On the hot electrons and K α x-rays generation in the intense laser interaction with silver targets

Published on Nov 1, 2016
· DOI :10.1088/1742-6596/774/1/012112
O F Kostenko1
Estimated H-index: 1
(RAS: Russian Academy of Sciences),
N. E. Andreev10
Estimated H-index: 10
(RAS: Russian Academy of Sciences)
+ 1 AuthorsA Schönlein1
Estimated H-index: 1
(Goethe University Frankfurt)
Sources
Abstract
Intensity dependence of the conversion efficiency of laser energy into the energy of hot electrons is determined with the aid of measurements and modeling of Kα-photon yield from silver targets irradiated by relativistically intense subpicosecond laser pulses. We take into account intensity dependence of the effective hot electron temperature assuming the Wilks' scaling. The measurements reveal approximately the same values of the Kα yield from a silver foil of 10 μm thickness, attached onto aluminium or plexiglass substrates, at the intensities about 1018 W/cm2 and 2 × 1019 W/cm2. Intensity dependence of the Kα yield from the silver foil, calculated using determined conversion efficiency of laser energy into the energy of hot electrons, is in agreement with the measurements.
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#1L. P. Pugachev (RAS: Russian Academy of Sciences)H-Index: 4
#2N. E. Andreev (RAS: Russian Academy of Sciences)H-Index: 10
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Abstract Optimization study for future experiments on interaction of petawatt laser pulses with foam targets was done by 3D PIC simulations. Densities in the range 0.5 n c – n c and thicknesses in the range 100 – 500 μ m of the targets were considered corresponding to those which are currently available. It is shown that heating of electrons mainly occurs under the action of the ponderomotive force of a laser pulse in which amplitude increases up to three times because of self-focusing effect in...
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#1Nikolay Andreev (JINR: Joint Institute for Nuclear Research)H-Index: 22
#2L. P. PugachevH-Index: 1
Last. Pavel LevashovH-Index: 30
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Generation of hot electrons at grazing incidence of a subpicosecond relativistic-intense laser pulse onto a plane solid target is analyzed for the parameters of petawatt class laser systems. We study preplasma formation on the surface of solid aluminum targets produced by laser prepulses with a different time structure. For modeling of the preplasma dynamics, we use a wide-range two-temperature hydrodynamic model. As a result of simulations, the preplasma expansion under the action of the laser ...
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We have developed a model to calculate the yield of the characteristic X-ray radiation from a foil, taking into account the dependence of the average energy and the number of hot electrons on the intensity of the laser pulse, the self-absorption of X-rays and the effect of refluxing of hot electrons. The yield of Kα radiation from a silver foil is optimised at relativistic intensities. A method is proposed for diagnosing the effect of electron refluxing, which greatly increases the yield of Kα r...
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#1Mark N. Quinn (University of Strathclyde)H-Index: 23
#2Xiaohui Yuan (CAS: Chinese Academy of Sciences)H-Index: 20
Last. Paul McKennaH-Index: 55
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The propagation of fast electrons produced in the interaction of relativistically intense, picosecond laser pulses with solid targets is experimentally investigated using K-alpha emission as a diagnostic. The role of fast electron refluxing within the target, which occurs when the electrons are reflected by the sheath potentials formed at the front and rear surfaces, is elucidated. The targets consist of a Cu fluorescence layer of fixed thickness at the front surface backed with a propagation la...
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#1Paul NeumayerH-Index: 26
#2Bastian AurandH-Index: 15
Last. D. Zimmer (University of Mainz)H-Index: 7
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A study of the contribution of refluxing electrons in the production of K-alpha radiation from high-intensity laser irradiated thin targets has been performed. Thin copper foils both freestanding, and backed by a thick substrate were irradiated with laser pulses of energies around 100 J at intensities ranging from below 1017 to above 1019 W/cm2. At high laser intensities we find a strong reduction in the K-alpha yield from targets backed by the substrate. The observed yield reduction is in good ...
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#1Vincent BagnoudH-Index: 25
#2Bastian Aurand (University of Mainz)H-Index: 15
Last. K. Witte (LMU: Ludwig Maximilian University of Munich)H-Index: 1
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At the Helmholtz center GSI, PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) has been commissioned for operation in stand-alone mode and, in combination with ions accelerated up to an energy of 13 MeV/u by the heavy ion accelerator UNILAC. The combination of PHELIX with the heavy-ion beams available at GSI enables a large variety of unique experiments. Novel research opportunities are spanning from the study of ion–matter interaction, through challenging new experiments in atomic p...
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The Bremsstrahlung and K-shell emission from 1×1×1 mm3 planar targets irradiated by a short-pulse 3×1018–8×1019 W/cm2 laser were measured. The Bremsstrahlung was measured using a filter stack spectrometer with spectral discrimination up to 500 keV. K-shell emission was measured using a single photon counting charge coupled device. From Monte Carlo modeling of the target emission, conversion efficiencies into 1–3 MeV electrons of 3%–12%, representing 20%–40% total conversion efficiencies, were in...
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#2Brian MaddoxH-Index: 19
Last. Erik BrambrinkH-Index: 25
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We have developed 17 keV to 75 keV 1-dimensional and 2-dimensional high-resolution ( 10{sup 17} W/cm{sup 2}. We have achieved high resolution point projection 1-dimensional and 2-dimensional radiography using micro-foil and micro-wire targets attached to low-Z substrate materials. The micro-wire size was 10 {micro}m x 10 {micro}m x 300 {micro}m on a 300 {micro}m x 300 {micro}m x 5 {micro}m CH substrate. The radiography performance was demonstrated using the Titan laser at LLNL. We observed that ...
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#1J.F. MyattH-Index: 33
#2W. TheobaldH-Index: 29
Last. R. W. ShortH-Index: 33
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The modeling of petawatt laser-generated hot electrons in mass-limited solid-foil-target interactions at “relativistic” laser intensities is presented using copper targets and parameters motivated by recent experiments at the Rutherford Appleton Laboratory Petawatt and 100-TW facilities [Theobald et al., Phys. Plasmas 13, 043102 (2006)]. Electron refluxing allows a unique determination of the laser-electron conversion efficiency and a test with simulations. Good agreement between experiments and...
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#7T Goldsack (Atomic Weapons Establishment)H-Index: 2
The characteristics of 22–40keV Kα x-ray sources are measured. These high-energy sources are produced by 100TW and petawatt high-intensity lasers and will be used to develop and implement workable radiography solutions to probe high-Z and dense materials for the high-energy density experiments. The measurements show that the Kα source size from a simple foil target is larger than 60μm, too large for most radiography applications. The total Kα yield is independent of target thicknesses, verifying...
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Cited By1
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#1O F Kostenko (JINR: Joint Institute for Nuclear Research)H-Index: 2
#2N. E. AndreevH-Index: 10
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A two-temperature hot electron energy distribution has been revealed by modeling of bremsstrahlung emission, measured by the radiation attenuation and half-shade methods, and Kα emission from a massive silver cylinder irradiated by a subpicosecond s-polarized laser pulse with a peak intensity of about 2 × 1019 W/cm2. To deduce parameters of the hot electron spectrum, we have developed semi-analytical models of generation and measurements of the x-rays. The models are based on analytical expressi...
Source
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