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Stark-Broadened Profiles of the Spectral Line P_α in He Ⅱ Ions

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Chinese Physics Letters 2016年第3期33卷 24-27页

作者：段斌 Muhammad Abbas Bari 吴泽清颜君王建国 institute of applied Physics and Computational mathematics Department of Physics and applied mathematics Pakistan Institute of Engineering and Applied Sciences

We report a systematic method to perform calculations of spectral line broadening parameters in plasmas. This method is applied to calculate Stark-broadening line profiles of Pα（n = 4 → n = 3） transitions under certain specific plasma conditions, by treating this case as an example. In the framework of the fully relativistic Dirac R- matrix theory, we calculate the electron-impact broadening operators, which are assumed to be diagonal matrix to simplify the situation. The electric microfield distribution function is calculated by retaining Hooper＇s formalism. The dipole matrix elements and atomic structure parameters used in these calculations have been obtained from atomic structure GRASP code. Based on this required data, we calculate the Stark-broadened line profiles of the Paschen spectral lines in He Ⅱ ions in a systematic manner. Overall, there is a very good agreement between our calculated Stark-broadened line profiles and other line Our reported spectral line-broadening data have real also play a fundamental role in plasma modeling. broadening numerical simulation codes （Sire U and MELS）. applications in plasma spectroscopy, plasma diagnosis and

关键词： Stark-Broadened Profiles of the Spectral Line P line on is II in He Ions of

Modelling of spall damage in ductile materials and its application to the simulation of the plate impact on copper

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Chinese Physics B 2012年第9期21卷 378-384页

作者：张凤国周洪强胡军邵建立张广财洪滔何斌 institute of applied Physics and Computational mathematics

A statistical model of dynamic spall damage due to void nucleation and growth is proposed for ductile materials under intense loading, which takes into account inertia, the elastic-plastic effect, and initial void size. To some extent, void interaction could be accounted for in this approach. Based on this model, the simulation of spall experiments for copper is performed by using the Lagrangian finite element method. The simulation results are in good agreement with experimental data for the free surface velocity profile, stress record behind copper target, final porosity, and void concentrations across the target. The influence of elastic-plastic effect upon the damage evolution is explored. The correlation between the damage evolution and the history of the stress near the spall plane is also analyzed.

关键词： spall damage ductile materials free surface velocity plate impact

Numerical simulations of instabilities in the implosion process of inertial confined fusion in 2D cylindrical coordinates

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Science China(Physics,Mechanics & Astronomy) 2016年第1期59卷 75-85页

作者： Heng Yong ChuanLei Zhai Song Jiang Peng Song ZhenSheng Dai JianFa Gu institute of applied Physics and Computational mathematics

In this paper, we introduce a multi-material arbitrary Lagrangian and Eulerian method for the hydrodynamic radiative multi-group diffusion model in 2D cylindrical coordinates. The basic idea in the construction of the method is the following： In the Lagrangian step, a closure model of radiation-hydrodynamics is used to give the states of equations for materials in mixed cells. In the mesh rezoning step, we couple the rezoning principle with the Lagrangian interface tracking method and an Eulerian interface capturing scheme to compute interfaces sharply according to their deformation and to keep cells in good geometric quality. In the interface reconstruction step, a dual-material Moment-of-Fluid method is introduced to obtain the unique interface in mixed ceils. In the remapping step, a conservative remapping algorithm of conserved quantities is presented. A munber of numerical tests are carried out and the numerical results show that the new method can simulate instabilities in complex fluid field under large deformation, and are accurate and robust.

关键词： material interfaces Rayleigh-Taylor instability Richtmyer-Meshkov instability arbitrary Lagrangian and Eulerian frame-work Moment-of-Fluid method

Mean-field potential calculations of high-pressure equation of state for BeO

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Chinese Physics B 2008年第4期17卷 1341-1348页

作者：张其黎张平宋海峰刘海风 institute of applied Physics and Computational mathematics

A systematic study of the Hugoniot equation of state, phase transition, and the other thermodynamic properties including the Hugoniot temperature, the electronic and ionic heat capacities, and the Gruneisen parameter for shockcompressed BeO, has been carried out by calculating the total free energy. The method of calculations combines first-principles treatment for 0 K and finite-T electronic contribution and the mean-field-potential approach for the vibrational contribution of the lattice ion to the total energy. Our calculated Hugoniot is in good agreement with the experimental data.

关键词： Hugoniot mean-field-potential,first-principles

Monte Carlo simulation for bremsstrahlung and photoneutron yields in high-energy x-ray radiography

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Chinese Physics B 2010年第6期19卷 213-220页

作者：许海波彭现科陈朝斌 institute of applied Physics and Computational mathematics

This paper reports on the results of calculations using a Monte Carlo code （MCNP5） to study the properties of photons, electrons and photoneutrons obtained in the converted target and their transportations in x-ray radiography. A comparison between measurements and calculations for bremsstrahlung and photoneutrons is presented. The radiographic rule and the effect of the collimator on the image are studied with the experimental model. The results provide exact parameters for the optimal design of radiographic layout and shielding systems.

关键词： x-ray radiography bremsstrahlung photoneutron energy spectrum angular distribution

Transport diffuse interface model for simulation of solid-fluid interaction

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applied mathematics and Mechanics(English Edition) 2019年第3期40卷 321-330页

作者： Li LI Qian CHEN Baolin TIAN institute of applied Physics and Computational mathematics

For solid-fluid interaction, one of the phase-density equations in diffuse interface models is degenerated to a "0 = 0" equation when the volume fraction of a certain phase takes the value of zero or unity. This is because the conservative variables in phasedensity equations include volume fractions. The degeneracy can be avoided by adding an artificial quantity of another material into the pure phase. However, nonphysical waves,such as shear waves in fluids, are introduced by the artificial treatment. In this paper,a transport diffuse interface model, which is able to treat zero/unity volume fractions, is presented for solid-fluid interaction. In the proposed model, a new formulation for phase densities is derived, which is unrelated to volume fractions. Consequently, the new model is able to handle zero/unity volume fractions, and nonphysical waves caused by artificial volume fractions are prevented. One-dimensional and two-dimensional numerical tests demonstrate that more accurate results can be obtained by the proposed model.

关键词： solid-fluid interaction diffuse interface model phase-density equation Mie-Gruneisen equation of state(EOS) Eulerian method

Mechanical, electronic, and thermodynamic properties of zirconium carbide from first-principles calculations

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Chinese Physics B 2015年第11期24卷 352-357页

作者：杨晓勇鲁勇郑法伟张平 institute of applied Physics and Computational mathematics

Mechanical, electronic, and thermodynamic properties of zirconium carbide have been systematically studied using the ab initio calculations. The calculated equilibrium lattice parameter, bulk modulus, and elastic constants are all well consistent with the experimental data. The electronic band structure indicates that the mixture of C 2p and Zr 4d and 4p orbitals around the Fermi level makes a large covalent contribution to the chemical bonds between the C and Zr atoms. The Bader charge analysis suggests that there are about 1.71 electrons transferred from each Zr atom to its nearest C atom. Therefore, the Zr-C bond displays a mixed ionic/covalent character. The calculated phonon dispersions of ZrC are stable, coinciding with the experimental measurement. A drastic expansion in the volume of ZrC is seen with increasing temperature, while the bulk modulus decreases linearly. Based on the calculated phonon dispersion curves and within the quasi-harmonic approximation, the temperature dependence of the heat capacities is obtained, which gives a good description compared with the available experimental data.

关键词： first-principles calculations mechanical properties electronic properties thermodynamic properties

Coherent spectroscopy of a strongly driven triple quantum dot molecule

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Chinese Physics B 2010年第11期19卷 576-583页

作者：解研段素青楚卫东杨宁 institute of applied Physics and Computational mathematics

Based on a calculation model, we study the interference phenomena of serially coupled ∨-type and ∧-type triple quantum dots （CTQDs） driven simultaneously by a strong driving field and a weak probe field. Strongly depending on the configuration of the three-level CTQD, the probe absorption spectra, which are shown in the tunneling current, exhibit various quantum coherence properties. In the case where the two pairs of transitions of the CTQD have a small eigenfrequency difference △ω, the double-coupling effect of the driving field results in two Autler Townes doublets and one weak Mollow triplet in one spectrum. With the value of △ω increasing, only one Autler-Townes splitting remains due to the single-coupling of the field. We also find that the effect of spontaneous emission of phonons may lead to an obvious background current, which can be used to distinguish which transition is driven by the driving field in experiment. The interesting quantum property of a CTQD revealed in our results suggests its potential applications in quantum modulators and quantum logic devices.

关键词： coherent spectroscopy coupled quantum dots quantum transport photon assistance

Transition from the Kondo effect to a Coulomb blockade in an electron shuttle

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Chinese Physics B 2013年第11期22卷 518-523页

作者：张荣楚卫东段素青杨宁 institute of applied Physics and Computational mathematics

We investigate the effect of the mechanical motion of a quantum dot on the transport properties of a quantum dot shuttle, Employing the equation of motion method for the nonequilibrium Green＇s function, we show that the oscillation of the dot, i.e., the time-dependent coupling between the dot＇s electron and the reservoirs, can destroy the Kondo effect. With the increase in the oscillation frequency of the dot, the density of states of the quantum dot shuttle changes from the Kondo-like to a Coulomb-blockade pattern. Increasing the coupling between the dot and the electrodes may partly recover the Kondo peak in the spectrum of the density of states. Understanding of the effect of mechanical motion on the transport properties of an electron shuttle is important for the future application of nanoelectromechanical devices.

关键词： quantum dot electron shuttle Kondo effect Coulomb blockade