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Suppression of stimulated Brillouin and Raman scatterings using an alternating frequency laser and transverse magnetic fields

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Chinese physics B 2024年第1期33卷 545-553页

作者：程瑞锦李晓旬王清刘德基黄卓明吕帅宇周远志张舒童李雪铭陈祖杰王强刘占军曹莉华郑春阳 Institute of Applied Physics and Computational Mathematics Beijing 100094China HEDPS Center for Applied Physics and Technologyand State Key Laboratory of Nuclear Physics and TechnologySchool of PhysicsPeking UniversityBeijing 100871China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

A novel scheme to suppress both stimulated Brillouin scattering(SBS) and stimulated Raman scattering(SRS) by combining an alternating frequency(AF) laser and a transverse magnetic field is proposed. The AF laser allows the laser frequency to change discretely and alternately over time. The suppression of SBS is significant as long as the AF difference is greater than the linear growth rate of SBS or the alternating time of the laser frequency is shorter than the linear growth time of SBS. However, the AF laser proves ineffective in suppressing SRS, which usually has a much higher linear growth rate than SBS. To remedy that, a transverse magnetic field is included to suppress the SRS instability. The electrons trapped in the electron plasma waves(EPWs) of SRS can be accelerated by the surfatron mechanism in a transverse magnetic field and eventually detrapped. While continuously extracting energy from EPWs, the EPWs are dissipated and the kinetic inflation of SRS is suppressed. The one-dimensional particle-in-cell simulation results show that both SBS and SRS can be effectively suppressed by combining the AF laser with a transverse magnetic field with tens of Tesla. The total reflectivity can be dramatically reduced by more than one order of magnitude. These results provide a potential reference for controlling SBS and SRS under the related parameters of inertial confinement fusion.

关键词： stimulated Brillouin scattering stimulated Raman scattering alternating frequency laser transverse magnetic field

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A Composite Ansatz for Calculation of Dynamical Structure Factor

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Chinese physics Letters 2024年第1期41卷 92-103页

作者：张玉佩莫崇杰张平康炜 HEDPS Center for Applied Physics and Technologyand School of PhysicsPeking UniversityBeijing 100871China Beijing Computational Science Research Center Beijing 100193China Institute of Applied Physics and Computational Mathematics Beijing 100088China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

We propose an ansatz without adjustable parameters for the calculation of a dynamical structure *** ansatz combines the quasi-particle Green’s function,especially the contribution from the renormalization factor,and the exchange-correlation kernel from time-dependent density functional theory together,verified for typical metals and semiconductors from a plasmon excitation regime to the Compton scattering *** has the capability to reconcile both small-angle and large-angle inelastic x-ray scattering(IXS)signals with muchimproved accuracy,which can be used as the theoretical base model,in inversely inferring electronic structures of condensed matter from IXS experimental signals *** may also be used to diagnose thermal parameters,such as temperature and density,of dense plasmas in x-ray Thomson scattering experiments.

关键词： excitation inverse verified

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Deformation and mutual influence of two cylindrical water columns in tandem subjected to shock wave

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Chinese physics B 2024年第8期33卷 316-327页

作者：洪振宇宋洋王睿马宗强马东军王裴 Institute of Applied Physics and Computational Mathematics Beijing 100094China Graduate School of China Academy of Engineering Physics Beijing 100088China Center for Applied Physics and Technology Peking UniversityBeijing 100871China

The interaction between shock waves and multiple cylinders,referred to as shock–cylinder interaction(SCI),is an important phenomenon in science and ***,its underlying physical mechanisms remain *** study entailed the numerical simulation of the aerobreakup of two tandem water columns subjected to a high-speed gas flow by using an adaptive mesh refinement(AMR)-based diffusion-interface *** objective was to elucidate the changes in water–column deformation patterns over a wide range of Weber *** analysis was performed to examine the deformation of the water columns in vertical *** reveal distinct deformation patterns between the two columns as the Weber number ***,an extended exponential stretching law model was devised,and its improved capability to predict the deformation patterns was demonstrated.

关键词： shock-cylinder interaction(SCI) Weber number effect aerobreakup multiphase flow

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Thermal conductivity of iron under the Earth’s inner core pressure

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Chinese physics B 2024年第10期33卷 343-348页

作者： Cui-E Hu Mu-Xin Jiao Xue-Nan Yang Zhao-Yi Zeng Jun Chen College of Physics and Electronic Engineering Chongqing Normal UniversityChongqing 400047China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Center for Applied Physics and Technology Peking UniversityBeijing 100071China

The thermal conductivity ofε-iron at high pressure and high temperature is a key parameter to constrain the dynamics and thermal evolution of the Earth’s *** this work,we use first-principles calculations to study the Hugoniot sound velocity and the thermal transport properties ofε-*** total thermal conductivity considering lattice vibration is 200 W/mK at the Earth’s inner core *** suppressed anharmonic interactions can significantly enhance the lattice thermal conductivity under high pressure,and the contribution of the lattice thermal conductivity should not be ignored under the Earth’s core conditions.

关键词： thermal conductivity first-principles high pressure and high temperature

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A Corrected H_(N)^(T)-UGKS for Boundary Layer Problems of the Gray Radiative Transfer Equations

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Communications on applied Mathematics and Computation 2025年第2期7卷 689-717页

作者： Song Jiang Qi Li Wenjun Sun National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing100094China Center for Applied Physics and Technology College of EngineeringPeking UniversityBeijing100871China

In this paper,the corrected method to the original H_(N)^(T)-unified gas kinetic scheme(H_(N)^(T)-UGKS)is developed in order to solve the nonlinear radiative transfer equations with boundary *** H_(N)^(T)-UGKS is an asymptotic preserving(AP)scheme that uses UGKS for spatial discretization and the hybrid H_(N)^(T)method for angular discretization which is constructed in the paper(Li et *** ***.198(5):993-1020,2024).First,the correction idea in Mieussens(***.253:138-156,2013)is adopted,such that H_(N)^(T)-UGKS can correctly simulate the linear radiative transfer equation with boundary ***,for the nonlinear radiative transfer equations with boundary layers,the transformation from the implicit Monte Carlo(IMC)method is introduced to rewrite the nonlinear transfer equations into a linearized *** is the key point in the construction of the current scheme to use this linearized system to construct the numerical boundary *** this way,the boundary density is included in the numerical fluxes,and consequently,the modification method for the linear radiative transfer equation can be used to deal with the nonlinear problem studied in this paper.A number of numerical examples are presented to demonstrate the accuracy and effectiveness of the current scheme for resolving boundary layers in both linear and nonlinear radiative transfer problems.

关键词： Nonlinear radiative transfer Boundary layer -UGKS Implicit Monte Carlo(IMC)method

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Vibronic effect study of ^(1)A_(2) state of H_(2)O and D_(2)O

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Chinese physics B 2024年第5期33卷 395-399页

作者：张倍源王礼涵朱剑辉徐卫青马子茹赵小利吴勇朱林繁 Department of Modern Physics University of Science and Technology of ChinaHefei 230026China Center for Transformative Science ShanghaiTech UniversityShanghai 201210China Department of Physics Yantai UniversityYantai 264005China Institute of Applied Physics and Computational Mathematics Beijing 100088China School of Physics and Information Technology Shaanxi Normal UniversityXi'an 710119China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100084China

The generalized oscillator strengths of the dipole-forbidden excitations of the ^(1)A_(2) of H_(2)O and D_(2)O were calculated with the time dependent density functional theory,by taking into account the vibronic *** is found that the vibronic effect converts the dipole-forbidden excitation of the ^(1)A_(2) into a dipole-allowed one,which enhances the intensities of the corresponding generalized oscillator strength in the small squared momentum transfer *** present investigation shows that the vibronic effect of H_(2)O is slightly stronger than that of D_(2)O,which exhibits a clear isotopic effect.

关键词： water heavy water generalized oscillator strength vibronic effect isotope effect

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Using the shadow of a black hole to examine the energy exchange between axion matter and a rotating black hole

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Physical Review D 2024年第6期110卷 L061503页

作者： Xiao-Mei Kuang Yuan Meng Eleftherios Papantonopoulos Xi-Jing Wang Center for Gravitation and Cosmology College of Physical Science and Technology Physics Division School of Applied Mathematical and Physical Sciences Department of Astronomy School of Physics and Technology

We find that a slowly rotating axion-modified black hole resulting from the backreaction of an axion field on a rotating Kerr black hole can have a D-shaped shadow as that for a highly counterrotating Kerr black hole. This is attributed to the fact that the energy exchange between the axion matter and the black hole influences the rotation of the black hole, so the black hole angular momentum first decreases to zero and then starts to rotate to the opposite direction. Further increasing the coupling leads to “human-face-like”-shaped shadows and new lensing due to the chaotic scattering, which are novel and drastically different from those for a Kerr black hole. Our analysis provides the first counterexample to that slowly rotating black hole has nearly circular shadow.

关键词： Alternative gravity theories Classical black holes

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A CELL-centerED GODUNOV METHOD BASED ON STAGGERED DATA DISTRIBUTION,PART Ⅰ:ONE-DIMENSIONAL CASE

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Journal of Computational Mathematics 2024年第4期42卷 1172-1196页

作者： Jiayin Zhai Xiao Li Zhijun Shen Institute of Applied Physics and Computational Mathematics LCPP.O.Box 8009-26Beijing 100088China College of Big Data and Internet Shenzhen Technology UniversityShenzhen 518118China Center for Applied Physics and Technology HEDPSPeking UniversityChina

This paper presents a cell-centered Godunov method based on staggered data distribu-tion in Eulerian *** motivation is to reduce the intrinsic entropy dissipation of classical Godunov methods in the calculation of an isentropic or rarefaction *** the same time,the property of accurate shock capturing is also *** analyzing the factors that cause nonphysical entropy in the conventional Godunov methods,we introduce two velocities rather than a single velocity in a cell to reduce kinetic energy dissipation.A series of redistribution strategies are adopted to update subcell quantities in order to improve *** examples validate that the present method can dramatically reduce nonphysical entropy *** subject classification:35Q35,76N15,76M12.

关键词： Godunov method Riemann solver Rarefaction wave Nonphysical entropy increase.

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Theoretical study of electron-impact broadening for highly charged Ar XV ion lines

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Chinese physics B 2023年第5期32卷 49-56页

作者：吴超高翔朱宇豪韩小英段斌孟举张松斌颜君吴勇王建国 National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100084China School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710119China School of Science Xi’an University of Architecture and TechnologyXi’an 710055China

Spectral line widths produced by collisions between charged particles and emitters are of special interest for precise plasma *** highly charged Ar XV ion is demonstrated to have strong intrashell electron interactions,which manifest as an atomic system with many resonance structures,due to the quasi-degeneracy of orbital *** this paper we use the relativistic R-matrix method to investigate the electron-impact broadening of highly charged Ar XV ion spectral lines under the impact *** is found that the results considering resonance structures are significantly different from those of the distorted wave ***,we propose a new empirical formula with a correction term to take into account the effect of resonances for electron-impact widths over a relatively wide range of plasma *** corresponding fitting parameters of the new empirical formula for all 47 calculated transitions are also given with an estimated accuracy within 1%,which should be convenient for practical *** dataset that supported the findings of this study is available in Science Data Bank,with the link https://***/10.57760/sciencedb.j00113.00101.

关键词： highly charged ions electron-impact broadening empirical formula

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Effect of Central Multiphase Microstructure of Thick Plates on Work Hardening and Crack Propagation

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 325-338页

作者： Lei Hu Liqin Zhang Feng Hu Kuan Zheng Guohong Zhang Collaborative Innovation Center for Advanced Steels Wuhan University of Science and TechnologyWuhan430081China Department of Applied Physics Wuhan University of Science and TechnologyWuhan430081China Analysis and Testing Center Wuhan University of Science and TechnologyWuhan430081China

The effect of multiphase microstructure in the center segregation zones(CSZ)of high-strength steel thick plates on work hardening characteristics and crack initiation/propagation were *** was correlated with deformation damage behavior by using Taylor factor(TF)gradients,kernel average misorientation(KAM),and geometric necessary dislocation(GND)*** results show that the segregation leads to a mixed structure of ferrite(soft phase)and martensite/bainite(hard phase)in the center of the thick *** to the 1/4 thickness(1/4 T)region,grain refinement occurred in the CSZ,with KAM values increasing from 0.24 to 0.49 and a decrease in the proportion of high-angle grain boundaries(>15°)from 77.4 to 51.8%.In the process of deformation,due to the influence of grain refinement and adjacent martensite/bainite,ferrite grains were divided into structural units with different TF *** higher KAM value and GND density at the interface between soft/hard phases resulted in severe work *** addition,the presence of micron-sized inclusions in the CSZ caused local strain concentration and non-continuous deformation of the matrix,which induced crack *** fracture surface showed a mixed mode of brittle cleavage fracture and ductile fracture.

关键词： Thick plate center segregation zone Multiphase microstructure Taylor factor Crack propagation

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