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.

scholarly journals Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets

2011 ◽  
Vol 29 (3) ◽  
pp. 345-351 ◽  
Author(s):  
C.M. Brenner ◽  
J.S. Green ◽  
A.P.L. Robinson ◽  
D.C. Carroll ◽  
B. Dromey ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Focal Spot ◽  
Laser Pulse Energy ◽  
Laser Energy ◽  
Spot Size ◽  
Proton Flux ◽  
Focal Spot Size ◽  
Order Of Magnitude ◽  
Laser Focal Spot ◽  
Accelerated Protons

AbstractThe scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.

scholarly journals IR Laser-Induced Changes to L-adrenaline-D-hydrogentartrate Incorporated in KBr Matrices

2002 ◽  
Vol 20 (2-4) ◽  
pp. 89-98
Author(s):  
Tatijana S. Jovanovic ◽  
Milica R. Bogavac ◽  
Bojan B. Radak ◽  
Milan S. Trtica
Keyword(s):  
Carbon Dioxide ◽  
Energy Density ◽  
Laser Energy ◽  
Laser Pulses ◽  
Laser Energy Density ◽  
Cooh Group ◽  
Temporal Shape ◽  
Ir Laser ◽  
Out Of Plane ◽  
Induced Changes

Changes in the pharmaceutical L-adrenaline-D-hydrogentartrate, incorporated in KBr matrices, induced by a pulsed carbon-dioxide Transversely Excited Atmospheric (TEA) laser, were observed. Modifications of the sample were monitored via infrared spectra. Special attention was devoted to the dependence of the sample changes on the laser energy density used. The irradiation of the pharmaceutical has been performed with two laser lines at wavelengths of about 10.6 µm. The laser lines coincide well with the absorption band of the pharmaceutical, which is assigned to the ring vibrations/out-of-plane OH deformation vibrations, within the carboxyl (COOH) group of L-adrenaline-D-hydrogentartrate. Laser energy densities of 1.20 and 1.70 J/cm2 modified the pharmaceutical/compound. It was found that this modification is in essence a thermal effect. The level of change showed a dependence on the laser energy density, number of accumulated laser pulses and temporal shape of the pulse.

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 Reflection of intense laser light from microstructured targets as a potential diagnostic of laser focus and plasma temperature

2018 ◽  
Vol 7 ◽  
Author(s):  
J. Jarrett ◽  
M. King ◽  
R. J. Gray ◽  
N. Neumann ◽  
L. Döhl ◽  
...  
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Plasma Temperature ◽  
Regular Structure ◽  
Intense Laser ◽  
Reflected Light ◽  
Laser Focus ◽  
Speckle Patterns ◽  
Focal Spot Diameter ◽  
Laser Focal Spot

The spatial-intensity profile of light reflected during the interaction of an intense laser pulse with a microstructured target is investigated experimentally and the potential to apply this as a diagnostic of the interaction physics is explored numerically. Diffraction and speckle patterns are measured in the specularly reflected light in the cases of targets with regular groove and needle-like structures, respectively, highlighting the potential to use this as a diagnostic of the evolving plasma surface. It is shown, via ray-tracing and numerical modelling, that for a laser focal spot diameter smaller than the periodicity of the target structure, the reflected light patterns can potentially be used to diagnose the degree of plasma expansion, and by extension the local plasma temperature, at the focus of the intense laser light. The reflected patterns could also be used to diagnose the size of the laser focal spot during a high-intensity interaction when using a regular structure with known spacing.

scholarly journals Conversion of laser light into soft X rays with 3-ns and 30-ps laser pulses

1991 ◽  
Vol 9 (2) ◽  
pp. 551-562 ◽  
Author(s):  
K. Eidmann ◽  
W. Schwanda
Keyword(s):  
Laser Light ◽  
Laser Energy ◽  
Short Pulse ◽  
Laser Pulses ◽  
X Rays ◽  
Incident Laser ◽  
X Ray ◽  
Transmission Grating ◽  
Incident Laser Energy ◽  
Temporal And Spatial

The X-ray emission from planar targets made of aluminum, copper, or gold irradiated by a frequency-doubled Nd laser (530-nm wavelength and 1012–1014-W/cm2 laser intensity) was measured at two pulse durations: 3 ns and 30 ps. We absolutely measured the X-ray emission with spectral, temporal, and spatial resolution in the wavelength range 3 Å < λ < 250 Å by using filtered bolometers, a transmission grating spectrometer, X-ray diodes, and an X-ray streak camera as diagnostics. In addition, the absorption of laser light was measured. For the short, 30-ps laser pulse the conversion of incident laser energy into X rays was considerably less than that with the long, 3-ns pulse. This is caused by less absorption of laser light and, in addition, by less conversion of absorbed laser energy into X rays in the case of the short pulse. The results are compared with numerical simulations performed with the MULTI hydrocode.

ENERGETIC PROTON ACCELERATION BY ULTRAINTENSE LASER PULSES IN INHOMOGENEOUS PLASMA TARGETS

2007 ◽  
Vol 21 (03n04) ◽  
pp. 642-646 ◽  
Author(s):  
A. ABUDUREXITI ◽  
Y. MIKADO ◽  
T. OKADA
Keyword(s):  
Laser Pulse ◽  
Inhomogeneous Plasma ◽  
Laser Pulses ◽  
Proton Acceleration ◽  
Particle In Cell ◽  
Target Plasma ◽  
Plasma Target ◽  
Experimental Process ◽  
Foil Target ◽  
Proton Bunch

Particle-in-Cell (PIC) simulations of fast particles produced by a short laser pulse with duration of 40 fs and an intensity of 1020W/cm2 interacting with a foil target are performed. The experimental process is numerically simulated by considering a triangular concave target illuminated by an ultraintense laser. We have demonstrated increased acceleration and higher proton energies for triangular concave targets. We also determined the optimum target plasma conditions for maximum proton acceleration. The results indicated that a change in the plasma target shape directly affects the degree of contraction accelerated proton bunch.

Raman compression of iodine laser pulses

1993 ◽  
Vol 10 (6) ◽  
pp. 1040 ◽  
Author(s):  
H. Schillinger ◽  
K. J. Witte
Keyword(s):  
Laser Pulses ◽  
Iodine Laser

scholarly journals Bremsstrahlung emission profile from intense laser-solid interactions as a function of laser focal spot size

2019 ◽  
Vol 61 (3) ◽  
pp. 034001 ◽  
Author(s):  
C D Armstrong ◽  
C M Brenner ◽  
E Zemaityte ◽  
G G Scott ◽  
D R Rusby ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Intense Laser ◽  
Focal Spot Size ◽  
Emission Profile ◽  
Bremsstrahlung Emission ◽  
Laser Focal Spot ◽  
Laser Solid Interactions

scholarly journals Preparation and Characterization of Lead Oxide Nanoparticles by Laser Ablation as Antibacterial Agent

2017 ◽  
Vol 14 (4) ◽  
pp. 801-807
Author(s):  
Baghdad Science Journal
Keyword(s):  
Laser Ablation ◽  
Lead Oxide ◽  
Laser Energy ◽  
Laser Pulses ◽  
Diffusion Method ◽  
Lead Target ◽  
Oxide Nanoparticles ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

In this work, lead oxide nanoparticles were prepared by laser ablation of lead target immersed in deionized water by using pulsed Nd:YAG laser with laser energy 400 mJ/pulse and different laser pulses. The chemical bonding of lead oxide nps was investigated by Fourier Transform Infrared (FTIR); surface morphology and optical properties were investigated by Scanning Electron Microscope (SEM) and UV-Visible spectroscopy respectively, and the size effect of lead oxide nanoparticles was studied on its antibacterial action against two types of bacteria Gram-negitive (Escherichia coli) and Gram-positive (Staphylococcusaurus) by diffusion method. The antibacterial property results show that the antibacterial activity of the Lead oxide NPs was inversely proportional to the size of the nanoparticles in both Gram-negative and Gram-positive, and also it has been found that Gram-positive bacteria possess have greater sensitivity and less resistance to the lead oxide nanoparticles compared with Gram-negative bacteria.

scholarly journals Numerical simulation of a plasmonic lens for laser light focusing

2021 ◽  
Vol 2103 (1) ◽  
pp. 012174
Author(s):  
E S Kozlova ◽  
V V Kotlyar
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Incident Light ◽  
Lens Design ◽  
Light Wavelength ◽  
Optimal Parameters ◽  
Plasmonic Lens ◽  
Radial Polarization ◽  
Incident Light Wavelength ◽  
Difference Time

Abstract In this paper, the design of a plasmonic lens in gold and silver thin films for focusing the light with radial polarization is presented. Using the finite difference time domain method the optimal parameters of the plasmonic lens design are found. It was shown that the silver plasmonic lens produces a tight focal spot with a full width at half maximum of 0.38 of the incident light wavelength.

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