Upper hybrid turbulence as a source of nonthermal continuum radiation

Abstract

Recent observations of very narrow band features in the terrestrial electromagnetic “continuum” spectrum indicate that at least part of the radiation is generated in comparatively small source regions, and that weak turbulence theory can account only for the average power. We point out that the structure of the dispersion relation of electrostatic waves near the upper hybrid frequency allows localized nonlinear collapse processes, which could be responsible for the observed narrow band radiation.