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Wyszukujesz frazę "Ristić, V." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
Calculating Ionization Transition Rate for Circularly Polarized Fields, Including Non-Zero Initial Momentum
Autorzy:
Ristić, V.
Miladinović, T.
Radulović, M.
Powiązania:
https://bibliotekanauki.pl/articles/1791204.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.-t
32.80.Fb
32.80.Rm
Opis:
Potassium atoms in circularly polarized laser field whose intensity (I) varies from 2× $10^{12}$ W/$cm^2$ to 2.5× $10^{14}$ W/$cm^2$ were studied. In the case when there is zero initial momentum, transition rate (that depends only on I) exhibits standard behaviour: as I increases, so thus the rate, until it reaches its maximum value at 1.1× $10^{14}$ W/$cm^2$; after that, rate diminishes as I increases. In the case of non-zero initial momentum, transition rate (that now depends on I but additionally on initial momentum, too) exhibits following behaviour: dependence of the rate on I follows standard pattern, it rises with increase of I until it reaches its maximum, and then diminishes. But with increase of momentum, ionization rate gradually diminishes.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 504-506
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Ponderomotive Potential and NonZero Initial Momentum of Ejected Electron on Transition Rate in Multiphoton Ionization
Autorzy:
Miladinović, T.
Petrović, V.
Ristić, V.
Powiązania:
https://bibliotekanauki.pl/articles/1399265.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.-t
32.80.Fb
32.80.Wr
Opis:
The multiphoton ionization of neutral atoms irradiated by photons is an interesting topic for experimental and also theoretical examination. We study the influence of ponderomotive potential and non-zero initial momentum of ejected electrons on transition rate, and also on the generalized cross-section in the case of a multiphoton ionization process. Also, we study how the transition rate depends on the number of absorbed photons.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 658-660
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Circularly Polarized Laser Fields, with Different Z, Including Non-Zero Initial Momentum
Autorzy:
Ristić, V.
Miladinović, T.
Stevanović, J.
Powiązania:
https://bibliotekanauki.pl/articles/1504530.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.-t
32.80.Fb
32.80.Rm
Opis:
In this paper, by estimating the influence of different atom charge Z to the transition rate in tunnel ionization of atoms in strong laser fields we are devoloping further the observations from our earlier work. That is in the process of tunnel ionization including non-zero momentum into calculation of the transition rate gives result in lower transition rates for ejecting electrons from atoms by low-frequency laser fields, indicating that much of the photons are engaged in transferring energy to the free electron and thus unable to contribute to the effect of ionization. This is a conclusion that needs further experimental testing, which would clarify the mechanisms of tunnel ionization.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 761-763
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transition Rate Dependence on the Non-Zero Initial Momentum in the ADK-Theory
Autorzy:
Ristić, V. M.
Miladinović, T. T.
Radulović, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/2047850.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.-t
32.80.Fb
32.80.Rm
Opis:
Tunneling regime, introduced by Keldysh, in the interaction of strong lasers with atoms has been now accepted as the reliable method for describing processes when low frequency lasers are involved. Yet it was always assumed that the ionized electrons are leaving the atom with zero initial momentum. Because we are interested in how non-zero momentum influences the transition probability of tunnel ionization, we obtained the exact expression for the momentum. Here the estimation of the transition probability with nonzero momentum included was conducted. Potassium atoms in the laser field whose intensity varied from 10$\text{}^{13}$ W/cm$\text{}^{2}$ to 10$\text{}^{14}$ W/cm$\text{}^{2}$ were studied. It seems that all energy of laser field is used for tunneling ionization process at the beginning of laser pulse - ionization probability is large. After that, with further action of laser pulse, ionization probability decreases, probably because part of laser pulse energy is used for increasing momentum of ejected electrons, leaving smaller amounts of light quanta available for ionization of remaining electrons. If laser pulse lasts long enough, then the amounts of light quanta available for ionization become larger, resulting in increase in ionization probability, now with greater starting energy of ejected electrons.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 909-914
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Electrical Properties of Sintered Barium-Zinc-Titanate Ceramics
Autorzy:
Obradović, N.
Filipović, S.
Pavlović, V.
Paunović, V.
Mitrić, M.
Ristić, M.
Powiązania:
https://bibliotekanauki.pl/articles/1503704.pdf
Data publikacji:
2011-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Wk
81.20.Ev
61.05.C-
84.37.+q
Opis:
The aim of this work was an investigation of structural and electrical properties of sintered barium-zinc-titanate ceramics. Mixtures of $BaCO_{3},$ $ZnO$ and $TiO_{2}$ were mechanically activated in a planetary ball mill up to 80 minutes and sintered isothermally in air for 120 minutes at 1300°C. The phase composition in the $BaCO_{3}-ZnO-TiO_{2}$ system after milling and sintering was analyzed using the XRD method. The existence of pure barium-zinc-titanate has been registered. Microstructure analyses were performed using SEM. The results of electric resistivity, capacitance and loss tangent of the sintered samples were correlated with the XRD and SEM results.
Źródło:
Acta Physica Polonica A; 2011, 120, 2; 322-325
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic field simulation in the central region of the VINCY Cyclotron
Autorzy:
Vorojtsov, S.
Vorozhtsov, A.
Nešković, N.
Ristić -Durović, J.
Ćirković, S.
Vujović, V.
Powiązania:
https://bibliotekanauki.pl/articles/148735.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
cyclotron
central region
magnetic field
plug
beam dynamics
Opis:
The VINCY Cyclotron is under construction at the Vinca Institute of Nuclear Sciences, Laboratory of Physics, Belgrade, Serbia and Montenegro. One of the most difficult problems to solve is the magnetic field shaping in the central region of the machine in a wide range of field levels. The latest measurements showed a very large magnetic field depression in the central region. The following shimming elements are used for the field shaping in the central region: a central plug and a spacer ring between the sectors and the median pole plate. These elements should both release enough vertical space for the inflector and the RF electrodes and produce a field bump in the very center of the machine. Concerning this region, one has to mention the following facts: sectors are absent or very reduced, and the small gap between the sectors restricts remarkably the possibilities of producing a field bump. Therefore, the design of these elements is the most critical one. Optimization of the central plug gap affects both the vertical sparking probability and the beam dynamics at higher harmonic modes. The redesign of the magnetic structure of the central region relied solely on the detailed 3-dimensional calculations to speed up the experimental shimming procedure. The desired calculated magnetic field shapes, which include the influence of the plug, have been produced and confirmed
Źródło:
Nukleonika; 2003, 48,suppl.2; 39-44
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ruby Laser Interaction with Austenite Structural Materials
Autorzy:
Milosavljević, A.
Petronić, S.
Srećković, M.
Ristić, S.
Nešić, I.
Pljakić, R.
Negovanović, V.
Powiązania:
https://bibliotekanauki.pl/articles/1808064.pdf
Data publikacji:
2009-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
01.55.+b
42.62.-b
81.05.-t
Opis:
The investigations were carried out on chrome nickel steel and nickel based superalloy samples thermo-mechanically treated to obtain optimal mechanical properties and surface stability. Chrome nickel steel and a few nickel based superalloys samples were exposed to the laser beam before creep deformation process. The second group of nickel based superalloy samples were exposed after the creep deformation. The damages occurred by exposing of chrome nickel steel and nickel base superalloy samples to the ruby laser were analyzed by scanning electron microscope and energy-dispersive X-ray spectrometry. In this paper, the influence of laser dynamical regime (MW/$mm^{2}$) to the microstructural changes of heat treated chrome nickel steel and nickel based superalloy are analyzed and discussed.
Źródło:
Acta Physica Polonica A; 2009, 115, 4; 823-825
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Status report of the VINCY Cyclotron
Autorzy:
Nešković, N.
Ristić-Ðurović, J.
Vorojtsov, S. B.
Belicev, P.
Ivanenko, I. A.
Ćirković, S.
Vorozhtsov, A. S.
Bojović, B.
Dobrosavljević, A.
Vujović, V.
Comor, J. j.
Pajović, S. B.
Powiązania:
https://bibliotekanauki.pl/articles/146191.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
accelerators
cyclotrons
ion sources
radioisotopes
radiation research
Opis:
The VINCY Cyclotron is the main part of the TESLA Accelerator Installation. The diameter of the pole of this machine is 2000 mm. Its bending constant is 145 MeV while its focusing constant is 75 MeV. The radiofrequency system of the machine consists of two l/4-resonators with the eigenfrequency in the range from 17 to 31 MHz. Ions coming from a heavy ion source or a light ion source will be injected into the machine axially. They will be introduced into its median plane by a spiral inflector. Heavy ions accelerated in the machine will be extracted from it by a foil stripping system or by an electrostatic deflection system. Light ions will be extracted from it by the foil stripping system. The first programs of use of the VINCY Cyclotron are related to routine and experimental production of radioisotopes and radiopharmaceuticals, and to biomedical research with ion beams. The first beam extracted from the machine will be the proton beam of the energy of 22 MeV obtained from the H2+ beam extracted from the light ion source. This beam will be used first for production of radioisotope 18F and radio-pharmaceutical 18FDG, to be employed for positron emission tomography
Źródło:
Nukleonika; 2003, 48,suppl.2; 135-139
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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