Preliminary report on detection of electrostatic ion waves in the magnetosphere

The Lockheed-Aerospace P11 satellite (1964-45A) launched into a polar eccentric orbit on August 15, 1964, included in its payload a VLF electric field experiment supplied by TRW Space Technology Laboratories. Measurements in the frequency range 1.7 to 14.5 kc/s reveal that the indicated background rarely falls below 10−3 volt/m and that sustained field enhancements with E ≃ 20–100 mv/m are generally detected in regions where energetic electrons are precipitated from the Van Allen belts. The experiment is described; some early results are presented; and an interpretation in terms of electrostatic ion waves is given. The possibility that large-amplitude ion waves cause diffusion across L shells and magnetospheric electron acceleration is also discussed.