Numerical Simulations of Laser-Driven Cratering Experiments into Porous Graphite

We present the results of an experimental campaign conducted on the LULI2000 laser facility. Semi-infinite targets of a commercial grade of porous graphite were submitted to high-power laser irradiation inorder to generate craters. A 15 ns pulse duration was used along with a focal spot diameter of 900 µm to deliver energies up to 750 J. Numerical simulations of these shots have been performed following a specificmethodology which can be divided in three steps. Firstly, the mechanical loading induced by the laser iscalibrated by simulating the same shot on a thin aluminum target of which free surface velocity is measured byPDV and line-VISAR. Secondly, the same shot is performed on a thin graphite target to validate the materialmodel of graphite. Thirdly, the craterization shot on semi-infinite target is simulated. Numerical results arecompared to experimental measurements of craters obtained using an interferometric profilometer.

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Laser-induced cratering of a 3DCC material at mesoscale: Experiments and simulations

EPJ Web of Conferences ◽

10.1051/epjconf/201818301028 ◽

2018 ◽

Vol 183 ◽

pp. 01028

Author(s):

Vincent Jaulin ◽

David Hébert ◽

Bertrand Aubert ◽

Jean-Luc Rullier ◽

Frédéric Malaise ◽

...

Keyword(s):

Composite Material ◽

Composite Materials ◽

Dynamic Behaviour ◽

Focal Spot ◽

Dynamic Pressure ◽

Dynamic Strength ◽

Mesoscopic Scale ◽

Spot Diameter ◽

Laser Facility ◽

Focal Spot Diameter

This study concerns the damaging of a 3-Dimension Carbon/Carbon (3DCC) composite material under dynamic loading. Experiments were performed with a laser facility delivering energies between 13 and 40 J with 100 nanoseconds pulse duration. The focal spot diameter was 250 μm, leading to dynamic pressure up to 10 GPa. The focal spot being smaller than the size of the composite components, it allows us to study the dynamic behaviour of the material at mesoscopic scale. The dynamic process of this cratering is then investigated via 3D numerical simulations, and a Johnson-Holmquist model is proposed. It appears that comparison of simulations with experimental results is useful to identify the dynamic strength of individual components of composite materials.

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Laser and target experiments on KrF GARPUN laser installation at FIAN

Laser and Particle Beams ◽

10.1017/s0263034699171064 ◽

1999 ◽

Vol 17 (1) ◽

pp. 69-88 ◽

Cited By ~ 8

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.

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Numerical simulations in support of the design of an ultrasonic device for sub-assembly identification

EPJ Web of Conferences ◽

10.1051/epjconf/202125305001 ◽

2021 ◽

Vol 253 ◽

pp. 05001

Author(s):

Kevin Paumel ◽

Tom Maurel ◽

Christian Lhuillier

Keyword(s):

Numerical Simulations ◽

Focal Spot ◽

Numerical Models ◽

Spectral Response ◽

Spot Size ◽

Liquid Sodium ◽

Focal Distance ◽

Element Simulation ◽

Focal Spot Diameter ◽

Harsh Conditions

In this paper, it is shown how numerical simulations can help designing an ultrasonic instrument operating in harsh conditions. To prevent fuel handling errors in sodium cooled fast reactors, the identification of fuel sub-assemblies using ultrasound is being investigated. It is based on the interpretation of a code (aligned notches) engraved on the sub-assembly head using an emitting/receiving ultrasonic sensor. This reading is performed in liquid sodium with high temperature (up to 600°C) transducers. A first experiment in liquid sodium demonstrated the feasibility of this method. The reading quality and robustness depend on various parameters related to the ultrasonic beam (spectral response, focal distance, focal spot size), the code geometry (especially the notches’ dimensions) and geometrical alignments. In order to avoid numerous experiments, two numerical models are developed. The first one is a finite element simulation of the sensor providing its radiated field. This model is validated with the well-known analytic solution of the Rayleigh integral; then it is applied to the sensor used in the sodium experiment. The focal distance and focal spot diameter are close to the expected values. The second simulation, using CIVA software, provides the ultrasonic scan of the code. The result is in good agreement with the sodium experiment and a first comparison with a water experiment shows that this numerical tool is relevant for easily taking into account misalignment and misorientation of the scan.

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XRMF applications of a monolithic, polycapillary, focusing x-ray optic

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163666 ◽

1996 ◽

Vol 54 ◽

pp. 240-241

Author(s):

D. A. Carpenter ◽

Ning Gao ◽

G. J. Havrilla

Keyword(s):

Trace Elements ◽

Point Source ◽

Focal Spot ◽

Fluorescence Analysis ◽

X Rays ◽

Focal Distance ◽

Spot Diameter ◽

X Ray ◽

Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

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Numerical simulations with RELAP5-3D of the first experimental campaign on In-box LOCA transient for HCLL TBS

Fusion Engineering and Design ◽

10.1016/j.fusengdes.2020.112160 ◽

2021 ◽

Vol 163 ◽

pp. 112160

Author(s):

A. Venturini ◽

M. Utili ◽

N. Forgione

Keyword(s):

Numerical Simulations ◽

Experimental Campaign

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Wavefront correction for near diffraction-limited focal spot on a 6×100 J/1-ns laser facility

10.1117/12.517964 ◽

2003 ◽

Author(s):

Julien Fuchs ◽

Benoit F. Wattellier ◽

Ji P. Zou ◽

Jean-Christophe Chanteloup ◽

H. Bandulet ◽

...

Keyword(s):

Focal Spot ◽

Wavefront Correction ◽

Laser Facility

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Energy Prediction and Sensitivity of Influence Factors with Ensemble Neural Networks for High-Power Laser Facility

Optics Express ◽

10.1364/oe.447763 ◽

2022 ◽

Author(s):

Lu Zou ◽

Yuanchao Geng ◽

Liu guodong ◽

Lanqin Liu ◽

Chen Fengdong ◽

...

Keyword(s):

Neural Networks ◽

High Power ◽

Influence Factors ◽

High Power Laser ◽

Power Laser ◽

Energy Prediction ◽

Ensemble Neural Networks ◽

Laser Facility

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Interferometric investigations of influence of target irradiation on the parameters of laser-produced plasma jets

Laser and Particle Beams ◽

10.1017/s0263034607000547 ◽

2007 ◽

Vol 25 (3) ◽

pp. 425-433 ◽

Cited By ~ 13

Author(s):

A. Kasperczuk ◽

T. Pisarczyk ◽

S. Borodziuk ◽

J. Ullschmied ◽

E. Krousky ◽

...

Keyword(s):

Focal Spot ◽

Laser Energy ◽

Plasma Jet ◽

Plasma Jets ◽

Plasma Expansion ◽

Third Harmonic ◽

Fundamental Process ◽

Laser Produced Plasma ◽

Laser Facility ◽

Planar Target

Our recent experimental results demonstrate that the formation of plasma jets is a fundamental process accompanying the laser produced plasma expansion, if a massive planar target with relatively high atomic number is irradiated by a defocused laser beam. In this paper some new results on the influence of target irradiation conditions on plasma jet parameters are presented. The experiment was carried out at the PALS iodine laser facility, with the third harmonic beam of the pulse duration of 250 ps (FWHM). The beam energies varied in the range of 13–160 J, the focal spot radii in the range of 35–600 µm. The planar massive targets used in the experiment were made of Cu, Ag and Ta. For measurements of the electron density evolution a three frame interferometric system was employed. The jets were observed in the whole range of the laser energy used. The initial velocities of the plasma jets produced in the reported experiment reached the value of up to 7·107 cm/s, the jets were up to 4 mm long including the jet pedestal and about 400 µm in diameter. Calculations of the efficiency of the plasma jet production show that it decreases with increasing the laser energy.

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