Ion cyclotron waves generated by an ionospheric barium injection

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Abstract
A shaped charge, barium, plasma injection experiment was performed in June 1976 at the ERDA Kauai test facility. The barium was injected perpendicular to the geomagnetic field at an altitude of 450 km. The second stage of the rocket, located approximately 1.2 km from the point of detonation, contained a payload to measure dc and ac electric fields using a dual spherical probe antenna. A variety of plasma waves were detected for approximately 20 s following the detonation. The initial impulse generated ion cyclotron waves at the Ba+, O2+, Al+, OH+, and O+ gyrofrequencies. No evidence for a Doppler shift was observed. This was followed by a time period during which ion cyclotron waves were observed in passbands between the barium gyrofrequency harmonics up to the oxygen gyrofrequency. At the high‐frequency end of this range the spectrum is essentially continuous, i.e., similar to an ion sound wave spectrum.