Scheme and photo of the experimental setup: (1) laser pulse from a Ti:Sa laser system, (2) liquid metal target, (3) vacuum chamber, (4) resistive heater, (5) x-ray detectors, and (6) x-ray band filters.
Spectrum of x-ray radiation from laser-produced plasma in the case of a high nanosecond contrast ratio (∼106).
(a) X-ray yield above 3 keV and (b) average hot-electron energy as a function of the intensity contrast ratio C for p- and s-polarized laser light: the error bars show the standard deviation of the average values. The thin solid lines in panel (b) display the lower and upper limits of the mean energy distribution Ehot at half maximum in a series of 100 laser shots. The inset in (b) shows the distribution of mean hot-electron energy Ehot obtained for p-polarization of the laser pulse and the contrast ∼50.
Dependence of the ratio R of the Ga Kα line intensity to bremsstrahlung intensity (above 5 keV) on the contrast ratio C.
Experimental scheme for optical shadowgraphy: (1) beam splitter (silica wedge), (2) second harmonic crystal, (3) moving mirror (delay line), (4) focusing objective, (5) target with heater, (6) plasma imaging objective, and (7) CCD camera.
Images of plasma plume from the melted Ga target obtained at different time delays after the action of an arbitrary weak femtosecond laser pulse. (a)–(e) probe pulse illuminating plasma plume propagates in the same plane with the main pulse, (f) probe pulse propagates in transverse direction relative to the main pulse. The white arrow indicates the laser radiation direction.
Electron density profiles for liquid Al (a) at different delays from plasma creation and laser pulse fluence of 5 J/cm2 (deposited fluence of 0.5 J/cm2) and (b) at fluences varying from 0.5 to 50 J/cm2 and a delay of 10 ns. Panel (b) also contains the plot for a solid Al target at the deposited fluence of 0.5 J/cm2.
Electron density distributions in the laser incidence plane for the targets used in three-dimensional PIC simulations: (a) foil target, (b) foil target with microjets. The inset shows a pure jet target. The laser pulse propagates in the X direction from the left.
Electron energy spectrum from a foil target with microjets (solid line), without jets (dashed line), and for the jet-only target (dotted line). All the curves are normalized to the total number of particles.
(a) The longitudinal electric field averaged over the laser light period at the instant t = 17 fs, and (b) the distribution of hot electrons at the same instant. The vectors correspond to the magnitudes and directions of the electron momentum.
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