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Pulse chirping effect on controlling the transverse cavity oscillations in nonlinear bubble regime

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Chinese Physics B 2017年第2期26卷 313-319页

作者： h Vosoughian Z Riazi h Afarideh G Sarri Laser and Optic Institute Nuclear Science and Technology Research Institute Tehran Iran physics and Accelerator School Nuclear Science and Technology Research Institute Tehran Iran Department of Energy Engineering and Physics Amirkabir University of Technology P. O. Box 15875-4413 Tehran Iran School of Mathematics and Physics The Queen's University of Belfast BT7 INN Belfast United Kingdom

The propagation of an intense laser pulse in an under-dense plasma induces a plasma wake that is suitable for the acceleration of electrons to relativistic energies. For an ultra-intense laser pulse which has a longitudinal size shorter than the plasma wavelength, λp, instead of a periodic plasma wave, a cavity free from cold plasma electrons, called a bubble, is formed behind the laser pulse. An intense charge separation electric field inside the moving bubble can capture the electrons at the base of the bubble and accelerate them with a narrow energy spread. In the nonlinear bubble regime, due to localized depletion at the front of the pulse during its propagation through the plasma, the phase shift between carrier waves and pulse envelope plays an important role in plasma response. The carrier–envelope phase（CEP） breaks down the symmetric transverse ponderomotive force of the laser pulse that makes the bubble structure unstable. Our studies using a series of two-dimensional（2D） particle-in-cell（PIC） simulations show that the frequency-chirped laser pulses are more effective in controlling the pulse depletion rate and consequently the effect of the CEP in the bubble regime. The results indicate that the utilization of a positively chirped laser pulse leads to an increase in rate of erosion of the leading edge of the pulse that rapidly results in the formation of a steep intensity gradient at the front of the pulse. A more unstable bubble structure, the self-injections in different positions, and high dark current are the results of using a positively chirped laser pulse. For a negatively chirped laser pulse, the pulse depletion process is compensated during the propagation of the pulse in plasma in such a way that results in a more stable bubble shape and therefore, a localized electron bunch is produced during the acceleration process. As a result, by the proper choice of chirping, one can tune the number of self-injected electrons, the size of accelerated bunch

关键词： bubble regime plasma wake field positively chirped laser pulse

SYNThESIS, ChARACTERIZATION AND SPECTROSCOPIC INVESTIGATION OF PYRAZINOPORPhYRAZINE NETWORK POLYMER-SUPPORTED METAL (Ⅱ)-BASED CATALYSTS

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Chinese Journal of Polymer Science 2013年第2期31卷 242-250页

作者： h.h. Abdel-Razik B.h. Asghar E. Kenawy Chemistry Department Faculty of Science Mansoura University Chemistry Department Faculty of Science Taif University Chemistry Department Faculty of Applied Sciences Umm Al-Qura University Chemistry Department Polymer Research Group Faculty of Science Tanta University

Chloranil through condensation reaction with vicinal diamine such as diaminomaleonitrile produced heterocyclic monomer, p-benzoquinonebis[2,3-b; 2＇,3＇-b＇]pyrazine-5,6-dinitrile. The tetranitrile monomer was cyclo-tetramerised using lithium/pentanol and acetic acid affording the corresponding tetrap-benzoquinone bis[2,3-b; 2＇,3＇-b＇]pyrazinoporphyrazine）]- based network polymer （2h-Pz）. The tetranitril monomer was cyclo-tetramerised using metal salt and quinoline affording the corresponding porphyrazinato-metal II-based network polymers （M-Pz）, M = Co, Ni or Cu. Elemental analytical results, IR and NMR spectral data of the prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses which confirm the efficiency of tetramerization polymerization and complexation reactions. The prepared pyrazinoporphyrazines were used as efficient catalysts for the oxidation of thiophenol and benzylthiol to their disulfides in the presence of air atmosphere. The results of oxidation of thiophenol and benzylthiol show that after 15 min the maximum yield of the corresponding disulfides reached 95%, 91%, respectively.

关键词： Pyrazinoporphyrazine Polymer-supported metal (II)-based catalysts Chloranil.

Comment on 'Mathematical structure of the three-dimensional (3D) Ising model'

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Chinese Physics B 2013年第8期22卷 356-360页

作者： Jacques h. h. Perk Department of Physics Oklahoma State UniversityStillwater OK 74078-3072 USA

The review paper by Zhang Zhi-Dong （Zhang Z D 2013 Chin. Phys. B 22 030513, arXiv：1305.2956） contains many errors and is based on several earlier works that are equally wrong.

关键词： Ising model Lie algebra series analysis thermodynamic limit

Quantum correlations and optical effects in a quantum-well cavity with a second-order nonlinearity

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Communications in Theoretical Physics 2021年第11期73卷 93-101页

作者： h Jabri higher Institute of Biotechnology of Beja University of JendoubaBeja 9000.Tunisia

In this paper,we investigate the photon correlations and the statistical properties of light produced by an optical cavity with an embedded quantum well interacting with squeezed *** show that the squeezed source substantially improves the intensity of the emitted light and generates a narrowing and a duplication of the spectrum *** a strong dependence on frequency detuning,the cavity produces considerably squeezed radiation,and perfect squeezing is predicted for weak light–matter ***,the system under consideration presents a bunching effect of the transmitted radiation resulting from weak pumping of the coherent *** results obtained may have potential applications in the fields of very accurate measurement and quantum computing.

关键词： quantum-well cavity second-order nonlinearity quantum fluctuations nonclassical effects

Calculation of the Specific heats for the Ⅱ—Ⅲ and Ⅱ—Ⅳ Phase transitions in Nh4I

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Chinese Physics Letters 2003年第1期20卷 35-38页

作者： h.Yurtseven h.Kaya Departmentofphysics IstanbulTechnicalUniversityMaslakIstanbulTurkey

This study gives our calculation for the specific heats CVI due to an Ising model using the observed CP data for the II-III and II-IV phase transitions in Nh4I. By fitting to the CP data we determine the values of the critical exponent for the pressure of 0.14 GPa (II-III phase transition) and for the pressures of 0.75, 1.35 and 1.97 GPa (II-IV phase transition) in Nh4I. Our exponent values are close to the predicted values of the specific heat in a three-dimensional Ising model. Our calculated CVI are in good agreement with the experimental CP for Nh4I in most cases.

关键词： Specific heat

Mechanical and microstructural characterization of Al7075/SiC nanocomposites fabricated by dynamic compaction

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International Journal of Minerals,Metallurgy and Materials 2014年第3期21卷 295-303页

作者： A.Atrian G.h.Majzoobi M.h.Enayati h.Bakhtiari Mechanical Engineering Department Bu-Ali Sina University Department of Materials Engineering Isfahan University of Technology

This paper describes the synthesis of Al7075 metal matrix composites reinforced with SiC, and the characterization of their microstructure and mechanical behavior. The mechanically milled Al7075 micron-sized powder and SiC nanoparticles are dynamically compacted using a drop hammer device. This compaction is performed at different temperatures and for various volume fractions of SiC nanoparticles. The relative density is directly related to the compaction temperature rise and indirectly related to the content of SiC nanoparticle reinforcement, respectively. Furthermore, increasing the amount of SiC nanoparticles improves the strength, stiffness, and hardness of the compacted specimens. The increase in hardness and strength may be attributed to the inherent hardness of the nanoparticles, and other phenomena such as thermal mismatch and crack shielding. Nevertheless, clustering of the nanoparticles at aluminum particle boundaries make these regions become a source of concentrated stress, which reduces the load carrying capacity of the compacted nanocomposite.

关键词： nanocomposites metallic matrix composites silicon carbide nanoparticles compaction

Solid-State Interfacial Reaction between Eutectic Au-Ge Solder and Cu/Ni(P)/Au Metalized Ceramic Substrate and Its Suppression

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Journal of Materials Science & Technology 2015年第5期31卷 445-452页

作者： F.Q.Lang h.Yamaguchi h.Nakagawa h.Sato Advanced Power Electronics Research Center(ADPERC) National Institute of Advanced Industrial Science and Technology(AIST).Central 21-1-1UmezonoTsukubaIbaraki 305-8568.Japan

Eutectic Au-12 Ge solder was employed to bond the SiC power devices to a Si3N4/Cu/Ni（P）/Au multilayered *** high-temperature reliability of the bond was investigated in detail at 200,250,300 and 330 ℃,*** and Ni5Ge3intermetallic compounds（IMCs） were identified at the Au-12Ge/Ni（P） interface by micro X-ray diffraction（μXRD） and scanning electron microscopy（SEM）equipped with energy dispersive X-ray analysis（EDX）.The growth of the Ni-Ge IMCs was dominated by Ni5Ge3layer,which formed at the Ni5Ge3/NiGe interface by outward diffusion of Ni from the Ni（P） *** activation energy of the total Ni-Ge IMCs growth was 66 kJ/*** shear strength of the bond was tested at both 25 ℃ and the aging temperatures,*** shear strength decreased slightly after aging at 200 and 250 ℃.The shear strength tested at 250 ℃ was 46 MPa after aging at 250 ℃ for 3000 *** shear strength aged at 300 and 330 ℃ rapidly decreased with aging time due to the rapid growth of the *** slow down the interfacial reaction between the high temperature solder and the Ni（P）layer,an approximately 200 nm-thick Ta/TaN/Ta new diffusion barrier（DB） was deposited on the *** by transmission electron microscopy（TEM） equipped with EDX,reveals that the Ta/TaN/Ta DB was bonded well to the Ni（P） layer and the *** temperature storage test at 330 ℃ for1500 h reveals that the bond of the SiC devices maintained its high shear strength of approximately56 MPa without *** new DB effectively suppressed the interfacial reaction between the Au-12 Ge solder and the Ni（P） layer of the substrate.

关键词： high-temperature solder Interfacial reaction Activ

A modified averaging scheme with application to the secondary hopf bifurcation of a delayed van der Pol oscillator

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Acta Mechanica Sinica 2008年第4期24卷 449-454页

作者： Z.h.Wang h.Y.hu Institute of Sciences PLA University of Science and Technology Nanjing 211101 China Institute of Vibration Engineering Research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In this paper, a modified averaging scheme is presented for a class of time-delayed vibration systems with slow variables. The new scheme is a combination of the averaging techniques proposed by hale and by Lehman and Weibel, respectively. The averaged equation obtained from the modified scheme is simple enough but it retains the required information for the local nonlinear dynamics around an equilibrium. As an application of the present method, the delay value for which a secondary hopf bifurcation occurs is successfully located for a delayed van der Pol oscillator.

关键词： Time delay ·Secondary hopf bifurcation·The averaging technique van der Pol oscillator

Numerical Solution of the Asymmetric Water Impact of A Wedge in Three Degrees of Freedom

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China Ocean Engineering 2013年第3期27卷 313-322页

作者： h. Ghazizade-Ahsaee A. h. Nikseresht Faculty of Mechanical & Aerospace Engineering Shiraz University of Technology

Impact problems associated with water entry have important applications in various aspects of naval architecture and ocean engineering. Estimation of hydrodynamic impact forces especially during the first instances after the impact is very important and is of interest. Since the estimation of hydrodynamic impact load plays an important role in safe design and also in evaluation of structural weight and costs, it is better to use a reliable and accurate prediction method instead of a simple estimation resulted by analyzing methods. In landing of flying boats, some phenomena such as weather conditions and strong winds can cause asymmetric instead of symmetric descent. In this paper, a numerical simulation of the asymmetric impact of a wedge, as the step of a flying boat, considering dynamic equations in two-phase flow is taken into account. The dynamic motion of the wedge in two-phase flow is solved based on finite volume method with volume of fluid （VOF） scheme considering dynamic equations. Then the effects of different angles of impact and water depth on the velocity change and slamming forces in an asymmetric impact are investigated. The comparison between the simulation results and experimental data verifies the accuracy of the method applied in the present study.

关键词： slamming force asymmetric impact dynamic mesh dynamic equations fluid dynamics