TY  - JOUR
AU  - Gaković, Biljana M.
AU  - Stašić, Jelena
AU  - Petrović, Suzana
AU  - Radak, Bojan
AU  - Krmpot, Aleksandar J.
AU  - Jelenković, Branislav
AU  - Trtica, Milan
PY  - 2009
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6844
AB  - Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm(2) had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter ( LT = 10 mu m) and relatively large depth ( LT = 50 mu m). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.
T2  - Acta Physica Polonica A
T1  - Surface Modification of Metallic Targets with Ultrashort Laser Pulses
VL  - 116
IS  - 4
SP  - 611
EP  - 613
DO  - 10.12693/APhysPolA.116.611
ER  - 

@article{
author = "Gaković, Biljana M. and Stašić, Jelena and Petrović, Suzana and Radak, Bojan and Krmpot, Aleksandar J. and Jelenković, Branislav and Trtica, Milan",
year = "2009",
abstract = "Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm(2) had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter ( LT = 10 mu m) and relatively large depth ( LT = 50 mu m). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.",
journal = "Acta Physica Polonica A",
title = "Surface Modification of Metallic Targets with Ultrashort Laser Pulses",
volume = "116",
number = "4",
pages = "611-613",
doi = "10.12693/APhysPolA.116.611"
}

Gaković, B. M., Stašić, J., Petrović, S., Radak, B., Krmpot, A. J., Jelenković, B.,& Trtica, M.. (2009). Surface Modification of Metallic Targets with Ultrashort Laser Pulses. in Acta Physica Polonica A, 116(4), 611-613.
https://doi.org/10.12693/APhysPolA.116.611

Gaković BM, Stašić J, Petrović S, Radak B, Krmpot AJ, Jelenković B, Trtica M. Surface Modification of Metallic Targets with Ultrashort Laser Pulses. in Acta Physica Polonica A. 2009;116(4):611-613.
doi:10.12693/APhysPolA.116.611 .

Gaković, Biljana M., Stašić, Jelena, Petrović, Suzana, Radak, Bojan, Krmpot, Aleksandar J., Jelenković, Branislav, Trtica, Milan, "Surface Modification of Metallic Targets with Ultrashort Laser Pulses" in Acta Physica Polonica A, 116, no. 4 (2009):611-613,
https://doi.org/10.12693/APhysPolA.116.611 . .

TY  - JOUR
AU  - Davidović, Dragomir A.
AU  - Vukanić, Jovan V.
AU  - Arsenović, Dušan
PY  - 2008
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3370
AB  - The Chandrasekhars H functions play a central role in theoretical descriptions of radiative transfer in planetary and stellar atmospheres. In the present work our aim is to obtain in a simple way new analytic approximations of the Chandrasekhars function for isotropic scattering, which would be sufficiently simple but more accurate than the existing approximations. We apply the mean value theorem for definite integrals in the nonlinear integral equation for the Chandrasekhars H function. In this way the integral equation is formally solved but the solution depends on a new unknown parameter. We determine this parameter approximately, from the condition that the obtained H function matches the zero-order moment of the H function, which is known exactly, as accurately as possible in the whole range of the single particle albedo. The result gives our first analytic approximation for the H function. Using it as a starting approximation in the corresponding integral equation, after only one iteration which may be performed analytically, we obtain our second analytic approximation. The maximum relative error of our first analytic. approximation, which is very simple in structure, is below 2.5%. The accuracy of our second approximation is within 0.07%, so that it highly surpasses the accuracy of the other analytic approximations available in the literature. (c) 2007 Elsevier Inc. All rights reserved.
T2  - Icarus
T1  - Two new analytic approximations of the Chandrasekhars H function for isotropic scattering
VL  - 194
IS  - 1
SP  - 389
EP  - 397
DO  - 10.1016/j.icarus.2007.09.024
ER  - 

@article{
author = "Davidović, Dragomir A. and Vukanić, Jovan V. and Arsenović, Dušan",
year = "2008",
abstract = "The Chandrasekhars H functions play a central role in theoretical descriptions of radiative transfer in planetary and stellar atmospheres. In the present work our aim is to obtain in a simple way new analytic approximations of the Chandrasekhars function for isotropic scattering, which would be sufficiently simple but more accurate than the existing approximations. We apply the mean value theorem for definite integrals in the nonlinear integral equation for the Chandrasekhars H function. In this way the integral equation is formally solved but the solution depends on a new unknown parameter. We determine this parameter approximately, from the condition that the obtained H function matches the zero-order moment of the H function, which is known exactly, as accurately as possible in the whole range of the single particle albedo. The result gives our first analytic approximation for the H function. Using it as a starting approximation in the corresponding integral equation, after only one iteration which may be performed analytically, we obtain our second analytic approximation. The maximum relative error of our first analytic. approximation, which is very simple in structure, is below 2.5%. The accuracy of our second approximation is within 0.07%, so that it highly surpasses the accuracy of the other analytic approximations available in the literature. (c) 2007 Elsevier Inc. All rights reserved.",
journal = "Icarus",
title = "Two new analytic approximations of the Chandrasekhars H function for isotropic scattering",
volume = "194",
number = "1",
pages = "389-397",
doi = "10.1016/j.icarus.2007.09.024"
}

Davidović, D. A., Vukanić, J. V.,& Arsenović, D.. (2008). Two new analytic approximations of the Chandrasekhars H function for isotropic scattering. in Icarus, 194(1), 389-397.
https://doi.org/10.1016/j.icarus.2007.09.024

Davidović DA, Vukanić JV, Arsenović D. Two new analytic approximations of the Chandrasekhars H function for isotropic scattering. in Icarus. 2008;194(1):389-397.
doi:10.1016/j.icarus.2007.09.024 .

Davidović, Dragomir A., Vukanić, Jovan V., Arsenović, Dušan, "Two new analytic approximations of the Chandrasekhars H function for isotropic scattering" in Icarus, 194, no. 1 (2008):389-397,
https://doi.org/10.1016/j.icarus.2007.09.024 . .