Laboratory Investigation of Triggered Emissions

The mechanisms that control magnetospheric whistler wave generation have been investigated by ground based VLF ($3-30 \mathrm{kHz}$) wave-injection experiments such as at Siple Station and HAARP. Coherent signals were shown to routinely trigger the generation of new coherent waves known as “triggered emissions”. VLF triggered emissions are long-lived, many times the length of the triggering signal, and exhibit spectral characteristics that closely resemble natural magnetospheric chorus waves. These controlled injection experiments have produced a wealth of data, but at the same time, comparison of this dataset to theory is difficult since the ground observations are at the end of the interaction region, giving access only to cumulative effects of the wave-particle interaction.