The Experts below are selected from a list of 6462 Experts worldwide ranked by ideXlab platform
S V Bulanov - One of the best experts on this subject based on the ideXlab platform.
-
high power γ ray flash generation in ultraintense Laser Plasma Interactions
Physical Review Letters, 2012Co-Authors: Tatsufumi Nakamura, S V Bulanov, James Koga, Timur Zh Esirkepov, Masaki Kando, G KornAbstract:When high-intensity Laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high-power $\ensuremath{\gamma}$-ray flashes. The $\ensuremath{\gamma}$-ray pulse duration and divergence are determined by the Laser pulse amplitude and by the Plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a $\ensuremath{\gamma}$-ray flash with a tailored overcritical density target are found.
-
high power γ ray flash generation in ultraintense Laser Plasma Interactions
Physical Review Letters, 2012Co-Authors: Tatsufumi Nakamura, James Koga, Timur Zh Esirkepov, Masaki Kando, G Korn, S V BulanovAbstract:When high-intensity Laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high power gamma ray flashes. The gamma-ray pulse duration and divergence are determined by the Laser pulse amplitude and by the Plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a gamma-ray flash with a tailored overcritical density target are found.
-
generation of collimated beams of relativistic ions in Laser Plasma Interactions
Jetp Letters, 2000Co-Authors: S V Bulanov, K Mima, Zh T Esirkepov, Francesco Califano, Yoshiaki Kato, T V Liseikina, N M Naumova, K Nishihara, F Pegoraro, H RuhlAbstract:A method is proposed for generating collimated beams of fast ions in Laser-Plasma Interactions. Two-dimensional and three-dimensional particle-in-cell simulations show that the ponderomotive force expels electrons from the Plasma region irradiated by a Laser pulse. The ions with unneutralized electric charge that remain in this region are accelerated by Coulomb repulsive forces. The ions are focused by tailoring the target and also as a result of pinching in the magnetic field produced by the electric current of fast ions.
M Zepf - One of the best experts on this subject based on the ideXlab platform.
-
giant isolated attosecond pulses from two color Laser Plasma Interactions
Physical Review Letters, 2020Co-Authors: M Zepf, Y Zhang, S G Rykovanov, Mingyuan Shi, C L Zhong, B QiaoAbstract:A new regime in the interaction of a two-color (ω,2ω) Laser with a nanometer-scale foil is identified, resulting in the emission of extremely intense, isolated attosecond pulses-even in the case of multicycle Lasers. For foils irradiated by Lasers exceeding the blow-out field strength (i.e., capable of fully separating electrons from the ion background), the addition of a second harmonic field results in the stabilization of the foil up to the blow-out intensity. This is then followed by a sharp transition to transparency that essentially occurs in a single optical cycle. During the transition cycle, a dense, nanometer-scale electron bunch is accelerated to relativistic velocities and emits a single, strong attosecond pulse with a peak intensity approaching that of the Laser field.
-
intense attosecond pulses carrying orbital angular momentum using Laser Plasma Interactions
Nature Communications, 2019Co-Authors: Jingwei Wang, M Zepf, S G RykovanovAbstract:Light beams with helical phase-fronts are known to carry orbital angular momentum (OAM) and provide an additional degree of freedom to beams of coherent light. While OAM beams can be readily derived from Gaussian Laser beams with phase plates or gratings, this is far more challenging in the extreme ultra-violet (XUV), especially for the case of high XUV intensity. Here, we theoretically and numerically demonstrate that intense surface harmonics carrying OAM are naturally produced by the intrinsic dynamics of a relativistically intense circularly-polarized Gaussian beam (i.e. non-vortex) interacting with a target at normal incidence. Relativistic surface oscillations convert the Laser pulses to intense XUV harmonic radiation via the well-known relativistic oscillating mirror mechanism. We show that the azimuthal and radial dependence of the harmonic generation process converts the spin angular momentum of the Laser beam to orbital angular momentum resulting in an intense attosecond pulse (or pulse train) with OAM. Vortices in light fields are of growing importance in the XUV and X-ray ranges. Here the authors show by simulations that high harmonics and attosecond pulses, generated while irradiating a deformed thin foil with circularly-polarized Gaussian Laser pulses, carry a well-defined orbital angular momentum.
-
beaming of high order harmonics generated from Laser Plasma Interactions
Physical Review Letters, 2013Co-Authors: M Yeung, B Dromey, D Adams, S Cousens, Rainer Horlein, Yutaka Nomura, George D Tsakiris, M ZepfAbstract:Beam divergences of high-order extreme ultraviolet harmonics from intense Laser Interactions with steep Plasma density gradients are studied through experiment and Fourier analysis of the harmonic spatial phase. We show that while emission due to the relativistically oscillating mirror mechanism can be explained by ponderomotive surface denting, in agreement with previous results, the divergence of the emission due to the coherent wake emission mechanism requires a combination of the dent phase and an intrinsic emission phase. The temporal dependence of the divergences for both mechanisms is highlighted while it is also shown that the coherent wake emission divergence can be small in circumstances where the phase terms compensate each other.
-
ion acceleration from the shock front induced by hole boring in ultraintense Laser Plasma Interactions
Physical Review E, 2004Co-Authors: H Habara, C D Murphy, M Borghesi, M Zepf, K L Lancaster, S Karsch, P A Norreys, R G Evans, L Romagnani, T NorimatsuAbstract:Ion-acceleration processes have been studied in ultraintense Laser Plasma Interactions for normal incidence irradiation of solid deuterated targets via neutron spectroscopy. The experimental neutron spectra strongly suggest that the ions are preferentially accelerated radially, rather than into the bulk of the material from three-dimensional Monte Carlo fitting of the neutron spectra. Although the Laser system has a ${10}^{\ensuremath{-}7}$ contrast ratio, a two-dimensional magnetic hydrodynamics simulation shows that the Laser pedestal generates a $10\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ scale length in the coronal Plasma with a $3\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ scale-length Plasma near the critical density. Two-dimensional particle-in-cell simulations, incorporating this realistic density profile, indicate that the acceleration of the ions is caused by a collisionless shock formation. This has implications for modeling energy transport in solid density Plasmas as well as cone-focused fast ignition using the next generation PW Lasers currently under construction.
-
measurements of ultrastrong magnetic fields during relativistic Laser Plasma Interactions
Physics of Plasmas, 2002Co-Authors: M Tatarakis, A. E. Dangor, P A Norreys, A Gopal, I Watts, F N Beg, K Krushelnick, U Wagner, E L Clark, M ZepfAbstract:Measurements of magnetic fields generated during ultrahigh intensity (>1019 W cm−2), short pulse (0.7–1 ps) Laser–solid target interaction experiments are reported. An innovative method is used and the results are compared with particle-in-cell simulations. It is shown that polarization measurements of the self-generated harmonics of the Laser can provide a convenient method for diagnosing the magnetic field—and that the experimental measurements indicate the existence of peak fields greater than 340 MG and below 460 MG at such high intensities. In particular, the observation of the X-wave cutoffs and the observed induced ellipticity of the harmonics can provide a reliable method for measuring these fields. These observations are important for evaluating the use of intense Lasers in various potential applications and perhaps for understanding the complex physics of exotic astrophysical objects such as neutron stars.
A G R Thomas - One of the best experts on this subject based on the ideXlab platform.
-
measuring magnetic flux suppression in high power Laser Plasma Interactions
arXiv: Plasma Physics, 2021Co-Authors: Paul T Campbell, I V Igumenshchev, C A Walsh, Brandon Russell, J P Chittenden, Aidan Crilly, G Fiksel, Lan Gao, P M Nilson, A G R ThomasAbstract:Biermann battery magnetic field generation driven by high power Laser-solid Interactions is explored in experiments performed with the OMEGA EP Laser system. Proton deflectometry captures changes to the strength, spatial profile, and temporal dynamics of the self-generated magnetic fields as the target material or Laser intensity is varied. Measurements of the magnetic flux during the interaction are used to help validate extended magnetohydrodynamic (MHD) simulations. Results suggest that kinetic effects cause suppression of the Biermann battery mechanism in Laser-Plasma Interactions relevant to both direct and indirect-drive inertial confinement fusion. Experiments also find that more magnetic flux is generated as the target atomic number is increased, which is counter to a standard MHD understanding.
-
enhanced Laser absorption from radiation pressure in intense Laser Plasma Interactions
New Journal of Physics, 2017Co-Authors: F Dollar, C Zulick, V Chvykov, Anthony Raymond, A G R Thomas, L Willingale, V Yanovsky, A MaksimchukAbstract:The reflectivity of a short-pulse Laser at intensities of 2 x 10(21) Wcm(-2) with ultra-high contrast (10(-15)) on sub-micrometer silicon nitride foils was studied experimentally using varying polarizations and target thicknesses. The reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. Experimental results and trends observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure on the absorption process. Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.
-
energetic neutron beams generated from femtosecond Laser Plasma Interactions
Applied Physics Letters, 2013Co-Authors: C Zulick, F Dollar, V Chvykov, G Kalinchenko, George Petrov, Anthony Raymond, A G R ThomasAbstract:Experiments at the HERCULES Laser facility have produced directional neutron beams with energies up to 16.8(±0.3) MeV using d12(d,n)23He,Li73(p,n)47Be,andLi37(d,n)48Be reactions. Efficient Li12(d,n)48Be reactions required the selective acceleration of deuterons through the introduction of a deuterated plastic or cryogenically frozen D2O layer on the surface of a thin film target. The measured neutron yield was ≤1.0 (±0.5)×107 neutrons/sr with a flux 6.2(±3.7) times higher in the forward direction than at 90°. This demonstrates that femtosecond Lasers are capable of providing a time averaged neutron flux equivalent to commercial d12(d,n)23He generators with the advantage of a directional beam with picosecond bunch duration.
-
observation of monoenergetic relativistic electron beams from intense Laser Plasma Interactions
Quantum Electronics and Laser Science Conference, 2005Co-Authors: Stuart Mangles, C D Murphy, A G R Thomas, Zulfikar Najmudin, A. E. Dangor, P S Foster, K Krushelnick, B Walton, C J Hooker, A J LangleyAbstract:We report the observation of monoenergetic electron beams (dE/E<5%) produced by the interaction of a 12TW, 40fs Laser pulse with underdense Plasma, in contrast to all previous experiments, which produced energy spreads ~100%
-
monoenergetic beams of relativistic electrons from intense Laser Plasma Interactions
Nature, 2004Co-Authors: Stuart Mangles, C D Murphy, A G R Thomas, Zulfikar Najmudin, A. E. Dangor, E. J. Divall, J L Collier, P S Foster, J. G. GallacherAbstract:High-power Lasers that fit into a university-scale laboratory1 can now reach focused intensities of more than 1019 W cm-2 at high repetition rates. Such Lasers are capable of producing beams of energetic electrons2,3,4,5,6,7,8,9,10,11, protons12 and γ-rays13. Relativistic electrons are generated through the breaking9,10,14 of large-amplitude relativistic Plasma waves created in the wake of the Laser pulse as it propagates through a Plasma, or through a direct interaction between the Laser field and the electrons in the Plasma15. However, the electron beams produced from previous Laser–Plasma experiments have a large energy spread6,7,9,14, limiting their use for potential applications. Here we report high-resolution energy measurements of the electron beams produced from intense Laser–Plasma Interactions, showing that—under particular Plasma conditions—it is possible to generate beams of relativistic electrons with low divergence and a small energy spread (less than three per cent). The monoenergetic features were observed in the electron energy spectrum for Plasma densities just above a threshold required for breaking of the Plasma wave. These features were observed consistently in the electron spectrum, although the energy of the beam was observed to vary from shot to shot. If the issue of energy reproducibility can be addressed, it should be possible to generate ultrashort monoenergetic electron bunches of tunable energy, holding great promise for the future development of ‘table-top’ particle accelerators.
L O Silva - One of the best experts on this subject based on the ideXlab platform.
-
anisotropic heating and magnetic field generation due to raman scattering in Laser Plasma Interactions
Physical Review Research, 2020Co-Authors: T Silva, Ricardo Fonseca, K M Schoeffler, Jorge Vieira, Masahiro Hoshino, L O SilvaAbstract:This work uses theory and particle-in-cell simulations to unveil a novel mechanism for the generation of strong magnetic fields in Laser-Plasma Interactions. The authors show that stimulated Raman scattering Plasma waves heat a Plasma anisotropically. The resulting temperature anisotropy leads to the onset of the Weibel instability.
-
Laser Plasma Interactions for fast ignition
arXiv: Plasma Physics, 2013Co-Authors: A J Kemp, W B Mori, Y Sentoku, F Fiuza, A Debayle, T Johzaki, P K Patel, L O SilvaAbstract:In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt Laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense Laser Plasma Interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of Laser absorption fraction, the Laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as Laser intensity are considered, as well as the dependence on Plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the comparison of simulation results with experimental observables. In particular, we address the question of surrogacy of today's experiments for the full-scale fast ignition problem.
-
efficient modeling of Laser Plasma Interactions in high energy density scenarios
arXiv: Plasma Physics, 2012Co-Authors: F Fiuza, Michael Marti, Ricardo Fonseca, L O Silva, J Tonge, Joshua May, W B MoriAbstract:We describe how a new framework for coupling a full-PIC algorithm with a reduced PIC algorithm has been implemented into the code OSIRIS. We show that OSIRIS with this new hybrid-PIC algorithm can efficiently and accurately model high energy density scenarios such as ion acceleration in Laser-solid Interactions and fast ignition of fusion targets. We model for the first time the full density range of a fast ignition target in a fully self-consistent hybrid-PIC simulation, illustrating the possibility of stopping the Laser generated electron flux at the core region with relatively high efficiencies. Computational speedups greater than 1000 times are demonstrated, opening the way for full-scale multi-dimensional modeling of high energy density scenarios and for the guiding of future experiments.
-
three dimensional simulations of Laser Plasma Interactions at ultrahigh intensities
IEEE Transactions on Plasma Science, 2011Co-Authors: F Fiuza, Ricardo Fonseca, L O Silva, J Tonge, Joshua May, W B MoriAbstract:Three-dimensional particle-in-cell simulations are used to investigate the interaction of ultrahigh-intensity Lasers (>;1020 W/cm-2) with matter at overcritical densities. Intense Laser pulses are shown to penetrate up to relativistic critical density levels and to be strongly self-focused during this process. The heat flux of the accelerated electrons is observed to have an annular structure when the Laser is tightly focused, showing that a large fraction of fast electrons is accelerated at an angle. These results shed light into the multidimensional effects present in Laser-Plasma Interactions of relevance to fast ignition of fusion targets and Laser-driven ion acceleration in Plasmas.
-
efficient modeling of Laser Plasma Interactions in high energy density scenarios
Plasma Physics and Controlled Fusion, 2011Co-Authors: F Fiuza, Michael Marti, Ricardo Fonseca, L O Silva, J Tonge, Joshua May, W B MoriAbstract:We describe how a new framework for coupling a full-particle-in-cell (PIC) algorithm with a reduced PIC algorithm has been implemented into the OSIRIS code. We show that OSIRIS, with this new hybrid-PIC algorithm, can efficiently and accurately model high energy density scenarios such as ion acceleration in Laser–solid Interactions and fast ignition of fusion targets. We model, for the first time, the full-density range of a fast ignition target in a fully self-consistent hybrid-PIC simulation, illustrating the possibility of stopping the Laser generated electron flux at the core region with relatively high efficiencies. Computational speedups greater than 1000 times are demonstrated, opening the way for full-scale multi-dimensional modeling of high energy density scenarios and the guiding of future experiments.
Tatsufumi Nakamura - One of the best experts on this subject based on the ideXlab platform.
-
high power γ ray flash generation in ultraintense Laser Plasma Interactions
Physical Review Letters, 2012Co-Authors: Tatsufumi Nakamura, James Koga, Timur Zh Esirkepov, Masaki Kando, G Korn, S V BulanovAbstract:When high-intensity Laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high power gamma ray flashes. The gamma-ray pulse duration and divergence are determined by the Laser pulse amplitude and by the Plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a gamma-ray flash with a tailored overcritical density target are found.
-
high power γ ray flash generation in ultraintense Laser Plasma Interactions
Physical Review Letters, 2012Co-Authors: Tatsufumi Nakamura, S V Bulanov, James Koga, Timur Zh Esirkepov, Masaki Kando, G KornAbstract:When high-intensity Laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high-power $\ensuremath{\gamma}$-ray flashes. The $\ensuremath{\gamma}$-ray pulse duration and divergence are determined by the Laser pulse amplitude and by the Plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a $\ensuremath{\gamma}$-ray flash with a tailored overcritical density target are found.
