bluuebunny/crossref_metadata_2025 huggingface dataset:
A new atmospheric RF cold plasma source with microhollow cathode structure
Authors: Qiu Liang  , Meng Yue-Dong  , Ren Zhao-Xing  , Zhong Shao-Feng  ,   中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

The configuration and mechanism of a microhollow cathode discharge (MHCD) is introduced in this paper. The focus is a new type of cold atmospheric large-area plasma source, the fused hollow cathode (FHC) plasma source based on radio frequency hollow cathodes. Through its applications and related research, we present the characteristics of the hollow cathode discharge and the factors on which its characteristics depend, such as the cathode material, gas specy, frequency, gas flow, pressure, inner diameter of cathode, and the like. Two other types of related MHCD systems are given in addition.
Properties of large-area surface wave plasma
Authors: Liu Ming-Hai  , Sugai H  , Hu Xi-Wei  , Ishijima T  , Jiang Zhong-He  , Li Bin  , Dan Min  ,   (1)华中科技大学电气与电子工程学院，武汉  430074; (2)名古屋大学工学部电气研究科，名古屋  4648603
Published: December 2020

Property of rectangular structure surface wave plasma was reported. Large-area uniform and high density plasma was produced by the optimization of slot antenna and the shape of dielectric plates. Plasma density and electron temperature for different operation conditions were measured by a Langmuir probe. Profile of plasma density along the vertical direction was modeled by a diffusive model, and the simulation result can be used to interpret qualitatively the measurement value very well.
Characteristics of dielectric barrier homogenous discharge at atmospheric pressure in nitrogen
Authors: Wang Yan-Hui  , Wang De-Zhen  ,   三束材料改性国家重点实验室，大连理工大学物理系，大连  116023
Published: December 2020

On the basis of one-dimensional fluid model, the characteristics of a homogeneous discharge at atmospheric pressure in nitrogen are numerically investigated. The primary processes of excitation and ionization in N2 are considered. The species included in the model are the electron e，N2 in the ground state，two ions N+2，N+4 and two metastable states N2(a1∑-u)，N2(A3∑+u). The simulation results show that the discharge in N2 appears mostly as a low-pressure Townsend discharge. The amplitude of discharge current is small and the gas voltage changes slowly in the breakdown phase. The electron density is much lower than that of ions and its maximum value occurs at the anode. Electrons are not trapped in the gas gap. There is no quasineutral plasma domain. The densities of metastable states N2(a1∑-u) and N2(A3∑+u) are at least three order higher than that of electron. The maximum metastable densities are located close to the anode, which determines the space structure of N2 discharge. Seed electrons needed in discharge are mainly provided by Penning ionizations between metastable molecules. This regime results in a low ionization level, which makes the discharge in N2 being close to a Townsend discharge. When changing discharge conditions properly, multiple-peak discharge can be obtained in N2.
Calculation on runaway process of high-energy fast electrons under nanosecond-pulse
Authors: Shao Tao  , Sun Guang-Sheng  , Yan Ping  , Gu Chen  , Zhang Shi-Chang  ,   (1)中国科学院电工研究所，北京  100080; (2)中国科学院电工研究所，北京  100080；中国科学院研究生院，北京  100049
Published: December 2020

The runaway breakdown model induced by fast electrons is promising in explaining the nanosecond-pulse breakdown. In this paper, runaway process and collision ionization of fast electrons are discussed. Based on the relations between the electron energy and effective retarding force, the evolution of injected electron energy as a function of distance away from the avalanche head was simulated. The higher applied electric filed strength is, the lower the runaway energy threshold is and the more fast electrons can runaway, and gas pressures affect the runaway process of fast electrons greatly. Moreover, the runaway breakdown process under the high-voltage nanosecond pulse is described qualitatively.
Study of characteristics of coplanar dielectric barrier discharge
Authors: Ouyang Ji-Ting  , He Feng  , Miao Jin-Song  , Feng Shuo  ,   北京理工大学理学院，北京  100081
Published: December 2020

The process of coplanar dielectric barrier discharge (DBD) has been investigated experimentally and theoretically by using a segmented-electrode system. The local discharge current, light emission intensity and the developing velocity of plasma on the cathode were obtained. The results of the experiment and the two-dimension fluid modeling are compared. It was shown that there exists a non-uniform field in plasma region which causes the disagreement between the local discharge and the light emission during the discharge development in coplanar DBD. The secondary electron emission producod by photon bombardment on the dielectric surface should be taken into account in studying DBD.
Crystal growth, color centers and spectra properties of V3+∶YAG grown by TGT
Authors: Su Liang-Bi  , Zhang Dan  , Li Hong-Jun  , Qian Xiao-Bo  , Shen Jiong  , Zhou Guo-Qing  , Xu Jun  ,   中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

A V∶YAG single crystal was grown by the temperature gradient technique (TGT) with graphite heating elements, which exhibited two kinds of colorations of light-green and yellow-brown in different parts. Differences in absorption spectra of three samples with different colors suggest that the reduction effect of carbon diffused from the heating element should enhance the concentration of tetrahedral V3+ ions and induce the F color centers with absorption band peaking at 370nm. The three samples all exhibited light-green color after annealing under vacuum at 1300℃. From changes of their absorption spectra, it can be inferred that tetrahedral V3+ ions should be produced through the exchange of octahedral V3+ and tetrahedral Al3+ ions in neighboring sites under heat exciting. During the process of annealing, the F color centers were thoroughly eliminated and the escaped free electrons could be captured by V ions with higher valance states than +3 to further improve the concentration of tetrahedral V3+ ions.
Anelastic relaxation of excess oxygen in GdBaCo2O5+δ system studied by low -frequency internal friction
Authors: Liu Wei  , Zhang Yan-Min  , Wu Xiu-Sheng  , Zhang Hua-Li  , Chen Chu-Sheng  ,   中国科学技术大学材料科学与工程系先进功能材料和器件实验室,合肥  230026
Published: December 2020

The investigation of GdBaCo2O5+δ system using low frequency internal friction method indicates that there exists a relaxation internal friction peak originated from the jump of excess oxygen atoms. The excess oxygen content δ affects greatly the height, shape and position of the peaks, which reflects the state of the excess oxygen varying with the value of δ. When the excess oxygen content is very small, say for the sample with δ=0.005, the corresponding internal friction peak disappears. On increasing the excess oxygen the relaxation internal friction peak will be observed. Three different states of excess oxygen can be concluded from the relaxation peaks which exist in the samples with δ=0.278,0.407,0.421,0.431 and 0.515. In addition, an internal friction peak with the features of phase transition are also observed in samples with δ=0.421 and 0.515 at about 360K, which may be attributed to metal-insulator transition.
Theoretical study of stabilization effect of the substituted atom and magnetism of intermetallic compounds YFe11Ti
Authors: Gao Guo-Qiang  , Chen Bo  , Huang Zheng  , Zhang Xiu-Lan  , Sun Guang-Ai  , Huang Hua-Shan  , Yu Cong  ,   (1)西南交通大学理学院,成都  610031; (2)中国工程物理研究院核物理与化学研究所,绵阳  621900; (3)中国工程物理研究院核物理与化学研究所,绵阳  621900；西南交通大学理学院,成都  610031
Published: December 2020

Based on the density functional theory (DFT), using full-potential linearized augmented plane wave and improved local orbital (APW+lo) method, the structure and magnetism of the rare-earth permanent magnetic materials YFe11Ti are analyzed and calculated. The formation energy of YFe12，Y2Fe17 and YFe11Ti are calculated, The stabilization effect and the possible positions of the substituted atom Ti are discussed. The magnetic moments for the system and respective atoms are obtained. The calculated result is consistent with the experiment. The contributions of the density of states of the electrons to the magnetism are discussed.
An analytical model of mobility in nano-scaled n-MOSFETs
Authors: Dai Yue-Hua  , Chen Jun-Ning  , Ke Dao-Ming  , Sun Jia-E  , Hu Yuan  ,   安徽大学电子科学与技术学院,合肥  230039
Published: December 2020

In this work, a method for calculating mobility of nano-scaled MOSFETs from the Boltzmann transport equation(BTE) is presented. Some approximations are assumed for the BTE in nano-scaled MOSFETs, and an improved distribution function of the carriers is obtained which is used to model the mobility of carriers. An analytical expression of carrier mobility is deduced considering the statistical distribution of carrier velocity and carrier life-span and taking into account especially the interaction between the longitudinal and the transverse fields. The reasonable agreement of the calculated results with simulation validated the new model, which is explicit, simple and physically well grounded.
Analysis of the spatio-temporal characteristics of precipitation of China based on the power-law exponent
Authors: Zhi Rong  , Gong Zhi-Qiang  , Wang De-Ying  , Feng Guo-Lin  ,   (1)扬州大学物理科学与技术学院，扬州  225009；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (2)扬州大学物理科学与技术学院，扬州  225009；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029; (3)中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029；国家气候中心，中国气象局气候研究开放实验室，北京  100081; (4)中国气象科学研究院，北京  100081
Published: December 2020

The daily precipitation observational data of 740 stations from 1960a to 2000a Which provided by National Climate Center of Chinese Meteorologial Administration, are divided in sections and statistically analyzed. A common feature is revealed——the power-law distribution, and different precipitation corresponds to different power-law exponent; this to a certain extent reflects that different precipitation have different climate backgrounds and control systems. The power-law exponents of the seven climate regions of China show the trend of increase from southeast to northwest, this corresponds to the spatial characteristic of precipitation of China——more in east and less in west, more in south and less in north. The analysis on the characteristic of the temporal evolvement of the power-law exponent shows that the abruption points of the power-law exponent of northeast, east, and northwest of China correspond to the drying trend of northern China starting from 1970s.
Study of X-ray detector system characteristics on the 3B3 medium energy beamline in BSRF
Authors: Yi Rong-Qing  , Yang Guo-Hong  , Cui Yan-Li  , Du Hua-Bing  , Wei Min-Xi  , Dong Jian-Jun  , Zhao Yi-Dong  , Cui Ming-Qi  , Zheng Lei  ,   (1)中国工程物理研究院激光聚变研究中心，绵阳  621900; (2)中国科学院高能物理研究所,北京  100049
Published: December 2020

On the 3B3 medium energy X-ray beamline, a new monochromatic X-ray source tunable in the 2—6 keV energy range bas been constructed and implemented. The characteristic parameters of the X-ray source having been determined, with the help of the light source, we have calibrated the sensitivity of X-ray detector,thickness of filter,diffraction efficiency of crystals and energy response of the BAS5000-RS, which showed the high performance of the monochromator and detecter system.
The classical dissociation of HF molecule by chirped laser pulse
Authors: Chi Yu-Hua  , Liu Xue-Shen  , Ding Pei-Zhu  ,   (1)吉林大学原子与分子物理研究所，长春  130012; (2)中国石油大学(华东)物理科学与技术学院，东营  257061;吉林大学原子与分子物理研究所，长春  130012
Published: December 2020

The classical dissociation of a diatomic molecule by chirped laser pulses is evaluated by means of symplectic algorithm. We discuss the effect of the vibro-rotational energy level transition on the dissociation probability.
Cascade decays and final charge-state distribution of hollow argon ions
Authors: Hu Hong-Wei  , Dong Chen-Zhong  ,   西北师范大学物理与电子工程学院,兰州  730070
Published: December 2020

On the basis of a previous model of radiative-Auger-cascade for calculation of final-charge-state distributions of hollow ions, a new model of radiative-Auger-double Auger-cascade has been constructed by including double Auger process, and was applied to study the final-charge-state distribution in the production of Ar+(1s-1) (argon ion with an initial 1s hole) and Ar+(2s-1) (argon ion with an initial 2s hole). Comparing with the previous calculations and experiments, the present results show excellent agreement.
Applicability of the reaction window theory
Authors: Chen Lan-Fang  , Ma Xin-Wen  , Zhu Xiao-Long  ,   (1)中国科学院近代物理研究所，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000;中国科学院研究生院，北京  100049
Published: December 2020

Based on the molecular Coulombic over barrier model for description of slow ion-atom collisions, the reaction window theory related to projectile velocity is presented briefly. According to the theory, the state-selective differential cross sections of single electron capture in O8+-H, Ar8+-H, Ar8+-He, Ne10+-He and Ar18+-He collisions at different collision velocities are calculated and compared with experimental results. Calculations are also done for single, double, and triple electron capture in 15N7+-Ne collisions at fixed velocity of 0.53　a.u., and are compared with experimental data. It is found that the predictions of the final electronic state distribution of captured electron(s) are in agreement with experimental data, and both theory and experiments show that the widths of the reaction window increase with the projectile velocity. The differential cross sections predicted by the theory are larger for smaller Q-values, vice versa, when compared with experimental data.
Theoretical investigation of optical heterodyne cavity ring down spectroscopy
Authors: Cao Lin  , Wang Chun-Mei  , Chen Yang-Qin  , Yang Xiao-Hua  ,   华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062
Published: December 2020

A simplified optical heterodyne cavity ring down spectroscopy, which is relatively easy to implement and more suitable for molecular ro-vibrational spectrum study, is suggested in the present paper. It avoids measuring the ring down time directly, and in addition cancels the DC common mode signal resulting from the loss of the cavity mirrors. Theoretically, it could reach the quantum noise detection limit. Furthermore, its lineshape of the first derivative of Gaussian profile is theoretically analyzed, and the dependence of the spectral intensity and lineshape on some experimental parameters are also discussed, and thus the optimal parameters are obtained.
The transmittance of Savart polariscope in polarization interference imaging spectrometer
Authors: Peng Zhi-Hong  , Zhang Chun-Min  , Zhao Bao-Chang  , Li Ying-Cai  , Wu Fu-Quan  ,   (1)曲阜师范大学激光研究所，曲阜  273165; (2)西安交通大学理学院，西安  710049; (3)中国科学院西安光机所，西安  710068
Published: December 2020

The Savart polariscope is the key spectroscopic component of the static polarization interference imaging spectrometer (SPIIS) that we have developed. The principle of beam splitting of Savart polariscope is described. This paper mainly studies the reflection and refraction of light incident from one medium to another when incident plane and the principle section of the left plate are coincident or perpendicular, according to electromagnetic boundary conditions. The transmission coefficient of each interface is deduced, and the total transmittance is given as a function of angle and wavelength of the incident light which is analyzed through computer simulation. It is proved in theory and by experiment that the Savart polariscope has the advantages of both high flux and large field of view, and can be used as high performance lateral shearing beam splitter in static interferometer and SPIIS. This will provide the theoretical basis for the development of new polarization interference imaging spectral systems.
Spectral properties of hydrogen-containing organic solution of neodymium chelate
Authors: Ye Yun-Xia  , Yu Ke-Han  , Qian Lie-Jia  , Fan Dian-Yuan  , Peng Bo  ,   (1)复旦大学信息科学与工程学院，上海  200433; (2)中国科学院上海光学精密机械研究所高功率激光物理国家实验室，上海  201800; (3)中国科学院上海光学精密机械研究所高功率激光物理国家实验室，上海  201800;江苏大学机械学院，镇江  212013
Published: December 2020

Tris-thenoyltrifluroacetonate of Nd3+ has been prepared and dissolved in DMF solation with very high concentration, and the contained hydrogen has not been substituted by deuterium. The absorption spectrum, emission spectrum, and fluorescence lifetime of the solution were measured. Very obvious characteristic fluorescence peaks were observed at 898 and 1058 nm. Based on Judd-Ofelt theory, three intensity parameters were obtained: Ω2=4.9×10-20 cm2, Ω4=5.1×10-20 cm2 and Ω6=2.5×10-20 cm2. Line strengths Scal, oscillator strengths fcal, radiative transition probabilities Aed, radiative lifetimes τr and branch ratios β were calculated too. The measured lifetime τ of 1058 nm peak is 460 μs, and that of 898 nm 505 μs. Comparison between theoretically computed radiative lifetime τr (682 μs) and the measured lifetime indicates that the non-radiative transition probability of the solution is very low and the fluorescence quantum efficiency very high. High values of three intensity parameters prove the high asymmetric surroundings of Nd3+, which is important for Nd3+ to absorb the excitation energy. Spectropic quality factor Ω4/Ω6>1 makes radiation at 898 nm stronger than at 1058 nm.
Photon localization in amorphous photonic crystal
Authors: Xu Xing-Sheng  , Chen Hong-Da  , Zhang Dao-Zhong  ,   (1)中国科学院半导体研究所光电子集成国家重点实验室，北京  100083; (2)中国科学院物理研究所，北京  100080
Published: December 2020

The photon localization in disordered two-dimensional photonic crystal is studied by use of multiple-scattering method. The disorder degree can be controlled by adjusting the random rotating angle of the square cell. It is found that the transmission in the band decreases and that in the gap increases as the disorder degree increases, and localization induced by disorder will spread from the band gap edge to the band center and the gap center. Moreover, the mean transmission of the band will decrease exponentially with disorder increasing.
Microwave transmission behavior of the single dissymmetrical hexagonal split-ring resonators
Authors: Yao Yuan  , Zhao Xiao-Peng  , Zhao Jing  , Zhou Xin  ,   (1)清华大学电机工程与应用电子技术系，北京  100084; (2)西北工业大学电流变技术研究所，西安  710072
Published: December 2020

Inspired by the dendritic geometry in nature, we designed the single dissymmetrical hexagonal split ring resonators (SRRs). The SRRs were fabricated on one side of the dielectric substrate using shadow mask/etching technique. By experiments and computer simulations, we have researched the microwave transmission behavior of the SRRs in the frequency band of 7—12 GHz. The results show that, for an individual hexagonal SRR, the resonance frequency is affected by the size of the SRR; for two SRRs, there are two resonance peaks in the transmittion curve when they are close to each other. For three SRRs or the radialized rings, the resonance frequency of the structure with high-level branches shifts towards lower values compared with that with no branches. The simulations are in agreement with the experimental results.
Regulating ability of defects on the negative refraction of left-handed metamaterials
Authors: Zheng Qing  , Zhao Xiao-Peng  , Li Ming-Ming  , Zhao Jing  ,   (1)清华大学电机工程与应用电子技术系，北京  100084; (2)西北工业大学电流变技术研究所，西安  710072
Published: December 2020

We have investigated the defect effect on negative refraction of the left-handed metamaterials (LHMs). The printed circuit boards with LHMs are fabricated using a shadow mask/etching technique. The negative refraction of wedge-shaped LHMs samples with and without defects is investigated respectively. The experimental result shows that when two kinds of point defects are introduced into the sample, the ratio of the maximum power of samples with point defects to that without defects are 1.035 and 1.256, and the absolute value of the negative refraction index increases by 9.6% and 19.6%, respectively. When three kinds of vacant defects are introduced into the sample, the ratios of the maximum power of samples with vacant defects to that without defects have the highest value of 1.973 and the lowest value of 0.364, and the absolute values of the negative refraction index have increased by 68.33% and 9.6% accordingly. We think that the defect breaks the periodic structure of the sample, resulting in a new condition of the electromagnetism resonance which leads to the changes of the negative refraction index and the maximum power. So we can regulate the negative refraction index of LHMs by adjusting the defects.
Time-frequency analysis for phase retrieval from traces of frequency resolved optical gating
Authors: Deng Yu-Qiang  , Wang Qing-Yue  , Zhang Zhi-Gang  ,   (1)天津大学精密仪器与光电子工程学院，天津  300072; (2)天津大学精密仪器与光电子工程学院，天津  300072;北京大学信息科学与技术学院，北京  100871; (3)中国计量科学研究院光学与激光计量科学研究所，北京  100013;天津大学精密仪器与光电子工程学院，天津  300072
Published: December 2020

Based on the theory of wavelet-transform analysis for spectral phase retrieval from spectral shearing interferogram, we extract phases from the traces of frequency resolved optical gating (FROG) with time-frequency analysis method. The method enables the phases to be extracted from the ridges of FROG traces directly, and requires no iterative algorithm. For the flap ridges, accurate phases can be extracted. However, for the frequency-varying ridges, the results have great error at the tails of the pulses, and the reasons for error generation are analyzed.
Atomic modeling on the elastic properties of double-walled carbon nanotubes under tension
Authors: Ni Xiang-Gui  , Yin Jian-Wei  ,   (1)中国工程物理研究院研究生部，北京  100088; (2)中国科学技术大学中国科学院材料力学行为和设计重点实验室，合肥  230026
Published: December 2020

The stress versus strain relations and the Poisson's ratios under tension of 4 double-walled carbon nanotubes (DWCNTs) with diameters greater than 1 nm were numerically studied with the molecular dynamics method. The simulation shows that in the elastic range the stress and the strain have nonlinear relation, and the tangent elastic moduli of the DWCNTs decrease from 720 to 570 GPa with increasing strain. As the strain increases, the value of Poisson's ratio changes from 0.3 to 0.17, and the sizes of the DWCNTs have little influences on the Poisson's ratio.
The effects of axial magnetic field on electronic properties of carbon nanotubes
Authors: Zhang Zhu-Hua  , Guo Wan-Lin  , Guo Yu-Feng  ,   南京航空航天大学纳米科学研究所，南京  210016
Published: December 2020

The effects of the external magnetic field on the energy gap of carbon nanotubes were investigated by using the tight-bonding method. It was found that, under the applied magnetic field, the peak of energy gap induced by magnetic field and the slope of energy gap versus magnetic field depend on their diameters tightly; when tubes with the same diameters are used, the metal type tubes have the highest energy gap peak. Furthermore, under the magnetic field, the density of states of carbon nanotubes near the Fermi level are also calculated, showing that the Van Hove singularities will exhibit a periodic phenomenon of splitting, moving and merging. Our calculations meet the results from Green's function method, so they are reasonable.
Phase transition from amorphous carbon to diamond nanocrystalline induced by 40Ar+
Authors: Hu Jian-Gang  , Wang Zhen-Xia  , Yong Zhen-Zhong  , Li Qin-Tao  , Zhu Zhi-Yuan  ,   (1)中国科学院上海应用物理研究所，上海  201800; (2)中国科学院上海应用物理研究所，上海  201800;中国科学院研究生院，北京  100049
Published: December 2020

Large-scale diamond nanocrystals of different sizes were synthesized by 60 keV 40Ar+ irradiation on amorphous carbon. Investigated by high-resolution transmission electron microscopy, energy diffraction X-ray spectrum, electron diffraction and Raman spectrum, the diamond crystallites embeded in graphitic film have a high nucleation density (about 1013/cm2) and can grow to large sizes even of the micrometer order. The mechanism of phase transition is discussed preliminarily.
Electronic structure of intrinsic defects and mechanism of donor-acceptor pair luminescence in CuI crystal
Authors: Liu Hai-Lan  , Gu Mu  , Zhang Rui  , Xu Rong-Kun  , Li Guang-Wu  , Ouyang Xiao-Ping  ,   (1)同济大学波耳固体物理研究所，上海  200092; (2)西北核技术研究所，西安  710024; (3)中国工程物理研究院核物理与化学研究所，绵阳  621900; (4)中国原子能科学研究院，北京  102413
Published: December 2020

The electronic structures of γ phase copper iodide crystal and the intrinsic point defects associated with iodine and copper have been studied with relativistic density functional theory and embedded cluster method. The simulations for point defects show that the tetrahedron interstitial copper atoms and copper vacancies may lead to the shallow donor and acceptor levels in the energy gap, which is related with the origins of the broad donor-acceptor pair recombination luminescence band 420—430 nm of CuI crystal.
Study of single-walled carbon nanotube's differential conductance in high magnetic field under high pressure
Authors: Cai Jian-Zhen  , Zhu Hong-Wei  , Wu De-Hai  , Liu Feng  , Lü Li  ,   (1)Department of Electrical and Computer Engineering and Center for Computation and Technology,Louisiana State University,Baton Rouge  70803,USA; (2)Department of Materials Science and Engineering,University of Utah,Salt Lake City  84112,USA; (3)清华大学机械工程系，北京  100084; (4)中国科学院物理研究所，北京  100080
Published: December 2020

Accompanied by the structural phase transition, the electron transport properties of single-walled carbon nanotubes bundles undergo a metal-semiconductor transition at a hydrostatic pressure of 1.5 GPa. In the semiconducting phase there coexist two effects——electron phase coherence which leads to two-dimensional electron weak localization, and Coulomb correlation which leads to the environmental quantum fluctuation of charge transport. We applied hydrostatic pressure up to 10 GPa to single-walled carbon nanotube bundles, and studied the bias voltage dependence of the differential conductance at low temperatures and in strong magnetic fields. Our results show that phase coherence and Coulomb correlation are two effects that independently influence on the electron transport process in the semiconducting phase of the single walled carbon nanotube bundles.
Investigation on stability of microcrystalline silicon thin film transistors
Authors: Li Juan  , Wu Chun-Ya  , Zhao Shu-Yun  , Liu Jian-Ping  , Meng Zhi-Guo  , Xiong Shao-Zhen  , Zhang Fang  ,   (1)科学技术部高技术研究发展中心,北京  100044; (2)南开大学光电子薄膜器件与技术研究所，天津  300071;南开大学光电子薄膜器件与技术天津市重点实验室，天津  300071;南开大学光电信息技术科学教育部重点实验室，天津  300071
Published: December 2020

Instability of a bottom gate microcrystalline silicon (μc-Si) thin film transistor (TFT), of which the active layer was deposited by very high frequency-plasma enhanced chemical vapor deposition with silane concentration of 4% diluted by H2, was measured and compared under two different gate bias stress conditions. A new instability phenomenon of TFT under the voltage bias stress of Vgs=Vds=10 V was found, where the ratio of the source-drain current of μc-Si TFT to its initial value decreases first, then stays flat for a period of time, then increases. However, under the voltage bias stress of Vgs=10 V(Vds＝0 V), the source-drain current of μc-Si TFT decreases as normal exponential decay. Analysis on the change of sub-threshold swing S and threshold voltage Vth with stress time indicated the recoverable degradation could have resulted from the electron trapping and releasing in μc-Si TFT treated by gate-bias stress with Vds≠0.
Improved performance of the dispenser cathode with a Re intermediate layer
Authors: Li Yu-Tao  , Zhang Hong-Lai  , Liu Pu-Kun  , Zhang Ming-Chen  ,   中国科学院电子学研究所,北京  100080
Published: December 2020

A new type dispenser cathode with Os-W/Re dual-layer has been developed. Emission performance and surface microstructure of the cathode with the dual-layer before and after ageing were studied. The performance of the dispenser cathode is improved by introducing a Re intermediate leyer. DC current density of the dispenser cathodes coated with Os-W alloy and Os-W/Re were compared. It is found that the cathode with Os-W/Re shows better emission performance than the cathode with Os-W alloy. Both cathodes were investigated using X-ray photoelectron spectroscopy after full activation. Ternary alloy coating being formed for the cathode with Os-W/Re is the major reason for its better emission performance. Scanning electron microscopy was used for investigating surface microstructures of both kinds of cathodes and the results show that the emitting surface of the cathode with Os-W alloy after ageing appeared non-adherent (flaking) in localized areas. This is one of the reasons for its non-uniform emission. However, surface of the cathode with Os-W/Re does not suffer from peeling under the same conditions, thus ensuring better emission uniformity and functional reliability of the dispenser cathode.
Homotopic mapping method of solution for the sea-air oscillator model of decadal variations in subtropical cells and equatorial pacific
Authors: Mo Jia-Qi  , Lin Wan-Tao  ,   (1)安徽师范大学，芜湖 241000；湖州师范学院，湖州 313000；上海高校计算科学院E-研究院上海交通大学研究所，上海 200240; (2)中国科学院大气物理研究所，北京 100029
Published: December 2020

A time delay equation for sea-air oscillator model is studied. We aim at the cre ateion of an approximate method for solving sea-air oscillator model of nonlinea r equation, employing the theory of homotopic mapping, with due colisideration o f the approximate solution of the corresponding problem. This is an approximate analytical method, which can be further used for analyzing other behaviors of th e sea surface temperature anomaly of the atmosphere-ocean oscillator model.
A new type of non-Noether adiabatic invariants, i.e. adiabatic invariants of Lut zky type, for Lagrangian systems
Authors: Luo Shao-Kai  ,   浙江理工大学数学力学与数学物理研究所,杭州 310018;先进纺织材料与制备技术教育部重点实验室(浙江理工大学),杭州 310018
Published: December 2020

The perturbation of Lie symmetries and new non-Noether adiabatic invariants for the Lagrangian system are studied. The exact invariants of Lutzky type arising f rom the Lie symmetries of Lagrangian system without perturbation are given. Base d on the definition of high-order adiabatic invariants of a mechanical system, the perturbation of Lie symmetries for Lagrangian system under the action of smal l disturbances is investigated, and a type of Lutzky adiabatic invariants of the system are obtained. An example is given to illustrate the application of the m ethod and results.
Generalized synchronization of different orders of chaotic systems with unknown parameters and parameter identification
Authors: Jia Fei-Lei  , Xu Wei  , Du Lin  ,   西北工业大学理学院应用数学系,西安 710072
Published: December 2020

Using add-order method to translate the problem of generalized synchronization of different orders of chaotic systems into the synchronization of systems of identical order. Based on Lyapunov stability theory and adaptive control method, we give the expression of adaptive controller and the updating rule of parameters, then achieve generalized synchronization of different order of chaotic systems with unknown parameters and enable the estimation of the parameters of the drive and the response systems. This method has been applied to solve the generalized synchronization problem of hyperchaotic Lü system, Lorenz system, generalized Lorenz system, and Liu system with unknown parameters. It is proved theoretically that this method is feasible. Numerical simulations show the effectiveness of the adaptive control technique.
State equation of inert plasma
Authors: Tian Yang-Meng  , Wang Cai-Xia  , Jiang Ming  , Cheng Xin-Lu  , Yang Xiang-Dong  ,   (1)北京信息工程学院基础部,北京 100101; (2)四川大学原子分子物理研究所,成都 610065; (3)西南民族大学物理系,成都 610064
Published: December 2020

The paper present a simplified new model for computing state equation and ionization degree of inert plasma, which is based on the Thomas-Feimi(TF)statistical model. We fitted the numerical results of the ionization potential calculated by TF statistical model and obtained the analytic function for computing the ionization potential. Then in the local thermal equilibrium (LTE) case we assume the density of plasma n(Z*) is a continuous function of Z*, and based on Saha equation with Debye-Hückel correction we established a simplified model of state equation of inert plasma. Using this simplified model we calculated the average degree of ionization and the state equation for Helium, Neon and Argon Plasma. The results from this simplified model are basically in agreement with both theory and experimental data. This simplified model can be used to calculate the state equation of plasma mixtures and is expected to have a wider applieation in the field of strongly ionized plasma.
Effect of line shift on the calculated radiative opacity using average atom approach
Authors: Ma Wen  , Jin Feng-Tao  , Yuan Jian-Min  ,   国防科学技术大学物理系,长沙 410073
Published: December 2020

The radiative opacities of iron and bromine plasmas have been calculated using an average atom (AA) model with modification of the transition energy. The line positions obtained after the modification have better agreement with the results of the detailed term accounting model. However,discrepencies still exist for some strong transition peaks. To eliminate the discrepencies the charge state distribution should be included. The mean opacity of iron was calculated. We found that the transition energy shift has obvious effect on the mean opacity of iron plasma at relatively lower densities.
Resonance radiation trapping in Ca, Sr, Ba and Hg ion lasers
Authors: Mao Bang-Ning  , Pan Bai-Liang  , Chen Li  , Wang Yu-Bo  , Wang Li-Min  ,   浙江大学物理系，杭州 310027
Published: December 2020

According to Holstein's theory about radiation trapping effect, the influence of gas temperature and ground-state population density on the effective lifetime of the resonance level is discussed. The results show that the ground-state population density is the dominating factor in the radiation trapping effect. The threshold parameters of radiatoin trapping have been calculated for seven resonance metastable transition laser lines in Ca+, Sr+, Ba+ and Hg+ in different ionization ratios. The threshold temperature of radiation trapping was found to be consistent with the initial lasing temperature for the ionization ratio of 5%, which matches the ionization ratio of 3% to 5% observed in experiment. This consistency reveals that the threshold condition of radiation trapping effect is an important factor for population inversion in lastrs based on the ionic resonance to metastable transition.
Surface plasmon modulated nano-aperture vertical-cavity surface-emitting laser
Authors: Gao Jian-Xia  , Song Guo-Feng  , Guo Bao-Shan  , Gan Qiao-Qiang  , Chen Liang-Hui  ,   中国科学院半导体研究所，纳米光电子实验室,北京 100083
Published: December 2020

Surface plasmon modulated nano-aperture vertical-cavity surface-emitting lasers were fabricated from common 850nm VCSELs. When the diameter of the aperture was 200nm, and the period of grating was 400nm, the maximum far-field output power reached 0.3mW at a driving current of 15mA. The fabrication process was described and the beaming properties were studied via experimentally and theoretically.
A novel technique for improving beam quality of high power laser diode arrays
Authors: Su Zhou-Ping  , Lou Qi-Hong  , Dong Jing-Xing  , Zhou Jun  , Wei Yun-Rong  ,   (1)中国科学院上海光学精密机械研究所，上海 201800; (2)中国科学院上海光学精密机械研究所，上海 201800;中国科学院研究生院,北京 100039
Published: December 2020

According to optical waveguide theory, the far-field profile of laser diode arrays is derived. Basing on the distribution, an off-axis external cavity is designed. By employing the external cavity, at the operating current of 17A, the BPP of output laser is reduced from 1100mm·mrad to 128mm·mrad and the beam quality has about 8.5-fold improvement. The output power is 75% of the radiated power in free-running state without external cavity.
The effect of opening-angle at choke point on the two-dimensional granular flow on a conveyor belt
Authors: Bao De-Song  , Lei Zhe-Min  , Hu Guo-Qi  , Zhang Xun-Sheng  , Tang Xiao-Wei  ,   浙江大学物理系,杭州 310027
Published: December 2020

The relationship between the granular flow rate Q on a two-dimensional conveyor belt and the opening-angle θ at choke point together with the velocity of the conveyor belt and the exit-size has been studied in the experiment. The result shows that the granular flow rate Q is influenced chiefly by the following factors: the exit width R, the speed of the conveyor belt and the opening-angle θ at choke point. The rate of flow Q increases linearly with the speed v and the exit width R, and the rate of flow Q decreases linearly with cosθ when the opening-angle θ is larger than 15° for the dilute granular flow.
Preparation and characteristics research of p-type ZnO films
Authors: Wang Nan  , Kong Chun-Yang  , Zhu Ren-Jiang  , Qin Guo-Ping  , Dai Te-Li  , Nan Mao  , Ruan Hai-Bo  ,   重庆师范大学物理学与信息技术学院，重庆 400047
Published: December 2020

The ZnO films were prepared on Si substrates by RF magnetron sputtering and doped with N by ion-implantation. The samples were then annealed at different temperatures, and showed p-type conduction. The properties were examined by scanning electron microscopy(SEM), X-ray diffraction (XRD), and Hall measurement. The results show that the ZnO films have good surface morphology and are highly c-axis oriented. Hall measurement showed that the resistivity and hole concentration were 41.5Ω·cm and 1.68×1016cm-3， respectively. This paper focuses on the discussion and analysis of the influence of the temperature and time of annealing on the p-type transition of the ZnO films.
Highly c-axis textured ZnO thin films grown by electrochemical deposition and their optical properties
Authors: Gu Jian-Feng  , Fu Wei-Jia  , Liu Ming  , Liu Zhi-Wen  , Ma Chun-Yu  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室，大连 116024
Published: December 2020

ZnO thin films were electrodeposited on glasses coated with a transparent-conductive film (InSnO) with different deposition currents. We have studied the dependence of microstructure, morphology and photoluminescence (PL) on the deposition current by X-ray diffraction, scanning electron microscopy and PL measurement at room temperature. We found that all the films show highly c-axis textured structure and the surface morphology is strongly current-dependent. The transmission spectra show that the films have a transmittance higher than 80% in the visible range. The films have an increase in thickness with the deposition current. The PL spectra exhibit two emission bands, an ultraviolet (UV) one from the exciton transition and a visible light one that might emerge from the defects in the films. The UV emission band has an obvious blueshift, which is found to be due to in doping during the deposition. With the increase of deposition current, the UV emission decreases while the visible light emission goes up.
Electronic and optical properties of CuInSe2 from ab-initio calculations
Authors: Feng Jing  , Xiao Bing  , Chen Jing-Chao  ,   稀贵及有色先进材料教育部重点实验室及云南省新材料制备与加工重点实验室，昆明理工大学，昆明 650093
Published: December 2020

In this article，optical and electronic properties of CIS are studied from DFT calculations. For the exchange-correction energy，we employ GGA in the form of RPBE. The interactions between valence electrons and ionic core are represented by the ultrasoft pseudo potential. By analyzing the results，a mixed bonding state is found to exist in CIS，which is a strong ionic bond with a much weaker covalent bond. The interactions between Cu and Se are much stronger than that between In and Se. It was clarified that CuInSe2 has a direct band gap. We also calculate various optical properties of this material，such as reflection index，refraction index，adsorption spectrum and dielectric constant. For the adsorption spectrum，there are six peaks：3.1，7.6，10.0，16.1，19.0eV，21.0eV and the strongest adsorption peak is located in ultraviolet region.
Surface dynamic evolution of Ta film growth in the initial stage
Authors: Yang Ji-Jun  , Xu Ke-Wei  ,   西安交通大学金属材料强度国家重点实验室，西安 710049
Published: December 2020

Tantalum thin films with thicknesses varying from 15 to 250nm were grown on silicon substrates by magnetron sputtering. Surface morphology of the films was investigated by atomic force microscopy. Then the film surface dynamic evolution was analyzed within the framework of dynamic scaling theory. The results show that the growth exponent β is about 0.17 for the films thinner than 50nm and 0.45 for thicker films. With the increase of film thickness，the roughness exponent α increases from 0.24 to 0.69 and remains constant for the films thicker than 50nm. The dynamic surface evolution reveals the growth transition from island coalescence to bulk film growth. Surface islands prefer lateral growth to vertical growth during island coalescence.
Influence of evaporation conditions on the structure of the polycrystalline lead iodide films
Authors: Li Yu-Hong  , He De-Yan  , Zhang Yu  , Li Zhen-Sheng  ,   (1)兰州大学核科学与技术学院，兰州 730000; (2)兰州大学物理科学与技术学院，兰州 730000
Published: December 2020

Polycrystalline lead iodide (PbI2) thin films have been prepared on glass substrates by vacuum evaporation. The influences of evaporating rate，the distance between the resources and the substrates，the thickness of the films and the temperature of the substrate on the structure of the film were studied. The structures of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results shows that the films were (001) preferentially grown，when the substrate was at room temperature. At higher substrate temperature，the films were mostly (003) preferentially grown and the size of the grains were larger. The internal stress became smaller when the substrate temperature became higher.
Abnormal minigap induced by superconducting proximity effects in a metallic film
Authors: Yu Hua-Ling  ,   淮阴师范学院物理与电子学系，淮安 223001
Published: December 2020

The scattering matrix approach is applied to study tunneling spectra in normal metal/normal metal/superconductor double junctions. The abnormal minigap in tunneling conductance is attributed to the phase coherence of electrons and Andreev-reflected holes in the middle metallic film. We consider a combination of the coherent tunneling with the sequential tunneling and the calculated results provide a reasonable explanation for the abnormal minigap observed in recent experiments.
Structure and magnetic properties of NiFe2O4 nanoparticles prepared by low-temperature solid-state reaction
Authors: Liu Jin-Hong  , Zhang Ling-Fei  , Tian Geng-Fang  , Li Ji-Chen  , Li Fa-Shen  ,   (1)兰州大学磁学与磁性材料教育部重点实验室，兰州 730000; (2)兰州大学磁学与磁性材料教育部重点实验室，兰州 730000；中国原子能科学研究院中子散射实验室，北京 102413; (3)英国曼彻斯特大学物理与天文学院，曼彻斯特 M60 1DQ; (4)英国曼彻斯特索尔福德大学材料科学研究所，曼彻斯特 M5 4WT
Published: December 2020

NiFe2O4 nanoparticle series samples in the grain size range of 8—47nm were successfully synthesized by low-temperature solid-state reaction. The X-ray diffractometer (XRD)，HRPT neutron powder diffractometer，vibrating sample magnetometer (VSM) and superconducting quantum interference devices (SQUID) were used to characterize the structure，magnetic properties and surface anisotropy of nanoparticles. Data of XRD and neutron diffraction showed that the lattice constants of NiFe2O4 nanoparticles were lager than that of the bulk counterpart. Oxygen parameters suggested that lattice distortion were decreased with reduced particle sizes. In comparison with the bulk material，smaller magnetization，larger coercive force and anisotropy energy density for nanoparticles were observed. The critical sizes for transition from multidomain to single domain and for superparamagnetic transition were estimated to be 40nm and 16nm，respectively.
Effect of oxygen content on the dielectric properties of polycrystalline BiFeOδ ceramics
Authors: Chang Fang-Gao  , Song Gui-Lin  , Fang Kun  , Wang Zhao-Kui  ,   河南师范大学物理与信息工程学院，新乡 453007
Published: December 2020

Multiferroic BiFeOδ ceramics of various oxygen contents (δ) were prepared by solid state reaction. Frequency dependence of dielectric properties of BiFeOδ samples at room temperature was measured in the frequency range from 40Hz to 1MHz with a HP4294A precision impedance analyzer. For all the samples, the dielectric constant and loss decrease with measurement frequency. The effect of introducing oxygen vacancy or excess oxygen is to reduce the dielectric constant of BiFeO3. The dielectric loss in BiFeOδ increases with oxygen content. The large change (10%—35%) in the dielectric properties of BiFeO3 samples with various oxygen content(δ) may be understood in terms of the space charge limited conduction associated with crystal defects. The effects of oxygen content on the crystal structure of BiFeO3　ceramics were also investigated using positron annihilation technique (PAT). It has been found that the mean positron lifetime in BiFeOδ　is strongly dependent on the oxygen content. Introducing oxygen vacancy leads to an increase in positron lifetime and a decrease in local electron density of BiFeO3 ceramics.
Effects of neodymium doping on microstructures and ferroelectric properties of bismuth titanate ferroelectric thin films
Authors: Tan Cong-Bing  , Zhong Xiang-Li  , Wang Jin-Bin  , Liao Min  , Zhou Yi-Chun  , Pan Wei  ,   (1)低维材料及其应用技术教育部重点实验室,湘潭大学,湘潭 411105; (2)低维材料及其应用技术教育部重点实验室,湘潭大学,湘潭 411105;湖南科技大学物理学院,湘潭 411201; (3)清华大学材料科学与工程系,北京 100084
Published: December 2020

The Bi4-xNdxTi3O12(x=0.00,0.30,0.45,0.75,0.85,1.00,1.50) ferroelectric thin films were prepared on the Pt/Ti/SiO2/Si(100) substrates using sol-gel method. The effect of neodynium doping on the microstructures and ferroelectric properties of films were studied. The experimental results show that Nd3+ only substitutes Bi3+ in the pseudo-perovskite block when Nd content x is lower than 0.45. When Nd content x is about 0.45, the film has the largest remnant polarization (2Pr) of 32.7μC·cm-2 at an applied field of about 270kV·cm-1. At x>0.45, part of Nd ions are incorporated into the (Bi2O2)2+block, which would change the microstructure of (Bi2O2)2+ block and weaken its functions as the insulating layer and the space charge storage, resulting in the decrease of the 2Pr. When x=1.50, the dopout would destroy the structure of (Bi2O2)2+ block, which leads to ferroelectric-paraelectric phase transition of the film.
Use of wiener filtration in wavelet domain in ensemble pulsar time algorithm
Authors: Zhong Chong-Xia  , Yang Ting-Gao  ,   (1)中国科学院国家授时中心，西安 710600; (2)中国科学院国家授时中心，西安 710600；中国科学院研究生院，北京 100049；北京无线电计量测试研究所，北京 100854
Published: December 2020

Pulsars rotate extremely stably, they can be used as time standard. However, pulsar time defined by single pulsar is influenced by several noise resources. To weaken these influences to get a more stable time scale, one can take ensemble analysis to obtain the ensemble pulsar time. Since different pulsars have different rotation frequency, and the noise source have different influence on different frequency of each pulsar，we can apply wavelet analysis to integrate the pulsar time, and this algorithm can take consideration of the long-term and short-term stability of pulsar time. On the other hand, the pulsar timing residuals are caused by reference atomic clock and pulsar itself, so we can apply Wiener filtration analysis to distinguish the two parts, and then calculate the ensemble pulsar time with the residuals after removing the error of reference atomic clock. Based on both of the two algorithms, a new algorithm of Wiener filtration in wavelet domain has been presented, which combines the merits of wavelet analysis and Wiener filtration and can remove the noise influence to pulsar time more effectively. Experimental results prove that Wiener filtration in wavelet domain can reduce noise influence of pulsar timing residuals effectively.