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Combining Effects between LHW and IBW Injections on EAST

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Chinese physics Letters 2012年第8期29卷 188-190页

作者：段文学马志为吴斌 institute for fusion theory and simulation Zhejiang UniversityHangzhou 310027 institute of Plasma physics Chinese Academy of SciencesHefei 230031

The quasilinear combining effects between lower hybrid wave(LHW)and ion Bernstein wave(IBW)injections on current drive profiles are systematically studied based on the MHD equilibrium profiles of the Experimental Advanced Superconducting Tokamak(EAST).The simulation results indicate that the modifications of the distribution function due to IBW injection are nonlocalized in space and can affect the current drive profiles.The lower hybrid current drive efficiency can be either enhanced or reduced depending on the spectrum of the IBW injected into the plasma.In order to achieve stronger driven current,an appropriate IBW spectrum should be chosen for the combination of the LHW and IBW injections.

关键词： spectrum wave stronger

Generation of Electric Field and Net Charge in Hall Reconnection

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Chinese physics Letters 2008年第8期25卷 2934-2937页

作者：马志为冯淑玲 institute of Plasma physics Chinese Academy of Sciences Hefei 230031 institute for fusion theory and simulation Zhejiang University Hangzhou 310027

Generation of Hall electric field and net charge associated initial conditions of plasma density and magnetic field. with magnetic reconnection is studied under different With inclusion of the Hall effects, decoupling of the electron and ion motions leads to the formation of a narrow layer with strong electric field and large net charge density along the separatrix. The asymmetry of the plasma density or magnetic field or both across the current sheet will largely increase the magnitude of the electric field and net charge. The results indicate that the asymmetry of the magnetic field is more effective in producing larger electric field and charge density. The electric field and net charge are always much larger in the low density or/and high magnetic field side than those in the high density or/and low magnetic field side. Both the electric field and net charge density are linearly dependent on the ratios of the plasma density or the square of the magnetic field across the current sheet. For the case with both initial asymmetries of the magnetic field and density, rather large Hall electric field and charge density are generated.

关键词： MAGNETIC RECONNECTION CHALLENGE

A simulation Study of Hall Effect on Double Tearing Modes

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Plasma Science and Technology 2008年第4期10卷 407-411页

作者：张城龙马志为董家齐 institute of Plasma physics Chinese Academy of SciencesHefei 230031China institute of Plasma physics Chinese Academy of SciencesHefei 230031China Institute for Fusion Theory and SimulationZhejiang UniversityHangzhou 310027China institute for fusion theory and simulation Zhejiang UniversityHangzhou 310027China Southwestern Institute of PhysicsChengdu 610041China

A Hall magnetohydrodynamics （MHD） simulation is carried out to study the dynamic process of double tearing mode. The results indicated that the growth rates in the earlier nonlinear and transition phases agree with the previous results. With further development of reconnection, the current sheet thickness is much smaller than the ion inertia length, which leads to a strong influence of the Hall effects. As a result, the reconnection in the late nonlinear phase exhibits an explosive nature with a time scale nearly independent of resistivity. A localized and severely intensified current density is observed and the maximum kinetic energy is over one order of magnitude higher in Hall MHD than that in resistive MHD.

关键词： Hall effect double-tearing mode magnetic reconnection Hall MHD

Research on Driver’s Fatigue Detection Based on Information fusion

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Computers, Materials & Continua 2024年第4期79卷 1039-1061页

作者： Meiyan Zhang Boqi Zhao Jipu Li Qisong Wang Dan Liu Jinwei Sun Jingxiao Liao Harbin institute of Technology School of Instrument Science and EngineeringHarbin150036China department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong Kong100872China

Driving fatigue is a physiological phenomenon that often occurs during driving.After the driver enters a fatigued state,the attentionis lax,the response is slow,and the ability todeal with emergencies is significantly reduced,which can easily cause traffic accidents.Therefore,studying driver fatigue detectionmethods is significant in ensuring safe driving.However,the fatigue state of actual drivers is easily interfered with by the external environment(glasses and light),which leads to many problems,such as weak reliability of fatigue driving detection.Moreover,fatigue is a slow process,first manifested in physiological signals and then reflected in human face images.To improve the accuracy and stability of fatigue detection,this paper proposed a driver fatigue detection method based on image information and physiological information,designed a fatigue driving detection device,built a simulation driving experiment platform,and collected facial as well as physiological information of drivers during driving.Finally,the effectiveness of the fatigue detection method was evaluated.Eye movement feature parameters and physiological signal features of drivers’fatigue levels were extracted.The driver fatigue detection model was trained to classify fatigue and non-fatigue states based on the extracted features.Accuracy rates of the image,electroencephalogram(EEG),and blood oxygen signals were 86%,82%,and 71%,separately.Information fusion theory was presented to facilitate the fatigue detection effect;the fatigue features were fused using multiple kernel learning and typical correlation analysis methods to increase the detection accuracy to 94%.It can be seen that the fatigue driving detectionmethod based onmulti-source feature fusion effectively detected driver fatigue state,and the accuracy rate was higher than that of a single information source.In summary,fatigue drivingmonitoring has broad development prospects and can be used in traffic accident prevention and wearable driver fatigue recognition.

关键词： Driving fatigue information fusion EEG blood oxygen

Free-boundary plasma equilibria with toroidal plasma flows

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Plasma Science and Technology 2022年第3期24卷 61-70页

作者：陈文锦马志为张豪伟张威严龙文 institute for fusion theory and simulation.Zhejiang University Hangzhou 310027People's Republic of China Southwestern institute of physics Chengdu 610225People's Republic of China

Magnetohydrodynamic equilibrium schemes with toroidal plasma flows and scrape-off layer are developed for the'divertor-type'and'limiter-type'free boundaries in the tokamak cylindrical coordinate.With a toroidal plasma flow,the flux functions are considerably different under the isentropic and isothermal assumptions.The effects of the toroidal flow on the magnetic axis shift are investigated.In a high beta plasma,the magnetic shifts due to the toroidal flow are almost the same for both the isentropic and isothermal cases and are about 0.04a_(0)(a_(0)is the minor radius)for M_(0)=0.2(the toroidal Alfvén Mach number on the magnetic axis).In addition,the X-point is slightly shifted upward by 0.0125a_(0).But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M_(0) is usually less than 0.05 in a real tokamak.The effects of the toroidal flow on the plasma parameters are also investigated.The high toroidal flow shifts the plasma outward due to the centrifugal effect.Temperature profiles are noticeable different because the plasma temperature is a flux function in the isothermal case.

关键词： tokamak plasma plasma flow equilibria

Effect of inner-surface roughness of conical target on laser absorption and fast electron generation

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Chinese physics B 2014年第5期23卷 392-396页

作者：王欢曹莉华赵宗清郁明阳谷渝秋贺贤土 Center for Applied physics and Technology Peking University Key Laboratory of High Energy Density physics simulation of the Ministry of Education Peking University institute of Applied physics and Computational Mathematics Laser fusion Research Center China Academy of Engineering Physics institute for fusion theory and simulation Zhejiang University institute for Theoretical physics I Ruhr University

The effect of inner-surface roughness of conical targets on the generation of fast electrons in the laser-cone interaction is investigated using particle-in-cell simulation. It is found that the surface roughness can reduce the fast-electron number （in the energy range E 〉 1 MeV） and energy, as compared to that from a cone with smooth inner wall. A scaling law for the laser reflectivity based on the vacuum-heating model is derived. Both theory and simulation indicate that laser reflection increases with the height-to-width ratio of the periodic inner surface structure and approaches that of a smooth cone as this ratio becomes zero.

关键词： inner-surface roughness of cone target particle-in-cell simulation vacuum-heating model laserreflection

Kinetic micro-instabilities in the presence of impurities in toroidal magnetized plasmas

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Plasma Science and Technology 2018年第9期20卷 50-71页

作者：董家齐 Southwestern institute of physics Chengdu 610041 People's Republic of China institute for fusion theory and simulation Zhejiang University Hangzhou 310027 People's Republic of China

The theoretical and numerical studies on kinetic micro-instabilities,including ion temperature gradient（ITG） driven modes,trapped electron modes（TEMs） in the presence of impurity ions as well as impurity modes（IMs）,induced by impurity density gradient alone,in toroidal magnetized plasmas,such as tokamak and reversed-field pinch（RFP） are reviewed briefly.The basic theory for IMs,the electrostatic instabilities in tokamak and RFP plasmas are discussed.The observations of hybrid and coexistence of the instabilities are categorized systematically.The effects of impurity ions on electromagnetic instabilities such as ITG modes,the kinetic ballooning modes（KBMs） and kinetic shear Alfvén modes induced by impurity ions in tokamak plasmas of finite β（=plasma pressure/magnetic pressure） are analyzed.The interesting topics for future investigation are suggested.

关键词： micro-instabilities ideal and resistive MHD modes gyrofluid and gyrokinetic simulations

Comparison of ELM-Filament Mitigation Between Supersonic Molecular Beam Injection and Pellet Injection on HL-2A

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Plasma Science and Technology 2016年第2期18卷 120-125页

作者：聂林程钧徐红兵黄渊严龙文丁玄同许敏许宇鸿姚良骅冯北滨朱根良刘万东董家齐余德良钟武律高金明陈程远杨青巍段旭如 Key Laboratory of Basic Plasma physics and department of Modern physics University of Science and Technology of China Hefei 230026 China Southwestern institute of physics Chengdu 610041 China institute for fusion theory and simulation Zhejiang University Hangzhou 310027 China

On HL-2A,two different injections（supersonic molecular beam injection（SMBI）and pellet injection（PI）） are used to mitigate edge localized mode（ELM）-filament convective transport.The changes of their characteristics are studied in this paper.A high spatiotemporal resolution probe shows there are many similar phenomena,and the filament density amplitude and radial velocity are both suppressed.Our statistical results indicate that：the velocity suppression comes from the decrease of filament density and temperature;the transient particle and heat fluxes drop strongly;and long-range correlation along a magnetic flux surface also decreases,when the electron-ion collisionality increases significantly,which may have a role on the filament parallel current during ELM mitigation.

关键词： ELM-filament SMBI pellet injection convective transport electron-ion collisionality long-range correlation

Experimental quantum simulation of a topologically protected Hadamard gate via braiding Fibonacci anyons

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The Innovation 2023年第5期4卷 41-46页

作者： Yu-ang Fan Yingcheng Li Yuting Hu Yishan Li Xinyue Long Hongfeng Liu Xiaodong Yang Xinfang Nie Jun Li Tao Xin Dawei Lu Yidun Wan Shenzhen institute for Quantum Science and Engineering and department of physics Southem University of Science and Technology Shenzhen 518055China State Key Laboratory of Surface physics Department of PhysicsCenter for Field Theory and Particle Physicsand Institute for Nanoelectronic Devices and Quantum ComputingFudan UniversityShanghai 200433and Shanghai Qi Zhi InstituteShanghai 200030China School of physics Hangzhou Normal UniversityHangzhou 311121China

Topological quantum computation(TQC)is one of the most striking architectures that can realize fault-tolerant quantum computers.In TQC,the logical space and the quantum gates are topologically protected,i.e.,robust against local disturbances.The topological protection,however,requires complicated lattice models and hard-to-manipulate dynamics;even the simplest system that can realize universal TQC-the Fibonacci anyon system—lacks a physical realization,let alone braiding the non-Abelian anyons.Here,we propose a disk model that can simulate the Fibonacci anyon system and construct the topologically protected logical spaces with the Fibonacci anyons.Via braiding the Fibonacci anyons,we can implement universal quantum gates on the logical space.Our disk model merely requires two physical qubits to realize three Fibonacci anyons at the boundary.By 15 sequential braiding operations,we construct a topologically protected Hadamard gate,which is to date the least-resource requirement for TQC.To showcase,we implement a topological Hadamard gate with two nuclear spin qubits,which reaches 97.18%fidelity by randomized benchmarking.We further prove by experiment that the logical space and Hadamard gate are topologically protected:local disturbances due to thermal fluctuations result in a global phase only.As a platform-independent proposal,our work is a proof of principle of TQC and paves the way toward fault-tolerant quantum computation.

关键词： Fibonacci Hadamard TQC