Nonlinear laser-plasma interactions
Kaw, P. K.
2017-12-01
laser plasma experiments and have become the backbone of our present understanding of how lasers nonlinearly interact with fully ionized fusion plasmas. A review of this early work will be presented. We shall also present a review of our involvement in the recent work on nonlinear penetration of light into overdense plasmas with gradual and sharp interfaces.
Towards modeling of nonlinear laser-plasma interactions with hydrocodes: The thick-ray approach
Colaïtis, A.; Duchateau, G.; Nicolaï, P.; Tikhonchuk, V.
2014-03-01
This paper deals with the computation of laser beam intensity in large-scale radiative hydrocodes applied to the modeling of nonlinear laser-plasma interactions (LPIs) in inertial confinement fusion (ICF). The paraxial complex geometrical optics (PCGO) is adapted for light waves in an inhomogeneous medium and modified to include the inverse bremsstrahlung absorption and the ponderomotive force. This thick-ray model is compared to the standard ray-tracing (RT) approach, both in the chic code. The PCGO model leads to different power deposition patterns and better diffraction modeling compared to standard RT codes. The intensity-reconstruction technique used in RT codes to model nonlinear LPI leads to artificial filamentation and fails to reproduce realistic ponderomotive self-focusing distances, intensity amplifications, and density channel depletions, whereas PCGO succeeds. Bundles of Gaussian thick rays can be used to model realistic non-Gaussian ICF beams. The PCGO approach is expected to improve the accuracy of ICF simulations and serve as a basis to implement diverse LPI effects in large-scale hydrocodes.
International Nuclear Information System (INIS)
Labaune, C.; Fuchs, J.; Bandulet, H.
2002-01-01
Imprint elimination, smoothing and preheat control are considerable problems in inertial fusion and their possible solution can be achieved by using low-density porous materials as a buffer in target design. The articles gathered in this document present various aspects of the laser-plasma interaction, among which we have noticed: -) numerical algorithmic improvements of the Vlasov solver toward the simulation of the laser-plasma interaction are proposed, -) the dependence of radiation temperatures and X-ray conversion efficiencies of hohlraum on the target structures and laser irradiation conditions are investigated, -) a study of laser interaction with ultra low-density (0,5 - 20 mg/cm 3 ) porous media analyzing backscattered light at incident laser frequency ω 0 and its harmonics 3*ω 0 /2 and 2*ω 0 is presented, -) investigations of laser interaction with solid targets and crater formation are carried out with the objective to determine the ablation loading efficiency, -) a self organization in an intense laser-driven plasma and the measure of the relative degree of order of the states in an open system based on the S-theorem are investigated, and -) the existence and stability of electromagnetic solitons generated in a relativistic interaction of an intense laser light with uniform under-dense cold plasma are studied
Laser-plasma interactions and applications
Neely, David; Bingham, Robert; Jaroszynski, Dino
2013-01-01
Laser-Plasma Interactions and Applications covers the fundamental and applied aspects of high power laser-plasma physics. With an internationally renowned team of authors, the book broadens the knowledge of young researchers working in high power laser-plasma science by providing them with a thorough pedagogical grounding in the interaction of laser radiation with matter, laser-plasma accelerators, and inertial confinement fusion. The text is organised such that the theoretical foundations of the subject are discussed first, in Part I. In Part II, topics in the area of high energy density physics are covered. Parts III and IV deal with the applications to inertial confinement fusion and as a driver of particle and radiation sources, respectively. Finally, Part V describes the principle diagnostic, targetry, and computational approaches used in the field. This book is designed to give students a thorough foundation in the fundamental physics of laser-plasma interactions. It will also provide readers with knowl...
Quasilinear theory of laser-plasma interactions
International Nuclear Information System (INIS)
Neil, A.J.
1992-01-01
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 pondermotive 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 the author proposes 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 the author has applied quasilinear theory to model the resonant interactions of the photons in an ISI beam with the beam's wake field. An analytic expression is derived 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 with the maximum growth rate for the ponderomotive filamentation of a uniform beam, the author derived a worst case criterion for stability against ponderomotive filamentation
TOPICAL REVIEW: Relativistic laser-plasma interactions
Umstadter, Donald
2003-04-01
By focusing petawatt peak power laser light to intensities up to 1021 W cm-2, highly relativistic plasmas can now be studied. The force exerted by light pulses with this extreme intensity has been used to accelerate beams of electrons and protons to energies of a million volts in distances of only microns. This acceleration gradient is a thousand times greater than in radio-frequency-based accelerators. Such novel compact laser-based radiation sources have been demonstrated to have parameters that are useful for research in medicine, physics and engineering. They might also someday be used to ignite controlled thermonuclear fusion. Ultrashort pulse duration particles and x-rays that are produced can resolve chemical, biological or physical reactions on ultrafast (femtosecond) timescales and on atomic spatial scales. These energetic beams have produced an array of nuclear reactions, resulting in neutrons, positrons and radioactive isotopes. As laser intensities increase further and laser-accelerated protons become relativistic, exotic plasmas, such as dense electron-positron plasmas, which are of astrophysical interest, can be created in the laboratory. This paper reviews many of the recent advances in relativistic laser-plasma interactions.
Laser-Plasma Interactions in Magnetized Environment
Shi, Yuan
2017-10-01
Propagation and scattering of lasers present new phenomena and applications when the plasma medium becomes magnetized. Starting from mega-Gauss magnetic fields, laser scattering becomes manifestly anisotropic [arXiv 1705.09758]. By arranging beams at special angles, one may be able to optimize laser-plasma coupling in magnetized environment. In stronger giga-Gauss magnetic field, laser propagation becomes modified by relativistic quantum effects [PRA 94.012124]. The modified wave dispersion relation enables correct interpretation of Faraday rotation measurements of strong magnetic fields, as well as correct extraction of plasma parameters from the X-ray spectra of pulsars. In addition, magnetized plasmas can be utilized to mediate laser pulse compression [PRE 95.023211]. Using magnetic resonances, it is not only possible to produce optic pulses of higher intensity, but also possible to amplify UV and soft X-ray pulses that cannot be compressed using existing technology. This research is supported by NNSA Grant No. DE-NA0002948 and DOE Research Grant No. DEAC02- 09CH11466.
Mono Energetic Beams from Laser Plasma Interactions
Geddes, Cameron G; Esarey, Eric; Leemans, Wim; Nieter, Chet; Schröder, Carl B; Toth, Csaba; Van Tilborg, Jeroen
2005-01-01
A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the LOASIS laser,* the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing >200pC charge above 80 MeV and with normalized emittance estimated at < 2 pi -mm-mrad were produced.** Data and simulations (VORPAL***) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was g...
PIC Simulation of Laser Plasma Interactions with Temporal Bandwidths
Tsung, Frank; Weaver, J.; Lehmberg, R.
2015-11-01
We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temperal bandwidths under conditions relevant to current and future shock ignition experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth, the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using smoothing techniques such as SSD or ISI). We will show that temporal bandwidth along play an important role in the control of LPI's in these lasers and discuss future directions. This work is conducted under the auspices of NRL.
Laser plasma interaction physics on the LIL facility
International Nuclear Information System (INIS)
Masson-Laborde, P. E.; Depierreux, S.; Michel, D. T.; Hueller, S.; Pesme, D.; Robiche, J.; Loiseau, P.; Tikhonchuk, V. T.; Stenz, C.; Nicolai, P.; Casanova, M.; Teychenne, D.; Marion, D.; Goyon, C.; Yahia, V.; Riconda, C.; Borisenko, N. G.; Nazarov, W.; Wrobel, R.; Labaune, C.
2013-01-01
We present an overview of the interpretation of laser plasma interaction (LPI) experiments carried out on the LIL facility. These multi-kiloJoule experiments have been done using underdense foam targets at 0.351 μm laser light leading to high temperature and large plasmas. We discuss the interpretation using our different numerical tools: hydrodynamics simulations carried out with the code FCI2 to characterize the plasma, linear gain estimates with the post processor Piranah and paraxial simulations with the code HERA. (authors)
Klimentov, Sergei M.; Kononenko, Taras V.; Pivovarov, Pavel A.; Konov, Vitalii I.; Prokhorov, A. M.; Breitling, D.; Dausinger, F.
2002-05-01
Nonlinear light scattering appearing upon air breakdown induced by high-power ultrashort pulses (110 — 5200 fs) from a Ti:Al2O3 laser is studied. As a result of forward scattering, the beam profile is severely deformed, which is accompanied by spectral conversion of the incident radiation to a series of shorter-wavelength peaks extending into the visible spectral range. Measurements are made of the thresholds and the scattered radiation energy, which amounts to 75% of the incident energy. The effect of scattering on the material ablation in air is investigated. The obtained data offer an explanation for the experimentally observed paradoxical morphology of the channels ablated by high-power femtosecond pulses.
Progress in Long Scale Length Laser-Plasma Interactions
International Nuclear Information System (INIS)
Glenzer, S H; Arnold, P; Bardsley, G; Berger, R L; Bonanno, G; Borger, T; Bower, D E; Bowers, M; Bryant, R; Buckman, S.; Burkhart, S C; Campbell, K; Chrisp, M P; Cohen, B I; Constantin, G; Cooper, F; Cox, J; Dewald, E; Divol, L; Dixit, S; Duncan, J; Eder, D; Edwards, J; Erbert, G; Felker, B; Fornes, J; Frieders, G; Froula, D H; Gardner, S D; Gates, C; Gonzalez, M; Grace, S; Gregori, G; Greenwood, A; Griffith, R; Hall, T; Hammel, B A; Haynam, C; Heestand, G; Henesian, M; Hermes, G; Hinkel, D; Holder, J; Holdner, F; Holtmeier, G; Hsing, W; Huber, S; James, T; Johnson, S; Jones, O S; Kalantar, D; Kamperschroer, J H; Kauffman, R; Kelleher, T; Knight, J; Kirkwood, R K; Kruer, W L; Labiak, W; Landen, O L; Langdon, A B; Langer, S; Latray, D; Lee, A; Lee, F D; Lund, D; MacGowan, B; Marshall, S; McBride, J; McCarville, T; McGrew, L; Mackinnon, A J; Mahavandi, S; Manes, K; Marshall, C; Mertens, E; Meezan, N; Miller, G; Montelongo, S; Moody, J D; Moses, E; Munro, D; Murray, J; Neumann, J; Newton, M; Ng, E; Niemann, C; Nikitin, A; Opsahl, P; Padilla, E; Parham, T; Parrish, G; Petty, C; Polk, M; Powell, C; Reinbachs, I; Rekow, V; Rinnert, R; Riordan, B; Rhodes, M.
2003-01-01
The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3ω) with a total intensity of 2 x 10 15 W cm -2 . The targets were filled with 1 atm of CO 2 producing of up to 7 mm long homogeneously heated plasmas with densities of n e = 6 x 10 20 cm -3 and temperatures of T e = 2 keV. The high energy in a NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last ∼1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 6% for the smallest length (∼2 mm). increasing to 12% for ∼7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modeling of the laser-plasma interactions at ignition-size scale lengths
Progress in long scale length laser plasma interactions
Glenzer, S. H.; Arnold, P.; Bardsley, G.; Berger, R. L.; Bonanno, G.; Borger, T.; Bower, D. E.; Bowers, M.; Bryant, R.; Buckman, S.; Burkhart, S. C.; Campbell, K.; Chrisp, M. P.; Cohen, B. I.; Constantin, C.; Cooper, F.; Cox, J.; Dewald, E.; Divol, L.; Dixit, S.; Duncan, J.; Eder, D.; Edwards, J.; Erbert, G.; Felker, B.; Fornes, J.; Frieders, G.; Froula, D. H.; Gardner, S. D.; Gates, C.; Gonzalez, M.; Grace, S.; Gregori, G.; Greenwood, A.; Griffith, R.; Hall, T.; Hammel, B. A.; Haynam, C.; Heestand, G.; Henesian, M.; Hermes, G.; Hinkel, D.; Holder, J.; Holdner, F.; Holtmeier, G.; Hsing, W.; Huber, S.; James, T.; Johnson, S.; Jones, O. S.; Kalantar, D.; Kamperschroer, J. H.; Kauffman, R.; Kelleher, T.; Knight, J.; Kirkwood, R. K.; Kruer, W. L.; Labiak, W.; Landen, O. L.; Langdon, A. B.; Langer, S.; Latray, D.; Lee, A.; Lee, F. D.; Lund, D.; MacGowan, B.; Marshall, S.; McBride, J.; McCarville, T.; McGrew, L.; Mackinnon, A. J.; Mahavandi, S.; Manes, K.; Marshall, C.; Menapace, J.; Mertens, E.; Meezan, N.; Miller, G.; Montelongo, S.; Moody, J. D.; Moses, E.; Munro, D.; Murray, J.; Neumann, J.; Newton, M.; Ng, E.; Niemann, C.; Nikitin, A.; Opsahl, P.; Padilla, E.; Parham, T.; Parrish, G.; Petty, C.; Polk, M.; Powell, C.; Reinbachs, I.; Rekow, V.; Rinnert, R.; Riordan, B.; Rhodes, M.; Roberts, V.; Robey, H.; Ross, G.; Sailors, S.; Saunders, R.; Schmitt, M.; Schneider, M. B.; Shiromizu, S.; Spaeth, M.; Stephens, A.; Still, B.; Suter, L. J.; Tietbohl, G.; Tobin, M.; Tuck, J.; Van Wonterghem, B. M.; Vidal, R.; Voloshin, D.; Wallace, R.; Wegner, P.; Whitman, P.; Williams, E. A.; Williams, K.; Winward, K.; Work, K.; Young, B.; Young, P. E.; Zapata, P.; Bahr, R. E.; Seka, W.; Fernandez, J.; Montgomery, D.; Rose, H.
2004-12-01
The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3ω) with a total intensity of 2 × 1015 W cm-2. The targets were filled with 1 atm of CO2 producing up to 7 mm long homogeneously heated plasmas with densities of ne = 6 × 1020 cm-3 and temperatures of Te = 2 keV. The high energy in an NIF quad of beams of 16 kJ, illuminating the target from one direction, creates unique conditions for the study of laser-plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x-rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last ~1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 3% for the smallest length (~2 mm), increasing to 10-12% for ~7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modelling of the laser-plasma interactions at ignition-size scale lengths.
Laser--plasma interaction in a theta-pinch geometry
International Nuclear Information System (INIS)
Armstrong, W.T.
1978-06-01
Prompt stimulated Brillouin scatter (SBS) is studied in an experiment wherein a high power, pulsed CO 2 laser irradiates an independently produced, theta-pinch plasma. SBS does not significantly affect laser heating of the plasma. Measurements of density profiles and temperature histories permitted examination of laser refraction, local heating and net absorption. Refractive containment of the CO 2 laser beam by an on-axis density minimum was observed at early times during the laser pulse. However, refractive containment was lost at late times due to the diffusive loss of the density minimum. Classical modeling of the expected heating required ''bleached'' absorption to account for the observed heating. A plasma absorptivity of approximately 46% was inferred from calorimetry measurements at 250 mtorr fill pressure. These results confirm that classical heating and refraction dominated the laser-plasma interaction
Novel features of non-linear Raman instability in a laser plasma
Czech Academy of Sciences Publication Activity Database
Mašek, Martin; Rohlena, Karel
2010-01-01
Roč. 56, č. 1 (2010), s. 79-90 ISSN 1434-6060 R&D Projects: GA MŠk(CZ) 7E08099; GA MŠk(CZ) LC528; GA ČR GA202/05/2475 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser plasma * non-linear Raman instability Subject RIV: BH - Optics, Masers, Laser s Impact factor: 1.513, year: 2010
60th Scottish Universities Summer School in Physics: 6th Laser-plasma interactions
Cairns, R A; Jaroszinski, D A
2009-01-01
Presents diagnostic methods, experimental techniques, and simulation tools used to study and model laser-plasma interactions. This book discusses the basic theory of the interaction of intense electromagnetic radiation fields with matter.
Energy Technology Data Exchange (ETDEWEB)
Kemp, Gregory Elijah [The Ohio State Univ., Columbus, OH (United States)
2013-01-01
Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic
Ion Acceleration by Laser Plasma Interaction from Cryogenic Microjets
Energy Technology Data Exchange (ETDEWEB)
Propp, Adrienne [Harvard Univ., Cambridge, MA (United States)
2015-08-16
Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high-power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. However, this mechanism is not ideal for creating the high-energy proton beams needed for future applications. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for exploring new regimes of ion acceleration. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we achieved a pure proton beam with evidence of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the possibility of transforming our liquid cryogenic
Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor
International Nuclear Information System (INIS)
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 > 5x10 17 W/cm 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
Electrons trajectories around a bubble regime in intense laser plasma interaction
International Nuclear Information System (INIS)
Lu, Ding; Xie, Bai-Song; Ali Bake, Muhammad; Sang, Hai-Bo; Zhao, Xue-Yan; Wu, Hai-Cheng
2013-01-01
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
Laser plasma interaction in rugby-shaped hohlraums
Masson-Laborde, P.-E.; Philippe, F.; Tassin, V.; Monteil, M.-C.; Gauthier, P.; Casner, A.; Depierreux, S.; Seytor, P.; Teychenne, D.; Loiseau, P.; Freymerie, P.
2014-10-01
Rugby shaped-hohlraum has proven to give high performance compared to a classical similar-diameter cylinder hohlraum. Due to this performance, this hohlraum has been chosen as baseline ignition target for the Laser MegaJoule (LMJ). Many experiments have therefore been performed during the last years on the Omega laser facility in order to study in details the rugby hohlraum. In this talk, we will discuss the interpretation of these experiments from the point of view of the laser plasma instability problem. Experimental comparisons have been done between rugby, cylinder and elliptical shape rugby hohlraums and we will discuss how the geometry differences will affect the evolution of laser plasma instabilities (LPI). The efficiency of laser smoothing techniques on these instabilities will also be discussed as well as gas filling effect. The experimental results will be compared with FCI2 hydroradiative calculations and linear postprocessing with Piranah. Experimental Raman and Brillouin spectrum, from which we can infer the location of the parametric instabilities, will be compared to simulated ones, and will give the possibility to compare LPI between the different hohlraum geometries.
Investigation of electron heating in laser-plasma interaction
Directory of Open Access Journals (Sweden)
A Parvazian
2013-03-01
Full Text Available In this paper, stimulated Raman scattering (SRS and electron heating in laser plasma propagating along the plasma fusion is investigated by particle-in cell simulation. Applying an external magnetic field to plasma, production of whistler waves and electron heating associated with whistler waves in the direction perpendicular to external magnetic field was observed in this simulation. The plasma waves with low phase velocities, generated in backward-SRS and dominateing initially in time and space, accelerated the backward electrons by trapping them. Then these electrons promoted to higher energies by the forward-SRS plasma waves with high phase velocities. This tow-stage electron acceleration is more efficient due to the coexistence of these two instabilities.
Laser-plasma interactions and implosion symmetry in rugby hohlraums
Michel, Pierre; Berger, R. L.; Lasinski, B. F.; Ross, J. S.; Divol, L.; Williams, E. A.; Meeker, D.; Langdon, B. A.; Park, H.; Amendt, P.
2011-10-01
Cross-beam energy transfer is studied in the context of ``rugby''-hohlraum experiments at the Omega laser facility in FY11, in preparation for future NIF experiments. The transfer acts in opposite direction between rugby and cylinder hohlraums due to the different beam pointing geometries and flow patterns. Its interaction with backscatter is also different as both happen in similar regions inside rugby hohlraums. We will analyze the effects of non-linearities and temporal beam smoothing on energy transfer using the code pF3d. Calculations will be compared to experiments at Omega; analysis of future rugby hohlraum experiments on NIF will also be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Laser-plasma interaction physics for shock ignition
Directory of Open Access Journals (Sweden)
Goyon C.
2013-11-01
Full Text Available In the shock ignition scheme, the ICF target is first compressed with a long (nanosecond pulse before creating a convergent shock with a short (∼100 ps pulse to ignite thermonuclear reactions. This short pulse is typically (∼2.1015–1016 W/cm2 above LPI (Laser Plasma Instabilities thresholds. The plasma is in a regime where the electron temperature is expected to be very high (2–4 keV and the laser coupling to the plasma is not well understood. Emulating LPI in the corona requires large and hot plasmas produced by high-energy lasers. We conducted experiments on the LIL (Ligne d'Integration Laser, 10 kJ at 3ω and the LULI2000 (0.4 kJ at 2ω facilities, to approach these conditions and study absorption and LPI produced by a high intensity beam in preformed plasmas. After introducing the main risks associated with the short pulse propagation, we present the latest experiment we conducted on LPI in relevant conditions for shock ignition.
Advanced diagnostics for laser plasma interaction studies and some recent experiments
International Nuclear Information System (INIS)
Chaurasia, S.; Munda, D.S.; Dhareshwar, L.J.
2008-10-01
The complete characterization of Laser plasma interaction studies related to inertial confinement fusion laser and Equation of state (EOS) studies needs many diagnostics to explain the several physical phenomena occurring simultaneously in the laser produced plasma. This involves many on ion emission are important to understand physical phenomena which are responsible for generation of laser plasma as well as its interaction with an intense laser. In this report we describe the development of various x-ray diagnostics which are used in determining temporal, spatial and spectral properties of x-rays radiated from laser produced plasma. Diagnostics which have been used in experiments for investigation of laser-produced plasma as a source of ions are also described. Techniques using an optical streak camera and VISAR which are being used in the Equation of States (EOS) studies of various materials, which are important for material science, astrophysics as well as ICF is described in details. (author)
High density ultrashort relativistic positron beam generation by laser-plasma interaction
Czech Academy of Sciences Publication Activity Database
Gu, Yanjun; Klimo, Ondřej; Weber, Stefan A.; Korn, Georg
2016-01-01
Roč. 18, č. 11 (2016), 1-7, č. článku 113023. ISSN 1367-2630 R&D Projects: GA MŠk EF15_008/0000162 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : radation reaction effect * pair creation * laser-plasma interaction Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.786, year: 2016
Experimental study of laser-plasma interaction physics with short laser wavelength
International Nuclear Information System (INIS)
Labaune, C.; Amiranoff, F.; Fabre, E.; Matthieussent, G.; Rousseaux, C.; Baton, S.
1989-01-01
Many non-linear processes can affect laser-plasma coupling in fusion experiments. The interaction processes of interest involve three or more waves, including the incident electromagnetic wave and various selections of electromagnetic, electrostatic and accoustic waves. Whenever plasma waves are involved (stimulated Raman scattering, two-plasmon decay instability, parametric decay instability and others), energetic electrons are created through the various damping processes of these waves: these energetic electrons in turn deleteriously affect the compression phase in laser fusion experiments through pre-heating of the fuel core. Some parametric processes lead primarily to loss of incident laser energy (stimulated Brillouin scattering) while others, such as filamentation, lead to strongly enhanced local laser intensities through the focusing of part (or all) of the laser beam into filaments of very small dimensions with a concomitant expulsion of the plasma out of these regions. So filamentation destroys the uniformity of energy deposition in the plasma and prevents high compression efficiency of the target. These interaction effects are typically of parametric nature, with their thresholds and growth rates depending critically on plasma scale lengths. Since these scale lengths increase with available laser energy and since millimeter sized plasmas are expected from reactor targets which will be used in direct drive implosion experiments, a good understanding of these processes and their saturation mechanisms becomes imperative. We report here the results on absolute energy measurements and time-resolved spectra of SRS and SBS obtained in various types of plasmas where the major changes were the inhomogeneity scale lengths. (author) 7 refs., 7 figs
Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction
Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.
2016-03-01
In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.
International Nuclear Information System (INIS)
Kato, Susumu; Takahashi, Eiichi; Miura, Eisuke; Owadano, Yoshiro; Nakamura, Tatsufumi; Kato, Tomokazu
2002-01-01
The scaling of hot electron temperature and the spectrum of electron energy by intense laser plasma interactions are reexamined from a viewpoint of the difference in laser wavelength. Laser plasma interaction such as parametric instabilities is usually determined by the Iλ2 scaling, where I and λ is the laser intensity and wavelength, respectively. However, the hot electron temperature is proportional to (ncr/ne0)1/2 [(1 + a 0 2 ) 1/2 - 1] rather than [(1 + a 0 2 ) 1/2 - 1] at the interaction with overdense plasmas, where ne0 is a electron density of overdense plasmas and a0 is a normalized laser intensity
Colaïtis, A.; Chapman, T.; Strozzi, D.; Divol, L.; Michel, P.
2018-03-01
A three-dimensional laser propagation model for computation of laser-plasma interactions is presented. It is focused on indirect drive geometries in inertial confinement fusion and formulated for use at large temporal and spatial scales. A modified tesselation-based estimator and a relaxation scheme are used to estimate the intensity distribution in plasma from geometrical optics rays. Comparisons with reference solutions show that this approach is well-suited to reproduce realistic 3D intensity field distributions of beams smoothed by phase plates. It is shown that the method requires a reduced number of rays compared to traditional rigid-scale intensity estimation. Using this field estimator, we have implemented laser refraction, inverse-bremsstrahlung absorption, and steady-state crossed-beam energy transfer with a linear kinetic model in the numerical code Vampire. Probe beam amplification and laser spot shapes are compared with experimental results and pf3d paraxial simulations. These results are promising for the efficient and accurate computation of laser intensity distributions in holhraums, which is of importance for determining the capsule implosion shape and risks of laser-plasma instabilities such as hot electron generation and backscatter in multi-beam configurations.
Exploring Ultrahigh-Intensity Laser-Plasma Interaction Physics with QED Particle-in-Cell Simulations
Luedtke, S. V.; Yin, L.; Labun, L. A.; Albright, B. J.; Stark, D. J.; Bird, R. F.; Nystrom, W. D.; Hegelich, B. M.
2017-10-01
Next generation high-intensity lasers are reaching intensity regimes where new physics-quantum electrodynamics (QED) corrections to otherwise classical plasma dynamics-becomes important. Modeling laser-plasma interactions in these extreme settings presents a challenge to traditional particle-in-cell (PIC) codes, which either do not have radiation reaction or include only classical radiation reaction. We discuss a semi-classical approach to adding quantum radiation reaction and photon production to the PIC code VPIC. We explore these intensity regimes with VPIC, compare with results from the PIC code PSC, and report on ongoing work to expand the capability of VPIC in these regimes. This work was supported by the U.S. DOE, Los Alamos National Laboratory Science program, LDRD program, NNSA (DE-NA0002008), and AFOSR (FA9550-14-1-0045). HPC resources provided by TACC, XSEDE, and LANL Institutional Computing.
Synchrotron radiation based on laser-plasma interaction in the relativistic range
International Nuclear Information System (INIS)
Albert, F.
2007-12-01
This work illustrates the experimental characterization of a new compact X-ray source: the Betatron X-ray source. It is the first time that collimated hard X-ray source is produced by laser. Through the focusing of an ultra-intense laser radiation (30 TW, 30 fs) on a helium plasma, the ponderomotive force linked to the light intensity gradient expels the plasma electrons forming an accelerating cavity in the wake of the laser plasma. Some electrons trapped in the back of this structure, are accelerated and oscillate to produce X-radiation. This document is composed of 8 chapters. The first one is a presentation of the topic. The second chapter gives an account of the physics behind the laser-plasma interaction in the relativistic range and for ultra-short pulses. The third chapter presents the theoretical characteristics of the Betatron X-ray source. This chapter begins with an analogy with current synchrotron radiation and the radiation emitted by an electron undergoing Betatron oscillations is described in terms of power, spectral intensity and photon flux. The fourth chapter is dedicated to the numerical simulation of the Betatron radiation. The trajectories of the electrons are computed from the equation of motion, taking into account longitudinal and transverse forces. The radiation emission term is then computed from the radiation equation detailed in the previous chapter. The fifth chapter presents the experimental setting to produce Betatron X-rays. The sixth chapter gives the experimental characterization of the source (size, divergence and spectrum) on one hand, and on the other hand studies how source flux and spectra vary when laser and plasma parameters change. The seventh chapter presents experimental methods used to characterize the electrons trajectories in the plasma wiggler. The last chapter draws some perspectives on this source in terms of improvement and uses. (A.C.)
Optical Probing of CO2 Laser-Plasma Interactions at Near Critical Density
Gong, Chao
The interaction of a high-power laser beam with plasma has been explored extensively in the context of laser-driven fusion, plasma-based acceleration of ions and electrons and high energy-density physics. One of the fundamental processes common to all these studies is the penetration of intense light into a dense matter through the hole boring effect and self-induced transparency. Light with a given wavelength lambda will be reflected once the electron density equals the critical electron plasma density nc = 1.1x 1021cm -3 /[lambda(mum)]2. The radiation pressure exerted on the critical density layer is characterized by the ponderomotive force of a focused laser pulse which scales with a laser intensity, I as Ilambda2 Wmum2/cm 2. At Ilambda2 ˜1017 Wmum2/cm2 and above, it becomes possible for the laser pulse not only to steepen the plasma profile but to push the overcritical plasma with ne > nc creating a cavity or a hole in the target. The phenomenon of hole boring, whereby a laser pulse propagates through a reduced density cavity to reach and push the critical density layer, is of importance in fast-ignition fusion because it may allow the laser pulse to deliver its energy closer to the compressed fuel where it can be converted into fast electrons that are needed to ignite a small portion of the fuel. The layer of plasma pushed by the radiation pressure can reflect and accelerate ions via the so called Hole Boring Radiation Pressure Acceleration mechanism. Also the density pile- up in combination with the strong electron heating at the critical density layer can facilitate the formation of a collisionless shock. This shock wave acceleration can produce high energy ion beams with a narrow energy spread. Numerous experiments have been carried out to study dynamics of laser plasma interaction indirectly using solid state targets that are opaque for 1?m laser. However, by using a longer wavelength CO2 laser, lambda = 10.6mum, the critical plasma density is decreased
Transforming the Idler for Use in Laser-Plasma Interaction Experiments
Bucht, S.; Haberberger, D.; Bromage, J.; Froula, D. H.
2016-10-01
A novel optical system has been designed to transform the idler produced in an optical parametric chirped-pulse-amplification (OPCPA) system into a useable high-power pulse for laser-plasma interaction (LPI) experiments. The idler is an existing byproduct created by all OPCPA systems and has similar bandwidth and energy to the signal; with proper preparation it can be another high-fidelity laser pulse at a shifted or unique wavelength from the signal. This preparation is made difficult because of two issues arising in the optical parametric amplifier: (1) angular dispersion and (2) complex chirp reversal. A two-prism angular dispersion compensator and a grism stretcher show promising analytic solutions to these two problems without significantly sacrificing energy or bandwidth. The unusual wavelength range of this beam makes it ideal for unique LPI experiments such as Raman amplification. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Modeling Laser-Plasma Interaction over a Suite of NIF Experiments
Strozzi, D. J.; Berger, R. L.; Jones, O. S.; Chapman, T.; Woods, D. T.; MacLaren, S. A.; Michel, P.; Divol, L.
2017-10-01
We systematically study laser-plasma interaction (LPI) on NIF indirect-drive experiments, namely backscatter and cross-beam energy transfer. LLNL's best practice radiation-hydrodynamic simulation methodology in the Lasnex simulation code is employed without ad-hoc tuning to match experimental data. This entails converged numerical resolution, an improved DCA model for coronal (ne 1 keV) gold opacity, electron heat flux strongly limited to 0.03neTe3 / 2 me- 1 / 2 , and the inline CBET model. The rad-hydro plasma conditions are used for LPI analysis, namely linear instability gains, and the paraxial-envelope code pF3D. Simulated scattered-light spectra are also compared to measurements. We initially focus on shots with low backscatter, so its self-consistent treatment should not be important. These shots have low hohlraum fill density and short laser pulses, and the only significant backscatter is outer-beams Brillouin. Our long-term goals are to understand reflectivity trends to guide target design and develop LPI mitigation strategies. Work performed under auspices of US DoE by LLNL under Contract DE-AC52-07NA27344.
Laser-Plasma Interaction Experiments in Gas-Filled Hohlraums at the LIL Facility
Masson-Laborde, Paul-Edouard; Loiseau, Pascal; Casanova, Michel; Rousseaux, Christophe; Teychenne, Denis; Laffite, Stephane; Huser, Gael
2009-11-01
The first laser-plasma interaction campaign conducted at the LIL facility, using gas-filled hohlraums, ended in spring 09. Two different gas-filled hohlraums have been designed in order to mimic plasma conditions expected along two particular beam paths in ignition hohlraums. The targets consist of 3- or 4-millimeters long, 1 atm neo-pentane gas-filled gold hohlraums. The LIL quadruplet is aligned with the hohlraum's axis and delivers a 6-ns long pulse with 15 kJ at 3φ. Optical smoothing is achieved by longitudinal dispersion and a phase plate giving a near 10^15 W/cm^2 mean intensity on the focal spot at maximum power. Plasma conditions from hydrodynamic calculations allow to calcule SBS and SRS linear gain with the PIRANAH code. The calculated spectra are compared to experimental results. We use the paraxial code HERA to investigate the propagation of the LIL quad. Finally, 1D and 2D PIC simulations based on the plasma conditions of the cavity will be discussed in order to understand experimental SRS spectrum.
The development of laser-plasma interaction program LAP3D on thousands of processors
Directory of Open Access Journals (Sweden)
Xiaoyan Hu
2015-08-01
Full Text Available Modeling laser-plasma interaction (LPI processes in real-size experiments scale is recognized as a challenging task. For explorering the influence of various instabilities in LPI processes, a three-dimensional laser and plasma code (LAP3D has been developed, which includes filamentation, stimulated Brillouin backscattering (SBS, stimulated Raman backscattering (SRS, non-local heat transport and plasmas flow computation modules. In this program, a second-order upwind scheme is applied to solve the plasma equations which are represented by an Euler fluid model. Operator splitting method is used for solving the equations of the light wave propagation, where the Fast Fourier translation (FFT is applied to compute the diffraction operator and the coordinate translations is used to solve the acoustic wave equation. The coupled terms of the different physics processes are computed by the second-order interpolations algorithm. In order to simulate the LPI processes in massively parallel computers well, several parallel techniques are used, such as the coupled parallel algorithm of FFT and fluid numerical computation, the load balance algorithm, and the data transfer algorithm. Now the phenomena of filamentation, SBS and SRS have been studied in low-density plasma successfully with LAP3D. Scalability of the program is demonstrated with a parallel efficiency above 50% on about ten thousand of processors.
Reyes, Jonathan; Shadwick, B. A.
2016-10-01
Modeling the evolution of a short, intense laser pulse propagating through an underdense plasma is of particular interest in the physics of laser-plasma interactions. Numerical models are typically created by first discretizing the equations of motion and then imposing boundary conditions. Using the variational principle of Chen and Sudan, we spatially discretize the Lagrangian density to obtain discrete equations of motion and a discrete energy conservation law which is exactly satisfied regardless of the spatial grid resolution. Modifying the derived equations of motion (e.g., enforcing boundary conditions) generally ruins energy conservation. However, time-dependent terms can be added to the Lagrangian which force the equations of motion to have the desired boundary conditions. Although some foresight is needed to choose these time-dependent terms, this approach provides a mechanism for energy to exit the closed system while allowing the conservation law to account for the loss. An appropriate time discretization scheme is selected based on stability analysis and resolution requirements. We present results using this variational approach in a co-moving coordinate system and compare such results to those using traditional second-order methods. This work was supported by the U. S. Department of Energy under Contract No. DE-SC0008382 and by the National Science Foundation under Contract No. PHY- 1104683.
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.
International Nuclear Information System (INIS)
Wang Naiyan; Shan Yusheng; Ma Weiyi; Yao Gang; Zhou Chuangzhi; Tang Xiuzhang; Tang Zhihong; Gao Junsi; Wang Ganchang.
1994-01-01
A high power KrF laser system is under development in China Institute of Atomic Energy. The system consists of a front end, two-stage KrF amplifiers and two-stage Raman amplifiers, providing 100J, 1ns KrF laser with maximum average power density about 10 14 W/cm 2 on target for laser plasma interaction research. Some important technologies, such as front-end system, Angular Multiplexer, and injection locked oscillator are discussed. (author)
International Nuclear Information System (INIS)
Drouin, M.
2009-11-01
This research thesis proposes a new formulation of the relativistic implicit direct method, based on the weak formulation of the wave equation which is solved by means of a Newton algorithm. The first part of this thesis deals with the properties of the explicit particle-in-cell (PIC) methods: properties and limitations of an explicit PIC code, linear analysis of a numerical plasma, numerical heating phenomenon, interest of a higher order interpolation function, and presentation of two applications in high density relativistic laser-plasma interaction. The second and main part of this report deals with adapting the direct implicit method to laser-plasma interaction: presentation of the state of the art, formulating of the direct implicit method, resolution of the wave equation. The third part concerns various numerical and physical validations of the ELIXIRS code: case of laser wave propagation in vacuum, demonstration of the adjustable damping which is a characteristic of the proposed algorithm, influence of space-time discretization on energy conservation, expansion of a thermal plasma in vacuum, two cases of plasma-beam unsteadiness in relativistic regime, and then a case of the overcritical laser-plasma interaction
Ion Acceleration by Laser Plasma Interaction from Cryogenic Micro Jets - Oral Presentation
Energy Technology Data Exchange (ETDEWEB)
Propp, Adrienne [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-08-25
Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for this type of interaction, capable of producing the highest proton energies possible with today’s laser technologies. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis and investigate new, potentially more efficient mechanisms of ion acceleration, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we acheived a pure proton beam with an indiciation of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the
Skin depth theory explaining anomalous picosecond-terawatt laser plasma interaction
Czech Academy of Sciences Publication Activity Database
Hora, H.; Osman, F.; Höpfl, R.; Badziak, J.; Parys, P.; Wolowski, J.; Woryna, E.; Boody, F.; Jungwirth, Karel; Králiková, Božena; Krása, Josef; Láska, Leoš; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří; Ullschmied, Jiří
2002-01-01
Roč. 52, Suppl. D (2002), s. D349-D359 ISSN 0011-4626. [Plasma Physics and Technology. Prague, 10.06.2002-13.06.2002] R&D Projects: GA ČR GA202/00/1217 Institutional research plan: CEZ:AV0Z1010921 Keywords : laser plasma * ion acceleration Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.311, year: 2002
Kabashin, A. V.; Nikitin, P. I.; Marine, W.; Sentis, M. L.
1998-01-01
An experimental investigation was made of the spatiotemporal structure of the electric fields of a plasma formed as a result of optical breakdown of air near the target surface by radiations of various wavelengths (0.193, 0.53, 1.06, and 10.6 μm), pulse durations (microsecond, nanosecond, and subnanosecond), and intensities (108 — 1013 W cm-2). A study was made of the influence of the target and of nearby objects, and of their materials (conductor, dielectric) on the distribution of the electric fields of the laser plasma, and also on the probe diagnostic system.
Feng, Qingsong; Zheng, Chunyang; Liu, Zhanjun; Xiao, Chengzhuo; Wang, Qing; Cao, Lihua; He, Xiantu
2017-10-01
The anti-Stokes scattering and Stokes scattering in stimulated Brillouin scattering (SBS) cascade have been researched by the Vlasov-Maxwell simulation. In the high-intensity laser-plasmas interaction, the stimulated anti-Stokes Brillouin scattering (SABS) will occur after the second stage SBS rescattering. The mechanism of SABS has been put forward to explain this phenomenon. In the early time of SBS evolution, only the first stage SBS appears, and the total SBS reflectivity comes from the first stage SBS. However, when the high-stage SBS and SABS occur, the SBS reflectivity will appear a 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, the SBS rescattering including the SABS is an important saturation mechanism of SBS, and should be taken into account in the high-intensity laser-plasmas interaction. This research was supported by the National Natural Science Foundation of China (Grant Nos. 11375032, 11575035, 11475030 and 11435011), National Basic Research Program of China (Grant No. 2013CB834101) and Science Challenge Project, No. TZ2016005.
Ivanov, V. V.; Swanson, K. J.; Maximov, A. V.; Betti, R.; Sawada, H.; Mancini, R. C.; Sentoku, Y.; Wiewior, P. P.; Astanovitskiy, A. L.; Nalajala, V.; Chalyy, O.; Dmitriev, O.; Wong, N.
2017-10-01
Experiments were developed for investigation of the laser plasma interaction in the megagauss magnetic field of the 1MA Zebra pulsed power generator coupled with a 50TW laser. These experiments are relevant to astrophysical plasmas, particle and x-ray generation, and isochoric heating in a strong magnetic field. Magnetic fields in loads were measured with Faraday rotation in a glass sample placed near the load. 1-3MG longitudinal and transversal magnetic fields were measured in different loads. Impact of the fast rising magnetic field on metal laser targets was demonstrated. Focusing and targeting laser systems were integrated into the chamber of the Zebra generator. Shots at intensity of >1018 W/cm2 demonstrated collimation of plasma and generation of jets on the front and rear sides of the foil target in the axial magnetic field. Work was supported by the DOE Grant DE-SC0016500 and DOE/NNSA Grant DE-NA 0002075.
Ivanov, V. V.; Maximov, A. V.; Swanson, K. J.; Wong, N. L.; Sarkisov, G. S.; Wiewior, P. P.; Astanovitskiy, A. L.; Covington, A. M.
2018-03-01
An experimental platform for the studying of high-intensity laser plasma interactions in strong magnetic fields has been developed based on the 1 MA Zebra pulsed power generator coupled with the 50-TW Leopard laser. The Zebra generator produces 100-300 T longitudinal and transverse magnetic fields with different types of loads. The Leopard laser creates plasma at an intensity of 1019 W/cm2 in the magnetic field of coil loads. Focusing and targeting systems are integrated in the vacuum chamber of the pulsed power generator and protected from the plasma debris and strong mechanical shock. The first experiments with plasma at laser intensity >2 × 1018 W/cm2 demonstrated collimation of the laser produced plasma in the axial magnetic field strength >100 T.
Jansen, Oliver; Wang, Tao; Toncian, Toma; Stark, David; D'Humieres, Emmanuel; Arefiev, Alexey
2017-10-01
Compact sources of directed high-energy photons are of great interest in current research. Common sources of high-energy photons include synchrotrons and other large and expensive accelerators. Laser-plasma interactions promise sources that are significantly smaller and cheaper than conventional ones. However, they come at the cost of producing either only small number of photons or very undirected ones. A recent study shows, that the use of a plasma channel is able to significantly mitigate these problems while producing a large number of high energy, well collimated photons. We provide an analysis on the physical processes, that lead to the formation of strong magnetic fields responsible for this improvement of emission. Furthermore, we investigate the channel properties in relation to a given laser pulse. This research was supported by the National Science Foundation under Grant No. 1632777. Simulations were performed with the EPOCH code using HPC resources provided by the TACC at the University of Texas.
Scisciò, M; Migliorati, M; Mostacci, A; Palumbo, L; Papaphilippou, Y; Antici, P
2016-01-01
In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupo...
International Nuclear Information System (INIS)
Quesnel, Brice
1998-01-01
This research thesis reports a theoretical and numeric study of the behaviour of two non linear phenomena of the laser-plasma interaction physics in a relativistic regime: the electronic parametric instabilities, and the ponderomotive force. In a first part, the author establishes the three-dimensional scattering relationship of electron parametric instabilities for a circularly polarised wave propagating in a homogeneous and cold plasma, without limitations of wave intensity, nor of plasma density. Results are verified by comparison with those of two-dimensional numerical simulations. The Weibel instability is also briefly studied in relativistic regime. In the second part, the author establishes an expression of the ponderomotive force exerted by an ultra-intense laser pulse in the vacuum about the focus point. A numerical code of integration of equations of motion of an electron in the laser field is used for the different expressions corresponding different approximation degrees. Results are used to interpret a recent experiment, and to critic other theoretical works [fr
International Nuclear Information System (INIS)
1998-03-01
Records of the First JAERI-Kansai International Workshop, which focused on the subject of 'Ultrashort-Pulse Ultrahigh-Power Lasers and Simulation for Laser-Plasma Interactions', are contained in this issue. The First JAERI-Kansai International Workshop was held as Joint ICFA/JAERI-Kansai International Workshop '97 with International Committee for Future Accelerators (ICFA). This report consists of 24 contributed papers. (J.P.N.)
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-03-01
Records of the First JAERI-Kansai International Workshop, which focused on the subject of `Ultrashort-Pulse Ultrahigh-Power Lasers and Simulation for Laser-Plasma Interactions`, are contained in this issue. The First JAERI-Kansai International Workshop was held as Joint ICFA/JAERI-Kansai International Workshop `97 with International Committee for Future Accelerators (ICFA). This report consists of 24 contributed papers. (J.P.N.)
International Nuclear Information System (INIS)
Henry C. Kapteyn
2005-01-01
In this project, we use coherent short-wavelength light generated using high-order harmonic generation as a probe of laser-plasma dynamics and phase transitions on femtosecond time-scales. The interaction of ultrashort laser pulses with materials and plasmas is relevant to stockpile stewardship, to understanding the equation of state of matter at high pressures and temperatures, and to plasma concepts such as the fast-ignitor ICF fusion concept and laser-based particle acceleration. Femtosecond laser technology makes it possible to use a small-scale setup to generate 20fs pulses with average power >10W at multiple kHz repetition rates, that can be focused to intensities in excess of 1017W/cm2. These lasers can be used either to rapidly heat materials to initiate phase transitions, or to create laser plasmas over a wide parameter space. These lasers can also be used to generate fully spatially coherent XUV beams with which to probe these materials and plasma systems. We are in process of implementing imaging studies of plasma hydrodynamics and warm, dense matter. The data will be compared with simulation codes of laser-plasma interactions, making it possible to refine and validate these codes
Calculating the radiation characteristics of accelerated electrons in laser-plasma interactions
International Nuclear Information System (INIS)
Li, X. F.; Yu, Q.; Qu, J. F.; Kong, Q.; Gu, Y. J.; Ma, Y. Y.; Kawata, S.
2016-01-01
In this paper, we studied the characteristics of radiation emitted by electrons accelerated in a laser–plasma interaction by using the Lienard–Wiechert field. In the interaction of a laser pulse with a underdense plasma, electrons are accelerated by two mechanisms: direct laser acceleration (DLA) and laser wakefield acceleration (LWFA). At the beginning of the process, the DLA electrons emit most of the radiation, and the DLA electrons emit a much higher peak photon energy than the LWFA electrons. As the laser–plasma interaction progresses, the LWFA electrons become the major radiation emitter; however, even at this stage, the contribution from DLA electrons is significant, especially to the peak photon energy.
Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods
Energy Technology Data Exchange (ETDEWEB)
Hora, H. (PS-Division, CERN, CH1211 Geneva 23 (Switzerland)); Aydin, M. (Department of Theoretical Physics, University of New South Wales, Kensington 2033 (Australia))
1992-04-15
The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too.
Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods
International Nuclear Information System (INIS)
Hora, H.; Aydin, M.
1992-01-01
The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too
Ensemble of ultra-high intensity attosecond pulses from laser-plasma interaction
International Nuclear Information System (INIS)
Bulanov, S.S.; Maksimchuk, A.; Krushelnick, K.; Popov, K.I.; Bychenkov, V.Yu.; Rozmus, W.
2010-01-01
The efficient generation of intense X-rays and γ-radiation is studied. The scheme is based on the relativistic mirror concept, i.e., a flying thin plasma slab interacts with a counterpropagating laser pulse, reflecting part of it in the form of an intense ultra-short electromagnetic pulse having an up-shifted frequency. In the proposed scheme a series of relativistic mirrors is generated in the interaction of the intense laser with a thin foil target as the pulse tears off and accelerates thin electron layers. A counterpropagating pulse is reflected by these flying layers in the form of an ensemble of ultra-short pulses resulting in a significant energy gain of the reflected radiation due to the momentum transfer from flying layers.
Optical Probing of CO2 Laser-Plasma Interactions at Near Critical Density
Gong, Chao
2015-01-01
The interaction of a high-power laser beam with plasma has been explored extensively in the context of laser-driven fusion, plasma-based acceleration of ions and electrons and high energy-density physics. One of the fundamental processes common to all these studies is the penetration of intense light into a dense matter through the hole boring effect and self-induced transparency. Light with a given wavelength will be reflected once the electron density equals the critical electron plasma d...
Plasma effects in attosecond pulse generation from ultra-relativistic laser-plasma interactions
International Nuclear Information System (INIS)
Boyd, T.J.M.
2010-01-01
Complete text of publication follows. Particle-in-cell simulations were performed to examine the influence of plasma effects on high harmonic spectra from the interaction of ultra-intense p-polarized laser pulses with overdense plasma targets. Furthermore, a theoretical model is proposed to explain the radiation mechanism that leads to attosecond pulse generation in the reflected field. It is shown that plasma harmonic emission affects the spectral characteristics, causing deviations in the harmonic power decay as compared with the so-called universal 8/3-decay. These deviations may occur, in a varying degree, as a consequence of the extent to which the plasma line and its harmonics affect the emission. It is also found a strong correlation of the emitted attosecond pulses with electron density structures within the plasma, responsible to generate intense localised electrostatic fields. A theoretical model based on the excitation of Langmuir waves by the re-entrant Brunel electron beams in the plasma and their electromagnetic interaction with the laser field is proposed to explain the flatter power spectral emission - described by a weaker 5/3 index and observed in numerical simulations - than that of the universal decay.
MULTI-fs - A computer code for laser-plasma interaction in the femtosecond regime
Ramis, R.; Eidmann, K.; Meyer-ter-Vehn, J.; Hüller, S.
2012-03-01
The code MULTI-fs is a numerical tool devoted to the study of the interaction of ultrashort sub-picosecond laser pulses with matter in the intensity range from 10 11 to 10 17 W cm -2. Hydrodynamics is solved in one-dimensional geometry together with laser energy deposition and transport by thermal conduction and radiation. In contrast to long nanosecond pulses, short pulses generate steep gradient plasmas with typical scale lengths in the order of the laser wavelength and smaller. Under these conditions, Maxwell's equations are solved explicitly to obtain the light field. Concerning laser absorption, two different models for the electron-ion collision frequency are implemented to cover the regime of warm dense matter between high-temperature plasma and solid matter and also interaction with short-wave-length (VUV) light. MULTI-fs code is based on the MULTI radiation-hydrodynamic code [R. Ramis, R. Schmalz, J. Meyer-ter-Vehn, Comp. Phys. Comm. 49 (1988) 475] and most of the original features for the treatment of radiation are maintained. Program summaryProgram title: MULTI-fs Catalogue identifier: AEKT_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 49 598 No. of bytes in distributed program, including test data, etc.: 443 771 Distribution format: tar.gz Programming language: FORTRAN Computer: PC (32 bits and 64 bits architecture) Operating system: Linux/Unix RAM: 1.6 MiB Classification: 19.13, 21.2 Subprograms used: Cat Id: AECV_v1_0; Title: MULTI2D; Reference: CPC 180 (2009) 977 Nature of problem: One-dimensional interaction of intense ultrashort (sub-picosecond) and ultraintense (up to 10 17 W cm -2) laser beams with matter. Solution method: The hydrodynamic motion coupled to laser propagation and
Splitter target for controlling magnetic reconnection in relativistic laser plasma interactions
Gu, Y. J.; Bulanov, S. S.; Korn, G.; Bulanov, S. V.
2018-04-01
The utilization of a conical target irradiated by a high power laser is proposed to study fast magnetic reconnection in relativistic plasma interactions. Such target, placed in front of the near critical density gas jet, splits the laser pulse, forming two parallel laser pulses in the 2D case and a donut shaped pulse in the 3D case. The magnetic annihilation and reconnection occur in the density downramp region of the subsequent gas jet. The magnetic field energy is converted into the particle kinetic energy. As a result, a backward accelerated electron beam is obtained as a signature of reconnection. The above mechanisms are demonstrated using particle-in-cell simulations in both 2D and 3D cases. Facilitating the synchronization of two laser beams, the proposed approach can be used in designing the corresponding experiments on studying fundamental problems of relativistic plasma physics.
Laser-Plasma Interactions in Drive Campaign targets on the National Ignition Facility
International Nuclear Information System (INIS)
Hinkel, D E; Callahan, D A; Moody, J D; Amendt, P A; Lasinski, B F; MacGowan, B J; Meeker, D; Michel, P A; Ralph, J; Rosen, M D; Ross, J S; Schneider, M B; Storm, E; Strozzi, D J; Williams, E A
2016-01-01
The Drive campaign [D A Callahan et al., this conference] on the National Ignition Facility (NIF) laser [E. I. Moses, R. N. Boyd, B. A. Remington, C. J. Keane, R. Al-Ayat, Phys. Plasmas 16, 041006 (2009)] has the focused goal of understanding and optimizing the hohlraum for ignition. Both the temperature and symmetry of the radiation drive depend on laser and hohlraum characteristics. The drive temperature depends on the coupling of laser energy to the hohlraum, and the symmetry of the drive depends on beam-to-beam interactions that result in energy transfer [P. A. Michel, S. H. Glenzer, L. Divol, et al, Phys. Plasmas 17, 056305 (2010).] within the hohlraum. To this end, hohlraums are being fielded where shape (rugby vs. cylindrical hohlraums), gas fill composition (neopentane at room temperature vs. cryogenic helium), and gas fill density (increase of ∼ 150%) are independently changed. Cylindrical hohlraums with higher gas fill density show improved inner beam propagation, as should rugby hohlraums, because of the larger radius over the capsule (7 mm vs. 5.75 mm in a cylindrical hohlraum). Energy coupling improves in room temperature neopentane targets, as well as in hohlraums at higher gas fill density. In addition cross-beam energy transfer is being addressed directly by using targets that mock up one end of a hohlraum, but allow observation of the laser beam uniformity after energy transfer. Ideas such as splitting quads into “doublets” by re-pointing the right and left half of quads are also being pursued. LPI results of the Drive campaign will be summarized, and analyses of future directions presented. (paper)
Zulick, Calvin Andrew
The development of short pulse high power lasers has led to interest in laser based particle accelerators. Laser produced plasmas have been shown to support quasi-static TeV/m acceleration gradients which are more than four orders of magnitude stronger than conventional accelerators. These high gradients have the potential to allow compact particle accelerators for active interrogation of nuclear material. In order to better understand this application, several experiments have been conducted at the HERCULES and Lambda Cubed lasers as the Center for Ultrafast Optical Science at the University of Michigan. Electron acceleration and bremsstrahlung generation were studied on the Lambda Cubed laser. The scaling of the intensity, angular, and material dependence of bremsstrahlung radiation from an intense (I > 10 18 W/cm2 ) laser-solid interaction has been characterized at energies between 100 keV and 1 MeV. These were the first high resolution (lambda / d lambda > 100) measurements of bremsstrahlung photons from a relativistic laser plasma interaction. The electron populations and bremsstrahlung temperatures were modeled in the particle-in-cell code OSIRIS and the Monte Carlo code MCNPX and were in good agreement with the experimental results. Proton acceleration was studied on the HERCULES laser. The effect of three dimensional perturbations of electron sheaths on proton acceleration was investigated through the use of foil, grid, and wire targets. Hot electron density, as measured with an imaging Cu Kalpha crystal, increased as the target surface area was reduced and was correlated to an increase in the temperature of the accelerated proton beam. Additionally, experiments at the HERCULES laser facility have produced directional neutron beams with energies up to 16.8 (+/-0.3) MeV using (d,n) and (p,n) reactions. Efficient (d,n) reactions required the selective acceleration of deuterons through the introduction of a deuterated plastic or cryogenically frozen D2O layer
Masson-Laborde, P. E.; Monteil, M. C.; Tassin, V.; Philippe, F.; Gauthier, P.; Casner, A.; Depierreux, S.; Neuville, C.; Villette, B.; Laffite, S.; Seytor, P.; Fremerye, P.; Seka, W.; Teychenné, D.; Debayle, A.; Marion, D.; Loiseau, P.; Casanova, M.
2016-02-01
Gas-filled rugby-shaped hohlraums have demonstrated high performances compared to a classical similar diameter cylinder hohlraum with a nearly 40% increase of x-ray drive, 10% higher measured peak drive temperature, and an increase in neutron production. Experimental comparisons have been done between rugby, cylinder, and elliptical hohlraums. The impact of these geometry differences on the laser plasma instabilities is examined. Using comparisons with hydrodynamic simulations carried out with the code FCI2 and postprocessed by Piranah, we have been able to reproduce the stimulated Raman and Brillouin scattering spectrum of the different beams. Using a methodology based on a statistical analysis for the gain calculations, we show that the behavior of the laser plasma instabilities in rugby hohlraums can be reproduced. The efficiency of laser smoothing techniques to mitigate these instabilities are discussed, and we show that while rugby hohlraums exhibit more laser plasma instabilities than cylinder hohlraum, the latter can be mitigated in the case of an elliptical hohlraum.
Labaune, Christine
2016-10-01
Laser-driven Inertial Confinement Fusion (ICF) relies on the use of high-energy laser beams to compress and ignite a the1monuclear fuel with the ultimate goal of producing energy. Fusion is the holy grail of energy sources-combining abundant fuel with no greenhouse gas emissions, minimal waste products and a scale that can meet mankind's long-term energy demands. The quality and the efficiency of the coupling of the laser beams with the target are an essential step towards the success of laser fusion. A long-te1m program on laser-plasma interaction physics has been pursued to understand the propagation and the coupling of laser pulses in plasmas for a wide range of parameters.
Directory of Open Access Journals (Sweden)
Labaune Christine
2013-11-01
Full Text Available Laser-driven Inertial Confinement Fusion (ICF relies on the use of high-energy laser beams to compress and ignite a thermonuclear fuel with the ultimate goal of producing energy. Fusion is the holy grail of energy sources–combining abundant fuel with no greenhouse gas emissions, minimal waste products and a scale that can meet mankind's long-term energy demands. The quality and the efficiency of the coupling of the laser beams with the target are an essential step towards the success of laser fusion. A long-term program on laser-plasma interaction physics has been pursued to understand the propagation and the coupling of laser pulses in plasmas for a wide range of parameters.
Mobaraki, M.; Jafari, S.
2016-08-01
In this paper, the nonlinear interaction of ultra-high power laser beam with fusion plasma at relativistic regime in the presence of obliquely external magnetic Geld has been studied. Imposing an external magnetic Geld on plasma can modify the density profile of the plasma so that the thermal conductivity of electrons reduces which is considered to be the decrease of the threshold energy for ignition. To achieve the fusion of Hydrogen-Boron (HB) fuel, the block acceleration model of plasma is employed. Energy production by HB isotopes can be of interest, since its reaction does not generate radioactive tritium. By using the inhibit factor in the block model acceleration of plasma and Maxwell's as well as the momentum transfer equations, the electron density distribution and dielectric permittivity of the plasma medium are obtained. Numerical results indicate that with increasing the intensity of the external magnetic field, the oscillation of the laser magnetic field decreases, while the dielectric permittivity increases. Moreover, the amplitude of the electron density becomes highly peaked and the plasma electrons are strongly bunched with increasing the intensity of external magnetic field. Therefore, the magnetized plasma can act as a positive focusing lens to enhance the fusion process. Besides, we find that with increasing θ-angle (from oblique external magnetic field) between 0 and 90°, the dielectric permittivity increases, while for θ between 90° and 180°, the dielectric permittivity decreases with increasing θ.
Bogodaev, N. V.; Zozulya, A. A.; Ivleva, Lyudmila I.; Korshunov, A. S.; Mamaev, A. V.; Polozkov, N. M.
1992-05-01
Most photorefractive crystals suitable for four-wave systems of phase self-conjugation and mutual conjugation have a fairly high level of light-induced scattering (fanning). This may imply that the nonlinearity of a crystal is too strong for optimal operation and a reduction in this nonlinearity would improve the characteristics. This statement is illustrated theoretically and experimentally using the geometry of a loop parametric oscillator as an example.
New basic theory from laser-plasma double layers
International Nuclear Information System (INIS)
Hora, H.; Eliezer, S.; Pease, R.S.; Scharmann, A.; Schwabe, D.
1991-01-01
The study of laser-plasma interaction results in several extensions and new developments of plasma theory including the general formulation of the nonlinear force of laser-plasma interaction, the importance of collisions, quantum collisions and to the discovery of dynamic internal electric fields and double layers in inhomogeneous plasmas. The resulting surface tension in cavitons and at plasma boundaries (due to the faster emitted electrons) results in stabilization against Raleigh-Taylor instability. The same occurs with the degenerate electron gas within the ion lattice of a metal: the electrons try to leave the ion lattice with the Fermi energy until a double layer is being built up. The resulting surface tension immediately agrees with measured values from metals. This can be applied to explain the driving surface force of the Marangoni flow by the flow of the electrons in the electron layer swimming at the metal surface. Hofstadter's charge decay in nuclei from a Debye length is derived and the measured surface energy of nuclei is calculated
Higher order terms of the nonlinear forces in plasmas with collisions at laser interaction
International Nuclear Information System (INIS)
Kentwell, G.W.; Hora, H.
1980-01-01
The evaluation of the general expression of the nonlinear force of laser-plasma interaction showed discrepancies depending on the assumptions of the phase and collisions in the expressions used for E and H. While the first order terms of the derivations are remaining unchanged, new third order terms are found for the case of perpendicular incidence without collisions. With collisions, the additional non-pondermotive terms are derived to be more general than known before. It is then possible to evaluate the forces for oblique incidence with collisions and find an absorption caused force in the plane of the plasma surface. (author)
Energy Technology Data Exchange (ETDEWEB)
Rostampooran, Shabnam; Dorranian, Davoud, E-mail: doran@srbiau.ac.ir [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
2016-08-15
A system of nonlinear one-dimensional equations of the electron hydrodynamics with Maxwell's equations was developed to describe electromagnetic (EM) solitons in plasma with nonthermal electrons. Equation of vector potential was derived in relativistic regime by implementing the multiple scales technique, and their solitonic answers were introduced. The allowed regions for bright and dark electromagnetic solitons were discussed in detail. Roles of number density of nonthermal electrons, temperature of electrons, and frequency of fast participate of vector potential on the Sagdeev potential and properties of EM soliton were investigated. Results show that with increasing the number of nonthermal electrons, the amplitude of vector potential of bright solitons increases. By increasing the number of nonthermal electrons, dark EM solitons may be changed to bright solitons. Increasing the energy of nonthermal electrons leads to generation of high amplitude solitons.
Some nonlinear estimates for lateral propagation of self-generated B fields
International Nuclear Information System (INIS)
Goldman, S.R.
1982-01-01
We present nonlinear estimates which provide plausible guidelines and scalings for the lateral transport of magnetic fields due to laser-plasma interaction in both slab and cylindrical geometries. Limitations of the modelling are also indicated
Inovenkov, I. N.; Echkina, E. Yu.; Nefedov, V. V.; Ponomarenko, L. S.
2017-12-01
In this paper we discuss how a particles-in-cell computation code can be combined with methods of multicriterion optimization (in particular the Pareto optimal solutions of the multicriterion optimization problem) and a hierarchy of computational models approach to create an efficient tool for solving a wide array of problems related to the laser-plasma interaction. In case of the computational experiment the multicriterion optimization can be applied as follows: the researcher defines the objectives of the experiment - some computable scalar values (i.e. high kinetic energy of the ions leaving the domain, least possible number of electrons leaving domain in the given direction, etc). After that the parameters of the experiment which can be varied to achieve these objectives and the constrains on these parameters are chosen (e.g. amplitude and wave-length of the laser radiation, dimensions of the plasma slab(s)). The Pareto optimality of the vector of the parameters can be seen as this: x 0 is Pareto optimal if there exists no vector which would improve some criterion without causing a simultaneous degradation in at least one other criterion. These efficient set of parameter and constrains can be selected based on the preliminary calculations in the simplified models (one or two-dimensional) either analytical or numerical. The multistage computation of the Pareto set radically reduces the number of variants which are to be evaluated to achieve the given accuracy. During the final stage we further improve the results by recomputing some of the optimal variants on the finer grids, with more particles and/or in the frame of a more detailed model. As an example we have considered the ion acceleration caused by interaction of very intense and ultra-short laser pulses with plasmas and have calculated the optimal set of experiment parameters for optimizing number and average energy of high energy ions leaving the domain in the given direction and minimizing the expulsion
Holec, M.; Nikl, J.; Vranic, M.; Weber, S.
2018-04-01
Interaction of high-power lasers with solid targets is in general strongly affected by the limited contrast available. The laser pre-pulse ionizes the target and produces a pre-plasma which can strongly modify the interaction of the main part of the laser pulse with the target. This is of particular importance for future experiments which will use laser intensities above 1021 W cm-2 and which are subject to the limited contrast. As a consequence the main part of the laser pulse will be modified while traversing the pre-plasma, interacting with it partially. A further complication arises from the fact that the interaction of a high-power pre-pulse with solid targets very often takes place under nonlocal transport conditions, i.e. the characteristic mean-free-path of the particles and photons is larger than the characteristic scale-lengths of density and temperature. The classical diffusion treatment of radiation and heat transport in the hydrodynamic model is then insufficient for the description of the pre-pulse physics. These phenomena also strongly modify the formation of the pre-plasma which in turn affects the propagation of the main laser pulse. In this paper nonlocal radiation-hydrodynamic simulations are carried out and serve as input for subsequent kinetic simulations of ultra-high intensity laser pulses interacting with the plasma in the ultra-relativistic regime. It is shown that the results of the kinetic simulations differ considerably whether a diffusive or nonlocal transport is used for the radiation-hydrodynamic simulations.
Energy Technology Data Exchange (ETDEWEB)
Scott, R. H. H.; Norreys, P. A. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Perez, F.; Baton, S. D. [LULI, Ecole Polytechnique, UMR 7605, CNRS/CEA/UPMC, Route de Saclay, 91128 Palaiseau (France); Santos, J. J.; Nicolai, Ph.; Hulin, S. [Univ. Bordeaux/CNRS/CEA, CELIA, UMR 5107, 33405 Talence (France); Ridgers, C. P. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Davies, J. R. [GoLP, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Lancaster, K. L.; Trines, R. M. G. M. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Bell, A. R.; Tzoufras, M. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Rose, S. J. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom)
2012-05-15
A systematic experimental and computational investigation of the effects of three well characterized density scalelengths on fast electron energy transport in ultra-intense laser-solid interactions has been performed. Experimental evidence is presented which shows that, when the density scalelength is sufficiently large, the fast electron beam entering the solid-density plasma is best described by two distinct populations: those accelerated within the coronal plasma (the fast electron pre-beam) and those accelerated near or at the critical density surface (the fast electron main-beam). The former has considerably lower divergence and higher temperature than that of the main-beam with a half-angle of {approx}20 Degree-Sign . It contains up to 30% of the total fast electron energy absorbed into the target. The number, kinetic energy, and total energy of the fast electrons in the pre-beam are increased by an increase in density scalelength. With larger density scalelengths, the fast electrons heat a smaller cross sectional area of the target, causing the thinnest targets to reach significantly higher rear surface temperatures. Modelling indicates that the enhanced fast electron pre-beam associated with the large density scalelength interaction generates a magnetic field within the target of sufficient magnitude to partially collimate the subsequent, more divergent, fast electron main-beam.
Chen, Yu-Hsin
2012-10-01
When exceeding the critical power Pcr, an intense laser pulse propagating in a gas collapses into one or multiple ``filaments,'' which can extend meters in length with weakly ionized plasma and local intensity ˜ 10^13 W/cm^2 radially confined in a diameter of < 100 μm [1]. While it has been generally accepted the nonlinear self-focusing of the laser pulse leading to beam collapse is stabilized by plasma generation [2], neither the field-induced nonlinearity nor the plasma generation had been directly measured. This uncertainty has given rise to recent controversy about whether plasma generation does indeed counteract the positive nonlinearity [3, 4]. For even a basic understanding of femtosecond filamentation and for applications, the focusing and defocusing mechanisms---nonlinear self-focusing and ionization---must be understood. By employing a single-shot, time-resolved technique based on spectral interferometry [5] to study the constituents of air, it is found that the rotational responses in O2 and N2 are the dominant nonlinear effect in filamentary propagation when the laser pulse duration is longer than ˜ 100fs. Furthermore, we find that the instantaneous nonlinearity scales linearly up to the ionization threshold [6], eliminating any possibility of an ionization-free negative stabilization [3] of filamentation. This is confirmed by space-resolved electron density measurements in meter-long filaments produced with different pulse durations, using optical interferometry with a grazing-incidence, ps-delayed probe [7].[4pt] [1] A. Braun et al., Opt. Lett. 20, 73 (1995).[0pt] [2] A. Couairon and A. Mysyrowicz, Phys. Rep. 441, 47 (2007).[0pt] [3] V. Loriot et al., Opt. Express 17, 13429 (2009).[0pt] [4] P. B'ejot et al., Phys. Rev. Lett. 104, 103903 (2010).[0pt] [5] Y.-H. Chen et al., Opt. Express 15, 7458 (2007); Opt. Express 15, 11341 (2007).[0pt] [6] J. K. Wahlstrand et al., Phys. Rev. Lett. 107, 103901 (2011).[0pt] [7] Y.-H. Chen et al., Phys. Rev. Lett
The application of laser plasma in ophthalmology
International Nuclear Information System (INIS)
He Yujiang; Luo Le; Sun Yabing
2000-01-01
The production and development of laser plasma are introduced, and the contribution of laser biomedicine and laser plasma technology to ophthalmology is analyzed. The latest three progresses (laser photocoagulation, photo-refractive keratotomy and laser iridectomy) of laser plasma applications in ophthalmology are presented
Controlling Laser Plasma Instabilities Using Temporal Bandwidth
Tsung, Frank; Weaver, J.; Lehmberg, R.
2016-10-01
We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temporal bandwidth under conditions relevant to current and future experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth (where the inverse bandwidth is comparable with the linear growth time), the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using beam smoothing techniques such as ISI). We will quantify these effects and investigate higher dimensional effects such as laser speckles. This work is supported by DOE and NRL.
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.
Afeyan, Bedros; Hüller, Stefan; Montgomery, David; Moody, John; Froula, Dustin; Hammer, James; Jones, Oggie; Amendt, Peter
2014-10-01
In mid-Z and high-Z plasmas, it is possible to control crossed bean energy transfer (CBET) and subsequently occurring single or multiple beam instabilities such as Stimulated Raman Scattering (SRS) by novel means. These new techniques are inoperative when the ion acoustic waves are in their strong damping limit, such as occurs in low Z plasmas with comparable electron and ion temperatures. For mid-Z plasmas, such as Z = 10, and near the Mach 1 surface, the strong coupling regime (SCR) can be exploited for LPI mitigation. While at higher Z values, it is thermal filamentation in conjunction with nonlocal heat transport that are useful to exploit. In both these settings, the strategy is to induce laser hot spot intensity dependent, and thus spatially dependent, frequency shifts to the ion acoustic waves in the transient response of wave-wave interactions. The latter is achieved by the on-off nature of spike trains of uneven duration and delay, STUD pulses. The least taxing use of STUD pulses is to modulate the beams at the 10 ps time scale and to choose which crossing beams are overlapping in time and which are not. Work supported by a grant from the DOE NNSA-OFES joint program on HEDP
Nonlinear electromagnetic interactions in thermal QED
International Nuclear Information System (INIS)
Brandt, F.T.; Frenkel, J.
1995-01-01
We examine the behavior of the nonlinear interactions between electromagnetic fields at high temperature. It is shown that, in general, the ln(T) dependence on the temperature of the Green functions is simply related to their UV behavior at zero temperature. We argue that the effective action describing the nonlinear thermal electromagnetic interactions has a finite limit as T→∞. This thermal action approaches, in the long wavelength limit, the negative of the corresponding zero-temperature action
Laser-plasma based electron acceleration studies planned at CAT, Indore
International Nuclear Information System (INIS)
Naik, P.A.; Gupta, P.D.
2005-01-01
The Laser Plasma Division at the Centre for Advanced Technology is engaged in a variety of R and D activities on laser-plasma interaction with special emphasis on laser-matter interaction at ultra-high intensities. An important aspect of our future work is studies in laser-plasma based acceleration using an elaborate infrastructural set-up of ultra-fast laser and plasma diagnostic systems and recently acquired 10 TW, 50 fs Ti: Sapphire laser system. This paper presents outline of the planned studies in this field. (author)
Soil-structure interaction including nonlinear soil
Gicev, Vlado
2008-01-01
There are two types of models of soil-structure system depending upon the rigidity of foundation: models with rigid and models with flexible foundation. Main features of the soil-structure interaction phenomenon: -wave scattering, -radiation damping, -reduction of the system frequencies. In this presentation, the influence of interaction on the development of nonlinear zones in the soil is studied.
Tunable Resonators for Nonlinear Modal Interactions
Ramini, Abdallah
2016-10-04
Understanding the various mechanisms of nonlinear mode coupling in micro and nano resonators has become an imminent necessity for their successful implementation in practical applications. However, consistent, repeatable, and flexible experimental procedures to produce nonlinear mode coupling are lacking, and hence research into well-controlled experimental conditions is crucial. Here, we demonstrate well-controlled and repeatable experiments to study nonlinear mode coupling among micro and nano beam resonators. Such experimental approach can be applied to other micro and nano structures to help study their nonlinear interactions and exploit them for higher sensitive and less noisy responses. Using electrothermal tuning and electrostatic excitation, we demonstrate three different kinds of nonlinear interactions among the first and third bending modes of vibrations of slightly curved beams (arches): two-one internal resonance, three-one internal resonance, and mode veering (near crossing). The experimental procedure is repeatable, highly flexible, do not require special or precise fabrication, and is conducted in air and at room temperature. This approach can be applied to other micro and nano structures, which come naturally curved due to fabrication imperfections, such as CNTs, and hence lays the foundation to deeply investigate the nonlinear mode coupling in these structures in a consistent way.
Principles of laser-plasma accelerators; Les accelerateurs de particules laser-plasma
Energy Technology Data Exchange (ETDEWEB)
Malka, V. [Ecole polytechnique, Lab. d' Optique Appliquee, ENSTA, CNRS, 91 - Palaiseau (France); Mora, P. [Ecole polytechnique, Centre de physique Theorique, CNRS, 91 - Palaiseau (France)
2009-03-15
The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain in which extremely high electric and magnetic fields are generated. Thanks to these tremendous fields, that only plasma can support and sustain, new and compact approaches for producing energetic particle beams have been recently achieved (for example the bubble regime and the colliding laser pulses scheme). The incredible progress of these laser-plasma accelerators has allowed physicists to produce high quality beams of energetic radiation and particles. These beams have interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine (radiotherapy, proton therapy, imaging), radiation biology (short-time-scale), chemistry (radiolysis), physics and material science (radiography, electron and photon diffraction), security (material inspection), and of course accelerator science. Stimulated by the advent of compact and powerful lasers, with moderate costs and high repetition rate, this research field has witnessed considerable growth in the past few years, and the promises of laser-plasma accelerators are in tremendous progress. The recent years in particular have seen spectacular progress in the acceleration of electrons and of ions, both in terms of energy and in terms of quality of the beams. (authors)
Albert, Felicie
2017-10-01
Bright sources of x-rays, such as synchrotrons and x-ray free electron lasers (XFEL) are transformational tools for many fields of science. They are used for biology, material science, medicine, or industry. Such sources rely on conventional particle accelerators, where electrons are accelerated to gigaelectronvolts (GeV) energies. The accelerated particles are wiggled in magnetic structures to emit x-ray radiation that is commonly used for molecular crystallography, fluorescence studies, chemical analysis, medical imaging, and many other applications. One of the drawbacks of these machines is their size and cost, because electric field gradients are limited to about 100 V/M in conventional accelerators. Particle acceleration in laser-driven plasmas is an alternative to generate x-rays via betatron emission, Compton scattering, or bremsstrahlung. A plasma can sustain electrical fields many orders of magnitude higher than that in conventional radiofrequency accelerator structures. When short, intense laser pulses are focused into a gas, it produces electron plasma waves in which electrons can be trapped and accelerated to GeV energies. X-ray sources, driven by electrons from laser-wakefield acceleration, have unique properties that are analogous to synchrotron radiation, with a 1000-fold shorter pulse. An important use of x-rays from laser plasma accelerators is in High Energy Density (HED) science, which requires laser and XFEL facilities to create in the laboratory extreme conditions of temperatures and pressures that are usually found in the interiors of stars and planets. To diagnose such extreme states of matter, the development of efficient, versatile and fast (sub-picosecond scale) x-ray probes has become essential. In these experiments, x-ray photons can pass through dense material, and absorption of the x-rays can be directly measured, via spectroscopy or imaging, to inform scientists about the temperature and density of the targets being studied. Performed
Nonlinear theory of electroelastic and magnetoelastic interactions
Dorfmann, Luis
2014-01-01
This book provides a unified theory of nonlinear electro-magnetomechanical interactions of soft materials capable of large elastic deformations. The authors include an overview of the basic principles of the classical theory of electromagnetism from the fundamental notions of point charges and magnetic dipoles through to distributions of charge and current in a non-deformable continuum, time-dependent electromagnetic fields and Maxwell’s equations. They summarize the basic ingredients of continuum mechanics that are required to account for the deformability of material and present nonlinear constitutive frameworks for electroelastic and magnetoelastic interactions in a highly deformable material. The equations contained in the book are used to formulate and solve a variety of representative boundary-value problems for both nonlinear electroelasticity and magnetoelasticity.
Nonlinear dynamics of interacting populations
Bazykin, Alexander D
1998-01-01
This book contains a systematic study of ecological communities of two or three interacting populations. Starting from the Lotka-Volterra system, various regulating factors are considered, such as rates of birth and death, predation and competition. The different factors can have a stabilizing or a destabilizing effect on the community, and their interplay leads to increasingly complicated behavior. Studying and understanding this path to greater dynamical complexity of ecological systems constitutes the backbone of this book. On the mathematical side, the tool of choice is the qualitative the
Study of the combined laser-plasma effect on metals
Gabdrakhmanov, AT; Galiakbarov, AT; Israphilov, I. H.
2017-09-01
Interaction processes of laser radiation with the metal surface layer during laser effect, and the main factors influencing the absorption capacity of the metal with a surface processing by a laser beam are considered. The method is proposed for increasing the absorption capacity of laser radiation by plasmatron pre-heating of the material. The results of the combined laser-plasma effect are presented.
Nonlinear interactions of counter-travelling waves
International Nuclear Information System (INIS)
Matsuuchi, Kazuo
1980-01-01
Nonlinear interactions between two waves travelling in opposite directions are investigated. When a nonlinear Klein-Gordon equation is adopted as a model equation, it is shown that such a wave system is governed by a simple set of equations for their complex amplitudes. Steady progressive waves governed by this set are investigated for various cases classified according to the signs of the coefficients. It is then found that one wave travelling in one direction appears from a certain point and the other travelling in the opposite direction has a constant amplitude from that point. This phenomenon may be regarded as a sort of reflection in spite of no rigid boundary. (author)
Non-linear soil-structure interaction
International Nuclear Information System (INIS)
Wolf, J.P.
1984-01-01
The basic equation of motion to analyse the interaction of a non-linear structure and an irregular soil with the linear unbounded soil is formulated in the time domain. The contribution of the unbounded soil involves convolution integrals of the dynamic-stiffness coefficients in the time domain and the corresponding motions. As another possibility, a flexibility formulation fot the contribution of the unbounded soil using the dynamic-flexibility coefficients in the time domain, together with the direct-stiffness method for the structure and the irregular soil can be applied. As an example of a non-linear soil-structure-interaction analysis, the partial uplift of the basemat of a structure is examined. (Author) [pt
Non-Linear Dynamics and Fundamental Interactions
Khanna, Faqir
2006-01-01
The book is directed to researchers and graduate students pursuing an advanced degree. It provides details of techniques directed towards solving problems in non-linear dynamics and chos that are, in general, not amenable to a perturbative treatment. The consideration of fundamental interactions is a prime example where non-perturbative techniques are needed. Extension of these techniques to finite temperature problems is considered. At present these ideas are primarily used in a perturbative context. However, non-perturbative techniques have been considered in some specific cases. Experts in the field on non-linear dynamics and chaos and fundamental interactions elaborate the techniques and provide a critical look at the present status and explore future directions that may be fruitful. The text of the main talks will be very useful to young graduate students who are starting their studies in these areas.
Absorption of turbulent laser plasma radiation
International Nuclear Information System (INIS)
Silin, V.P.
1979-02-01
Some theoretical results relating to the interaction of high-power laser radiation with a plasma are presented including the development of a theory of parametric instabilities in an inhomogeneous laser plasma which shows that the size of the spatial region in which the turbulent state develops is comparable with the characteristic dimension of a several-fold fluctuation in the plasma density close to its critical value. The conditions are identified under which parametric turbulence gives an anomalous effective collision frequency substantially greater than the normal electron-ion collision frequency. Even during the build-up of strong parametric turbulence, conditions are found for the development of anomalous dissipation which results in heating of the bulk of the electrons. Under opposite conditions, the dynamic behaviour due to the influence of the ponderomotive forces associated with the p component of the radiation field shows that under slow plasma flow conditions, a considerable proportion of the laser energy absorbed by the plasma is transferred to the fast electrons. Suppression of the Cherenkov mechanism for generation of the fast electron component is observed on transition to fast plasma flow conditions. (author)
Combined impact features for laser plasma generation
International Nuclear Information System (INIS)
Loktionov, E; Protasov, Yu; Telekh, V
2017-01-01
Laser-induced plasma has been considered for multiple applications by the moment, and its characteristics strongly depend on laser radiation parameters. Reaching demanded values for the latter might be rather costly, but, in certain cases, similar or even better results could be reached in case of additional impact (optical, electric, magnetic, corpuscular, mechanical etc.). Combined impact effects are mainly based on target properties or interaction mechanism change, and found to decrease plasma generation thresholds by orders of magnitude, improve energy efficiency significantly, and also broaden the range of plasma parameters. Application area, efficiency and optimal regimes for laser plasma generation at such combined impact have been considered. Analysis based on published data and own experiments was performed for both target material and induced plasma flows. Criterial parameters have been suggested to characterize both combined impact and response to it. The data on plasma generation thresholds, controlled parameters, working media supply systems and recovery rate of droplets are very important for technology setups, including those for material modification. (paper)
Nonlinear interaction model of subsonic jet noise.
Sandham, Neil D; Salgado, Adriana M
2008-08-13
Noise generation in a subsonic round jet is studied by a simplified model, in which nonlinear interactions of spatially evolving instability modes lead to the radiation of sound. The spatial mode evolution is computed using linear parabolized stability equations. Nonlinear interactions are found on a mode-by-mode basis and the sound radiation characteristics are determined by solution of the Lilley-Goldstein equation. Since mode interactions are computed explicitly, it is possible to find their relative importance for sound radiation. The method is applied to a single stream jet for which experimental data are available. The model gives Strouhal numbers of 0.45 for the most amplified waves in the jet and 0.19 for the dominant sound radiation. While in near field axisymmetric and the first azimuthal modes are both important, far-field sound is predominantly axisymmetric. These results are in close correspondence with experiment, suggesting that the simplified model is capturing at least some of the important mechanisms of subsonic jet noise.
Nonlinear wave interactions of kinetic sound waves
Directory of Open Access Journals (Sweden)
G. Brodin
2015-08-01
Full Text Available We reconsider the nonlinear resonant interaction between three electrostatic waves in a magnetized plasma. The general coupling coefficients derived from kinetic theory are reduced here to the low-frequency limit. The main contribution to the coupling coefficient we find in this way agrees with the coefficient recently presented in Annales Geophysicae. But we also deduce another contribution which sometimes can be important, and which qualitatively agrees with that of an even more recent paper. We have thus demonstrated how results derived from fluid theory can be improved and generalized by means of kinetic theory. Possible extensions of our results are outlined.
Nonlinear interactions in magnetised piezoelectric semiconductor plasmas
International Nuclear Information System (INIS)
Sharma, Giriraj; Ghosh, S.
2000-01-01
Based on hydrodynamics model of plasmas an analytical investigation of frequency modulational interaction between copropagating high frequency pump and acoustic mode and consequent amplification (steady-state and transient) of the modulated waves is carried out in a magnetised piezoelectric semiconductor medium. The phenomenon of modulation amplification is treated as four wave interaction process involving cubic nonlinearity of the medium. Gain constants, threshold-pump intensities and optimum-pulse duration for the onset of modulational instabilities are estimated. The analysis has been performed in non-dispersive regime of the acoustic mode, which is one of the preconditions for achieving an appreciable initial steady-state growth of the modulated signal wave. It is found that the transient gain diminishes very rapidly if one chooses the pump pulse duration beyond the maximum gain point. Moreover, the desired value of the gain can be obtained by adjusting intensity and pulse duration of the pump and doping concentration of the medium concerned. (author)
PRECISE CHARGE MEASUREMENT FOR LASER PLASMA ACCELERATORS
Energy Technology Data Exchange (ETDEWEB)
Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; Tilborg, Jeroen van; Osterhoff, Jens; Donahue, Rich; Rodgers, David; Smith, Alan; Byrne, Warren; Leemans, Wim
2011-07-19
Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based measurement, and integrating current transformer. The diagnostics agreed within {+-}8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.
Precise Charge Measurement For Laser Plasma Accelerators
International Nuclear Information System (INIS)
Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; van Tilborg, Jeroen; Osterhoff, Jens; Donahue, Rich; Rodgers, David; Smith, Alan; Byrne, Warren; Leemans, Wim
2011-01-01
Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based measurement, and integrating current transformer. The diagnostics agreed within ±8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.
En Route: next-generation laser-plasma-based electron accelerators
International Nuclear Information System (INIS)
Hidding, Bernhard
2008-05-01
Accelerating electrons to relativistic energies is of fundamental interest, especially in particle physics. Today's accelerator technology, however, is limited by the maximum electric fields which can be created. This thesis presents results on various mechanisms aiming at exploiting the fields in focussed laser pulses and plasma waves for electron acceleration, which can be orders of magnitude higher than with conventional accelerators. With relativistic, underdense laser-plasma-interaction, quasimonoenergetic electron bunches with energies up to ∼50 MeV and normalized emittances of the order of 5mmmrad have been generated. This was achieved by focussing the ∼80 fs, 1 J pulses of the JETI-laser at the FSU Jena to intensities of several 10 19 W=cm 2 into gas jets. The experimental observations could be explained via ''bubble acceleration'', which is based on self-injection and acceleration of electrons in a highly nonlinear breaking plasma wave. For the rst time, this bubble acceleration was achieved explicitly in the self-modulated laser wakefield regime (SMLWFA). This quasimonoenergetic SMLWFA-regime stands out by relaxing dramatically the requirements on the driving laser pulse necessary to trigger bubble acceleration. This is due to self-modulation of the laser pulse in high-density gas jets, leading to ultrashort laser pulse fragments capable of initiating bubble acceleration. Electron bunches with durations < or similar 5 fs can thus be created, which is at least an order of magnitude shorter than with conventional accelerator technology. In addition, more than one laser pulse fragment can be powerful enough to drive a bubble. Distinct double peaks have been observed in the electron spectra, indicating that two quasimonoenergetic electron bunches separated by only few tens of fs have formed. This is backed up by PIC-Simulations (Particle-in-Cell). These results underline the feasibility of the construction of small table-top accelerators, while at the
Coulomb implosion mechanism of negative ion acceleration in laser plasmas
Energy Technology Data Exchange (ETDEWEB)
Nakamura, T., E-mail: nakamura.tatsufumi@jaea.go.j [Kansai Photon Science Institute (JAEA), 8-1 Umemidai, Kizugawa, Kyoto 619-0215 (Japan); Fukuda, Y.; Yogo, A.; Tampo, M.; Kando, M.; Hayashi, Y.; Kameshima, T.; Pirozhkov, A.S.; Esirkepov, T.Zh.; Pikuz, T.A.; Faenov, A.Ya.; Daido, H.; Bulanov, S.V. [Kansai Photon Science Institute (JAEA), 8-1 Umemidai, Kizugawa, Kyoto 619-0215 (Japan)
2009-07-06
Coulomb implosion mechanism of the negatively charged ion acceleration in laser plasmas is proposed. When a cluster target is irradiated by an intense laser pulse and the Coulomb explosion of positively charged ions occurs, the negative ions are accelerated inward. The maximum energy of negative ions is several times lower than that of positive ions. We present the theoretical description and Particle-in-Cell simulation results of the Coulomb implosion mechanism, and show the evidence of the negative ion acceleration in the experiments on the high intensity laser pulse interaction with the cluster targets.
Nonlinear acoustic interactions in superfluid helium
International Nuclear Information System (INIS)
Wright, D.R.
1989-01-01
Studies of nonlinear acoustic interactions in superfluid helium at temperatures below 0.2 degree K have culminated in the construction of an all-acoustic parametric amplifier at gigahertz frequencies. This amplifier represents the shortest wavelength parametric amplifier ever made, with signal wavelengths shorter than 1000 angstrom and pump wavelengths shorter than 600 angstrom. Begun as part of a program to extend the frequency range, and hence improve the resolution, of the scanning acoustic microscope while maintaining an adequate signal-to-noise ratio, the early work on nonlinearity concentrated on the very high power densities achieved at the focus of an acoustic lens. In a pressure range where the dispersion forbids three-phonon processes, indirect evidence of four-phonon mixing is observed. In the parametric amplifier experiment, plane waves are mixed at a predefined angle in the superfluid helium. Two gain regimes are observed. The first regime is a four-phonon collinear process, in which gain on the signal is created by the second-harmonic of the pump. The second regime is a noncollinear phase-matched process, in which the signal phonon stimulates decay of the pump phonon to create gain at the signal frequency
Studies of intense-laser plasma instabilities
Czech Academy of Sciences Publication Activity Database
Láska, Leoš; Krása, Josef; Badziak, J.; Jungwirth, Karel; Krouský, Eduard; Margarone, Daniele; Parys, P.
2013-01-01
Roč. 272, May (2013), 94-98 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528; GA AV ČR IAA100100715 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser plasma instabilities * self-generated magnetic field * longitudinal structure of the expanding plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.538, year: 2013
Energy Technology Data Exchange (ETDEWEB)
Katsouleas, Thomas C. [Duke Univ., Durham, NC (United States). Dept. of Electrical and Computer Engineering; Sahai, Aakash A. [Imperial College, London (United Kingdom). Dept. of Physics
2016-08-08
There were two goals for this funded project: 1. Studies of plasma wakefields for high repetition-rate plasma collider, and 2. Theoretical study of laser-plasma proton and ion acceleration. For goal 1, an analytical model was developed to determine the ion-motion resulting from the interaction of non-linear “blow-out” wakefields excited by beam-plasma and laser-plasma interactions. This is key to understanding the state of the plasma at timescales of 1 picosecond to a few 10s of picoseconds behind the driver-energy pulse. More information can be found in the document. For goal 2, we analytically and computationally analyzed the longitudinal instabilities of the laser-plasma interactions at the critical layer. Specifically, the process of “Doppler-shifted Ponderomotive bunching” is significant to eliminate the very high-energy spread and understand the importance of chirping the laser pulse frequency. We intend to publish the results of the mixing process in 2-D. We intend to publish Chirp-induced transparency. More information can be found in the document.
Nonlinear optical interactions in silicon waveguides
Directory of Open Access Journals (Sweden)
Kuyken B.
2017-03-01
Full Text Available The strong nonlinear response of silicon photonic nanowire waveguides allows for the integration of nonlinear optical functions on a chip. However, the detrimental nonlinear optical absorption in silicon at telecom wavelengths limits the efficiency of many such experiments. In this review, several approaches are proposed and demonstrated to overcome this fundamental issue. By using the proposed methods, we demonstrate amongst others supercontinuum generation, frequency comb generation, a parametric optical amplifier, and a parametric optical oscillator.
Nonlinear interaction of waves in an inhomogeneous plasma
International Nuclear Information System (INIS)
Istomin, Ya.N.
1988-01-01
Nonlinear wave processes in a weakly inhomogeneous plasma are considered. A quasilinear equation is derived which takes into account the effect of the waves on resonance particles, provided that the inhomogeneity appreciably affects the nature of the resonance interaction. Three-wave interaction is investigated under the same conditions. As an example, the nonlinear interaction in a relativistic plasma moving along a strong curvilinear magnetic field is considered
Energy Technology Data Exchange (ETDEWEB)
Hidding, Bernhard
2008-05-15
Accelerating electrons to relativistic energies is of fundamental interest, especially in particle physics. Today's accelerator technology, however, is limited by the maximum electric fields which can be created. This thesis presents results on various mechanisms aiming at exploiting the fields in focussed laser pulses and plasma waves for electron acceleration, which can be orders of magnitude higher than with conventional accelerators. With relativistic, underdense laser-plasma-interaction, quasimonoenergetic electron bunches with energies up to {approx}50 MeV and normalized emittances of the order of 5mmmrad have been generated. This was achieved by focussing the {approx}80 fs, 1 J pulses of the JETI-laser at the FSU Jena to intensities of several 10{sup 19}W=cm{sup 2} into gas jets. The experimental observations could be explained via 'bubble acceleration', which is based on self-injection and acceleration of electrons in a highly nonlinear breaking plasma wave. For the rst time, this bubble acceleration was achieved explicitly in the self-modulated laser wakefield regime (SMLWFA). This quasimonoenergetic SMLWFA-regime stands out by relaxing dramatically the requirements on the driving laser pulse necessary to trigger bubble acceleration. This is due to self-modulation of the laser pulse in high-density gas jets, leading to ultrashort laser pulse fragments capable of initiating bubble acceleration. Electron bunches with durations
Nonlinear interaction of ultraintense laser pulse with relativistic thin ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 87; Issue 5. Nonlinear interaction of ultraintense laser pulse ... In the RPD regime, the plasma foil is pushed by ultraintense laser pulse when the radiation cannot propagate through the foil, while the electron and ion layers move together. The nonlinear character of ...
Collaborative Research: Tomographic imaging of laser-plasma structures
Energy Technology Data Exchange (ETDEWEB)
Downer, Michael [University of Texas at Austin
2018-01-18
The interaction of intense short laser pulses with ionized gases, or plasmas, underlies many applications such as acceleration of elementary particles, production of energy by laser fusion, generation of x-ray and far-infrared “terahertz” pulses for medical and materials probing, remote sensing of explosives and pollutants, and generation of guide stars. Such laser-plasma interactions create tiny electron density structures (analogous to the wake behind a boat) inside the plasma in the shape of waves, bubbles and filaments that move at the speed of light, and evolve as they propagate. Prior to recent work by the PI of this proposal, detailed knowledge of such structures came exclusively from intensive computer simulations. Now “snapshots” of these elusive, light-velocity structures can be taken in the laboratory using dynamic variant of holography, the technique used to produce ID cards and DVDs, and dynamic variant of tomography, the technique used in medicine to image internal bodily organs. These fast visualization techniques are important for understanding, improving and scaling the above-mentioned applications of laser-plasma interactions. In this project, we accomplished three things: 1) We took holographic pictures of a laser-driven plasma-wave in the act of accelerating electrons to high energy, and used computer simulations to understand the pictures. 2) Using results from this experiment to optimize the performance of the accelerator, and the brightness of x-rays that it emits. These x-rays will be useful for medical and materials science applications. 3) We made technical improvements to the holographic technique that enables us to see finer details in the recorded pictures. Four refereed journal papers were published, and two students earned PhDs and moved on to scientific careers in US National Laboratories based on their work under this project.
Ignition target and laser-plasma instabilities
International Nuclear Information System (INIS)
Laffite, S.; Loiseau, P.
2010-01-01
For the first time indirect drive ignition targets have been designed with the constraint of limiting laser-plasma instabilities. The amplification of these instabilities is directly proportional to the luminous flux density, it means to the sizes of the focal spots too. This study shows that increasing the sizes of the focal spots does not reduce linear amplification gains in a proportional way because the global optimization of the target implies changes in hydrodynamical conditions that in turn have an impact on the value of the amplification gain. The design of the target is a 2-step approach: the first step aims at assuring a uniform irradiation and compression of the target. The first step requires information concerning the laser focusing spots, the dimensions of the hohlraum, the inert gas contained in it, the materials of the wall. The second step is an optimization approach whose aim is to reduce the risk of laser-plasmas instabilities. This optimization is made through simulations of the amplification gains of stimulated Raman and Brillouin backscattering. This method has allowed us to design an optimized target for a rugby-shaped hohlraum. (A.C.)
Laser-Plasma experiments at ELI-NP
Ghenuche, Petru; Negoita, Florin; Diaconescu, Bogdan; Stutman, Dan
2017-10-01
Recent advances in ultra-high power lasers architecture brings unprecedented intensity and pressure regimes within our reach. Extreme Light Infrastructure - Nuclear Physics (ELI-NP) is a new large laser facility, part of the ELI European research infrastructure that will benefit from these upgrades in the next years. It has the ambitious goal to use extreme electromagnetic fields generated by two 10 PW laser beams for a broad range of research topics in fundamental physics at the frontier of plasma physics, nuclear physics and astrophysics, together with applied research in materials and life sciences. Here we describe the facility implementation status and challenges and the commissioning experiments related with laser-plasma interaction.
Laser-Plasma Xuv Sources, Advances in Performance
F. Bijkerk,
1993-01-01
Radiative characteristics of laser-plasma x-ray sources, and the dependence of plasma parameters on the heating conditions are reviewed. A comparison is given with other x-ray sources like electron storage rings. Scaling of laser plasma x-ray sources to high average x-ray powers and methods to
Nonlinear Dynamics and Heterogeneous Interacting Agents
Lux, Thomas; Reitz, Stefan; Samanidou, Eleni
Economic application of nonlinear dynamics, microscopic agent-based modelling, and the use of artificial intelligence techniques as learning devices of boundedly rational actors are among the most exciting interdisciplinary ventures of economic theory over the past decade. This volume provides us with a most fascinating series of examples on "complexity in action" exemplifying the scope and explanatory power of these innovative approaches.
Dynamical and spectral properties of interacting quantum nonlinear resonances
International Nuclear Information System (INIS)
Berman, G.P.; Vlasova, O.F.; Kolovskij, A.R.; Izrajlev, F.M.
1987-01-01
While considering nonlinear quantum systems in the quasiclassical occupation region interacting with an external periodical field, the renormalization method is used. In case of interactions of two nonlinear resonances renormalization is associated with occurence of higher order nonlinear resonances. There is a limit in the renormalization pattern related to existence of higher resonances, for which the number of quasienergy levels in the potential pit is small. Analysis of distributions of delocalized quasi-energy functions, corresponding to destroyed resonances, and those of distances between the adjastment quasienergy levels has shown the presence of considerable correlations. The correlations are due to phase space restricted in action and quantum effects leading to classical chaos restriction
Symbolic computation of nonlinear wave interactions on MACSYMA
International Nuclear Information System (INIS)
Bers, A.; Kulp, J.L.; Karney, C.F.F.
1976-01-01
In this paper the use of a large symbolic computation system - MACSYMA - in determining approximate analytic expressions for the nonlinear coupling of waves in an anisotropic plasma is described. MACSYMA was used to implement the solutions of a fluid plasma model nonlinear partial differential equations by perturbation expansions and subsequent iterative analytic computations. By interacting with the details of the symbolic computation, the physical processes responsible for particular nonlinear wave interactions could be uncovered and appropriate approximations introduced so as to simplify the final analytic result. Details of the MACSYMA system and its use are discussed and illustrated. (Auth.)
Nonlinear Interactions for Broadband Energy Harvesting
2015-04-22
Inman, D.J., 2010, “On the manifestation and influence of material nonlinearity in electroelastic power generator” ASME/AIAA Conference on Smart ...ASME/AIAA Conference on Smart Materials, Adaptive Structures, and Intelligent Systems, Philadelphia, PA, Sep. 29–Oct. 1 (Best student paper for the...3. Lipp, G.M., Hall, K.C., Mann, B.P., 2013,“Effect of rider position on bicycle stability,” Proceedings of ASME International Mechanical Engineering
Charge Diagnostics for Laser Plasma Accelerators
Energy Technology Data Exchange (ETDEWEB)
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.
Charge Diagnostics for Laser Plasma Accelerators
International Nuclear Information System (INIS)
Nakamura, K.; Gonsalves, A.J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W.P.
2010-01-01
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.
Efficient algorithms for non-linear four-wave interactions
Van Vledder, G.P.
2012-01-01
This paper addresses the on-going activities in the development of efficient methods for computing the non-linear four-wave interactions in operational discrete third-generation wind-wave models. It is generally assumed that these interactions play an important role in the evolution of wind
Summary Report of Working Group 6: Laser-Plasma Acceleration
Energy Technology Data Exchange (ETDEWEB)
Leemans, Wim P.; Downer, Michael; Siders, Craig
2006-07-01
A summary is given of presentations and discussions in theLaser-Plasma Acceleration Working Group at the 2006 Advanced AcceleratorConcepts Workshop. Presentation highlights include: widespreadobservation of quasi-monoenergetic electrons; good agreement betweenmeasured and simulated beam properties; the first demonstration oflaser-plasma acceleration up to 1 GeV; single-shot visualization of laserwakefield structure; new methods for measuring<100 fs electronbunches; and new methods for "machining" laser-plasma acceleratorstructures. Discussion of future direction includes: developing a roadmapfor laser-plasma acceleration beyond 1 GeV; a debate over injection andguiding; benchmarking simulations with improved wake diagnostics;petawatt laser technology for future laser-plasmaaccelerators.
Laboratory beam-plasma interactions: linear and nonlinear
International Nuclear Information System (INIS)
Christiansen, P.J.; Jain, V.K.; Bond, J.W.
1982-01-01
The present investigation is concerned with the configuration of a cool plasma (often magnetized axially) penetrated by an injected electron beam. The attempt is made to demonstrate that despite unavoidable scaling limitations, laboratory experiments can illuminate, in a controlled fashion, details of beam plasma interaction processes in a way which will never be possible in the space plasma physics. In view of the increasing interest in high frequency instabilities in the auroral zone, the possibilities for interesting cross fertilizations of the two fields appear to be extensive. The linear theory is considered along with low frequency couplings and indirect effects. Attention is given to the evidence for the existence of exponentially growing instabilities in beam plasma interactions. The consequences of such instabilities are also explored and some processes of nonlinear processes are discussed, taking into account quasi-linear effects, trapping effects, nonlinear effects, trapping effects, nonlinear wave-wave interactions, and self-modulation and cavitation. 80 references
A Hybrid Model for Multiscale Laser Plasma Simulations with Detailed Collisional Physics
2016-11-29
Utilize hybridization techniques to produce accurate and efficient plasma simulations that spans many orders of magnitude in both space and time...hybridization • Special attention to low density low energy conditions Laser Plasma Interaction 4Distribution A – Approved for public release...Rob Martin (FRC) • Onsite Contractors (ERC inc.) – Richard Abrantes (Grad Student , LPI) – Dr. Jun Araki (Flight Support, PIC) – Dr. Carl Lederman
Plume Expansion and Ionization in a Micro Laser Plasma Thruster
National Research Council Canada - National Science Library
Reilly, Michael P; Miley, George H; Hargus, William A., Jr
2005-01-01
.... The micro-laser plasma thruster (micro-LPT) discussed here ablates a target material through the back surface by focusing the laser through a transparent substrate in a process typically referred to as Transmissive mode (T-mode) ablation...
Pulse Front Tilt and Laser Plasma Acceleration
Mittelberger, Daniel; Thévenet, Maxence; Nakamura, Kei; Lehe, Remi; Gonsalves, Anthony; Benedetti, Carlo; Leemans, Wim
2017-10-01
Pulse front tilt (PFT) is potentially present in any CPA laser system, but its effects may be overlooked because spatiotemporal pulse characterization is considerably more involved than measuring only spatial or temporal profile. PFT is particularly important for laser plasma accelerators (LPA) because it influences electron beam injection and steering. In this work, experimental results from the BELLA Center will be presented that demonstrate the effect of optical grating misalignment and optical compression, resulting in PFT, on accelerator performance. Theoretical models of laser and electron beam steering will be introduced based on particle-in-cell simulations showing distortion of the plasma wake. Theoretical predictions will be compared with experiments and complimentary simulations, and tolerances on PFT and optical compressor alignment will be developed as a function of LPA performance requirements. This work was supported by the Office of High Energy Physics, Office of Science, US Department of Energy under Contract DE-AC02-05CH11231 and the National Science Foundation under Grant PHY-1415596.
EFFECT OF LASER LIGHT ON LASER PLASMAS: Laser plasma at low air pressure
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.
Nonlinear interaction of the surface waves at a plasma boundary
International Nuclear Information System (INIS)
Dolgopolov, V.V.; El-Naggar, I.A.; Hussein, A.M.; Khalil, Sh.M.
1976-01-01
Amplitudes of electromagnetic waves with combination frequencies, radiating from the plasma boundary due to nonlinear interaction of the surface waves, have been found. Previous papers on this subject did not take into account that the tangential components of the electric field of waves with combination frequencies were discontinuous at the plasma boundary. (Auth.)
NON-LINEAR MODELING OF THE RHIC INTERACTION REGIONS
International Nuclear Information System (INIS)
TOMAS, R.; FISCHER, W.; JAIN, A.; LUO, Y.; PILAT, F.
2004-01-01
For RHIC's collision lattices the dominant sources of transverse non-linearities are located in the interaction regions. The field quality is available for most of the magnets in the interaction regions from the magnetic measurements, or from extrapolations of these measurements. We discuss the implementation of these measurements in the MADX models of the Blue and the Yellow rings and their impact on beam stability
NON-LINEAR MODELING OF THE RHIC INTERACTION REGIONS.
Energy Technology Data Exchange (ETDEWEB)
TOMAS,R.FISCHER,W.JAIN,A.LUO,Y.PILAT,F.
2004-07-05
For RHIC's collision lattices the dominant sources of transverse non-linearities are located in the interaction regions. The field quality is available for most of the magnets in the interaction regions from the magnetic measurements, or from extrapolations of these measurements. We discuss the implementation of these measurements in the MADX models of the Blue and the Yellow rings and their impact on beam stability.
Nonlinear light-matter interactions in engineered optical media
Litchinitser, Natalia
In this talk, we consider fundamental optical phenomena at the interface of nonlinear and singular optics in artificial media, including theoretical and experimental studies of linear and nonlinear light-matter interactions of vector and singular optical beams in metamaterials. We show that unique optical properties of metamaterials open unlimited prospects to ``engineer'' light itself. Thanks to their ability to manipulate both electric and magnetic field components, metamaterials open new degrees of freedom for tailoring complex polarization states and orbital angular momentum (OAM) of light. We will discuss several approaches to structured light manipulation on the nanoscale using metal-dielectric, all-dielectric and hyperbolic metamaterials. These new functionalities, including polarization and OAM conversion, beam magnification and de-magnification, and sub-wavelength imaging using novel non-resonant hyperlens are likely to enable a new generation of on-chip or all-fiber structured light applications. The emergence of metamaterials also has a strong potential to enable a plethora of novel nonlinear light-matter interactions and even new nonlinear materials. In particular, nonlinear focusing and defocusing effects are of paramount importance for manipulation of the minimum focusing spot size of structured light beams necessary for nanoscale trapping, manipulation, and fundamental spectroscopic studies. Colloidal suspensions offer as a promising platform for engineering polarizibilities and realization of large and tunable nonlinearities. We will present our recent studies of the phenomenon of spatial modulational instability leading to laser beam filamentation in an engineered soft-matter nonlinear medium. Finally, we introduce so-called virtual hyperbolic metamaterials formed by an array of plasma channels in air as a result of self-focusing of an intense laser pulse, and show that such structure can be used to manipulate microwave beams in a free space. This
Nonlinear Wave-Particle Interactions in Radiation Belt Physics
Summers, D.; Tang, R.; Omura, Y.; Miyashita, Y.
2010-12-01
Earth's radiation belts have undergone considerable theoretical and experimental investigation since their discovery in 1958 by James Van Allen and colleagues.Much of our understanding of wave-particle interactions in the radiation belts has been based on the linear theory of plasma waves and quasi-linear diffusion.There is recent evidence ,however,that fully nonlinear aspects of wave-particle interactions may play an essential role in radiation belt physics.This evidence is in the form of increasingly refined wave and particle data,and,in parallel,recently developed nonlinear wave growth theory supported by self-consistent particle simulations.We examine the nonlinear spatio-temporal evolution of whistler-mode chorus emissions in the Earth's inner magnetosphere.Chorus waves with rising frequency are generated at the magnetic equator,and propagate to higher latitudes.During propagation,nonlinear wave evolution occurs due to interaction with resonant electrons.From model equations we reproduce the time evolution of the chorus wave at the equator.By taking into account the adiabatic variation of the off-equatorial energetic particle distribution,we determine the resonant current.Then by solving general wave equations numerically we obtain the time evolution of the chorus wave frequency and amplitude along the static dipole magnetic field.Further,we incorporate the effects of nonlinear wave growth into the calculation of the Kennel-Petschek limit for the stably-trapped particle flux in a planetary magnetosphere.Using the model chorus equations we estimate nonlinear growth rates for a range of input parameters.By calculating the resulting total wave gain,we are able to estimate the self-limiting particle flux.We compare our new theoretical results for the limiting flux with particle observations at Earth and Saturn.
Dynamical soil-structure interactions: influence of soil behaviour nonlinearities
International Nuclear Information System (INIS)
Gandomzadeh, Ali
2011-01-01
The interaction of the soil with the structure has been largely explored the assumption of material and geometrical linearity of the soil. Nevertheless, for moderate or strong seismic events, the maximum shear strain can easily reach the elastic limit of the soil behavior. Considering soil-structure interaction, the nonlinear effects may change the soil stiffness at the base of the structure and therefore energy dissipation into the soil. Consequently, ignoring the nonlinear characteristics of the dynamic soil-structure interaction (DSSI) this phenomenon could lead to erroneous predictions of structural response. The goal of this work is to implement a fully nonlinear constitutive model for soils into a numerical code in order to investigate the effect of soil nonlinearity on dynamic soil structure interaction. Moreover, different issues are taken into account such as the effect of confining stress on the shear modulus of the soil, initial static condition, contact elements in the soil-structure interface, etc. During this work, a simple absorbing layer method based on a Rayleigh/Caughey damping formulation, which is often already available in existing Finite Element softwares, is also presented. The stability conditions of the wave propagation problems are studied and it is shown that the linear and nonlinear behavior are very different when dealing with numerical dispersion. It is shown that the 10 points per wavelength rule, recommended in the literature for the elastic media is not sufficient for the nonlinear case. The implemented model is first numerically verified by comparing the results with other known numerical codes. Afterward, a parametric study is carried out for different types of structures and various soil profiles to characterize nonlinear effects. Different features of the DSSI are compared to the linear case: modification of the amplitude and frequency content of the waves propagated into the soil, fundamental frequency, energy dissipation in
LINEAR AND NONLINEAR CORRECTIONS IN THE RHIC INTERACTION REGIONS
International Nuclear Information System (INIS)
PILAT, F.; CAMERON, P.; PTITSYN, V.; KOUTCHOUK, J.P.
2002-01-01
A method has been developed to measure operationally the linear and non-linear effects of the interaction region triplets, that gives access to the multipole content through the action kick, by applying closed orbit bumps and analyzing tune and orbit shifts. This technique has been extensively tested and used during the RHIC operations in 2001. Measurements were taken at 3 different interaction regions and for different focusing at the interaction point. Non-linear effects up to the dodecapole have been measured as well as the effects of linear, sextupolar and octupolar corrections. An analysis package for the data processing has been developed that through a precise fit of the experimental tune shift data (measured by a phase lock loop technique to better than 10 -5 resolution) determines the multipole content of an IR triplet
Multilayer optics provides laser--plasma-coupling insight
International Nuclear Information System (INIS)
Godwin, R.P.
1995-01-01
The Herpin theorem permits the reflectance of an arbitrary medium to be reproduced with a substrate of one complex refractive index overlaid with a coating film of a second complex refractive index and an appropriate thickness. The reflectances of a variety of laser--plasma-coupling experiments can be matched with a simple and physically meaningful procedure for choosing the fitting parameters. For short-pulse experiments, s-light coupling is dominated by substrate interactions at electron densities above critical and p-light coupling is dominated by resonance at the critical density. The weak dependence of resonance absorption on damping is the result of the harmonic-oscillator resonance form. As the plasma scale length becomes vanishingly small, the reflectance is that of the Fresnel equations, but surprisingly small plasma scale lengths have dramatic effects on the p-light reflectance. Film--substrate and WKB models predict similar resonance absorption, where both models are valid approximations and both should agree with multilayer and Helmholtz wave-optics calculations. For plasma scale lengths well below a wavelength, the film--substrate and the vacuum-heating models are closely related
Intense ion beams from laser plasma : production and application
International Nuclear Information System (INIS)
Bykovsky, Yu.A.; Kozlovsky, K.I.; Shikanov, A.E.
1994-01-01
The production of intense ion beams from plasma injectors using laser-induced plasma bundles are considered. Laser plasma bundles with quantity of ions about 10 sup 1 sup 5 - 10 sup 1 sup 6 imp sup -1 are created by interaction of laser irradiation ( q = 10 sup 9 - 10 sup 1 sup 3 W / cm sup 2, less than 'thermonuclear' intensities, lambda - 0.53 - 10.6 micro, E 0.1 - 10 J/ imp )with various solid targets in vacuum. By changing laser parameters and focusing conditions it is able to produce ions from very wide spectrum of chemical elements and of different charge. High density moving plasma gives the possibility to extract and to form in time up to 1 - 3 microsecond ion current equal 10-10 sup 3 A. Some types of such injector for radiation physics arrangements were elaborated. The main goals of the application of these equipment are the following : - acceleration of multiply charged ions in big accelerators; - ion implantation and material modification; - generation of intense pulse neutron fluxes; - vaporization of material and special layers creation. 4 refs., (author)
International Nuclear Information System (INIS)
Lalousis, P.
1984-01-01
Nonthermal direct electrodynamic interaction between laser energy and a fully ionized plasma was studied. The particular emphasis is on the action of nonlinear forces, in which the optical electromagnetic fields act on the plasma electrons which then transfer their energy to the ions electrostatically. Instead of the usual single fluid model, the plasma is treated as two separate conducting fluids for electrons and ions, coupled by momentum and Coulomb interactions. The equations governing the two fluids are derived from first principles, and numerical algorithms for computing these equations are developed, enabling the plasma oscillatons to be resolved and studied. Fully ionized plasma expansion without laser irradiation is studied first numerically. Remarkable damping mechanisms by coupling to ion oscillations have been observed. Inhomogeneities in densities of the two fluids result in large electrostatic fields and double layers are generated. There is quite close agreement between numerically calculated electrostatic fields and analytical solutions. Laser interaction with fully ionized plasma is also studied numerically. The generation of cavitons is numerically observed, and it is inferred that laser plasma interactions produce very high electrostatic fields in the vicinity of cavitons. It is further shown that charge neutrality is not necessarily maintained in a caviton
Laser-plasma-based Space Radiation Reproduction in the Laboratory.
Hidding, B; Karger, O; Königstein, T; Pretzler, G; Manahan, G G; McKenna, P; Gray, R; Wilson, R; Wiggins, S M; Welsh, G H; Beaton, A; Delinikolas, P; Jaroszynski, D A; Rosenzweig, J B; Karmakar, A; Ferlet-Cavrois, V; Costantino, A; Muschitiello, M; Daly, E
2017-02-08
Space radiation is a great danger to electronics and astronauts onboard space vessels. The spectral flux of space electrons, protons and ions for example in the radiation belts is inherently broadband, but this is a feature hard to mimic with conventional radiation sources. Using laser-plasma-accelerators, we reproduced relativistic, broadband radiation belt flux in the laboratory, and used this man-made space radiation to test the radiation hardness of space electronics. Such close mimicking of space radiation in the lab builds on the inherent ability of laser-plasma-accelerators to directly produce broadband Maxwellian-type particle flux, akin to conditions in space. In combination with the established sources, utilisation of the growing number of ever more potent laser-plasma-accelerator facilities worldwide as complementary space radiation sources can help alleviate the shortage of available beamtime and may allow for development of advanced test procedures, paving the way towards higher reliability of space missions.
Soft X-Ray amplification in laser plasmas
International Nuclear Information System (INIS)
Louis-Jacquet, M.
1988-01-01
The principles, experiments and theoretical models of soft x-ray, amplification, produced in laser plasmas, are studied. In the discussion of the principles, the laser plasma medium, the definition of the gain, the population inversions, saturation and superradiance are described. The results concerning recombination and collisional excitation experiments, as well as experimental devices are shown. A complete physical simulation to design and interpret x-ray laser experiments is given. Applications of x-ray lasers in grating production techniques, in contact microscopy and holography are considered
Theory and simulation of laser plasma coupling
International Nuclear Information System (INIS)
Kruer, W.L.
1979-01-01
The theory and simulation of these coupling processes are considered. Particular emphasis is given to their nonlinear evolution. First a brief introduction to computer simulation of plasmas using particle codes is given. Then the absorption of light via the generation of plasma waves is considered, followed by a discussion of stimulated scattering of intense light. Finally these calculations are compared with experimental results
Energy Technology Data Exchange (ETDEWEB)
Guenther, Marc M.
2011-01-19
The present work explores with the development of a novel nuclear diagnostic method for the investigation of the electron dynamics in relativistic laser-plasma interactions. An additional aim of this work was the determination of the real laser peak intensity via the interaction of an intense laser short-pulse with a solid target. The nuclear diagnostics is based on a photo-neutron disintegration nuclear activation method. The main constituent of the nuclear diagnostic are novel pseudoalloic activation targets as a kind of calorimeter to measure the high-energy bremsstrahlung produced by relativistic electrons. The targets are composed of several stable isotopes with different ({gamma},xn)-reaction thresholds. The activated nuclides were identified via the characteristic gamma-ray decay spectrum by using high-resolution gamma spectroscopy after the laser irradiation. Via the gamma spectroscopy the ({gamma},xn)-reaction yields were determined. The high-energy bremsstrahlung spectrum has been deconvolved using a novel analysis method based on a modified Penfold-Leiss method. This facilitates the reconstruction of the spectrum of bremsstrahlung photons without any anticipated fit procedures. Furthermore, the characterization of the corresponding bremsstrahlung electrons in the interaction zone is accessible immediately. The consolidated findings about the properties of the relativistic electrons were used to determine the real peak intensity at the laser-plasma interaction zone. In the context of this work, experiments were performed at three different laser facilities. First Experiments were carried out at the 100 TW laser facility at Laboratoire pour l'Utilisation des Lasers Intense (LULI) in France and supplementary at the Vulcan laser facility at Rutherford Appleton Laboratory (RAL) in United Kingdom. The main part of the activation experiments were performed at the PHELIX laser facility (Petawatt High Energy Laser for heavy Ion EXperiments) at GSI
Fluid transport due to nonlinear fluid-structure interaction
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard
1997-01-01
This work considers nonlinear fluid-structure interaction for a vibrating pipe containing fluid. Transverse pipe vibrations will force the fluid to move relative to the pipe creating unidirectional fluid flow towards the pipe end. The fluid flow induced affects the damping and the stiffness...... of the pipe. The behavior of the system in response to lateral resonant base excitation is analysed numerically and by the use of a perturbation method (multiple scales). Exciting the pipe in the fundamental mode of vibration seems to be most effective for transferring energy from the shaker to the fluid......, whereas higher modes of vibration can be used to transport fluid with pipe vibrations of smaller amplitude. The effect of the nonlinear geometrical terms is analysed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement...
LDRD Final Report: Adaptive Methods for Laser Plasma Simulation
International Nuclear Information System (INIS)
Dorr, M R; Garaizar, F X; Hittinger, J A
2003-01-01
The goal of this project was to investigate the utility of parallel adaptive mesh refinement (AMR) in the simulation of laser plasma interaction (LPI). The scope of work included the development of new numerical methods and parallel implementation strategies. The primary deliverables were (1) parallel adaptive algorithms to solve a system of equations combining plasma fluid and light propagation models, (2) a research code implementing these algorithms, and (3) an analysis of the performance of parallel AMR on LPI problems. The project accomplished these objectives. New algorithms were developed for the solution of a system of equations describing LPI. These algorithms were implemented in a new research code named ALPS (Adaptive Laser Plasma Simulator) that was used to test the effectiveness of the AMR algorithms on the Laboratory's large-scale computer platforms. The details of the algorithm and the results of the numerical tests were documented in an article published in the Journal of Computational Physics [2]. A principal conclusion of this investigation is that AMR is most effective for LPI systems that are ''hydrodynamically large'', i.e., problems requiring the simulation of a large plasma volume relative to the volume occupied by the laser light. Since the plasma-only regions require less resolution than the laser light, AMR enables the use of efficient meshes for such problems. In contrast, AMR is less effective for, say, a single highly filamented beam propagating through a phase plate, since the resulting speckle pattern may be too dense to adequately separate scales with a locally refined mesh. Ultimately, the gain to be expected from the use of AMR is highly problem-dependent. One class of problems investigated in this project involved a pair of laser beams crossing in a plasma flow. Under certain conditions, energy can be transferred from one beam to the other via a resonant interaction with an ion acoustic wave in the crossing region. AMR provides an
China-US-Japan workshop on laser plasma and drivers
International Nuclear Information System (INIS)
1994-01-01
Organized by China Institute of Applied Physics and Computational Mathematics (IMPCM) and other 5 organizations, China-US-Japan Workshop on Laser Plasma and Drivers, LPD'94, was held on October 17-21, 1994 at Fragrant Hill Hotel, Beijing, China. Main topics includes: target and plasma physics, ICF Experiments, ICF drivers, etc.. More than 50 pieces of papers are included in the proceedings
Summary Report of Working Group: Laser-Plasma Acceleration
International Nuclear Information System (INIS)
Esarey, Eric; Schroeder, Carl B.; Tochitsky, Sergei; Milchberg, Howard M.
2004-01-01
A summary is given on the work presented and discussed in the Laser-Plasma Acceleration Working Group at the 2004 Advanced Accelerator Concepts Workshop, including the Plasma Acceleration Subgroup (Group-Leader: Eric Esarey; Co-Group-Leader: Sergei Tochitsky) and the Plasma Guiding Subgroup (Group-Leader: Howard Milchberg; Co-Group-Leader: Carl Schroeder)
Laser Plasmas: Multiple charge states of titanium ions in laser ...
Indian Academy of Sciences (India)
Author Affiliations. M Shukla1 S Bandhyopadhyay1 V N Rai1 A V Kilpio1 2 H C Pant1. Laser Plasma Division, Center for Advanced Technology, Indore 452 013, India; KAMETRON Laser Group, General Physics Institute, Valivov Street, Moscow ...
DEVICE FOR INVESTIGATION OF MAGNETRON AND PULSED-LASER PLASMA
Directory of Open Access Journals (Sweden)
A. P. Burmakov
2012-01-01
Full Text Available Various modifications of complex pulsed laser and magnetron deposition thin-film structures unit are presented. They include joint and separate variants of layer deposition. Unit realizes the plasma parameters control and enhances the possibility of laser-plasma and magnetron methods of coatings deposition.
Nonlinear interactions of focused resonance cone fields with plasmas
International Nuclear Information System (INIS)
Stenzel, R.L.; Gekelman, W.
1977-01-01
A simple yet novel rf exciter structure has been developed for generating remotely intense rf fields in a magnetoplasma. It is a circular line source of radius R in a plane perpendicularB 0 driven with an rf signal at ω 0 E/sub rf/ 2 /nkT/sub e/>0.2, a strong density depression in the focal region (deltan/n>40%) is observed. The density perturbation modifies the cone angle and field distribution. This nonlinear interaction leads to a rapid growth of ion acoustic wave turbulence and a corresponding random rf field distribution in a broadened focal region. The development of the interaction is mapped in space and time
A non-linear theory of strong interactions
International Nuclear Information System (INIS)
Skyrme, T.H.R.
1994-01-01
A non-linear theory of mesons, nucleons and hyperons is proposed. The three independent fields of the usual symmetrical pseudo-scalar pion field are replaced by the three directions of a four-component field vector of constant length, conceived in an Euclidean four-dimensional isotopic spin space. This length provides the universal scaling factor, all other constants being dimensionless; the mass of the meson field is generated by a φ 4 term; this destroys the continuous rotation group in the iso-space, leaving a 'cubic' symmetry group. Classification of states by this group introduces quantum numbers corresponding to isotopic spin and to 'strangeness'; one consequences is that, at least in elementary interactions, charge is only conserved module 4. Furthermore, particle states have not a well-defined parity, but parity is effectively conserved for meson-nucleon interactions. A simplified model, using only two dimensions of space and iso-space, is considered further; the non-linear meson field has solutions with particle character, and an indication is given of the way in which the particle field variables might be introduced as collective co-ordinates describing the dynamics of these particular solutions of the meson field equations, suggesting a unified theory based on the meson field alone. (author). 7 refs
Nonlinear dynamic soil-structure interaction in earthquake engineering
International Nuclear Information System (INIS)
Nieto-Ferro, Alex
2013-01-01
The present work addresses a computational methodology to solve dynamic problems coupling time and Laplace domain discretizations within a domain decomposition approach. In particular, the proposed methodology aims at meeting the industrial need of performing more accurate seismic risk assessments by accounting for three-dimensional dynamic soil-structure interaction (DSSI) in nonlinear analysis. Two subdomains are considered in this problem. On the one hand, the linear and unbounded domain of soil which is modelled by an impedance operator computed in the Laplace domain using a Boundary Element (BE) method; and, on the other hand, the superstructure which refers not only to the structure and its foundations but also to a region of soil that possibly exhibits nonlinear behaviour. The latter sub-domain is formulated in the time domain and discretized using a Finite Element (FE) method. In this framework, the DSSI forces are expressed as a time convolution integral whose kernel is the inverse Laplace transform of the soil impedance matrix. In order to evaluate this convolution in the time domain by means of the soil impedance matrix (available in the Laplace domain), a Convolution Quadrature-based approach called the Hybrid Laplace-Time domain Approach (HLTA), is thus introduced. Its numerical stability when coupled to Newmark time integration schemes is subsequently investigated through several numerical examples of DSSI applications in linear and nonlinear analyses. The HLTA is finally tested on a more complex numerical model, closer to that of an industrial seismic application, and good results are obtained when compared to the reference solutions. (author)
Barkhudarov, É. M.; Gelashvili, G. V.; Gumberidze, G. G.; Taktakishvili, M. I.
1990-06-01
An investigation was made of the enhancement in the efficiency of generation of currents when a target in air was subjected to two consecutive CO2 laser radiation pulses. Preliminary interaction with a low-energy (1.5-5 J) pulse increased by more than one order of magnitude the currents generated by the second pulse and this was true in a wide range of energies of the latter pulse. The energy conversion efficiency was practically unaffected. The results were in qualitative agreement with the proposed pattern of plasma formation and propagation of shock waves near a target.
High magnetic field generation for laser-plasma experiments
International Nuclear Information System (INIS)
Pollock, B. B.; Froula, D. H.; Davis, P. F.; Ross, J. S.; Fulkerson, S.; Bower, J.; Satariano, J.; Price, D.; Krushelnick, K.; Glenzer, S. H.
2006-01-01
An electromagnetic solenoid was developed to study the effect of magnetic fields on electron thermal transport in laser plasmas. The solenoid, which is driven by a pulsed power system supplying 30 kJ, achieves magnetic fields of 13 T. The field strength was measured on the solenoid axis with a magnetic probe and optical Zeeman splitting. The measurements agree well with analytical estimates. A method for optimizing the solenoid design to achieve magnetic fields exceeding 20 T is presented
MED101: a laser-plasma simulation code. User guide
International Nuclear Information System (INIS)
Rodgers, P.A.; Rose, S.J.; Rogoyski, A.M.
1989-12-01
Complete details for running the 1-D laser-plasma simulation code MED101 are given including: an explanation of the input parameters, instructions for running on the Rutherford Appleton Laboratory IBM, Atlas Centre Cray X-MP and DEC VAX, and information on three new graphics packages. The code, based on the existing MEDUSA code, is capable of simulating a wide range of laser-produced plasma experiments including the calculation of X-ray laser gain. (author)
Coulomb implosion mechanism of negative ion acceleration in laser plasmas
Nakamura, T.; Fukuda, Y.; Yogo, A.; Tampo, M.; Kando, M.; Hayashi, Y.; Kameshima, T.; Pirozhkov, A. S.; Esirkepov, T. Zh.; Pikuz, T. A.; Faenov, A. Ya.; Daido, H.; Bulanov, S. V.
2008-01-01
Coulomb implosion mechanism of the negatively charged ion acceleration in laser plasmas is proposed. When a cluster target is irradiated by an intense laser pulse and the Coulomb explosion of positively charged ions occurs, the negative ions are accelerated inward. The maximum energy of negative ions is several times lower than that of positive ions. The theoretical description and Particle-in-Cell simulation of the Coulomb implosion mechanism and the evidence of the negative ion acceleration...
Plasma Injection Schemes for Laser-Plasma Accelerators
Faure, J.
2016-01-01
Plasma injection schemes are crucial for producing high-quality electron beams in laser-plasma accelerators. This article introduces the general concepts of plasma injection. First, a Hamiltonian model for particle trapping and acceleration in plasma waves is introduced; ionization injection and colliding-pulse injection are described in the framework of this Hamiltonian model. We then proceed to consider injection in plasma density gradients.
Interaction between two point-like charges in nonlinear electrostatics
Breev, A. I.; Shabad, A. E.
2018-01-01
We consider two point-like charges in electrostatic interaction within the framework of a nonlinear model, associated with QED, that provides finiteness of their field energy. We find the common field of the two charges in a dipole-like approximation, where the separation between them R is much smaller than the observation distance r : with the linear accuracy with respect to the ratio R / r, and in the opposite approximation, where R≫ r, up to the term quadratic in the ratio r / R. The consideration proposes the law a+b R^{1/3} for the energy, when the charges are close to one another, R→ 0. This leads to the singularity of the force between them to be R^{-2/3}, which is weaker than the Coulomb law, R^{-2}.
Nonlinear dynamic susceptibilities of interacting and noninteracting magnetic nanoparticles
Joensson, P; García-Palacios, J L; Svedlindh, P
2000-01-01
The linear and cubic dynamic susceptibilities of solid dispersions of nanosized maghemite gamma-Fe sub 2 O sub 3 particles have been measured for three samples with a volume concentration of magnetic particles ranging from 0.3% to 17%, in order to study the effect of dipole-dipole interactions. Significant differences between the dynamic response of the samples are observed. While the linear and cubic dynamic susceptibilities of the most dilute sample compare reasonably well with the corresponding expressions proposed by Raikher and Stepanov for noninteracting particles, the nonlinear dynamic response of the most concentrated sample exhibits at low temperatures similar features as observed in a Ag(11 at% Mn) spin glass.
National Aeronautics and Space Administration — ZONA Technology, Inc. proposes to develop an integrated flight dynamics simulation capability with nonlinear aeroelastic interactions by combining a flight dynamics...
National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an integrated flight dynamics simulation capability with nonlinear aeroelastic interactions by combining a flight...
Zaikin, A. E.; Levin, A. V.; Petrov, A. L.
1995-02-01
A surface optical-discharge plasma was formed in a metal vapour under normal conditions by steady-state irradiation with a cw CO2 laser delivering radiation of moderate (2-4.5 MW cm-2) intensity. This plasma strongly screened the irradiated surface. Under the selected experimental conditions the optical discharge was not a continuous (steady-state) process. The plasma cloud was displaced along the beam out of the waist to a region where the laser radiation intensity was almost an order of magnitude less than the threshold for excitation of the optical-discharge plasma in the vapour. A strong screening of the metal surface, which could even completely stop evaporation of the metal, was observed. Self-oscillations of the optical-discharge plasma were observed for the first time in a vapour interacting with cw CO2 radiation: this was attributed to screening of the target surface. Within one period of the self-oscillations there were additional hf plasma pulsations which led to stratification of the plasma cloud. The results obtained were interpreted.
Nonlinear interaction of colliding beams in particle storage rings
Energy Technology Data Exchange (ETDEWEB)
Herrera, J C; Month, M
1979-01-01
When two beams of high energy particles moving in opposite directions are brought into collision, a large amount of energy is available for the production of new particles. However to obtain a sufficiently high event rate for rare processes, such as the production of the intermediate vector boson (Z/sub 0/ and W/sup + -/), large beam currents are also required. Under this circumstance, the high charge density of one beam results in a classical electromagnetic interaction on the particles in the other beam. This very nonlinear space charge force, caled the beam-beam force, limits the total circulating charge and, thereby, the ultimate performance of the colliding ring system. The basic nature of the beam-beam force is discussed, indicating how it is quite different in the case of continuous beams, which cross each other at an angle as compared to the case of bunched beams which collide head-on. Some experimental observations on the beam-beam interaction in proton-proton and electron-positron beams are then reviewed and interpreted. An important aspect of the beam-beam problem in storage rings is to determine at what point in the analysis of the particle dynamics is it relevant to bring in the concepts of stochasticity, slow diffusion, and resonance overlap. These ideas are briefly discussed.
Characterization and modeling of nonlinear hydrophobic interaction chromatographic systems.
Nagrath, Deepak; Xia, Fang; Cramer, Steven M
2011-03-04
A general rate model was employed in concert with a preferential interaction quadratic adsorption isotherm for the characterization of HIC resins and the prediction of solute behavior in these separation systems. The results indicate that both pore and surface diffusion play an important role in protein transport in HIC resins. The simulated and experimental solute profiles were compared for two model proteins, lysozyme and lectin, for both displacement and gradient modes of chromatography. Our results indicate that a modeling approach using the generate rate model and preferential interaction isotherm can accurately predict the shock layer response in both gradient and displacement chromatography in HIC systems. While pore and surface diffusion played a major role and were limiting steps for proteins, surface diffusion was seen to play less of a role for the displacer. The results demonstrate that this modeling approach can be employed to describe the behavior of these non-linear HIC systems, which may have implications for the development of more efficient preparative HIC separations. Copyright © 2011 Elsevier B.V. All rights reserved.
Nonlinear interactions of electromagnetic waves with the auroral ionosphere
Wong, Alfred Y.
1999-09-01
The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO2 through the use of ion cyclotron resonant heating.
Development of Laser Plasma X-ray Microbeam Irradiation System and Radiation Biological Application
Sato, Katsutoshi; Nishikino, Masaharu; Numasaki, Hodaka; Kawachi, Tetsuya; Teshima, Teruki; Nishimura, Hiroaki
Laser plasma x-ray source has the features such as ultra short pulse, high brilliance, monochromaticity, and focusing ability. These features are excellent compared with conventional x-ray source. In order to apply the laser plasma x-ray source to the biomedical study and to more closely research the radiobilogical responce of the cancer cell such as radiation induced bystander effect, we have developed x-ray microbeam system using laser plasma x-ray source. The absorbed dose of laser plasma x-ray was estimated with Gafchromic EBT film and DNA double strand breaks on the cells were detected by immunofluorescence staining. When the cells were irradiated with laser plasma x-ray, the circular regions existing γ-H2AX positive cells were clearly identified. The usefulness of the laser plasma x-ray on the radiobiological study was proved in this research.
Summary Report of Working Group 1: Laser-Plasma Acceleration
Energy Technology Data Exchange (ETDEWEB)
Geddes, C.G.R.; Clayton, C.; Lu, W.; Thomas, A.G.R.
2010-06-01
Advances in and physics of the acceleration of particles using underdense plasma structures driven by lasers were the topics of presentations and discussions in Working Group 1 of the 2010 Advanced Accelerator Concepts Workshop. Such accelerators have demonstrated gradients several orders beyond conventional machines, with quasi-monoenergetic beams at MeV-GeV energies, making them attractive candidates for next generation accelerators. Workshop discussions included advances in control over injection and laser propagation to further improve beam quality and stability, detailed diagnostics and physics models of the acceleration process, radiation generation as a source and diagnostic, and technological tools and upcoming facilities to extend the reach of laser-plasma accelerators.
Erosion resistant nozzles for laser plasma extreme ultraviolet (EUV) sources
Kubiak, Glenn D.; Bernardez, II, Luis J.
2000-01-04
A gas nozzle having an increased resistance to erosion from energetic plasma particles generated by laser plasma sources. By reducing the area of the plasma-facing portion of the nozzle below a critical dimension and fabricating the nozzle from a material that has a high EUV transmission as well as a low sputtering coefficient such as Be, C, or Si, it has been shown that a significant reduction in reflectance loss of nearby optical components can be achieved even after exposing the nozzle to at least 10.sup.7 Xe plasma pulses.
Summary Report of Working Group 1: Laser-Plasma Acceleration
International Nuclear Information System (INIS)
Geddes, C.G.R.; Clayton, C.; Lu, W.; Thomas, A.G.R.
2010-01-01
Advances in and physics of the acceleration of particles using underdense plasma structures driven by lasers were the topics of presentations and discussions in Working Group 1 of the 2010 Advanced Accelerator Concepts Workshop. Such accelerators have demonstrated gradients several orders beyond conventional machines, with quasi-monoenergetic beams at MeV-GeV energies, making them attractive candidates for next generation accelerators. Workshop discussions included advances in control over injection and laser propagation to further improve beam quality and stability, detailed diagnostics and physics models of the acceleration process, radiation generation as a source and diagnostic, and technological tools and upcoming facilities to extend the reach of laser-plasma accelerators.
Particle physicist's dreams about PetaelectronVolt laser plasma accelerators
International Nuclear Information System (INIS)
Vesztergombi, G.
2012-01-01
Present day accelerators are working well in the multi TeV energy scale and one is expecting exciting results in the coming years. Conventional technologies, however, can offer only incremental (factor 2 or 3) increase in beam energies which does not follow the usual speed of progress in the frontiers of high energy physics. Laser plasma accelerators theoretically provide unique possibilities to achieve orders of magnitude increases entering the PetaelectronVolt (PeV) energy range. It will be discussed what kind of new perspectives could be opened for the physics at this new energy scale. What type of accelerators would be required?.
Angular-Momentum Evolution in Laser-Plasma Accelerators
Thaury, Cédric; Corde, Sébastien; Lehe, Rémi; Le Bouteiller, Madeleine; Ta Phuoc, Kim; Davoine, Xavier; Rax, J. M.; Rousse, Antoine; Malka, Victor
2013-01-01
The transverse properties of an electron beam are characterized by two quantities, the emittance which indicates the electron beam extent in the phase space and the angular momentum which allows for non-planar electron trajectories. Whereas the emittance of electron beams produced in laserplasma accelerator has been measured in several experiments, their angular momentum has been scarcely studied. It was demonstrated that electrons in laser-plasma accelerator carry some angular momentum, but its origin was not established. Here we identify one source of angular momentum growth and we present experimental results showing that the angular momentum content evolves during the acceleration.
A pinhole camera for ultrahigh-intensity laser plasma experiments
Wang, C.; An, H. H.; Xiong, J.; Fang, Z. H.; Wang, Y. W.; Zhang, Z.; Hua, N.; Sun, J. R.; Wang, W.
2017-11-01
A pinhole camera is an important instrument for the detection of radiation in laser plasmas. It can monitor the laser focus directly and assist in the analysis of the experimental data. However, conventional pinhole cameras are difficult to use when the target is irradiated by an ultrahigh-power laser because of the high background of hard X-ray emission generated in the laser/target region. Therefore, an improved pinhole camera has been developed that uses a grazing-incidence mirror that enables soft X-ray imaging while avoiding the effect of hard X-ray from hot dense plasmas.
XUV radiation from gaseous nitrogen and argon target laser plasmas
Czech Academy of Sciences Publication Activity Database
Vrba, Pavel; Vrbová, M.; Brůža, P.; Pánek, D.; Krejčí, F.; Kroupa, M.; Jakůbek, J.
2012-01-01
Roč. 370, č. 1 (2012), s. 012049 ISSN 1742-6588. [Latin American Workshop on Plasma Physics (LAWPP 2011)/14/. Mar del Plata, 20.11.2011-25.11.2011] R&D Projects: GA MŠk LA08024; GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z20430508 Keywords : Laser plasma source of XUV radiation in water window range * RHMD Z* engine code Subject RIV: BH - Optics, Masers, Lasers http://iopscience.iop.org/1742-6596/370/1/012049/pdf/1742-6596_370_1_012049.pdf
Particle physicist's dreams about PetaelectronVolt laser plasma accelerators
Vesztergombi, G.
2012-07-01
Present day accelerators are working well in the multi TeV energy scale and one is expecting exciting results in the coming years. Conventional technologies, however, can offer only incremental (factor 2 or 3) increase in beam energies which does not follow the usual speed of progress in the frontiers of high energy physics. Laser plasma accelerators theoretically provide unique possibilities to achieve orders of magnitude increases entering the PetaelectronVolt (PeV) energy range. It will be discussed what kind of new perspectives could be opened for the physics at this new energy scale. What type of accelerators would be required?.
Ultrafast Diagnostics for Electron Beams from Laser Plasma Accelerators
Energy Technology Data Exchange (ETDEWEB)
Matlis, N. H.; Bakeman, M.; Geddes, C. G. R.; Gonsalves, T.; Lin, C.; Nakamura, K.; Osterhoff, J.; Plateau, G. R.; Schroeder, C. B.; Shiraishi, S.; Sokollik, T.; van Tilborg, J.; Toth, Cs.; Leemans, W. P.
2010-06-01
We present an overview of diagnostic techniques for measuring key parameters of electron bunches from Laser Plasma Accelerators (LPAs). The diagnostics presented here were chosen because they highlight the unique advantages (e.g., diverse forms of electromagnetic emission) and difficulties (e.g., shot-to-shot variability) associated with LPAs. Non destructiveness and high resolution (in space and time and energy) are key attributes that enable the formation of a comprehensive suite of simultaneous diagnostics which are necessary for the full characterization of the ultrashort, but highly-variable electron bunches from LPAs.
High-energy 4ω probe laser for laser-plasma experiments at Nova
International Nuclear Information System (INIS)
Glenzer, S.H.; Weiland, T.L.; Bower, J.; MacKinnon, A.J.; MacGowan, B.J.
1999-01-01
For the characterization of inertial confinement fusion plasmas, we implemented a high-energy 4ω probe laser at the Nova laser facility. A total energy of >50 J at 4ω, a focal spot size of order 100 μm, and a pointing accuracy of 100 μm was demonstrated for target shots. This laser provides intensities of up to 3x10 14 Wcm -2 and therefore fulfills high-power requirements for laser-plasma interaction experiments. The 4ω probe laser is now routinely used for Thomson scattering. Successful experiments were performed in gas-filled hohlraums at electron densities of n e >2x10 21 cm -3 which represents the highest density plasma so far being diagnosed with Thomson scattering. copyright 1999 American Institute of Physics
179th International School of Physics "Enrico Fermi" : Laser-Plasma Acceleration
Gizzi, L A; Faccini, R
2012-01-01
Impressive progress has been made in the field of laser-plasma acceleration in the last decade, with outstanding achievements from both experimental and theoretical viewpoints. Closely exploiting the development of ultra-intense, ultrashort pulse lasers, laser-plasma acceleration has developed rapidly, achieving accelerating gradients of the order of tens of GeV/m, and making the prospect of miniature accelerators a more realistic possibility. This book presents the lectures delivered at the Enrico Fermi International School of Physics and summer school: "Laser-Plasma Acceleration" , held in Varenna, Italy, in June 2011. The school provided an opportunity for young scientists to experience the best from the worlds of laser-plasma and accelerator physics, with intensive training and hands-on opportunities related to key aspects of laser-plasma acceleration. Subjects covered include: the secrets of lasers; the power of numerical simulations; beam dynamics; and the elusive world of laboratory plasmas. The object...
Nonlinear approach to NN interactions using self-interacting meson fields
International Nuclear Information System (INIS)
Jaede, L.; von Geramb, H.V.
1997-01-01
Motivated by the success of models based on chiral symmetry in NN interactions, we investigate self-interacting scalar, pseudoscalar, and vector meson fields and their impact for NN forces. We parametrize the corresponding nonlinear field equations and get analytic wavelike solutions. A probability amplitude for the propagation of particle states is calculated and applied in the framework of a boson-exchange NN potential. Using a proper normalization of the meson fields makes all self-scattering amplitudes finite. The same normalization is able to substitute for the phenomenological form factors used in conventional boson-exchange potentials and thus yields a phenomenological understanding of this part of the NN interaction. We find an empirical scaling law which relates the meson self-interaction couplings to the pion mass and self-interaction coupling constant. Our model yields np phase shifts comparable to the Bonn B potential results and deuteron properties, in excellent agreement with experimental data. copyright 1997 The American Physical Society
''Flicker'' in laser-plasma self-focusing
International Nuclear Information System (INIS)
Coggeshall, S.V.; Mead, W.C.; Jones, R.D.
1988-01-01
Under certain conditions, a new mode of laser-plasma self-focusing can occur which is characterized by a self-sustaining, continual shifting of filament-produced focal spots and a somewhat chaotic redistribution of light at the critical surface. Associated with this phenomenon is the possibility of significant intensity multiplication due to self-focusing. This flickering of laser light is caused by small amplitude, short wavelength ion acoustic waves which are produced near the foci of the filaments and subsequently propagate and convect toward the laser. As these ion fluctuations move toward the laser, they cause further light ray trajectory changes which shift the locations of the foci. New sound waves are launched and the process is self-perpetuated. 7 refs., 5 figs
High-order finite difference solution for 3D nonlinear wave-structure interaction
DEFF Research Database (Denmark)
Ducrozet, Guillaume; Bingham, Harry B.; Engsig-Karup, Allan Peter
2010-01-01
This contribution presents our recent progress on developing an efficient fully-nonlinear potential flow model for simulating 3D wave-wave and wave-structure interaction over arbitrary depths (i.e. in coastal and offshore environment). The model is based on a high-order finite difference scheme...... OceanWave3D presented in [1, 2]. A nonlinear decomposition of the solution into incident and scattered fields is used to increase the efficiency of the wave-structure interaction problem resolution. Application of the method to the diffraction of nonlinear waves around a fixed, bottom mounted circular...
Advanced Seismic Fragility Modeling using Nonlinear Soil-Structure Interaction Analysis
Energy Technology Data Exchange (ETDEWEB)
Bolisetti, Chandu [Idaho National Lab. (INL), Idaho Falls, ID (United States); Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talaat, Mohamed [Simpson-Gupertz & Heger, Waltham, MA (United States); Hashimoto, Philip [Simpson-Gupertz & Heger, Waltham, MA (United States)
2015-09-01
The goal of this effort is to compare the seismic fragilities of a nuclear power plant system obtained by a traditional seismic probabilistic risk assessment (SPRA) and an advanced SPRA that utilizes Nonlinear Soil-Structure Interaction (NLSSI) analysis. Soil-structure interaction (SSI) response analysis for a traditional SPRA involves the linear analysis, which ignores geometric nonlinearities (i.e., soil and structure are glued together and the soil material undergoes tension when the structure uplifts). The NLSSI analysis will consider geometric nonlinearities.
Theory of nonlinear interaction of particles and waves in an inverse plasma maser. Part 1
International Nuclear Information System (INIS)
Krivitsky, V.S.; Vladimirov, S.V.
1991-01-01
An expression is obtained for the collision integral describing the simultaneous interaction of plasma particles with resonant and non-resonant waves. It is shown that this collision integral is determined by two processes: a 'direct' nonlinear interaction of particles and waves, and the influence of the non-stationary of the system. The expression for the nonlinear collision integral is found to be quite different from the expression for a quasi-linear collision integral; in particular, the nonlinear integral contains higher-order derivatives of the distribution function with respect to momentum than the quasi-linear one. (author)
The Impact of Dam-Reservoir-Foundation Interaction on Nonlinear Response of Concrete Gravity Dams
Amini, AliReza; Motamedi, Mohammad Hossein; Ghaemian, Mohsen
2008-07-01
To study the impact of dam-reservoir-foundation interaction on nonlinear response of concrete gravity dams, a two-dimensional finite element model of a concrete gravity dam including the dam body, a part of its foundation and a part of the reservoir was made. In addition, the proper boundary conditions were used in both reservoir and foundation in order to absorb the energy of outgoing waves at the far end boundaries. Using the finite element method and smeared crack approach, some different seismic nonlinear analyses were done and finally, we came to a conclusion that the consideration of dam-reservoir-foundation interaction in nonlinear analysis of concrete dams is of great importance, because from the performance point of view, this interaction significantly improves the nonlinear response of concrete dams.
The Impact of Dam-Reservoir-Foundation Interaction on Nonlinear Response of Concrete Gravity Dams
International Nuclear Information System (INIS)
Amini, Ali Reza; Motamedi, Mohammad Hossein; Ghaemian, Mohsen
2008-01-01
To study the impact of dam-reservoir-foundation interaction on nonlinear response of concrete gravity dams, a two-dimensional finite element model of a concrete gravity dam including the dam body, a part of its foundation and a part of the reservoir was made. In addition, the proper boundary conditions were used in both reservoir and foundation in order to absorb the energy of outgoing waves at the far end boundaries. Using the finite element method and smeared crack approach, some different seismic nonlinear analyses were done and finally, we came to a conclusion that the consideration of dam-reservoir-foundation interaction in nonlinear analysis of concrete dams is of great importance, because from the performance point of view, this interaction significantly improves the nonlinear response of concrete dams
Interaction of few-cycle laser pulses in an isotropic nonlinear medium
International Nuclear Information System (INIS)
Oganesyan, D L; Vardanyan, A O
2007-01-01
The interaction of few-cycle laser pulses propagating in an isotropic nonlinear medium is studied theoretically. A system of nonlinear Maxwell's equations is integrated numerically with respect to time by the finite difference method. The interaction of mutually orthogonal linearly polarised 0.81-μm, 10-fs pulses is considered. Both the instant Kerr polarisation response and Raman inertial response of the medium in the nonlinear part of the medium are taken into account. The spectral shift of the probe pulse caused by the cross-action of the reference pulse is studied. The spectra of the interacting pulses are studied for different time delays between them and the shifts of these spectra are obtained as a function of the time delay. (nonlinear optical phenomena)
Frequency-Domain Tomography for Single-shot, Ultrafast Imaging of Evolving Laser-Plasma Accelerators
Li, Zhengyan; Zgadzaj, Rafal; Wang, Xiaoming; Downer, Michael
2011-10-01
Intense laser pulses propagating through plasma create plasma wakefields that often evolve significantly, e.g. by expanding and contracting. However, such dynamics are known in detail only through intensive simulations. Laboratory visualization of evolving plasma wakes in the ``bubble'' regime is important for optimizing and scaling laser-plasma accelerators. Recently snap-shots of quasi-static wakes were recorded using frequency-domain holography (FDH). To visualize the wake's evolution, we have generalized FDH to frequency-domain tomography (FDT), which uses multiple probes propagating at different angles with respect to the pump pulse. Each probe records a phase streak, imprinting a partial record of the evolution of pump-created structures. We then topographically reconstruct the full evolution from all phase streaks. To prove the concept, a prototype experiment visualizing nonlinear index evolution in glass is demonstrated. Four probes propagating at 0, 0.6, 2, 14 degrees to the index ``bubble'' are angularly and temporally multiplexed to a single spectrometer to achieve cost-effective FDT. From these four phase streaks, an FDT algorithm analogous to conventional CT yields a single-shot movie of the pump's self-focusing dynamics.
Directory of Open Access Journals (Sweden)
S. I. Samsudin
2014-01-01
Full Text Available The wastewater treatment plant (WWTP is highly known with the nonlinearity of the control parameters, thus it is difficult to be controlled. In this paper, the enhancement of nonlinear PI controller (ENon-PI to compensate the nonlinearity of the activated sludge WWTP is proposed. The ENon-PI controller is designed by cascading a sector-bounded nonlinear gain to linear PI controller. The rate variation of the nonlinear gain kn is automatically updated based on adaptive interaction algorithm. Initiative to simplify the ENon-PI control structure by adapting kn has been proved by significant improvement under various dynamic influents. More than 30% of integral square error and 14% of integral absolute error are reduced compared to benchmark PI for DO control and nitrate in nitrogen removal control. Better average effluent qualities, less number of effluent violations, and lower aeration energy consumption resulted.
The dynamics of interacting nonlinearities governing long wavelength driftwave turbulence
International Nuclear Information System (INIS)
Newman, D.E.
1993-09-01
Because of the ubiquitous nature of turbulence and the vast array of different systems which have turbulent solutions, the study of turbulence is an area of active research. Much present day understanding of turbulence is rooted in the well established properties of homogeneous Navier-Stokes turbulence, which, due to its relative simplicity, allows for approximate analytic solutions. This work examines a group of turbulent systems with marked differences from Navier-Stokes turbulence, and attempts to quantify some of their properties. This group of systems represents a variety of drift wave fluctuations believed to be of fundamental importance in laboratory fusion devices. From extensive simulation of simple local fluid models of long wavelength drift wave turbulence in tokamaks, a reasonably complete picture of the basic properties of spectral transfer and saturation has emerged. These studies indicate that many conventional notions concerning directions of cascades, locality and isotropy of transfer, frequencies of fluctuations, and stationarity of saturation are not valid for moderate to long wavelengths. In particular, spectral energy transfer at long wavelengths is dominated by the E x B nonlinearity, which carries energy to short scale in a manner that is highly nonlocal and anisotropic. In marked contrast to the canonical self-similar cascade dynamics of Kolmogorov, energy is efficiently passed between modes separated by the entire spectrum range in a correlation time. At short wavelengths, transfer is dominated by the polarization drift nonlinearity. While the standard dual cascade applies in this subrange, it is found that finite spectrum size can produce cascades that are reverse directed and are nonconservative in enstrophy and energy similarity ranges. In regions where both nonlinearities are important, cross-coupling between the nolinearities gives rise to large no frequency shifts as well as changes in the spectral dynamics
International Nuclear Information System (INIS)
Zhang Jiatai
1994-01-01
From the theory of stimulated Raman scattering (SRS) three wave interaction, a new method of detecting the electron temperature in laser-plasma is obtained. SRS spectrum obtained from Shenguang No. 12 Nd-laser experiments are analysed. Using the wave length of short wave cut off of SRS, the electron temperature in corona plasma region is calculated consistently. These results agree reasonable with X-ray spectrum experiments
Dynamical interactions between solute and solvent studied by nonlinear infrared spectroscopy
International Nuclear Information System (INIS)
Ohta, K.; Tominaga, K.
2006-01-01
Interactions between solute and solvent play an important role in chemical reaction dynamics and in many relaxation processes in condensed phases. Recently third-order nonlinear infrared (IR) spectroscopy has shown to be useful to investigate solute-solvent interaction and dynamics of the vibrational transition. These studies provide detailed information on the energy relaxation of the vibrationally excited state, and the time scale and the magnitude of the time correlation functions of the vibrational frequency fluctuations. In this work we have studied vibrational energy relaxation (VER) of solutions and molecular complexes by nonlinear IR spectroscopy, especially IR pump-probe method, to understand the microscopic interactions in liquids. (authors)
Higher-Order Spectral Analysis to Identify Quadratic Nonlinearities in Fluid-Structure Interaction
Directory of Open Access Journals (Sweden)
Imran Akhtar
2018-01-01
Full Text Available Hydrodynamic forces on a structure are the manifestation of fluid-structure interaction. Since this interaction is nonlinear, these forces consist of various frequencies: fundamental, harmonics, excitation, sum, and difference of these frequencies. To analyze this phenomenon, we perform numerical simulations of the flow past stationary and oscillating cylinders at low Reynolds numbers. We compute the pressure, integrate it over the surface, and obtain the lift and drag coefficients for the two configurations: stationary and transversely oscillating cylinders. Higher-order spectral analysis is performed to investigate the nonlinear interaction between the forces. We confirmed and investigated the quadratic coupling between the lift and drag coefficients and their phase relationship. We identify additional frequencies and their corresponding energy present in the flow field that appear as the manifestation of quadratic nonlinear interaction.
Ulku, Huseyin Arda
2015-02-01
An explicit marching on-in-time (MOT) based time domain electric field volume integral equation (TDVIE) solver for characterizing electromagnetic wave interactions on scatterers with nonlinear material properties is proposed. Discretization of the unknown electric field intensity and flux density is carried out by half and full Schaubert-Wilton-Glisson basis functions, respectively. Coupled system of spatially discretized TDVIE and the nonlinear constitutive relation between the field intensity and the flux density is integrated in time to compute the samples of the unknowns. An explicit PE(CE)m scheme is used for this purpose. Explicitness allows for \\'easy\\' incorporation of the nonlinearity as a function only to be evaluated on the right hand side of the coupled system of equations. A numerical example that demonstrates the applicability of the proposed MOT scheme to analyzing electromagnetic interactions on Kerr-nonlinear scatterers is presented. © 2015 IEEE.
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Johansson, M.
1998-01-01
The dynamics of discrete two-dimensional nonlinear Schrodinger models with long-range dispersive interactions is investigated. In particular, we focus on the cases where the dispersion arises from a dipole-dipole interaction, assuming the dipole moments at each lattice site to be aligned either...
Plasma heating by non-linear wave-Plasma interaction | Echi ...
African Journals Online (AJOL)
We simulate the non-linear interaction of waves with magnetized tritium plasma with the aim of determining the parameter values that characterize the response of the plasma. The wave-plasma interaction has a non-conservative Hamiltonian description. The resulting system of Hamilton's equations is integrated numerically ...
Nonlinear interaction of Rayleigh--Taylor and shear instabilities
International Nuclear Information System (INIS)
Finn, J.M.
1993-01-01
Results on the nonlinear behavior of the Rayleigh--Taylor instability and consequent development of shear flow by the shear instability [Phys. Fluids B 4, 488 (1992)] are presented. It is found that the shear flow is generated at sufficient amplitude to reduce greatly the convective transport. For high viscosity, the time-asymptotic state consists of an equilibrium with shear flow and vortex flow (with islands, or ''cat's eyes''), or a relaxation oscillation involving an interplay between the shear instability and the Rayleigh--Taylor instability in the presence of shear. For low viscosity, the dominant feature is a high-frequency nonlinear standing wave consisting of convective vortices localized near the top and bottom boundaries. The localization of these vortices is due to the smaller shear near the boundary regions. The convective transport is largest around these convective vortices near the boundary and there is a region of good confinement near the center. The possible relevance of this behavior to the H mode and edge-localized modes (ELM's) in the tokamak edge region is discussed
Mohammad Moeini; Mehrdad Ghyabi; Kiarash Mohtasham Dolatshahi
2017-01-01
This paper investigates seismic soil-pile interaction using the Beam on Nonlinear Winkler Foundation (BNWF) approach. Three soil types are considered to cover all the possible responses, as well as nonlinear site response analysis using finite element method in OpenSees platform. Excitations at each elevation that are output of the site response analysis are used as the input excitation to the soil pile system implementing multi-support excitation method. Spectral intensities of acceleration ...
Laser-Plasma Modeling Using PERSEUS Extended-MHD Simulation Code for HED Plasmas
Hamlin, Nathaniel; Seyler, Charles
2017-10-01
We discuss the use of the PERSEUS extended-MHD simulation code for high-energy-density (HED) plasmas in modeling the influence of Hall and electron inertial physics on laser-plasma interactions. By formulating the extended-MHD equations as a relaxation system in which the current is semi-implicitly time-advanced using the Generalized Ohm's Law, PERSEUS enables modeling of extended-MHD phenomena (Hall and electron inertial physics) without the need to resolve the smallest electron time scales, which would otherwise be computationally prohibitive in HED plasma simulations. We first consider a laser-produced plasma plume pinched by an applied magnetic field parallel to the laser axis in axisymmetric cylindrical geometry, forming a conical shock structure and a jet above the flow convergence. The Hall term produces low-density outer plasma, a helical field structure, flow rotation, and field-aligned current, rendering the shock structure dispersive. We then model a laser-foil interaction by explicitly driving the oscillating laser fields, and examine the essential physics governing the interaction. This work is supported by the National Nuclear Security Administration stewardship sciences academic program under Department of Energy cooperative agreements DE-FOA-0001153 and DE-NA0001836.
Optical emission spectroscopy of carbon laser plasma ion source
Balki, Oguzhan; Rahman, Md. Mahmudur; Elsayed-Ali, Hani E.
2018-04-01
Carbon laser plasma generated by an Nd:YAG laser (wavelength 1064 nm, pulse width 7 ns, fluence 4-52 J cm-2) is studied by optical emission spectroscopy and ion time-of-flight. Up to C4+ ions are detected with the ion flux strongly dependent on the laser fluence. The increase in ion charge with the laser fluence is accompanied by observation of multicharged ion lines in the optical spectra. The time-integrated electron temperature Te is calculated from the Boltzmann plot using the C II lines at 392.0, 426.7, and 588.9 nm. Te is found to increase from ∼0.83 eV for a laser fluence of 22 J cm-2 to ∼0.90 eV for 40 J cm-2. The electron density ne is obtained from the Stark broadened profiles of the C II line at 392 nm and is found to increase from ∼ 2 . 1 × 1017cm-3 for 4 J cm-2 to ∼ 3 . 5 × 1017cm-3 for 40 J cm-2. Applying an external electric field parallel to the expanding plume shows no effect on the line emission intensities. Deconvolution of ion time-of-flight signal with a shifted Maxwell-Boltzmann distribution for each charge state results in an ion temperature Ti ∼4.7 and ∼6.0 eV for 20 and 36 J cm-2, respectively.
Electron Beam Charge Diagnostics for Laser Plasma Accelerators
Energy Technology Data Exchange (ETDEWEB)
Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Smith, Alan; Rodgers, David; Donahue, Rich; Byrne, Warren; Leemans, Wim
2011-06-27
A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). First, a scintillating screen (Lanex) was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT) for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160 pC/mm{sup 2} and 0.4 pC/(ps mm{sup 2}), respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within {+-}8%, showing that they all can provide accurate charge measurements for LPAs.
Chaotic saddles in nonlinear modulational interactions in a plasma
Miranda, Rodrigo A.; Rempel, Erico L.; Chian, Abraham C.-L.
2012-11-01
A nonlinear model of modulational processes in the subsonic regime involving a linearly unstable wave and two linearly damped waves with different damping rates in a plasma is studied numerically. We compute the maximum Lyapunov exponent as a function of the damping rates in a two-parameter space, and identify shrimp-shaped self-similar structures in the parameter space. By varying the damping rate of the low-frequency wave, we construct bifurcation diagrams and focus on a saddle-node bifurcation and an interior crisis associated with a periodic window. We detect chaotic saddles and their stable and unstable manifolds, and demonstrate how the connection between two chaotic saddles via coupling unstable periodic orbits can result in a crisis-induced intermittency. The relevance of this work for the understanding of modulational processes observed in plasmas and fluids is discussed.
The role of nonlinear coupling in Human-Horse Interaction: A preliminary study.
Lanata, Antonio; Guidi, Andrea; Valenza, Gaetano; Baragli, Paolo; Scilingo, Enzo Pasquale
2017-07-01
This study focuses on the analysis of human-horse dynamic interaction using cardiovascular information exclusively. Specifically, the Information Theoretic Learning (ITL) approach has been applied to a Human-Horse Interaction paradigm, therefore accounting for the nonlinear information of the heart-heart interplay between humans and horses. Heartbeat dynamics was gathered from humans and horses during three experimental conditions: absence of interaction, visual-olfactory interaction, and brooming. Cross Information Potential, Cross Correntropy, and Correntropy Coefficient were computed to quantitatively estimate nonlinear coupling in a group of eleven subjects and one horse. Results showed a statistical significant difference on all of the three interaction phases. Furthermore, a Support Vector Machine classifier recognized the three conditions with an accuracy of 90:9%. These preliminary and encouraging results suggest that ITL analysis provides viable metrics for the quantitative evaluation of human-horse interaction.
International Nuclear Information System (INIS)
Khalil, Sh.M.; El-Sherif, N.; El-Siragy, N.M.; Tanta Univ.; El-Naggar, I.A.; Alexandria Univ.
1985-01-01
Investigation is made for nonlinear interaction between incident radiation and a surface wave in a magnetized plasma layer. Both interacting waves are of P polarization. The generated currents and fields at combination frequencies are obtained analytically. Unlike the S-polarized interacting waves, the magnetic field affects the fundamental waves and leads to an amplification of generated waves when their frequencies approach the cyclotron frequency. (author)
Schwartz, Sylvain; Gutty, François; Feugnet, Gilles; Bouyer, Philippe; Pocholle, Jean-Paul
2008-05-09
We report fine-tuning of nonlinear interactions in a solid-state ring laser gyroscope by vibrating the gain medium along the cavity axis. We demonstrate both experimentally and theoretically that nonlinear interactions vanish for some values of the vibration parameters, leading to quasi-ideal rotation sensing. We eventually point out that our conclusions can be mapped onto other subfields of physics such as ring-shaped superfluid configurations, where nonlinear interactions could be tuned by using Feshbach resonance.
Schwartz, Sylvain; Gutty, François; Feugnet, Gilles; Bouyer, Philippe; Pocholle, Jean-Paul
2008-01-01
International audience; We study the suppression of nonlinear interactions in resonant macroscopic quantum devices in the case of the solid-state ring laser gyroscope. These nonlinear interactions are tuned by vibrating the gain medium along the cavity axis. Beat note occurrence under rotation provides a precise measurement of the strength of nonlinear interactions, which turn out to vanish for some discrete values of the amplitude of vibration. Our theoretical description, in very good agree...
International Nuclear Information System (INIS)
Yeates, P.; Kennedy, E. T.
2010-01-01
Laser plasma plumes were generated in aluminum rectangular cavities of fixed depth (6 mm) and varying height (2.0, 1.5, and 1.0 mm). Space and time resolved visible emission spectroscopy, gated intensified visible imaging, and Langmuir probe diagnostics were utilized to diagnose the evolution of the confined plasma plumes in comparison to freely expanding plasma plume generated from ablation of a planar target. The constrained plasma behavior displayed a multiphase history. Early stage interactions (t 160 ns) resulted in sustained 'decay', i.e., a rapid termination of continuum emission, in concert with decreases in peak electron density (N e ) and plasma temperature (T). This later phase originates from loss mechanisms which bleed the plasma plume of thermal energy and charged particles. These loss mechanisms increase in magnitude as the duration of the plasma-surface interaction increases. The transition from enhancement phase, originating from hydrodynamic containment, and plasma-surface collisions, to decay phase is described and occurs for each cavity at a different point in the space time history.
Veering and nonlinear interactions of a clamped beam in bending and torsion
Ehrhardt, David A.; Hill, Thomas L.; Neild, Simon A.; Cooper, Jonathan E.
2018-03-01
Understanding the linear and nonlinear dynamic behaviour of beams is critical for the design of many engineering structures such as spacecraft antennae, aircraft wings, and turbine blades. When the eigenvalues of such structures are closely-spaced, nonlinearity may lead to interactions between the underlying linear normal modes (LNMs). This work considers a clamped-clamped beam which exhibits nonlinear behaviour due to axial tension from large amplitudes of deformation. An additional cross-beam, mounted transversely and with a movable mass at each tip, allows tuning of the primary torsion LNM such that it is close to the primary bending LNM. Perturbing the location of one mass relative to that of the other leads to veering between the eigenvalues of the bending and torsion LNMs. For a number of selected geometries in the region of veering, a nonlinear reduced order model (NLROM) is created and the nonlinear normal modes (NNMs) are used to describe the underlying nonlinear behaviour of the structure. The relationship between the 'closeness' of the eigenvalues and the nonlinear dynamic behaviour is demonstrated in the NNM backbone curves, and veering-like behaviour is observed. Finally, the forced and damped dynamics of the structure are predicted using several analytical and numerical tools and are compared to experimental measurements. As well as showing a good agreement between the predicted and measured responses, phenomena such as a 1:1 internal resonance and quasi-periodic behaviour are identified.
Nonlinear disruption of ecological interactions in response to nitrogen deposition.
Ochoa-Hueso, Raúl
2016-10-01
Global environmental change (GEC) is affecting species interactions and causing a rapid decline in biodiversity. In this study, I present a new Ecosystem Disruption Index to quantify the impacts of simulated nitrogen (N) deposition (0, 10, 20, and 50 kg N·ha -1 ·yr -1 + 6-7 kg N·ha -1 ·yr -1 background) on abiotic and biotic ecological interactions. This comparative index is based on pairwise linear and quadratic regression matrices. These matrices, calculated at the N treatment level, were constructed using a range of abiotic and biotic ecosystem constituents: soil pH, shrub cover, and the first component of several separate principal component analyses using soil fertility data (total carbon and N) and community data (annual plants, microorganisms, biocrusts, edaphic fauna) for a total of seven ecosystem constituents. Four years of N fertilization in a semiarid shrubland completely disrupted the network of ecological interactions, with a greater proportional increase in ecosystem disruption at low N addition levels. Biotic interactions, particularly those involving microbes, shrubs, and edaphic fauna, were more prone to be lost in response to N, whereas interactions involving soil properties were more resilient. In contrast, edaphic fauna was the only group directly affected by N addition, with mites and collembolans increasing their abundance with up to 20 kg N·ha -1 ·yr -1 and then decreasing, which supports the idea of higher-trophic-level organisms being more sensitive to disturbance due to more complex links with other ecosystem constituents. Future experimental studies evaluating the impacts of N deposition, and possibly other GEC drivers, on biodiversity and biotic and abiotic interactions may be able to explain results more effectively in the context of ecological networks as a key feature of ecosystem sensitivity. © 2016 by the Ecological Society of America.
Electrostatic potential profile and nonlinear current in an interacting ...
Indian Academy of Sciences (India)
Unknown
Abstract. We consider an interacting one-dimensional molecular wire attached to two metal electrodes on either side of it. The electrostatic potential profile across the wire-electrode interface has been deduced solving the Schrodinger and Poisson equations self-consistently. Since the Poisson distribution crucially depends ...
Dalafi, A.; Naderi, M. H.
2017-04-01
An interacting cigar-shaped Bose-Einstein condensate (BEC) inside a driven optical cavity exhibits an intrinsic cross-Kerr (CK) nonlinearity due to the interaction with the optical mode of the cavity. Although the CK coupling is much weaker than those of the radiation pressure and the atom-atom interactions, it can affect the bistability behavior of the system when the intensity of the laser pump is strong enough. On the other hand, there is a competition between the CK nonlinearity and the atom-atom interaction so that the latter can neutralize the effect of the former. Furthermore, the CK nonlinearity causes the effective frequency of the Bogoliubov mode of the BEC as well as the quantum fluctuations of the system to be increased by increasing the cavity driving rate. However, in the dispersive interaction regime the effect of the CK nonlinearity is negligible. In addition, we show that by increasing the s -wave scattering frequency of atomic collisions one can generate a strong stationary quadrature squeezing in the Bogoliubov mode of the BEC.
Modeling classical and quantum radiation from laser-plasma accelerators
Directory of Open Access Journals (Sweden)
M. Chen
2013-03-01
Full Text Available The development of models and the “Virtual Detector for Synchrotron Radiation” (vdsr code that accurately describe the production of synchrotron radiation are described. These models and code are valid in the classical and linear (single-scattering quantum regimes and are capable of describing radiation produced from laser-plasma accelerators (LPAs through a variety of mechanisms including betatron radiation, undulator radiation, and Thomson/Compton scattering. Previous models of classical synchrotron radiation, such as those typically used for undulator radiation, are inadequate in describing the radiation spectra from electrons undergoing small numbers of oscillations. This is due to an improper treatment of a mathematical evaluation at the end points of an integration that leads to an unphysical plateau in the radiation spectrum at high frequencies, the magnitude of which increases as the number of oscillation periods decreases. This is important for betatron radiation from LPAs, in which the betatron strength parameter is large but the number of betatron periods is small. The code vdsr allows the radiation to be calculated in this regime by full integration over each electron trajectory, including end-point effects, and this code is used to calculate betatron radiation for cases of experimental interest. Radiation from Thomson scattering and Compton scattering is also studied with vdsr. For Thomson scattering, radiation reaction is included by using the Sokolov method for the calculation of the electron dynamics. For Compton scattering, quantum recoil effects are considered in vdsr by using Monte Carlo methods. The quantum calculation has been benchmarked with the classical calculation in a classical regime.
Conceptual design of a laser-plasma accelerator driven free-electron laser demonstration experiment
International Nuclear Information System (INIS)
Seggebrock, Thorben
2015-01-01
Up to now, short-wavelength free-electron lasers (FEL) have been systems on the scale of hundreds of meters up to multiple kilometers. Due to the advancements in laser-plasma acceleration in the recent years, these accelerators have become a promising candidate for driving a fifth-generation synchrotron light source - a lab-scale free-electron laser. So far, demonstration experiments have been hindered by the broad energy spread typical for this type of accelerator. This thesis addresses the most important challenges of the conceptual design for a first lab-scale FEL demonstration experiment using analytical considerations as well as simulations. The broad energy spread reduces the FEL performance directly by weakening the microbunching and indirectly via chromatic emittance growth, caused by the focusing system. Both issues can be mitigated by decompressing the electron bunch in a magnetic chicane, resulting in a sorting by energies. This reduces the local energy spread as well as the local chromatic emittance growth and also lowers performance degradations caused by the short bunch length. Moreover, the energy dependent focus position leads to a focus motion within the bunch, which can be synchronized with the radiation pulse, maximizing the current density in the interaction region. This concept is termed chromatic focus matching. A comparison shows the advantages of the longitudinal decompression concept compared to the alternative approach of transverse dispersion. When using typical laser-plasma based electron bunches, coherent synchrotron radiation and space-charge contribute in equal measure to the emittance growth during decompression. It is shown that a chicane for this purpose must not be as weak and long as affordable to reduce coherent synchrotron radiation, but that an intermediate length is required. Furthermore, the interplay of the individual concepts and components is assessed in a start-to-end simulation, confirming the feasibility of the
Electron-lattice Interaction and Nonlinear Excitations in Cuprate Structures
International Nuclear Information System (INIS)
Paulsen, J.; Eschrig, H.; Drechsler, S.L.; Malek, J.
1995-01-01
A low temperature lattice modulation of the chains of the YBa 2 Cu 3 O 7 is considered by deriving a Hamiltonian of electron-lattice interaction from density-functional calculations for deformed lattice and solving it for the groundstate. Hubbard-type Coulomb interaction is included. The obtained groundstate is a charge-density-wave state with a pereodicity of four lattice constants and a gap for one-electron excitations of about 1eV, sensitively depending on parameters of the Hamiltonian. There are lots of polaronic and solitonic excitations with formation energies deep in the gap, which can pin the Fermi level and thus produce again metallicity of the chain. They might also contribute to pairing of holes in adjacent CuO 2 -planes. (author)
Entanglement of a nonlinear two two-level atoms interacting with ...
Indian Academy of Sciences (India)
S Abdel-Khalek
2017-12-08
Dec 8, 2017 ... Abstract. In this paper we investigate the entanglement dynamics between two two-level atoms interacting with two coherent fields in two spatially separated cavities which are filled with a Kerr-like medium. We examine the effect of nonlinear medium on the dynamical properties of entanglement and atomic ...
Interaction-induced effects in the nonlinear coherent response of quantum-well excitons
DEFF Research Database (Denmark)
Wagner, Hans Peter; Schätz, A.; Langbein, Wolfgang Werner
1999-01-01
Interaction-induced processes are studied using the third-order nonlinear polarization created in polarization-dependent four-wave-mixing experiments (FWM) on a ZnSe single quantum well. We discuss their influence by a comparison of the experimental FWM with calculations based on extended optical...
Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zheng, Huinan; Shen, Chao; Wang, Yuming; Wang, Shui
2013-06-01
Electromagnetic ion cyclotron (EMIC) waves are long suggested to account for the rapid loss of radiation belt relativistic electrons. Here we perform both theoretical analysis and numerical simulation to comprehensively investigate the nonlinear interaction between EMIC wave and relativistic electrons. In particular, we emphasize the dependence of nonlinear processes on the electron initial latitude. The nonlinear phase trapping yields negative equatorial pitch angle transport, with efficiency varying over the electron initial latitude, implying that it can increase the loss rate predicted by quasilinear theory. The nonlinear channel effect phase bunching produces positive equatorial pitch angle transport, less dependent on the electron initial latitude, suggesting that it can decrease the loss rate predicted by quasilinear theory. The nonlinear cluster effect phase bunching alternately causes positive and negative equatorial pitch angle transport, quasi-periodically dependent on the electron initial latitude, suggesting that it can either decrease or increase the loss rate predicted by the quasilinear theory. Such latitudinal dependence of nonlinear processes should be taken into account in the evaluation of radiation belt electron loss rate driven by EMIC waves.
Nonlinear resonant interaction between acoustic impulse and electrons in superconductors
International Nuclear Information System (INIS)
Bratus, E.N.; Shumeiko, V.S.
1985-01-01
The problem of inelastic electron interaction in a perfectly pure superconductor with a longitudinal sound impulse is considered. It is shown that the problem reduces to the equivalent one of elastic scattering by the static potential, and the sound absorption is expressed in terms of the reflection coefficient of this scattering. The classical and quantum properties of the scattering are studied and the phase region in which new excitations are created is indicated. A formula is derived that expresses the density matrix of the excitations created in terms of the exact scattering matrix of an impulse. The quasiclassical creation of excitations by a smooth-shaped impulse is investigated with regard to both overbarrier and underbarrier processes
Study on concentration nonlinearity of interacting acoustic flows in cadmium sulfide and tellurium
International Nuclear Information System (INIS)
Ilisavskij, Yu.V.; Kulakova, L.A.; Yakhkind, Eh.Z.
1976-01-01
The ratio of an one-mode (self-action of an external monochromatic sound wave) and a many-mode (interaction of an external wave with crystal thermal phonons) concentration nonlinearity has been experimentally investigated on sound amplification in cadmium sulphide and tellurium. It has been shown that in a strong piezoelectric the main part in the nonlinear limitation of the sound amplification in a drift field is played by the wave interaction, i.e., the transfer of the sound wave energy into the crystal sound modes starts before the nonlinear self-action of a wave. In Te characterized by a large value of the electromechanical coupling constant value at the sound frequency of about 250 MHz the threshold of many-mode nonlinearity is achieved in fields much below the critical one, and corresponds to the sound intensity as low as 10 -7 W/cm 2 , as compared with 10 -2 W/cm 2 -the threshold of the one-mode nonlinearity
Role of Density Profiles for the Nonlinear Propagation of Intense Laser Beam through Plasma Channel
Directory of Open Access Journals (Sweden)
Sonu Sen
2014-01-01
Full Text Available In this work role of density profiles for the nonlinear propagation of intense laser beam through plasma channel is analyzed. By employing the expression for the dielectric function of different density profile plasma, a differential equation for beamwidth parameter is derived under WKB and paraxial approximation. The laser induces modifications of the dielectric function through nonlinearities. It is found that density profiles play vital role in laser-plasma interaction studies. To have numerical appreciation of the results the propagation equation for plasma is solved using the fourth order Runge-Kutta method for the initial plane wave front of the beam, using boundary conditions. The spot size of the laser beam decreases as the beam penetrates into the plasma and significantly adds self-focusing in plasma. This causes the laser beam to become more focused by reduction of diffraction effect, which is an important phenomenon in inertial confinement fusion and also for the understanding of self-focusing of laser pulses. Numerical computations are presented and discussed in the form of graphs for typical parameters of laser-plasma interaction.
Entanglement of a nonlinear two two-level atoms interacting with deformed fields in Kerr medium
Abdel-Khalek, S.; El-Saman, Y. S.; Abdel-Aty, M.
2018-01-01
In this paper we investigate the entanglement dynamics between two two-level atoms interacting with two coherent fields in two spatially separated cavities which are filled with a Kerr-like medium. We examine the effect of nonlinear medium on the dynamical properties of entanglement and atomic occupation probabilities in the case of even and odd deformed coherent states. The results show that the deformed fields play important roles in the evolution of entanglement. Also, the results demonstrate that entanglement sudden death, sudden birth and long-distance can be controlled by the deformation and nonlinear parameters.
Shen, Yanfeng; Cesnik, Carlos E. S.
2016-04-01
This paper presents a parallelized modeling technique for the efficient simulation of nonlinear ultrasonics introduced by the wave interaction with fatigue cracks. The elastodynamic wave equations with contact effects are formulated using an explicit Local Interaction Simulation Approach (LISA). The LISA formulation is extended to capture the contact-impact phenomena during the wave damage interaction based on the penalty method. A Coulomb friction model is integrated into the computation procedure to capture the stick-slip contact shear motion. The LISA procedure is coded using the Compute Unified Device Architecture (CUDA), which enables the highly parallelized supercomputing on powerful graphic cards. Both the explicit contact formulation and the parallel feature facilitates LISA's superb computational efficiency over the conventional finite element method (FEM). The theoretical formulations based on the penalty method is introduced and a guideline for the proper choice of the contact stiffness is given. The convergence behavior of the solution under various contact stiffness values is examined. A numerical benchmark problem is used to investigate the new LISA formulation and results are compared with a conventional contact finite element solution. Various nonlinear ultrasonic phenomena are successfully captured using this contact LISA formulation, including the generation of nonlinear higher harmonic responses. Nonlinear mode conversion of guided waves at fatigue cracks is also studied.
Statistical analysis of nonlinear wave interactions in simulated Langmuir turbulence data
Directory of Open Access Journals (Sweden)
J. Soucek
2003-03-01
Full Text Available We present a statistical analysis of strong turbulence of Langmuir and ion-sound waves resulting from beam-plasma interaction. The analysis is carried out on data sets produced by a numerical simulation of one-dimensional Zakharov’s equations. The nonlinear wave interactions are studied using two different approaches: high-order spectra and Volterra models. These methods were applied to identify two and three wave processes in the data, and the Volterra model was furthermore employed to evaluate the direction and magnitude of energy transfer between the wave modes in the case of Langmuir wave decay. We demonstrate that these methods allow one to determine the relative importance of strongly and weakly turbulent processes. The statistical validity of the results was thoroughly tested using surrogated data set analysis.Key words. Space plasma physics (wave-wave interactions; experimental and mathematical techniques; nonlinear phenomena
Optical diagnostics of lead and PbGa2S4 layered crystal laser plasmas
International Nuclear Information System (INIS)
Shuaibov, A.K.; Dashchenko, A.I.; Shevera, I.V.
2001-01-01
Paper presents the results of the optic diagnostics of plasma of laser flames formed from lead surface and PbGa 2 S 4 laminar crystal using a neodymium laser. It is shown that the most intensive lines in the lead laser plasma are as follows: 405.7, 368.3, 364.0 nm PbI and 220.4 nm PbII while for the laminar crystal base plasma - the combination of the most intensive lines of PbI and GaI emission. One determined the narrow point of recombination fluxes for the ion and the atomic components of laser plasma of lead and of PbGa 2 S 4 crystal. One conducted comparison study of emission dynamics of PbI and GaI lines in laser plasma of the respective metals and of PbGa 2 S 4 crystal [ru
Energy Technology Data Exchange (ETDEWEB)
Bhaumik, Lopamudra, E-mail: lbhaumi2@illinois.edu [University of Illinois at Urbana-Champaign (United States); Raychowdhury, Prishati, E-mail: prishati@iitk.ac.in [Indian Institute of Technology Kanpur (India)
2013-12-15
Highlights: • Seismic response analysis of an internal shearwall of a reactor is done. • Incremental dynamic analysis is performed with 30 recorded ground motions. • Equivalent viscous damping increases up to twice when nonlinear SSI is considered. • Roof drift demand increases up to 25% upon consideration of foundation nonlinearity. • Base shear, base moment and ductility reduce up to 62%, 40%, and 35%, respectively. - Abstract: This study focuses on the seismic response analysis of an internal shearwall of a typical Indian reactor resting on a medium dense sandy silty soil, incorporating the nonlinear behavior of the soil-foundation interface. The modeling is done in an open-source finite element framework, OpenSees, where the soil-structure interaction (SSI) is modeled using a Beam-on-Nonlinear-Winkler-Foundation (BNWF) approach. Static pushover analysis and cyclic analysis are performed followed by an incremental dynamic analysis (IDA) with 30 recorded ground motions. For performing IDA, the spectral acceleration of each motion corresponding to the fundamental period, S{sub a}(T{sub 1})is incremented from 0.1 g to 1.0 g with an increment step of 0.1 g. It is observed from the cyclic analysis that the equivalent viscous damping of the system increases upto twice upon incorporation of inelastic SSI. The IDA results demonstrate that the average peak base shear, base moment and displacement ductility demand reduces as much as 62%, 40%, and 35%, respectively, whereas the roof drift demand increases up to 25% upon consideration of foundation nonlinearity for the highest intensity motion. These observations indicate the need of critical consideration of nonlinear soil-structure interaction as any deficient modeling of the same may lead to an inaccurate estimation of the seismic demands of the structure.
Three-wave interaction in two-component quadratic nonlinear lattices
DEFF Research Database (Denmark)
Konotop, V. V.; Cunha, M. D.; Christiansen, Peter Leth
1999-01-01
We investigate a two-component lattice with a quadratic nonlinearity and find with the multiple scale technique that integrable three-wave interaction takes place between plane wave solutions when these fulfill resonance conditions. We demonstrate that. energy conversion and pulse propagation known...... from three-wave interaction is reproduced in the lattice and that exact phase matching of parametric processes can be obtained in non-phase-matched lattices by tilting the interacting plane waves with respect to each other. [S1063-651X(99)15110-9]....
Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators
International Nuclear Information System (INIS)
Osterhoff, Jens; Sokollik, Thomas; Nakamura, Kei; Bakeman, Michael; Weingartner, R.; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; vanTilborg, Jeroen; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Toth, Csaba; DeSantis, Stefano; Byrd, John; Gruner, F.; Leemans, Wim
2011-01-01
The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.
Wave–vortex interactions in the nonlinear Schrödinger equation
Energy Technology Data Exchange (ETDEWEB)
Guo, Yuan, E-mail: yuanguo@cims.nyu.edu; Bühler, Oliver [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2014-02-15
This is a theoretical study of wave–vortex interaction effects in the two-dimensional nonlinear Schrödinger equation, which is a useful conceptual model for the limiting dynamics of superfluid quantum condensates at zero temperature. The particular wave–vortex interaction effects are associated with the scattering and refraction of small-scale linear waves by the straining flows induced by quantized point vortices and, crucially, with the concomitant nonlinear back-reaction, the remote recoil, that these scattered waves exert on the vortices. Our detailed model is a narrow, slowly varying wavetrain of small-amplitude waves refracted by one or two vortices. Weak interactions are studied using a suitable perturbation method in which the nonlinear recoil force on the vortex then arises at second order in wave amplitude, and is computed in terms of a Magnus-type force expression for both finite and infinite wavetrains. In the case of an infinite wavetrain, an explicit asymptotic formula for the scattering angle is also derived and cross-checked against numerical ray tracing. Finally, under suitable conditions a wavetrain can be so strongly refracted that it collapses all the way onto a zero-size point vortex. This is a strong wave–vortex interaction by definition. The conditions for such a collapse are derived and the validity of ray tracing theory during the singular collapse is investigated.
Wave-vortex interactions in the nonlinear Schrödinger equation
Guo, Yuan; Bühler, Oliver
2014-02-01
This is a theoretical study of wave-vortex interaction effects in the two-dimensional nonlinear Schrödinger equation, which is a useful conceptual model for the limiting dynamics of superfluid quantum condensates at zero temperature. The particular wave-vortex interaction effects are associated with the scattering and refraction of small-scale linear waves by the straining flows induced by quantized point vortices and, crucially, with the concomitant nonlinear back-reaction, the remote recoil, that these scattered waves exert on the vortices. Our detailed model is a narrow, slowly varying wavetrain of small-amplitude waves refracted by one or two vortices. Weak interactions are studied using a suitable perturbation method in which the nonlinear recoil force on the vortex then arises at second order in wave amplitude, and is computed in terms of a Magnus-type force expression for both finite and infinite wavetrains. In the case of an infinite wavetrain, an explicit asymptotic formula for the scattering angle is also derived and cross-checked against numerical ray tracing. Finally, under suitable conditions a wavetrain can be so strongly refracted that it collapses all the way onto a zero-size point vortex. This is a strong wave-vortex interaction by definition. The conditions for such a collapse are derived and the validity of ray tracing theory during the singular collapse is investigated.
Harmonic Propagation and Interaction Evaluation between Small-Scale Wind Farms and Nonlinear Loads
Directory of Open Access Journals (Sweden)
Cheng-Xiong Mao
2013-07-01
Full Text Available Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P – Q(V nodes, the paper discusses the expanding Newton-Raphson power flow method for the wind farm. Then the generalized gamma mixture models are proposed to study the non-characteristic harmonic propagation of the wind farm, which are based on Gaussian mixture models, improved phasor clustering and generalized Gamma models. After the integration of the small-scale wind farm, harmonic emissions of nonlinear loads will become random and fluctuating due to the non-stationary wind power. Furthermore, in this paper the harmonic coupled admittance matrix model of nonlinear loads combined with a wind farm is deduced by rigorous formulas. Then the harmonic propagation and interaction between a real wind farm and nonlinear loads are analyzed by the harmonic coupled admittance matrix and generalized gamma mixture models. Finally, the proposed models and methods are verified through the corresponding simulation models in MATLAB/SIMULINK and PSCAD/EMTDC.
Nonlinear soil-structure interaction analysis of SIMQUAKE II. Final report
International Nuclear Information System (INIS)
Vaughan, D.K.; Isenberg, J.
1982-04-01
This report describes an analytic method for modeling of soil-structure interaction (SSI) for nuclear power plants in earthquakes and discusses its application to SSI analyses of SIMQUAKE II. The method is general and can be used to simulate a three-dimensional structural geometry, nonlinear site characteristics and arbitrary input ground shaking. The analytic approach uses the soil island concept to reduce SSI models to manageable size and cost. Nonlinear constitutive behavior of the soil is represented by the nonlinear, kinematic cap model. In addition, a debonding-rebonding soil-structure interface model is utilized to represent nonlinear effects which singificantly alter structural response in the SIMQUAKE tests. STEALTH, an explicit finite difference code, is used to perform the dynamic, soil-structure interaction analyses. Several two-dimensional posttest SSI analyses of model containment structures in SIMQUAKE II are performed and results compared with measured data. These analyses qualify the analytic method. They also show the importance of including debonding-rebonding at the soil-structure interface. Sensitivity of structural response to compaction characteristics of backfill material is indicated
Siminos, E; Sánchez-Arriaga, G; Saxena, V; Kourakis, I
2014-12-01
We investigate the dynamics of localized solutions of the relativistic cold-fluid plasma model in the small but finite amplitude limit, for slightly overcritical plasma density. Adopting a multiple scale analysis, we derive a perturbed nonlinear Schrödinger equation that describes the evolution of the envelope of circularly polarized electromagnetic field. Retaining terms up to fifth order in the small perturbation parameter, we derive a self-consistent framework for the description of the plasma response in the presence of localized electromagnetic field. The formalism is applied to standing electromagnetic soliton interactions and the results are validated by simulations of the full cold-fluid model. To lowest order, a cubic nonlinear Schrödinger equation with a focusing nonlinearity is recovered. Classical quasiparticle theory is used to obtain analytical estimates for the collision time and minimum distance of approach between solitons. For larger soliton amplitudes the inclusion of the fifth-order terms is essential for a qualitatively correct description of soliton interactions. The defocusing quintic nonlinearity leads to inelastic soliton collisions, while bound states of solitons do not persist under perturbations in the initial phase or amplitude.
Ulku, Huseyin Arda
2014-07-06
Effects of material nonlinearities on electromagnetic field interactions become dominant as field amplitudes increase. A typical example is observed in plasmonics, where highly localized fields “activate” Kerr nonlinearities. Naturally, time domain solvers are the method of choice when it comes simulating these nonlinear effects. Oftentimes, finite difference time domain (FDTD) method is used for this purpose. This is simply due to the fact that explicitness of the FDTD renders the implementation easier and the material nonlinearity can be easily accounted for using an auxiliary differential equation (J.H. Green and A. Taflove, Opt. Express, 14(18), 8305-8310, 2006). On the other hand, explicit marching on-in-time (MOT)-based time domain integral equation (TDIE) solvers have never been used for the same purpose even though they offer several advantages over FDTD (E. Michielssen, et al., ECCOMAS CFD, The Netherlands, Sep. 5-8, 2006). This is because explicit MOT solvers have never been stabilized until not so long ago. Recently an explicit but stable MOT scheme has been proposed for solving the time domain surface magnetic field integral equation (H.A. Ulku, et al., IEEE Trans. Antennas Propag., 61(8), 4120-4131, 2013) and later it has been extended for the time domain volume electric field integral equation (TDVEFIE) (S. B. Sayed, et al., Pr. Electromagn. Res. S., 378, Stockholm, 2013). This explicit MOT scheme uses predictor-corrector updates together with successive over relaxation during time marching to stabilize the solution even when time step is as large as in the implicit counterpart. In this work, an explicit MOT-TDVEFIE solver is proposed for analyzing electromagnetic wave interactions on scatterers exhibiting Kerr nonlinearity. Nonlinearity is accounted for using the constitutive relation between the electric field intensity and flux density. Then, this relation and the TDVEFIE are discretized together by expanding the intensity and flux - sing half
Laser Plasmas: Optical guiding of laser beam in nonuniform plasma
Indian Academy of Sciences (India)
We have solved the nonlinear parabolic partial differential equation governing the propagation characteristics for an approximate analytical solution using variational approach. Results are compared with the theoretical model of Liu and Tripathi (Phys. Plasmas 1, 3100 (1994)) based on paraxial ray approximation.
An explicit method in non-linear soil-structure interaction
International Nuclear Information System (INIS)
Kunar, R.R.
1981-01-01
The explicit method of analysis in the time domain is ideally suited for the solution of transient dynamic non-linear problems. Though the method is not new, its application to seismic soil-structure interaction is relatively new and deserving of public discussion. This paper describes the principles of the explicit approach in soil-structure interaction and it presents a simple algorithm that can be used in the development of explicit computer codes. The paper also discusses some of the practical considerations like non-reflecting boundaries and time steps. The practicality of the method is demonstrated using a computer code, PRESS, which is used to compare the treatment of strain-dependent properties using average strain levels over the whole time history (the equivalent linear method) and using the actual strain levels at every time step to modify the soil properties (non-linear method). (orig.)
Statistical analysis of nonlinear wave interaction in simulated Langmuir turbulence data
Czech Academy of Sciences Publication Activity Database
Souček, Jan; Dudok de Wit, T.; Krasnoselskikh, V.; Volokitin, A.
2003-01-01
Roč. 21, - (2003), s. 681-692 ISSN 0992-7689 R&D Projects: GA ČR GA205/01/1064 Grant - others:CNRS(FR) PICS 1175 Institutional research plan: CEZ:AV0Z3042911 Keywords : space plasma physics * wave-wave interactions * experimental and matehmatical techniques * nonlinear phenomena Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.031, year: 2003
International Nuclear Information System (INIS)
El Naggar, I.A.; Hussein, A.M.; Khalil, Sh.M.
1992-09-01
Electromagnetic waves radiated with combination frequencies from a semi-bounded plasma due to nonlinear interaction of radiation with surface wave (both of P-polarization) has been investigated. Waves are radiated both into vacuum and plasma are found to be P-polarized. We take into consideration the continuity at the plasma boundary of the tangential components of the electric field of the waves. The case of normal incidence of radiation and rarefield plasma layer is also studied. (author). 7 refs
Multi-scale-nonlinear interactions among micro-turbulence, magnetic islands, and zonal flows
International Nuclear Information System (INIS)
Ishizawa, A.; Nakajima, N.; Okamoto, M.; Ramos, J.J.
2006-10-01
We investigate multi-scale-nonlinear interactions among micro-instabilities, macro-scale tearing instabilities and zonal flows, by solving reduced two-fluid equations numerically. We find that the nonlinear interactions of these instabilities trigger macro-scale MHD activity after an equilibrium is formed by a balance between the micro-turbulence and zonal flow. This MHD activity breaks magnetic surfaces then this breaking spreads the micro-turbulence over the plasma. These multi-scale-nonlinear interactions can explain the evolution of fluctuation observed in torus plasma experiments because micro-turbulence and MHD instabilities usually appear in the plasma at the same time, in spite of the fact that effects of micro-turbulence and MHD instabilities on plasma confinement have been investigated separately. For instance, MHD activities are observed in reversed shear tokamak plasmas with a transport barrier related to zonal flows and micro-turbulence, and micro-turbulence is observed in Large Helical Device plasmas that usually exhibit MHD activities. (author)
Zeng, Shihao; Chen, Manna; Zhang, Ting; Hu, Wei; Guo, Qi; Lu, Daquan
2018-01-01
We illuminate an analytical model of soliton interactions in lead glass by analogizing to a gravitational force system. The orbits of spiraling solitons under a long-range interaction are given explicitly and demonstrated to follow Newton's second law of motion and the Binet equation by numerical simulations. The condition for circular orbits is obtained and the oscillating orbits are proved not to be closed. We prove the analogy between the nonlocal nonlinear optical system and gravitational system and specify the quantitative relation of the quantity between the two models.
Uniform strongly interacting soliton gas in the frame of the Nonlinear Schrodinger Equation
Gelash, Andrey; Agafontsev, Dmitry
2017-04-01
The statistical properties of many soliton systems play the key role in the fundamental studies of integrable turbulence and extreme sea wave formation. It is well known that separated solitons are stable nonlinear coherent structures moving with constant velocity. After collisions with each other they restore the original shape and only acquire an additional phase shift. However, at the moment of strong nonlinear soliton interaction (i.e. when solitons are located close) the wave field are highly complicated and should be described by the theory of inverse scattering transform (IST), which allows to integrate the KdV equation, the NLSE and many other important nonlinear models. The usual approach of studying the dynamics and statistics of soliton wave field is based on relatively rarefied gas of solitons [1,2] or restricted by only two-soliton interactions [3]. From the other hand, the exceptional role of interacting solitons and similar coherent structures - breathers in the formation of rogue waves statistics was reported in several recent papers [4,5]. In this work we study the NLSE and use the most straightforward and general way to create many soliton initial condition - the exact N-soliton formulas obtained in the theory of the IST [6]. We propose the recursive numerical scheme for Zakharov-Mikhailov variant of the dressing method [7,8] and discuss its stability with respect to increasing the number of solitons. We show that the pivoting, i.e. the finding of an appropriate order for recursive operations, has a significant impact on the numerical accuracy. We use the developed scheme to generate statistical ensembles of 32 strongly interacting solitons, i.e. solve the inverse scattering problem for the high number of discrete eigenvalues. Then we use this ensembles as initial conditions for numerical simulations in the box with periodic boundary conditions and study statics of obtained uniform strongly interacting gas of NLSE solitons. Author thanks the
A review of low density porous materials used in laser plasma experiments
Nagai, Keiji; Musgrave, Christopher S. A.; Nazarov, Wigen
2018-03-01
This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists' point of view to aid physicists and the new comers to this field.
Laser Plasma Plume Kinetic Spectroscopy of the Nitrogen and Carbon Species
Czech Academy of Sciences Publication Activity Database
Zelinger, Zdeněk; Novotný, Michal; Bulíř, Jiří; Lančok, Ján; Kubát, Pavel; Jelínek, Miroslav
2003-01-01
Roč. 43, - (2003), s. 426-432 ISSN 0863-1042 R&D Projects: GA AV ČR IAA1010110 Institutional research plan: CEZ:AV0Z4040901 Keywords : laser ablation * laser plasma * emission spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.863, year: 2003
High Repetition Rate Krf Laser Plasma X-Ray Source for Microlithography
F. Bijkerk,; E. Louis,; Turcu, E. C. I.; Tallents, G. J.
1992-01-01
As part of a development programme for a high-intensity laser-plasma X-ray source, experiments have been carried out using a high repetition rate excimer laser (up to 100 Hz; 249 nm, 300 mJ). Remedies are given to problems inherent to operating this type of source at high repetition rates. The
Periodic nonlinear waves resulting from the contact interaction of a crack
Lee, Sang Eon; Jin, Suyeong; Hong, Jung-Wuk
2017-09-01
When two different inputs of distinct low and high frequencies are applied to a medium, the linear responses are composed of waves of two dominant frequencies. However, microcracks such as fatigue cracks generate nonlinear waves by modulating the characteristics of the incident waves. Although this phenomenon has been observed and used to detect microcracks, the underlying principles have not been thoroughly elucidated. The hysteresis properties were introduced to describe the nonlinear relationship between the stress and strain to explain these phenomena [Van Den Abeele et al., Res. Nondestruct. Eval. 12, 17 (2000) and Nazarov et al., Acoust. Phys. 49, 344 (2003)]. The generation of harmonics was explained by superimposing stress-strain relations that vary with crack width and excitation magnitude. As the crack depth increases, the ratio of magnitudes of the second harmonic to the first harmonic increases, but the increment becomes smaller [Kawashima et al., Ultrasonics 40, 611 (2002)]. Here, we show that the waves affected by the contact motion of the crack surfaces cultivate the nonlinearity in waveforms, resulting in high frequency off-band signals. With the hypothesis that the clapping of cracks might generate nonlinear components close to the high excitation frequency, we prove that the generation of the high frequency off-band peaks is directly affected by the clapping contact interaction of the crack surfaces. The amount of energy transmitted is closely related to the size of the crack width and the magnitudes of low and high frequency excitations.
Soliton interactions and complexes for coupled nonlinear Schrödinger equations.
Jiang, Yan; Tian, Bo; Liu, Wen-Jun; Sun, Kun; Li, Min; Wang, Pan
2012-03-01
Under investigation in this paper are the coupled nonlinear Schrödinger (CNLS) equations, which can be used to govern the optical-soliton propagation and interaction in such optical media as the multimode fibers, fiber arrays, and birefringent fibers. By taking the 3-CNLS equations as an example for the N-CNLS ones (N≥3), we derive the analytic mixed-type two- and three-soliton solutions in more general forms than those obtained in the previous studies with the Hirota method and symbolic computation. With the choice of parameters for those soliton solutions, soliton interactions and complexes are investigated through the asymptotic and graphic analysis. Soliton interactions and complexes with the bound dark solitons in a mode or two modes are observed, including that (i) the two bright solitons display the breatherlike structures while the two dark ones stay parallel, (ii) the two bright and dark solitons all stay parallel, and (iii) the states of the bound solitons change from the breatherlike structures to the parallel one even with the distance between those solitons smaller than that before the interaction with the regular one soliton. Asymptotic analysis is also used to investigate the elastic and inelastic interactions between the bound solitons and the regular one soliton. Furthermore, some discussions are extended to the N-CNLS equations (N>3). Our results might be helpful in such applications as the soliton switch, optical computing, and soliton amplification in the nonlinear optics.
Directory of Open Access Journals (Sweden)
James Sae Siew
2015-01-01
Full Text Available Rail turnouts are built to enable flexibility in the rail network as they allow for vehicles to switch between various tracks, therefore maximizing the utilisation of existing rail infrastructure. In general, railway turnouts are a safety-critical and expensive feature to a rail system as they suffer aggressive operational loads, in comparison to a plain rail track, and thus require frequent monitoring and maintenance. In practice, great consideration is given to the dynamic interaction between the turnouts components as a failed component may have adverse effects on the performance of neighbouring components. This paper presents a nonlinear 3D finite element (FE model, taking into account the nonlinearities of materials, in order to evaluate the interaction and behaviour of turnout components. Using ABAQUS, the finite element model was developed to simulate standard concrete bearers with 60 kg/m rail and with a tangential turnout radius of 250 m. The turnout structure is supported by a ballast layer, which is represented by a nonlinearly deformable tensionless solid. The numerical studies firstly demonstrate the importance of load transfer mechanisms in the failure modes of the turnout components. The outcome will lead to a better design and maintenance of railway turnouts, improving public safety and operational reliability.
Modeling Laterally Loaded Single Piles Accounting for Nonlinear Soil-Pile Interactions
Directory of Open Access Journals (Sweden)
Maryam Mardfekri
2013-01-01
Full Text Available The nonlinear behavior of a laterally loaded monopile foundation is studied using the finite element method (FEM to account for soil-pile interactions. Three-dimensional (3D finite element modeling is a convenient and reliable approach to account for the continuity of the soil mass and the nonlinearity of the soil-pile interactions. Existing simple methods for predicting the deflection of laterally loaded single piles in sand and clay (e.g., beam on elastic foundation, p-y method, and SALLOP are assessed using linear and nonlinear finite element analyses. The results indicate that for the specific case considered here the p-y method provides a reasonable accuracy, in spite of its simplicity, in predicting the lateral deflection of single piles. A simplified linear finite element (FE analysis of piles, often used in the literature, is also investigated and the influence of accounting for the pile diameter in the simplified linear FE model is evaluated. It is shown that modeling the pile as a line with beam-column elements results in a reduced contribution of the surrounding soil to the lateral stiffness of the pile and an increase of up to 200% in the predicted maximum lateral displacement of the pile head.
International Nuclear Information System (INIS)
Spears, Robert Edward; Coleman, Justin Leigh
2015-01-01
Currently the Department of Energy (DOE) and the nuclear industry perform seismic soil-structure interaction (SSI) analysis using equivalent linear numerical analysis tools. For lower levels of ground motion, these tools should produce reasonable in-structure response values for evaluation of existing and new facilities. For larger levels of ground motion these tools likely overestimate the in-structure response (and therefore structural demand) since they do not consider geometric nonlinearities (such as gaping and sliding between the soil and structure) and are limited in the ability to model nonlinear soil behavior. The current equivalent linear SSI (SASSI) analysis approach either joins the soil and structure together in both tension and compression or releases the soil from the structure for both tension and compression. It also makes linear approximations for material nonlinearities and generalizes energy absorption with viscous damping. This produces the potential for inaccurately establishing where the structural concerns exist and/or inaccurately establishing the amplitude of the in-structure responses. Seismic hazard curves at nuclear facilities have continued to increase over the years as more information has been developed on seismic sources (i.e. faults), additional information gathered on seismic events, and additional research performed to determine local site effects. Seismic hazard curves are used to develop design basis earthquakes (DBE) that are used to evaluate nuclear facility response. As the seismic hazard curves increase, the input ground motions (DBE's) used to numerically evaluation nuclear facility response increase causing larger in-structure response. As ground motions increase so does the importance of including nonlinear effects in numerical SSI models. To include material nonlinearity in the soil and geometric nonlinearity using contact (gaping and sliding) it is necessary to develop a nonlinear time domain methodology. This
Nonlinear acoustoelectric interactions in GaAs/LiNbO3 structures
Rotter, M.; Wixforth, A.; Govorov, A. O.; Ruile, W.; Bernklau, D.; Riechert, H.
1999-08-01
Surface acoustic waves accompanied by very large piezoelectric fields can be created in a semiconductor/piezoelectric hybrid system. Such intense waves interact with the mobile carries in semiconductor quantum well structures in a manner being strongly governed by nonlinear effects. At high sound intensities, a formerly homogeneous two-dimensional electron system breaks up into well confined stripes surfing the wave. As a result, we observe a strong reduction of electronic sound attenuation. On the other hand, large momentum transfer between the electron system and the wave results in nonlinear acoustoelectric effects and acoustoelectric amplification. We describe our experimental findings in terms of a generalized theory of the acoustoelectric effect and discuss the importance for possible device applications.
Complete elimination of nonlinear light-matter interactions with broadband ultrafast laser pulses
DEFF Research Database (Denmark)
Shu, Chuan-Cun; Dong, Daoyi; Petersen, Ian R.
2017-01-01
optical effects, however, the probability of pure single-photon absorption is usually very low, which is particularly pertinent in the case of strong ultrafast laser pulses with broad bandwidth. Here we demonstrate theoretically a counterintuitive coherent single-photon absorption scheme by eliminating...... nonlinear interactions of ultrafast laser pulses with quantum systems. That is, a completely linear response of the system with respect to the spectral energy density of the incident light at the transition frequency can be obtained for all transition probabilities between 0 and 100% in multilevel quantum...... systems. To that end, a multiobjective optimization algorithm is developed to find an optimal spectral phase of an ultrafast laser pulse, which is capable of eliminating all possible nonlinear optical responses while maximizing the probability of single-photon absorption between quantum states. This work...
International Nuclear Information System (INIS)
Mirzade, F. Kh.
2006-01-01
A system of equations is formulated to describe the self-consistent behavior of elastic displacement fields and the concentration field of point defects in irradiated crystals with a symmetry center (germanium, silicon). In accordance with the values of the defect relaxation times, the model evolution equations are derived, describing the steady-state nonlinear longitudinal waves, with regard to the flexoelectric effect. The effect is due to the dielectric polarization induced by nonuniform elastic deformations of the lattice. For a particular relationship between the coefficients of these equations, i.e., between the parameters of the subsystem of defects and those of the nonlinear elastic medium, the exact solutions are obtained, which describe the generation of solitons and low-intensity shock waves. The contributions of the strain-defect interaction and the flexoelectric effect to the linear velocity of sound and the dispersion properties of the medium are estimated
REALISTIC NON-LINEAR MODEL AND FIELD QUALITY ANALYSIS IN RHIC INTERACTION REGIONS.
Energy Technology Data Exchange (ETDEWEB)
BEEBE-WANG,J.; JAIN, A.
2007-06-25
The existence of multipole components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. So, a realistic non-linear model is crucial for understanding the beam behavior and to achieve the ultimate performance in RHIC. A procedure is developed to build a non-linear model using the available multipole component data obtained from measurements of RHIC magnets. We first discuss the measurements performed at different stages of manufacturing of the magnets in relation to their current state in RHIC. We then describe the procedure to implement these measurement data into tracking models, including the implementation of the multipole feed down effect due to the beam orbit offset from the magnet center. Finally, the field quality analysis in the RHIC interaction regions (IR) is presented.
3D non-linear time domain FEM–BEM approach to soil–structure interaction problems
Romero Ordóñez, Antonio; Galvín, Pedro; Domínguez Abascal, José
2013-01-01
Dynamic soil-structure interaction is concerned with the study of structures supported on ﬂexible soils and subjected to dynamic actions. Methods combining the ﬁnite element method (FEM) and the boundary element method (BEM) are well suited to address dynamic soil-structure interaction problems. Hence, FEM-BEM models have been widely used. However, non-linear contact conditions and non-linear behaviour of the structures have not usually been considered in the analyses. This paper ...
2015-09-30
Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves Lian Shen St. Anthony Falls Laboratory and Department of Mechanical...on studying surface gravity wave evolution and spectrum in the presence of surface currents caused by strongly nonlinear internal solitary waves...interaction of surface and internal gravity waves in the South China Sea. We will seek answers to the following questions: 1) How does the wind-wave
Hadjipapas, Avgis; Hillebrand, Arjan; Holliday, Ian E; Singh, Krish D; Barnes, Gareth R
2005-06-01
This study aimed to explore methods of assessing interactions between neuronal sources using MEG beamformers. However, beamformer methodology is based on the assumption of no linear long-term source interdependencies [VanVeen BD, vanDrongelen W, Yuchtman M, Suzuki A. Localization of brain electrical activity via linearly constrained minimum variance spatial filtering. IEEE Trans Biomed Eng 1997;44:867-80; Robinson SE, Vrba J. Functional neuroimaging by synthetic aperture magnetometry (SAM). In: Recent advances in Biomagnetism. Sendai: Tohoku University Press; 1999. p. 302-5]. Although such long-term correlations are not efficient and should not be anticipated in a healthy brain [Friston KJ. The labile brain. I. Neuronal transients and nonlinear coupling. Philos Trans R Soc Lond B Biol Sci 2000;355:215-36], transient correlations seem to underlie functional cortical coordination [Singer W. Neuronal synchrony: a versatile code for the definition of relations? Neuron 1999;49-65; Rodriguez E, George N, Lachaux J, Martinerie J, Renault B, Varela F. Perception's shadow: long-distance synchronization of human brain activity. Nature 1999;397:430-3; Bressler SL, Kelso J. Cortical coordination dynamics and cognition. Trends Cogn Sci 2001;5:26-36]. Two periodic sources were simulated and the effects of transient source correlation on the spatial and temporal performance of the MEG beamformer were examined. Subsequently, the interdependencies of the reconstructed sources were investigated using coherence and phase synchronization analysis based on Mutual Information. Finally, two interacting nonlinear systems served as neuronal sources and their phase interdependencies were studied under realistic measurement conditions. Both the spatial and the temporal beamformer source reconstructions were accurate as long as the transient source correlation did not exceed 30-40 percent of the duration of beamformer analysis. In addition, the interdependencies of periodic sources were
Directory of Open Access Journals (Sweden)
Matías A Goldin
Full Text Available The nature of telencephalic control over premotor and motor circuits is debated. Hypotheses range from complete usurping of downstream circuitry to highly interactive mechanisms of control. We show theoretically and experimentally, that telencephalic song motor control in canaries is consistent with a highly interactive strategy. As predicted from a theoretical model of respiratory control, mild cooling of a forebrain nucleus (HVC led to song stretching, but further cooling caused progressive restructuring of song, consistent with the hypothesis that respiratory gestures are subharmonic responses to a timescale present in the output of HVC. This interaction between a life-sustaining motor function (respiration and telencephalic song motor control suggests a more general mechanism of how nonlinear integration of evolutionarily new brain structures into existing circuitry gives rise to diverse, new behavior.
Otsuka, Hisanori; Hattori, Masahiro
When the structures, for example arch bridges are subjected bending moments and torsional moments, the strength and rigidity of the members decline compared to those of pure bending or torsion load condition. However, any analysis soft don't consider interrelation between bending and torsion ,and effects of torsional moments have not been considered severely in seismic design. In this study, the authors proposed analysis technique considering interaction between bending and torsion to estimate torsional moments severely, and formulized the analysis tools for this technique. These are interaction curve, skeleton for combined load, hysteresis for torsion. Moreover, the authors analyzed a RC arch bridge using this method, and inspected the validity of comparing the results obtained equivalent linear analysis about torsion and nonlinear torsional analysis not considering the interaction between bending and torsion.
International Nuclear Information System (INIS)
Itasse, Maxime; Brazier, Jean-Philippe; Léon, Olivier; Casalis, Grégoire
2015-01-01
Nonlinear evolution of disturbances in an axisymmetric, high subsonic, high Reynolds number hot jet with forced eigenmodes is studied using the Parabolized Stability Equations (PSE) approach to understand how modes interact with one another. Both frequency and azimuthal harmonic interactions are analyzed by setting up one or two modes at higher initial amplitudes and various phases. While single mode excitation leads to harmonic growth and jet noise amplification, controlling the evolution of a specific mode has been made possible by forcing two modes (m 1 , n 1 ), (m 2 , n 2 ), such that the difference in azimuth and in frequency matches the desired “target” mode (m 1 − m 2 , n 1 − n 2 ). A careful setup of the initial amplitudes and phases of the forced modes, defined as the “killer” modes, has allowed the minimizing of the initially dominant instability in the near pressure field, as well as its estimated radiated noise with a 15 dB loss. Although an increase of the overall sound pressure has been found in the range of azimuth and frequency analyzed, the present paper reveals the possibility to make the initially dominant instability ineffective acoustically using nonlinear interactions with forced eigenmodes
Energy Technology Data Exchange (ETDEWEB)
Itasse, Maxime, E-mail: Maxime.Itasse@onera.fr; Brazier, Jean-Philippe, E-mail: Jean-Philippe.Brazier@onera.fr; Léon, Olivier, E-mail: Olivier.Leon@onera.fr; Casalis, Grégoire, E-mail: Gregoire.Casalis@onera.fr [Onera - The French Aerospace Lab, F-31055 Toulouse (France)
2015-08-15
Nonlinear evolution of disturbances in an axisymmetric, high subsonic, high Reynolds number hot jet with forced eigenmodes is studied using the Parabolized Stability Equations (PSE) approach to understand how modes interact with one another. Both frequency and azimuthal harmonic interactions are analyzed by setting up one or two modes at higher initial amplitudes and various phases. While single mode excitation leads to harmonic growth and jet noise amplification, controlling the evolution of a specific mode has been made possible by forcing two modes (m{sub 1}, n{sub 1}), (m{sub 2}, n{sub 2}), such that the difference in azimuth and in frequency matches the desired “target” mode (m{sub 1} − m{sub 2}, n{sub 1} − n{sub 2}). A careful setup of the initial amplitudes and phases of the forced modes, defined as the “killer” modes, has allowed the minimizing of the initially dominant instability in the near pressure field, as well as its estimated radiated noise with a 15 dB loss. Although an increase of the overall sound pressure has been found in the range of azimuth and frequency analyzed, the present paper reveals the possibility to make the initially dominant instability ineffective acoustically using nonlinear interactions with forced eigenmodes.
Tang, H. T.; Hofmann, R.; Yee, G.; Vaughan, D. K.
1980-01-01
Transient, nonlinear soil-structure interaction simulations of an Electric Power Research Institute, SIMQUAKE experiment were performed using the large strain, time domain STEALTH 2D code and a cyclic, kinematically hardening cap soil model. Results from the STEALTH simulations were compared to identical simulations performed with the TRANAL code and indicate relatively good agreement between all the STEALTH and TRANAL calculations. The differences that are seen can probably be attributed to: (1) large (STEALTH) vs. small (TRANAL) strain formulation and/or (2) grid discretization differences.
International Nuclear Information System (INIS)
Poterasu, V.F.
1984-01-01
It is presented a method and the phase resonance for damping characteristic identification of non-linear soil-structural interaction. The algorithm can be applied in case of any, not necessarily, damping characteristic of the system examined. For the identification, the system is harmonically excited and are considered the super-harmonic amplitudes for odd and even powers of the x. The response of shear beam system for different levels of base excitation and for different locations of the load is considered. (Author) [pt
Nonlinear interaction of instability waves and vortex-pairing noise in axisymmetric subsonic jets
Yang, Hai-Hua; Zhou, Lin; Zhang, Xing-Chen; Wan, Zhen-Hua; Sun, De-Jun
2016-10-01
A direct simulation with selected inflow forcing is performed for an accurate description of the jet flow field and far-field noise. The effects of the Mach number and heating on the acoustic field are studied in detail. The beam patterns and acoustic intensities are both varied as the change of the Mach number and temperature. The decomposition of the source terms of the Lilley-Goldstein (L-G) equation shows that the momentum and thermodynamic components lead to distinctly different beam patterns. Significant cancellation is found between the momentum and thermodynamic components at low polar angles for the isothermal jet and large polar angles for the hot jet. The cancellation leads to the minimum values of the far-field sound. Based on linear parabolized stability equation solutions, the nonlinear interaction model for sound prediction is built in combination with the L-G equation. The dominant beam patterns and their original locations predicted by the nonlinear model are in good agreement with the direct simulation results, and the predictions of sound pressure level (SPL) by the nonlinear model are relatively reasonable.
Nonlinear gyrokinetic simulation of fast ion-driven modes including continuum interaction
Cole, M. D. J.; Borchardt, M.; Kleiber, R.; Könies, A.; Mishchenko, A.
2018-01-01
Energetic particle transport in toroidal magnetic confinement fusion devices can be enhanced by the particles' interaction with electromagnetic global modes. This process has been modelled numerically. The most extensive work has been with reduced models, which may use a simplified description of the bulk plasma, assuming a perturbative approximation for mode structure evolution, restrict simulation to the linear phase, or some combination. In this work, nonlinear non-perturbative simulations are performed using a fully gyrokinetic and reduced models of the bulk plasma. Previous linear investigation of a simple model tokamak case is extended to show that, at least under some conditions, dramatic qualitative differences in mode structure and saturated mode amplitude can exist due to non-perturbative response in the linear and nonlinear phases that depends upon the bulk plasma physics. This supports analytical work which has shown that the non-perturbative energetic particle response should depend upon the magnetic geometry and kinetic physics. It is also shown that energetic particle modes that dominate in the linear phase can be subdominant to a non-perturbative toroidal Alfvén eigenmode-based global structure in the nonlinear phase.
McKenzie, Ross Hugh
A brief overview of past experimental and theoretical investigations of the linear and nonlinear interaction of zero sound with the order parameter collective modes in superfluid ^3He-B is given before introducing the quasiclassical (QC) theory of superfluid ^3He. A new approach to calculating the linear and nonlinear response is presented. The QC propagator is calculated by expanding the low energy Dyson's equation in powers of the nonequilibrium self energy. The expression given for the expansion coefficients, involving products of pairs of equilibrium Green's functions, has a simple diagrammatic representation, and establishes a connection between the QC theory and other theoretical formalisms which have been used to investigate the collective modes. It is shown that the expansion coefficients satisfy Onsager-like relations and some identities required by gauge and galilean invariance. Consequently, this new approach to deriving dynamical equations for the collective modes is more efficient and transparent than solving the QC transport equations. This new approach is used to investigate the linear coupling of zero sound to the order parameter collective modes in weakly inhomogeneous superfluid ^3 He. It makes tractable the treatment of (nonlinear) parametric processes involving zero sound and the collective modes. It is shown that the approximate particle-hole symmetry of the ^3He Fermi liquid determines important selection rules for nonlinear acoustic processes, just as it is well known to do for linear processes. Analogues with nonlinear optics guide the derivation, solution and interpretation of the dynamical equations for a three-wave resonance between two zero sound waves and the J = 2 ^+ order parameter collective mode. It is shown that stimulated Raman scattering and two phonon absorption of zero sound by the J = 2^+ collective mode should be observable when the pump sound wave has energy density larger than about one percent of the superfluid
Lundh, O; Rechatin, C; Faure, J; Ben-Ismaïl, A; Lim, J; De Wagter, C; De Neve, W; Malka, V
2012-06-01
To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research. © 2012 American Association of Physicists in Medicine.
International Nuclear Information System (INIS)
Lundh, O.; Rechatin, C.; Faure, J.; Ben-Ismaïl, A.; Lim, J.; De Wagter, C.; De Neve, W.; Malka, V.
2012-01-01
Purpose: To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. Methods: In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. Results: It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. Conclusions: The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research.
Hoffman, F. M.; Randerson, J. T.; Moore, J. K.; Goulden, M.; Fu, W.; Koven, C.; Swann, A. L. S.; Mahowald, N. M.; Lindsay, K. T.; Munoz, E.
2017-12-01
Quantifying interactions between global biogeochemical cycles and the Earth system is important for predicting future atmospheric composition and informing energy policy. We applied a feedback analysis framework to three sets of Historical (1850-2005), Representative Concentration Pathway 8.5 (2006-2100), and its extension (2101-2300) simulations from the Community Earth System Model version 1.0 (CESM1(BGC)) to quantify drivers of terrestrial and ocean responses of carbon uptake. In the biogeochemically coupled simulation (BGC), the effects of CO2 fertilization and nitrogen deposition influenced marine and terrestrial carbon cycling. In the radiatively coupled simulation (RAD), the effects of rising temperature and circulation changes due to radiative forcing from CO2, other greenhouse gases, and aerosols were the sole drivers of carbon cycle changes. In the third, fully coupled simulation (FC), both the biogeochemical and radiative coupling effects acted simultaneously. We found that climate-carbon sensitivities derived from RAD simulations produced a net ocean carbon storage climate sensitivity that was weaker and a net land carbon storage climate sensitivity that was stronger than those diagnosed from the FC and BGC simulations. For the ocean, this nonlinearity was associated with warming-induced weakening of ocean circulation and mixing that limited exchange of dissolved inorganic carbon between surface and deeper water masses. For the land, this nonlinearity was associated with strong gains in gross primary production in the FC simulation, driven by enhancements in the hydrological cycle and increased nutrient availability. We developed and applied a nonlinearity metric to rank model responses and driver variables. The climate-carbon cycle feedback gain at 2300 was 42% higher when estimated from climate-carbon sensitivities derived from the difference between FC and BGC than when derived from RAD. We re-analyzed other CMIP5 model results to quantify the
Nonlinear Dynamics of Cantilever-Sample Interactions in Atomic Force Microscopy
Cantrell, John H.; Cantrell, Sean A.
2010-01-01
The interaction of the cantilever tip of an atomic force microscope (AFM) with the sample surface is obtained by treating the cantilever and sample as independent systems coupled by a nonlinear force acting between the cantilever tip and a volume element of the sample surface. The volume element is subjected to a restoring force from the remainder of the sample that provides dynamical equilibrium for the combined systems. The model accounts for the positions on the cantilever of the cantilever tip, laser probe, and excitation force (if any) via a basis set of set of orthogonal functions that may be generalized to account for arbitrary cantilever shapes. The basis set is extended to include nonlinear cantilever modes. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a matrix iteration procedure. The effects of oscillatory excitation forces applied either to the cantilever or to the sample surface (or to both) are obtained from the solution set and applied to the to the assessment of phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) modalities. The influence of bistable cantilever modes of on AFM signal generation is discussed. The effects on the cantilever-sample surface dynamics of subsurface features embedded in the sample that are perturbed by surface-generated oscillatory excitation forces and carried to the cantilever via wave propagation are accounted by the Bolef-Miller propagating wave model. Expressions pertaining to signal generation and image contrast in A-AFM are obtained and applied to amplitude modulation (intermittent contact) atomic force microscopy and resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM). The influence of phase accumulation in A-AFM on image contrast is discussed, as is the effect of hard contact and maximum nonlinearity regimes of A-AFM operation.
Beam-beam interaction and Pacman effects in the SSC with random nonlinear multipoles
International Nuclear Information System (INIS)
Goderre, G.P.; Ohnuma, S.
1988-01-01
In order to find the combined effects of beam-beam interaction (head-on and long-range) and random nonlinear multipoles in dipole magnets, transverse tunes and smears have been calculated as a function of oscillation amplitudes. Two types of particles, ''regular'' and ''Pacman,'' have been investigated using a modified version of tracking code TEAPOT. Regular particles experience beam-beam interactions in all four interaction regions (IR's), both head-on and long range, while pacman particles interact with bunches of the other beam in one medium-beta and one low-beta IR's only. The model for the beam-beam interaction is of weak-strong type and the strong beam is assumed to have a round Gaussian charge distribution. Furthermore, it is assumed that the vertical closed orbit deviation arising from the finite crossing angle of 70 μrad is perfectly compensated for regular particles. The same compensation applied to pacman particles creates a closed orbit distortion. Linear tunes are adjusted for regular particles to the design values but there are no nonlinear corrections except for chromaticity correcting sextupoles in two families. Results obtained in this study do not show any reduction of dynamic or linear aperture for pacman particles but some doubts exist regarding the validity of defining the linear aperture from the smear alone. Preliminary results are given for regular particles when (Δp/p) is modulated by the synchrotron oscillation. For these, fifty oscillations corresponding to 26,350 revolutions have been tracked. A very slow increase in the horizontal amplitude, /approximately/4 /times/ 10/sup /minus/4//oscillation (relative), is a possibility but this should be confirmed by trackings of larger number of revolutions. 11 refs., 18 figs., 2 tabs
Dangles, Olivier; Herrera, Mario; Mazoyer, Charlotte; Silvain, Jean-François
2013-04-01
Understanding how and to what extent the influence of temperature on physiological performance scales up to interspecific interactions and process rate patterns remains a major scientific challenge faced by ecologists. Here, we combined approaches developed by two conceptual frameworks in ecology, the stress-gradient hypothesis (SGH), and the biodiversity-ecosystem functioning relationship (B-EF), to test the hypothesis that interspecific difference in thermal performance modulates multiple species interactions along a thermal stress (SGH) and the subsequent richness effects on process rates (B-EF). We designed an experiment using three species of herbivorous agricultural pests with different thermal optima for which we determined how temperature influences the direction and the strength of interaction and subsequent richness effects on crop damage (7 species interaction treatments × 6 temperature treatments × 10 replicates). We showed that both biotic interactions and species richness effects drive variations in crop damages along a thermal stress gradient, and thus have the potential to drive agro-system responses to climate change. To help explain and generalize underlying mechanisms of richness effects on process rates, we further proposed a conceptual model that views interaction outcomes as shifting between positive and negative along a thermal stress depending on species thermal optima. Overall, our study demonstrates that nonlinear effects of temperature on process rates must be a major concern in terms of prediction and management of the consequences of global warming. © 2012 Blackwell Publishing Ltd.
Interaction trajectory of solitons in nonlinear media with an arbitrary degree of nonlocality
International Nuclear Information System (INIS)
Dai, Zhiping; Yang, Zhenjun; Ling, Xiaohui; Zhang, Shumin; Pang, Zhaoguang
2016-01-01
The interaction trajectory of solitons in nonlocal nonlinear media is investigated. A simple differential equation describing the interaction trajectories is derived based on the light ray equation. Numerical calculations are carried out to illustrate the interaction trajectories with different parameters. The results show that the degree of nonlocality greatly affects the interaction of solitons. For a strongly nonlocal case, the interaction trajectory can be described by a cosine function. Analytical expressions describing the trajectory and the oscillation period are obtained. For generally and weakly nonlocal cases, the interaction trajectories still oscillate periodically, however it is no longer sinusoidal and the oscillation period increases with the nonlocal degree decreasing. In addition, the trajectory of two solitons launched with a relative angle at the entrance plane is investigated. It is found that there exists a critical angle. When the initial relative angle is larger than the critical angle, the two solitons do not collide on propagation. The influence of the degree of nonlocality on the critical angle is also discussed.
Nonlinear cardio-respiratory interactions revealed by time-phase bispectral analysis
International Nuclear Information System (INIS)
Jamsek, Janez; Stefanovska, Aneta; McClintock, Peter V E
2004-01-01
Bispectral analysis based on high order statistics, introduced recently as a technique for revealing time-phase relationships among interacting noisy oscillators, has been used to study the nature of the coupling between cardiac and respiratory activity. Univariate blood flow signals recorded simultaneously by laser-Doppler flowmetry on both legs and arms were analysed. Coupling between cardiac and respiratory activity was also checked by use of bivariate data and computation of the cross-bispectrum between the ECG and respiratory signals. Measurements were made on six healthy males aged 25-27 years. Recordings were taken during spontaneous breathing (20 min), and during paced respiration at frequencies both lower and higher than that of spontaneous respiration (either two or three recordings with a constant frequency in the interval between 0.09 and 0.35 Hz). At each paced frequency recordings were taken for 12 min. It was confirmed that the dynamics of blood flow can usefully be considered in terms of coupled oscillators, and demonstrated that interactions between the cardiac and respiratory processes are weak and time-varying, and that they can be nonlinear. Nonlinear coupling was revealed to exist during both spontaneous and paced respiration. When present, it was detected in all four blood flow signals and in the cross-bispectrum between the ECG and respiratory signal. The episodes with nonlinear coupling were detected in 11 out of 22 recordings and lasted between 19 s in the case of high frequency (0.34 Hz) and 106 s in the case of low frequency paced respiration (0.11 Hz)
Ion response to relativistic electron bunches in the blowout regime of laser-plasma accelerators.
Popov, K I; Rozmus, W; Bychenkov, V Yu; Naseri, N; Capjack, C E; Brantov, A V
2010-11-05
The ion response to relativistic electron bunches in the so called bubble or blowout regime of a laser-plasma accelerator is discussed. In response to the strong fields of the accelerated electrons the ions form a central filament along the laser axis that can be compressed to densities 2 orders of magnitude higher than the initial particle density. A theory of the filament formation and a model of ion self-compression are proposed. It is also shown that in the case of a sharp rear plasma-vacuum interface the ions can be accelerated by a combination of three basic mechanisms. The long time ion evolution that results from the strong electrostatic fields of an electron bunch provides a unique diagnostic of laser-plasma accelerators.
Chimera regimes in a ring of oscillators with local nonlinear interaction
Shepelev, Igor A.; Zakharova, Anna; Vadivasova, Tatiana E.
2017-03-01
One of important problems concerning chimera states is the conditions of their existence and stability. Until now, it was assumed that chimeras could arise only in ensembles with nonlocal character of interactions. However, this assumption is not exactly right. In some special cases chimeras can be realized for local type of coupling [1-3]. We propose a simple model of ensemble with local coupling when chimeras are realized. This model is a ring of linear oscillators with the local nonlinear unidirectional interaction. Chimera structures in the ring are found using computer simulations for wide area of values of parameters. Diagram of the regimes on plane of control parameters is plotted and scenario of chimera destruction are studied when the parameters are changed.
Nonlinear mode interaction in equal-leg angle struts susceptible to cellular buckling.
Bai, L; Wang, F; Wadee, M A; Yang, J
2017-11-01
A variational model that describes the interactive buckling of a thin-walled equal-leg angle strut under pure axial compression is presented. A formulation combining the Rayleigh-Ritz method and continuous displacement functions is used to derive a system of differential and integral equilibrium equations for the structural component. Solving the equations using numerical continuation reveals progressive cellular buckling (or snaking) arising from the nonlinear interaction between the weak-axis flexural buckling mode and the strong-axis flexural-torsional buckling mode for the first time-the resulting behaviour being highly unstable. Physical experiments conducted on 10 cold-formed steel specimens are presented and the results show good agreement with the variational model.
Fuzzy adaptive interacting multiple model nonlinear filter for integrated navigation sensor fusion.
Tseng, Chien-Hao; Chang, Chih-Wen; Jwo, Dah-Jing
2011-01-01
In this paper, the application of the fuzzy interacting multiple model unscented Kalman filter (FUZZY-IMMUKF) approach to integrated navigation processing for the maneuvering vehicle is presented. The unscented Kalman filter (UKF) employs a set of sigma points through deterministic sampling, such that a linearization process is not necessary, and therefore the errors caused by linearization as in the traditional extended Kalman filter (EKF) can be avoided. The nonlinear filters naturally suffer, to some extent, the same problem as the EKF for which the uncertainty of the process noise and measurement noise will degrade the performance. As a structural adaptation (model switching) mechanism, the interacting multiple model (IMM), which describes a set of switching models, can be utilized for determining the adequate value of process noise covariance. The fuzzy logic adaptive system (FLAS) is employed to determine the lower and upper bounds of the system noise through the fuzzy inference system (FIS). The resulting sensor fusion strategy can efficiently deal with the nonlinear problem for the vehicle navigation. The proposed FUZZY-IMMUKF algorithm shows remarkable improvement in the navigation estimation accuracy as compared to the relatively conventional approaches such as the UKF and IMMUKF.
International Nuclear Information System (INIS)
Ishizawa, A.; Nakajima, N.
2007-01-01
Micro-turbulence and macro-magnetohydrodynamic (macro-MHD) instabilities can appear in plasma at the same time and interact with each other in a plasma confinement. The multi-scale-nonlinear interaction among micro-turbulence, double tearing instability and zonal flow is investigated by numerically solving a reduced set of two-fluid equations. It is found that the double tearing instability, which is a macro-MHD instability, appears in an equilibrium formed by a balance between micro-turbulence and zonal flow when the double tearing mode is unstable. The roles of the nonlinear and linear terms of the equations in driving the zonal flow and coherent convective cell flow of the double tearing mode are examined. The Reynolds stress drives zonal flow and coherent convective cell flow, while the ion diamagnetic term and Maxwell stress oppose the Reynolds stress drive. When the double tearing mode grows, linear terms in the equations are dominant and they effectively release the free energy of the equilibrium current gradient
Development of a gated optical multichannel analyser for laser-plasma spectroscopy
Corcoran, Richard
1990-01-01
An Optical Multichannel Analyser (OMA) has been developed for the detection of radiation from laser-produced plasmas (LPPs). The system is based on a gated image - intensified photodiode array (PDA) Software for the control of, and data acquisition from, the OMA system has been developed. A high resolution (10ns) delay generator was also designed and constructed to permit timeresolved. optical spectroscopy. The system has been tested and operated with a laser plasma source m...
Micro- and Nanoprocessing of Polymers Using a Laser Plasma Extreme Ultraviolet Source
International Nuclear Information System (INIS)
Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Rakowski, R.; Szczurek, A.; Szczurek, M.
2010-01-01
Laser plasma with temperature of the order of tens eV can be an efficient source of extreme ultraviolet (EUV). The radiation can be focused using different kind of optics, giving sufficient fluence for some applications. In this work we present results of investigations concerning applications of a laser plasma EUV source based on a double stream gas puff target. The source was equipped with two different grazing incidence collectors. One of them was a multifoil collector, the second one was an axisymmetrical ellipsoidal collector. The multifoil mirror was used mainly in experiments concerning micromachining of organic polymers by direct photo-etching. The experiments were performed for different polymers that were irradiated through a fine metal grid as a contact mask. The smallest element of a pattern structure obtained in this way was 5 μm, while the structure height was 50 μm giving an aspect ratio about 10. The laser-plasma EUV source equipped with the axisymmetrical ellipsoidal collector was used for surface modification of organic polymers and inorganic solids. The surface morphology after irradiation was investigated. Different forms of micro- and nanostructures were obtained depending on material and irradiation conditions. (author)
[Experimental investigation of laser plasma soft X-ray source with gas target].
Ni, Qi-liang; Gong, Yan; Lin, Jing-quan; Chen, Bo; Cao, Jian-lin
2003-02-01
This paper describes a debris-free laser plasma soft X-ray source with a gas target, which has high operating frequency and can produce strong soft X-ray radiation. The valve of this light source is drived by a piezoelectrical ceramic whose operating frequency is up to 400 Hz. In comparison with laser plasma soft X-ray sources using metal target, the light source is debris-free. And it has higher operating frequency than gas target soft X-ray sources whose nozzle is controlled by a solenoid valve. A channel electron multiplier (CEM) operating in analog mode is used to detect the soft X-ray generated by the laser plasma source, and the CEM's output is fed to to a charge-sensitive preamplifier for further amplification purpose. Output charges from the CEM are proportional to the amplitude of the preamplifier's output voltage. Spectra of CO2, Xe and Kr at 8-14 nm wavelength which can be used for soft X-ray projection lithography are measured. The spectrum for CO2 consists of separate spectral lines originate mainly from the transitions in Li-like and Be-like ions. The Xe spectrum originating mainly from 4d-5f, 4d-4f, 4d-6p and 4d-5p transitions in multiply charged xenon ions. The spectrum for Kr consists of separate spectral lines and continuous broad spectra originating mainly from the transitions in Cu-, Ni-, Co- and Fe-like ions.
Large-solid-angle illuminators for extreme ultraviolet lithography with laser plasmas
International Nuclear Information System (INIS)
Kubiak, G.D.; Tichenor, D.A.; Sweatt, W.C.; Chow, W.W.
1995-06-01
Laser Plasma Sources (LPSS) of extreme ultraviolet radiation are an attractive alternative to synchrotron radiation sources for extreme ultraviolet lithography (EUVL) due to their modularity, brightness, and modest size and cost. To fully exploit the extreme ultraviolet power emitted by such sources, it is necessary to capture the largest possible fraction of the source emission half-sphere while simultaneously optimizing the illumination stationarity and uniformity on the object mask. In this LDRD project, laser plasma source illumination systems for EUVL have been designed and then theoretically and experimentally characterized. Ellipsoidal condensers have been found to be simple yet extremely efficient condensers for small-field EUVL imaging systems. The effects of aberrations in such condensers on extreme ultraviolet (EUV) imaging have been studied with physical optics modeling. Lastly, the design of an efficient large-solid-angle condenser has been completed. It collects 50% of the available laser plasma source power at 14 nm and delivers it properly to the object mask in a wide-arc-field camera
The study on the non-linear soil structure interaction for nuclear power plants
International Nuclear Information System (INIS)
Tetsuya Hagiwara; Yoshio Kitada
2005-01-01
1. Introduction: JNES is planning a new project to study non-linear soil-structure interaction (SSI) effect under large earthquake ground motions equivalent to and/or over a design earthquake ground motion of S2(The extreme design earthquake). Concerning the SSI test, it is pointed out that handling of the scale effect of the specimen together with the surrounding soil on the earthquake response evaluation of the actual structure is essential issue for the scaled model test. Thus, for the test, the largest specimen possible and the biggest input motion possible are necessary. Taking into account the above issues, new test methodology, which utilizes artificial earthquake ground motion, is considered desirable if it can be performed at a realistic cost. Under this motivation, we have studied the test methodology which applying blasting power as for a big earthquake ground motion. The information from a coal mine company in the U.S.A. indicates that the works performed in the surface coal mine to blast a rock covering a coal layer generates a big artificial ground motion, which is similar to earthquake ground motion. Application of this artificial earthquake ground motion for the SSI test is considered very promising because the blasting work is carried out periodically for mining coal so that we can apply artificial motions generated by the work if we construct a building model at a closed point to the blasting work area. The major purposes of the test will be to understand (a) basic earthquake response characteristics of a Nuclear Power Plant (NPP) reactor building when a large earthquake strikes the NPP site and (b) nonlinear characteristics of SSI phenomenon during a big earthquake. In the paper, we introduce the test method and basic characteristics of measured artificial ground motions generated by the blasting works on an actual site. 2. Conclusion: It was confirmed that the artificial ground motions generated by blasting works have enough acceleration level
Stimulated Brillouin scattering in long-scale-length laser plasmas
International Nuclear Information System (INIS)
Chirokikh, A.; Seka, W.; Simon, A.; Craxton, R.S.; Tikhonchuk, V.T.
1998-01-01
Brillouin scattering from a preformed, inhomogeneous, expanding plasma has been investigated. Backscattered light near the incident laser wavelength (λ=1054 nm) from CH planar targets has been spectrally and temporally resolved. By varying the time delay of the interaction beam, the scattering was studied for different plasma conditions. The backscattered light is predominantly blue-shifted and appears before the peak of the laser pulse. The experimental time-integrated reflectivity of backscattered light is in the range of 1%endash 10% and decreases with the plasma density. The time-resolved spectra and total reflectivity were calculated using a theory of convective stimulated Brillouin scattering (SBS) in a flowing inhomogeneous plasma combined with a statistical hot spot model for the interaction beam. The plasma parameters for these calculations were provided by simulations using a two-dimensional hydrodynamic code. The calculated SBS spectra are similar to the experimental observations. The time-integrated reflectivities agree well with the experimental results for the higher peak density interactions, but are below the observations by orders of magnitude for the lowest peak density cases. copyright 1998 American Institute of Physics
Laser-plasmas in the relativistic-transparency regime: Science and applications
Cort Gautier, D.; Palaniyappan, Sasikumar; Albright, Brian J.; Favalli, Andrea; Hunter, James F.; Mendez, Jacob; Roth, Markus; Deppert, Oliver; Espy, Michelle; Guler, Nevzat; Hamilton, Christopher; Hegelich, Bjorn Manuel; Henzlova, Daniela; Ianakiev, Kiril D.; Iliev, Metodi; Johnson, Randall P.; Kleinschmidt, Annika; Losko, Adrian S.; McCary, Edward; Mocko, Michal; Nelson, Ronald O.; Roycroft, Rebecca; Schanz, Victor A.; Schaumann, Gabriel; Schmidt, Derek W.; Sefkow, Adam; Taddeucci, Terry N.; Yin, Lin
2017-01-01
Laser-plasma interactions in the novel regime of relativistically induced transparency (RIT) have been harnessed to generate intense ion beams efficiently with average energies exceeding 10 MeV/nucleon (>100 MeV for protons) at “table-top” scales in experiments at the LANL Trident Laser. By further optimization of the laser and target, the RIT regime has been extended into a self-organized plasma mode. This mode yields an ion beam with much narrower energy spread while maintaining high ion energy and conversion efficiency. This mode involves self-generation of persistent high magnetic fields (∼104 T, according to particle-in-cell simulations of the experiments) at the rear-side of the plasma. These magnetic fields trap the laser-heated multi-MeV electrons, which generate a high localized electrostatic field (∼0.1 T V/m). After the laser exits the plasma, this electric field acts on a highly structured ion-beam distribution in phase space to reduce the energy spread, thus separating acceleration and energy-spread reduction. Thus, ion beams with narrow energy peaks at up to 18 MeV/nucleon are generated reproducibly with high efficiency (≈5%). The experimental demonstration has been done with 0.12 PW, high-contrast, 0.6 ps Gaussian 1.053 μm laser pulses irradiating planar foils up to 250 nm thick at 2–8 × 1020 W/cm2. These ion beams with co-propagating electrons have been used on Trident for uniform volumetric isochoric heating to generate and study warm-dense matter at high densities. These beam plasmas have been directed also at a thick Ta disk to generate a directed, intense point-like Bremsstrahlung source of photons peaked at ∼2 MeV and used it for point projection radiography of thick high density objects. In addition, prior work on the intense neutron beam driven by an intense deuterium beam generated in the RIT regime has been extended. Neutron spectral control by means of a flexible converter-disk design has been
Czech Academy of Sciences Publication Activity Database
Znojil, Miloslav; Růžička, František; Zloshchastiev, K. G.
2017-01-01
Roč. 9, č. 8 (2017), č. článku 165. ISSN 2073-8994 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : PT symmetry * nonlinear Schrodinger equations * logarithmic nonlinearities Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 1.457, year: 2016
Directory of Open Access Journals (Sweden)
C. M. Huang
2006-12-01
Full Text Available To quantitatively study the effects of nonlinear interactions on tide structure, a nonlinear numerical tidal model is developed, and the reliability and convergence of the adopted algorithm and coding are checked by numerical experiments. Under the same conditions as those employed by the GSWM-00 (Global Scale Wave Model 2000, our model provides the nonlinear quasi-steady solution of the migrating semidiurnal tide, which differs from the GSWM-00 result (the linear steady solution in the MLT region, especially above 100 km. Additionally, their amplitude difference displays a remarkable month-to-month variation, and its significant magnitudes occur during the month with strong semidiurnal tide. A quantitative analysis suggests that the main cause for the amplitude difference is that the initial migrating 12-h tide will interact with the mean flow as well as the nonlinearity-excited 6-h tide, and subsequently yield a new 12-h tidal part. Furthermore, our simulations also show that the mean flow/tidal interaction will significantly alter the background wind and temperature fields. The large magnitudes of the tidal amplitude difference and the background alteration indicate that the nonlinear processes involved in tidal propagations should be comprehensively considered in the description of global atmospheric dynamics in the MLT region. The comparisons among our simulations, the GSWMs and some observations of tides suggest that the nonlinearity-induced tidal structure variation could be a possible mechanism to account for some discrepancies between the GSWMs and the observations.
Bhardwaj, Divyanshu; Guha, Anirban
2018-01-01
Theoretical studies on linear shear instabilities often use simple velocity and density profiles (e.g., constant, piecewise) for obtaining good qualitative and quantitative predictions of the initial disturbances. Furthermore, such simple profiles provide a minimal model for obtaining a mechanistic understanding of otherwise elusive shear instabilities. However, except a few specific cases, the efficacy of simple profiles has remained limited to the linear stability paradigm. In this work, we have proposed a general framework that can simulate the fully nonlinear evolution of a variety of stratified shear instabilities as well as wave-wave and wave-topography interaction problems having simple piecewise constant and/or linear profiles. To this effect, we have modified the classical vortex method by extending the Birkhoff-Rott equation to multiple interfaces and, furthermore, have incorporated background shear across a density interface. The latter is more subtle and originates from the understanding that Bernoulli's equation is not just limited to irrotational flows but can be modified to make it applicable for piecewise linear velocity profiles. We have solved diverse problems that can be essentially reduced to the multiple interacting interfaces paradigm, e.g., spilling and plunging breakers, stratified shear instabilities like Holmboe and Taylor-Caulfield, jet flows, and even wave-topography interaction problems like Bragg resonance. Free-slip boundary being a vortex sheet, its effect can also be effectively captured using vortex method. We found that the minimal models capture key nonlinear features, e.g., wave breaking features like cusp formation and roll-ups, which are observed in experiments and/or extensive simulations with smooth, realistic profiles.
Rate of non-linearity in DMS aerosol-cloud-climate interactions
Directory of Open Access Journals (Sweden)
M. A. Thomas
2011-11-01
Full Text Available The degree of non-linearity in DMS-cloud-climate interactions is assessed using the ECHAM5-HAMMOZ model by taking into account end-to-end aerosol chemistry-cloud microphysics link. The evaluation is made over the Southern oceans in austral summer, a region of minimal anthropogenic influence. In this study, we compare the DMS-derived changes in the aerosol and cloud microphysical properties between a baseline simulation with the ocean DMS emissions from a prescribed climatology, and a scenario where the DMS emissions are doubled. Our results show that doubling the DMS emissions in the current climate results in a non-linear response in atmospheric DMS burden and subsequently, in SO_{2} and H_{2}SO_{4} burdens due to inadequate OH oxidation. The aerosol optical depth increases by only ~20 % in the 30° S–75° S belt in the SH summer months. This increases the vertically integrated cloud droplet number concentrations (CDNC by 25 %. Since the vertically integrated liquid water vapor is constant in our model simulations, an increase in CDNC leads to a reduction in cloud droplet radius of 3.4 % over the Southern oceans in summer. The equivalent increase in cloud liquid water path is 10.7 %. The above changes in cloud microphysical properties result in a change in global annual mean radiative forcing at the TOA of −1.4 W m^{−2}. The results suggest that the DMS-cloud microphysics link is highly non-linear. This has implications for future studies investigating the DMS-cloud climate feedbacks in a warming world and for studies evaluating geoengineering options to counteract warming by modulating low level marine clouds.
Quantitative Assessment of MeV Electron Acceleration in Non-Linear Interactions with VLF Chorus
Foster, J. C.; Erickson, P. J.; Omura, Y.; Baker, D. N.
2016-12-01
For occurrences of apparent rapid acceleration of radiation belt electrons to MeV energies at L 4, we examine the energy gained by seed electrons in non-linear (NL) interactions with VLF chorus rising tones. For the 17-18 March 2013 storm, observations of outer zone radiation belt electron populations were made with the magEIS and REPT instruments on Van Allen Probes A & B. These reveal that MeV electron fluxes at L=4.2 increased 10-fold in 30 min at the times of 30 - 100 keV electron injections during "substorm" dipolarizations. Simultaneous enhancements of VLF chorus were observed with the EMFISIS wave instruments. Three-axis burst mode observations of wave electric and magnetic fields have been used to investigate electron interactions with individual chorus rising tones on a sub millisecond time scale. Wave amplitudes at 2500 Hz were 1 nT (|B|) and 30 mV/m (|E|). Frequency - time characteristics of the observed chorus elements closely match those predicted by NL electron-chorus interaction modeling [Omura et al., 2015, J. Geophys. Res. Space Phys., 120, doi:10.1002/2015JA021563]. For seed electrons with initial energies 50 keV to 8 MeV, subpacket wave analysis was used to quantify resonant electron energy gain both by relativistic turning acceleration and by ultrarelativistic acceleration through nonlinear trapping by the chorus waves. Electrons with 1-2 MeV initial energy can experience a 300 keV total energy gain in NL interactions with a single 200 msec rising tone. Maximum energy gain from interaction with a single 10 msec subpacket was 100 keV for a 2 MeV seed electron. Examining a number of chorus elements at different locations during the rapid local acceleration of the radiation belt during this event, we conclude that seed electrons (100s keV - 5 MeV) can be accelerated by 50 keV - 500 keV in resonant NL interactions with a single VLF rising tone on a time scale of 10-100 msec.
Zakharov, Yu P.; Ponomarenko, A. G.; Tishchenko, V. N.; Antonov, V. M.; Melekhov, A. V.; Posukh, V. G.; Prokopov, P. A.; Terekhin, V. A.
2016-05-01
We present the results of first experiments on the formation of collisionless shock waves (CSWs) in background plasma by injecting laser plasma bunches transverse to the magnetic field (as a piston) with a maximum energy up to 100 J per unit of solid angle and with a high enough degree of ion magnetisation. With this aim in view, on a unique KI-1 facility at the Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences (ILP), a plastic (polyethylene) target irradiated by a CO2 laser in the most energy-efficient regime (near the plasma formation threshold) and a highly ionised hydrogen plasma with a high concentration in a large volume (not less than 1 m3) have been employed. As a result of model experiments performed on the basis of a model of collisionless interaction of plasma flows, developed at the VNIIEF and being adequate to the problem under consideration, not only an intensive, background-induced, deceleration of a super-Alfven laser plasma flow, but also the formation in that flow of a strong perturbation having the properties of a subcritical CSW and propagating transverse to the magnetic field, have been first registered in the laboratory conditions.
Near-field soil-structure interaction analysis using nonlinear hybrid modeling
International Nuclear Information System (INIS)
Katayama, I.; Chen, C.; Lee, Y.J.; Jean, W.Y.; Penzien, J.
1989-01-01
The hybrid modeling method (Gupta and Penzien 1980) and associated analysis procedure for solving a three-dimensional soil-structure interaction problem was developed by Gupta and Penzien (1981) and Gupta et al.(1982). Subsequently, successive modifications have been made to the original modeling method and analysis procedure allowing more general treatment of the SSI problem (Penzien, 1988). Through many correlation studies of field test data obtained under forced-vibration and earthquake-excitation conditions, it has been shown that the HASSI programs can effectively predict the dynamic response of a soil-structure system, if realistic soil parameters are adopted. In the above, the entire structure-foundation system is considered to respond in a linear fashion. Since the reflected three-dimensional waves at the soil-structure interface decays very rapidly with distance away from the structure (Katayama, 1987 (a)), the response of the soil close to the base of the structure may greatly affect its response; therefore, proper modeling of the non-linear soil behavior characteristic is essential. The nonlinear behavior of near-field soil has been taken into consideration in HASSI-7 by the standard equivalent linearization procedures used in programs SHAKE and FLUSH
Nonlinear effects of a beam interacting with a single damped wave
International Nuclear Information System (INIS)
Stoltz, Peter H.; Cary, John R.
2000-01-01
A self-consistent nonlinear theory of the longitudinal dynamics of a low density beam interacting with a single damped wave is developed. In this paper, the model is applied to the coasting beam-cavity system of accelerator physics, but it also applies to beam-plasma systems and traveling wave tubes. Motivating the theory are numerical simulations showing different beam behaviors in the nonlinear regime depending on the amount of wave damping. For highly damped systems, breakoff and energy loss of a self-formed bunch from the beam is observed. This bunch breakoff and energy loss is the cause of the overshoot phenomenon of accelerator physics; furthermore this overshoot does not contradict the Keil-Schnell criterion, as the beam is far from a Gaussian distribution. An expression for the amount of cavity damping necessary for bunch breakoff is derived. Finally, using a single-particle model, an expression for the rate of energy loss of the bunch in terms of the cavity damping is derived. (c) 2000 American Institute of Physics
Electron-phonon interaction and nonlinear transport phenomena in solid Hg point-contacts
Energy Technology Data Exchange (ETDEWEB)
Khotkevych, V V [Department of Physics, University of Bath, Claverton Down, BA2 7AY Bath (United Kingdom); Khotkevych, N V [Department of Physics, Karazin National University, 61077 Kharkiv (Ukraine); Morlok, S V [National Technical University, 61002, Kharkiv (Ukraine); Konopatskyi, B L; Khotkevych, A V [B.Verkin Institute for Low Temperature Physics and Engineering, 61103 Kharkiv (Ukraine)], E-mail: V.Khotkevych@bath.ac.uk
2009-02-01
At cryogenic temperatures the conductivity of Hg point-contacts was studied in both the superconducting and normal state. An original method of fabricating the Hg-based point-contacts directly in liquid {sup 4}He was proposed, which guaranteed creation of small-size high-purity ballistic contacts. The resistance of the contacts as well as the current-voltage characteristics along with the voltage dependence of their first and second derivatives were experimentally investigated at 1.5 K. We analyze such characteristics of the contacts as Josephson critical current, excess current, energy gap and the nonlinear part of conductivity caused by electron-phonon interaction (EPI). The point-contact EPI function g{sub pc}({omega}) for Hg was reconstructed and integral parameters of EPI were calculated. The g{sub pc}({omega}) was then used as an approximation to the phonon density of states for estimations of the thermodynamic characteristics in Hg. Finally we discuss the results of our calculations of non-linear conductivity caused by manifestation of the frequency dependence of the energy gap function in the elastic current component through the contact.
A Nonlinear Model for Gene-Based Gene-Environment Interaction
Directory of Open Access Journals (Sweden)
Jian Sa
2016-06-01
Full Text Available A vast amount of literature has confirmed the role of gene-environment (G×E interaction in the etiology of complex human diseases. Traditional methods are predominantly focused on the analysis of interaction between a single nucleotide polymorphism (SNP and an environmental variable. Given that genes are the functional units, it is crucial to understand how gene effects (rather than single SNP effects are influenced by an environmental variable to affect disease risk. Motivated by the increasing awareness of the power of gene-based association analysis over single variant based approach, in this work, we proposed a sparse principle component regression (sPCR model to understand the gene-based G×E interaction effect on complex disease. We first extracted the sparse principal components for SNPs in a gene, then the effect of each principal component was modeled by a varying-coefficient (VC model. The model can jointly model variants in a gene in which their effects are nonlinearly influenced by an environmental variable. In addition, the varying-coefficient sPCR (VC-sPCR model has nice interpretation property since the sparsity on the principal component loadings can tell the relative importance of the corresponding SNPs in each component. We applied our method to a human birth weight dataset in Thai population. We analyzed 12,005 genes across 22 chromosomes and found one significant interaction effect using the Bonferroni correction method and one suggestive interaction. The model performance was further evaluated through simulation studies. Our model provides a system approach to evaluate gene-based G×E interaction.
On the solution of the equations for nonlinear interaction of three damped waves
International Nuclear Information System (INIS)
1976-01-01
Three-wave interactions are analyzed in a coherent wave description assuming different linear damping (or growth) of the individual waves. It is demonstrated that when two of the coefficients of dissipation are equal, the set of equations can be reduced to a single equivalent equation, which in the nonlinearly unstable case, where one wave is undamped, asymptotically takes the form of an equation defining the third Painleve transcendent. It is then possible to find an asymptotic expansion near the time of explosion. This solution is of principal interest since it indicates that the solution of the general three-wave system, where the waves undergo different individual dissipations, belongs to a higher class of functions, which reduces to Jacobian elliptic functions only in the case where all waves suffer the same damping [fr
Laser cutting of ultra-thin glasses based on a nonlinear laser interaction effect
Chen, Jian; Wu, Zhouling
2013-07-01
Glass panel substrates have been widely used in consumer electronics such as in flat panel TVs, laptops, and cell phones. With the advancement in the industry, the glass substrates are becoming thinner and stronger for reduced weight and volume, which brings great challenges for traditional mechanical processes in terms of cut quality, yield, and throughput. Laser glass cutting provides a non-contact process with minimum impact and superior quality compared to the mechanical counterparts. In this paper, we presented recent progresses in advanced laser processing of ultra-thin glass substrates, especially laser-cutting of ultra-thin glasses by a high power laser through a nonlinear interaction effect. Our results indicate that this technique has great potential of application for mass production of ultra-thin glass substrates.
Directory of Open Access Journals (Sweden)
Etienne Thoret
2016-06-01
Full Text Available In this paper, a flexible control strategy for a synthesis model dedicated to nonlinear friction phenomena is proposed. This model enables to synthesize different types of sound sources, such as creaky doors, singing glasses, squeaking wet plates or bowed strings. Based on the perceptual stance that a sound is perceived as the result of an action on an object we propose a genuine source/filter synthesis approach that enables to elude physical constraints induced by the coupling between the interacting objects. This approach makes it possible to independently control and freely combine the action and the object. Different implementations and applications related to computer animation, gesture learning for rehabilitation and expert gestures are presented at the end of this paper.
Nonlinear evolution dynamics of holographic superconductor model with scalar self-interaction
Li, Ran; Zi, Tieguang; Zhang, Hongbao
2018-04-01
We investigate the holographic superconductor model that is described by the Einstein-Maxwell theory with the self-interaction term λ |Ψ |4 of complex scalar field in asymptotic anti-de Sitter (AdS) spacetime. Below critical temperature Tc, the planar Reissner-Nordström-AdS black hole is unstable due to the near-horizon scalar condensation instability. We study the full nonlinear development of this instability by numerically solving the gravitational dynamics in the asymptotic AdS spacetime, and observe a dynamical process from the perturbed Reissner-Nordström-AdS black hole to a hairy black hole when the initial black hole temperature T evolution of superconducting condensate operator, event and apparent horizon areas of the final hairy black hole.
A Boussinesq-type method for fully nonlinear waves interacting with a rapidly varying bathymetry
DEFF Research Database (Denmark)
Madsen, Per A.; Fuhrman, David R.; Wang, Benlong
2006-01-01
New equations are derived for fully nonlinear and highly dispersive water waves interacting with a rapidly varying bathymetry. The derivation is an extension of a recent high order Boussinesq type formulation valid on a mildly sloping bottom. It is based on a series expansion from a rapidly...... spatially varying expansion level and the resulting general velocity formulation is given as a triple-summation of terms involving high derivatives of this expansion level. For practical implementation, it is necessary to simplify and truncate this general formulation and we do this by assuming...... that the expansion level (but not the bathymetry) is slowly varying in space. On this basis, the general expressions are simplified to include first and second derivatives of the expansion level and up to fifth-derivatives of the velocity variables. With this new approach, the accuracy of the dispersion relation can...
Romanelli, N.; Mazelle, C.; Meziane, K.
2018-02-01
Seen from the solar wind (SW) reference frame, the presence of newborn planetary protons upstream from the Martian and Venusian bow shocks and SW protons reflected from each of them constitutes two sources of nonthermal proton populations. In both cases, the resulting proton velocity distribution function is highly unstable and capable of giving rise to ultralow frequency quasi-monochromatic electromagnetic plasma waves. When these instabilities take place, the resulting nonlinear waves are convected by the SW and interact with nonthermal protons located downstream from the wave generation region (upstream from the bow shock), playing a predominant role in their dynamics. To improve our understanding of these phenomena, we study the interaction between a charged particle and a large-amplitude monochromatic circularly polarized electromagnetic wave propagating parallel to a background magnetic field, from first principles. We determine the number of fix points in velocity space, their stability, and their dependence on different wave-particle parameters. Particularly, we determine the temporal evolution of a charged particle in the pitch angle-gyrophase velocity plane under nominal conditions expected for backstreaming protons in planetary foreshocks and for newborn planetary protons in the upstream regions of Venus and Mars. In addition, the inclusion of wave ellipticity effects provides an explanation for pitch angle distributions of suprathermal protons observed at the Earth's foreshock, reported in previous studies. These analyses constitute a mean to evaluate if nonthermal proton velocity distribution functions observed at these plasma environments present signatures that can be understood in terms of nonlinear wave-particle processes.
Adaptive nonlinear polynomial neural networks for control of boundary layer/structural interaction
Parker, B. Eugene, Jr.; Cellucci, Richard L.; Abbott, Dean W.; Barron, Roger L.; Jordan, Paul R., III; Poor, H. Vincent
1993-01-01
The acoustic pressures developed in a boundary layer can interact with an aircraft panel to induce significant vibration in the panel. Such vibration is undesirable due to the aerodynamic drag and structure-borne cabin noises that result. The overall objective of this work is to develop effective and practical feedback control strategies for actively reducing this flow-induced structural vibration. This report describes the results of initial evaluations using polynomial, neural network-based, feedback control to reduce flow induced vibration in aircraft panels due to turbulent boundary layer/structural interaction. Computer simulations are used to develop and analyze feedback control strategies to reduce vibration in a beam as a first step. The key differences between this work and that going on elsewhere are as follows: that turbulent and transitional boundary layers represent broadband excitation and thus present a more complex stochastic control scenario than that of narrow band (e.g., laminar boundary layer) excitation; and secondly, that the proposed controller structures are adaptive nonlinear infinite impulse response (IIR) polynomial neural network, as opposed to the traditional adaptive linear finite impulse response (FIR) filters used in most studies to date. The controllers implemented in this study achieved vibration attenuation of 27 to 60 dB depending on the type of boundary layer established by laminar, turbulent, and intermittent laminar-to-turbulent transitional flows. Application of multi-input, multi-output, adaptive, nonlinear feedback control of vibration in aircraft panels based on polynomial neural networks appears to be feasible today. Plans are outlined for Phase 2 of this study, which will include extending the theoretical investigation conducted in Phase 2 and verifying the results in a series of laboratory experiments involving both bum and plate models.
Holographic Imaging of Evolving Laser-Plasma Structures
Energy Technology Data Exchange (ETDEWEB)
Downer, Michael [Univ. of Texas, Austin, TX (United States); Shvets, G. [Univ. of Texas, Austin, TX (United States)
2014-07-31
In the 1870s, English photographer Eadweard Muybridge captured motion pictures within one cycle of a horse’s gallop, which settled a hotly debated question of his time by showing that the horse became temporarily airborne. In the 1940s, Manhattan project photographer Berlin Brixner captured a nuclear blast at a million frames per second, and resolved a dispute about the explosion’s shape and speed. In this project, we developed methods to capture detailed motion pictures of evolving, light-velocity objects created by a laser pulse propagating through matter. These objects include electron density waves used to accelerate charged particles, laser-induced refractive index changes used for micromachining, and ionization tracks used for atmospheric chemical analysis, guide star creation and ranging. Our “movies”, like Muybridge’s and Brixner’s, are obtained in one shot, since the laser-created objects of interest are insufficiently repeatable for accurate stroboscopic imaging. Our high-speed photographs have begun to resolve controversies about how laser-created objects form and evolve, questions that previously could be addressed only by intensive computer simulations based on estimated initial conditions. Resolving such questions helps develop better tabletop particle accelerators, atmospheric ranging devices and many other applications of laser-matter interactions. Our photographic methods all begin by splitting one or more “probe” pulses from the laser pulse that creates the light-speed object. A probe illuminates the object and obtains information about its structure without altering it. We developed three single-shot visualization methods that differ in how the probes interact with the object of interest or are recorded. (1) Frequency-Domain Holography (FDH). In FDH, there are 2 probes, like “object” and “reference” beams in conventional holography. Our “object” probe surrounds the light-speed object, like a fleas swarming around a
Wang, X. L.; Xu, Z. Y.; Luo, W.; Lu, H. Y.; Zhu, Z. C.; Yan, X. Q.
2017-09-01
Photo-transmutation of long-lived nuclear waste induced by a high-charge relativistic electron beam (e-beam) from a laser plasma accelerator is demonstrated. A collimated relativistic e-beam with a high charge of approximately 100 nC is produced from high-intensity laser interaction with near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor and then radiates energetic bremsstrahlung photons with flux approaching 1011 per laser shot. Taking a long-lived radionuclide 126Sn as an example, the resulting transmutation reaction yield is the order of 109 per laser shot, which is two orders of magnitude higher than obtained from previous studies. It is found that at lower densities, a tightly focused laser irradiating relatively longer NCD plasmas can effectively enhance the transmutation efficiency. Furthermore, the photo-transmutation is generalized by considering mixed-nuclide waste samples, which suggests that the laser-accelerated high-charge e-beam could be an efficient tool to transmute long-lived nuclear waste.
International Nuclear Information System (INIS)
Gasilov, S. V.; Faenov, A. Ya.; Pikuz, T. A.; Villoresi, P.; Poletto, L.; Stagira, S.; Calegari, F.; Vozzi, C.; Nisoli, M.
2007-01-01
Nowadays charged-coupled device (CCD) detectors are widely used for the registration of multicharged ions x-ray spectra. These spectra are generated in a plasma during interaction of ultrashort, ultraintense laser pulses with solid targets. Strong parasitic radiation from the plasma affects CCD detectors and contaminates resulting spectra, so that spectral features can be completely covered by noise even during measurements with a very short accumulation time. In this work we propose a ''mean to median'' (M2M) algorithm for noise suppression in femtosecond laser plasma x-ray spectra. Series of spectra is necessary for the identification of corrupted data points by the developed method. The algorithm was tested with model spectra which reflect main features of experimental data. In practice we used it for extracting information about spectral lines of Ne-like Fe ions and He-like Al ions which allowed us to calculate plasma parameters. It is demonstrated that M2M method is able to clean spectra with more than 10% of corrupted pixels. Fluctuations in intensity of spectral lines induced by laser instability do not affect validity of the proposed method
Seryi, Andrei; Lesz, Zsolt; Andreev, Alexander; Konoplev, Ivan
2017-03-01
A novel method for generating GigaGauss solenoidal fields in a laser-plasma bubble, using screw-shaped laser pulses, has been recently presented. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper, we present an outline of what a staged plasma-acceleration FEL could look like, and discuss further studies needed to investigate the feasibility of the concept in detail.
Stability, diffusion and interactions of nonlinear excitations in a many body system
Coste, Christophe; Jean, Michel Saint; Dessup, Tommy
2017-04-01
When repelling particles are confined in a quasi-one-dimensional trap by a transverse potential, a configurational phase transition happens. All particles are aligned along the trap axis at large confinement, but below a critical transverse confinement they adopt a staggered row configuration (zigzag phase). This zigzag transition is a subcritical pitchfork bifurcation in extended systems and in systems with cyclic boundary conditions in the longitudinal direction. Among many evidences, phase coexistence is exhibited by localized nonlinear patterns made of a zigzag phase embedded in otherwise aligned particles. We give the normal form at the bifurcation and we show that these patterns can be described as solitary wave envelopes that we call bubbles. They are stable in a large temperature range and can diffuse as quasi-particles, with a diffusion coefficient that may be deduced from the normal form. The potential energy of a bubble is found to be lower than that of the homogeneous bifurcated phase, which explains their stability. We observe also metastable states, that are pairs of solitary wave envelopes which spontaneously evolve toward a stable single bubble. We evidence a strong effect of the discreteness of the underlying particles system and introduce the concept of topological frustration of a bubble pair. A configuration is frustrated when the particles between the two bubbles are not organized in a modulated staggered row. For a nonfrustrated (NF) bubble pair configuration, the bubbles interaction is attractive so that the bubbles come closer and eventually merge as a single bubble. In contrast, the bubbles interaction is found to be repulsive for a frustrated (F) configuration. We describe a model of interacting solitary wave that provides all qualitative characteristics of the interaction force: it is attractive for NF-systems, repulsive for F-systems, and decreases exponentially with the bubbles distance.
Plastino, A. R.; Curado, E. M. F.; Nobre, F. D.; Tsallis, C.
2018-02-01
Nonlinear Fokker-Planck equations endowed with power-law diffusion terms have proven to be valuable tools for the study of diverse complex systems in physics, biology, and other fields. The nonlinearity appearing in these evolution equations can be interpreted as providing an effective description of a system of particles interacting via short-range forces while performing overdamped motion under the effect of an external confining potential. This point of view has been recently applied to the study of thermodynamical features of interacting vortices in type II superconductors. In the present work we explore an embedding of the nonlinear Fokker-Planck equation within a Vlasov equation, thus incorporating inertial effects to the concomitant particle dynamics. Exact time-dependent solutions of the q -Gaussian form (with compact support) are obtained for the Vlasov equation in the case of quadratic confining potentials.
DEFF Research Database (Denmark)
Castaldi, P J; Demeo, D L; Hersh, C P
2010-01-01
with COPD. Using data from the Alpha-1 Antitrypsin Genetic Modifiers Study, the accuracy and power of two different approaches to model smoking were compared by performing a simulation study of a genetic variant with a range of gene-by-smoking interaction effects. Results Non-linear relationships between...... range of COPD severity, a non-linear relationship between pack-years of smoking and FEV(1) is likely. In this setting, approaches that account for this non-linearity can be more powerful and less biased than the more common approach of using total pack-years to model the smoking effect.......Background The identification of gene-by-environment interactions is important for understanding the genetic basis of chronic obstructive pulmonary disease (COPD). Many COPD genetic association analyses assume a linear relationship between pack-years of smoking exposure and forced expiratory volume...
Nonlinear seismic soil-structure interaction analysis of nuclear power plant structures
International Nuclear Information System (INIS)
Khanna, J.K.; Setlur, A.V.; Pathak, D.V.
1977-01-01
The heterogeneous and nonlinear soil medium and the detailed three-dimensional structure are synthesized to determine the seismic response to soil-structure systems. The approach is particularly attractive in a design office environment since it: a) leads to interactive motion at the soil-structure interface; b) uses existing public domain programs such as SAPIV, LUSH and FLUSH with marginal modifications; and c) meets current regulatory requirements for soil-structure interaction analysis. Past methods differ from each other depending on the approach adopted for soil and structure representations and procedures for solving the governing differential equations. Advantages and limitations of these methods are reviewed. In the current approach, the three-dimensional structure is represented by the dynamic characteristics of its fixed base condition. This representation is ideal when structures are designed to be within elastic range. An important criterion is the design of the nuclear power plant structures. Model damping coefficients are varied to reflect the damping properties of different structural component materials. The detailed structural model is systematically reduced to reflect important dynamic behavior with simultaneous storing of intermediate information for retrieval of detailed structural response. Validity of the approach has been established with simple numerical experiments. (Auth.)
Nonlinear response surface in the study of interaction analysis of three combination drugs.
Wan, Wen; Pei, Xin-Yan; Grant, Steven; Birch, Jeffrey B; Felthousen, Jessica; Dai, Yun; Fang, Hong-Bin; Tan, Ming; Sun, Shumei
2017-01-01
Few articles have been written on analyzing three-way interactions between drugs. It may seem to be quite straightforward to extend a statistical method from two-drugs to three-drugs. However, there may exist more complex nonlinear response surface of the interaction index (II) with more complex local synergy and/or local antagonism interspersed in different regions of drug combinations in a three-drug study, compared in a two-drug study. In addition, it is not possible to obtain a four-dimensional (4D) response surface plot for a three-drug study. We propose an analysis procedure to construct the dose combination regions of interest (say, the synergistic areas with II≤0.9). First, use the model robust regression method (MRR), a semiparametric method, to fit the entire response surface of the II, which allows to fit a complex response surface with local synergy/antagonism. Second, we run a modified genetic algorithm (MGA), a stochastic optimization method, many times with different random seeds, to allow to collect as many feasible points as possible that satisfy the estimated values of II≤0.9. Last, all these feasible points are used to construct the approximate dose regions of interest in a 3D. A case study with three anti-cancer drugs in an in vitro experiment is employed to illustrate how to find the dose regions of interest. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Moore, Jason H
2010-01-01
Human health is a complex process that is dependent on many genes, many environmental factors and chance events that are perhaps not measurable with current technology or are simply unknowable. Success in the design and execution of population-based association studies to identify those genetic and environmental factors that play an important role in human disease will depend on our ability to embrace, rather that ignore, complexity in the genotype to phenotype mapping relationship for any given human ecology. We review here three general computational challenges that must be addressed. First, data mining and machine learning methods are needed to model nonlinear interactions between multiple genetic and environmental factors. Second, filter and wrapper methods are needed to identify attribute interactions in large and complex solution landscapes. Third, visualization methods are needed to help interpret computational models and results. We provide here an overview of the multifactor dimensionality reduction (MDR) method that was developed for addressing each of these challenges. Copyright © 2010 Elsevier Inc. All rights reserved.
Neurosurgery simulation using non-linear finite element modeling and haptic interaction
Lee, Huai-Ping; Audette, Michel; Joldes, Grand R.; Enquobahrie, Andinet
2012-02-01
Real-time surgical simulation is becoming an important component of surgical training. To meet the realtime requirement, however, the accuracy of the biomechancial modeling of soft tissue is often compromised due to computing resource constraints. Furthermore, haptic integration presents an additional challenge with its requirement for a high update rate. As a result, most real-time surgical simulation systems employ a linear elasticity model, simplified numerical methods such as the boundary element method or spring-particle systems, and coarse volumetric meshes. However, these systems are not clinically realistic. We present here an ongoing work aimed at developing an efficient and physically realistic neurosurgery simulator using a non-linear finite element method (FEM) with haptic interaction. Real-time finite element analysis is achieved by utilizing the total Lagrangian explicit dynamic (TLED) formulation and GPU acceleration of per-node and per-element operations. We employ a virtual coupling method for separating deformable body simulation and collision detection from haptic rendering, which needs to be updated at a much higher rate than the visual simulation. The system provides accurate biomechancial modeling of soft tissue while retaining a real-time performance with haptic interaction. However, our experiments showed that the stability of the simulator depends heavily on the material property of the tissue and the speed of colliding objects. Hence, additional efforts including dynamic relaxation are required to improve the stability of the system.
Self-consistent one-dimensional modelling of x-ray laser plasmas
International Nuclear Information System (INIS)
Wan, A.S.; Walling, R.S.; Scott, H.A.; Mayle, R.W.; Osterheld, A.L.
1992-01-01
This paper presents the simulation of a planar, one-dimensional expanding Ge x-ray laser plasma using a new code which combines hydrodynamics, laser absorption, and detailed level population calculations within the same simulation. Previously, these simulations were performed in separate steps. We will present the effect of line transfer on gains and excited level populations and compare the line transfer result with simulations using escape probabilities. We will also discuss the impact of different atomic models on the accuracy of our simulation
Absorption of laser plasma in competition with oscillation currents for a terahertz spectrum.
Li, Xiaolu; Bai, Ya; Li, Na; Liu, Peng
2018-01-01
We generate terahertz radiation in a supersonic jet of nitrogen molecules pumped by intense two-color laser pulses. The tuning of terahertz spectra from blue shift to red shift is observed by increasing laser power and stagnation pressure, and the red shift range is enlarged with the increased stagnation pressure. Our simulation reveals that the plasma absorption of the oscillation currents and expanded plasma column owing to increased laser intensity and gas number density are crucial factors in the recurrence of the red shift of terahertz spectra. The findings disclose the microscopic mechanism of terahertz radiation and present a controlling knob for the manipulation of a broadband terahertz spectrum from laser plasma.
Electron multiplier as a detector for soft x rays from synchrotron and laser plasma sources
Buckley, Christopher J.; Dermody, Geraint; Khaleque, Naz I.; Michette, Alan G.; Pfauntsch, Slawka J.; Turcu, I. C. Edmond; Allott, Ric M.
1998-11-01
An electron-tubes-LTD 129EM electron multiplier tube has been modified to act as a detector of soft x-rays. the first dynode was coated with 100 nm of CsI and the assembly was mounted in a small vacuum chamber with 100 nm thick silicon nitride entrance window. Initial tests show the detector is linear up to an input flux of approximately 1MHz on a synchrotron source and has proved effective in providing pulse height discrimination when used on a pulsed laser plasma source.
Computer assisted treatments for image pattern data of laser plasma experiments
International Nuclear Information System (INIS)
Yaoita, Akira; Matsushima, Isao
1987-01-01
An image data processing system for laser-plasma experiments has been constructed. These image data are two dimensional images taken by X-ray, UV, infrared and visible light television cameras and also taken by streak cameras. They are digitized by frame memories. The digitized image data are stored in disk memories with the aid of a microcomputer. The data are processed by a host computer and stored in the files of the host computer and on magnetic tapes. In this paper, the over view of the image data processing system and some software for data handling in the host computer are reported. (author)
DEVELOPMENT OF WATER JET PLASMA MIRROR FOR STAGING OF LASER PLASMA ACCELERATORS
International Nuclear Information System (INIS)
Panasenko, Dmitriy; Gonsalves, Anthony J.; Leemans, Wim; Nakamura, Kei; Shu, Anthony; Toth, Csaba
2009-01-01
Staging Laser Plasma Accelerators (LPAs) is necessary in order to reach beam energies of 100 GeV and above. This requires incoupling of additional laser beams into accelerating stages. In order to maintain the high average accelerating gradient of a staged LPA, it is imperative to minimize the distance that is needed for laser incoupling. A plasma mirror is proposed as the final coupling optic reducing the coupling distance from tens of meters, using a conventional optic, to as small as a few cm. Both a planar water jet and a nitrocellulose foil are used as reflecting surfacesand characterized. A maximum reflectivity of 70percent was obtained using both surfaces.
Sapsis, T.; Dijkstra, H.A.
2013-01-01
In this paper the authors study the interactions of additive noise and nonlinear dynamics in a quasi-geostrophicmodel of the double-gyre wind-driven ocean circulation. The recently developed framework of dynamically orthogonal field theory is used to determine the statistics of the flows that arise
Jaishankar, Aditya; Wee, May; Matia-Merino, Lara; Goh, Kelvin K T; McKinley, Gareth H
2015-06-05
Mamaku gum is a polysaccharide extracted from the fronds of the black tree fern found in New Zealand. The cooked pith has traditionally been used for various medicinal purposes and as a food source by the Maori people of New Zealand. It has potential applications as a thickener in the food industry and as a palliative for patients with dysphagia. Studies on the shear rheology of Mamaku gum have revealed that the gum exhibits shear thickening at a critical shear rate due to a transition from intra- to inter-molecular chain interactions upon shear-induced chain elongation. In this paper, we demonstrate that these interactions are primarily due to hydrogen bonding. We perform extensional rheology on mixtures of Mamaku gum and urea (a known disruptor of hydrogen bonds) to quantify the nature of these interactions. Capillary Breakup Extensional Rheometry (CaBER) performed on the pure Mamaku gum solutions yield plateau values of the Trouton ratio as high as ∼10(4), showing that the viscoelasticity of the gum in uniaxial elongation is much higher than in shear. For all Mamaku concentrations tested, the extensional viscosity decreases upon increasing urea concentration. Furthermore, the relaxation time decreases exponentially with increasing urea concentration. This exponential relationship is independent of the Mamaku concentration, and is identical to the relationships between urea concentration and characteristic timescales measured in nonlinear shear rheology. We show using the sticky reptation model for polymers with multiple sticker groups along the backbone how such a relationship is consistent with a linear decrease in the free energy for hydrogen bond dissociation. We then demonstrate that a time-concentration superposition principle can be used to collapse the viscoelastic properties of the Mamaku-gum/urea mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.
Nonlinear dynamics of magnetic island interacting with external helical magnetic field
International Nuclear Information System (INIS)
Nishimura, S.; Yagi, M.; Itoh, S.-I.; Itoh, K.
2009-01-01
Full text: The control of magnetic islands is one of important issues for magnetically confined fusion plasmas. Magnetic islands strongly affect the achievable β''-value by modifying transports, equilibrium fields (i.e. radial profiles of electric current, pressure and electric field) and the stability of plasmas. The induction of resonant helical magnetic fields, which interact with magnetic islands, is an effective method to control the dynamics of magnetic islands. In the Large Helical Device (LHD), magnetic islands are excited by the external magnetic, and the generation of equilibrium poloidal E x B flows by magnetic islands is observed. On the other hand, the external helical magnetic fields have been used to control the poloidal rotation and the stability of magnetic islands in tokamak plasmas. The error field, which is caused by the misalignment of toroidal magnetic coil, plays a similar role to the external helical magnetic field. The locking of the rotation of magnetic islands by error field triggers the disruption in tokamak plasmas. Thus, it is important to understand the basic mechanism of the interaction between magnetic islands and external helical magnetic fields. In this study, nonlinear simulation of drift tearing mode is performed using a set of reduced two-fluid equations, and the detailed study of the interaction between magnetic islands with external helical magnetic fields is reported. The external helical field associated with magnetic islands is imposed by means of finite amplitude of perturbed magnetic flux (vector potential) at edge boundary. In our simulation, the locking (stop) of the rotation of magnetic islands is observed. The rotation of magnetic island is basically driven by the diamagnetic drift flow and E x B flow. It is found that contributions of these flows approximately cancel each other inside the separatrix of magnetic island in the locking phase. The detailed mechanism of the locking of magnetic island rotation is
Large-field high-resolution x-ray microscope for studying laser plasmas
International Nuclear Information System (INIS)
Sauneuf, R.; Dalmasso, J.; Jalinaud, T.; Le Breton, J.; Schirmann, D.; Marioge, J.; Bridou, F.; Tissot, G.; Clotaire, J.
1997-01-01
In 1948, P. Kirkpatrick and A. V. Baez developed an x-ray microscope (energy range about 100 eV endash 10 keV) composed of two concave spherical mirrors working at grazing incidence. That device, named KB microscope, presents a 3 endash 5 μm resolution within a field having a radius about 100 μm; outside that field, its resolution lowers rapidly when the object point recedes from the center. The adjunction of two similar mirrors can notably increase the useful field (typically, the resolution can be better than 10 μm within a 2-mm-diam field of view), which is necessary for studying laser plasmas. Its main advantage with respect to more simple optics, as the pinhole, is that it can be located far enough from the plasma to avoid any destruction during the shot. We describe such a microscope that we call KBA microscope and present some images of fine metallic grids. Those grids were backlighted by x-ray sources, either a cw one or a series of laser plasmas from the Octal endash Hacute eliotrope facility. Examining the films in detail shows that the experimental results are very close to the theoretical characteristics; hence the interest of this device for the x-ray diagnostics on the future powerful laser facilities. copyright 1997 American Institute of Physics
Optical diagnostics of lead and PbGa2S4 layered crystal laser plasmas
International Nuclear Information System (INIS)
Shuaibov, A.K.; Dashchenko, A.I.; Shevera, I.V.
2001-01-01
Laser plasmas produced at the surfaces of lead and a PbGa 2 S 4 layered crystal irradiated by a neodymium laser with λ = 1.06 μm, pulse duration τ = 20 ns, and intensity W = (1-2) x 10 9 W/cm 2 are studied using optical diagnostics. It is shown that, in a lead plasma, the most intense (characteristic) lines are the PbI 405.7-nm, PbI 368.3-nm, PbI 364-nm, and PbII 220.4-nm lines. In a layered crystal plasma, the emission spectrum is an aggregation of the most intense PbI and GaI lines, whereas sulfur lines are absent. The bottlenecks of the recombination of the ionic and atomic components of the lead and PbGa 2 S 4 crystal plasmas are determined. The average propagation velocity of the lead laser plume is 18-20 km/s. A comparative analysis of the emission dynamics of PbI and GaI lines in the laser plasmas of these metals and in the plasma of a PbGa 2 S 4 crystal is carried out. The results obtained are important for the optical diagnostics of the plasmas of lead- and gallium-containing crystals and for the optimization of laser deposition of the thin films of these substances
Collective acceleration of laser plasma in a nonstationary and nonuniform magnetic field
Isaev, A.; Kozlovskiy, K.; Shikanov, A.; Vovchenko, E.
2017-12-01
This paper presents the new experimental results concerning acceleration of deuterium ions extracted from laser plasma in the rapid-growing nonuniform magnetic field in order to initiate the nuclear reactions D(d, n)3He and T(d, n)4He. For obtaining of laser plasma a Nd: YAG laser (λ = 1,06 μm) that generates in Q-switched mode the radiation pulses with the energy W ≤ 0,85 J and duration of τ ≈ 10 ns was used. Rapid-growing magnetic field was created with the discharge of Arkadyev-Marx pulsed-voltage generator to conical coil with the inductance of 0,65 μΗ. At characteristic discharge time of 30 ns, the rate of magnetic field growth achieved 2·107 T/s. Ion velocity was determined with the time-of-flight technique. During the experiment on deuterium plasma an ion flux velocity of ∼3 · 108 cm/s was obtained, which corresponds to the deuteron energy of ∼100 keV. Herewith, for target power density of ∼5·1011 W/cm2 obtaining of up to 1015 of accelerated deuterons and up to 108 of neutrons per a pulse is expected.
Foster, J. C.; Erickson, P. J.; Omura, Y.; Baker, D. N.; Kletzing, C. A.; Claudepierre, S. G.
2017-01-01
Prompt recovery of MeV (millions of electron Volts) electron populations in the poststorm core of the outer terrestrial radiation belt involves local acceleration of a seed population of energetic electrons in interactions with VLF chorus waves. Electron interactions during the generation of VLF rising tones are strongly nonlinear, such that a fraction of the relativistic electrons at resonant energies are trapped by waves, leading to significant nonadiabatic energy exchange. Through detailed examination of VLF chorus and electron fluxes observed by Van Allen Probes, we investigate the efficiency of nonlinear processes for acceleration of electrons to MeV energies. We find through subpacket analysis of chorus waveforms that electrons with initial energy of hundreds of keV to 3 MeV can be accelerated by 50 keV-200 keV in resonant interactions with a single VLF rising tone on a time scale of 10-100 ms.
International Nuclear Information System (INIS)
Haney, S.J.; Berger, K.W.; Kubiak, G.D.; Rockett, P.D.; Hunter, J.
1993-01-01
A prototype high-speed tape target transport is constructed for use in a high-repetition-rate laser plasma source. To reduce plasma debris, a 1000--5000-A-thick film of target material is supported by thin Mylar tape backing. Tape is transported to the laser focal volume at a maximum velocity of 356 cm/s, a rate sufficient to accommodate laser repetition rates of 1 kHz. The transport is fully vacuum compatible and can be retracted and then isolated from the laser plasma vacuum enclosure during tape reel replacement. The operating characteristics of the transport are described
International Nuclear Information System (INIS)
Toth, Cs.; Faure, J.; Geddes, C.G.R.; Tilborg, J. van; Leemans, W.P.
2003-01-01
In typical chirped pulse amplification (CPA) laser systems, scanning the grating separation in the optical compressor causes the well know generation of linear chirp of frequency vs. time in a laser pulse, as well as a modification of all the higher order phase terms. By setting the compressor angle slightly different from the optimum value to generate the shortest pulse, a typical scan around this value will produce significant changes to the pulse shape. Such pulse shape changes can lead to significant differences in the interaction with plasmas such as used in laser wake-field accelerators. Strong electron yield dependence on laser pulse shape in laser plasma wake-field electron acceleration experiments have been observed in the L'OASIS Lab of LBNL [1]. These experiments show the importance of pulse skewness parameter, S, defined here on the basis of the ratio of the ''head-width-half-max'' (HWHM) and the ''tail-width-halfmax'' (TWHM), respectively
Collisional effects on coherent nonlinear wave particle interactions at cyclotron harmonics
International Nuclear Information System (INIS)
Carter, M.D.; Callen, J.D.; Batchelor, D.B.; Goldfinger, R.C.
1985-06-01
When particle orbits are trapped very near a cyclotron harmonic resonance, the quasilinear concept of weakly perturbed, uncorrelated passages through resonance breaks down, and nonlinear effects become important. Numerical as well as analytic studies demonstrate that relativistic detuning of the resonance can be important for electrons even at low initial energies (approx. 20 eV) and that coupling to perturbed parallel motion can lead to strong interactions for values of the turning point where the wave frequency differs from a harmonic multiple of the bounce averaged gyrofrequency by an integral multiple of the bounce frequency. The resultant motion is described by large periodic energy excursions for which small angle Coulomb collisions or other randomization processes are required to realize net heating. Analytic formulae are derived describing the energy excursion behavior and heating in a mildly relativistic limit. Also, a Monte Carlo numerical model of the collisional effects on the orbits has been employed to study electron heating at the second harmonic cyclotron resonance and to test the analytic results. In certain regimes of collisionality, a strong enhancement over quasilinear heating has been found
Karabulut, Ibrahim
2017-11-01
We investigate theoretically the saturation problem of the nonlinear intersubband response in a symmetric quantum well. We first obtain the analytical expressions for the absorption/dispersion spectra from the steady-state solutions of the nonlinear density matrix equations. This expressions include the depolarization effect that results from the electron-electron interactions and also depends on the population difference between the first two subbands. We calculate the line shape of the dispersion spectrum and show that the dispersion spectrum becomes non-antisymetric as the intensity of the radiation increases. For larger values of the electron sheet density, this distortion becomes more apparent. We also find that the optical bistability can be obtained for appropriate values of the electron sheet density and the intensity of the optical radiation. Our results also show that the electron redistribution among the subbands by additional external factor has a dramatic effect on the nonlinear intersubband response.
Halladay, Kate; Good, Peter
2017-10-01
We present a detailed analysis of mechanisms underlying the evapotranspiration response to increased CO_2 in HadGEM2-ES, focussed on western Amazonia. We use three simulations from CMIP5 in which atmospheric CO_2 increases at 1% per year reaching approximately four times pre-industrial levels after 140 years. Using 3-hourly data, we found that evapotranspiration (ET) change was dominated by decreased stomatal conductance (g_s), and to a lesser extent by decreased canopy water and increased moisture gradient (specific humidity difference between surface and near-surface). There were large, non-linear decreases in ET in the simulation in which radiative and physiological forcings could interact. This non-linearity arises from non-linearity in the conductance term (includes aerodynamic and stomatal resistance and partitioning between the two, which is determined by canopy water availability), the moisture gradient, and negative correlation between these two terms. The conductance term is non-linear because GPP responds non-linearly to temperature and GPP is the dominant control on g_s in HadGEM2-ES. In addition, canopy water declines, mainly due to increases in potential evaporation, which further decrease the conductance term. The moisture gradient responds non-linearly owing to the non-linear response of temperature to CO_2 increases, which increases the Bowen ratio. Moisture gradient increases resulting from ET decline increase ET and thus constitute a negative feedback. This analysis highlights the importance of the g_s parametrisation in determining the ET response and the potential differences between offline and online simulations owing to feedbacks on ET via the atmosphere, some of which would not occur in an offline simulation.
Builes-Jaramillo, Alejandro; Marwan, Norbert; Poveda, Germán; Kurths, Jürgen
2017-07-01
We study the physical processes involved in the potential influence of Amazon (AM) hydroclimatology over the Tropical North Atlantic (TNA) Sea Surface Temperatures (SST) at interannual timescales, by analyzing time series of the precipitation index (P-E) over AM, as well as the surface atmospheric pressure gradient between both regions, and TNA SSTs. We use a recurrence joint probability based analysis that accounts for the lagged nonlinear dependency between time series, which also allows quantifying the statistical significance, based on a twin surrogates technique of the recurrence analysis. By means of such nonlinear dependence analysis we find that at interannual timescales AM hydrology influences future states of the TNA SSTs from 0 to 2 months later with a 90-95% statistical confidence. It also unveils the existence of two-way feedback mechanisms between the variables involved in the processes: (1) precipitation over AM leads the atmospheric pressure gradient between TNA and AM from 0 to 2 month lags, (2) the pressure gradient leads the trade zonal winds over the TNA from 0 to 3 months and from 7 to 12 months, (3) the zonal winds lead the SSTs from 0 to 3 months, and (4) the SSTs lead precipitation over AM by 1 month lag. The analyses were made for time series spanning from 1979 to 2008, and for extreme precipitation events in the AM during the years 1999, 2005, 2009 and 2010. We also evaluated the monthly mean conditions of the relevant variables during the extreme AM droughts of 1963, 1980, 1983, 1997, 1998, 2005, and 2010, and also during the floods of 1989, 1999, and 2009. Our results confirm that the Amazon River basin acts as a land surface-atmosphere bridge that links the Tropical Pacific and TNA SSTs at interannual timescales. The identified mutual interactions between TNA and AM are of paramount importance for a deeper understanding of AM hydroclimatology but also of a suite of oceanic and atmospheric phenomena over the TNA, including recently
Builes-Jaramillo, Alejandro; Marwan, Norbert; Poveda, Germán; Kurths, Jürgen
2018-04-01
We study the physical processes involved in the potential influence of Amazon (AM) hydroclimatology over the Tropical North Atlantic (TNA) Sea Surface Temperatures (SST) at interannual timescales, by analyzing time series of the precipitation index (P-E) over AM, as well as the surface atmospheric pressure gradient between both regions, and TNA SSTs. We use a recurrence joint probability based analysis that accounts for the lagged nonlinear dependency between time series, which also allows quantifying the statistical significance, based on a twin surrogates technique of the recurrence analysis. By means of such nonlinear dependence analysis we find that at interannual timescales AM hydrology influences future states of the TNA SSTs from 0 to 2 months later with a 90-95% statistical confidence. It also unveils the existence of two-way feedback mechanisms between the variables involved in the processes: (1) precipitation over AM leads the atmospheric pressure gradient between TNA and AM from 0 to 2 month lags, (2) the pressure gradient leads the trade zonal winds over the TNA from 0 to 3 months and from 7 to 12 months, (3) the zonal winds lead the SSTs from 0 to 3 months, and (4) the SSTs lead precipitation over AM by 1 month lag. The analyses were made for time series spanning from 1979 to 2008, and for extreme precipitation events in the AM during the years 1999, 2005, 2009 and 2010. We also evaluated the monthly mean conditions of the relevant variables during the extreme AM droughts of 1963, 1980, 1983, 1997, 1998, 2005, and 2010, and also during the floods of 1989, 1999, and 2009. Our results confirm that the Amazon River basin acts as a land surface-atmosphere bridge that links the Tropical Pacific and TNA SSTs at interannual timescales. The identified mutual interactions between TNA and AM are of paramount importance for a deeper understanding of AM hydroclimatology but also of a suite of oceanic and atmospheric phenomena over the TNA, including recently
He, Shuai; Ng, Ching Tai
2017-08-01
This study proposes a time-domain spectral finite element (SFE) model and investigates nonlinear guided wave interaction at a breathing crack. An extended time-domain SFE method based on the Mindlin-Hermann rod and Timoshenko beam theory is proposed to predict the nonlinear guided wave generation at the breathing crack. An SFE crack element is proposed to simulate the mode-conversion effect, in which a bilinear crack mechanism is implemented to take into account the contact nonlinearity at the breathing crack. There is good agreement between the results calculated using the proposed time-domain SFE method and three-dimensional finite element simulation. This demonstrates the accuracy of the proposed SFE method in simulating contact nonlinearity at the breathing crack. Parametric studies using the fundamental symmetric (S0) and anti-symmetric (A0) modes of guided waves are also carried out to provide physical insights into the higher harmonics generated due to the contact nonlinearity at the breathing crack. The magnitude of the higher harmonics generated as a function of the crack depth is investigated in detail. The results show that the mode-converted higher harmonic guided waves provide valuable information for damage detection.
31. European Conference on Laser Interaction with Matter. Book of abstracts
International Nuclear Information System (INIS)
2010-01-01
The ECLIM conferences on the field of high intensity laser-matter interactions. In this year has the 50th anniversary of Maiman's first laser. ECLIM is a conference for all types of laser-matter interactions, especially for those occurring at high power. New lasers, new ideas are traditionally welcome. Applications as inertial fusion energy have been the driving force in the last decades towards increasing laser intensity, and toward the discovery of new, nonlinear interactions. This time the organizers want to open the doors even broader toward short-pulse laser-plasma interactions and attophysics, organizing even special session for the Extreme Light Infrastructure (ELI). ECLIM is this time hosted the first time in Hungary, one of the sites of the future's great undertaking, the ELI laser. (S.I.)
Testik, Firat Yener
An experimental and theoretical study has been conducted to obtain a fundamental understanding of the dynamics of the sand, water and a solid object interaction as progressive gravity waves impinge on a sloping beach. Aside from obvious scientific interest, this exceedingly complex physical problem is important for naval applications, related to the behavior of disk/cylindrical shaped objects (mines) in the coastal waters. To address this problem, it was divided into a set of simpler basic problems. To begin, nonlinear progressive waves were investigated experimentally in a wave tank for the case of a rigid (impermeable) sloping bottom. Parameterizations for wave characteristics were proposed and compared with the experiments. In parallel, a numerical wave tank model (NWT) was calibrated using experimental data from a single run, and wave field in the wave tank was simulated numerically for the selected experiments. Subsequently, a layer of sand was placed on the slope and bottom topography evolution processes (ripple and sandbar dynamics, bottom topography relaxation under variable wave forcing, etc.) were investigated experimentally. Models for those processes were developed and verified by experimental measurements. Flow over a circular cylinder placed horizontally on a plane wall was also studied. The far-flow field of the cylinder placed in the wave tank was investigated experimentally and numerical results from the NWT simulations were compared with the experimental data. In the mean time, the near-flow velocity/vorticity field around a short cylinder under steady and oscillatory flow was studied in a towing tank. Horseshoe vortex formation and periodic shedding were documented and explained. With the understanding gained through the aforementioned studies, dynamics and burial/scour around the bottom objects in the wave tank were studied. Possible scenarios on the behavior of the disk-shaped objects were identified and explained. Scour around 3D cylindrical
Nonlinear wave-particle interaction upstream from the Earth's bow shock
Directory of Open Access Journals (Sweden)
C. Mazelle
2000-01-01
Full Text Available Well-defined ring-like backstreaming ion distributions have been recently reported from observations made by the 3DP/PESA-High analyzer onboard the WIND spacecraft in the Earth's foreshock at large distances from the bow shock, which suggests a local production mechanism. The maximum phase space density for these distributions remains localized at a nearly constant pitch-angle value for a large number of gyroperiods while the shape of the distribution remains very steady. These distributions are also observed in association with quasi-monochromatic low frequency (~ 50 mHz waves with substantial amplitude (δB/B>0.2. The analysis of the magnetic field data has shown that the waves are propagating parallel to the background field in the right-hand mode. Parallel ion beams are also often observed in the same region before the observation of both the ring-like distributions and the waves. The waves appear in cyclotron resonance with the ion parallel beams. We investigate first the possibility that the ion beams could provide the free energy source for driving an ion/ion instability responsible for the ULF wave occurrence. For that, we solve the wave dispersion relation with the observed parameters. Second, we show that the ring-like distributions could then be produced by a coherent nonlinear wave-particle interaction. It tends to trap the ions into narrow cells in velocity space centered on a well-defined pitch-angle, directly related to the saturation wave amplitude in the analytical theory. The theoretical predictions are in good quantitative agreement with the observations
Narrow bandwidth Laser-Plasma Accelerator driven Thomson photon source development
Geddes, C. G. R.; Tsai, H.-E.; Otero, G.; Liu, X.; van Tilborg, J.; Toth, Cs.; Vay, J.-L.; Lehe, R.; Schroeder, C. B.; Esarey, E.; Friedman, A.; Grote, D. P.; Leemans, W. P.
2017-10-01
Compact, high-quality photon sources at MeV energies can be provided by Thomson scattering of a laser from the electron beam of a Laser-Plasma Accelerator (LPA). Recent experiments and simulations demonstrate controllable LPAs in the energy range appropriate to MeV sources. Simulations indicate that high flux with narrow energy spread can be achieved via control of the scattering laser pulse shape and laser guiding, and that undesired background bremsstrahlung can be mitigated by plasma based deceleration of the electron beam after photon production. Construction of experiments and laser capabilities to combine these elements will be presented, along with initial operations, towards a compact photon source system. Work supported by US DOE NNSA DNN R&D and by Sc. HEP under contract DE-AC02-05CH11231.
Drag Reduction by Laser-Plasma Energy Addition in Hypersonic Flow
International Nuclear Information System (INIS)
Oliveira, A. C.; Minucci, M. A. S.; Toro, P. G. P.; Chanes, J. B. Jr; Myrabo, L. N.
2008-01-01
An experimental study was conducted to investigate the drag reduction by laser-plasma energy addition in a low density Mach 7 hypersonic flow. The experiments were conducted in a shock tunnel and the optical beam of a high power pulsed CO 2 TEA laser operating with 7 J of energy and 30 MW peak power was focused to generate the plasma upstream of a hemispherical model installed in the tunnel test section. The non-intrusive schlieren optical technique was used to visualize the effects of the energy addition to hypersonic flow, from the plasma generation until the mitigation of the shock wave profile over the model surface. Aside the optical technique, a piezoelectric pressure transducer was used to measure the impact pressure at stagnation point of the hemispherical model and the pressure reduction could be observed
Image-converter diagnostics of laser and laser plasma in pico-femtosecond region
International Nuclear Information System (INIS)
Schelev, M.Ya.
1979-01-01
In the present communication we would like to outline some new trends in development of pico-femtosecond image-converter diagnostics for laser and laser plasma research on the basis of the recent works done in P.N.Lebedev Physical Institute. The discussion of the following subjects will be included: new generation of picosecond image-converter tubes (ICT), pulsed control circuitry, late prototype of picosecond image-converter cameras (ICC), test installation consisting of Nd: glass and YAG lasers for production the ultra-short pulses and sinusoidally modulated radiation, methods and techniques for image tube and camera dynamic measurements in IR, visible and X-ray spectral regions. Also discussed are the image processing technique for pictures taken with picosecond ICC in order to correct the geometrical distortions, enhance pictures quality and evaluate parameters of the input signals through their recorded images. (author)
Parametric emittance measurements of electron beams produced by a laser plasma accelerator
Barber, S. K.; van Tilborg, J.; Schroeder, C. B.; Lehe, R.; Tsai, H.-E.; Swanson, K. K.; Steinke, S.; Nakamura, K.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.
2018-05-01
Laser plasma accelerators (LPA) offer an exciting possibility to deliver high energy, high brightness electrons beams in drastically smaller distance scales than is typical for conventional accelerators. As such, LPAs draw considerable attention as potential drivers for next generation light sources and for a compact linear collider. In order to asses the viability of an LPA source for a particular application, the brightness of the source should be properly characterized. In this paper, we present charge dependent transverse emittance measurements of LPA sources using both ionization injection and shock induced density down ramp injection, with the latter delivering smaller transverse emittances by a factor of two when controlling for charge density. The single shot emittance method is described in detail with a discussion on limitations related to second order transport effects. The direct role of space charge is explored through a series of simulations and found to be consistent with experimental observations.
He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme
2013-10-01
Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.
Energy Technology Data Exchange (ETDEWEB)
Anania, M. P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); INFN, Laboratori Nazionali di Frascati, I-00044 Frascati (Italy); Brunetti, E.; Wiggins, S. M.; Grant, D. W.; Welsh, G. H.; Issac, R. C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; Jaroszynski, D. A., E-mail: d.a.jaroszynski@strath.ac.uk [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Geer, S. B. van der; Loos, M. J. de [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands); Poole, M. W.; Shepherd, B. J. A.; Clarke, J. A. [ASTeC, STFC, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Gillespie, W. A. [SUPA, School of Engineering, Physics and Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); MacLeod, A. M. [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee DD1 1HG (United Kingdom)
2014-06-30
Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 10{sup 6} per shot for a 100 period undulator, with a mean peak brilliance of 1 × 10{sup 18} photons/s/mrad{sup 2}/mm{sup 2}/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs.
Li, F.; Nie, Z.; Wu, Y. P.; Guo, B.; Zhang, X. H.; Huang, S.; Zhang, J.; Cheng, Z.; Ma, Y.; Fang, Y.; Zhang, C. J.; Wan, Y.; Xu, X. L.; Hua, J. F.; Pai, C. H.; Lu, W.; Mori, W. B.
2018-04-01
We report the transverse phase space diagnostics for electron beams generated through ionization injection in a laser-plasma accelerator. Single-shot measurements of both ultimate emittance and Twiss parameters are achieved by means of permanent magnetic quadrupole. Beams with emittance of μm rad level are obtained in a typical ionization injection scheme, and the dependence on nitrogen concentration and charge density is studied experimentally and confirmed by simulations. A key feature of the transverse phase space, matched beams with Twiss parameter α T ≃ 0, is identified according to the measurement. Numerical simulations that are in qualitative agreement with the experimental results reveal that a sufficient phase mixing induced by an overlong injection length leads to the matched phase space distribution.
Generation of periodic structures on SiC upon laser plasma XUV/NIR radiations
Czech Academy of Sciences Publication Activity Database
Gemini, L.; Margarone, Daniele; Trusso, S.; Juha, Libor; Limpouch, Jiří; Mocek, Tomáš; Ossi, P.M.
2013-01-01
Roč. 31, č. 3 (2013), s. 547-550 ISSN 0263-0346 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE.2.3.20.0087; GA MŠk ED2.1.00/01.0027 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087; HILASE(XE) CZ.1.05/2.1.00/01.0027 Institutional support: RVO:68378271 Keywords : generation of periodic structures * laser plasma irradiation of SiC * LDPE plasma formation by ultra-short pulse laser * XUV/NIR dual action Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.701, year: 2013
Analysis on laser plasma emission for characterization of colloids by video-based computer program
Putri, Kirana Yuniati; Lumbantoruan, Hendra Damos; Isnaeni
2016-02-01
Laser-induced breakdown detection (LIBD) is a sensitive technique for characterization of colloids with small size and low concentration. There are two types of detection, optical and acoustic. Optical LIBD employs CCD camera to capture the plasma emission and uses the information to quantify the colloids. This technique requires sophisticated technology which is often pricey. In order to build a simple, home-made LIBD system, a dedicated computer program based on MATLAB™ for analyzing laser plasma emission was developed. The analysis was conducted by counting the number of plasma emissions (breakdowns) during a certain period of time. Breakdown probability provided information on colloid size and concentration. Validation experiment showed that the computer program performed well on analyzing the plasma emissions. Optical LIBD has A graphical user interface (GUI) was also developed to make the program more user-friendly.
Cantrell, John H., Jr.; Cantrell, Sean A.
2008-01-01
A comprehensive analytical model of the interaction of the cantilever tip of the atomic force microscope (AFM) with the sample surface is developed that accounts for the nonlinearity of the tip-surface interaction force. The interaction is modeled as a nonlinear spring coupled at opposite ends to linear springs representing cantilever and sample surface oscillators. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a standard iteration procedure. Solutions are obtained for the phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) techniques including force modulation microscopy, atomic force acoustic microscopy, ultrasonic force microscopy, heterodyne force microscopy, resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), and the commonly used intermittent contact mode (TappingMode) generally available on AFMs. The solutions are used to obtain a quantitative measure of image contrast resulting from variations in the Young modulus of the sample for the amplitude and phase images generated by the A-AFM techniques. Application of the model to RDF-AFUM and intermittent soft contact phase images of LaRC-cp2 polyimide polymer is discussed. The model predicts variations in the Young modulus of the material of 24 percent from the RDF-AFUM image and 18 percent from the intermittent soft contact image. Both predictions are in good agreement with the literature value of 21 percent obtained from independent, macroscopic measurements of sheet polymer material.
Simulation of QED effects in ultrahigh intensity laser-plasma interaction
International Nuclear Information System (INIS)
Kostyukov, I.; Nerush, E.
2010-01-01
Complete text of publication follows. Due to an impressive progress in laser technology, laser pulses with peak intensity of nearly 2 x 10 22 W/cm 2 are now available in laboratory. When the matter is irradiated by so intense laser pulses high energy density plasma is produced. Besides of fundamental interest such plasma is the efficient source of particles and radiation with extreme parameters that opens bright perspectives in developments of advanced particle accelerators, next generation of radiation sources, laboratory modelling of astrophysics phenomena etc. Even high laser intensity the radiation reaction and QED effects become important. One of the QED effects, which recently attracts much attention, is the electron-positron plasma creation in strong laser field. The plasma can be produced via electromagnetic cascades: the seeded charged particles is accelerated in the field of counter-propagating laser pulses, then they emit energetic photons, the photons by turn decay in the laser field and create electron-positron pairs. The pair particles accelerated in the laser field produce new generation of the photons and pairs. For self-consistent study of the electron-positron plasma dynamics in the laser field we develop 2D code based on particle-in-cell and Monte-Carlo methods. The electron, positron and photon dynamics as well as evolution of the plasma and laser fields are calculated by PIC technique while photon emission and pair production are calculated by Monte-Carlo method. We simulate pair production in the field of counter-propagating linearly polarized laser pulses. It is shown that for the laser intensity above threshold the plasma production becomes so intense that the laser pulse are strongly absorbed in the plasma. The laser intensity threshold and the rate of laser field absorption are calculated. Acknowledgements. This work has been supported by federal target 'The scientific and scientific-pedagogical personnel of innovation in Russia' and by the Russian Foundation for Basic Research.
Energy Technology Data Exchange (ETDEWEB)
Singh, Mamta; Gupta, D. N., E-mail: dngupta@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Suk, H. [Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 500 712 (Korea, Republic of)
2015-06-15
We propose an idea to enhance the efficiency of second- and third-harmonic generation by considering the amplitude-modulation of the fundamental laser pulse. A short-pulse laser of finite spot size is modeled as amplitude modulated in time. Amplitude-modulation of fundamental laser contributes in quiver velocity of the plasma electrons and produces the strong plasma-density perturbations, thereby increase in current density at second- and third-harmonic frequency. In a result, the conversion efficiency of harmonic generation increases significantly. Power conversion efficiency of harmonic generation process is the increasing function of the amplitude-modulation parameter of the fundamental laser beam. Harmonic power generated by an amplitude modulated laser is many folds higher than the power obtained in an ordinary case.
International Nuclear Information System (INIS)
Singh, Mamta; Gupta, D. N.; Suk, H.
2015-01-01
We propose an idea to enhance the efficiency of second- and third-harmonic generation by considering the amplitude-modulation of the fundamental laser pulse. A short-pulse laser of finite spot size is modeled as amplitude modulated in time. Amplitude-modulation of fundamental laser contributes in quiver velocity of the plasma electrons and produces the strong plasma-density perturbations, thereby increase in current density at second- and third-harmonic frequency. In a result, the conversion efficiency of harmonic generation increases significantly. Power conversion efficiency of harmonic generation process is the increasing function of the amplitude-modulation parameter of the fundamental laser beam. Harmonic power generated by an amplitude modulated laser is many folds higher than the power obtained in an ordinary case
Energy Technology Data Exchange (ETDEWEB)
Ma, Tammy Yee Wing [Univ. of California, San Diego, CA (United States)
2010-01-01
The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.
Calculating the radiation characteristics of accelerated electrons in laser-plasma interactions
Czech Academy of Sciences Publication Activity Database
Li, X.F.; Yu, Q.; Gu, Yanjun; Qu, J.F.; Ma, Y.Y.; Kong, Q.; Kawata, S.
2016-01-01
Roč. 23, č. 3 (2016), s. 1-5, č. článku 033113. ISSN 1070-664X R&D Projects: GA MŠk EF15_008/0000162; GA MŠk LQ1606 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : wakefield accelerator * x- rays * beams * driven Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.115, year: 2016
Proton Radiography of Laser-Plasma Interactions with Picosecond Time Resolution
International Nuclear Information System (INIS)
Mackinnon, A J; Patel, P K; Town, R J; Hatchett, S P; Hicks, D; Phillips, T H; Wilks, S C; Price, D; Key, M H; Lasinski, B; Langdon, B; Borghesi, M; Romagnani, L; Kar, S
2005-01-01
Radiography of laser-produced plasmas with MeV protons has the potential to provide new information on plasma conditions in extreme states of matter. Protons with energies up to many hundreds MeV, produced by large scale accelerators have been recently been used to obtain mass density radiographs of the behavior of large samples which have been shocked on microsecond timescales with approximately mm spatial resolution. The recent discovery of laminar proton beams accelerated to multi-MeV energies by picosecond duration laser beams has provided the opportunity to probe dense plasmas with hitherto unparalleled temporal and spatial resolution
A four-color beam smoothing irradiation system for laser-plasma interaction experiments at LLNL
International Nuclear Information System (INIS)
Pennington, D.M.; Henesian, M.A.; Wilcox, R.B.; Weiland, T.L.; Eimerl, D.; Ehrlich, R.B.; Laumann, C.W.; Miller, J.L.
1995-01-01
A novel four-color beam smoothing scheme with a capability similar to that planned for the proposed National Ignition Facility has been deployed on the Nova laser, and has been successfully used for laser fusion experiments. Wavefront aberrations in high power laser systems produce nonuniformities in the energy distribution of the focal spot that can significantly degrade the coupling of the energy into a fusion target, driving various plasma instabilities. The introduction of temporal and spatial incoherence over the face of the beam using techniques such as smoothing by spectral dispersion (SSD) can reduce these variation in the focal irradiance when averaged over a finite time interval. We developed a multiple frequency source that is spatially separated into four quadrants, each containing a different central frequency. Each quadrant is independently converted to the third harmonic in a four-segment Type I/ Type II KDP crystal array with independent phase-matching for efficient frequency conversion. Up to 2.3 kJ of third harmonic light is generated in a 1 ns pulse, corresponding to up to 65% conversion efficiency. SSD is implemented by adding limited frequency modulated bandwidth to each frequency component. Smoothing by spectral dispersion is implemented during the spatial separation of the FM modulated beams to provide additional smoothing, reaching a 16% rms intensity variation level. The four- color system was successfully used to probe NIF-like plasmas, producing 2x10 15 W/cm 2 . This paper discusses the detailed implementation and performance of the segmented four-color system on the Nova laser system
Target Surface Area Effects on Hot Electron Dynamics from High Intensity Laser-Plasma Interactions
2016-08-19
experiment was performed using theHERCULES [22] laser facility at theUniversity ofMichigan. HERCULES is a Ti:sapphire system (l = 800 nm)which...shifting of the aK emission as a result of heating . A reduced aK signal was not observed for lower volume targets investigated here, indicating the...SandnerW2010New J. Phys. 12 113013 [18] HenigA et al 2009Phys. Rev. Lett. 102 095002 [19] Ter-Avetisyan S, SchnürerM,Nickles PV , KalashnikovM,Risse E
Electron plasma waves in CO/sub 2/ laser plasma interactions
International Nuclear Information System (INIS)
Baldis, H.A.; Villeneuve, D.M.; Walsh, C.J.
1984-01-01
During the past few years, the use of Thomson scattering in CO/sub 2/ laser produced plasmas has permitted the identification and study of electron plasma waves and ion waves, driven by various instabilities in the plasma corona, such as Stimulated Raman Scattering (SRS), two plasmon decay, and Stimulated Brillouin Scattering (SBS). Since these instabilities may coexist in the plasma, the density fluctuations associated with one wave may influence the behaviour of one or more of the other instabilities. The authors discuss the experimental evidence of such effects and, in particular, the consequences of a recent experiment in which the ion waves driven by SBS were observed to adversely affect the production of the electron plasma waves driven by SRS. In that experiment, a strong correlation was observed between the onset of SBS and the disappearance of the electron plasma waves driven by SRS at low densities (n/sub e/ n/sub e/ > 0.05 n/sub c/)
Vlasov simulations of self generated strong magnetic fields in plasmas and laser-plasma interaction
Directory of Open Access Journals (Sweden)
Inglebert A.
2013-11-01
Full Text Available A new formulation based on Hamiltonian reduction technique using the invariance of generalized canonical momentum is introduced for the study of relativistic Weibel-type instability. An example of application is given for the current filamentation instability resulting from the propagation of two counter-streaming electron beams in the relativistic regime of the instability. This model presents a double advantage. From an analytical point of view, the method is exact and standard fluid dispersion relations for Weibel or filamentation instabilies can be recovered. From a numerical point of view, the method allows a drastic reduction of the computational time. A 1D multi-stream Vlasov-Maxwell code is developed using such dynamical invariants in the perpendicular momentum space. Numerical comparison with a full Vlasov-Maxwell system has also been carried out to show the efficiency of this reduction technique.
International Nuclear Information System (INIS)
Bonnaud, G.; Reisse, C.
1986-04-01
Laser-irradiated plasma were simulated by means of an electromagnetic particle code 1 D 1/2. The aim was to study the influence of the laser wave spectral band width on stimulated Raman scattering. The results given were obtained with two different kinds of laser source: a purely monochromatic wave, used to study the effect of the plasma density, and a source with several distinct frequencies of the same intensity. The main results on the Raman scattering growth rate, the back-scattering and forward-scattering rates and the production of suprathermal electrons are given. The influence of irradiance and ion mobility is investigated. Part of this work was presented at the 14th Anomalous Absorption Conference held in May 1984 at Charlottesville (Virgina - United States) [fr
Target surface area effects on hot electron dynamics from high intensity laser-plasma interactions
Zulick, C.; Raymond, A.; McKelvey, A.; Chvykov, V.; Maksimchuk, A.; Thomas, A. G. R.; Willingale, L.; Yanovsky, V.; Krushelnick, K.
2016-06-01
Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a {K}α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Hybrid Vlasov-Fokker-Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.
Energetic beams of negative and neutral hydrogen from intense laser plasma interaction
Czech Academy of Sciences Publication Activity Database
Abicht, F.; Prasad, R.; Borghesi, Marco; Priebe, G.; Braenzel, J.; Andreev, A.; Nickles, P.V.; Schnürer, M.; Jequier, S.; Revet, G.; Tikhonchuk, V.; Ter-Avetisyan, Sargis
2013-01-01
Roč. 103, č. 25 (2013), "253501-1"-"253501-5" ISSN 0003-6951 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : charge-exchange * cross-sections * atomic-hydrogen * helium ions * gases * potassium * protons Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.515, year: 2013
Osipov, V. V.; Platonov, V. V.; Lisenkov, V. V.
2009-06-01
The dynamics of the plume ejected from the surface of solid targets (YSZ, Nd:YAG and graphite) by a CO2 laser pulse with a duration of ~500 μs (at the 0.03 level), energy of 1.0-1.3 J and peak power of 6-7 kW have been studied using high-speed photography of the plume luminescence and shadow. The targets were used to produce nanopowders by laser evaporation. About 200 μs after termination of the pulse, shadowgraph images of the plumes above the YSZ and Nd:YAG targets showed dark straight tracks produced by large particles. The formation of large (~10 μm) particles is tentatively attributed to cracking of the solidified melt at the bottom of the ablation crater. This is supported by the fact that no large particles are ejected from graphite, which sublimes without melting. Further support to this hypothesis is provided by numerical 3D modelling of melt cooling in craters produced by laser pulses of different shapes.
High quality electron bunch generation with CO2-laser-plasma interaction
Zhang, Lingang; Shen, Baifei; Xu, Jiancai; Ji, Liangliang; Zhang, Xiaomei; Wang, Wenpeng; Zhao, Xueyan; Yi, Longqing; Yu, Yahong; Shi, Yin; Xu, Tongjun; Xu, Zhizhan
2015-02-01
CO2 laser-driven electron acceleration in low-density plasma is demonstrated using particle-in-cell simulation. An intense CO2 laser pulse of long wavelength excites a wake bubble that has a large elongated volume for accelerating a large number of electrons before reaching the charge saturation limit. A transversely injected laser pulse is used to induce and control the electron injection. It is found that an electron bunch with total charge up to 10 nC and absolute energy spread less than 16 MeV can be obtained. As a result, the charge per energy interval of the bunch reaches up to 0.6 nC/MeV. Intense CO2-laser based electron acceleration can provide a new direction for generating highly charged electron bunches with low energy spread, which is of much current interest, especially for table-top X-ray generation.
International Nuclear Information System (INIS)
Liu, Zhaohong; Liu, Simin; Guo, Ru; Song, Tao; Zhu, Nan
2007-01-01
We study experimentally the interaction of a dark spot with a nonlinear photonic lattice with fully incoherent white light emitted from an incandescent bulb in the self-defocussing photovoltaic media when the dark spot is aimed at different positions of lattices with different lattice spacing. In this case a host of novel phenomena is demonstrated, including dark spot induced lattice dislocation-deformation, the annihilation of the dark spot and so on. Results demonstrate that the interaction between incoherent dark spot and photonic lattice is always attraction and the large-spacing photonic lattice is analogous to the continuous medium
Nonlinear interaction of infrared waves on a VO2 surface at a semiconductor-metal phase transition
Berger, N. K.; Zhukov, E. A.; Novokhatskii, V. V.
1984-04-01
Nonlinear interactions (including wavefront reversal) of light from CW or pulsed 10.6-micron CO2 lasers at the semiconductor-metal phase transition in a VO2 film are investigated experimentally. The results are presented in graphs and characterized in detail. The intensity reflection coefficients of the three-wave interactions are found to be 0.5 percent for a CW reference wave of intensity 900 mW/sq cm and 42 percent for a pulsed reference wave of threshold density 600-800 microjoule/sq cm.
Mann, Nishan Singh
Photonic crystal waveguides (PCWs) are nano-scale devices offering an exciting platform for exploring and exploiting enhanced linear and nonlinear light-matter interactions, aided in-part by slowing down the group velocity (vg) of on-chip photons. However, with potential applications in telecommunications, bio-sensing and quantum computing, the road to commercialization and practical devices is hindered by our limited understanding of the influence of structural disorder on linear and nonlinear light propagation. This thesis refines and develops state-of-the-art mathematical and numerical models for understanding the important role of disorder-related optical phenomena for PCWs in the linear and optical nonlinear regime. The importance of Bloch modes is demonstrated by computing the power loss caused by disorder-induced scattering for various dispersion engineered PCWs. The theoretical results are found to be in very good agreement with related experiments and it is shown how dispersion engineered designs can minimize the Bloch fields around spatial imperfections resulting in a radical departure from the usual assumed scaling vg. -2 of backscatteringlosses. We also conduct a systematic investigation of the influence of intra-hole correlation length, a parameter characterizing disorder on backscattering losses and find the loss behaviour to be qualitatively dependent on waveguide design and frequency. We then model disorder-induced resonance shifts to compute the ensemble averaged disordered density of states, accounting for important local field effects which are crucial in achieving good qualitative agreement with experiments. Lastly, motivated by emerging experiments examining enhanced nonlinear interactions, we develop an intuitive time dependent coupled mode formalism to derive propagation equations describing nonlinear pulse propagation in the presence of disorder-induced multiple scattering. The framework establishes a natural length scale for each physical
Allen, Karina L; Byrne, Susan M; Crosby, Ross D; Stice, Eric
2016-12-01
Almost no research has tested whether risk factors interact in the prediction of future eating disorder onset, which might suggest qualitatively distinct etiologic pathways. Accordingly, this prospective study tested for possible interactions between risk factors in the prediction of binge eating and purging eating disorders in adolescents. It also examined sex differences in pathways to risk. Two analytical approaches were used: (1) classification tree analysis (CTA), which is ideally suited to identifying non-linear interactions and the optimal cut-points for defining risk, with follow-up random forest analyses; and (2) two-way interaction terms in a series of logistic regression models. Data were drawn from the Western Australian Pregnancy Cohort (Raine) Study, a population-based study that followed participants from pre-birth to young adulthood. This study involved 1297 adolescents (49% male), 146 (11%) of whom developed bulimia nervosa, binge eating disorder or purging disorder in late adolescence. In CTA, sex was the first and most potent predictor of eating disorder risk with females showing a 5-fold increase in risk relative to males. For males and females, weight and eating concerns were the next most potent predictor of risk and three risk groups emerged, reflecting non-linear risk. For females with intermediate weight and eating concerns, externalizing problems emerged as an additional predictor. Interaction terms in logistic regression models did not produce significant results after correcting for multiple testing. Findings advance knowledge on risk pathways to eating disorder onset, highlight non-linear risk processes, and provide cut-points for prospectively identifying high-risk youth for prevention programs. Copyright Â© 2016. Published by Elsevier Ltd.
Automated detection and analysis of particle beams in laser-plasma accelerator simulations
Energy Technology Data Exchange (ETDEWEB)
Ushizima, Daniela Mayumi; Geddes, C.G.; Cormier-Michel, E.; Bethel, E. Wes; Jacobsen, J.; Prabhat, ,; R.ubel, O.; Weber, G,; Hamann, B.
2010-05-21
Numerical simulations of laser-plasma wakefield (particle) accelerators model the acceleration of electrons trapped in plasma oscillations (wakes) left behind when an intense laser pulse propagates through the plasma. The goal of these simulations is to better understand the process involved in plasma wake generation and how electrons are trapped and accelerated by the wake. Understanding of such accelerators, and their development, offer high accelerating gradients, potentially reducing size and cost of new accelerators. One operating regime of interest is where a trapped subset of electrons loads the wake and forms an isolated group of accelerated particles with low spread in momentum and position, desirable characteristics for many applications. The electrons trapped in the wake may be accelerated to high energies, the plasma gradient in the wake reaching up to a gigaelectronvolt per centimeter. High-energy electron accelerators power intense X-ray radiation to terahertz sources, and are used in many applications including medical radiotherapy and imaging. To extract information from the simulation about the quality of the beam, a typical approach is to examine plots of the entire dataset, visually determining the adequate parameters necessary to select a subset of particles, which is then further analyzed. This procedure requires laborious examination of massive data sets over many time steps using several plots, a routine that is unfeasible for large data collections. Demand for automated analysis is growing along with the volume and size of simulations. Current 2D LWFA simulation datasets are typically between 1GB and 100GB in size, but simulations in 3D are of the order of TBs. The increase in the number of datasets and dataset sizes leads to a need for automatic routines to recognize particle patterns as particle bunches (beam of electrons) for subsequent analysis. Because of the growth in dataset size, the application of machine learning techniques for
Detection of interactions between myogenic and TGF mechanisms using nonlinear analysis
DEFF Research Database (Denmark)
Chon, K H; Chen, Y M; Marmarelis, V Z
1994-01-01
Previous studies using linear techniques have provided valuable insights into the dynamic characteristics of whole kidney autoregulation and have led to the general conclusion that the myogenic mechanism and tubuloglomerular feedback (TGF) are highly nonlinear control mechanisms. To explore further...... for computation of the kernels have made this technique more attractive for the study of the dynamics of nonlinear physiological systems, such as the system mediating renal autoregulation. In this study, the general theory and requirements for using this technique are discussed. The feasibility of using...
Liepmann, H. W.; Torczynski, J. R.
1983-01-01
Second sound techniques were used to study superfluid helium. Second sound shock waves produced relative velocities in the bulk fluid. Maximum counterflow velocities produced in this way are found to follow the Langer-Fischer prediction for the fundamental critical velocity in its functional dependence on temperature and pressure. Comparison of successive shock and rotating experiments provides strong evidence that breakdown results in vorticity production in the flow behind the shock. Schlieren pictures have verified the planar nature of second sound shocks even after multiple reflections. The nonlinear theory of second sound was repeatedly verified in its prediction of double shocks and other nonlinear phenomena.
2016 CIME Course on Nonlocal and Nonlinear Diffusions and Interactions : New Methods and Directions
Grillo, Gabriele
2017-01-01
Presenting a selection of topics in the area of nonlocal and nonlinear diffusions, this book places a particular emphasis on new emerging subjects such as nonlocal operators in stationary and evolutionary problems and their applications, swarming models and applications to biology and mathematical physics, and nonlocal variational problems. The authors are some of the most well-known mathematicians in this innovative field, which is presently undergoing rapid development. The intended audience includes experts in elliptic and parabolic equations who are interested in extending their expertise to the nonlinear setting, as well as Ph.D. or postdoctoral students who want to enter into the most promising research topics in the field.
AUTHOR|(CDS)2160109; Støvneng, Jon Andreas
2017-08-15
The performance of high-energy circular hadron colliders, as the Large Hadron Collider, is limited by beam-beam interactions. The strength of the beam-beam interactions will be higher after the upgrade to the High-Luminosity Large Hadron Collider, and also in the next generation of machines, as the Future Circular Hadron Collider. The strongly nonlinear force between the two opposing beams causes diverging Hamiltonians and drives resonances, which can lead to a reduction of the lifetime of the beams. The nonlinearity makes the effect of the force difficult to study analytically, even at first order. Numerical models are therefore needed to evaluate the overall effect of different configurations of the machines. For this thesis, a new code named CABIN (Cuda-Accelerated Beam-beam Interaction) has been developed to study the limitations caused by the impact of strong beam-beam interactions. In particular, the evolution of the beam emittance and beam intensity has been monitored to study the impact quantitatively...
Energy Technology Data Exchange (ETDEWEB)
Krivitsky, V.S.; Vladimirov, S.V. (Academy of Sciences of the USSR, Moscow (USSR). General Physics Institute. Theoretical Dept.)
1991-10-01
The evolution of the distribution function due to the simultaneous nonlinear interaction of plasma particles with resonant and non-resonant waves is studied. A stationary particle distribution resulting from a balance of the quasi-linear interaction and the nonlinear one is found. The temporal evolution of an initial {delta}-function-shaped distribution (like a 'beam') is examined in the one-dimensional case. General formulae are obtained for stochastic particle acceleration. (author).
A direct approach to nonlinear shells with application to surface-substrate interactions
Czech Academy of Sciences Publication Activity Database
Šilhavý, Miroslav
2013-01-01
Roč. 1, č. 2 (2013), s. 211-232 ISSN 2326-7186 Institutional support: RVO:67985840 Keywords : thin films * nonlinear shells * surface geometry Subject RIV: BA - General Mathematics http://msp.org/memocs/2013/1-2/p04.xhtml
Magneto-elastic oscillator: Modeling and analysis with nonlinear magnetic interaction
Kumar, K. Aravind; Ali, Shaikh Faruque; Arockiarajan, A.
2017-04-01
The magneto-elastically buckled beam is a classic example of a nonlinear oscillator that exhibits chaotic motions. This system serves as a model to analyze the motion of elastic structures in magnetic fields. The system follows a sixth order magneto-elastic potential and may have up to five static equilibrium positions. However, often the non-dimensional Duffing equation is used to approximate the system, with the coefficients being derived from experiments. In few other instances, numerical methods are used to evaluate the magnetic field values. These field values are then used to approximate the nonlinear magnetic restoring force. In this manuscript, we derive analytical closed form expressions for the magneto-elastic potential and the nonlinear restoring forces in the system. Such an analytical formulation would facilitate tracing the effect of change in a parameter, such as the magnet dimension, on the dynamics of the system. The model is derived assuming a single mode approximation, taking into account the effect of linear elastic and nonlinear magnetic forces. The developed model is then numerically simulated to show that it is accurate in capturing the system dynamics and bifurcation of equilibrium positions. The model is validated through experiments based on forced vibrations of the magneto-elastic oscillator. To gather further insights about the magneto-elastic oscillator, a parametric study has been conducted based on the field strength of the magnets and the distance between the magnets and the results are reported.
Entanglement of a nonlinear two two-level atoms interacting with ...
Indian Academy of Sciences (India)
... occupation probabilities in the case of even and odd deformed coherent states. The results show that the deformed fields play important roles in the evolution of entanglement. Also, the results demonstrate that entanglement sudden death, sudden birth and long-distance can be controlled by the deformation and nonlinear ...
A direct approach to nonlinear shells with application to surface-substrate interactions
Šilhavý, M. (Miroslav)
2013-01-01
International audience; he paper develops a direct, intrinsic approach to the equilibrium equations of bodies coated by a thin film with a nonlinear shell like structure. The forms of the equations in the reference and actual configurations are considered. The equations are shown to coincide with those obtained by using coordinate systems on the film or on the thin shell.
Palmero, Faustino; Lemos, M; Sánchez-Rey, Bernardo; Casado-Pascual, Jesús
2018-01-01
This book presents an overview of the most recent advances in nonlinear science. It provides a unified view of nonlinear properties in many different systems and highlights many new developments. While volume 1 concentrates on mathematical theory and computational techniques and challenges, which are essential for the study of nonlinear science, this second volume deals with nonlinear excitations in several fields. These excitations can be localized and transport energy and matter in the form of breathers, solitons, kinks or quodons with very different characteristics, which are discussed in the book. They can also transport electric charge, in which case they are known as polarobreathers or solectrons. Nonlinear excitations can influence function and structure in biology, as for example, protein folding. In crystals and other condensed matter, they can modify transport properties, reaction kinetics and interact with defects. There are also engineering applications in electric lattices, Josephson junction a...
Borisyuk, P. V.; Chubunova, E. V.; Lebedinskii, Yu Yu; Tkalya, E. V.; Vasilyev, O. S.; Yakovlev, V. P.; Strugovshchikov, E.; Mamedov, D.; Pishtshev, A.; Karazhanov, S. Zh
2018-05-01
We report the results of experimental studies related to implantation of thorium ions into thin silicon dioxide by pulsed plasma flux expansion. Thorium ions were generated by laser ablation from a metal target, and the ionic component of the laser plasma was accelerated in an electric field created by the potential difference (5, 10 and 15 kV) between the ablated target and a SiO2/Si (0 0 1) sample. The laser ablation system installed inside the vacuum chamber of the electron spectrometer was equipped with a YAG:Nd3 + laser having a pulse energy of 100 mJ and time duration of 15 ns in the Q-switched regime. The depth profile of thorium atoms implanted into the 10 nm thick subsurface areas together with their chemical state as well as the band gap of the modified silicon oxide at different conditions of implantation processes were studied by means of x-ray photoelectron spectroscopy and reflected electron energy loss spectroscopy methods. Analysis of the chemical composition showed that the modified silicon oxide film contains complex thorium silicates. Depending on the local concentration of thorium atoms, the experimentally established band gaps were located in the range 6.0–9.0 eV. Theoretical studies of the optical properties of the SiO2 and ThO2 crystalline systems were performed by ab initio calculations within hybrid functional. The optical properties of the SiO2/ThO2 composite were interpreted on the basis of the Bruggeman effective medium approximation. A quantitative assessment of the yield of isomeric nuclei in ‘hot’ laser plasma at the early stages of expansion was performed. The estimates made with experimental results demonstrated that the laser implantation of thorium ions into the SiO2 matrix can be useful for further research of low-lying isomeric transitions in a 229Th isotope with energy of 7.8 +/- 0.5 eV.
International Nuclear Information System (INIS)
Aihara, S.; Atsumi, K.; Ujiie, K.; Emori, K.; Odajima, M.; Masuda, K.
1983-01-01
The objective of this paper is to evaluate the nonlinear soil-structure interaction effects resulting from base mat uplift for static lateral loads. Nonlinear soil-structure interaction effects are modeled through the use of equivalent soil-structure interaction frictional and axial springs, which properties are determined by results of experimental data. It is assumed that normal stresses in compression and corresponding shear stresses, and friction, can occur in the area of contact between the embedded structure and soil. The remaining parts of the structure and soil are based on elastic analysis. A two-dimensional finite element method with incremental loadings is applied. The substructuring technique is used to reduce computation time. The results of this method with respect to the contact ratio of the base mat are compared with the values obtained by static elastic calculation which is simply derived from an overturning moment and a vertical load of the structure. This analytical concept will be developed into dynamic problems, and then it will be possible to state whether or not this concept can represent a true alternative for the contact ratio of the base mat of a structure. (orig./HP)
Wu, Jinju; Cheng, Jian; Xu, Zhiwei; Zhao, Kefu; Zhao, Desheng; Xie, Mingyu; Yang, Huihui; Wen, Liying; Li, Kesheng; Su, Hong
2016-10-01
Hand, foot and mouth disease (HFMD) is one of the major infectious diseases among children and remains a health threat, especially among Asian countries. Many epidemiologic studies suggested significant association of air temperature and humidity with childhood HFMD; however, evidence on the temperature effects on childhood HFMD in temperate cities is limited, and the interactive effects of temperature and humidity have not been studied yet. Daily counts of HFMD in children younger than 15 years of age and daily meteorologic variables during 2010 to 2012 were obtained in Hefei, China. A distributed lag nonlinear model was applied to estimate the potential nonlinear association between temperature and childhood HFMD. The interactive effects between temperature and humidity on childhood HFMD were also investigated. Temperature rise was associated with higher risk of childhood HFMD. Within the incubation period of HFMD, temperature rise appeared to have the acute effects on childhood HFMD, and a 5°C increase of temperature at lag 0-6 days was associated with 24.8% (95% confidence interval: 11.94%-39.10%) increase of childhood HFMD. Females and children of 0-4 years of agewere more vulnerable to temperature rise. Notably, there were obvious combined effects between temperature and humidity on childhood HFMD-the risk of childhood HFMD elevated at higher temperature and humidity level. This study provides evidence that temperature and humidity may jointly affect childhood HFMD, and such interactive impact needs to be considered when evaluating the temperature-childhood HFMD relationship.
Westra, H.J.R.
2012-01-01
In this Thesis, nonlinear dynamics and nonlinear interactions are studied from a micromechanical point of view. Single and doubly clamped beams are used as model systems where nonlinearity plays an important role. The nonlinearity also gives rise to rich dynamic behavior with phenomena like
Energy Technology Data Exchange (ETDEWEB)
Chen, H.W.; Aine, C.J.; Flynn, E.R.; Wood, C.C.
1996-02-01
Reciprocal connections, in essence, are the dynamic wiring (connections) of the neural network circuitry. Given the high complexity of the neural circuitry in the human brain, it is quite a challenge to study the dynamic wiring of highly parallel and widely distributed neural networks. The measurements of stimulus evoked coherent oscillations provide indirect evidence of dynamic wiring. In this study, in addition to the coherent oscillation measurements, two more techniques are discussed for testing possible dynamic wiring: measurements of spatio-temporal interactions beyond the classical receptive fields, and neural structural testing using nonlinear systems analysis.
Czech Academy of Sciences Publication Activity Database
Kosík, Adam; Feistauer, M.; Hadrava, Martin; Horáček, Jaromír
2015-01-01
Roč. 267, September (2015), s. 382-396 ISSN 0096-3003 R&D Projects: GA ČR(CZ) GAP101/11/0207 Institutional support: RVO:61388998 Keywords : discontinuous Galerkin method * nonlinear elasticity * compressible viscous flow * fluid–structure interaction Subject RIV: BI - Acoustics Impact factor: 1.345, year: 2015 http://www. science direct.com/ science /article/pii/S0096300315002453/pdfft?md5=02d46bc730e3a7fb8a5008aaab1da786&pid=1-s2.0-S0096300315002453-main.pdf
Berger, N. K.; Zhukov, E. A.; Novokhatskiĭ, V. V.
1984-04-01
The use of a semiconductor-metal phase transition for wavefront reversal of laser radiation was proposed. An investigation was made of nonlinear reflection of CO2 laser radiation at a phase transition in VO2. A three-wave interaction on a VO2 surface was achieved using low-power cw and pulsed CO2 lasers. In the first case, the intensity reflection coefficient was 0.5% for a reference wave intensity of 0.9 W/cm2 and in the second case, it was 42% for a threshold reference wave energy density of 0.6-0.8 mJ/cm2.
Directory of Open Access Journals (Sweden)
Fan Yuxin
2014-12-01
Full Text Available A fluid–structure interaction method combining a nonlinear finite element algorithm with a preconditioning finite volume method is proposed in this paper to simulate parachute transient dynamics. This method uses a three-dimensional membrane–cable fabric model to represent a parachute system at a highly folded configuration. The large shape change during parachute inflation is computed by the nonlinear Newton–Raphson iteration and the linear system equation is solved by the generalized minimal residual (GMRES method. A membrane wrinkling algorithm is also utilized to evaluate the special uniaxial tension state of membrane elements on the parachute canopy. In order to avoid large time expenses during structural nonlinear iteration, the implicit Hilber–Hughes–Taylor (HHT time integration method is employed. For the fluid dynamic simulations, the Roe and HLLC (Harten–Lax–van Leer contact scheme has been modified and extended to compute flow problems at all speeds. The lower–upper symmetric Gauss–Seidel (LU-SGS approximate factorization is applied to accelerate the numerical convergence speed. Finally, the test model of a highly folded C-9 parachute is simulated at a prescribed speed and the results show similar characteristics compared with experimental results and previous literature.
Li, Zhaoying; Zhou, Wenjie; Liu, Hao
2016-09-01
This paper addresses the nonlinear robust tracking controller design problem for hypersonic vehicles. This problem is challenging due to strong coupling between the aerodynamics and the propulsion system, and the uncertainties involved in the vehicle dynamics including parametric uncertainties, unmodeled model uncertainties, and external disturbances. By utilizing the feedback linearization technique, a linear tracking error system is established with prescribed references. For the linear model, a robust controller is proposed based on the signal compensation theory to guarantee that the tracking error dynamics is robustly stable. Numerical simulation results are given to show the advantages of the proposed nonlinear robust control method, compared to the robust loop-shaping control approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Nonlinear interaction of charged particles with strong laser pulses in a gaseous media
Directory of Open Access Journals (Sweden)
H. K. Avetissian
2007-07-01
Full Text Available The charged particles nonlinear dynamics in the field of a strong electromagnetic wave pulse of finite duration and certain form of the envelope, in the refractive medium with a constant and variable refraction indexes, is investigated by means of numerical integration of the classical relativistic equations of motion. The particle energy dependence on the pulse intensity manifests the nonlinear threshold phenomenon of a particle reflection and capture by actual laser pulses in dielectric-gaseous media that takes place for a plane electromagnetic wave in the induced Cherenkov process. Laser acceleration of the particles in the result of the reflection from the pulse envelope and in the capture regime with the variable refraction index along the pulse propagation direction is investigated.
Directory of Open Access Journals (Sweden)
Eric Abraham Hurtado-Aviles
2017-10-01
Full Text Available A strong influence of mechanical action in nonlinear optical transmittance experiments with bimetallic nanoparticles integrated by gold and platinum was observed. The nanostructured samples were synthesized by a sol-gel method and contained in an ethanol suspension. UV-VIS spectroscopy evaluations, Transmission electron microscopy studies and input-output laser experiments were characterized. A two-photon absorption effect was induced by nanosecond pulses at 532 nm wavelength with an important contribution from the plasmonic response of the nanomaterials. All-optical identification of acoustical waves was remarkably improved by optical nonlinearities. High sensitivity for instrumentation of mechano-optical signals sensing particular fluids was demonstrated by using a variable carbon dioxide incorporation to the system.
DG-FEM solution for nonlinear wave-structure interaction using Boussinesq-type equations
DEFF Research Database (Denmark)
Engsig-Karup, Allan Peter; Hesthaven, Jan; Bingham, Harry B.
2008-01-01
equations in complex and curvilinear geometries which amends the application range of previous numerical models that have been based on structured Cartesian grids. The Boussinesq method provides the basis for the accurate description of fully nonlinear and dispersive water waves in both shallow and deep...... and absorbed in the interior of the computational domain using a flexible relaxation technique applied on the free surface variables....
The nonlinear interactions between O+ ions and oxygen band EMIC waves
Wang, Zhiqiang; Pan, Zhirui; Zhai, Hao; Gao, Zhuxiu; Sun, Kang; Zhang, Yusheng
2017-07-01
During geomagnetically active times, O+ ions from the ionosphere become an important ion component in the ring current, which changes the dispersion relations and significantly enlarges the growth rate of oxygen band electromagnetic ion cyclotron (EMIC) waves. Motivated by a large number of oxygen band EMIC wave observations in the inner magnetosphere, we study the nonlinear motions of ring current O+ ions caused by the cyclotron resonance with oxygen band EMIC waves. A dimensionless parameter R is used to characterize the competition between wave-induced and adiabatic motions. The numerical calculations based on gyroaveraged test particle equations are performed. For typical 20 keV O+ ions at L = 5, two kinds of nonlinear processes occur simultaneously when αeq > 59° (R loss cone and reduce the overall loss rate estimated from the quasi-linear theory. Instead, phase bunching tends to increase the overall loss rate. The phase-trapped O+ ions have chance to be accelerated drastically, reaching 750% of the initial energy. These O+ ions move forward and backward alternatively along the field lines when they are bouncing back to the equator, forming a periodic energy variation which has not been reported before. The results suggest that the oxygen band EMIC waves, which appear frequently during storms, should be considered in the ring current dynamics in terms of nonlinear acceleration and resonance scattering of ring current particles.
International Nuclear Information System (INIS)
Saikia, P.
1981-01-01
The spectrum of stimulated Brillouin scattering from an inhomogeneous moving laser plasma is analyzed. The damping of acoustic waves and scattered electromagnetic waves is taken into account. Spectra are derived for various scattering angles and for various radii of the laser beam. For all observation angles the center of the spectral line is at an unshifted frequency. As the observation angle increases, the width of the red wing in the spectrum increases. The intensity of the scattered light is very anisotropic
Experimental studies of X-UV rays by a laser plasma: X-UV strioscopy by means of multilayer mirrors
International Nuclear Information System (INIS)
Lutrin, F.
1996-01-01
This thesis studies a new instrument -from its conception to the measures interpretation- that analyses electronic density gradient in the super critical transportation area of a laser plasma (0,35 μm). This device, so-called of X-UV Schlieren, is based on the refraction property of a probe beam by an index gradient. Its specificity is the use of the X-UV emission at 13 nm (92 eV) of another laser plasma as X-UV probe. The conception and characterization of this instrument are defined thanks to both the emissivity and reflectivity properties of laser plasmas and the reflectivity properties of multilayers. Within this report are presented strioscopy images, spatially and spectrally resolved of an aluminium plasma from a 3.10 12 W/cm 2 laser flux, probed by a 13 nm wavelength. The device has to be closely aligned so as to obtain good contrast and good spatial resolution. For the first time, the refraction of a X-UV probe beam by a laser plasma is displayed. The experiments show that this refraction is all the more obvious for a gold probe plasma of energy 105 J and an aluminium probed plasma of energy 1 J. According to our plasma hydrodynamic simulation, the detected refraction corresponds to an electronic density gradient of 6,5.10 25 electrons/cm 4 in the two first microns of the sur-critical area. To study the parameters dependence of this gradient in the sur-critical area, several solutions for improving the instrument are produced. (author)
Energy Technology Data Exchange (ETDEWEB)
Batani, D.; Botto, C.; Moret, M.; Milani, M.; Lucchini, G. [Universita degli Studi di Milano-Bicocca and INFM, Milano (Italy); Eidmann, K. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Cotelli, F.; Lora Lamia Donin, C.; Poletti, G. [Universita di Milano (Italy); Ford, T.; Stead, A. [London Univ., Royal Holloway (United Kingdom)
2002-11-01
In this paper the results of an experiment on soft X-ray contact microscopy using a laser-plasma source are presented. A resolution of 50 nm has been achieved imaging pig sperm cells, while other specimens, such as algae and yeast cells, showed internal details, proving the technique to be a powerful tool for biological investigations. Original biological information has been obtained and the conditions for optimal image formation have been studied. (authors)
Nanoimaging using soft X-ray and EUV laser-plasma sources
Wachulak, Przemyslaw; Torrisi, Alfio; Ayele, Mesfin; Bartnik, Andrzej; Czwartos, Joanna; Węgrzyński, Łukasz; Fok, Tomasz; Fiedorowicz, Henryk
2018-01-01
In this work we present three experimental, compact desk-top imaging systems: SXR and EUV full field microscopes and the SXR contact microscope. The systems are based on laser-plasma EUV and SXR sources based on a double stream gas puff target. The EUV and SXR full field microscopes, operating at 13.8 nm and 2.88 nm wavelengths are capable of imaging nanostructures with a sub-50 nm spatial resolution and short (seconds) exposure times. The SXR contact microscope operates in the "water-window" spectral range and produces an imprint of the internal structure of the imaged sample in a thin layer of SXR sensitive photoresist. Applications of such desk-top EUV and SXR microscopes, mostly for biological samples (CT26 fibroblast cells and Keratinocytes) are also presented. Details about the sources, the microscopes as well as the imaging results for various objects will be presented and discussed. The development of such compact imaging systems may be important to the new research related to biological, material science and nanotechnology applications.
Electron bunch diagnostics for laser-plasma accelerators, from THz to X-rays
International Nuclear Information System (INIS)
Plateau, G.
2011-10-01
This thesis presents a series of single-shot non-intrusive diagnostics of key attributes of electron bunches produced by a laser-plasma accelerator (LPA). Three injection mechanisms of the LPA are characterized: channeled and self-guided self-injection, plasma down-ramp injection, and two-beam colliding pulse injection. New diagnostic techniques are successfully demonstrated: up to 8 times higher sensitivity wavefront sensor-based plasma density measurements, strong spatio-temporal coupling of the focused THz pulse is demonstrated using the temporal electric-field cross-correlation (TEX) of a long chirped probe with a short probe and confirms the two-component structure of the bunch observed by electron spectrometry, and normalized transverse emittances as low as 0.1 mm mrad are demonstrated for 0.5 GeV-class beams produced in a capillary-guided LPA by characterizing the betatron radiation emitted by the electrons inside the plasma using a new single-shot X-ray spectroscopy technique. (author)
Magnetic Field Measurement in Magnetized Laser Plasmas Using Zeeman Broadening Diagnostics
Haque, S.; Wallace, M. S.; Arias, A.; Morita, T.; Plechaty, C.; Huntington, C.; Martinez, D.; Ross, S. J.; Park, H.-S.; Presura, R.
2013-10-01
The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult when the field orientation is fluctuating in the plasma volume or when the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Based on an idea proposed by Tessarin et al. (2011), we implemented a solution to this problem to the field measurement in magnetized laser plasmas. High resolution spectra were obtained at the Nevada Terawatt Facility for plasmas created by 20 J, 400 fs Leopard laser pulses in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator. The components of the Al III 3s 2S1/2 - 3p 2P1 / 2 , 3 / 2 were recorded with space resolution along the direction normal to the target, which coincided with the magnetic field radius. In several shots, the spectra were time gated for 10 ns at different values of the magnetic field. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength can be measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.
Development of a Multi-GeV spectrometer for laser-plasma experiment at FLAME
International Nuclear Information System (INIS)
Valente, P.; Anelli, F.; Bacci, A.; Batani, D.; Bellaveglia, M.; Benocci, R.; Benedetti, C.; Cacciotti, L.; Cecchetti, C.A.; Clozza, A.; Cultrera, L.; Di Pirro, G.; Drenska, N.; Faccini, R.; Ferrario, M.; Filippetto, D.; Fioravanti, S.; Gallo, A.; Gamucci, A.; Gatti, G.
2011-01-01
The advance in laser-plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular, the upcoming experiments with the 250 TW laser at the FLAME facility of the INFN Laboratori Nazionali di Frascati, will enter the GeV regime with more than 100 pC of electrons. At the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need for developing a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV), with still unknown angular divergences. Within the PlasmonX experiment at FLAME, a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence, present challenges in the design and construction of such a device. We present the design considerations for this spectrometer that lead to the use of scintillating fibers, multichannel photo-multipliers and a multiplexing electronics, a combination which is innovative in the field. We also present the experimental results obtained with a high intensity electron beam performed on a prototype at the LNF beam test facility.
Development of a Multi-GeV spectrometer for laser-plasma experiment at FLAME
Valente, P.; Anelli, F.; Bacci, A.; Batani, D.; Bellaveglia, M.; Benocci, R.; Benedetti, C.; Cacciotti, L.; Cecchetti, C. A.; Clozza, A.; Cultrera, L.; Di Pirro, G.; Drenska, N.; Faccini, R.; Ferrario, M.; Filippetto, D.; Fioravanti, S.; Gallo, A.; Gamucci, A.; Gatti, G.; Ghigo, A.; Giulietti, A.; Giulietti, D.; Gizzi, L. A.; Koester, P.; Labate, L.; Levato, T.; Lollo, V.; Londrillo, P.; Martellotti, S.; Pace, E.; Pathak, N.; Rossi, A.; Tani, F.; Serafini, L.; Turchetti, G.; Vaccarezza, C.
2011-10-01
The advance in laser-plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular, the upcoming experiments with the 250 TW laser at the FLAME facility of the INFN Laboratori Nazionali di Frascati, will enter the GeV regime with more than 100 pC of electrons. At the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need for developing a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV), with still unknown angular divergences. Within the PlasmonX experiment at FLAME, a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence, present challenges in the design and construction of such a device. We present the design considerations for this spectrometer that lead to the use of scintillating fibers, multichannel photo-multipliers and a multiplexing electronics, a combination which is innovative in the field. We also present the experimental results obtained with a high intensity electron beam performed on a prototype at the LNF beam test facility.
International Nuclear Information System (INIS)
Yeates, P.; Kennedy, E. T.
2011-01-01
Generation and expansion dynamics of aluminum laser plasma plumes generated between parallel plates of varying separation (ΔZ = 2.0, 3.2, 4.0, and 5.6 mm), which confined plume expansion normal to the ablation surface, were diagnosed. Space and time resolved visible emission spectroscopy in the spectral range λ = 355-470 nm and time gated visible imaging were employed to record emission spectra and plume dynamics. Space and time resolved profiles of N e (the electron density), T e (the electron temperature), and T ionz (the ionization temperature) were compared for different positions in the plasma plume. Significant modifications of the profiles of the above parameters were observed for plasma-surface collisions at the inner surface of the front plate, which formed a barrier to the free expansion of the plasma plume generated by the laser light on the surface of the back plate. Shockwave generation at the collision interface resulted in delayed compression of the low-density plasma plume near the inner ablation surface, at late stages in the plasma history. Upon exiting the cavity formed by the two plates, through an aperture in the front plate, the plasma plume underwent a second phase of free expansion.
Nanoimaging using soft X-ray and EUV laser-plasma sources
Directory of Open Access Journals (Sweden)
Wachulak Przemyslaw
2018-01-01
Full Text Available In this work we present three experimental, compact desk-top imaging systems: SXR and EUV full field microscopes and the SXR contact microscope. The systems are based on laser-plasma EUV and SXR sources based on a double stream gas puff target. The EUV and SXR full field microscopes, operating at 13.8 nm and 2.88 nm wavelengths are capable of imaging nanostructures with a sub-50 nm spatial resolution and short (seconds exposure times. The SXR contact microscope operates in the “water-window” spectral range and produces an imprint of the internal structure of the imaged sample in a thin layer of SXR sensitive photoresist. Applications of such desk-top EUV and SXR microscopes, mostly for biological samples (CT26 fibroblast cells and Keratinocytes are also presented. Details about the sources, the microscopes as well as the imaging results for various objects will be presented and discussed. The development of such compact imaging systems may be important to the new research related to biological, material science and nanotechnology applications.
Analysis, modeling, and design of short-wavelength laser-plasma experiments
International Nuclear Information System (INIS)
Mead, W.C.; Coggeshall, S.V.; Goldman, S.R.; Stover, E.K.; Goldstone, P.D.; Hauer, A.; Kindel, J.M.; Montierth, L.
1985-01-01
We present analysis and LASNEX modeling of two experiments designed to explore the mechanisms and scaling of laser-plasma coupling in high-Z plasmas. The first used layered Au-on-CH spheres irradiated symmetrically using the Omega (Laboratory for Laser Energetics) 0.35 μm laser to observe the x-ray emission and energy penetration in gold plasmas. Measurements of the subkilovolt and kilovolt emission from targets with varying Au-coating thicknesses were made using diagnostics of varying spectral, temporal, and spatial resolution. The results indicate that the x-ray conversion efficiency is a function of target size, with larger targets yielding x-ray emission in excellent agreement with calculations. The x-ray emission fall-off with decreasing gold thickness agrees well with predictions. The second experiment used the Novette (Lawrence Livermore National Laboratory) laser to irradiate solid gold disk targets, examining wavelength scaling to 0.26 μm. The measured subkilovolt x-ray emission is in good agreement with calculations using mildly inhibited thermal electron transport, indicating enhanced target coupling, compared with previous experiments using smaller spot sizes. The experiment also indicates very low suprathermal electron populations, on the order of 0.1% at about 30 keV effective temperature. Finally, we present preliminary plans and designs for experiments which will use the Aurora 5 kJ, 5 ns, 0.25 μm KrF laser now being constructed at Los Alamos
Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV
Wang, Xiaoming; Zgadzaj, Rafal; Fazel, Neil; Li, Zhengyan; Yi, S. A.; Zhang, Xi; Henderson, Watson; Chang, Y.-Y.; Korzekwa, R.; Tsai, H.-E.; Pai, C.-H.; Quevedo, H.; Dyer, G.; Gaul, E.; Martinez, M.; Bernstein, A. C.; Borger, T.; Spinks, M.; Donovan, M.; Khudik, V.; Shvets, G.; Ditmire, T.; Downer, M. C.
2013-06-01
Laser-plasma accelerators of only a centimetre’s length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.
Laser-plasma EUV source dedicated for surface processing of polymers
Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Szczurek, M.; Wachulak, P. W.
2011-08-01
In this work, a 10 Hz laser-plasma extreme ultraviolet (EUV) source built for surface processing of polymers is presented. The source is based on a double-stream gas puff target created in a vacuum chamber synchronously with the pumping laser pulse. The target is formed by pulsed injection of Kr, Xe or a KrXe gas mixture into a hollow stream of helium. The EUV radiation is focused using a grazing incidence gold-plated ellipsoidal collector. Spectrum of the reflected radiation consists of a narrow feature with intensity maximum at 10-11 nm wavelength and a long-wavelength spectral tail up to 70 nm. The exact spectral distribution depends on a gas applied for plasma creation. To avoid strong absorption of the EUV radiation in a residual gas present in the chamber during the source operation a two step differential pumping system was employed. The system allows for polymer processing under relatively high vacuum conditions (10 -5 mbar) or in a reactive gas atmosphere. Polymer samples can be irradiated in a focal plane of the EUV collector or at some distance downstream the focal plane. This way fluence of the EUV beam at the polymer surface can be regulated.
Physical and chemical modifications of PET surface using a laser-plasma EUV source
Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Szczurek, M.; Biliński, A.; Chernyayeva, O.; Sobczak, J. W.
2010-06-01
Extreme ultraviolet (EUV) radiation is the electromagnetic radiation ranging from vacuum ultraviolet to soft X-rays. A single EUV photon carries enough energy to ionize any atom or molecule. The penetration depth of the radiation in any material is very short, ranging from tens to hundreds nanometers. Intense EUV pulses can remove material from the surface or modify its morphology or/and chemical structure. In this work, the radiation from a laser-plasma EUV source based on a double-stream gas-puff target was used for surface modification of polyethylene terephthalate (PET). The PET samples were irradiated with the EUV pulses emitted from krypton plasma and focused with a gold-plated ellipsoidal collector. The spectrum of the focused radiation covered the wavelength range from 9 to 70 nm. The PET samples were irradiated for 1 s-2 min at a 10-Hz repetition rate. Surface morphology of polymer samples after irradiation was investigated using a scanning electron microscope. Changes in chemical surface structure of the irradiated samples were investigated using an X-ray photoelectron spectroscopy. Different kinds of surface microstructures were obtained depending on the EUV fluence in a single pulse and the total EUV fluence. XPS measurements also revealed a modification of the chemical structure.
Brilliant GeV electron beam with narrow energy spread generated by a laser plasma accelerator
Directory of Open Access Journals (Sweden)
Ronghao Hu
2016-09-01
Full Text Available The production of GeV electron beam with narrow energy spread and high brightness is investigated using particle-in-cell simulations. A controlled electron injection scheme and a method for phase-space manipulation in a laser plasma accelerator are found to be essential. The injection is triggered by the evolution of two copropagating laser pulses near a sharp vacuum-plasma transition. The collection volume is well confined and the injected bunch is isolated in phase space. By tuning the parameters of the laser pulses, the parameters of the injected electron bunch, such as the bunch length, energy spread, emittance and charge, can be adjusted. Manipulating the phase-space rotation with the rephasing technique, the injected electron bunch can be accelerated to GeV level while keeping relative energy spread below 0.5% and transverse emittance below 1.0 μm. The results present a very promising way to drive coherent x-ray sources.
Bunch decompression for laser-plasma driven free-electron laser demonstration schemes
Directory of Open Access Journals (Sweden)
T. Seggebrock
2013-07-01
Full Text Available X-ray free-electron lasers (FELs require a very high electron beam quality in terms of emittance and energy spread. Since 2004 high quality electrons produced by laser-wakefield accelerators have been demonstrated, but the electron quality up to now did not allow the operation of a compact x-ray FEL using these electrons. Maier et al. [Phys. Rev. X 2, 031019 (2012PRXHAE2160-330810.1103/PhysRevX.2.031019] suggested a concept for a proof-of-principle experiment allowing FEL operation in the vacuum ultraviolet range based on an optimized undulator and bunch decompression using electron bunches from a laser-plasma accelerator as currently available. In this paper we discuss in more detail how a chicane can be used as a bunch stretcher instead of a bunch compressor to allow the operation of a laser-wakefield accelerator driven FEL using currently available electrons. A scaling characterizing the impact of bunch decompression on the gain length is derived and the feasibility of the concept is tested numerically in a demanding scenario.
X-ray Spectral Measurements of the JMAR High-Power Laser-plasma Source
Whitlock, Robert R.; Dozier, Charles M.; Newman, Daniel A.; Turcu, I. C. Edmond; Gaeta, Celestino J.; Cassidy, Kelly L.; Powers, Michael F.; Kleindolph, Thomas; Morris, James H.; Forber, Richard A.
2002-10-01
X-ray spectra of Cu plasmas at the focus of a four-beam, solid-state diode-pumped laser have been recorded. This laser-plasma X-ray source is being developed for JMAR's lithography systems aimed at high- performance semiconductor integrated circuits. The unique simultaneous overlay of the four sub-nanosecond laser beams at 300 Hertz produces a bright, point-plasma X-ray source. PIN diode measurements of the X-ray output indicate that the conversion efficiency (ratio of X-ray emission energy into 2π steradians to incident laser energy) was approximately 9 percent with average X-ray power yields of greater than 10 Watts. Spectra were recorded on calibrated Kodak DEF film in a curved-crystal spectrograph. A KAP crystal (2d = 26.6 Angstroms) was used to disperse the 900 eV to 3000 eV spectral energies onto the film. Preliminary examination of the films indicated the existence of Cu and Cu XX ionization states. Additional spectra as a function of laser input power were also recorded to investigate potential changes in X-ray yields. These films are currently being analyzed. The analysis of the spectra provide absolute line and continuum intensities, and total X-ray output in the measured spectral range.
Investigation of radiation characteristics of laser plasma on a surface of metal targets
Anikeev, Boris V.; Khaydukov, Evgeny V.; Khramov, Vladimir N.; Sevost'yanov, Andrey V.; Zatrudina, Rimma S.
2007-06-01
Results of numerical model operation of the x-ray radiation spectra and values of the magnetic field induction of the laser plasma received on aluminium and copper targets under action of USP are presented in this work. In calculations the mathematcial model including combined equations of ideal magnetohydrodynamics in vie of tranpsor ot laser radiation and a self-radiation of laser plasm, supplemented by equations of state and tabulared absorption constant was used. Calculations have shown the oscillation of the x-rays in a pectral rang 1-10 keV with intensity up to 10 11 W/cm2. It is revealed that the accoutn of a heating of plasma by the laser USP changes sharply the morphology of a powerful shock plams wave. Calucation has shown that near to a surface of a target there is an oscillation of spontaneous magnetic fields with an induction about 5•10 7 Gs. And medial value of a magnetic field induction on a copper target in 1. times is more than on an aluminium target. The electron concnetration in laser plams on a copper target, on the average, in 1.3 times is more than on an aluminium target. The velocity of a motion of front of laser plama is ovservationally estimaed at an optical breakdown in atmosphere which ahs made quantity about 7.5•10 6cm/s.
Nanostructured imaging of biological specimens in vivo with laser plasma X-ray contact microscopy
Energy Technology Data Exchange (ETDEWEB)
Cefalas, A.C.; Sarantopoulou, E.; Kollia, Z.; Argitis, P.; Tegou, E.; Ford, T.W.; Stead, A.D.; Danson, C.N.; Neely, D.; Kobe, S
2003-01-15
Soft X-ray contact microscopy (SXCM) enables the study of the ultrastructure of living hydrated specimens, without the need of dehydration or any other chemical pretreatment, by using suitable pulsed X-ray sources such as laser plasmas. The successful imaging of biological specimen requires the development of sensitive photoresist materials for image recording; these should have capabilities of high-resolution lithography and an extended grey scale. A very sensitive photoresist, used for the first time in SXCM, enabled the biological imaging with the specific source in single-pulse experiments in the water window spectral range. This photoresist is an epoxy novolac-based chemically amplified photoresist (EPR), which has been proven capable of resolving subtenth-micron features. The photoresist response was at least two orders of magnitude 'faster' than polymethyl methacrylate (PMMA), which is the standard resist used so far in SXCM. Atomic force microscopy (AFM) and scanning electron microscopy of the biological specimen images recorded in the resist clearly showed the flagella of the motile green alga, suggesting a lateral resolution better than 100 nm. The resist was also capable of providing height features, as small as 20 nm, in AFM depth profiles and discriminating the flagella intersection areas.
Pieronek, C. V.; Daniels, J.; Gonsalves, A. J.; Benedetti, C.; Leemans, W. P.
2017-10-01
To date, the most energetic electron beams from laser-plasma accelerators have been produced using gas-filled capillary discharge waveguides, which increase the acceleration length by mitigating diffraction of the driving laser pulse. To reach higher electron beam energies, lower plasma density is required to reduce bunch dephasing. However, confinement of the driver is reduced for lower plasma density, reducing the acceleration length. A laser-heated capillary discharge waveguide, where the discharge is heated by a coaxial laser pulse, was proposed to create a steeper density gradient at lower density. Here the first measurements of group velocity in laser-heated capillary discharges, obtained via spectral interferometry, are presented. Increase of the driver group velocity and reduction in on-axis plasma density by laser-heating are shown. Work supported by the U.S. Dept. of Energy, Office of Science, Office of High Energy Physics, under Contract No. DE-AC02-05CH11231. Additional support by the National Science Foundation under Grant PHY-1415596.
The physics of megajoule, large-scale, and ultrafast short-scale laser plasmas
International Nuclear Information System (INIS)
Campbell, E.M.
1992-01-01
Recent advances in laser science and technology have opened new possibilities for the study of high energy density plasma physics. The advances include techniques to control the laser spatial and temporal coherence, and the development of laser architectures and optical materials that have led to the demonstration of compact, short pulse (τ≤10 -12 sec) high brightness lasers, capable of irradiating plasmas with intensities ≥10 18 W/cm 2 . Experiments with reduced laser coherence have shown a substantial decrease in laser-driven parametric instabilities and have extended the parameter range where inverse bremsstrahlung absorption is the dominant coupling process. Beam smoothing with short wavelength lasers should result in inverse bremsstrahlung dominated coupling in the irradiance parameter regimes of the millimeter scale-length plasmas envisioned for the megajoule class lasers for ignition and gain in inertial fusion. In addition new regimes of laser--plasma coupling will become experimentally accessible when plasmas are irradiated with I≥10 18 W/cm 2 . Relativistic effects, extreme profile modification, and electrons heated to energies exceeding 1 MeV are several of the phenomena that are expected. Numerous applications in basic and applied plasma physics will result from these new capabilities
DNA strand breaks induced by soft X-ray pulses from a compact laser plasma source
Adjei, Daniel; Wiechec, Anna; Wachulak, Przemyslaw; Ayele, Mesfin Getachew; Lekki, Janusz; Kwiatek, Wojciech M.; Bartnik, Andrzej; Davídková, Marie; Vyšín, Luděk; Juha, Libor; Pina, Ladislav; Fiedorowicz, Henryk
2016-03-01
Application of a compact laser plasma source of soft X-rays in radiobiology studies is demonstrated. The source is based on a laser produced plasma as a result of irradiation of a double-stream gas puff target with nanosecond laser pulses from a commercially available Nd:YAG laser. The source allows irradiation of samples with soft X-ray pulses in the "water window" spectral range (wavelength: 2.3-4.4 nm; photon energy: 280-560 eV) in vacuum or a helium atmosphere at very high-dose rates and doses exceeding the kGy level. Single-strand breaks (SSB) and double-strand breaks (DBS) induced in DNA plasmids pBR322 and pUC19 have been measured. The different conformations of the plasmid DNA were separated by agarose gel electrophoresis. An exponential decrease in the supercoiled form with an increase in linear and relaxed forms of the plasmids has been observed as a function of increasing photon fluence. Significant difference between SSB and DSB in case of wet and dry samples was observed that is connected with the production of free radicals in the wet sample by soft X-ray photons and subsequent affecting the plasmid DNA. Therefore, the new source was validated to be useful for radiobiology experiments.
Directory of Open Access Journals (Sweden)
Djillali Amar Bouzid
2018-04-01
Full Text Available A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines (OWTs chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KR and cross-coupling stiffness KLR, of which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements (displacements and rotations, the values of KL, KR and KLR were obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness. Keywords: Nonlinear finite element analysis, Vertical slices model, Monopiles under horizontal loading, Natural frequency, Monopile head stiffness, Offshore wind turbines (OWTs
DEFF Research Database (Denmark)
Castaldi, P J; Demeo, D L; Hersh, C P
2010-01-01
with COPD. Using data from the Alpha-1 Antitrypsin Genetic Modifiers Study, the accuracy and power of two different approaches to model smoking were compared by performing a simulation study of a genetic variant with a range of gene-by-smoking interaction effects. Results Non-linear relationships between......Background The identification of gene-by-environment interactions is important for understanding the genetic basis of chronic obstructive pulmonary disease (COPD). Many COPD genetic association analyses assume a linear relationship between pack-years of smoking exposure and forced expiratory volume...... in 1 s (FEV(1)); however, this assumption has not been evaluated empirically in cohorts with a wide spectrum of COPD severity. Methods The relationship between FEV(1) and pack-years of smoking exposure was examined in four large cohorts assembled for the purpose of identifying genetic associations...
Hu, Kun; Peng, C. K.; Huang, Norden E.; Wu, Zhaohua; Lipsitz, Lewis A.; Cavallerano, Jerry; Novak, Vera
2008-04-01
Cerebral autoregulation is an important mechanism that involves dilatation and constriction in arterioles to maintain relatively stable cerebral blood flow in response to changes of systemic blood pressure. Traditional assessments of autoregulation focus on the changes of cerebral blood flow velocity in response to large blood pressure fluctuations induced by interventions. This approach is not feasible for patients with impaired autoregulation or cardiovascular regulation. Here we propose a newly developed technique-the multimodal pressure-flow (MMPF) analysis, which assesses autoregulation by quantifying nonlinear phase interactions between spontaneous oscillations in blood pressure and flow velocity during resting conditions. We show that cerebral autoregulation in healthy subjects can be characterized by specific phase shifts between spontaneous blood pressure and flow velocity oscillations, and the phase shifts are significantly reduced in diabetic subjects. Smaller phase shifts between oscillations in the two variables indicate more passive dependence of blood flow velocity on blood pressure, thus suggesting impaired cerebral autoregulation. Moreover, the reduction of the phase shifts in diabetes is observed not only in previously-recognized effective region of cerebral autoregulation (type 2 diabetes mellitus alters cerebral blood flow regulation over a wide frequency range and that this alteration can be reliably assessed from spontaneous oscillations in blood pressure and blood flow velocity during resting conditions. We also show that the MMPF method has better performance than traditional approaches based on Fourier transform, and is more suitable for the quantification of nonlinear phase interactions between nonstationary biological signals such as blood pressure and blood flow.
DEFF Research Database (Denmark)
Zhou, B. B.; Chong, A.; Wise, F. W.
2012-01-01
response with an octave-spanning bandwidth. We verify this experimentally by showing few-cycle soliton compression with noncritical cascaded second-harmonic generation: Energetic 47 fs infrared pulses are compressed in a just 1-mm long bulk lithium niobate crystal to 17 fs (under 4 optical cycles) with 80......% efficiency, and upon further propagation an octave-spanning supercontinuum is observed. Such ultrafast cascading is expected to occur for a broad range of pump wavelengths spanning the near- and mid-IR using standard nonlinear crystals....
Light-Matter Interaction Atoms and Molecules in External Fields and Nonlinear Optics
Hill, Wendell T
2006-01-01
This book draws together the principal ideas that form the basis of atomic, molecular, and optical science and engineering. It covers the basics of atoms, diatomic molecules, atoms and molecules in static and electromagnetic fields and nonlinear optics. Exercises and bibliographies supplement each chapter, while several appendices present such important background information as physics and math definitions, atomic and molecular data, and tensor algebra. Accessible to advanced undergraduates, graduate students, or researchers who have been trained in one of the conventional curricula of physic
International Nuclear Information System (INIS)
Zuo, Zhifeng; Maekawa, Hiroshi
2014-01-01
The interaction between a moderate-strength shock wave and a near-wall vortex is studied numerically by solving the two-dimensional, unsteady compressible Navier–Stokes equations using a weighted compact nonlinear scheme with a simple low-dissipation advection upstream splitting method for flux splitting. Our main purpose is to clarify the development of the flow field and the generation of sound waves resulting from the interaction. The effects of the vortex–wall distance on the sound generation associated with variations in the flow structures are also examined. The computational results show that three sound sources are involved in this problem: (i) a quadrupolar sound source due to the shock–vortex interaction; (ii) a dipolar sound source due to the vortex–wall interaction; and (iii) a dipolar sound source due to unsteady wall shear stress. The sound field is the combination of the sound waves produced by all three sound sources. In addition to the interaction of the incident shock with the vortex, a secondary shock–vortex interaction is caused by the reflection of the reflected shock (MR2) from the wall. The flow field is dominated by the primary and secondary shock–vortex interactions. The generation mechanism of the third sound, which is newly discovered, due to the MR2–vortex interaction is presented. The pressure variations generated by (ii) become significant with decreasing vortex–wall distance. The sound waves caused by (iii) are extremely weak compared with those caused by (i) and (ii) and are negligible in the computed sound field. (paper)
Nonlinear localized excitations in magnets with a weak exchange interaction as a soliton problem
International Nuclear Information System (INIS)
Gvozdikova, M.V.; Kovalev, A.S.
1998-01-01
The spin dynamics of soliton-like localized excitations in a discrete ferromagnet chain with an easy axis anisotropy and a weak exchange interaction is studied. The connection of these excitations with longwave magnetic solitons is discussed. The localized excitation frequency dependence on exchange interaction is found for a fixed number of spin deviation. It is shown that this dependence modifies essentially when the exchange interaction becomes comparable with an anisotropy value
Said-Houari, Belkacem
2012-09-01
The goal of this work is to study a model of the viscoelastic wave equation with nonlinear boundary/interior sources and a nonlinear interior damping. First, applying the Faedo-Galerkin approximations combined with the compactness method to obtain existence of regular global solutions to an auxiliary problem with globally Lipschitz source terms and with initial data in the potential well. It is important to emphasize that it is not possible to consider density arguments to pass from regular to weak solutions if one considers regular solutions of our problem where the source terms are locally Lipschitz functions. To overcome this difficulty, we use an approximation method involving truncated sources and adapting the ideas in [13] to show that the existence of weak solutions can still be obtained for our problem. Second, we show that under some restrictions on the initial data and if the interior source dominates the interior damping term, then the solution ceases to exist and blows up in finite time provided that the initial data are large enough.
Super-Gaussian transport theory and the field-generating thermal instability in laser-plasmas
Bissell, J. J.; Ridgers, C. P.; Kingham, R. J.
2013-02-01
Inverse bremsstrahlung (IB) heating is known to distort the electron distribution function in laser-plasmas from a Gaussian towards a super-Gaussian, thereby modifying the equations of classical transport theory (Ridgers et al 2008 Phys. Plasmas 15 092311). Here we explore these modified equations, demonstrating that super-Gaussian effects both suppress traditional transport processes, while simultaneously introducing new effects, such as isothermal (anomalous Nernst) magnetic field advection up gradients in the electron number density ne, which we associate with a novel heat-flow qn∝∇ne. Suppression of classical phenomena is shown to be most pronounced in the limit of low Hall-parameter χ, in which case the Nernst effect is reduced by a factor of five, the ∇Te × ∇ne field generation mechanism by ˜30% (where Te is the electron temperature), and the diffusive and Righi-Leduc heat-flows by ˜80 and ˜90% respectively. The new isothermal field advection phenomenon and associated density-gradient driven heat-flux qn are checked against kinetic simulation using the Vlasov-Fokker-Planck code impact, and interpreted in relation to the underlying super-Gaussian distribution through simplified kinetic analysis. Given such strong inhibition of transport at low χ, we consider the impact of IB on the seeding and evolution of magnetic fields (in otherwise un-magnetized conditions) by examining the well-known field-generating thermal instability in the light of super-Gaussian transport theory (Tidman and Shanny 1974 Phys. Fluids 12 1207). Estimates based on conditions in an inertial confinement fusion (ICF) hohlraum suggest that super-Gaussian effects can reduce the growth-rate of the instability by ≳80%. This result may be important for ICF experiments, since by increasing the strength of IB heating it would appear possible to inhibit the spontaneous generation of large magnetic fields.
The Sandia laser plasma extreme ultraviolet and soft x-ray (XUV) light source
International Nuclear Information System (INIS)
Tooman, T.P.
1986-01-01
Laser produced plasmas have been shown to be extremely bright sources of extreme ultraviolet and soft x-ray (XUV) radiation; however, certain practical difficulties have hindered the development of this source as a routinely usable laboratory device. To explore solutions to these difficulties, Sandia has constructed an XUV laser plasma source (LASPS) with the intention of developing an instrument that can be used for experiments requiring intense XUV radiation from 50-300 eV. The driving laser for this source is a KrF excimer with a wavelength of 248 nm, divergence of 200 μrad, pulse width of 23 ns at 20 Hz and typical pulse energy of 500 mJ which allows for good energy coupling to the plasma at moderate (10/sup 12/ W cm/sup 2/) power densities. This source has been pulsed approximately 2 x 10/sup 5/ times, demonstrating good tolerance to plasma debris. The source radiates from the visible to well above 1000 eV, however, to date attention has been concentrated on the 50-300 eV region. In this paper, spectral data and plasma images for both stainless steel and gold targets are presented with the gold target yielding a 200 μm plasma and reradiating 3.9% of the pump energy into 15-73 eV band, a flux of 1.22 x 10/sup 13/ photons/pulse/eV into 2π sr. Further efforts will expand these measurements to rare earth targets and to higher spectral energies. A special high throughput wide angle XUV (50-300 eV) monochromator and associated optics is being concurrently developed to collect the plasma radiation, perform energy dispersion and focus the radiation onto the experimental area
Combustion instability due to the nonlinear interaction between sound and flame
Wu, Xuesong; Wang, Meng; Moin, Parviz; Peters, Norbert
2003-12-01
It has been observed in experiments that significant levels of sound may be produced when a curved flame propagates downwards along a tube in a gravity field. In this paper, we present a mathematical description of this acoustic amplification process, which represents a simple form of combustion instability. First, based on the large-activation-energy and small-Mach-number assumptions, a general asymptotic formulation is derived, in which the nature of flame sound coupling is brought out explicitly. This framework is then employed to study the weakly nonlinear coupling between a Darrieus Landau (D-L) instability mode of the flame and an acoustic mode of the tube, which is the main mechanism for sound generation in the experiments. In order to provide a somewhat unified description, the linear coupling via the direct pressure effect has also been included in our analysis. A set of coupled equations which govern the evolution of the acoustic and D-L modes was derived. The solutions show that the nonlinear coupling leads to very rapid amplification of sound. After reaching an appreciable level, the sound inhibits the flame, causing the latter to flatten. The sound then saturates at an almost constant level, or continues to grow at a smaller rate owing to the pressure effect. The above theoretical predictions are in good qualitative agreement with experiments. The present study also considered the influence of weak vortical disturbances in the oncoming flow. It is shown that certain components in these perturbations may form resonant triads with the acoustic and D-L modes, thereby providing an additional coupling mechanism.
Czech Academy of Sciences Publication Activity Database
Kasperczuk, A.; Pisarczyk, T.; Nicolai, P.; Stenz, Ch.; Tikhonchuk, V.T.; Kálal, M.; Ullschmied, Jiří; Krouský, Eduard; Mašek, Karel; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří; Klír, D.; Kravárik, J.; Kubeš, P.; Pisarczyk, P.
2009-01-01
Roč. 27, č. 1 (2009), s. 115-122 ISSN 0263-0346 R&D Projects: GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z10100523 Keywords : Laser -plasma interaction * PALS laser * plasma jets * jet interaction with ambient * shock waves * laser interferometry Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.420, year: 2008
Research of Non-linear 2.5D Fluid-structure Interaction Model of Gravity Dam
Li, Yiran; Xu, Menghua; Sun, Hao
2017-10-01
Aseismic safety of dam involves people’s lives and properties, even has a great impact on national economic development. The key to this project is to have a fairly complete fluid-structure interaction (FSI) theory and a calculation method with a good accuracy. Therefore, focused on the FSI dynamic problem of gravity dam under seismic action, this paper presented the non-linear 2.5D dynamic theoretical model of concrete gravity dam established by segmenting fluid model and numerical solution method, compared the numerical simulation result under preliminary gravity action with 3D model. The study showed that the 2.5D dynamic calculation model could well reflect the seismic dynamic FSI behavior and effect of concrete gravity dam in the respects of displacement and stress and benefited the large-scale non-linear 3D aseismic calculation of gravity dam because of the effective reduction of 3D FSI numerical calculation time, which improved the calculation efficiency.
International Nuclear Information System (INIS)
Ovchinnikov, V. M.; Schumacher, D. W.; Kemp, G. E.; Krygier, A. G.; Van Woerkom, L. D.; Akli, K. U.; Freeman, R. R.; Stephens, R. B.; Link, A.
2011-01-01
We report the results of an experimental and numerical modeling study of the formation of time-integrated K α images by electrons excited during an intense laser-plasma interaction. We report the use of the spatial structure of time-integrated K α images to quantitatively characterize the pre-plasma profile near the critical surface and to verify the near elimination of back-surface refluxing from targets when a thick layer of a low-Z material is attached to the back. The time integrated K α images are found to be sensitive to the relative separation between the critical surface and the bulk target, permitting a single parameter exponential pre-plasma scale length to be determined by fitting to experimental results. The refluxed electrons affect different parts of the K α images in a manner that varies depending on the location of the refluxing. We use these properties to characterize refluxing also by fitting to experimental results. Experiments were performed using the Titan laser at the Lawrence Livermore National Laboratory and the simulations used a customized version of the hybrid-PIC code, LSP. We find good quantitative match between experiment and simulation.
Interaction of High Intensity Electromagnetic Waves with Plasmas: Final Report
International Nuclear Information System (INIS)
Shvets, G.
2008-01-01
The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.
International Nuclear Information System (INIS)
Wolf, J.P.; Darbre, G.R.
1985-01-01
The computational procedure of the so-called truncated indirect boundary-element method is derived. The latter, which is non-local in space and time, represents a rigorous generally applicable procedure for taking into account a layered halfspace in a non-linear soil-structure interaction analysis. As an example, the non-linear soil-structure interaction analysis of a structure embedded in a halfspace with partial uplift of the basement and separation of the side wall is investigated. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Chen, Shun-Li; Fu, Li; Chase, Zizwe A.; Gan, Wei; Wang, Hong-Fei
2016-11-10
Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group has been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.
Numerical simulation of nonlinear beam-plasma interaction for the application to solar radio burst
International Nuclear Information System (INIS)
Takakura, T.
1981-01-01
By the use of semi-analytical method the numerical simulations for the nonlinear scattering of axially symmetric plasma waves into plasma waves and radio waves have been made. The initial electron beam has a finite length and one-dimensional velocity distribution of power law. Induced back-scattering of plasma waves by thermal ions is strong even for a solar electron stream of rather low flux, say 2x10 11 cm -2 above 5 keV at fsub(p) of 40 MHz, which is enough to emit the observed type III bursts as the second harmonic. The ratio between the energy densities of plasma waves and thermal electrons (nkT) is of the order of 10 -6 , which may be a few orders lower than the threshold value for a caviton collapse of the plasma waves to occur. The second harmonic radio emission as attributed to the coalescence of two plasma waves, i.e. one excited by electron beam and one back-scattered by ions, is several orders higher than the fundamental radio emission caused by the scattering of plasma waves by thermal ions. (Auth.)
Lump solutions and interaction phenomenon to the third-order nonlinear evolution equation
Kofane, T. C.; Fokou, M.; Mohamadou, A.; Yomba, E.
2017-11-01
In this work, the lump solution and the kink solitary wave solution from the (2 + 1) -dimensional third-order evolution equation, using the Hirota bilinear method are obtained through symbolic computation with Maple. We have assumed that the lump solution is centered at the origin, when t = 0 . By considering a mixing positive quadratic function with exponential function, as well as a mixing positive quadratic function with hyperbolic cosine function, interaction solutions like lump-exponential and lump-hyperbolic cosine are presented. A completely non-elastic interaction between a lump and kink soliton is observed, showing that a lump solution can be swallowed by a kink soliton.
DEFF Research Database (Denmark)
Rasmussen, Kim; Christiansen, Peter Leth; Johansson, Magnus
1998-01-01
, s(cr), there is an interval of bistability where two stable stationary states exist at each excitation number. The bistability of on-site solitons may occur for dipole-dipole dispersive interaction (s = 3), while s(cr) for inter-sire solitons is close to 2.1. In the framework of the DNLS equation...
Palilonis, Jennifer; Butler, Darrell; Leidig-Farmen, Pamela
2013-01-01
As online teaching techniques continue to evolve, new opportunities surface for research and insight regarding best practices for the development and implementation of interactive, multimedia teaching and learning tools. These tools are particularly attractive for courses that lend themselves to a rich media approach. Such is the case for visual…
DEFF Research Database (Denmark)
Ganji, S. S.; Barari, Amin; Sfahani, M. G.
2011-01-01
The phenomenon of stream–aquifer interaction was investigated via mathematical modeling using the Boussinesq equation. A new approximate solution of the one-dimensional Boussinesq equation is presented for a semi-infinite aquifer when the hydraulic head at the source is an arbitrary function of t...
Tsai, Hai-En; Swanson, Kelly K.; Lehe, Remi; Barber, Sam K.; Isono, Fumika; Otero, Jorge G.; Liu, Xinyao; Mao, Hann-Shin; Steinke, Sven; Tilborg, Jeroen Van; Geddes, Cameron G. R.; Leemans, Wim
2017-10-01
High-level control of a laser-plasma accelerator (LPA) using a shock injector was demonstrated by systematically varying the shock injector profile, including the shock angle, up-ramp width and shock position. Particle-in-cell (PIC) simulation explored how variations in the shock profile impacted the injection process and confirmed results obtained through acceleration experiments. These results establish that, by adjusting shock position, up-ramp, and angle, beam energy, energy spread, and pointing can be controlled. As a result, e-beam were highly tunable from 25 to 300 MeV with Administration, Defense Nuclear Nonproliferation R&D (NA22).
Higher order structure analysis of nano-materials by spectral reflectance of laser-plasma soft x-ray
International Nuclear Information System (INIS)
Azuma, Hirozumi; Takeichi, Akihiro; Noda, Shoji
1995-01-01
We have proposed a new experimental arrangement to measure spectral reflectance of nano-materials for analyzing higher order structure with laser-plasma soft x-rays. Structure modification of annealed Mo/Si multilayers and a nylon-6/clay hybrid with poor periodicity was investigated. The measurement of the spectral reflectance of soft x-rays from laser-produced plasma was found to be a useful method for the structure analysis of nano-materials, especially those of rather poor periodicity
International Nuclear Information System (INIS)
Bolton, Paul R.; Tatchyn, Roman; Fukuda, Yuji; Kando, Masaki; Daito, Izuru; Ma, Jinglong; Chen, Liming; Pirozhkov, Alexander; Tajima, Toshiki
2007-01-01
Development of new diagnostics is critical for future laser-plasma accelerators, laser-driven light sources and for x-ray FELs. Recent laser wakefield electron acceleration developments and novel beam-based light source schemes (such as free electron lasers) obviate the need for next generation ultrafast diagnostics, capable of temporal resolution of a few femtoseconds (and in some cases attoseconds) for laser pulses (high order harmonics), x-ray pulses and electron bunches. Single shot detection capability in noninvasive and parasitic modes is also important. Alterations of laser pulse spectra and the associated dynamics can be informative diagnostics. The portion of a high intensity laser pulse that is transmitted through a self-induced underdense plasma (such as in laser wakefield acceleration LWFA schemes) carries the effects of plasma processes it has experienced. A distinction between the self-modulated laser wakefield (SMLWF) acceleration regime and the forced laser wakefield (FLWF) acceleration regime is in the spectral signature of the transmitted ir laser pulse. The former regime generates sidebands from stimulated Raman forward scattering (SRS-F) and the latter exhibits general spectral broadening that evidences ir laser pulse compression. Transmitted spectral effects can diagnose these acceleration regimes. Existing noninvasive electro-optic (EO) schemes for detection of ultrashort electron bunches are limited by material properties to temporal resolution at the 50-100 femtosecond level. While timing jitter at conventional accelerators is of this order (or greater), single bunch longitudinal profile measurements can require improvement of at least an order of magnitude. A new FO technique is described here which monitors enhancement and associated dynamics of spectral components in a probe pulse. Three correlation schemes for detecting ultrashort x-ray pulses are described. Two-photon absorption in tailored ion targets is proposed for scanning auto
Application of the CIP Method to Strongly Nonlinear Wave-Body Interaction Problems
Zhu, Xinying
2006-01-01
Water entry and exit, green water on deck, sloshing in tanks and capsizing in intact and damaged conditions are examples on violent fluid motion. The combination of model tests, theoretical analysis and Computational Fluid Dynamics (CFD) methods is emphasized in treating these problems. Because mixing of air and liquid may occur, the interaction between the flow in the air and in the liquid ought to be considered in numerical simulations. Further, the mixing of air and liquid represents a sca...
On the starting process of strongly nonlinear vortex/Rayleigh-wave interactions
BROWN, P. G.; BROWN, S. N.; SMITH, F. T.; TIMOSHIN, S. N.
1993-01-01
An oncoming two-dimensional laminar boundary layer that develops an unstable inflection point and becomes three-dimensional is described by the Hall-Smith (1991) vortex/wave interaction equations. These equations are now examined in the neighbourhood of the position where the critical surface starts to form. A consistent structure is established in which an inviscid core flow is matched to a viscous buffer-layer solution where the appropriate jump condition on the transverse shear stress is s...
Directory of Open Access Journals (Sweden)
Xiaozhong Ren
2015-01-01
Full Text Available A three-dimensional numerical flume is developed to study cnoidal wave interaction with multiple arranged perforated quasi-ellipse caissons. The continuity equation and the Navier-Stokes equations are used as the governing equation, and the VOF method is adopted to capture the free surface elevation. The equations are discretized on staggered cells and then solved using a finite difference method. The generation and propagation of cnoidal waves in the numerical flume are tested first. And the ability of the present model to simulate interactions between waves and structures is verified by known experimental results. Then cnoidal waves with varying incident wave height and period are generated and interact with multiple quasi-ellipse caissons with and without perforation. It is found that the perforation plays an effective role in reducing wave runup/rundown and wave forces on the caissons. The wave forces on caissons reduce with the decreasing incident wave period. The influence of the transverse distance of multiple caissons on wave forces is also investigated. A closer transverse distance between caissons can produce larger wave forces. But when relative adjacent distance L/D (L is the transverse distance and D is the width of the quasi-ellipse caisson is larger than 3, the effect of adjacent distance is limited.
Nonlinear charge and energy dynamics of an adiabatically driven interacting quantum dot
Romero, Javier I.; Roura-Bas, Pablo; Aligia, Armando A.; Arrachea, Liliana
2017-06-01
We formulate a general theory to study the time-dependent charge and energy transport of an adiabatically driven interacting quantum dot in contact with a reservoir for arbitrary amplitudes of the driving potential. We study within this framework the Anderson impurity model with a local ac gate voltage. We show that the exact adiabatic quantum dynamics of this system is fully determined by the behavior of the charge susceptibility of the frozen problem. At T =0 , we evaluate the dynamic response functions with the numerical renormalization group (NRG). The time-resolved heat production exhibits a pronounced feature described by an instantaneous Joule law characterized by a universal Büttiker resistance quantum R0=h /(2 e2) for each spin channel. We show that this law holds in the noninteracting as well as in the interacting system and also when the system is spin polarized. In addition, in the presence of a static magnetic field, the interplay between many-body interactions and spin polarization leads to a nontrivial energy exchange between electrons with different spin components.
Energy Technology Data Exchange (ETDEWEB)
Varma, Amit H. [Stanex, LLC, West Lafeyette, IN (United States); Seo, Jungil [Stanex, LLC, West Lafeyette, IN (United States); Coleman, Justin Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-11-01
Seismic probabilistic risk assessment (SPRA) methods and approaches at nuclear power plants (NPP) were first developed in the 1970s and aspects of them have matured over time as they were applied and incrementally improved. SPRA provides information on risk and risk insights and allows for some accounting for uncertainty and variability. As a result, SPRA is now used as an important basis for risk-informed decision making for both new and operating NPPs in the US and in an increasing number of countries globally. SPRAs are intended to provide best estimates of the various combinations of structural and equipment failures that can lead to a seismic induced core damage event. However, in some instances the current SPRA approach contains large uncertainties, and potentially masks other important events (for instance, it was not the seismic motions that caused the Fukushima core melt events, but the tsunami ingress into the facility). INL has an advanced SPRA research and development (R&D) activity that will identify areas in the calculation process that contain significant uncertainties. One current area of focus is the use of nonlinear soil-structure interaction (NLSSI) analysis methods to accurately capture: 1) nonlinear soil behavior and 2) gapping and sliding between the NPP and soil. The goal of this study is to compare numerical NLSSI analysis results with recorded earthquake ground motions at Fukushima Daichii (Great Tohuku Earthquake) and evaluate the sources of nonlinearity contributing to the observed reduction in peak acceleration. Comparisons are made using recorded data in the free-field (soil column with no structural influence) and recorded data on the NPP basemat (in-structure response). Results presented in this study should identify areas of focus for future R&D activities with the goal of minimizing uncertainty in SPRA calculations. This is not a validation activity since there are too many sources of uncertainty that a numerical analysis would need
Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong
2015-01-01
This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.
El Sayed, K.; Birkedal, D.; Lyssenko, V. G.; Hvam, J. M.
1997-01-01
We present a theoretical investigation of ultrafast transient four-wave mixing (FWM) of GaAs quantum wells for coherent excitation of excitons and a large number of continuum states. It is shown that in this case the line shape of the FWM signal is drastically altered due to an interaction-induced coupling of the exciton to all the excited continuum states. The signal is dominantly emitted at the spectral position of the exciton and decays, as a function of delay, on a time scale set by the duration of the laser pulse rather than by the intrinsic dephasing time. Nevertheless, the spectral width of the exciton line in the FWM spectrum and in the decay of the time-resolved FWM signal in real time are governed by the intrinsic excitonic dephasing rate. It is shown that for pulse durations of ~ 100 fs (for GaAs quantum wells) this behavior can be explained as the influence of the Coulomb exchange interaction, while for even shorter pulses this behavior is dominantly caused by nonlinear polarization decay.
Zhang, Yali; Wang, Jun
2017-09-01
In an attempt to investigate the nonlinear complex evolution of financial dynamics, a new financial price model - the multitype range-intensity contact (MRIC) financial model, is developed based on the multitype range-intensity interacting contact system, in which the interaction and transmission of different types of investment attitudes in a stock market are simulated by viruses spreading. Two new random visibility graph (VG) based analyses and Lempel-Ziv complexity (LZC) are applied to study the complex behaviors of return time series and the corresponding random sorted series. The VG method is the complex network theory, and the LZC is a non-parametric measure of complexity reflecting the rate of new pattern generation of a series. In this work, the real stock market indices are considered to be comparatively studied with the simulation data of the proposed model. Further, the numerical empirical study shows the similar complexity behaviors between the model and the real markets, the research confirms that the financial model is reasonable to some extent.
Two-dimensional Heisenberg model with nonlinear interactions: 1/N corrections
International Nuclear Information System (INIS)
Caracciolo, Sergio; Mognetti, Bortolo Matteo; Pelissetto, Andrea
2005-01-01
We investigate a two-dimensional classical N-vector model with a generic nearest-neighbor interaction W(σi-bar σj) in the large-N limit, focusing on the finite-temperature transition point at which energy-energy correlations become critical. We show that this transition belongs to the Ising universality class. However, the width of the region in which Ising behavior is observed scales as 1/N3/2 along the magnetic direction and as 1/N in the thermal direction; outside a crossover to mean-field behavior occurs. This explains why only mean-field behavior is observed for N=∼
Bartnik, Andrzej; Wachulak, Przemysław; Jarocki, Roman; Kostecki, Jerzy; Szczurek, Mirosław; Adjei, Daniel; Ahad, Inam Ul; Ayele, Mesfin G.; Fok, Tomasz; Szczurek, Anna; Torrisi, Alfio; Wegrzyński, Łukasz; Fiedorowicz, Henryk
2015-05-01
Laser plasma sources of soft x-rays and extreme ultraviolet (EUV) developed in our laboratory for application in various areas of technology and science are presented. The sources are based on a laser-irradiated gas puff target approach. The targets formed by pulsed injection of gas under high-pressure are irradiated with nanosecond laser pulses from Nd:YAG lasers. We use commercial lasers generating pulses with time duration from 1ns to 10ns and energies from 0.5J to 10J at 10Hz repetition rate. The gas puff targets are produced using a double valve system equipped with a special nozzle to form a double-stream gas puff target which secures high conversion efficiency without degradation of the nozzle. The use of a gas puff target instead of a solid target makes generation of laser plasmas emitting soft x-rays and EUV possible without target debris production. The sources are equipped with various optical systems, including grazing incidence axisymmetric ellipsoidal mirrors, a "lobster eye" type grazing incidence multi-foil mirror, and an ellipsoidal mirror with Mo/Si multilayer coating, to collect soft x-ray and EUV radiation and form the radiation beams. In this paper new applications of these sources in various fields, including soft x-ray and EUV imaging in nanoscale, EUV radiography and tomography, EUV materials processing and modification of polymer surfaces, EUV photoionization of gases, radiobiology and soft x-ray contact microscopy are reviewed.
International Nuclear Information System (INIS)
Birnbaum, N.K.; Cowler, M.S.; Itoh, M.; Katayama, M.; Obata, H.
1987-01-01
AUTODYN uses a two dimensional coupled finite difference approach similar to the one described by Cowler and Hancock (1979). Both translational and axial symmetry are treated. The scheme allows alternative numerical processors to be selectively used to model different components/regions of a problem. Finite difference grids operated on by these processors can be coupled together in space and time to efficiently compute structural (or fluid-structure) interactions. AUTODYN currently includes a Lagrange processor for modeling solid continua and structures, an Euler processor for modeling fluids and the large distortion of solids, an ALE (Arbitrary Lagrange Euler) processor for specialized flow models and a shell processor for modeling thin structures. At present, all four processors use explicit time integration but implicit options will be added to the Lagrange and ALE processors in the near future. Material models are included for solids, liquids and gases (including HE detonation products). (orig.)
Nonlinear dynamics of emotion-cognition interaction: when emotion does not destroy cognition?
Afraimovich, Valentin; Young, Todd; Muezzinoglu, Mehmet K; Rabinovich, Mikhail I
2011-02-01
Emotion (i.e., spontaneous motivation and subsequent implementation of a behavior) and cognition (i.e., problem solving by information processing) are essential to how we, as humans, respond to changes in our environment. Recent studies in cognitive science suggest that emotion and cognition are subserved by different, although heavily integrated, neural systems. Understanding the time-varying relationship of emotion and cognition is a challenging goal with important implications for neuroscience. We formulate here the dynamical model of emotion-cognition interaction that is based on the following principles: (1) the temporal evolution of cognitive and emotion modes are captured by the incoming stimuli and competition within and among themselves (competition principle); (2) metastable states exist in the unified emotion-cognition phase space; and (3) the brain processes information with robust and reproducible transients through the sequence of metastable states. Such a model can take advantage of the often ignored temporal structure of the emotion-cognition interaction to provide a robust and generalizable method for understanding the relationship between brain activation and complex human behavior. The mathematical image of the robust and reproducible transient dynamics is a Stable Heteroclinic Sequence (SHS), and the Stable Heteroclinic Channels (SHCs). These have been hypothesized to be possible mechanisms that lead to the sequential transient behavior observed in networks. We investigate the modularity of SHCs, i.e., given a SHS and a SHC that is supported in one part of a network, we study conditions under which the SHC pertaining to the cognition will continue to function in the presence of interfering activity with other parts of the network, i.e., emotion.
Non-linear and stimulated effects in laser-free electrons interaction
International Nuclear Information System (INIS)
Kupersztych, Joseph.
1977-11-01
A new method of calculating interaction processes between free particles and the strong field of an arbitrary plane electromagnetic wave is presented. To construct the method, the electron behavior is examined by investigating the most general space-time symmetry properties of the field. The classical evolution operator is shown to describe both the evolution of the electron and the evolution of its spin in the external field. The quantum evolution operator allows one to define a representation well adapted to the calculation of scattering processes that occur in a laser beam. The nonrelativistic and ultra-relativistic limits of that representation are obtained by means of two unitary transformations which enable the Volkov states to be put exactly in two-component forms. The physical meaning of those transformations is shown to be connected to the motion of the electron spin (rigorously described by the Bargmann-Michel-Telegdi equation) and to the motion of its helicity in the wave. The method is used to calculate completely the relativistic cross-sections of the stimulated Bremsstrahlung and multiphoton inverse Bremsstrahlung processes. This last process is also investigated numerically and a saturation effect at high flux is exhibited [fr
Dietrich, David E.; Mehra, Avichal; Haney, Robert L.; Bowman, Malcolm J.; Tseng, Yu-Heng
2003-01-01
Gulf Stream (GS) separation near its observed Cape Hatteras (CH) separation location, and its ensuing path and dynamics, is a challenging ocean modeling problem. If a model GS separates much farther north than CH, then northward GS meanders, which pinch off warm core eddies (rings), are not possible or are strongly constrained by the Grand Banks shelfbreak. Cold core rings pinch off the southward GS meanders. The rings are often re-absorbed by the GS. The important warm core rings enhance heat exchange and, especially, affect the northern GS branch after GS bifurcation near the New England Seamount Chain. This northern branch gains heat by contact with the southern branch water upstream of bifurcation, and warms the Arctic Ocean and northern seas, thus playing a major role in ice dynamics, thermohaline circulation and possible global climate warming. These rings transport heat northward between the separated GS and shelf slope/Deep Western Boundary Current system (DWBC). This region has nearly level time mean isopycnals. The eddy heat transport convergence/divergence enhances the shelfbreak and GS front intensities and thus also increases watermass transformation. The fronts are maintained by warm advection by the Florida Current and cool advection by the DWBC. Thus, the GS interaction with the DWBC through the intermediate eddy field is climatologically important.
Directory of Open Access Journals (Sweden)
N. A. Veretenov
2014-09-01
Full Text Available The paper deals with generalization of investigation materials performed by the authors in recent years and analysis of obtained results. The subject of the paper is accounting of many-particle interactions in molecular J-aggregates at their resonance excitation by laser radiation. In this case, not only twin interactions are taken into considerations, but also the interactions of a given particle with three and more particles simultaneously. Three basic directions can be denoted among carried out investigations. The first direction is connected with derivation (from the first principles of motion equations for molecular of J-aggregates in view of many-particle interactions, and also twin correlations between particles. The derivation of equations from the first principles leads in general to the system of coupled equations for the means of products of n operators relating to n different molecules. Since n increases in every following equation, the problems arise, connected with uncoupling of this system and also factorization of the means with the highest n. The most difficult and complicated problem in this process is correct calculation of relaxed terms, arising due to exciton-exciton annihilation. The first direction is connected concretely with solution of all above mentioned problems. Within the second direction the study of bistability has been carried out on the basis of obtained equations, in view of three-particle interactions. Meanwhile primary attention has been concentrated on analysis of homogeneous regimes in J-aggregates. It has been shown, in particular, that accounting of many-particle contributions leads to the shift of bistability boundary into region of smaller constants of exciton-exciton annihilation. And, at last, the third direction of investigations is connected with analysis of modulation instability for stationary states of J-aggregates considered earlier at bistability study. The study of stability region boundaries
Laser Plasmas: Lie-optic matrix algorithm for computer simulation of ...
Indian Academy of Sciences (India)
Propagation algorithm for computer simulation of stationary paraxial self-focusing laser beam in a medium with saturating nonlinearity is given in Lie-optic form. Accordingly, a very natural piece-wise continuous Lie transformation that reduces to a restricted Lorentz group of the beam results. It gives rise to a matrix method ...
Kumar, Santosh; Raychowdhury, Prishati; Gundlapalli, Prabhakar
2015-06-01
Design of critical facilities such as nuclear power plant requires an accurate and precise evaluation of seismic demands, as any failure of these facilities poses immense threat to the community. Design complexity of these structures reinforces the necessity of a robust 3D modeling and analysis of the structure and the soil-foundation interface. Moreover, it is important to consider the multiple components of ground motion during time history analysis for a realistic simulation. Present study is focused on investigating the seismic response of a nuclear containment structure considering nonlinear Winkler-based approach to model the soil-foundation interface using a distributed array of inelastic springs, dashpots and gap elements. It is observed from this study that the natural period of the structure increases about 10 %, whereas the force demands decreases up to 24 % by considering the soil-structure interaction. Further, it is observed that foundation deformations, such as rotation and sliding are affected by the embedment ratio, indicating an increase of up to 56 % in these responses for a reduction of embedment from 0.5 to 0.05× the width of the footing.
Yamanaka, Tsuyuko; Raffaelli, David; White, Piran C L
2013-01-01
Sea-level rise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Accelerated sea-level rise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-level rise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-level rise will also be affected by local ecological context, especially for less sloping beaches.
International Nuclear Information System (INIS)
Berthollet, A.
2003-10-01
Concrete structures are examined during their lifetime and often present important cracking states, which can progress with time and lead to change the structural behavior. The civil engineering works that the main function corresponds to protection's wall are very sensitive to this damage and its evolution. The growth of the time - dependent cracks represents an aging pathology linked with interaction between creep mechanism and the non-linear behavior of the material. In this thesis, a modeling for these mechanisms and their coupling are proposed. It based on creep strains analysis under different load levels, on the influence of the rate effect to the mechanical behavior. A stress limit is put on prominent manner, where beyond it, the creep - cracking interaction becomes important with the introduction of the ultimate tertiary creep kinetic. This level of strength is identified for infinitely slow loading rates and is also called intrinsic strength. It defines the limit on this side the viscous behavior of the cement paste limits the irreversibility processes as cracking. Thus, a constitutive law of viscoelastic - viscoplastic behavior with a high coupling between the cracking mechanism and the creep strains is proposed. The developments of the model are built on DUVAUT - LIONS approach integrated a generalized MAXWELL chain model. For one part, the viscoelastic behavior translates the creep mechanism under low stresses. For a second part, it associated with the viscoplastic behavior, which allows introducing both creep effect under high stresses and rate effect acting on micro-cracked zones. The cracking mechanism is described throughout a plasticity theory with multi-criteria, which induce a property of anisotropy for hardening. Qualitatively, ails of the creep kinetics are reproduced. An additional validation is based on experimental tests in compression, traction and flexion where the main parameters of the modeling are detailed. Thus, we can conclude on the
International Nuclear Information System (INIS)
Liu, Rong-Xiang; Tian, Bo; Liu, Li-Cai; Qin, Bo; Lü, Xing
2013-01-01
In this paper we investigate a fourth-order dispersive nonlinear Schrödinger equation, which governs the dynamics of a one-dimensional anisotropic Heisenberg ferromagnetic spin chain with the octuple–dipole interaction in condensed-matter physics as well as the alpha helical proteins with higher-order excitations and interactions in biophysics. Beyond the existing constraint, upon the introduction of an auxiliary function, bilinear forms and N-soliton solutions are constructed with the Hirota method. Asymptotic analysis on the two-soliton solutions indicates that the soliton interactions are elastic. Soliton velocity varies linearly with the coefficient of discreteness and higher-order magnetic interactions. Bound-state solitons can also exist under certain conditions. Period of a bound-state soliton is inversely correlated to the coefficient of discreteness and higher-order magnetic interactions. Interactions among the three solitons are all pairwise elastic
Czech Academy of Sciences Publication Activity Database
Wachulak, P.W.; Bartnik, A.; Fiedorowicz, H.; Feigl, T.; Jarocki, R.; Kostecki, J.; Rudawski, P.; Sawicka, Magdalena; Szczurek, M.; Szczurek, A.; Zawadzki, Z.
2010-01-01
Roč. 100, č. 3 (2010), 461-469 ISSN 0946-2171 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser-plasma * EUV source * gas puff target * elliptical multi- layer * mirror * table-top setup Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.239, year: 2010
Control of electron beam by using high-Z gas target in the laser-plasma acceleration
International Nuclear Information System (INIS)
Mori, Michiaki
2012-01-01
We investigate the pointing stability and the divergence of a quasi-monoenergetic electron beam generated in a self-injected laser-plasma acceleration regime using high-Z gas-jet target. Gas-jet targets have been irradiated with focused 40 fs laser pulses at the 4-TW peak power. A pointing stability and a beam divergence of electron beam were improved using argon target. These values were about three times smaller than at the optimum condition using helium. This stabilization method is available for another gas material such as nitrogen. At nitrogen gas-jet target, the pointing stability is more improved to two times smaller than that in argon gas-jet target and the peak energy is increased to >30 MeV. These results prove that this method not only stabilizes the e-beam but also allows controlling the electron energy. (author)
Directory of Open Access Journals (Sweden)
E. Çelebi
2012-11-01
Full Text Available The objective of this paper focuses primarily on the numerical approach based on two-dimensional (2-D finite element method for analysis of the seismic response of infinite soil-structure interaction (SSI system. This study is performed by a series of different scenarios that involved comprehensive parametric analyses including the effects of realistic material properties of the underlying soil on the structural response quantities. Viscous artificial boundaries, simulating the process of wave transmission along the truncated interface of the semi-infinite space, are adopted in the non-linear finite element formulation in the time domain along with Newmark's integration. The slenderness ratio of the superstructure and the local soil conditions as well as the characteristics of input excitations are important parameters for the numerical simulation in this research. The mechanical behavior of the underlying soil medium considered in this prediction model is simulated by an undrained elasto-plastic Mohr-Coulomb model under plane-strain conditions. To emphasize the important findings of this type of problems to civil engineers, systematic calculations with different controlling parameters are accomplished to evaluate directly the structural response of the vibrating soil-structure system. When the underlying soil becomes stiffer, the frequency content of the seismic motion has a major role in altering the seismic response. The sudden increase of the dynamic response is more pronounced for resonance case, when the frequency content of the seismic ground motion is close to that of the SSI system. The SSI effects under different seismic inputs are different for all considered soil conditions and structural types.
Li, Min; Xu, Tao
2015-03-01
Via the Nth Darboux transformation, a chain of nonsingular localized-wave solutions is derived for a nonlocal nonlinear Schrödinger equation with the self-induced parity-time (PT) -symmetric potential. It is found that the Nth iterated solution in general exhibits a variety of elastic interactions among 2N solitons on a continuous-wave background and each interacting soliton could be the dark or antidark type. The interactions with an arbitrary odd number of solitons can also be obtained under different degenerate conditions. With N=1 and 2, the two-soliton and four-soliton interactions and their various degenerate cases are discussed in the asymptotic analysis. Numerical simulations are performed to support the analytical results, and the stability analysis indicates that the PT-symmetry breaking can also destroy the stability of the soliton interactions.
Gopal, S. Veena; Chitrambalam, S.; Joe, I. Hubert
2018-01-01
Third-order nonlinear response of synthesized polyethylene glycol coated Fe3O4 nanoparticles dispersed in a suitable solvent, polyethylene glycol has been studied. The structural characterization of the synthesized magnetite nanoparticles were carried out. The linear optical property of the synthesized magnetite nanoparticles was investigated using UV-visible technique. Both closed and open aperture Z-scan techniques have been performed at 532 nm with pulse width 5 ns and repetition rate 10 Hz. It was found that polyethylene glycol coated magnetite exhibits reverse saturable absorption, with significant nonlinear absorption coefficient. Two-photon absorption intensity dependent positive nonlinear refraction coefficients indicate self focusing phenomena. Results show that higher concentration gives better nonlinear and optical limiting properties.
International Nuclear Information System (INIS)
Mizuno, J.; Namba, H.; Komura, T.; Tuchiya, Y.; Saitoh, M.
1993-01-01
Effects of uncertainties in materials and modeling on seismic responses of nuclear reactor buildings are relatively small if responses remain in the elastic range of structures. However, under extremely severe earthquakes, responses are expected to go into nonlinear ranges, and responses may exhibit wider scatters due to the uncertainties and variabilities in materials and nonlinear characteristics of shear walls. Thus, it may be quite important to evaluate the effects of the uncertainties on nonlinear responses, especially, the maximum shear strain response, which is one of the most critical responses to the seismic safety of reinforced concrete shear walls and to reactor buildings as a whole. To this end, the sensitivities of nonlinear responses, mainly shear strain responses, to the uncertainties and variabilities of materials and nonlinear characteristics of shear walls arc evaluated for a reactor building of BWR Mark I type; then, the variabilities of nonlinear responses due to the uncertainties and variabilities are evaluated on the basis of the first-order approximation of response statistics as well as numerical simulations
Energy Technology Data Exchange (ETDEWEB)
Perrier, V
2007-07-15
This work deals with the modelling and simulation of compressible flows. A seven equations model is obtained by homogenizing the Euler system. Fluctuation terms are modeled as relaxation terms. When the relaxation terms tend to infinity, which means that the phases are well mixed, a five equations model is obtained via an asymptotic expansion. This five equations model is strictly hyperbolic, but nonconservative. The discretization of this model is obtained by an asymptotic expansion of a scheme for the seven equations model. The numerical method is implemented, validated on analytic cases, and compared with experiments in the case of multiphase shocks. We are then interested in the modelling of phase transition with two equations of state. Optimization of the mixture entropy leads to the fact that three zones can be separated: one in which the pure liquid is the most stable, one in which the pure gas is the most stable, and one in which a mixture with equality of temperature, pressure and chemical potentials is the most stable. Conditions are given on the coupling of the two equations of state for ensuring that the mixture equation of state is convex, and that the system is strictly hyperbolic. In order to take into account phase transition, a vaporization wave is introduced in the solution of the Riemann problem, that is modeled as a deflagration wave. It is then proved that the usual closure, the Chapman-Jouguet closure, is wrong in general, and a correct closure in the case when both fluids have a perfect gas equation of state. Last, the solution of the Riemann problem is implemented in a multiphase code, and validated on analytic cases. In the same code, models of laser release and thermal conduction are implemented to simulate laser ablation. The results are comparable to the ones obtained with scale laws. The last chapter, fully independent, is concerned with correctors in stochastic homogenization in the case of heavy tails process. (author)
Nonlinear Fluid Simulation Study of Stimulated Raman and Brillouin Scatterings in Shock Ignition
Ren, Chuang; Hao, Liang; Yan, Rui; Li, Jun; Liu, Wenda
2017-10-01
We developed a new nonlinear fluid laser-plasma-instability code FLAME using a multi-fluid plasma model combined with full electromagnetic wave equations. The completed one-dimensional (1D) version of FLAME was used to study laser-plasma instabilities in shock ignition. The simulations results showed that absolute Stimulated Raman Scattering (SRS) modes growing near the quarter-critical surface were saturated by Langmuir-wave Decay Instabilities (LDI) and pump depletion. The ion-acoustic waves from LDI acted as seeds of Stimulated Brillouin Scattering (SBS), which displayed a bursting pattern and caused strong pump depletion. Re-scattering of SRS was also observed in a high temperature case. These results largely agreed with corresponding Particle-in-Cell simulations. Work funded by DOE (DE-SC0012316), NSF (PHY-1314734), NSFC (11642020, 11621202), and Science Challenge Project (No. JCKY2016212A505).
International Nuclear Information System (INIS)
Lichters, R.; Pfund, R.E.W.; Meyer-ter-Vehn, J.
1997-08-01
The code LPIC++ presented here, is based on a one-dimensional, electromagnetic, relativistic PIC code that has originally been developed by one of the authors during a PhD thesis at the Max-Planck-Institut fuer Quantenoptik for kinetic simulations of high harmonic generation from overdense plasma surfaces. The code uses essentially the algorithm of Birdsall and Langdon and Villasenor and Bunemann. It is written in C++ in order to be easily extendable and has been parallelized to be able to grow in power linearly with the size of accessable hardware, e.g. massively parallel machines like Cray T3E. The parallel LPIC++ version uses PVM for communication between processors. PVM is public domain software, can be downloaded from the world wide web. A particular strength of LPIC++ lies in its clear program and data structure, which uses chained lists for the organization of grid cells and enables dynamic adjustment of spatial domain sizes in a very convenient way, and therefore easy balancing of processor loads. Also particles belonging to one cell are linked in a chained list and are immediately accessable from this cell. In addition to this convenient type of data organization in a PIC code, the code shows excellent performance in both its single processor and parallel version. (orig.)
International Nuclear Information System (INIS)
Lefebvre, E.
2010-01-01
This series of slides overviews the development of powerful lasers for inertial confinement fusion (Icf) at NIF (National Ignition Facility, Usa) and LMJ (Laser Megajoule, France) facilities. Then the principle of laser wakefield acceleration is presented and the possibility of designing compact accelerators delivering 200 GeV/m while conventional RF accelerators reach only 50 MeV/m, is considered. This technical breakthrough will bring important gains in terms of size, cost and new uses for accelerators. While Icf will use nanosecond (10 -9 s) laser pulses, wakefield accelerators will use femtosecond (10 -15 s) laser pulses which means more power but less energy. The electrons accelerated by laser can produce a multi-MeV X radiation useful for industrial radiography or cancer treatment. (A.C.)
International Nuclear Information System (INIS)
Fouquet, T.
2007-01-01
In this work we present 2 important results. First, for a relatively moderate laser lighting (I*λ 2 ≅ 10 14 Wμm 2 /cm 2 ), cavitation appears in Langmuir decay instability (LDI) whenever the plasma wavelength is above a certain limit. Secondly, in the case of an inhomogeneous plasma there is an increase of the Raman reflectivity in presence of LDI for a plasma density profile that was initially smooth. This work is divided into 5 chapters. The first chapter is dedicated to parametric instabilities especially Raman instability and Langmuir decay instability. The equations that govern these instabilities as well as their numerical solutions are presented in the second chapter. The third chapter deals with the case of a mono-dimensional plasma with homogenous density. The saturation of the Raman instability in a mono-dimensional plasma with inhomogeneous density is studied in the fourth chapter. The last chapter is dedicated to bi-dimensional simulations for various types of laser beams
INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA High-power EUV (13.5 nm) light source
Borisov, Vladimir M.; Borisova, Galina N.; Vinokhodov, Aleksandr Yu; Zakharov, S. V.; Ivanov, Aleksandr S.; Kiryukhin, Yurii B.; Mishchenko, Valentin A.; Prokof'ev, Aleksandr V.; Khristoforov, Oleg B.
2010-10-01
Characteristics of a discharge-produced plasma (DPP) light source in the spectral band 13.5±0.135 nm, developed for Extreme Ultra Violet (EUV) lithography, are presented. EUV light is generated by DPP in tin vapour formed between rotating disk electrodes. The discharge is ignited by a focused laser beam. The EUV power 1000 W/(2π sr) in the spectral band 13.5±0.135 nm was achieved with input power about of ~63 kW to the plasma at a pulse repetition rate ~7 kHz . The results of numerical simulation are compared with the experimental data.
Mantouvalou, I; Jung, R; Tuemmler, J; Legall, H; Bidu, T; Stiel, H; Malzer, W; Kanngiesser, B; Sandner, W
2011-06-01
Different metal targets were investigated as possible source material for tailored laser-produced plasma-sources. In the wavelength range from 1 to 20 nm, x-ray spectra were collected with a calibrated spectrometer with a resolution of λ/Δλ = 150 at 1 nm up to λ/Δλ = 1100 at 15 nm. Intense line emission features of highly ionized species as well as continuum-like spectra from unresolved transitions are presented. With this knowledge, the optimal target material can be identified for the envisioned application of the source in x-ray spectrometry on the high energy side of the spectra at about 1 keV. This energy is aimed for because 1 keV-radiation is ideally suited for L-shell x-ray spectroscopy with nm-depth resolution. © 2011 American Institute of Physics
Directory of Open Access Journals (Sweden)
J. Ferri
2016-10-01
Full Text Available Petawatt, picosecond laser pulses offer rich opportunities in generating synchrotron x-rays. This paper concentrates on the regimes accessible with the PETAL laser, which is a part of the Laser Megajoule (LMJ facility. We explore two physically distinct scenarios through Particle-in-Cell simulations. The first one realizes in a dense plasma, such that the period of electron Langmuir oscillations is much shorter than the pulse duration. Hallmarks of this regime are longitudinal breakup (“self-modulation” of the picosecond-scale laser pulse and excitation of a rapidly evolving broken plasma wake. It is found that electron beams with a charge of several tens of nC can be obtained, with a quasi-Maxwellian energy distribution extending to a few-GeV level. In the second scenario, at lower plasma densities, the pulse is shorter than the electron plasma period. The pulse blows out plasma electrons, creating a single accelerating cavity, while injection on the density downramp creates a nC quasi-monoenergetic electron bunch within the cavity. This bunch accelerates without degradation beyond 1 GeV. The x-ray sources in the self-modulated regime offer a high number of photons (∼10^{12} with the slowly decaying energy spectra extending beyond 60 keV. In turn, quasimonoenergetic character of the electron beam in the blowout regime results in the synchrotron-like spectra with the critical energy around 10 MeV and a number of photons >10^{9}. Yet, much smaller source duration and transverse size increase the x-ray brilliance by more than an order of magnitude against the self-modulated case, also favoring high spatial and temporal resolution in x-ray imaging. In all explored cases, accelerated electrons emit synchrotron x-rays of high brilliance, B>10^{20} photons/s/mm^{2}/mrad^{2}/0.1%BW. Synchrotron sources driven by picosecond kilojoule lasers may thus find an application in x-ray diagnostics on such facilities such as the LMJ or National Ignition Facility (NIF.
Energy Technology Data Exchange (ETDEWEB)
Kotaki, H; Daito, I; Hayashi, Y; Ma, J; Chen, L-M; Kando, M; Esirkepov, T Z; Fukuda, Y; Homma, T; Pirozhkov, A; Koga, J K; Nakajima, K; Daido, H; Bulanov, S V [Advanced Photon Research Center, Japan Atomic Energy Agency, Kizugawa, Kyoto (Japan)], E-mail: kotaki.hideyuki@jaea.go.jp
2008-05-01
Counter-crossing injection, which is a realistic setup for applications, by two sub-relativistic laser pulses colliding at an angle of 45 degrees is demonstrated. The collision of the two laser pulses generates a high-quality electron beam with high reproducibility. The generated monoenergetic electron beam has a peak energy of 14.4 MeV, an energy spread of 10.6%, a charge of 21.8 pC, a normalized emittance of 1.6 {pi} mm mrad, and a reproducibility of 50%. The electron beam generation is unfolded with two-dimensional-particle-in-cell simulations. The laser pulses in plasma are self-focused to higher intensity when the laser power is above the threshold for relativistic self-focusing. The collision of the self-focused laser pulses generates a high-quality electron beam with high reproducibility.
Directory of Open Access Journals (Sweden)
S. Savin
2006-01-01
Full Text Available Proceeding with the analysis of Amata et al. (2005, we suggest that the general feature for the local transport at a thin magnetopause (MP consists of the penetration of ions from the magnetosheath with gyroradius larger than the MP width, and that, in crossing it, the transverse potential difference at the thin current sheet (TCS is acquired by these ions, providing a field-particle energy exchange without parallel electric fields. It is suggested that a part of the surface charge is self-consistently produced by deflection of ions in the course of inertial drift in the non-uniform electric field at MP. Consideration of the partial moments of ions with different energies demonstrates that the protons having gyroradii of roughly the same size or larger than the MP width carry fluxes normal to MP that are about 20% of the total flow in the plasma jet under MP. This is close to the excess of the ion transverse velocity over the cross-field drift speed in the plasma flow just inside MP (Amata et al., 2005, which conforms to the contribution of the finite-gyroradius inflow across MP. A linkage through the TCS between different plasmas results from the momentum conservation of the higher-energy ions. If the finite-gyroradius penetration occurs along the MP over ~1.5 RE from the observation site, then it can completely account for the formation of the jet under the MP. To provide the downstream acceleration of the flow near the MP via the cross-field drift, the weak magnetic field is suggested to rotate from its nearly parallel direction to the unperturbed flow toward being almost perpendicular to the accelerated flow near the MP. We discuss a deceleration of the higher-energy ions in the MP normal direction due to the interaction with finite-scale electric field bursts in the magnetosheath flow frame, equivalent to collisions, providing a charge separation. These effective collisions, with a nonlinear frequency proxy of the order of the proton
Crouch, R.S.; Bennett, T.
2000-01-01
This paper presents results and observations from the use of a rigorous method of treating the dynamic far-field as part of a non-linear FE analysis. The technique de-veloped by Wolf and Song (referred to as the Scaled Boundary Finite-Element Method) is incorporated into a 3-D time-domain analysis
Nonlinear optics at interfaces
International Nuclear Information System (INIS)
Chen, C.K.
1980-12-01
Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory
New high-power laser facility PALS-prospects for laser-plasma research
Czech Academy of Sciences Publication Activity Database
Rus, Bedřich; Rohlena, Karel; Skála, Jiří; Králiková, Božena; Jungwirth, Karel; Ullschmied, Jiří; Witte, K. J.; Baumhacker, H.
1999-01-01
Roč. 17, č. 2 (1999), s. 179-194 ISSN 0263-0346. [European Conference on Laser Interaction With Matter, ECLIM 1998 /25./. Formia, 04.05.1999-08.05.1999] Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.553, year: 1999
Czech Academy of Sciences Publication Activity Database
Ryc, L.; Krása, Josef; Nowak, T.; Kravárik, J.; Klír, J.; Krouský, Eduard; Lorusso, A.; Margarone, Daniele; Nassisi, V.; Pfeifer, Miroslav; Skála, Jiří; Ullschmied, Jiří; Velyhan, Andriy
2010-01-01
Roč. 165, 6-10 (2010), s. 481-487 ISSN 1042-0150 R&D Projects: GA MŠk(CZ) LC528 EU Projects: European Commission(XE) 228334 - LASERLAB-EUROPE Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : diamond detector * laser plasma * x-ray emission * ion emission Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.660, year: 2010
International Nuclear Information System (INIS)
Epstein, R.; Yaakobi, B.
1991-01-01
In laser-plasma experiments, conditions in an embedded layer in a target shell can be inferred from the spectral attenuation of x-ray continuum radiation by the layer [B. Yaakobi et al., Opt. Commun. 34, 213 (1980)]. In such experiments, absorption lines are formed by 1s-2p absorption transitions in heliumlike through fluorinelike species of certain ions in the layer to be diagnosed. The areal density of each species can be inferred from the attenuation in the spectrum within its respective band, provided the average 1s-2p absorption cross sections for each species are known and provided competing line-forming mechanisms are taken into account. In photoelectric fluorescence, which is one such potentially important competing mechanism, the formation of a 1s vacancy by photoionization is followed by 2p-1s spontaneous emission within the same spectral range as the 1s-2p absorption band of the same ion. The importance of photoelectric fluorescence depends on the supply of ionizing photons, which is sensitive to the design of the experiment. This process should be considered when analyzing experiments where the continuum is hardened by high core temperatures, by opacity effects, or by core components that radiate efficiently at ionizing energies
International Nuclear Information System (INIS)
Beaurepaire, B.
2009-01-01
Electronic microscopy and electron diffraction allowed the understanding of the organization of atoms in matter. Using a temporally short source, one can measure atomic displacements or modifications of the electronic distribution in matter. To date, the best temporal resolution for time resolved diffraction experiments is of the order of a hundred femto-seconds (fs). Laser accelerators are good candidates to reach the femtosecond temporal resolution in electron diffraction experiments. Such accelerators used to work at a low repetition rate, so that it was necessary to develop a new one operating at a high repetition rate in order to accumulate a large amount of data. In this thesis, a laser-plasma accelerator operating at the kHz repetition rate was developed and built. This source generates electron bunches at 100 keV from 3 mJ and 25 fs laser pulses. The physics of the acceleration has been studied, and the effect of the laser wavefront on the electron transverse distribution has been demonstrated. (author)
International Nuclear Information System (INIS)
Yamamoto, Yoshimasa; Friedman, Herman; Yoshimura, Hideyuki; Kinjo, Yasuhito; Shioda, Seiji; Debari, Kazuhiro; Shinohara, Kunio; Rajyaguru, Jayshree; Richardson, Martin
2000-01-01
A compact, high-resolution, laser-plasma, x-ray contact microscope using a table-top Nd:glass laser system has been developed and utilized for the analysis of the surface structure of live macrophages. Fine fluffy surface structures of murine peritoneal macrophages, which were live, hydrolyzed and not sliced and stained, were observed by the x-ray microscope followed by analysis using an atomic force microscopy. In order to compare with other techniques, a scanning electron microscopy (SEM) was utilized to observe the surface structure of the macrophages. The SEM offered a fine whole cell image of the same macrophages, which were fixed and dehydrated, but the surfaces were ruffled and different from that of x-ray images. A standard light microscope was also utilized to observe the shape of live whole macrophages. Light microscopy showed some fluffy surface structures of the macrophages, but the resolution was too low to observe the fine structures. Thus, the findings of fine fluffy surface structures of macrophages by x-ray microscopy provide valuable information for studies of phagocytosis, cell spreading and adherence, which are dependent on the surface structure of macrophages. Furthermore, the present study also demonstrates the usefulness of x-ray microscopy for analysis of structures of living cells
The prospects for soft x-ray contact microscopy using laser plasmas as an x-ray source
Energy Technology Data Exchange (ETDEWEB)
Stead, A.D.; Page, A.M.; Ford, T.W. [Univ. of London, Egham (United Kingdom). School of Biological Sciences
1995-12-31
Since its invention, a major concern of those using a microscope has been to improve the resolution without the introduction of artifacts. While light microscopy carries little risk of the introduction of artifacts, because the preparative techniques are often minimal, the resolution is somewhat limited. The advent of the electron microscope offered greatly improved resolution but since biological specimens require extensive preparation, the possibility of causing structural damage to the specimen is also increased. The ideal technique for structural studies of biological specimens would enable hydrated material to be examined without any preparation and with a resolution equal to that of electron microscopy. Soft x-ray microscopy certainly enables living material to be examined and whilst the resolution does not equal that of electron microscopy it exceeds that attainable by light microscopy. This paper briefly reviews the limitations of light and electron microscopy for the biologist and considers the various ways that soft x-rays might be used to image hydrated biological material. Consideration is given to the different sources that have been used for soft x-ray microscopy and the relative merits of laser-plasma sources are discussed.
International Nuclear Information System (INIS)
Newberger, B.S.; Thode, L.E.
1979-05-01
Experiments on the two-stream instability of a relativistic electron beam propagating through a neutral gas, carried out with the Lawrence Livermore Laboratory Astron beam, have been analyzed using a nonlinear saturation model for a cold beam. The behavior of the observed microwave emission due to the instability is in good agreement with that of the beam energy loss. Collisions on the plasma electrons weaken the nonlinear state of the instability but do not stabilize the mode. The beam essentially acts as if it were cold, a result substantiated by linear theory for waves propagating along the beam. In order to predict the effect of both beam momentum scatter and plasma electron collisions on the stability of the mode in future experiments a full two-dimensional linear theory must be developed
Magnetic field in laser plasmas: non-local electron transport and reconnection
International Nuclear Information System (INIS)
Riquier, Raphael
2016-01-01
In the framework of the inertial confinement fusion, a pellet filled with the deuterium-tritium fuel is imploded, either through laser irradiation (direct drive, laser - low atomic number target interaction) or by the black body radiation from a cavity converting the laser radiation (indirect drive, laser - high atomic number target interaction). In both cases, a correct modeling of the electron transport is of first importance in order to have predictive hydro-radiative simulations. Nonetheless, it has been shown early on that the hypothesis of the linear transport are not valid in the framework of a solid target irradiated by a high power laser (I≅10 14 W/cm 2 ). This is due in part to very steep temperature gradients (kinetic effects, so-called 'non-local') and because of a magnetic field self-generated through the thermo-electric effect. Finally, the heat flux and the magnetic field are strongly coupled through two mechanisms: the advection of the field with the heat flux (Nernst effect) and the rotation and inhibition of the heat flux by the plasma's magnetization (Righi-Leduc effect).In this manuscript, we will first present the various electron transport models, particularly the non-local with magnetic field model included in the hydro-radiative code FCI2. Following, in order to validate this model, we will compare it first against a kinetic code, and then with an experiment during which the magnetic field has been probed through proton radiography. Once the model validated, we will use FCI2 simulations to explain the source and transport of the field, as well as its effect on the interaction. Finally, the reconnection of the magnetic field, during the irradiation of a solid target by two laser beams, will be studied. (author) [fr
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.
International Nuclear Information System (INIS)
Prokopov, P A; Zakharov, Yu P; Tishchenko, V N; Shaikhislamov, I F; Boyarintsev, E L; Melekhov, A V; Ponomarenko, A G; Posukh, V G; Terekhin, V A
2016-01-01
Generation of Alfven waves propagating along external magnetic field B 0 and Collisionless Shock Waves propagating across B 0 are studied in experiments with laser- produced plasma and magnetized background plasma. The collisionless interaction of interpenetrating plasma flows takes place through a so-called Magnetic Laminar Mechanism (MLM) or Larmor Coupling. At the edge of diamagnetic cavity LP-ions produce induction electric field E φ which accelerates BP-ions while LP-ions rotate in opposite direction. The ions movement generates sheared azimuthal magnetic field B φ which could launches torsional Alfven wave. In previous experiments at KI-1 large scale facility a generation of strong perturbations propagating across B 0 with magnetosonic speed has been studied at a moderate value of interaction parameter δ∼0.3. In the present work we report on experiments at conditions of 5∼R2 and large Alfven-Mach number M A ∼10 in which strong transverse perturbations traveling at a scale of ∼1 m in background plasma at a density of ∼3*10 13 cm -3 is observed. At the same conditions but smaller M A ∼ 2 a generation, the structure and dynamic of Alfven wave with wavelength ∼0.5 m propagating along fields B 0 ∼100÷500 G for a distance of ∼2.5 m is studied. (paper)
Energy Technology Data Exchange (ETDEWEB)
Kaehle, Stephan
2009-04-23
This thesis deals with the production and application of ultrashort X-ray pulses. In the beginning different possibilities for the production of X-ray pulses with pulse durations of below one picosecond are presented, whereby the main topic lies on the so called laser-plasma X-ray sources with high repetition rate. In this case ultrashort laser pulses are focused on a metal, so that in the focus intensities of above 10{sup 16} W/cm{sup 2} dominate. In the ideal case in such way ultrafast electrons are produced, which are responsible for line radiation. In these experiments titanium K{sub {alpha}} radiation is produced, thes photons possess an energy of 4.51 keV. For the efficient production of line radiation here the Ti:Sa laser is optimized in view of the laser energy and the pulse shape and the influence of the different parameters on the K{sub {alpha}} production systematically studied. The influences of laser intensity, system-conditioned pre-pulses and of phase modulation are checked. It turns out that beside the increasement of the K{sub {alpha}} radiation by a suited laser intensity a reduction of the X-ray background radiation is of deciding importance for the obtaining of clear diffraction images. This background radiation is mainly composed of bremsstrahlung. It can be suppressed by the avoidance of intrinsic pre-pulses and by means of 2nd-order phase modulation. By means of optical excitation and X-ray exploration experiments the production of acoustic waves after ultrashort optical excitation in a 150 nm thick Ge(111) film on Si(111) is studied. These acoustic waves are driven by thermal (in this time scale time-independent) and electronic (time dependent) pressure amounts. As essential results it turns out that the relative amount of the electronic pressure increases with decreasing excitation density. [German] Diese Arbeit befasst sich mit der Erzeugung und Anwendung ultrakurzer Roentgenimpulse. Zu Beginn werden verschiedene Moeglichkeiten zur
Effects of ponderomotive forces and space-charge field on laser plasma hydrodynamics
International Nuclear Information System (INIS)
Cang Yu; Lu Xin; Wu Huichun; Zhang Jie
2005-01-01
Using a two-fluid two-temperature hydrodynamic code, authors studied the hydrodynamics in the interaction of intense (10 15 W/cm 2 ) ultrashort (150 fs) laser pulses and linear density plasmas. The simulation results show the ponderomotive force effect on the formation of the electron density ripples in under-dense region, such ripples increase the reflection of the laser pulse, and on the separation of the plasma in critical surface. Quasi-electroneutrality is not suitable in this case because of the different ponderomotive force and the gradient of thermal-pressure for ions and electrons. Ions are moved by the electrostatic force. Comparing with the simulation results from one-fluid two-temperature code, authors find that under strong ponderomotive force and gradient of thermo-pressure, two-fluid code is more suitable to simulate the hydrodynamics of plasmas. (authors)
Complementary ion and extreme ultra-violet spectrometer for laser-plasma diagnosis.
Ter-Avetisyan, S; Ramakrishna, B; Doria, D; Sarri, G; Zepf, M; Borghesi, M; Ehrentraut, L; Stiel, H; Steinke, S; Priebe, G; Schnürer, M; Nickles, P V; Sandner, W
2009-10-01
Simultaneous detection of extreme ultra-violet (XUV) and ion emission along the same line of sight provides comprehensive insight into the evolution of plasmas. This type of combined spectroscopy is applied to diagnose laser interaction with a spray target. The use of a micro-channel-plate detector assures reliable detection of both XUV and ion signals in a single laser shot. The qualitative analysis of the ion emission and XUV spectra allows to gain detailed information about the plasma conditions, and a correlation between the energetic proton emission and the XUV plasma emission can be suggested. The measured XUV emission spectrum from water spray shows efficient deceleration of laser accelerated electrons with energies up to keV in the initially cold background plasma and the collisional heating of the plasma.
Complementary ion and extreme ultra-violet spectrometer for laser-plasma diagnosis
International Nuclear Information System (INIS)
Ter-Avetisyan, S.; Ramakrishna, B.; Doria, D.; Sarri, G.; Zepf, M.; Borghesi, M.; Ehrentraut, L.; Stiel, H.; Steinke, S.; Schnuerer, M.; Nickles, P. V.; Sandner, W.; Priebe, G.
2009-01-01
Simultaneous detection of extreme ultra-violet (XUV) and ion emission along the same line of sight provides comprehensive insight into the evolution of plasmas. This type of combined spectroscopy is applied to diagnose laser interaction with a spray target. The use of a micro-channel-plate detector assures reliable detection of both XUV and ion signals in a single laser shot. The qualitative analysis of the ion emission and XUV spectra allows to gain detailed information about the plasma conditions, and a correlation between the energetic proton emission and the XUV plasma emission can be suggested. The measured XUV emission spectrum from water spray shows efficient deceleration of laser accelerated electrons with energies up to keV in the initially cold background plasma and the collisional heating of the plasma.
The image of a nanosecond laser plasma in its own optical radiation
Fronya, A. A.; Borisenko, N. G.; Puzyrev, V. N.; Sahakyan, A. T.; Starodub, A. N.; Yakushev, O. F.
2017-12-01
The results of experiments on the interaction of nanosecond laser radiation (wavelength of 1.06 μm and a radiation power density of 1012–1013 W/cm2) with targets from various materials (Cu, (C2H4)n, TAC) are presented in the paper. In the experiments images of the plasma in own optical radiation in the wavelength range 0.4–1.1 μm were obtained. In one shot of laser images at wavelengths corresponding to the radiation of the harmonics 2ω 0, 3/2ω 0, 5/2ω 0, and at the frequency of laser radiation ω 0 were recorded. Using the obtained images the spatial characteristics of the radiating regions of the plasma, as well as the radiated energy for each of the harmonics, were estimated.
Efficient Modeling of Laser-Plasma Accelerators with INF&RNO
Energy Technology Data Exchange (ETDEWEB)
Benedetti, C.; Schroeder, C. B.; Esarey, E.; Geddes, C. G. R.; Leemans, W. P.
2010-06-01
The numerical modeling code INF&RNO (INtegrated Fluid& paRticle simulatioN cOde, pronounced"inferno") is presented. INF&RNO is an efficient 2D cylindrical code to model the interaction of a short laser pulse with an underdense plasma. The code is based on an envelope model for the laser while either a PIC or a fluid description can be used for the plasma. The effect of the laser pulse on the plasma is modeled with the time-averaged poderomotive force. These and other features allow for a speedup of 2-4 orders of magnitude compared to standard full PIC simulations while still retaining physical fidelity. The code has been benchmarked against analytical solutions and 3D PIC simulations and here a set of validation tests together with a discussion of the performances are presented.
Brilliant radiation sources by laser-plasma accelerators and optical undulators
Energy Technology Data Exchange (ETDEWEB)
Debus, Alexander
2012-09-06
This thesis investigates the use of high-power lasers for synchrotron radiation sources with high brilliance, from the EUV to the hard X-ray spectral range. Hereby lasers accelerate electrons by laser-wakefield acceleration (LWFA), act as optical undulators, or both. Experimental evidence shows for the first time that LWFA electron bunches are shorter than the driving laser and have a length scale comparable to the plasma wavelength. Furthermore, a first proof of principle experiment demonstrates that LWFA electrons can be exploited to generate undulator radiation. Building upon these experimental findings, as well as extensive numerical simulations of Thomson scattering, the theoretical foundations of a novel interaction geometry for laser-matter interaction are developed. This new method is very general and when tailored towards relativistically moving targets not being limited by the focusability (Rayleigh length) of the laser, while it does not require a waveguide. In a theoretical investigation of Thomson scattering, the optical analogue of undulator radiation, the limits of Thomson sources in scaling towards higher peak brilliances are highlighted. This leads to a novel method for generating brilliant, highly tunable X-ray sources, which is highly energy efficient by circumventing the laser Rayleigh limit through a novel traveling-wave Thomson scattering (TWTS) geometry. This new method suggests increases in X-ray photon yields of 2-3 orders of magnitudes using existing lasers and a way towards efficient, optical undulators to drive a free-electron laser. The results presented here extend far beyond the scope of this work. The possibility to use lasers as particle accelerators, as well as optical undulators, leads to very compact and energy efficient synchrotron sources. The resulting monoenergetic radiation of high brilliance in a range from extreme ultraviolet (EUV) to hard X-ray radiation is of fundamental importance for basic research, medical
Furuseth, Sondre
2017-01-01
The performance of high-energy circular hadron colliders, as the Large Hadron Collider, is limited by beam-beam interactions. The strongly nonlinear force between the two opposing beams causes diverging Hamiltonians and resonances, which can lead to a reduction of the lifetime of the beams. The nonlinearity makes the effect of the force difficult to study analytically, even at first order. Numerical models are therefore needed to evaluate the overall effect of different configurations of the machines. This report discusses results from an implementation of the weak-strong model, studying the effects of head-on beam-beam interactions. The assumptions has been shown to be valid for configurations where the growth and losses of the beam are small. The tracking has been done using an original code which applies graphic cards to reduce the computation time. The bunches in the beams have been modelled cylindrically symmetrical, based on a Gaussian distribution in three dimensions. This choice fits well with bunches...
Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question
Yang, X; Reboredo Gil, David; Welsh, Gregor H; Li, Y.F; Cipiccia, Silvia; Ersfeld, Bernhard; Grant, D. W; Grant, P. A; Islam, Muhammad; Tooley, M.B; Vieux, Gregory; Wiggins, Sally; Sheng, Zheng-Ming; Jaroszynski, Dino
2017-01-01
Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lowerenergy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wake...
Progress on laser plasma accelerator development using transverselyand longitudinally shaped plasmas
Energy Technology Data Exchange (ETDEWEB)
Leemans, Wim P.; Esarey, E.; Geddes, C.G.R.; Toth, Cs.; Schroeder, C.B.; Nakamura, K.; Gonsalves, A.J.; Panasenko, D.; Cormier-Michel, E.; Plateau, G.R.; Lin, C.; Bruhwiler, D.L.; Cary, J.R.
2009-03-31
A summary of progress at Lawrence Berkeley National Laboratory is given on: (1) experiments on down-ramp injection; (2) experiments on acceleration in capillary discharge plasma channels; and (3) simulations of a staged laser wakefield accelerator (LWFA). Control of trapping in a LWFA using plasma density down-ramps produced electron bunches with absolute longitudinal and transverse momentum spreads more than ten times lower than in previous experiments (0.17 and 0.02 MeV Ic FWHM, respectively) and with central momenta of 0.76 +- 0.02 MeV Ic, stable over a week of operation. Experiments were also carried out using a 40 TW laser interacting with a hydrogen-filled capillary discharge waveguide. For a 15 mm long, 200 mu m diameter capillary, quasi-monoenergetic bunches up to 300 MeV were observed. By detuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized. For a 33 mm long, 300 mu m capillary, a parameter regime with high energy bunches, up to 1 Ge V, was found. In this regime, peak electron energy was correlated with the amount of trapped charge. Simulations show that bunches produced on a down-ramn and iniected into a channel-guided LWFA can produce stable beams with 0.2 MeV Ic-class momentum spread at high energies.
Observation of 1-D time dependent non-propagating laser plasma structures using fluid and PIC codes
Verma, Deepa; Bera, Ratan Kumar; Kumar, Atul; Patel, Bhavesh; Das, Amita
2017-12-01
The manuscript reports the observation of time dependent localized and non-propagating structures in the coupled laser plasma system through 1-D fluid and Particle-In-Cell (PIC) simulations. It is reported that such structures form spontaneously as a result of collision amongst certain exact solitonic solutions. They are seen to survive as coherent entities for a long time up to several hundreds of plasma periods. Furthermore, it is shown that such time dependence can also be artificially recreated by significantly disturbing the delicate balance between the radiation and the density fields required for the exact non-propagating solution obtained by Esirkepov et al., JETP 68(1), 36-41 (1998). The ensuing time evolution is an interesting interplay between kinetic and field energies of the system. The electrostatic plasma oscillations are coupled with oscillations in the electromagnetic field. The inhomogeneity of the background and the relativistic nature, however, invariably produces large amplitude density perturbations leading to its wave breaking. In the fluid simulations, the signature of wave breaking can be discerned by a drop in the total energy which evidently gets lost to the grid. The PIC simulations are observed to closely follow the fluid simulations till the point of wave breaking. However, the total energy in the case of PIC simulations is seen to remain conserved throughout the simulations. At the wave breaking, the particles are observed to acquire thermal kinetic energy in the case of PIC. Interestingly, even after wave breaking, compact coherent structures with trapped radiation inside high-density peaks continue to exist both in PIC and fluid simulations. Although the time evolution does not exactly match in the two simulations as it does prior to the process of wave breaking, the time-dependent features exhibited by the remnant structures are characteristically similar.
van Tilborg, Jeroen
2017-10-01
The success of laser plasma accelerator (LPA) based applications, such as a compact x-ray free electron laser (FEL), relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot energy-dispersed emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock-induced density down-ramp injection. Both injection mechanisms have gained in popularity in recent years due to their demonstrated stable LPA performance. For the down-ramp injection configuration, normalized emittances a factor of two lower were recorded: less than 1 micron at spectral charge densities up to 2 pC/MeV. For both injection mechanisms, a contributing correlation of space charge to the emittance was identified. This measurement technique in general, and these results specifically, are critical to the evaluation of LPA injection methods and development of high-quality LPA beam lines worldwide. This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the U.S. DOE NNSA, DNN R&D (NA22), by the National Science Foundation under Grant No. PHY-1415596, and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.
Terletska, Kateryna; Maderich, Vladimir; Brovchenko, Igor; Jung, Kyung Tae
2013-04-01
In the freshwater lakes in moderate latitudes stratification occurs as a result of the seasonal warming of the surface water layer. Than the intense wind surges (usually in autumn) tilt the surface and generate long basin-scale low-frequency standing internal waves (seiches). Depending on the initial interface tilt and stratification wide spectra of possible flow regimes can be observed [1]-[2].They varied from small amplitude symmetric seiches to large amplitude nonlinear waves.Nonlinearity leads to an asymmetry of internal waves and appearance of the surge or bore and further disintegration of it on a sequence of solitary waves. In present study degeneration of the strongly nonlinear internal seiches in elongated lakes with a concave "spoon-like" topography is investigated.Two different three-dimensional non-hydrostatic free-surface numerical models are used to investigate degeneration of large internal waves and its subsequent interaction with the concave lake slope. One of this model is non-hydrostatic model [3] and the other is a well-known MIT model. At first we consider idealized elongated elliptic-shape lake with the dimension of 5 km X 1 km with the maximal depth 30 m. The stratification in lake is assumed to be given in a form of the tangent function with a density difference between upper and lower layers 2 kgm-3 . It is assumed that motion in such lake is initiated by inclination of thermocline on a certain angle. Than lake adjusts to return to its original state producing internal seiches which begin interacting with a bottom topography. The process of degeneration of internal seiches in the lake with concave ends consist of chain of elementary processes: 1) steeping of long basin scale large amplitude wave, that evolve into internal surge, 2) surge interact with concave lake ends that leads the concentration of the flow and formation of down slope bottom jet along the lake axis, 3) due to cumulative effect local velocity in the jet accelerates up to
Rojan, Katharina; Léger, Yoan; Morigi, Giovanna; Richard, Maxime; Minguzzi, Anna
2017-09-01
Semiconductor microcavities in the strong-coupling regime exhibit an energy scale in the terahertz (THz) frequency range, which is fixed by the Rabi splitting between the upper and lower exciton-polariton states. While this range can be tuned by several orders of magnitude using different excitonic media, the transition between both polaritonic states is dipole forbidden. In this work, we show that, in cadmium telluride microcavities, the Rabi-oscillation-driven THz radiation is actually active without the need for any change in the microcavity design. This feature results from the unique resonance condition which is achieved between the Rabi splitting and the phonon-polariton states and leads to a giant enhancement of the second-order nonlinearity.
Nonlinear Optics and Applications
Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)
2007-01-01
Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.
Bloembergen, Nicolaas
1996-01-01
Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe
Singh, B. P.; Nampoothiri, A. V. V.; Kundu, T.; Puntambekar, P. N.; Saha, D.; Dhanabalan, A.; Talwar, S. S.
1999-02-01
A model incorporating the exciton-phonon interaction for a quantitative description of the third-order nonlinear optical response of a one-dimensional conjugated polymer chain in the vicinity of a one-photon resonance is proposed. This model has been used to describe our observations on the dispersion of the second molecular hyperpolarizability, γ( - ωω,ω, - ω), of poly(1,4 bis(3-quinolyl))-1,3 butadyne in the spectral range 720 810 nm satisfactorily. The large observed precipitous enhancement close to the absorption tail could not be explained by the essential states models. It is found that the phonon-mediated shift of the exciton resonance is responsible for the large monotonic variation of γ, whilst the phase space filling effect renders γ its self-defocusing character.
Time-resolved X-ray diffraction with accelerator- and laser-plasma-based X-ray sources
Energy Technology Data Exchange (ETDEWEB)
Nicoul, Matthieu
2010-09-01
Femtosecond X-ray pulses are a powerful tool to investigate atomic motions triggered by femtosecond pump pulses. This thesis is dedicated to the production of such pulses and their use in optical pump - X-ray probe measurement. This thesis describes the laser-plasma-based sources available at the University of Duisburg-Essen. Part of it consists of the description of the design, built-up and characterization of a new ''modular'' X-ray source dedicated to optimize the X-ray flux onto the sample under investigation. The acoustic wave generation in femtosecond optically excited semiconductor (gallium arsenide) and metal (gold) was performed using the sources of the University of Duisburg-Essen. The physical answer of the material was modeled by a simple strain model for the semiconductor, pressure model for the metal, in order to gain information on the interplay of the electronic and thermal pressures rising after excitation. Whereas no reliable information could be obtain in gallium arsenide (principally due to the use of a bulk), the model for gold achieved very good agreement, providing useful information. The relaxation time of the electron to lattice energy was found to be (5.0{+-}0.3) ps, and the ratio of the Grueneisen parameters was found to be {gamma}{sub e} / {gamma}{sub i} = (0.5{+-}0.1). This thesis also describes the Sub-Picosecond Pulse Source (SPPS) which existed at the (formally) Stanford Linear Accelerator Center, an accelerator-based X-ray source, and two measurements performed with it. The first one is the detailed investigation of the phonon softening of the A{sub 1g} mode launch in bismuth upon fluence excitation. Detailed information concerning the new equilibrium position and phonon frequency were obtained over extended laser pump fluences. The second measurement concerned the study of the liquid phase dynamics in a newly formed liquid phase following ultrafast melting in indium antimonide. The formation of the liquid phase
Energy Technology Data Exchange (ETDEWEB)
Titberidze, Mikheil
2017-10-15
Laser wakefield acceleration (LWFA) is a novel technique to accelerate charged particles. Acceleration is achieved by a high-power laser pulse transmitting a gas target where electrons and ions form a strong wakefield with gradients up to 100 GVm{sup -1}. Hence, the size of the laser-plasma accelerator (LPA) is significantly smaller compared to conventional radio frequency (RF) accelerators, because its accelerating gradients are 3 orders of magnitude higher. At present, electron beams generated by LWFA do not satisfy all requirements to make them directly usable for applications such as LPA driven free-electron laser (FEL). Pointing stability and relatively high energy spread are the major limiting factors. Typically, plasma electrons are self-injected in the plasma wake which is created by a high-power laser. There is a lack of control for the injection process and there is no direct access for diagnostics. In order to overcome these challenges and better understand the overall LWFA process, external injection experiments are planned at Deutsches Elektronen-Synchrotron (DESY) in the framework of the Laboratory for Laser and beam-driven plasma Acceleration (LAOLA) collaboration. Thus, well characterized and ultrashort (< 10 fs) electron bunches from the conventional RF accelerator Relativistic Electron Gun for Atomic Exploration (REGAE) will be injected into the laser driven plasma wake. This approach allows to reconstruct and map the plasma wakefield by post diagnosing the injected electron bunches by measuring the energy spectra of it for different injection times. To conduct such a pump-probe type of experiment, synchronization with fs accuracy is required between the electron bunches from REGAE and the high-power driver laser. Two main aspects of the laser synchronization are presented in this thesis. First, a detailed experimental investigation of the conventional, fast photodiode based direct conversion laser-to-RF synchronization setup and its limitations
International Nuclear Information System (INIS)
Titberidze, Mikheil
2017-10-01
Laser wakefield acceleration (LWFA) is a novel technique to accelerate charged particles. Acceleration is achieved by a high-power laser pulse transmitting a gas target where electrons and ions form a strong wakefield with gradients up to 100 GVm -1 . Hence, the size of the laser-plasma accelerator (LPA) is significantly smaller compared to conventional radio frequency (RF) accelerators, because its accelerating gradients are 3 orders of magnitude higher. At present, electron beams generated by LWFA do not satisfy all requirements to make them directly usable for applications such as LPA driven free-electron laser (FEL). Pointing stability and relatively high energy spread are the major limiting factors. Typically, plasma electrons are self-injected in the plasma wake which is created by a high-power laser. There is a lack of control for the injection process and there is no direct access for diagnostics. In order to overcome these challenges and better understand the overall LWFA process, external injection experiments are planned at Deutsches Elektronen-Synchrotron (DESY) in the framework of the Laboratory for Laser and beam-driven plasma Acceleration (LAOLA) collaboration. Thus, well characterized and ultrashort (< 10 fs) electron bunches from the conventional RF accelerator Relativistic Electron Gun for Atomic Exploration (REGAE) will be injected into the laser driven plasma wake. This approach allows to reconstruct and map the plasma wakefield by post diagnosing the injected electron bunches by measuring the energy spectra of it for different injection times. To conduct such a pump-probe type of experiment, synchronization with fs accuracy is required between the electron bunches from REGAE and the high-power driver laser. Two main aspects of the laser synchronization are presented in this thesis. First, a detailed experimental investigation of the conventional, fast photodiode based direct conversion laser-to-RF synchronization setup and its limitations are
Time-resolved X-ray diffraction with accelerator- and laser-plasma-based X-ray sources
International Nuclear Information System (INIS)
Nicoul, Matthieu
2010-01-01
Femtosecond X-ray pulses are a powerful tool to investigate atomic motions triggered by femtosecond pump pulses. This thesis is dedicated to the production of such pulses and their use in optical pump - X-ray probe measurement. This thesis describes the laser-plasma-based sources available at the University of Duisburg-Essen. Part of it consists of the description of the design, built-up and characterization of a new ''modular'' X-ray source dedicated to optimize the X-ray flux onto the sample under investigation. The acoustic wave generation in femtosecond optically excited semiconductor (gallium arsenide) and metal (gold) was performed using the sources of the University of Duisburg-Essen. The physical answer of the material was modeled by a simple strain model for the semiconductor, pressure model for the metal, in order to gain information on the interplay of the electronic and thermal pressures rising after excitation. Whereas no reliable information could be obtain in gallium arsenide (principally due to the use of a bulk), the model for gold achieved very good agreement, providing useful information. The relaxation time of the electron to lattice energy was found to be (5.0±0.3) ps, and the ratio of the Grueneisen parameters was found to be γ e / γ i = (0.5±0.1). This thesis also describes the Sub-Picosecond Pulse Source (SPPS) which existed at the (formally) Stanford Linear Accelerator Center, an accelerator-based X-ray source, and two measurements performed with it. The first one is the detailed investigation of the phonon softening of the A 1g mode launch in bismuth upon fluence excitation. Detailed information concerning the new equilibrium position and phonon frequency were obtained over extended laser pump fluences. The second measurement concerned the study of the liquid phase dynamics in a newly formed liquid phase following ultrafast melting in indium antimonide. The formation of the liquid phase and its development for excitations close to the
International Nuclear Information System (INIS)
Kennedy, R.P.; Kincaid, R.H.; Short, S.A.
1985-03-01
This report presents the results of part of a two-task study on the engineering characterization of earthquake ground motion for nuclear power plant design. Task I of the study, which is presented in NUREG/CR-3805, Vol. 1, developed a basis for selecting design response spectra taking into account the characteristics of free-field ground motion found to be significant in causing structural damage. Task II incorporates additional considerations of effects of spatial variations of ground motions and soil-structure interaction on foundation motions and structural response. The results of Task II are presented in four parts: (1) effects of ground motion characteristics on structural response of a typical PWR reactor building with localized nonlinearities and soil-structure interaction effects; (2) empirical data on spatial variations of earthquake ground motion; (3) soil-structure interaction effects on structural response; and (4) summary of conclusions and recommendations based on Tasks I and II studies. This report presents the results of the first part of Task II. The results of the other parts will be presented in NUREG/CR-3805, Vols. 3 to 5
International Nuclear Information System (INIS)
Palmer, R.B.; Baggett, N.; Claus, J.; Fernow, R.; Ghosh, A.; Giordano, S.; Radeka, V.; Stumer, I.; Takacs, P.; Warren, J.
1985-01-01
The grating accelerator concept is reviewed. The use of a double row of conducting droplets instead of a conventional grating constrains the fields to a narrow band. The use of droplets also allows fields that will destroy the structure. RF modelling results are presented together with a simple theory of the fields. Coupling to incoming radiation is described. A possible laser specification is also given. (orig.)