scholarly journals Plasma mirror focal spot quality for glass and aluminum mirrors for laser pulses up to 20  ps

2020 ◽  
Vol 45 (5) ◽  
pp. 1228
Author(s):  
Brandon Edghill ◽  
Pierre Forestier-Colleoni ◽  
Jaebum Park ◽  
Alexander Rubenchik ◽  
Farhat N. Beg ◽  
...  
Keyword(s):  
Focal Spot ◽  
Laser Pulses ◽  
Spot Quality

Plasma expansion produced by a long-pulse CO2 laser

1980 ◽  
Vol 58 (11) ◽  
pp. 1585-1588
Author(s):  
C. R. Neufeld ◽  
J. L. Lachambre
Keyword(s):  
Focal Spot ◽  
Laser Pulses ◽  
Plasma Expansion ◽  
Steady State Regime ◽  
Plasma Ions ◽  
Isothermal Expansion ◽  
State Regime ◽  
Expansion Model ◽  
Long Pulse ◽  
Aluminium Target

We have studied the plasma expansion produced when a 25 ns CO2 laser pulse is focussed onto a massive aluminium target. The maximum laser power density available was 2 × 1012 W cm−2 in a focal spot of approximately 250 μm in diameter. Charge collector measurements of the ions in the blow-off plasma indicate that an isothermal expansion model best describes the motion of the bulk of the plasma ions. Strong competing effects thus seem to inhibit the establishment of the steady-state regime expected for sufficiently long laser pulses, although faint indications of the beginnings of such a trend may be present.

scholarly journals X-ray conversion with PHEBUS laser

1999 ◽  
Vol 17 (3) ◽  
pp. 459-463 ◽  
Author(s):  
D. BABONNEAU ◽  
L. BONNET ◽  
S. JACQUEMOT ◽  
J.L. BOCHER ◽  
J.Y. BOUTIN ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Focal Spot ◽  
Transport Coefficients ◽  
Laser Pulses ◽  
Time Resolved ◽  
X Ray ◽  
Solid Liquid

A time-resolved X-ray conversion efficiency campaign was conducted at CEA/Limeil–Valenton on the PHEBUS laser, with Au planar targets. The calibrated diagnostic DEMIXART has measured X-ray emissions driven by shaped laser pulses. The results have been analyzed with the “physicist” 1D1/2 hydrodynamical code CHIVAS, where improved transport coefficients have been implemented. The influence of the degeneracy and solid/liquid corrections on various parameters is shown. Other significant effects due to focal spot shapes and lateral conduction are quantified with the FCI2 hydroradiative code of CEA/DRIF.

scholarly journals Passage of laser light through a hole-plasma shutter

1994 ◽  
Vol 12 (3) ◽  
pp. 445-454 ◽  
Author(s):  
K. Mašek ◽  
B. Králiková ◽  
J. Krása ◽  
L. Láska ◽  
K. Rohlena ◽  
...  
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Laser Energy ◽  
Laser Pulses ◽  
Hole Diameter ◽  
Simple Analytical Model ◽  
Iodine Laser ◽  
Temporal Shape ◽  
Foil Target ◽  
Laser Focal Spot

The interaction of a plasma produced by irradiation of perforated foils with laser pulses was studied. The laser beam of the first harmonics of the iodine laser (λ = 1.315 μm) system PERUN was focused by anf/2 optics (f = 20 cm) on a hole in the foil target of high-Z material. The laser energy and the temporal shape of the pulses were monitored both before and behind the hole. Foils of two different materials (Pb, Cu) were used, and a series of hole diameters 2rH ranging from 100 μm to 500 μm were tested. The diameter of the laser focal spot 2r0 was about 150 μm. For hole diameters smaller than 300 μm, a shortening of the laser pulse was observed, demonstrating the effect of plasma shutter. The pulse shortening, which depends on the hole diameter, corresponds to the reduction in the pulse energy passing through the hole. An analysis of the experimental data is based on hydrodynamic computations, and the physics of the process is illustrated by a simple analytical model.

Simulation and Measurement of the Laser Induced Breakdown in Air and Argon for Nanosecond Order Pulses

2012 ◽  
Author(s):  
Yongjun Choi ◽  
Chuandong Zhou ◽  
Peter Stoltz ◽  
Sachin Joshi ◽  
Azer Yalin
Keyword(s):  
Impact Ionization ◽  
Focal Spot ◽  
Laser Energy ◽  
Fluid Dynamic ◽  
Ambient Pressure ◽  
Laser Pulses ◽  
Focal Region ◽  
Laser Propagation ◽  
Laser Induced Breakdown ◽  
Photon Ionization

The interest in lasers for engine ignition is the possibility of higher efficiency and reduction of pollutants compared with conventional spark plugs. The interest in this area is to understand the laser energy needed for breakdown and ignition in order to better design practical systems. To support such development, the laser induced breakdown of air is simulated by the use of a two-dimensional computational fluid-dynamic model for 10 and 46 ns laser pulses for several pressures and focal spot sizes. The simulation includes the laser propagation, multi-photon ionization, impact ionization, electrons heating and energy loss. The dependence of breakdown irradiance on pulse duration, ambient pressure, and dimensions of the focal region is investigated and compared with experimental results.

scholarly journals Laser and target experiments on KrF GARPUN laser installation at FIAN

1999 ◽  
Vol 17 (1) ◽  
pp. 69-88 ◽  
Author(s):  
V.D. ZVORYKIN ◽  
I.G. LEBO
Keyword(s):  
Inertial Confinement Fusion ◽  
Focal Spot ◽  
Laser Pulses ◽  
Inertial Confinement ◽  
Power Laser ◽  
Spot Diameter ◽  
Confinement Fusion ◽  
Short Laser Pulses ◽  
Focal Spot Diameter ◽  
Laser Installation

Multistage, e-beam-pumped, 100 J-class KrF laser installation “GARPUN” is described with the emphases to high-power laser beam control and target irradiation experiments. The ablation pressures in the megabar range were measured and hydrodynamic flow was investigated both experimentally and by numerical simulations for laser intensities up to 5×1012 W/cm2, pulse duration of 100 ns, and focal spot diameter 150 μm. Graphite-diamond phase transformation under laser loading was observed by dynamic and Raman scattering methods. Some approaches to the fast ignition inertial confinement fusion, using the simultaneous amplification of long and short laser pulses in KrF drivers, are considered.

scholarly journals Analysis of wavefront effects for large-aperture tiled-grating compressor

2018 ◽  
Vol 36 (1) ◽  
pp. 84-91
Author(s):  
S. Zhang ◽  
J. W. Zhang ◽  
Y. Zhou ◽  
J. Q. Su ◽  
X. Wang ◽  
...  
Keyword(s):  
Focal Spot ◽  
Input Pulse ◽  
Output Pulse ◽  
Large Aperture ◽  
Spot Quality ◽  
Wavefront Error ◽  
Aperture Diffraction ◽  
Coating Stress ◽  
Wave Aberration ◽  
Intensity Laser

AbstractMonolithic large-aperture diffraction grating tiling is desired to increase the output capability of multi-kilojoule petawatt laser facilities. However, the wavefront errors of input pulse and gratings will degrade the focal spot quality and the compressibility of the output pulse. In this work, the effects of wavefront error of input pulse, deformation and wave aberration of the grating for the large-aperture tiled-grating compressor are investigated theoretically. A series of numerical simulations are presented to discuss the changing trends of focal spot energy caused by wavefront error of input pulse and obtain the error tolerance for specific goals. The influences of coating stress and the wave aberration of holographic exposure gratings on the diffraction wavefront are also discussed. Some advice is proposed for improving the performance of large-aperture tiled-grating. This work paves the way for the design of practical large-aperture tiled-grating compressor for ultrahigh intensity laser facilities in the future.

scholarly journals Laser assisted bioprinting at different wavelengths and pulse durations with a metal dynamic release layer: A parametric study

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Lothar Koch ◽  
Ole Brandt ◽  
Andrea Deiwick ◽  
Boris Chichkov
Keyword(s):  
Laser Pulse ◽  
Focal Spot ◽  
Femtosecond Lasers ◽  
Metal Layer ◽  
Laser Pulses ◽  
Spot Size ◽  
Laser Wavelength ◽  
Focal Spot Size ◽  
Gold Silver ◽  
Absorbing Material

 For more than a decade living cells and biomaterials (typically hydrogels) have been printed with laser-assisted bioprinting. Often, a thin metal layer is applied as laser-absorbing material, called dynamic release layer (DRL). This layer is vaporized by focused laser pulses generating vapor pressure that propels forward a coated biomaterial. Different lasers with laser wavelengths from 193 to 1064 nanometer have been used. As a metal DRL gold, silver, or titanium layers have been used. The applied laser pulse durations were usually in the nanosecond range from 1 to 30 ns. In addition, some studies with femtosecond lasers have been published. However, there are no studies on the effect of all these lasers parameters on bioprinting with a metal DRL, comparing different wavelengths and pulse durations – except one study comparing 500 femtosecond pulses with 15 ns pulses. In this paper, the effects of laser wavelength (355, 532, and 1064 nm) and laser pulse duration (in the range of 8 to 200 ns) are investigated. Furthermore, the effects of laser pulse energy, intensity, and focal spot size are studied. The printed droplet volume, hydrogel jet velocity, and cell viability are analyzed.

Focal spot analysis of radially polarized femtosecond laser pulses

2014 ◽  
Author(s):  
Wenchao Sun ◽  
Wenhua Hu ◽  
Junli Qi ◽  
Weiming Wang ◽  
Jiali Liao ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Focal Spot ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Radially Polarized ◽  
Spot Analysis

scholarly journals Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions

2009 ◽  
Vol 27 (2) ◽  
pp. 243-248 ◽  
Author(s):  
B. Dromey ◽  
C. Bellei ◽  
D.C. Carroll ◽  
R.J. Clarke ◽  
J.S. Green ◽  
...  
Keyword(s):  
High Intensity ◽  
Focal Spot ◽  
Spot Size ◽  
Harmonic Order ◽  
Third Harmonic ◽  
Spot Quality ◽  
High Laser ◽  
High Intensity Laser ◽  
Laser Systems ◽  
Laser Focal Spot

AbstractAs the state of the art for high power laser systems increases from terawatt to petawatt level and beyond, a crucial parameter for routinely monitoring high intensity performance is laser spot size on a solid target during an intense interaction in the tight focus regime (<10 µm). Here we present a novel, simple technique for characterizing the spatial profile of such a laser focal spot by imaging the interaction region in third harmonic order (3ωlaser). Nearly linear intensity dependence of 3ωlaser generation for interactions >1019 Wcm−2 is demonstrated experimentally and shown to provide the basis for an effective focus diagnostic. Importantly, this technique is also shown to allow in-situ diagnosis of focal spot quality achieved after reflection from a double plasma mirror setup for very intense high contrast interactions (>1020 Wcm−2) an important application for the field of high laser contrast interaction science.

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