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Motion of charged particles in bright squeezed vacuum

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Light(Science & Applications) 2024年第2期13卷 347-353页

作者： Matan Even Tzur Oren Cohen Solid State Institute and Physics Department Technion-Israel Institute of TechnologyHaifa3200003Israel

The motion of laser-driven electrons quivers with an average energy termed pondermotive *** explore electron dynamics driven by bright squeezed vacuum(BSV),finding that BSV induces width oscillations,akin to electron quivering in laser light,with an equivalent ponderomotive *** identify closed and open trajectories of the electronic width that are associated with high harmonic generation and above-threshold ionization,respectively,similarly to trajectories of the electron position when its motion is driven by coherent *** the case of bound electrons,the width oscillations may lead to ionization with noisy sub-cycle *** results are foundational for strong-field and free-electron quantum optics,as they shed light on ionization,high harmonic generation,and nonlinear Compton scattering in BSV.

关键词： structure vacuum ionization

A fuse-based DC circuit breaker with vacuum interrupter enhanced by an external transverse magnetic field

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High Voltage 2024年第3期9卷 710-720页

作者： Yu Xiao Yi Wu Yifei Wu Fei Yang Mingzhe Rong Zhuo Yang State Key Laboratory of Electrical Insulation and Power Equipment School of Electric EngineeringXi'an Jiaotong UniversityXi'anChina State Grid Shaanxi Electric Power Company Limited Xi'anChina

Due to the increasing power system capacity,the interruption of large fault currents has gradually become a major challenge in power *** the moment,such currents are interrupted mainly via circuit breakers based on the method of active current ***,these types of circuit breakers tend to be costly and *** possible alternative—a fuse-based circuit breaker with current commutation process enhanced by an external transverse magnetic field(ETMF)—is proposed by the *** main advantage lies in the fast current commutation achieved by an ETMF-enhanced three-stage increase of the vacuum arc *** study of the current commutation process is mainly represented by the authors,and the influencing factors of the current commutation—contact opening speed and ETMF current—are *** last,the proposed circuit breaker is verified by an experiment,whose results show that a short-circuit current of 42 kA can be interrupted within just 2 ms.

关键词： vacuum transverse interrupt

Tribological behavior of TiN,AlTiN,and AlTiCrN coatings in atmospheric and vacuum environments

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Friction 2024年第11期12卷 2611-2626页

作者： Youn-Hoo HWANG Kuk-Jin SEO Tae-Hyeong KIM You Jin MIN Yuzhen LIU Dae-Eun KIM Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Mechatronics and Energy Engineering Ningbo Tech UniversityNingbo 315211China

In this study,the tribological characteristics of TiN,AlTiN,and AlTiCrN coatings sliding against a SUS420J1 stainless steel pin were investigated in atmospheric and vacuum *** coatings were deposited on SUS440C substrates using the arc-physical vapor deposition *** friction and wear behavior of the coatings were evaluated based on the systematic analyses of the friction coefficient data as well as the physical and chemical state of the wear *** results revealed that the friction coefficients of the SUS440C specimen and AlTiCrN coatings increased,whereas those of the TiN and AlTiN coatings decreased when the environment was changed from atmospheric to *** was confirmed that the formation of an oxide layer and adsorption of oxides on the surface were dominant factors that influenced the tribological behavior in the atmospheric *** the other hand,the compatibility,oxidation inhibition,and droplets of the surface mainly affected the frictional characteristics in the vacuum *** results of this work are expected to aid in the selection of proper coating materials for tribological systems operating in a vacuum.

关键词： friction wear coating vacuum TiN

Real-Time Observation of Instantaneous ac Stark Shift of a vacuum Using a Zeptosecond Laser Pulse

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Chinese Physics Letters 2024年第1期41卷 11-15页

作者：苏丹丹江淼 Key Laboratory for Laser Plasmas(Ministry of Education)and School of Physics and Astronomy Collaborative Innovation Center for IFSA(CICIFSA)Shanghai Jiao Tong UniversityShanghai 200240China School of Science China University of Mining and TechnologyBeijing 100083China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China

Based on the numerical solution of the time-dependent Dirac equation,we propose a method to observe in real time the ac Stark shift of a vacuum driven by an ultra-intense laser *** overlapping the ultra-intense pump pulse with another zeptosecond probe pulse whose photon energy is smaller than 2mc^(2),electron–positron pair creation can be controlled by tuning the time delay between the pump and probe *** the pair creation rate depends sensitively on the instantaneous vacuum potential,one can reconstruct the ac Stark shift of the vacuum potential according to the time-delay-dependent pair creation rate.

关键词： pump tuning vacuum

INTERFACE BEHAVIOR AND DECAY RATES OF COMPRESSIBLE NAVIER-STOKES SYSTEM WITH DENSITY-DEPENDENT VISCOSITY AND A vacuum

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Acta Mathematica Scientia 2024年第1期44卷 247-274页

作者：郭真华张学耀 School of Mathematics and CNS Northwest UniversityXi’an710127China School of Mathematics and Information Science Guangxi UniversityNanning530004China

In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in *** interface behavior,the pointwise decay rates of the density function and the expanding rates of the interface are obtained with the viscosity coefficientμ(ρ)=ρ^(α)for any 0<α<1;this includes the timeweighted boundedness from below and *** smoothness of the solution is ***,we construct a class of self-similar classical solutions which exhibit some interesting properties,such as optimal *** present paper extends the results in[Luo T,Xin Z P,Yang *** J Math Anal,2000,31(6):1175-1191]to the jump boundary conditions case with density-dependent viscosity.

关键词： decay rates interface Navier-Stokes equations vacuum

vacuum current-carrying tribological behavior of MoS2-Ti films with different conductivities

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Chinese Physics B 2022年第6期31卷 563-571页

作者： Lu-Lu Pei Peng-Fei Ju Li Ji Hong-Xuan Li Xiao-Hong Liu Hui-Di Zhou Jian-Min Chen Key Laboratory of Science and Technology on Wear and Protection of Materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Shanghai Aerospace Equipment Manufacture Shanghai 200245China

Current-carrying sliding is widely applied in aerospace equipment,but it is limited by the poor lubricity of the present materials and the unclear tribological *** study demonstrated the potential of MoS_(2)-based materials with excellent lubricity as space sliding electrical contact materials by doping Ti to improve its *** tribological behavior of MoS_(2)-Ti films under current-carrying sliding in vacuum was studied by establishing a simulation evaluating ***,the noncurrent-carrying sliding and static current-carrying experiments in vacuum were carried out for comparison to understand the tribological *** addition to mechanical wear,the current-induced arc erosion and thermal effect take important roles in accelerating the *** erosion is caused by the accumulation of electric charge,which is related to the conductivity of the *** the current-thermal effect softens the film,causing strong adhesive wear,and good conductivity and the large contact area are beneficial for minimizing the thermal *** the moderate hardness and good conductivity of MoS_(2)-Ti film contribute to its excellent current-carrying tribological behavior in vacuum,showing a significant advantage compared with the traditional ones.

关键词： MoS2-Ti films conductivity current-carrying tribological behavior vacuum

vacuum induced transparency and slow light phenomena in a two-level atomic ensemble controlled by a cavity

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Chinese Physics B 2015年第9期24卷 240-244页

作者：郭玉杰聂文杰 Department of Physics Tsinghua University Beijing Computational Science Research Center Department of Applied Physics East China Jiaotong University

We study the optical properties of a two-level atomic ensemble controlled by a high-finesse cavity. Even though the cavity is initially in the vacuum state in the absence of external driving, the probe response of the atomic ensemble can be dramatically modified. When the collectively enhanced atom–cavity coupling is strong enough and the cavity decay rate is much smaller than the atomic damping rate, an electromagnetically induced transparency-like coherent phenomenon emerges with a dip absorption for the response of the two-level atoms in the cavity without driving, and thus is called vacuum induced transparency. We also show the slow light with very low group velocity in such an atomic ensemble.

关键词： electromagnetically induced transparency two-level atomic ensemble vacuum slow light

vacuum heating of solid target irradiated by femtosecond laser pulses

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Science China(Physics,Mechanics & Astronomy) 2003年第1期46卷 71-77页

作者： DONG Quanli(董全力) ZHANG Jie(张杰) Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

The interaction of femtosecond laser pulses with solid targets was studied through experiments and particle-in-cell (PIC) simulations. It is proved that the vacuum heating and the inverse bremsstralung process are the main mechanisms of the laser pulse absorption under such conditions. The distribution of hot electrons and that of X-ray are found to have double-temperature structure, which is confirmed by PIC simulations. While the lower temperature is attributed to the resonant absorption, the higher one, however, is caused by the laser-induced electric field in the target normal direction. The time-integrated spectra ofthe reflected laser pulse shows that the mechanism of electron acceleration is determined by the plasma density profile.

关键词： vacuum heating, electron acceleration, harmonics.

vacuum promotes metabolic shifts and increases biogenic hydrogen production in dark fermentation systems

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Frontiers of Environmental Science & Engineering 2016年第3期10卷 513-521页

作者： Haifa RAJHI Daniel PUYOL Mirna C. MARTiNEZ Emiliano E. DLAZ Jose L. SANZ Department of Molecular Biology University Autonoma of Madrid Madrid 28049 Spain Section of Chemical Engineering University Autonoma of Madrid Madrid 28049 Spain MYGEN Laboratory Cantoblanco Madrid 28049 Spain

The successful operation of any type of hydrogen-producing bioreactor depends on the performance of the microorganisms present in the system. Both substrate and partial gas pressures are crucial factors affecting dark fermentation metabolic pathways. The main objective of this study was to evaluate the impact of both factors on hydrogen production using anaerobic granular sludge as inoculum and, secondly, to study the metabolic shifts of an anaerobic community subjected to low partial gas pressures. With this goal in mind, seven different wastewater （four synthetic media, two industrial waste- water, and one domestic effluent） and the effect of applying vacuum on the systems were analyzed. The application of vacuum promoted an increase in the diversity of hydrogen-producing bacteria, such as Clostridium, and promoted the dominance of acetoclasticover hydrogenotrophic methanogens. The application of different media promoted a wide variety of metabolic pathways. Nevertheless, reduction of the hydrogen partial pressure by application of vacuum lead to further oxidation of reaction intermediates irrespective of the medium used, which resulted in higher hydrogen and methane production, and improved the COD removal. Interestingly, vacuum greatly promoted biogenic hydrogen production from a real wastewater, which opens possibilities for future application of dark fermentation systems to enhance biohydrogen yields.

关键词： dark fermentation biohydrogen wastewaters vacuum