scholarly journals Dynamics of UV short pulse laser-induced plasmas from a ceramic material “titanium carbide”: a hydrodynamical out of equilibrium investigation

2019 ◽  
Vol 37 (01) ◽  
pp. 86-100
Author(s):  
A. Ait Oumeziane ◽  
J-D. Parisse
Keyword(s):  
Laser Beam ◽  
Ceramic Material ◽  
Material Properties ◽  
Atmospheric Pressure ◽  
Short Pulse ◽  
Plume Expansion ◽  
Pure Material ◽  
Short Pulse Laser ◽  
Helium Gas ◽  
Ionization Rates

AbstractThe present work is motivated by the numerous applications of short lasers–ceramics interaction. It aims at applying a newly developed model to investigate the dynamic of laser-induced plasmas from a ceramic material into a helium gas under atmospheric pressure. To have a better understanding of the link between the material properties, the plume characteristics and its interaction with the laser beam, a thorough examination of the entire ablation processes is conducted. Comparison with the behavior of laser-induced plumes under the same conditions from a pure material is shown to have a key role in shedding the light on what monitors the plume expansion in the background environment. Plume temperatures, velocities, ionization rates as well as elemental composition have been presented and compared under carefully chosen relevant conditions. This study is of interest for laser matter applications depending on the induced plasmas dynamics and composition.

scholarly journals A Study on the Plasma Plume Expansion Dynamics of Nanosecond Laser Ablating Al/PTFE

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3321
Author(s):  
Sheng Tan ◽  
Moge Wang ◽  
Jianjun Wu ◽  
Yu Zhang ◽  
Jian Li
Keyword(s):  
Plasma Plume ◽  
Laser Energy ◽  
Short Pulse ◽  
Ambient Pressure ◽  
Rapid Expansion ◽  
Nanosecond Laser ◽  
Expansion Process ◽  
Plume Expansion ◽  
Plume Front ◽  
Short Pulse Laser

To study the plasma plume expansion dynamics of nanosecond laser ablating Al/PTFE, the Al/PTFE propellant was prepared by a molding sintering method and the rapid expansion process of the plasma plume was photographed using fast photography technology. The effects of the proportion of Al, laser energy and ambient pressure on plasma plume expansion dynamics are analyzed. The results show that the plume expansion process of laser ablating Al/PTFE plasma can be divided into three stages and this phenomenon has not been reported in the literature. The Al powder doped in PTFE will block part of the laser transmission into the propellant, thus reducing the laser absorption depth of the propellant. In the case of short pulse laser ablation, the reaction rate between Al and PTFE is optimal when the reductant is slightly higher than the oxidant. As the laser energy increases, the light intensity of the plasma becomes stronger, the plasma size becomes larger and the existence time of plasma becomes longer. In the first stage plume, the plume expands freely at the ambient pressure of 0.005 Pa and the plume expansion distance is linearly related to time, while the shock wave formed at the interface between the plume front and the ambient gas at the ambient pressure of 5 Pa and the expansion can be described by S-T theory.

Mathematical Models for Analyzing Tissue Ablation Using Short Pulse Lasers

2009 ◽  
Author(s):  
Ogugua Onyejekwe ◽  
Amir Yousef Sajjadi ◽  
Ugur Abdulla ◽  
Kunal Mitra ◽  
Michael Grace
Keyword(s):  
Temperature Distribution ◽  
Laser Beam ◽  
Heat Equation ◽  
Surface Temperature ◽  
Mathematical Models ◽  
Short Pulse ◽  
Ablation Depth ◽  
Tissue Ablation ◽  
Surface Temperature Distribution ◽  
Short Pulse Laser

Mathematical modeling of biological tissue ablation performed using a short pulse laser and the corresponding experimental analysis is of fundamental importance to the understanding and predicting the temperature distribution and heat affected zone for advancing surgical application of lasers. The objective of this paper is to use mathematical models to predict the thermal ablated zones during irradiation of freshly excised mouse skin tissue samples by a novel approach using a focused laser beam from a short pulse laser source. Suggested mathematical model is Stefan kind free boundary problem for the heat equation in unknown region. Temperature of the skin satisfies the classical heat equation subjected to Neumann boundary condition on the known boundary, while along the time-dependent unknown boundary, which characterizes the ablation depth, two conditions are met: (1) temperature is equal to the ablation temperature and (2) classical Stefan condition is satisfied. The latter expresses the conservation of energy at the ablation moment. A method of integral equations is used to reduce the Stefan problem to a system of two Volterra kind integral equations for temperature and ablation depth. MATLAB is used subsequently for the numerical solution. Experiments are performed using two lasers—a diode laser having a wavelength of 1552 nm and pulsewidth of 1.3 ps. The surface temperature distribution is measured using an imaging camera. After irradiation, histological studies of laser irradiated tissues are performed using frozen sectioning technique to determine the extent of thermal damage caused by the laser beam. The ablation depth and width is calculated based on the interpolated polygon technique using image processing software. The surface temperature distribution and the ablation depth obtained from the mathematical models are compared with the experimental measurements and are in very good agreement. A parametric study of various laser parameters such as time-average power, pulse repetition rate, pulse energy, and irradiation time is performed to determine the necessary ablation threshold parameters.

Filamentation instability of a laser beam in an inhomogeneous plasma in an arbitrarily oriented external magnetic field

2013 ◽  
Vol 79 (5) ◽  
pp. 921-926
Author(s):  
A. HASANBEIGI ◽  
A. MOUSAVI ◽  
H. MEHDIAN
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
External Magnetic Field ◽  
Laser Beam ◽  
Short Pulse ◽  
Inhomogeneous Plasma ◽  
Plasma Inhomogeneity ◽  
Short Pulse Laser ◽  
Filamentation Instability ◽  
Applied External Magnetic Field

AbstractThe interaction of a short pulse laser beam with an inhomogeneous plasma has been studied in the presence of an obliquely applied external magnetic field. The dispersion relation and the analytical growth rate have been obtained solving the nonlinear wave equation. It is found that the growth rate and the cut-off wavenumber are strongly influenced by the direction and magnitude of the applied magnetic field. Moreover, the growth rate has been modified by plasma inhomogeneity.

Experimental Measurements and Numerical Modeling Validation of Temperature Distribution in Tissue Medium During Short Pulse Laser Irradiation

2007 ◽  
Author(s):  
Ashim Dutta ◽  
Kyunghan Kim ◽  
Kunal Mitra ◽  
Zhixiong Guo
Keyword(s):  
Numerical Modeling ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Laser Beam ◽  
Pulse Laser ◽  
Short Pulse ◽  
Hyperbolic Heat Conduction ◽  
Experimental Measurements ◽  
Conduction Model ◽  
Short Pulse Laser

The objective of this paper is to analyze the temperature distributions and heat affected zone in skin tissue medium when irradiated with either a collimated or a focused laser beam from a short pulse laser source. Single-layer and three-layer tissue phantoms containing embedded inhomogeneities are used as a model of human skin tissue having subsurface tumor. Q-switched Nd:YAG laser is used in this study. Experimental measurements of axial and radial temperature distribution in the tissue phantom are compared with the numerical modeling results. For numerical modeling, the transient radiative transport equation is first solved using discrete ordinates method for obtaining the intensity distribution and radiative heat flux inside the tissue medium. Then the temperature distribution is obtained by coupling the bio-heat transfer equation with either hyperbolic non-Fourier or parabolic Fourier heat conduction model. The hyperbolic heat conduction equation is solved using MacCormack’s scheme with error terms correction. It is observed that experimentally measured temperature distribution is in good agreement with that predicted by hyperbolic heat conduction model. The experimental measurements also demonstrate that converging laser beam focused directly at the subsurface location can produce desired high temperature at that location as compared to that produced by collimated laser beam for the same laser parameters.

scholarly journals STUDY OF FOCUSING INTO CLOSELY SPACED SPOTS VIA ILLUMINATING A DIFFRACTIVE OPTICAL ELEMENT BY A SHORT-PULSE LASER BEAM

2015 ◽  
Vol 39 (2) ◽  
pp. 187-196 ◽  
Author(s):  
S. N. Khonina ◽  
S. A. Degtyarev ◽  
A. P. Porfirev ◽  
O. Yu. Moiseev ◽  
S. D. Poletaev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Pulse Laser ◽  
Short Pulse ◽  
Optical Element ◽  
Diffractive Optical Element ◽  
Pulse Laser Beam ◽  
Short Pulse Laser

Thermal Ablation of Mouse Skin Tissue Using Ultra-Short Pulse 1552 nm Laser

2008 ◽  
Author(s):  
Amir Yousef Sajjadi ◽  
Ogugua Onyejekwe ◽  
Shreya Raje ◽  
Kunal Mitra ◽  
Michael Grace
Keyword(s):  
Laser Beam ◽  
Short Pulse ◽  
Mouse Skin ◽  
Ablation Depth ◽  
Tissue Ablation ◽  
Tissue Samples ◽  
Histological Studies ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser

Analysis of biological tissue ablation by an ultra-short pulse laser and the corresponding mathematical modeling of ablation are of fundamental importance to the understanding of laser-tissue interaction for advancing surgical application of lasers. The objective of this paper is to analyze the thermal ablated damage zones during irradiation of freshly excised mouse skin tissue samples by a novel approach of using a focused laser beam from an ultra-short pulse laser source. Experiments are performed using Raydiance Desktop Laser having a wavelength of 1552 nm and a pulse width of 1.3 ps. Mouse tissue samples are translated in a direction perpendicular to the laser beam using three-axis automated motion-controlled stages. Scanning of the tissue sample ensures a fresh region of the tissue is irradiated each time. The surface temperature distribution is measured using a thermal imaging camera. It is observed that use of focused beam results in minimal radial heat spread to the surrounding tissue regions. The ablation phenomenon is analytically modeled by the use of two-phase transient heat conduction model. After completion of tissue irradiation experiments, histological studies are performed using frozen sectioning technique to observe morphological changes in tissue samples in response to laser irradiation. The ablation depth measurements obtained using histological studies are compared with the modeling results. A parametric study of various laser parameters such as time-average power, pulse repetition rate, and pulse energy, and as well as irradiation time and scanning velocity is performed to determine the necessary ablation threshold. Analytical modeling results are in very good agreement with experimentally measured ablation depth. The goal of this research is to develop a tool for selection of appropriate laser parameters for precise clean tissue ablation.

Short pulse laser beam beyond paraxial approximation

2017 ◽  
Vol 34 (8) ◽  
pp. 1351 ◽  
Author(s):  
Pierre Favier ◽  
Kevin Dupraz ◽  
Kevin Cassou ◽  
Xing Liu ◽  
Aurélien Martens ◽  
...  
Keyword(s):  
Laser Beam ◽  
Pulse Laser ◽  
Short Pulse ◽  
Paraxial Approximation ◽  
Pulse Laser Beam ◽  
Short Pulse Laser

Ablation of Subsurface Tumors Using 1552 nm Ultra-Short Pulse Laser

2008 ◽  
Author(s):  
Shreya Raje ◽  
Amir Sajjadi ◽  
Kunal Mitra ◽  
Michael S. Grace
Keyword(s):  
Laser Beam ◽  
Pulse Laser ◽  
Continuous Wave ◽  
Short Pulse ◽  
Laser Source ◽  
Short Pulse Laser ◽  
Fiber Optic Probes ◽  
Laser Immunotherapy ◽  
Ultra Short Pulse ◽  
Long Pulse

Over last two decades lasers have been used for the treatment of subsurface tumors. Various techniques such as Laser-induced Hyperthermia, Laser Interstitial Thermal Therapy (LITT), and Laser Immunotherapy have been developed for the successful ablation of subsurface tumors by different researchers. All these techniques use photo-thermal mechanism for tumor ablation by delivering thermal energy at the tumor site. In all these existing techniques, either continuous wave (CW) or long pulse laser source has been used, which often produces larger heat affected zone as compared to that produced by short pulse laser. Moreover, the delivery of laser beam at the target site is achieved through fiber optic probes which often require perforation of the skin. These drawbacks can be eliminated if a converging laser beam from a short pulse laser source is directly focused at the subsurface location to ablate the tumor.

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