Ion-expansion energy spectra correlated to laser plasma parameters

Olsen, J. N.; Kuswa, G. W.; Jones, E. D.

doi:10.1063/1.1662550

Cited by 51 publications

(13 citation statements)

References 9 publications

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“…However, a large portion of the incident light is reflected from the critical density layer of the plasma (where the laser frequency becomes equal to the plasma frequency and the laser cannot propagate deeper into the plasma) and only a small percentage of the laser energy is transferred to the electrons and even lesser to the ions 11 . In typical laser-solid experiments, the vacuum level of the experimental chamber (typically 10 −5 Torr) is not too high, such that the water vapour and/or hydrocarbons adsorbed on the target surface invariably generate ion species such as H + , C q + , O q + ( q = charge state) in addition to the metal ions from the bulk target 12 13 . Protons, being the lightest of the ions, are easily detected and are almost exclusively studied to probe the acceleration physics.…”

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confidence: 99%

Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces

Dalui

Wang

Trivikram

et al. 2015

Sci Rep

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High-intensity ultrashort laser pulses focused on metal targets readily generate hot dense plasmas which accelerate ions efficiently and can pave way to compact table-top accelerators. Laser-driven ion acceleration studies predominantly focus on protons, which experience the maximum acceleration owing to their highest charge-to-mass ratio. The possibility of tailoring such schemes for the preferential acceleration of a particular ion species is very much desired but has hardly been explored. Here, we present an experimental demonstration of how the nanostructuring of a copper target can be optimized for enhanced carbon ion acceleration over protons or Cu-ions. Specifically, a thin (≈0.25 μm) layer of 25–30 nm diameter Cu nanoparticles, sputter-deposited on a polished Cu-substrate, enhances the carbon ion energy by about 10-fold at a laser intensity of 1.2×1018 W/cm2. However, particles smaller than 20 nm have an adverse effect on the ion acceleration. Particle-in-cell simulations provide definite pointers regarding the size of nanoparticles necessary for maximizing the ion acceleration. The inherent contrast of the laser pulse is found to play an important role in the species selective ion acceleration.

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confidence: 99%

Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces

Dalui

Wang

Trivikram

et al. 2015

Sci Rep

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“…Barabash et al, 17 Olsen et al, 18 and W. Mróz et al 19 presented TP data about ions accelerated by microsecond, nanosecond, and picosecond lasers, respectively. The most striking publication was the detection of quasimonoenergetic ions produced by the interaction of a high-intensity laser with structured thin titanium foils by Schwoerer et al 20 Section II describes the working principle and the setup of the TP and gives a comparison to other detectors often used.…”

Section: Introductionmentioning

confidence: 99%

Development and calibration of a Thomson parabola with microchannel plate for the detection of laser-accelerated MeV ions

Harres

Schollmeier

Brambrink³

et al. 2008

Review of Scientific Instruments

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This article reports on the development and application of a Thomson parabola (TP) equipped with a (90x70) mm(2) microchannel-plate (MCP) for the analysis of laser-accelerated ions, produced by a high-energy, high-intensity laser system. The MCP allows an online measurement of the produced ions in every single laser shot. An electromagnet instead of permanent magnets is used that allows the tuning of the magnetic field to adapt the field strength to the analyzed ion species and energy. We describe recent experiments at the 100 TW laser facility at the Laboratoire d'Utilization des Lasers Intenses (LULI) in Palaiseau, France, where we have observed multiple ion species and charge states with ions accelerated up to 5 MeV/u (O(+6)), emitted from the rear surface of a laser-irradiated 50 microm Au foil. Within the experiment the TP was calibrated for protons and for the first time conversion efficiencies of MeV protons (2-13 MeV) to primary electrons (electrons immediately generated by an ion impact onto a surface) in the MCP are presented.

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“…Shearer et al 98 irradiated plastic targets with a Nd:glass laser at $2 Â 10 14 W/cm 2 and found 100-keV x rays with a temperature T H $ 50 keV; they suggested the parametric decay instability as the cause. Olsen et al 99 reported 200-to 800-keV x rays, also from a Nd:glass laser. Ehler 100 observed proton energies reaching $100 keV at a CO 2 laser irradiance up to 10 14 W/cm 2 .…”

Section: B Suprathermal Electronsmentioning

confidence: 99%

Direct-drive inertial confinement fusion: A review

et al. 2015

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The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

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Ion-expansion energy spectra correlated to laser plasma parameters

Cited by 51 publications

References 9 publications

Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces

Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces

Development and calibration of a Thomson parabola with microchannel plate for the detection of laser-accelerated MeV ions

Direct-drive inertial confinement fusion: A review

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