Stimulation of ULF (Ultra-Low-Frequencies) Geomagnetic Pulsations by Controlled VLF (Very-Low-Frequencies) Transmissions into the Magnetosphere

This report presents the results of an investigation of a proposed method for the controlled artificial generation of ultra-low-frequency ULF hydromagnetic waves of class Pc 1 0.2 to 5 Hz in the ionosphere and magnetosphere. In this method, which is called the VLF method, a large ground- based very-low-frequency VLF transmitter is used to stimulate the ULF waves by injecting pulses of VLF waves into the magnetosphere. A second possible method of ULF wave generation, the peninsula method, is discussed in a companion report. Combining the theoretical and experimental results obtained during this research, it is suggested that naturally-occurring repetitive VLF activity can stimulate Pc 1 pulsation events, and it is further suggested that such VLF activity may be a major source of stimulation for Pc 1 pulsations. Thus, future experiments on ULF wave generation with ground-based VLF transmitters would probably benefit greatly if they were combined with a program of simultaneous observations of naturally-occurring VLF and ULF activity.