Generation of Auroral Kilometric Radiation in a dipole magnetic field: 3-D approach. Planetary Radio Emissions|PLANETARY RADIO EMISSIONS VIII 8|

We have investigated the propagation and amplification of Auroral Kilometric Radiation (AKR) in a narrow three-dimensional plasma cavity, in which a weakly relativistic electron beam propagates along the magnetic field. Both electron beam velocity components, parallel and perpendicular to the magnetic field are taken into account. Although the energy of transverse electron motion serves as a source of free energy for the development of electron cyclotron maser instability, it is found that for correct description of the AKR spectrum formation it is necessary to take the velocity component of electron motion directed along the magnetic field into account, because it gives a possibility for wave generation in a much wider frequency range. The results of calculations performed for thousands of waves have strengthened the assumption made in our previous paper [Burinskaya, 2013] on a basis of calculations for several waves, that the main factor, determining the wave energy at the time of wave escape from a source, is the duration of wave lifetime inside an amplification region. Thus, the global magnetic field inhomogeneity plays a key role in the formation of the AKR spectrum, because it defines for each wave its lifetime inside an amplification region and, by this means, the wave spectral intensity