scholarly journals Development of holographic methods for investigating a moving free surface, accelerated by laser-induced shock waves

1999 ◽  
Vol 17 (4) ◽  
pp. 653-660 ◽  
Author(s):  
M. WERDIGER ◽  
S. ELIEZER ◽  
S. MAMAN ◽  
Y. HOROVITZ ◽  
B. ARAD ◽  
...  
Keyword(s):  
Shock Wave ◽  
Free Surface ◽  
Shock Waves ◽  
Atmospheric Pressure ◽  
Laser Light ◽  
Laser System ◽  
Rear Surface ◽  
Green Laser ◽  
Forward Scattering ◽  
High Power Lasers

Holographic methods developed to study the behavior of surfaces shocked by high power lasers are reported. Shock waves of the order of hundreds of kilobars are generated in Sn targets 50-μm thick, by a Nd:YAG laser system with a wavelength of 1.06 μm, a pulse duration of 7.5 ns FWHM, and irradiance in the range (1.0–2.6)·1013 W/cm2. Two configurations of off-axis holography were applied: holograms based on forward scattering, and holograms of both backward and forward scattering. The hologram is produced by scattering of a pulse, 6.7 ns (FWHM), of green laser light synchronized with the laser that generates the shock wave. Holograms of the topology of the rear surface of shocked Sn targets moving in vacuum and in air (at atmospheric pressure) are reported.

scholarly journals Detecting of melting by changes of rear surface reflectivity in shocked compressed metals using an interferometric diagnostic method

1999 ◽  
Vol 17 (3) ◽  
pp. 547-556 ◽  
Author(s):  
M. WERDIGER ◽  
S. ELIEZER ◽  
S. MAMAN ◽  
Y. HOROVITZ ◽  
E. MOSHE ◽  
...  
Keyword(s):  
Shock Wave ◽  
Free Surface ◽  
Pulse Width ◽  
Diagnostic Method ◽  
Laser System ◽  
Rear Surface ◽  
Power Laser ◽  
Shock Wave Pressure ◽  
Surface Reflectivity ◽  
Pressure Regime

When a high power laser (1012 W/cm2) irradiates a target, it induces a shock wave, which reaches the (free) rear surface. The free surface is accelerated and the shock wave is back-reflected as a rarefaction wave. In the shock wave pressure regime involved here, melting of the target during the shock or during the rarefaction may occur. An optically recording velocity interferometric system (ORVIS) has been developed to measure the time evolution of the change in the reflectivity of the free surface. Shock waves of the order of hundreds of kilobars are produced in 50–125 μm thick Sn and Al foils, by a Nd:YAG laser system with a wavelength of 1.06 μm, pulse width of 7 ns (FWHM), and irradiance in the range (1.4–2.4)·1013 W/cm2. The changes in the reflectivity occur along two time scales: a slow one, more than 17 ns in Al and more than 30 ns in Sn, and a rapid one, less than 2.5 ns, in both materials. A possible explanation for the sharp decreases in the time scale is that melting occurs during the release of the free surface.

scholarly journals Ultrafast ignition with relativistic shock waves induced by high power lasers

2014 ◽  
Vol 2 ◽  
Author(s):  
Shalom Eliezer ◽  
Noaz Nissim ◽  
Shirly Vinikman Pinhasi ◽  
Erez Raicher ◽  
José Maria Martinez Val
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Radiation Pressure ◽  
Ponderomotive Force ◽  
Relativistic Hydrodynamics ◽  
Pressure Shock ◽  
Compression Pressure ◽  
High Power Lasers ◽  
Relativistic Shock ◽  
Wave Induced

Abstract In this paper we consider laser intensities greater than $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}10^{16}\ \mathrm{W\ cm}^{-2}$ where the ablation pressure is negligible in comparison with the radiation pressure. The radiation pressure is caused by the ponderomotive force acting mainly on the electrons that are separated from the ions to create a double layer (DL). This DL is accelerated into the target, like a piston that pushes the matter in such a way that a shock wave is created. Here we discuss two novel ideas. Firstly, the transition domain between the relativistic and non-relativistic laser-induced shock waves. Our solution is based on relativistic hydrodynamics also for the above transition domain. The relativistic shock wave parameters, such as compression, pressure, shock wave and particle flow velocities, sound velocity and rarefaction wave velocity in the compressed target, and temperature are calculated. Secondly, we would like to use this transition domain for shock-wave-induced ultrafast ignition of a pre-compressed target. The laser parameters for these purposes are calculated and the main advantages of this scheme are described. If this scheme is successful a new source of energy in large quantities may become feasible.

scholarly journals Relativistic shock waves in the laboratory

2013 ◽  
Vol 31 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Shalom Eliezer ◽  
Jose Maria Martinez Val ◽  
Shirly Vinikman Pinhasi
Keyword(s):  
Fluid Dynamics ◽  
Shock Wave ◽  
Shock Waves ◽  
Ponderomotive Force ◽  
High Power Lasers ◽  
Relativistic Fluid Dynamics ◽  
Wave Velocities ◽  
Relativistic Shock ◽  
Relativistic Fluid ◽  
Recent Developments

AbstractDue to the recent developments in high power lasers in the multi-petawatt domain it seems now feasible to accelerate a micro-foil to relativistic velocities. In this paper, we calculate analytically the high velocities achieved by the ponderomotive force of the irradiating laser. The accelerated foil collides with a second foil resulting in the creation of the relativistic shock waves. The density, pressure, temperature, and shock wave velocities are calculated within the context of relativistic fluid dynamics. The calculated thermodynamic parameters that are achieved in these collisions are enormous.

scholarly journals Asymptotic measurements of free surface instabilities in laser-induced shock waves

1996 ◽  
Vol 14 (2) ◽  
pp. 133-147 ◽  
Author(s):  
M. Werdiger ◽  
B. Arad ◽  
Z. Henis ◽  
Y. Horowitz ◽  
E. Moshe ◽  
...  
Keyword(s):  
Free Surface ◽  
Shock Waves ◽  
Pulse Width ◽  
Laser System ◽  
Optical Scattering ◽  
Liquid Transition ◽  
Aluminium Copper ◽  
Metallic Sample ◽  
Mass Ejection ◽  
Surface Occurrence

An experimental technique based on optical scattering to detect melting in release of strongly shocked materials is presented. This method is used to study the asymptotic behavior of the free surface of shock-loaded materials. After reflection of a shock wave from a metallic sample free surface, occurrence of a solid to liquid transition will induce a dynamic behavior such as mass ejection and development of instabilities. A study of the mass ejection due to laser-induced shock waves in aluminium, copper, and tin targets is presented. Shock waves of order of hundreds of kilobars to more than one megabar are produced by a Nd:YAG laser system with a wavelength of 1.06 μm, pulse width of 7 ns FWHM focused to spot of 200 μm. The velocities, size, and topological structure of the ejected particles are measured. The radii of the ejecta are in the range 0.5–7 μm.

scholarly journals Laser-driven shock wave experiments at the University of British Columbia

1986 ◽  
Vol 4 (3-4) ◽  
pp. 555-567 ◽  
Author(s):  
A. Ng ◽  
D. Parfeniuk ◽  
L. Da Silva ◽  
P. Celliers
Keyword(s):  
Shock Wave ◽  
British Columbia ◽  
Shock Waves ◽  
Rear Surface ◽  
Laser Pulses ◽  
Shock Propagation ◽  
Dense Plasmas ◽  
University Of British Columbia ◽  
Surface Measurements ◽  
The University

A review of recent laser-driven shock wave experiments at the University of British Columbia is presented. These include emissivity and reflectivity measurements on target rear surfaces when the shock wave emerges as well as measurements of the trajectories of shock propagation in initially transparent targets irradiated by temporally tailored laser pulses. The rear surface measurements allowed us to study the equation of state and electron conductivity of dense plasmas while coalescence of shock waves was evident in the trajectory of shock waves driven by a shaped pulse.

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

Features of spatial shock-wave flows in vapor-gas-liquid mixtures

2014 ◽  
Vol 10 ◽  
pp. 27-31
Author(s):  
R.Kh. Bolotnova ◽  
U.O. Agisheva ◽  
V.A. Buzina
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Waves ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Pressure Vessels ◽  
Water Mixture ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Two Phase

The two-phase model of vapor-gas-liquid medium in axisymmetric two-dimensional formulation, taking into account vaporization is constructed. The nonstationary processes of boiling vapor-water mixture outflow from high-pressure vessels as a result of depressurization are studied. The problems of shock waves action on filled by gas-liquid mixture volumes are solved.

scholarly journals Nematic Dispersive Shock Waves from Nonlocal to Local

2021 ◽  
Vol 11 (11) ◽  
pp. 4736
Author(s):  
Saleh Baqer ◽  
Dimitrios J. Frantzeskakis ◽  
Theodoros P. Horikis ◽  
Côme Houdeville ◽  
Timothy R. Marchant ◽  
...  
Keyword(s):  
Shock Wave ◽  
Liquid Crystals ◽  
Shock Waves ◽  
Numerical Solutions ◽  
Wave Structure ◽  
Beam Power ◽  
Input Beam ◽  
Shock Wave Structure ◽  
Wave Solutions ◽  
Modulation Theory

The structure of optical dispersive shock waves in nematic liquid crystals is investigated as the power of the optical beam is varied, with six regimes identified, which complements previous work pertinent to low power beams only. It is found that the dispersive shock wave structure depends critically on the input beam power. In addition, it is known that nematic dispersive shock waves are resonant and the structure of this resonance is also critically dependent on the beam power. Whitham modulation theory is used to find solutions for the six regimes with the existence intervals for each identified. These dispersive shock wave solutions are compared with full numerical solutions of the nematic equations, and excellent agreement is found.

scholarly journals Reflecting petawatt lasers off relativistic plasma mirrors: a realistic path to the Schwinger limit

2021 ◽  
Vol 9 ◽  
Author(s):  
Fabien Quéré ◽  
Henri Vincenti
Keyword(s):  
Light Intensity ◽  
High Power ◽  
Quantum Electrodynamics ◽  
Laser Light ◽  
Optical Breakdown ◽  
Relativistic Plasma ◽  
Laser Beams ◽  
Relativistic Motion ◽  
Quantum Vacuum ◽  
High Power Lasers

Abstract The quantum vacuum plays a central role in physics. Quantum electrodynamics (QED) predicts that the properties of the fermionic quantum vacuum can be probed by extremely large electromagnetic fields. The typical field amplitudes required correspond to the onset of the ‘optical breakdown’ of this vacuum, expected at light intensities >4.7×1029 W/cm2. Approaching this ‘Schwinger limit’ would enable testing of major but still unverified predictions of QED. Yet, the Schwinger limit is seven orders of magnitude above the present record in light intensity achieved by high-power lasers. To close this considerable gap, a promising paradigm consists of reflecting these laser beams off a mirror in relativistic motion, to induce a Doppler effect that compresses the light pulse in time down to the attosecond range and converts it to shorter wavelengths, which can then be focused much more tightly than the initial laser light. However, this faces a major experimental hurdle: how to generate such relativistic mirrors? In this article, we explain how this challenge could nowadays be tackled by using so-called ‘relativistic plasma mirrors’. We argue that approaching the Schwinger limit in the coming years by applying this scheme to the latest generation of petawatt-class lasers is a challenging but realistic objective.

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