Absorption of high-intensity subpicosecond lasers on solid density targets

Denavit, J.

doi:10.1103/physrevlett.69.3052

Cited by 319 publications

(204 citation statements)

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“…Understanding absorption of laser radiation at high intensities, production of MeV electrons, and energy transport with associated isochoric heating is crucial to the development of these applications. The formation of a hot surface layer by sub ps laser irradiation at intensities >10 19 Wcm ÿ2 has been reported elsewhere [4,5]. At such high intensities, the collisional range of the MeV electrons produced by absorption of the laser radiation is more than 2 orders of magnitude greater than the thickness of the heated layer and we are concerned with explaining the physics of this heating.…”

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confidence: 99%

“…Strong heating occurs only over the first 0:3 m in the solid. The longitudinal ion phase space shows the signature of a light pressure-driven ion shock [18][19][20] with a group of ions moving at the flow velocity (0.015 c) behind the shock and a smaller group of reflected ions at twice that velocity. The electron number density shows the compression by the shock.…”

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confidence: 99%

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Laser Heating of Solid Matter by Light-Pressure-Driven Shocks at Ultrarelativistic Intensities

Akli

Hansen²,

Kemp³

et al. 2008

Phys. Rev. Lett.

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The heating of solid targets irradiated by 5 10 20 Wcm ÿ2 , 0.8 ps, 1:05 m wavelength laser light is studied by x-ray spectroscopy of the K-shell emission from thin layers of Ni, Mo, and V. A surface layer is heated to 5 keV with an axial temperature gradient of 0:6 m scale length. Images of Ni Ly show the hot region has 25 m diameter. These data are consistent with collisional particle-in-cell simulations using preformed plasma density profiles from hydrodynamic modeling which show that the >100 G bar light pressure compresses the preformed plasma and drives a shock into the solid, heating a thin layer.

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confidence: 99%

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confidence: 99%

Laser Heating of Solid Matter by Light-Pressure-Driven Shocks at Ultrarelativistic Intensities

Akli

Hansen²,

Kemp³

et al. 2008

Phys. Rev. Lett.

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“…Particles are trapped in the associated electrostatic potential, which steepens and eventually reaches a quasisteady-state collisionless electrostatic shock. Most of the theoretical work dates back to the 1970s [9-13] relying on the pseudo-Sagdeev potential [14] and progress has been mainly triggered by kinetic simulations [15][16][17][18].The short formation time scales and the one dimensionality of the problem make it easily accessible with theory and computer simulations. However, long time shock evolution was often one dimensional or electrostatic codes were used, and the role of electromagnetic modes was mostly neglected.…”

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Electromagnetic Field Generation in the Downstream of Electrostatic Shocks Due to Electron Trapping

et al. 2014

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A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ∼10 4 ω −1 pe . Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laserplasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock. Collisionless shocks have been studied for many decades, mainly in the context of space and astrophysics [1][2][3][4]. Recently, shock acceleration raised significant interest in the quest for a laser-based ion acceleration scheme due to an experimentally demonstrated high beam quality [5][6][7][8].Interpenetrating plasma slabs of hot electrons and cold ions are acting to set up the electrostatic fields via longitudinal plasma instabilities. The lighter electrons leaving the denser regions are held back by the electric fields, which pull the ions. Particles are trapped in the associated electrostatic potential, which steepens and eventually reaches a quasisteady-state collisionless electrostatic shock. Most of the theoretical work dates back to the 1970s [9-13] relying on the pseudo-Sagdeev potential [14] and progress has been mainly triggered by kinetic simulations [15][16][17][18].The short formation time scales and the one dimensionality of the problem make it easily accessible with theory and computer simulations. However, long time shock evolution was often one dimensional or electrostatic codes were used, and the role of electromagnetic modes was mostly neglected. More advanced multidimensional simulations have shown the importance of electromagnetic modes also in this context, due to transverse modes which are excited on the ion time scale [19,20]. We show that in the case of very high electron temperatures associated with the formation of electrostatic shocks [21], electromagnetic modes become important on electron time scales, creating strong magnetic fields in the downstream of the shock.With the increase in laser energy and intensity, the possibility to drive electrostatic shocks has become important for laboratory experiments of electrostatic shocks. Recent laser-driven shock experiments showed the appearance of an electromagnetic field structure [22][23][24], which was attributed to the ion-filamentation instability [25] that evolves on time scales of ten thousands of the inverse electron plasma frequency, ω −1 pe . As a main outcome of this Letter, we show that these structures can already be seeded and produced on tens of ω −1 pe and remain in a quasisteady state over t...

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“…On the other hand, in the case of thick enough targets, i.e., when laser < l foil = , this is the so-called collisionless shock acceleration at the front side of the target as analyzed in Refs. [10,19,20].…”

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confidence: 99%