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Electromagnetic Ion Beam Instability in the Solar Corona

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Research in Astronomy and Astrophysics 2024年第2期24卷 171-179页

作者： Wen liu Jin-Song Zhao De-Jin Wu Huan-Yu Jia si-ming liu School of Mechanics and Aeronautics Southwest Jiaotong UniversityChengdu 610000China School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610000China Key Laboratory of Planetary Sciences Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China

Remote-sensing measurements indicate that heavy ions in the corona undergo an anisotropic and mass-charge dependent energization.A popular explanation to this phenomenon is the damping of the Alfven/ion cyclotron *** this paper,we propose that the ion beam instability can be an important source of the Alfven/ion cyclotron waves,and we study the excitation of the ion beam instability in the corona at the heliocentric distance~3R_(⊙)and the corresponding energy transfer process therein ba sed on plasma kinetic *** results indicate that the existence of the motionless heavy ions inhibits the ion beam ***,the anisotropic beams of heavy ions promote the excitation of the ion beam ***,the existence ofαbeams can provide a second energy source for exciting beam ***,when both the proton beam and the a beam reach the instability excitation threshold,the proton beam driven instability excites ***,the excitation threshold of the Alfven/ion cyclotron instability driven by ion beam is of the local Alfven speed or even less in the corona.

关键词： plasmas-instabilities-waves-Sun corona

Statistical properties of radio flux densities of solar flares

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Research in Astronomy and Astrophysics 2020年第11期20卷 239-251页

作者： Lu Wang si-ming liu Zong-Jun Ning Purple Mountain Observatory Nanjing 210000China Key Laboratory of Dark Matter and Space Astronomy Nanjing 210000China University of Science and Technology of China Heifei 100049China

Short timescale flux variations are closely related to the energy release process of magnetic reconnection during solar *** light curves at 1,2,3.75,9.4,and 17 GHz of 209 flares observed by the Nobeyama Radio Polarimeter from 2000 to 2010 are analyzed with a running smooth *** find that the impulsive component(with a variation timescale shorter than 1 s)of 1 GHz emission of most flares peaks at a few tens of solar flux unit and lasts for about 1 minute and the impulsive component of 2 GHz emission lasts a shorter period and peaks at a lower flux level,while at the three high frequency channels the occurrence frequency of flares increases with the decrease of the flux density up to the noise level of the corresponding ***,the gradual components of these emissions have similar duration and peak flux density *** also derive the power spectrum on different timescales and a normalized wavelet analysis is used to confirm features on short *** a time resolution of 0.1 s,more than^60%of these radio light curves show significant flux variation on 1 s or shorter time *** fraction increases with the decrease of frequency and reaches^100%at 1 GHz,implying that short timescale processes are universal in solar *** also study the correlation between the impulsive radio flux densities and soft X-ray fluxes obtained with the GOES satellites and find that more than 65%of the flares with an impulsive component have their impulsive radio emission reach a peak value ahead of the soft X-ray fluxes and this fraction increases with the radio frequency.

关键词： methods data analysis Sun flares Sun radio radiation

MHD simulations of inward shocks in Cassiopeia A

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Research in Astronomy and Astrophysics 2020年第4期20卷 39-43页

作者： Chu-Yuan Yang Bi-Wen Bao si-ming liu Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210033China

Cassiopeia A,the brightest radio supernova remnant(SNR)in the sky,has several unique characteristics in comparison to its *** its radio brightness and prominent soft-concave radio spectrum,itsγ-ray spectrum appears to have a low-energy cutoff near 2 GeV,and it is the only SNR with prominent hard X-ray *** the unusual radio properties may be attributed to strong emission from reverse shocks,the hard X-ray emission has been associated with high-speed inward shocks induced by high density ***,the low-energyγ-ray spectral cutoff could be attributed to slow penetration of lower energy particles accelerated near the inward shocks into high-density emission *** this paper,we carry out magneto-hydrodynamic(MHD)simulations of shocks in Cassiopeia A and demonstrate that its inward shock structure can indeed be reproduced via shock interactions with clumps of gases with a density of 20 cm-3.

关键词： acceleration of particles supernovae:individual(Cassiopeia A) ISM:supernova remnants X-rays:ISM

On the power-law distributions of X-ray fluxes from solar flares observed with GOES

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Research in Astronomy and Astrophysics 2016年第10期16卷 99-106页

作者： You-Ping Li Li Feng Ping Zhang si-ming liu Wei-Qun Gan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences

The power-law frequency distributions of the peak flux of solar flare X-ray emission have been studied extensively and attributed to a system having self-organized criticality （SOC）. In this paper, we first show that, so long as the shape of the normalized light curve is not correlated with the peak flux, the flux histogram of solar flares also follows a power-law distribution with the same spectral index as the power- law frequency distribution of the peak flux, which may partially explain why power-law distributions are ubiquitous in the Universe. We then show that the spectral indexes of the histograms of soft X-ray fluxes observed by GOES satellites in two different energy channels are different： the higher energy channel has a harder distribution than the lower energy channel, which challenges the universal power-law distribution predicted by SOC models and implies a very soft distribution of thermal energy content of plasmas probed by the GOES satellites. The temperature （T） distribution, on the other hand, approaches a power-law dis- tribution with an index of 2 for high values of T. Hence the application of SOC models to the statistical properties of solar flares needs to be revisited.

关键词： Sun: flares -- Sun: X-rays Gamma rays -- methods: statistical

The breakdown of the power-law frequency distributions for the hard X-ray peak count rates of solar flares

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Research in Astronomy and Astrophysics 2013年第12期13卷 1482-1492页

作者： You-Ping Li Wei-Qun Gan Li Feng si-ming liu A.Struminsky Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences Space Research Institute(IKI) Russian Academy of Science

The frequency distribution for several characteristics of a solar flare obeys a power law only above a certain threshold, below which there is an apparent loss of small scale events presumably caused by limited instrumental sensitivity and th：e corresponding event selection bias. It is also possible that this deviation in the power law can have a physical origin in the source. We propose two fitting models incorpo- rating a power law distribution with a low count rate cutoff plus a noise component for the frequency distribution of the hard X-ray peak count rate of all solar flare sam- ples obtained with HXRBS/SMM and BATSE/CGRO observations. Our new fitting method produces the same power-law index as previously developed methods, a low cutoff of the power-law function and its corresponding noise level, which is consistent with measurements of the actual noise level of the hard X-ray count rate. We found that the fitted low cutoff appears to be related to the noise level, i.e., flares are only recognized when their peak count rate is 3or greater than noise. Therefore, the fitted low cutoff, which is smaller than the aforementioned threshold, might be attributed to selection bias, and probably not to the actual count rate cutoff in flares at smaller scales. Whether or not the actual low cutoff physically exists needs to be checked by future observations with increased sensitivities.

关键词： Sun: flares -- Sun: X-rays gamma-rays -- methods: statistical

Atomically Substitutional Engineering of Transition Metal Dichalcogenide Layers for Enhancing Tailored Properties and Superior Applications

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Nano-Micro Letters 2024年第5期16卷 248-284页

作者： Zhaosu liu si Yin Tee Guijian Guan ming‑Yong Han Institute of Molecular Plus Tianjin UniversityTianjin 300072People’s Republic of China Institute of Materials Research and Engineering A*STARSingapore 138634Singapore

Transition metal dichalcogenides(TMDs)are a promising class of layered materials in the post-graphene era,with extensive research attention due to their diverse alternative elements and fascinating semiconductor *** MX2 layers with different metal and/or chalcogen elements have similar structural parameters but varied optoelectronic properties,providing opportunities for atomically substitutional engineering via partial alteration of metal or/and chalcogenide atoms to produce ternary or quaternary *** resulting multinary TMD layers still maintain structural integrity and homogeneity while achieving tunable(opto)electronic properties across a full range of composition with arbitrary ratios of introduced metal or chalcogen to original counterparts(0–100%).Atomic substitution in TMD layers offers new adjustable degrees of freedom for tailoring crystal phase,band alignment/structure,carrier density,and surface reactive activity,enabling novel and promising *** review comprehensively elaborates on atomically substitutional engineering in TMD layers,including theoretical foundations,synthetic strategies,tailored properties,and superior *** emerging type of ternary TMDs,Janus TMDs,is presented specifically to highlight their typical compounds,fabrication methods,and potential ***,opportunities and challenges for further development of multinary TMDs are envisioned to expedite the evolution of this pivotal field.

关键词： Transition metal dichalcogenides Atomic substitution Tailored structure Tunable bandgap Enhanced applications

Nb_(2)CT_(x)MXene boosting PEO polymer electrolyte for all-solid-state Li-S batteries:two birds with one stone strategy to enhance Li+conductivity and polysulfide adsorptivity

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稀有金属:英文版 2023年第8期42卷 2562-2576页

作者： si-ming liu Meng-Xun Chen Ying Xie Deng-Hua liu Jin-Fei Zheng Xiang Xiong Heng Jiang Li-Chang Wang Heng Luo Kai Han State Key Laboratory for Powder Metallurgy College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China Shinghwa Advanced Material Group Co. LtdDongying 257500China School of Physics and Electronics Central South UniversityChangsha 410083China Department of Chemistry Oregon State UniversityCorvallis OR 97331-4003USA School of Geosciences and Info-Physics Central South UniversityChangsha 410083China

All-solid-state lithium-sulfur(Li-S)battery is regarded as next-generation high energy density and safety battery *** key challenge is to develop a compatible high-performance solid-state ***,a two birds with one stone strategy is proposed to simultaneously enhance Li+conductivity and polysulfide adsorptivity of poly(ethylene oxide)(PEO)-based polymer electrolyte via the integration of Nb_(2)CT_(x)***,the sheet size of Nb_(2)CT_(x)MXene is crucial for the enhancement of Li^(+)conductivity and polysulfide adsorptivity,attributing to the difference in a specific surface area related to the percolation *** tuning the sheet size of Nb_(2)CT_(x)MXene from 500-300 nm to below 100 nm,the ionic conductivity of the PEO electrolyte is increased to2.62×10^(-4)S·cm^(-1)with improved Li+transference number of 0.37 at ***,theoretical calculation and X-ray photoelectron spectroscopy(XPS)conjointly prove that poly sulfides could be effectively adsorbed by Nb2CTxnanosheets via forming Nb-S bonding to inhibit their shuttle in the PEO *** a result,the all-solid-state Li-S cell exhibits an initial capacity of 1149 mAh·g^(-1)at 0.5C and good cycling stability with 491 mAh·g^(-1)after 200 *** results demonstrate the necessity of polysulfide inhibition and the application of Nb_(2)CT_(x)MXene in PEO-based electrolytes for all-solid-state Li-S batteries.

关键词： All-solid-state Li-S batteries Polyethylene oxide(PEO)-based electrolyte Nb_(2)CT,MXene Shuttle effect inhibition

Global Zero-relaxation Limit Problem of the Electro-diffusion Model Arising in Electro-Hydrodynamics

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Acta Mathematicae Applicatae sinica 2024年第1期40卷 241-268页

作者： ming-hua Yang si-ming Huang Jin-yi Sun Department of Mathematics Jiangxi University of Finance and EconomicsNanchang330032China School of Public Administration Guangdong University of Foreign StudiesGuangzhou510006China College of Mathematics and Statistics Northwest Normal UniversityLanzhou730070China

In this paper,we study a global zero-relaxation limit problem of the electro-diffusion model arising in electro-hydrodynamics which is the coupled Planck-Nernst-Poisson and Navier-Stokes *** is,the paper deals with a singular limit problem of{u^(∈)_(t)+u^(∈)·▽u^(∈)-Δu^(∈)+▽P^(∈)=Δφ^(∈)▽φ^(∈),in R^(3)×(0,∞),▽·u^(∈)=0,in R^(3)×(0,∞),n^(∈)_(t)+u^(∈)·▽n^(∈)-Δn^(∈)=-▽·(n^(∈)▽φ^(∈)),in R^(3)×(0,∞),ct+u^(∈)·▽c^(∈)-Δc^(∈)=▽·(c^(∈)▽φ^(∈)),in R^(3)×(0,∞),∈^(-1)φ^(∈)_(t)=Δφ^(∈)-n^(∈)+c^(∈),in R^(3)×(0,∞),(u^(∈),n^(∈),c^(∈),φ^(∈))|t=0=(u0,n0,c0,φ0),in R^(3) involving with a positive,large parameter^(∈).The present work show a case that(u^(∈),n^(∈),c^(∈))stabilizes to(u^(∞),n∞,c∞):=(u,n,c)uniformly with respect to the time variable as^(∈)→+∞with respect to the strong topology in a certain Fourier-Herz space.

关键词： fourier-Herz space littlewood-Paley decomposition stability limit dissipative system

Development of a high-repetition-rate lumped-inductance kicker magnet prototype for the beam switchyard of SHINE

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Nuclear Science and Techniques 2024年第2期35卷 20-31页

作者： Yong-Fang liu Rui-Ping Wang Jin Tong Bo Zhang si Chen Qi-Bing Yuan Hai-Xiao Deng ming Gu Bo liu Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201412People’s Republic of China

The Shanghai high-repetition-rate X-ray free-electron laser and extreme light facility(SHINE)operates at a maximum repetition rate of 1 *** magnets are key components that distribute electron bunches into three different undulator lines in a bunch-by-bunch *** kicker field width must be less than the time interval between bunches.A lumpedinductance kicker prototype was developed using a vacuum chamber with a single-turn *** full magnetic field strength was 0.005 *** paper presents the requirements,design considerations,design parameters,magnetic field calculations,and measurements of the kicker *** relevant experimental results are also *** pulse width of the magnetic field was approximately 600 ns,and the maximum operation repetition rate was 1 *** developed kicker satisfies the requirements for the SHINE ***,numerous recommendations for the future optimization of kicker magnets are provided.

关键词： X-ray free-electron laser Kicker magnet Beam switchyard High repetition rate Ni-Zn ferrites