bluuebunny/crossref_metadata_2025 huggingface dataset:
Mei conserved quantity deduced from Mei symmetry of Appell equation in a dynamical system of relative motion
Authors: Luo Shao-Kai  , Jia Li-Qun  , Xie Yin-Li  ,   (1)Institute of Mathematical Mechanics and Mathematical Physics, Zhejiang Sci-Tech University,Hangzhou 310018, China; (2)School of Science Jiangnan University, Wuxi 214122, China
Published: December 2020

Mei symmetry and Mei conserved quantity deduced directly from Mei symmetry for Appell equations in a dynamical system of the relative motion are investigated. The definition and the criterion of Mei symmetry of Appell equations in a dynamical system of the relative motion under the infinitesimal transformations of groups are given. The expressions of the determining equation of Mei symmetry of Appell equations and Mei conserved quantity deduced directly from Mei symmetry in a dynamical system of the relative motion are gained. An example is given to illustrate the application of the results.
Hamiltonian spectrum for three coupled harmonic oscillators in non-commutative space
Authors: Zhang Xiu-Lan  , Liu Heng  , Yu Hai-Jun  , Zhang Wen-Hai  ,   (1)Department of Mathematics and Computer Science, Huainan Normal University, Huainan 232001, China; (2)Department of Physics and Electronic Information, Huainan Normal University, Huainan 232001, China
Published: December 2020

In non-commutative spaces the invariant eigen-operator method is used to derive and calculate Hamiltonian spectra for three kinds of three coupled harmonic oscillators: no coupling, coordinate coupling and momentum coupling. According to the comparison with the results in commutative space, it is shown that when the non-commutative parameter is zero the obtained energy levels are equal to the energy levels in commutative space. Finally the effect of the coupling coefficient on Hamiltonian spectrum in non-commutative space is discussed.
Cryptographic spatial chaos sequence
Authors: Sun Fu-Yan  , Lv Zong-Wang  ,   College of Information Science and Engineering Henan University of Technology, Zhengzhou 450001, China
Published: December 2020

In this paper, a novel pseudo-random sequence generator (PRSG) based on spatial chaos system is proposed. The statistical tests and correlation analysis on the proposed PRSG are performed by the well-known Federal Information Processing Standards FIPS140-1, and the experimental results show that the image encryption based on spatial chaos ergodic matrix has good random statistical characteristics, large key space and great sensitivity of the sequence.
Family of switched unified chaotic system
Authors: Liu Yang-Zheng  , Lin Chang-Sheng  , Li Xin-Chao  ,   Institute of Nonlinear Physics, Nanjing Institute of Technology,Nanjing 211167,China
Published: December 2020

A nonlinear function of unified chaotic system, the family of switched unified chaotic system is generated which contains six kinds of subsystems. Each subsystem can be switched by changing systematic parameter values in parameter space, and these subsystems can be switched continuously from one to another via changing nonlinear function in state space. The features of these subsystems are analyzed in detail using Lyapunov exponent and bifurcation diagram. The division-time switching of unified chaotic system is realized based on digital signal processing (DSP).
Phase-field simulation of Non-Isothermal dendritic growth of NiCu alloy
Authors: Wang Ming-Guang  , Zhao Yu-Hong  , Ren Juan-Na  , Mu Yan-Qing  , Wang Wei  , Yang Wei-Ming  , Li Ai-Hong  , Ge Hong-Hao  , Hou Hua  ,   Material Science and Engineering College,North University of China, Taiyuan 030051, China
Published: December 2020

Phase-field model is used and The dendrite growth of a Ni-40.83%Cu binaryalloy under were simulated by the model coupled with solute field and temperature field.The effects of solidification latent heat on the growth of equiaxed dendrite, distribution of solute field and temperature field in undercooled liquid alloy were analyzed.The results indicate that the dendritic has well-developed secondary arms as undercooling degree increases.Correspondently, the solute Peclet number and the tip speed increases, the tip radius decreases, and the solute segregation in solid-liquid interface increases. The results agree well with Ivantsov theory.
Exact solutions and soliton structures of (2+1)-dimensionalZakharov-Kuznetsov equation
Authors: Yang Zheng  , Ma Song-Hua  , Fang Jian-Ping  ,   College of Mathematics and Physics, Zhejiang Lishui University, Lishui 323000, China
Published: December 2020

With the help of the symbolic computation system Maple and an improved Riccati equation mapping approach, a series of exact solutions of the (2+1)-dimensional Zakharov-Kuznetsov equation (ZK) is derived. Based on the derived solution, we obtain some special soliton structures.
Influence of nanowire heterostructure on performanceof electron refrigerator
Authors: He Ji-Zhou  , Miao Gui-Ling  , He Bing-Xiang  ,   (1)Department of Physics, Nanchang University, Nanchang 330031, China; (2)Yingtan Vocational & Technical College, Yingtan 33500, China
Published: December 2020

In this paper, the electron transports through a three-barrier nanowire heterostructure between two reservoirs with different temperatures and chemical potentials are studied. The transport probability of electron is obtained by using the transfer matrix method,and the heat flow carried by the electrons transfer is calculated out. The performance characteristic curves of the refrigerator are plotted by numerical calculations. The influence of bias voltage and heterostructure on the performance of the refrigerator is analyzed. Especially, the effects of the height and the width of the middle barrier on transport probability, cooling rate, and colling coefficient are emphasized.
High sensitivity slow light interferometer based on dispersiveproperty of Ⅲ-Ⅴ and Ⅱ-Ⅵ semiconductor materials
Authors: Cai Yuan-Xue  , Zhang Yun-Dong  , Dang Bo-Shi  , Wu Hao  , Wang Jin-Fang  , Yuan Ping  ,   National Key Laboratory of Tunable Laser Technology, Institute of Optoelectronics, Harbin Instituteof Technology, Harbin 150080, China
Published: December 2020

We investigate the optical properties of Ⅲ-Ⅴ and Ⅱ-Ⅵ semiconductors. The results show that the sensitivity of the interferometer can be greatly enhanced by the dispersive property of semiconductor. Furthermore, the analyses show that the semiconductor slow light medium has a more wider working spectral range than gas slow light medium. Moreover, we experimentally demonstrate that the sensitivity of the interferometer based on the semiconductor GaAs is 3.2 times higher than those of traditional interferometers.
Mechanical model of tuning forks used in scanning probe microscopes
Authors: Qian Jian-Qiang  , Wang Xi  , Yao Jun-En  , Hua Bao-Cheng  ,   (1)Department of Applied Physics, Beihang University, Beijing 100191, China; (2)School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing 100191, China
Published: December 2020

Quartz tuning forks have been widely used as force sensors in scanning probe microscopes. The anti-phase and in-phase eigenmodes of a tuning fork are involved during microscope operations. Dynamic characteristics of both eigenmodes are studied by experiments and finite element analysis simulations. It is demonstrated that elastic couplings exist between not only both the prongs but also two prongs and the base of the tuning fork. Experimental results show that the coupling between both the prongs increases the anti-phase mode eigenfrequency while the coupling between two prongs and the base of the tuning fork decreases the in-phase mode eigenfrequency. A mechanical model of the tuning fork is introduced and simplified. Parameters of the simplified model are calculated, which is described as a four-springs-three-point-masses system. The quantitative relation between the effective mass of one prong and the eigenfrequency of the anti-phase mode of the mechanical model is in good agreement with that of finite element simulations.
Single attosecond pulse generated by atom exposed to two laser pulses with the same color and half cycle pulses
Authors: Pan Hui-Ling  , Li Peng-Cheng  , Zhou Xiao-Xin  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

By solving numerically the time-dependent Schrödinger equation with the split-operator method, we investigate the characteristic of the high-order harmonic of one-dimensional helium atom exposed to two laser pulses with the same color and half cycle pulses. It is shown that the harmonic spectrum is extended to Ip+9.6Up in the case of the combined fields, and an isolated 63 as pulse can be obtained by superposing the high-order harmonic spectra generated around the cut-off position. An analysis shows that the plateau of the high-order harmonic spectrum is extended greatly and the contribution of the long electron trajectory is suppressed by adding the half cycle pulses.
Experimental study on a high power microwave amplifier driven by low rf power
Authors: Wu Yang  , Xu Zhou  , Xu Yong  , Jin Xiao  , Chang An-Bi  , Li Zheng-Hong  , Huang Hua  , Liu Zhong  , Luo Xiong  , Ma Qiao-Sheng  , Tang Chuan-Xiang  ,   (1)Department of Engineering Physics, Tsinghua University, Beijing 100084, China; (2)Institute of Applied Electronics, CAEP, Mianyang 621900, China
Published: December 2020

In order to suppress high order mode self-oscillation in a high gain amplifier, some special procedures, such as decreasing the coupling between beam and rf field in the forepart of the amplifier, are taken such that the tube works in a fully amplified state in an operation range. In simulation, the rf output power is 1.7 GW with a beam of 7.5 kA at 750 kV when input power is 6.8 kW and the corresponding gain is 53.9dB. Based on the results from 2D PIC simulation, the experiment is performed on the Sinus accelerator. In experiment, the amplifier is driven by a beam of 8 kA at 800 kV, and the maximum output power is 2.04 GW when input power is 62 kW; the maximum gain reaches 46.7dB when the input reduces to 39 kW, the corresponding output power is about 1.84 GW. Both the simulation and the experiment prove that a kW-level rf power can drive the tube to generate a GW-level output power.
Automatic procedure for non-coplanar aberration compensation in lensless Fourier transform digital holography
Authors: Cui Hua-Kun  , Wang Da-Yong  , Wang Yun-Xin  , Liu Chang-Geng  , Zhao Jie  , Li Yan  ,   College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
Published: December 2020

When the lensless Fourier transform digital holography is applied to the microscopic phase-contrast imaging on live cells, the motion of cells will lead to a non-coplanary phenomenon between the object recorded and the reference source. This could result in the imaging aberration. An effective and robust autofocus procedure based on the phase distribution is presented in the paper. With the initial measurement of the distance between the reference source and the hologram, the optimal parameters corresponding to the phase-contrast image can be achieved by a single hologram combined with the linearity fitting. Lensless Fourier transform digital holographic system is built and the experiments on the phase-contrast imaging of the live cervical carcinoma cells are performed. Finally, the good experimental results are obtained. Both the theoretical analysis and the experimental investigation verify the feasibility and the validity of the automatic procedure for non-coplanar aberration compensation.
Studys of characteristics for pump-induced emission and anharmonic cavity-QED in quantum dot-cavity systems
Authors: Chen Xiang  , Mi Xian-Wu  ,   College of Physics Science and Information Engineering Jishou University,Jishou 416000,China
Published: December 2020

Theoretical derivation and numerical calculation achieve the quantum dot numerically exact multi-photon emission spectra starting from the interaction of quantum dot and cavity,using the master equation that includes incoherent pumping and pure dephasing and combines with the quantum regression theorem, and considering the relevant initial conditions.Then comparing the multi-photon(fermion statistics) spectra with the one-thoton(boson system) correlation level, our analysis shows that according to the fermion statistics the pure dephasing, and the thermal bath model, an excellent fitting to the data is obtained with the recent experimental of Ref[22] results in a quantum dot-micropiller cavity system. The theory and the recent experiments both show pump-induced stimulated emission and anharmonic cavity-QED in quantum dot-cavity systems.
Longitudinally polarized subwavelength beam generated by focusing radially modulated Bessel-Gaussian beam
Authors: Yu Yong-Jiang  , Chen Jian-Nong  , Yan Jin-Liang  , Wang Fei-Fei  ,   College of Physics, Ludong University, Yantai 264025,China
Published: December 2020

Longitudinally polarized subwavelength beams have found many applications such as particle acceleration, single molecule dipole detection, second harmonic generation imaging, longitudinally polarization confocal microscopy. We present a radially modulated Bessel-Gaussian beam model which produces longitudinally polarized beams with high purity after being focused by high numerical aperture objective. Based on the vector diffraction theory, the electric field intensity distribution, magnetic field intensity distribution and energy flux density near the focal plane are numerically simulated. The result shows that the full-width at half-maximum is as small as 0.4λ. The method does not require a physical annulus or annular phase filter and it features high energy efficiency, high resolution, thus improving application performances.
Three-dimensional numerical simulation of light field modulation in the vicinity of inclusions in silica subsurface
Authors: Hua Jin-Rong  , Li Li  , Xiang Xia  , Zu Xiao-Tao  ,   Institute of Physics and Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

One of the important factors of the low laser induced damage threshold is the defects in the subsurface of fused silica. The three-dimensional model of a spherical inclusion in the subsurface is established in this study. Three-dimensional finite-difference time-domain method is used to calculate and simulate the light field distribution in the vicinity of inclusions. The effects of dielectric constant and inclusion size are analyzed, separately. The results show that the light intensity enhancement factor (LIEF) does not change with the size and the dielectric constant of the inclusions when the dielectric constant is smaller than that of fused silica, where the LIEF is kept at about 4. When the dielectric constant is 6.0, the LIEFs are 50.1588, 73.3904 and 102.9953 for the inclusions with sizes of 1.5λ, 2λ and 2.5λ respectively. When the inclusion size is constant, the LIEF will increase with the increase of dielectric constant. The light enhancement for the round inclusions is much higher than that for the ellipsoidal inclusions. Therefore, the round inclusions with large size and dielectric constant significantly enhance the electric field.
Stochastic resonance with frequency noise in a linear model of single-mode laser
Authors: Cao Li  , Zhang Liang-Ying  , Jin Guo-Xiang  ,   (1)Hubei Province Key Laboratory of Intelligent Robot, Wuhan Institute of Technology, Wuhan 430073, China; (2)School of Physics and Electronic Engineering, Xiangfan University, Xiangfan 441053, China; (3)School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

By adding a periodic signal of the fluctuating frequency to the gain-noise model of the single-mode lasers, we calculate the correlated function and power spectrum of the output laser intensity and discuss the variation of signal-to-noise ratio(SNR) with the intensity of the noise and system parameter. The result indicates that the SNR shows stochastic resonances with the variations of intensities of the frequency noise, pump noise and quantum noise, also with the variations of gain coefficient and loss coefficient.
Evaluation of surface potential barriers after activation of GaAs photocathode
Authors: Niu Jun  , Zhang Yi-Jun  , Chang Ben-Kang  , Xiong Ya-Juan  ,   School of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

According to the ratios of the peak-values of photocurrents arising separately during the single Cs activation and during the Cs-O activation for negative electron affinity(NEA) GaAs photocathode, and the theoretical energy distributions of the photoelectrons passing separately through the single and the double potential barriers, a new method of evaluating the surface potential barrier parameters of NEA GaAs photocathode is presented. The results obtained by this method accord well with the double-dipole model theory and are in agreement with the results by fitting the experimental electrons energy distribution curve. The method is simple and efficave, which enriches the approaches to the evaluation of activation effect and surface characteristic of NEA GaAs photocathodes without increasing other test means.
Mach-Zehnder interferometer designed based on self-collimating beams and photonic band gap in photonic crystals
Authors: Han Kui  , Wang Zi-Yu  , Shen Xiao-Peng  , Wu Qiong-Hua  , Tong Xing  , Tang Gang  , Wu Yu-Xi  ,   Department of Physics, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

We propose a compact, high efficient full photonic crystal Mach-Zehnder (MZ) interferometer based on the self-collimation and photonic band gap in two-dimensional photonic crystals. Line defected photonic crystals are used as the beam splitter and the mirror. The interference theory is used to discuss the interferometer output mechanism, and compared with the finite-difference time-domain (FDTD) simulation results. The designed MZ interferometer can surve as micro-detectors of gas and liquid, which may play an important role in integrated optics.
Comb-filter based on two core fiber coupler and its CO2 laser trimming
Authors: Jiang Wei-Wei  , Fan Lin-Yong  , Zhao Rui-Feng  , Wei Yan  , Pei Li  , Jian Shui-Sheng  ,   Institute of Lightwave Technology, Beijing Jiaotong University,Key Lab of All Optical Network & Advanced Telecommunication Network of EMC,Beijing 100044, China
Published: December 2020

According to the wavelength characteristic of fiber coupler,its spectrum characteristics was analysed as a comb filter, and all-fiber comb-filter based on fiber couplers with different wavelength intervals were experimentally fabricated by splicing a section of single mode twin-core fiber (TCF) of different lengths between two single mode fibers (SMFs),and the extinction ratio is 25 dB. CO2 laser was used to trim the wavelength firstly,which results in the spectrum shifting to long wavelength and the change of extinction ratio.The trimming is based on the mechanism of residual stress and melting deformation between fiber and CO2 laser,and hydrogen-loaded TCF was used to improve the trimming efficiency.
Analytic method of studying defect mode of 1D doped phononic crystal
Authors: Liu Qi-Neng  ,   Calculator Science College of Chongqing Technology and Business University, Chongqing 400067, China
Published: December 2020

For the analytic study of the defect mode of 1D doped phononic crystal, the multiple-beam interference method and Bloh theorem are adopted, the analytical formula of defect mode is derived and the defect mode of 1D doped phononic crystal is studied. The varition law of defect mode is obtained. The method in freed from the weaknewes of other methods that cannot carry on the analysis of defect mode. The method is valid and accurate method of studying the defect mode of 1D doped phononic crystal.
A Method of constructing canonoid transformations
Authors: Ding Guang-Tao  ,   The College of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
Published: December 2020

A method of constructing canonoid transformations with respect to a Hamiltonian is presented. First, the Hamiltonian system is transformed into a Birkhoffian system. Second, the Birkhoffian system is transformed into a new one under gauge transformation. Finally, the Hamiltonization of new Birkhoffian system is realized. It is pointed out that there exist many different canonoid transformations for one Hamiltonian system. Two examples are given to illustrate the application of the results.
A cryptosystem based on simple physical models
Authors: Zhou Qing  , Chen Gang  , Hu Yue  ,   College of Computer Science, Chongqing University, Chongqing 400044, China
Published: December 2020

It is well known that some simple physical models can lead to complex behaviors. Moreover, some simple models possess a strongly logical expression ability. A cryptosystem is proposed based on two simple physical modes, which has the performances of its reversibility, parallelism, simplicity and efficiency. The simulation results show that the system presents satisfactory randomness and sensitivity. It is a promising method to use simple physical models for constructing a good cryptosystem.
Stability of fractional state space system and its application to fractional order chaotic system
Authors: Huang Li-Lian  , He Shao-Jie  ,   College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

In this paper, an stability theorem is proposed for a fractional state space system based on Lyapunov stability theory. Controller can be achieved easily by this theory without calculating any equilibrium point. The fractional unified chaotic system is used to improve the stability theorem. The effectiveness of the theory is verified by the simulation results.
Experiments on the generation of internal wavesby a hemispheroid in a linearly stratified fluid
Authors: Wei Gang  , Wu Ning  , Xu Xiao-Hui  , Su Xiao-Bing  , You Yun-Xiang  ,   (1)Department of Applied Math. and Phys. PLA Univesity of Science and Technology, Nanjing 211101, China; (2)Department of Naval Architecture and Ocean Engineering, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

Experiments are conducted to examine the characteristics of internal waves generated by a towing hemispheroid model alongside the side wall of stratified fluid flume with a linear density distribution. By the measured results with multi-channel conductivity arrays, the wave patterns, the vertical displacement and the correlation velocity for such internal waves are analyzed. Two distinct types of internal waves are obtained in experiments. One is the body-generated internal wave by the steady source with respect to the hemispheroid model, and the other is the wake-generated internal wave by the unsteady source. The transition between these two types of internal waves occurs at a critical Froude number of FrS=1.6. The corresponding comparison with towing spheroid model experiments is carried out. It follows that the number FrS is about 2/3 that of the spheroid and that the transition is more rapid and its borderline is more clear-cut than those of the spheroid modes. The body-generated internal waves of both experimental models have identical characteristics, but the draining-water volume is about 2/3 that of the spheroid model. Their wake-generated internal waves possess similar variation tendencyies, but their wave speed is about 2/3 that of the spheroid model . It also proves that this mirror-image experimental method in the flume can increase the effective range of spatio-temporal evolvement of body-generated internal waves.
Performance of shock ignition with varying ignitor
Authors: Yuan Qiang  , Hu Dong-Xia  , Zhang Xin  , Zhao Jun-Pu  , Hu Si-De  , Huang Wen-Hui  , Wei Xiao-Feng  ,   (1)Department of Engineering Physics, Tsinghua University, Beijing 100084, China; (2)Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In this paper, the performance of shock ignition with varying ignitor is analyzed theoretically and simulated numerically. First, based on the formation and the collision of shock waves, effects of ignitor pulse on shock ignition are investigated theoretically. Then simulations are performed using a variety of ignitor pulses, determined by their peak powers, pulse widths and rise times, and the ignition window is employed as an evaluation criterion of the shock ignition performance. The obtained results show that the peak power of ignitor pulse is one of the key factors to successfully ignite the core, and the ignitor pulse must be wide enough to provide sufficient ignition energy, however, as the rise time of ignitor is not so long(~ns), it will not degrade the performance of shock ignition significantly.
New results of Sino-Russian joint Z-pinch experiments
Authors: Zhang Fa-Qiang  , Wang Zhen  , Xu Ze-Ping  , Jiang Shi-Lun  , V. P. Smirnov  , Ning Jia-Min  , Li Lin-Bo  , Zhou Xiu-Wen  , E. V. Grabovsky  , G. M. Oleynic  , V. V. Alexandrov  , Ding Ning  , Xu Rong-Kun  , Li Zheng-Hong  , Yang Jian-Lun  ,   (1)Institute of Applied Physics and Computational Mathematics, Beijing 100088, China; (2)Institute of Nuclear Physics and Chemistry, Mianyang 621900, China; (3)Research Center of Laser Fusion of China Academy of Engineering Physics, Mianyang 621900, China; (4)Troitsk Institute for Innovation and Thermonuclear Researches, Troitsk 142190, Russia
Published: December 2020

Dynamics of double tungsten-wire array and dynamic hohlraum are investigated on the Angara-5 facility. X-ray power and hohlraum temperature are obtained to be as high as 5.6 TW and 63 eV respectively. Main experimental results together with the design idea are also given in this paper.
Molecular dynamics simulations of low-energy Clatoms etching Si(100) surface
Authors: He Ping-Ni  , Ning Jian-Ping  , Qin You-Min  , Zhao Cheng-Li  , Gou Fu-Jun  ,   Institute of Plasma Surface Interactions, Guizhou University, Guiyang 550025, China
Published: December 2020

In this study, molecular dynamics simulation method is used to investigate the interactions of Cl continuously bombarding a crystalline Si (100) surface in an incident energy range of 0.3—10 eV.The surface temperature is set to be 300 K for all the incident energies. The improved Tersoff-Brenner type potential is employed.The simulation results show that a Cl-rich reaction layer is formed on the surface due to Cl continuously bombarding. The SiCl group is the predominant species in the reaction layer.The thickness of the reaction layer increases with incident energy. The etching ratio increases with incident energy increasing. The main etching product is SiCl4 when the incident energies are 0.3, 1 and 5 eV, but it is SiClx(x<4) when the incident enery is 10 eV.With the incident energy increasing, the main etching mechanism changes from chemical etching to physical etching.
Characteristics of emission spectroscopyof radiatively heated Al plasma
Authors: Pu Yu-Dong  , Yang Jia-Min  , Jin Feng-Tao  , Zhang Lu  , Ding Yong-Kun  ,   Research Center of Laser Fusion of China Academy of Engineering Physics,Mianyang 621900,China
Published: December 2020

The X-ray spectrum of radiatively heated tracer Al in the doped foam was recorded by using a flat crystal spectrometer. The radiation thermal bath with a peak temperature of 150 eV is created inside the hohlraum irradiated by 8 laser beams, each delivering 250J. From the measured spectrum, we have observed that the intensities of jkl Li-like satellite were smaller than those of qr Li-like satellites, which is not a case usually encountered in electron collision dominated low density plasmas. The analyses of various generation and loss channels of doubly excited states indicate that in the radiatively heated plasma considered in the present work, the photo excitation and the photo ionization processes are fully responsible for the generation of doubly excited states instead of dielectronic recombination. Besides the satellite features, intercombination lines are also observed which imply the existence of a low density plasma region. Finally, we compare the calculated spectrum with the measured spectrum, and find that they are in fairly good agreement was achiered.
High dynamic range imaging and application to laser-plasma diagnostics in inertial confinement fusion (ICF) experiment
Authors: Cao Zhu-Rong  , Zhang Hai-Ying  , Dong Jian-Jun  , Yuan Zheng  , Miao Wen-Yong  , Liu Shen-Ye  , Jiang Shao-En  , Ding Yong-Kun  ,   Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

High dynamic range and large format technique of micro-chanunel plate (MCP), gated framing camera is developed to diagnose high-power laser-plasma X-ray emission spectra. The single frame format is 13 mm×36 mm, and exposure time is adjustable from 0.5 ns to 5 ns. Its spectral response in 1.0—10 keV is more flat than that of X-ray charge-coupled device (CCD), and there exists no energetic enhancement effect. Performance evaluation has been conducted on high power laser devices, and the results show that the system has a high signal-to-noise ratio and the dynamic range is greater than 3 × 103. The system has been applied successfully to inertial confinement fusion (ICF) physics experiment.
Effect of surface rubbing alignment on electro-optical properties of holographic polymer dispersed liquid-crystal gratings
Authors: Li Wen-Cui  , Liu Yong-Gang  , Xuan Li  ,   State Key Laboratory of Applied Optics,Changchun Institute of Optics, Fine Mechanics and Physics,Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

In order to obtain holographic polymer dispersed liquid crystal( HPDLC) grating with high diffraction efficiency and low threshold, the effect of parallel rubbing alignment on electro-optical properties of HPDLC grating is investigated. According to the theoretical analysis, the improvement of phase separation structure and the lower order difference of the liquid crystal droplets are essential for perfect electro-optical properties of the grating. The phase separation is significantly improved due to the diffusion match between monomers and liquid crystals in the case of parallel alignment treatment. So the diffraction capability is enhanced while the driven voltage is reduced obviously. Moreover, the order difference of liquid crystal droplets is reduced because of the uniform liquid crystal alignments and consequently the scattering loss is reduced greatly. Experimental results indicate that the diffraction efficiency of grating with rubbing alignment increases from 75.6% (traditional HPDLC grating) to 98.1% and the driving voltage is lowered from 9.2 V/μm to 4.8 V/μm. And also, only in the case of certain surface rubbing strength, the HPDLC with high diffraction efficiency and low threshold will be realized.
A new method of rigid-body refinementfor protein crystal structures
Authors: Ding Wei  , Jiang Fan  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

A new rigid-body refinement method for protein crystal structures is described. It is based on "Variable Metric Methods in Multidimensions" and "the Electron Density Map Correlation Coefficient". Test shows that the orientation and translation of the initial models can be improved effectively by this new method. And it can escape from the local extremum and reach the global optimum more easily than the maximum likelihood method when the search space has a large number of local extremum points.
Molecular dynamics simulation of radiation displacement effect in BaTiO3 ferroelectrics
Authors: Ma Ying  , Sun Ling-Ling  , Zhou Yi-Chun  ,   Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105,China
Published: December 2020

Radiation displacement effect is studied using shell model molecular dynamics simulations. Using oxygen atom as a primary knock-on atom, the creation and the evolution of various defects in the system corresponding to the primary knock-on atom(PKA) energy of 1 keV are studied. The results show that a largest number of defects are created when the incidence is along the [001]direction. Among all the defect species, oxygen atom defects are dominant, and its concentration reaches 80%. The creation of defects does not change the spontaneous polarization of the system significantly, and the polarization reversal also changes little. Defect migration is observed under an applied electric field.
Phase transition and influence of phase transitionon spall in α phase Fe-based alloy
Authors: Chen Yong-Tao  , Tang Xiao-Jun  , Li Qing-Zhong  ,   Laboratory for Shock Wave and Detonation Physical Research, Institute of Fluid Physics,China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

This paper provides an investigation of the phase transition and the spalling characteristics induced during shock loading and unloading in an α phase Fe-based alloy. Two kinds of impact set-ups are used. One is referred to as the direct impact, and the other is the reverse impact. The shock Hugoniot and the release stress-volume adiabat of the α phase Fe-based alloy are obtained. And the results show that the history of loading and unloading is determined by the relationship among the phase transition threshold and the reverse transition threshold and the shock pressure. It is found that abnormal spallations happen in the α phase Fe-based alloy sample as the pressure exceeds the phase transition threshold. Such abnormal spalling phenomena are believed to be related to the shocked α→ε phase transition, and a possible reason for the abnormal spalling is discussed also from the interaction process of stress wave.
Relationship between liquid structure and property Ⅰ— Kinematic viscosity of magnesium melt and its relationship with the microstructure
Authors: Сабирзянов А А  , Попель П С  , Mi Guang-Bao  , Li Pei-Jie  , Охапкин А В  , Константинова Н Ю  ,   (1)National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084, China; (2)Научно-исследовательскый центр "Расплав", Уральский Государственный Педагогический Университет, Екатеринбург 620017, Россия
Published: December 2020

The method of crucible rotating oscillation damping was employed to measure the kinematic viscosity of magnesium melt and the curve of viscosity v versus temperature T from 935 K to 1190 K was obtained. It is exponential increase (decrease) law of viscosity with the temperature during heating and cooling process; Besides, based on the physical model for evolution behavior of atomic cluster in liquid structure, the main structural information of magnesium melt in this temperature interval — the curve of size d of atomic cluster versus temperature T was obtained; By analyzing the experimental and calculated data, it is found that both kinematic viscosity and size of atomic cluster of magnesium melt are monodrome function of the temperature and the relation between them is linear function, i.e., v=v0 + K·d(T). This relation reveals the change characteristic of viscosity for magnesium melt microstructure, which presents a new way for calculating kinematic viscosity of metal melt and understanding the micro-nature deeply.
Theorectical study of the oxide-ion conductorLa2Mo2-xMxO9(M=Cr,W)
Authors: Chen Yue-Yun  , Hou Chun-Ju  , Kong Xiang-Shan  , Liu Chang-Song  , Wang Xian-Ping  , Fang Qian-Feng  ,   Institute of Solid State Physics Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

We perform the first-principles study of the structural properties and the high temperature phase stabilization of Cr, W-doped β-La2Mo2O9. We find that Cr prefers the site with four coordination numbers and W atom preferentially occupies the site with five coordination numbers. The nonlinear dependence of cell parameter on W content in W-doped systems results from the nonlinear change in Mo(W)-O and La-O bond lengths with W content and the decrease of coordination number around W occupied site. The decrease of cohesive energy with the W-doped concentration is conducive to the understanding of the stabilization of the β-La2Mo2-xWxO9 at lower temperature. The appearance of stronger W-O bond leads to the increase of the energy barrier of oxygen-ion concerted motion in W-dopedβ-La2Mo2O9.
The experiential fit of the capacitance-voltage characteristicsof the AlGaN/AlN/GaN high electron mobility transistors
Authors: Wang Xin-Hua  , Zhao Miao  , Liu Xin-Yu  , Pu Yan  , Zheng Ying-Kui  , Wei Ke  ,   Key Laboratory of Microelectronics Device & Integrated Technology, Institute of microelectronicsof Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

This paper expresses the experiential relationship between Fermi level and the density of two-dimensional electron gas, based on the capacitance voltage (C-V) characteristics of the AlGaN/AlN/GaN high electron mobility transistor (HEMT) on sapphire substrate. The expression provides important references for establishing the device charge control model and simpliying the transconductance and capacitance. Parameter α is introduced for describing the ability for the two-dimensional potential well to restrict electrons, and we believe that the smaller the value of α, the stronger the restricting ability is. A coherent fitting effect, compared with the measurement, is obtained by making use of the experiential relationship said above.
Electronic structure and magnetic propertiesof post-perovskite CaRhO3
Authors: Wang Jiang-Long  , Ge Zhi-Qi  , Li Hui-Ling  , Liu Hong-Fei  , Yu Wei  ,   College of Physics Science & Technology, Hebei University, Baoding 071002, China
Published: December 2020

Electronic structure and magnetic properties of Post-perovskite CaRhO3 have been studied by density functional theory calculations through using the projected augmented wave method. The Generalized-gradient approximation (GGA) calculations indicate a half-metallic ferromagnetic ground state and a low-spin configuration of Rh4+ ion with a magnetic moment of 0.57μB. While the experimental insulating antiferromagnetic ground state can be obtained only by GGA plus on-site Coulomb interaction U(GGA+U) calculations, which indicates the crucial role of corelation effect of 4d electron for the Post-perovskite CaRhO3.
First-principles study on influence of alloying element substitution on dehydrogenation ability of Li4BN3H10 hydrogen storage materials
Authors: Zhang Hui  , Zhang Guo-Ying  , Xiao Ming-Zhu  , Lu Guang-Xia  , Zhu Sheng-Long  , Zhang Ke  ,   (1)College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034, China; (2)State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Published: December 2020

A first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the dehydrogenation properties and the influence mechanism of Li4BN3H10 hydrogen storage materials. The binding energy, the density of states and the Mulliken overlap population are calculated. The results show that the binding energy of crystal has no direct correlation with the dehydrogenation ability of (LiM)4BN3H10(M=Ni,Ti,Al,Mg). The width of band gap and the energy level of impurity are key factors to affect the dehydrogenation properties of (LiM)4BN3H10 hydrogen storage materials: the wider the energy gap is, the more strongly the electron is bound to the bond, the more difficultly the bond breaks, and the higher wile the dehydrogenation temperature be. Alloying introduces the impurity energy level in band gap, which leads the Fermi level to enter into the conduction band and the bond to be weakened, thereby resulting in the improvement of the dehydrogenation properties of Li4BN3H10. It is found from the charge population analysis that the bond strengths of N—H and B—H are weakened by alloying, which improves the dehydrogenation properties of Li4BN3H10.
First-principles calculations of magnetism of Fe atomic sheet
Authors: Gao Tan-Hua  , Lu Dao-Ming  , Wu Shun-Qing  , Zhu Zi-Zhong  ,   (1)Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China; (2)Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China;Department of Physics, Xiamen University, Xiamen 361005, China; (3)Department of Physics, Xiamen University, Xiamen 361005, China
Published: December 2020

The electronic and the magnetic properties of Fe single-layered atomic shees separately with two-dimensional square and hexagonal structures are calculated by the first-principles method based on the spin-polarized density functional theory. The calculations show that planar square and hexagonal as well as the bcc structures manifest their magnetisms at their equilibrium lattice constants. The magnetic moments for these structures are 2.65, 2.54 and 2.20μВ, respectively. The calculated magnetic properties for the elongated and the compressed bond lengths suggest that when the bond is stretched to a length larger than 4.40, the bond should be broken and the magnetic moments of the systems reach the magnetic moment of an independent Fe atom, 4μВ. When the bond lengths are reduced, the magnetic moments of all the systems studied decrease correspondingly. At the critical bond lengths (1.80 for planar square lattice, and 1.75 for hexagonal lattice), the magnetisms of the two planar lattices disappear. Using the Stoner theory, the change from magnetism to non-magnetism for the lattice compression is elucidated.
Thermal-management of grad-doping Yb ∶YAG repetitive-rate laser
Authors: Yan Xiong-Wei  , Yu Hai-Wu  , Zheng Jian-Gang  , Li Ming-Zhong  , Jiang Xin-Ying  , Duan Wen-Tao  , Cao Ding-Xiang  , Wang Ming-Zhe  , Shang Xiao-Tong  , Zhang Yong-Liang  ,   Research Center of Laser Fusion of China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

To improve thermal capability of repetitive-rate laser,in this paper bonded Yb ∶YAG slices are chosen as gain medium, the doping-concentration in gain medium in chosen to be distributed in gradient manner. The distributions of stored energy, temperature and stress are obtained by calculating pumping process inside gain medium. From among the obtained results optimal parameters are chosen for an optimized design. The calculation indicate that using grad-doping medium can reduce temperature, deform, stress and wave aberration. In this paper, the feasibility of improving thermal-management by using grad-doping medium is demonstrated theoretically.
Ba3Tb(BO3)3 ∶Ce3+ : a green emitting phosphor for white LED
Authors: Li Pan-Lai  , Wang Zhi-Jun  , Yang Zhi-Ping  , Guo Qing-Lin  ,   College of Physics Science & Technology, Hebei University, Baoding 071002, China
Published: December 2020

Two green emitting phosphors, Ba3Tb(BO3)3 and Ba3Tb(BO3)3 ∶Ce3+, are synthesized by the high temperature solid-state method, and their luminescent characteristics are investigated. Ba3Tb(BO3)3 phosphor shows several emission peaks located at 439, 493, 547, 589 and 629 nm separately. The emission peaks correspond to the 5D3→7F4 and 5D4→7FJ=6. 5, 4, 3 transitions of Tb3+, respectively, and the maximal peak is 547 nm. For the 547 nm emission, the excitation spectrum consists of several bands, and the maximal peak is located at 380 nm. The Ce3+-activated Ba3Tb(BO3)3 phosphor is studied, and the result shows that the emission spectrum distribution of Ba3Tb(BO3)3 ∶Ce3+ is the same as that of Ba3Tb(BO3)3 phosphor, however, its emission intensity is higher than that of Ba3Tb(BO3)3,which is attributed to the sensitizing action of Ce3+ on Tb3+ in Ba3Tb(BO3)3. For the 547 nm emission, the excitation spectrum of Ba3Tb(BO3)3 ∶Ce3+presents a broad band, differing from that of Ba3Tb(BO3)3 phosphor. The effect of H3BO3 on the emission intensity of Ba3Tb(BO3)3 ∶Ce3+ phosphor is investigated, and the results show that the emission intensity can reach a maximum for 15 wt% excessive H3BO3. All the results show that Ba3Tb(BO3)3 ∶Ce3+ is a green emitting phosphor for white LED.
Optical properties of gold nanoring structures
Authors: Wang Hong-Yan  , Zhang Zhi-Dong  , Zhang Zhong-Yue  , Sun Zhong-Hua  ,   (1)School of Physical Science and Technology,Southwest Jiaotong University,Chengdu 610031,China; (2)School of Physical Science and Technology,Southwest University,Chongqing 400715, China
Published: December 2020

The extinction spectrum and the electric field distribution of gold nanoring structure have been calculated and compared with those of gold nanoplate structure by using the discrete dipole approximation method. It is found that the plasmon resonance peaks can have a red-shift or blue-shift when the radius size and the shape of the nanoring change. The gold nanoring with square cross section has a largest extinction coefficient.At the main plasmon peak,the nanoring with circlar cross section has much stronger electric field and larger electric field distribution,which can serves as the surface enhanced Raman scattering substrate for biological and chemical detections.
Analysis of multiple resonant operating points and their autonomous oscillation stabilities in inductive power transfer systems
Authors: Sun Yue  , Dai Xin  , Wang Zhi-Hui  , Su Yu-Gang  , Hu Ai-Guo  , Tang Chun-Sen  ,   (1)College of Automation, Chongqing University, Chongqing 400044, China; (2)School of Engineering, The University of Auckland, Auckland 1010, New Zealand
Published: December 2020

In this paper we determine multiple resonant operating points (ROPs) of inductive power transfer (IPT) systems and perform the corresponding stability analysis of a series-tuned IPT system, which is taken for example, through using nonlinear dynamics theories. The stroboscopic mapping model of the system is built and a piecewise analytical function of the steady-state response is derived with the fixed-point theory. Then a criterion for assessing the system ROPs is given mathematically. The stability analysis of ROPs is achieved according to the locations of the eigenvalues of the Jacobi matrix of the Poincare mapping model of the system. A case study of the phenomenon of multiple ROPs is conducted, and both simulation and experimental results verify the theoretical results of the proposed method. Furthermore, the proposed method can provide useful theoretical reference for modeling and steady-state analysing other similar resonant converters.
Design and experiment of a Kα-band TE01 modefundmetal wave gyroklystron amplifier
Authors: Xu Yong  , Luo Yong  , Xiong Cai-Dong  , Li Hong-Fu  , Deng Xue  , Pu You-Lei  , Wang Hui  , Wang Jian-Xun  , Yan Ran  ,   School of Physical Electronics,University of Electronic Science and Technology of China,Chengdu 610054,China
Published: December 2020

Based on the analyses and the calculations of the gyroklystron amplifiers self-consistent nonlinear theory, a scheme of Kα-band, TE01 mode, four-cavity fundmetal wave gyroklystron is designed.At the same time, a gyroklystron amplifier is made and tested. The hot test experiment shows that the gyroklystron amplifier can produce 245 kW peak output power, and 3 kW average power at a 35% efficiency and saturated gain of 36.1 dB at central frequency 34 GHz, when using 60 W driving power, and a 70 kV, 10 A annular electron beam in a magnetic field of 1.31 T. The full width half maximum (FWHM) bandwidth is higher than 280 MHz. The amplifier is zero-drive stable. Experimental results are found to be in excellent agreement with theoretical predictions.