Parametric excitation of Alfvén waves in the ionosphere

Abstract
A novel method for the excitation of ELF waves in the ionosphere is presented. It utilizes the nonlinear mixing of two ground‐ or satellite‐produced radio frequency waves with a compressional Alfvén wave. Parametric amplification thresholds are estimated to be between 10 and 20 MW peak power for 5‐MHz pumps producing waves in the ELF range. Potential applications to ELF communications are discussed.