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Transition from backward to sideward stimulated Raman scattering with broadband lasers in plasmas

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matter and Radiation at Extremes 2023年第6期8卷 63-73页

作者： X.F.Li S.m.Weng P.Gibbon H.H.ma S.H.Yew z.Liu Y.zhao m.Chen z.m.sheng J.zhang Key Laboratory for Laser Plasmas(moE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Institute for Advanced Simulation Jülich Supercomputing CentreForschungszentrum Jülich52425 JülichGermany Centre for mathematical Plasma Astrophysics Katholieke Universiteit Leuven3000 LeuvenBelgium Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China School of Science Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China

Broadband lasers have been proposed as future drivers of inertial confined fusion(ICF)to enhance the laser-target coupling efficiency via the mitigation of various parametric *** physical mechanisms involved have been explored recently,but are not yet fully ***,stimulated Raman scattering(SRS)as one of the key parametric instabilities is investigated theoretically and numerically for a broadband laser propagating in homogeneous plasma in multidimensional *** linear SRS growth rate is derived as a function of scattering angles for two monochromatic laser beams with a fixed frequency differenceδω.Ifδω/ω_(0)∼1%,withω0 the laser frequency,these two laser beams may be decoupled in stimulating backward SRS while remaining coupled for sideward SRS at the laser intensities typical for ***,side-scattering may dominate over backward SRS for two-color laser *** finding of SRS transition from backward to sideward SRS is then generalized for a broadband laser with a few-percent ***-in-cell simulations demonstrate that with increasing laser bandwidth,the sideward SRS gradually becomes dominant over the backward *** sideward SRS is very efficient in producing harmful hot electrons,attention needs to be paid on this effect if ultra-broadband lasers are considered as next-generation ICF drivers.

关键词： scattering backward Transition

Depolarization of intense laser beams by dynamic plasma density gratings

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高功率激光科学与工程:英文版 2023年第3期11卷 48-56页

作者： Y.X.Wang S.m.Weng P.Li z.C.Shen X.Y.Jiang J.Huang X.L.zhu H.H.ma X.B.zhang X.F.Li z.m.sheng J.zhang Key Laboratory for Laser Plasmas(moE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghaiChina Research Center of Laser Fusion of China Academy of Engineering Physics MianyangChina College of Physics and Electronics Engineering Northwest Normal UniversityLanzhouChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina

As a typical plasma-based optical element that can sustain ultra-high light intensity,plasma density gratings driven by intense laser pulses have been extensively studied for wide ***,we show that the plasma density grating driven by two intersecting driver laser pulses is not only nonuniform in space but also varies over ***,the probe laser pulse that passes through such a dynamic plasma density grating will be depolarized,that is,its polarization becomes spatially and temporally *** importantly,the laser depolarization may spontaneously take place for crossed laser beams if their polarization angles are arranged *** laser depolarization by a dynamic plasma density grating may find application in mitigating parametric instabilities in laser-driven inertial confinement fusion.

关键词： depolarization high-power laser plasma density grating

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mitigating parametric instabilities in plasmas by sunlight-like lasers

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matter and Radiation at Extremes 2021年第5期6卷 54-61页

作者： H.H.ma X.F.Li S.m.Weng S.H.Yew S.Kawata P.Gibbon z.m.sheng J.zhang Key Laboratory for Laser Plasmas(moE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Graduate School of Engineering Utsunomiya UniversityYohtoh 7-1-2Utsunomiya 321-8585Japan Institute for Advanced Simulation J¨ulich Supercomputing CentreForschungszentrum J¨ulich52425 J¨ulichGermany Centre for mathematical Plasma Astrophysics Katholieke Universiteit Leuven3000 LeuvenBelgium SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUnited Kingdom Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

Sunlight-like lasers that have a continuous broad frequency spectrum,random phase spectrum,and random polarization are formulated *** a sunlight-like laser beam consisting of a sequence of temporal speckles,the resonant three-wave coupling that underlies parametric instabilities in laser–plasma interactions can be greatly degraded owing to the limited duration of each speckle and the frequency shift between two adjacent *** wave coupling can be further weakened by the random polarization of such *** simulations demonstrate that the intensity threshold of stimulated Raman scattering in homogeneous plasmas can be doubled by using a sunlight-like laser beam with a relative bandwidth of∼1%as compared with a monochromatic laser ***,the hot-electron generation harmful to inertial confinement fusion can be effectively controlled by using sunlight-like laser *** drivers may be realized in the next generation of broadband lasers by combining two or more broadband beams with independent phase spectra or by applying polarization smoothing to a single broadband beam.

关键词： polarization scattering speckle

Optimization of hole-boring radiation pressure acceleration of ion beams for fusion ignition

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matter and Radiation at Extremes 2018年第1期3卷 28-39页

作者： S.m.Weng z.m.sheng m.murakami m.Chen m.Liu H.C.Wang T.Yuan J.zhang Key Laboratory for Laser Plasmas(moE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUK Institute of Laser Engineering Osaka UniversityOsaka 565-0871Japan

In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact ***,it is still challenging to simultaneously enhance their quality and yield for practical applications such as fast ion ignition of inertial confinement *** with other mechanisms of laser-driven ion acceleration,the hole-boring radiation pressure acceleration has a special advantage in generating high-fluence ion beams suitable for the creation of high energy density state of *** this paper,we present a review on some theoretical and numerical studies of the hole-boring radiation pressure *** we discuss the typical field structure associated with this mechanism,its intrinsic feature of oscillations,and the underling *** we will review some recently proposed schemes to enhance the beam quality and the efficiency in the hole-boring radiation pressure acceleration,such as matching laser intensity profile with target density profile,and using two-ion-species *** on this,we propose an integrated scheme for efficient high-quality hole-boring radiation pressure acceleration,in which the longitudinal density profile of a composite target as well as the laser transverse intensity profile are tailored according to the matching condition.

关键词： Laser-driven ion acceleration Radiation pressure acceleration Fast ignition Inertial confinement fusion High energy density Hole boring

Effects of multiple shapes for steady flow with transformer oil+Fe_(3)O_(4)+TiO_(2) between two stretchable rotating disks

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Applied mathematics and mechanics(English Edition) 2024年第2期45卷 373-388页

作者： m.RAHmAN m.TURKYILmAzOGLU z.mUSHTAQ Department of mathematics Mirpur University of Science and TechnologyMirpur 10250Pakistan Department of mathematics Hacettepe UniversityBeytepeAnkara 06532Turkiye

In this study,we examine the effects of various shapes of nanoparticles in a steady flow of hybrid nanofluids between two stretchable rotating *** steady flow of hybrid nanofluids with transformer oil as the base fluid and Fe_(3)O_(4)+TiO_(2)as the hybrid nanofluid is *** shapes of Fe_(3)O_(4)+TiO_(2)hybrid nanofluids,including sphere,brick,blade,cylinder,and platelet,are *** shape exists in the same volume of a *** leading equations(partial differential equations(PDEs))are transformed to the nonlinear ordinary differential equations(ODEs)with the help of similarity *** system of equations takes the form of ODEs depending on the boundary conditions,whose solutions are computed numerically by the bvp4c mATLAB *** outputs are compared with the previous findings,and an intriguing pattern is discovered,such that the tangential velocity is increased for the rotation parameter,while it is decreased by the stretching values because of the lower *** the reaction rate parameter,the concentration boundary layer becomes shorter,and the activation energy component increases the rate at which mass transfers come to the higher disk but have the opposite effect on the bottom *** ranges of various parameters taken into account are Pr=6.2,Re=2,m=1.0,φ_(1)=φ_(2)=0.03,K=0.5,S=-0.1,Br=0.3,Sc=2.0,α_(1)=0.2,γ=0.1,E_(n)=2.0,and q=1.0,and the rotation factor K is within the range of 0 to 1.

关键词： transformer oil Brinkman number skin friction coefficient double rotating disk Nusselt number Sherwood number

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Proton beams from intense laser-solid interaction:Effects of the target materials

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matter and Radiation at Extremes 2020年第6期5卷 42-47页

作者： Y.X.Geng D.Wu W.Yu z.m.sheng S.Fritzsche Q.Liao m.J.Wu X.H.Xu D.Y.Li W.J.ma H.Y.Lu Y.Y.zhao X.T.He J.E.Chen C.Lin X.Q.Yan Key Laboratory of HEDP of the ministry of Education CAPTand State Key Laboratory of Nuclear Physics and TechnologyPeking UniversityBeijing 100871China Institute for Fusion Theory and Simulation Department of PhysicsZhejiang University310058 HangzhouChina State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics201800 ShanghaiChina SUPA Department of Physics University of StrathclydeGlasgow G40NGUnited Kingdom Key Laboratory for Laser Plasmas(ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Helmholtz Institut-Jena and Friedrich-Schiller-University D-07743 JenaGermany

We report systematic studies of laser-driven proton beams produced with micrometer-thick solid targets made of aluminum and plastic,*** effects of the target materials are found on the total charge,cutoff energy,and beam spot of protons in the experiments,and these are described well by two-dimensional particle-in-cell simulations incorporating intrinsic material *** is found that with a laser intensity of 8×10^(19) W/cm^(2),target normal sheath acceleration is the dominant mechanism for both types of *** a plastic target,the higher charge and cutoff energy of the protons are due to the greater energy coupling efficiencies from the intense laser beams,and the larger divergence angle of the protons is due to the deflection of hot electrons during transport in the *** also find that the energy loss of hot electrons in targets of different thickness has a significant effect on the proton cutoff *** consistent results obtained here further narrow the gap between simulations and experiments.

关键词： properties. intense solid

Fire resistance evaluation through synthetic fire tests and generative adversarial networks

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 587-614页

作者： AybikeÖzyükselÇiftçioğlua m.z.Naser Department of Civil Engineering Manisa Celal Bayar University45140Türkiye School of Civil&Environmental Engineering and Earth Sciences(SCEEES) Clemson UniversityClemsonSC 29631USA Artificial Intelligence Research Institute for Science and Engineering(AIRISE) Clemson UniversityClemsonSC 29631USA

This paper introduces a machine learning approach to address the challenge of limited data resulting from costly and time-consuming fire experiments by enlarging small fire test data sets and predicting the fire resistance of reinforced concrete *** approach begins by creating deep learning models,namely generative adversarial networks and variational autoencoders,to learn the spatial distribution of real fire *** then use these models to generate synthetic tabular samples that closely resemble realistic fire resistance values for reinforced concrete *** generated data are employed to train state-of-the-art machine learning techniques,including Extreme Gradient Boost,Light Gradient Boosting machine,Categorical Boosting Algorithm,Support Vector Regression,Random Forest,Decision Tree,multiple Linear Regression,Polynomial Regression,Support Vector machine,Kernel Support Vector machine,Naive Bayes,and K-Nearest Neighbors,which can predict the fire resistance of the columns through regression and *** learning analyses achieved highly accurate predictions of fire resistance values,outperforming traditional models that relied solely on limited experimental *** study highlights the potential for using machine learning and deep learning analyses to revolutionize the field of structural engineering by improving the accuracy and efficiency of fire resistance evaluations while reducing the reliance on costly and time-consuming experiments.

关键词： deep learning fire resistance generative adversarial networks machine learning

Effects of target pre-heating and expansion on terahertz radiation production from intense laser-solid interactions

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High Power Laser Science and Engineering 2014年第1期2卷 13-17页

作者： X.H.Yuan Y.Fang D.C.Carroll D.A.macLellan F.Du N.Booth m.Burza m.Chen R.J.Gray Y.F.Jin Y.T.Li Y.Liu D.Neely H.Powell G.Scott C.-G.Wahlstrm J.zhang P.mcKenna z.m.sheng Key Laboratory for Laser Plasmas (ministry of Education) and Department of Physics and Astronomy Shanghai Jiao Tong University Beijing National Laboratory of Condensed matter Physics Institute of Physics Chinese Academy of Sciences SUPA Department of Physics University of Strathclyde Central Laser Facility Rutherford Appleton Laboratory Department of Physics Lund University

The first experimental measurements of intense(～7 × 1019 W cm-2) laser-driven terahertz(THz) radiation from a solid target which is preheated by an intense pulse of laser-accelerated protons is reported. The total energy of the THz radiation is found to decrease by approximately a factor of 2 compared to a cold target reference. This is attributed to an increase in the scale length of the preformed plasma, driven by proton heating, at the front surface of the target,where the THz radiation is generated. The results show the importance of controlling the preplasma scale length for THz production.

关键词： target heating terahertz radiation

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Dysregulation of RNA modification systems in clinical populations with neurocognitive disorders

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Neural Regeneration Research 2024年第6期19卷 1256-1261页

作者： Helen m.Knight merve Demirbugen ?z Adriana PerezGrovas-Saltijeral Division of Cells Organisms and Molecular Genetics School of Life Sciences University of Notingham Department of Pharmaceutical Toxicology Faculty of Pharmacy Ankara University

The study of modified RNA known as epitranscriptomics has become increasingly relevant in our understanding of disease-modifying mechanisms. methylation of N6 adenosine(m6A) and C5 cytosine(m5C) bases occur on mRNAs, tRNA, mt-tRNA, and rRNA species as well as non-coding RNAs. With emerging knowledge of RNA binding proteins that act as writer, reader, and eraser effector proteins, comes a new understanding of physiological processes controlled by these systems. Such processes when spatiotemporally disrupted within cellular nanodomains in highly specialized tissues such as the brain, give rise to different forms of disease. In this review, we discuss accumulating evidence that changes in the m6A and m5C methylation systems contribute to neurocognitive disorders. Early studies first identified mutations within FmR1 to cause intellectual disability Fragile X syndromes several years before FmR1 was identified as an m6A RNA reader protein. Subsequently, familial mutations within the m6A writer gene mETTL5, m5C writer genes NSUN2, NSUN3, NSUN5, and NSUN6, as well as THOC2 and THOC6 that form a protein complex with the m5C reader protein ALYREF, were recognized to cause intellectual development disorders. Similarly, differences in expression of the m5C writer and reader effector proteins, NSUN6, NSUN7, and ALYREF in brain tissue are indicated in individuals with Alzheimer’s disease, individuals with a high neuropathological load or have suffered traumatic brain injury. Likewise, an abundance of m6A reader and anti-reader proteins are reported to change across brain regions in Lewy bodies diseases, Alzheimer’s disease, and individuals with high cognitive reserve. m6A-modified RNAs are also reported significantly more abundant in dementia with Lewy bodies brain tissue but significantly reduced in Parkinson’s disease tissue, whilst modified RNAs are misplaced within diseased cells, particularly where synapses are located. In parahippocampal brain tissue, m6A modification is en

关键词： 5-methylcytosine methylation Alzheimer's disease cognitive diseases epitranscriptomics intellectual disability Lewy body diseases N6 adenosine RNA modification