Effects of preplasma scale length and critical surface dynamics on laser energy coupling to hot electrons

2012 ◽  
Author(s):  
R. J. Gray ◽  
D. C. Carroll ◽  
X. H. Yuan ◽  
C. M. Brenner ◽  
M. Burza ◽  
...  
Keyword(s):  
Laser Energy ◽  
Energy Coupling ◽  
Hot Electrons ◽  
Critical Surface ◽  
Surface Dynamics ◽  
Scale Length

Raman scattering

1986 ◽  
Vol 64 (8) ◽  
pp. 956-960 ◽  
Author(s):  
Albert Simon
Keyword(s):  
Raman Scattering ◽  
Alternative Explanation ◽  
Stimulated Raman Scattering ◽  
Scattered Light ◽  
Hot Electrons ◽  
Critical Surface ◽  
Laser Produced Plasma ◽  
Stimulated Raman

Observations of Raman scattered light from inhomogeneous laser-produced plasma have shown characteristics quite different from the simple predictions for the stimulated Raman scattering instability. An alternative explanation in terms of enhanced scattering, produced by bursts of hot electrons arising at the quarter-critical or critical surface, is described. Comparison is made between the predictions of this theory and four experiments.

Temporal Pulse Shaping and Optimization in Ultrafast Laser Ablation of Materials

2003 ◽  
Vol 780 ◽  
Author(s):  
R. Stoian ◽  
S. Winkler ◽  
M. Hildebrand ◽  
M. Boyle ◽  
A. Thoss ◽  
...  
Keyword(s):  
Pulse Shaping ◽  
Laser Energy ◽  
Energy Coupling ◽  
Laser Pulses ◽  
Ultrafast Laser ◽  
Ultrashort Laser Pulses ◽  
Adaptive Optimization ◽  
Ultrafast Laser Pulses ◽  
Energy Delivery ◽  
Optimal Processing

The possibility of phase manipulation and temporal tailoring of ultrashort laser pulses enables new opportunities for optimal processing of materials. Phase-manipulated ultrafast laser pulses allow adapting the laser energy delivery rate to the material properties for optimal processing laying the groundwork for adaptive optimization in materials structuring. Different materials respond with specific reaction pathways to the sudden energy input depending on the efficiency of electron generation and on the ability to release the energy into the lattice. The sequential energy delivery with judiciously chosen pulse trains may induce softening of the material during the initial steps of excitation and change the energy coupling for the subsequent steps. We show that this can result in lower stress, cleaner structures, and allow for a materialdependent optimization process.

scholarly journals Enhanced laser-energy coupling to dense plasmas driven by recirculating electron currents

2018 ◽  
Vol 20 (3) ◽  
pp. 033021 ◽  
Author(s):  
R J Gray ◽  
R Wilson ◽  
M King ◽  
S D R Williamson ◽  
R J Dance ◽  
...  
Keyword(s):  
Laser Energy ◽  
Energy Coupling ◽  
Dense Plasmas

Numerical study of the effect of laser-arc distance on laser energy coupling in pulsed Nd: YAG laser/TIG hybrid welding

2016 ◽  
Vol 91 (1-4) ◽  
pp. 1129-1143 ◽  
Author(s):  
Jie Ning ◽  
Lin-Jie Zhang ◽  
Suck-Joo Na ◽  
Xian-Qing Yin ◽  
Jing Niu ◽  
...  
Keyword(s):  
Laser Energy ◽  
Numerical Study ◽  
Energy Coupling ◽  
Hybrid Welding ◽  
Yag Laser ◽  
Arc Distance

scholarly journals A pulsed-power implementation of “Laser Gate” for increasing laser energy coupling and fusion yield in magnetized liner inertial fusion (MagLIF)

2020 ◽  
Vol 91 (6) ◽  
pp. 063507
Author(s):  
S. M. Miller ◽  
S. A. Slutz ◽  
S. N. Bland ◽  
S. R. Klein ◽  
P. C. Campbell ◽  
...  
Keyword(s):  
Laser Energy ◽  
Energy Coupling ◽  
Pulsed Power ◽  
Inertial Fusion ◽  
Fusion Yield

Study of femtosecond laser pulse induced shockwave in aluminum-coated dielectric target

2020 ◽  
Vol 91 (1) ◽  
pp. 10801
Author(s):  
Chuliang Zhou ◽  
Yafeng Bai ◽  
Zhongpeng Li ◽  
Yingying Ding ◽  
Haiyi Sun ◽  
...  
Keyword(s):  
Shock Wave ◽  
Laser Pulse ◽  
Femtosecond Laser ◽  
Time Scale ◽  
Laser Energy ◽  
Contrast Ratio ◽  
Nanosecond Time Scale ◽  
Dielectric Target ◽  
Overdense Plasma ◽  
Scale Length

The influence of the preplasma on laser induced shockwave in the laser and aluminum-coated planar dielectric target interaction at vacuum has been investigated with the shadowgraphy method. While the laser irradiate on the aluminum-coated dielectric target at intensity of about 1017 W/cm2, the metallic layers absorb laser energy, evaporate and ionize into plasma, it is verified that the scale length of laser-produced plasma is dramatically dependent on the contrast ratio of femtosecond-laser while the main laser pulse energy is almost kept. The characteristics of laser induced shock wave in nanosecond time scale were studied. In the nanosecond time scale, shock wave is only observed in the case of relatively short plasma scale length. This result can be explained by the dissipation of the shock wave during its propagation in the preplasma. In addition, we performed numerical simulation with MULTI2D to get an insight into the propagation of shock wave in the overdense plasma [R. Ramis, J. Meyer-ter-Vehn, and J. Ramírez, Comput. Phys. Commun. 180, 977 (2009)].

scholarly journals An Analytical Model for Estimating the Bending Curvatures of Metal Sheets in Laser Peen Forming

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 462
Author(s):  
Yunxia Ye ◽  
Zeng Nie ◽  
Xu Huang ◽  
Xudong Ren ◽  
Lin Li
Keyword(s):  
Analytical Model ◽  
Laser Energy ◽  
Stress Gradient ◽  
Energy Coupling ◽  
Complex Stress ◽  
Force Balance ◽  
Thin Plates ◽  
Forming Process ◽  
2024 Aluminum Alloy ◽  
Peen Forming

Laser peen forming (LPF) is suitable for shaping sheet metals without the requirement for die/mold and without causing high temperatures. An analytical model for estimating the bending curvatures of LPF is convenient and necessary for better understanding of the physical processes involved. In this paper, we describe a new analytical model based on internal force balance and the energy transformation in LPF. Experiments on 2024 aluminum alloy sheets of 1–3 mm thickness were performed to validate the analytical model. The results showed that for 1 mm and 3 mm thick–thin plates, the curvature obtained by the analytical model changes from −14 × 10−4 mm−1 and −1 × 10−4 mm−1 to 55 × 10−4 mm−1 and −21 × 10−4 mm−1, respectively, with the increase of laser energy, which is consistent with the experimental trend. So, when either the stress gradient mechanism (SGM) or the shock bending mechanism (SBM) overwhelmingly dominated the forming process, the analytical model could give relatively accurate predicted curvatures compared with the experimental data. Under those conditions where SGM and SBM were comparable, the accuracy of the model was low, because of the complex stress distributions within the material, and the complex energy coupling process under these conditions.

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