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 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 Nanosecond Laser Etching of Aluminum-Plated Composite Materials Applied to Frequency Selective Surfaces

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2808
Author(s):  
Jian Cheng ◽  
Shufeng Jing ◽  
Deyuan Lou ◽  
Qibiao Yang ◽  
Qing Tao ◽  
...  
Keyword(s):  
Composite Materials ◽  
Laser Pulse ◽  
Focal Spot ◽  
Incident Angle ◽  
Spot Size ◽  
Nanosecond Laser ◽  
Frequency Selective Surfaces ◽  
Laser Etching ◽  
Focal Spot Size ◽  
Frequency Selective

High-quality frequency selective surfaces (FSSs) are important for electromagnetic signal absorption/filtration. Usually, they are made from wave-transparent composite materials covered with a thin metal layer. Current machining methods show some disadvantages when performing fabrication on the structure. Based on its flexibility and uncontactable processing characteristics, nanosecond laser etching of aluminum-plated composite materials applied to FSSs was investigated. To observe the influence of the laser light incident angle, etching of a series of square areas with different incident angles was performed. Thereafter, an image processing method, named the image gray variance (IGV), was employed to perform etching quality evaluation analysis. The observed microscopic pictures of experimental samples were consistent with those of the IGV evaluation. The potential reasons that might affect the etching quality were analyzed. Following all the efforts above, an incident angle range of ±15° was recommended, and the best etching result was obtained at the incident angle of 10°. To observe the influence of the laser pulse overlap and focal spot size on the etched area border uniformity and on the potential damage to the base materials, a theoretical equation was given, and then its prediction of area border edge burrs fluctuation was compared with the experiments. Furthermore, SEM pictures of etched samples were examined. Based on the study, a processing window of the laser pulse overlap and focal spot size was recommended. To conclude, optimal etching results of the FSS materials could be guaranteed by using the right laser operating parameters with the nanosecond laser.

Optimizing laser focal spot size using self-focusing in a cone-guided fast-ignition ICF target

2021 ◽  
Vol 136 (5) ◽  
Author(s):  
Oriza Kamboj ◽  
Harjit Singh Ghotra ◽  
Vishal Thakur ◽  
John Pasley ◽  
Niti Kant
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Fast Ignition ◽  
Focal Spot Size ◽  
Self Focusing ◽  
Laser Focal Spot ◽  
Icf Target

Laser Pulse Simulation of High Energy Transient Thermal Loads on Bulk and Plasma Sprayed W for NFR

2016 ◽  
Vol 879 ◽  
pp. 1576-1581 ◽  
Author(s):  
Maria Richetta ◽  
Pasquale Gaudio ◽  
Roberto Montanari ◽  
Ekaterina Pakhomova ◽  
Luca Antonelli
Keyword(s):  
Laser Pulse ◽  
Focal Plane ◽  
Focal Spot ◽  
Spot Size ◽  
High Energy ◽  
Fusion Reactors ◽  
Thermal Loads ◽  
Focal Spot Size ◽  
Plasma Sprayed ◽  
Transient Thermal

W is a plasma-facing material candidate for applications in future nuclear fusion reactors (NFR). In this work transient thermal loads of high energy have been simulated by interaction with a single laser pulse. The experiments have been carried out by using the Nd:Glass TVLPS laser working in first harmonic (wavelength λ = 1064 nm); the pulse parameters are: energy E ≈ 8 J, pulse duration ∆t ≈ 15 ns, focal spot size Φ = 200 μm, surface power density on the focal plane I = 1.7 x 1012 W/cm2.The damage produced by the laser pulse on the surface of bulk and plasma sprayed W has been investigated by Scanning Electron Microscopy (SEM) observations. The preliminary results will be presented.

scholarly journals High energy heavy ion jets emerging from laser plasma generated by long pulse laser beams from the NHELIX laser system at GSI

2005 ◽  
Vol 23 (4) ◽  
pp. 503-512 ◽  
Author(s):  
G. SCHAUMANN ◽  
M.S. SCHOLLMEIER ◽  
G. RODRIGUEZ-PRIETO ◽  
A. BLAZEVIC ◽  
E. BRAMBRINK ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Laser Energy ◽  
Laser System ◽  
Heavy Ion ◽  
Spot Size ◽  
High Energy ◽  
Focal Spot Size ◽  
Laser Systems ◽  
Order Of Magnitude ◽  
Long Pulse

High energy heavy ions were generated in laser produced plasma at moderate laser energy, with a large focal spot size of 0.5 mm diameter. The laser beam was provided by the 10 GW GSI-NHELIX laser systems, and the ions were observed spectroscopically in status nascendi with high spatial and spectral resolution. Due to the focal geometry, plasma jet was formed, containing high energy heavy ions. The velocity distribution was measured via an observation of Doppler shifted characteristic transition lines. The observed energy of up to 3 MeV of F-ions deviates by an order of magnitude from the well-known Gitomer (Gitomer et al., 1986) scaling, and agrees with the higher energies of relativistic self focusing.

scholarly journals Laser assisted bioprinting at different wavelengths and pulse durations with a metal dynamic release layer: A parametric study

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Lothar Koch ◽  
Ole Brandt ◽  
Andrea Deiwick ◽  
Boris Chichkov
Keyword(s):  
Laser Pulse ◽  
Focal Spot ◽  
Femtosecond Lasers ◽  
Metal Layer ◽  
Laser Pulses ◽  
Spot Size ◽  
Laser Wavelength ◽  
Focal Spot Size ◽  
Gold Silver ◽  
Absorbing Material

 For more than a decade living cells and biomaterials (typically hydrogels) have been printed with laser-assisted bioprinting. Often, a thin metal layer is applied as laser-absorbing material, called dynamic release layer (DRL). This layer is vaporized by focused laser pulses generating vapor pressure that propels forward a coated biomaterial. Different lasers with laser wavelengths from 193 to 1064 nanometer have been used. As a metal DRL gold, silver, or titanium layers have been used. The applied laser pulse durations were usually in the nanosecond range from 1 to 30 ns. In addition, some studies with femtosecond lasers have been published. However, there are no studies on the effect of all these lasers parameters on bioprinting with a metal DRL, comparing different wavelengths and pulse durations – except one study comparing 500 femtosecond pulses with 15 ns pulses. In this paper, the effects of laser wavelength (355, 532, and 1064 nm) and laser pulse duration (in the range of 8 to 200 ns) are investigated. Furthermore, the effects of laser pulse energy, intensity, and focal spot size are studied. The printed droplet volume, hydrogel jet velocity, and cell viability are analyzed.

Computational Technique for the Qualification of Focal Spot Size and Shape of Industrial Radioscopy Equipment Using Star Patterns

2020 ◽  
Vol 78 (4) ◽  
pp. 479-486
Author(s):  
Marcela Tatiana Fernandes Beserra ◽  
◽  
Ricardo Tadeu Lopes ◽  
Davi Ferreira de Oliveira ◽  
Claudio Carvalho Conti ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Computational Technique ◽  
Focal Spot Size ◽  
Size And Shape

The determination of the focal spot size of an X-ray tube from the radiation beam profile

2015 ◽  
Vol 82 ◽  
pp. 138-145 ◽  
Author(s):  
A.D. Oliveira ◽  
M.J. Fartaria ◽  
J. Cardoso ◽  
L.M. Santos ◽  
C. Oliveira ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Beam Profile ◽  
Focal Spot Size ◽  
Radiation Beam ◽  
X Ray

scholarly journals Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Manzoor Ahmad Wani ◽  
Niti Kant
Keyword(s):  
Laser Beam ◽  
Plasma Density ◽  
Focal Spot ◽  
Beam Width ◽  
Spot Size ◽  
Laser Beams ◽  
Equation Approach ◽  
Focal Spot Size ◽  
Self Focusing ◽  
Small Spot

Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot size. Plasma density ramp plays an important role in reducing the defocusing effect and maintaining the focal spot size up to several Rayleigh lengths. To discuss the nature of self-focusing, the behaviour of beam-width parameters with dimensionless distance of propagation for various values of decentered parameters is examined by numerical estimates. The results are presented graphically and the effect of plasma density ramp and decentered parameter on self-focusing of the beams has been discussed.

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