WAVES GENERATED IN THE VICINITY OF AN ARGON PLASMA GUN IN THE IONOSPHERE

Wave and particle observations were made in the close vicinity of an a rgon plasma gun carried to over 600 km altitude on a sounding rocket. The gun was carried on a subpayload, separated from the main payload e arly in the flight. Twelve-second argon ion ejections were energized a lternately with a peak energy of 100 or 200 eV. They produced waves, w ith multiple harmonics, in the range of ion cyclotron waves, 10 to 100 0 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argo n or ambient, known to be present. In addition, the wave frequencies w ere observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of 0.1 V/m. Some of the waves may be ion-ion hybrid waves. Chan ges in ion populations were observed at the main payload and at the su bpayload during gun operations. A gun-related, field-aligned, electron population also appeared.