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Direct observation of radiation belt electrons precipitated by the controlled injection of VLF signals from a ground‐based transmitter
Author(s) -
Imhof W. L.,
Reagan J. B.,
Voss H. D.,
Gaines E. E.,
Datlowe D. W.,
Mobilia J.,
Helliwell R. A.,
Inan U. S.,
Katsufrakis J.,
Joiner R. G.
Publication year - 1983
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl010i004p00361
Subject(s) - van allen radiation belt , electron precipitation , physics , electron , transmitter , cyclotron , van allen probes , ionosphere , satellite , geophysics , magnetosphere , nuclear physics , electrical engineering , astronomy , plasma , channel (broadcasting) , engineering
Radiation belt electrons precipitated by controlled injection of VLF signals from a ground based transmitter have been directly observed for the first time. These observations were part of the SEEP (Stimulated Emission of Energetic Particles) experiment conducted during May ‐ December 1982. Key elements of SEEP were the controlled modulation of VLF transmitters and a sensitive low altitude satellite payload to detect the precipitation. An outstanding example of time‐correlated wave and particle data occurred from 8680 to 8740 seconds U.T. on 17 August 1982 when the satellite passed near the VLF transmitter at Cutler, Maine (NAA) as it was being modulated with a repeated ON (3‐s)/OFF (2‐s) pattern. During each of twelve consecutive pulses from the transmitter the electron counting rate increased significantly after start of the ON period and reached a maximum about 2 seconds later. The measured energy spectra revealed that approximately 15 to 50 percent of the enhanced electron flux was concentrated near the resonant energies for first order cyclotron interactions occurring close to the magnetic equator with the nearly monochromatic waves emitted from the transmitter.