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.