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Wide-range characteristics of beam perveance and saddle point potential of LIPS-200 ion thruster

Plasma science and technology 2022年第11期24卷 85-92页

作者： Xueer ZHANG Tianping ZHANG Detian LI Juanjuan CHEN Yanhui JIA Science and Technology on Vacuum Technology and Physics Laboratory Key Laboratory of Space Electric Propulsion Technology of Gansu ProvinceLanzhou Institute of PhysicsLanzhou 730000People’s Republic of China

Both the long-life and multi-mode versions of LIPS-200 ion thruster are under investigation in LIP(Lanzhou Institute of physics).To confirm the feasible ranges of the beam current and accel(abbreviation for accelaration)grid potential to apply to the thruster,the wide-range beam perveance(the state of beam focus)and saddle point potential(the lowest potential along beamlet centerline)characteristics of LIPS-200 are studied with a test-verified PIC-MCC(Particle in Cell-Monte Carlo Collisions)*** characteristics are investigated with both the initial and the eroded states of the accel grid aperture *** results show that the feasible ranges of these parameters with respect to perveance/crossover(overfocused)limit extend as the operating time accumulates,while the feasible range of accel grid potential narrows due to a reduced EBSF(electron backstreaming failure)*** feasible ranges determined by the initial condition are:(i)the beam current up to 0.981 A,and(ii)the accel grid potential up to−85 V.A 23%enlargement of the aperture diameter would bring up to 48 V of EBSF margin loss.

关键词： ion thruster perveance limit crossover limit saddle point potential parameter range

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High-entropy sulfurization enables efficient non-noble metal-based NiCoFeCuS electrocatalyst for alkaline oxygen evolution reaction

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Particuology 2024年第10期93卷 180-185页

作者： Pan Yang Mengxiang Sun Jingchuan Wang Jinfeng Li Ruizhu Yang Yawei Hao Li Qi Lijun Yang Xue Liu Institute of Materials China Academy of Engineering PhysicsJiangyou621908China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004China Science and Technology on Surface Physics and Chemistry Laboratory Jiangyou621907China

Highly active and cost-effective oxygen evolution reaction electrocatalysts have become essential to replace commercial electrocatalysts that rely on rare noble ***-entropy sulfide nanomaterials,characterized by abundant randomly distributed elements and inherent stability,possess significant potential for ***,challenges such as uneven composition,partial oxidation,or imprecise synthesis control still remain in the materials ***,a simple and effective two-step hydrothermal method was employed to synthesize NiCoFeCuS nanoparticles supported on foam nickel *** the catalytic active sites produced by electron density redistribution in high-entropy and sulfurization,NiCoFeCuS exhibits excellent alkaline OER performance,with an overpotential of 261 mV and a Tafel slope of 57.97 mV dec^(−1) at the current density of 10 mA cm^(−2),which is only 88%of commercial RuO_(2) without any noble metals.

关键词： High-entropy Sulfurization NiCoFeCuS electrocatalyst Oxygen evolution reaction Overpotentials

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Evaluation and Suppression of Vibrational Noise for Cryogenic Surface Electrode Ion Traps

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Chinese physics Letters 2025年第3期42卷 52-62页

作者： Qingqing Qin Baoquan Ou Wei Wu Yi Xie Ting Chen Chunwang Wu Pingxing Chen Institute for Quantum Science and Technology College of ScienceNational University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Mechanism and Technology of Quantum Information Changsha 410073China Department of Physics College of ScienceNational University of Defense TechnologyChangsha 410073China

Cryogenic ion traps offer substantial advantages over their room-temperature counterparts,particularly in terms of stable ion confinement and ***,this technological advancement has introduced a significant challenge,namely the generation of additional vibrational *** noise is pronounced during the compression and expansion phases of the Gifford–McMahon cycle refrigerator and stems from the mechanical operation of the cold *** residual vibrational noise can modulate the Rabi oscillation frequency,thereby compromising the fidelity of the quantum logic *** this study,we quantitatively assess the impact of residual vibrational noise and introduce an innovative strategy for its *** strategy was designed to reduce superimposed potential fluctuations within a cryogenic surface electrode ion *** measured residual vibrational noise was used for real-time feedback *** the inverse determination of the compensating potential for a stable superimposed trapping potential is an inherently ill-posed problem considering known measurement noise *** applying quadratic programming,we numerically calculated the optimal time series for the compensation *** ensemble of these compensation voltages was applied in real time to the static compensation *** this method is in the theoretical stage,we believe that it can effectively suppress the translation induced by vibrational noise and foster the creation of a stable superimposed harmonic *** deployment of this technique is expected to substantially improve the accuracy of quantum operations,thereby fueling the evolution of quantum technologies.

关键词： vibrational thereby quantum

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Real-Time Local Shear-Wave Splitting Measurement: Application to the Vicinity of the Baihetan Hydropower Plant

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Bulletin of the Seismological Society of America 2025年第2期115卷 505-515页

作者： Han, Xuefei Li, Zefeng Liu, Feng Li, Junlun Yao, Huajian Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space Sciences University of Science and Technology of China Hefei China Mengcheng National Geophysical Observatory University of Science and Technology of China Mengcheng China

Local shear-wave splitting (SWS) measurements can be potentially used to monitor changes in upper crustal anisotropy over time. However, its real-time implementation is not yet available due to the sophisticated measurement procedure. Here, we integrate a fully automated workflow of local SWS measurement into a 4G telemetric nodal seismom-eter system. This system has operated since October 2021 to monitor seismicity near the Baihetan hydropower plant in southwestern China. We validate the system by retrospec-tive evaluation on the reliability and interpretability of the automated measurements. Most fast-wave polarization directions align with the regional maximum horizontal stress and the nearby fault trends, generally consistent with previous observations. Five stations near the Zemuhe and Xiaojiang faults show a nearly 90° flip in the fast direction during the transition from low to high water storage in the Baihetan plant. Future improvement of this real-time SWS system is to narrow down the analysis with only repeating earthquakes or earthquake clusters, which is anticipated to better facilitate time-lapse seismic monitoring of anisotropic structures and stress changes in the upper crust. © Seismological Society of America.

关键词： Shear waves

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Effect of desorbed gas on microwave breakdown on vacuum side of dielectric window

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Plasma science and technology 2024年第4期26卷 85-93页

作者：赵朋程刘忠玉王瑞舒盼盼郭立新曹祥鑫 School of Physics Xidian UniversityXi’an 710071People’s Republic of China National Key Laboratory of Science and Technology on Space Microwave Xi’an Institute of Space Radio TechnologyXi’an 710100People’s Republic of China School of Sciences Xi’an University of TechnologyXi’an 710054People’s Republic of China

The gas desorbed from the dielectric surface has a great influence on the characteristics of microwave breakdown on the vacuum side of the dielectric window. In this paper, the dielectric surface breakdown is described by using the electromagnetic particle-in-cell-Monte Carlo collision(PIC-MCC) model. The process of desorption of gas and its influence on the breakdown characteristics are studied. The simulation results show that, due to the accumulation of desorbed gas, the pressure near the dielectric surface increases in time, and the breakdown mechanism transitions from secondary electron multipactor to collision ionization. More and more electrons generated by collision ionization drift to the dielectric surface, so that the amplitude of self-organized normal electric field increases in time and sometimes points to the dielectric surface. Nevertheless, the number of secondary electrons emitted in each microwave cycle is approximately equal to the number of primary electrons. In the early and middle stages of breakdown, the attenuation of the microwave electric field near the dielectric surface is very small. However, the collision ionization causes a sharp increase in the number density of electrons,and the microwave electric field decays rapidly in the later stage of breakdown. Compared with the electromagnetic PIC-MCC simulation results, the mean energy and number of electrons obtained by the electrostatic PIC-MCC model are overestimated in the later stage of breakdown because it does not take into account the attenuation of microwave electric field. The pressure of the desorbed gas predicted by the electromagnetic PIC-MCC model is close to the measured value,when the number of gas atoms desorbed by an incident electron is taken as 0.4.

关键词： electron multipactor collision ionization desorbed gas electromagnetic particle-in-cell-Monte Carlo collision model

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Computational temporal ghost imaging based on complementary modulation

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Chinese physics B 2024年第11期33卷 278-283页

作者： Jia-Wei Li Wei Zhang Xue-Feng Liu Xu-Ri Yao Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE) School of Physics Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Electronics and Information Technology for Space Systems National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

We report an experimental demonstration of temporal ghost imaging in which a digital micromirror device(DMD)and+1/-1 binary modulation have been combined to give an accurate reconstruction of a nonperiodic time *** to the 0/1 modulation,the reconstruction signal can be improved greatly by+1/-1 binary modulation even with half of the *** results show that 0/1 binary temporal objects up to 4 kHz and sinusoidal time objects up to 1 kHz can be reconstructed by this *** influences of modulation speed and array detector gray levels are also discussed.

关键词： temporal ghost imaging complementary modulation

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Mixing and combustion characteristics in a scramjet combustor with different distances between cavity and backward-facing step

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Chinese Journal of Aeronautics 2023年第7期36卷 400-411页

作者： Mingjiang LIU Mingbo SUN Daoning YANG Guoyan ZHAO Tao TANG Bin AN Hongbo WANG Science and Technology on Scramjet Laboratory National University of Defense TechnologyChangsha 410073China Department of Aerospace Science and Technology Space Engineering UniversityBeijing 101416China

The mixing and combustion characteristics in a cavity flameholding combustor under inlet Mach number 2.92 are numerically investigated with ethylene *** distance is defined as the ratio of the actual distance to the height of the combustor *** cavity shear-layer mode,the lifted cavity shear-layer mode,and jet wake mode with upstream separation are observed respectively with dimensionless distance equals to 1.5,4.5,and *** both non-reacting and reacting flow fields,the numerical results are essentially in agreement with the schlieren photography,flame chemiluminescence images,and wall pressure,which verify the reliability of the numerical *** results of non-reacting flow fields show that the BackwardFacing Step(BFS)can promote the flow separation downstream at a fixed *** more forward the separation position is,the larger the separation zone is in the non-reacting flow ***,the larger the separation zone is,the higher the intensity of combustion in the reacting flow field is.A reasonable distance can reduce the total pressure loss generated by the shock waves in the *** flame presents remarkable three-dimensional characteristics in the reacting flow *** dimensionless distance equals to 4.5,there are flames near the side wall above the cavity and it is difficult for the flame stabilization in the center of the combustor,while the combustion intensity in the center of the combustor is higher than that near the side wall when dimensionless distance equals to *** the cavity flameholding combustors with a backward-facing step,the higher combustion intensity may bring much total pressure loss to the ***,it is a good choice to achieve better thrust performance when dimensionless distance equals to 4.5 compared to the other two combustors.

关键词： Backward-facing step Cavity Combustion Scramjet combustor Supersonic flow

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The effect of room temperature magnetic field on photoluminescence of Mn:CsPbBr_(3) quantum dots prepared by one-pot method in air

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Nano Research 2025年第4期18卷 561-568页

作者： Mengwei Chen Chenguang Shen Wei Huang Yingping Yang Jie Shen Department of Physics School of Physics and MechanicsWuhan University of TechnologyWuhan 430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing School of Materials Science and EngineeringWuhan University of TechnologyWuhan 430070China

The generation and manipulation of spin-polarized electrons at room temperature are essential for the development of advanced spin-optoelectronic *** this work,a one-pot method was used to successfully synthesize homogenous Mn:CsPbBr_(3) perovskite quantum dots in air with particle sizes of 7−8 *** effects of Mn doping on the structure,optical and magnetic properties of CsPbBr_(3) quantum dots were *** findings demonstrated proper Mn doping improved the crystallinity and photoluminescence(PL)of quantum *** prepared quantum dots have a narrow full width at half maximum emission(FWHM)of about 17−20 *** magnetic properties of the doped samples and the effect of the magnetic field on the PL spectra properties were *** results show that trace Mn doping can improve the room-temperature ferromagnetism of CsPbBr_(3) quantum *** with magnetic elements makes CsPbBr_(3) quantum dots more responsive to the applied magnetic *** at a lower 50 mT magnetic field,the PL peak of Mn:CsPbBr_(3) still declined 5.91%.Mn:CsPbBr_(3) quantum dots are a new type of multifunctional material that is beneficial to spintronics *** work demonstrates a low-cost synthesis *** should make all-inorganic perovskite quantum dots a promising material for room-temperature spin optoelectronic devices.

关键词： CsPbBr_(3)quantum dots Mn doping one-pot method ferromagnetism magnetic field

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Comparison of Simulated Backgrounds with In-orbit Observations for HXI Onboard ASO-S

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Research in Astronomy and Astrophysics 2025年第3期25卷 144-156页

作者： Hao-Xiang Wang Zhe Zhang Wei Liu Xian-Kai Jiang Deng-Yi Chen Yi-Ming Hu Yang Su Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences School of Astronomy and Space Science University of Science and Technology of China

The Hard X-ray Imager (HXI) payload,a component of China’s Advanced space-based Solar Observatory satellite,is designed to observe solar X-ray emissions in the 30–200 keV range,with the aim of investigating nonthermal physical processes during solar *** launch,Geant4 simulations were employed to assess the onorbit background of the HXI instrument,evaluating its performance and potential to achieve its scientific *** study addresses issues identified in previous simulations and conducts further analyses to examine the distribution of background counts across the 99 *** results demonstrate alignment between simulations and observations at low and medium geomagnetic latitudes;however,challenges persist at high geomagnetic latitudes due to limitations in the current albedo photon *** investigation provides insights into background sources from various particles,enhances understanding of space background characteristics,and offers guidance for background subtraction in imaging processes.

关键词： (cosmology:) cosmic background radiation gamma-rays: diffuse background instrumentation: detectors Sun: X-rays, gamma-rays

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Study on the local time asymmetry of the Earth's ring currents based on multiple low-Earth-orbit satellite magnetic observations

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science China(Technological sciences) 2024年第11期67卷 3354-3364页

作者： OU JiaMing JIANG Yi YAN Qing State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China Macao Institute of Space Technology and Application Macao 999078China Zhuhai MUST Science and Technology Research Institute Macao University of Science and TechnologyZhuhai 519085China

The azimuthal morphology of Earth's ring currents has consistently shown asymmetry during extreme space weather events at low latitudes,particularly during geomagnetic storms.A dawn-dusk pattern has been detected during the storm main phase through near-Earth and in-situ magnetic *** asymmetry is believed to arise from asymmetric solar windmagnetosphere coupling and is linked to the closure of the ring *** evidence has confirmed the existence of asymmetric ring currents during quiet times and the storm recovery *** phenomenon may be closely related to the evolution of ring currents,including plasma injection and decay *** this study,the local time asymmetry of the ring current is estimated using data from low-Earth-orbit Swarm and Macao science Satellite-1(MSS-1)*** harmonics models are developed to quantify the magnetic field of ring currents through external Gauss coefficients during both quiet periods and the storm recovery *** features of dawn-dusk asymmetry are observed in various cases in different months.(1)The maximum difference in magnetic value across local time ranges from 3 to 10 nT,showing relative invariance compared with various Sym-H levels.(2)Stronger magnetic signals are detected at the premidnight sector during quiet times and at the afternoon sector during the storm recovery phase.(3)Magnetic perturbations remain at a lower level during the postmidnight and morning *** the pattern of local time asymmetry differs between quiet times and the recovery phase,dawn-dusk asymmetry remains the most pronounced feature,affecting the trapping and loss of charged particles in the inner *** Swarm and MSS-1 magnetic observations can enable convenient monitoring of the detailed azimuthal local time effects of the ring current at various disturbance levels in the future.

关键词： Earth's ring currents local time asymmetry SHA model Macao science Satellite-1

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