SPRG Seminars
April 7, 2009:
" Effects of Heavy Ions on EMIC waves in Inhomogeneous Space"
Dong-Hun Lee,Kyung Hee University, Korea
EMIC waves are strongly associated with the presence of heavy ions in the magnetosphere. We investigate the role of heavy ion resonances in nonuniform plasmas. The coupled plasma wave equations are solved in an exact manner to calculate the resonant absorption at the ion-ion hybrid resonance. Our results show that irreversible mode conversion occurs at the resonance, which absorbs the fast wave energy. It is found that waves near the resonances appear with linear polarization, and their amplitude and frequency are sensitive to the background heavy ion composition properties.
We examine how these resonances occur for various H+- He+ populations in detail by performing an accurate calculation on the mode conversion efficiency. Due to the fact that the multi-ion hybrid resonances in cold plasmas are determined by simple parameters such as the fraction of the ion number density of each species and the magnetic field, it is suggested that monitoring the local heavy ion population is possible simply by examining peak frequencies of the linearly polarized wave events in either electric field or magnetic field data.