SPRG Seminars
October 22, 2013:
"Quantifying the Role of VLF Transmitters in Radiation Belt Losses"
Maria Spasojevic, Stanford University
Energetic electrons trapped in the Earth's radiation belts are a threat to the sensitive electronics of spacecraft. Both natural and manmade events, such as high altitude nuclear detonations, can greatly increase trapped energetic electron fluxes, motivating the search for a method of radiation belt remediation to mitigate the danger of such events. Powerful ground-based VLF transmitters exist for the purpose of long distance naval communications. Although the wave energy radiated by these transmitters is primarily confined within the waveguide formed by the Earth and the lower portion of the ionosphere, a small fraction of the wave energy can propagate upward through the ionosphere. Once in the magnetosphere, these whistler-mode waves can resonantly interact with energetic electrons resulting in pitch angle scattering and the loss of electrons through precipitation into the upper atmosphere. We discuss challenges and recent advances in understanding and quantifying the role of ground-based VLF transmitters in radiation belt losses. We also introduce the forthcoming DSX mission, which will transmit VLF waves in situ and quantify the effect of these waves on the trapped electron population.