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In a proof of principle experiment using the LULI 100-TW laser facility ELFIE, we have demonstrated high spectral and spatial resolution of Kα volume radiation induced by energetic electrons generated by irradiating solid Cu targets with visible (0.53 µm) 350 fs laser pulses. Employing an x-ray spectrometer equipped with the spherically bent crystal of quartz (502) and with an image plate, single shot Cu-Kα radiation was recorded in first-order reflection allowing for a geometrical mapping of the emission induced by hot electrons with a spatial resolution down to 30 µm. The simultaneously achieved high spectral resolution permitted the identification of asymmetries in the Kα1-group emission profile. Data from the shot in which a part of the laser beam was incident at grazing angle to the target surface show a signature of enhanced lateral transport of energetic electrons. [ABSTRACT FROM AUTHOR]

Abstract: High resolution, spatially resolved spectroscopy is used to study the interaction of a short 3.4ps pulse laser at intensities between 1014 and 1017 W/cm2. The detailed lines shapes show a series of regular intensity modulations, or dips, across the spectral line. We present the analysis of the helium-like emission from these aluminium plasmas, and compare the Heβ transition to calculation. Assuming the intensity dips result from the interaction of quasi-monochromatic electric field of a strong plasma wave, we are able to infer the field strengths present and electron density. This suggests that the intensity dips are driven by the strong growth of laser-driven parametric instabilities at quarter critical density. The development of high resolution spectroscopy for the interpretation of parametric driven instabilities in short pulse laser-produced plasma is discussed. [Copyright &y& Elsevier]

Abstract: Precise X-ray spectroscopic investigation of the colliding plasmas produced at single-side laser-irradiated double-foil Al/Mg targets is reported. The spatially resolved, time-integrated line spectra of the Al Lyα group were measured using a high-dispersion vertical-geometry Johann spectrometer. The X-ray spectra were evaluated with the multilevel collisional-radiative code MARIA. The complex satellite-rich structure observed in the Al Lyα emission indicates a presence of relatively cold dense plasma close to the Al foil surface, hot plasma between both foils, and Al ion trapping close to the Mg foil. An unusual formation of the Al spectra at the Mg foil surface is discussed in terms of interaction of counter-propagating plasmas, in particular trapping, deceleration and thermalization of the Al ions in the colliding plasmas. The qualitative analysis of the observed spectral emission is supported by 2D hydrodynamic modeling and by time-resolved imaging of the expanding plasma. Prospective use of the J-satellite line shifts in diagnosis of colliding laser-produced plasmas is discussed. [Copyright &y& Elsevier]

A systematic study of the Langmuir-wave-caused dips (L dips) observed in profiles of the Al Ly γ line emitted from laser irradiated sandwich targets indicates that these fine spectral features can be used as a tool for density diagnostics in intermediately coupled plasmas. The spectroscopic data required for a reliable identification of L dips were collected by a vertical-geometry Johann spectrometer providing high spectral and spatial resolution. The electron densities deduced from the evolution of the L dips along the laser target axis compare well with those derived from hydrosimulations and from measurements of the line widths and shifts. [ABSTRACT FROM AUTHOR]

Abstract: The structures observed in profiles of the line of Al XIII emitted from the laser-produced plasma are identified as the Langmuir-wave-caused dips (L-dips). Hitherto, the L-dips were found in hydrogen and deuterium spectral lines only; we report the first experiment dedicated to their identification in higher-Z plasmas. The L-dip phenomenon has a fundamental importance as a nonlinear dynamic-resonance effect of essentially multifrequency nature. Besides, the L-dips can be practically used for measuring the amplitude of the Langmuir waves. The latter diagnostic application might be very important in future experiments with laser-produced plasmas, as no other method was suggested in the literature for this purpose yet. [Copyright &y& Elsevier]

An astrophysically relevant experiment is compared to the output of a multidimensional radiation transfer code in which populations and radiation are self-consistently treated. Experimental Al Ly α spectra obtained with a very high-resolution spectrometer are presented as quantitative evidence of dot plasma non-planar expansion. Analysis of these spectra using the code is performed, in particular examining the effects of velocity gradients in directions other than that of the primary expansion. These calculations are found to be in good agreement with the experimental results. Usage of the Ly α doublet as a planarity diagnostic is discussed. [ABSTRACT FROM AUTHOR]

Soft X-ray Contact Microscopy (SXCM) of caenorhabditis elegans nematodes with typical length ∼800 μm and diameter ∼30 μm has been performed using the PALS laser source of wavelength λ = 1.314 μm and pulse duration τ(FWFIM) 400 ps. Pulsed soft X-rays were generated using molybdenum and gold targets with laser intensities I ≥ 1014 W/cm². Images have been recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Cuticle features and several internal organs have been identified in the SXCM images including lateral field, cuticle annuli, pharynx, and hypodermal and neuronal cell nuclei. [ABSTRACT FROM AUTHOR]

Evolution of the extreme ultraviolet (XUV) and soft X-ray (SXR) emission in the 50- to 2000-eV photon energy range from a plasma corona formed by loading a relatively thick Cu wire (with an initial diameter of 120μm) was observed in a Z-pinch discharge with a maximum current of 2 MA and current rise time of 100 ns. A diagnostic complex consisting of a five-channel SXR polychromator, a four-frame X-ray pinhole camera, and a mica crystal spectrograph shows that double-humped emission pulses in the XUV and SXR spectral ranges are generated 70–130 ns after the onset of the discharge current. The total energy of the pulses is 5 kJ, and the maximum power is 60 GW. A part of the observed kiloelectronvolt X-ray emission from three to five spots with diameters of 1–2 mm consists of the Cu K- and L-shell lines. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Detailed spectroscopic analysis of K-shell emission simultaneously observed at the irradiated and unirradiated surface of laser-exploded foils is reported. The space-dependent spectral line widths and relative shifts in the positions of the Al Lyman transition are interpreted in terms of the plasma density variations; the trend in the shifts data supports the idea of a density-dependent line shift. The significant features of the spectra emitted from the densest part of the plasma are compared with predictions from standard diagnostics modeling based on codes MEDUSA and FLY, and with the results of 2D ATLANT hydrodynamic simulations post-processed with a novel suite of atomic physics codes XEPAP. The results obtained corroborate the feasibility of the plasma density diagnostics based on line shifts in the intermediately coupled plasmas. [Copyright &y& Elsevier]

It is shown that the development of instabilities in a Z-pinch plasma formed by loading a relatively thick Al wire (an initial diameter of 120μm and a maximum discharge current of 2–3 MA) is slowed down due to the high plasma density in the wire corona. A cylindrically symmetric, regular, and stable corona surrounding the wire contains a helical formation with a dense, cold, and magnetized plasma. X-ray pulses with a photon energy of several keV and an FWHM duration of 10–20 ns are generated by a few imploded neck structures in the pinch phase of the corona evolution (70–100 ns after the current onset). The main part of X radiation emitted by individual bright spots in the photon energy range 1.5–2.4 keV (up to 40 J at a peak power of 4 GW) consists of the continuum and the bound–bound transition radiation from H- and He-like Al ions. A possible scenario for the axial magnetic field evolution during an X-ray pulse is outlined. © 2002 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Reports on the theoretical design of a vertical variant of a double channel-cut crystal spectrometer for investigation of laser-generated plasmas. Basis of the multicrystal configuration theory; Spectral resolution and luminosity; Collection efficiencies of multicrystal schemes.

The positions and profiles of x-ray spectral lines emitted from well characterized laserproduced plasmas have been investigated. The red shifts observed for higher members of the aluminum Lyman series are consistent with theoretical predictions of the line shifts in hot dense plasmas. The experimentally observed profiles of Al XIII Lya line are interpreted by modeling the radiative transport through plasma with large transverse gradients. [ABSTRACT FROM AUTHOR]

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