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Spectral characteristics of laser-plasma instabilities with a broadband laser

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Chinese physics B 2024年第8期33卷 362-368页

作者：许国潇康宁雷安乐刘会亚赵耀周申蕾安红海熊俊王瑞荣谢志勇周熙晨方智恒王伟 Key Laboratory of High Power Laser and physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Shanghai institute of Laser {1. China Academy of Engineering PhysicsShanghai 201800China School of Science Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China University of Chinese Academy of Sciences Beijing 100049China

Recent experimental progresses regarding broadband laser-plasma instabilities(LPIs)show that a 0.6%laser bandwidth can reduce backscatters of the stimulated Brillouin scattering(SBS)and the stimulated Raman scattering(SRS)at normal incidence[***.1.20351.2(2024)].In this paper,we present a further discussion of the spectral distributions of the scatters developed by broadband LPIs,in addition to a brief validation of the effectiveness of bandwidth on LPIs mitigation at oblique *** backscatter has a small redshift in the broadband case contrary to the blueshift with narrowband laser,which may be explained by the self-cross beam energy transfer between the various frequency components within the *** backscatter spectrum presents a peak at a longer wavelength in the broadband case compared to the short one in the narrowband case,which is possibly attributed to the mitigation effect of bandwidth on filaments at underdense *** three-halves harmonic emission(3ω/2)has a one-peak spectral distribution under the broadband condition,which is different from the two-peak distribution under the narrowband condition,and may be related to the spectral mixing of different frequency components within the bandwidth if the main sources of the two are both two-plasmon decays.

关键词： laser-plasma instability laser bandwidth light spectrum

Scaling laws governing the elastic properties of 3D graphenes

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Science China(Technological Sciences) 2024年第6期67卷 1748-1756页

作者： LI Ming LU Guo YU HaoDong LI MengLei ZHENG FaWei Centre for Quantum physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of TechnologyBeijing100081China Beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of TechnologyBeijing100081China Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing100088China Department of physics Capital Normal UniversityBeijing100048China

In this study,we comprehensively investigated the scaling law for elastic properties of three-dimensional honeycomb-like graphenes(3D graphenes)using hybrid neural network potential-based molecular dynamics simulations and theoretical *** elastic constants were obtained as functions of honeycomb hole size,denoted by the graphene wall length *** five independent elastic constants in the large-L limit are proportional to L^(-1..The associated coefficients are combinations of elastic constants of two-dimensional ***-order terms including L^(-2)and L^(-3)emerge for finite L *** have three origins,the distorted areas close to the joint lines of 3D graphenes,the variation in solid angles between graphene plates,and the bending distortion of graphene ***,the chirality becomes essential with decreasing L because the joint line structures are different between the armchair and zigzag-type 3D *** findings provide insights into the elastic properties of graphene-based superstructures and can be used for further studies on graphene-based materials.

关键词： scaling law neural network elastic properties 3D graphene

Phase-field simulations of the effect of temperature and interface for zirconiumδ-hydrides

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Chinese physics B 2024年第4期33卷 701-710页

作者：陈子航盛杰刘瑜施小明黄厚兵许可王越超武帅孙博刘海风宋海峰 School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Department of physics University of Science and Technology BeijingBeijing 100083China

Hydride precipitation in zirconium cladding materials can damage their integrity and *** temperature and material defects have a significant effect on the dynamic growth of *** this study,we have developed a phasefield model based on the assumption of elastic behaviour within a specific temperature range(61. K-653 K).This model allows us to study the influence of temperature and interfacial effects on the morphology,stress,and average growth rate of zirconium *** results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride *** ultimate determinant of hydride orientation is the loss of interfacial coherency,primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree *** escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical,accompanied by the onset of redirection ***,redirection occurs at a critical mismatch level,denoted as qc,and remains unaffected by variations in temperature and interfacial ***,this redirection leads to an increase in the maximum stress,which may influence the direction of hydride crack *** research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.

关键词： zirconium hydride phase-field method temperature effect mismatch degree

Design of hadronic calorimeter for DarkSHINE experiment

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Nuclear Science and Techniques 2024年第9期35卷 155-167页

作者： Zhen Wang Rui Yuan Han-Qing Liu Jing Chen Xiang Chen Kim Siang Khaw Liang Li Shu Li Kun Liu Qi-Bin Liu Si-Yuan Song Tong Sun Xiao-Long Wang Yu-Feng Wang Hai-Jun Yang Jun-Hua Zhang Yu-Lei Zhang Zhi-Yu Zhao Chun-Xiang Zhu Xu-Liang Zhu Yi-Fan Zhu Tsung-Dao Lee institute Shanghai Jiao Tong University1 Lisuo RoadShanghai 201210China institute of Nuclear and Particle {1. School of Physics and Astronomy800 Dongchuan RoadShanghai 200240China Key Laboratory for Particle Astrophysics and Cosmology(MOE) Shanghai Key Laboratory for Particle Physics and Cosmology(SKLPPC)Shanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China Key Laboratory of Nuclear physics and Ion-beam Application(MOE) Fudan UniversityShanghai 200443China institute of Modern {1. Fudan UniversityShanghai 200443China

The sensitivity of the dark photon search through invisible decay final states in low-background experiments relies sig-nificantly on the neutron and muon veto efficiencies,which depend on the amount of material used and the design of the detector *** paper presents the optimized design of the hadronic calorimeter(HCAL)used in the DarkSHINE experiment,which is studied using a GEANT4-based simulation *** geometry is optimized by comparing a traditional design with uniform absorbers to one that uses different thicknesses at different locations on the detector,which enhances the efficiency of vetoing low-energy neutrons at the sub-GeV *** overall size and total amount of material used in the HCAL are optimized to be lower,owing to the load and budget requirements,whereas the overall performance is studied to satisfy the physical objectives.

关键词： Hadronic calorimeter GEANT4 simulation Neutron background Scintillation detector Dark photon

Research on the Encapsulation Device for Lunar Samples

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 104-117页

作者： Yonggang Du Chunyong Wang Haoling Li Ying Zhou Ming Ji Xuesong Wang Lanzhou institute of {1. CASTLanzhou 730000China

The encapsulation of lunar samples is a core research area in the third phase of the Chinese Lunar Exploration *** seal assembly,opening and closing mechanism(OCM),and locking mechanism are the core components of the encapsulation device of the lunar samples,and the requirements of a tight seal,lightweight,and low power make the design of these core components *** this study,a combined sealing assembly,OCM,and locking mechanism were investigated for the *** sealing architecture consists of rubber and an Ag-In alloy,and a theory was built to analyze the *** of the electroplate Au coating on the knife-edge revealed that the hermetic seal can be significantly *** driving principle for coaxial double-helical pairs was investigated and used to design the ***,a locking mechanism was created using an electric initiating explosive device with orifice *** optimizing the design,the output parameters were adjusted to meet the requirements of the lunar *** experimental results showed that the helium leak rate of the test pieces were not more than 5×1.^(-1.) Pa·m^(3)·s^(-1.,the minimum power of the OCM was 0.3 W,and the total weight of the principle prototype was 2.9 *** explosive driven locking mechanism has low *** investigation solved the difficulties in achieving tight seal,light weight,and low power for the lunar explorer,and the results can also be used to explore other extraterrestrial objects in the future.

关键词： Lunar samples Encapsulation Vacuum seal Mechanism

Longitudinal dependence of the forecast accuracy of the ionospheric total electron content in the equatorial zone

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Geodesy and Geodynamics 2024年第5期15卷 528-541页

作者： Artem Kharakhashyan Olga Maltseva institute for {1. Southern Federal University344090Russia

The longitudinal dependence of the behavior of ionospheric parameters has been the subject of a number of works where significant variations are *** also applies to the prediction of the ionospheric total electron content(TEC),which neural network methods have recently been widely ***,the results are mainly presented for a limited set of *** paper examines the longitudinal dependence of the TEC forecast accuracy in the equatorial *** this case,the methods are used that provided the best accuracy on three meridians:European(30°E),Southeastern(1.0°E)and American(75°W).Results for the stations considered are analyzed as a function of longitude using the Jet Propulsion Laboratory Global Ionosphere Map(JPL GIM)for *** results are for 2 h ahead and 24 h ahead *** was found that in this case,based on the metric values,three groups of architectures can be *** first group included long short-term memory(LSTM),gated recurrent unit(GRU),and temporal convolutional networks(TCN)models as a part of unidirectional deep learning models;the second group is based on the recurrent models from the first group,which were supplemented with a bidirectional algorithm,increasing the TEC forecasting accuracy by 2-3 *** third group,which includes the bidirectional TCN architecture(BiTCN),provided the highest *** this architecture,according to data obtained for 9 equatorial stations,practical independence of the TEC prediction accuracy from longitude was observed under the following metrics(Mean Absolute Error MAE,Root Mean Square Error RMSE,Mean Absolute Percentage Error MAPE):MAE(2 h)is 0.2 TECU approximately;MAE(24 h)is 0.4 TECU approximately;RMSE(2 h)is less than 0.5 TECU except Niue station(RMSE(2 h)is 1.TECU approximately);RMSE(24 h)is in the range of 1.0-1.7 TECU;MAPE(2 h)1.except Darwin station,MAPE(24 h)<2%.This result was confirmed by data from additional 5 stations that formed latitudinal chains in the

关键词： Ionosphere Total electron content Forecasting BiGRU BiLSTM BiTCN Temporal convolution

Observation of Doppler shift f_(D) modulated by the internal kink mode using conventional reflectometry in the EAST tokamak

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plasma Science and Technology 2024年第3期26卷 1-9页

作者：李恭顺张涛耿康宁文斐叶凯萱徐立清朱翔张学习钟富彬周振杨书琪周子强喻琳兰婷王守信提昂张寿彪刘海庆李国强高翔 the EAST Team institute of {1. physics Chinese Academy of SciencesHefei 230031People's Republic of China Advanced Energy Research Center Shenzhen UniversityShenzhen 518060People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China

In this paper we present a new experimental observation using a conventional reflectometry technique,poloidal correlation reflectometry(PCR),in the Experimental Advanced Superconducting Tokamak(EAST).The turbulence spectrum detected by the PCR system exhibits an asymmetry and induced Doppler shift f_(D)during the internal kink mode(IKM)rotation *** Doppler shift f_(D)is the target measurement of Doppler reflectometry,but captured by conventional *** show that the Doppler shift f_(D)is modulated by the periodic changes in the effective angle between the probing wave and cutoff layer normal,but not by plasma *** fishbone mode and saturated long-lived mode are typical IKMs,and this modulation phenomenon is observed in both ***,the value of the Doppler shift f_(D)is positively correlated with the amplitude of the IKM,even when the latter is ***,the positive and negative frequency components of the Doppler shift f_(D)can be asymmetric,which is related to the plasma configuration.A simulated analysis is performed by ray tracing to verify these *** results establish a clear link between f_(D)and IKM rotation,and are helpful for studying the characteristics of IKM and related physical phenomena.

关键词： microwave reflectometry Doppler shift internal kink mode

Explaining the dynamics of the sub-relativistic electron third belt in the Earth's radiation belts by using medium Earth orbit satellite observations

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Earth and Planetary physics 2024年第5期8卷 762-775页

作者： JiaLi Chen Hong Zou YuGuang Ye institute of Space {1. and Applied Technology Peking University

The Earth's electron radiation belts typically exhibit a two-belt structure. However, observations from the Van Allen Probes revealed the existence of a three-belt structure. This structure consists of an inner belt, a slot region, a remnant belt, a “second slot,” and a new outer belt(or the “third belt”). The formation of the structure involves both the partial loss of the original outer belts and the formation of the third belts. These processes are likely associated with radial diffusion induced by ultra-low-frequency(ULF) waves. In this study, we mainly analyzed electron flux data from medium Earth orbit(MEO) navigation satellites M1.–M1. to supplement the observational evidence for the sub-relativistic electron(～1.0–500 keV) three-belt structure. Evidence of substorm injections and ULF waves during the three-belt event was identified, suggesting they played significant roles in the formation and evolution of the third *** injections may introduce new electron populations to the third belt, whereas ULF waves may influence the evolution of the third belt through radial diffusion. Toward the end of the three-belt event, the compression of the magnetosphere by shocks may lead to the dropout of the third belt because of the magnetopause shadowing effect and outward radial diffusion, ultimately disrupting the three-belt structure. This study provides more evidence for the presence of a sub-relativistic electron three-belt structure and offers an analysis of the evolutionary mechanisms of the third belt, which may contribute to a comprehensive understanding of the electron three-belt structure in the radiation belts.

关键词： third belt sub-relativistic electrons three-belt structure radiation belts magnetic storms and substorms wave–particle interactions

Digital signal acquisition system for complex nuclear reaction experiments

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Nuclear Science and Techniques 2024年第1期35卷 124-133页

作者： Wei-Liang Pu Yan-Lin Ye Jian-Ling Lou Jia-Hao Chen School of physics and State Key Laboratory of Nuclear physics and Technology Peking UniversityBeijing 100871China institute of Applied {1. and Computational Mathematics Beijing 100094China

A digital data-acquisition system based on XIA LLC products was used in a complex nuclear reaction experiment using radioactive ion beams.A flexible trigger system based on a field-programmable gate array(FPGA)parametrization was developed to adapt to different experimental sizes.A user-friendly interface was implemented,which allows converting script language expressions into FPGA internal control *** proposed digital system can be combined with a conventional analog data acquisition system to provide more *** performance of the combined system was veri-fied using experimental data.

关键词： Digital signal acquisition system Trigger Programmable logic Timestamp