scholarly journals Backward Flux Re-Deposition Patterns during Multi-Spot Laser Ablation of Stainless Steel with Picosecond and Femtosecond Pulses in Air

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2243
Author(s):  
Tong Zhou ◽  
Sebastian Kraft ◽  
Walter Perrie ◽  
Jörg Schille ◽  
Udo Löschner ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Pulses ◽  
Ambient Air ◽  
Beam Splitting ◽  
Light Modulator ◽  
Interesting Phenomenon ◽  
Close Proximity ◽  
Plasma Plumes ◽  
Micro Structuring ◽  
Axes Of Symmetry

We report on novel observations of directed re-deposition of ablation debris during the ultrafast laser micro-structuring of stainless steel in the air with multi-beams in close proximity on the surface. This interesting phenomenon is observed with both 10 ps and 600 fs NIR laser pulses at 5 kHz repetition rate. Ablation spot geometries could be altered with the use of beam splitting optics or a phase-only Spatial Light modulator. At low fluence (F ~ 1.0 J cm−2) and pulse exposure of a few hundred pulses, the debris appears as concentrated narrow “filaments” connecting the ablation spots, while at higher fluence, (F ~ 5.0 J cm−2) energetic jets of material emanated symmetrically along the axes of symmetry, depositing debris well beyond the typical re-deposition radius with a single spot. Patterns of backward re-deposition of debris to the surface are likely connected with the colliding shock waves and plasma plumes with the ambient air causing stagnation when the spots are in close proximity. The 2D surface debris patterns are indicative of the complex 3D interactions involved over wide timescales during ablation from picoseconds to microseconds.

scholarly journals High-quality percussion drilling with ultrashort laser pulses

2021 ◽  
Vol 127 (9) ◽  
Author(s):  
A. Feuer ◽  
R. Weber ◽  
R. Feuer ◽  
D. Brinkmeier ◽  
T. Graf
Keyword(s):  
Stainless Steel ◽  
Laser Fluence ◽  
Ablation Threshold ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
High Quality ◽  
Edge Quality ◽  
Ultrashort Laser ◽  
Percussion Drilling

AbstractThe influence of the laser fluence on the quality of percussion-drilled holes was investigated both experimentally and by an analytical model. The study reveals that the edge quality of the drilled microholes depends on the laser fluence reaching the rear exit of the hole and changes with the number of pulses applied after breakthrough. The minimum fluence that must reach the hole’s exit in order to obtain high-quality microholes in stainless steel was experimentally found to be 2.8 times the ablation threshold.

Formation of Periodical Sub-Micron Sized Structures on Silicon by Interfered Nanosecond Laser Pulses

2010 ◽  
Vol 97-101 ◽  
pp. 3803-3806
Author(s):  
Yong Xiang Hu ◽  
Heng Zhang ◽  
Zheng Qiang Yao
Keyword(s):  
Cost Effective ◽  
Laser Pulses ◽  
Laser Beams ◽  
Nanosecond Laser ◽  
Effective Technique ◽  
First Order ◽  
Direct Fabrication ◽  
Cost Effective Technique ◽  
Nanosecond Laser Pulses ◽  
Micro Structuring

Laser interference micro-structuring is a relatively efficient and cost-effective technique for fabricating periodical micro-nano-structuring surfaces. The direct fabrication of sub-micron sized dot array on silicon was performed by four interfering nanosecond laser beams with a diffractive beam splitter. The mechanism to form the dot array was analyzed and it was found that the obtained conical dot array had a negative shape of the interference pattern of four laser beams. A second-order peak between two first-order peaks also occurred due to the liquid-solid expansion.

Study of ambient air ionization with femtosecond laser pulses

2005 ◽  
Author(s):  
Yi Wang ◽  
Xiaolei Wang ◽  
Nan Zhang ◽  
Hongchen Zhai ◽  
Xiaonong Zhu
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Ambient Air ◽  
Femtosecond Laser Pulses ◽  
Air Ionization

Effect of Focusing Plane on Laser Blow-off Shock Waves from Confined Aluminum and Copper Foils

2021 ◽  
Author(s):  
Nagaraju Guthikonda ◽  
Sai Shiva S ◽  
E. Manikanta ◽  
Kameswari P S L D ◽  
V. R. Ikkurthi ◽  
...  
Keyword(s):  
Laser Energy ◽  
Plasma Temperature ◽  
Laser Pulses ◽  
Ambient Air ◽  
Rear Side ◽  
Hydrodynamic Simulations ◽  
Enhanced Absorption ◽  
532 Nm ◽  
Lower Plasma Density ◽  
Good Agreement

Abstract We present results on the dynamics of laser-induced blow-off shockwave generation from the rear side of 20 µm thick aluminum and copper foil confined with a glass (BK7) substrate. These foils are irradiated by 10 ns, 532 nm laser pulses of energy 25 – 200 mJ corresponding to the intensity range 0.2 – 10 GW/cm2. The plasma temperature at the glass-foil interface is observed to play an important role in the coupling of laser energy to the foil. From our experiments and 1D hydrodynamic simulations, we confirm that moving the glass-foil interface away from the focal plane led to (a) enhanced absorption of the laser beam by the foil resulting in ~ 30 % higher blow-off shock velocities (b) significant changes in the material ejection in terms of increased blow-off mass of the foil (c) lower plasma density and temperatures. The material ejection as well as blow-off shock velocity is higher for Al compared to Cu. The simulated shock evolution in ambient air shows a reasonably good agreement with the experimental results.

scholarly journals X-ray emission from stainless steel foils irradiated by femtosecond petawatt laser pulses

2018 ◽  
Vol 946 ◽  
pp. 012018 ◽  
Author(s):  
M A Alkhimova ◽  
A Ya Faenov ◽  
T A Pikuz ◽  
I Yu Skobelev ◽  
S A Pikuz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Pulses ◽  
X Ray ◽  
Stainless Steel Foils ◽  
Steel Foils

scholarly journals Spatial biomonitoring of airborne heavy metals emitted from a steel recycling plant

2020 ◽  
Vol 31 (3) ◽  
pp. 548-563
Author(s):  
Abayomi Isaac Adeleke ◽  
Bamidele Sunday Fakinle ◽  
Olayemi Abosede Odunlami ◽  
Jacob Ademola Sonibare
Keyword(s):  
Heavy Metals ◽  
Ambient Air ◽  
Abundant Species ◽  
Pollution Indices ◽  
Recycling Process ◽  
Content Type ◽  
Metal Recycling ◽  
Close Proximity ◽  
Metal Flux

PurposeThe study investigated the heavy metal flux around the vicinity of a steel recycling factory using passive biomonitoring technique with several pollution indices to assess the quality of the ambient environment.Design/methodology/approachThe vegetation around the facility was identified, and the most abundant species were selected for analysis. The collected samples were dried, milled, sieved and analyzed for elemental composition using energy dispersive X-ray fluorescence (ED-XRF). Pollution indices were used to quantitatively assess the data.FindingsResults show that maximum contamination occurs at the vicinity of factory. Generally, the deterioration of the ambient air around the vicinity of the steel recycling plant decreases with increasing distance from the steel recycling plant. However, for the radius considered in this study – 1 km, the ambient air at 1 km of the steel recycling facility is quickly deteriorating, and there is an urgent need for measures to mitigate the air quality impact of the steel recycling facility.Originality/valueThe study shows that the metal recycling process emits high levels of heavy metals to the environment, and there is an urgent need for personal protective equipment for the human population working in and around the close proximity of the recycling plant.

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