Nanodomain shock wave in near-field laser–material interaction

2007 ◽  
Vol 369 (4) ◽  
pp. 323-327 ◽  
Author(s):  
Xuhui Feng ◽  
Xinwei Wang
Keyword(s):  
Shock Wave ◽  
Near Field ◽  
Laser Material ◽  
Material Interaction

Characteristics of Nanopatterns and the Associated Thermal Mechanisms During Near Field Laser-Material Interaction of Nanosecond Laser on Different Targets

2009 ◽  
Author(s):  
Vijay M. Sundaram ◽  
Sy-Bor Wen
Keyword(s):  
Near Field ◽  
Target Material ◽  
Optical Microscope ◽  
Laser Source ◽  
Nanosecond Laser ◽  
Metallic Surfaces ◽  
Experimental Conditions ◽  
Laser Material ◽  
Material Conditions ◽  
Material Interaction

Nano-patterns are generated on semiconducting and metallic surfaces through coupling an apertured near field scanning optical microscope (NSOM) with a pulsed laser source in this study. To understand the dominant mechanisms for the generation of the nano-patterns, a series of experimental measurement of the size and shape of nano-patterns generated on targets under different experimental conditions with different targets is conducted. The characteristic dimensions of nano-patterns show dependence on optical properties of the target material. The qualitative trend of the variation of nano-patterns as a function of laser and material conditions indicates that the dominant mechanisms for the generation of nano-patterns through a combination of nanosecond laser and an apertured NSOM under different conditions studied is near field laser-material interaction.

Shock Waves in Pulsed Laser Material Interaction: Internal Structure and Mass Penetration

2008 ◽  
Author(s):  
Lijun Zhang ◽  
Xinwei Wang
Keyword(s):  
Shock Wave ◽  
Wave Front ◽  
Shock Wave Front ◽  
Picosecond Laser ◽  
Mixing Length ◽  
Momentum Exchange ◽  
Laser Material ◽  
Ambient Gas ◽  
Background Gas ◽  
Material Interaction

This work pioneers the atomistic modeling of the shock wave in picosecond laser-material interaction by simulating the material that is irradiated with a picosecond laser pulse (11.3 ps FWHM) in a 0.25 MPa background gas. The dynamic structure and mutual mass penetration between the plume and background gas are investigated in detail. In the shock wave the compressed ambient gas region has a very uniform temperature distribution while the temperature decreases from the front of the plume to its end. The group velocity of atoms in the shock wave front is much smaller than the shock wave propagation speed and experiences a fast decay due to momentum exchange with the ambient gas. Strong decay of the shock wave front temperature and pressure is observed while its density features much slower attenuation. An effective mixing length is designed to quantitatively evaluate the mutual mass penetration between the plume and background gas. This effective mixing length grows at a rate of ∼ 60 m/s. This fast mixing/mass penetration is largely due to the strong relative movement between the plume and the background gas. The MD results agree well with the analytical solution in terms of relating various shock wave strengths.

Secondary shock wave in laser-material interaction

2008 ◽  
Vol 104 (12) ◽  
pp. 126101 ◽  
Author(s):  
Sobieslaw Gacek ◽  
Xinwei Wang
Keyword(s):  
Shock Wave ◽  
Laser Material ◽  
Secondary Shock ◽  
Material Interaction

Plume splitting in pico-second laser–material interaction under the influence of shock wave

2009 ◽  
Vol 373 (37) ◽  
pp. 3342-3349 ◽  
Author(s):  
Sobieslaw Gacek ◽  
Xinwei Wang
Keyword(s):  
Shock Wave ◽  
Laser Material ◽  
Material Interaction

scholarly journals Simulation of the laser-material interaction of ultrashort pulse laser processing of silicon nitride workpieces and the key factors in the ablation process

2021 ◽  
Author(s):  
Babak Soltani ◽  
Faramarz Hojati ◽  
Amir Daneshi ◽  
Bahman Azarhoushang
Keyword(s):  
Mathematical Model ◽  
Laser Ablation ◽  
Pulse Laser ◽  
Ultrashort Pulse ◽  
Laser Processing ◽  
Laser Power ◽  
Removal Rate ◽  
Ultrashort Pulse Laser ◽  
Laser Material ◽  
Material Interaction

AbstractUnderstanding the laser ablation mechanism is highly essential to find the effect of different laser parameters on the quality of the laser ablation. A mathematical model was developed in the current investigation to calculate the material removal rate and ablation depth. Laser cuts were created on the workpiece with different laser scan speeds from 1 to 10 mm s−1 by an ultrashort pulse laser with a wavelength of about 1000 nm. The calculated depths of laser cuts were validated via practical experiments. The variation of the laser power intensity on the workpiece’s surface during laser radiation was also calculated. The mathematical model has determined the laser-material interaction mechanism for different laser intensities. The practical sublimation temperature and ablated material temperature during laser processing are other data that the model calculates. The results show that in laser power intensities (IL) higher than 1.5 × 109 W cm−2, the laser-material interaction is multiphoton ionisation with no effects of thermal reaction, while in lower values of IL, there are effects of thermal damages and HAZ adjacent to the laser cut. The angle of incidence is an essential factor in altering incident IL on the surface of the workpiece during laser processing, which changes with increasing depth of the laser cut.

Negative ions generated by laser‐material interaction (invited)

1992 ◽  
Vol 63 (4) ◽  
pp. 2672-2675 ◽  
Author(s):  
G. Korschinek ◽  
T. Henkelmann
Keyword(s):  
Negative Ions ◽  
Laser Material ◽  
Material Interaction

scholarly journals A Lab-Scale Experiment Approach to the Measurement of Wall Pressure from Near-Field under Water Explosions by a Hopkinson Bar

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xiongwei Cui ◽  
Xiongliang Yao ◽  
Yingyu Chen
Keyword(s):  
Shock Wave ◽  
Near Field ◽  
Underwater Explosion ◽  
Experimental System ◽  
Hopkinson Bar ◽  
Wall Pressure ◽  
Pressure Loading ◽  
Target Plate ◽  
Wave Pressure ◽  
Shock Wave Pressure

Direct measurement of the wall pressure loading subjected to the near-field underwater explosion is of great difficulty. In this article, an improved methodology and a lab-scale experimental system are proposed and manufactured to assess the wall pressure loading. In the methodology, a Hopkinson bar (HPB), used as the sensing element, is inserted through the hole drilled on the target plate and the bar’s end face lies flush with the loaded face of the target plate to detect and record the pressure loading. Furthermore, two improvements have been made on this methodology to measure the wall pressure loading from a near-field underwater explosion. The first one is some waterproof units added to make it suitable for the underwater environment. The second one is a hard rubber cylinder placed at the distal end, and a pair of ropes taped on the HPB is used to pull the HPB against the cylinder hard to ensure the HPB’s end face flushes with loaded face of the target plate during the bubble collapse. To validate the pressure measurement technique based on the HPB, an underwater explosion between two parallelly mounted circular target plates is used as the validating system. Based on the assumption that the shock wave pressure profiles at the two points on the two plates which are symmetrical to each other about the middle plane of symmetry are the same, it was found that the pressure obtained by the HPB was in excellent agreement with pressure transducer measurements, thus validating the proposed technique. To verify the capability of this improved methodology and experimental system, a series of minicharge underwater explosion experiments are conducted. From the recorded pressure-time profiles coupled with the underwater explosion evolution images captured by the HSV camera, the shock wave pressure loading and bubble-jet pressure loadings are captured in detail at 5  mm, 10  mm, …, 30  mm stand-off distances. Part of the pressure loading of the experiment at 35  mm stand-off distance is recorded, which is still of great help and significance for engineers. Especially, the peak pressure of the shock wave is captured.

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