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Nonlinear change of ion-induced secondary electron emission in theκ-Al_(2)O_(3) surface charging from first-principle modelling

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Plasma science and Technology 2024年第9期26卷 40-50页

作者： Zhicheng JIAO Mingrui ZHU Dong DAI Tao sHAO Buang WANG south China university of Technology Guangzhou 510641People’s Republic of China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190People’s Republic of China university of Richmond Richmond 23173United States of America

secondary electron emission(sEE)induced by the positive ion is an essential physical process to influence the dynamics of gas discharge which relies on the specific surface *** charging has a significant impact on the material properties,thereby affecting the sEE in the plasma-surface ***,it does not attract enough attention in the previous *** this paper,sEE dependent on the charged surface of specific materials is described with the computational method combining a density functional theory(DFT)model from the first-principle theory and the theory of Auger *** effect ofκ-Al2O3 surface charge,as an example,on the ion-induced secondary electron emission coefficient(sEEC)is investigated by analyzing the defect energy level and band structure on the charged *** results indicate that,with the surface charge from negative to positive,the sEEC of a part of low ionization energy ions(such as Ei=12.6 eV)increases first and then decreases,exhibiting a nonlinear changing *** is quite different from the monotonic decreasing tendency observed in the previous model which simplifies the electronic *** irregular increase of the sEEC can be attributed to the lower escaped probability of orbital *** results further illustrate that the excessive charge could cause the bottom of the conduction band close to the valence band,thus leading to the decrease of the orbital energy occupied by the excited *** nonlinear change of sEEC demonstrates a more realistic situation of how the electronic structure of material surface influences the sEE *** work provides an accurate method of calculating sEEC from specific materials,which is urgent in widespread physical scenarios sensitive to surface materials,such as increasingly growing practical applications concerning plasma-surface interactions.

关键词： secondary electron emission charged surface density functional theory defect energy level

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First results of CO_(2) dispersion interferometer on EAsT tokamak

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Plasma science and Technology 2024年第3期26卷 76-82页

作者：刘郁阳李维明姚远张耀张家敏连辉洪博王守信揭银先刘海庆 Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People's Republic of China university of science and Technology of China Hefei 230026People's Republic of China Institutes of Physical science and Information Technology Anhui UniversityHefei 230031People's Republic of China

A dispersion interferometer(DI)has been installed and operates on the Experimental Advanced superconducting Tokamak(EAsT).This DI system utilizes a continuous-wave 9.3μm CO_(2)laser source to measure line-averaged electron densities *** contrast to conventional interferometers,the DI does not require substantial vibration isolations or compensating systems to reduce the impact of vibrations in the optical *** also employs a ratio of modulation amplitudes,ensuring it remains immune to the variations in detected *** a variation compensation system,the DI system on EAsT reaches a density resolution of less than1.8×10^(-2)πrad and a temporal resolution of 20μ*** measurements made by the POlarimeterINTerferometer(POINT)system and the far-infrared hydrogen cyanide(HCN)interferometer are remarkably consistent with the DI’s *** possibility of fringe jumps and the impact of refraction in high-density discharge can be significantly decreased using a shorter wavelength laser source.A rapid density change of 3×10^(19)m^(-3)during 0.15 s has been measured accurately in shot No.114755 of ***,the DI system demonstrates dependability and stability under 305 s long-pulse discharges in shot No.122054.

关键词： dispersion interferometer(DI) electron density plasma diagnostics Experimental Advanced superconducting Tokamak(EAsT)

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Comparison of transport coefficients before and after density pump-out induced by resonant magnetic perturbation using a BOUT++ six-field model on the EAsT tokamak

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Plasma science and Technology 2024年第6期26卷 111-119页

作者：邓成成刘子奚夏天阳刘彦君厉鹏程龙飞飞高翔王守信李国强刘海庆臧庆李玖瑛杨康宁吴茗甫尹晓宇李弘谢锦林兰涛毛文哲刘阿娣周楚丁卫星庄革刘万东 the EAsT Team Department of Plasma Physics and Fusion Engineering University of Science and Technology of ChinaHefei 230026People’s Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China

Many experiments have demonstrated that resonant magnetic perturbation(RMP) can affect the turbulent transport at the edge of the tokamak. Through the Experimental Advanced superconducting Tokamak(EAsT) density modulation experiment, the particle transport coefficients were calculated using the experimental data, and the result shows that the particle transport coefficients increase with RMP. In this study, the six-field two-fluid model in BOUT++ is used to simulate the transport before and after density pump-out induced by RMP,respectively referred as the case without RMP and the case with RMP. In the linear simulations,the instabilities generally decreases for cases with RMP. In the nonlinear simulation, ELM only appears in the case without RMP. Additionally, the particle transport coefficient was analyzed,and the result shows that the particle transport coefficient becomes larger for the case with RMP,which is consistent with the experimental conclusion. Moreover, its magnitude is comparable to the results calculated from experimental data.

关键词： BOUT++ resonant magnetic perturbation(RMP) transport coefficients

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single flow treatment degradation of antibiotics in water using falling-film dielectric barrier discharge

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Plasma science and Technology 2024年第4期26卷 27-36页

作者：许志远章程伍云健黄邦斗席登科张晓星邵涛 Hubei Engineering Research Center for safety Monitoring of New Energy and Power Grid Equipment Hubei University of TechnologyWuhan 430068People’s Republic of China Beijing International s&T Cooperation Base for Plasma science and Energy Conversion Institute of Electrical EngineeringChinese Academy of SciencesBeijing 100190People’s Republic of China university of chinese Academy of sciences Beijing 100049People’s Republic of China

The environmental contamination caused by antibiotics is increasingly conspicuous due to their widespread manufacture and misuse. Plasma has been employed in recent years for the remediation of antibiotic pollution in the environment. In this work, a falling-film dielectric barrier discharge was used to degrade the antibiotic tetracycline(TC) in water. The reactor combined the gas-liquid discharge and active gas bubbling to improve the TC degradation performance. The discharge characteristics, chemical species’ concentration, and degradation rates at different parameters were systematically studied. Under the optimized conditions(working gas was pure oxygen, liquid flow rate was 100 mL/min, gas flow rate was 1 L/min,voltage was 20 kV, single treatment), TC was removed beyond 70% in a single flow treatment with an energy efficiency of 145 mg/(kW·h). The reactor design facilitated gas and liquid flow in the plasma area to produce more ozone in bubbles after a single flow under pure oxygen conditions, affording fast TC degradation. Furthermore, long-term stationary experiment indicated that long-lived active species can sustain the degradation of TC. Compared with other plasma treatment systems, this work offers a fast and efficient degradation method, showing significant potential in practical industrial applications.

关键词： antibiotic degradation dielectric barrier discharge reactive species single flow treatment

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Degree of shade tolerance shapes seasonality of chlorophyll, nitrogen and phosphorus levels of trees and herbs in a temperate deciduous forest

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Journal of Forestry Research 2024年第4期35卷 60-72页

作者： Jiajia Zeng Fan Liu Yuan Zhu Jiayi Li Ying Ruan Xiankui Quan Chuankuan Wang Xingchang Wang Aulin College Northeast Forestry UniversityHarbin 150040People’s Republic of China Center for Ecological Research Northeast Forestry UniversityHarbin 150040People’s Republic of China Key Laboratory of Agricultural Water Resources Center for Agricultural Resources ResearchInstitute of Genetics and Developmental BiologyChinese Academy of SciencesShijiazhuang 050021People’s Republic of China Institute of Applied Ecology Chinese Academy of SciencesShenyang 110016People’s Republic of China Key Laboratory of sustainable Forest Ecosystem Management Ministry of EducationNortheast Forestry UniversityHarbin 150040People’s Republic of China

Forest productivity is closely linked to seasonal variations and vertical differentiation in leaf ***,leaf structural and chemical traits variation among co-existing species,and plant functional types within the canopy are poorly *** this study,the seasonality of leaf chlorophyll,nitrogen(N),and phosphorus(P)were quantified vertically along the canopy of four major tree species and two types of herbs in a temperate deciduous *** role of shade tolerance in shaping the seasonal variation and vertical differentiation was *** the entire season,chlorophyll content showed a distinct asymmetric unimodal pattern for all species,with greater chlorophyll levels in autumn than in spring,and the timing of peak chlorophyll per leaf area gradually decreased as shade tolerance *** a:b ratios gradually decreased with increasing shade *** N and P contents sharply declined during leaf expansion,remained steady in the mature stage and decreased again during leaf *** the seasons,the lower canopy layer had significantly higher chlorophyll per leaf mass but not chlorophyll per leaf area than the upper canopy layer regardless of degree of shade ***,N and P per leaf area of intermediate shade-tolerant and fully shade-tolerant tree species were significantly higher in the upper canopy than in the *** variations in N:P ratios suggest changes in N or P *** findings indicate that shade tolerance is a key feature shaping inter-specific differences in leaf chlorophyll,N,and P contents as well as their seasonality in temperate deciduous forests,which have significant implications for modeling leaf photosynthesis and ecosystem production.

关键词： Leaf traits Leaf nutrients seasonal variations Chlorophyll Nitrogen Phosphorus shade tolerance Canopy layers

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A fringe jump counting method for the phase measurement in the HCN laser interferometer on EAsT and its FPGA-based implementation

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Plasma science and Technology 2024年第4期26卷 156-161页

作者：姚远杨曜提昂宋扬张家敏王琰张耀刘海庆揭银先 Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China Anhui Electrical Engineering Professional Technique College Hefei 230022People’s Republic of China Institutes of Physical science and Information Technology Anhui UniversityHefei 230601People’s Republic of China

Electron density in fusion plasma is usually diagnosed using laser-aided interferometers. The phase difference signal obtained after phase demodulation is wrapped, which is also called a fringe jump. A method has been developed to unwrap the phase difference signal in real time using FPGA, specifically designed to handle fringe jumps in the hydrogen cyanide(HCN) laser interferometer on the EAsT superconducting tokamak. This method is designed for a phase demodulator using the fast Fourier transform(FFT) method at the front end. The method is better adapted for hardware implementation compared to complex mathematical analysis algorithms, such as field programmable gate array(FPGA). It has been applied to process the phase measurement results of the HCN laser interferometer on EAsT in real time. Electron density results show good confidence in the fringe jump unwrapping method. Further possible application in other laser interferometers, such as the POlarimeter-INTerferometer(POINT)system on EAsT tokamak is also discussed.

关键词： electron density laser-aided interferometer fringe jump unwrapping FPGA EAsT

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Decreasing productivity of pine forests on the southern edge of the Mongolian Plateau as indicated by tree rings

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Journal of Forestry Research 2024年第5期35卷 171-181页

作者： Zhuolan shen shijie Wang Feng Chen Heli Zhang Xiaoen Zhao Youping Chen Mao Hu Yunnan Key Laboratory of International Rivers and Transboundary Eco‑security Institute of International Rivers and Eco‑SecurityYunnan UniversityKunming 650500People’s Republic of China southwest United Graduate school Kunming 650500People’s Republic of China Key Laboratory of Tree-Ring Physical and Chemical Research of China Meteorological Administration/Xinjiang Laboratory of Tree-Ring Ecology Institute of Desert MeteorologyChina Meteorological AdministrationÜrümqi 830002People’s Republic of China

Vegetation productivity on the southern edge of the Inner Mongolian Plateau,which plays a vital role in the ecological environment and in the arable and pasto-ral production in this region,can be characterized by the NDVI(normalized difference vegetation index).However,the observed NDVI data span only the last~40 *** growth of Pinus tabulaeformis *** strongly correlated with the NDVI,making it a valuable proxy for extend-ing the length of observed NDVI *** this study,we reconstructed an NDVI series for 1776–2021 for the Daqing Mountains,based on a tree-ring width *** reconstructed data accounted for 55%of the variance in the observed data,and its statistical characteristics and validation indicate that the reconstruction is *** correlation analysis demonstrated the consistency of climate signals in central Inner Mongolia in both the arable and pastoral *** results of superposed epoch analysis revealed a good temporal consistency between drought and flood events and the reconstructed NDVI sequence in this region.

关键词： Drought semi-arid area Peru current Yinshan Mountains

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Astronomical Test with CMOs on the 60 cm Telescope at the Xinglong Observatory,NAOC

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Research in Astronomy and Astrophysics 2024年第5期24卷 85-102页

作者： Hai-Yang Mu Zhou Fan Yi-Nan Zhu Yu Zhang Hong Wu Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101People’s Republic of China school of Astronomy and space science University of Chinese Academy of SciencesBeijing 100049People’s Republic of China

This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of supersky flat fields, open clusters, standard stars and exoplanets. Photometry was precision achieved at the 0.02 mag level, with differential photometry of 0.004 mag precision. Extinction was found to agree with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with a charge-coupled device across the optical wavelengths.

关键词： atmospheric effects-instrumentation detectors-techniques polarimetric-stars atmospheres-eclipses

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Method to measure tree-ring width,density,elemental composition,and stable carbon and oxygen isotopes using one sample

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Journal of Forestry Research 2024年第3期35卷 167-174页

作者： Chenxi Xu Yaru Zhao Wenling An Qingyu Zhao Yucheng Liu Masaki sano Takeshi Nakatsuka Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029People's Republic of China CAs Center for Excellence in Life and Paleoenvironment Beijing 100044People's Republic of China College of Earth sciences University of Chinese Academy of SciencesBeijing 100049People's Republic of China Graduate school of Environment studies Nagoya UniversityNagoya 4648601Japan

Tree-ring width(RW),density,elemental com-position,and stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)are widely used as proxies to assess climate change,ecology,and environmental pollution;however,a specific pretreat-ment has been needed for each ***,we developed a method by which each proxy can be measured in the same ***,the sample is polished for ring width *** obtaining the ring width data,the sample is cut to form a 1-mm-thick wood *** sample is then mounted in a vertical sample holder,and gradually scanned by an X-ray ***,the count rates of the fluorescent photons of elements(for chemical characteriza-tion)and a radiographic grayscale image(for wood density)are obtained,*** density and the element content are ***,cellulose is isolated from the 1-mm wood plate by removal of lignin,and *** producing this cellulose plate,cellulose subsamples are separated by knife under the microscope for inter-annual and intra-annual stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)*** on this method,RW,density,elemental composition,δ^(13)C,and δ^(18)O can be measured from the same sample,which reduces sample amount and treatment time,and is helpful for multi-proxy comparison and combination research.

关键词： Tree-ring width Tree-ring density Tree-ring elemental composition Tree-ring stable carbon and oxygenisotopes

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Polarimeter–interferometer diagnostic using terahertz solid-state sources for fluctuation measurements on Keda Torus e Xperiment(KTX)

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Plasma science and Technology 2024年第3期26卷 61-65页

作者：汪兴康毛文哲谢锦林兰涛李弘刘阿娣周楚温晓辉卫子安吴捷陈晨刘东宽饶贤昊蔡虎邬佳仁邓鹏刘海庆丁卫星庄革刘万东 school of Nuclear science and Technology University of Science and Technology of ChinaHefei 230026People's Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China

A multi-channel polarimeter-interferometer has been developed on the Keda Torus eXperiment(KTX)for the study of equilibrium dynamics and internal magnetic fluctuations.A three-wave technique based on terahertz solid-state sources(-650 GHz)is applied for simultaneous measurements of electron density and Faraday rotation *** output power of the microwave source is 2 *** rotation effect using a rotating wave plate is tested with phase noise less than 0.8°,and the density phase noise is less than 0.9°.Measurement of Faraday rotation angle and density for discharges on KTX have demonstrated high sensitivity to internal MHD activities.

关键词： plasma diagnostics interferometry terahertz polarimeter

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