High-Energy Ion Expansion in Laser-Plasma Interactions

Decoste, R.; Ripin, B. H.

doi:10.1103/physrevlett.40.34

Cited by 62 publications

(23 citation statements)

References 11 publications

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“…The oxygen ionization stages can be strongly affected by the recombination of the ions during acceleration and propagation to the detector through the interaction chamber and spectrometer. 18,19 It has been observed that the signal from O 7+ and O 8+ ions disappears, if the pressure in the spectrometer grows up to 2 ϫ 10 −4 mbar ͑Ref. 20͒.…”

Section: Resultsmentioning

confidence: 98%

Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse

et al. 2006

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The paper presents an analytical model and particle-in-cell simulations of the quasi-mono-energetic ion acceleration by an intense laser pulse in a multispecies target and the corresponding experimental observations. Homogeneous and heterogeneous targets are considered, and it is shown that the formation of the energy spectrum proceeds in three stages: (1) the initial light ion acceleration in the sheath electric field, (2) the ion species separation followed by the electrostatic shock formation, and (3) the interaction of spatially separated ion bunches accompanied by electron cooling. The field ionization of heavy ions and interaction between the heavy and light species play an important role in the formation and preservation of the energy spectrum of light ions. The simulation results are compared with the theoretical predictions and the experiments.

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Section: Resultsmentioning

confidence: 98%

Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse

et al. 2006

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“…Most previous experiments [5] measured the ion energies with Faraday cups which cannot distinguish between different ion species. Hydrogen ions with energies up to 180 keV have been reported [7] with a laser intensity of 10 16 W͞cm 2 , however, this was performed with a single laser beam on an overdense target, so it is difficult to separate out the hot ions produced in the underdense plasma from those produced by interaction of the laser pulse with the critical density surface.…”

Section: Fast Ion Production By Laser Filamentation In Laser-producedmentioning

confidence: 99%

Fast Ion Production by Laser Filamentation in Laser-Produced Plasmas

et al. 1996

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Production of protons with energies of ϳ20 keV have been observed to originate from the interaction of a high intensity laser with a preformed underdense plasma. The energy and distribution of ions are explained by acceleration by the ponderomotive force resulting from filamentation. [S0031-9007(96) PACS numbers: 52.40.Nk, 52.35.Fp, 52.35.Mw, 52.50.Jm The propagation of high intensity laser pulses through plasmas has been studied for a number of years. Predictions of laser-target interactions for inertial confinement fusion (ICF) applications, for example, will change if the laser intensity is sufficiently high to form density channels via the ponderomotive force or exceed the threshold for the filamentation instability. Numerous theoretical works have studied filamentation at low intensities [1]. Presently nonlinear fluid simulations [2,3] are being used to simulate high intensities (.10 16 W͞cm 2 ) which can occur in ICF applications; it is important to experimentally verify their accuracy in this new regime. Experimental measurement of filamented density channels formed at high intensities is extraordinarily difficult via imaging techniques due to their small transverse dimensions (ϳ10 mm). On the other hand, as shown first in particle-in-cell simulations [4] and in the fluid simulations [2,3], intense laser pulses can produce a large transverse ponderomotive force which can accelerate ions to high velocities (y i ¿ c s , the sound speed) which can then be used to diagnose the laser intensity in the filament. Although the energy distributions of ions ejected from laser-plasma interactions have been studied extensively in the past [5], these ions have generally been accelerated by the ambipolar potential created by hot electrons which can be produced by processes such as resonance absorption [6].In this Letter, we describe the results of an experiment in which ion velocity distributions are observed which are produced when a focused laser beam interacts with preformed underdense plasmas. As we vary the incident laser intensity, the production of hot ions is correlated with the onset of filamentation. The separation of the plasma formation from the hot ion generation allows us to distinguish between the ion distributions from each process and to choose the maximum electron density reached by the interaction beam. We have observed proton energies of ϳ20 keV for incident intensities of 5 3 10 16 W͞cm 2 , a laser wavelength of 1.064 mm, and densities of 0.25n c , where n c is the critical density at which the incident laser frequency equals the electron plasma frequency. This result is confirmed by twodimensional fluid simulations, which show that the ion ejection is localized spatially to the filamentation region, and by particle-in-cell simulations which accurately predict the observed ion energies.A simple estimate shows that filamentation can easily produce ions with energies much greater than the initial thermal ion energy. We equate the kinetic energy of the ion to the potential energy set up by the ponde...

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“…The hot electrons also set up a potential difference that accelerates ions from the freely expanding plasma. [25][26][27][28] The laser pulse shining on a nanotube coated surface experiences a local electric field ͑and hence light intensity͒ amplification, simply understood to be due to the well known "lightning rod" effect. 5 Recently, this enhancement has been modeled in great detail and simple scaling laws have emerged.…”

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confidence: 99%

Bright, low debris, ultrashort hard x-ray table top source using carbon nanotubes

et al. 2011

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International audienceWe demonstrate that carbon nanotube coated surfaces produce two orders of magnitude brighter hard x-ray emission, in laser produced plasmas, than planar surfaces. It is accompanied by three orders of magnitude reduction in ion debris which is also low Z and nontoxic. The increased emission is a direct consequence of the enhancement in local fields and is via the simple and well known "lightning rod" effect. We propose that this carbon nanotube hard x-ray source is a simple, inexpensive, and high repetition rate hard x-ray point source for a variety of applications in imaging, lithography, microscopy, and material processing

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High-Energy Ion Expansion in Laser-Plasma Interactions

Cited by 62 publications

References 11 publications

Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse

Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse

Fast Ion Production by Laser Filamentation in Laser-Produced Plasmas

Bright, low debris, ultrashort hard x-ray table top source using carbon nanotubes

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