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Particle acceleration and transport in the inner heliosphere

发布时间:2018-04-28 23:35来源:未知 责任编辑:于莹

报告题目: Particle acceleration and transport in the inner heliosphere

报 告 人:李刚

报告时间:2018年05月17日 16时00分

报告地点:天文楼212

Title: Particle acceleration and transport in the inner heliosphere

LI Gang

Department of Space Science and CSPAR, University of Alabama in Huntsville,, USA

Abstract: 
Our Sun is a very efficient particle accelerator. It can produce high energy protons and heavy ions with energies exceeding GeV/nucleon in the so-called Solar Energetic Particle (SEP) events where large solar flares and fast coronal mass ejections (CMEs) often occur together. A variety of acceleration mechanisms exist and are believed to occur in a combined fashion in these events. Among these, diffusive shock acceleration (DSA)
dominates at CME-driven shocks. While the underlying theory of DSA is simple, its application in the solar system leads to the considerations of many fundamental issues, including the seed population and injection efficiency; characteristic Q/A dependence of spectral brakes; the shock geometry effect, etc.  Observations, especially simultaneous multi-spacecraft observations have provided useful clues to further understand the DSA and its application at CME-driven shocks. However, because observations of energetic particles are often made at Earth, the  propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. This propagation is modulated by the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. Therefore a correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. In this talk I discuss some of the current state of knowledge of particle acceleration at shocks and transport in the inner heliosphere, focusing on a few topics which may bear the key features to further understand the problem of particle acceleration and transport.

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