bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the effect of active layer thickness on polymer solar cell performance based on optical and opto-electronic model
Authors: Li Guo-Long  , Huang Zhuo-Yin  , Li Kan  , Zhen Hong-Yu  , Shen Wei-Dong  , Liu Xu  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

Polymer solar cell with excellent performance is currently composed of the blend bulk-heterojunction formed by conjugated polymer as donor material and fullerene as acceptor material, among which P3HT and PCBM are most widely used. For the photoelectric thin film device, the optical and the electric characteristics of the active layer can affect the device performance directly. The optical constants of the active layer are obtained primarily based on the Forouhi-Bloomer model. According to the Fresnel coefficient matrix, the numbers of photons absorbed by different active layer thick devices are investigated by calculating electromagnetic field distributions inside this structure. To make a specific analysis of the thickness effect on dissociation probability of bound pairs without external excitation, the model of Onsager-Braun is adopted. Theoretical analysis shows that the active layer with a thickness of 100 nm can maximize photon absorption by the device without reducing the dissociation probability of excitons obviously. As a result, an optimal thickness of the active layer is about 100 nm, which is confirmed by the theoretical and the experimental results from the device with the structure of ITO/PEDOT/ P3HT:PC60BM /LiF/Al.
Experimental study of the effects on signal noise ratio and dynamic range caused by analog gain for CCD
Authors: Wang De-Jiang  , Kuang Hai-Peng  ,   (1)Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,China; (2)Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,China;Graduate School of the Chinese Academy of Sciences,Beijing 100049,China
Published: December 2020

Charge coupled device (CCD) is a key component in a remote sensing system. In order to obtain high signal-to-noise ratio (SNR) and dynamic range in low illumination and quantization circumstance, first, according to CCD architecture and noise physical characteristics, relationship between analog gain quantization step and CCD SNR is proposed; next, integrating sphere calibration system is established, shot noise, photo response nonuniformity and noise floor model are also built, and the next relationship between analog gain and SNR in low illumination condition is analyzed thoroughly; finally, the practical photographing system is built, and remote images in different gain parameters are acquired. Theoretical analysis, experimental calibration, and practical images all indicate that when analog gain is increased by one to two times, the SNR is improved greatly and dynamic range is acceptable.
Field emission phenomena of hydro-thermally grown ZnO nanoinjectors
Authors: Wang Ma-Hua  , Zhu Han-Qing  , Zhu Guang-Ping  ,   (1)Advanced Photonics Center, Southeast University, Nanjing 210096, China; (2)Faculty of Electronic and Electrical Engineering, Huaiyin Institute of Technology, Huaian 223002,China; (3)Faculty of Electronic and Electrical Engineering, Huaiyin Institute of Technology, Huaian 223002,China;Advanced Photonics Center, Southeast University, Nanjing 210096, China
Published: December 2020

Injector-like nanostructure samples of ZnO, which are synthesized by hydrothermal method, are experimentally investigated for the field emission (FE) properties, especially the current density varying with the intensity of the applied electric field; and the fascinating two-stage behavior of electric field enhancement factor (β) is observed. The good performance and the two-stage behavior of the β are explained based on the combination of the intensive electric field effect in semiconductor and its influence on the Fermi energy level with the effective series connection circuit of FE detection systems. Finally, the previous analysis conclusion is well experimentally demonstrated by the FE properties and PL spectra of Znic oxide nanostrucutres fabricated by electrochemically deposition and vapor phase transmitting methods, separately.
Low temperature aging effect on structure, martensitic transformation and magnetic properties in ferromagnetic shape memory alloy of Mn2 NiGa
Authors: Song Rui-Ning  , Li Xiang  , Zhu Wei  , Liu En-Ke  , Li Gui-Jiang  , Cai Jin-Fang  , Wang Wen-Hong  , Wu Guang-Heng  ,   School of Material Sciences & Engineering, Beijing Institute of Technology, Beijing 100081, China;,   School of Science, Beijing Institute of Technology, Beijing 100081, China;,   State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;School of Material Sciences & Engineering, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The structure, the martensitic transformation and the magnetic properties of ferromagnetic shape memory alloy Mn2NiGa aged at low temperature are investigated. The lattice distortion and the internal stress are generated in the samples due to the fine precipitation generated during the aging treatment. When the precipitation concentration exceeds the tolerance limit of the parent phase lattice, it causes the martensitic transformation temperature to increase obviously, and thus the parent phase transforms to martensitic phase with a large coercivity up to 900 Oe. Because of the existence of internal stress, the reverse martensitic transformation is shifted toward high temperature up to 485 K. By extrapolating the experimental data, the Curie temperature of martensite is estimated at 530 K. The internal stress disappears and the martensite turns to be of the parent phase due to the coarsening of the precipitation at higher temperature. Two coarsening threshold temperatures are found to be 423 K and 485 K which are the temperature sensitive and the aging time sensitive, respectively.
Band-structure calculations of two-dimesional magnonic crystals with plane-wave expansion method*
Authors: Cao Yong-Jun  , Yun Guo-Hong  , Narsu  ,   (1)College of Physical Science and Technology, Inner Mongolia University, Huhhot 010020, China;Inner Mongolia Key Laboratory of Physics and Chemistry of Functional Materials and College of Physics and Electronic Information, Inner Mongolia Normal University,; (2)Inner Mongolia Key Laboratory of Physics and Chemistry of Functional Materials and College of Physics and Electronic Information, Inner Mongolia Normal University, Huhhot 010022, China
Published: December 2020

Recently, magnonic crystals which are the magnetic counterparts of photonic crystals or phononic crystals are growing into a hot area of research. In this paper, a plane-wave expansion method in the field of magnonic crystals is proposed. By using this method, band structures of two-dimensional magnonic crystals composed of ferromagnetic materials Fe and EuO are calculated. The numerical results show that the spin-wave gaps will be generated under a definite filling fraction ratio, and the effect of exchange field on the band structure is larger than that of other field in the effective field.
Hydrothermal synthesis, structure characterization and antiferromagnetic properties of thortveitite-type β-Mn2V2O7
Authors: Zhou Chuan-Cang  , Liu Fa-Min  , Ding Peng  , Zhong Wen-Wu  , Cai Lu-Gang  , Zeng Le-Gui  ,   School of Physics and Nuclear energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education),Beijing University of Aeronautics and Astronautics, Beijing 100191, China
Published: December 2020

β-Mn2V2O7 powder is successefully prepared at 200—220℃ under pH=6—9 by a novel hydrothermal synthesis technology. The phase, the morphology and the microstructure of the prepared sample are investigated by XRD, SEM, EDS, TEM, HRTEM and SAED. The results show that β-Mn2V2O7 powder has a thortveitite structure with monoclinic system. The powder synthesized at 200 ℃ under pH=6—7 has a rod morphology, while that at 200 ℃ under pH=8—9 has coexistent petal and rod morphologies. HRTEM and SAED measurements indicate that β-Mn2V2O7 grows anisotropically and has crystalline integrality. Magnetic properties are measured by superconducting quantum interference device (SQUID) in a temperature range of 2—300 K under a magnetic field of 1T. The magnetic measurement results indicate that β-Mn2V2O7 undergoes a transition from antiferromagnetic to paramagnetic with a Néel temperature of 24 K. Above 100K, the inverse susceptibility is fitted well to the Curie-Weiss law and paramagnetic Weiss temperature θ=-24.6 K, and the Curie constant C=9.846 K emu mol-f.u.-1 can be caculated, which means that there exists an obvious antiferromagnetic interaction in thortveitite-type β-Mn2V2O7, the antiferromagnetic behavior is caused by the superchange of Mn2+-O2--Mn2+.
Preparation and dielectric properties of BST films with high tunability
Authors: Yu Jian  , Liao Jia-Xuan  , Jin Long  , Wei Xiong-Bang  , Wang Peng  , Wei Xu-Bo  , Xu Zi-Qiang  ,   Research Institute of Electronic Science and Technology of UESTC, Chengdu 610054, China
Published: December 2020

Six-layer Ba0.6Sr0.4TiO3 (BST) films are prepared by an improved sol-gel method. The effects of various preheating methods on morphology and dielectric properties are studied. XRD results reveal that all BST films preferentially grow along the (110) direction and have cubic perovskite structures, and that preheating can obviously enhance crystallization. XPS results show that the preheating can also decrease surface non-perovskite structure and cause perovskite structure to increase markedly. AFM results display that as the preheating number increases, BST films show significant improvement on morphology with surface roughness reducing. The dielectric property measurement exhibits that tunability is remarkably increased with the increase of preheating number. BST film with all layers preheated shows that its tunability exceeds 55% at 20V bias voltage, while BST film with odd number layers preheated presents a moderate capacitance, lower dielectric loss, approximately 50% tunability at 20V bias voltage and significant increase in figure of merit (FOM) with the bias voltage. The excellent combination of dielectric properties can satisfy the application demand of microwave tunable devices. Also, the relevant mechanism of high tunability is discussed.
Manipulation of coherent Raman scattering process in CS2 byusing chirpped circularly polarized femtosecond pulses
Authors: Deng Li  ,   State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
Published: December 2020

The coherent anti-Stokes Raman scattering (CARS) and coherent Stokes Raman scattering (CSRS) signals of vibration mode at 397cm-1 of CS2 liquid are manipulated by using two chirped circularly polarized femtosecond pulses in non-collinear excitation geometry. Along the phase matching direction intensity distributions, polarizations and wavelengths of CARS and CSRS signals vary regularly as the polarizations of the laser beams are changed. The intensity distributions of CARS and CSRS reflect the scattering cross sections of the stimulated raman scattering of the sample under different circularly polarizations. The polarizations of CARS and CSRS follow the conservation law of the angular momentum of the excitations. The frequency shifts of CARS and CSRS demonstrate the transitions between the rotational energy levels of CS2. The above information is helpful for understanding the mechanism and the behaviors of the CARS and CSRS of CS2 as well as other molecules.
Luminescence of Bi-doped CdWO4 single crystals
Authors: Luo Cai-Xiang  , Xia Hai-Ping  , Yu Can  , Xu Jun  ,   (1)Key Laboratory of Photo-electronic Materials,Ningbo University,Ningbo 315211, China; (2)Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050, China
Published: December 2020

The bismuth-doped CdWO4 single crystals are prepared by the Bridgman method. The absorption spectra, emission spectra and X-Ray photoelectron spectroscopy (XPS) of various parts of as-grown Bi: CdWO4 crystal are investigated. The absorption edge of CdWO4 crystal is red-shifted from 345nm to 399nm due to the introdution of Bi into crystal. The four emission peaks at 470, 528, and 1078 and a weak peak at 1504 nm are observed under the excitation of light beams at 311, 373, 808, and 980 nm. From the X-Ray photoelectron spectroscopic measurements of the Bi: CdWO4 single crystals, Bi2O3 (Bi3+) and NaBiO3 (Bi5+) samples, we infer that there coexit Bi3+ and Bi5+ in Bi: CdWO4 crystals. The fluorescence emissions of visible bands at 470 and 528 nm result from both WO6-6 in Bi: CdWO4 and Bi3+ ions doped in the lattice, while the fluorescence emission of the near infrared band at 1078 nm is due to the Bi5+ luminescence. The analysis result of XPS is consistent with the change of the fluorescence intensity: along the growing direction the emission intensity at 1078 nm and the content of Bi5+ ion both decrease gradually, while the intensity at 528 nm and the number of Bi3+ both increase gradually.
Transport mechanism of copper thin film oxidation by isotopic labeling
Authors: Cao Si  , Gong Jia  , Zhong Cheng  , Li Jin  , Jiang Yi-Ming  ,   Department of Materials Science, Fudan University, Shanghai 200433, China
Published: December 2020

In this paper, a new method is proposed to investigate the transport mechanism of copper thin film oxidation in water vapor using H162O/H182O isotopic labeling. Copper thin films are prepared on glass substrates by vacuum deposition. The structure of copper oxide film is analysed by X-ray diffraction (XRD). The distributions of16O and18O in the oxide film are analysed by secondary ion mass spectroscopy (SIMS). The results demonstrate that the transport mechanism of copper film oxidation is short-circuit diffusion mechanism.
Formation and properties of GeOI prepared by cyclic thermal oxidation and annealing processes
Authors: Hu Mei-Jiao  , Li Cheng  , Xu Jian-Fang  , Lai Hong-Kai  , Chen Song-Yan  ,   Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China
Published: December 2020

Si0.82Ge0.18/SOI prepared by epitaxial growth of SiGe layer on SOI wafer in the ultra-high vacuum chemical vapor deposition is used to fabricate the SiGe on insulator (SGOI) substrate (0.24≤xGe≤1) by the cyclic oxidation and annealing processes. The structure and the optical properties of the SGOI with various Ge content are studied by employing HRTEM, Raman spectroscopy, and photoluminescence (PL) spectroscopy. The variations of Ge component and strain in the oxidation process are analyzed. High crystal quality Ge on insulator (GeOI), with a thickness of 11 nm, is obtained with a flat Ge/SiO2 interface. The direct band transition photoluminescence of the GeOI is observed at room temperature. The photoluminescence peak from GeOI is located at 1540 nm, and the PL intensity increases linearly with exciting power increasing. It is indicated that the formed GOI material has a high crystallization quality and is suitable for the applications in Ge optoelectronic and microelectronic devices.
Analytical modelling and calculation of impedance and pulsed magnetic field for rectangular meander coil based on second order potential
Authors: Hao Kuan-Sheng  , Huang Song-Ling  , Zhao Wei  , Wang Shen  ,   State Key Lab of Power Systems,Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Meander coil is an important kind of coil configuration used in eddy current testing and electromagnetic acoustic testing. Owing to lack of analytical calculation formulas of impedance and magnetic field for meander coil, the analytical modeling is performed and a method of calculating pulsed response is presented. In terms of the general model for eddy current testing and electromagnetic acoustic testing, the calculation of impedance and pulsed magnetic field is transformed into the superposition of impedance and pulsed magnetic field of single rectangular coils. Based on the second order vector potential and the time harmonic magnetic field equations, the scalar potential analytical expressions of the meander coil are derived. Then the analytical expressions of magnetic flux in all solution area and eddy current in the specimen are obtained. By calculating the induction electric potential and the impedance change, the impedance analytical expression of the rectangular meander coil is derived. An FFT-IFFT method is used to calculate the time domain response to pulsed magnetic field. A model with an 8-meander double-layer double-bundle coil above an aluminium plate is used in calculation, and the results are in good agreement with the experimental result and the TSFEM calculation result, which verifies the analytical model and the accuracy of the calculation method. The analytical calculation largely shortens the calculation time compared with that by TSFEM method.
Effects of Ni-assisted annealing on p-type contact resistivity of GaN-based LED films grown on Si(111) substrates
Authors: Wang Guang-Xu  , Tao Xi-Xia  , Xiong Chuan-Bing  , Liu Jun-Lin  , Feng Fei-Fei  , Zhang Meng  , Jiang Feng-Yi  ,   (1)Education Ministry Engineering Research Center for Luminescence Materials and Devices, Nanchang University, Nanchang 330047, China; (2)Education Ministry Engineering Research Center for Luminescence Materials and Devices, Nanchang University, Nanchang 330047, China;Latticepower (Jiangxi) Corporation, Nanchang 330029, China
Published: December 2020

Different thick Ni layers are deposited on the GaN-based LED films grown on Si(111) substrates, then LED films are annealed at 400℃—750 ℃ in the atmosphere of N2 ∶O2=4 ∶1. The Pt / p-GaN contact layer is prepared after removing the Ni-capping layer. It is found that annealing temperature and thickness of Ni-capping layer each have an important influence on the p-type contact of GaN-based LED film. The Ni film can significantly reduce the activation temperature of Mg acceptor of the p-type GaN. The characteristic of p-type contact of Ni-capping sample becomes better first then turns worse with annealing temperature and it become better then turns worse and then better with Ni-capping thickness. After optimization, the specific contact resistivity of Pt/p-GaN in the case of no second annealing can reach 6.1×10-5 Ω·cm2, when Ni-capping layer thickness is 1.5 nm and its annealing temperatune is 450 ℃.
Theoretical study of the effect of changes in the number of quantum wells of dual-wavelength LED
Authors: Zhang Yun-Yan  , Fan Guan-Han  ,   Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou 510631,Chian
Published: December 2020

A two-dimensional simulation of electrical and optical characteristics of the dual-wavelength LED with different numbers of quantum wells is conducted with APSYS software. The results show that the increase of the number of quantum wells will cause uneven distribution of hole concentrations. Therefore, the increase in the number of quantum wells cannot effectively enhance carrier recombination rate, internal quantum efficiency and luminous intensity. Furthermore, it will lead to the rising of threshold voltage and affect the energy conversion efficiency.
Multiscale base-scale entropy analysis of heart rate variability signal
Authors: Yan Bi-Ge  , Zhao Ting-Ting  ,   College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062 China
Published: December 2020

Multiscale base-scale entropy is introduced in this paper.We use it to analyze heart rate variability series.The results show that multiscale base-scale entropy can identify patterns generated from healthy and pathologic states, and can distinguish daytime and nighttime heartbeat time series. We also calculate the multiscale base-scale entropy of surrogate signal (phase randomized data), compare it with the entropy of atrial fibrillation signal, and find that the tends of two entropys are similar to each other, which indicates that atrial fibrillation reflects the linear characteristics of physiological signals. Multiscale base-scale entropy method has potential applications to studying a wide variety of other physiologic and physical time series data.
Empirical analysis of interpersonal interacting behavior in virtual community
Authors: Si Xia-Meng  , Liu Yun  ,   School of Electronic and Information Engineering, Beijing Jiaotong University, Key Laboratory of Communication and Information Systems (Beijing Jiaotong University), Beijing Municipal Commission of Education, Beijing 100044, China
Published: December 2020

Internet forum is the place where online mass incidents usually happen, and is very important in information diffusion and opinion spreading. We empirically analyze the interacting behavior of internet forum users, construct the virtual community network based on implicit interaction behavior. Through inspecting the statistical properties, we find that this virtual community network is directional, asymmetric and disassortative scale free network, and it has hierarchy and community structure.Moreover, user page view is positively correlated with his in-degree, so both can describe the influence power and popularity. From quantitative view, the results show that the effects of influential user with 'contribute-driven' property on information spreading can not be ignored; the success of internet forum needs to increase the activity of the most inert users; if user wants to be authoritative in virtual community networks, he needs to propose interesting message or has a personal brand.
Some new integrable nonlinear dispersive equations and their solitary wave solutions
Authors: Yin Jiu-Li  , Fan Yu-Qin  , Zhang Juan  , Tian Li-Xin  ,   Faculty of Science, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

Under different system parameters, some new integrable models of the generalized modified Dullin-Gottwald-Holm are obtained by Painlev analysis. Using the auto-Backlund transformation, solitary wave solutions of these integrable models are obtained.
Asymptotic solution to the delay sea-sir oscillator for El Nio/La Nia-southern oscillation mechnism
Authors: Mo Jia-Qi  , Lin Wan-Tao  , Lin Yi-Hua  ,   College of Mathematics and Computer Science, Anhui Normal University, Wuhu 241003, China;,   State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

A class of coupled system of the El Nio/La Nia-southern oscillation mechanism is studied. Using the asymptotic analytic perturbation method and the simple and valid technique, the asymptotic expansions of solution to the El Nio/La Nia-southern oscillation model are obtained and the asymptotic behavior of solution to the corresponding problem is considered.
Error correction and decoding for quantum stabilizer codes
Authors: Xiao Fang-Ying  , Chen Han-Wu  ,   School of Computer Science and Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Computer Network and Information Integration of Ministry of Education, Southeast University, Nanjing 211189, China
Published: December 2020

Mapping the error syndromes to error operators is the core of quantum decoding network and the key step to realize quantum error correction. The definitions of the bit flip error syndrome matrix and the phase flip error syndrome matrix are presented, and then the error syndromes of Pauli errors are expressed in terms of the columns of the bit flip error syndrome matrix and the phase flip error syndrome matrix. It is also shown that the error syndrome matrix of a stabilizer code is determined by its check matrix, which is similar to the relationship between the classical error and the parity check matrix of classical codes. So, the techniques of error detection and error correction for classical linear codes can be applied to quantum stabilizer codes after some modifications. The error correction circuits are constructed based on the relationship between the error operator and error syndrom. The decoding circuit is constructed by reversing the encoding circuit because the encoding operators are unitary.
Generalized variational principles for Boussinesq equation systems
Authors: Cao Xiao-Qun  , Song Jun-Qiang  , Zhang Wei-Min  , Zhu Xiao-Qian  , Zhao Jun  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The semi-inverse method is proposed by He to establish the generalized variational principles for physical problems, which can eliminate variational crisis brought by the Lagrange multiplier method. Via the He s semi-inverse method, a family of variational principles is constructed for the Boussinesq equation systems and variant Boussinesq equation systems of fluid dynamics. The obtained variational principles have also proved to be correct.
Thermodynamic properties of a weakly interacting Fermi gas in a strong magnetic field
Authors: Men Fu-Dian  , Wang Bing-Fu  , He Xiao-Gang  , Wei Qun-Mei  ,   College of Physics Science and Technology, China University of Petroleum (East China), Dongying 257061, China;,   Department of Physics, Binzhou University, Binzhou 256600, China
Published: December 2020

Based on the pseudopotential method and the local-density approximation, the thermodynamic properties of a weakly interacting Fermi gas in a strong magnetic filed are studied, the integrated analytical expressions of thermodynamic quantities of the system are derived, and the effects of magnetic field as well as interparticle interactions on the thermodynamic properties of the system are analyzed. It is shown that at both high and low temperatures, magnetic field may adjust the effects of interacting. At low temperatures, magnetic field can lower the chemical potential, total energy and heat capacity of the system compared with the situation of Fermi gas in the absence of the magnetic field. The repulsive interactions may increase the chemical potential, but reduce the total energy and heat capacity of the system compared with the situation of non-interacting Fermi gas. At high temperatures, magnetic field as well as repulsive interactions can reduce the total energy and increase heat capacity of the system, moreover, strong magnetic field may change the effects of interaction on the total energy and the heat capacity of the system.
The stochastic energetics resonance of bistable systems and efficiency of doing work
Authors: Lin Min  , Zhang Mei-Li  , Huang Yong-Mei  ,   College of Metrology Technology and Engineering, China Jiliang University, Hangzhou 310018, China
Published: December 2020

The interaction of work and heat between Brownian particles in a bistable system, the external periodic force and the thermal stochastic force are analyzed. The stochastic energy balance equation based on Langevin equation is established. For the Langevin equation subjected to periodic force, stochastic force and damping force, the method of combining dynamics and non-equilibrium thermodynamics is used. From force as the foothold changed into energy as the research core, the exchange of energy between system and environment and the efficiency of doing work are deeply analyzed with this method when the Brownian particle motion is along single trajectories, which reveals that the bistable system exhibits stochastic energetic resonance phenomenon.
A novel large-orbit electron gun with gradually-changing reversal magnetic field
Authors: Wu Xin-Hui  , Li Jia-Yin  , Zhao Xiao-Yun  , Li Tian-Ming  , Hu Biao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

A novel approach to achieve a large-orbit electron beam is demonstrated using a gradually-changing reversal magnetic field. On the basis of analyzing the general regularities of electron movement and various factors which lead to eccentricity and velocity spread in the gradually-changing reversal magnetic field, we design a large-orbit electron gun. Different from the traditional three-step method, our design does not pursuit the formation of thin tubular electron beam and the utilization of mutation reversal magnetic field, which reduces the difficulties in structure complexity and tube-making process. In addition, the cathode emission band can be placed in the axial magnetic field before the magnetic reversal point where its magnitude decreases gradually, by controlling the angular momentum difference between every trajectory starting points and using the offset effect of various unfavorable factors to reduce eccentricity and velocity spread. The simulation results are consistent with the theoretical analyses, which shows that the beam quality can be improved remarkably by fine-tuning electromagnetic fields, confirms that the efficiency and the applicability of the adjusting method we proposed, and provides a new technical way to obtain a high-quality large-orbit electron beam for high-efficiency large-orbit millimeter-wave devices.
Outgassing mass spectrum analysis with intense pulsed emission of carbon nanotube cathode
Authors: Shen Yi  , Zhang Huang  , Liu Xing-Guang  , Xia Lian-Sheng  , Yang An-Min  ,   Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The outgassing mass spectrum property with intense pulsed emission of the carbon nanotube(CNT) cathode is investigated on a 2 MeV linear induction accelerator injector by using the quadrupole mass spectrometer. The results show that the cathode has a capability of desorbing gases from the CNT cathode under pulsed high voltage. There are significant CO2, N2(CO) and H2 desorbing gases which play an important role in the formation of the cathode plasma. The mechanism of electron emission of CNT cathode is plasma-induced field emission, rather than explosive field emission, which is proved by analyzing the desorbed gases component.
Research of Kramers-Krnig relationship for reconstruction of ultrashort electron longitudinal bunch profile by means of frequency domain measurements
Authors: Wu Dai  , Liu Wen-Xin  , Tang Chuan-Xiang  , Li Ming  ,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China;,   Key Laboratory of Particle and Radiation Imaging of Ministry of Education, Tsinghua University, Beijing 100084, China;,   Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Kramers-Krnig (K-K) relationship is widely used in diagnostics of longitudinal bunch distribution with frequency domain measurement, and it has been used as a powerful tool in analysis of bunch profile and length. The study results show that the bunching beam parameters are severely affected by the choosing of the baseline of autocorrelation curve, power loss at low frequency and cutoff at high frequency, as well as extrapolation point, etc. As an example, the longitudinal bunching length is measured by means of coherent transition radiation in accelerator laboratory of Tsinghua University. We analyze the influence of the choice of parameters on measured experiment results and discuss the method of choosing the key parameters for the K-K transform.
Theoretical study of electronic structure and optical properties of OsnN0,(n=1 6) clusters
Authors: Zhang Xiu-Rong  , Wu Li-Qing  , Rao Qian  ,   School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China;,   School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
Published: December 2020

The possible geometrical and electronic structures of (OsnN)0,(n=16) clusters are optimized by using the density functional theory (B3LYP) at the LANL2DZ level. For the ground state structures of (OsnN)0,(n=16) clusters, The magnetic properties, the natural bond orbit (NBO), the spectrum and the aromatic characteristics are analyzed. The calculated results show that the magnetic moment of OsnN- cluster is quenched at n=1 and 5. Reversed ferromagnetic coupling between Os atom and N atom takes place in Os2N and Os4N0, clusters. The NBO charge distribution of clusters depends on the relative position of the atom, for example, the charge transfer happening to N atoms in the endpoint is more obvious than that happening to the N atoms in the middle. There are obvious vibration peaks in IR and Raman spectra of (OsnN)0,(n=16) clusters. The aromaticity of Os5N- cluster is the strongest.
Influence of longitudinal radio frequency electric field on multipactor effect on a dielectric surface
Authors: Zhu Fang  , Zhang Zhao-Chuan  , Dai Shun  , Luo Ji-Run  ,   Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on the multipactor dynamic model and the secondary electron emission yield curves, the multipactor phenomenon of the secondary electron emission subjected to the longitudinal radio frequency (RF) electric field existing on a dielectric surface is simulated using the Monte Carlo method. The susceptibility curve of the electric field on the surface and the temporal evolution image of the multipactor discharge are investigated. The power deposited on the dielectric surface by the multipactor is also obtained in terms of an S-band RF dielectric window. The results show that the longitudinal RF electric field may intensify the single-surface multipactor effect, which is likely to result in dielectric crack and detrimental to RF transmission.
Magnetic metamaterial based on connected split and closed rings
Authors: Chen Chun-Hui  , Qu Shao-Bo  , Wang Jia-Fu  , Ma Hua  , Xu Zhuo  , He Hua  ,   College of Science, Air Force Engineering University, Xi'an 710051, China;,   Key Laboratory of Electronics Ceramics and Devices of Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Through connecting split and closed rings together, a three-dimensional magnetic metamaterial is proposed in this paper. When the electric field of the induced electromagnetic wave is perpendicular to the dielectric board, this construction exhibits negative effective permeability. Its magnetic resonant frequency is insensitive to the variation of the width of the metallic wires, which facilitates practical fabrications and applications. Meanwhile this construction is of significance for designing polarization-independent and isotropic magnetic and left-handed metamaterials.
Diffraction characteristic of a misaligned vortex beam through a phase-hologram grating
Authors: Li Fang  , Jiang Yue-Song  , Ou Jun  , Tang Hua  ,   School of Electronic and Information Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
Published: December 2020

We study the analytical features of the output beam diffracted from a phase-hologram grating when the incident vortex beam is misaligned with respect to the grating. The analytical representation describing the diffracted beam of the 1st order is derived theoretically. Based on the representation, the central of gravity and the central intensity of the diffracted beam are investigated in the cases of the alignment, lateral displacement, angular tilt and simultaneous lateral misalignment and angular tilt, separately. It is shown that the diffracted beam is described through confluent hypergeometrical function. The misalignment of the incident vortex beam can give rise to the displacement of the beam center of gravity, which is independent of the misalignment direction and azimuth angle. The displacement is more obvious for the lager misalignment. In the case of angular tilt, the direction of beam center of gravity is nearly identical to the misalignment direction, whatever the topological charge of the incident beam and the fork number of the grating are. Besides, if the sum of the topological charge of the incident beam and the fork number of the grating is zero, with radial displacement and deflection angule increasing, the central intensity of the diffracted beam decreases gradually, otherwise, the central intensity is non-zero value any more. That means the misalignment between the phase-hologram grating and the incident vortex beam can influence the measurement of the topological charge of the vortex beam.
Phase noise detection method in fiber lasers based onphase modulation and demodulation
Authors: Wang Xiao-Lin  , Zhou Pu  , Ma Yan-Xing  , Ma Hao-Tong  , Li Xiao  , Xu Xiao-Jun  , Zhao Yi-Jun  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In coherent combination of active phase control, there have existed three main phase detection techniques until now, they are heterodyne phase detection technique, multi-dithering technique and stochastic parallel gradient descent algorithm. A new phase detection method based on phase modulation and demodulation is proposed according to the principle of heterodyne phase detection and multi-dithering technique. Periodic phase modulation signal is implemented on a reference laser, and the coherent detection is carried on between the reference laser and the signal laser. With some processing of the modulation signal and the coherent detected optoelectronic signal, the phase noise is detected and the noise compensation can be realized. Numerical simulation and experimental studies are conducated. Experimental results show that the phase detection accuracy is higher than 1/50 wavelength and the average phase compensation residual error is less than 1/50 wavelength in the case of a 2 kHz sine wave phase noise with a phase region of
Analysis and correction of object wavefront reconstruction errorsin two-step phase-shifting interferometry
Authors: Xu Xian-Feng  , Han Li-Li  , Yuan Hong-Guang  ,   College of Physics Science and Technology, China University of Petroleum (East China), Dongying 257061, China
Published: December 2020

The method of calculating and correcting object wave reconstruction errors caused by phase shift errors in two-step phase-shifting interferometry is studied systematically. Based on the principle of random distribution and the amplitude-phase independence of diffractive object wave, the expression of objective wave reconstruction error is introduced and the formula for that in the two-step standard algorithm is deduced. The automatic error correction method is suggested by further analyzing the structures, the characters of those errors caused by phase shift errors, and the objective expression. By the proposed method, the reconstructive amplitude and phase errors can be corrected at the same time through simple operation on the objective complex amplitude reconstructed by the standard two-step method without the additional measurement or the acknowledge of phase shift. The computer simulations are carried out to verify the effectiveness of this method, and the results show that the method is robust and reduces the effect of phase shift error on object wave-front reconstruction by about 2 orders of magnitude. Optical experiments also indicate that this method is effective and efficient.
Enhancing stimulated Raman scattering of benzene high-order Stokes lines by fluorescence of 4-sulfphenyl porphyin in liquid-core optical fiber
Authors: Li Zhan-Long  , Lu Guo-Hui  , Sun Cheng-Lin  , Men Zhi-Wei  , Li Zuo-Wei  , Gao Shu-Qin  ,   State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China;,   College of Physics, Jilin University, Changchun 130012, China
Published: December 2020

Stimulated Raman scattering of benzene is studied in liquid-core fiber. Owing to fluorescence and third-order nonlinear 4-sulfphenyl porphyin, the high-order stimulated Raman scattering, such as sixth-order Stokes line of benzene, can be observed at a relatively low input-laser power. The threshold of high Stokes line is lowered with the addition of the 4-sulfphenyl porphyin when the concentration of solution is within 10-6 and 10-9 mol/L. At the same time, the Stokes line width becomes narrow with Stokes line order increasing. These results are expected to be applied to tunable laser, seeding laser, biological molecular structures and biological molecule used in none biological area.
Influence of nonlocalization degree on the interaction between spatial dark solitons
Authors: Gao Xing-Hui  , Yang Zhen-Jun  , Zhou Luo-Hong  , Zheng Yi-Zhou  , Lu Da-Quan  , Hu Wei  ,   Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631, China;,   Institute of Mechanical and Electrical Engineering, Guangzhou University, Guangzhou 510006, China
Published: December 2020

The interaction between dark solitons in nonlocal self-defocusing media is investigated. Numerical results show that there is a critical condition for interaction between dark solitons in nonlocal self-defocusing medium. Under the critical condition, dark solitons will neither attract nor repell each other because the attractive force and repulsive force between them are identical. Beyound the critical condition, dark solitons may attract or repell each other depending on the nonlocalization degree and distance between them. The value of the critical condition is found.
Mutual-induced fractional Fourier transform in strongly nonlocal nonlinear medium
Authors: Zhao Bao-Ping  , Yang Zhen-Jun  , Lu Da-Quan  , Hu Wei  ,   Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

The effect of mutual-induced fractional Fourier transform (FRFT) between a weak signal beam and a strong pump beam in a strongly nonlocal nonlinear medium is described. The signal beam is an FRFT during propagation and the order of FRFT is dependent on the propagation distance and the power of the pump beam. When the propagation distance is fixed, the order of FRFT of the signal beam is proportional to the square root of the power of the pump beam. Mutual-induced FRFT is another method of light controlling light, and its properties contribute to the development of new type FRFT devices, optical information processing and optical imaging.
Frequency properties of the defect mode inside a photonic crystal band-gap with zero average refractive index
Authors: Liu Li-Xiang  , Dong Li-Juan  , Liu Yan-Hong  , Yang Chun-Hua  , Yang Cheng-Quan  , Shi Yun-Long  ,   Institute of Solid State Physics, Shanxi Datong University, Datong 037009, China
Published: December 2020

Left-handed metamaterial has been designed based on transmission line technology. A left-handed and a normal materials are studied alternately to form a one-dimensional photonic crystal with an average refractive index of zero but a special band-gap emerges. The two band-edge frequencies of this gap are insensitive to the incident angle and lattice constant. These characteristics can be used in the miniaturization of filters and high-quality coupling. Studies show that we can regulate the mode frequency by controlling the thickness of the defect layer, which can provide a method for the adjusting frequency in applications. The experimental results are consistent with numerical simulation.
Dynamical behaviors of hydrodynamic cavitation bubble under ultrasound field
Authors: Shen Zhuang-Zhi  , Lin Shu-Yu  ,   Institute of Appiled Acoustics, Key Laboratory of Ultrasonics of Shaanxi Province, Shaanxi Normal University, Xi’an 710062, China
Published: December 2020

Considering liquid viscosity, surface tension, liquid compressibility and turbulence, the dynamical behaviors of cavitation bubble in venturi cavitation reactor are numerically investigated with using acoustic field regarding water as a work medium. The effects of acoustic frequency, acoustic pressure and ratio of throat to pipe diameter on cavitation bubble dynamics, bubble temperature and pressure pulse by rapid collapse of cavitation bubble are analysed. The results show that bubble motion of hydrodynamic cavitation modulated by ultrasound, becomes the high energy stable cavitation. It is favorable for enhancing the cavitation effect.
The analysis of effects and theories for electromagnetic hydrodynamics propulsion by surface
Authors: Liu Zong-Kai  , Zhou Ben-Mou  , Liu Hui-Xing  , Liu Zhi-Gang  , Huang Yi-Fei  ,   Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The electromagnetic hydrodynamics(EMHD) propulsion by surface is performed through the reaction of electromagnetic body force, which is induced in conductive flow fluid (such as seawater, plasma and so on) around the propulsion unit. Based on the basic governing equations of electromagnetic field and hydrodynamics, by numerical simulations obtained by the finite volume method, the characteristics of flow field structures near the navigating and the strength variation of propulsion force are investigated at varying positions (the angle of attack). The results show that surface electromagnetic body force can modify the structure and the input energy of flow boundary layer, which enables the navigation to obtain the thrust. With the increase of interaction parameter the effect of viscous resistance and pressure drag to navigating decrease and the nonlinear relationship between propulsion coefficient and interaction parameter tends to be linear gradually. The strength of propulsion force depends mainly on the electromagnetic body force. The lift force can be improved effectively through the EMHD propulsion by surface at an angle of attack for navigating. The navigating surface can be designed as working space of propulsion units, which is of certain significance for optimizing the whole struction and improving the efficiency.
Numerical simulation of multipactor on dielectric surface in high direct current field
Authors: Cai Li-Bing  , Wang Jian-Guo  , Zhu Xiang-Qin  ,   Northwest Institute of Nuclear Technology, Xi'an 710024, China;,   School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The numerical simulation of multipactor in the dielectric surface breakdown in high direct current field is realized by using the particle-in-cell method. And the influence of the strength of the high direct current field, smoothness of the dielectric surface and secondary electron yield coefficient on the multipactor are researched through the simulation of multipactor. Finally, the influence of the tilting of high direct current field and external magnetic field on the multipactor are also investigated. The results show that selecting of the dielectric with low secondary electron yield coefficient and tilting of high direct current field can reduce the degree of multipactor, and for the external magnetic field the degree of multipactor decreases effectively only when the external magnetic field exceeds a certain value.