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Investigation of short-channel design on performance optimization effect of Hall thruster with large height–radius ratio

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Plasma Science and Technology 2022年第2期24卷 1-9页

作者： Haotian FAN Yongjie DING Chunjin MO Liqiu WEI Hong LI Daren YU Plasma propulsion lab Institute of Advanced PowerHarbin Institute of TechnologyHarbin 150001People's Republic of China Key laboratory of Aerospace Plasma propulsion Ministry of Industry and Information TechnologyHarbin 150001People's Republic of China

In this study,the neutral gas distribution and steady-state discharge under different discharge channel lengths were studied via numerical *** results show that the channel with a length of 22 mm has the advantage of comprehensive discharge *** this time,the magnetic field intensity at the anode surface is 10%of the peak magnetic field *** analysis shows that the high-gas-density zone moves outward due to the shortening of the channel length,which optimizes the matching between the gas flow field and the magnetic field,and thus increases the ionization *** outward movement of the main ionization zone also reduces the ion loss on the wall ***,the propellant utilization efficiency can reach a maximum of 96.8%.Moreover,the plasma potential in the main ionization zone will decrease with the shortening of the *** excessively short-channel will greatly reduce the voltage utilization *** thrust is reduced to a minimum of 46.1 m ***,because the anode surface is excessively close to the main ionization zone,the discharge reliability is also difficult to *** was proved that the performance of Hall thrusters can be optimized by shortening the discharge channel appropriately,and the specific design scheme of short-channel of HEP-1350 PM was defined,which serves as a reference for the optimization design of Hall thruster with large height–radius *** shortchannel design also helps to reduce the thruster axial dimension,further consolidating the advantages of lightweight and large thrust-to-weight ratio of the Hall thruster with large height–radius ratio.

关键词： Hall thruster large height-radius ratio short-channel design discharge performance numerical simulation

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An efficient regulation approach for tomographic reconstruction in combustion diagnostics based on TDLAS method

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Chinese Journal of Aeronautics 2020年第12期33卷 3158-3166页

作者： Mingyuan XIN Junling SONG Wei RAO Yanji HONG Yajing JIANG State Key laboratory of Laser propulsion&Application Space Engineering UniversityBeijing 101416China

For tomographic reconstruction in combustion diagnostics,it is usually necessary to solve a rank-deficient problem,where the number of non-linear dependent equations is smaller than the number of *** some reconstructions,there are grids without rays passing *** produces artifacts during the *** this paper,the weight of the regulation equation is modified with the number of the rays crossing the grid *** effect of the neighboring grid values as well as the number of rays crossing the grid cells is considered in the new regulation *** simulation results show that the new regulation method suppresses the reconstruction error of the no rays crossing grid and successfully restrains the corner distortion in four projection *** effects of the weight coefficient and the smoothing factor on the reconstruction are examined through a numerical ***,a combustion experiment demonstrates that the new regulation method can significantly reduce the reconstructed error,especially for the nonray crossing condition,and the results are compared with thermocouple measurements and reconstructions without modified regulation.

关键词： Absorption spectroscopy Combustion Number of rays Regulation function Tomographic reconstruction

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Development of a novel signal restoration algorithm to eliminate the distorted components in space charge measurement excited by femtosecond laser irradiation

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HIGH VOLTAGE 2024年第3期9卷 659-673页

作者： Qi, Tianrun Ren, Hanwen Gao, Haoyu Li, Qingmin Ma, Yidan Ma, Yiqun Xiao, Tao North China Elect Power Univ State Key Lab Alternate Elect Power Syst Renewable Beijing Peoples R China North China Elect Power Univ State Key Lab Alternate Elect Power Syst Renewable Beijing 102206 Peoples R China

For the space charge measurement method with optical excitation for electrical insulation, the distortion of the excitation laser on the measurement signal and the accumulation of space charge have not been discussed before. Both experiment and simulation results show that three types of distorted components introduced by optical excitation can lead to distortion of the upper interface signal. Further, the factors causing distortion of the measured signal and the formation mechanism are analysed. A virtual electrode potential compensation method and a distorted component extraction method are proposed. Meanwhile, an attenuation restoration and charge conversion correction factor is introduced, leading to a novel signal processing algorithm adapted to space charge optical measurement methods. Compared with the traditional algorithm, the novel algorithm has an error of less than 1% in the calculation of charge and electric field strength, with an increase in accuracy of 47.7% and 9.81%, respectively. By applying the novel restoration algorithm, the comparison shows that the space charge accumulation does not change significantly under laser irradiation, verifying the reliability of the optical excitation. The given algorithm can provide a theoretical and technical foundation for the realisation of the optical measurement method for space charge.

关键词： ULTRASOUND DECONVOLUTION DISTRIBUTIONS VOLTAGE WAVES

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Magnet stage optimization of 5 kW multi-cusped field thruster

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Plasma Science and Technology 2020年第9期22卷 128-138页

作者： Peng HU Daren YU Yan SHEN Beijing Institute of Control Engineering Beijing 100094People's Republic of China lab of advanced space propulsion Beijing 100094People’s Republic of China Beijing Engineering Research Center of Efficient and Green Aerospace propulsion Technology Beijing 100094People’s Republic of China Plasma propulsion laboratory of Harbin Institute of Technology Harbin 150001People's Republic of China School of Aeronautics and Astronautics Sun Yat-sen UniversityGuangzhou 510006People's Republic of China

The multi-cusped field thruster is a unique electric thruster device,which has many advantages such as long lifetime,large-range thrust throttling ability,high thrust density,and low *** thruster employs several alternating polarity permanent magnets to create a periodic magnetic field with several *** studies have indicated that the basic ionization and acceleration processes are directly related to the electron motion behavior,which mainly depends on the magnetic field *** magnet number and magnet stage length are two key magnetic field parameters that have important effects on the thruster *** this paper,both the magnet number and magnet stage length parameters are studied for the optimization of a 5 k W multi-cusped field *** results indicate that the three-stage thruster has a better electron confinement than the two-stage *** has lower ion energy loss at the wall,and shows a higher ionization ***,the three-stage magnetic field is a superior magnetic field ***,the three-stage magnetic field simulation results indicate that an optimal accelerating electric field distribution and ionization region distribution could be obtained when the magnet length ratio is 78:25:20.

关键词： multi-cusped field magnet number magnet length performance optimization

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A hybrid memory architecture supporting fine-grained data migration

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Frontiers of Computer Science 2024年第2期18卷 31-41页

作者： Ye CHI Jianhui YUE Xiaofei LIAO Haikun LIU Hai JIN National Engineering Research Center for Big Data Technology and System Services Computing Technology and System LabCluster and Grid Computing LabSchool of Computer Science and TechnologyHuazhong University of Science and TechnologyWuhan 430074China Department of Computer Science Michigan Technological UniversityMichigan 49931USA

Hybrid memory systems composed of dynamic random access memory(DRAM)and Non-volatile memory(NVM)often exploit page migration technologies to fully take the advantages of different memory *** previous proposals usually migrate data at a granularity of 4 KB pages,and thus waste memory bandwidth and DRAM *** this paper,we propose Mocha,a non-hierarchical architecture that organizes DRAM and NVM in a flat address space physically,but manages them in a cache/memory *** the commercial NVM device-Intel Optane DC Persistent Memory Modules(DCPMM)actually access the physical media at a granularity of 256 bytes(an Optane block),we manage the DRAM cache at the 256-byte size to adapt to this feature of *** design not only enables fine-grained data migration and management for the DRAM cache,but also avoids write amplification for Intel Optane *** also create an Indirect Address Cache(IAC)in Hybrid Memory Controller(HMC)and propose a reverse address mapping table in the DRAM to speed up address translation and cache ***,we exploit a utility-based caching mechanism to filter cold blocks in the NVM,and further improve the efficiency of the DRAM *** implement Mocha in an architectural *** results show that Mocha can improve application performance by 8.2%on average(up to 24.6%),reduce 6.9%energy consumption and 25.9%data migration traffic on average,compared with a typical hybrid memory architecture-HSCC.

关键词： non-volatile memory hybrid memory system data migration fine-grained caching

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Practical compensation for nonlinear dynamic thrust measurement system

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Chinese Journal of Aeronautics 2015年第2期28卷 418-426页

作者： Chen Lin Chen Jie Li Jianxun Department of Automation Shanghai Jiao Tong University Shanghai Institute of space propulsion Shanghai Academy of spaceflight Technology

The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network （RBF-NN）, where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical compensation method for the measurement system using left inverse model is proposed. Left inverse model can be considered as a perfect dynamic compensation of the dynamic thrust measurement system, and in practice, it can be approximated by RBF-NN based on least mean square （LMS） algorithms. Different weights are set for producing the multi-step force, which is the ideal input signal of the nonlinear dynamic thrust measurement system. The validity of the compensation method depends on the engine＇s performance and the tolerance error 0.5%, which is commonly demanded in engineering. Results from simulations and experiments show that the practical compensation using left inverse model based on RBF-NN in dynamic thrust measuring system can yield high tracking accuracy than the conventional methods.

关键词： Digital compensation Dynamic thrust measure-ment system Identification Left inverse model Nonlinear model Radial basis function neuralnetwork

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BSN:Photometric Light Curve Analysis of Two Contact Binary Systems LS Del and V997 Cyg

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Research in Astronomy and Astrophysics 2024年第4期24卷 192-213页

作者： Atila Poro Mehmet Tanriver Elham Sarvari Shayan Zavvarei Hossein Azarara Laurent Corp Sabrina Baudart Asma Ababafi Nazanin Kahali Poor Fariba Zare Ahmet Bulut Ahmet Keskin Astronomy Department of the Raderon AI lab. BurnabyBC.Canada Department of Astronomy and space Science Faculty of ScienceErciyes UniversityKayseri TR-38039Turkiye Erciyes University Astronomy and Space Science Observatory Application and Research CenterKayseri TR-38039Turkiye Independent Astrophysics Researcher TehranIran Department of Physics Shahid Beheshti UniversityTehranIran Faculty of Physics Shahid Bahonar University of KermanP.O.Box 76175KermanIran Double Stars Committee SociétéAstronomique de FranceParisFrance Dez Astronomical Association Khouzestan ProvinceDezfulIran Department of Physics Amirkabir University of TechnologyTehranIran Department of Physics Faculty of SciencesCanakkale Onsekiz Mart UniversityTerzioglu KampusuTR-17020CanakkaleTurkiye Astrophysics Research Center and Observatory Canakkale Onsekiz Mart UniversityTerzioğlu KampusuTR-17020CanakkaleTürkiye

The light curve analyses and orbital period variations for two contact binary stars,LS Del and V997 Cyg,are presented in this work which was conducted in the frame of the Binary Systems of South and North project Ground-based photometric observations were performed at two observatories in *** used the Transiting Exoplanet Survey Satellite(TESS)data for extracting times of minima and light curve analysis of the targe *** O-C diagram for both systems displays a parabolic *** Del and V997 Cyg’s orbital periods are increasing at rates of dP/dt=7.20×10^(-08)days yr^(-1)and dP/dt=2.54×10^(-08)days yr^(-1),respectively Therefore,it can be concluded that mass is being transferred from the less massive star to the more massive component with a rate of dM/dt=-1.96×10^(-7)M_(⊙)yr^(-1)for the LS Del system,and dM/dt=-3.83×10^(-7)M_(⊙)yr-1for V997 *** parameters of a third possible object in the system are also *** PHysics Of Eclipsing BinariEs Python code was used to analyze the light *** light curve solutions needed a cold starspot due to the asymmetry in the LS Del system’s light curve *** mass ratio fill-out factor,and star temperature all indicate that both systems are contact binary types in this *** methods were applied to estimate the absolute parameters of the systems:one method relied on the parallax of Gaia DR3,and the other used a P-M *** positions of the systems are also depicted on the M-L,M-R q-L_(ratio),and logM_(tot)-logJ_(0)*** recommend that further observations and investigations be done on the existence of a fourth body in this system.

关键词： (stars:)binaries:eclipsing methods:observational stars:individual(LS Del and V997 Cyg)

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Burning rate analysis of laser controlled 5-aminotetrazole propellant

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Defence Technology（防务技术） 2023年第4期22卷 10-27页

作者： Nianbai He Ruiqi Shen Luigi T.DeLuca Lizhi Wu Wei Zhang Yinghua Ye School of Chemical Engineering Nanjing University of Science and Technology210094JiangsuChina Institute of space propulsion Nanjing University of Science and Technology210094JiangsuChina space propulsion laboratory(Ret) Department of Aerospace Science and TechnologyPolitecnico di Milano20156MilanItaly

As an innovative propulsion technique, laser augmented chemical propulsion(LACP) seems superior to the traditional ones. However, the corresponding combustion theories have still to be ascertained for LACP. Burning rate of 5-aminotetrazole(5-ATZ) propellant has been studied by testing pressed samples under different combustor pressures and laser powers. Based on micro computed tomography(Micro CT),an advanced thickness-over-time(TOT) method to characterize the regression of the produced nonplanar burning surface is established. Because of a shell structure covering the combustion surface,the burning rate of the implemented 5-ATZ propellant is not constant during laser ablation. Resorting to functional fitting, a new law of non-constant burning including the effect of the observed unique burning surface structures is proposed. Accordingly, applicable combustion conditions of 5-ATZ based propellants have been preliminarily speculated for future research activities.

关键词： 5-Aminotetrazole(5-ATZ) Laser-augmented chemical propulsion(LACP) Non-constant burning rate Micro computed tomography(MicroCT) Non-planar burning surface

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Influence of heating on the discharge characteristics of a hollow cathode

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Plasma Science and Technology 2020年第1期22卷 15-23页

作者： Yanlin HU Zhongxi NING Xiaoyu LIU Yanfeng CHU Wei MAO Yan SHEN Ximing ZHU Beijing Institute of Control Engineering Beijing 100080People's Republic of China Plasma propulsion lab Institute of Advanced PowerHarbin Institute of TechnologyHarbin 150001People's Republic of China

Hollow cathodes are widely used as electron sources and neutralizers in ion and Hall electric *** applications such as commercial aerospace and gravitational wave detection require hollow cathodes with a very wide discharge current *** this paper,a heater is used to compensate for the temperature drop of the emitter at low *** self-sustained current can be extended from 0.6 to 0.1 A with a small discharge oscillation and ion energy when the flow rate is *** is also beneficial for long-life ***,when the discharge current is high(>1 A),heating can cause discharge oscillation,discharge voltage and ion energy to increase,f urther,combined with a rapid decline of pressure inside the cathode and an increase in the temperature in the cathode orifice plate,electron emission in die orifice and outside the orifice increases and the plasma density in the orifice *** leads to a change in the cathode discharge mode.

关键词： electric propulsion hollow cathode discharge oscillation heater extended operation range

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Interaction between plasma and electromagnetic field in ion source of 10 cm ECR ion thruster

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Chinese Physics B 2022年第7期31卷 404-412页

作者： Hao Mou Yi-Zhou Jin Juan Yang Xu Xia Yu-Liang Fu College of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Shanghai Institute of space Electric propulsion Shanghai 200000China

Through diagnosing the plasma density and calculating the intensity of microwave electric field,four 10 cm electron cyclotron resonance(ECR)ion sources with different magnetic field structures are studied to reveal the inside interaction between the plasma,magnetic field and microwave electric *** the diagnosing result it can be found that the plasma density distribution is controlled by the plasma generation and electron loss volumes associated with the magnetic field and microwave power *** on the cold plasma hypothesis and diagnosing result,the microwave electric field intensity distribution in the plasma is *** result shows that the plasma will significantly change the distribution of the microwave electric field intensity to form a bow *** the boundary region of the shape to the center,the electric field intensity varies from higher to lower and the diagnosed density inversely *** the bow and its inside lower electric field intensity region are close to the screen grid,the performance of ion beam extracting will be *** study can provide useful information for the creating of 10 cm ECR ion source and understanding its mechanism.

关键词： electron cyclotron resonance plasma plasma diagnosing ion source

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