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Observations and parametric study on the role of plasma density on extremely low-frequency chorus wave generation

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Science China(Technological Sciences) 2022年第11期65卷 2649-2657页

作者： HE Qian LIU Si xiao fuliang GAO ZhongLei LI Tong SHANG XiongJun ZHOU QingHua YANG Chang HE YiHua School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China

Extremely low-frequency(ELF)chorus waves with frequencies below 0.1 fcecan cause the scattering losses of relativistic *** studies have suggested that ELF chorus waves are excited by anisotropic electrons with energies up to a few hundred ke ***,we report an interesting event observed using the Van Allen Probes on November 1,2012,where distinct ELF chorus waves occurred exactly corresponding to the enhancement of the plasma *** the correlated data of particles and plasma environments,the continuous calculation of growth rates along the satellite trajectory was *** linear analysis results display a similar pattern to the observation *** further identify the impact of the plasma density on the frequency control of ELF chorus waves,the growth rates were then calculated by only changing the value of the plasma *** calculation results show that the growth rates move to lower frequencies with plasma density enhancement during the *** findings indicate that the increased plasma density has a considerable impact on the wave *** current study can enrich our understanding of the possible role of plasma density on the generation of ELF chorus waves.

关键词： radiation belts plasma density extremely low-frequency chorus waves numerical simulation

A machine-learning-based electron density (MLED) model in the inner magnetosphere

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Earth and Planetary Physics 2022年第4期6卷 350-358页

作者： QingHua Zhou YunXiang Chen fuliang xiao Sai Zhang Si Liu Chang Yang YiHua He ZhongLei Gao School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering Changsha University of Science and TechnologyChangsha 410114China

Plasma density is an important factor in determining wave-particle interactions in the *** develop a machine-learning-based electron density(MLED)model in the inner magnetosphere using electron density data from Van Allen Probes between September 25,2012 and August 30,*** MLED model is a physics-based nonlinear network that employs fundamental physical principles to describe variations of electron *** predicts the plasmapause location under different geomagnetic conditions,and models separately the electron densities of the plasmasphere and of the *** train the model using gradient descent and backpropagation algorithms,which are widely used to deal effectively with nonlinear relationships among physical quantities in space plasma *** model gives explicit expressions with few parameters and describes the associations of electron density with geomagnetic activity,solar cycle,and seasonal *** various geomagnetic conditions,the electron densities calculated by this model agree well with empirical observations and provide a good description of plasmapause *** MLED model,which can be easily incorporated into previously developed radiation belt models,promises to be very helpful in modeling and improving forecasting of radiation belt electron dynamics.

关键词： background electron density inner magnetosphere machine learning Van Allen Probes observation

十五个叶色特异茶树资源在重庆高山地区的引种试验

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南方农业 2024年第9期18卷 66-70,84页

作者：张维肖富良程邦曹兴华翟秀明李解重庆市永川区经济作物技术推广站重庆永川402160 重庆市农业科学院茶叶研究所重庆永川402160 奉节县种植业发展中心重庆奉节404600

为了筛选出适宜在重庆高山茶区生态环境推广种植的特异茶树品种,分析了白叶1号、奶白茶、黄金芽等15个叶色特异茶树品种的成活率、树高、树幅、分枝数、物候期等生物学性状,以及鲜叶生化成分等。结果表明:1)白牛早、特早奶黄资源萌发期... 详细信息

为了筛选出适宜在重庆高山茶区生态环境推广种植的特异茶树品种,分析了白叶1号、奶白茶、黄金芽等15个叶色特异茶树品种的成活率、树高、树幅、分枝数、物候期等生物学性状,以及鲜叶生化成分等。结果表明:1)白牛早、特早奶黄资源萌发期早,其中1芽1叶、1芽2叶初展期,白牛早较于白叶1号提前10 d以上,特早奶黄较中黄1号提前4 d以上。2)奶白茶、中黄1号茶树资源的游离氨基酸含量相对较高,酚氨比均小于4.8,也具有较高的儿茶素品质指数,指数均达到400以上,同时奶白茶茶氨酸含量分别高达1.496%。3)白叶1号、黄金芽的整体性状表现优秀,适宜在重庆高山茶区大范围示范推广种植,并适宜搭配白牛早、特早奶黄、奶白茶、中黄1号等品种。

关键词：叶色特异茶树引种重庆高山地区

维普期刊数据库博看期刊

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重庆地区老鹰茶种质资源现状及保护利用建议

南方农业 2024年第13期18卷 155-158页

作者：李解戴前莉杨娟肖富良袁林颖翟秀明侯渝嘉重庆市农业科学院茶叶研究所重庆永川402160 重庆市林业科学研究院重庆400036

重庆地区具有丰富多样的毛豹皮樟老鹰茶种质资源,由于当前老鹰茶基础研究不够深入,加之重庆地区老鹰茶资源现状不清楚及保护意识薄弱等问题,严重制约重庆老鹰茶产业的健康发展。为给重庆老鹰茶资源的保护与开发利用提供支撑,介绍了重庆... 详细信息

重庆地区具有丰富多样的毛豹皮樟老鹰茶种质资源,由于当前老鹰茶基础研究不够深入,加之重庆地区老鹰茶资源现状不清楚及保护意识薄弱等问题,严重制约重庆老鹰茶产业的健康发展。为给重庆老鹰茶资源的保护与开发利用提供支撑,介绍了重庆市老鹰茶的资源分布与保护现状、品质特性与利用情况等,分析了目前发展中存在的问题,最后提出了“科学合理采摘,提升老鹰茶标准化生产水平;加强生态保护,构建老鹰茶种质资源核心库;加强基础设施建设,打造特色老鹰茶区域品牌;加大资金投入,加强重庆老鹰茶遗传背景与优异种质筛选研究”等对策建议。

关键词：老鹰茶种质资源现状保护利用对策建议重庆

维普期刊数据库博看期刊

Responses of geostationary orbit energetic electron fluxes to chorus waves under different geomagnetic conditions

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Science China Earth Sciences 2013年第11期56卷 2006-2014页

作者： ZHOU xiaoPing xiao fuliang HE YiHua YANG Chang ZHOU QingHua ZHANG ZeLong GAO ZhongLei & DING YuanHui School of Physics and Electronic SciencesChangsha University of Science and Technology

We investigate the flux evolution of geostationary orbit energetic electrons during a strong storm on 24 August 2005(event A,the storm index Dst50 nT,average AE=320 nT).Data collected by LANL and GOES-12 satellites show that energetic electron fluxes increase by a factor of 10 during the recovery phase compared to the prestorm level for both events A and *** the substorm continued,the Cluster C4 satellite observed strong whistler-mode chorus waves(with spectral density approaching 10 5nT2/Hz).The wave amplitude correlates with the substorm AE index,but is less correlated with the storm Dst *** a Gaussian distribution fitting method,we solve the Fokker-Planck diffusion equation governing the wave-particle *** results demonstrate that chorus waves efficiently accelerate^1 MeV energetic electrons,particularly at high pitch *** calculated acceleration time scale and amplitude are comparable to *** results provide new observational support for chorus-driven acceleration of radiation belt energetic electrons.

关键词： energetic electron flux chorus waves wave-particle interaction geomagnetic condition

Direct evidence for efficient scattering of suprathermal electrons by whistler mode waves in the Martian magnetosphere

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Earth and Planetary Physics 2023年第6期7卷 607-614页

作者： Tong Li Si Liu Chang Yang fuliang xiao HongMing Yang Sai Zhang ZhongLei Gao Qian He QingHua Zhou QiWu Yang YiHua He School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering Changsha University of Science and TechnologyChangsha 410114China School of Electrical and Information Engineering Changsha University of Science and TechnologyChangsha 410114China

Whistler mode waves are critical emissions in magnetized plasmas that usually influence the electron dynamics in a planetary *** this paper,we present a unique event in the Martian magnetosphere in which enhanced whistler mode waves(~10^(−11) V^(2)/m^(2)/Hz)with frequency of 0.1 f_(ce)-0.5 f_(ce) occurred,based on MAVEN data,exactly corresponding to a significant decrease of suprathermal electron *** diffusion coefficients are calculated by using the observed electric field wave *** pitch angle diffusion coefficient can approach 10^(−2) s^(−1),which is much larger,by~100 times,than the momentum diffusion coefficient,indicating that pitch angle scattering dominates the whistler-electron resonance *** current results can successfully explain the dropout of the suprathermal electrons in this *** study provides direct evidence for whistler-driven electron losses in the Martian magnetosphere.

关键词： whistler mode waves diffusion coefficients electron scattering Martian magnetosphere

Upward propagation of lightning-generated whistler waves into the radiation belts

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Science China(Technological Sciences) 2020年第2期63卷 243-248页

作者： GUO MingYue ZHOU QingHua xiao fuliang LIU Si HE YiHua YANG Chang School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China

Lightning-generated whistler(LGW) waves which induce energetic electron precipitation provide an important coupling between the ionosphere and radiation belts. Using the ray-tracing technique, we examine the propagation behaviour of LGW waves and show that they can travel upward into the radiation belts during higher geomagnetic activities due to the plasmapause inward compression, particularly in cases of lower wave frequencies, lower wave normal angles and azimuthal angles. Both perpendicular and parallel group velocities of LGW waves remain in relatively small values inside the plasmasphere but change rapidly to high values outside the plasmasphere. The launching latitude increases with increasing LGW wave normal angle. These results here further reveal a detailed picture on how LGW waves escape out of the plasmasphere and onto the radiation belts.

关键词： lightning-generated whistler waves radiation belts numerical simulation

Magnetospheric chorus wave instability induced by relativistic Kappa-type distributions

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Science China(Technological Sciences) 2016年第11期59卷 1739-1745页

作者： YANG QiWu YANG Chang HE YiHua LIU Si ZHOU QingHua xiao fuliang School of Physics and Electronic Sciences Changsha University of Science and Technology

We study the field-aligned propagating magnetospheric chorus wave instability using a fully relativistic wave growth formula,the previously developed relativistic Kappa-type(KT) distribution and the regular Kappa distribution of energetic *** demonstrate that the peak growth rate using the nonrelativistic Kappa simulation is higher than that using either the relativistic KT or the Kappa simulation at/above 100 keV, because the significant relativistic effect yields a reduction in the relativistic anisotropy. The relativistic anisotropy Arel basically decreases as the thermal parameter θ2 increases, allowing the peak growth by relativistic KT or Kappa distribution to stay at the lower frequency region. The growth rates tend to increase with the loss-cone parameter l because the overall anisotropy increases. Moreover, at high energy ~1.0 MeV, both the growth rate and the upper cutoff frequency become smaller as l increases for the relativistic KT calculation because the significant relativistic effect reduces both the resonant anisotropy and the number of the hot electrons, which is in contrast to the relativistic and nonrelativistic Kappa distribution calculations because the less relativistic or non-relativistic effect enhances the resonant anisotropy as l increases. The above results can be applied to the whistler-mode wave instability in the outer radiation belts of the Earth, the Jovian inner magnetosphere and other astrophysical plasmas where relativistic electrons often exist.

关键词： Kappa-type distribution energetic electrons wave-particle interaction chorus wave instability

Butterfly distribution of Earth＇s radiation belt relativistic electrons induced by dayside chorus

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Science China(Technological Sciences) 2018年第2期61卷 212-218页

作者： jin yuyue yang chang he yihua liu si zhou qinghua xiao fuliang school of physics and electronic sciences changsha university of science and technologyChangsha 410004China

Previous theoretical studies have shown that dayside chorus can produce butterfly distribution of energetic electrons in the Earth＇s radiation belts by preferentially accelerating medium pitch angle electrons, but this requires the further confirmation from high- resolution satellite observation. Here, we report correlated Van Allen Probes data on wave and particle during the 1 I-13 April, 2014 geomagnetic storm. We find that a butterfly pitch angle distribution of relativistic electrons is formed around the location L = 4.52, corresponding to the presence of enhanced dayside chorus. Using a Gaussian distribution fit to the observed chorus spectra, we calculate the bounce-averaged diffusion rates and solve two-dimensional Fokker-Planck equation. Numerical results demonstrate that acceleration by dayside chorus can yield the electron flux evolution both in the energy and butterfly pitch angle distribution comparable to the observation, providing a further evidence for the formation of butterfly distribution of relativistic electrons driven by very low frequency （VLF） plasma waves.

关键词： butterfly distribution relativistic electrons radiation belts wave-particle interaction dayside chorus