K-shell spectroscopy of plasmas created by intense laser irradiation of micron-scale pyramid and sphere targets

Kneip, S.; Cho, B. I.; Symes, D. R.; Sumeruk, H. A.; Dyer, G.; Churina, I. V.; Belolipetski, A.; Henig, A.; Wehrhan, O.; Förster, E.; Donnelly, Thomas D.; Ditmire, T.

doi:10.1016/j.hedp.2007.10.002

Cited by 6 publications

(2 citation statements)

References 28 publications

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“…Aiming at enhancing the laser-plasma coupling, in recent years, a large effort was dedicated to testing targets containing micro-or nanostructures, which in many cases, have given evidence of a larger absorptivity of laser radiation and of an enhancement of bremsstrahlung or Kα x-ray yield, one to two orders of magnitude higher than that obtained by standard flat targets [1][2][3][4][5][6][7][8][9][10][11][12], and of a higher amount and temperature of the hot electrons generated [4,[13][14][15][16]. The mechanisms able to produce an enhancement of the absorptivity of a nanoor micro-structured target can be various, depending on the geometry and dimensions of the structures.…”

Section: Introductionmentioning

confidence: 99%

Investigation on laser–plasma coupling in intense, ultrashort irradiation of a nanostructured silicon target

Cristoforetti

Anzalone

Baffigi

et al. 2014

Plasma Phys. Control. Fusion

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One of the most interesting research fields in laser-matter interaction studies is the investigation of effects and mechanisms produced by nano-or micro-structured targets, mainly devoted to the enhancing of laser-target or laser-plasma coupling. In intense and ultra-intense laser interaction regimes, the observed enhancement of x-ray plasma emission and/or hot electron conversion efficiency is explained by a variety of mechanisms depending on the dimensions and shape of the structures irradiated. In the present work, the attention is mainly focused on the lowering of the plasma formation threshold which is induced by the larger absorptivity.Flat and nanostructured silicon targets were here irradiated with an ultrashort laser pulse, in the range 1 × 10 17 -2 × 10 18 W µm 2 cm −2 . The effects of structures on laser-plasma coupling were investigated at different laser pulse polarizations, by utilizing x-ray yield and 3/2ω harmonics emission. While the measured enhancement of x-ray emission is negligible at intensities larger than 10 18 W µm 2 cm −2 , due to the destruction of the structures by the amplified spontaneous emission (ASE) pre-pulse, a dramatic enhancement, strongly dependent on pulse polarization, was observed at intensities lower than ∼3.5 × 10 17 W µm 2 cm −2 . Relying on the three-halves harmonic emission and on the non-isotropic character of the x-ray yield, induced by the two-plasmon decay instability, the results are explained by the significant lowering of the plasma threshold produced by the nanostructures. In this view, the strong x-ray enhancement obtained by s-polarized pulses is produced by the interaction of the laser pulse with the preplasma, resulting from the interaction of the ASE pedestal with the nanostructures.

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Section: Introductionmentioning

confidence: 99%

Investigation on laser–plasma coupling in intense, ultrashort irradiation of a nanostructured silicon target

Cristoforetti

Anzalone

Baffigi

et al. 2014

Plasma Phys. Control. Fusion

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“…[5][6][7][8][9][10][11] A particular case is that of targets with a periodic surface modulation which allows the resonant coupling of the laser pulse with surface waves (SWs), 12 as it is widely used in plasmonics applications at low laser intensity. Most studies on structured targets and on SW-induced absorption [13][14][15][16] have been limited to relatively modest intensities (I 10 16 W/cm 2 ) because of the effects of "prepulses", typical of chirped pulse amplification (CPA) based laser systems, 17 which can destroy the surface structures before the interaction with the short intense pulse.…”

Section: Grating Targetsmentioning

confidence: 99%

Laser plasma proton acceleration experiments using foam-covered and grating targets

et al. 2013

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Experimental results are reported for two different configurations of laser driven ion acceleration using solid targets with a structured layer on the irradiated side. Two experimental campaigns have been performed exploiting the 100TW 25fs Ti:Sa UHI-100 laser pulse at CEA Saclay. The use of a double plasma mirror allowed a contrast ratio of > 1012 so that the structures of the front surface withstanded the prepulse. ”Foam” targets have been manufactured by depositing a 10 μm nanostructured carbon foam with an average density of 1-5 mg/cm3 on a 1 μm thick aluminium foil. At maximum focalization, corresponding to an intensity of 1019 W/cm2. the foam targets gave a maximum proton energy similar to the case of bare aluminium target (about 6 MeV). Reducing the intensity by moving the target from the best focus plane, the presence of the foam enhanced the maximum proton energy, obtaining about 1.5MeV vs. 500KeV with a target 500 μm from the best focus, corresponding to an intensity of 5 · 1016 W/cm2. ”Grating” targets have been manufactured by engraving thin mylar foils (0.9, 20 and 40 μm) with a regular modulation having 1.6 μm period and 0.5 μm depth. The periodicity of the grating corresponds to a resonant incident angle of 30 degrees for the excitation of surface waves. Considering a target of 20 micron and changing the angle of incidence from 10 to 45 degrees, a broad maximum in the proton energy cut-off was observed around the resonant angle. The proton energy cut-off was up to 5 MeV for a laser intensity of 1019 W/cm2. As suggested by numerical simulation, radiochromic films placed 300 degrees around the target showed a very intense electron signal suggesting the presence of a peak emission tangent to the target only in presence of the grating. The experiments have been supported by the LaserLAB EU access scheme

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Coherent transition radiation from thin targets irradiated by high intensity laser pulses

Bae

Cho

2015

Current Applied Physics

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K-shell spectroscopy of plasmas created by intense laser irradiation of micron-scale pyramid and sphere targets

Cited by 6 publications

References 28 publications

Investigation on laser–plasma coupling in intense, ultrashort irradiation of a nanostructured silicon target

Investigation on laser–plasma coupling in intense, ultrashort irradiation of a nanostructured silicon target

Laser plasma proton acceleration experiments using foam-covered and grating targets

Coherent transition radiation from thin targets irradiated by high intensity laser pulses

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