Magnetohydrodynamic wave phenomena have been investigated in the deep plasmasphere by the electric field measurements in the EXOS-D(Akebono) satellite.EXOS-D has highly eccentric orbits(the perigee: Food Service:Commercial Kitchen Equipment:Food Preparation Equipment:Commercial Bread 274km, the apogee: 10,500km), which allows relatively long observational time interval near the apogee region compared to othe satellites which pass by the same region with less eccentric orbits.Case studies are peformed on one month data of October in 1989 where the apogee is located near the equator and the magnetic local time is about 9:00-12:00 a.m.
in the dayside plasmasphere.The observational region ranges from L=2 to L=3 and the Stick Welder (SMAW) magnetic latitude is restricted to less than 30 degress.The power spectrum is examined for each 128 point series of 8-sec averaged data through a FFT, which covers f=0-62.3 mHz frequency bands.
The results are well consistent with field line resonances(FLRs) and cavity modes in the plasmasphere.