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《中国科学：技术科学》英文版Science China Technological Sciences邀请出版了北京大学空间物理与应用技术研究所长江学者宗秋刚教授团队与青年千人周煦之研究员团队合作的研究成果：利用该所自主研发卫星探测器揭示磁层超低频波演化特性。文章题目为"Ultralow frequency wave characteristics extracted from particledata: Application of IGSO observations"，近日作为封面文章刊登于ScienceChina Technological Sciences 2017年第60卷第3期。敬请关注！
充满高能带电粒子的地球辐射带是空间环境的重要组成部分，自上世纪六十年代被发现以来就因其对宇航、通信、国民经济生产与军事活动的重要影响而受到广泛的关注。而磁层中的超低频波活动则被学界认为与辐射带的动态过程有着密不可分的联系——超低频波可以通过波-粒相互作用实现对辐射带粒子的加速，进而影响空间天气。故而揭示超低频波的产生、演化特征及其与粒子的相互作用对理解辐射带物理过程、预测空间天气有着重要的意义。
北京大学地球与空间科学学院空间物理与应用技术研究所长江学者宗秋刚教授团队与邹鸿副教授团队合作，自主研发了“北大成像粒子谱仪（BeiDa-IES）”，是搭载于我国自主导航卫星平台的新一代空间科学载荷，其设计新颖、测量可靠、高能量与时空分辨率等特性均居世界同类探测器中的领先地位。本文根据“北大成像粒子谱仪（BeiDa-IES）”返回的高精度、高能量分辨率测量数据，结合团队先前已经发展出的“推广的漂移共振”理论模型，分析得出了磁层中超低频波动随时间的增长-衰减演化特性及其时间尺度。本文观测数据与新近理论模型的高度吻合为地球磁层超低频波的演化和粒子的加速提供了全新的理解。
Citation: LI Li, ZHOU XuZhi, ZONG QiuGang, CHEN XingRan, ZOU Hong, REN Jie, HAO YiXin, ZHANG XianGuo. Ultralow frequency wave characteristics extracted from particle data: Application of IGSO observations. Sci China Tech Sci, 2017, 60: 419–424, doi: 10.1007/s11431-016-0702-4
Abstract：Interaction between ultralow frequency (ULF) waves and charged particles plays an important role in the acceleration of particles in the Van Allen radiation belts. The strong wave-particle interaction predicts an energy-dependent observational signature of particle flux variations during different stages of the ULF wave evolution. In this paper, we find that the energetic particle data newly available from an IGSO spacecraft are quite consistent with theoretical predictions, which enables the application of a best-fit procedure to quantitatively extract key parameters of the ULF waves from the particle data. The general agreement between observations and the best-fit results validates the scenario of wave-particle drift resonance within the entire ULF life span, and provides a new technique to understand the ULF wave characteristics in the absence of electromagnetic field data. We also examine the minor differences between observations and the best-fit results, and propose that the differences may result from a longitudinal dependence of the ULF wave power to be considered in a future study.
Keywords：ultralow frequency waves, wave-particle interactions, drift resonance, ULF wave characteristics
Cover Story：The BD-IES instrument is an imaging electron spectrometer onboard the IGSO spacecraft, which was developed by Peking University IES instrument development team based on the PIN-hole technique. The instrument is able to measure high-resolution electron differential fluxes in 9 directions, with 8 energy channels for each direction. On 11 November 2015, BD-IES observed large-amplitude modulations of energetic electron fluxes with the frequency of a few millihertz, which indicates strong interactions between energetic electrons and ultralow frequency (ULF) waves. In the electron energy spectrum, a series of increasingly-inclined stripes were observed from 12:25 to 13:00 UT, which are a most characteristic, “smoking-gun” signature of ULF wave-particle drift resonance after considering the growth and damping of the wave amplitude. The excellent agreement between theory and observations also enables extraction of electromagnetic wave characteristics from the BD-IES electron data, and therefore provides new insights into ULF wave evolution and particle acceleration (to relativistic energies) in the Earth’s magnetosphere.
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发表于 2017-8-13 10:34:16
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