Bounce-averaged Pitch-angle Diffusion by Electromagnetic Ion Cyclotron Waves in Multi-ion Plasmas
XIAO Fu-Liang1,2, TIAN Tian3, CHEN Liang-Xu1
1$School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 4100042State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 1001903School of Earth and Space Sciences, Peking University, Beijing 100871
Bounce-averaged Pitch-angle Diffusion by Electromagnetic Ion Cyclotron Waves in Multi-ion Plasmas
XIAO Fu-Liang1,2, TIAN Tian3, CHEN Liang-Xu1
1$School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 4100042State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 1001903School of Earth and Space Sciences, Peking University, Beijing 100871
We present a study on the gyroresonant interaction between electromagnetic ion cyclotron waves and ring current particles in multi-ion (H+, He+, and O+) plasmas. We provide a first evaluation of the bounce-averaged pitch angle diffusion coefficient <Dαα> for three typical energies of 50, 100 and 150keV at L≈3.5, the heart of the symmetrical ring current. We show that in the H+-band and He+-band, <Dαα> can approach ~10-4s-1 for ion H+, and ~5× 10-5s-1 for ion He+; meanwhile, in the O+-band, <Dαα> can reach ~10-5s-1 for ions He+ and O+. The results above show that the EMIC wave can efficiently produce precipitation loss of energetic (~100keV) ions (H+, He+ and even O+), and such a wave tends to be a serious candidate responsible for the ring current decay.
We present a study on the gyroresonant interaction between electromagnetic ion cyclotron waves and ring current particles in multi-ion (H+, He+, and O+) plasmas. We provide a first evaluation of the bounce-averaged pitch angle diffusion coefficient <Dαα> for three typical energies of 50, 100 and 150keV at L≈3.5, the heart of the symmetrical ring current. We show that in the H+-band and He+-band, <Dαα> can approach ~10-4s-1 for ion H+, and ~5× 10-5s-1 for ion He+; meanwhile, in the O+-band, <Dαα> can reach ~10-5s-1 for ions He+ and O+. The results above show that the EMIC wave can efficiently produce precipitation loss of energetic (~100keV) ions (H+, He+ and even O+), and such a wave tends to be a serious candidate responsible for the ring current decay.
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2009, Vol. 26 
