Multiply charged ions from iodine laser-produced plasma of medium- and high-Z targets

Maximum charge states of ions registered in the far expansion zone from laser-produced plasma of Al, Co, Ni, Cu, Ta, W, Pt, Au, Pb, and Bi are presented. The Thomson parabola spectrometer was used to display a general view of the ion species of an expanding plasma while detailed ion charge-energy spectra were determined by the cylindrical electrostatic ion energy analyzer. The current densities of highly charged ion groups above 20 mA/cm2 were measured by use of an ion collector at a distance of 1 m from the target. The photodissociation iodine laser system PERUN (λ = 1.315 μm, power density up to 1015 W cm−2) was employed as a drive

Ion production by lasers using high-power densities in a near infrared region

Results are presented of experiments on ion production from Ta targets using a short pulse (350-600 ps in focus) illumination with focal power densities exceeding 1014 Wcm-2 at the wavelength of an iodine photodissociation laser (1.315 μm) and its harmonics. Strong evidence of the existence of tantalum ions with the charge state +45 near the target surface was obtained by X-ray spectroscopy methods. The particle diagnostics point to the existence of frozen high charge states (4 MeV) for the highest observed charge states. A tentative theoretical explanation of the observed anomalous charge state freezing phenomenon in the expanding plasma produced by a subnanosecond laser pulse is give

X-ray microscopy of living multicellular organisms with the Prague Asterix Iodine Laser System

Soft X-ray contact microscopy (SXCM) experiments have been performed using the Prague Asterix Iodine Laser System (PALS). Laser wavelength and pulse duration were λ = 1.314 μm and τ (FWHM) = 450 ps, respectively. Pulsed X rays were generated using teflon, gold, and molybdenum targets with laser intensities I ≥ 1014 W/cm2. Experiments have been performed on the nematodes Caenorhabditis elegans. Images were recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Our preliminary results indicate the suitability of the SXCM for multicellular specimens

Shock pressure induced by 0.44 [mu]m laser radiation on aluminum targets

Shock pressure generated in aluminum targets due to the interaction of 0.44 μm (3 ω of iodine laser) laser radiation has been studied. The laser intensity profile was smoothed using phase zone plates. Aluminum step targets were irradiated at an intensity I ≈ 1014 W/cm2. Shock velocity in the aluminum target was estimated by detecting the shock luminosity from the target rear using a streak camera to infer the shock pressure. Experimental results show a good agreement with the theoretical model based on the delocalized laser absorption approximation. In the present report, we explicitly discuss the importance of target thickness on the shock pressure scaling

Exhumation of west Sundaland: A record of the path of India?

The Indian Plate commenced its northward migration towards Eurasia in the Early Cretaceous. The lateral effect of this migration on the western edge of the Sunda Plate in Southeast Asia still remains equivocal. In order to assess this effect, we evaluate several key sectors characterized by deep crustal exhumation along a N-S transect from the southern Malay Peninsula to the East Himalayan Syntaxis. The evaluation is aided by a structural analysis of vertical movements and basin development. Five major metamorphic domes with similar geodynamic evolution, maximum P-T burial conditions and exhumation are studied. Exhumation of these domes migrated with time between Late Cretaceous in the Stong Complex (north Malaysia) in the south and Late Miocene in the Gaoligong Shear Zone (south China) in the north, as documented by published work and our new fission track data presented herein. Deformation is characterized by a N-S oriented extension that followed the more regional E-W oriented plate tectonic shortening, creating local core-complexes and syn-kinematic magmatism in the footwall of crustal-scale detachments, which displays a consistent temporal northward migration. The N-S extension was associated with the onset of hanging-wall deposition in the sedimentary basins of western Sundaland (e.g. Malay, Sumatra, and Thai Basins) during continuous exhumation of the footwall to upper brittle levels. Our multifaceted analysis of structural and thermochronological data shows a similar succession of tectonic, thermal and sedimentary events in west Sundaland that was driven by the gradual northward migration of India starting from Cretaceous times. We infer that the principal mechanism was driven by the subduction of an excess topography of Greater India rifted continental margin during its underplating, resulting in uplift, thermal anomalies, extensional exhumation and associated subsidence

Geochronological evidence for the Alpine tectono-thermal evolution of the Veporic Unit (Western Carpathians, Slovakia)

Tectono-thermal evolution of the Veporic Unit was revealed by multiple geochronological methods, including 87Rb/86Sr on muscovite and biotite, zircon and apatite fission-track, and apatite (U-Th)/He analysis. Based on the new data, the following Alpine tectono-thermal stages can be distinguished: The Eo-Alpine Cretaceous nappe stacking (~135-95 Ma) resulted in burial of the Veporic Unit beneath the northward overthrusting Gemeric Unit and overlying Jurassic Meliata accretionary wedge. During this process the Veporic Unit reached metamorphic peak of greenschist- to amphibolite facies accompanied by orogen-parallel flow in its lower and middle crust. The subsequent evolution of this crust is associated with two distinct exhumation mechanisms related to collision with the northerly Tatric-Fatric basement. The first mechanism (~90-80 Ma) is associated with internal subhorizontal shortening of the Veporic Unit reflected by large-scale upright folding and heterogeneous exhumation of the Veporic lower crust in the cores of crustal-scale antiforms. This led to juxtaposition of the higher and lower grade parts of basement, all cooled down to ~350 °C by ~80 Ma. The second mechanism is associated with the overthrusting of the Veporic Unit over the attenuated Fatric crust. This led to a passive en-block exhumation of the Veporic crust from ~350 °C to 60 °C between ~80 and 55 Ma followed by erosion (~55-35 Ma). The erosion processes resulted in formation of planation surface before the Late Eocene transgression. After erosion and planation, a new sedimentary cycle of the Central Carpathian Palaeogene Basin was deposited with the sedimentary strata thickness of ~1.5-2.0 km (~21-17 Ma). The early to middle Miocene is characterised by destruction tectonic disintegration and erosion of this basin (~20-13 Ma) and formation of the Neogene Vepor Stratovolcano (~13 Ma). The final shaping of the area has been linked to erosional processes of the volcanic structure since the Late Sarmatian with accelerated processes during the Plio-Quaternary