Fig. 7

Solution of the linearized dispersion relation for electromagnetic ion cyclotron (EMIC) waves. a Wave number and b growth rate as a function of wave angular frequency for the oxygen torus case, that is, ion composition of (H⁺:He⁺:O⁺) = (80.6:3.4:16.0). Red, green, and blue curves present the branch of the H⁺, He⁺, and O⁺ band EMIC waves, respectively. Parameters used in the calculation are displayed in the top of panels. c, d Same as in a, b except for the no O⁺ ion case, that is, the ion composition of (H⁺:He⁺:O⁺) = (80.6:19.4:0.0). e, f Same as in a and b except for M identical to the oxygen torus case (3.5 amu) with less O⁺ ions, that is, the ion composition of (H⁺:He⁺:O⁺) = (67.8:19.4:12.8)