Polar mesosphere summer echoes (PMSE) are very strong radar echoes from altitudesclose to the polar summer mesopause. The data from sounding rocket campaigns indicatethat the radar signal to noise ratio (SNR), electro...Polar mesosphere summer echoes (PMSE) are very strong radar echoes from altitudesclose to the polar summer mesopause. The data from sounding rocket campaigns indicatethat the radar signal to noise ratio (SNR), electron density and dust charge density of polar mesospherein summer show obvious layered structure. In this paper the theory of wave propagationin layered media is used to study the reflectance and SNR at each layer in polar mesosphere. Thecalculated SNR using theory of dusty plasma is found in good agreement with the experimentalresult, which may imply that the intensity of the radar echoes reflected by the layered structure inpolar mesosphere where polar mesosphere summer echoes used to occur can interpret partially thephenomenon of PMSE. In other words, reflection may play an important role in the occurrence ofPMSE.展开更多
The bulk kinetic energy of jets can be dissipated via generating tur- bulen plasma waves. We examine stochastic particle acceleration in blazar jets to explain the emissions of all blazars. We show that acceleration o...The bulk kinetic energy of jets can be dissipated via generating tur- bulen plasma waves. We examine stochastic particle acceleration in blazar jets to explain the emissions of all blazars. We show that acceleration of electrons by plasma turbulence wavs with a spectrum W（k） k-4/3 produces a nonthermal population of relativistic electrons whose peak frequency of synchrotron emission can fit the observational trends in the spectral energy distribution of all blazars. The plasma nonlinear processes responsible for the formation of turbulent spectrum are investigated. Increases in the ioteraction time of turbulent waves can produce a fiatter spectrum leading to efficient particle acceleration.展开更多
2018年3月22日,国际空间科学联合会前主席BalanNanan教授来所讲学。报告题目是"Severe space weather and its relevance to the High-Tech sociity"。Balan教授是国际著名的空间物理学家,从事地球电离层-磁层及空间天气环境...2018年3月22日,国际空间科学联合会前主席BalanNanan教授来所讲学。报告题目是"Severe space weather and its relevance to the High-Tech sociity"。Balan教授是国际著名的空间物理学家,从事地球电离层-磁层及空间天气环境研究长达40多年。先后在印度、英国等长期工作,并长期在巴西、日本及台湾等多地开展合作研究。Balan教授在空间物理探测及空间等离子体理论研究两方面均有很高造诣,是学术界最为活跃的空间物理学家之一。展开更多
基金supported by National Natural Science Foundation of China (Nos.40831062, 60971034)the Scientific Research Starting Foundation of University of Electronic Science and Technology of China (No.Y02002010401066)
文摘Polar mesosphere summer echoes (PMSE) are very strong radar echoes from altitudesclose to the polar summer mesopause. The data from sounding rocket campaigns indicatethat the radar signal to noise ratio (SNR), electron density and dust charge density of polar mesospherein summer show obvious layered structure. In this paper the theory of wave propagationin layered media is used to study the reflectance and SNR at each layer in polar mesosphere. Thecalculated SNR using theory of dusty plasma is found in good agreement with the experimentalresult, which may imply that the intensity of the radar echoes reflected by the layered structure inpolar mesosphere where polar mesosphere summer echoes used to occur can interpret partially thephenomenon of PMSE. In other words, reflection may play an important role in the occurrence ofPMSE.
基金the National AstronomicalObservatories, Chinese Academy of Sciences (NAOCAS) and by NAOCAS grant 991-5102CA.
文摘The bulk kinetic energy of jets can be dissipated via generating tur- bulen plasma waves. We examine stochastic particle acceleration in blazar jets to explain the emissions of all blazars. We show that acceleration of electrons by plasma turbulence wavs with a spectrum W（k） k-4/3 produces a nonthermal population of relativistic electrons whose peak frequency of synchrotron emission can fit the observational trends in the spectral energy distribution of all blazars. The plasma nonlinear processes responsible for the formation of turbulent spectrum are investigated. Increases in the ioteraction time of turbulent waves can produce a fiatter spectrum leading to efficient particle acceleration.
文摘2018年3月22日,国际空间科学联合会前主席BalanNanan教授来所讲学。报告题目是"Severe space weather and its relevance to the High-Tech sociity"。Balan教授是国际著名的空间物理学家,从事地球电离层-磁层及空间天气环境研究长达40多年。先后在印度、英国等长期工作,并长期在巴西、日本及台湾等多地开展合作研究。Balan教授在空间物理探测及空间等离子体理论研究两方面均有很高造诣,是学术界最为活跃的空间物理学家之一。
