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Test particle simulation on the ion and electron zebra stripes and their time evolution in inner radiation belt

Science China(Technological Sciences) 2018年第4期61卷 623-632页

作者： WANG YongFu ZONG QiuGang ZHOU XuZhi State Key Laboratory of Nuclear physics and Technology School of Physics and Fusion Simulation CenterPeking University institute of space physics and Applied Technology Peking University Key Laboratory of Earth and Planetary physics Chinese Academy of Sciences

During February 15–16, 2014, the energetic electron spectrogram for four successive inner radiation belt crossing show clearly the electron zebra structures and their time evolution which last for about 17 h. Unfortunately, the time of flight(TOF) in RBSPICE measurement is turned off below 3 RE, and the ion measurement is contaminated by electrons. Thus in this study we studied the differences between the ion and electron zebra stripe structures and their time evolution using simple theory and test particle simulation, combining the electron measurement from RBSIPICE onboard Van Allen Probes. Theoretical analysis predicts that the ion zebra stripe structures should lie at a higher energy range than the corresponding electron zebra stripe structures due to that the directions of gradient B drift and corotation E×B drift are the same for electrons while opposite for ions. Test particle simulation with the dipole magnetic field and Volland-Stern electric field model have shown that the ion and electron zebra stripe structures could be produced by the convection electric field penetrating into the inner magnetosphere in this event, with their time evolution determined by total drift velocity that are different for ions and electrons. The predicted differences between the ion and electron zebra stripe structures are partially verified through observation. The ion zebra stripe structures could have potential influence to the ring current.

关键词： inner radiation belt ion zebra stripes energetic ions energetic electrons

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Three-dimensional magnetic reconnection in complex multiple X-point configurations in an ancient solar-lunar terrestrial system

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Chinese physics B 2024年第3期33卷 488-495页

作者：何向磊毛傲华孙萌萌邹继同王晓钢 School of physics Harbin Institute of TechnologyHarbin 150001China Laboratory for space Environment and Materials Science Harbin Institute of TechnologyHarbin 150001China

Magnetic reconnection processes in three-dimensional(3D)complex field configurations have been investigated in different magneto-plasma systems in space,laboratory,and astrophysical ***-dimensional(2D)features of magnetic reconnection have been well developed and applied successfully to systems with symmetrical property,such as toroidal fusion plasmas and laboratory experiments with an axial *** in asymmetric systems,the 3D features are inevitably different from those in the 2D *** reconnection structures in multiple celestial body systems,particularly star-planet-Moon systems,bring fresh insights to the understanding of the 3D geometry of ***,we take magnetic reconnection in an ancient solar-lunar terrestrial magneto-plasma system as an example by using its crucial parameters approximately estimated already and also some specific applications in pathways for energy and matter transports among Earth,ancient Moon,and the interplanetary magnetic field(IMF).Then,magnetic reconnection of the ancient lunar-terrestrial magnetospheres with the IMF is investigated numerically in this *** a 3D simulation for the Earth-Moon-IMF system,topological features of complex magnetic reconnection configurations and dynamical characteristics of magnetic reconnection processes are *** is found that a coupled lunar-terrestrial magnetosphere is formed,and under various IMF orientations,multiple X-points emerge at distinct locations,showing three typical magnetic reconnection structures in such a geometry,i.e.,the X-line,the triple current sheets,and the A-B null *** results can conduce to further understanding of reconnection physics in 3D for plasmas in complex magnetic configurations,and also a possible mechanism for energy and matters transport in evolutions of similar astrophysical systems.

关键词： magnetic reconnection multiple X-points complex magneto-plasma system

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Roles of initial current carrier in the distribution of field-aligned current in 3-D Hall MHD simulations

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Science China(Technological Sciences) 2008年第3期51卷 323-336页

作者： ZHANG XianGuo PU ZuYin MA ZhiWei ZHOU XuZhi institute of space physics and Applied Technology School of Earth and Space SciencePeking UniversityBeijing 100871China institute of Plasma physics Chinese Academy of SciencesHefei 230031China institute of Fusion Theory and Simulation School of ScienceZhejiang UniversityHangzhou 310027China

A three-dimensional (3-D) Hall MHD simulation is carried out to study the roles of initial current carrier in the topology of magnetic field, the generation and distribu- tion of field aligned currents (FACs), and the appearance of Alfvén waves. Consid- ering the contribution of ions to the initial current, the topology of the obtained magnetic field turns to be more complex. In some cases, it is found that not only the traditional By quadrupole structure but also a reversal By quadrupole structure appears in the simulation box. This can explain the observational features near the diffusion region, which are inconsistent with the Hall MHD theory with the total ini- tial current carried by electrons. Several other interesting features are also emerged. First, motions of electrons and ions are decoupled from each other in the small plasma region (Hall effect region) with a scale less than or comparable with the ion inertial length or ion skin depth di=c/ωp. In the non-Hall effect region, the global magnetic structure is shifted in +y direction under the influence of ions with initial y directional motion. However, in the Hall effect region, magnetic field lines are bent in ?y direction, mainly controlled by the motion of electrons, then By is generated. Second, FACs emerge as a result of the appearance of By. Compared with the prior Hall MHD simulation results, the generated FACs shift in +y direction, and hence the dawn-dusk symmetry is broken. Third, the Walén relation in our simulations is consistent with the Walén relation in Hall plasma, thus the presence of Alfvén wave is confirmed.

关键词： collisionless magnetic reconnection Hall MHD simulation field aligned current (FAC) Alfvén wave Hall effects

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The detection, extraction and parameter estimation of extreme-mass-ratio inspirals with deep learning

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Science China(physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 86-96页

作者： Qianyun Yun Wen-Biao Han Yi-Yang Guo He Wang Minghui Du Hangzhou institute for Advanced Study University of Chinese Academy of Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences School of physics and Astronomy Shanghai Jiao Tong University School of Astronomy and space Science University of Chinese Academy of Sciences Taiji Laboratory for Gravitational Wave Universe (Beijing/Hangzhou) University of Chinese Academy of Sciences Lanzhou Center for Theoretical physics Key Laboratory of Theoretical Physics of Gansu Province Key Laboratory of Quantum Theory and Applications of MoE Lanzhou University institute of Theoretical physics & Research Center of Gravitation Lanzhou University International Centre for Theoretical physics Asia-Pacific (ICTP-AP) University of Chinese Academy of Sciences (UCAS) Center for Gravitational Wave Experiment National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences

One of the primary goals of space-borne gravitational wave detectors is to detect and analyze extreme-mass-ratio inspirals(EMRIs). This task is particularly challenging because EMRI signals are complex, lengthy, and faint. In this work, we introduce a2-layer convolutional neural network(CNN) approach to detect EMRI signals for space-borne detectors, achieving a true positive rate(TPR) of 96.9% at a 1% false positive rate(FPR) for signal-to-noise ratio(SNR) from 50 to 100. Especially, the key intrinsic parameters of EMRIs such as the mass, spin of the supermassive black hole(SMBH) and the initial eccentricity of the orbit can also be inferred directly by employing a neural network. The mass and spin of the SMBH can be determined at 99% and 92% respectively. This will greatly reduce the parameter spaces and computing cost for the following Bayesian parameter *** model also has a low dependency on the accuracy of the waveform model. This study underscores the potential of deep learning methods in EMRI data analysis, enabling the rapid detection of EMRI signals and efficient parameter estimation.

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Analysis of magnetotail flux rope events by ARTEMIS observations

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Science China(Technological Sciences) 2014年第5期57卷 1010-1019页

作者： TIAN AnMin SHI QuanQi ZONG QiuGang DU Jian FU SuiYan DAI YaNan School of space Science and physics Shandong University at Weihai State Key Laboratory of space weather Chinese Academy of Sciences Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment institute of space physics and Applied Technology Peking University

Three earthward flowing magnetic flux ropes observed in the duskside plasma sheet at geocentric solar magnetospheric coordinate X~–55 Re by P1 and P2 of acceleration,reconnection,turbulence and electrodynamics of moon’s interaction with the sun mission during 13:00–15:00 UT on July 3,2012,were *** morphologies of the flux ropes were studied in detail based on Grad-Shfranov reconstruction method and electronic pitch angle distribution *** is found that(1)the flux rope cross-sectional dimensions are 1.0 Re×0.78 Re,1.3 Re×0.78 Re,and 2.5 Re×1.25 Re,*** magnetic field lines were asymmetric about the center with field line compression on both sides of the current sheet at the leading region;(2)the electron energy flux data presented asymmetry with larger electron flux and lower temperature in the precursor *** flux ropes were blocked by the resistance of compressed particle density in the front central plasma sheet and the enhanced magnetic field on its sides;and(3)it is found that the flux rope has a layered *** inside out,event 1 can be divided into three regions,namely electronic depletion core region,closed field line region,and the caudal area possible with fields connected with the *** suggests that the flux ropes cannot merge with the tail magnetic field lines near the lunar ***,the flux rope asymmetrical shape reflects the different reconnection processes that caused it on both sides of the magnetic *** events shown in this paper support the multiple X-line magnetic reconnection model for flux ropes with in situ observations.

关键词： magnetic flux ropes ARTEMIS GS reconstruction method asymmetry

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Large solar energetic particle event that occurred on 2012 March 7 and its VDA analysis

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Research in Astronomy and Astrophysics 2016年第8期16卷 33-42页

作者： Liu-Guan Ding Xin-Xin Cao Zhi-Wei Wang Gui-Ming Le School of physics and Optoelectronic Engineering Institute of Space WeatherNanjing University of Information Science and Technology National Center for space Weather China Meteorological Administration

On 2012 March 7, the STEREO Ahead and Behind spacecraft, along with near-Earth spacecraft （e.g. SOHO, Wind） situated between the two STEREO spacecraft, observed an extremely large global solar energetic particle （SEP） event in Solar Cycle 24. Two successive coronal mass ejections （CMEs） have been detected close in time. From the multi-point in-situ observations, it can be found that this SEP event was caused by the first CME, but the second one was not involved. Using velocity dispersion analysis （VDA）, we find that for a well magnetically connected point, the energetic protons and electrons are released nearly at the same time. The path lengths to STEREO-B （STB） for protons and electrons have a distinct difference and deviate remarkably from the nominal Parker spiral path length, which is likely due to the presence of interplanetary magnetic structures situated between the source and STB. Also, the VDA method seems to only obtain reasonable results at well-connected locations and the inferred release times of energetic particles in different energy channels are similar. We suggest that good-connection is crucial for obtaining both an accurate release time and path length simultaneously, agreeing with the modeling result of Wang ＆ Qin （2015）.

关键词： Sun particle emission -- Sun coronal mass ejection (CME) -- method velocity dispersionanalysis (VDA)

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In-situ lunar dust deposition amount induced by lander landing in Chang’E-3 mission

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Science China(Technological Sciences) 2020年第3期63卷 520-527页

作者： ZHANG HaiYan WANG Yi CHEN LiPing ZHANG He LI CunHui ZHUANG JianHong LI DeTian WANG YongJun YANG ShengSheng LI XiongYao WANG WeiDong Science and Technology on Vacuum Technology and physics Laboratory Lanzhou Institute of PhysicsChinese Academy of Space TechnologyLanzhou 730000China Beijing institute of physics Chinese Academy of Space TechnologyBeijing 100094China Center for Lunar and Planetary Sciences Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China School of Mechano-Electronic Engineering Xidian UniversityXi'an 710071China

China first in-situ lunar dust experiment is performed by a lunar dust detector in Chang’E-3 mission. The existed dust(less than 20 μm in diameter) properties, such as levitation, transportation and adhesion, are critical constraints for future lunar exploration program and even manned lunar exploration. Based on the problems discussed above, the in-situ lunar dust detector is originally designed to characterize dust deposition properties induced by lander landing as a function of environmental temperature, solar incident angle and orbit short circuit current on the northern Mare Imbrium, aiming to study lunar dust deposition properties induced by lander landing in depth. This paper begins with a brief of introduction of Chang’E-3 lunar dust detector design,followed by a series of experimental analysis of this instrument under different influencing factors, and concludes with lunar dust mass density deposition amount observed on the first lunar day is about 0.83 mg/cm^2, which is less than that observed in Apollo 11 mission because the landing site of Chang’E-3 has the youngest mare basalts comparing with previous Apollo and lunar landing sites. The young geologic environment is less weathered and thus it has thinner layer of lunar dust than Apollo missions’;hence, the amount of kicked-up lunar dust in Chang’E-3 mission is less than that in Apollo 11 mission.

关键词： in-situ lunar dust experiment Chang'E-3 mission unnatural mechanisms lunar dust deposition amount

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CsI-bowl:an ancillary detector for exit channel selection inγ-ray spectroscopy experiments

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Nuclear Science and Techniques 2023年第9期34卷 32-39页

作者： Xing-Chi Han Shuo Wang Hong-Yi Wu Zhi-Huan Li Guo-Zhu Shi Ruo-Fu Chen Yue-Zhao Zhang Shou-Yu Wang Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and PhysicsInstitute of Space SciencesShandong UniversityWeihai 264209China WeiHai Research institute of Industrial Technology of Shandong University Weihai 264209China School of physics and State Key Laboratory of Nuclear physics and Technology Peking UniversityBeijing 100871China institute of Modern physics Chinese Academy of SciencesLanzhou 73000China

A particle detector array designed for light-charged particles, known as the CsI-bowl, was built for exit channel selection for in-beam γ-ray spectroscopy experiments. This device is composed of 64 CsI(Tl) detectors, organized in a structure reminiscent of a tea-bowl. High quantum efficiency photodiodes, characterized by their minimal mass, were employed to collect scintillation light. Its design, construction, particle identification resolution, and its effectiveness in relation to exit channel selection are described in this paper. In source tests, the optimal figure of merit for the identification of α-particles and γ-rays using the charge comparison method was found to be 3.3 and 12.1 for CsI detectors coupled to photodiodes and avalanche photodiodes, respectively. The CsI-bowl demonstrated effectiveness in identifying particles, specifically the emission of protons and α-particles in the58Ni(19F, xpyn) fusion–evaporation reaction, thereby enabling the selection of the desired exit channels.

关键词： Light charged particle detector array Particle identification Charge comparison method

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Visibility enhancement in two-dimensional lensless ghost imaging with true thermal light

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Chinese physics B 2017年第6期26卷 101-105页

作者：陈希浩燕玲吴炜孟少英吴令安孙志斌王超翟光杰 Key Laboratory of Optoelectronic Devices and Detection Technology College of PhysicsLiaoning University Laboratory of Optical physics Institute of Physics and Beijing National Laboratory for Condensed Matter PhysicsChinese Academy of Sciences Laboratory of space Science Experiment Technology Center for Space Science and Applied ResearchChinese Academy of Sciences

We report an experimental demonstration of two-dimensional（2D） lensless ghost imaging with true thermal light. An electrodeless discharge lamp with a higher light intensity than the hollow cathode lamp used before is employed as a light source. The main problem encountered by the 2D lensless ghost imaging with true thermal light is that its coherence time is much shorter than the resolution time of the detection system. To overcome this difficulty we derive a method based on the relationship between the true and measured values of the second-order optical intensity correlation, by which means the visibility of the ghost image can be dramatically enhanced. This method would also be suitable for ghost imaging with natural sunlight.

关键词： ghost imaging true thermal light image visibility two-dimensional image

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Possible Candidates for Chirality in the Odd-Odd As Isotopes

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Chinese physics Letters 2020年第11期37卷 12-15页

作者： Chen Liu Shouyu Wang Bin Qi Hui Jia Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and PhysicsInstitute of Space SciencesShandong UniversityWeihai 264209China

The deformations and the corresponding configurations of the odd-odd As isotopes are investigated using the adiabatic and configuration-fixed constrained triaxial relativistic mean field(RMF)*** minima with triaxial deformations and high-j particle-hole configurations are obtained in 72,74,76,78,80As,where the chiral doublet bands are possible to *** existence of multiple chiral doublet(MχD)is demonstrated in 74,76,*** on the calculated single-particle levels,we also find possible coexistence of chiral and pseudospin symmetries in the odd-odd As isotopes.

关键词： theory. chiral configuration

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