Mulțumim pentru înțelegere.
Echipa CETAL.
Author: Andrei Popescu
Abstract:
Author: Bogdana Mitu
Abstract:
Author: Diana CHIOIBASU
Abstract:
Author: Sabin Mihai
Abstract:
Author: Mihail Lungu
Abstract:
Author: Muhammad Arif Mahmood
Abstract: Cold rollings for Al5182 aluminum alloy strips are carried out to evaluate the optical parameters with the applications of two lubricants and various operating conditions. In order to obtain these optical parameters, the fractal parameters, which include periodic lengths (Lx, Ly) and fractal dimensions (Dx, Dy) in the modified three-dimensional formula for the fractal surface morphology have been solved first for the rolled surfaces. This three-dimensional formula can provide an effective way to correlate these fractal parameters with the optical parameters using TracePro software, which can help to define rolling conditions efficiently for the specific demand of optical properties. The deterministic results for fractal surface simulations using MATLAB in series and 20° incident angle simulation in TracePro software explain that an increase in Dx and Dy will yield dense profiles which elevates the maximum illuminance and lower down the minimum illuminance. While an increment in Lx and Ly would increase the characteristic distance between two predominant asperities and increase minimum illuminance and decrease maximum illuminance. Finite element analyses prove that different friction coefficients in the upper and lower rolls potentially induce surface deflection and thus affect the optical properties. A high illuminance uniformity can be achieved by making a compromise among the fractal parameters (Dx , Dy, Lx and Ly) such that a small difference in the maximum and minimum illuminances is available.
Author: Mihai Oane
Abstract: This work is devoted to the electron temperature variation in metals through interaction with femtosecond laser pulses. Our study was inspired by the last mathematical breakthroughs regarding the exact analytical solutions of the heat equation in the case of flash laser-matter interaction. To this purpose, the classical Anisimov’s two temperature model was extended via the 3D telegraph Zhukovsky equation. Based upon this new approach, the computational plots of electron thermal fields during the first laser pulse interaction with a gold surface were inferred. It is shown that relaxation times and coupling factors over electron thermal conductivities (g/K) govern the interaction between the laser pulse and metal sample during the first picoseconds. The lower the factor g/K, the higher the electron temperature becomes. In contrast, the lower the relaxation time, the lower the electron temperature.
Author: Raluca Ivan
Abstract:
Author: Florin Jipa
Abstract:
Author: Cristina Elena Staicu
Abstract:
Author: Andrei STANCALIE
Abstract: The investigation of the radiation effects on novel or well-assessed sensing devices has attracted a lot of interest, however, the facilities required to do this (when available) are barely accessible to the device to be characterized. In order to reduce the limitations of these types of experiments and ensure a highly controlled environment, we implemented a configuration that permits the on-line testing of optical components inside a Co-60 gamma chamber research irradiator.
Author: Georgiana Giubega
Abstract: CETAL-PW high power laser facility reports first accelerated electron beams with maximum energies up to ~500 MeV obtained in Romania, by focusing ultra-short laser pulses of 35 fs with energies up to 5 J before compression on supersonic gas jets of low-density He 99% - N2 1% mixture. The conditions for generation of stable electron beams (root mean square (rms) pointing stability of about 5 mrad), with different types of spectral characteristics and average maximum electron energies between 180 MeV and 380 MeV are presented. Maximum energies for all accelerated electron spectra are well described by theoretical estimations.
Author: Mihai Serbanescu
Abstract: Modulul de control initial al sistemului laser de mare putere din cadrul departamentului CETAL-PW permitea utilizarea pulsurilor laser doar în mod continuu la o rata de repetitie de 10 si 0,1Hz. Acest lucru îngreuna atât implementarea montajelor cât și desfășurarea experimentelor. În cadrul laboratorului a fost dezvoltat un sistem dedicat pentru controlul modului de emisie a pulsurilor de către sistemul laser. Acesta permite comanda emiterii de pulsuri în mod rafală de câte n pulsuri, sau în mod continuu cu rata de repetiţie nominală sau sub-nominală și generare semnalelor electrice si software de sincronizare asociate pulsurilor. Acestea sunt necesare comenzii dispozitivelor electronice de diagnoză si monitorizare precum si pentru sincronizarea aplicațiilor software de achizitie a datelor experimentale.
Author: Daniel Avram
Abstract:
Luminescence thermometry has emerged as an exciting field of research due to its potential in nanotechnology, biomedicine, photonics and microelectronic applications [1]. We present a simple approach to obtain a luminescence nanothermometer operating in the near infrared (NIR) range (1000-1700 nm) under pulsed excitation by use of binary mixtures, Ho - Y2O3 + Er - Y2O3 and Ho - Y2O3 + Nd - Y2O3 [2]. The thermometry performance was assessed in terms of emission shape, intensity, excitation wavelength, dynamics, acquisition mode and weight ratio of the binary mixture [2, 3]. The temperature evolution of the emission shape was monitored in the range of 297 - 472 K. For the binary mixture of Ho - Y2O3 + Er - Y2O3 with 3: 1 weight ratio, the maximum relative sensitivity was of 1% K-1 at 297 K under 536.8 nm excitation [2]. We have further extended the excitation wavelength from visible range to the first biological window using the Er, Ho, Yb codoped Y2O3 nanoparticles. Using pulsed excitation at 905 nm, a maximum relative sensitivity of 1.5 % K-1 at 310 K was obtained, among the best values obtained to date for lanthanide based near infrared luminescent thermometers [4]. References: [1] L. Carlos, F. Palacio, Thermometry at the nanoscale: techniques and selected applications, Thermometry Nanoscale Tech. Sel. Appl. 38, 2016, 124-166 [2] D. Avram, C. Colbea, M. Florea, C. Tiseanu, Highly-sensitive near infrared luminescent nanothermometers based on binary mixture. Journal of Alloys and Compounds, 785, 2019, 250-259. [3] D. Avram, C. Tiseanu, Thermometry properties of Er, Yb–Gd2O2S microparticles: dependence on the excitation mode (cw versus pulsed excitation) and excitation wavelength (980 nm versus 1500 nm). Methods and applications in fluorescence, 6(2), 2018, 025004. [4] I. Porosnicu, C. Colbea, F. Baiasu, M. Lungu, M. C. Istrate, D. Avram, C. Tiseanu, A sensitive near infrared to near-infrared luminescence nanothermometer based on triple doped Ln -Y2O3 Methods and Applications in Fluorescence, 8, 2020, 035005.
Author: Yehia Sasa-Alexandra
Abstract:
Tehnologiile cu plasmă sunt promițătoare pentru decontaminarea apelor poluate datorită radicalilor puternic oxidativi, particulelor încărcate și radiației UV produși de plasmă. În acest studiu raportăm potențialul surselor de plasmă filamentară la presiune atmosferică cu barieră dielectrică (DBD) generate în radiofrecvență pentru decolorarea unei soluții de albastru de metilen (MB). S-au realizat și investigații de spectroscopie optică de emisie (OES) pentru caracterizarea plasmei ce evoluează în aer și imersată în lichid. Procesul de decolorare a fost monitorizat prin spectroscopia de absorbție.
Author: Marian Zamfirescu
Abstract:
Curs laseri
Author: Prof. Gheorghe Dinescu
Abstract:
Author: Prof. Ion Mihailescu
Abstract:
Author: Andrei Popescu
Abstract:
Author: Calin Atanasiu
Abstract:
Dezvoltarea de modele teoretice şi numerice pentru controlul activ al perturbaţiilor MHD în plasma tokamak C.V. Atanasiu1, L.E. Zakharov2, M. Hoelz3, S. Gerasimov4 1National Institute for Lasers, Plasma and Radiation Physics,2LiWFusion, Princeton, USA, 3Max Planck Institute for Plasma Physics, Garching, Germany, 4UKAEA-CCFE, Culham Science Centre, UK Instabilitǎțile MHD ale plasmei tokamak de tip kink ce ating peretele tokamak (Wall Touching Kink Modes – WTKM) se dezvoltǎ frecvent ȋn timpul evenimentelor de deplasare verticalǎ a plasmei tokamak (Vertical Displacement Events - VDE) cauzȃnd forțe laterale intense asupra peretelui tokamak, forțe ce sunt greu de stǎpȃnit ȋn instalțiile tokamak ITER și DEMO. Apariția ȋn aceste instalații tokamak a unui numǎr limitat de disrupții va deteriora ȋn mod definitiv peretele, fǎrǎ nicio posibilitate de restaurare. Ințelegere disrupțiilor plasmelor tokamak și prezicerea efectelor reclamǎ simularea realistǎ a curenților excitați ȋn structurile tri-dimensionale ale camerei de reacție de cǎtre plasma ce atinge peretele tokamak. La cererea comunitǎții de fuziune, codul de calcul elaborat de noi a primit statutul de «open source licence» putȃnd fi folosit de ȋntreaga comunitate europeanǎ de fuziune.