The Experts below are selected from a list of 8217 Experts worldwide ranked by ideXlab platform

Leonid V Zhigilei - One of the best experts on this subject based on the ideXlab platform.

  • atomistic simulation study of short pulse laser interactions with a Metal Target under conditions of spatial confinement by a transparent overlayer
    Journal of Applied Physics, 2014
    Co-Authors: Eaman T Karim, Maxim V Shugaev, Chengping Wu, Robert F Hainsey, Leonid V Zhigilei
    Abstract:

    The distinct characteristics of short pulse laser interactions with a Metal Target under conditions of spatial confinement by a solid transparent overlayer are investigated in a series of atomistic simulations. The simulations are performed with a computational model combining classical molecular dynamics (MD) technique with a continuum description of the laser excitation, electron-phonon equilibration, and electronic heat transfer based on two-temperature model (TTM). Two methods for incorporation of the description of a transparent overlayer into the TTM-MD model are designed and parameterized for Ag-silica system. The material response to the laser energy deposition is studied for a range of laser fluences that, in the absence of the transparent overlayer, covers the regimes of melting and resolidification, photomechanical spallation, and phase explosion of the overheated surface region. In contrast to the irradiation in vacuum, the spatial confinement by the overlayer facilitates generation of sustain...

  • atomistic modeling of short pulse laser ablation of Metals connections between melting spallation and phase explosion
    Journal of Physical Chemistry C, 2009
    Co-Authors: Leonid V Zhigilei, Zhibin Lin, D S Ivanov
    Abstract:

    The mechanisms of short pulse laser interactions with a Metal Target are investigated in simulations performed with a model combining the molecular dynamics method with a continuum description of laser excitation, electron−phonon equilibration, and electron heat conduction. Three regimes of material response to laser irradiation are identified in simulations performed with a 1 ps laser pulse, which corresponds to the condition of stress confinement: melting and resolidification of a surface region of the Target, photomechanical spallation of a single or multiple layers or droplets, and an explosive disintegration of an overheated surface layer (phase explosion). The processes of laser melting, spallation, and phase explosion are taking place on the same time scale and are closely intertwined with each other. The transition to the spallation regime results in a reduction of the melting zone and a sharp drop in the duration of the melting and resolidification cycle. The transition from spallation to phase e...

  • computational study of the generation of crystal defects in a bcc Metal Target irradiated by short laser pulses
    Physical Review B, 2008
    Co-Authors: R A Johnson, Leonid V Zhigilei
    Abstract:

    The generation of crystal defects in a Cr Target irradiated by a short, 200 fs, laser pulse is investigated in computer simulations performed with a computational model that combines the classical molecular dynamics method with a continuum description of the laser excitation of conduction band electrons, electron-phonon coupling, and electron heat conduction. Interatomic interactions are described by the embedded atom method EAM potential with a parametrization designed for Cr. The potential is tested by comparing the properties of the EAM Cr material with experimental data and predictions of density functional theory calculations. The simulations are performed at laser fluences close to the threshold for surface melting. Fast temperature variation and strong thermoelastic stresses produced by the laser pulse are causing surface melting and epitaxial resolidification, transient appearance of a high density of stacking faults along the 110 planes, and generation of a large number of point defects vacancies and self-interstitials. The stacking faults appear as a result of internal shifts in the crystal undergoing a rapid uniaxial expansion in the direction normal to the irradiated surface. The stacking faults are unstable and disappear shortly after the laser-induced tensile stress wave leaves the surface region of the Target. Thermally activated generation of vacancy-interstitial pairs during the initial temperature spike and quick escape of highly mobile self-interstitials to the melting front or the free surface of the Target, along with the formation of vacancies at the solid-liquid interface during the fast resolidification process, result in a high density of vacancies, on the order of 10 3 per lattice site, created in the surface region of the Target. The strong supersaturation of vacancies can be related to the incubation effect in multipulse laser ablation/damage and should play an important role in mixing/alloying of multicomponent or composite Targets.

Ranran Fang - One of the best experts on this subject based on the ideXlab platform.

  • Improved two-temperature model and its application in femtosecond laser ablation of Metal Target
    Laser and Particle Beams, 2020
    Co-Authors: Ranran Fang, Duanming Zhang, Zhihua Li, Fengxia Yang
    Abstract:

    AbstractAn improved two-temperature model to describe femtosecond laser ablation of Metal Target was presented. The temperature-dependent heat capacity and thermal conductivity of the electron, as well as electron temperature-dependent absorption coefficient and absorptivity are all considered in this two-temperature model. The tailored two-temperature model is solved using a finite difference method for copper Target. The time-dependence of lattice and electron temperature of the surface for different laser fluence are performed, respectively. The temperature distribution of the electron and lattice along with space and time for a certain laser fluence is also presented. Moreover, the variation of ablation rate per pulse with laser fluence is obtained. The satisfactory agreement between our numerical results and experimental data indicates that the temperature dependence of heat capacity, thermal conductivity, absorption coefficient and absorptivity in femtosecond laser ablation of Metal Target must not be neglected. The present model will be helpful for the further experimental investigation of application of the femtosecond laser.

  • improved thermal model and its application in uv high power pulsed laser ablation of Metal Target
    Solid State Communications, 2008
    Co-Authors: Ranran Fang, Duanming Zhang, Fengxia Yang, Zhihua Li, Li Li
    Abstract:

    An improved thermal model describing UV high-power nanosecond laser ablation of Metal Target is presented. The vaporization effect, the plasma shielding effect, as well as the absorption coefficient and absorptivity dependence of temperature are considered in this model. Take iron Target as an example, the numerical solutions are obtained from the heat flow equations (before and after melting) using a finite difference method. The space and time dependence of temperature of the Target, the time dependence of temperature at two different positions for a certain laser fluence, and the ablation rate as a function of laser fluence are also presented. The numerical results that agreed well with the experimental data are much better than the one without, which indicates that the above two effects and the temperature dependence of absorption coefficient and absorptivity in UV high-power laser ablation of Metal Target should not be neglected. We hope the present model will be useful for further experimental investigation of Metal thin films prepared by pulsed laser deposition.

  • Improved thermal model and its application in UV high-power pulsed laser ablation of Metal Target
    Solid State Communications, 2008
    Co-Authors: Ranran Fang, Duanming Zhang, Fengxia Yang, Xinyu Tan, Zhihua Li, Lin Li, Min Sun
    Abstract:

    An improved thermal model describing UV high-power nanosecond laser ablation of Metal Target is presented. The vaporization effect, the plasma shielding effect, as well as the absorption coefficient and absorptivity dependence of temperature are considered in this model. Take iron Target as an example, the numerical solutions are obtained from the heat flow equations (before and after melting) using a finite difference method. The space and time dependence of temperature of the Target, the time dependence of temperature at two different positions for a certain laser fluence, and the ablation rate as a function of laser fluence are also presented. The numerical results that agreed well with the experimental data are much better than the one without, which indicates that the above two effects and the temperature dependence of absorption coefficient and absorptivity in UV high-power laser ablation of Metal Target should not be neglected. We hope the present model will be useful for further experimental investigation of Metal thin films prepared by pulsed laser deposition. © 2008 Elsevier Ltd. All rights reserved.

Li Li - One of the best experts on this subject based on the ideXlab platform.

  • improved thermal model and its application in uv high power pulsed laser ablation of Metal Target
    Solid State Communications, 2008
    Co-Authors: Ranran Fang, Duanming Zhang, Fengxia Yang, Zhihua Li, Li Li
    Abstract:

    An improved thermal model describing UV high-power nanosecond laser ablation of Metal Target is presented. The vaporization effect, the plasma shielding effect, as well as the absorption coefficient and absorptivity dependence of temperature are considered in this model. Take iron Target as an example, the numerical solutions are obtained from the heat flow equations (before and after melting) using a finite difference method. The space and time dependence of temperature of the Target, the time dependence of temperature at two different positions for a certain laser fluence, and the ablation rate as a function of laser fluence are also presented. The numerical results that agreed well with the experimental data are much better than the one without, which indicates that the above two effects and the temperature dependence of absorption coefficient and absorptivity in UV high-power laser ablation of Metal Target should not be neglected. We hope the present model will be useful for further experimental investigation of Metal thin films prepared by pulsed laser deposition.

Min Sun - One of the best experts on this subject based on the ideXlab platform.

  • Improved thermal model and its application in UV high-power pulsed laser ablation of Metal Target
    Solid State Communications, 2008
    Co-Authors: Ranran Fang, Duanming Zhang, Fengxia Yang, Xinyu Tan, Zhihua Li, Lin Li, Min Sun
    Abstract:

    An improved thermal model describing UV high-power nanosecond laser ablation of Metal Target is presented. The vaporization effect, the plasma shielding effect, as well as the absorption coefficient and absorptivity dependence of temperature are considered in this model. Take iron Target as an example, the numerical solutions are obtained from the heat flow equations (before and after melting) using a finite difference method. The space and time dependence of temperature of the Target, the time dependence of temperature at two different positions for a certain laser fluence, and the ablation rate as a function of laser fluence are also presented. The numerical results that agreed well with the experimental data are much better than the one without, which indicates that the above two effects and the temperature dependence of absorption coefficient and absorptivity in UV high-power laser ablation of Metal Target should not be neglected. We hope the present model will be useful for further experimental investigation of Metal thin films prepared by pulsed laser deposition. © 2008 Elsevier Ltd. All rights reserved.

Zhihua Li - One of the best experts on this subject based on the ideXlab platform.

  • Improved two-temperature model and its application in femtosecond laser ablation of Metal Target
    Laser and Particle Beams, 2020
    Co-Authors: Ranran Fang, Duanming Zhang, Zhihua Li, Fengxia Yang
    Abstract:

    AbstractAn improved two-temperature model to describe femtosecond laser ablation of Metal Target was presented. The temperature-dependent heat capacity and thermal conductivity of the electron, as well as electron temperature-dependent absorption coefficient and absorptivity are all considered in this two-temperature model. The tailored two-temperature model is solved using a finite difference method for copper Target. The time-dependence of lattice and electron temperature of the surface for different laser fluence are performed, respectively. The temperature distribution of the electron and lattice along with space and time for a certain laser fluence is also presented. Moreover, the variation of ablation rate per pulse with laser fluence is obtained. The satisfactory agreement between our numerical results and experimental data indicates that the temperature dependence of heat capacity, thermal conductivity, absorption coefficient and absorptivity in femtosecond laser ablation of Metal Target must not be neglected. The present model will be helpful for the further experimental investigation of application of the femtosecond laser.

  • improved thermal model and its application in uv high power pulsed laser ablation of Metal Target
    Solid State Communications, 2008
    Co-Authors: Ranran Fang, Duanming Zhang, Fengxia Yang, Zhihua Li, Li Li
    Abstract:

    An improved thermal model describing UV high-power nanosecond laser ablation of Metal Target is presented. The vaporization effect, the plasma shielding effect, as well as the absorption coefficient and absorptivity dependence of temperature are considered in this model. Take iron Target as an example, the numerical solutions are obtained from the heat flow equations (before and after melting) using a finite difference method. The space and time dependence of temperature of the Target, the time dependence of temperature at two different positions for a certain laser fluence, and the ablation rate as a function of laser fluence are also presented. The numerical results that agreed well with the experimental data are much better than the one without, which indicates that the above two effects and the temperature dependence of absorption coefficient and absorptivity in UV high-power laser ablation of Metal Target should not be neglected. We hope the present model will be useful for further experimental investigation of Metal thin films prepared by pulsed laser deposition.

  • Improved thermal model and its application in UV high-power pulsed laser ablation of Metal Target
    Solid State Communications, 2008
    Co-Authors: Ranran Fang, Duanming Zhang, Fengxia Yang, Xinyu Tan, Zhihua Li, Lin Li, Min Sun
    Abstract:

    An improved thermal model describing UV high-power nanosecond laser ablation of Metal Target is presented. The vaporization effect, the plasma shielding effect, as well as the absorption coefficient and absorptivity dependence of temperature are considered in this model. Take iron Target as an example, the numerical solutions are obtained from the heat flow equations (before and after melting) using a finite difference method. The space and time dependence of temperature of the Target, the time dependence of temperature at two different positions for a certain laser fluence, and the ablation rate as a function of laser fluence are also presented. The numerical results that agreed well with the experimental data are much better than the one without, which indicates that the above two effects and the temperature dependence of absorption coefficient and absorptivity in UV high-power laser ablation of Metal Target should not be neglected. We hope the present model will be useful for further experimental investigation of Metal thin films prepared by pulsed laser deposition. © 2008 Elsevier Ltd. All rights reserved.