scholarly journals Laser-impact-induced splashing: an analysis of the splash crown evolution after Nd:YAG ns-pulse laser impact on a liquid tin pool

2021 ◽  
Vol 127 (3) ◽  
Author(s):  
J. Hermens ◽  
H. Gelderblom ◽  
B. Liu ◽  
J. Duffhues ◽  
P. Rindt ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Extreme Ultraviolet ◽  
Laser Energy ◽  
Spot Size ◽  
Intense Laser ◽  
Expansion Velocity ◽  
Laser Fluences ◽  
Crown Width ◽  
Laser Impact ◽  
Liquid Tin

AbstractThe splash created by intense laser pulse impact onto a liquid tin layer is studied experimentally using time-delayed stroboscopic shadowgraphy. An 8-ns infrared (1064 nm) laser pulse is focused onto a deep liquid tin pool. Various laser spot sizes (70, 120, and 130 $$\upmu$$ μ m in diameter) and various laser pulse energies (ranging 2.5–30 mJ) are used, resulting in laser fluences of $$\sim$$ ∼  10–1000 J/cm$$^2$$ 2 inducing pronounced splashing. Specifically, we study the time evolution of the splash crown-width. The crown width expansion velocity is found to be linearly dependent on the laser energy, and independent of the focal spot size. A collapse of all crown width evolution data onto a single master curve confirms that the hydrodynamic evolution of our laser-impact-induced splash is equivalent to droplet-impact-induced splashing. Laser-impact splashing is particularly relevant, e.g. for high-brightness laser-assisted discharge-produced plasma and laser-produced plasma sources of extreme ultraviolet light for nanolithography.

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.

Effect of obliquely external magnetic field on the intense laser pulse propagating in plasma medium

2020 ◽  
Vol 34 (07) ◽  
pp. 2050044
Author(s):  
Mehdi Abedi-Varaki
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Laser Pulse ◽  
Magnetoactive Plasma ◽  
Spot Size ◽  
The Self ◽  
Intense Laser ◽  
Intense Laser Pulse ◽  
Laser Spot Size ◽  
Self Focusing

In this paper, self-focusing of intense laser pulse propagating along the obliquely external magnetic field on the collisional magnetoactive plasma by using the perturbation theory have been studied. The wave equation describing the interaction of intense laser pulse with collisional magnetoactive plasma is derived. In addition, employing source-dependent expansion (SDE) method, the analysis of the laser spot-size is discussed. It is shown that with increasing of the angle in obliquely external magnetic field, the spot-size of laser pulse decreases and as a result laser pulse becomes more focused. Furthermore, it is concluded that the self-focusing quality of the laser pulse has been enhanced due to the presence of obliquely external magnetic field in the collisional magnetoactive plasma. Besides, it is seen that with increasing of [Formula: see text], the laser spot-size reduces and subsequently the self-focusing of the laser pulse in plasma enhances. Moreover, it is found that changing the collision effect in the magnetoactive plasma leads to increases of self-focusing properties.

scholarly journals Self focusing of a laser pulse in plasma with periodic density ripple

2009 ◽  
Vol 27 (2) ◽  
pp. 193-199 ◽  
Author(s):  
Sukhdeep Kaur ◽  
A.K. Sharma
Keyword(s):  
Laser Pulse ◽  
Spot Size ◽  
High Plasma ◽  
The Self ◽  
Intense Laser ◽  
Wave Number ◽  
Plasma Parameters ◽  
Density Region ◽  
Focusing Effect ◽  
Self Focusing

AbstractPropagation of an intense laser pulse in plasma with a periodically modulated density is considered using envelope equations. The laser induces modifications of the plasma refractive indexviarelativistic and ponderomotive nonlinearities. In the region of high plasma density, the self focusing effect of nonlinearity suppresses the diffraction divergence, and the laser converges. As the beam enters into the low density region, the diffraction tends to diverge it offsetting the convergence due to the curvature it has acquired. For a given set of plasma parameters, there is a critical power of the laser above which it propagates in a periodically focused manner. Below this power the laser undergoes overall divergence. At substantially higher powers, the laser beam continues to converge until the saturation effect of nonlinearity suppresses the self focusing and diffraction predominates. The effect of density ripple is to cause overall increase in the self focusing length. The minimum spot size decreases with the wave number of the ripple.

scholarly journals Simulation of optical breakdown in nitrogen by focused short laser pulses of 1064 nm wavelength

2008 ◽  
Vol 26 (4) ◽  
pp. 567-573 ◽  
Author(s):  
G. Tartar ◽  
H. Ranner ◽  
F. Winter ◽  
E. Wintner
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Dynamic Process ◽  
Collision Cross Section ◽  
Optical Breakdown ◽  
Initial Pressure ◽  
Spot Size ◽  
Laser Wavelength ◽  
Intense Laser ◽  
Electron Recombination

AbstractA kinetic model of electron cascade growth in the electromagnetic field of a focused intense laser pulse as used for laser spark generation in gases has been numerically implemented in Visual C code. The effects considered comprise Drude absorption, diffusive kinetic and inelastic losses as well as (three-particle) electron recombination. The objectives were to illustrate the dynamic process of gas ionization, and to clarify the pressure dependence of known breakdown thresholds within a range of about 2 × 104 to 2 × 106 Pa of initial pressure. Two-dimensional (cylindric coordinates) simulations of the optical breakdown in nitrogen were conducted on a commercial PC, using constant values for the collision cross section (2 × 10−19 m2), prevalent electronic excitation states (~4.8 eV), and a laser wavelength of 1064 nm. A certain aerosol concentration on the order of 3 ppb was assumed in order to provide initial electrons for cascade growth. Exemplary results with laser pulse energy of 26 mJ, pulse duration of 14 ns and an 18 µm focal spot size illustrate the dynamic process of ionization within a very short time period of less than 0.5 ns. The kinetic energy of the electrons is found to increase sharply up to more than 100,000 K on breakdown. A series of simulations considered the minimum pulse energy of breakdown (MPE) under variation of initial pressure. Identical laser parameters as in experiments conducted previously were used and the results are in excellent agreement with respect to curve shapes, i.e., MPE ~1/p0.4 in the first experiment and MPE ~1/p0.3 in the second one. The absolute values lie within a factor of two, which is explained by model abstraction and input data uncertainties.

scholarly journals Ultra-intense laser pulses in near-critical underdense plasmas – radiation reaction and energy partitioning

2017 ◽  
Vol 83 (2) ◽  
Author(s):  
Erik Wallin ◽  
Arkady Gonoskov ◽  
Christopher Harvey ◽  
Olle Lundh ◽  
Mattias Marklund
Keyword(s):  
Laser Pulse ◽  
Pulse Propagation ◽  
Laser Energy ◽  
Radiation Reaction ◽  
Laser Pulses ◽  
High Energy ◽  
Intense Laser ◽  
Long Distance ◽  
Weakly Nonlinear ◽  
Highly Nonlinear

Although, for current laser pulse energies, the weakly nonlinear regime of laser wakefield acceleration is known to be the optimal for reaching the highest possible electron energies, the capabilities of upcoming large laser systems will provide the possibility of running highly nonlinear regimes of laser pulse propagation in underdense or near-critical plasmas. Using an extended particle-in-cell (PIC) model that takes into account all the relevant physics, we show that such regimes can be implemented with external guiding for a relatively long distance of propagation and allow for the stable transformation of laser energy into other types of energy, including the kinetic energy of a large number of high energy electrons and their incoherent emission of photons. This is despite the fact that the high intensity of the laser pulse triggers a number of new mechanisms of energy depletion, which we investigate systematically.

scholarly journals Enhancement of extreme ultraviolet emission from laser irradiated targets by surface nanostructures

2017 ◽  
Vol 35 (4) ◽  
pp. 574-578 ◽  
Author(s):  
E. F. Barte ◽  
R. Lokasani ◽  
J. Proska ◽  
L. Maresova ◽  
D. Kos ◽  
...  
Keyword(s):  
Surface Layer ◽  
Laser Pulse ◽  
Conversion Efficiency ◽  
Extreme Ultraviolet ◽  
Laser Energy ◽  
Porous Alumina ◽  
Reflection Band ◽  
Ultraviolet Emission ◽  
Surface Nanostructures ◽  
Neodymium:Yttrium Aluminum Garnet Laser

AbstractThe effects of shape and thickness of a tin surface layer and of the energy of a 170 ps neodymium:yttrium-aluminum-garnet laser pulse on the conversion efficiency (CE) into extreme ultraviolet emission in the 13.5 nm region is investigated. Whereas a CE of up to 1.16% into the 2% reflection band of multilayer Mo/Si optics was measured for a bulk Sn target at a laser energy of 25 mJ, significant CE enhancement up to 1.49% is demonstrated for a 200-nm-thick Sn layer on a microstructured porous alumina substrate.

scholarly journals Radial density profile and stability of capillary discharge plasma waveguides of lengths up to 40 cm

2021 ◽  
Vol 9 ◽  
Author(s):  
M. Turner ◽  
A. J. Gonsalves ◽  
S. S. Bulanov ◽  
C. Benedetti ◽  
N. A. Bobrova ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Electron Density ◽  
Density Profile ◽  
Pulse Propagation ◽  
Spot Size ◽  
Capillary Discharge ◽  
Electron Density Profile ◽  
Plasma Waveguide ◽  
Wakefield Acceleration ◽  
Plasma Wakefield

Abstract We measured the parameter reproducibility and radial electron density profile of capillary discharge waveguides with diameters of 650 $\mathrm{\mu} \mathrm{m}$ to 2 mm and lengths of 9 to 40 cm. To the best of the authors’ knowledge, 40 cm is the longest discharge capillary plasma waveguide to date. This length is important for $\ge$ 10 GeV electron energy gain in a single laser-driven plasma wakefield acceleration stage. Evaluation of waveguide parameter variations showed that their focusing strength was stable and reproducible to $<0.2$ % and their average on-axis plasma electron density to $<1$ %. These variations explain only a small fraction of laser-driven plasma wakefield acceleration electron bunch variations observed in experiments to date. Measurements of laser pulse centroid oscillations revealed that the radial channel profile rises faster than parabolic and is in excellent agreement with magnetohydrodynamic simulation results. We show that the effects of non-parabolic contributions on Gaussian pulse propagation were negligible when the pulse was approximately matched to the channel. However, they affected pulse propagation for a non-matched configuration in which the waveguide was used as a plasma telescope to change the focused laser pulse spot size.

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