussian x-ray laser beam has been analyzed in collisionless thermal quantum plasma with considering a ramped density profile. In this density profile due to the increase in the plasma density, an earlier and stronger self-focusing effect is noticed where the beam width oscillates with higher frequency and less amplitude. Moreover, the effect of the density profile slope and the initial plasma density on the laser propagation has been studied. It is found that, by increasing the initial density and the ramp slope, the laser beam focuses faster with less oscillation amplitude, smaller laser spot size and more oscillations. Furthermore, a comparison is made among the laser self-focusing in thermal quantum plasma, cold quantum plasma and classical plasma. It is realized that the laser self-focusing in the quantum plasma becomes stronger in comparison with the classical regime.

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

    PubMed

    Lancaster, K L; Sherlock, M; Green, J S; Gregory, C D; Hakel, P; Akli, K U; Beg, F N; Chen, S N; Freeman, R R; Habara, H; Heathcote, R; Hey, D S; Highbarger, K; Key, M H; Kodama, R; Krushelnick, K; Nakamura, H; Nakatsutsumi, M; Pasley, J; Stephens, R B; Storm, M; Tampo, M; Theobald, W; Van Woerkom, L; Weber, R L; Wei, M S; Woolsey, N C; Yabuuchi, T; Norreys, P A

    2009-10-01

    The energy transport in cone-guided low- Z targets has been studied for laser intensities on target of 2.5x10(20) W cm(-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 microm for slab targets. The cone slabs showed a reduced spot size of 44+/-10 microm. The shadowgraphy for the aforementioned shots demonstrate the same behavior. The transverse size of the expansion pattern was 357+/-32 microm for the slabs and reduced to 210+/-30 microm. 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.

  5. Hot electron generation in a dense plasma by femtosecond laser pulses of subrelativistic intensity

    SciTech Connect

    Bolshakov, V V; Vorob'ev, A A; Uryupina, D S; Ivanov, K A; Morshedian, Nader; Volkov, Roman V; Savel'ev, Andrei B

    2009-07-31

    We report a study of hot electron generation via the interaction of femtosecond laser pulses of subrelativistic intensity (10{sup 15} to 2x10{sup 17} W cm{sup -2}), having different linear polarisations and nanosecond-scale contrasts, with the surface of 'transparent' (quartz glass) and 'absorbing' (silicon) targets. As the incident pulse intensity increases from 10{sup 15} to 10{sup 17} W cm{sup -2}, the difference in hard X-ray yield and average hot electron energy between s- and p-polarised beams rapidly decreases. This effect can be understood in terms of relativistic electron acceleration mechanisms. (special issue devoted to the 80th birthday of S.A. Akhmanov)

  6. 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.

  7. Time evolution of plasmas using the exact solution of the Boltzmann equation in the presence of an intense laser field

    NASA Astrophysics Data System (ADS)

    Rashid, Shahid

    1990-07-01

    The kinematically based concept of quasi-free electron states developed by Rashid (1988) is extended to obtain a coupling/decoupling technique capable of separating dynamical and kinematical factors. This method is then applied to a reduced form of the Boltzmann equation (assuming that the electrons are in quantum states with quasi-four-momentum, as in an intense laser field). The solution obtained is applicable to the relativistic case and consists of the product of (1) the initial distribution function and (2) a time-evolving part dependent on the differential cross section of the plasma-heating scattering process. The significance of the present analysis for laser-fusion studies is briefly indicated.

  8. 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.

  9. 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.

  10. Evolution of a Plasma Waveguide Created during Relativistic-Ponderomotive Self-Channeling of an Intense Laser Pulse

    NASA Astrophysics Data System (ADS)

    Chen, S.-Y.; Sarkisov, G. S.; Maksimchuk, A.; Wagner, R.; Umstadter, D.

    1998-03-01

    An on-axis plasma density depression channel was observed during and after the passage of a relativistically and ponderomotively self-guided laser pulse through a plasma. Optical interferometry was used to produce time-resolved plasma density distributions, revealing the formation of a plasma waveguide. These results were complemented by the guiding of a collinear trailing pulse.

  11. Evolution of a Plasma Waveguide Created during Relativistic-Ponderomotive Self-channeling of an Intense Laser Pulse

    NASA Astrophysics Data System (ADS)

    Chen, S.-Y.; Sarkisov, G. S.; Maksimchuk, A.; Wagner, R.; Umstadter, D.

    1998-04-01

    An on-axis plasma density depression channel was observed during and after the passage of a relativistically and ponderomotively self-guided laser pulse through a plasma. Optical interferometry was used to produce time-resolved plasma density distributions, revealing the formation of a plasma waveguide. These results were complemented by the guiding of a collinear trailing pulse.

  12. 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.

  13. Identifying the source of super-high energetic electrons in the presence of pre-plasma in laser-matter interaction at relativistic intensities

    NASA Astrophysics Data System (ADS)

    Wu, D.; Krasheninnikov, S. I.; Luan, S. X.; Yu, W.

    2017-01-01

    The generation of super-high energetic electrons influenced by pre-plasma in relativistic intensity laser-matter interaction is studied in a one-dimensional slab approximation with particle-in-cell simulations. Different pre-plasma scale lengths and laser intensities are considered, showing an increase in both particle number and cut-off kinetic energy of electrons with the increase of pre-plasma scale length and laser intensity, the cut-off kinetic energy greatly exceeding the corresponding laser ponderomotive energy. A two-stage electron acceleration model is proposed to explain the underlying physics. The first stage is attributed to the synergetic acceleration by longitudinal electric field and counter-propagating laser pulses, and a scaling law is obtained with efficiency depending on the pre-plasma scale length and laser intensity. These electrons pre-accelerated in the first stage could build up an intense electrostatic potential barrier with maximal value several times as large as the initial electron kinetic energy. Some of the energetic electrons could be further accelerated by reflection off the electrostatic potential barrier, with their finial kinetic energies significantly higher than the values pre-accelerated in the first stage.

  14. 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.

  15. Laser Plasma Material Interactions

    SciTech Connect

    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.

  16. 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

  17. X-ray polarization spectroscopy to study energy transport in ultra-high intensity laser produced plasmas

    SciTech Connect

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

    2009-07-25

    X-ray polarization spectroscopy was studied to derive directly the velocity distribution function (VDF) of hot electrons propagating in plasma created with a high intensity laser pulse. Polarization measurement was made at around 10{sup 18} W/cm{sup 2} using a laser pulse (approx10 J in approx1 ps) from Alise facility at CEA/CESTA. Chlorinated triple-layer targets were irradiated, and Cl Healpha line was observed with an x-ray polarization spectrometer. Polarization degrees were measured as a function of the target overcoat thickness, corresponding to the depth along pre-formed plasma. It is found that the polarization is weakly negative for thin coating, but becomes positive, and finally zero for thick coating. This result is consistent with predictions made with a time-dependent atomic kinetics code developed to gain an insight into the generation of polarized Cl Healpha radiation. The de-polarization on the surface is attributed to excessive bulk electron temperature and that in the deep region to elastic-scattering processes by the isotropic bulk electrons in dense region.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Bartnik, Andrzej; Fiedorowicz, Henryk; Jarocki, Roman; Kostecki, Jerzy; Szczurek, Anna; Szczurek, Mirosław; Wachulak, Przemysław; Pina, Ladislav

    2012-05-01

    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.

  20. 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.

  1. Ion explosion and multi-mega-electron-volt ion generation from an underdense plasma layer irradiated by a relativistically intense short-pulse laser.

    PubMed

    Yamagiwa, M; Koga, J; Tsintsadze, L N; Ueshima, Y; Kishimoto, Y

    1999-11-01

    Ion acceleration and expansion in the interaction of a relativistically intense short-pulse laser with an underdense plasma layer are investigated. Ion and electron dynamics are studied by a two-dimensional particle-in-cell simulation with the real mass ratio. It is shown that the longitudinal electric field induced by electron evacuation due to a large ponderomotive force or light pressure can accelerate ions to several MeV in the direction of the laser propagation. It is after the laser completely passes through the plasma layer that the ion explosion starts to be significant.

  2. X-ray line spectral signatures of plasmas driven by high- intensity ultra-short laser pulses

    NASA Astrophysics Data System (ADS)

    Hakel, Peter

    2001-11-01

    In this dissertation we report on our atomic-kinetics and X-ray line spectra modeling work in the context of plasmas generated by high-intensity, ultrashort-duration pulsed lasers. We focus on characterizing the properties of X-ray line emissions (i.e., intensity, broadening, and polarization) as signatures of plasma conditions, discuss the relevant atomic processes, and introduce atomic kinetics as a means for their quantitative assessment. This also requires the knowledge of detailed line shapes including the effects of Doppler and natural broadening, Stark broadening, line shifts and radiation transport. A suite of time-dependent, collisional-radiative atomic kinetics and spectral codes, CRAK/SPECTRUM, were developed. We applied these codes to the analysis of K- shell aluminum X-ray line spectra recorded in experiments using layered targets performed at the Max-Planck- Institut für Quantenoptik. Modeling calculations indicate that red line shifts observed in these experiments cannot be explained by shifts in the centers of gravity of composite spectral features due to enhanced satellite contributions, but are consistent with line shift effects in resonance and satellite lines. We discuss the mechanism of polarized X-ray line emission in plasmas, its connection to plasma anisotropy, and introduce an atomic kinetics model and code (POLAR) based on the population kinetics of magnetic sublevels. POLAR represents a multi-level, multi-process approach to the problem of polarized spectra in plasmas, and hence it is well suited for plasma applications where cascade effects and alignment transfer can become important. Polarization degrees of X-ray spectral lines computed with POLAR were successfully benchmarked against calculations done with other formalisms, and experimental results obtained at the EBIT facility of Lawrence Livermore National Laboratory. We investigate the polarization of He-like Si X-ray satellite lines as spectral signatures of anisotropy in the

  3. Nonlinear space charge dynamics and modulational instability in the interaction of intense laser pulses with electron-positron plasmas

    NASA Astrophysics Data System (ADS)

    Hashemzadeh, M.; Niknam, A. R.

    2017-06-01

    Nonlinear space charge dynamics and modulational instability in the interaction between ultrashort, intense laser pulses and electron-positron pair plasmas are investigated taking into account the relativistic ponderomotive force and the relativistic mass of electrons and positrons. By coupling Maxwell's equations and hydrodynamic model, the electron and positron density distributions and the dispersion relation for the modulational instability are obtained. Moreover, two coupled nonlinear equations for the scalar and vector potentials are derived and numerically solved. The results show that the growth rate of instability increases with the decrease in the electron and positron temperatures. Moreover, it is shown that when the temperatures of electrons and positrons are not equal to each other, the profiles of scalar potential are similar to bright-like or dark-like solitons.

  4. Self-focusing of a high-intensity laser pulse by a magnetized plasma lens in sub-relativistic regime

    NASA Astrophysics Data System (ADS)

    Abari, Mehdi Etehadi; Sedaghat, Mahsa; Hosseinnejad, Mohammad Taghi

    2017-06-01

    Interaction of high power circularly polarized short laser pulses with a cold underdense magnetized thin plasma lens is analyzed in the sub-relativistic regime. The magnetic field is applied along the direction of the laser field propagation. The evolution equation of the beam spot size is derived and solved by making use of the variational principle approach method. The theoretical investigations reveal that not only the magnetized plasma lens more sufficiently decreases the laser spot size, but also the left-handed circularly polarized beam is more effectively focused by a magnetized plasma lens compared to the right-handed circularly polarized beam.

  5. Self-focusing of a high-intensity laser pulse by a magnetized plasma lens in sub-relativistic regime

    NASA Astrophysics Data System (ADS)

    Abari, Mehdi Etehadi; Sedaghat, Mahsa; Hosseinnejad, Mohammad Taghi

    2017-01-01

    Interaction of high power circularly polarized short laser pulses with a cold underdense magnetized thin plasma lens is analyzed in the sub-relativistic regime. The magnetic field is applied along the direction of the laser field propagation. The evolution equation of the beam spot size is derived and solved by making use of the variational principle approach method. The theoretical investigations reveal that not only the magnetized plasma lens more sufficiently decreases the laser spot size, but also the left-handed circularly polarized beam is more effectively focused by a magnetized plasma lens compared to the right-handed circularly polarized beam.

  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. Toward a self-consistent model of the interaction between an ultra-intense, normally incident laser pulse with an overdense plasma

    SciTech Connect

    Debayle, A.; Sanz, J.; Gremillet, L.; Mima, K.

    2013-05-15

    Following a recent work by Sanz et al. [Phys. Rev. E 85, 046411 (2012)], we elaborate upon a one-dimensional model describing the interaction between an ultra-intense, normally incident laser pulse and an overdense plasma. The analytical solutions of the reflected laser field, the electrostatic field, and the plasma surface oscillation are obtained within the cold-fluid approximation. The high-order harmonic spectrum is calculated from the exact solution of the plasma surface oscillations. In agreement with particle-in-cell simulations, two regimes of harmonic generation are predicted: for moderately relativistic laser intensities, or high plasma densities, the harmonic spectrum is determined by the discontinuity in the derivative of the reflected field when the electron plasma boundary oscillates across the fixed ion boundary. For higher intensities, the electron plasma boundary is confined inside the ion region and oscillates at relativistic velocities, giving rise to a train of reflected attosecond pulses. In both cases, the harmonic spectrum obeys an asymptotic ω{sup −4} scaling. The acceleration of electrons and the related laser absorption efficiency are computed by a test particle method. The model self-consistently reproduces the transition between the “anomalous skin effect” and the “J × B” heating predicted by particle-in-cell simulations. Analytical estimates of the different scalings are presented.

  8. Effect of Laser Wavelength and Ablator Material on Hot Electron Generation in High Power Laser Plasma Interaction at Shock Ignition High Intensity Conditions

    NASA Astrophysics Data System (ADS)

    Wei, M. S.; Alexander, N. B.; Krauland, C. M.; Zhang, S.; Beg, F. N.; Theobald, W.; Betti, R.

    2015-11-01

    Hot electrons with energies <100 keV have been found to augment ablation pressure leading to Gbar shocks in strong spherical shock experiments on OMEGA*. To study this potential benefit at shock ignition-relevant high intensities (~1016 W/cm2) , we have conducted an experiment using the high-energy OMEGA EP laser system to examine the effect of laser wavelength, intensity and ablator material on hot electron generation and energy coupling. Targets are multilayered planar foils consisting of Cu and Al layers with an ablator made of either plastic (CH) or lithium. The target is first irradiated by multi-kJ UV beams at low intensity to produce a long scalelength, hot plasma, as is the case in the shock ignition regime. Correspondingly, this is followed by the injection of the high intensity UV or IR main interaction pulse. The resultant energy, spectrum and angular distributions of the hot electrons are measured via their induced Cu fluorescence emission and the bremsstrahlung radiation. Details of the experiment and results will be presented. Work supported by the DOE/NNSA under Contract DE-NA0002730 (NLUF).

  9. 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.

  10. Interaction of Intense Lasers and Relativistic Electron Beams with Solids, Gases and Plasmas

    DTIC Science & Technology

    1993-06-01

    DYNAMICS IN NEURAL NETWORKS 14 IX. WORKSHOP ON IONOSPHERIC HEATING 16 X. DESIGN AND TESTING OF A CO-AXIAL WIGGLER 18 MAGNET FOR FREE ELECTRON LASERS (FELS) V...relativistic electrons, and esti- mating of a net reduction in the heating rate of the atmosphere. b. since the reduction of ozone concentration changes the...and recognizing spatiotemporal patterns by means of network activation patterns will be explored. 15 IX. WORKSHOP ON IONOSPHERIC HEATING Contact: K

  11. 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.

  12. 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).

  13. 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

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Simulation of generation of bremsstrahlung gamma quanta upon irradiation of thin metal films by ultra-intense femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Andreev, Stepan N.; Garanin, Sergey G.; Rukhadze, Anri A.; Tarakanov, V. P.; Yakutov, B. P.

    2010-06-01

    We report the results of simulations of generation of bremsstrahlung gamma quanta upon irradiation of a thin-film metal target by ultra-intense femtosecond laser pulses. It is shown by the example of a thin gold target that the mean electron energy is twenty five times higher than the mean energy of gamma quanta generated by them. A simple approximating formula is proposed, which establishes a one-to-one relation between these quantities. The angular distributions of electrons and gamma quanta are studied. It is shown that only the angular distribution of high-energy gamma quanta repeats the angular distribution of the electrons leaving the target.

  15. 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.

  16. Spectroscopic investigations of hard x-ray emission from 120 ps laser-produced plasmas at intensities near 10{sup 17} W cm{sup {minus}2}

    SciTech Connect

    Dunn, J.; Young, B.K.F.; Osterheld, A.L.; Foord, M.E.; Walling, R.S.; Stewart, R.E.; Faenov, A.Y.

    1995-11-01

    Spectroscopic investigations of the x-ray emission of plasmas heated by 120 ps, frequency doubled pulses from the JANUS Nd: glass laser are presented. High Z K-shell spectra emitted from slab targets heated to near 10{sup 17} W cm{sup {minus}2} intensity are investigated. High resolution ({gamma}/{Delta}{gamma}>5000) x-ray spectra of multicharged ions of H-like Ti, Co, Ni, Cu, and also H-like Sc in the spectral range 1.5--3.0 {angstrom} are obtained in single laser shots using a spherically bent Mica crystal spectrograph with a 186 mm radius of curvature. The spectra- have one dimensional spatial resolution of about 25{mu}m and indicate that the size of the emission zone of the resonance, transitions is <25{mu}m. Simultaneous x-ray images of the plasma from a charge-coupled device pinhole camera confirmed that the plasma x-ray emission is from a similar sized source. Survey spectra {gamma}/{Delta}{gamma}=500--1000) taken with a flat LiF (200) crystal spectrometer with a charge-coupled device detector complement the high resolution data. Two dimensional LASNEX modeling of the laser target conditions indicate that the high K-shell charge states are produced in the hot dense region of the plasma with electron temperature >2 keV and density{approximately}10{sup 22} cm{sup {minus}3}. These experiments demonstrate that with modest laser energy, plasmas heated by high-intensity 120 ps lasers provide a very bright source of hard {approximately}8 keV x-ray emission.

  17. 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.}

  18. Plasma-Based Generation and Control of a Single Few-Cycle High-Energy Ultrahigh-Intensity Laser Pulse

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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 1023 W/cm2 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.

  19. Amplification and lasing in a plasma channel formed in gases by an intense femtosecond laser pulse in the regime of interference stabilization

    NASA Astrophysics Data System (ADS)

    Bogatskaya, A. V.; Volkova, E. A.; Popov, A. M.

    2016-01-01

    The effect of the interference stabilization of Rydberg atoms in a high-intensity laser field is proposed to create a plasma channel with population inversion between a set of Rydberg states and the low-lying excited and ground state for the conversion of the input laser energy into the visible or VUV and XUV frequency band. Furthermore, there is a possibility of creating population inversion between high-lying Rydberg states that can be used for lasing and amplification in the IR, mid-IR, and terahertz frequency band.

  20. 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.

  1. Plasma Physics Applications to Intense Radiation Sources, Pulsed Power and Space Physics. Short Pulse Ultra Intense Laser-Plasma Interaction Experiment

    DTIC Science & Technology

    1993-05-31

    applications, including gas insulated spark gaps, thyratrons, saturable magnetic inductors, surface flashover switches , etc. Each has different capabilities...result of potentially severe erosion problems on the main output switches of the NIKE laser at the Naval Research Laboratory (NRL), NRL has funded...having to store the full pulse energy at each stage and by making the triggered stage (prior to the magnetic switches ) output pulse as narrow as possible

  2. Evolution of laser pulse shape in a parabolic plasma channel

    NASA Astrophysics Data System (ADS)

    Kaur, M.; Gupta, D. N.; Suk, H.

    2017-01-01

    During high-intensity laser propagation in a plasma, the group velocity of a laser pulse is subjected to change with the laser intensity due to alteration in refractive index associated with the variation of the nonlinear plasma density. The pulse front sharpened while the back of the pulse broadened due to difference in the group velocity at different parts of the laser pulse. Thus the distortion in the shape of the laser pulse is expected. We present 2D particle-in-cell simulations demonstrating the controlling the shape distortion of a Gaussian laser pulse using a parabolic plasma channel. We show the results of the intensity distribution of laser pulse in a plasma with and without a plasma channel. It has been observed that the plasma channel helps in controlling the laser pulse shape distortion. The understanding of evolution of laser pulse shape may be crucial while applying the parabolic plasma channel for guiding the laser pulse in plasma based accelerators.

  3. Experimental investigation of ion production and acceleration mechanism in laser-produced plasma at moderate intensity for nuclear studies @ ELI-NP

    NASA Astrophysics Data System (ADS)

    Altana, C.; Tudisco, S.; Lanzalone, G.; Mascali, D.; Muoio, A.; Brandi, F.; Cristoforetti, G.; Ferrara, P.; Fulgentini, L.; Koester, P.; Labate, L.; Palla, D.; Gizzi, L.

    2017-04-01

    High-power lasers allow to produce plasmas extremely appealing for the nuclear physics studies. An intense scientific program is under preparation for the experiments that will be conducted at the Extreme Light Infrastructure for Nuclear Physics (ELI-NP) in Magurele, Romania. Among the several planned activities, we aim to study low-energy fusion reactions and nuclear structure in a plasma environment. In this work, we discuss the results of some preliminary tests related to the experimental set-up, which is in phase of preparation, for the conduction of this scientific program at ELI-NP. Tests have been performed at ILIL laboratory in Pisa, where a Terawatt laser is installed. The goal of this experimental campaign was a systematic experimental investigation of ion production and acceleration mechanism that occur in laser-produced plasma at moderate intensity, I=1018-1022 W/cm2. We particularly focus the attention to identify the role of the target composition: surface contaminants versus volume contribution.

  4. 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.

  5. Time-resolved dynamics of plasma self-channeling and bulk modification in silica glasses induced by a high-intensity femtosecond laser

    NASA Astrophysics Data System (ADS)

    Cho, Sung-Hak; Kumagai, Hiroshi; Midorikawa, Katsumi; Obara, Minoru

    2000-11-01

    The time-resolved dynamics of plasma self-channeling and refractive index bulk modification in the silica glasses are first observed using a high-intensity femtosecond (110 fs) Ti: sapphire laser ((Lambda) pequals790 nm) We propose the new pump-probe measurement to observe the lifetime of both plasma self-channeling and induced refractive index bulk modification. The energy variation of transmitted probe beam, which propagates transversely through the plasma self- channeling is measured. At the pre-breakdown domain, the lifetime of induced plasma self-channeling is 20 ps and structural transition time for reforming the refractive index change is 10 ps. At the breakdown domain, however, the lifetime of induced plasma formation is 30 ps and structural transition time for forming the optical damage is 40 ps. We find that the process of refractive index bulk modification is significantly different from those of optical damage. We also measure a wavelength shift (blueshift) of reflected probe beam from the surface of the plasma self-channeling induced by the pump beam. A maximum value of blue wavelength shift is 3 nm when the time delay of probe beam is 2 ps. The expanding velocity of the plasma ionization is calculated from the wavelength shirt (blueshift) using the Doppler formula. A maximum velocity of the plasma ionization is calculated to be approximately 6x105 m/s at the delay time of 2 ps.

  6. Diagnostics of laser-produced plasmas based on the analysis of intensity ratios of He-like ions X-ray emission

    NASA Astrophysics Data System (ADS)

    Ryazantsev, S. N.; Skobelev, I. Yu.; Faenov, A. Ya.; Pikuz, T. A.; Higginson, D. P.; Chen, S. N.; Revet, G.; Béard, J.; Portugall, O.; Soloviev, A. A.; Grum-Grzhimailo, A. N.; Fuchs, J.; Pikuz, S. A.

    2016-12-01

    In this paper, we detail the diagnostic technique used to infer the spatially resolved electron temperatures and densities in experiments dedicated to investigate the generation of magnetically collimated plasma jets. It is shown that the relative intensities of the resonance transitions in emitting He-like ions can be used to measure the temperature in such recombining plasmas. The intensities of these transitions are sensitive to the plasma density in the range of 1016-1020 cm-3 and to plasma temperature ranges from 10 to 100 eV for ions with a nuclear charge Zn ˜ 10. We show how detailed calculations of the emissivity of F VIII ions allow to determine the parameters of the plasma jets that were created using ELFIE ns laser facility (Ecole Polytechnique, France). The diagnostic and analysis technique detailed here can be applied in a broader context than the one of this study, i.e., to diagnose any recombining plasma containing He-like fluorine ions.

  7. Pulsed laser beam intensity monitor

    SciTech Connect

    Cason, C.M.; Jones, R.W.

    1982-07-13

    A pulsed laser beam intensity monitor measures the peak power within a selectable cross section of a test laser beam and measures integrated energy of the beam during the pulse period of a test laser. A continuous wave laser and a pulsed ruby laser are coaxially arranged for simultaneously transmitting optical output energy through a crystal flat during the time a test laser pulse is transmitted through the flat. Due to stress birefringence in the crystal, the ruby laser pulse transmitted through the flat is recorded and analyzed to provide peak power information about the test laser output pulse, and the continuous wave laser output reflected from the crystal flat provides a measurement of energy during the test laser pulse.

  8. Online plasma diagnostics of a laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Kai, Gao; Nasr, A. M. Hafz; Song, Li; Mohammad, Mirzaie; Guangyu, Li; Quratul, Ain

    2017-01-01

    In this study, we report a laser interferometry experiment for the online-diagnosing of a laser-produced plasma. The laser pulses generating the plasma are ultra-fast (30 femtoseconds), ultra-intense (tens of Terawatt) and are focused on a helium gas jet to generate relativistic electron beams via the laser wakefield acceleration (LWFA) mechanism. A probe laser beam (λ = 800 nm) which is split-off the main beam is used to cross the plasma at the time of arrival of the main pulse, allowing online plasma density diagnostics. The interferometer setup is based on the NoMarski method in which we used a Fresnel bi-prism where the probe beam interferes with itself after crossing the plasma medium. A high-dynamic range CCD camera is used to record the interference patterns. Based upon the Abel inversion technique, we obtained a 3D density distribution of the plasma density.

  9. Generation of quasi-monoenergetic heavy ion beams via staged shock wave acceleration driven by intense laser pulses in near-critical plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, W. L.; Qiao, B.; Shen, X. F.; You, W. Y.; Huang, T. W.; Yan, X. Q.; Wu, S. Z.; Zhou, C. T.; He, X. T.

    2016-09-01

    Laser-driven ion acceleration potentially offers a compact, cost-effective alternative to conventional accelerators for scientific, technological, and health-care applications. A novel scheme for heavy ion acceleration in near-critical plasmas via staged shock waves driven by intense laser pulses is proposed, where, in front of the heavy ion target, a light ion layer is used for launching a high-speed electrostatic shock wave. This shock is enhanced at the interface before it is transmitted into the heavy ion plasmas. Monoenergetic heavy ion beam with much higher energy can be generated by the transmitted shock, comparing to the shock wave acceleration in pure heavy ion target. Two-dimensional particle-in-cell simulations show that quasi-monoenergetic {{{C}}}6+ ion beams with peak energy 168 MeV and considerable particle number 2.1 × {10}11 are obtained by laser pulses at intensity of 1.66 × {10}20 {{W}} {{cm}}-2 in such staged shock wave acceleration scheme. Similarly a high-quality {{Al}}10+ ion beam with a well-defined peak with energy 250 MeV and spread δ E/{E}0=30 % can also be obtained in this scheme.

  10. 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.

  11. 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.

  12. 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)

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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 a0 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.

  14. 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.

  15. 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.

  16. 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.

  17. [Effects of gas composition and pressure on the intensity and quality of the plasma induced by a high-energy neodymium glass laser].

    PubMed

    Chen, Jin-zhong; Zhao, Shu-rui; Wei, Yan-hong; Guo, Qing-lin; Huai, Su-fang

    2005-03-01

    In this experiment, the effects of gas composition and pressure on the intensity and quality of the plasma induced by a high-energy neodymium glass laser were studied. The experimental results show that the spectral intensity of the plasma in the argon atmosphere is stronger than that in the air when the pressure is the same. For the steel alloy sample, the intensities of the emission spectrum reach the maximum values when the argon pressure is 0.8 x 10(5) Pa. The self-absorption phenomena of Al II 308.22 and Al II 309.27 nm lines strengthen with the increase of the pressure, and even serious self-reversal appears when the pressure is (0.8-0.9) x 10(5) Pa. The temperature of plasma also raises with the increase of the pressure. When the argon pressure is 0.93 x 10(5) Pa, t h e temperature is about 1500 K higher than that when the argon pressure is about 0.43 x 10(5) Pa.

  18. High intensity laser interactions with atomic clusters

    SciTech Connect

    Ditmire, T

    2000-08-07

    The development of ultrashort pulse table top lasers with peak pulse powers in excess of 1 TW has permitted an access to studies of matter subject to unprecedented light intensities. Such interactions have accessed exotic regimes of multiphoton atomic and high energy-density plasma physics. Very recently, the nature of the interactions between these very high intensity laser pulses and atomic clusters of a few hundred to a few thousand atoms has come under study. Such studies have found some rather unexpected results, including the striking finding that these interactions appear to be more energetic than interactions with either single atoms or solid density plasmas. Recent experiments have shown that the explosion of such clusters upon intense irradiation can expel ions from the cluster with energies from a few keV to nearly 1 MeV. This phenomenon has recently been exploited to produce DD fusion neutrons in a gas of exploding deuterium clusters. Under this project, we have undertaken a general study of the intense femtosecond laser cluster interaction. Our goal is to understand the macroscopic and microscopic coupling between the laser and the clusters with the aim of optimizing high flux fusion neutron production from the exploding deuterium clusters or the x-ray yield in the hot plasmas that are produced in this interaction. In particular, we are studying the physics governing the cluster explosions. The interplay between a traditional Coulomb explosion description of the cluster disassembly and a plasma-like hydrodynamic explosion is not entirely understood, particularly for small to medium sized clusters (<1000 atoms) and clusters composed of low-Z atoms. We are focusing on experimental studies of the ion and electron energies resulting from such explosions through various experimental techniques. We are also examining how an intense laser pulse propagates through a dense medium containing these clusters.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Numerical study of the wave-break in the vacuum-plasma interface during the interaction of an intense laser pulse

    NASA Astrophysics Data System (ADS)

    Chakhmachi, Amir; Khalilzadeh, Elnaz; Pishdast, Masoud; Yazdanpanah, Jamalaldin

    2017-08-01

    In this paper, the wave break in the plasma-vacuum interface during the intense laser interaction is investigated. Since the nonlinear wave breaking is a non-adiabatic process, the fully kinetic 1D-3V Particle-In-Cell (PIC) simulation experiments are performed to identify whether that the origin of this mechanism is electromagnetic or electrostatic. Our simulation results show that the nonlinear wave breaking on the vacuum-plasma interface has electrostatic origin. In addition, it is found that for pulse lengths exceeding the plasma wavelength this electrostatic phenomenon comes in conjunction with some active electromagnetic effects having the same impact on the electron acceleration. In these regards, we conduct sophisticated simulations isolating these electromagnetic effects and study the effects of the pulse parameters such as the pulse rise time, pulse length, and pulse shape on the boundary nonlinear wave breaking. The study of the pulse rise-time variation effects shows that as the rise time of the laser pulse decreases, the number of the electrons involved in the nonlinear wave breaking, maximum energy of the trapped electrons and the path length of the accelerated electrons in the phase space are increased. Also, the study of phase space and field patterns in our simulation indicates that the reduction of the pulse flat top duration time causes that the smaller part of the electrons and the smaller portion of the wake wave involve in the nonlinear wave breaking.

  5. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Determination of the intensities of electric fields in gases and plasmas by the CARS method

    NASA Astrophysics Data System (ADS)

    Evsin, O. A.; Kupryanova, E. B.; Ochkin, Vladimir N.; Savinov, Sergei Yu; Tskhai, Sergei N.

    1995-03-01

    A nonlinear optical method for nonperturbing local measurements of the intensity of electric fields in gaseous and plasma molecular media is proposed. It is based on the generation of coherent infrared radiation as a result of biharmonic laser pumping in a static electric field. Investigations are reported of the dependences of the intensity of infrared radiation, emitted by molecular hydrogen at the frequency of the Raman-active vibrational—rotational transition Q(1) (υ = 0, J = 1 → υ = 1, J = 1) in the ground electronic state X1Σg+ (λ = 2.4 μm), on the electric field and gas pressure. The weakest electric field which can be detected at a molecular hydrogen pressure of 1 bar is 20 V cm-1. The capabilities of the method are illustrated by local electric field measurements in a corona discharge.

  6. Plasma Diagnostics of a Capillary Plasma Channel for Laser Guiding

    SciTech Connect

    Terauchi, Hiromitsu; Higashiguchi, Takeshi; Yugami, Noboru; Bobrova, Nadezhda A.

    2010-11-04

    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 Normarski 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 200 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.

  7. Laser-pulse compression using magnetized plasmas

    DOE PAGES

    Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

    2017-02-28

    Proposals to reach the next generation of laser intensities through Raman or Brillouin backscattering have centered on optical frequencies. Higher frequencies are beyond the range of such methods mainly due to the wave damping that accompanies the higher-density plasmas necessary for compressing higher frequency lasers. However, we find that an external magnetic field transverse to the direction of laser propagation can reduce the required plasma density. Using parametric interactions in magnetized plasmas to mediate pulse compression, both reduces the wave damping and alleviates instabilities, thereby enabling higher frequency or lower intensity pumps to produce pulses at higher intensities and longermore » durations. Finally, in addition to these theoretical advantages, our method in which strong uniform magnetic fields lessen the need for high-density uniform plasmas also lessens key engineering challenges or at least exchanges them for different challenges.« less

  8. Laser-pulse compression using magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

    2017-02-01

    Proposals to reach the next generation of laser intensities through Raman or Brillouin backscattering have centered on optical frequencies. Higher frequencies are beyond the range of such methods mainly due to the wave damping that accompanies the higher-density plasmas necessary for compressing higher frequency lasers. However, we find that an external magnetic field transverse to the direction of laser propagation can reduce the required plasma density. Using parametric interactions in magnetized plasmas to mediate pulse compression, both reduces the wave damping and alleviates instabilities, thereby enabling higher frequency or lower intensity pumps to produce pulses at higher intensities and longer durations. In addition to these theoretical advantages, our method in which strong uniform magnetic fields lessen the need for high-density uniform plasmas also lessens key engineering challenges or at least exchanges them for different challenges.

  9. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Microwave generation in an optical breakdown plasma created by modulated laser radiation

    NASA Astrophysics Data System (ADS)

    Antipov, A. A.; Grasyuk, Arkadii Z.; Losev, Leonid L.; Soskov, V. I.

    1990-06-01

    It was established that when laser radiation, intensity modulated at a frequency of 2.2 GHz, interacted with an optical breakdown plasma which it had created, a microwave component appeared in the thermal emf of the plasma. The amplitude of the microwave thermal emf reached 0.7 V for a laser radiation intensity of 6 GW/cm2. Laser radiation with λL = 1.06 μm was converted to the microwave range with λmω = 13 cm in the optical breakdown plasma. A microwave signal power of ~ 0.5 W was obtained from a laser power of ~ 5 MW.

  10. 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.

  11. 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.

  12. Detection of 1 - 100 keV x-rays from high intensity, 500 fs laser- produced plasmas using charge-coupled devices

    SciTech Connect

    Dunn, J.; Young, B.K.F.; Conder, A.D.; Stewart, R.E.

    1996-01-01

    We describe a compact, vacuum compatible, large format, charge- coupled device (CCD) camera for scientific imaging and detection of 1- 100 keV x rays in experiments at LLNL JANUS-1ps laser. A standard, front-illuminated, multi-pin phase device with 250 k electron full well capacity, low dark current (10 pA/cm{sup 2} at 20 C) and low read noise (5 electron rms) is cooled to -35 C to give the camera excellent 15-bit dynamic range and signal-to-noise response. Intensity and x-ray energy linear response were determined for optical and x-ray (<65 keV) photons and are in excellent agreement. Departure from linearity was less than 0.7%. Inherent linearity and energy dispersive characteristics of CCD cameras are well suited for hard x-ray photon counting. X-rays absorbed within the depletion and field-free regions can be distinguished by studying the pulse height spectrum. Results are presented for the detection of 1-100 keV Bremsstrahlung continuum, K-shell and L-shell fluorescence spectra emitted from high intensity (10{sup 18}W cm{sup -2}), 500 fs laser- produced plasmas.

  13. Laser beat frequency heating of a rippled density plasma

    NASA Astrophysics Data System (ADS)

    Vijay, A.; Tripathi, V. K.

    2016-09-01

    Two collinear laser beams propagating through a rippled density plasma, with their frequency difference close to plasma frequency, resonantly excite a large amplitude plasma wave. The density ripple of suitable wavenumber slows down the plasma wave very significantly, leading to strong electron heating via the Landau damping of the plasma wave. An analytical framework of the process is developed and the electron temperature scaling with plasma density, laser power and laser frequency have been obtained. Its relevance to recent experiments on intense short pulse laser plasma interaction has been discussed.

  14. Relativistic self-focusing of an intense laser pulse with hot magnetized plasma in the presence of a helical magnetostatic wiggler

    NASA Astrophysics Data System (ADS)

    Abedi-Varaki, M.; Jafari, S.

    2017-08-01

    In this paper, we study the nonlinear interaction of a circularly polarized laser pulse propagating through a hot magnetized plasma in the presence of a helical magnetostatic wiggler. A non-linear equation that describes the spot-size of the laser beam for both left- and right-hand polarizations has been derived. Non-linear dispersion relation describing the evolution of the laser frequency propagating through the hot magnetized plasma has been obtained. The effect of the wiggler magnetic field strength on the evolution of the laser spot-size has been discussed. The results indicate that for the right-hand polarization with increasing wiggler magnetic field strength, the laser spot-size decreases and the laser pulse becomes more focused. On the contrary, for the left-hand polarization, the self-focusing decreases with increasing wiggler magnetic field strength. Besides, it was found that in the right-hand polarization, the laser spot-size increases with the increasing plasma temperature, and the laser beam becomes more defocused. Furthermore, for the left-hand polarization, the laser self-focusing increases with the decreasing plasma temperature. Further numerical results revealed that by increasing the wiggler field strength, the normalized laser power increases significantly.

  15. NON-EQUILIBRIUM MODELING OF THE FE XVII 3C/3D LINE RATIO IN AN INTENSE X-RAY FREE-ELECTRON LASER EXCITED PLASMA

    SciTech Connect

    Loch, S. D.; Ballance, C. P.; Li, Y.; Fogle, M.; Fontes, C. J.

    2015-03-01

    Recent measurements using an X-ray Free Electron Laser (XFEL) and an Electron Beam Ion Trap at the Linac Coherent Light Source facility highlighted large discrepancies between the observed and theoretical values for the Fe xvii 3C/3D line intensity ratio. This result raised the question of whether the theoretical oscillator strengths may be significantly in error, due to insufficiencies in the atomic structure calculations. We present time-dependent spectral modeling of this experiment and show that non-equilibrium effects can dramatically reduce the predicted 3C/3D line intensity ratio, compared with that obtained by simply taking the ratio of oscillator strengths. Once these non-equilibrium effects are accounted for, the measured line intensity ratio can be used to determine a revised value for the 3C/3D oscillator strength ratio, giving a range from 3.0 to 3.5. We also provide a framework to narrow this range further, if more precise information about the pulse parameters can be determined. We discuss the implications of the new results for the use of Fe xvii spectral features as astrophysical diagnostics and investigate the importance of time-dependent effects in interpreting XFEL-excited plasmas.

  16. A Novel Source of Mesoscopic Particles for Laser Plasma Studies

    DTIC Science & Technology

    2015-12-16

    fast ions from the plasma. Over the last decade laser plasma acceleration has made rapid strides in terms of providing high brightness,4,5 tunable...in Solid Targets with Wavelength-Scale Spheres. Phys. Rev. Lett. 98, 045001 (2007). 13Henig, A. et al. Laser -Driven Shock Acceleration of Ion Beams ...ABSTRACT Intense laser produced plasma are known for generating high dense - high temperatures plasma that is a source for electron, ion acceleration and

  17. Creating Extended and Dense Plasma Channels in Air by Using Spatially and Temporally Shaped Ultra-Intense Laser Pulses

    DTIC Science & Technology

    2011-08-16

    operating at 1064 nm wavelength. The maximum pulse energy of the heater laser is 3.3 J. The heater pulses are combined with femtosecond igniter pulses...properties of the optical fiber where lasers pulses propagate. Figure 3: Top row, left: Temporal waveforms of the Airy pulse with -60,000 fs3...γ equals 105 (W·m)−1, and the zero dispersion wavelength of the fiber is 745 nm. The coupling efficiency of the shaped laser pulses into the fiber in

  18. Experiments on laser-produced plasmas and laser plasma- wall interactions

    NASA Astrophysics Data System (ADS)

    Wang, Quan

    2001-06-01

    The study of the interaction of laser-produced plasmas with a secondary wall has both practical and theoretical significance. The laser-produced plasmas are sources of highly-charged ions, fast electrons, as well as continuum and monochromatic x-ray radiation. Intense x-ray radiation also results when a nanosecond laser-produced plasma collides with a secondary wall positioned close to the target. The study of this interaction is essential to understand the laser-produced plasma expansion, shock wave formation, recombination, collisional excitation and many other transition processes. The laser plasma-wall interaction experiment has been carried out with laser pulses with vastly different time scales. In nanosecond experiment, the plasma-wall interaction was studied with varying target-wall distance. We conclude that the isothermal plasma expansion followed by the shock wave formation near the wall surface contributes to the intense x-ray radiation. We also have done some preliminary research in the femtosecond regime. We claim that the shock wave formation that plays an important role in nanosecond experiment does not play the same role in femtosecond one. We suggest that a femtosecond laser-produced plasma could be an efficient fast electron and monochromatic x- ray source. We also provide some suggestions and predictions for further investigations.

  19. Propagation of chirped laser pulses in a plasma channel

    SciTech Connect

    Jha, Pallavi; Malviya, Amita; Upadhyay, Ajay K.

    2009-06-15

    Propagation of an initially chirped, Gaussian laser pulse in a preformed parabolic plasma channel is analyzed. A variational technique is used to obtain equations describing the evolution of the phase shift and laser spot size. The effect of initial chirp on the laser pulse length and intensity of a matched laser beam propagating in a plasma channel has been analyzed. The effective pulse length and chirp parameter of the laser pulse due to its interaction with plasma have been obtained and graphically depicted. The resultant variation in laser frequency across the laser pulse is discussed.

  20. Applications of Ultra-Intense, Short Laser Pulses

    NASA Astrophysics Data System (ADS)

    Ledingham, Ken W. D.

    The high intensity laser production of electron, proton, ion and photon beams is reviewed particularly with respect to the laser-plasma interaction which drives the acceleration process. A number of applications for these intense short pulse beams is discussed e.g. ion therapy, PET isotope production and laser driven transmutation studies. The future for laser driven nuclear physics at the huge new, multi-petawatt proposed laser installation ELI in Bucharest is described. Many people believe this will take European nuclear research to the next level.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Population Inversions in Ablation Plasmas Generated by Intense Electron Beams.

    DTIC Science & Technology

    1988-11-01

    light weight design, and moderate cost. The Soviets have investigated intense proton beam pumped plasma lasers , however, the University of Michigan...interpretations have been verified by moving the position of the probe laser beam away from the surface of the anode (from 0.1 cm to 0.4 cm) and noting the changes...Properties Effects on Ultraviolet Laser induced Flashover of Angled Plastic insulators in Vacuum", C.L. Ensloe and R. M. Gilgenbach, IEEE 3 Trans. on

  7. X-ray Polarization Measurements at Relativistic Laser Intensities

    SciTech Connect

    Beiersdorfer, P; Shepherd, R; Mancini, R C; Chen, H; Dunn, J; Keenan, R; Kuba, J; Patel, P K; Ping, Y; Price, D F; Widmann, K

    2004-03-20

    An effort has been started to measure the short pulse laser absorption and energy partition at relativistic laser intensities up to 10{sup 21} W/cm{sup 2}. Plasma polarization spectroscopy is expected to play an important role in determining fast electron generation and measuring the electron distribution function.

  8. Spatially Confined Propagation of Intense Ultraviolet Radiation in Plasmas.

    NASA Astrophysics Data System (ADS)

    Shi, Xiaomei

    X-ray amplification requires a high energy deposition rate in a high aspect-ratio volume. High power lasers for x-ray laser pumping have become available with the development of the short pulse and high intensity laser technology capable of producing pulses with a peak power as high as 10^{12} watts. Short pulses of high intensity x-ray have been observed in laser -plasma interactions, which encurages many scientists actively pursuing the goal of constructing practical x-ray lasers. Our approach has concentrated on producing high aspect ratio x-ray amplifying medium by spatially confined propagation of high power laser pulse in plasmas. A high intensity laser beam induces nonlinear refractive index changes in plasma. In the case of subpicosecond ultrahigh power laser-plasma interaction, the dominant mechanisms responsible for the refractive index change in plasmas are: (1) the relativistic free electron mass increase due to the increase of electron oscillation velocity in the intense electromagnetic field of the laser pulses; and (2) displacement of free electrons out of the high intensity region of the laser beam by ponderomotive force. Both of the above effects lead to a refractive index change of the plasma, which in turn has a positive lensing effect on the beam. If the focusing effect is strong enough to overcome diffraction the beam will stay in a spatially confined mode of propagation. This confined propagation provides an effective method of concentrating energy. The field intensity associated with the confined propagation is so high that the highly excited medium with high aspect ratio suitable for x-ray amplification can be achieved. In this research we have successfully demonstrated spatially confined propagation of 500 GW subpicosecond laser pulse in laser induced plasma. The measured diameter of the propagation is less than 2 μm and the aspect ratio of the confined propagation is over 1000. The filed intensity associated with the propagation is

  9. Spectroscopic characterization of laser ablation brass plasma

    NASA Astrophysics Data System (ADS)

    Shaikh, Nek M.; Hafeez, Sarwat; Kalyar, M. A.; Ali, R.; Baig, M. A.

    2008-11-01

    We present optical emission studies of the laser ablation brass plasma generated by the fundamental, second, and third harmonics of a neodymium doped yttrium aluminum garnet laser. The spectra predominantly reveal the spectral lines of the neutral and singly ionized copper and zinc. The excitation temperatures are determined by the Boltzmann plot method, whereas the electron number densities have been extracted from the Stark broadened line profiles. The spatial variations in the spectral line intensities and the plasma parameters at 1000, 500, and 100 mbar air pressures have been evaluated. Besides, the effect of the ambient gases (He, Ne, and Ar), the laser irradiance, and the laser wavelengths on the plasma parameters have been investigated.

  10. High-intensity subpicosecond vacuum ultraviolet laser system

    NASA Astrophysics Data System (ADS)

    Kubodera, Shoichi; Kaku, Masanori; Taniguchi, Yuta; Katto, Masahito; Yokotani, Atsushi; Miyanaga, Noriaki; Mima, Kunioki

    2008-02-01

    We have been developing an ultrashort-pulse high-intensity vacuum ultraviolet (VUV) laser. Ultrashort VUV pulses at 126 nm have been produced in rare-gases by nonlinear wavelength conversion of an infrared Ti:sapphire laser at 882 nm. This pulse will be amplified inside an Ar II* amplifier excited by optical-field-induced ionization electrons. The amplification characteristics of the Ar II* amplifier has been improved by plasma channeling induced by a high-intensity plasma-initiating laser.

  11. Hot Electron Diagnostic in a Solid Laser Target by Buried K-Shell Fluorer Technique from Ultra-Intense (3x1020W/cm2,< 500 J) Laser-Plasma Interactions on the Petawatt Laser at LLNL

    SciTech Connect

    Yasuike, K.; Key, M.H.; Hatchett, S.P.; Snavely, R.A.

    2000-06-29

    Characterization of hot electron production (a conversion efficiency from laser energy into electrons) in ultra intense laser-solid target interaction, using 1.06 {micro}m laser light with an intensity of up to 3 x 10{sup 20}W cm{sup -2} and an on target laser energy of {le}500 J, has been done by observing K{sub {beta}} as well as K{sub {alpha}} emissions from a buried Mo layer in the targets, which are same structure as in the previous 100 TW experiments but done under less laser intensity and energy conditions ({le} 4 x 10{sup 19} Wcm{sup -2} and {le} 30 J). The conversion efficiency from the laser energy into the energy, carried by hot electrons, has been estimated to be {approx}50%, which are little bit higher than the previous less laser energy ({approx} 20 J) experiments, yet the x-ray emission spectra from the target has change drastically, i.e., gamma flash.

  12. 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.

  13. 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.

  14. Concerted manipulation of laser plasma dynamics with two laser pulses

    NASA Astrophysics Data System (ADS)

    Braenzel, J.; Andreev, A. A.; Ehrentraut, L.; Sommer, D.; Schnürer, M.

    2017-05-01

    In this article we present experimental results from a counter-propagating two laser pulse experiment at high intensity and using ultrathin gold and plastic foil targets. We applied one laser pulse as a pre-pulse with an intensity of up to 1x1018 W/cm2. By this method we manipulated the pre-plasma of the foil target with which the stronger laser pulse with an intensity of 6x1019W/cm2 interacts. This alters significantly subsequent processes from the laser plasma interaction which we show the ion acceleration and high harmonic generation. On the one hand, the maximum kinetic ion energy and the maximum charge state for gold ions decline due to the pre-heating of the target in the time range of few ps, on the other hand the number of accelerated ions is increased. For the same parameter range we detected a significant raise of the high harmonic emission. Moreover, we present first experimental observations, that when the second laser pulse is applied as a counter-propagating post-pulse the energy distribution of accelerated carbon ions is charge selective altered. Our findings indicate that using this method a parametric optimization can be achieved, which promises new insights about the concurrent processes of the laser plasma dynamics.

  15. 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.

  16. Development And Optical Absorption Properties Of A Laser Induced Plasma During CO2-Laser Processing

    NASA Astrophysics Data System (ADS)

    Beyer, E.; Bakowsky, L.; Loosen, P.; Poprawe, R.; Herziger, G.

    1984-03-01

    Laser material processing is accompanied by a laser induced plasma in front of the target surface as soon as the laser radiation exceeds a certain critical intensity. For cw CO2-laser machining of metal targets the threshold for plasma onset is about 106 W/cm2. Critical condition for plasma generation at this intensity level is to reach evaporation temperature at the target's surface. At intensity levels exceeding 106 W/cm2 the laser light is interacting with the laser induced plasma and then the plasma in turn interacts with the target. The absorptivity is no longer constant, but increases with increasing intensity of the incident radiation, so that the total amount of power coupled to the target is increasing. This holds up to intensity levels of 2'10 Wicm2. Then the plasma begins to withdraw from the target surface, thus interrupting plasma-target interaction so that the laser power is no longer coupled into the target completely. The results of laser welding (welding depth) in the intensity level of 106 W/cm2 are governed by the product of incident intensity times focus radius, so that welding results are a measure to determine focus radius and laser intensity.

  17. Laser-Plasma Interactions in High-Energy-Density Plasmas

    SciTech Connect

    Baldis, H

    2006-10-17

    High temperature hohlraums (HTH) are designed to reach high radiation temperatures by coupling a maximum amount of laser energy into a small target in a short time. These 400-800 {micro}m diameter gold cylinders rapidly fill with hot plasma during irradiation with multiple beams in 1ns laser pulses. The high-Z plasmas are dense, (electron density, n{sub e}/n{sub c} {approx} 0.1-0.4), hot (electron temperature, T{sub e} {approx} 10keV) and are bathed in a high-temperature radiation field (radiation temperature, T{sub rad} {approx} 300eV). Here n{sub c}, the critical density, equals 9 x 10{sup 21}/cm{sup 3}. The laser beams heating this plasma are intense ({approx} 10{sup 15} - 10{sup 17} W/cm{sup 2}). The coupling of the laser to the plasma is a rich regime for Laser-Plasma Interaction (LPI) physics. The LPI mechanisms in this study include beam deflection and forward scattering. In order to understand the LPI mechanisms, the plasma parameters must be known. An L-band spectrometer is used to measure the and electron temperature. A ride-along experiment is to develop the x-radiation emitted by the thin back wall of the half-hohlraum into a thermal radiation source.

  18. Self-Focusing and de-Focusing of Intense Left- and Right-Hand Polarized Laser Pulse in Hot Magnetized Plasma in the Presence of an External Non-Uniform Magnetized Field

    NASA Astrophysics Data System (ADS)

    Abedi-Varaki, Mehdi; Jafari, Saed

    2017-10-01

    In this paper, self-focusing of an intense circularly polarized laser beam in the presence of a non-uniform positive guide magnetic field with slope constant parameter δ in hot magnetized plasma, using Maxwell's equations and relativistic fluid momentum equation is investigated. An envelope equation governing the spot-size of laser beam for both of left- and right-hand polarizations has been derived, and the effects of the plasma temperature and magnetic field on the electron density distribution of hot plasma with respect to variation of normalized laser spot-size has been studied. Numerical results show that self-focusing is better increased in the presence of an external non-uniform magnetic field. Moreover, in plasma density profile, self-focusing of the laser pulse improves in comparison with no non-uniform magnetic field. Also, with increasing slope of constant parameter of the non-uniform magnetic field, the self-focusing increases, and subsequently, the spot-size of laser pulse propagated through the hot magnetized plasma decreases.

  19. 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.

  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. 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.

  2. 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.

  3. Interference stabilization and UV lasing in a plasma channel formed in gas by intense RF field

    NASA Astrophysics Data System (ADS)

    Bogatskaya, A. V.; Popov, A. M.

    2015-04-01

    The effect of interference stabilization of Rydberg atoms in a high-intensity IR laser field is proposed to create a plasma channel with population inversion for conversion of the input laser energy into the VUV and XUV frequency band.

  4. Astrophysically relevant hydrodynamics experiments using intense lasers

    NASA Astrophysics Data System (ADS)

    Remington, B. A.; Budil, K. S.; Estabrook, K.; Glendinning, S. G.; Gold, D.; Ryutov, D.; Kane, J.; Arnett, D.; Drake, R. P.; Smith, T.; Carroll, J.; McCray, R.; Liang, E.; Keilty, K.; Rubenchik, A.

    1998-04-01

    In a broad-based collaboration, we are developing a series of astrophysically relevant hydrodynamics experiments on the Nova and PetaWatt lasers at Lawrence Livermore National Laboratory. Issues that we are or planning to investigate are deep nonlinear hydrodynamic instabilities in 2D versus 3D, relevant to core-collapse supernova explosions [J. Kane et al., Ap. J. (1997); B.A. Remington et al., Phys. Plasmas (1997).]; strong-shock hydrodynamics relevant to supernova remnant formation [R.P. Drake et al., submitted, Ap. J. (1997).]; radiative blast wave development, of potential interest to gamma-ray burst models [E. Liang et al., 2nd Int. Workshop on LaboratoryAstrophysics using Intense Lasers, Mar. 19-21, 1998, Univ. of AZ.]; and cratering experiments, of possible interest to hypervelocity meteoroid impacts [A. Rubenchik et al., 2nd Int. Workshop on Laboratory Astrophysics using Intense Lasers, Mar. 19-21, 1998, Univ. of AZ.]. An overview of this work will be given, and the issue of scaling will be addressed [D. Ryutov et al., in preparation for submittal to Ap. J. (1998).].

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

    SciTech Connect

    Vinoth Kumar, L.; Manikanta, E.; Leela, Ch.; Prem Kiran, P. E-mail: prem@uohyd.ac.in

    2016-06-07

    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 sin{sup 2}θ/r{sup 2} dependence of the electric dipole radiation. The normalized RF emissions were observed to vary with incident laser intensity (Iλ{sup 2}), 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.

  6. 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.

  7. 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.

  8. 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

  9. Laser plasma diagnostics of dense plasmas

    SciTech Connect

    Glendinning, S.G.; Amendt, P.; Budil, K.S.; Hammel, B.A.; Kalantar, D.H.; Key, M.H.; Landen, O.L.; Remington, B.A.; Desenne, D.E.

    1995-07-12

    The authors describe several experiments on Nova that use laser-produced plasmas to generate x-rays capable of backlighting dense, cold plasmas (p {approximately} 1--3 gm/cm{sup 3}, kT {approximately} 5--10 eV, and areal density {rho}{ell}{approximately} 0.01--0.05 g/cm{sup 2}). The x-rays used vary over a wide range of h{nu}, from 80 eV (X-ray laser) to 9 keV. This allows probing of plasmas relevant to many hydrodynamic experiments. Typical diagnostics are 100 ps pinhole framing cameras for a long pulse backlighter and a time-integrated CCD camera for a short pulse backlighter.

  10. Parametric instabilities in large nonuniform laser plasmas

    SciTech Connect

    Baldis, H.A.; Montgomery, D.S.; Moody, J.D.; Estabrook, K.G.; Berger, R.L.; Kruer, W.L.; Labaune, C.; Batha, S.H.

    1992-09-01

    The study of parametric instabilities in laser plasmas is of vital importance for inertial confinement fusion (ICF). The long scale-length plasma encountered in the corona of an ICF target provides ideal conditions for the growth of instabilities such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and filamentation. These instabilities can have detrimental effects in ICF and their characterization and understanding is of importance. Scattering instabilities are driven through a feedback loop by which the beating between the electromagnetic EM fields of the laser and the scattered light matches the frequency of a local longitudinal mode of the plasma. Any process which interferes with the coherence of this mechanism can substantially alter the behavior of the instability. Of particular interest is the study of laser beam smoothing techniques on parametric instabilities. These techniques are used to improve irradiation uniformity which can suppress hydrodynamic instabilities. Laser beam smoothing techniques have the potential to control the scattering level from parametric instabilities since they provide not only a smoother laser intensity distribution, but also reduced coherence. Beam smoothing techniques that affect the growth of parametric instabilities include spatial smoothing and temporal smoothing by laser bandwidth. Spatial smoothing modifies the phase fronts and temporal distribution of intensities in the focal volume. The transverse intensity spectrum is shifted towards higher spatial wavenumber and can significantly limit the growth of filamentation. Temporal smoothing reduces the coherence time and consequently limits the growth time. Laser bandwidth is required for most smoothing techniques, and can have an independent effect on the instabilities as well.

  11. Hydrogen atom in a laser-plasma

    NASA Astrophysics Data System (ADS)

    Falaye, Babatunde J.; Sun, Guo-Hua; Liman, Muhammed S.; Oyewumi, K. J.; Dong, Shi-Hai

    2016-11-01

    We scrutinize the behaviour of the eigenvalues of a hydrogen atom in a quantum plasma as it interacts with an electric field directed along θ  =  π and is exposed to linearly polarized intense laser field radiation. We refer to the interaction of the plasma with the laser light as laser-plasma. Using the Kramers-Henneberger (KH) unitary transformation, which is the semiclassical counterpart of the Block-Nordsieck transformation in the quantized field formalism, the squared vector potential that appears in the equation of motion is eliminated and the resultant equation is expressed in the KH frame. Within this frame, the resulting potential and the corresponding wavefunction have been expanded in Fourier series, and using Ehlotzky’s approximation we obtain a laser-dressed potential to simulate an intense laser field. By fitting the exponential-cosine-screened Coulomb potential into the laser-dressed potential, and then expanding it in Taylor series up to O≤ft({{r}4},α 09\\right) , we obtain the eigensolution (eigenvalues and wavefunction) of the hydrogen atom in laser-plasma encircled by an electric field, within the framework of perturbation theory formalism. Our numerical results show that for a weak external electric field and a very large Debye screening parameter length, the system is strongly repulsive, in contrast with the case for a strong external electric field and a small Debye screening parameter length, when the system is very attractive. This work has potential applications in the areas of atomic and molecular processes in external fields, including interactions with strong fields and short pulses.

  12. 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.

  13. 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.

  14. 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.

  15. Laser-plasma booster for ion post acceleration

    NASA Astrophysics Data System (ADS)

    Satoh, D.; Kawata, S.; Takahashi, K.; Izumiyama, T.; Barada, D.; Ma, Y. Y.; Kong, Q.; Wang, P. X.; Wang, W. M.; Li, Y. T.; Sheng, Z. M.; Klimo, O.; Limpouch, J.; Andreev, A. A.

    2013-11-01

    A remarkable ion energy increase is demonstrated for post acceleration by a laser-plasma booster. An intense short-pulse laser generates a strong current by high-energy electrons accelerated, when this intense short-pulse laser illuminates a plasma target. The strong electric current creates a strong magnetic field along the high-energy electron current in plasma. During the increase phase in the magnetic field, a longitudinal inductive electric field is induced for the forward ion acceleration by the Faraday law. Our 2.5-dimensional particle-in-cell simulations demonstrate a remarkable increase in ion energy by several tens of MeV.

  16. Filamentation of a relativistic short pulse laser in a plasma

    NASA Astrophysics Data System (ADS)

    Kumar, Naveen; Tripathi, V. K.; Sawhney, B. K.

    2006-06-01

    An intense short pulse laser propagating through a plasma undergoes filamentation instability under the combined effects of relativistic mass variation and ponderomotive force-induced electron density depression. These two nonlinearities superimpose each other. In a tenuous plasma, the filament size scales as {\\sim}( c / \\omega _p\\; a_0 ) \\sqrt 2 \\gamma _0^{1/2} , where ω p is the plasma frequency, a0 is the normalized laser amplitude and γ 0 is the relativistic gamma factor.

  17. Fast photography of plasma formed by laser ablation of aluminum

    NASA Astrophysics Data System (ADS)

    Nedanovska, E.; Ivkovic, M.

    2008-07-01

    In this paper we present results of the temporal and spatial analysis of laser induced plasma performed by use of ICCD fast photography. The plasma is formed by excimer laser ablation of aluminum target in vacuum, air or different pressures of argon and helium. It is shown how the plasma luminous intensity and duration depends on gas pressure. The obtained time dependence of wave propagation distance is also compared with predictions given by the blast wave and drag-force theory also.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Kinetic Approach for Laser-Induced Plasmas

    NASA Astrophysics Data System (ADS)

    Omar, Banaz; Rethfeld, Bärbel

    2008-10-01

    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.

  5. A review of astrophysics experiments on intense lasers

    NASA Astrophysics Data System (ADS)

    Remington, B. A.

    1999-11-01

    Modern, high power laser facilities open new possibilities for simulating astrophysical systems in the laboratory.(S.J. Rose, Laser & Part. Beams 9, 869 (1991); B.H. Ripin et al., Laser & Part. Beams 8, 183 (1990); B.A. Remington et al., Science 284, 1488 (1999); H. Takabe et al., Plasma Phys. Contr. Fusion 41, A75 (1999); R.P. Drake, J. Geophys. Res. 104, 14505 (1999).) Scaled investigations of the hydrodynamics.(J. Kane et al., Phys. Plasmas 6, 2065 (1999); R.P. Drake et al., Ap. J. 500, L157 (1998); D. Ryutov et al., Ap. J. 518, 821 (1999).) and radiative transfer.(J. Wark et al., Phys. Plasmas 4, 2004 (1997); P.K. Patel et al., JQSRT 58, 835 (1997).) relevant to supernovae, and opacities relevant to stellar interiors.(F.J. Rogers and C.A. Iglesias, Science 263, 50 (1994); H. Merdji et al., JSQRT 58, 783 (1997).) are now possible with laser experiments. Equations of state relevant to the interiors of giant planets and brown dwarfs are also being experimentally accessed.(G.W. Collins et al., Science 281, 1178 (1998); A. Benuzzi et al., Phys. Rev. E 54, 2162 (1996).) With the construction of the NIF laser in the U.S., and the LIL and LMJ lasers in France, controlled investigations of thermonuclear burn physics will become possible in the next decade. And with existing and future ultra-high intensity short pulse lasers, investigations of relativistic astrophysical plasmas are becoming possible.(M.H. Key et al., Phys. Plasmas 5, 1966 (1998); F. Pegoraro et al., Plasma Phys. Contr. Fus. 39, B261 (1997).) A review of laboratory astrophysics experiments using intense lasers will be presented, and the potential for the future will be discussed.

  6. High intensity laser beam propagation through a relativistic warm magnetoplasma

    NASA Astrophysics Data System (ADS)

    Rezaei, S.; Jafari Milani, M. R.; Jafari, M. J.

    2017-04-01

    In this work, nonlinear aspects of a circularly polarized high intensity Gaussian laser beam propagating in a relativistic warm magnetized plasma are studied, taking into account the relativistic ponderomotive force. The differential equation governing the dimensionless beam width parameter is achieved and numerically solved by introducing the dielectric permittivity of such plasma and using the paraxial ray approximation. The effects of entrance laser intensity and its polarization state, external magnetic field, and electron temperature on the laser spot size evolution are studied. It is found that for both right and left-handed polarization states increasing initial laser intensity deteriorates the self-focusing mechanism while rising electron temperature improves it. It is also observed that enhancing magnetic field leads to faster and stronger self-focusing in the case of right-handed polarization and an attenuation in the self-focusing process in the case of left-handed one. In addition, the spatial distribution of normalized modified electron density as well as laser intensity profiles as a function of plasma length and beam radius is plotted and discussed for three self-focusing, self-trapping, and defocusing regimes.

  7. 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.

  8. 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.

  9. Laser ignition of plasma off aluminum surfaces

    NASA Astrophysics Data System (ADS)

    Weyl, G.; Pirri, A.; Root, R.

    1980-07-01

    The prompt initiation of a plasma above metal surfaces irradiated by a CO2 laser pulse in the intensities range one million to one billion W per sq cm is modelled. The initiation mechanism is assumed to be the vaporization of flakes or surface defects that are thermally insulated from the bulk surface, followed by laser induced breakdown in the vapor. The fluid dynamics of the expansion in an air background is modelled in the 1 dimensional and 3 dimensional regimes. Breakdown of the vapor due to inverse bremsstrahlung absorption of the laser radiation is calculated specifically for aluminum by use of a Boltzmann code. Results are presented in the form of a map of breakdown time versus incident laser flux and compared with available experimental data.

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

    DOE PAGES

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; ...

    2016-03-03

    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.

  11. Resonant laser plasma channel undulator

    NASA Astrophysics Data System (ADS)

    Lei, Bifeng; Wang, Jingwei; Kharin, Vasily; Rykovanov, Sergey

    2016-10-01

    Laser-plasma based undulators/wigglers attract a lot of attention because of their potential for the next generation of compact ( cm scales) radiation sources. The undulator wavelength of plasma-based devices can theoretically reach 1 mm or less while keeping the undulator strength on the order of unity - values so far unachievable by conventional magnetic undulators. Recently, a novel type of the plasma channel undulator/wiggler (PIGGLER) based on the wakefields generated in a parabolic plasma channel by a laser pulse undergoing centroid oscillations was proposed. It was demonstrated analytically and with the help of numerical simulations that narrow-bandwidth, flexible polarization and bright UV-soft X-ray source can be obtained for the case when the laser pulse centroid oscillation frequency, proportional to the Rayleigh length of the laser pulse, is tuned to be much larger than the betatron frequency. In the current contribution, the case of the resonance, when the laser pulse centroid oscillation frequency is equal to the betatron frequency is discussed. It is shown that significant photon yield enhancement can be. Both linear and nonlinear regimes are studied. Helmholtz Institute Jena, Germany.

  12. 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.

  13. 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.

  14. Intense ultrashort laser-Xe cluster interaction

    NASA Astrophysics Data System (ADS)

    Davis, J.; Whitney, K. G.; Petrova, Tz. B.; Petrov, G. M.

    2012-09-01

    The last several years have witnessed a surge of activity involving the interaction of clusters with intense ultrashort pulse lasers. The interest in laser-cluster interaction has not been only of academic interest, but also because of the wide variety of potential applications. Clusters can be used as a compact source of X-rays, incoherent as well as coherent, and of fast ions capable of driving a fusion reaction in deuterium plasmas. In one set of xenon cluster experiments, in particular, amplification of ˜2.8 Å X-rays has been observed [28]. X-ray amplification in cluster media is a phenomenon of critical importance and may lead to applications such as EUV lithography, EUV and X-ray microscopy, X-ray tomography, and variety of applications in biology and material sciences. However, while amplification of ˜2.8 Å X-rays has been documented in experiments, the mechanism for producing it remains to be fully understood. In this talk, a xenon model of laser-cluster interaction dynamics is presented to shed light on the processes responsible for amplification. The focus of this research is on the feasibility of creating population inversions and gain in some of the inner-shell hole state transitions within the M-shell of highly ionized xenon. The model couples a molecular dynamics (MD) treatment of the explosively-driven, non-Maxwellian cluster expansion to a comprehensive multiphoton-radiative ionization dynamic (ID) model including single- and double-hole state production within the Co- and Fe-like ionization stages of xenon. The hole-state dynamics is self-consistently coupled to a detailed valence-state collisional-radiative dynamics of the Ni-, Co-, and Fe-like ionization stages of xenon. In addition, the model includes tunneling ionization rates that confirm an initial condition assumption that Ni-like ground states can be created almost instantaneously, on the order of a femtosecond or less, i.e., at laser intensities larger than 1019 W/cm2, all of the N

  15. Relativistic mirrors in laser plasmas (analytical methods)

    NASA Astrophysics Data System (ADS)

    Bulanov, S. V.; Esirkepov, T. Zh; Kando, M.; Koga, J.

    2016-10-01

    Relativistic flying mirrors in plasmas are realized as thin dense electron (or electron-ion) layers accelerated by high-intensity electromagnetic waves to velocities close to the speed of light in vacuum. The reflection of an electromagnetic wave from the relativistic mirror results in its energy and frequency changing. In a counter-propagation configuration, the frequency of the reflected wave is multiplied by the factor proportional to the Lorentz factor squared. This scientific area promises the development of sources of ultrashort x-ray pulses in the attosecond range. The expected intensity will reach the level at which the effects predicted by nonlinear quantum electrodynamics start to play a key role. We present an overview of theoretical methods used to describe relativistic flying, accelerating, oscillating mirrors emerging in intense laser-plasma interactions.

  16. 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.

  17. Interaction of Ultraintense Laser Vortices with Plasma Mirrors

    NASA Astrophysics Data System (ADS)

    Denoeud, A.; Chopineau, L.; Leblanc, A.; Quéré, F.

    2017-01-01

    Laser beams carrying orbital angular momentum (OAM) have found major applications in a variety of scientific fields, and their potential for ultrahigh-intensity laser-matter interactions has since recently been considered theoretically. We present an experiment where such beams interact with plasma mirrors up to laser intensities such that the motion of electrons in the laser field is relativistic. By measuring the spatial intensity and phase profiles of the high-order harmonics generated in the reflected beam, we obtain evidence for the helical wavefronts of the high-intensity laser at focus, and study the conservation of OAM in highly nonlinear optical processes at extreme laser intensities. The physical effects determining the field mode content of the twisted harmonic beams are elucidated.

  18. High-Intensity Plasma Glass Melter

    SciTech Connect

    2004-01-01

    Modular high-intensity plasma melter promises improved performance, reduced energy use, and lower emissions. The glass industry has used the same basic equipment for melting glass for the past 100 years.

  19. Laser-Plasma Interactions in Exploding Wires

    DTIC Science & Technology

    1975-07-01

    the optical properties of the laser interaction with this plasma; (3) the scaling of laser heating with laser pulse shape, pulse width (10 to 80 nano...EXPLODING WIRES INITIATION AND LASER HEATING OF EXPLODING WIRE PLASMAS REFERENCES DISTRIBUTION Page 3 5 12 24 41 42 1/2 r mmmmmm «beüsaBamtaän...INTRODUCTION Heating a preformed plasma with a laser has been of interest because ef basic physics and a wide variety of applications. Some previous

  20. 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.

  1. Deflection of a Reflected Intense Vortex Laser Beam.

    PubMed

    Zhang, Lingang; Shen, Baifei; Zhang, Xiaomei; Huang, Shan; Shi, Yin; Liu, Chen; Wang, Wenpeng; Xu, Jiancai; Pei, Zhikun; Xu, Zhizhan

    2016-09-09

    An interesting deflection effect deviating the optical reflection law is revealed in the relativistic regime of intense vortex laser plasma interaction. When an intense vortex laser obliquely impinges onto an overdense plasma target, the reflected beam deflects out of the plane of incidence with an experimentally observable deflection angle. The mechanism is demonstrated by full three-dimensional particle-in-cell simulation as well as analytical modeling using the Maxwell stress tensor. The deflection results from the rotational symmetry breaking of the foil driven by the unsymmetrical shear stress of the vortex beam. The l-dependent shear stress, where l is the topological charge, as an intrinsic characteristic to the vortex beam, plays an important role as the ponderomotive force in relativistic vortex laser matter interaction.

  2. Deflection of a Reflected Intense Vortex Laser Beam

    NASA Astrophysics Data System (ADS)

    Zhang, Lingang; Shen, Baifei; Zhang, Xiaomei; Huang, Shan; Shi, Yin; Liu, Chen; Wang, Wenpeng; Xu, Jiancai; Pei, Zhikun; Xu, Zhizhan

    2016-09-01

    An interesting deflection effect deviating the optical reflection law is revealed in the relativistic regime of intense vortex laser plasma interaction. When an intense vortex laser obliquely impinges onto an overdense plasma target, the reflected beam deflects out of the plane of incidence with an experimentally observable deflection angle. The mechanism is demonstrated by full three-dimensional particle-in-cell simulation as well as analytical modeling using the Maxwell stress tensor. The deflection results from the rotational symmetry breaking of the foil driven by the unsymmetrical shear stress of the vortex beam. The l -dependent shear stress, where l is the topological charge, as an intrinsic characteristic to the vortex beam, plays an important role as the ponderomotive force in relativistic vortex laser matter interaction.

  3. Laser-produced annular plasmas

    SciTech Connect

    Veloso, F.; Chuaqui, H.; Aliaga-Rossel, R.; Favre, M.; Mitchell, I. H.; Wyndham, E.

    2006-06-15

    A new technique is presented for the formation of annular plasmas on a metal surface with a high-power laser using a combination of axicon and converging lenses. The annular plasma formed on a titanium target in a chamber of hydrogen gas was investigated using schlieren imaging and Mach Zehnder interferometry. Expansion of the plasma was shown to be anisotropic with velocities of {approx}10{sup 3}-10{sup 4} m/s. Electron densities of 10{sup 18} cm{sup -3} were measured with radial profiles that confirm the presence of a hollow structure. The interferometric observations also show the presence of an inward shock wave traveling to the center of the annular plasma, which compresses the background neutrals, reaching a density around 18 times initial gas density, at 95 ns after the initial annular plasma is produced.

  4. Laser-produced plasma source system development

    NASA Astrophysics Data System (ADS)

    Fomenkov, Igor V.; Brandt, David C.; Bykanov, Alexander N.; Ershov, Alexander I.; Partlo, William N.; Myers, David W.; Böwering, Norbert R.; Vaschenko, Georgiy O.; Khodykin, Oleh V.; Hoffman, Jerzy R.; Vargas L., Ernesto; Simmons, Rodney D.; Chavez, Juan A.; Chrobak, Christopher P.

    2007-03-01

    This paper describes the development of laser produced plasma (LPP) technology as an EUV source for advanced scanner lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193 nm immersion technology for critical layer patterning below 32 nm beginning with beta generation scanners in 2009. This paper describes the development status of subsystems most critical to the performance to meet joint scanner manufacturer requirements and semiconductor industry standards for reliability and economic targets for cost of ownership. The intensity and power of the drive laser are critical parameters in the development of extreme ultraviolet LPP lithography sources. The conversion efficiency (CE) of laser light into EUV light is strongly dependent on the intensity of the laser energy on the target material at the point of interaction. The total EUV light generated then scales directly with the total incident laser power. The progress on the development of a short pulse, high power CO2 laser for EUV applications is reported. The lifetime of the collector mirror is a critical parameter in the development of extreme ultra-violet LPP lithography sources. The deposition of target materials and contaminants, as well as sputtering of the collector multilayer coating and implantation of incident particles can reduce the reflectivity of the mirror substantially over the exposure time even though debris mitigation schemes are being employed. The results of measurements of high energy ions generated by a short-pulse CO2 laser on a laser-produced plasma EUV light source with Sn target are presented. Droplet generation is a key element of the LPP source being developed at Cymer for EUV lithography applications. The main purpose of this device is to deliver small quantities of liquid target material as droplets to the laser focus. The EUV light in such configuration is obtained as a result of creating a highly ionized plasma from the material of the

  5. Laser Plasma Microthruster Performance Evaluation

    NASA Astrophysics Data System (ADS)

    Luke, James R.; Phipps, Claude R.

    2003-05-01

    The micro laser plasma thruster (μLPT) is a sub-kilogram thruster that is capable of meeting the Air Force requirements for the Attitude Control System on a 100-kg class small satellite. The μLPT uses one or more 4W diode lasers to ablate a solid fuel, producing a jet of hot gas or plasma which creates thrust with a high thrust/power ratio. A pre-prototype continuous thrust experiment has been constructed and tested. The continuous thrust experiment uses a 505 mm long continuous loop fuel tape, which consists of a black laser-absorbing fuel material on a transparent plastic substrate. When the laser is operated continuously, the exhaust plume and thrust vector are steered in the direction of the tape motion. Thrust steering can be avoided by pulsing the laser. A torsion pendulum thrust stand has been constructed and calibrated. Many fuel materials and substrates have been tested. Best performance from a non-energetic fuel material was obtained with black polyvinyl chloride (PVC), which produced an average of 70 μN thrust and coupling coefficient (Cm) of 190 μN/W. A proprietary energetic material was also tested, in which the laser initiates a non-propagating detonation. This material produced 500 μN of thrust.

  6. Tunable Plasma-Wave Laser Amplifier

    NASA Astrophysics Data System (ADS)

    Bromage, J.; Haberberger, D.; Davies, A.; Bucht, S.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.

    2016-10-01

    Raman amplification is a process by which a long energetic pump pulse transfers its energy to a counter-propagating short seed pulse through a resonant electron plasma wave. Since its conception, theory and simulations have shown exciting results with up to tens of percent of energy transfer from the pump to the seed pulse. However, experiments have yet to surpass transfer efficiencies of a few percent. A review of past literature shows that largely chirped pump pulses and finite temperature wave breaking could have been the two most detrimental effects. A Raman amplification platform is being developed at the Laboratory for Laser Energetics where a combination of a high-intensity tunable seed laser with sophisticated plasma diagnostics (dynamic Thomson scattering) will make it possible to find the optimal parameter space for high-energy transfer. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  7. Interaction physics of multipicosecond Petawatt laser pulses with overdense plasma.

    PubMed

    Kemp, A J; Divol, L

    2012-11-09

    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.

  8. 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.

  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.

  10. Microwave interferometry of laser induced air plasmas formed by short laser pulses

    SciTech Connect

    Jungwirth, Patrick 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 μm. 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.

  11. Laser plasma as an effective ion source

    NASA Astrophysics Data System (ADS)

    Masek, Karel; Krasa, Josef; Laska, Leos; Pfeifer, Miroslav; Rohlena, Karel; Kralikova, Bozena; Skala, Jiri; Woryna, Eugeniusz; Farny, J.; Parys, Piotr; Wolowski, Jerzy; Mraz, W.; Haseroth, H.; Sharkov, B.; Korschinek, G.

    1998-09-01

    Ions in different charge state and with different energy distribution are generated in the process of interaction of intense laser radiation with solid targets. Multiply charged ions of medium- and high-Z elements (Al, Co, Ni, Cu, Sn, Ta, W, Pt, Au, Pb, Bi), produced by photodissociation iodine laser system PERUN ((lambda) equals 1.315 micrometer, EL approximately 40 J, (tau) approximately 500 ps) are reported. Corpuscular diagnostics based on time-of-flight method (ion collectors and a cylindrical electrostatic ion energy analyzer) as well as Thomson parabola spectrometer were used in the experiments. The ions in maximum charge state up to about 55+ and with energies of several MeV were registered at a distance of about 2 m from the plasma plume. Measured ion current densities higher than 10 mA/cm2 in about 1 m from the target demonstrate the performance of laser ion source. A theoretical interpretation of ion spectra is attempted.

  12. 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.

  13. 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.

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Implantation of high-energy ions produced by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Golishnikov, D. M.; Gordienko, Vyacheslav M.; Savel'ev, Andrei B.; Chernysh, V. S.

    2005-01-01

    Germanium ions of an expanding plasma were implanted in a silicon collector. The plasma was produced by a femtosecond laser pulse with an intensity of ~1015 W cm-2 at the surface of the solid-state target. A technique was proposed for determining the energy characteristics of the ion component of the laser plasma from the density profile of the ions implanted in the substrate.

  15. Isoelectronic line intensity ratios for plasma electron temperature measurement (invited)

    NASA Astrophysics Data System (ADS)

    Marjoribanks, Robin S.; Budnik, Fredric; Kulcsár, Gábor; Zhao, Liang

    1995-01-01

    Strictly speaking, temperature is uniquely defined only in plasmas which are in complete thermodynamic equilibrium. In typical laser-produced plasmas, measurement of electron temperature amounts to a parametrization of some part of the distribution of electron energies, typically inferred from the recombination continuum, or from the ratio of spectral lines that are implicitly dependent on the electron distribution. Where the plasma is highly transient, suffers appreciable opacity, or is subject to a background radiation field, the interpretation of temperature from disparate spectral lines can become untrustworthy. For these complicated plasmas, a conceptually simpler spectral line diagnostic offers great advantages. A technique has been introduced that begins with plasmas that include two elements of similar atomic number, in a known ratio, and compares isoelectronic lines from ions that differ only in their nuclear charge Z, and thus in their ionization potentials χi. Since these two have different values of the same dimensionless parameter Te/χi, the ratio of intensities of isoelectronic lines can be interpreted to determine the temperature Te. The technique and its areas of advantage are described, the applications made to the special problems of laboratories elsewhere are summarized, and this particular progress in application to laser plasmas produced by high-intensity picosecond pulses are reported here.

  16. Resonant enhancement for amplitude-modulated laser filament induced magnetic field in an inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Annou, R.; Tripathi, V. K.; Srivastava, M. P.

    1996-09-01

    The Tripathi-Liu [Phys. Plasmas 1, 990 (1994)] model of magnetic-field generation due to an amplitude-modulated laser in a plasma is revisited. At plasma resonance, where modulation frequency equals the plasma frequency, significant enhancement in the magnetic field is seen. The magnetic field is found to scale directly with laser intensity and plasma frequency, while scaling inversely with laser spot size.

  17. Laser-Induced Incandescence: Excitation Intensity

    NASA Astrophysics Data System (ADS)

    Vander Wal, Randall L.; Jensen, Kirk A.

    1998-03-01

    Assumptions of theoretical laser-induced incandescence (LII) models along with possible effects of high-intensity laser light on soot aggregates and the constituent primary particles are discussed in relation to selection of excitation laser fluence. Ex situ visualization of laser-heated soot by use of transmission electron microscopy reveals significant morphological changes (graphitization) induced by pulsed laser heating. Pulsed laser transmission measurements within a premixed laminar sooting flame suggest that soot vaporization occurs for laser fluences greater than 0.5 J cm 2 at 1064 nm. Radial LII intensity profiles at different axial heights in a laminar ethylene gas jet diffusion flame reveal a wide range of signal levels depending on the laser fluence that is varied over an eight fold range. Results of double-pulse excitation experiments in which a second laser pulse heats in situ the same soot that was heated by a prior laser pulse are detailed. These two-pulse measurements suggest varying degrees of soot structural change for fluences below and above a vaporization threshold of 0.5 J cm 2 at 1064 nm. Normalization of the radial-resolved LII signals based on integrated intensities, however, yields self-similar profiles. The self-similarity suggests robustness of LII for accurate relative measurement of soot volume fraction despite the morphological changes induced in the soot, variations in soot aggregate and primary particle size, and local gas temperature. Comparison of LII intensity profiles with soot volume fractions ( f v ) derived by light extinction validates LII for quantitative determination of f v upon calibration for laser fluences ranging from 0.09 to 0.73 J cm 2 .

  18. Laser-induced incandescence: excitation intensity.

    PubMed

    Vander Wal, R L; Jensen, K A

    1998-03-20

    Assumptions of theoretical laser-induced incandescence (LII) models along with possible effects of high-intensity laser light on soot aggregates and the constituent primary particles are discussed in relation to selection of excitation laser fluence. Ex situ visualization of laser-heated soot by use of transmission electron microscopy reveals significant morphological changes (graphitization) induced by pulsed laser heating. Pulsed laser transmission measurements within a premixed laminar sooting flame suggest that soot vaporization occurs for laser fluences greater than 0.5 J/cm(2) at 1064 nm. Radial LII intensity profiles at different axial heights in a laminar ethylene gas jet diffusion flame reveal a wide range of signal levels depending on the laser fluence that is varied over an eight fold range. Results of double-pulse excitation experiments in which a second laser pulse heats in situ the same soot that was heated by a prior laser pulse are detailed. These two-pulse measurements suggest varying degrees of soot structural change for fluences below and above a vaporization threshold of 0.5 J/cm(2) at 1064 nm. Normalization of the radial-resolved LII signals based on integrated intensities, however, yields self-similar profiles. The self-similarity suggests robustness of LII for accurate relative measurement of soot volume fraction despite the morphological changes induced in the soot, variations in soot aggregate and primary particle size, and local gas temperature. Comparison of LII intensity profiles with soot volume fractions (f(v)) derived by light extinction validates LII for quantitative determination of f(v) upon calibration for laser fluences ranging from 0.09 to 0.73 J/cm(2).

  19. Laser-plasma interactions relevant to Inertial Confinement Fusion

    SciTech Connect

    Wharton, K. B.

    1998-11-01

    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

  20. 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.

  1. Laser Guiding and Wakefield Excitation in Plasma Channels.

    NASA Astrophysics Data System (ADS)

    Volfbeyn, Paul

    1998-11-01

    Laser driven plasma waves have been experimentally shown to sustain electric field gradients in excess of 10 GV/m. (For a review see E. Esarey et al., IEEE Trans. Plasma Sci. PS-24), 252 (1996). Laser diffraction limits the distance over which the high gradients are excited, thus placing a severe limit on the energy gain achievable in a laser plasma accelerating stage. To overcome the limitation on the acceleration distance due to laser beam diffraction, plasma channel guiding has been proposed in which, plasma channels with density minimum on axis can serve as optical guides. An overview is given of various techniques for plasma channel creation, relying on hydrodynamic shock expansion in laser heated plasmas (C.G. Durfee III and H. M. Milchberg, Phys. Rev. Lett., vol. 71, pp. 2409, (1993).) and capillary discharges. ( Y. Ehrlich, et al. Phys. Rev. Lett., vol.77, (no.20), p.4186-9 (1996).) Details of the dual laser pulse Ignitor - Heater scheme (P. Volfbeyn and W. P. Leemans, Phys. Rev. Lett., to be submitted.) will be presented, which allows creation of plasma channels in low atomic number gases, such as hydrogen. The current status of experiments on characterization of the plasma channel density profile and guiding of high intensity laser pulses will then be reviewed. These measurements are important since the density profile of plasma channels defines the modes of plasma oscillations and, therefore both the transverse (focusing) and longitudinal (accelerating) properties of the wake modes. Results of theoretical calculations of the wake modes for various plasma channel density profiles are presented, and their significance for the laser-plasma accelerator design is discussed.

  2. 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.

  3. 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.

  4. Novel concepts for laser-plasma-based acceleration of electrons using ultrahigh power laser pulses

    NASA Astrophysics Data System (ADS)

    Kim, Joon-Koo

    Analytical and numerical studies of plasma physics in ultra-intense plasma wave generation, electron injection, and wavebreaking are performed, which are relevant to the subject of plasma wake-field accelerators. A method for generating large-amplitude nonlinear plasma waves, which utilizes an optimized train of independently adjustable, intense laser pulses, is analyzed in one dimension both theoretically and numerically (using both Maxwell-fluid and particle-in-cell codes). Optimal pulse widths and interpulse spacings are computed for pulses with either square or finite-rise-time sine shapes. A resonant region of the plasma-wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. Resonant excitation is found to be superior for electron acceleration to either beatwave or single- pulse excitation because comparable plasma wave amplitudes may be generated at lower plasma densities, reducing electron-phase detuning, or at lower laser intensities, reducing laser-plasma instabilities. The idea of all-optical acceleration of electrons in the wakefield is also discussed. It is shown that the injection of background plasma electrons can be accomplished using the large ponderomotive force of an injection laser pulse in either collinear or transverse geometry with respect to the direction of pump propagation, thus removing the necessity of an expensive first-stage linac system for injection of electrons. Detailed nonlinear analysis of the trapping and acceleration of electrons inside the separatrix of the wakefield is formulated and compared with PIC (Particle- In-Cell) and fluid simulations. The three-dimensional wave-breaking of relativistic plasma waves driven by a ultrashort high-power lasers, is described within a framework of cold 2-D fluid theory. It is shown that the transverse nonlinearity of the plasma wave results in temporally increasing transverse plasma oscillation in the wake of the laser pulse, inevitably inducing wave

  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. 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.

  7. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Mechanism of high-energy electron production in a laser plasma

    NASA Astrophysics Data System (ADS)

    Belyaev, V. S.

    2004-01-01

    A mechanism of high-energy electron production in the interaction of high-intensity short laser pulses with a solid target is proposed and analysed. The theoretical dependences of fast-electron kinetic energy on the parameters of laser radiation and target material are given. The effect of ionisation of the target material is considered. The generation of ultrastrong magnetic fields in the laser plasma is shown to play the key part in the formation, transfer, and acceleration of electron beams. This results in the production of vortex electric fields accelerating electrons. The theoretical dependences yield well-proved limits for the electron energy and are in good agreement with the results of experiments performed on high-intensity laser setups, including the results obtained with participation of the author.

  8. 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.

  9. Spatiotemporal dynamics of Gaussian laser pulse in a multi ions plasma

    SciTech Connect

    Jafari Milani, M. R.

    2016-08-15

    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.

  10. Atoms in intense laser fields

    SciTech Connect

    Gavrila, M. )

    1992-01-01

    This book covers the following topics. Multiphoton ionization; photoionization with ultra-short laser pulses; Rydberg atoms in strong microwave fields; high-order harmonic generation in rare gases; mechanisms of short-wavelength generation; time-dependent studies of multiphoton processes; numerical experiments in strong and super-strong fields; resonance in multiphonton ionization nonpertubative treatment of multiphonton ionization within the floquet framework, atomic structure and decay in high frequency fields.

  11. PIC Simulations of direct laser accelerated electron from underdense plasmas using the OMEGA EP Laser

    NASA Astrophysics Data System (ADS)

    Hussein, Amina; Batson, Thomas; Krushelnick, Karl; Willingale, Louise; Arefiev, Alex; Wang, Tao; Nilson, Phil; Froula, Dustin; Haberberger, Dan; Davies, Andrew; Theobald, Wolfgang; Williams, Jackson; Chen, Hui

    2016-10-01

    The OMEGA EP laser system is used to study channeling phenomena and direct laser acceleration (DLA) through an underdense plasma. The interaction of a ps laser pulse with a subcritical density CH plasma plume results in the expulsion of electron along the laser axis, forming a positively charged channel. Electrons confined within this channel are subject to the action of the laser field as well as the transverse electric field of the channel, resulting the DLA of these electrons and the formation of a high energy electron beam. We have performed 2D simulations of ultra-intense laser radiation with underdense plasma using the PIC code EPOCH to investigate electron densities and self-consistently generated electric fields, as well as electron trajectories. This work was supported by the National Laser Users' Facility (NLUF), DOE.

  12. Quasilinear Theory of Laser-Plasma Interactions.

    NASA Astrophysics Data System (ADS)

    Neil, Alastair John

    The interaction of a high intensity laser beam with a plasma is generally susceptible to the filamentation instability due to nonuniformities in the laser profile. In ponderomotive filamentation high intensity spots in the beam expell plasma by ponderomotive force, lowering the local density, causing even more light to be focused into the already high intensity region. The result--the beam is broken up into a filamentary structure. Several optical smoothing techniques have been proposed to eliminate this problem. In the Random Phase Plates (RPS) approach, the beam is split into a very fine scale, time-stationary interference pattern. The irregularities in this pattern are small enough that thermal diffusion is then responsible for smoothing the illumination. In the Induced Spatial Incoherence (ISI) approach the beam is broken up into a larger scale but non-time-stationary interference pattern. In this dissertation we propose that the photons in an ISI beam resonantly interact with the sound waves in the wake of the beam. Such a resonant interaction induces diffusion in the velocity space of the photons. The diffusion will tend to spread the distribution of photons, thus if the diffusion time is much shorter than the e-folding time of the filamentation instability, the instability will be suppressed. Using a wave-kinetic description of laser-plasma interactions we have applied quasilinear theory to model the resonant interaction of the photons in an ISI beam with the beam's wake field. We have derived an analytic expression for the transverse diffusion coefficient. The quasilinear hypothesis was tested numerically and shown to yield an underestimate of the diffusion rate. By comparing the quasilinear diffusion rate, gamma_ {D}, with the maximum growth rate for the ponderomotive filamentation of a uniform beam, gamma_{f_{max}} , we have derived a worst case criterion for stability against ponderomotive filamentation: { gamma_{f_{max}} over gamma_ D} ~ .5 { ~ f^5/~ D

  13. 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.

  14. Wakefield evolution and electron acceleration in interaction of frequency-chirped laser pulse with inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Rezaei-Pandari, M.; Niknam, A. R.; Massudi, R.; Jahangiri, F.; Hassaninejad, H.; Khorashadizadeh, S. M.

    2017-02-01

    The nonlinear interaction of an ultra-short intense frequency-chirped laser pulse with an underdense plasma is studied. The effects of plasma inhomogeneity and laser parameters such as chirp, pulse duration, and intensity on plasma density and wakefield evolutions, and electron acceleration are examined. It is found that a properly chirped laser pulse could induce a stronger laser wakefield in an inhomogeneous plasma and result in higher electron acceleration energy. It is also shown that the wakefield amplitude is enhanced by increasing the slope of density in the inhomogeneous plasma.

  15. Laser electron acceleration in the prepulse produced plasma corona

    NASA Astrophysics Data System (ADS)

    Andreev, N. E.; Povarnitsyn, M. E.; Pugachev, L. P.; Levashov, P. R.

    2015-11-01

    The generation of hot electrons at grazing incidence of a subpicosecond relativistic-intense laser pulse onto the plane solid target is analyzed for the parameters of the petawatt class laser systems. We study the preplasma formation on the surface of solid Al target produced by the laser prepulses with different time structure. For modeling of the preplasma dynamics we use a wide-range two-temperature hydrodynamic model. As a result of simulations, the preplasma expansion under the action of the laser prepulse and the plasma density profiles for different contrast ratios of the nanosecond pedestal are found. These density profiles were used as the initial density distributions in 3-D PIC simulations of electron acceleration by the main P-polarized laser pulse. Results of modeling demonstrate the substantial increase of the characteristic energy and number of accelerated electrons for the grazing incidence of a subpicosecond intense laser pulse in comparison with the laser-target interaction at normal incidence.

  16. 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.

  17. Laser diagnostics for plasma turbulence

    NASA Astrophysics Data System (ADS)

    The purpose of this effort is to further develop the multiple-beam laser scattering diagnostic for tokamak plasmas. Present laser scattering diagnostics have very poor spatial resolution. Yet good spatial resolution is necessary if adequate comparison of theory and experiment is to occur. The proposed multiple beam scattering diagnostic promises a spatial resolution of approximately 10 cm at a fluctuation wave number of 5 cm(exp -1) when the angular envelope of the beams is 0.1 radians. A larger angular envelope would further improve the spatial resolution. This kind of spatial resolution is impossible with current laser scattering diagnostics. Enclosed are two items. These items constitute the major results of this study. Appendix A is a draft of a paper being prepared for submission to the journal on the review of scientific instruments. This paper consists of three sections. Section 1 compares the proposed diagnostic to conventional laser scattering diagnostics and argues for the need of increased spatial resolution. Section 2 presents a thorough rendering of the conceptual basis of the proposed multiple beam diagnostic. Section 3 presents an optical design suitable for use on the TEXT upgrade tokamak. Appendix B is a schematic of a proposed proof-of-principle bench-top experiment of the multiple beam scattering diagnostic. It is designed to demonstrate the concept thoroughly at a greatly reduced cost. An actual multiple beam CO2 laser scattering experiment on a controlled laboratory plasma would be a good follow-up before attempting construction of the diagnostic on a major tokamak.

  18. 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.

  19. A source to deliver mesoscopic particles for laser plasma studies.

    PubMed

    Gopal, R; Kumar, R; Anand, M; Kulkarni, A; Singh, D P; Krishnan, S R; Sharma, V; Krishnamurthy, M

    2017-02-01

    Intense ultrashort laser produced plasmas are a source for high brightness, short burst of X-rays, electrons, and high energy ions. Laser energy absorption and its disbursement strongly depend on the laser parameters and also on the initial size and shape of the target. The ability to change the shape, size, and material composition of the matter that absorbs light is of paramount importance not only from a fundamental physics point of view but also for potentially developing laser plasma sources tailored for specific applications. The idea of preparing mesoscopic particles of desired size/shape and suspending them in vacuum for laser plasma acceleration is a sparsely explored domain. In the following report we outline the development of a delivery mechanism of microparticles into an effusive jet in vacuum for laser plasma studies. We characterise the device in terms of particle density, particle size distribution, and duration of operation under conditions suitable for laser plasma studies. We also present the first results of x-ray emission from micro crystals of boric acid that extends to 100 keV even under relatively mild intensities of 10(16) W/cm(2).

  20. A source to deliver mesoscopic particles for laser plasma studies

    NASA Astrophysics Data System (ADS)

    Gopal, R.; Kumar, R.; Anand, M.; Kulkarni, A.; Singh, D. P.; Krishnan, S. R.; Sharma, V.; Krishnamurthy, M.

    2017-02-01

    Intense ultrashort laser produced plasmas are a source for high brightness, short burst of X-rays, electrons, and high energy ions. Laser energy absorption and its disbursement strongly depend on the laser parameters and also on the initial size and shape of the target. The ability to change the shape, size, and material composition of the matter that absorbs light is of paramount importance not only from a fundamental physics point of view but also for potentially developing laser plasma sources tailored for specific applications. The idea of preparing mesoscopic particles of desired size/shape and suspending them in vacuum for laser plasma acceleration is a sparsely explored domain. In the following report we outline the development of a delivery mechanism of microparticles into an effusive jet in vacuum for laser plasma studies. We characterise the device in terms of particle density, particle size distribution, and duration of operation under conditions suitable for laser plasma studies. We also present the first results of x-ray emission from micro crystals of boric acid that extends to 100 keV even under relatively mild intensities of 1016 W/cm2.

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

    PubMed

    Lehmann, G; Spatschek, K H

    2016-06-03

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

  2. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Spectral and temporal characteristics of a laser plasma

    NASA Astrophysics Data System (ADS)

    Lipchak, A. I.; Solomonov, V. I.; Tel'nov, V. A.; Osipov, V. V.

    1995-04-01

    An experimental investigation was made of the spectral and temporal characteristics of a laser plasma formed by the interaction of a CO2 laser pulse with a target in atmospheric air. The results obtained indicate that the main role in the process of filling the excited states in a laser plasma is played by a recombination cascade and that both atoms and molecules of the atmospheric gases are excited. The result also show that a laser plasma can be used in spectroscopic analysis of multicomponent samples. The solution of the thermophysical problem of heating of a target by laser radiation supports the existing ideas on the process of formation of a plasma near the target surface in air.

  3. 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.

  4. Terahertz acoustics in hot dense laser plasmas.

    PubMed

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

    2015-03-20

    We present a hitherto unobserved facet of hydrodynamics, namely the generation of an ultrahigh frequency acoustic disturbance in the terahertz frequency range, whose origins are purely hydrodynamic in nature. The disturbance is caused by differential flow velocities down a density gradient in a plasma created by a 30 fs, 800 nm high-intensity laser (∼5×10(16)  W/cm(2)). The picosecond scale observations enable us to capture these high frequency oscillations (1.9±0.6  THz) which are generated as a consequence of the rapid heating of the medium by the laser. Adoption of two complementary techniques, namely pump-probe reflectometry and pump-probe Doppler spectrometry provides unambiguous identification of this terahertz acoustic disturbance. Hydrodynamic simulations well reproduce the observations, offering insight into this process.

  5. 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.

  6. 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.

  7. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. 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.

  9. 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.

  10. Subpicosecond laser-produced plasma dynamics

    NASA Astrophysics Data System (ADS)

    Audebert, Patrick; Fallies, F.; Geindre, Jean-Paul; Delettrez, J.; Rousse, Antoine; Gauthier, Jean-Claude J.

    1994-02-01

    To simulate the interaction of high laser intensity with solid targets, we have used the 1D code FILM in which the collisional plasma absorption is calculated by solving the linear electromagnetic field for p and s polarization. For p-polarized light the collision frequency is adjusted so that the field in the critical region of the plasma never exceeds the maximum field allowed by the wave breaking limit. Energy transport by thermal conduction is described with the help of the delocalized heat flux theory. The ponderomotive force resulting from the huge filed is taken into account. The calculated temperatures and ion densities are used as an input to a time-dependent atomic physics code. Non-stationary ionization dynamics is demonstrated.

  11. Laser propagation and soliton generation in strongly magnetized plasmas

    SciTech Connect

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

    2016-03-15

    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.

  12. 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.

  13. Laser pulse evolution and electron acceleration in plasmas

    NASA Astrophysics Data System (ADS)

    Esarey, Eric

    2000-04-01

    Laser-driven plasma-based accelerators(For a review see, E. Esarey et al., IEEE Trans. Plasma Sci. 24, 252 (1996).) require the propagation of intense laser pulses over long distances in plasmas, the generation of large amplitude wakefields, and the injection and acceleration of electrons. This talk will discuss the nonlinear propagation of short laser pulses in plasmas, with or without channels. Non-paraxial effects will be analyzed and simulated, including finite pulse duration, finite group velocity, and dispersion(E. Esarey et al., Phys. Rev. Lett., submitted.). These effects on the evolution of the forward Raman and self-modulation instabilities, that lead the generation of wakefields, will be examined. Also discussed are methods for self-trapping and injecting electrons into the wakefield. Application to ongoing experiments at LBNL(W.P. Leemans et al., Phys. Plasma 5, 1615 (1998); in preparation.) will be discussed.

  14. Simulations of Relativistic Laser-Plasma Interactions

    SciTech Connect

    Nikolic, Lj.; Skoric, M.M.; Ishiguro, S.

    2004-12-01

    To investigate the growth of instabilities in an underdense plasma, a number of simulations was carried out using the one-dimensional electromagnetic (EM) relativistic particle-in-cell code. A new type of Raman-like scattering was identified in a subcritical regime, which is overdense for standard SRS. This novel instability is a parametric decay of the relativistic EM wave into a scattered light and an electron-acoustic ({omega} < {omega}p) electrostatic wave. In the linear stage, resonant matchings are well satisfied, while the scattered Stokes wave is always driven near critical. During nonlinear saturation, due to rapid growth and strong localization of the Stokes wave, narrow intense EM soliton-like structures with down-shifted laser light trapped inside are formed; eventually, to be irradiated through the plasma-vacuum interface in the form of intense low-frequency EM bursts. This behavior alters the distribution of laser energy between transmission, scattering losses and generation of energetic electrons.

  15. 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.

  16. Plasma formation in diode pumped alkali lasers sustained in Cs

    NASA Astrophysics Data System (ADS)

    Markosyan, Aram H.; Kushner, Mark J.

    2016-11-01

    In diode pumped alkali lasers (DPALs), lasing action occurs on the resonant lines of alkali atoms following pumping by broadband semiconductor lasers. The goal is to convert the efficient but usually poor optical quality of inexpensive diode lasers into the high optical quality of atomic vapor lasers. Resonant excitation of alkali vapor leads to plasma formation through the excitation transfer from the 2P states to upper lying states, which then are photoionized by the pump and intracavity radiation. A first principles global model was developed to investigate the operation of the He/Cs DPAL system and the consequences of plasma formation on the efficiency of the laser. Over a range of pump powers, cell temperatures, excitation frequency, and mole fraction of the collision mixing agent (N2 or C2H6), we found that sufficient plasma formation can occur that the Cs vapor is depleted. Although N2 is not a favored collisional mixing agent due to large rates of quenching of the 2P states, we found a range of pump parameters where laser oscillation may occur. The poor performance of N2 buffered systems may be explained in part by plasma formation. We found that during the operation of the DPAL system with N2 as the collisional mixing agent, plasma formation is in excess of 1014-1015 cm-3, which can degrade laser output intensity by both depletion of the neutral vapor and electron collisional mixing of the laser levels.

  17. Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

    NASA Astrophysics Data System (ADS)

    Salehi, M.; Mirzanejad, S.

    2017-05-01

    Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

  18. Laser-intensity requirements for generating enhanced kilovolt bremsstrahlung emission in intense laser-cluster interactions

    NASA Astrophysics Data System (ADS)

    Whitney, K. G.; Davis, J.; Petrova, Tz. B.; Petrov, G. M.

    2012-06-01

    The effects of ultrahigh-intensity laser radiation on dynamical processes such as electron scattering, bremsstrahlung emission, and pair production, have received growing theoretical interest as laser intensities in the laboratory continue to increase. Recently, for example, a calculation was published that predicted resonant increases of more than four orders of magnitude in bremsstrahlung emission in the presence of intense optical laser radiation [A. A. Lebed and S. P. Roshchupkin, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.81.033413 81, 033413 (2010)]. The analysis in that paper was limited to laser intensities of ≤1017 W/cm2, and it was applied only to bremsstrahlung emissions at the laser frequency. In the present paper, we extend this Lebed and Roshchupkin analysis in order to assess the possibility of achieving some enhancement in bremsstrahlung emissions at significantly higher harmonics of the optical laser photon energies (˜6 keV) and thereby to appraise whether or not enhanced bremsstrahlung emissions may have played a hidden role in producing the population inversions and kilovolt x-ray amplifications that have been seen experimentally [A. B. Borisov , J. Phys. B 40, F307 (2007)]. In those experiments, light from a KrF laser was focused onto a gas of xenon clusters to intensities ≳1019 W/cm2. A model of the expansion and ionization dynamics of a xenon cluster when heated by such laser intensities has been constructed [Tz. B. Petrova , High Energy Density Phys.1574-181810.1016/j.hedp.2012.03.007 8, 209 (2012)]. It is capable of replicating the x-ray gains seen experimentally, but only under the assumption that sufficiently high inner-shell photoionization rates are generated in the experiments. We apply this model to show that such photoionization rates are achievable, but only if there are enhancements of the Bethe-Heitler bremsstrahlung emission rate of three to four orders of magnitude. Our extended analysis of the Lebed and Roshchupkin work

  19. 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.

  20. Efficient energy absorption of intense ps-laser pulse into nanowire target

    SciTech Connect

    Habara, H.; Honda, S.; Katayama, M.; Tanaka, K. A.; Sakagami, H.; Nagai, K.

    2016-06-15

    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.

  1. 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.

  2. High-intensity laser-atom interactions

    NASA Astrophysics Data System (ADS)

    Joachain, Charles J.

    2014-11-01

    Following a historical introduction on the nature of light and its interaction with matter, a survey is given of the development of lasers capable of delivering short pulses of very intense radiation. The peak intensities of these laser pulses are so high that the corresponding laser fields can compete with, or even dominate, the Coulomb field in governing the dynamics of atomic systems. As a result, new phenomena, known as multiphoton processes, can occur. An outline is given of the basic properties found in the study of three important multiphoton processes. Firstly, the multiphoton ionization of atoms and the phenomenon of “above-threshold ionization”. Secondly, the emission by atoms of high-order harmonics of the frequency of the driving laser and their use to generate laser pulses having durations in the attosecond range. Thirdly, laser-assisted electron-atom collisions. A review is then given of the main non-perturbative methods which have been used to perform theoretical studies of multiphoton processes.

  3. 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.

  4. 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.

  5. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Low-threshold generation of harmonics and hard x radiation in a laser plasma. 1. Single-peak generation

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Derzhavin, S. I.; Kazakov, K. Kh

    1993-02-01

    A source of hard x radiation based on a laser plasma has been studied under conditions such that parametric instabilities are driven in the plasma at low intensities of the pump radiation (below 10 GW/cm2). A qualitative interpretation of the observed effects is offered.

  6. High intensity 30 femtosecond laser pulse interaction with thin foils

    SciTech Connect

    Giulietti, A.; Barbini, A.; Gizzi, L. A.; Chessa, P.; Giulietti, D.; Teychenne, D.

    1998-02-20

    An experimental investigation on the interaction of 30 femtosecond laser pulses with 0.1 and 1.0 {mu}m thick plastic foils has been performed at intensities from 5x10{sup 16} to 5x10{sup 18} W/cm{sup 2}. The interaction physics was found to be definitely different whether the nanosecond low intensity prepulses led to an early plasma formation or not. In the first case high reflectivity and very low transmittivity were observed, together with second and three-half harmonic generation. In absence of precursor plasma, with increasing intensity, reflectivity dropped to low values, while transmittivity increased up to an almost complete transparency. No harmonic generation was observed in this latter condition, while ultra-fast ionisation was inferred by the blue-shift of the transmitted pulse. Finally, intense hard X-ray emission was detected at the maximum laser intensity level. Current theories or numerical simulations cannot explain the observed transparency. A new model of magnetically induced optical transparency (MIOT) is briefly introduced.

  7. 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.

  8. 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.

  9. 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.

  10. Laser-Plasma Interactions in High-Energy Density Plasmas

    SciTech Connect

    Constantin, C G; Baldis, H A; Schneider, M B; Hinkel, D E; Langdon, A B; Seka, W; Bahr, R; Depierreaux, S

    2005-08-24

    Laser-plasma interactions (LPI) have been studied experimentally in high-temperature, high-energy density plasmas. The studies have been performed using the Omega laser at the Laboratory for Laser Energetics (LLE), Rochester, NY. Up to 10 TW of power was incident upon reduced-scale hohlraums, distributed in three laser beam cones. The hot hohlraums fill quickly with plasma. Late in the laser pulse, most of the laser energy is deposited at the laser entrance hole, where most of the LPI takes place. Due to the high electron temperature, the stimulated Raman scattering (SRS) spectrum extends well beyond {omega}{sub 0}/2, due to the Bohm-Gross shift. This high-temperature, high-energy density regime provides a unique opportunity to study LPI beyond inertial confinement fusion (ICF) conditions.

  11. Advanced targets, diagnostics and applications of laser-generated plasmas

    NASA Astrophysics Data System (ADS)

    Torrisi, L.

    2015-04-01

    High-intensity sub-nanosecond-pulsed lasers irradiating thin targets in vacuum permit generation of electrons and ion acceleration and high photon yield emission in non-equilibrium plasmas. At intensities higher than 1015 W/cm2 thin foils can be irradiated in the target-normal sheath acceleration regime driving ion acceleration in the forward direction above 1 MeV per charge state. The distributions of emitted ions in terms of energy, charge state and angular emission are controlled by laser parameters, irradiation conditions, target geometry and composition. Advanced targets can be employed to increase the laser absorption in thin foils and to enhance the energy and the yield of the ion acceleration process. Semiconductor detectors, Thomson parabola spectrometer and streak camera can be employed as online plasma diagnostics to monitor the plasma parameters, shot by shot. Some applications in the field of the multiple ion implantation, hadrontherapy and nuclear physics are reported.

  12. Coherent acceleration by laser pulse echelons in periodic plasma structures

    NASA Astrophysics Data System (ADS)

    Pukhov, A.; Kostyukov, I.; Tückmantel, T.; Luu-Thanh, Ph.; Mourou, G.

    2014-05-01

    We consider a possibilty to use an echelon of mutually coherent laser pulses generated by the emerging CAN (Coherent Amplification Network) technology for direct particle acceleration in periodic plasma structures. We discuss resonant and free streaming configurations. The resonant plasma structures can trap energy of longer laser pulses but are limited to moderate laser intensities of about 1014 W/cm2 and are very sensitive to the structure quality. The free streaming configurations can survive laser intensities above 1018 W/cm2 for several tens of femtoseconds so that sustained accelerating rates well above TeV/m are feasible. In our full electromagnetic relativistic particle-in-cell (PIC) simulations we show a test electron bunch gaining up to 200 GeV over a distance of 10.2 cm only.

  13. Intense EM filamentation in relativistic hot plasmas

    NASA Astrophysics Data System (ADS)

    Hu, Qiang-Lin; Chen, Zhong-Ping; Mahajan, Swadesh M.

    2017-03-01

    Through 2D particle-in-cell (PIC) simulations, we demonstrate that the nature of filamentation of a high intensity electromagnetic (EM) pulse propagating in an underdense plasma, is profoundly affected at relativistically high temperatures. The "relativistic" filaments are sharper, are dramatically extended (along the direction of propagation), and live much longer than their lower temperature counterparts. The thermally boosted electron inertia is invoked to understand this very interesting and powerful phenomenon.

  14. Interaction of intense ultrashort pulse lasers with clusters.

    NASA Astrophysics Data System (ADS)

    Petrov, George

    2007-11-01

    The last ten years have witnessed an explosion of activity involving the interaction of clusters with intense ultrashort pulse lasers. Atomic or molecular clusters are targets with unique properties, as they are halfway between solid and gases. The intense laser radiation creates hot dense plasma, which can provide a compact source of x-rays and energetic particles. The focus of this investigation is to understand the salient features of energy absorption and Coulomb explosion by clusters. The evolution of clusters is modeled with a relativistic time-dependent 3D Molecular Dynamics (MD) model [1]. The Coulomb interaction between particles is handled by a fast tree algorithm, which allows large number of particles to be used in simulations [2]. The time histories of all particles in a cluster are followed in time and space. The model accounts for ionization-ignition effects (enhancement of the laser field in the vicinity of ions) and a variety of elementary processes for free electrons and charged ions, such as optical field and collisional ionization, outer ionization and electron recapture. The MD model was applied to study small clusters (1-20 nm) irradiated by a high-intensity (10^16-10^20 W/cm^2) sub-picosecond laser pulse. We studied fundamental cluster features such as energy absorption, x-ray emission, particle distribution, average charge per atom, and cluster explosion as a function of initial cluster radius, laser peak intensity and wavelength. Simulations of novel applications, such as table-top nuclear fusion from exploding deuterium clusters [3] and high power synchrotron radiation for biological applications and imaging [4] have been performed. The application for nuclear fusion was motivated by the efficient absorption of laser energy (˜100%) and its high conversion efficiency into ion kinetic energy (˜50%), resulting in neutron yield of 10^6 neutrons/Joule laser energy. Contributors: J. Davis and A. L. Velikovich. [1] G. M. Petrov, et al Phys

  15. Laser beat wave resonant terahertz generation in a magnetized plasma channel

    SciTech Connect

    Bhasin, Lalita; Tripathi, V. K.; Kumar, Pawan

    2016-02-15

    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.

  16. 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.

  17. Fundamental Study of a Laser-Assisted Plasma Thruster

    NASA Astrophysics Data System (ADS)

    Horisawa, Hideyuki; Kawakami, Masatoshi; Lin, Wun-Wei; Igari, Akira; Kimura, Itsuro

    2003-05-01

    In this study we propose a novel laser-assisted plasma thruster, in which plasma is induced through a laser beam irradiation onto a target, or a laser-assisted process, and accelerated by electrical means instead of a direct acceleration only by using a laser beam. Inducing the short-duration conductive plasma between electrodes with certain voltage, the short-duration switching or a discharge is achieved, in the laser-assisted thruster. Also, reductions of energy losses to electrodes, electrodes erosion, and an improvement of specific impulse through the intense current caused by the short duration discharge can be expected. Here, a fundamental study of newly developed two-dimensional laser-assisted pulsed-plasma thruster (PPT) and coaxial laser assisted PPT is conducted. A DC power supply (10 ~ 600 V) was used for the power source, and an Nd:YAG laser (wave length: 1.06μm, maximum pulse energy: 1.4J/pulse, pulse width: 10 nsec) was utilized. With this system, the peak current of about 500A with its duration of 3 μsec (FWHM) was observed in a typical case.

  18. 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.

  19. Space-dependent characterization of laser-induced plasma plume during fiber laser welding

    NASA Astrophysics Data System (ADS)

    Xiao, Xianfeng; Song, Lijun; Xiao, Wenjia; Liu, Xingbo

    2016-12-01

    The role of a plasma plume in high power fiber laser welding is of considerable interest due to its influence on the energy transfer mechanism. In this study, the space-dependent plasma characteristics including spectrum intensity, plasma temperature and electron density were investigated using optical emission spectroscopy technique. The plasma temperature was calculated using the Boltzmann plot of atomic iron lines, whereas the electron density was determined from the Stark broadening of the Fe I line at 381.584 nm. Quantitative analysis of plasma characteristics with respect to the laser radiation was performed. The results show that the plasma radiation increases as the laser power increases during the partial penetration mode, and then decreases sharply after the initiation of full penetration. Both the plasma temperature and electron density increase with the increase of laser power until they reach steady state values after full penetration. Moreover, the hottest core of the plasma shifts toward the surface of the workpiece as the penetration depth increases, whereas the electron density is more evenly distributed above the surface of the workpiece. The results also indicate that the absorption and scattering of nanoparticles in the plasma plume is the main mechanism for laser power attenuation.

  20. Kr photoionized plasma induced by intense extreme ultraviolet pulses

    SciTech Connect

    Bartnik, A. Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.

    2016-04-15

    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.

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. Plasma heating effects during laser welding

    NASA Astrophysics Data System (ADS)

    Lewis, G. K.; Dixon, R. D.

    Laser welding is a relatively low heat input process used in joining precisely machined components with minimum distortion and heat affects to surrounding material. The CO2 (10.6 (MU)m) and Nd-YAG (1.06 (MU)m) lasers are the primary lasers used for welding in industry today. Average powers range up to 20 kW for CO2 and 400 W for Nd-YAG with pulse lengths of milliseconds to continuous wave. Control of the process depends on an understanding of the laser-plasma-material interaction and characterization of the laser beam being used. Inherent plasma formation above the material surface and subsequent modulation of the incident laser radiation directly affect the energy transfer to the target material. The temporal and spatial characteristics of the laser beam affect the available power density incident on the target, which is important in achieving repeatability in the process. Other factors such as surface texture, surface contaminants, surface chemistry, and welding environment affect plasma formation which determines the weld penetration. This work involves studies of the laser-plasma-material interaction process and particularly the effect of the plasma on the coupling of laser energy to a material during welding. A pulsed Nd-YAG laser was used with maximum average power of 400 W.

  6. Ultra-relativistic laser-plasma interaction and beyond

    NASA Astrophysics Data System (ADS)

    Ping, Yuan

    2011-10-01

    Relativistic laser-plasma interaction (LPI) is of broad interest in modern physics, with applications ranging from particle acceleration, laboratory astrophysics, to fast ignition for inertial confinement fusion. LPI is a highly dynamic process, especially in the relativistic regime. The plasma conditions evolve rapidly upon intense laser irradiation, which modifies laser absorption and energy partition. This talk summarizes recent advances in understanding laser absorption and dynamics of ultra-relativistic LPI. It is found that the total absorption of laser pulses by solid targets is strongly enhanced in the ultra-relativistic regime, reaching a surprisingly high level of ~90% at intensities above 1020 W / cm2 . Both presence of preplasma and hole boring contribute to the high absorption. The dynamics of hole boring is studied with a novel single-shot time-resolved diagnostic based on Frequency Resolved Optical Gating (FROG). Time history of the Doppler shift in the reflected light indicates that ponderomotive steepening occurs rapidly and majority of the laser pulse interacts with a sharpened density profile. Two-dimensional (2D) Particle-In-Cell (PIC) simulation results agree well with measurements for short pulses (<5 ps), however discrepancy showing up after 5ps for longer pulses, indicating 3D effect starts to play a role. In case of high-contrast laser pulses interacting with solid targets, the preplasma is minimal and the delicate competition between plasma creation and ponderomotive pushing results in a snake-like structure in the reflected spectrum. Finally, the talk will briefly cover potential schemes utilizing LPI as an amplification process of laser pulses for next-generation laser systems, which could enable ``vacuum boiling'' laser intensities for future experiments. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  7. Intense ion beam generation, plasma radiation source and plasma opening switch research

    NASA Astrophysics Data System (ADS)

    Hammer, D. A.; Coleman, M. D.; Qi, N.; Similon, P. L.; Sudan, R. N.

    1989-04-01

    This report describes research on intense ion beam diodes, plasma opening switches and dense z-pinch plasma radiators. Laser induced fluorescence spectroscopy has been used to map the electrostatic potential profile in a plasma-prefilled magnetically insulated ion diode. In a simple planar diode, the measured profile is inconsistent with the electrons being confined in a sheath near the cathode by the magnetic field. Rather, the profile implies the presence of electrons throughout the accelerating gap. A theoretical model of the penetration of current and magnetic field into a plasma, and of the current-driven effective collision frequency has been developed. The snowplow action of the rising magnetic field causes a steep rise in the plasma density at the leading edge. The subsequent multistreaming of the ions caused by ion reflection at the current layer could lead to ion heating through collective effects. The two-dimensional electron flow in the plasma cathode vacuum gap is also treated. Dense z-pinch plasma radiation source experiments have been initiated on the LION accelerator using gas puff and fine wire loads. The x-pinch was found to be a more effective way to generate soft x-rays than a single wire pinch or a gas puff implosion. Plasma opening switch experiments being initiated, and plasma anode ion diode development work being terminated are also briefly described.

  8. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Percolation upon expansion of nanosecond-pulse-produced laser plasma into a gas

    NASA Astrophysics Data System (ADS)

    Kask, Nikolai E.; Michurin, Sergei V.; Fedorov, Gennadii M.

    2005-01-01

    Spectral studies of a plasma expanding into the ambient gas upon ablation of various targets by nanosecond laser pulses of moderate intensities are performed. It is found that the dependences of the intensities of spectral lines on the pressure of the buffer gas and the target composition have a threshold character typical of percolation. It is ascertained that a three-dimensional percolation occurs in plasma, and its threshold is determined by the atomic density of the metal component contained in the target. It is shown that percolation clusters, existing at temperatures higher than the boiling temperature of the target material, affect the plasma absorption ability, temperature, and spectral continuum of plasma emission.

  9. Laser intensity effects in noncommutative QED

    SciTech Connect

    Heinzl, Thomas; Ilderton, Anton; Marklund, Mattias

    2010-03-01

    We discuss a twofold extension of QED assuming the presence of strong external fields provided by an ultraintense laser and noncommutativity of spacetime. While noncommutative effects leave the electron's intensity induced mass shift unchanged, photons change significantly in character: they acquire a quasimomentum that is no longer lightlike. We study the consequences of this combined noncommutative strong-field effect for the basic lepton-photon interactions.

  10. Vacuum ultraviolet argon excimer laser at 126 nm excited by a high intensity laser

    NASA Astrophysics Data System (ADS)

    Kaku, Masanori; Harano, Shinya; Katto, Masahito; Kubodera, Shoichi

    2010-09-01

    We have observed the optical amplification of the Ar2* excimer at 126 nm pumped by optical-field-induced ionization (OFI) caused by an infrared high-intensity laser. We have evaluated similar small signal gain coefficients of approximately 1.0 cm-1 in two different experiments, where OFI Ar plasmas as gain media were produced in free space filled with Ar and inside an Ar-filled hollow fiber. This indicates that the function of a hollow fiber was to guide the infrared excitation laser and VUV Ar2* emissions, and not to regulate the OFI plasma. Despite the gain coefficient value at 126 nm, the laser oscillation has not been observed. This was limited by the optical quality of available state-of-the-art vacuum ultraviolet optics.

  11. High-energy laser plasma diagnostic system

    NASA Astrophysics Data System (ADS)

    Zhao, Mingjun M.; Aye, Tin M.; Fruehauf, Norbert; Savant, Gajendra D.; Erwin, Daniel A.; Smoot, Brayton E.; Loose, Richard W.

    2000-07-01

    This paper describes the development of a non-contact diagnosis system for analyzing the plasma density profile, temperature profile, and ionic species of a high energy laser-generated plasma. The system was developed by Physical Optics Corporation in cooperation with the U.S. Army Space and Missile Defense Command, High Energy Laser Systems Test Facility at White Sands Missile Range, New Mexico. The non- contact diagnostic system consists of three subsystems: an optical fiber-based interferometer, a plasma spectrometer, and a genetic algorithm-based fringe-image processor. In the interferometer subsystem, the transmitter and the receiver are each packaged as a compact module. A narrow notch filter rejects strong plasma light, passing only the laser probing beam, which carries the plasma density information. The plasma spectrum signal is collected by an optical fiber head, which is connected to a compact spectrometer. Real- time genetic algorithm-based data processing/display permits instantaneous analysis of the plasma characteristics. The research effort included design and fabrication of a vacuum chamber, and high-energy laser plasma generation. Compactness, real-time operation, and ease of use make the laser plasma diagnosis system well suited for dual use applications such as diagnosis of electric arc and other industrial plasmas.

  12. [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.

  13. 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.

  14. Raman laser amplification in preformed and ionizing plasmas

    SciTech Connect

    Clark, D S; Fisch, N J

    2004-09-01

    The recently proposed backward Raman laser amplification scheme utilizes the stimulated Raman backscattering in plasma of a long pumping laser pulse to amplify a short, frequency downshifted seed pulse. The output intensity for this scheme is limited by the development of forward Raman scattering (FRS) or modulational instabilities of the highly amplified seed. Theoretically, focused output intensities as high as 1025 W/cm{sup 2} and pulse lengths of less than 100 fs could be accessible by this technique for 1 {micro}m lasers--an improvement of 10{sup 4}-10{sup 5} in focused intensity over current techniques. Simulations with the particle-in-cell (PIC) code Zohar are presented which investigate the effects of FRS and modulational instabilities and of Langmuir wave breaking on the output intensity for Raman amplification. Using the intense seed pulse to photoionize the plasma simultaneous with its amplification (and hence avoid plasmas-based instabilities of the pump) is also investigated by PIC simulations. It is shown that both approaches can access focused intensities in the 1025 W/cm{sup 2} range.

  15. 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

  16. Plasma undulator excited by high-order mode lasers

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Rykovanov, Sergey

    2016-10-01

    A laser-created plasma undulator together with a laser-plasma accelerator makes it possible to construct an economical and extremely compact XFEL. However, the spectrum spread of the radiation from the current plasma undulators is too large for XFELs, because of the different values of strength parameters. The phase slippage between the electrons and the wakefield also limits the number of the electron oscillation cycles, thus reduces the performance of XFEL. Here we proposed a phase-locked plasma undulator created by high-order mode lasers. The modulating field is uniform along the transverse direction by choosing appropriate laser intensities of the modes, which enables all the electrons oscillate with the same strength parameter. The plasma density is tapered to lock the phase between the electrons and the wakefield, which signally increases the oscillation cycles. As a result, X-ray radiation with high brightness and narrow bandwidth is generated by injecting a high-energy electron beam into the novel plasma undulator. The beam loading limit indicates that the current of the electron beam could be hundreds of Ampere. These properties imply that such a plasma undulator may have great potential in compact XFELs. This work was supported by the Helmholtz Association (Young Investigator's Group No. VH-NG-1037).

  17. 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.

  18. Third harmonic generation with ultra-high intensity laser pulses

    SciTech Connect

    Rax, J.M.; Fisch, N.J.

    1992-04-01

    When an intense, plane-polarized, laser pulse interacts with a plasma, the relativistic nonlinearities induce a third harmonic polarization. A phase-locked growth of a third harmonic wave can take place, but the differences between the nonlinear dispersion of the pump and driven waves leads to a rapid unlocking, resulting in a saturation. What becomes third harmonic amplitude oscillations are identified here, and the nonlinear phase velocity and the renormalized electron mass due to plasmon screening are calculated. A simple phase-matching scheme, based on a resonant density modulation, is then proposed and analyzed.

  19. Third harmonic generation with ultra-high intensity laser pulses

    SciTech Connect

    Rax, J.M.; Fisch, N.J.

    1992-04-01

    When an intense, plane-polarized, laser pulse interacts with a plasma, the relativistic nonlinearities induce a third harmonic polarization. A phase-locked growth of a third harmonic wave can take place, but the differences between the nonlinear dispersion of the pump and driven waves leads to a rapid unlocking, resulting in a saturation. What becomes third harmonic amplitude oscillations are identified here, and the nonlinear phase velocity and the renormalized electron mass due to plasmon screening are calculated. A simple phase-matching scheme, based on a resonant density modulation, is then proposed and analyzed.

  20. 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.

  1. 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.

  2. 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.

  3. Plasma dynamics near critical density inferred from direct measurements of laser hole boring.

    PubMed

    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, v_{HB}, of the density cavity pushed forward by a train of CO_{2} 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 v_{HB} 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 v_{HB}, 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.

  4. 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.

  5. Simulation of Laser Interaction with Ablative Plasma and ydrodynamic of Laser Supported Plasma(LSP)

    NASA Astrophysics Data System (ADS)

    Huifeng, Tong; Zhiping, Tang

    2011-06-01

    A general Godunov finite difference schemes-WENO(Weighted Essentially Non-Oscillatory) Schemes which have fifth-order accuracy was used to make a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target. The models of the calculation of ionization degree of plasma and the interaction between laser beam and plasma and the simplified eos(equation of state) of plasma were considered in the simulation. The plasma field parameters during and after laser duration variation with time are also obtained. The simulation results show that the laser beam power was strong absorbed by plasma of target surface, and the velocity of LSD(Laser Supported Detonation) wave is half of ideal LSD value which derived from C-J detonation theory.

  6. 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.

  7. High energy density micro plasma bunch from multiple laser interaction with thin target

    SciTech Connect

    Xu, Han; Yu, Wei; Luan, S. X.; Xu, Z. Z.; Yu, M. Y.; Cai, H. B.; Zhou, C. T.; Yang, X. H.; Yin, Y.; Zhuo, H. B.; Wang, J. W.; Murakami, M.

    2014-01-13

    Three-dimensional particle-in-cell simulation is used to investigate radiation-pressure driven acceleration and compression of small solid-density plasma by intense laser pulses. It is found that multiple impacts by presently available short-pulse lasers on a small hemispheric shell target can create a long-living tiny quasineutral monoenergetic plasma bunch of very high energy density.

  8. Ponderomotive perturbations of low density low-temperature plasma under laser Thomson scattering diagnostics

    NASA Astrophysics Data System (ADS)

    Shneider, Mikhail N.

    2017-10-01

    The ponderomotive perturbation in the interaction region of laser radiation with a low density and low-temperature plasma is considered. Estimates of the perturbation magnitude are determined from the plasma parameters, geometry, intensity, and wavelength of laser radiation. It is shown that ponderomotive perturbations can lead to large errors in the electron density when measured using Thomson scattering.

  9. Simultaneous streak and frame interferometry for electron density measurements of laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Quevedo, H. J.; McCormick, M.; Wisher, M.; Bengtson, Roger D.; Ditmire, T.

    2016-01-01

    A system of two collinear probe beams with different wavelengths and pulse durations was used to capture simultaneously snapshot interferograms and streaked interferograms of laser produced plasmas. The snapshots measured the two dimensional, path-integrated, electron density on a charge-coupled device while the radial temporal evolution of a one dimensional plasma slice was recorded by a streak camera. This dual-probe combination allowed us to select plasmas that were uniform and axisymmetric along the laser direction suitable for retrieving the continuous evolution of the radial electron density of homogeneous plasmas. Demonstration of this double probe system was done by measuring rapidly evolving plasmas on time scales less than 1 ns produced by the interaction of femtosecond, high intensity, laser pulses with argon gas clusters. Experiments aimed at studying homogeneous plasmas from high intensity laser-gas or laser-cluster interaction could benefit from the use of this probing scheme.

  10. Simultaneous streak and frame interferometry for electron density measurements of laser produced plasmas

    SciTech Connect

    Quevedo, H. J. McCormick, M.; Wisher, M.; Bengtson, Roger D.; Ditmire, T.

    2016-01-15

    A system of two collinear probe beams with different wavelengths and pulse durations was used to capture simultaneously snapshot interferograms and streaked interferograms of laser produced plasmas. The snapshots measured the two dimensional, path-integrated, electron density on a charge-coupled device while the radial temporal evolution of a one dimensional plasma slice was recorded by a streak camera. This dual-probe combination allowed us to select plasmas that were uniform and axisymmetric along the laser direction suitable for retrieving the continuous evolution of the radial electron density of homogeneous plasmas. Demonstration of this double probe system was done by measuring rapidly evolving plasmas on time scales less than 1 ns produced by the interaction of femtosecond, high intensity, laser pulses with argon gas clusters. Experiments aimed at studying homogeneous plasmas from high intensity laser-gas or laser-cluster interaction could benefit from the use of this probing scheme.

  11. Influence of laser energy on the electron temperature of a laser-induced Mg plasma

    NASA Astrophysics Data System (ADS)

    Asamoah, Emmanuel; Hongbing, Yao

    2017-01-01

    The magnesium plasma induced by a 1064-nm Q-switched Nd:YAG laser in atmospheric air was investigated. The evolution of the plasma was studied by acquiring spectral images at different laser energies and delay times. We observed that the intensities of the spectral lines decrease with larger delay times. The electron temperature was determined using the Boltzmann plot method. At a delay time of 100 ns and laser energy of 350 mJ, the electron temperature attained their highest value at 10164 K and then decreases slowly up to 8833.6 K at 500 ns. We found that the electron temperature of the magnesium plasma increases rapidly with increasing laser energy.

  12. Characterization of a laser plasma produced from a graphite target

    NASA Astrophysics Data System (ADS)

    Ruiz, M.; Guzmán, F.; Favre, M.; Hevia, S.; Correa, N.; Bhuyan, H.; Wynham, E. S.; Chuaqui, H.

    2014-05-01

    In order to improve the understanding of pulsed laser deposition (PLD) of diamondlike carbon (DLC) films, we have initiated a detailed study of the plasma dynamics of laser produced carbon plasmas. The carbon plasma is produced by focusing a Nd:YAG laser pulse, 380 mJ, 4 ns at 1.06 μm, onto a graphite target, at a background pressure of 0.3 mTorr. Time resolved optical emission spectroscopic (OES) observations of the carbon plasma plume are obtained, with time and space resolution, using a SpectraPro 275 spectrograph, with a 15 ns MCP gated OMA. Line emission from CII to CIV carbon ions is identified at different stages of the plasma evolution. Line intensity ratios of successive ionization stages, CIII/CIV, was used to estimate the electron temperature throughout the Saha-Boltzmann equation, under the assumption of local thermodynamic equilibrium (LTE), and Stark broadening of CII lines was used to obtain measurements of the electron density. Characteristic plasma parameters, short after plasma formation, are 3.0 eV and 2-1017 cm-3which after 60 ns of plasma expansion decay to 2.7 eV and 5·10 cm-3, respectively.

  13. Containing intense laser light in circular cavity with magnetic trap door

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    It is shown by particle-in-cell simulation that intense circularly polarized (CP) laser light can be contained in the cavity of a solid-density circular Al-plasma shell for hundreds of light-wave periods before it is dissipated by laser-plasma interaction. A right-hand CP laser pulse can propagate with almost no reflection and attenuation into the cavity through a highly magnetized overdense H-plasma slab filling the entrance hole. The entrapped laser light is then multiply reflected at the inner surfaces of the slab and shell plasmas, slowly losing energy to the latter. Compared to that of the incident laser, the frequency is only slightly broadened and the wave vector slightly modified by the appearance of weak nearly isotropic and homogeneous fluctuations.

  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. Investigation of early plasma evolution induced by ultrashort laser pulses.

    PubMed

    Hu, Wenqian; Shin, Yung C; King, Galen B

    2012-07-02

    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 environment(1-11). Early plasma evolution has been captured through pump-probe shadowgraphy(1-3) and interferometry(1,4-7). 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 10(14) W/cm(2). Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions(12). 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.

  16. Picosecond X-ray Laser Interferometry for Probing Dense Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Dunn, James; Smith, Raymond F.; Filevich, Jorge; Rocca, Jorge J.; Moon, Stephen J.; Nilsen, Joseph; Shlyaptsev, Vyacheslav N.; Keenan, Roisin; Ng, Andrew; Hunter, James R.; Marconi, Mario. C.

    2003-10-01

    The development of compact, x-ray laser (XRL) sources has great potential to advance interferometric techniques to shorter wavelengths for probing dense, rapidly changing, laser-heated plasmas. The use of soft x-rays has many advantages over optical or UV wavelength probes including greatly reduced refraction and lower absorption within the plasma. Another advantage when coupled with a short probe pulse duration, is the achievement of sub-micron spatial resolution close to the target surface to make precise measurements in the highest density region with negligible plasma motion blurring. This makes x-ray laser interferometry a unique tool for studying high density plasmas giving new information about the underlying physical processes and allowing the study of new plasma regimes. We describe precision interferometric characterization experiments using the picosecond, 14.7 nm x-ray laser source generated on the Compact Multipulse Terawatt (COMET) laser facilty at LLNL together with the Mach-Zehnder type Diffraction Grating Interferometer (DGI) designed and built at Colorado State University. A review of the results from dense, mm-scale line focus plasma experiments will be described with detailed comparisons to 1-, 1.5- and 2-D hydrodynamic simulations. Ongoing experiments on smaller spot focus high intensity plasmas will be discussed.

  17. 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.

  18. 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.

  19. 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.

  20. Relativistic Electron Accleration by a Laser of Intensity in Excess of 1020 W cm-2

    NASA Astrophysics Data System (ADS)

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

    Relativistic electrons with energies in excess of 300 MeV have been observed resulting from the interaction of a 0.3 PW laser beam focused to intensities of around 3 × 1020 W cm-2 interacting with an underdense plasma. Two dimensional particle in cell simulation of the interaction show that an interaction directly between preheated electrons and the intense laser field is responsible for the maximum acceleration.

  1. Laser beam propagation through inertial confinement fusion hohlraum plasmas

    SciTech Connect

    Froula, D. H.; Divol, L.; Meezan, N. B.; Dixit, S.; Neumayer, P.; Moody, J. D.; Pollock, B. B.; Ross, J. S.; Suter, L.; Glenzer, S. H.

    2007-05-15

    A study of the laser-plasma interaction processes have been performed in plasmas that are created to emulate the plasma conditions in indirect drive inertial confinement fusion targets. The plasma emulator is produced in a gas-filled hohlraum; a blue 351-nm laser beam propagates along the axis of the hohlraum interacting with a high-temperature (T{sub e}=3.5 keV), dense (n{sub e}=5x10{sup 20} cm{sup -3}), long-scale length (L{approx}2 mm) plasma. Experiments at these conditions have demonstrated that the interaction beam produces less than 1% total backscatter resulting in transmission greater than 90% for laser intensities less than I<2x10{sup 15} W cm{sup -2}. The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows a stimulated Brillouin scattering threshold (R=10%) for a linear gain of 15; these high temperature, low density experiments produce plasma conditions comparable to those along the outer beams in ignition hohlraum designs. By increasing the gas fill density (n{sub e}=10{sup 21} cm{sup -3}) in these targets, the inner beam ignition hohlraum conditions are accessed. In this case, stimulated Raman scattering dominates the backscattering processes and we show that scattering is small for gains less than 20 which can be achieved through proper choice of the laser beam intensity.

  2. Laser and intense pulsed light management of couperose and rosacea.

    PubMed

    Dahan, S

    2011-11-01

    Management of couperosis and rosacea has been totally renewed by laser and vascular laser techniques, with efficacy targeted on the telangiectases and to a lesser extent on the erythrosis. Laser management of hypertrophic rosacea or rhinophyma depends on surgical treatment with decortication, continuous CO(2) ablative laser or Erbium, fractionated at high power, then vascular laser treatment for the telangiectases: lasers with pulsed dye, KTP, or pulsed lights for red laser telangiectases and long pulse Nd-Yag laser for blue telangiectases. For papulopustular rosacea, vascular laser treatment (pulsed dye and KTP) and intense pulsed light will be begun once the inflammation has been treated. The major indication for vascular lasers and intense pulsed light is found in erythematotelangiectatic rosacea, with high efficacy for the telangiectases. Diffuse erythrosis is difficult to treat, requiring a high number of laser and/or intense pulsed light sessions. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  3. [Laser and intense pulsed light management of couperose and rosacea].

    PubMed

    Dahan, S

    2011-09-01

    Management of couperosis and rosacea has been totally renewed by laser and vascular laser techniques, with efficacy targeted on the telangiectases and to a lesser extent on the erythrosis. Laser management of hypertrophic rosacea or rhinophyma depends on surgical treatment with decortication, continuous CO(2) ablative laser or Erbium, fractionated at high power, then vascular laser treatment for the telangiectases: lasers with pulsed dye, KTP, or pulsed lights for red laser telangiectases and long pulse Nd-Yag laser for blue telangiectases. For papulopustular rosacea, vascular laser treatment (pulsed dye and KTP) and intense pulsed light will be begun once the inflammation has been treated. The major indication for vascular lasers and intense pulsed light is found in erythematotelangiectatic rosacea, with high efficacy for the telangiectases. Diffuse erythrosis is difficult to treat, requiring a high number of laser and/or intense pulsed light sessions. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  4. 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.

  5. Laser-electron Compton interaction in plasma channels

    SciTech Connect

    Pogorelsky, I.V.; Ben-Zvi, I.; Hirose, T.

    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, the authors 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. They demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider.

  6. 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.

  7. Two-dimensional fluorescence spectroscopy of laser-produced plasmas

    SciTech Connect

    Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark 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 solid aluminum targets 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, 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 continuous-wave laser at one transition. Time-delayed and gated detection of the emission spectrum is used to isolate the resonantly-excited fluorescence emission from the thermally-excited emission from the plasma. In addition, the tunable continuous-wave laser measures the absorption spectrum of the Al transition with ultra-high resolution after the plasma has cooled, resulting in narrower spectral linewidths than observed in emission spectra. Our results highlight that fluorescence spectroscopy employing continuous-wave laser re-excitation after pulsed laser ablation combines benefits of both traditional emission and absorption spectroscopic methods.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Toward Extrapolating Two-Dimensional High-intensity Laser-Plasma Ion Acceleration Particle-in-Cell Simulations to Three Dimensions

    NASA Astrophysics Data System (ADS)

    Stark, D. J.; Yin, L.; Albright, B. J.; Guo, F.

    2016-10-01

    A PIC study of laser-ion acceleration via relativistic induced transparency points to how 2D-S (laser polarization in the simulation plane) and -P (out-of-plane) simulations may capture different physics characterizing these systems, visible in their entirety in (often cost-prohibitive) 3D simulations. The electron momentum anisotropy induced in the target by the laser pulse is dramatically different in the two 2D cases, manifesting in differences in polarization shift, electric field strength, density threshold for onset of relativistic induced transparency, and target expansion timescales. In particular, a trajectory analysis of individual electrons and ions may allow one to delineate the role of the fields and modes responsible for ion acceleration. With this information, we consider how 2D simulations might be used to develop, in some respects, a fully 3D understanding of the system. Work performed under the auspices of the U.S. DOE by the LANS, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396. Funding provided by the Los Alamos National Laboratory Directed Research and Development Program.

  14. 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.

  15. Single laser based pump-probe technique to study plasma shielding during nanosecond laser ablation of copper thin films

    NASA Astrophysics Data System (ADS)

    Nammi, Srinagalakshmi; Vasa, Nilesh J.; Gurusamy, Balaganesan; Mathur, Anil C.

    2017-09-01

    A plasma shielding phenomenon and its influence on micromachining is studied experimentally and theoretically for laser wavelengths of 355 nm, 532 nm and 1064 nm. A time resolved pump-probe technique is proposed and demonstrated by splitting a single nanosecond Nd3+:YAG laser into an ablation laser (pump laser) and a probe laser to understand the influence of plasma shielding on laser ablation of copper (Cu) clad on polyimide thin films. The proposed nanosecond pump-probe technique allows simultaneous measurement of the absorption characteristics of plasma produced during Cu film ablation by the pump laser. Experimental measurements of the probe intensity distinctly show that the absorption by the ablated plume increases with increase in the pump intensity, as a result of plasma shielding. Theoretical estimation of the intensity of the transmitted pump beam based on the thermo-temporal modeling is in qualitative agreement with the pump-probe based experimental measurements. The theoretical estimate of the depth attained for a single pulse with high pump intensity value on a Cu thin film is limited by the plasma shielding of the incident laser beam, similar to that observed experimentally. Further, the depth of micro-channels produced shows a similar trend for all three wavelengths, however, the channel depth achieved is lesser at the wavelength of 1064 nm.

  16. 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.

  17. 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

    2014-08-22

    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.

  18. Plasma generated during underwater pulsed laser processing

    NASA Astrophysics Data System (ADS)

    Hoffman, Jacek; Chrzanowska, Justyna; Moscicki, Tomasz; Radziejewska, Joanna; Stobinski, Leszek; Szymanski, Zygmunt

    2017-09-01

    The plasma induced during underwater pulsed laser ablation of graphite is studied both experimentally and theoretically. The results of the experiment show that the maximum plasma temperature of 25000 K is reached 20 ns from the beginning of the laser pulse and decreases to 6500 K after 1000 ns. The observed OH absorption band shows that the plasma plume is surrounded by the thin layer of dissociated water vapour at a temperature around 5500 K. The hydrodynamic model applied shows similar maximum plasma temperature at delay times between 14 ns and 30 ns. The calculations show also that already at 14th ns, the plasma electron density reaches 0.97·1027 m-3, which is the critical density for 1064 nm radiation. At the same time the plasma pressure is 2 GPa, which is consisted with earlier measurements of the peak pressure exerted on a target in similar conditions.

  19. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Effect of the electronic structure of target atoms on the emission continuum of laser plasma

    NASA Astrophysics Data System (ADS)

    Kask, Nikolai E.; Michurin, Sergei V.; Fedorov, Gennadii M.

    2004-06-01

    The low-temperature laser plasma at the surface of metal targets is experimentally investigated. Continuous spectra emitted from a laser plume are found to be similar for targets consisting of the elements of the same subgroup of the Mendeleev periodic table. The similarity manifests itself both in the dependence of the emission intensity on the external pressure and in the structure of absorption bands related to a fine-dispersed phase existing in the peripheral regions of the plume.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Laser plasma interactions in fused silica cavities

    SciTech Connect

    Zeng, Xianzhong; Mao, Xianglei; Mao, Samuel S.; Yoo, Jong H.; Greif, Ralph; Russo, Richard E.

    2003-06-24

    The effect of laser energy on formation of a plasma inside a cavity was investigated. The temperature and electron number density of laser-induced plasmas in a fused silica cavity were determined using spectroscopic methods, and compared with laser ablation on a flat surface. Plasma temperature and electron number density during laser ablation in a cavity with aspect ratio of 4 increased faster with irradiance after the laser irradiance reached a threshold of 5 GW/cm{sup 2}. The threshold irradiance of particulate ejection was lower for laser ablation in a cavity compared with on a flat surface; the greater the cavity aspect ratio, the lower the threshold irradiance. The ionization of silicon becomes saturated and the crater depths were increased approximately by an order of magnitude after the irradiance reached the threshold. Phase explosion was discussed to explain the large change of both plasma characteristics and mass removal when irradiance increased beyond a threshold value. Self-focusing of the laser beam was discussed to be responsible for the decrease of the threshold in cavities.

  9. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Efficient heating of near-surface plasmas with femtosecond laser pulses stimulated by nanoscale inhomogeneities

    NASA Astrophysics Data System (ADS)

    Mikhailova, Yu M.; Platonenko, Viktor T.; Savel'ev, Andrei B.

    2005-01-01

    The interaction of intense (1016 - 1018 W cm-2) ultrashort (50-200 fs) laser pulses with the dense plasmas produced at the surfaces of the porous target is numerically simulated by the particle-in-cell technique. Nanostructure-enhanced absorption of femtosecond pulses in high-porous (P>4) targets is demonstrated. We show that the presence of plasma inhomogeneities essentially alters the heating of plasma electrons and ions; in particular, it stimulates the significant increase in the mean energy and number of hot electrons. The numerical investigation of the dynamics of plasma electrons made it possible to reveal the physical mechanisms behind their heating in a porous medium.

  10. 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.

  11. Laser amplifier based on Raman amplification in plasma (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Vieux, Gregory; Cipiccia, Silvia; Lemos, Nuno R. C.; Ciocarlan, Cristian; Grant, Peter A.; Grant, David W.; Ersfeld, Bernhard; Hur, MinSup; Lepipas, Panagiotis; Manahan, Grace; Reboredo Gil, David; Subiel, Anna; Welsh, Gregor H.; Wiggins, S. Mark; Yoffe, Samuel R.; Farmer, John P.; Aniculaesei, Constantin; Brunetti, Enrico; Yang, Xue; Heathcote, Robert; Nersisyan, Gagik; Lewis, Ciaran L. S.; Pukhov, Alexander; Dias, João. Mendanha; Jaroszynski, Dino A.

    2017-05-01

    The increasing demand for high laser powers is placing huge demands on current laser technology. This is now reaching a limit, and to realise the existing new areas of research promised at high intensities, new cost-effective and technically feasible ways of scaling up the laser power will be required. Plasma-based laser amplifiers may represent the required breakthrough to reach powers of tens of petawatt to exawatt, because of the fundamental advantage that amplification and compression can be realised simultaneously in a plasma medium, which is also robust and resistant to damage, unlike conventional amplifying media. Raman amplification is a promising method, where a long pump pulse transfers energy to a lower frequency, short duration counter-propagating seed pulse through resonant excitation of a plasma wave that creates a transient plasma echelon that backscatters the pump into the probe. Here we present the results of an experimental campaign conducted at the Central Laser Facility. Pump pulses with energies up to 100 J have been used to amplify sub-nanojoule seed pulses to near-joule level. An unprecedented gain of eight orders of magnitude, with a gain coefficient of 180 cm-1 has been measured, which exceeds high-power solid-state amplifying media by orders of magnitude. High gain leads to strong competing amplification from noise, which reaches similar levels to the amplified seed. The observation of 640 Jsr-1 directly backscattered from noise, implies potential overall efficiencies greater than 10%.

  12. Intense femtosecond laser driven collimated fast electron transport in a dielectric medium-role of intensity contrast.

    PubMed

    Dey, Indranuj; Adak, Amitava; Singh, Prashant Kumar; Shaikh, Moniruzzaman; Chatterjee, Gourab; Sarkar, Deep; Lad, Amit D; Kumar, G Ravindra

    2016-12-12

    Ultra-high intensity (> 1018 W/cm2), femtosecond (~30 fs) laser induced fast electron transport in a transparent dielectric has been studied for two laser systems having three orders of magnitude different peak to pedestal intensity contrast, using ultrafast time-resolved shadowgraphy. Use of a 400 nm femtosecond pulse as a probe enables the exclusive visualization of the dynamics of highest density electrons (> 7 × 1021 cm-3) observed so far. High picosecond contrast (~109) results in greater coupling of peak laser energy to the plasma electrons, enabling long (~1 mm), collimated (divergence angle ~2°) transport of fast electrons inside the dielectric medium at relativistic speeds (~0.66c). In comparison, the laser system with a contrast of ~106 has a large pre-plasma, limiting the coupling of laser energy to the solid and yielding limited fast electron injection into the dielectric. In the lower contrast case, bulk of the electrons expand as a cloud inside the medium with an order of magnitude lower speed than that of the fast electrons obtained with the high contrast laser. The expansion speed of the plasma towards vacuum is similar for the two contrasts.

  13. Staging of laser-plasma accelerators

    DOE PAGES

    Steinke, S.; van Tilborg, J.; Benedetti, C.; ...

    2016-05-02

    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 thanmore » the transverse wake size at the entrance of the second stage. Furthermore, this permitted electron beam trapping, verified by a 100 MeV energy gain.« less

  14. Staging of laser-plasma accelerators

    SciTech Connect

    Steinke, S. Tilborg, J. van; Benedetti, C.; Geddes, C. G. R.; Gonsalves, A. J.; Nakamura, K.; Schroeder, C. B.; Esarey, E.; Daniels, J.; Swanson, K. K.; Shaw, B. H.; Leemans, W. P.

    2016-05-15

    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.

  15. 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.

  16. 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.

  17. Staging of laser-plasma accelerators

    SciTech Connect

    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.

    2016-05-02

    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. Furthermore, this permitted electron beam trapping, verified by a 100 MeV energy gain.

  18. 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.

  19. 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.

  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. Laser plasma emission of small particles in different gas atmospheres

    NASA Astrophysics Data System (ADS)

    Andreev, Alexander A.; Ueda, Toshitsugu; Wakamatsu, Muneaki

    2002-06-01

    The problem of laser pulse interaction with small solid particles in a gas atmosphere when detecting its parameters is a serous one in industrial and environmental applications. Previous investigations have shown the possibility of using the laser induced breakdown method. This method is very sensitive, but for a particle size of less than 0.1 micrometers the damage threshold of the solid target is very close to the breakdown point of pure gas. At breakdown, a small volume of dense hot plasma emits radiation by which the size and material of particles can be detected. We used an analytical model, simulation code and experiments to analyze this radiation and found that the emitted intensity varied with laser, gas and particle parameters. The increased dependence of SSP plasma emission rate on initial particle volume permits this method to be used for measuring small particle size by using emitted line spectrum at the late time stage.

  2. 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.

  3. Collisionless Plasma Astrophysics Simulation Experiments using Lasers

    SciTech Connect

    Woolsey, N. C.; Ash, A. D.; Courtois, C.; Gregory, C. D.; Hall, I. M.; Howe, J.; Dendy, R. O.

    2006-04-07

    Laboratory experiment is an attractive method of exploring the plasma physics that may occur in solar and astrophysical shocks. An experiment enables repeated and detailed measurements of a plasma as the input conditions are adjusted. To form a scaled experiment of an astrophysical shock a plasma physics model of the shock is required, and the important dimensionless parameters identified and reproduced in the laboratory. A laboratory simulation of a young supernova remnant is described. The experiment uses the interaction of two millimetre-sized counter-streaming laser-produced plasmas placed in a strong transverse magnetic field to achieve this scaling. The collision-free dynamics of the two plasmas and their interaction are studied with and without the magnetic field through spatially and temporally resolved optical measurements. Laboratory astroplasma physics experiments using high-energy, high-power laser technology enables us to reproduce in the laboratory the conditions of temperature and pressure that are met in extreme stellar environments.

  4. Editorial: Focus on Laser- and Beam-Driven Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Joshi, Chan; Malka, Victor

    2010-04-01

    The ability of short but intense laser pulses to generate high-energy electrons and ions from gaseous and solid targets has been well known since the early days of the laser fusion program. However, during the past decade there has been an explosion of experimental and theoretical activity in this area of laser-matter interaction, driven by the prospect of realizing table-top plasma accelerators for research, medical and industrial uses, and also relatively small and inexpensive plasma accelerators for high-energy physics at the frontier of particle physics. In this focus issue on laser- and beam-driven plasma accelerators, the latest advances in this field are described. Focus on Laser- and Beam-Driven Plasma Accelerators Contents Slow wave plasma structures for direct electron acceleration B D Layer, J P Palastro, A G York, T M Antonsen and H M Milchberg Cold injection for electron wakefield acceleration X Davoine, A Beck, A Lifschitz, V Malka and E Lefebvre Enhanced proton flux in the MeV range by defocused laser irradiation J S Green, D C Carroll, C Brenner, B Dromey, P S Foster, S Kar, Y T Li, K Markey, P McKenna, D Neely, A P L Robinson, M J V Streeter, M Tolley, C-G Wahlström, M H Xu and M Zepf Dose-dependent biological damage of tumour cells by laser-accelerated proton beams S D Kraft, C Richter, K Zeil, M Baumann, E Beyreuther, S Bock, M Bussmann, T E Cowan, Y Dammene, W Enghardt, U Helbig, L Karsch, T Kluge, L Laschinsky, E Lessmann, J Metzkes, D Naumburger, R Sauerbrey, M. Scḧrer, M Sobiella, J Woithe, U Schramm and J Pawelke The optimum plasma density for plasma wakefield excitation in the blowout regime W Lu, W An, M Zhou, C Joshi, C Huang and W B Mori Plasma wakefield acceleration experiments at FACET M J Hogan, T O Raubenheimer, A Seryi, P Muggli, T Katsouleas, C Huang, W Lu, W An, K A Marsh, W B Mori, C E Clayton and C Joshi Electron trapping and acceleration on a downward density ramp: a two-stage approach R M G M Trines, R Bingham, Z Najmudin

  5. 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.

  6. Isentropic expansion of copper plasma in Mbar pressure range at "Luch" laser facility

    NASA Astrophysics Data System (ADS)

    Bel'kov, S. A.; Derkach, V. N.; Garanin, S. G.; Mitrofanov, E. I.; Voronich, I. N.; Fortov, V. E.; Levashov, P. R.; Minakov, D. V.

    2014-01-01

    We present experimental results on thermodynamic properties of dense copper plasma in Mbar pressure range. The laser facility "Luch" with laser intensity 1014 W/cm2 is used to compress copper up to ˜8 Mbar by a strong shock wave; subsequent expansion of copper plasma into Al, Ti, Sn allows us to obtain release isentropes of copper by the impedance-matching method. A theoretical analysis and quantum simulations show that in our experiments strongly coupled quantum plasma is generated.

  7. Experimental and theoretical investigation of the effect of laser parameters on laser ablation and laser-induced plasma formation

    NASA Astrophysics Data System (ADS)

    Stancalie, Andrei; Ciobanu, Savu-Sorin; Sporea, Dan

    2016-04-01

    We report results from a wide range of laser operating conditions, typical for laser induced breakdown spectroscopy (LIBS) and laser ablation (LA) experiments on copper metallic target, which form the basis of further systematically investigation of the effect of laser irradiance, pulse duration and wavelength, on the target, plume and plasma behavior, during and after laser-solid interaction. In the LA experiment, the laser beam was focused through a 25 cm focal length convergent lens on a plane copper target in air, at atmospheric pressure. The target was rotated in order to have fresh areas under laser irradiance. In the LIBS experiment, the Applied Photonics LIBS-6 instrument allowed modifying the laser irradiance at the sample surface by changing the pulse energy or the laser focusing distance. For the duration of the laser pulse, the power density at the surface of the target material exceeds 109 W/cm2 using only a compact laser device and simple focusing lenses. The plasma parameters were experimentally estimated from spectroscopic data generated by the plasma itself, namely by the line intensities and their ratio which reflect the relative population of neutral or ionic excited species in the plasma. The fitting of the Saha-Boltzmann plot to a straight line provides an apparent ionization temperature, whose value depends on the lines used in the plots. For the typical conditions of LA and LIBS, the temperature can be so high that Cu+ ions are formed. The first-order ionization of Cu (i.e., the ratio of Cu+/Cu0 ) is calculated.

  8. Laser Plasma Instability Experiments with KrF Lasers

    DTIC Science & Technology

    2007-01-01

    L. Phillips, A. J. Schmitt, J. D. Sethain, R . K. McCrory, W. Seka, C. Verdon, J. P. Knauer, B. B. Afeyan, H. T . Powell, Physics of Plasmas, 5, 5...Physics of Plasmas. 8 R . Betti, K. Anderson, J. Knauer, T . J. B. Collins, R . L. McCrory, R . W. McKenty, S. Skupsky, Physics of Plasmas, 12, 4, 042703...2005). 9 W. L. Kruer, The Physics of Laser Plasma Interactions (Addison-Wesley, Boulder, 1988). 10 J. M. McMahon, R . P. Burns, T . H. DeRieux, R

  9. Laser Beam Propagation through Inertial Confinement Fusion Hohlraum Plasmas

    SciTech Connect

    Froula, D H; Divol, L; Meezan, N B; DIxit, S; Neumayer, P; Moody, J D; Pollock, B B; Ross, J S; Glenzer, S H

    2006-10-26

    A study of the relevant laser-plasma interaction processes has been performed in long-scale length plasmas that emulate the plasma conditions in indirect drive inertial confinement fusion targets. Experiments in this high-temperature (T{sub e} = 3.5 keV), dense (n{sub e} = 0.5 - 1 x 10{sup -3}) hohlraum plasma have demonstrated that blue 351-nm laser beams produce less than 1% total backscatter resulting in transmission greater than 90% for ignition relevant laser intensities (I < 2 x 10{sup 15} W cm{sup -2}). The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows that these results are relevant for the outer beams in ignition hohlraum experiments corresponding to a gain threshold for stimulated Brillouin scattering of 15. By increasing the gas fill density in these experiments further accesses inner beam ignition hohlraum conditions. In this case, stimulated Raman scattering dominates the backscattering processes. They show that scattering is small for gains smaller than 20, which can be achieved through proper choice of the laser beam intensity.

  10. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Effect of pulsed laser target cleaning on ionisation and acceleration of ions in a plasma produced by a femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Vorobiev, A. A.; Gordienko, Vyacheslav M.; Dzhidzhoev, M. S.; Lachko, I. M.; Mar'in, B. V.; Savel'ev, Andrei B.; Uryupina, D. S.

    2005-10-01

    The impurity layer on the surface of a solid target is shown to exert a significant effect on the characteristics of the ion current of the laser plasma produced under the action of ultrahigh-intensity femtosecond radiation on the surface of this target. The application of pulsed laser cleaning gives rise to an additional high-energy component in the ion spectrum of the target material. It is shown that the ion current parameters of the laser plasma such as the average and highest ion charge, the highest ion energy of the target material, etc., can be controlled by varying the lead time of the cleaning laser radiation.

  11. Enhancement of laser plasma extreme ultraviolet emission by shockwave-laser interaction

    SciTech Connect

    Bruijn, Rene de; Koshelev, Konstantin N.; Zakharov, Serguei V.; Novikov, Vladimir G.; Bijkerk, Fred

    2005-04-15

    A double laser pulse heating scheme has been applied to generate plasmas with enhanced emission in the extreme ultraviolet (EUV). The plasmas were produced by focusing two laser beams (prepulse and main pulse) with a small spatial separation between the foci on a xenon gas jet target. Prepulses with ps-duration were applied to obtain high shockwave densities, following indications of earlier published results obtained using ns prepulses. EUV intensities around 13.5 nm and in the range 5-20 nm were recorded, and a maximum increase in intensity exceeding 2 was measured at an optimal delay of 140 ns between prepulse and main pulse. The gain in intensity is explained by the interaction of the shockwave produced by the prepulse with the xenon in the beam waist of the main pulse. Extensive simulation was done using the radiative magnetohydrodynamic code Z{sup *}.

  12. The effect of laser contrast on generation of highly charged Fe ions by ultra-intense femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Faenov, Anatoly Ya.; Alkhimova, Maria A.; Pikuz, Tatiana A.; Skobelev, Igor Yu.; Nishiuchi, Mamiko; Sakaki, Hironao; Pirozhkov, Alexander S.; Sagisaka, Akito; Dover, Nicholas P.; Kondo, Kotaro; Ogura, Koichi; Fukuda, Yuji; Kiriyama, Hiromitsu; Andreev, Alexander; Nishitani, Keita; Miyahara, Takumi; Watanabe, Yukinobu; Pikuz, Sergey A.; Kando, Masaki; Kodama, Ruosuke; Kondo, Kiminori

    2017-07-01

    Experimental studies on the formation of highly charged ions of medium-Z elements using femtosecond laser pulses with different contrast levels were carried out. Multiply charged Fe ions were generated by laser pulses with 35 fs duration and an intensity exceeding 1021 W/cm2. Using high-resolution X-ray spectroscopic methods, bulk electron temperature of the generated plasma has been identified. It is shown that the presence of a laser pre-pulse at a contrast level of 105-106 with respect to the main pulse drastically decreases the degree of Fe ionization. We conclude that an effective source of energetic, multiply charged moderate and high- Z ions based on femtosecond laser-plasma interactions can be created only using laser pulses of ultra-high contrast.

  13. 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.

  14. Laser-driven Acceleration in Clustered Plasmas

    SciTech Connect

    Gao, X.; Wang, X.; Shim, B.; Downer, M. C.

    2009-01-22

    We propose a new approach to avoid dephasing limitation of laser wakefield acceleration by manipulating the group velocity of the driving pulse using clustered plasmas. We demonstrated the control of phase velocity in clustered plasmas by third harmonic generation and frequency domain interferometry experiments. The results agree with a numerical model. Based on this model, the group velocity of the driving pulse in clustered plasmas was calculated and the result shows the group velocity can approach the speed of light c in clustered plasmas.

  15. 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.

  16. Nonlinear spectral singularities and laser output intensity

    NASA Astrophysics Data System (ADS)

    Ghaemi-Dizicheh, Hamed; Mostafazadeh, Ali; Sarısaman, Mustafa

    2017-10-01

    The mathematical notion of spectral singularity admits a description in terms of purely outgoing solutions of a corresponding linear wave equation. This leads to a nonlinear generalization of this notion for nonlinearities that are confined in space. We examine the nonlinear spectral singularities in arbitrary transverse electric (TE) and transverse magnetic (TM) modes of a mirrorless slab laser that involves a weak Kerr nonlinearity. This provides a computational scheme for the determination of the laser output intensity I for these modes. In particular, we offer an essentially mathematical derivation of the linear-dependence of I on the gain coefficient g and obtain an explicit analytic expression for its slope. This shows that if the real part η of the refractive index of the slab does not exceed 3, there is a lower bound on the incidence angle θ below which lasing in both its TE and TM modes requires η to be shifted by a small amount as g surpasses the threshold gain. Our results suggest that lasing in the oblique TM modes of the slab is forbidden if the incidence (emission) angle of the TM mode exceeds the Brewster’s angle.

  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-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.

  19. Laser fluence dependence on emission dynamics of ultrafast laser induced copper plasma

    SciTech Connect

    Anoop, K. K.; Harilal, S. S.; Philip, Reji; Bruzzese, R.; Amoruso, S.

    2016-11-14

    The characteristic emission features of a laser-produced plasma strongly depend strongly on the laser fluence. We investigated the spatial and temporal dynamics of neutrals and ions in femtosecond laser (800 nm, ≈ 40 fs, Ti:Sapphire) induced copper plasma in vacuum using both optical emission spectroscopy (OES) and spectrally resolved two-dimensional (2D) imaging methods over a wide fluence range of 0.5 J/cm2-77.5 J/cm2. 2D fast gated monochromatic images showed distinct plume splitting between the neutral and ions especially at moderate to higher fluence ranges. OES studies at low to moderate laser fluence regime confirm intense neutral line emission over the ion emission whereas this trend changes at higher laser fluence with dominance of the latter. This evidences a clear change in the physical processes involved in femtosecond laser matter interaction at high input laser intensity. The obtained ion dynamics resulting from the OES, and spectrally resolved 2D imaging are compared with charged particle measurement employing Faraday cup and Langmuir probe and results showed good correlation.

  20. Effect of the laser wavefront in a laser-plasma accelerator

    NASA Astrophysics Data System (ADS)

    Vernier, Aline; Beaurepaire, B.; Bocoum, M.; Böhle, F.; Jullien, A.; Rousseau, J.-P.; Lefrou, T.; Iaquaniello, G.; Lopez-Martens, R.; Lifschitz, A.; Faure, J.

    2015-11-01

    Laser-plasma accelerators are a promising alternative as they can currently provide short (down to a few fs), relativistic (from a few MeV up to a few GeV) electron beams over millimeter distances. In such devices, an intense laser pulse drives a plasma wave in which self-injected electrons can be accelerated. The quality, in terms of emittance, of such electron beams is known to strongly depend on the laser focal spot, but very little attention is generally given to the laser transverse distribution on either side of the focal plane. Our recent experimental results and PIC simulations quantify the role of the wavefront at the focus on the acceleration of eletrons: distortions of the laser wavefront cause spatial inhomogeneity of the out-of-focus laser intensity distribution and consequently, the laser pulse drives a transversely inhomogenous wakefield whose focusing/defocusing properties affect the electron distribution. We acknowledge support from the ERC (Contract No. 306708), and the ANR (ANR-11-EQPX-005-ATTOLAB).

  1. Plasma confinement by hemispherical cavity in laser-induced breakdown spectroscopy

    SciTech Connect

    Guo, L. B.; Li, C. M.; Hu, W.; Zhou, Y. S.; Zhang, B. Y.; Lu, Y. F.; Cai, Z. X.; Zeng, X. Y.

    2011-03-28

    An aluminum hemispherical cavity (diameter: 11.1 mm) was used to confine plasmas produced by a KrF excimer laser in air from a steel target with a low concentration manganese in laser-induced breakdown spectroscopy. A significant enhancement (factor >12) in the emission intensity of Mn lines was observed at a laser fluence of 7.8 J/cm{sup 2} when the plasma was confined by the hemispherical cavity, leading to an increase in plasma temperature about 3600 K. The maximum emission enhancement increased with increasing laser fluence. The spatial confinement mechanism was discussed using shock wave theory.

  2. Raman scattering of circularly polarized laser beam in homogeneous and inhomogeneous magnetized plasma channel

    NASA Astrophysics Data System (ADS)

    Ghaffari-Oskooei, S. S.; Aghamir, F. M.

    2017-06-01

    Raman scattering of circularly polarized laser beams in a magnetized plasma channel is investigated. The scattering is considered as parametric instability. Dispersion relations of backward and forward scattered waves in a magnetized plasma are derived in a weakly relativistic regime. Growth rates of the corresponding instabilities are calculated. The effects of laser intensity and its polarization as well as the strength of the magnetic field and corresponding cyclotron frequency along with plasma density and its inhomogeneity on the growth rate of Raman scattering are examined. The study shows that the left-handed circularly polarized laser beam has different behaviors in comparison to the right-handed beam, and their growth rates are different due to the anisotropic properties of the magnetized plasma. In addition, Raman scattering in an inhomogeneous plasma with a linear density profile is investigated. The comparison between homogeneous and inhomogeneous plasmas has indicated that inhomogeneity reduces the growth rate. The frequency shift of scattered waves, when laser intensity is high, is studied in the magnetized plasma. The findings indicate that the shift depends on laser intensity and its polarization as well as plasma density and dc magnetic field. The frequency shift can be used as a diagnostic tool for density measurement in laser-plasma interactions.

  3. 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.

  4. Properties of laser radiation scattering by a laser-induced spark plasma revisited after 40 years

    SciTech Connect

    Malyutin, A A

    2008-05-31

    Experimental studies of a laser-induced spark produced in air by 1.05-{mu}m, 100-ns pulses with spatial TEM{sub 00}, TEM{sub 01} and TEM{sub 02} modes are described. It is found that when the spark is observed at an angle of 90{sup 0} to the laser beam axis, the scattered radiation has the maximal intensity outside the beam waist. The intensity ratio of the scattered laser radiation for two orthogonal polarisations is {approx}100, and the spatial structures of their depolarisation considerably differ. These properties are explained by using a model of the Fresnel reflection from the spherical front of the plasma-undisturbed gas interface. (laser radiation scattering)

  5. Trends in laser-plasma-instability experiments for laser fusion

    SciTech Connect

    Drake, R.P. Lawrence Livermore National Lab., CA )

    1991-06-06

    Laser-plasma instability experiments for laser fusion have followed three developments. These are advances in the technology and design of experiments, advances in diagnostics, and evolution of the design of high-gain targets. This paper traces the history of these three topics and discusses their present state. Today one is substantially able to produce controlled plasma conditions and to diagnose specific instabilities within such plasmas. Experiments today address issues that will matter for future laser facilities. Such facilities will irradiate targets with {approx}1 MJ of visible or UV light pulses that are tens of nanoseconds in duration, very likely with a high degree of spatial and temporal incoherence. 58 refs., 4 figs.

  6. Simulation of laser-plasma interactions and fast-electron transport in inhomogeneous plasma

    SciTech Connect

    Cohen, B.I. Kemp, A.J.; Divol, L.

    2010-06-20

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogeneous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  7. Hybrid Simulation of Laser-Plasma Interactions and Fast Electron Transport in Inhomogeneous Plasma

    SciTech Connect

    Cohen, B I; Kemp, A; Divol, L

    2009-05-27

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogenous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  8. Spectroscopic Studies of Laser Produced Plasma Metasurfaces

    NASA Astrophysics Data System (ADS)

    Colon Quinones, Roberto; Underwood, Thomas; Cappelli, Mark

    2016-10-01

    In this presentation, we describe the spatial and temporal plasma characteristics of the dense plasma kernels that are used to construct a laser produced plasma metasurface (PM) that is intended to serve as a tunable THz reflector. The PM is an n x n array of plasmas generated by focusing the light from a 2 J/p Q-switched Nd:YAG laser through a multi-lens array (MLA) and into a gas of varying pressure. A gated CCD camera coupled to a high-resolution spectrometer is used to obtain chord-averaged H α broadening data for the cross section of a single plasma element at the lens focal point. The data is then Abel inverted to derive the radial plasma density distribution. Measurements are repeated for a range of pressures, laser energies, and lens f-number, with a time resolution of 100 ns and a gate width of 20 ns. Results are presented for the variation of plasma density and size over these different conditions. Work supported by the Air Force Office of Scientific Research (AFOSR). R. Colon Quinones and T. Underwood acknowledge the support of the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

  9. 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.

  10. Plasma spectroscopy using optical vortex laser

    NASA Astrophysics Data System (ADS)

    Yoshimura, Shinji; Aramaki, Mitsutoshi; Terasaka, Kenichiro; Toda, Yasunori; Czarnetzki, Uwe; Shikano, Yutaka

    2014-10-01

    Laser spectroscopy is a useful tool for nonintrusive plasma diagnostics; it can provide many important quantities in a plasma such as temperature, density, and flow velocity of ions and neutrals from the spectrum obtained by scanning the frequency of narrow bandwidth laser. Obtainable information is, however, limited in principle to the direction parallel to the laser path. The aim of this study is to introduce a Laguerre-Gaussian beam, which is called as optical vortex, in place of a widely used Hermite-Gaussian beam. One of the remarkable properties of the Laguerre-Gaussian beam is that it carries an angular momentum in contrast to the Hermite-Gaussian beam. It follows that particles in the laser beam feel the Doppler effect even in the transverse direction of the laser path. Therefore it is expected that the limitation imposed by the laser path can be overcome by using an optical vortex laser. The concept of optical vortex spectroscopy, the development of the laser system, and some preliminary results of a proof-of-principle experiment will be presented. This work is performed with the support and under the auspices of NINS young scientists collaboration program for cross-disciplinary study, NIFS collaboration research program (NIFS13KOAP026), and JSPS KAKENHI Grant Number 25287152.

  11. Ge laser-generated plasma for ion implantation

    NASA Astrophysics Data System (ADS)

    Giuffrida, L.; Torrisi, L.; Czarnecka, A.; Wołowski, J.; Quarta, Ge; Calcagnile, L.; Lorusso, A.; Nassisi, V.

    Laser-generated plasma obtained by Ge ablation in vacuum was investigated with the aim to implant energetic Ge ions in light substrates (C, Si, SiO2). Different intensities of laser sources were employed for these experiments: Nd:Yag of Catania-LNS; Nd:Yag of Warsaw-IPPL; excimer laser of Lecce-INFN; iodine laser of Prague-PALS. Different experimental setups were used to generate multiple ion stream emissions, multiple ion energetic distributions, high implantation doses, thin film deposition and post-acceleration effects. `On line' measurements of ion energy were obtained with ion collectors and ion energy analyzer in time-of-flight configuration. `Off line' measurement of Ge implants were obtained with 2.25 MeV helium beam in Rutherford backscattering spectrometry. Results indicated that ion implants show typical deep profiles only for substrates placed along the normal to the target surface at which the ion energy is maximum.

  12. Saturation of Langmuir waves in laser-produced plasmas

    SciTech Connect

    Baker, K.L.

    1996-04-01

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

  13. Kinetic simulations of laser parametric amplification in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Jia, Qing; Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

    2017-09-01

    Laser pulse compression using magnetized resonance near the upper-hybrid frequency is promising for achieving higher output intensity in regimes previously thought impossible using unmagnetized plasmas. Using one dimensional particle-in-cell simulations, we verify that, by partially replacing plasma with an external transverse magnetic field of megagauss scale, the output pulse can be intensified by a factor of a few, due to the increased allowable amplification time despite a decreased growth rate. Further improvement is impeded by the generation of an electromagnetic wakefield, to which the amplified pulse loses more energy than it does in the unmagnetized case. This limitation can however be circumvented by the use of a stronger pump. In contrast to unmagnetized compression, the magnetized amplification remains efficient when the pump intensity is well above the wavebreaking threshold, until a higher phase-mixing threshold is exceeded. This surprising resilience to wavebreaking in magnetized plasma is of great benefit for magnetized compression.

  14. Adventures in Laser Produced Plasma Research

    SciTech Connect

    Key, M

    2006-01-13

    In the UK the study of laser produced plasmas and their applications began in the universities and evolved to a current system where the research is mainly carried out at the Rutherford Appleton Laboratory Central Laser Facility ( CLF) which is provided to support the universities. My own research work has been closely tied to this evolution and in this review I describe the history with particular reference to my participation in it.

  15. Second harmonic generation of Cosh-Gaussian laser beam in collisional plasma with nonlinear absorption

    NASA Astrophysics Data System (ADS)

    Singh, Navpreet; Gupta, Naveen; Singh, Arvinder

    2016-12-01

    This paper investigates second harmonic generation (SHG) of an intense Cosh-Gaussian (ChG) laser beam propagating through a preformed underdense collisional plasma with nonlinear absorption. Nonuniform heating of plasma electrons takes place due to the nonuniform irradiance of intensity along the wavefront of laser beam. This nonuniform heating of plasma leads to the self-focusing of the laser beam and thus produces strong density gradients in the transverse direction. The density gradients so generated excite an electron plasma wave (EPW) at pump frequency that interacts with the pump beam to produce its second harmonics. To envision the propagation dynamics of the ChG laser beam, moment theory in Wentzel-Kramers-Brillouin (W.K.B) approximation has been invoked. The effects of nonlinear absorption on self-focusing of the laser beam as well as on the conversion efficiency of its second harmonics have been theoretically investigated.

  16. Laser-Produced Plasmas and Radiation Sources.

    DTIC Science & Technology

    1980-01-31

    Vlases, H. Rutkowski, A. Hertzberg, A. Hoffman, L. Steinhauer, J. Dawson, D.R. Cohn, W. Halverson, B. Lax, J.D. Daugherty, J.E. Eninger , E.R. Pugh, T.K...Meeting, Albuquerque (October 1974). J.D. Daugherty, J.E. Eninger , D.R. Cohn, and W. Halverson, "Scaling of Laser Heated Plasmas Confined in Long Solenoids...Cohn, H.E. Eninger , W. Halverson, and D.J. Rose, "Stress, Dissipation, and Neutronics Constraints on ’fagnets for Laser-Solenoid Reactors," APS Plasma

  17. Ion beams from laser-generated plasmas

    NASA Technical Reports Server (NTRS)

    Hughes, R. H.; Anderson, R. J.; Gray, L. G.; Rosenfeld, J. P.; Manka, C. K.; Carruth, M. R.

    1980-01-01

    The paper describes the space-charge-limited beams produced by the plasma blowoffs generated by 20-MW bursts of 1.06-micron radiation from an active Q-switched Nd:YAG laser. Laser power densities near 10 to the 11th/sq cm on solid targets generate thermalized plasma plumes which drift to a 15-kV gridded extraction gap where the ions are extracted, accelerated, and electrostatically focused; the spatially defined ion beams are then magnetically analyzed to determine the charge state content in the beams formed from carbon, aluminum, copper, and lead targets. This technique preserves time-of-flight (TOF) information in the plasma drift region, which permits plasma ion temperatures and mass flow velocities to be determined from the Maxwellian ion curve TOF shapes for the individual charge species.

  18. Plasma acceleration and cooling by strong laser field due to the action of radiation reaction force.

    PubMed

    Berezhiani, V I; Mahajan, S M; Yoshida, Z

    2008-12-01

    It is shown that for super intense laser pulses propagating in a hot plasma, the action of the radiation reaction force (appropriately incorporated into the equations of motion) causes strong bulk plasma motion with the kinetic energy raised even to relativistic values; the increase in bulk energy is accompanied by a corresponding cooling (intense cooling) of the plasma. The effects are demonstrated through explicit analytical calculations.

  19. Coupling between electron plasma waves in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Everett, M. J.; Lal, A.; Clayton, C. E.; Mori, W. B.; Joshi, C.; Johnston, T. W.

    1996-05-01

    A Lagrangian fluid model (cold plasma, fixed ions) is developed for analyzing the coupling between electron plasma waves. This model shows that a small wave number electron plasma wave (ω2,k2) will strongly affect a large wave number electron plasma wave (ω1,k1), transferring its energy into daughter waves or sidebands at (ω1+nω2,k1+nk2) in the lab frame. The accuracy of the model is checked via particle-in-cell simulations, which confirm that the energy in the mode at (ω1,k1) can be completely transferred to the sidebands at (ω1+nω2,k1+nk2) by the presence of the electron plasma mode at (ω2,k2). Conclusive experimental evidence for the generation of daughter waves via this coupling is then presented using time- and wave number-resolved spectra of the light from a probe laser coherently Thomson scattered by the electron plasma waves generated by the interaction of a two-frequency CO2 laser with a plasma.

  20. Study of spatio-temporal dynamics of laser-hole boring in near critical plasma

    NASA Astrophysics Data System (ADS)

    Tochitsky, Sergei; Gong, Chao; Fiuza, Frederico; Pigeon, Jeremy; Joshi, Chan

    2015-11-01

    At high-intensities of light, radiation pressure becomes one of the dominant mechanisms in laser-plasma interaction. The radiation pressure of an intense laser pulse can steepen and push the critical density region of an overdense plasma creating a cavity or a hole. This hole boring phenomenon is of importance in fast-ignition fusion, high-gradient laser-plasma ion acceleration, and formation of collisionless shocks. Here multi-frame picosecond optical interferometry is used for the first direct measurements of space and time dynamics of the density cavity as it is pushed forward by a train of CO2 laser pulses in a helium plasma. The measured values of the hole boring velocity into an overdense plasma as a function of laser intensity are consistent with a theory based on energy and momentum balance between the heated plasma and the laser and with two-dimensional numerical simulations. We show possibility to extract a relative plasma electron temperature within the laser pulse by applying an analytical theory to the measured hole boring velocities. This work was supported by DOE grant DE-SC0010064.