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    Methane Conversion to Higher and Valuable Hydrocarbons by Non-Thermal Plasma

    , M.Sc. Thesis Sharif University of Technology Souri, Somayeh (Author) ; Sadighi Bonabi, Rasol (Supervisor)
    Abstract
    Methane conversion into higher hydrocarbons has been investigated by non-thermal plasma. The most important advantages of utilizing this type of plasma are atmospheric pressure and ambient temperature of the operating system. In order to prepare non-thermal plasma, a spark discharge reactor has been used with the main prospect of acetylene production. Other components such as hydrogen, ethylene and ethane are also formed in the process as by-products. By optimizing the affecting parameters on methane conversion and products selectivity, maximum methane conversion of 83.2% is obtained. Acetylene yield varies between 25%-63% with input gas flow rate, voltage, frequency and discharge volume.... 

    Self-focusing up to the incident laser wavelength by an appropriate density ramp

    , Article Laser and Particle Beams ; Volume 29, Issue 4 , 2011 , Pages 453-458 ; 02630346 (ISSN) Sadighi Bonabi, R ; Moshkelgosha, M ; Sharif University of Technology
    2011
    Abstract
    This work is devoted to improving relativistic self-focusing of intense laser beam in underdense unmagnetized plasma. New density profiles are introduced to achieve beam width parameter up to the wavelength of the propagating laser. By investigating variations of the beam width parameter in presence of different density profiles it is found that the beam width parameter is considerably decreased for the introduced density ramp comparing with uniform density and earlier introduced density ramp profiles. By using this new density profile high intensity laser pulses are guided over several Rayleigh lengths with extremely small beam width parameter  

    Theoretical investigation of electromagnetically induced phase grating in RF-driven cascade-Type atomic systems

    , Article Applied Optics ; Volume 54, Issue 11 , 2015 , Pages 3484-3490 ; 1559128X (ISSN) Sadighi Bonabi, R ; Naseri, T ; Sharif University of Technology
    2015
    Abstract
    A new scheme for investigating electromagnetically induced grating in four-level cascade-Type of 87Rb cold atoms is presented. The novel result indicates that the diffraction efficiency of phase grating is dramatically enhanced due to the presence of an RF-driven field and a diffraction efficiency up to 34% can be obtained. Furthermore, it is found that the frequency detuning of the applied laser fields with the corresponding atomic transition and the interaction length can improve the efficiency of the phase grating in the present atomic model. This work has potential applications in all-optical communication processes  

    Potential and energy of the monoenergetic electrons in an alternative ellipsoid bubble model

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 81, Issue 2 , 2010 ; 10502947 (ISSN) Sadighi Bonabi, R ; Rahmatallahpur, S ; Sharif University of Technology
    2010
    Abstract
    The electron acceleration in the bubble regime is considered during the intense laser-plasma interaction. The presented ellipsoid cavity model is more consistent than the previous spherical model, and it explains the monoenergetic electron trajectory more accurately. At the relativistic region, the maximum energy of electrons in the ellipsoid model is about 24% more than the spherical model, and this is confirmed by PIC and the measured experimental results reported here. The electron energy spectrum is also calculated, and it is found that the energy distribution ratio of electrons ΔE/E for the ellipsoid model in the here reported condition is about 11% which is less than the one third that... 

    A complete accounting of the monoenergetic electron parameters in an ellipsoidal bubble model

    , Article Physics of Plasmas ; Volume 17, Issue 3 , 2010 ; 1070664X (ISSN) Sadighi Bonabi, R ; Rahmatollahpur, S ; Sharif University of Technology
    2010
    Abstract
    A reliable analytical expression for the potential of plasma waves with phase velocities near the speed of light is derived. The presented ellipsoid cavity model is more consistent than the previous spherical model and it explains the monoenergetic electron trajectory more accurately especially in the relativistic regime. The electron energy spectrum is also calculated and it is found that the energy distribution ratio of electrons ΔE/E for the ellipsoid model in the here reported condition is about 10%, which is less than half that of the spherical model (25%) and it is in good agreement with the experimentally measured value of 12% under the same condition. The experimental measurements... 

    Laser induced sonofusion: A new road toward thermonuclear reactions

    , Article AIP Advances ; Volume 6, Issue 3 , 2016 ; 21583226 (ISSN) Sadighi Bonabi, R ; Gheshlaghi, M ; Sharif University of Technology
    American Institute of Physics Inc  2016
    Abstract
    The Possibility of the laser assisted sonofusion is studied via single bubble sonoluminescence (SBSL) in Deuterated acetone (C3D6O) using quasi-adiabatic and hydro-chemical simulations at the ambient temperatures of 0 and -28.5 °C. The interior temperature of the produced bubbles in Deuterated acetone is 1.6 × 106 K in hydro-chemical model and it is reached up to 1.9 × 106 K in the laser induced SBSL bubbles. Under these circumstances, temperature up to 107 K can be produced in the center of the bubble in which the thermonuclear D-D fusion reactions are promising under the controlled conditions. © 2016 Author(s)  

    Evaluation of transmutation of 137Cs(γ,n) 136Cs using ultra-intense lasers in solid targets

    , Article Chinese Physics Letters ; Volume 23, Issue 6 , 2006 , Pages 1434-1436 ; 0256307X (ISSN) Sadighi Bonabi, R ; Kokabee, O ; Sharif University of Technology
    Institute of Physics Publishing  2006
    Abstract
    Relativistic electrons produced in ultra-intense laser-solid interaction generate highly collimated γ-ray beams through Bremsstrahlung that can be used to induce photonuclear reactions. Photonuclear transmutation (of (γ,n) type) of 137Cs, one of the hazardous nuclear wastes with half-life of 30.17 years which cannot be transmuted practically with neutron bombardment due to its very low neutron capture cross section, has been considered. Nuclear activity of produced 136Cs with half-life of 13.16 days has been evaluated analytically using available experimental data. With irradiating a 137Cs sample by p-polarized laser light of 10 20Wcm-2 and the repetition rate of 10Hz for 30min, the activity... 

    The Measurement of Ultrashort Optical Parametric Oscillator Pulses

    , M.Sc. Thesis Sharif University of Technology Sadighi Bonabi, Sakineh (Author) ; Anvari, Abbas (Supervisor) ; Ebrahim-Zadeh, Majid (Supervisor) ; Sadighi Bonabi, Rasoul (Co-Advisor)
    Abstract
    The picosecond (ps) pulses in a synchronously pumped optical parametric oscillator (SPOPO) is generated by a 20W and 81.1 MHz Yb fiber laser at 1064nm, providing 11.7 W of total average power in near to mid-IR at 73% efficiency so that the signal pulse with a wavelength of 1560 nm and 7.1W average power and 3330 nm idler pulse with an average power of about 4.6W has been produced. The optical parametric oscillator (OPO), based on a 50 mm MgO:PPLN crystal with 5 gratings which is capable of withstanding large average powers without thermal effects.
    The duration of these ultrashort infrared signal pulse generated by the described SPOPO is measured by using homemade interferometric... 

    The evaluation of transmutation of hazardous nuclear waste of 90Sr, into valuable nuclear medicine of 89Sr by ultraintense lasers

    , Article Laser and Particle Beams ; Volume 28, Issue 2 , 2010 , Pages 269-276 ; 02630346 (ISSN) Sadighi, S. K ; Sadighi Bonabi, R ; Sharif University of Technology
    2010
    Abstract
    The analytical evaluation of the capability of Bremsstrahlung highly directional energetic γ-beam to induce photo transmutation of 90Sr (γ,n) 89Sr is presented. Photo transmutation of hazardous nuclear waste of 90Sr, one of the two main sources of heat and radioactivity in spent fuel into valuable nuclear medicine radioisotope of 89Sr is explained. Based on the calculations, a fairly decent fraction of gamma rays in this range are used in transmuting of 90Sr into 89Sr where according to the available experimental data it is shown that by irradiating a 1-cm thick 90Sr sample with lasers of intensity of 1021 W/cm2 and repletion rate of 100Hz for an hour, the reaction activity would be 1.45... 

    The electron density distribution and field profile in underdense magnetized plasma

    , Article Physics of Plasmas ; Volume 17, Issue 3 , 2010 ; 1070664X (ISSN) Sadighi-Bonabi, R ; Etehadi-Abari, M ; Sharif University of Technology
    2010
    Abstract
    In this work propagation of a high frequency electromagnetic wave in underdense plasma in presence of an external magnetic field is investigated. When a constant magnetic field perpendicular to the motion of electrons is applied, then the electrons rotate around the magnetic field lines and generate electromagnetic part in the wake with a nonzero group velocity. By using of the Maxwell equations and nonlinear differential equation for the electric field a direct one-dimensional (1D) procedure for calculating hydrodynamic equations are developed and the electric and magnetic field profiles in the plasma are investigated. It is shown that by using the external (dc) magnetic field in constant... 

    Survying the Process of Photodissociation of Methane with Using the Femto Second Lasers

    , M.Sc. Thesis Sharif University of Technology Irani, Elnaz (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    In this project , the dissociation of methane in the presence of Ti:Sapphire laser with parameters of 1014wcm-2, 800nm wave lengths and 100fs pulse width have been investigated theoretically, by using the Gaussian03 package –computational chemistry program that is capable of predicting many properties of atomic and molecular systems. It is based upon the fundamental laws of quantum mechanism. By considering some limitations in approximate techniques and incapability of advancing them, numerical calculation of solving the time dependent Schrödinger equation in order to improve the results and find more quantum dynamic information is applied. Therefore at first, by Gaussian03 package some of... 

    Effect of Laser Pulse Shape on the Plasma Wakefield

    , M.Sc. Thesis Sharif University of Technology Zare, Somaye (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    Plasma-based accelerators are capable of producing compact and high energy electron sources in much shorter distances than conventional accelerators. Electron will be trapped and accelerated to higher energy by two pulses as compared to the single pulse case. The aim of the present work is to take up a detailed analytical study of a novel idea of wakefield amplification making use of two laser pulses copropagating one behind the other, with a fixed distance between them. However, we attempt for enhancing the wake field and hence the electron acceleration by employing different shapes of the laser pulses  

    Effects of Target Profile on X-Rays Produced by Mono-Energetic Electrons Generated by Femtosecond Lasers

    , M.Sc. Thesis Sharif University of Technology Mahmoodkalayeh, Sadreddin (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    Considering the generation of quasi-monoenergetic electrons with femto-second Lasers, producing X-Rays using these electrons is of interest. Lately, higher efficiencies of x-ray generation have been demonstrated by bombardment of different metal slabs, with quasi-monoenergetic electrons instead of Maxwellian electrons. The goal of this research is to study how changing the geometry of the target will affect efficiency and angular distribution of generated X-rays. The electron source is defined using a theoretical model and experimental data. MCNP4C code has been utilized to simulate the collisions of these electrons with a metal target. Intensity and quality of generated X-Rays are obtained... 

    Investigate the Oscillations and Parameters of Bubble Induced by Laser in the Prescence of Acoustic Field

    , M.Sc. Thesis Sharif University of Technology Razeghi, Fatemeh (Author) ; Sadighi-Bonabi, Rasoul (Supervisor)
    Abstract
    Sonoluminescence is called a phenomenon in which a gas bubble is trapped in an antinode of a pressure field by a driven periodic acoustical field in a fluid and oscillations and at the end of each collapse, emits a flash. For this emission various conditions for stability must be satisfied, like diffusion stability, shape stability and positional stability. Another method to produce the bubbles is applications of a focused laser beam. In this method, a laser pulse is focused into a transparent buffer liquid like water and bubbles which are induced by the laser are so called Laser Induced Single Cavitation Bubble Luminescence (LI-SCBL). In the presence of the laser, the fluid acts as... 

    Production of Relativistic Mono-Energetic Electron Beams by Using Terawatt and Femtosecond Laser Pulses

    , M.Sc. Thesis Sharif University of Technology Fanaei, Masoumeh (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    In general cases, the generated electron beam with interaction of high intense and ultra short laser with gas plasma targets has large distributed energy spectrum (100%) that is called Quasi-maxwellian energy spectrum. Recently, in some experimental and 3D-PIC simulation results, a narrow band electron energy spectrum has observed that is called Quasi-monoenergetic electron. We approximated that these electrons have Gaussian distribution. High quality quasi-monoenergetic electron beam can focus in small spot. Therefore, there are many applications such as medical applications, crystallography with electron scattering, spectroscopy with soft energy and ultra fast x-ray, photonuclear... 

    Construction and Optimization of a Copper Chloride Laser

    , M.Sc. Thesis Sharif University of Technology Farhadi, Leila (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    Copper vapor Laser is one of the strongest and the most efficient visible laser with high repetition rate. It has been the subject of interest in research, industrial and clinical applications. It’s oscillating lines with 510.5 and 578.2 nm between resonance level and metastable level is acting as pulsed type laser. The problem with this laser is its high operating temperature of 1500 C. This high operating temperature could be reduced by using copper halides, where the temperature decreases from 400 to 500 C. The produced heat will first produce the molecular vapors, then the release and excitation of copper occurs with electrical discharge.
    In the present study the effect of... 

    , M.Sc. Thesis Sharif University of Technology Oghbaei, Saeeid (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    Quantum interference and coherence could change the optical response of media and results several effect such as electromagnetically induced transparency (EIT), Lasing Without inversion (LWI) and optical nonlinearityenhancement.In Quantum Computing, by using Quantum coherence, one can producedecoherence free sub-space whichhasoutstandingapplications in this field.
    In this work optical bistability behavior studied in two coupled quantum dots which resembles a three-level V type atomic system under influence of squeezed state reservoir. Spontaneously generated coherence (SGC) is responsible for Quantum interference. The squeezed state radiation could break the coherence in media and make... 

    Investigation of the Effective Parameters in the Attosecond X-Ray Spectrum Driven with Laser-Plasma Interaction in Relativistic Oscillating Surface

    , M.Sc. Thesis Sharif University of Technology Shirozhan, Mojtaba (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    With the invention of the Chirped Pulse Amplification (CPA) technique in 1985, it became possible to amplify ultra-short laser pulses to high intensities with suitable pre-pulses contrast. By considering the importance of the short wavelengths radiation sources, the interaction of the intense laser with dense plasma is one of the most promising routs to reach this goal.
    This thesis is devoted to theoretical studies of the interaction of intense laser pulses with solid-state targets. The Relativistically Oscillating Mirror (ROM) and the nanobunching regime models, which introduced in 2006 and 2010 respectively, are presented and discussed. The reflection of a laser pulse from an overdense... 

    Investigation of the Attosecond X-Ray Spectrum Driven with Laser-plasma Interaction in Relativistic Oscillating Surface Model

    , M.Sc. Thesis Sharif University of Technology Roustaie, Moslem (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Abstract
    With the invention of the Chirped Pulse Amplification (CPA) technique in 1985, it became possible to amplify ultra-short laser pulses to high intensities with suitable pre-pulses contrast. By considering the importance of the short wavelengths radiation sources, the interaction of the intense laser with dense plasma is one of the most promising routs to reach this goal.This thesis is devoted to theoretical studies of the interaction of intense laser pulses with solid-state targets. The Relativistically Oscillating Mirror (ROM) models, which introduced in 2006, is presented and discussed. The reflection of a laser pulse from an overdense plasma surface as the oscillating mirror, to the speed... 

    Ionization and Dissociation of the Chlorine Molecule by the Femtosecond Ti: Sapphire Laser Radiation

    , M.Sc. Thesis Sharif University of Technology Mostafaei, Anahita (Author) ; Sadighi-Bonabi, Rasoul (Supervisor)
    Abstract
    Ionization probability of Cl2 molecule is studied by irradiation of 800 nm Ti: Sapphire laser pulses at intensities of 1014 Wcm-2 to 1016 Wcm-2 with the Gaussian package. Molecular orbital symmetry and orientation of the molecule dipole moment with laser field polarization axis are very effective in ionization probability. The results show that the most ionization probability for the intensity of 1014 wcm-2 is at 900 and also 50 at intensity of 1016 wcm-2. Due to the lack of intrinsic dipole moment, variation of dipole moment with the intensity, bond length and time evolution of dipole moment are investigated. It is found that there is a linear dependance of these parameters with ionization...