Emissivity and growth of auroral kilometric radiation in source regions with perpendicular gradients

Abstract

Emission and propagation of the auroral kilometric radiation in the auroral zones of the Earth are investigated with the use of the transfer equation for the intensity of the wave along the trajectory, which is obtained with the formulation of the geometríc optics. The cyclotron emissivity and the components of the dielectric tensor are evaluated using the locally homogeneous plasma approximation, taking into account thermal effects and con­ sidering both the energetic and the background electron populations. For frequencies in the vicinity of the electron cyclotron frequency we consider a range of values of the parallel wave number which result in significant amplification. The effect of the finite width of the amoral cavities is also investigated. Our results show that the inclusion of the effect of wave emissivity along the trajectory is not sufficient to modify significatively the efficiency of the amplification.