1990 Volume 66 Issue 7 Pages 129-134
The earth is a rotating magnetized emitter of coherent radio bursts called the auroral kilometric radiation (AKR); the phenomena have a common characteristics with Jupiter and pulsars. The origin of AKR has long been understood as the results of the cyclotron maser mechanisms that are only possible in the very tenuous plasma cavity with fp/fc (fp and fc are respectively plasma and electron cyclotron frequencies) value less than 0.1. Furthermore, the cyclotron maser mechanism requires only the trapped component of the energetic particles with loss cone velocity distributions. Contrary to this cyclotron maser mechanisms, generation of the plasma waves by the inverse Landau mechanism of the upper hybrid mode waves in the frequency range fc<fe<(fc2+fp2)1/2, for the emission frequency fe and conversion of this plasma waves to the escape mode of the electromagnetic waves have been proposed in this paper. The evidences of large fp/fc value (fp/fc>0.3) and the emissions associated with 2nd harmonics of fUHR (fUHR=(fc2+fp2)1/2) discovered by the EXOS-D satellite observations support the origin at the upper hybrid mode wave branch and the conversion of that wave into AKR. The informations on the polarizations of AKR detected by the EXOS-D satellite data show clear consistency with the polarization features predicted by the plasma wave conversion theory.
