scholarly journals Measurements and laser-wavelength dependence of mass-ablation rate and ablation pressure in planar layered targets

1991 ◽  
Vol 9 (3) ◽  
pp. 769-778 ◽  
Author(s):  
F. Dahmani ◽  
T. Kerdja
Keyword(s):  
Steady State ◽  
Energy Transport ◽  
Laser Light ◽  
Plasma Heating ◽  
Wavelength Dependence ◽  
Ablation Rate ◽  
Laser Wavelength ◽  
Ablation Pressure ◽  
Hydrodynamical Simulations ◽  
Laser Flux

Layered-targets experiments at 1.06-μm laser light have been performed in order to measure mass-ablation rate ṁ and ablation pressure Pa as a function of absorbed laser flux Ia and laser wavelength λL at irradiances of 1011-4.5 × 1012 W/cm2. The results can be put in the forms ṁ(g/cm2-s) ≈ 4.25 × 105[Ia(W/cm2)/1014]5/9(1 μm/λL)4/9 and Pa(Mbar) ≈ 20[Ia(W/cm2)/1014]7/9(1 μm/λL)2/9, which are consistent with the estimates obtained from a steady-state self-regulated model for plasma heating and with hydrodynamical simulations. Results show also a small lateral energy transport.

Measurements of Ablation Pressure and Mass Ablation Rate Using a Target Pendulum and a Thin Foil Target at 10 µm Laser Wavelength

1983 ◽  
Vol 22 (Part 2, No. 4) ◽  
pp. L248-L250 ◽  
Author(s):  
Hiroyuki Daido ◽  
Ryuzi Tateyama ◽  
Kazuki Ogura ◽  
Kunioki Mima ◽  
Sadao Nakai ◽  
...  
Keyword(s):  
Thin Foil ◽  
Ablation Rate ◽  
Laser Wavelength ◽  
Foil Target ◽  
Ablation Pressure

Laser-wavelength dependence of mass-ablation rate and heat-flux inhibition in laser-produced plasmas

1982 ◽  
Vol 26 (4) ◽  
pp. 2289-2292 ◽  
Author(s):  
R. Fabbro ◽  
E. Fabre ◽  
F. Amiranoff ◽  
C. Garban-Labaune ◽  
J. Virmont ◽  
...  
Keyword(s):  
Heat Flux ◽  
Wavelength Dependence ◽  
Ablation Rate ◽  
Laser Wavelength

scholarly journals Simulations of shock generation and propagation in laser-plasmas

2008 ◽  
Vol 26 (2) ◽  
pp. 179-188 ◽  
Author(s):  
I.G. Lebo ◽  
A.I. Lebo ◽  
D. Batani ◽  
R. Dezulian ◽  
R. Benocci ◽  
...  
Keyword(s):  
Recent Experiment ◽  
Laser Light ◽  
Laser Wavelength ◽  
Two Dimensional ◽  
Laser Plasmas ◽  
Ablation Pressure ◽  
Shock Generation

AbstractWe analyze the results of a recent experiment performed at the PALS laboratory and concerning ablation pressure at 0.44 µm laser wavelength measured at irradiance up to 2 × 1014 W/cm2. Using the code “ATLANT,” we have performed two-dimensional (2D) hydrodynamics simulations. Results show that 2D effects did not affect the experiment and also give evidence of the phenomenon of delocalized absorption of laser light.

Effect of lateral energy transport on ablation pressure scaling in laser irradiated planar foil targets

Pramana ◽  
1985 ◽  
Vol 25 (1) ◽  
pp. 63-70 ◽  
Author(s):  
L J Dhareshwar ◽  
P A Naik ◽  
S Sharma ◽  
H C Pant
Keyword(s):  
Energy Transport ◽  
Ablation Pressure

Laser-Induced Acoustic Waves for Measurement and Imaging

2000 ◽  
Author(s):  
Wen Li ◽  
Ronald A. Roy ◽  
Robin O. Cleveland ◽  
Lawrence J. Berg ◽  
Charles A. DiMarzio
Keyword(s):  
Acoustic Waves ◽  
Peak Power ◽  
Laser Light ◽  
Short Pulse ◽  
Laser Wavelength ◽  
Acoustic Imaging ◽  
Acoustic Energy ◽  
High Peak Power ◽  
First Case ◽  
Very High

Abstract A short pulse of laser light can act as a source of acoustic energy for acoustic imaging. Although there are a number of mechanisms by which the light pulse may generate sound, all require a pulse of high peak power density and short duration. In this work, we address examples where the material is highly absorbing at the laser wavelength, and the sound is generated near the surface. In these cases, there exist two different mechanisms which can convert the light to sound. The first is heating followed by expansion, and the second is generation of a plasma in the air above the surface. In the first case, sound generation occurs in the medium of interest and the energy efficiency can be very high, in the sense that no reflection losses occur. We present two applications from our own research.

Nonlinear excitation of a geodesic acoustic mode by reversed shear Alfvén eignemodes

2021 ◽  
Author(s):  
Yahui Wang ◽  
Tao Wang ◽  
Shizhao Wei ◽  
Zhiyong Qiu
Keyword(s):  
Steady State ◽  
Plasma Heating ◽  
Acoustic Mode ◽  
Decay Process ◽  
Nonlinear Excitation ◽  
Parametric Decay ◽  
Geodesic Acoustic Mode ◽  
Burning Plasmas ◽  
Reversed Shear ◽  
Excitation Conditions

Abstract The parametric decay process of a reversed shear Alfv\'{e}n eigenmeode (RSAE) into a geodesic acoustic mode (GAM) and a kinetic reversed shear Alfv\'{e}n eigenmode (KRSAE) is investigated using nonlinear gyrokinetic theory. The excitation conditions mainly require the pump RSAE amplitude to exceed a certain threshold, which could be readily satisfied in burning plasmas operated in steady-state advanced scenario. This decay process can contribute to thermal plasma heating and confinement improvement.

Ruby Laser Induced Changes in the Absorption Spectra of Sodium Decorated Sodium Chloride Crystals

1970 ◽  
Vol 25 (2) ◽  
pp. 229-236
Author(s):  
H. Kuzmany
Keyword(s):  
Absorption Spectra ◽  
Ruby Laser ◽  
Laser Light ◽  
Temperature Treatment ◽  
Laser Wavelength ◽  
Beam Path ◽  
General Increase ◽  
Annealing Conditions ◽  
Different Depths ◽  
Induced Changes

Abstract The effects of intense Q-switched ruby laser light on the absorption spectra of NaCl crystals, additively coloured by colloidal sodium were investigated at different depths along the laser beam path as well as after being subjected to different annealing conditions. A strong general increase in absorption was observed in the region where the laser light entered the crystal, while a strong decrease in absorption occurred in the colloid band, especially around the laser wavelength. This bleaching was accompanied by the generation of a new absorption band at ~ 1200 nm (~1.0eV) in the infrared, which, according to its sensitivty to temperature treatment, is not of colloidal origin, The energy denisty necessary for its generation was found to be about 400mJ/cm2. Its is suggested that the bleaching of the colloid band could be used for the storage of holograms.

scholarly journals Excitation of kinetic Alfvén turbulence by MHD waves and energization of space plasmas

2004 ◽  
Vol 11 (5/6) ◽  
pp. 535-543 ◽  
Author(s):  
Y. Voitenko ◽  
M. Goossens
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Energy Transport ◽  
Plasma Heating ◽  
Alfven Wave ◽  
Mhd Waves ◽  
Space Plasmas ◽  
Small Scale ◽  
The Magnetic Field ◽  
Dissipation Range

Abstract. There is abundant observational evidence that the energization of plasma particles in space is correlated with an enhanced activity of large-scale MHD waves. Since these waves cannot interact with particles, we need to find ways for these MHD waves to transport energy in the dissipation range formed by small-scale or high-frequency waves, which are able to interact with particles. In this paper we consider the dissipation range formed by the kinetic Alfvén waves (KAWs) which are very short- wavelengths across the magnetic field irrespectively of their frequency. We study a nonlocal nonlinear mechanism for the excitation of KAWs by MHD waves via resonant decay AW(FW)→KAW1+KAW2, where the MHD wave can be either an Alfvén wave (AW), or a fast magneto-acoustic wave (FW). The resonant decay thus provides a non-local energy transport from large scales directly in the dissipation range. The decay is efficient at low amplitudes of the magnetic field in the MHD waves, B/B0~10-2. In turn, KAWs are very efficient in the energy exchange with plasma particles, providing plasma heating and acceleration in a variety of space plasmas. An anisotropic energy deposition in the field-aligned degree of freedom for the electrons, and in the cross-field degrees of freedom for the ions, is typical for KAWs. A few relevant examples are discussed concerning nonlinear excitation of KAWs by the MHD wave flux and consequent plasma energization in the solar corona and terrestrial magnetosphere.

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