[en] The interaction between energetic electrons and whistler mode ELF/VLF waves measured on board GEOS 1 has been studied using a method to calculate the particle anisotropy and the wave growth rate from five-minute average electron fluxes. The results are discussed with respect to the power density of the wave field according to the theory of quasilinear diffusion in pitch angle. Conditions for the existence of a steady state emission are considered in terms of a minimum level of the integrated spatial growth rate needed to compensate for wave losses at the ionosphere. 26 references