Chris Crabtree
United States Naval Research Laboratory
"Injecting VLF Waves into the Radiation Belts to Control and Learn about the Near-Earth Space Environment"
Our modern society increasingly relies on communication, monitoring, and imaging capabilities provided by near-Earth orbiting satellites and yet the near-Earth space environment is plagued by intermittent and highly variable fluxes of relativistic electrons that can interfere with normal satellite operations. Nature regulates the flux of relativistic electrons through wave-particle interactions with Very Low Frequency (VLF) waves. Understanding the sources, sinks, and self-consistent interaction between the population of energetic electrons and VLF waves is a difficult and pressing challenge. By performing active experiments that inject VLF waves into the radiation belts, we can affect a degree of control over the energetic electrons and thus enhance our understanding of the natural plasma environment. In this talk, we describe two approaches to injecting VLF waves into the heart of the Radiation belts. The first approach involves converting kinetic energy of neutral atoms into an electromagnetic energy source in the ionosphere. An upcoming sounding rocket experiment named SMART, Space Measurement of Rocket-released Turbulence, to test this concept will be described. We will review the theoretical underpinnings of the experiment and the results of laboratory experiments performed to verify the nonlinear kinetic physics. The second approach described involves using conventional antennas to radiate small amounts of power into the radiation belts. The power radiated is too small by itself to affect the energetic electrons, but pre-existing natural phenomenon to amplify the waves may exist. Through a nonlinear mechanism that is responsible for chorus waves the waves may achieve sufficient amplitude to control the radiation belt population. Experimental and theoretical results pertaining to the nonlinear amplification phenomenon will be presented.
Host: Andrew Cole
