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Excitation of oblique O + band EMIC waves in the inner magnetosphere driven by hot H + with ring velocity distributions
Author(s) -
Yu Xiongdong,
Yuan Zhigang,
Wang Dedong,
Huang Shiyong,
Qiao Zheng,
Yu Tao,
Yao Fei
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023221
Subject(s) - physics , excitation , magnetosphere , atomic physics , ring current , van allen probes , ion , emic and etic , anisotropy , plasma , computational physics , nuclear physics , van allen radiation belt , optics , quantum mechanics , sociology , anthropology
Based on the linear theory, the detailed growth rate expression of plasma waves for hot ions with ring velocity distributions is derived, which can be directly used to study the wave growth with satellite data. Using linear growth rate calculations with simple magnetic field and background plasma density models, the roles of five parameters ( N e , η H + : η He + : η O + , E r , T perp , and T para ) playing in the excitation of O + band electromagnetic ion cyclotron (EMIC) waves driven by hot H + with ring velocity distributions are investigated. Our calculations demonstrate that ring distributions with sufficiently large ring velocity V r , small perpendicular thermal spread V ⊥ , and appropriate parallel thermal spread V // could enhance the wave growth of oblique O + band EMIC waves. Moreover, our results show that O + band EMIC waves considered here are mainly unstable with large wave normal angles in a dense and rich O + background plasma, in consistent with the statistical characteristics of O + band EMIC waves previously observed by satellites. Therefore, it is indicated that hot H + with ring velocity distributions should play an important role in the excitation of O + band EMIC waves, as a necessary and useful supplement to ring current ions with temperature‐anisotropy bi‐Maxwellian distributions.