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Study of dual-frequency-band millimeter-wave extended interaction klystron based on dual-2πmode 认领 引用
1
作者 XU Che LU Jia-Ni +1 位作者 TANG Yong-Liang TANG Xian-Feng 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2026年第1期42-50,共9页
This paper proposes a novel dual-frequency-band millimeter-wave extended interaction klystron ampli-fier(EIKA).It is primarily based on the multimode operating mechanism of dual-2πmode.This design inte-grates a broad... This paper proposes a novel dual-frequency-band millimeter-wave extended interaction klystron ampli-fier(EIKA).It is primarily based on the multimode operating mechanism of dual-2πmode.This design inte-grates a broadband traveling-standing-wave mode input cavity with a dual-2πstanding-wave mode output cavity,resulting in a compact slow-wave structure design that efficiently operates within a total circuit length of approxi-mately 24 mm.Particle-in-cell simulation results reveal that under a 15.6 kV,1 A electron beam and a uniform 0.6 T magnetic field,the device achieves output power for 183-1024 W across a broadly 1.20 GHz bandwidth,spanning 93.76-94.96 GHz.Remarkably,it facilitates dual-band output in both lower-2πand upper-2πbands,delivering maximum gains of 37.09 dB(1024.10 W at 93.90 GHz)and 35.75 dB(752.20 W at 94.84 GHz),with-3 dB bandwidths of 0.33 GHz and 0.20 GHz,respectively.The effectiveness for the dual-2πmode design is further confirmed through a cold-test experiment using the perturbation method.This experiment demonstrated typical dual-2πmode field distribution profiles,affirming the design's efficacy. 展开更多
关键词 extended interaction klystron(EIK) dual-band multi-mode millimeter waves vacuum electronics
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Dual‐Metal Co‐Doping Strategy Enhances the Hydrogen Dissociation and Hydrogen Release Performance of LiBH4Assisted by Ensemble Learning 认领 引用
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作者 Zishan Luo Xi Sun +9 位作者 Hang Zhang Yuhang Zhou Wenhao Yan Tao Zhang Jiawei Li Hong Cui Weizhi Tian Rong Feng Lingxia Jin Hongkuan Yuan 《Rare Metals》 SCIE EI CAS CSCD 2026年第6期625-639,共15页
LiBH4has drawn significant attention due to its high theoretical hydrogen storage capacity of 18.5 wt%,yet its practical application is hindered by the harsh dehydrogenation conditions.This paper proposes a strateg... LiBH4has drawn significant attention due to its high theoretical hydrogen storage capacity of 18.5 wt%,yet its practical application is hindered by the harsh dehydrogenation conditions.This paper proposes a strategy integrating ensemble learning with density functional theory(EL-DFT)for rapidly screening modified LiBH4systems that exhibit both structural stability and low dehydrogenation temperatures within an acceptable capacity loss range.The results indicate that,in dual‐metal‐doped LiBH4structures(TM1TM2@LiBH4)at different doping sites,the synergistic interaction between the crystal structure and the local electronic environment collectively reduces the dissociation energy(Ed)of H in the BH4−group.Using the substitution energy(Esub)and dissociation energy(Ed)of 60 randomly selected TM1TM2@LiBH4structures as target values,a dual ensemble model AdaBoost.R2 was trained,yielding excellent predictive models:AdaBoost‐SVR(Esub)and AdaBoost‐GBR(Ed),with R2 values reaching 0.970 and 0.927,respectively.SHAP analysis reveals that structures with TM1 anchored at the S1 and S2 sites exhibit lower hydrogen dissociation energy.In particular,the ScSc(S1)@LiBH4structure shows Esub=−0.977 eV and Ed=0.549 eV.DFT calculations further demonstrate that dual Sc doping weakens the stability of B-H bonds,significantly lowering the dissociation energy barrier.AIMD simulations confirm that this structure initiates hydrogen release at 500 K.The EL-DFT strategy successfully identifies materials with mild dehydrogenation conditions and stable structures,providing theoretical guidance for further exploration of solid‐state hydrogen storage materials. 展开更多
关键词 co‐doping effect density functional theory ensemble learning hydrogen release performance modified LiBH4
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Reversible thermodynamic pathways in shock-compressed liquid nitrogen:Unveiling the role of molecular dissociation in shock cooling and phase transition 认领 引用
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作者 Muhammad Sabeeh Akram Shumail Sattar +5 位作者 Yi-Wen Wei Lei Yang Wen-Shuo Yuan Zhuo-Ning Fan Qi-Jun Liu Fu-Sheng Liu 《Matter and Radiation at Extremes》 SCIE EI CAS CSCD 2026年第3期107-120,共14页
This study investigates the high-pressure behavior of liquid nitrogen(LN2),under dynamic compression from 19 to 89 GPa and corresponding temperatures from 4000 to 8200 K.Using Doppler velocimetry and multichannel pyro... This study investigates the high-pressure behavior of liquid nitrogen(LN2),under dynamic compression from 19 to 89 GPa and corresponding temperatures from 4000 to 8200 K.Using Doppler velocimetry and multichannel pyrometry,we determine the Hugoniot states,shock temperatures,and emissivity.The application of sequential shocks and subsequent pressure release process lead to significant variations in radiance and radiative temperature,which help to predict the optical transparency at the LN2/LiF interface.Our results indicate the existence of two distinct thermodynamic pathways.In experiments with an initial shock>30 GPa,at the second shock(re-shock),the fluid undergoes shock cooling,which we attribute to the formation of a transient complex molecular state.Further,during pressure release,we observe thermal energy emission,which indicates that decompression primarily governs the phase transitions as well as the reversible thermodynamic pathways.By contrast,LN2 initially shocked to 19 GPa undergoes dissociation upon re-shock,followed by recombination during pressure release,with no evidence of cooling being observed.A comparison of these results suggests that shock cooling consistently appears above 30 GPa and 6500 K.Furthermore,these two regimes are differentiated by their response to pressure release:while both show a decrease in emissivity that reflects restoration of the fluid’s transparency,the magnitudes are dramatically different.A 21%decrease occurs in the shock-cooling regime,compared with a 39%reduction in the dissociation-dominated regime. 展开更多
关键词 reversible thermodynamic pathways doppler velocimetry molecular dissociation shock compressed liquid nitrogen dynamic compression multichannel pyrometrywe pressure release process sequential shocks
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Evolution of Dust Properties and Disk Structure of the Young Star EX Lup 认领 引用
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作者 Fei Gao Yao Liu +5 位作者 Dafa Li Min Fang Fujun Du Xi Liu Sheng Jin Lei Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2026年第7期71-84,共14页
EX Lup is a young M0-type variable star that undergoes intermittent accretion-driven outbursts.In 2008,it experienced the largest outburst ever recorded.Mid-infrared spectroscopic observations exhibit pronounced chang... EX Lup is a young M0-type variable star that undergoes intermittent accretion-driven outbursts.In 2008,it experienced the largest outburst ever recorded.Mid-infrared spectroscopic observations exhibit pronounced changes in dust emission features following this event.Literature studies interpreted these changes as evidence for the formation of crystalline dust grains in the inner disk and their subsequent transport to outer disk regions.In this work,we performed a homogeneous decomposition of the mid-infrared spectra with the goal of quantitatively constraining the mineralogical properties of dust grains and their temporal evolution.We found that the dust crystallinity peaked at∼8%during the 2008 outburst,then gradually declined and returned to a quiescent level of∼1%.This pattern of crystallinity variation is consistent with the scenario in which crystalline grains form in the inner disk during the outburst and are subsequently redistributed to larger disk radii.Moreover,the mid-infrared spectroscopic observations reveal that the flux ratio(F24/F8)between 24 and 8μm exhibits a complex trend,and particularly reaches the smallest value during the 2008 event.We investigated the ratio F24/F8as a function of time with self-consistent radiative transfer models.The modeling shows that the 2008 outburst caused the inner rim and inner disk regions(R≲10 au)to expand vertically,and the observed trend in the ratio F24/F8can be well interpreted as a variation in the scale height of the disk. 展开更多
关键词 (stars:)circumstellar matter protoplanetary disks infrared:stars
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Deformation of wire-arc additively manufactured magnesium alloy under uniaxial tension:In situ synchrotron X-ray diffraction and tomography study 认领 引用
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作者 Y.X.Ye W.Z.Wang +6 位作者 Tao Yang X.J.Zhao B.X.Bie Ke Li Y.J.Deng L.Lu S.N.Luo 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2026年第6期300-316,共17页
Deformation dynamics of a wire-arc additively manufactured(WAAM)Mg-3Al-1Zn alloy are investigated via in situ synchrotron computed tomography(CT)and X-ray diffraction along with in situ digital imaging correlation mea... Deformation dynamics of a wire-arc additively manufactured(WAAM)Mg-3Al-1Zn alloy are investigated via in situ synchrotron computed tomography(CT)and X-ray diffraction along with in situ digital imaging correlation measurements,and postmortem microstructural characterizations.Bulk true stress-strain curves,mesoscale strain fields and microscale X-ray diffraction patterns are obtained simultaneously for tensile loading along the build direction(BD)and the transverse direction(TD).The alloys texture-free,equiaxed microstructure gives rise to the pronounced activation of non-basal slip systems,and limited{10-12}extension twinning.This critical shift in deformation mode from highly anisotropic deformation relying on twinning to more isotropic deformation driven by non-basal slip explains the observed weak anisotropy in its mechanical behavior and stable strain hardening,different from conventional Mg alloys.Our in situ observations further dynamically track the evolution of solidification voids,demonstrating how their initial preferred orientation and subsequent reorientation dictate early ductility and influence damage accumulation mechanisms.Additionally,loading temperature significantly modulates the intricate interplay between these active deformation modes,evolving void morphology,and ultimately the fracture mechanisms.This work provides multi-scale mechanistic insights into how WAAM-specific microstructures,temperature,and defect evolution interact during deformation,providing new insights into the high-performance Mg alloys. 展开更多
关键词 Wire-arc additive manufacturing In situ synchrotron XRD In situ micro computed tomography Deformation dynamics.
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Study on lightning-attraction characteristics of high-speed maglev trains and implications for railway lightning protection 认领 引用
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作者 Qirui Peng Jianqiong Zhang +1 位作者 Qingfeng Wang Xiangqiang Li 《Railway Sciences》 2026年第2期260-275,共16页
Purpose-To support the operational safety and lightning protection design of high-speed maglev railways,this paper quantitatively evaluates how suspension height and operating speed influence lightning susceptibility.... Purpose-To support the operational safety and lightning protection design of high-speed maglev railways,this paper quantitatively evaluates how suspension height and operating speed influence lightning susceptibility.It characterizes trends of the critical background electric field with respect to these two variables,tracks the evolution of surface hotspot distributions and identifies dominant attachment locations and their sensitivity.Design/methodology/approach-A coupled procedure of“electrostatic field-aerodynamic flow field-scaled assessment”is proposed.The electrostatic model provides surface field-enhancement factors and their spatial distribution,while turbulent-flow simulations characterize near-wall density variations induced by speed.Under a unified leader height,a critical criterion based on a density-scaled breakdown field maps these two fields to a train-wise critical background electric field.Representative regions(nose,roof and bottom or tail)are used to build statistical metrics for hotspot migration and dominance with speed.Findings-Increasing suspension height weakens electric-field coupling to ground,raises the critical background-field threshold and reduces the relative contribution of bottom and edge regions.At the same suspension height,a rigidly grounded train has a lower critical threshold than an electrically floating one.Within 0-500 km/h,the train-wise threshold decreases slowly with speed.Region-wise,roof-tail and bottom-mid sections show a decreasing trend with speed,while the nose stagnation point increases slightly;over the entire speed range,the dominant region remains the roof-tail section.Originality/value-Within a unified framework,suspension height and operating speed affect lightning attraction through two distinct channels.Suspension height mainly modifies the threshold and hotspot distribution by changing geometric polarization,whereas speed alters discharge-initiation difficulty through aerodynamically induced density variations.The framework evaluates these effects separately and in combination,explaining the slow variation of the global threshold and the subtle evolution of hotspot locations and providing a physics-based reference for lightning protection design and operational safety assessment of high-speed maglev railway systems. 展开更多
关键词 High-speed maglev train Lightning-attraction characteristics Suspension height Operating speed Railway system safety Lightning protection
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First-principles study of electronic structure and superconductivity of xenon nitride under high pressure 认领 引用
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作者 ZHAO Shuang GAO Juan JIAO Zhen 《原子与分子物理学报》 CAS 北大核心 2026年第2期107-115,共9页
Employing first-principles calculations based on density functional theory,we establish the high-pressure phase diagrams for XeN3 and XeN6,and investigate their electronic and superconducting properties under hi... Employing first-principles calculations based on density functional theory,we establish the high-pressure phase diagrams for XeN3 and XeN6,and investigate their electronic and superconducting properties under high pressure.Our results indicate that at their respective lowest stable pressures,XeN3 is a direct-bandgap semiconductor with a bandgap of 1.64 eV,whereas XeN6 is an indirect-bandgap material with a bandgap of 1.45 eV,which transitions to a metallic state as pressure increases.The density of states analysis reveals significant hybridization between N-2p and Xe-5p orbitals,with contributions to the Fermi level predominantly from these orbitals.Additionally,it was found that XeN6 becomes a superconductor under high pressures after metallization,with its superconducting transition temperature showing a linear dependence on pressure. 展开更多
关键词 First-principles calculations XeN3 XeN6 Electronic properties Superconductivity
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Electronic,mechanical properties and impact sensitivity of metal azides MN3(M=Li,Na,Ag,Cu)and X(N3)2(X=Cu,Hg,Pb)from first-principles study 认领 引用
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作者 LIU Yu-Shi QIN Han +1 位作者 JIAO Zhen LIU Fu-Sheng 《原子与分子物理学报》 CAS 北大核心 2026年第2期123-129,共7页
Utilizing the first-principles calculation method of density functional theory,we investigate the electronic and mechanical properties of metal azides MN3(M=Li,Na,Ag,Cu)and X(N3)2(X=Cu,Hg,Pb),and explore thei... Utilizing the first-principles calculation method of density functional theory,we investigate the electronic and mechanical properties of metal azides MN3(M=Li,Na,Ag,Cu)and X(N3)2(X=Cu,Hg,Pb),and explore their correlation with impact sensitivity.The findings indicate that the impact sensitivities of the seven metal azides can be roughly ranked by considering both the band gap of the crystal and the relative atomic mass energy of the metal.Furthermore,it is suggested that the strong covalent nature of the metal-N in the upper valence band may be a significant factor contributing to the sensitivity observed in Cu(N3)2and CuN3.The dominance of azide in the upper valence band while that of metal cations in lower conduction bands could explain why Hg(N3)2and Pb(N3)2exhibit higher sensitivity levels.Additionally,an analysis on mechanical properties reveals that the mechanical properties of metal azides will greatly affect their impact sensitivity,and the compression resistance is the most influential factor. 展开更多
关键词 Metal azides Electronic structure Mechanical properties Impact sensitivity
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First-principles calculations of the structural,electronic,and thermodynamic properties of 4,7-diamino-1H-[1,2,3]triazolo[4,5-d]pyridazin-5-ium nitrate 认领 引用
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作者 LEI Si-Jia LI Jia-Hao +1 位作者 JIAO Zhen LIU Fu-Sheng 《原子与分子物理学报》 CAS 北大核心 2026年第6期130-136,共7页
Nitrogen-rich ionic salts have been regarded as highly efficient energy materials and have received increasing attention in recent studies.This study focuses on a newly synthesized nitrate,4,7-diamino-1H-[1,2,3]triazo... Nitrogen-rich ionic salts have been regarded as highly efficient energy materials and have received increasing attention in recent studies.This study focuses on a newly synthesized nitrate,4,7-diamino-1H-[1,2,3]triazolo[4,5-d]pyridazin-5-ium nitrate.The structural,electronic,and thermodynamic properties of the compound are investigated using first-principles calculations.The optimized lattice constants are in close agreement with the experimentally measured values,validating the reliability of the computational approach.The electronic band structure analysis indicates that the compound possesses an indirect bandgap of 3.179 eV.Thermodynamic functions including constant volume heat capacity(C V),enthalpy(H),Helmholtz free energy(F),entropy(S),Gibbs free energy(G),and Debye temperature(Θ)are computed.This work serves as a useful reference for future studies on energetic ionic salts. 展开更多
关键词 4,7-diamino-1H-[1,2,3]triazolo[4,5-d]pyridazin-5-ium nitrate Electronic properties Thermodynamic properties
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Machine learning approaches for predicting impact sensitivity and detonation performances of energetic materials 认领 引用 被引量：7
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作者 Wei-Hong Liu Qi-Jun Liu +1 位作者 Fu-Sheng Liu Zheng-Tang Liu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2025年第3期161-171,共11页
Excellent detonation performances and low sensitivity are prerequisites for the deployment of energetic materials.Exploring the underlying factors that affect impact sensitivity and detonation performances as well as ... Excellent detonation performances and low sensitivity are prerequisites for the deployment of energetic materials.Exploring the underlying factors that affect impact sensitivity and detonation performances as well as exploring how to obtain materials with desired properties remains a long-term challenge.Machine learning with its ability to solve complex tasks and perform robust data processing can reveal the relationship between performance and descriptive indicators,potentially accelerating the development process of energetic materials.In this background,impact sensitivity,detonation performances,and 28 physicochemical parameters for 222 energetic materials from density functional theory calculations and published literature were sorted out.Four machine learning algorithms were employed to predict various properties of energetic materials,including impact sensitivity,detonation velocity,detonation pressure,and Gurney energy.Analysis of Pearson coefficients and feature importance showed that the heat of explosion,oxygen balance,decomposition products,and HOMO energy levels have a strong correlation with the impact sensitivity of energetic materials.Oxygen balance,decomposition products,and density have a strong correlation with detonation performances.Utilizing impact sensitivity of 2,3,4-trinitrotoluene and the detonation performances of 2,4,6-trinitrobenzene-1,3,5-triamine as the benchmark,the analysis of feature importance rankings and statistical data revealed the optimal range of key features balancing impact sensitivity and detonation performances:oxygen balance values should be between-40%and-30%,density should range from 1.66 to 1.72 g/cm3,HOMO energy levels should be between-6.34 and-6.31 eV,and lipophilicity should be between-1.0 and 0.1,4.49 and 5.59.These findings not only offer important insights into the impact sensitivity and detonation performances of energetic materials,but also provide a theoretical guidance paradigm for the design and development of new energetic materials with optimal detonation performances and reduced sensitivity. 展开更多
关键词 Energetic materials Machine learning Impact sensitivity Detonation performances Feature descriptors Balancing strategy
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Quantified causality dependence of dynamical relation between zonal flow and heat transport on isotope mass in tokamak edge plasmas 认领 引用
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作者 Yu He Zhongbing Shi +10 位作者 Yuhong Xu Jun Cheng Jianqiang Xu Zhihui Huang Na Wu Kaiyang Yi Weice Wang Min Jiang Longwen Yan Xiaoquan Ji Wulyu Zhong 《Chinese Physics B》 SCIE EI CAS CSCD 2025年第10期452-457,共6页
The isotope effect on zonal flows(ZFs)and turbulence remains a key issue that is not completely solved in fusion plasmas.This paper presents the first experimental results of the ab initio prediction of causal relatio... The isotope effect on zonal flows(ZFs)and turbulence remains a key issue that is not completely solved in fusion plasmas.This paper presents the first experimental results of the ab initio prediction of causal relation between geodesic acoustic mode(GAM)and ambient turbulence at different isotope masses in the edge of HL-2A tokamak,where transfer entropy method based on information-theoretical approach is utilized as a quantified indicator of causality.Analysis shows that GAM is more pronounced in deuterium plasmas than in hydrogen,leading to a lower heat transport as well as more peaked profiles in the former situation.The causal impact of GAM on conductive heat flux component is stronger than on the convective component,which is resulted from a larger causal influence of zonal flow on temperature fluctuation.While a stronger GAM in deuterium plasmas has larger influence on all flux components,the relative change in temperature fluctuation and coefficient is more obvious when the ion mass varies.These findings not only offer an in-depth understanding of the real causality between zonal flow and turbulence in the present isotope experiments,but also provide useful ways for the physical understandings of transport and zonal flow dynamics in future deuterium-tritium fusion plasmas. 展开更多
关键词 isotope effect zonal flow heat transport causality
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Retrieval of energy-momentum tensor for self-gravitating and collapsing thin spherical shell 认领 引用
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作者 Wenbin Lin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2025年第7期171-173,共3页
We prove that the post-Newtonian time-dependent metric of the self-gravitating and collapsing infinitely-thin spherical shell does satisfy Einstein field equations to the corresponding order.Meanwhile, the leading-ord... We prove that the post-Newtonian time-dependent metric of the self-gravitating and collapsing infinitely-thin spherical shell does satisfy Einstein field equations to the corresponding order.Meanwhile, the leading-order components of the thin spherical shell's energy-momentum tensor are recovered. 展开更多
关键词 post-Newtonian approximation gravitomagnetic field second gravitational potential spherically-symmetric system
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Ok Null Test with Multi-Task Gaussian Processes:Cosmic Curvature and Data Compatibility 认领 引用
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作者 Yungui Gong Qing Gao +1 位作者 Xuchen Lu Zhu Yi 《Chinese Physics Letters》 SCIE EI CAS CSCD 2026年第5期414-421,共8页
The Ok null test can not only assess whether the cosmic curvature is zero—thereby,if true,reducing degeneracies between cosmic curvature and other cosmological parameters—but also provide a model-independent chec... The Ok null test can not only assess whether the cosmic curvature is zero—thereby,if true,reducing degeneracies between cosmic curvature and other cosmological parameters—but also provide a model-independent check of compatibility between different data sets.However,traditional implementations often require absolute distance data from Type Ia supernovae(SNe Ia)or baryon acoustic oscillation(BAO)measurements,limiting their applicability because such absolute distance data are usually not accessible.The BAO Alcock-Paczynski(AP)parameter FAP is a measurement of a distance ratio,making the Dark Energy Spectroscopic Instrument(DESI)AP measurements particularly well suited for the Oknull test,as no absolute distance measurements are required.We propose a novel null test of cosmic curvature tailored to DESI BAO data that combines FAPwith ratios such as D′V/DVor D′M/DM.Crucially,this construction eliminates the need for absolute distance measurements.We further develop multi-task Gaussian processes to perform the null test.This approach can also be applied to a joint DESI BAO and SNe Ia dataset,and we find that DESI BAO and SNe Ia data are compatible.Although there is~2σ evidence of nonzero curvature at low redshift z■0.5,this result is not conclusive,largely due to the lack of observational data in the corresponding redshift range. 展开更多
关键词 baryon acoustic oscillation bao measurementslimiting multi task Gaussian processes type ia supernovae sne data setshowevertraditional data compatibility absolute distance data cosmic curvature assess whether cosmic curvature zero therebyif
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Microwave electric field induced spin Stark effect of trapped electron on liquid helium 认领 引用
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作者 Y F Wang Miao Zhang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2026年第6期200-206,共7页
We show the Stark effect of electronic spin in the cavity-QED system of a trapped electron on liquid helium.This effect is derived from strong spin-orbit coupling and the electric dipole interaction between the microw... We show the Stark effect of electronic spin in the cavity-QED system of a trapped electron on liquid helium.This effect is derived from strong spin-orbit coupling and the electric dipole interaction between the microwave-driving cavity field and orbital states of a trapped electron.We further show that the obtained effect can be used to implement the single photon detection of gigahertz(GHz) microwaves using the spin Ramsey interferometry. 展开更多
关键词 spin-orbit coupling ac Stark effect electron on liquid helium microwave singlephoton detection
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Design and manufacture of planar GaAs Gunn diode for millimeter wave application 认领 引用 被引量：5
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作者 黄杰 杨浩 +3 位作者 田超 董军荣 张海英 郭天义 《Chinese Physics B》 SCIE EI CAS 2010年第12期451-455,共5页
GaAs-based planar Gunn diodes with A1GaAs hot electron injector have been successfully developed to be used as a local oscillator of 76 GHz in monolithic millimeter-wave integrated circuits. We designed two kinds of s... GaAs-based planar Gunn diodes with A1GaAs hot electron injector have been successfully developed to be used as a local oscillator of 76 GHz in monolithic millimeter-wave integrated circuits. We designed two kinds of structure diode, one has a fixed distance between the anode and cathode, but has variational cathode area, the other has a fixed cathode area, but has different distances between two electrodes. The fabrication of Gunn diode is performed in accordance with the order of operations： cathode defining, mesa etching, anode defining, isolation, passivation, via hole and electroplating. A peak current density of 29.5 kA/cm^2 is obtained. And the charavteristics of negative differential resistance and the asymmetry of the current-voltage curve due to the A1GaAs hot electron injector are discussed in detail. It is demonstrated that the smaller size of active area corresponds to the smaller current, and the shorter distance between anode and cathode also corresponds to the lower threshold voltage and higher peak current, and hot electron injector can effectively enhance the radio frequency conversion efficiency and output power. 展开更多
关键词 GaAs planar Gunn diode hot electron injector millimeter generation
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Structural,electronic,optical,elastic properties and Born effective charges of monoclinic HfO_2 from first-principles calculations 认领 引用 被引量：4
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作者 刘其军 张宁超 +1 位作者 刘福生 刘正堂 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期496-503,共8页
First-principles calculations of structural, electronic, optical, elastic, mechanical properties, and Born effective charges of monoclinic HfO2 are performed with the plane-wave pseudopotential technique based on the ... First-principles calculations of structural, electronic, optical, elastic, mechanical properties, and Born effective charges of monoclinic HfO2 are performed with the plane-wave pseudopotential technique based on the density-functional theory. The calculated structural properties are consistent with the previous theoretical and experimental results. The electronic structure reveals that monoclinic HfO2 has an indirect band gap. The analyses of density of states and Mulliken charges show mainly covalent nature in Hf-O bonds. Optical properties, including the dielectric function, refractive index, extinction coefficient, reflectivity, absorption coefficient, loss function, and optical conductivity each as a function of photon energy are calculated and show an optical anisotropy. Moreover, the independent elastic constants, bulk modulus, shear modulus, Young＇s modulus, Poisson＇s ratio, compressibility, Lam6 constant, sound velocity, Debye temperature, and Born effective charges of monoclinic HfO2 are obtained, which may help to understand monoclinic HfO2 for future work. 展开更多
关键词 density-functional theory optical properties elastic constants monoclinic HfO2
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First-principles study on the mechanical properties and thermodynamic properties of Mo-Ta alloys 认领 引用 被引量：2
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作者 Xin ZHANG Heng LI +12 位作者 Yuhong XU Qijun LIU Yangyang LIU Zilin CUI Haifeng LIU Xianqu WANG Jie HUANG Hai LIU Jun CHENG Ming LI Shaofei GENG Changjian TANG Guangjiu LEI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第6期180-187,共8页
The mechanical properties,thermodynamic properties and electronic structure of Mo1-xTax(Mo-Ta)alloys(x=0,0.0625,0.125,0.25,0.3125,0.5 and 1)were calculated by using firstprinciples.The electronic structure of Mo-Ta al... The mechanical properties,thermodynamic properties and electronic structure of Mo1-xTax(Mo-Ta)alloys(x=0,0.0625,0.125,0.25,0.3125,0.5 and 1)were calculated by using firstprinciples.The electronic structure of Mo-Ta alloys was analysed by the projected density of states(PDOS).The low temperature heat capacity was estimated by Fermi energy and Debye temperature.It is shown that the formation enthalpy will decrease with the increase of Ta content,and the cohesive energy will increase with the increase of the Ta content.On the other hand,the addition of Ta atoms will reduce the strength and improve the ductility of Mo-Ta alloys,the Debye temperature will decrease and the low temperature heat capacity will be improved with the increase of the Ta content.All these results will be useful for the research of new plasma grid(PG)materials,which is mainly used in neutral beam injection(NBI)systems to produce negative hydrogen ions. 展开更多
关键词 first principles calculations Mo-Ta alloy mechanical properties thermodynamic
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The FAST Galactic Plane Pulsar Snapshot Survey.II.Discovery of 76 Galactic Rotating Radio Transients and the Enigma of RRATs 认领 引用 被引量：1
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作者 D.J.Zhou J.L.Han +15 位作者 Jun Xu Chen Wang P.F.Wang Tao Wang Wei-Cong Jing Xue Chen Yi Yan Wei-QiSu Heng-Qian Gan Peng Jiang Jing-Hai Sun Hong-Guang Wang Na Wang Shuang-Qiang Wang Ren-Xin Xu Xiao-Peng You 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第10期1-70,共70页
We have carried out the Galactic Plane Pulsar Snapshot(GPPS)survey by using the Five-hundred-meter Aperture Spherical radio Telescope(FAST),the most sensitive systematic pulsar survey in the Galactic plane.In addition... We have carried out the Galactic Plane Pulsar Snapshot(GPPS)survey by using the Five-hundred-meter Aperture Spherical radio Telescope(FAST),the most sensitive systematic pulsar survey in the Galactic plane.In addition to more than 500 pulsars already discovered through normal periodical search,we report here the discovery of 76 new transient radio sources with sporadic strong pulses,detected by using the newly developed module for a sensitive single-pulse search.Their small DM values suggest that they all are Galactic rotating radio transients(RRATs).They show different properties in the follow-up observations.More radio pulses have been detected from 26 transient radio sources but no periods can be found due to a limited small number of pulses from all FAST observations.The followup observations show that 16 transient sources are newly identified as being the prototypes of RRATs with a period already determined from more detected sporadic pulses,and 10 sources are extremely nulling pulsars,and 24 sources are weak pulsars with sparse strong pulses.On the other hand,48 previously known RRATs have been detected by the FAST,either during verification observations for the GPPS survey or through targeted observations of applied normal FAST projects.Except for one RRAT with four pulses detected in a session of 5-minute observation and four RRATs with only one pulse detected in a session,sensitive FAST observations reveal that 43 RRATs are just generally weak pulsars with sporadic strong pulses or simply very nulling pulsars,so that the previously known RRATs always have an extreme emission state together with a normal hardly detectable weak emission state.This is echoed by the two normal pulsars J1938+2213 and J1946+1449 with occasional brightening pulses.Though strong pulses of RRATs are very outstanding in the energy distribution,their polarization angle variations follow the polarization angle curve of the averaged normal pulse profile,suggesting that the predominant sparse pulses of RRATs are emitted in the same region with the same geometry as normal weak pulsars. 展开更多
关键词 (stars:)pulsars:general surveys methods:data analysis
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Effects of sawtooth heat pulses on edge flows and turbulence in a tokamak plasma 认领 引用 被引量：1
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作者 赵开君 Yoshihiko NAGASHIMA +22 位作者 郭志彬 Patrick H DIAMOND 董家齐 严龙文 Kimitaka ITOH Sanae-I ITOH 李晓博 李继全 Akihide FUJISAWA Shigeru INAGAKI 程钧 许健强 Yusuke KOSUGA Makoto SASAKI 王正汹 张怀强 陈俞钱 曹小岗 余德良 刘仪 宋显明 夏凡 王硕 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第1期1-9,共9页
Enhancements of edge zonal flows,radial electric fields,and turbulence are observed in electron cyclotron resonance heating-heated plasmas(Zhao et al 2013 Nucl.Fusion 53083011).In this paper,the effects of sawtooth he... Enhancements of edge zonal flows,radial electric fields,and turbulence are observed in electron cyclotron resonance heating-heated plasmas(Zhao et al 2013 Nucl.Fusion 53083011).In this paper,the effects of sawtooth heat pulses on flows and turbulence are presented.These experiments are performed using multiple Langmuir probe arrays in the edge plasmas of the HL-2A tokamak.The edge zonal flows,radial electric fields,and turbulence are all enhanced by sawteeth.Propagation of the zonal flow and turbulence intensities is also observed.The delay time of the maximal intensity of the electric fields,zonal flows,and turbulence with respect to the sawtooth crashes is estimated as~1 ms and comparable to that of the sawtooth-triggered intermediate phases.Not only the zonal flows but also the radial electric fields lag behind the turbulence.Furthermore,the intensities of both the zonal flows and electric fields nearly linearly increase/decrease with the increase/decrease of the turbulence intensity.A double-source predator-prey model analysis suggests that a relatively strong turbulence source may contribute to the dominant zonal flow formation during sawtooth cycles. 展开更多
关键词 tokamak Langmuir probe arrays edge flows and turbulence sawtooth heat pulses
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Non-volatile tunable multispectral compatible infrared camouflage based on the infrared radiation characteristics of Rosaceae plants 认领 引用 被引量：1
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作者 Xin Li Xinye Liao +9 位作者 Junxiang Zeng Zao Yi Xin He Jiagui Wu Huan Chen Zhaojian Zhang Yang Yu Zhengfu Zhang Sha Huang Junbo Yang 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2025年第8期68-83,共16页
Most multispectral compatible infrared camouflage devices primarily focus on achieving low emissivity but neglect environmental emissivity matching when environmental emissivity exceeds that of the devices,this create... Most multispectral compatible infrared camouflage devices primarily focus on achieving low emissivity but neglect environmental emissivity matching when environmental emissivity exceeds that of the devices,this creates a"low-emissivity exposure"risk.To address this issue,we develop a tunable multispectral compatible infrared camouflage device using phase change material In3SbTe2(IST).Simulation and experimental results demonstrate that in both the amorphous(aIST)and crystalline(cIST)states,the device achieves simulated plant infrared camouflage and ultra-low emissivity infrared camouflage within the atmospheric window bands(3–5μm and 8–14μm).To address thermal management,it utilizes two non-atmospheric window bands(2.5–3μm and 5–8μm)for heat dissipation.Additionally,laser stealth is realized at three specific wavelengths(1.064μm,1.55μm,and 10.6μm).In the visible spectrum,high absorptivity enables effective visible light camouflage.Adjusting the geometric parameters of top layer structure enables color variation.This work not only highlights potential applications in reversible switching,reconfigurable imaging,and dynamic coding using IST but also offers an effective strategy to counter multispectral detection technology. 展开更多
关键词 multispectral compatible infrared camouflage phase change laser stealth heat management color variation
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