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Suprathermal particle events observed by WIND spacecraft in interplanetary space during 1995―1999 and their classification

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Science china(Technological sciences) 2008年第9期51卷 1542-1553页

作者： sun lingpeng1,2, wu dejin1 & wang deyu1 1 purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 2 Graduate School of chinese academy of sciences, Beijing 100049, china purple mountain observatory Chinese Academy of Sciences Nanjing 210008 China Graduate School of chinese academy of sciences Beijing 100049 China

Fifty-five suprathermal particle events were selected from WIND observations between 1995 and 1999. Based on systematic analysis on the observational characteristics of these events a two-parameter (the rising time and the flux ratio of electrons to protons in each event) classification method was proposed to classify these events. The three clas-sified classes are (1) impulsive electron events with the flux ratio of electrons to protons being bigger than 1 and rising time being shorter than 200 min, (2) impulsive proton events with the flux ratio being smaller than 1 and rising time being shorter than 200 min, and (3) gradual proton events with the flux ratio being smaller than 1 and the rising time being longer than 200 min. In the past, "impulsive solar electron events" were under in-tense research. However, because the selection standards of their velocity dispersions or pitch-angle distributions were inadequate, statistical surveys of selected events were dif-ferent from each other and even some conclusions were not consistent with the theory, for example, the relation of type-III solar radio bursts to the "impulsive solar electron events". The first class of impulsive electron events are associated with type-III radio bursts and with clear velocity dispersions; therefore they ought to originate from the sun. The second class of the events, which have short continuance time and usually are not associated with type-III radio bursts and without velocity dispersion, are still far away from inter-planetary shocks and most of them do not one-to-one correspond to corrotating interact-ing regions (CIRs); such events are possible results of local interplanetary magnetic field reconnection or electromagnetic disturbances. Finally, about 2/3 gradual proton events of the third class occur with interplanetary shocks, the delay times of which are almost equal to the rising time. Some of these events can be understood as particle accelerations by shocks.

关键词： suprathermal particles solar wind plasma solar eruptive activity interplanetary active regions

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Saturation level of Alfvén waves driven by Kelvin–Helmholtz instability

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chinese Science Bulletin 2014年第28期59卷 3536-3542页

作者： Ling Chen dejin wu Guoqing Zhao Jing Huang purple mountain observatory Chinese Academy of Sciences Key Laboratory of Solar Activity National Astronomical Observatories Chinese Academy of Sciences University of chinese academy of sciences

Alfve′n waves(AWs) can play an important role in the macroscopic dynamics as well as in the microscopic wave–particle interaction in various magnetoplasma environments. A very wide observed range of the relative amplitude of magnetic fluctuations of AWs from lower than 10-3in the terrestrial magnetosphere up to *1in the solar wind implies the complexity of saturation mechanisms of AWs. Taking account of the ion-neutral collision damping in a partially ionized plasma, the saturation level of AWs driven by the Kelvin–Helmholtz(K–H) instability is investigated in this paper. The intensified magnetic field due to the excited AWs may result in the saturation of the excited AWs when the growth rate is balanced by the damping rate. An equation determining the saturation level of the AWs is obtained. The results show that, for a fixed-frequency wave, the saturation level of the AWs considerably increases as the ionization degree increases as well as the sheared-flow velocity. On the other hand, for a fixed ionization degree the saturation level of the AWs slightly increases as the plasma b increases but decreases as the wave frequency increases. These results have potential importance for us to estimate the saturation level of AWs in space and astrophysical plasmas.

关键词：阿尔芬波不稳定性亥姆霍兹饱和度开尔文驱动等离子体环境 AWS

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Magnetic Fine Structures in the Solar Corona and Their Heating by Kinetic Alfven Waves

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Bulletin of the chinese academy of sciences 2011年第3期25卷 215-219页

作者： wu dejin CHEN Ling purple mountain observatory CAS Nanjing 210008

The sun is our nearest star and the energy released by nuclear reactions near its centre is transported by photons inside the inner - 71% of the solar radius （ R⊙= 6.9 × 10^5km）, called the radiative zone. Outside this radiative zone, called the convective zone, photons are no longer able to transfer energy efficiently, so convective instabilities set in and vertical flows carry nearly all the excess heat to the solar surface. This visible surface, called the photosphere,

关键词：结构动力学阿尔文波太阳表面取暖日冕能量效率对流不稳定辐射区

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The Oblique Alfvén Ion Beam Instability in the Earth’s Ion Foreshock

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Research in Astronomy and Astrophysics 2023年第2期23卷 177-186页

作者： Yuhang Yao Jinsong Zhao Huasheng Xie Wen Liu dejin wu Key Laboratory of Planetary sciences Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Hebei Key Laboratory of Compact Fusion Langfang 065001China ENN Science and Technology Development Co. Ltd.Langfang065001China

How ions evolve in the Earth’s ion foreshock is a basic problem in the heliosphere community,and the ion beam instability is usually proposed to be one major mechanism affecting the ion dynamics *** work will perform comprehensive analyses of the oblique ion beam instability in the Earth’s ion *** show that in addition to two well-known parallel instabilities (i.e.,the parallel fast-magnetosonic whistler instability and the parallel Alfvén ion cyclotron instability),the oblique Alfvén ion beam (OA/IB) instability can also be triggered by free energy relating to the relative drift d V between the solar wind proton and reflected proton *** slow d V (e.g.,d V■2.2V_(A),where VAdenotes the Alfvén speed),it only triggers the OA/IB *** d V■2.2V_(A),the growth rate in the OA/IB instability can be about 0.6 times the maximum growth rate in parallel ***,this work finds the existence of two types of OA/IB *** first one appears at slow d V and in the small wavenumber region at fast d V,and this instability can be described by the cold fluid *** second one arises in large wavenumber regions at fast d V,and this instability only appears in warm ***,through the energy transfer rate method,we propose that the OA/IB instability is driven by the competition among the Landau and cyclotron wave-particle interactions of beam protons,the cyclotron wave-particle interaction of core protons,and the Landau wave-particle interaction of *** oblique waves can experience significant damping,the importance of the OA/IB instability may be the effective heating of ions in the Earth’s foreshock.

关键词： plasmas-instabilities-waves-(sun:)solar-terrestrial relations

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