《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！
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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