Effect of general loss-cone distribution function on EIC waves in multi- component plasma-particle aspect approach

Abstract

Electrostatic ion-cyclotron waves are investigated in multi-ion plasma (H+, He+ and O+) using particle aspect analysis. Variations with perpendicular wave number of wave frequency, resonant energy and growth rate with general loss-cone distribution function are studied. The whole plasma is considered to consist of resonant and non-resonant particles. The resonant particles participate in energy exchange while the non-resonant particles support the oscillatory motion of the wave. The wave is assumed to propagate obliquely to the static magnetic field. It is found that the frequency for the lighter ions increases then decreases by increasing the perpendicular wave number while the frequency for the heavier ions is constant. Perpendicular wave number decreases the growth rate of the wave and also decreases perpendicular resonant energy and increases parallel resonant energy. The effect of general loss-cone distribution is also discussed with multi-component plasma which increases the wave frequency, growth rate and parallel resonant energy while decreases the perpendicular resonant energy. The study may explain the EIC waves observed in auroral acceleration region. The results are interpreted for the space plasma parameters appropriate to the auroral acceleration region around the earth’s magnetosphere.