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Tsymbalov I, Gorlova D, Savel'ev A. Hybrid stimulated Raman scattering-two-plasmon decay instability and 3/2 harmonic in steep-gradient femtosecond plasmas. Phys Rev E 2020; 102:063206. [PMID: 33466029 DOI: 10.1103/physreve.102.063206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
We numerically study interaction of a very intense (I∼10^{17} to 5×10^{19}W/cm^{2}) femtosecond obliquely incident p-polarized laser pulse with a steep-gradient (L∼λ) plasma, i.e., within the conditions typical for modern experiments. It is shown that the hybrid stimulated Raman scattering-two-plasmon decay instability develops near the quarter-critical density surface and plays the dominant role for the plasma waves' excitation and energy absorption. The plasmons are excited as two wave packets confined near this surface with very wide ≈ω_{0}/c spatial spectra along its normal. Hence, phase-matching conditions for the 3/2 harmonic generation are fulfilled immediately and include the mechanism coming from the high harmonics of plasma waves. This mechanism has been proved experimentally by observing an additional 3/2 harmonic beam.
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Affiliation(s)
- I Tsymbalov
- Faculty of Physics and International Laser Center, Lomonosov Moscow State University, 119991, Moscow, Russia
- Institute for Nuclear Research of Russian Academy of Sciences, 117312, Moscow, Russia
| | - D Gorlova
- Faculty of Physics and International Laser Center, Lomonosov Moscow State University, 119991, Moscow, Russia
- Institute for Nuclear Research of Russian Academy of Sciences, 117312, Moscow, Russia
| | - A Savel'ev
- Faculty of Physics and International Laser Center, Lomonosov Moscow State University, 119991, Moscow, Russia
- Lebedev Physical Institute of Russian Academy of Sciences, 119991, Moscow, Russia
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2
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Lin J, Batson T, Nees J, Thomas AGR, Krushelnick K. Towards isolated attosecond electron bunches using ultrashort-pulse laser-solid interactions. Sci Rep 2020; 10:18354. [PMID: 33110187 PMCID: PMC7591899 DOI: 10.1038/s41598-020-75418-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/12/2020] [Indexed: 11/09/2022] Open
Abstract
We investigate MeV-level attosecond electron bunches from ultrashort-pulse laser-solid interactions through similarities between experimental and simulated electron energy spectra. We show measurements of the bunch duration and temporal structure from particle-in-cell simulations. The experimental observation of such bunches favors specular reflection direction when focusing the laser pulse onto a subwavelength boundary of thick overdense plasmas at grazing incidence. Particle-in-cell simulation further reveals that the attosecond duration is a result of ultra-thin ([Formula: see text]tenth of a micron) gaps of zero electromagnetic energy density in the modulated reflected radiation, while the bunching (locally peaked electron concentration) comes from the highly-directional electron angular distribution acquired by the electrons in a grazing incidence setup. To isolate a single electron bunch, we perform simulations using 1-cycle laser pulses and analyze the effect of carrier-envelop phase with particle tracking. The duration of the electron bunch can be further decreased by increasing the laser intensity and the focal spot size, while its direction can be changed by tuning the preplasma density gradient.
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Affiliation(s)
- Jinpu Lin
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Thomas Batson
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109, USA
| | - John Nees
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Alexander G R Thomas
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Karl Krushelnick
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI, 48109, USA
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3
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Cardenas DE, Ostermayr TM, Di Lucchio L, Hofmann L, Kling MF, Gibbon P, Schreiber J, Veisz L. Sub-cycle dynamics in relativistic nanoplasma acceleration. Sci Rep 2019; 9:7321. [PMID: 31086214 PMCID: PMC6513988 DOI: 10.1038/s41598-019-43635-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 04/28/2019] [Indexed: 11/26/2022] Open
Abstract
The interaction of light with nanometer-sized solids provides the means of focusing optical radiation to sub-wavelength spatial scales with associated electric field enhancements offering new opportunities for multifaceted applications. We utilize collective effects in nanoplasmas with sub-two-cycle light pulses of extreme intensity to extend the waveform-dependent electron acceleration regime into the relativistic realm, by using 106 times higher intensity than previous works to date. Through irradiation of nanometric tungsten needles, we obtain multi-MeV energy electron bunches, whose energy and direction can be steered by the combined effect of the induced near-field and the laser field. We identified a two-step mechanism for the electron acceleration: (i) ejection within a sub-half-optical-cycle into the near-field from the target at >TVm-1 acceleration fields, and (ii) subsequent acceleration in vacuum by the intense laser field. Our observations raise the prospect of isolating and controlling relativistic attosecond electron bunches, and pave the way for next generation electron and photon sources.
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Affiliation(s)
- D E Cardenas
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann Strasse 1, 85748, Garching, Germany
- Ludwig-Maximilian-Universität München, Am Couloumbwall 1, 85748, Garching, Germany
| | - T M Ostermayr
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann Strasse 1, 85748, Garching, Germany
- Ludwig-Maximilian-Universität München, Am Couloumbwall 1, 85748, Garching, Germany
| | - L Di Lucchio
- Forschungszentrum Jülich GmbH, Institute for Advanced Simulation, Jülich Supercomputing Centre, D-52425, Jülich, Germany
| | - L Hofmann
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann Strasse 1, 85748, Garching, Germany
- Ludwig-Maximilian-Universität München, Am Couloumbwall 1, 85748, Garching, Germany
| | - M F Kling
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann Strasse 1, 85748, Garching, Germany
- Ludwig-Maximilian-Universität München, Am Couloumbwall 1, 85748, Garching, Germany
| | - P Gibbon
- Forschungszentrum Jülich GmbH, Institute for Advanced Simulation, Jülich Supercomputing Centre, D-52425, Jülich, Germany
- Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, 3001, Heverlee, Belgium
| | - J Schreiber
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann Strasse 1, 85748, Garching, Germany
- Ludwig-Maximilian-Universität München, Am Couloumbwall 1, 85748, Garching, Germany
| | - L Veisz
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann Strasse 1, 85748, Garching, Germany.
- Department of Physics, Umeå University, SE-901 87, Umeå, Sweden.
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4
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Wen M, Salamin YI, Keitel CH. Electron acceleration by a radially-polarized laser pulse in a plasma micro-channel. OPTICS EXPRESS 2019; 27:557-566. [PMID: 30696140 DOI: 10.1364/oe.27.000557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 11/21/2018] [Indexed: 06/09/2023]
Abstract
Encouraged by recent advances in radially-polarized laser technology, simulations have been performed of electron acceleration by a tightly-focused, ultra-short pulse in a parabolic plasma micro-channel. Milli-joule laser pulses, generated at kHz repetition rates, are shown to produce electron bunches of MeV energy, pC charge, low emittance and low divergence. The pivotal role played by the channel length in controlling the process is demonstrated, and the roles of direct and wakefield acceleration are distinguished.
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5
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Mao JY, Rosmej O, Ma Y, Li MH, Aurand B, Gaertner F, Wang WM, Urbancic J, Schoenlein A, Zielbauer B, Eisenbarth U, Bagnoud V, Wagner F, Horst F, Syha M, Mathias S, Li YT, Aeschlimann M, Chen LM, Kuehl T. Energy enhancement of the target surface electron by using a 200 TW sub-picosecond laser. OPTICS LETTERS 2018; 43:3909-3912. [PMID: 30106914 DOI: 10.1364/ol.43.003909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/05/2018] [Indexed: 06/08/2023]
Abstract
One order of magnitude energy enhancement of the target surface electron beams with central energy at 11.5 MeV is achieved by using a 200 TW, 500 fs laser at an incident angle of 72° with a prepulse intensity ratio of 5×10-6. The experimental results demonstrate the scalability of the acceleration process to high electron energy with a longer (sub-picosecond) laser pulse duration and a higher laser energy (120 J). The total charge of the beam is 400±20 pC(E>2.7 MeV). Such a high orientation and mono-energetic electron jet would be a good method to solve the problem of the large beam divergence in fast ignition schemes and to increase the laser energy deposition on the target core.
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Abstract
Compact acceleration of a tightly collimated relativistic electron beam with high charge from a laser-plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from gases and vacuum laser acceleration from solids, often produce electron beams either with low charge or with large divergence angles. In this work, we report the generation of highly collimated electron beams with a divergence angle of a few degrees, nonthermal spectra peaked at the megaelectronvolt level, and extremely high charge (∼100 nC) via a powerful subpicosecond laser pulse interacting with a solid target in grazing incidence. Particle-in-cell simulations illustrate a direct laser acceleration scenario, in which the self-filamentation is triggered in a large-scale near-critical-density plasma and electron bunches are accelerated periodically and collimated by the ultraintense electromagnetic field. The energy density of such electron beams in high-Z materials reaches to [Formula: see text], making it a promising tool to drive warm or even hot dense matter states.
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Kleeschulte F, Hagmeister B, Hemmers D, Pretzler G. Fast electrons generated by quasistatic electric fields of a fs-laser-pulse-induced plasma. Phys Rev E 2018; 96:033201. [PMID: 29346907 DOI: 10.1103/physreve.96.033201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Indexed: 11/07/2022]
Abstract
We present a new acceleration mechanism for electrons taking place during the interaction of an ultrashort, nonrelativistic laser pulse with a plasma generated at the surface of a solid density target. In our experiments, the plasma is created by a laser pulse with femtosecond duration and an energy of about 1 mJ focused to intensities of above 10^{17}W/cm^{2}. We observe that the electron energies acquired by this mechanism exceed the ponderomotive potential of the laser by an order of magnitude. This result was reproduced and quantitatively confirmed by particle-in-cell simulations, which further revealed that the observed electron acceleration is based on quasistatic electric fields caused by the space charges of ponderomotively preaccelerated electrons. This acceleration process is examined in more detail by a simplified numerical model, which allows a qualitative explanation of the final electron energies.
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Affiliation(s)
- F Kleeschulte
- Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf
| | - B Hagmeister
- Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf
| | - D Hemmers
- Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf
| | - G Pretzler
- Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf
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8
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Feister S, Austin DR, Morrison JT, Frische KD, Orban C, Ngirmang G, Handler A, Smith JRH, Schillaci M, LaVerne JA, Chowdhury EA, Freeman RR, Roquemore WM. Relativistic electron acceleration by mJ-class kHz lasers normally incident on liquid targets. OPTICS EXPRESS 2017; 25:18736-18750. [PMID: 29041068 DOI: 10.1364/oe.25.018736] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/20/2017] [Indexed: 06/07/2023]
Abstract
We report observation of kHz-pulsed-laser-accelerated electron energies up to 3 MeV in the -klaser (backward) direction from a 3 mJ laser interacting at normal incidence with a solid density, flowing-liquid target. The electrons/MeV/s.r. >1 MeV recorded here using a mJ-class laser exceeds or equals that of prior super-ponderomotive electron studies employing lasers at lower repetition-rates and oblique incidence. Focal intensity of the 40-fs-duration laser is 1.5 · 1018 W cm-2, corresponding to only ∼80 keV electron ponderomotive energy. Varying laser intensity confirms electron energies in the laser-reflection direction well above what might be expected from ponderomotive scaling in normal-incidence laser-target geometry. This direct, normal-incidence energy spectrum measurement is made possible by modifying the final focusing off-axis-paraboloid (OAP) mirror with a central hole that allows electrons to pass, and restoring laser intensity through adaptive optics. A Lanex-based, optics-free high-acquisition rate (>100 Hz) magnetic electron-spectrometer was developed for this study to enable shot-to-shot statistical analysis and real-time feedback, which was leveraged in finding optimal pre-plasma conditions. 3D Particle-in-cell simulations of the interaction show qualitative super-ponderomotive spectral agreement with experiment. The demonstration of a high-repetition-rate, high-flux source containing >MeV electrons from a few-mJ, 40 fs laser and a simple liquid target encourages development of future ≥kHz-repetition, fs-duration electron-beam applications.
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9
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Salehi F, Goers AJ, Hine GA, Feder L, Kuk D, Miao B, Woodbury D, Kim KY, Milchberg HM. MeV electron acceleration at 1 kHz with <10 mJ laser pulses. OPTICS LETTERS 2017; 42:215-218. [PMID: 28081077 DOI: 10.1364/ol.42.000215] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/30/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate laser-driven acceleration of electrons to MeV-scale energies at 1 kHz repetition rate using <10 mJ pulses focused on near-critical density He and H2 gas jets. Using the H2 gas jet, electron acceleration to ∼0.5 MeV in ∼10 fC bunches was observed with laser pulse energy as low as 1.3 mJ. Increasing the pulse energy to 10 mJ, we measure ∼1 pC charge bunches with >1 MeV energy for both He and H2 gas jets.
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10
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Bocoum M, Thévenet M, Böhle F, Beaurepaire B, Vernier A, Jullien A, Faure J, Lopez-Martens R. Anticorrelated Emission of High Harmonics and Fast Electron Beams From Plasma Mirrors. PHYSICAL REVIEW LETTERS 2016; 116:185001. [PMID: 27203328 DOI: 10.1103/physrevlett.116.185001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Indexed: 06/05/2023]
Abstract
We report for the first time on the anticorrelated emission of high-order harmonics and energetic electron beams from a solid-density plasma with a sharp vacuum interface-plasma mirror-driven by an intense ultrashort laser pulse. We highlight the key role played by the nanoscale structure of the plasma surface during the interaction by measuring the spatial and spectral properties of harmonics and electron beams emitted by a plasma mirror. We show that the nanoscale behavior of the plasma mirror can be controlled by tuning the scale length of the electron density gradient, which is measured in situ using spatial-domain interferometry.
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Affiliation(s)
- Maïmouna Bocoum
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Maxence Thévenet
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Frederik Böhle
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Benoît Beaurepaire
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Aline Vernier
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Aurélie Jullien
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Jérôme Faure
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
| | - Rodrigo Lopez-Martens
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 bd des Maréchaux, 91762 Palaiseau cedex, France
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11
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Bocoum M, Böhle F, Vernier A, Jullien A, Faure J, Lopez-Martens R. Spatial-domain interferometer for measuring plasma mirror expansion. OPTICS LETTERS 2015; 40:3009-3012. [PMID: 26125354 DOI: 10.1364/ol.40.003009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a practical spatial-domain interferometer for characterizing the electronic density gradient of laser-induced plasma mirrors with sub-30-femtosecond temporal resolution. Time-resolved spatial imaging of an intensity-shaped pulse reflecting off an expanding plasma mirror induced by a time-delayed pre-pulse allows us to measure characteristic plasma gradients of 10-100 nm with an expansion velocity of 10.8 nm/ps. Spatial-domain interferometry (SDI) can be generalized to the ultrafast imaging of nm to μm size laser-induced phenomena at surfaces.
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12
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Dollar F, Cummings P, Chvykov V, Willingale L, Vargas M, Yanovsky V, Zulick C, Maksimchuk A, Thomas AGR, Krushelnick K. Scaling high-order harmonic generation from laser-solid interactions to ultrahigh intensity. PHYSICAL REVIEW LETTERS 2013; 110:175002. [PMID: 23679739 DOI: 10.1103/physrevlett.110.175002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Indexed: 06/02/2023]
Abstract
Coherent x-ray beams with a subfemtosecond (<10(-15) s) pulse duration will enable measurements of fundamental atomic processes in a completely new regime. High-order harmonic generation (HOHG) using short pulse (<100 fs) infrared lasers focused to intensities surpassing 10(18) W cm(-2) onto a solid density plasma is a promising means of generating such short pulses. Critical to the relativistic oscillating mirror mechanism is the steepness of the plasma density gradient at the reflection point, characterized by a scale length, which can strongly influence the harmonic generation mechanism. It is shown that for intensities in excess of 10(21) W cm(-2) an optimum density ramp scale length exists that balances an increase in efficiency with a growth of parametric plasma wave instabilities. We show that for these higher intensities the optimal scale length is c/ω0, for which a variety of HOHG properties are optimized, including total conversion efficiency, HOHG divergence, and their power law scaling. Particle-in-cell simulations show striking evidence of the HOHG loss mechanism through parametric instabilities and relativistic self-phase modulation, which affect the produced spectra and conversion efficiency.
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Affiliation(s)
- F Dollar
- Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA
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13
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Tian Y, Liu J, Wang W, Wang C, Deng A, Xia C, Li W, Cao L, Lu H, Zhang H, Xu Y, Leng Y, Li R, Xu Z. Electron emission at locked phases from the laser-driven surface plasma wave. PHYSICAL REVIEW LETTERS 2012; 109:115002. [PMID: 23005638 DOI: 10.1103/physrevlett.109.115002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 05/31/2012] [Indexed: 06/01/2023]
Abstract
By irradiating a flat Al target with femtosecond laser pulses at moderate intensities of ∼10(17) W/cm(2), we obtained stable collimated quasimonoenergetic electrons in the specular direction but deviated somewhat toward the target normal. An associated local minimum located on the other side of the specular direction seems to indicate that the peak actually results from the deflection of the collimated electrons from their initial ejection direction. We have proposed a two-step model in which some laser-accelerated electrons are able to leave the plasma in a narrow phase-locked window of the moving wave interference pattern, and are then steered toward the target normal by the ponderomotive force of the interference field. The periodic repetition of the electron emission leads to a pulse train of collimated quasimonoenergetic electrons with subcycle duration.
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Affiliation(s)
- Ye Tian
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
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14
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Sarkisov GS, Ivanov VV, Leblanc P, Sentoku Y, Yates K, Wiewior P, Chalyy O, Astanovitskiy A, Bychenkov VY, Jobe D, Spielman RB. Propagation of a laser-driven relativistic electron beam inside a solid dielectric. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:036412. [PMID: 23031038 DOI: 10.1103/physreve.86.036412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 06/09/2012] [Indexed: 06/01/2023]
Abstract
Laser probe diagnostics: shadowgraphy, interferometry, and polarimetry were used for a comprehensive characterization of ionization wave dynamics inside a glass target induced by a laser-driven, relativistic electron beam. Experiments were done using the 50-TW Leopard laser at the University of Nevada, Reno. We show that for a laser flux of ∼2 × 10(18) W/cm2 a hemispherical ionization wave propagates at c/3 for 10 ps and has a smooth electron-density distribution. The maximum free-electron density inside the glass target is ∼2 × 10(19) cm-3, which corresponds to an ionization level of ∼0.1%. Magnetic fields and electric fields do not exceed ∼15 kG and ∼1 MV/cm, respectively. The electron temperature has a hot, ringlike structure with a maximum of ∼0.7 eV. The topology of the interference phase shift shows the signature of the "fountain effect", a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields driven by laser. The very low ionization observed after the laser heating pulse suggests a fast recombination on the sub-ps time scale.
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Affiliation(s)
- G S Sarkisov
- Raytheon Ktech, 1300 Eubank Blvd, Albuquerque, New Mexico 87123, USA
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15
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Mao JY, Chen LM, Ge XL, Zhang L, Yan WC, Li DZ, Liao GQ, Ma JL, Huang K, Li YT, Lu X, Dong QL, Wei ZY, Sheng ZM, Zhang J. Spectrally peaked electron beams produced via surface guiding and acceleration in femtosecond laser-solid interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:025401. [PMID: 22463272 DOI: 10.1103/physreve.85.025401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 01/04/2012] [Indexed: 05/31/2023]
Abstract
Highly collimated MeV electron beam guiding has been observed along the target surface following the interaction of bulk target irradiation by femtosecond laser pulses at relativistic intensities. The beam quality is shown to depend critically on the laser contrast: With a ns prepulse, the generated electron beam is well concentrated and intense, while a high laser contrast produces divergent electron beams. In the case of large preplasma scale lengths, tunable guiding and acceleration of the target surface electrons is achieved by changing the laser incident angle. By expanding the preplasma scale length to several hundred micrometers, we obtained MeV spectrum-peaked electron beams with a 100 pC per laser pulse and divergence angles of only 3°. This technique suggests a stable method of injection of elections into a variety of accelerator designs.
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Affiliation(s)
- J Y Mao
- Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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